The Chemistry of the Actinide and Transactinide Elements (5 Volume Set) (v. 1-5)

THE CHEMISTRY OF THE

ACTINIDE AND TRANSACTINIDE ELEMENTS

Joseph J. Katz

Glenn T. Seaborg

This work is dedicated to Joseph J. Katz and Glenn T. Seaborg, authors of the first and second editions of The Chemistry of the Actinide Elements and leaders in the field of actinide chemistry.

THE CHEMISTRY OF THE

ACTINIDE AND TRANSACTINIDE ELEMENTS THIRD EDITION

Volume 1 EDITED BY Lester R. Morss Argonne National Laboratory, Argonne, Illinois, USA

Norman M. Edelstein Lawrence Berkeley National Laboratory, Berkeley, California, USA

Jean Fuger University of Lie`ge, Lie`ge, Belgium

Honorary Editor Joseph J. Katz Argonne National Laboratory

Library of Congress Control Number: 2008922620

ISBN-10 1-4020-3555-1 (HB) ISBN-10 1-4020-3598-5 (e-book) ISBN-13 978-1-4020-3555-5 (HB) ISBN-13 978-1-4020-3598-2 (e-book)

Published by Springer, P.O. Box 17, 3300 AA Dordrecht, The Netherlands.

www.springer.com

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All Rights Reserved First published in 2006 Reprinted 2006 Reprinted with corrections in 2008 # 2006 and 2008 Springer Science + Business Media B.V. No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work.

CONTENTS Volume 1 ix xv

Contributors Preface 1. Introduction Joseph J. Katz, Lester R. Morss, Norman M. Edelstein, and Jean Fuger 2. Actinium H. W. Kirby and L. R. Morss 3. Thorium Mathias S. Wickleder, Blandine Fourest, and Peter K. Dorhout 4. Protactinium Boris F. Myasoedov, H. W. Kirby, and Ivan G. Tananaev 5. Uranium Ingmar Grenthe, Janusz Droz˙dz˙yn´ski, Takeo Fujino, Edgar C. Buck, Thomas E. Albrecht-Schmitt, and Stephen F. Wolf Subject Index (Volume 1) Author Index (Volume 1)

1

18 52 161 253

I-1 I-31

Volume 2 ix xv

Contributors Preface 6. Neptunium Zenko Yoshida, Stephen G. Johnson, Takaumi Kimura, and John R. Krsul 7. Plutonium David L. Clark, Siegfried S. Hecker, Gordon D. Jarvinen, and Mary P. Neu 8. Americium Wolfgang H. Runde and Wallace W. Schulz Subject Index (Volume 2) Author Index (Volume 2)

699

813

1265

I-1 I-27 v

vi

Contents

Volume 3 Contributors Preface

ix xv

9. Curium 1397 Gregg J. Lumetta, Major C. Thompson, Robert A. Penneman, and P. Gary Eller 10. Berkelium 1444 David E. Hobart and Joseph R. Peterson 11. Californium 1499 Richard G. Haire 12. Einsteinium 1577 Richard G. Haire 13. Fermium, Mendelevium, Nobelium, and Lawrencium 1621 Robert J. Silva 14. Transactinide Elements and Future Elements 1652 Darleane C. Hoffman, Diana M. Lee, and Valeria Pershina 15. Summary and Comparison of Properties of the Actinide and Transactinide Elements 1753 Norman M. Edelstein, Jean Fuger, Joseph J. Katz, and Lester R. Morss 16. Spectra and Electronic Structures of Free Actinide Atoms and Ions 1836 Earl F. Worden, Jean Blaise, Mark Fred, Norbert Trautmann, and Jean-Franc¸ois Wyart 17. Theoretical Studies of the Electronic Structure of Compounds of the Actinide Elements 1893 Nikolas Kaltsoyannis, P. Jeffrey Hay, Jun Li, Jean-Philippe Blaudeau, and Bruce E. Bursten 18. Optical Spectra and Electronic Structure 2013 Guokui Liu and James V. Beitz Subject Index (Volume 3) Author Index (Volume 3)

I-1 I-39

Volume 4 Contributors Preface 19. Thermodynamic Properties of Actinides and Actinide Compounds Rudy J. M. Konings, Lester R. Morss, and Jean Fuger 20. Magnetic Properties Norman M. Edelstein and Gerard H. Lander

ix xv 2113 2225

Contents

vii

21. 5f-Electron Phenomena in the Metallic State A. J. Arko, John J. Joyce, and Ladia Havela 22. Actinide Structural Chemistry Keith E. Gutowski, Nicholas J. Bridges, and Robin D. Rogers 23. Actinides in Solution: Complexation and Kinetics Gregory R. Choppin and Mark P. Jensen 24. Actinide Separation Science and Technology Kenneth L. Nash, Charles Madic, Jagdish N. Mathur, and Je´roˆme Lacquement

2307

Subject Index (Volume 4) Author Index (Volume 4)

I-1 I-35

2380 2524 2622

Volume 5 Contributors Preface 25. Organoactinide Chemistry: Synthesis and Characterization Carol J. Burns and Moris S. Eisen 26. Homogeneous and Heterogeneous Catalytic Processes Promoted by Organoactinides Carol J. Burns and Moris S. Eisen 27. Identification and Speciation of Actinides in the Environment Claude Degueldre 28. X-ray Absorption Spectroscopy of the Actinides Mark R. Antonio and Lynda Soderholm 29. Handling, Storage, and Disposition of Plutonium and Uranium John M. Haschke and Jerry L. Stakebake 30. Trace Analysis of Actinides in Geological, Environmental, and Biological Matrices Stephen F. Wolf 31. Actinides in Animals and Man Patricia W. Durbin

ix xv 2799

2911 3013 3086 3199

3273 3339

Appendix I Nuclear Spins and Moments of the Actinides Irshad Ahmad

3441

Appendix II Nuclear Properties of Actinide and Transactinide Nuclides Irshad Ahmad

3442

Cumulative Subject Index (Volumes 1, 2, 3, 4 and 5) Cumulative Author Index (Volumes 1, 2, 3, 4 and 5)

I-1 I-141

CONTRIBUTORS Irshad Ahmad Argonne National Laboratory, USA Thomas E. Albrecht-Schmitt Auburn University, Alabama, USA Mark R. Antonio Argonne National Laboratory, USA A. J. Arko Los Alamos National Laboratory, USA (retired) James V. Beitz Argonne National Laboratory, USA (retired) Jean Blaise Laboratoire Aime´ Cotton, Orsay, France Jean-Philippe Blaudeau High Performance Technologies, Inc., Wright-Patterson Air Force Base, Ohio, USA Nicholas J. Bridges The University of Alabama, USA Edgar C. Buck Pacific Northwest National Laboratory, Richland, Washington, USA Carol J. Burns Los Alamos National Laboratory, USA Bruce E. Bursten The University of Tennessee, USA Gregory R. Choppin Florida State University, USA David L. Clark Los Alamos National Laboratory, USA

ix

x

Contributors

Claude Degueldre Paul Scherrer Institute, Switzerland Peter K. Dorhout Colorado State University, USA Janusz Droz˙dz˙yn´ski University of Wroclaw, Poland Patricia W. Durbin Lawrence Berkeley National Laboratory, USA Norman M. Edelstein Lawrence Berkeley National Laboratory, USA Moris S. Eisen Technion -Israel Institute of Technology, Israel P. Gary Eller Los Alamos National Laboratory, USA (retired) Mark Fred Argonne National Laboratory, USA (deceased) Blandine Fourest Institut de Physique Nucle´aire, Orsay, France Jean Fuger University of Lie`ge, Belgium Takeo Fujino Tohoku University, Japan (retired) Ingmar Grenthe Royal Institute of Technology, Stockholm, Sweden Keith E. Gutowski The University of Alabama, USA Richard G. Haire Oak Ridge National Laboratory, USA John M. Haschke Actinide Science Consulting, Harwood, TX, USA

Contributors Ladia Havela Charles University, Czech Republic P. Jeffrey Hay Los Alamos National Laboratory, USA Siegfried S. Hecker Los Alamos National Laboratory, USA David E. Hobart Los Alamos National Laboratory, USA Darleane C. Hoffman Lawrence Berkeley National Laboratory, USA Gordon D. Jarvinen Los Alamos National Laboratory, USA Mark P. Jensen Argonne National Laboratory, USA Stephen G. Johnson Idaho National Laboratory, USA John J. Joyce Los Alamos National Laboratory, USA Nikolas Kaltsoyannis University College London, UK Joseph J. Katz Argonne National Laboratory, USA (retired) Takaumi Kimura Japan Atomic Energy Agency, Japan Harold W. Kirby (deceased) Mound Laboratory, Miamisburg, Ohio, USA Rudy J. M. Konings European Commission, Joint Research Centre Institute for Transuranium Elements, Karlsruhe, Germany John R. Krsul Argonne National Laboratory, USA (retired)

xi

xii

Contributors

Je´roˆme Lacquement CEA-Valrho, Marcoule, France Gerard H. Lander European Commission, Joint Research Centre Institute for Transuranium Elements, Karlsruhe, Germany Diana M. Lee Lawrence Berkeley National Laboratory, USA Jun Li Pacific Northwest National Laboratory, Richland, Washington, USA Guokui Liu Argonne National Laboratory, USA Gregg J. Lumetta Pacific Northwest National Laboratory, Richland, Washington, USA Charles Madic CEA-Saclay, Gif-sur-Yvette, France Jagdish N. Mathur Bhabha Atomic Research Centre, Mumbai, India Lester R. Morss Argonne National Laboratory (retired) and U.S. Department of Energy, Washington DC, USA Boris F. Myasoedov Russian Academy of Sciences, Moscow, Russia Kenneth L. Nash Washington State University, USA Mary P. Neu Los Alamos National Laboratory, USA Robert A. Penneman Los Alamos National Laboratory, USA (retired) Valeria Pershina Gesellschaft fu¨r Schwerionenforschung, Darmstadt, Germany

Contributors Joseph R. Peterson The University of Tennessee, USA and Oak Ridge National Laboratory, USA (retired) Robin D. Rogers The University of Alabama, USA Wolfgang Runde Los Alamos National Laboratory, USA Wallace W. Schulz Albuquerque, New Mexico, USA Robert J. Silva Lawrence Livermore National Laboratory, USA (retired) Lynda Soderholm Argonne National Laboratory, USA Jerry L. Stakebake Boulder, Colorado, USA Ivan G. Tananaev Russian Academy of Sciences, Moscow, Russia Major C. Thompson Savannah River National Laboratory, USA (retired) Norbert Trautmann Universita¨t Mainz, Germany Mathias S. Wickleder Carl von Ossietzky Universita¨t, Oldenburg, Germany Stephen F. Wolf Indiana State University, Terre Haute, Indiana, USA Earl F. Worden, Jr. Lawrence Livermore National Laboratory, USA (retired) Jean-Franc¸ois Wyart Laboratoire Aime´ Cotton, Orsay, France Zenko Yoshida Japan Atomic Energy Agency, Japan

xiii

PREFACE The first edition of this work (The Chemistry of the Actinide Elements by J. J. Katz and G. T. Seaborg) was published in 1957, nearly a half century ago. Although the chemical properties of thorium and uranium had been studied for over a century, and those of actinium and protactinium for over fifty years, all of the chemical properties of neptunium and heavier elements as well as a great deal of uranium chemistry had been discovered since 1940. In fact, the concept that these elements were members of an “actinide” series was first enunciated in 1944. In this book of 500 pages the chemical properties of the first transuranium elements (neptunium, plutonium, and americium) were described in great detail but the last two actinide elements (nobelium and lawrencium) remained to be discovered. It is not an exaggeration to say that The Chemistry of the Actinide Elements expounded a relatively new branch of chemistry. The second edition was published in 1986, by which time all of the actinide elements had been synthesized and chemically characterized, at least to some extent. At this time the chemistry of the actinide elements had reached maturity. The second edition filled two volumes, with a chapter for each of the elements (the elements beyond einsteinium were combined in one chapter) and systematic treatment of various aspects of the chemical and electronic properties of the actinide elements, ions, and compounds due to the filling of the 5f subshell. Six transactinide elements had been synthesized by 1986 but their experimentally determined chemical properties occupied only 1.5 pages of text in the second edition. This edition was initiated by the editors of the second edition (J. J. Katz, G. T. Seaborg, and L. R. Morss) in 1997. They realized that the study of the chemical properties of the actinide elements had advanced to produce distinct subdisciplines of actinide chemistry, for example actinide coordination chemistry, actinide X-ray absorption spectroscopy, itinerancy in actinide intermetallics, organoactinide chemistry, and actinide environmental chemistry. These fields had sufficiently matured so that scientists could make more substantial contributions to predicting and controlling the fate of actinides in the laboratory, in technology, and in the environment. We now understand and are able to predict with some degree of confidence the chemical bonding and reactivity of actinides in actinide materials, in actual environmental matrices and in proposed nuclear waste repositories. Most of the unique properties of the actinides are caused by their accessible and partly filled 5f orbitals. In addition to advances with the actinides, there have been research groups at nuclear research centers in several countries that have dedicated themselves to carry out significant and systematic experimental studies on the transactinide elements for several decades. For these reasons the editors initiated the writing of a third edition, with the xv

xvi

Preface

enlarged title The Chemistry of the Actinide and Transactinide Elements that is both broader and deeper than the second edition. The third edition follows the plan enunciated by the authors of the first edition: “This book is intended to provide a comprehensive and uniform treatment of the chemistry of the actinide [and transactinide] elements for both the nuclear technologist and the inorganic and physical chemist.” To fulfill this plan consistent with the maturity of the field, the third edition is organized in three parts. The first group of chapters follows the format of the first and second editions by beginning with chapters on individual elements or groups of elements that describe and interpret their chemical properties. A chapter on the chemical properties of the transactinide elements is included. The second group, chapters 15-26, summarizes and correlates physical and chemical properties that are in general unique to the actinide elements, because most of these elements contain partially-filled shells of 5f electrons whether present as isolated atoms or ions, as metals, as compounds, or as ions in solution. The third group of chapters (chapters 27-31) focuses on specialized topics that encompass contemporary fields related to actinide species in the environment, in the human body, and in storage or wastes. There are also two appendices that tabulate important nuclear properties of all actinide and transactinide isotopes. Each chapter has been written to provide sufficient background for the substantial parts of the readership that are not specialists in actinide science, nuclear-science-related areas (nuclear physics, health physics, nuclear engineering), spectroscopy, or solid-state science (metallurgy, solid state physics). The editors hope that this work educates and informs those readers who are scientists and engineers that are unfamiliar with the field and wish to learn how to deal with actinides in their research or technology. The editors are deeply indebted to the contributors of each chapter, all of whom agreed enthusiastically to write their chapters and all of whom did so as a labor of love as well as a long-term professional responsibility. We take special pleasure in thanking Dr. Emma Roberts, Senior Publishing Editor of Springer, who provided the resources to turn more than thirty manuscripts into this attractive and useful professional series of volumes. We also thank Roger Wayman and Aaliya Jetha of Springer and all the other professional staff at Springer and SPI Publisher Services who brought this work to completion. The editors dedicate this work to Joseph J. Katz and Glenn T. Seaborg, the first authors of the first edition and second editions of The Chemistry of the Actinide Elements. They provided inspiration for the generations of scientists who followed them and they set high standards in their research. Dr. Katz guided and motivated the editors and authors of the third edition to produce a work that followed the model of the first and second editions and provided leadership as this edition was unfolding. Because of his insights and leadership as an inorganic, physical, and actinide chemist, we have asked Dr. Katz to be

Preface

xvii

listed on the title page as honorary editor, and he has agreed to accept this role. The editors also dedicate this work to the memory of Professor Seaborg, the codiscover of plutonium and many other actinide and transactinide elements, and pioneer in actinide chemistry. We note with sadness that he participated in planning this edition but passed away before any of the chapters had been written. We believe that he would have been pleased to see how productive has been the research of the authors and many other actinide and transactinide scientists who follow his leadership. All of us who have participated in the writing, editing, and publishing The Chemistry of the Actinide and Transactinide Elements express our hope that this new edition will make a substantive contribution to research in actinide and transactinide science, and that it will be an appropriate source of factual information on these elements for teachers, researchers, and students and for those who have the responsibility for utilizing the actinide elements to serve humankind and to control and mitigate their environmental hazards. Lester R. Morss Norman M. Edelstein Jean Fuger

CHAPTER ONE

INTRODUCTION Joseph J. Katz, Lester R. Morss, Norman M. Edelstein, and Jean Fuger References

15

Additional suggested readings

15

The actinide elements are the 15 chemical elements with atomic numbers 89 through 103, the first member of which is actinium and the last member is lawrencium (Fig. 1.1). The transactinide elements (those beyond the actinides) are the heaviest known chemical elements. Both the actinide and the transactinide elements have chemical properties that are governed by their outermost electronic subshells. Each of these groups of elements is a unique transition series (a group of elements in which d or f electronic subshells are being filled). The actinides are the transition elements that fill the 5f subshell. The actinide series is unique in several respects:
Most of the elements (those heavier than uranium) were first discovered by










synthetic methods: bombardment of heavy atoms with neutrons in nuclear reactors, bombardment with other particles in accelerators, or as the result of nuclear detonations. All actinide isotopes are radioactive, with a wide range of nuclear properties, especially that of spontaneous and induced nuclear fission. They are all metals with very large radii, and exist in chemical compounds and in solution as cations with very large ionic radii. The metals exhibit an unusual range of physical properties. Plutonium, with six allotropes, is the most unusual of all metals. Many of the actinide elements have a large number of oxidation states. In this respect plutonium is unique, being able to exist in aqueous solution simultaneously in four oxidation states. In metallic materials and in some other compounds with elements lighter than plutonium, the 5f orbitals are sufficiently diffuse that the electrons in these orbitals are ‘‘itinerant” (delocalized, chemically bonding, often with unique magnetic moments and electrical conductivity). In metallic materials and in most compounds with elements heavier than plutonium the 5f electrons are ‘‘localized” (not contributing significantly to electrical conductivity or to chemical bonds). Materials with plutonium and adjacent

1

2

Introduction elements can exhibit both itinerant and localized behavior, depending on conditions such as temperature and applied pressure.
Actinium (which has no 5f electrons in the metal, free atom, or in any of its ions) and the elements americium through lawrencium are similar in many respects to the lanthanide elements (the elements that fill the 4f electron subshell). The elements thorium through neptunium have some properties similar to those of the d transition elements.
Relativistic contributions to electronic properties and spin–orbit effects are important in the chemical properties of actinides.

The transactinide elements are at the frontier of both the periodic table (Fig. 1.1) and the chart of the nuclides. Transactinide chemistry has been in existence since 1970. Although these elements have unique properties, they are very difficult to study because their synthesis and identification require unique nuclear reactions and rapid separations. The heaviest transactinide element for which chemical properties have been identified (at the time of writing of this work) is hassium (atomic number 108). Experimental evidence and theoretical studies to date indicate that the elements through 112 are part of a 6d transition series of elements.

Fig. 1.1 The periodic table of the elements, showing placement of transactinides and superactinides through element 154 (see Chapter 14). (Italics indicate elements reported but not yet confirmed as of 2005. Undiscovered elements are shown in parentheses.)

Introduction

3

The transactinides are also unique in several respects:
One-atom-at-a-time chemistry is required to compensate for low nuclear

yields and short isotopic half-lives. Ingenious techniques have been developed to study their chemical properties in both gas phase and solution.
Relativistic effects cause substantial contraction of the 7s (occupied), 7p (empty), and 6d (partially filled) orbitals. (Many electronic configurations have been calculated; see Chapter 14.) The contraction of the 7s orbitals stabilizes the 7s2 electron pair. The contraction of the 7p orbitals makes 7p terms accessible, e.g., the first excited multiplet of rutherfordium (element 104) outside the [Xe 5f14] core is calculated to be 6d7s27p.
The first part of the transactinides constitutes a 6d transition series, with the calculated ionic radii intermediate between those of the 5d ions and actinide ions of the same charge. Relativistic effects decrease the polarizability of transactinide ions.
Fundamental properties – electronic configurations, ionization energies of atoms and ions, oxidation–reduction potentials in solution – remain to be calculated theoretically and measured experimentally. In the six decades that have elapsed since the ‘‘actinide concept” was enunciated by G. T. Seaborg, great advances have taken place in actinide and transactinide chemistry. As in many other important areas of science, new information and new concepts have accumulated to an extraordinary extent. This, in itself, would be ample justification for a comprehensive examination of the scientific aspects of the actinide elements. Of equal, or perhaps even greater, importance in the preparation of this third edition are the contributions that its many authors have made to provide the foundations for the solution of some of the most urgent technological and environmental problems that face humanity worldwide. We refer, of course, to the problems created by nuclear reactors used for electricity production; nuclear weapons production and dismantlement; the treatment and storage of nuclear wastes; and the cleanup of Cold War nuclear material sites. These are sources of acute global concern, in all of which the actinide elements are intimately involved. In 1957, when the first edition of this work was published, the chemistry of the actinide elements was remarkably well developed, considering that the actinide concept itself had first been publicly described in 1945. (See Chapter 15, section 1.2, of this book) The elements thorium and uranium had already been studied by chemists for more than 100 years. Uranium enjoyed some small distinction as the heaviest element in nature, and as the terminus of the classical periodic table. In 1895 Becquerel had discovered that uranium undergoes radioactive decay, a discovery that permanently divested uranium of its obscurity, and that inaugurated the era of the Curies, Rutherford, Soddy, Hahn and Meitner, Fajans, and others who mapped the very complex radioactive transformations of the naturally occurring elements. The crucial importance of uranium, however, became fully apparent only after Fermi and his colleagues irradiated many of the

Introduction

4

elements, including uranium, with neutrons in the 1930s. They produced new radioactive species with chemical properties that were not identical with any of the known heavy elements. The Fermi group believed that they had created new elements heavier than uranium. In 1938 Hahn, Meitner, and Strassmann conducted definitive chemical experiments showing that the radioactive species produced by neutron irradiation of uranium were in fact fission fragments resulting from the cleavage of the uranium nucleus into smaller nuclei. Their experiments constituted the discovery of nuclear fission. The earlier formation of transuranium elements had been disproved, but the way to their synthesis was now open. The first transuranium element, neptunium, was nevertheless the by-product of an investigation by McMillan and Abelson into the details of the fission process. While fission fragments recoil with enormous energy from a uranium nucleus undergoing fission, a radioactive species with a half-life of 2.3 days was observed to be formed with insufficient energy to escape from a thin film of irradiated uranium. Chemical investigation confirmed that a new element, neptunium, unknown in nature, with atomic number 93 and mass number 239, had been formed by neutron capture in 238U. 238 1 92 Uþ0 n

b

! 239 92 U !

23:5 min

239 93 Np

ðt1=2 ¼ 2:36 daysÞ

ð1:1Þ

The new prospects opened up by the discovery of the first transuranium element were rapidly explored, and soon the trickle became a flood. Table 1.1 lists the transuranium elements, the discoverers and the date of discovery, and the date of first isolation in weighable amount. The first of the transuranium elements to be synthesized on purpose, so to speak, was element 94 as the isotope of mass number 238. In 1940, Seaborg, McMillan, Kennedy, and Wahl at the University of California in Berkeley bombarded uranium oxide with 16 MeV deuterons produced in the 60 in. cyclotron and succeeded in isolating a long-lived alpha-particle emitter, chemically separable from both uranium and neptunium, which was identified as an isotope of element 94 and later given the name plutonium: 238 92 U

1 þ 21 H ! 238 93 Np þ 20 n

b 238 238 93 Np ! 94 Pu 2:1d

ðt1=2 ¼ 87:7 yearsÞ

ð1:2Þ ð1:3Þ

Twenty isotopes of plutonium are now known. The plutonium isotope of major importance has always been the isotope of mass number 239. Research with 239Pu has been strongly motivated by the fact that it was shown to be fissile by slow neutrons in the same way as 235U, and would thus be able to sustain a neutron chain reaction. The isotope 239Pu can thus be used for both military and nuclear energy purposes. To separate 235U from 238U requires an isotope separation of

Plutonium

94

Americium

Curium

Berkelium

Californium

Einsteinium

Fermium

Mendelevium

Nobelium

95

96

97

98

99

100

101

102

Plutonium-239

Neptunium

Element

93

Atomic number

No

Md

Fm

Es

Cf

Bk

Cm

Am

Pu

Np

Symbol

G. T. Seaborg, E. M. McMillan, J. W. Kennedy, and A. C. Wahl, 1940–41 J. W. Kennedy, G. T. Seaborg, E. Segre`, and A. C. Wahl, 1941 G. T. Seaborg, R. A. James, L. O. Morgan, and A. Ghiorso, 1944–45 G. T. Seaborg, R. A. James, and A. Ghiorso, 1944 S. G. Thompson, A. Ghiorso, and G. T. Seaborg, 1949 S. G. Thompson, K. Street, Jr, A. Ghiorso, and G. T. Seaborg, 1950 A. Ghiorso, S. G. Thompson, G. H. Higgins, G. T. Seaborg, M. H. Studier, P. R. Fields, S. M. Fried, H. Diamond, J. F. Mech, G. L. Pyle, J. R. Huizenga, A. Hirsch, W. M. Manning, C. I. Browne, H. L. Smith, and R. W. Spence, 1952 A. Ghiorso, S. G. Thompson, G. H. Higgins, G. T. Seaborg, M. H. Studier, P. R. Fields, S. M. Fried, H. Diamond, J. F. Mech, G. L. Pyle, J. R. Huizenga, A. Hirsch, W. M. Manning, C. I. Browne, H. L. Smith, and R. W. Spence, 1953 A. Ghiorso, B. G. Harvey, G. R. Choppin, S. G. Thompson, and G. T. Seaborg, 1955 A. Ghiorso, T. Sikkeland, J. R. Walton, and G. T. Seaborg, 1958

E. M. McMillan and P. H. Abelson, 1940

Discoverers and date of discovery

Table 1.1 The transuranium elements.

L. B. Werner and I. Perlman, 1947 S. G. Thompson and B. B. Cunningham, 1958 B. B. Cunningham and S. G. Thompson, 1958 B. B. Cunningham, J. C. Wallmann, L. Phillips, and R. C. Gatti, 1961

B. B. Cunningham and L. B. Werner, 1942 B. B. Cunningham, 1945

L. B. Magnusson and T. J. LaChapelle, 1944

First isolation in weighable amount

Element

Lawrencium

Rutherfordium

Dubnium

Seaborgium

Bohrium

Hassium

Meitnerium

Darmstadtium

Atomic number

103

104

105

106

107

108

109

110

Ds

Mt

Hs

Bh

Sg

Db

Rf

Lr

Symbol A. Ghiorso, T. Sikkeland, A. E. Larsh, and R. M. Latimer, 1961 A. Ghiorso, M. Nurmia, J. Harris, K. Eskola, and P. Eskola, 1969; Y. T. Oganessian, Y. V. Lobanov, S. P. Tretyakova, Y. A. Lasarev, I. V. Kolesov, K.A. Gavrilov, V. M. Plotko, and Y. V. Poluboyarinov, 1974 A. Ghiorso, M. Nurmia, K. Eskola, J. Harris, and P. Eskola, 1970; G. N. Flerov, Y.T. Oganessian, Y.V. Lobanov, Y. A. Lasarev, and S. P. Tretyakova, 1970 A. Ghiorso, J. M. Nitschke, J. R. Alonso, C. T. Alonso, M. Nurmia, G. T. Seaborg, E. K. Hulet, and R. W. Lougheed, 1974 G. Mu¨nzenberg, S. Hofmann, F. P. Hessberger, W. Reisdorf, K. H. Schmidt, J. H. R. Schneider, P. Armbruster, C. C. Sahm, and B. Thuma, 1981 G. Mu¨nzenberg, P. Armbruster, H. Folger, F. P. Hessberger, S. Hofmann, J. Keller, K. Poppensieker, W. Reisdorf, K. H. Schmidt, H. J. Schott, M. E. Leino, and R. Hingmann, 1984 G. Mu¨nzenberg, P. Armbruster, F. P. Hessberger, S. Hofmann, K. Poppensieker, W. Reisdorf, J. R. H. Schneider, W. F. W. Schneider, K. H. Schmidt, C. C. Sahm, and D. Vermeulen, 1982 S. Hofmann, V. Ninov, F. P. Hessberger, P. Armbruster, H. Folger, G. Mu¨nzenberg, H. J. Scho¨tt, A. G. Popeko, A. V. Yeremin, A. N. Andreyev, S. Saro, R. Janik, and M. Leino, 1995

Discoverers and date of discovery

Table 1.1 (Contd.) First isolation in weighable amount

a

Roentgenium

Rg

S. Hofmann, V. Ninov, F. P. Hessberger, P. Armbruster, H. Folger, G. Mu¨nzenberg, H. J. Scho¨tt, A. G. Popeko, A. V. Yeremin, A. N. Andreyev, S. Saro, R. Janik, and M. Leino, 1995 S. Hofmann, F. P. Hessberger, D. Ackermann, G. Mu¨nzenberg, S. Antalic, P. Cagarda, B. Kindler, J. Kojouharova, M. Leino, B. Lonnel, R. Mann, A. G. Popeko, S. Reshitko, S. Saro, J. Uusitalo, and V. Yeremin, 2002a Same as element 115a Yu. Ts. Oganessian, V. K. Utyonkov, Yu. V. Lobanov, F. Sh. Abdullin, A. N. Polyakov, I. V. Shirokovsky, Yu. Ts. Tsyganov, G. G. Gulbekian, S. L. Bogomolov, B. N. Gikal, A. N. Metsentsev, S. Iliev, V. G. Subbotin, A. M. Sukhov, O. V. Ivanov, G. V. Buklanov, K. Subotic, M. G. Itkis, K. J. Moody, J. F. Wild, N. J. Stoyer, M. A. Stoyer, and R. W. Lougheed, 2000a Yu. Ts. Oganessian, V. K. Utyonkov, Yu. V. Lobanov, F. Sh. Abdullin, A. N. Polyakov, I. V. Shirokovsky, Yu. Ts. Tsyganov, G. G. Gulbekian, S. L. Bogomolov, A. N. Metsentsev, S. Iliev, V. G. Subbotin, A. M. Sukhov, A. A. Voinov, G. V. Buklanov, K. Subotic, V. I. Zagrebaev, M. G. Itkis, J. J. Patin, K. J. Moody, J. F. Wild, M. A. Stoyer, N. J. Stoyer, D. A. Shaughnessy, J. M. Kenneally, and R. W. Lougheed, 2004a Yu. Ts. Oganessian, V. K. Utyonkov, Yu. V. Lobanov, F. Sh. Abdullin, A. N. Polyakov, I. V. Shirokovsky, Yu. Ts. Tsyganov, G. G. Gulbekian, S. L. Bogomolov, B. N. Gikal, A. N. Metsentsev, S. Iliev, V. G. Subbotin, A. M. Sukhov, O. V. Ivanov, G. V. Buklanov, K. Subotic, M. G. Itkis, K. J. Moody, J. F. Wild, N. J. Stoyer, M. A. Stoyer, R. W. Lougheed, C. A. Laue, Ye. A. Karelin, and A. N. Tatarinov, 2000a

Discovery claimed and published but not confirmed by IUPAC/IUPAP.

116

115

113 114

112

111

Introduction

8

formidable proportions, but separating 239Pu in pure form requires only a chemical separation from other elements, likewise an intimidating problem, but one that is in principle a considerably simpler undertaking. In 1941, Kennedy, Seaborg, Segre´, and Wahl successfully obtained 239Pu by radioactive decay from 239Np, which was first produced by irradiating natural 238 U with cyclotron-generated neutrons: 238 92 U

239 92 U

b

!

23:5 min

239 93 Np

þ 10 n ! 239 92 U þ
b

!

2:36 days

239 94 Pu

ðt1=2 ¼ 24 110 yearsÞ

ð1:4Þ ð1:5Þ

The isotope plutonium-239 indeed turned out to be fissionable, with a slow neutron cross section 1.7 times that of uranium-235. Later work at the wartime Los Alamos Laboratory established conclusively that sufficient neutrons were emitted in the act of fission to sustain a nuclear chain reaction. The exigencies of World War II soon made available the massive resources necessary to convert the scientific possibilities of the transuranium elements into actuality, and the nuclear age was truly upon us. Seaborg (1982, 1992) has given a vivid eyewitness account of the discovery and early experiments with plutonium. This chronicle describes in unusual detail the problems that confronted the investigators in this strange and intimidating new field of research, and how they were solved. Twelve transplutonium elements were added to the periodic table in the 30 years between 1944 and 1974. The syntheses of the elements with atomic number 95 through 106 required the development of new and ingenious experimental techniques as well as new conceptual frameworks, and these were elaborated with remarkable speed. Elements 95 and 96, named americium and curium, respectively, were first prepared in 1944 by bombardment of 239Pu; curium was synthesized by irradiation of plutonium with helium ions (alpha particles), and soon thereafter americium was synthesized by multiple neutron capture in plutonium in a nuclear reactor. As was the case for neptunium and plutonium, chemical identification was essential; it was not until these elements were predicted to be part of an actinide (5f ) transition series with þ3 oxidation states that they were isolated and identified. By 1946 the chemical properties of americium and curium were already well defined, and by 1949 sufficient amounts of americium241 and curium-242 had been accumulated to make it possible to undertake a search for the next members of the actinide series. Bombardment of elements 95 and 96 by helium ions accelerated in the 60 in. Berkeley cyclotron produced alpha-particle-emitting species that could be identified as isotopes of elements 97 and 98. These in turn were named berkelium and californium after their place of discovery. Again, prediction of their behavior as þ3 ions in aqueous solution was essential. During this same period of time, magnetic and spectroscopic evidence confirmed that the transuranium elements were indeed members of a 5f series of elements; see the review by Gruen (1992).

Introduction

9

The detonation of a thermonuclear device is capable of producing enormously high fluxes of neutrons. The first test thermonuclear explosion was set off at Eniwetok Atoll by the United States at the end of 1952. The huge numbers of neutrons produced by the explosion resulted in multineutron captures in the uranium-238 that was a part of the device. The capture of no fewer than 15 neutrons by a 238U nucleus yielded an isotope of element 98: 238 92 U

multiple b decays

253 þ 1510 n ! 253 92 U ! 98 Cf

ð1:6Þ

Capture of the 15 neutrons must have been accomplished in a fraction of a microsecond, and the subsequent radioactive decay of uranium-253 via a series of beta-particle emissions to form californium-253 must have been completed in a short time. Californium-253 then undergoes decay by beta-particle emission (with a half-life of 17.8 days) to form einsteinium-253. Close examination of the debris from the nuclear explosion revealed another alpha-particleemitting radioactive species that was identified as an isotope of element 100 with the mass number 255. The new elements were named einsteinium and fermium in honor of two of the most important progenitors of the nuclear age. The unexpected consequences of the vast numbers of neutrons released by the nuclear chain reaction thus led to the synthesis of two new elements and revealed the potential utility of high-flux nuclear reactors in the production of transplutonium elements. Following the earlier use of other reactors in the 1950s, the High-Flux Isotope Reactor (HFIR) and the transuranium processing facility, currently named Radiochemical Engineering Development Center (REDC) were built at Oak Ridge National Laboratory in the 1960s for the production of transcurium elements. The HFIR starting material is highly irradiated plutonium-239 already containing substantial amounts of heavier isotopes of plutonium. Prolonged exposure to the intense neutron flux of HFIR produces considerable amounts of plutonium-242, americium-243, and curium-244, which have been isolated and refabricated into new targets for irradiation in the HFIR. Work-up of these targets, a task of no mean proportions because of the intense radioactivity from fission products and the newly formed transcurium elements, yields heavy isotopes of curium, berkelium, and californium plus smaller quantities of einsteinium and fermium. The discovery of elements 99 and 100 in a sense was a watershed in the search for elements of ever higher atomic number. The experimental methods developed to isolate and identify neptunium and plutonium, refined and elaborated, were adequate for the task of isolation and characterization of the transplutonium elements up to element 100. With the transfermium elements, matters became much more difficult. Among the isotopes of the elements uranium, neptunium, plutonium, and curium, there is at least one that has a half-life of 106 years or more. For americium and berkelium, the longest-lived isotopes, produced by neutron irradiation, have half-lives of the order of 104 years and 1 year, respectively. The most stable californium isotope has a half-life less than

10

Introduction

1000 years, einsteinium a half-life less than a year, and fermium a half-life of about 3 months. The elements of atomic number greater than 100 have isotopes with lifetimes measured in days, hours, minutes, seconds, and fractions of a second. The short half-lives severely limit the amount of a heavier isotope that can be made. Whereas the elements up to atomic number 100 could be characterized with amazingly small amounts of material, these, nevertheless, still contained large numbers of atoms. All of the actinides with atomic numbers up to 99 have been studied with weighable amounts (Table 1.1) but there is no prospect for producing weighable amounts of heavier elements. The elements of higher atomic number had to be identified with as little as one atom of a new element. That this feat was achievable was a result of the rapid developments in nuclear systematics, which made it possible to predict the nuclear properties of new isotopes; the actinide concept, which predicted the chemical properties of transuranium elements; and the development of new experimental techniques, which made it possible to isolate a single atom of a new isotope almost simultaneously with its formation in a nuclear reaction, and to measure half-lives in the millisecond range. On the complex subject of nuclear systematics, it will be sufficient here to mention that the great progress made in the theoretical understanding of the behavior of atomic nuclei allowed predictions about lifetimes and the nature of radioactive emissions and their energetics to be made with considerable confidence, and this played a major role in the search for new elements. The actinide concept similarly played a crucial part. When the first transuranium elements were studied in the laboratory, it soon became apparent that the new members of the periodic table did not have the chemical properties that might be expected of them if they were placed in traditional sequence after uranium. Neptunium did not behave like rhenium, and in no way did plutonium resemble osmium, which would have been positioned directly above plutonium had the first two transuranium elements merely been inserted in the next vacant positions in the periodic table directly after uranium. Because similarities in chemical behavior arise in the periodic table from similarities in electronic configuration of the ions of homologous elements, simple insertion of the transuranium elements into the periodic table would have precluded its use as a reliable guide to the chemistry of the new elements. The actinide hypothesis advanced by Seaborg systematized the chemistry of the transuranium elements, and thus greatly facilitated the search for new elements. From the vantage point of the actinide concept, the transuranium elements are considered to constitute a second inner transition series of elements similar to the rare-earth elements. In the rare-earth series, successive electrons are added to the inner 4f shell beginning with cerium and ending with lutetium. In the actinide series, fourteen 5f electrons are added beginning, formally, with thorium (atomic number 90) and ending with lawrencium (atomic number 103). Although the regularities are not as pronounced in the actinide as in the lanthanide series, the concept of the actinide elements as members of a 5f

Introduction

11

transition series is now accepted and has served as a unifying principle in the evolution of the chemistry of the actinide elements. A more detailed discussion of the actinide hypothesis can be found in Chapter 15. The first chemical studies on neptunium and plutonium were made using classical radiochemical techniques in the 1940s. Amounts far too small to be weighed were studied by tracer methods, where solutions are handled in ordinary-sized laboratory vessels. Concentrations of the order of 10–12 mol L–1 or less are not unusual in tracer work, and valuable information could be acquired on solutions containing only a few million atoms. The radioactive element is detected by its radioactivity, and the chemistry is inferred from its behavior relative to that of an element of known chemistry present in macro amounts. When weighable amounts were available, ultramicrochemical methods were used. These manipulations were and still are carried out with microgram or even lesser amounts of material in volumes of solution too small to be seen by the naked eye at concentrations normally encountered in the laboratory. Ultramicro methods make possible the isolation of small samples of pure chemical compounds, which can then be identified by X-ray crystallography or electron diffraction in a transmission electron microscope. All of the actinide elements are radioactive, and, except for thorium and uranium, special containment and shielded facilities are mandatory for safe handling of these substances. Gloved boxes are required (Fig. 1.2)

Fig. 1.2 A modern laboratory with a bank of gloved boxes for carrying out experimental chemistry of transuranium elements. (Reproduced by permission of Los Alamos National Laboratory.)

12

Introduction

Fig. 1.3 A hot-cell facility for remote synthesis and characterization of gram-scale transuranium materials. (Reproduced by permission of Institute for Transuranium Elements, Karlsruhe, part of the Joint Research Centre, European Commission.)

and, where high levels of penetrating radiation (gamma rays or neutrons) are encountered, which is not infrequent, all manipulations may need to be performed by remote control (Figs. 1.3 and 1.4). Even when radiation can easily be shielded, as is the case with alpha-particle emitters, containment to prevent inhalation is still essential because of the toxicity of the transuranium elements. Inhaled transuranium isotopes may be deposited in the lungs and ingested isotopes may be translocated to the bone, where the intense alpha radioactivity over a period of time can give rise to neoplasms. The shorter the half-life, i.e., the higher the specific activity of the radioactive isotope, the more serious are the difficulties of experiments with macro amounts of material. Consequently, every effort has been made to produce long-lived isotopes. There are available isotopes of neptunium, plutonium, and curium with half-lives longer than 105 years, and isotopes of americium and californium that have half-lives of the order of 1000 years can be used in chemical studies. These long-lived isotopes greatly reduce the extent of radiolysis of water or other solvents for experiments in the liquid phase, they minimize radiation damage in the solid phase, and they also considerably reduce the health hazards in the experiment. Even with the longest-lived isotopes, most laboratory research with transuranium elements is carried out on the milligram or smaller scale. The syntheses of the transfermium elements presented an even more challenging set of problems. Because of the short lifetimes of these isotopes, production by successive neutron capture in a high-flux reactor was not possible. Methods

Introduction

13

Fig. 1.4 Example of an experimental setup within a hot-cell facility. (Reproduced by permission of Institute for Transuranium Elements, Karlsruhe, part of the Joint Research Centre, European Commission.)

for the rapid collection of the newly formed isotopes had to be developed and very rapid separation procedures were required to isolate a pure product for identification. Ghiorso (1982) described in fascinating detail how these problems were surmounted. A newly formed nucleus contains sufficient energy to eject it from a target undergoing bombardment; the atom that recoils can be caught on a clean foil placed in close proximity to the target. The catcher foil can then be dissolved and the solution examined. For identification, ion-exchange chromatography proved to be ideal. Elution from an ion-exchange column can be carried out very rapidly. The order of elution is very specific and provides an unmistakable fingerprint for identification. In this way, it was possible to synthesize and identify element 101, subsequently named mendelevium, in experiments in which it was made one atom at a time. Even more highly refined collection procedures were evolved to complete the actinide series of elements by the discovery of nobelium (atomic number 102) and lawrencium (atomic number 103). The transactinide elements 104 through 112 have been discovered at Berkeley and Darmstadt (see Table 1.1). Scientists at the Dubna Laboratory in Russia also made claims for the discovery of a number of these elements, but their evidence did not meet the accepted criteria for the discovery of new elements (Wilkinson et al., 1991, 1993). No names have been suggested for elements

14

Introduction

heavier than 111, in conformity with the IUPAC rules for the naming of new elements (Koppenol, 2002). A surprising amount of information has accumulated about the oxidation states of the transfermium and transactinide ions in solution even though only a few atoms of any of these were available at any one time. Evidence for isotopes of elements heavier than 112 has been published by a consortium of scientists from Dubna and Livermore (Table 1.1). The chemistry of transactinide elements, and predicted chemical properties of these elements, is presented in Chapter 14. One frontier is the synthesis of longer-lived isotopes and determination of chemical properties of additional transactinide elements (Chapter 14 of this work; Scha¨del, 2003). Numerous theoretical calculations have been made that indicate that there may be more than one ‘‘island” of relatively stable nuclei near the presently defined limits of the periodic table. In addition to the island of spherical stability originally predicted to be around atomic number Z ¼ 114 and neutron number N ¼ 184, other islands of spherical nuclei have been predicted at Z ¼ 120 or 126 and N ¼ 184 and at Z ¼ 120 and N ¼ 172. A predicted island of deformed nuclei at Z ¼ 108 and N ¼ 162 has already been confirmed experimentally. Because of the relatively long half-lives of isotopes conferred by closed nuclear shells, the goal of carrying out chemical studies with the elements at or near these islands is considered to be attainable by some scientists. The new techniques and theoretical understanding required to attain this goal will undoubtedly have profound consequences for nuclear and inorganic chemistry. There are outstanding questions in actinide chemistry. One is the understanding of the bonding and electronic structure of the 5f electrons in condensed phases containing plutonium and adjacent elements. Another is the bonding and chemical behavior of actinides that may be released into the environment. To advance both of these frontiers, heavy-element chemists utilize modern instrumental techniques – X-ray absorption spectroscopy, laser fluorescence spectroscopy, electron microscopy, mass spectroscopy, neutron scattering, to name only a few – that make it possible to study the elements described in the subsequent chapters as pure materials, at extremely low concentrations, and under many unique conditions. Theoretical actinide and transactinide chemistry is advancing rapidly. Relativistic contributions to electronic properties that incorporate spin–orbit interactions are being calculated for bulk actinide solids, actinide metal surfaces, actinide complexes in solution, and transactinide atoms. Relativistic electronic structure theory utilizes time-dependent density functional theory and relativistic effective core potentials. The actinide and transactinide elements in the last 65 years have played an important role in inorganic chemistry, in nuclear chemistry and physics, and in many other branches of science and technology. The actinide elements are also of crucial importance in energy resource development and, regrettably, in warfare. These elements are destined to continue to occupy the attention of scientists, engineers, environmentalists, and statesmen. We hope that these

References

15

volumes will help provide the factual basis so necessary for the important research breakthroughs and technical decisions that will have to be made in future years.

REFERENCES Ghiorso, A. (1982) Actinides in Perspective (ed. N. M. Edelstein), Pergamon Press, Oxford, pp. 23–56. Gruen, D. M. (1992) Transuranium Elements – A Half Century (eds. L. R. Morss and J. Fuger), American Chemical Society, Washington, DC, pp. 63–77. Koppenol, W. H. (2002) Pure Appl. Chem., 74, 787–791. Scha¨del, M. (2003) Chemistry of Superheavy Elements, Kluwer Academic Publishers, Dordrecht. Seaborg, G. T. (1982) Actinides in Perspective (ed. N. M. Edelstein), Pergamon Press, Oxford, pp. 1–22. Seaborg, G. T. (1992) Transuranium Elements – A Half Century (eds. L. R. Morss and J. Fuger), American Chemical Society, Washington, DC, pp. 10–49. Wilkinson, D. H., Wapstra, A. H., Uhelea, I., Barber, R. C., Greenwood, N. N., Hrynkiewicz, A., Jeannin, Y. P., Lefort, M., and Sakai, M. (1991) Pure Appl. Chem., 63, 879–886. Wilkinson, D. H., Wapstra, A. H., Uhelea, I., Barber, R. C., Greenwood, N. N., Hrynkiewicz, A., Jeannin, Y. P., Lefort, M., and Sakai, M. (1993) Pure Appl. Chem., 65, 1764–1814.

ADDITIONAL SUGGESTED READINGS Bagnall, K. W. (1972) The Actinide Elements, Elsevier, Amsterdam. Bagnall, K. W. (ed.) (1972, 1975) Lanthanides and Actinides (MTP International Review of Science, Inorganic Chemistry, series 1, vol. 7, set. 2, vol. 7), Butterworths, London. Blank, H. and Lindner, R. (eds.) (1976) Plutonium 1975 and Other Actinides, North Holland, Amsterdam. Brown, D. (1968) Halides of the Lanthanides and Actinides, Wiley-Interscience, London. Burney, G. A. and Harbour, R. M. (1974) Radiochemistry of Neptunium, Report NASNS 3060. Carnall, W. T. and Choppin, G. R. (eds.) (1983) Plutonium Chemistry (ACS Symp. Ser. 216), American Chemical Society, Washington, DC. Cleveland, J. M. (1979) The Chemistry of Plutonium, 2nd edn, American Nuclear Society, La Grange Park, IL. Cordfunke, E. H. P. (1969) The Chemistry of Uranium, Elsevier, Amsterdam. Edelstein, N. M. (ed.) (1980) Lanthanide and Actinide Chemistry and Spectroscopy (ACS Symp. Ser. 131), American Chemical Society, Washington, DC. Edelstein, N. M. (ed.) (1982) Actinides in Perspective, Pergamon Press, Oxford and New York. Edelstein, N. M., Navratil, J. D., and Schulz, W. W. (eds.) (1985) Americium and Curium Chemistry and Technology, Reidel, Dordrecht.

16

Introduction

Erdo¨s, P. and Robinson, J. M. (1983) The Physics of Actinide Compounds, Plenum, New York. Fields, P. R. and Moeller, T. (eds.) (1967) Lanthanide/Actinide Chemistry (ACS Adv. Ser. 71), American Chemical Society, Washington, DC. Freeman, A. J. and Darby, J. B. (eds.) (1974) The Actinides: Electronic Structure and Related Properties, Academic Press, New York. Handbook on the Physics and Chemistry of Rare Earths, North-Holland, Amsterdam, New York; Elsevier Science, New York, NY, vols 17–19, 1993–1994. Handbook on the Physics and Chemistry of the Actinides, North-Holland, Amsterdam, New York; Elsevier Science, New York, NY, 1984–1991, 6 volumes. Hoffman, Darleane C. (2002) Advances in Plutonium Chemistry, 1967–2000, American Nuclear Society, La Grange Park, IL. Kaltsoyannis, N. and Scott, P. (1999) The f Elements, Oxford University Press, Oxford. Katz, J. J. and Rabinowitch, E. (1951) The Chemistry of Uranium, McGraw-Hill, New York. (Reprinted 1961 by Dover Publications, New York.) Katz, J. J. and Rabinowitch, E. (eds.) (1958) Chemistry of Uranium, 2 vols. U.S. Atomic Energy Commission, Technical Information Service, Oak Ridge, TN, TID-5290. Keller, C. (1971) The Chemistry of the Transuranium Elements, Verlag Chemie, Weinheim. Los Alamos National Laboratory (2000) Challenges in plutonium science, Los Alamos Science No. 26, 2 vols, Los Alamos National Laboratory, Los Alamos, NM. http:// www.fas.org/sgp/othergov/doe/lanl/pubs/number26.htm Milyukova, M. S., Gusev, N. L., Sentyurin, I. G., and Sklyarenko, I. S. (1967) Analytical Chemistry of Plutonium, Israel Program for Scientific Translations, Jerusalem. Myasoedov, B. F., Guseva, L. I., Lebedev, I. A., Milyukova, M. S., and Chmutova, M. S. (1974) Analytical Chemistry of the Transplutonium Elements (Engl. transl.), Wiley, New York. Meyer, G. and Morss, L. R. (eds.) (1991) Synthesis of Lanthanide and Actinide Compounds, Kluwer Academic Publishers, Dordrecht. Morss, L. R. and Fuger, J. (eds.) (1992) Transuranium Elements – A Half Century, American Chemical Society, Washington, DC. Mu¨ller, W. and Blank, H. (eds.) (1976) Heavy Element Properties, North-Holland, Amsterdam. Mu¨ller, W. and Lindner, R. (eds.) (1976) Transplutonium 1975, North-Holland, Amsterdam. National Academy of Sciences (1959–86) Series on Radiochemistry: Stevenson, P. C. and Nervik, W. E. (1961) Actinium, NAS-NS-3020; Hyde, E. (1960) Thorium, NAS-NS3004; Kirby, H. W. (1959) Protactinium, NAS-NS-3016; Gindler, J. (1961) Uranium, NAS-NS-3050; Burney, G. A. and Harbour, R. M. (1974) Neptunium, NAS-NS-3060; Coleman, G. H. and Hoff, R. W. (1965) Plutonium, NAS-NS-3058; Penneman, R. A. and Keenan, R. K. (1960) Americium and Curium, NAS-NS-3006; Higgins, G. H. (1960) The Transcurium Elements, NAS-NS-3031; Roberts, R. A., Choppin, G. R., and Wild, J. F. (1986). Uranium, Neptunium and Plutonium, An Update, NA-NS-3063. Volumes of this series can be found at http://lib-lanl.gov/radiochemistry/ elements.htm. Navratil, J. D. and Schulz, W. W. (eds.) (1980) Actinide Separations (ACS Symp. Ser. 117), American Chemical Society, Washington, DC.

Additional suggested readings

17

Navratil, J. D. and Schulz, W. W. (eds.) (1981) Transplutonium Elements – Production and Recovery (ACS Symp. Ser. 161), American Chemical Society, Washington, DC. Scha¨del, M. (2003) Chemistry of Superheavy Elements, Kluwer Academic Publishers, Dordrecht. Scha¨del, M. (2006) Angew. Chem. Int. Ed., 45, 368–401. Seaborg, G. T. (1958) The Transuranium Elements, Yale University Press, New Haven. Seaborg, G. T. (1963) Man-Made Transuranium Elements, Prentice-Hall, Englewood Cliffs, NJ. Seaborg, G. T. (1978) Transuranium Elements, Products of Modern Alchemy, Dowden, Hutchison and Ross, Stroudsburg, PA. Seaborg, G. T. and Katz, J. J. (eds.) (1954) The Actinide Elements (Natl Nucl. Eng. Ser., Div. IV, 14A), McGraw-Hill, New York. Seaborg, G. T., Katz, J. J., and Manning, W. M. (eds.) (1949) The Transuranium Elements (Natl Nucl. Eng. Ser., Div. IV, 14B), McGraw-Hill, New York. Seaborg, G. T. and Loveland, W. D. (1990) The Elements Beyond Uranium, WileyInterscience, New York. Schulz, W. W. (1976) The Chemistry of Americium, Report TID-26971, US Dept of Energy, Technical Information Center, Oak Ridge, TN. Sterne, P. A., Gonis, A., and Borovoi, A. A. (1998) Actinides and the Environment, Kluwer Academic Publishers, Dordrecht. Taube, M. (1974) Plutonium – A General Survey, Verlag Chemie, Weinheim. Trotman-Dickenson, A. F. (exec. ed.) (1973) Comprehensive Inorganic Chemistry, vol. 5, The Actinides, Pergamon, Oxford. Wick, O. J. (ed.) (1967) Plutonium Handbook, Gordon and Breach, New York, 2 vols.

CHAPTER TWO

ACTINIUM H. W. Kirby and L. R. Morss 2.1 2.2 2.3 2.4 2.5 2.6

Introduction 18 Nuclear properties 20 Occurrence in nature 26 Preparation and purification Atomic properties 33 The metallic state 34

2.1

2.7 Compounds 35 2.8 Solution and analytical chemistry 37 2.9 Applications of actinium References 44

27

42

INTRODUCTION

The actinide series of elements encompasses all the 15 chemical elements that have properties attributable to the presence of low‐lying 7p, 6d, and 5f orbitals such that their tripositive ions have electronic configurations 7p06d05f n, where n ¼ 0,1,2,. . .,14. According to this definition, actinium, element 89, is the first member of the actinide series of elements, although it has no 5f electrons in its metallic, gaseous, or ionic forms. As such, its position in group 3 (in current IUPAC terminology) or group 3B (commonly used in some American textbooks) of the periodic table is analogous to that of its homolog, lanthanum, in the lanthanide series. This definition, which includes actinium as the first of the actinides (Seaborg, 1994), parallels the accepted inclusion of lanthanum as the first member of the lanthanide series (Moeller, 1963). The chemistry of actinium closely follows that of lanthanum. There are no qualitative differences between them; the only quantitative differences are those ˚ for Ac3þ and 1.032 A ˚ for attributable to the difference in their ionic radii (1.12 A 3þ La in six‐fold coordination) (Shannon, 1976 and Chapter 15, section 7.5, of this book). Because of this similarity, lanthanum is a nearly ideal surrogate for actinium in the development of preparative or analytical procedures. As a carrier for trace amounts of actinium, lanthanum suffers from only one disadvantage: Once mixed, the two elements behave like any pair of adjacent rare earths and can be separated only by ion‐exchange chromatography, solvent extraction, or fractional crystallization. The most important isotope of actinium is 227Ac, a member of the naturally occurring uranium–actinium (4n þ 3) family of radioelements. Its applications 18

Introduction

19

are derived from its unique radioactive properties. Although 227Ac itself is essentially (98%) a weak b emitter, with a moderately long half‐life (21.773 years), its decay chain includes five short‐lived a emitters. The net effect is one of high specific power and long service life, a combination that makes 227Ac suitable as a heat source in thermoelectric generators on space missions to the outer planets and beyond. Recently 225Ac and 228Ac have found applications (see Section 2.9). The early actinium literature (up to January 1940) was comprehensively reviewed by the staff of the Gmelin Institute, and an English translation is available (Gmelin, 1942). Later reviews and bibliographies have appeared with the waxing and waning of interest in possible applications of actinium (Clarke, 1954, 1958; Hagemann, 1954; Bagnall, 1957; Katz and Seaborg, 1957; Bouissie`res, 1960; Stevenson and Nervik, 1961; Salutsky, 1962; Sedlet, 1964; Kirby, 1967; Keller, 1977). The most recent monograph on actinium chemistry is the Gmelin Handbook supplement (Gmelin, 1981). 2.1.1

Historical

In 1899, Andre´ Debierne, in the laboratory of Pierre and Marie Curie, reported that he had found a new radioactive substance, whose chemistry closely followed that of titanium (Debierne, 1899). Six months later, he said that the titanium fraction was no longer very active, but that the radioactive material he was now recovering exhibited the same chemical behavior as thorium (Debierne, 1900). Debierne claimed the right of discovery and named the new substance actinium (aktis, ray). His claim was accepted uncritically at the time, but, in the light of what we now know of the chemical and nuclear properties of actinium, it is clear that his 1899 preparation contained no actinium at all and that his 1900 preparation was a mixture of several radioelements, possibly including actinium as a minor constituent (Kirby, 1971; Adloff, 2000). In 1902, Friedrich Giesel reported a new ‘emanation-producing’ substance among the impurities he had separated with radium from pitchblende residues (Giesel, 1902). He correctly established many of its chemical properties, including the important fact that it followed the chemistry of the cerium group of rare earths. By 1903, he had concentrated and purified it to a point where lanthanum was the chief impurity and thorium was spectroscopically undetectable (Giesel, 1903). A year later, he proposed the name, emanium, for what was clearly a new radioelement (Giesel, 1904a). Giesel’s claim was vigorously attacked by Debierne (1904), who now had an emanation‐producing substance of his own, which, he insisted, was the same as the substance he had originally named actinium, although the 1900 preparation had titanium‐ or thorium‐like properties (Adloff, 2000). Debierne’s claim prevailed, and has been propagated by historians (Ihde, 1964; Partington, 1964; Weeks and Leicester, 1968), largely because of the prestige of the Curies and the support of Rutherford (1904). The latter based his conclusion solely on

Actinium

20

the similarity in the decay characteristics of the ‘‘emanations” (i.e. 219Rn) and the ‘‘active deposits” (211Pb) given off by the samples supplied to him by the two claimants. Although some historical studies (Weeks and Leicester, 1968; Adloff, 2000) give both Debierne and Giesel credit for the discovery, Kirby (1971), Keller (1977), and the second author of this chapter believe that it is more appropriate to give credit for discovery of actinium to Giesel. The actinium decay chain was sorted out rather quickly. In 1905, Godlewski (1904–5, 1905) and Giesel (1904b, 1905) independently reported the existence of actinium X (also referred to as ‘‘emanium X”), now known as 223Ra, and showed it to be the direct source of the actinium emanation and its active deposit. The following year, Hahn (1906a,b) discovered radioactinium (227Th), the immediate descendant of actinium and the parent of actinium X. 231 Pa, the parent of actinium, was discovered independently in 1918 by Soddy and Cranston (1918a,b) and by Hahn and Meitner (1918). The primordial origin of the actinium series (4n þ 3 or uranium–actinium series, Fig. 2.1) was not finally resolved until 1935, when Dempster (1935) detected the uranium isotope of atomic weight 235 by mass spectroscopy.

2.2

NUCLEAR PROPERTIES

Of the 29 known isotopes of actinium (Table 2.1) only three are of particular significance to chemists. Two of these isotopes are the naturally occurring isotopes, 227Ac (Fig. 2.1, 4n þ 3 or uranium–actinium series) and 228Ac (mesothorium II, Fig. 2.2, 4n or thorium series). The third is 225Ac, a descendant of reactor‐produced 233U (Fig. 2.3, 4n þ 1 or neptunium series). 2.2.1 227



Actinium–227

The isotope Ac, a b emitter, is a member of the naturally occurring 235U (AcU) decay series (Fig. 2.1). It is the daughter of 231Pa and the parent of 227Th (RdAc). It is also the parent, by a 1.38% a branch (Kirby, 1970; Monsecour et al., 1974), of 223Fr, which was discovered in 1939 by Perey (1939a,b). The half‐life of 227Ac is (21.772 ± 0.003) years (Jordan and Blanke, 1967; Browne, 2001), as determined by calorimetric measurements made over a period of 14 years. The thermal‐neutron‐capture cross section st and the resonance integral are (762 ± 29) barn and (1017 ± 103) barn, respectively (1 barn ¼ 1028 m2) (Monsecour and De Regge, 1975). The b radiation of 227Ac is so weak (0.045 MeV maximum) (Beckmann, 1955; Novikova et al., 1960) that the nuclide was once thought to be ‘rayless’ (Marckwald, 1909; Rutherford, 1911). Even with modern nuclear spectrometers, neither the b nor the g radiation is useful for analytical purposes because of interference from the rapidly growing decay products. On the other hand, 227Ac is readily identified, even in the presence of its decay products,

Fig. 2.1

Uranium–actinium series (4n þ 3).

Table 2.1 Nuclear properties of actinium isotopes.a Mass number

Half‐life

Mode of decay

Main radiations (MeV )

Method of production

a a a a a a a

a 7.750 a 7.790 a 7.712 a 7.572 a 7.758 a 7.59 a 7.46

175

Lu(40Ar,9n)

175

Lu(40Ar,8n) Lu(40Ar,7n)

209 210

33 ms 22 ms 22 ms 95 ms 25 ms 0.10 s 0.35 s

211

0.25 s

a

a 7.48

212

0.93 s

a

a 7.38

213

0.80 s

a

a 7.36

214

8.2 s

215

0.17 s

a 7.214 (52%) 7.082 (44%) a 7.604

216 216 m

0.33 ms 0.33 ms

a  86% EC  14% a 99.91% EC 0.09% a a

217 218 219 220

69 ns 1.08 ms 11.8 ms 26.4 ms

a a a a

221

52 ms

a

222

5.0 s

a

222 m

63 s

223

2.10 min

224

2.78 h

225

10.0 d

a > 90% EC  1% IT < 10% a 99% EC 1% EC  90% a  10% a

226

29.37 h

227

21.772 yr

206 207 208

b 83% EC 17% a 6  103% b 98.62% a 1.38%

a 9.072 a 9.108 (46%) 9.030 (50%) a 9.650 a 9.20 a 8.66 a 7.85 (24%) 7.68 (21%) 7.61 (23%) a 7.65 (70%) 7.44 (20%) a 7.00 a 7.00 (15%) 6.81 (27%) a 6.662 (32%) 6.647 (45%) a 6.211 (20%) 6.139 (26%) a 5.830 (51%) 5.794 (24%) g 0.100 (1.7%) a 5.399 b 1.10 g 0.230 (27%) a 4.950 (47%) 4.938 (40%) b 0.045 g 0.086

175 197

Au(20Ne,8n) Au(20Ne,7n) 203 Tl(16O,9n) 197 Au(20Ne,6n) 203 Tl(16O,8n) 203 Tl(16O,7n) 197 Au(20Ne,5n) 197 Au(20Ne,4n) 203 Tl(16O,6n) 203 Tl(16O,5n) 197 Au(20Ne,3n) 203 Tl(16O,4n) 209 Bi(12C,6n) 209 Bi(12C,5n) 197

208

Pb(14N,5n) Pa daughter 223 Pa daughter 208 Pb(15N,3n) 224 Pa daughter 222

205

Tl(22Ne,a2n) Pb(18O,p4n) 226 Ra(p,5n) 208 Pb(18O,p3n) 208 Pb(18O,p3n) 209 Bi(18O,an) 208

227

Pa daughter

228

Pa daughter

225

Ra daughter

226

Ra(d,2n)

Nature

Nuclear properties

23

Table 2.1 (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

228

6.15 h

b

Nature

229

62.7 min

b

230

122 s

b

231

7.5 min

b

b 2.18 g 0.991 b 1.09 g 0.165 b 1.4 g 0.455 b 2.1 g 0.282

232 233 234 a

119 s 145 s 44 s



b b b

229

Ra daughter Th(g,p2n) 232 Th(g,pn) 232

232

Th(g,p) Th(n,pn) U þ Ta 238 U þ Ta 238 U þ Ta 232

238

Appendix II.

Fig. 2.2

Thorium series (4n).

by a spectrometry (Fig. 2.4), and a computational technique has been described for its quantitative determination by this method (Kirby, 1970). The g spectrum of 227Ac in equilibrium with its decay products is shown in Fig. 2.5. The 235.9‐keV g‐ray, which has an intensity of (12.3 ± 1.3)% of 227Th

Actinium

24

Fig. 2.3

Neptunium series (4n þ 1).

a decay, can be used for quantitative analysis of 227Ac. For a detailed level scheme, see the most recent critical compilation (Firestone and Shirley, 1996). 2.2.2 228

Actinium–228 (MsTh II or MsTh2)

The isotope Ac (mesothorium II or MsTh2) is a member of the naturally occurring 232Th decay chain. It is the daughter of 5.77‐year 228Ra (mesothorium I or MsTh1) and the parent of 1.9116‐year 228Th (radiothorium). All three nuclides were discovered by Otto Hahn (1905, 1907, 1908). The long‐accepted half‐life of 228Ac (6.13 ± 0.03) h, reported in 1926 (Hahn and Erbacher, 1926), was redetermined to be (6.15 ± 0.02) h in 1985 (Skarnemark and Skalberg, 1985). 228 Ac has a complex b spectrum (Bjornholm et al., 1957; Arnoux and Giaon, 1969; Dalmasso et al., 1974), but, unlike 227Ac, more than 99% of the b particles have maximum energies greater than 0.5 MeV so that its g‐ray spectrum (Novikova et al., 1960) is a useful analytical tool. By contrast, the

Nuclear properties

Fig. 2.4

25

Alpha spectrum of 227Ac in equilibrium with its decay products (Kirby, 1970).

b and g radiations from 228Ra are too weak for routine detection; consequently, nearly all methods for the determination of 228Ra are based on the isolation and counting of 228Ac (Hahn and Erbacher, 1926). 228Ac is frequently used as a tracer for other actinium isotopes (Bhatki and Adloff, 1964; Chayawattanangkur et al., 1973). A level scheme and a critical compilation of g‐ray energies for 228Ac have been published (Horen, 1973). 2.2.3

Actinium-225

The isotope 225Ac is an a emitter. It is a member of the 4n þ 1 decay series, of which 237Np is the longest‐lived member and progenitor (Fig. 2.3). In practice, however, 225Ac is most easily obtained by milking a sample of 229Th that was previously separated from aged 233U (Valli, 1964). The latter isotope is itself produced by neutron bombardment of natural thorium (St. John and Toops, 1958; Hyde et al., 1964): 232

b

Thðn;
Þ233 Th !

22:3 min

233

b

Pa !

26:967 d

233

U

ð2:1Þ

Actinium

26

Fig. 2.5 Gamma spectrum of 2002).

227

Ac in equilibrium with its decay products (I. Ahmad,

Unfortunately, 229Th is always more or less contaminated with 228Th because of side reactions during the production of 233U: 232

b

Thðn; 2nÞ231 Th !

231

25:52 h

231

b

Paðn;
Þ232 Pa !

1:31 d

232

ð2:2Þ

Pa

a

U !

68:9 y

228

Th

ð2:3Þ

To obtain pure samples of 225Ac, the presence of 228Th in 229Th is not a serious problem, because the 224Ra daughter of 228Th can be chemically separated from he 225Ac, together with 225Ra, after its milking from thorium. The 224Ra must be removed to ensure the absence of its progeny 208Tl, which emits a 2.6‐MeV g‐ray. The complex fine structure of the 225Ac a spectrum was thoroughly investigated by Dzhelepov et al. (1967) and by Bastin‐Scoffier (1967). A level scheme is given in a critical compilation (Maples, 1973).

2.3

OCCURRENCE IN NATURE

The natural occurrence of 227Ac is proportional to that of its primordial ancestor, 235U, which is widely distributed in the Earth’s crust (Kirby, 1974). The average crustal abundance of uranium is 2.7 ppm (Taylor, 1964), of which

Preparation and purification

27

0.720 mass% is 235U (Holden, 1977). Therefore, the natural abundance of 227Ac (calculated from its half‐life and that of 235U) is 5.7  1010 ppm. Based upon a crustal mass of 2.5  1025 g (to a depth of 36 km) (Heydemann, 1969), the global inventory of 227Ac is estimated to be 1.4  104 metric tons. Although the 4n þ 1 family is not ordinarily considered to be ‘naturally occurring’ because its primordial ancestor has become extinct, both 237Np and 225 Ac have been detected in uranium refinery wastes and 225Ac has been found 232 in Th isolated from Brazilian monazite (Peppard et al., 1952). These nuclides are believed to be formed continually in nature by the bombardment of natural thorium and uranium with neutrons arising from spontaneous fission of 238U and from neutrons produced by (a,n) reactions on light elements: 238

232

2.4

Uðn; 2nÞ

Thðn;
Þ

237

b

U !

237

6:75d

233

b

Th !

Np

233

22:3 min

U

ð2:4Þ

ð2:5Þ

PREPARATION AND PURIFICATION

Uranium ores always contain large amounts of rare earths, and were thus generally unsatisfactory as sources of actinium before modern methods of rare earth separations were developed. The most concentrated actinium sample ever prepared from a natural raw material consisted of 0.5 mCi (7 mg) of 227Ac in less than 0.1 mg of La2O3 (Lecoin et al., 1950). In 1949, Peterson reported that 227Ac could be synthesized by irradiating 226 Ra with thermal neutrons (Peterson, 1949): 226

Raðn;
Þ

227

b

Ra !

227

42:2 min

Ac

ðt ffi 20 barnÞ

ð2:6Þ

This reaction greatly simplified the chemical separations required to prepare macroscopic amounts of pure 227Ac and, in 1950, Hagemann reported the isolation of 1.27 mg of 227Ac from 1 g of neutron‐irradiated 226Ra (Hagemann, 1950). Later work (Kirby et al., 1956; Cabell, 1959; Monsecour and De Regge, 1975) showed that the neutron‐capture cross section of 227Ac is many times greater than that of 226Ra (Fig. 2.6). A new problem is introduced, namely that of separating 227Ac from the large amounts of 1.9‐year 228Th produced by the second‐order reactions: 227

Acðn; gÞ

228

b

Ac !

6:15 h

228

Th

ðt ¼ 762 barnÞ

ð2:7Þ

Actinium

28

Fig. 2.6 Growth of 227Ac in neutron‐irradiated 226Ra at various thermal‐neutron fluxes F (in cm2 s1). The calculations assume st(226Ra) ¼ 20 barn and st(227Ac) ¼ 795 barn (Gomm and Eakins, 1968).

Nevertheless, neutron irradiation of 226Ra remains the method of choice for the preparation of 227Ac at either the tracer or the macroscopic level. The isotope 225Ac is best generated by separating it from the generator 229Th (Geerlings et al.,1993; Tsoupko‐Sitnikov et al., 1996; Khalkin et al., 1997). The 229 Th generator must be separated from 233U. The isotope 233U is synthesized by neutron irradiation of 232Th, which contaminates the 229Th with some 228Th and its daughters. The isotope 228Ac can be generated by separating it from the generator 228Ra, which can be isolated from natural 232Th (Gmelin, 1981). Detailed procedures were given by Sekine et al. (1967). Sani (1970) and Mikheev et al. (1995) removed 228Ra from aged 232Th by cocrystallization with Ba(NO3)2. The 228 Ac that grew into 228Ra was removed by extraction or by adding GdCl3 to an aqueous solution of the 228Ra in Ba(NO3)2 and coprecipitating Ac3þ with Gd (OH)3 using NH3(g). 2.4.1

Purification by liquid–liquid extraction

Hagemann (1950, 1954) isolated the first milligram of 227Ac from neutron‐ irradiated 226Ra by liquid–liquid extraction with 2‐thenoyltrifluoroacetone (TTA). Experience has shown (Engle, 1950; Stevenson and Nervik, 1961; Kirby, 1967), however, that TTA is not a suitable reagent for quantitative extraction of actinium because a relatively high pH (5.5, Fig. 2.7) is required

Preparation and purification

29

Fig. 2.7 Extraction of various elements with thenoyltrifluoroacetone (TTA). (After Stevenson and Nervik, 1961).

for efficient chelation but Ac3þ hydrolyzes above pH 7 and forms inextractable polymeric species when the pH is in the ‘desirable’ range, 6–7. The recovery of actinium requires tight pH control and speed of operation for satisfactory yields (Allison et al., 1954; Tousset, 1961) that are usually not quantitative. The most effective application of TTA in the purification of 227Ac is to remove 227Th, which can be selectively and quantitatively extracted from moderately acid solutions. For this extraction, the pH50 (the pH at which 50% of the Th4þ is extracted or partitioned equally between the phases, i.e. D ¼ 1) is 0.48 (Poskanzer and Foreman, 1961). On the other hand, Sekine et al. (1967) found that, while the extraction of 228 Ac with TTA alone was not quantitative, a mixture of 0.1 M TTA and 0.1 M tri(n‐butyl)phosphate (TBP) in CCl4 gave reproducible distribution ratios and quantitative extraction of Ac3þ at pH  4. Solvent extraction systems that have been applied to other actinide and lanthanide separations have also been applied to actinium separations from thorium and radium. Thus, Karalova et al. (1977a) studied the extraction of Ac(III) in aqueous nitrate solution by trioctylphosphine oxide dissolved in cyclohexane, o‐xylene, carbon tetrachloride, octyl alcohol, or chloroform. Optimum extraction conditions were: [NaNO3]  2 M, pH 2, and cyclohexane as the partition solvent. Making the aqueous phase 8 M in lithium chloride appears to facilitate extraction with 0.1 M trioctylphosphine oxide (Karalova et al., 1977b). Trialkylphosphine oxide in aliphatic hydrocarbon solvents was used by Xu et al. (1983) for the solvent extraction separation of Ac(III) from La(III) in nitric acid solution. Amines and quaternary ammonium bases have also been used in

Actinium

30

solvent extraction systems for the separation of Ac(III) from rare earths and Am(III). Karalova et al. (1979a) examined the separation of Ac(III) from Eu(III) by extraction from aqueous solutions containing lithium nitrate at pH 2.5–3 with tri‐n‐octylamine in cyclohexane, and concluded that this partition system shows promise for the separation of Ac(III) from rare earths. A 0.5 M solution of the quaternary ammonium base Aliquat 336 (methyltrioctylammonium chloride) in xylene extracts Ac, Am, and Eu efficiently from aqueous alkaline (pH > 11) solutions containing ethylenediaminetetraacetic acid (EDTA) or 2‐hydroxydiaminopropanetetraacetic acid; separation factors for Ac(III)/Am(III) and Ac(III)/Eu(III) greater than 100 were attained (Karalova et al., 1978a, 1979b). A mixture of trialkylmethylammonium nitrate and TBP was reported by Mikhailichenko et al. (1982) to exert a weak synergistic effect on La(III) extraction and an antagonistic effect on Ac(III) extraction. Bis(2‐ethylhexyl) phosphoric acid (HDEHP) has been successfully employed in the solvent extraction separation of 227Ac(III), 227Th(IV), 223Ra(II), and 223Fr(I) (Mitsugashira et al., 1977). Karalova et al. (1978b) established that the actinium species extracted from 1 M perchloric acid is AcX3·2HX, and at higher perchloric acid concentrations is HAc(C1O4)4·2HX. The use of bis(2‐ethylhexyl)phosphoric acid (HDEHP) as an extractant for Ac3þ has been little explored. Two studies have explored the fundamental mechanism of this extractant with Ac3þ (Szeglowski and Kubica, 1991) and the influence of colloidal rare earth particles on this extraction (Szeglowski and Kubica, 1990). An unusual purification procedure is one in which actinium must be removed from rare earths on a commercial scale to minimize the level of radioactive contamination of the rare earth products (Kosynkin et al., 1995). Uranium–rare earth phosphorites [fibrous apatites, generic formula Ca5(PO4)3(OH,F,Cl)] have been processed commercially to remove both uranium and rare earths. After uranium was extracted from the dissolved phosphorite, cerium was removed by oxidation and precipitation from dilute acid. The trivalent rare earths and actinium remained in the aqueous phase and the actinium was removed from the rare earth fraction using mixer‐settlers with mixtures of TBP and trialkyl amine (TAA) extractants in kerosene. Decontamination from a level of 108 Ci/(g rare earth oxides) to a level of 2  1011 Ci/(g rare earth oxides) has been achieved on an industrial scale. 2.4.2

Purification by ion‐exchange chromatography

Cation‐exchange chromatography is the simplest and most consistently effective method of separating sub‐milligram amounts of 227Ac from its principal decay products, 18.68‐day 227Th and 11.43‐day 223Ra (Gmelin, 1981). The resin most commonly employed is a strong cation‐exchange resin such as Dowex 50 (Andrews and Hagemann, 1948; Cabell, 1959; Farr et al., 1961; Eichelberger et al., 1964; Nelson, 1964; De Troyer and Dejonghe, 1966; Baetsle´ et al., 1967;

Preparation and purification

31

Baetsle´ and Droissart, 1973; Kraus, 1979; Boll et al., 2005), but inorganic ion exchangers have also been used successfully (Huys and Baetsle´, 1967; Monsecour and De Regge, 1975). The method is applicable to milking of 228 Ac tracer from its parent, 5.76 year 228Ra (Bjornholm et al., 1956, 1957; Duyckaerts and Lejeune, 1960; Bryukher, 1963; Bhatki and Adloff, 1964; Gomm and Eakins, 1966; Arnoux and Giaon, 1969; Monsecour et al., 1973). A typical separation is illustrated in Fig. 2.8. Anion‐exchange chromatography is now used for bulk separation of 225Ac and 223Ra from 229Th. The 225Ac and 223Ra are eluted in 2–4 bed volumes of 8 M HNO3 and then 229Th is stripped from the resin in 0.1 M HNO3, after which the 229 Th can be recycled (Boll et al., 2004). Partition chromatography by reverse‐phase and ion‐exchange chromatography has been explored (Sinitsyna et al., 1977, 1979). The radioisotopes of actinium were separated from other elements using trioctylamine, bis(2‐ethylhexyl)phosphoric acid, and TBP as stationary phases on Teflon. Chromatography on a Teflon support was also investigated by Korotkin (1981). He used a mixture of TTA and TBP impregnated in Teflon to sorb the metal ions. Elution

Fig. 2.8 Separation of 227Ac from its decay products by cation‐exchange chromatography on Dowex 50, hydrogen form, 200–400 mesh, 60 C (Cabell, 1959).

Actinium

32

was by oxalate in a phthalate buffer. The procedure appears to have general utility for the rapid separation of actinides, lanthanides, and other metal ions. 227Ac was separated from irradiated radium samples containing Pb, Tl, Bi, Po, and Th, and 225Ac was separated from 233U containing the same elements. The inorganic cation exchanger, cryptomelane MnO2 [a sorbent for large cations related to the mineral cryptomelane, K(Mn4þ,Mn2þ)8O16] is highly radiation‐resistant and has distribution ratios (Kd values) for trivalent lanthanides and actinides that are orders of magnitude smaller than for Ra2þ. This ion exchanger has been used to separate 225Ac3þ or 228Ac3þ from 225Ra2þ or 228 Ra2þ in radioisotope generators (Włodzimirska et al., 2003). 2.4.3

Isolation of gram quantities of actinium

The history of large‐scale actinium production is littered with the mutilated corpses of carefully designed processes, developed at the laboratory scale, which failed utterly, or required innumerable ad hoc modifications, when they were applied to the recovery of multi‐Curie amounts of 227Ac and 228Th from multigram quantities of neutron‐irradiated 226Ra (Andrews and Hagemann, 1948; Engle, 1950; Kirby, 1951, 1952; Eichelberger et al., 1964, 1965; De Troyer and Dejonghe, 1966; Foster, 1966; Baetsle´ et al., 1967; Huys and Baetsle´, 1967; Baetsle´ and Droissart, 1973). Not the least of the problems is that posed by 3.824‐day 222Rn, a noble gas, which is evolved copiously and continuously by the decay of 226Ra. The radioactive gaseous exhaust from the facility must be trapped and immobilized for several weeks while it decays to levels at which it can safely be released to the environment. (The maximum permissible concentration [inhalation derived air concentration (DAC)] of 222Rn and its progeny in air in the workplace is very low, 3  108 mCi mL1) (U.S. Nuclear Regulatory Commission, 2005) Until now, this low level has been achieved by adsorbing the radon on activated charcoal at 75 to 180 C (Baetsle´ et al., 1972), or by replacing the air at a sufficiently high rate, but chemical methods for removing radon and its daughters from the air by reaction with powerful fluorination reagents were also shown to bear promise for the removal of radon from air (Stein and Hohorst, 1982). At the Belgian Nuclear Research Center (SCK‐CEN, Mol), the irradiated RaCO3 was dissolved in dilute nitric acid, and then precipitated as Ra(NO3)2 from 80% HNO3, leaving nearly all the 227Ac and 228Th in solution. This step made the 226Ra immediately available for recycling to the reactor; it also eliminated many of the severe radiolytic problems that develop when organic solvents or ion‐exchange resins are in contact with large amounts of 226Ra for extended periods of time. The solution was then filtered, adjusted to 5 M HNO3, and passed through a column of Dowex AG 1  8, an anion‐exchange resin. 228Th was quantitatively

Atomic properties

33

adsorbed (Danon, 1956, 1958), while the non‐complexing cations (Fe, Ni, Cr) passed through the column unimpeded. 227Ac, which appeared to be adsorbed to a slight extent by the resin, followed after a brief delay. The actinium was finally purified by oxalate precipitation (Salutsky and Kirby, 1956) and ignited to Ac2O3 at 700 C. The process gave excellent Ac/Th separations ( 10. They determined the *Ks,0

225

AcðOHÞ3 ðsÞ þ 3Hþ ðaqÞ ! Ac3þ ðaqÞ þ 3H2 O *Ks;0

ð2:11Þ

to be 7.9  10 . This value is much higher than that derived by Ziv and Shestakova or that expected by extrapolating from trivalent rare earths and actinide hydroxides. 31

2.8.3

Complexation

As in all its reactions, actinium closely resembles lanthanum in its behavior toward complexing agents. To the extent that they have been determined experimentally, the stability constants of actinium complexes (a selection is given in Table 2.4) are the same as, or slightly smaller than, those of the corresponding lanthanum complexes (Rao et al., 1968, 1970; Shahani et al., 1968; Sekine et al., 1969; Sekine and Sakairi, 1969; Gmelin, 1981), in agreement with prediction from the similarity in their electronic configurations and their ionic radii (Kirby, 1967; Section 15.7.5). There is a linear dependence of log (formation constant) upon ionic radius, with Ac3þ always having the extreme position of largest ionic radius (Gmelin, 1981 and Section 15.7.5). The hydrolysis of Ac3þ(aq) is the smallest of all 3þ ions. Moutte and Guillaumont (1969) determined the equilibrium constant for the reaction þ AcOH2þ ðaqÞ þ H2 O ! AcðOHÞþ 2 ðaqÞ þ H ðaqÞ

ð2:12Þ

to be 3.5  109 mol L1. Using the isotope 228Ac, they determined that, at pH 8, 74% of the actinium in solution exists as Ac(OH)2þ and 26% exists as AcðOHÞþ 2. The Ac3þ–citrate complexes are sufficiently strong that citrate complexes almost all Ac3þ in 0.001 M citrate even at pH 8.1 (Moutte and Guillaumont, 1969). In addition to the complexes listed in Table 2.4, Ac3þ complexes have been studied with trans-1,2‐diaminocyclohexanetetraacetic acid (DCTA), TTA and other diketones, arsenazo III, and other organic ligands (Gmelin, 1981). Fukusawa et al. (1982) determined stability constants for chloro and bromo complexes of Ac(III), among many others, by a solvent extraction procedure. A much larger contribution from inner‐sphere complex formation was observed in chloro than in bromo complexes for tripositive actinide ions. An empirical approach for predicting the stability of metal‐ion complexes has been applied to actinium (Kumok, 1978). On the basis of known and estimated ionic radii, Abramov et al. (1998) calculated the extraction constant Kex of Ac3þ with bis(2‐ethylhexyl)phosphoric acid (HDEHP) into toluene. The calculated Kex value for Ac3þ is nearly an order of magnitude smaller than that for La3þ.

Solution and analytical chemistry

41

Table 2.4 Cumulative stability constants of selected actinium complexes. Ligand

Ionic strength (m)

[Hþ] (M)

Stability constanta

F

0.5

0.00025

F Cl

0.1 1.0

0.016 1.0

Cl

4.0

0.01

Br

1.0

1.0

NO 3

1.0

1.0

SO2 4

1.0–1.16

1.0

SO24

1.0

pH 3–3.5

SCN

1.0

pH 2

SCN

5.0

pH 3–3.5

C2 O2 4

1.0

pH 3–3.5

H2 PO 4 Citrate b NTA EDTAc

0.5 0.1 0.1 0.1

pH 2–3 pH 2–3 pH 5 pH 2.8

b1 ¼529 ± 8 b2 ¼(1.67 ± 0.09)  105 b3 ¼8  107 b1 ¼885 b1 ¼0.80 ± 0.09 b2 ¼0.24 ± 0.08 b1 ¼0.9 b2 ¼0.09 b3 ¼0.05 b1 ¼0.56 ± 0.07 b2 ¼0.30 ± 0.06 b1 ¼1.31 ± 0.12 b2 ¼1.02 ± 0.12 b1 ¼15.9 ± 1.3 b2 ¼71.4 ± 7.3 b1 ¼22.9 b2 ¼479 b1 ¼1.11 ± 0.07 b2 ¼0.82 ± 0.08 b1 ¼0.18 b2 ¼0.35 b1 ¼3.63  103 b2 ¼1.45  106 b1 ¼38.8 ± 5 b1 ¼9.55  106 b3 ¼4.3  1014 b1 ¼1.66  1014

a

n ¼ ½MLn=½M½Ln :

b

HNTA, 2‐naphthoyltrifluoroacetone. EDTA, ethylenediaminetetraacetic acid.

c

2.8.4

Reference Aziz and Lyle (1970) Makarova et al. (1973) Shahani et al. (1968) Sekine and Sakairi (1969) Shahani et al. (1968) Shahani et al. (1968) Shahani et al. (1968) Sekine and Sakairi (1969) Rao et al. (1968) Sekine and Sakairi (1969) Sekine and Sakairi (1969) Rao et al. (1970) Makarova et al. (1974) Keller and Schreck (1969) Makarova et al. (1972)

Radiocolloid formation

Kirby (1969) noted that when acidic aqueous solutions containing tracer amounts of Ac3þ and its progeny 227Th4þ and 223Ra2þ are dried on platinum disks, the actinium can be separated by redissolution in dilute NH4NO3(aq) and the radium by redissolution in dilute HF(aq), leaving the thorium on the disk. He described this separation as an application of ‘residue adsorption’; it may represent radiocolloid formation and selective redissolution at the metal surface. Rao and Gupta (1961) studied the adsorption of 228Ra and 228Ac onto sintered glass and paper, and found that the adsorption of 228Ac onto the glass increased with pH and time of aging. They studied the phenomenon by

Actinium

42

centrifugation; the 228Ac fraction could be centrifuged at pH  5. Paper chromatography showed that the 228Ac was immobile at a pH of 3 and higher, whereas Ba remained in solution. They concluded that the 228Ac formed radiocolloids at pH  5. 2.8.5

Analytical chemistry of actinium

Sedlet (1964) published a complete set of procedures for analytical chemistry of actinium, primarily radiochemical procedures for 227Ac. Kirby (1967) published a review that selected published and unpublished procedures that ‘‘will be of most value to the modern analytical chemist.” Kirby also wrote the section on analytical chemistry in Gmelin (1981). Karalova (1979) reviewed the analytical chemistry of actinium. The analytical procedures that they described were based upon separation of actinium from other radioelements and then determination by measurement of the a, b, or g radioactivity of a sample that has reached secular equilibrium with its daughters. The techniques suitable for tracer‐level determination of 227Ac are neutron activation analysis, by which 227Ac can be determined at the level of 1017 g, and total a, b, and g radioactivity of a sample that has reached secular equilibrium with its daughters, by which 227Ac can be determined at the level of 1020 g. Recently a procedure for determination of 227 Ac in environmental samples by coprecipitation with lead sulfate, ion exchange, and a spectrometry after allowing the daughter isotopes 227Th and 223Ra to reach secular equilibrium (2–3 months) has been published (Martin et al., 1995). The method requires the use of a short‐lived actinium yield tracer, 225Ac or 228Ac. The lower limit of detection is 0.2 mBq per sample (7.5  1016 g) at 95% confidence level. The isotope 225Ac, which is useful for tumor radiotherapy (see below), can be determined by a‐spectrometric measurement of its a‐emitting progeny 217At (Martin et al., 1995) or by g spectrometry of the progeny 221Fr and 213Bi (McDevitt et al., 2001).

2.9

2.9.1

APPLICATIONS OF ACTINIUM

Heat sources for radioisotope thermoelectric generators

The first practical use of actinium was to produce multi‐Curie amounts of 227Ac in order to take advantage of the energy released from the five a particles that are generated during its decay (Fig. 2.1) to produce electrical power for spacecraft and other devices that must operate for long periods of time in remote locations. An ambitious radioisotope thermoelectric generator (RTG) program was undertaken in Belgium to produce a 250 Wth thermoelectric generator fueled with 18 g of 227Ac (Baetsle´ and Droissart, 1973). A prototype heat source that contained 2 g of 227Ac was prepared but was not put into use (Baetsle´ and

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43

Droissart, 1973). Kirby (Gmelin, 1981) listed the radioisotopes that can be used as thermoelectric heat sources. Of these, 238Pu has been the most suitable; it has been used in almost all U.S. spacecrafts that utilized RTGs, beginning with 2.7‐ W SNAP–3B (Space Nuclear Auxiliary Power) generators for Transit 4A and 4B satellites in 1961 (Lange and Mastal, 1994; U.S. Department of Energy, 1987) and continuing to the three 276‐W general purpose heat source (GPHS) RTGs in the Cassini probe, which was launched in 1997 and reached Saturn in 2004. (See also relevant sections in Chapter 7 and Chapter 15, section 11.2, this book.) 2.9.2

Neutron sources

Isotopes of elements with Z  20 emit neutrons when they are bombarded by 5 MeV a particles. Kirby (Gmelin, 1981) listed the properties of important (a,n) generators. The advantages of 227Ac as a heat source are also those that make it attractive as an (a,n) generator. A few 227Ac (a,n) generators have been constructed and used (Gmelin, 1981). 2.9.3

Alpha‐particle generators for tumor radiotherapy

The 10‐day a emitter 225Ac has desirable properties for destroying rapidly growing cancer cells. After decay of 225Ac to 221Fr, four additional high‐energy a decays and two b decays occur rapidly (Fig. 2.3), delivering 40 MeV of high linear‐energy‐transfer radiation over a range of less than 100 mm. None of the decay events emits hard g‐rays, so that 225Ac can deliver large doses to a tumor cell and negligible doses to surrounding healthy tissue (Tsoupko‐Sitnikov et al., 1996; Khalkin et al., 1997; Boll et al., 2005). To utilize this isotope for therapy, the principal challenges are to generate the isotope free of other radioisotopes, to deliver it to the cancer cell for a long enough period of time, to bind it firmly to the target call, and to retain the daughter radioisotopes (especially the 221Frþ ion) at the target site. The in vivo stability of several macrocyclic complexes of 225 Ac have been evaluated. Deal et al. (1999) found the most promising complex to be that with 1,4,7,10,13,16‐hexaazacyclohexadecane‐N,N0 ,N00 ,N000 ,N0000 ‐hexaacetic acid (HEHA); Ouadi et al. (2000) bifunctionalized an isothiocyanate derivative of HEHA for good covalent bonding to biomolecules. A procedure for delivering 225Ac to tumors via bifunctional chelators related to the ligand 1,4,7,10‐tetraazacyclododecane-1,4,7,10‐tetraacetic acid (DOTA) has been described (McDevitt et al., 2001). Kennel et al. (2000, 2002) evaluated radioimmunotherapy of mice with lung and other tumors using 225Ac–HEHA conjugates with monoclonal antibodies; their studies concluded that the radiotoxicity of 225Ac can only be controlled if conjugates that bind strongly with the daughters as well as with Acþ can be discovered. As described in the earlier paragraph and in Section 2.2.3, 229Th (a, t1/2 ¼7340 years) is an appropriate generator from which 225Ac can be removed periodically. At the time of writing, Oak Ridge National Laboratory is producing

Actinium

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50–60 mCi of 225Ac from 229Th every 8 weeks. Additional shipments of 5–20 mCi of 225Ac are produced by ORNL every 2 weeks from the decay of the 225Ra parent. The 225Ac is shipped to hospitals and other research facilities (Boll et al., 2005). The isotope 225Ac can also serve as a 213Bi generator, which decays with a 45.6‐min half‐life (97.8% b, 2.2% a). The decay is accompanied by a 440‐keV g‐ray, so that 213Bi can be delivered to tumors with a bifunctional chelating agent for radioimmunotherapy as well as for imaging (Pippin et al., 1995; Nikula et al., 1999). Generators have been delivered to hospitals, where radioisotopically pure, chemically active 213Bi can be eluted for radiotherapy, with minimum shielding every 5–6 h for at least 10 days. At the time of writing, the Institute for Transuranium Elements (Joint Research Centre of the European Commission, located at Karlsruhe, Germany) is producing and distributing 225 Ac/213Bi generators. 2.9.4

Actinium-227 as a geochemical tracer

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Nozaki, Y. (1984) Nature, 310, 486–8. Nugent, L. J., Baybarz, R. D., Burnett, J. L., and Ryan, J. L. (1973a) J. Phys. Chem., 77, 1528–39. Nugent, L. J., Burnett, J. L., and Morss, L. R. (1973b) J. Chem. Thermodyn., 5, 665–78. Nugent, L. J., and Vander Sluis, K. L. (1971) J. Opt. Soc. Am., 61, 1112–5. Ouadi, A., Loussouarn, A., Remaud, P., Morandeau, L., Apostolidis, C., Musikas, C., Fauve‐Chauvet, A., and Gestin, J.‐F. (2000) Tetrahedron Lett., 41, 7207–9. Partington, J. R. (1964) A History of Chemistry, Macmillan, London, vol. 4, p. 938. Peppard, D. F., Mason, G. W., Gray, P. R., and Mech, J. F. (1952) J. Am. Chem. Soc., 74, 6081–4. Perey, M. (1939a) C. R. Acad. Sci. Paris, 208, 97–9. Perey, M. (1939b) J. Phys. Radium, 10, 435–8. Peterson, S. (1949) Natl. Nucl. En. Ser., Div. IV, in The Transuranium Elements (eds. G. Seaborg, J. J. Katz, and W. M. Manning), McGraw‐Hill, New York, vol. 14B, pp. 1393–4. Pippin, C. G., Gansow, O. A., Brechbiel, M. W., Koch, L., Molinet, R., van Geel, J., Apostolidis, C., Geerlings, M. W., and Scheinberg, D. A. (1995) in Chemist’s Views of Imaging Centers (ed. A. M. Emran), Plenum Press, New York, pp. 315–25. Poskanzer, A. M. and Foreman, B. M. J. (1961) J. Inorg. Nucl. Chem., 16, 323–36. Rao, C. L. and Gupta, A. R. (1961) J. Chromatogr., 5, 147–52. Rao, C. L., Shahani, C. I., and Mathew, K. A. (1968) Inorg. Nucl. Chem. Lett., 4, 655–9. Rao, V. K., Shahani, C. J., and Rao, C. L. (1970) Radiochim. Acta, 14, 31–4. Rutherford, E. (1904) Phil. Trans. R. Soc. Lond., 204A, 169–219. Rutherford, E. (1911) in Encyclopaedia Britannica, 11th edn, vol. 22, pp. 795–802. Salutsky, M. L. (1962) in Comprehensive Analytical Chemistry (eds. C. L. Wilson and D. W. Wilson), Elsevier, Amsterdam, 1C, pp. 492–6. Salutsky, M. L. and Kirby, H. W. (1956) Anal. Chem., 28, 1780–2. Sani, A. R. (1970) J. Radioanal. Chem., 4, 127–9. Seaborg, G. T. (1994) Origin of the Actinide Concept, in Handbook on the Chemistry and Physics of the Rare Earths (eds. K. A. Gschneidner, L. Eyring, G. R. Choppin, and G. Lander), North‐Holland, Amsterdam, 18, 1–27. Sedlet, J. (1964) Actinium, Astatine, Francium, Polonium, and Protactinium, in Treatise on Analytical Chemistry, Part II, vol. 6 (eds. I. M. Kolthoff, P. J. Elving, and E. B. Sandell), Wiley, New York, pp. 435–610. Sekine, T., Koike, Y., and Sakairi, M. (1967) J. Nucl. Sci. Technol., 4, 308–11. Sekine, T., Koike, Y., and Hasegawa, Y. (1969) Bull. Chem. Soc. Japan, 42, 432–6. Sekine, T. and Sakairi, M. (1969) Bull. Chem. Soc. Jpn., 42, 2712–3. Shahani, C. J., Mathew, K. A., Rao, C. L., and Ramaniah, M. V. (1968) Radiochim. Acta, 10, 165–7. Shannon, R. D. (1976) Acta Crystallogr., A32, 751–67. Sinitsyna, G. S., Shestakova, I. A., Shestakov, B. I., Plyushcheva, N. A., and Malyshev, N. A., Belyatskii, A. F. (1977) Tezisy Dokl.‐Konf. Anal. Khim. Radioakt., Nauka, Moscow. Sinitsyna, G. S., Shestakova, I. A., Shestakov, B. I., Plyushcheva, N. A., Malyshev, N. A., Belyatskii, A. F., and Tsirlin, V. A. (1979) Sov. Radiochem., 21, 146–51; Radiokhimiya, 21, 172–7. Skarnemark, G. and Skalberg, M. (1985) Int. J. Appl. Radiat. Isot., 36, 439–41.

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CHAPTER THREE

THORIUM Mathias S. Wickleder, Blandine Fourest, and Peter K. Dorhout 3.6 Thorium metal 60 3.7 Important compounds 64 3.8 Solution chemistry 117 References 134

3.1 3.2 3.3 3.4

Historical 52 Nuclear properties 53 Occurrence of thorium 55 Thorium ore processing and separation 56 3.5 Atomic spectroscopy of thorium 59

3.1

HISTORICAL

In 1815 Berzelius analyzed a rare mineral from the Falun district. He assumed that the mineral contained a new element, which he named thorium after the ancient Scandinavian god of thunder and weather, Thor (Weeks and Leicester, 1968). Unfortunately, 10 years later the mineral turned out to be simply xenotime, e.g. yttrium phosphate. However, in 1828, Berzelius was given a mineral by the Reverend Hans Morten Thrane Esmark. In that mineral Berzelius really discovered a new element and gave it the same name (Berzelius, 1829; Gmelin, 1955, 1986a; Weeks and Leicester, 1968). Consequently, he called the mineral from which he isolated the new element thorite. It is a silicate that contains significant amounts of uranium and should therefore be written as (Th,U)SiO4. Although thorium was discovered in 1828, it virtually had no application until the invention of the incandescent gas mantle in 1885 by C. Auer von Welsbach. Thereafter the application of thorium developed into a wide array of products and processes (Gmelin, 1988b). Besides the above‐mentioned incandescent gas mantles, the production of ceramics, carbon arc lamps, and strong alloys may serve as examples. To be mentioned is also its use as coating for tungsten welding rods, because it provides a hotter arc. Furthermore, when added to refractive glass, it allows for smaller and more accurate camera lenses. As minor important applications, the use of ThO2 in producing more heat‐resistant laboratory crucibles and its occasional use as a catalyst for the oxidation of ammonia to nitric acid and other industrial chemical reactions can be 52

Nuclear properties

53

mentioned. Nevertheless, during the last decade the demand for thorium in non‐ nuclear applications has sharply decreased due to environmental concerns related to its radioactivity. The radioactivity of thorium is helpful for the dating of very old materials, e.g. seabeds or mountain ranges. Maybe the largest potential for thorium is its usage in nuclear energy. This is because 232Th can be converted by thermal (slow) neutrons to the fissionable uranium isotope 233U via the following reaction sequence: 232

b

b

Thðn;
Þ ! 233 Th ! 233 Pa ! 233 U

Fission of the 233U can provide neutrons to start the cycle again. This cycle of reactions is known as the thorium cycle (Seaborg et al., 1947; Katzin, 1952). Conversion of 232Th into 233U provides the possibility to gain large amounts of slow‐neutron‐fissile material, several times the amount of uranium naturally present on Earth, and several hundred times the amount of the naturally occurring fissile uranium isotope 235U (Seaborg and Katzin, 1951). A number of advantages of thorium‐based nuclear fuels exist in comparison with the presently utilized uranium–plutonium fuels (Rand et al., 1975; Trauger, 1978). These include the inherent detectability of 233U, its higher neutron yield, the fact that 233U, unlike 239Pu, can be mixed with 238U so that it cannot directly be used in weapons manufacture, and the superior physical properties of thorium‐based fuels that enhance reactor core safety and performance. The disadvantage of the use of thorium‐based fuels is that thorium must be irradiated and reprocessed before the advantages of 232Th can be realized. This reprocessing step, requiring more advanced technology than that needed for uranium fuels, and other factors have projected greater costs for thorium fuels. The nuclear technology has nevertheless matured with the development of high‐temperature gas‐cooled reactors. 3.2

NUCLEAR PROPERTIES

Thorium refined from ores free of uranium would be almost monoisotopic 232 Th, with less than one part in 1010 of 228Th (radiothorium) produced by its own radioactivity decay chain (4n family). If the ore contains uranium, as is usually the case, practically undetectable concentrations of 231Th (uranium Y) and 227Th (radioactinium) are present, products of the (4n þ 3) decay chain that starts with 235U. Also present are greater quantities of 230Th (ionium), as well as lesser amounts of 234Th (uranium X1), which originate from the (4n þ 2) decay chain whose progenitor is 238U. 229Th is the first product in the (4n þ 1) decay series (English et al., 1947; Hagemann et al., 1947, 1950) derived from man‐made 233U formed as indicated in Section 3.1. The remaining thorium isotopes listed in Table 3.1 (see also Appendix II) are also synthetic, being formed directly by bombardment of lead or bismuth targets with energetic

Table 3.1

Nuclear properties of thorium isotopes.a

Mass number

Half‐life

Mode of decay

209 210 211 212 213 214 215

3.8 ms 9 ms 37 ms 30 ms 140 ms 100 ms 1.2 s

a a a a a a a

216 217 218

28 ms 0.237 ms 0.109 μs

a a a

219 220 221

1.05 μs 9.7 μs 1.68 ms

a a a

222 223

2.8 ms 0.60 s

a a

224

1.05 s

a

225

8.0 min

a 90% EC 10%

226

30.57 min

a

227

18.68 d

a

228

1.9116 yr

a

229

7.340  103 yr

a

230

7.538  104 yr

a

231

25.52 h

b−

232

1.405  1010 yr > 1  1021 yr

a SF

Main radiations (MeV) a 8.080 a 7.899 a 7.792 a 7.82 a 7.691 a 7.686 a 7.52 (40%) 7.39 (52%) a 7.92 a 9.261 a 9.665 a 9.34 a 8.79 a 8.472 (32%) 8.146 (62%) a 7.98 a 7.32 (40%) 7.29 (60%) a 7.17 (81%) 7.00 (19%) g 0.177 a 6.478 (43%) 6.441 (15%) g 0.321 a 6.335 (79%) 6.225 (19%) g 0.1113 a 6.038 (25%) 5.978 (23%) g 0.236 a 5.423 (72.7%) 5.341 (26.7%) g 0.084 a 4.901 (11%) 4.845 (56%) g 0.194 a 4.687 (76.3%) 4.621 (23.4%) g 0.068 b− 0.302 g 0.084 a 4.016 (77%) 3.957 (23%)

Method of production S þ 182W Cl þ 181Ta 35 Cl þ 181Ta 176 Hf(40Ar,4n) 206 Pb(16O,9n) 206 Pb(16O,8n) 206 Pb(16O,7n) 32 35

206

Pb(16O,6n) Pb(16O,5n) 206 Pb(16O,4n) 209 Bi(14N,5n) 206 Pb(16O,3n) 208 Pb(16O,4n) 208 Pb(16O,3n) 206

208 208 228 208 229 231 230

Pb(16O,2n) Pb(18O,3n) U daughter Pb(22Ne,a2n) U daughter Pa(p,a3n) U daughter

nature nature 233

U daughter

nature nature 230 Th(n,g) nature

Occurrence of thorium

55

Table 3.1 (Contd.) Mass number

Half‐life

Mode of decay

233

22.3 min

b−

234

24.10 d

b−

235 236

7.1 min 37.5 min

b− b−

237 238

5.0 min 9.4 min

b− b−

a

Main radiations (MeV) b− 1.23 g 0.086 b− 0.198 g 0.093 g 0.111

Method of production 232

Th(n,g)

nature 238

U(n,a) U(g,2p) U(p,3p) 18 O þ 238U 18 O þ 238U 238 238

Appendix II.

multi‐nucleon projectiles, by decay of lightweight uranium isotopes, which are themselves synthetic and formed by nuclear bombardment, or by other miscellaneous nuclear reactions. Uranium ores that are relatively thorium‐free can be processed to prepare multigram amounts of material with significant proportions of ionium, 230Th. From one unselected ore residue, after removal of uranium, thorium was obtained (Hyde, 1952, 1960) that was 26.4% ionium and 73.6% 232Th (Roll and Dempster, 1952).

3.3

OCCURRENCE OF THORIUM

Two volumes of the Gmelin Handbook of Inorganic Chemistry deal with the natural occurrence of thorium and give a comprehensive review of known thorium minerals (Gmelin, 1990a, 1991a). So only the most important features will be emphasized here. Thorium has a much wider distribution than is generally thought. In the Earth’s crust it is three times as abundant as Sn, twice as abundant as As, and nearly as abundant as Pb and Mo. It occurs in the tetravalent state in nature and is frequently associated with U(IV), Zr(IV), Hf(IV), and Ce(IV) but also with the trivalent rare earth elements that are relatively close in ionic radii (Cuthbert, 1958; Frondel, 1958; Shannon, 1976). Due to the isotypism of ThO2 and UO2 solid state solutions can be formed and depending on the uranium content the mixtures are named thorianite (75– 100 mol% ThO2), uranothorianite (25–75 mol% ThO2), thorian uraninite (15– 25 mol% ThO2) and uraninite (0–15 mol% ThO2). A second mineral with a high thorium content is thorite, ThSiO4, from which the element has originally been discovered. Thorite has the tetragonal zircon‐type of structure but also a monoclinic variant of ThSiO4 is known, which is called huttonite (Taylor and

Thorium

56

Table 3.2 Thorium content of various minerals. Accessory mineral

Th (ppm)

monazite allanite zircon titanite epidote apatite magnetite xenotime

25000 to 2  105 1000 to 20000 50 to 4000 100 to 600 50 to 500 20 to 150 0.3 to 20 Low

4 Ewing, 1978). In both modifications of ThSiO4, substitution of PO3 4 for SiO4 4þ is frequently observed with additional replacement of Th by trivalent rare earth − ions for charge compensation. SiO4 4 ions may be also replaced by OH groups according to Th(SiO4)1–x(OH)4x leading to a new mineral, thorogummite. However, in all the minerals given in Table 3.2, Th occurs as the minor constituent. From these minerals, monazite is of significant commercial interest because it is distributed throughout the world, and some of the deposits are very large. Monazite is a phosphate of high specific gravity that is found in the form of yellow to brown sand in nature (monazite sand). The chemical inertness of monazite makes it hard to process.

3.4

THORIUM ORE PROCESSING AND SEPARATION

Monazite can be only attacked by strong acid, which essentially transforms the phosphate ion to H2 PO 4 and H3PO4 and leaves the metal ions as water‐soluble salts, or by strong alkali, which transforms the insoluble phosphates to insoluble metal hydroxides that can easily be dissolved in acid after removal from the supernatant solution of alkali phosphates. Thorium in monazite follows the rare earths in either the acid or the alkali processes. Thorium can be separated from the rare earths in strong sulfuric acid solution (Fig. 3.1) by partial dilution and reduction of acidity (by ammonia addition) to about pH 1.0, at which point hydrated thorium phosphates, containing only small amounts of entrained rare earths, precipitate (Fig. 3.2). The acidity must be reduced to about pH 2.3 to ensure precipitation of the bulk of the rare earths. (Any uranium present in the process solution is separated from the rare earths at this step.) The crude precipitate of thorium phosphate is then treated with alkali to remove undesired sulfate and phosphate anions, and the thorium hydroxide residue may then be dissolved in nitric acid for subsequent

Thorium ore processing and separation

57

Fig. 3.1 Simplified schematic diagram of sulfuric acid digestion of monazite sand and recovery of thorium, uranium, and the rare earths.

purification. Purification is achieved efficiently by solvent extraction of the thorium with tri(n‐butyl)phosphate (TBP) dissolved in kerosene, a procedure that separates thorium nitrate from rare earths and other non‐extractable species. Numerous further extractants have been employed as pointed out in the Gmelin Handbook (Gmelin, 1985a). The solid reaction product of the alkaline digestion of monazite (Fig. 3.3) may be dissolved in acid after separation from the supernatant solution. The solubility of the thorium‐containing fraction, however, is a function of the conditions under which the alkaline digestion is performed. Too prolonged

58

Thorium

Fig. 3.2 Effect of acidity on precipitation of thorium, rare earths, and uranium from a monazite–sulfuric acid solution of Idaho and Indian monazite sands: agitation time 5 min; dilution ratio, 45 to 50 parts water per one part monazite sand; digestion ratio of 93% sulfuric acid to digestion sands, 1.77; neutralizing agent, 3.1% ammonium hydroxide (Cuthbert, 1958).

digestion at too high temperature may produce a product in which a large fraction of the thorium will not react readily with the acid used to dissolve the hydroxide cake. Presumably this is a consequence of the formation of ThO2. Depending on whether hydrochloric, nitric, or sulfuric acid is used to dissolve the hydroxide cake, different procedures may be used in subsequent purification. Assuming the use of hydrochloric acid, which involves the fewest complications, a solution of thorium and rare earth chlorides is obtained. Differential precipitation of thorium from this solution again offers several choices: hydroxide (preferred), peroxide, or phosphate may be used to precipitate the thorium, or precipitation by carbonate may be used to separate the rare earths from thorium (and uranium), which form soluble anionic complexes. Final purification of thorium, again, is preferably made by solvent extraction (Marcus and Kertes, 1969; Gmelin, 1985a), but also chromatographic methods are applied (Kiriyama and Kuroda, 1978; Mayankutty et al., 1982; Gmelin, 1990c, 1991b). Thorium may also be recovered as a by‐product from the treatment of uraninite or uranothorianite to obtain uranium. The thorium remaining in the solution of sulfuric acid after removal of the uranium is extracted into kerosene with the aid of long‐chain amines. The thorium is part of a complex sulfate anion, which accompanies the protonated cationic amine into the organic phase. Neutralization of the quaternary ammonium cation precipitates the thorium from the organic phase or allows it to be back‐extracted into an aqueous phase.

Atomic spectroscopy of thorium

59

Fig. 3.3 Simplified schematic diagram of caustic soda digestion of monazite sand and recovery of thorium, uranium, and the rare earths.

3.5

ATOMIC SPECTROSCOPY OF THORIUM

The atomic spectroscopy of thorium provides not only information about the electronic states of thorium but also clues to the properties expected for elements of higher atomic number. The electronic structure of thorium and the related spectra will be discussed in more detail in Chapter 16 and are only summarized briefly here. Further details are also given in a volume of Gmelin’s Handbook (Gmelin, 1989). The four valence electrons of the neutral atom have available to them, in principle, the 5f, 6d, 7s, and 7p orbitals. The stable ground state configuration of the neutral thorium atom turns out to be 6d27s2 (3F2) (Giacchetti et al., 1974).

Thorium

60

The 6d37s (5F1) level is at higher energy by 5563.143 cm−1 and it is only at 7795.270 cm−1 that one encounters 5f6d7s2 (3H4). Still higher lie 6d7s27p (10783.153 cm−1), 6d27s7p (14465.220 cm−1), and 5f6d27s (15618.98 cm−1) (Zalubas, 1968). The ionization potential of neutral Th was recently measured by resonance ionization mass spectrometry (RIMS) (Ko¨hler et al., 1997) as 6.3067(2) eV. The value obtained earlier (Sugar, 1974; Ackermann and Rauh, 1972) by extrapolation of spectroscopic data was 6.08 eV. The ground level of singly ionized Th is d2s, followed by ds2 (1859. 938 cm−1), fs2 (4490.256 cm−1), fds (6168.351 cm−1), d3 (7001.425 cm−1), and fd2 (12485.688 cm−1) (Zalubas and Corliss, 1974). It is a major step up in energy to configurations with either p contribution or to configurations that contain paired f‐electrons: dsp is at 23372.582 cm−1, followed by f2s (24381.802 cm−1), fsp (26488.644 cm−1), d2p (28243.812 cm−1), fdp (30 452.723 cm−1), s2p (31625.680 cm−1), and f2d (32620.859 cm−1). The ground state of doubly ionized thorium is 5f6d but the 6d2 configuration is only 63.267 cm−1 and the 5f7s is 2527.095 cm−1 higher (Racah, 1950). These are followed by 6d7s (5523.881 cm−1), 7s2 (11961.133 cm−1), 5f2 (15148.519 cm−1), 5f7p (33562. 349 cm−1), 6d7p (37280.229 cm−1), and 7s7p (42259.714 cm−1). These trends are continued in the triply ionized form (Klinkenberg and Lang, 1949), in which the ground level is 5f, and 6d is at 9193.245 cm−1, 7s at 23130.75 cm−1, and 7p at 60239.10 cm−1. Thus, with increasing ionic charge, configurations that include 5f electrons are stabilized with respect to others and the configurations containing 7p electrons become grossly destabilized. Effects in 7s and 6d systems are less but are still significant. The stabilization of the 5f electron in the triply charged ion is not sufficient however to make triply charged thorium a stable chemical species. The stable form is tetrapositive Th4þ, in which only the radon core of electrons is present. Solid metallic thorium with the ground state configuration d2s2 has the 5f electrons in a reasonably broad energy band (Koelling and Freeman, 1971), about 5 eV above the Fermi level of 7.5–8.0 eV. This presumably is because the fds2 level lies so low and interacts with the d2s2 level. Electron‐binding energies for the various core levels of the atom have been determined (Nordling and Hagstro¨m, 1964), and the X‐ray transitions have been determined with precision (Bearden, 1967; Bearden and Burr, 1967; Murthy and Redhead, 1974).

3.6

THORIUM METAL

A comprehensive treatment of the physical and chemical properties of thorium metal is given in the Gmelin Handbook (Gmelin, 1989, 1997). A brief summary on the most important properties shall be given here. The preparation of thorium has been done by reducing halides or double halides by sodium, potassium, or calcium (Berzelius, 1829; Chydenius, 1863;

Thorium metal

61

Nilson, 1876; Chauvenet, 1911). Furthermore, ThCl4 can be reduced by sodium or electrolysis can be applied to a melt of thorium chloride or fluoride in sodium chloride or potassium chloride (Matignon and Delepine, 1901; Moissan and Ho¨nigschmid, 1906; von Bolton, 1908; von Wartenberg, 1909; Chauvenet, 1911; Kaplan, 1956). Also, ThO2 can be used as starting material and various reductants may be used (Ruff and Brintzinger, 1923; Marden and Rentschler, 1927). Care has to be taken when carbon or silicon is used because the formation of ´ tard, 1896, carbides and silicides may occur (Berzelius, 1829; Moissan and E ¨ 1897; Honigschmid, 1906a,b). In the so‐called ‘Sylvania process’ calcium is used as the reducing agent (Dean, 1957; Smith et al., 1975). Other reduction processes involve ThO2 and aluminum or magnesium (Winkler, 1891; Leber, 1927). Both reactions are preferably carried out in the presence of zinc, making the reduction process thermodynamically favorable due to the formation of the intermetallic compound Th2Zn17 (Spedding et al., 1952). Zinc can easily be removed by vacuum distillation and leaves the metal mainly as a powder (Meyerson, 1956; Fuhrman et al., 1957). Zinc is usually introduced as chloride or fluoride in the process (Briggs and Cavendish, 1971), but attempts have been made to use a zinc–magnesium alloy as reductant (Capocchi, 1971). Unusual reductions include, for example, the reaction of ThCl4 with DyCl2 (Mikheev et al., 1993). A method leading to high‐purity thorium is the thermal decomposition of ThI4 on a hot tungsten filament, known as the van Arkel–de Boer process (van Arkel and de Boer, 1925). This reaction is also used for the purification of thorium because the iodine formed in the reaction can be used to transport the crude metal from the low‐temperature source to the hot wire. Another method to gain very pure thorium is the electrotransport that refines the high‐grade thorium from the van Arkel–de Boer process further to a material containing less than 50 ppm impurities in total (Peterson and Schmidt, 1971). Thorium appears as a bright silvery metal that has the highest melting point among the actinide elements while its density is the lowest one in the series except for Ac. Under ambient conditions, Th adopts the face‐centered cubic (fcc) structure of copper that transforms to the body‐centered cubic (bcc) structure of tungsten above 1360 C. Under high pressure, a third modification with a body‐centered tetragonal lattice has been observed (Bridgman, 1935; Vohra, 1991, 1993; Vohra and Akella, 1991, 1992). Note that the transition conditions between the modifications depend remarkably on the amount of impurities in the metal (Smith et al., 1975; Oetting et al., 1976). The same is true for the properties like melting point, density (James and Straumanis, 1956), resistance, and others shown in Table 3.3, which summarizes selected properties of thorium as reported in two monographs (Smith et al., 1975; Oetting et al., 1976), and in the Gmelin Handbook (Gmelin, 1997). Thorium metal is paramagnetic (ground state 6d27s2) and shows a specific magnetic susceptibility of 0.412  4π  10−9 m3 kg−1 at room temperature (Greiner and Smith, 1971). The magnetic susceptibility is nearly

Thorium

62

Table 3.3 Some physical properties of thorium metal. melting point crystal structure face‐centered cubic up to 1633 K body‐centered cubic from 1633–2023 K body‐centered tetragonal at high pressure atomic radius (from fcc structure ) density from X‐ray lattice parameters bomb reduced, as‐cast arc melted, van Arkel metal enthalpy of sublimation (298 K)a vapor pressure of the solid (1757–1956 K) vapor pressure of the liquid (2020–2500 K) enthalpy of fusion elastic constants Young’s modulus shear modulus Poisson’s ratio compressibility coefficient of thermal expansion (298–1273 K) electric resistivity electrorefined metal (298 K) temperature coefficient of resistance thermal conductivity (298 K) work function Hall coefficient (297 K) emissivity (solid, 1600 K) a

2023 K ˚ (298 K) a ¼ 5.0842 A ˚ (1723 K) a ¼ 4.11 A ˚ , c ¼ 4.411 A ˚ (102 GPa) a ¼ 2.282 A ˚ 1.798 A 11.724 g cm−3 11.5–11.6 g cm−3 11.66 g cm−3 602 ± 6 kJ mol−1 log p(atm) ¼ –28780 (T/K)−1 + 5.991 log p(atm) ¼ −(29770 ± 218) (T/K)−1 – (6.024 ± 0.098) 14 kJ mol−1 7.2  107 kPa 2.8  107 kPa 0.265 17.3  10−8 cm2 N−1 12.5  10−6 K−1 15.7  10−6 Ω cm 3.6  10−3 K−1 0.6 W cm−1 K−1 3.49 eV –11.2  10−5 cm3 C−1 0.31

Cox et al. (1989).

temperature‐independent but it depends on the amount of impurities or dopants, respectively (Sereni et al., 1987). Thorium is superconducting at low temperature (Meissner, 1929; de Haas and van Alphen, 1931). The transition temperature Tc is between 1.35 and 1.40 K, the critical magnetic field Hc has been found to be (159.22 ± 0.10) G for a high‐purity sample (Decker and Finnemore, 1968). Thorium is an excellent example of a weakly coupled type‐I superconductor that exhibits a complete Meissner effect and whose critical field curve Hc(T) has a parabolic temperature dependence and is in good agreement with the predictions of the theory of Bardeen, Cooper, and Schrieffer (Bardeen et al., 1957). The pressure dependence of Hc has been determined (Fertig et al., 1972)

Thorium metal

63

and the specific heat discontinuity at Tc has been reported by several authors to be around 8.4 mJ mol−1 K−1 (Gordon et al., 1966; Satoh and Kumagai, 1971, 1973; Luengo et al., 1972a,b). Calculations on electron–phonon coupling have been also reported (Winter, 1978; Skriver and Mertig, 1985; Allen, 1987; Skriver et al., 1988). The pressure dependence of the critical temperature has been followed up to 20 GPa (Palmy et al., 1971; Rothwarf and Dubeck, 1973). Below 2.5 GPa Tc decreases linearly with pressure. The decrease flattens to a minimum around 7.4 GPa, increases slightly up to 10 GPa, before it smoothly decreases again. The pressure dependence of Tc has also been recently examined theoretically (Rosengren et al., 1975; Mahalingham et al., 1993). Furthermore, the dependence of Tc on impurities has been investigated (Guertin et al., 1980). The chemical reactivity of thorium is high. It is easily attacked by oxygen, hydrogen (Winkler, 1891; Matignon and Delepine, 1901; Sieverts and Roell, 1926; Nottorf et al., 1952), nitrogen (Matignon, 1900; Kohlschu¨tter, 1901; Matignon and Delepine, 1901), the halogens (Nilson, 1876; Moissan and E´tard, 1896, 1897; von Wartenberg, 1909), and sulfur (Berzelius, 1829; Nilson, 1876; von Wartenberg, 1909) at elevated temperatures. Also carbon and phosphorus are known to form binary compounds with thorium (Strotzer et al., 1938; Meisel, 1939; Wilhelm and Chiotti, 1950). Finely divided thorium is even pyrophoric (Raub and Engles, 1947). The reaction of bulky thorium with air under ambient conditions is low, but nevertheless corrosion is observed according to the investigations of several authors. Thorium reacts vigorously with hydrochloric acid. The reaction with hydrochloric acid always leaves a certain amount of a black residue (12 to 15%) behind, which was first thought to be ThO2 that was originally present in the metal (Matignon and Delepine, 1901; Meyer, 1908; von Wartenberg, 1909). As discussed in Section 3.7.3, other studies have suggested that a lower‐valent thorium oxide hydrate, ThO·H2O, is formed but it is much more likely that this compound is in fact an oxide hydride containing hydroxide and chloride ions according to ThO(X)H (X ¼ combination of OH− and Cl−) (von Bolton, 1908; Karstens, 1909, Katzin, 1944, 1958; Karabash, 1958; Katzin et al., 1962). This assumption is also supported by mass spectroscopic investigations that show Cl− to be present in the residue (Ackermann and Rauh, 1973a). The reaction of thorium with other acids occurs slowly, with nitric acid even passivation is observed (Smithells, 1922; Schuler et al., 1952). The latter can be overcome by adding small amounts of fluoride or fluorosilicate ions. A great number of thorium alloys are known, including those with iron, cobalt, nickel, copper, gold, silver, platinum, molybdenum, tungsten, tantalum, zinc, bismuth, lead, mercury, sodium, beryllium, magnesium, and aluminum. Other systems, like Th/Cr and Th/U, are simply eutectics, and complete miscibility is found in the liquid and solid states with cerium. An overview of thorium alloys with main group metals can be found in the Gmelin Handbook (Gmelin, 1992a, 1997).

Thorium

64 3.7

IMPORTANT COMPOUNDS

As Chapter 19 is devoted to the thermodynamic properties of the actinides and their compounds, data such as enthalpies of formation or entropies will not be given here, except when needed for the clarity of the discussion. 3.7.1

Hydrides

Reaction of thorium with hydrogen, and formation of two hydrides, ThH2 and Th4H15, has been known for more than a century (Winkler, 1891). A substoichiometric dihydride with the fluorite‐type of structure was observed by X‐ray diffraction (XRD) along with the tetragonal ThH2–x in a preparation of overall composition ThH1.73 (Korst, 1962) as well as in dihydrides containing some ThO2 (Peterson et al., 1959). The well‐known dihydride, which can be significantly substoichiometric, has a tetragonal structure (Nottorf et al., 1952; Rundle et al., 1952; Flotow and Osborne, 1978). The compound contains two metal atoms in the unit cell and is isotypic with ZrH2 (Rundle et al., 1948a; Nottorf et al., 1952). The higher hydride (Matignon and Delepine, 1901; Sieverts and Roell, 1926; Rundle et al., 1948a, 1952; Nottorf et al., 1952; Zachariasen, 1953; Mueller et al., 1977), Th4H15 (¼ ThH3.75), has a unique cubic structure, with the Th atom in 12‐fold coordination of hydrogen atoms. The hydrogen atoms are coordinated by three and four thorium atoms as may be expressed by the formula ThH9/3H3/4 according to Niggli’s formalism. The structure has also been determined for the deuterated analog Th4D15 (Mueller et al., 1977). Th4H15 was the first metal hydride to be found to show superconductivity (Satterthwaite and Toepke, 1970; Satterthwaite and Peterson, 1972; Dietrich et al., 1974). The transition temperature for superconductivity is 7.5–8 K, which is narrow, but not isothermal. Metallic conduction is exhibited at room temperature. Both the hydride and the deuteride are superconducting, with no apparent isotope effect. The existence of another crystalline form, with a 1% tetragonal distortion, that is non‐superconducting has been suggested (Caton and Satterthwaite, 1977). The transition temperature is reversibly pressure‐sensitive, with a slope of about 42 mK kbar−1, up to a pressure of about 28 kbar. The heat capacities of ThH2 and Th4H15 have been measured from 5 to 350 K (Schmidt and Wolf, 1975; Miller et al., 1976; Flotow and Osborne, 1978). As pointed out in more detail in Chapter 19, experimental values have been extrapolated to 800 K by Flotow et al. (1984). The electronic structure of these binary thorium hydrides has been investigated by photoelectron spectroscopy (Weaver et al., 1977) and nuclear magnetic resonance (NMR) spectroscopy (Schreiber, 1974; Lau et al., 1977; Peretz et al., 1978; Maxim et al., 1979). Powdered or sintered thorium metal reacts immediately and exothermically with hydrogen at room temperature, whereas massive metal may require heating to 300–400 C before reaction takes place. For the reaction with massive

Important compounds

65

metal, an induction period that is a function of the impurity content of the metal was found (Nottorf et al., 1952). In general, it is taken for granted that a consequence of the reaction of hydrogen on massive metal is a crumbling and powdering of the mass. However, it has been found (Satterwaithe and Peterson, 1972) that, at temperatures around 850 C, massive metal yields massive ThH2, and then massive Th4H15, whereas even at 500 C the reaction fractures and cracks the massive metal. It is assumed that at high temperature, there is a sufficiently close match between the crystal structures of the metal and the hydride formed at that temperature that the incorporation of hydrogen can proceed without causing disruption of the solid. At 900 C, in high vacuum, thorium hydride is completely decomposed to its elements. The decomposition product is grey to black, powdered, or in the form of an easily disintegrated mass. When it is desired to prepare thorium metal for some subsequent reaction, formation and decomposition of the hydride is generally used to accomplish this goal. The dissociation pressures of the two hydrides have been reported as (Nottorf et al., 1952): log pðmmHgÞ ¼ 7700 ðT=KÞ1 þ 9:54 ðTh=ThH2 systemÞ log pðmmHgÞ ¼ 4220 ðT=KÞ1 þ 9:50

ðThH2 =Th4 H15 systemÞ

Flotow et al. (1984) discuss in greater detail the hydrogen pressures associated with the Th–H2 system as a function of the hydrogen composition of the solid phases and the temperatures. Thorium hydride reacts readily with oxygen to form ThO2. Many hydride preparations are in fact pyrophoric. ThO2 can also be formed smoothly by reaction of thorium hydride with steam at 100 C. The reactions with oxygen and with steam are typical for the procedures commonly used for the synthesis of binary compounds of thorium. Pure thorium is necessary to prepare thorium hydride that is free of oxygen or moisture. Subsequent manipulation in the absence of air or moisture then assures the formation of pure binary compounds. Thus, in the range of 250–350 C, the hydride reacts smoothly with halogens as well as with hydrogen compounds of the halogens, sulfur, phosphorus, or nitrogen to give the corresponding binary compounds of thorium (Foster, 1945, 1950; Lipkind and Newton, 1952). Methane or carbon dioxide does not react with thorium hydride. A number of ternary hydrides and deuterides has been reported (Table 3.4). The iron compounds Th2Fe17Dx are structurally related to the respective alloy Th2Fe17 and show interesting magnetic properties (Isnard et al., 1993). The deuterides ThZr2Dx can be described as stuffed variant of the cubic Laves phases as it has been shown by neutron diffraction (van Houten and Bartram, 1971; Bartscher et al., 1986). ThZr2H7þx (and also the hexagonal ThTi2H6þx) combine an extremely large amount of hydrogen per unit volume with relatively low equilibrium vapor pressures of hydrogen at elevated temperatures. Both of

Thorium

66

Table 3.4 Crystallographic data of thorium hydrides and deuterides. Lattice parameters Compound

˚) Space group a (A

ThH2 Th4H15 Th4D15 Th2Fe17D4.956 Th2Fe17D4.668 Th6Mn23D16.2 Th6Mn23D16 Th6Mn23D16 Th6Mn23D28.5 ThZr2D6 ThZr2D3.6 ThZr2D4.8 ThZr2D6.3 ThNi2D2 ThNi2D2.6 Th2AlD2 Th2AlD3 Th2AlD4 Th2AlD3.71 Th2AlD2.75 Th2AlD2.29

I4/mmm I43d I43d R3m R3m Fm3m Fm3m P4/mmm Fm3m Fd3m Fd3m Fd3m Fd3m P6/mmm P6/mmm I4/mcm I4/mcm I4/mcm I4/mcm P42m I4/mcm

4.055 9.11 9.11 8.7116 8.682 12.922 12.921 9.076 13.203 9.151 9.042 9.112 9.154 3.87 4.405 7.702 7.676 7.629 7.6260 7.6796 7.7014

˚ ) c (A ˚) b (A

References

Flotow and Osborne, 1978a Mueller et al. (1977) Mueller et al. (1977) 12.624 Isnard et al. (1993) 12.56 Isnard et al. (1993) Hardman et al. (1980) Hardman et al. (1980) 12.961 Hardman‐Rhyne et al. (1984) Hardman‐Rhyne et al. (1984) Bartscher et al. (1986) Bartscher et al. (1986) Bartscher et al. (1986) Bartscher et al. (1986) 3.951 Andresen et al. (1984) 4.360 Andresen et al. (1984) 6.23 Bergsma et al. (1961) 6.383 Bergsma et al. (1961) 6.517 Bergsma et al. (1961) 6.5150 Sorby et al. (2000) 19.073 Sorby et al. (2000) 6.2816 Sorby et al. (2000) 4.965

˚ . The F‐centered cell has the diagonal of These authors use the F4/mmm setting with a ¼ 5.734 A the ab‐plane as axis, i.e. square root of twice the a axis of the I‐centered cell.

a

these ternary hydrides are apparently stable in air. Unlike thorium hydride itself, the Th–Zr hydride is not superconducting (Satterthwaite and Peterson, 1972). Also the nickel phases ThNi2Dx are derived from the alloy ThNi2 and show the deuterium atom in tetrahdral interstices of the metal atom network (Andresen et al., 1984). The thorium manganese compounds Th6Mn23Dx have been investigated frequently with respect to the D atom distribution in the lattice (Hardman et al., 1980, 1982; Jacob, 1981; Carter, 1982; Hardman‐ Rhyne et al., 1984). Furthermore, the ternary aluminum hydrides Th2AlDx have been reported in great detail (Bergsma et al., 1961; Sorby et al., 2000). Other hydrides, for example with cobalt and palladium are known, however not very well characterized in the most cases (Buschow et al., 1975; Oesterreicher et al., 1976). 3.7.2

Borides, carbides, and silicides

Three binary thorium borides are well characterized (du Jassonneix, 1905; Allard, 1932; Stackelberg and Neumann, 1932; Lafferty, 1951; Post et al., 1956; Konrad et al., 1996). ThB6 contains a network of linked [B6] octahedra;

Important compounds

67

in ThB4, [B2] dumbbells accompany the octahedra (Brewer et al., 1951; Zalkin and Templeton, 1951; Blum and Bertaut, 1954). Investigations of the thorium– boron system at low boron concentrations showed that non‐stoichiometric varieties of ThB4 can be prepared (Rand et al., 1975; Chiotti et al., 1981). On the other hand, certain impurities (for example ThO2) have been suggested to be accountable for the non‐stoichiometry (Brewer et al., 1951). The third boride, ThB12, is isotypic with UB12 (Cannon and Hall, 1977; Cannon and Farnsworth, 1983). Furthermore, the borides ThB66 and ThB76 have been reported (Naslain et al., 1971; Schwetz et al., 1972), but it was not clear whether they are truly thorium–boron phases or if they are a metal‐stabilized form of a boron allotrope. Various ternary thorium borides have been prepared, especially those containing transition metals. The orthorhombic borides Th2MB10 were obtained from the elements by arc melting and show a structure that is closely related to that of ThB6 (Konrad and Jeitschko, 1995). Borides of the composition ThMB4 have been recognized for M ¼ V, Mo, W, Re, Cr, and Mo (Pitman and Das, 1960; Rogl and Nowotny, 1974; Konrad et al., 1996). The crystal structures have been determined for M ¼ Cr and Mo, in which the boron atoms form infinite layers with the metal atoms in between similar to MgB2. The chromium compound ThCr2B6 is isotypic with CeCr2B6 and shows metallic conduction and Pauli paramagnetism (Konrad and Jeitschko, 1995). The hexagonal borides ThIr3B2 and ThRu3B2 have been characterized magnetically and structurally. They contain discrete boride ions in prismatic coordination of the platin metal atoms (Hiebl et al., 1980; Ku et al., 1980). The magnetic properties have also been also determined for the rather complicated borides R2–xThxFe14B (R ¼ Y, Dy, Er) (Pedziwiatr et al., 1986). Further boron‐containing thorium compounds are the borohydrides Th(BH4)4, LiTh(BH4)5, and Li2Th(BH4)6 (Ehemann and No¨th, 1971). They contain the tetrahedral BH4− ion. Carbides of thorium have been discussed in great detail in the Gmelin Handbook (Gmelin, 1992b). Thus only the most important items shall be given here briefly. Binary thorium carbides were obtained by the reaction of ThO2 with carbon or the direct fusion of the elements (Troost, 1883; Moissan and E´tard, 1896, 1897; Wilhelm and Chiotti, 1949, 1950). Three compositions, ThC2, Th2C3, and ThC, are known (Fig. 3.4). ThC2 occurs in three different modifications. At room temperature, a monoclinic unit cell is found (Jones et al., 1987). Between 1430 and 1480 C, a rotation of the C2 dumbbells starts, leading to a tetragonal structure that changes to cubic above 1480 C with complete rotational disorder of the C2 units (Hunt and Rundle, 1951; Gantzel and Baldwin, 1964; Hill and Cavin, 1964; Langer et al., 1964; Bowman et al., 1968). The monocarbide, ThC, has the cubic NaCl structure. Both ThC2 and ThC are refractory solids with high melting points (2655 ± 25 and 2625 ± 25, respectively). For ThC, the specific heat has been measured from 1.5 to 300 K (Danan, 1975). The third binary thorium carbide, Th2C3, has been observed at pressures

Thorium

68

Fig. 3.4

Phase diagram of the thorium–carbon system (Chiotti et al., 1981).

above 33 kbar in the region of 1200 C (Krupka, 1970). It has the cubic structure of Pu2C3 and is a superconductor with Tc decreasing with increasing pressure (Giorgi et al., 1976). Besides these three carbides, several non‐stoichiometric phases have been found that can be seen as solid state solutions between a‐Th and γ‐ThC2 (Chiotti et al., 1967; Storms, 1967) that have cubic symmetry. Upon heating ThC2 to high temperature on a graphite filament, ThCþ 4 ions were observed (Asano et al., 1974). ThC2 burns in the air to form ThO2 and reacts with sulfur or selenium vapor (Moissan and E´tard, 1896, 1897). Halogens react with the carbide to give anhydrous halides. According to an early study (Lebeau and Damiens, 1913) the hydrolysis of the carbide produces a mixture of almost 60% hydrogen, 3.16% methane, 10.7% ethane, 15% acetylene, 3% ethylene, 8% propylene and propane, and higher products. Other studies on the hydrolysis of ThC and ThC2 report the formation of methane in the ThC case and the formation of ethane and hydrogen in the ThC2 case (Kemper and Krikorian, 1962). It seems evident that not only the composition and purity of the carbide but also the actual hydrolysis conditions may be important factors. A number of ternary carbides have been reported (Table 3.5). The boride carbides have the compositions ThBC, Th3B2C3, and ThB2C (Rogl, 1978, 1979;

Important compounds

69

Rogl and Fischer, 1989). ThBC and Th3B2C3 contain CBBC units; in Th3B2C3 additional C atoms are found (Fig. 3.5). For ThB2C extended layers of connected B and C atoms are found with the thorium atoms located between the layers. In the nitride carbide ThCN (Benz, 1969; Benz and Troxel, 1971), dumbbell‐shaped C2 units and nitride ions are present (Benz et al., 1972). Several ternary carbide systems have been investigated, Th–M–C, with M being a transition metal element or a lanthanide, and a huge number of compounds are believed to exist (Gmelin, 1992b). However, only a few of them are structurally characterized. Specifically, for ruthenium and nickel, several structure determinations have been performed. In the former case, the compounds Th11Ru12C18, Th2Ru6C5, and ThRu3C were investigated (Aksel’rud et al., 1990a,b; Wachtmann et al., 1995). The carbon‐rich species contain both C2 units and single C atoms while ThRu3C can be regarded as a cubic closest packing of metal atoms with the carbon atoms in octahedral interstices. Two series of thorium iron carbides have been structutrally and magnetically investigated recently. They have the composition ThFe11C1þx (0 < x < 1) and Th2Fe17Cx (0 < x < 1), respectively (Isnard et al., 1992a,b; Singh Mudher et al., 1995). In the nickel system, three compounds were found: Th2NiC2, Th3Ni5C5, and Th4Ni3C6. According to the structure determination the latter two should be more correctly described as Th3Ni4.96C4.79 and Th4Ni2.88C6, respectively (Moss and Jeitschko, 1991a,b). Two carbides have been prepared in the system Th–Al–C, namely Th2Al2C3 and ThAl4C4 (Gesing and Jeitschko, 1996). They are both methanides in the sense that they contain isolated carbon atoms. One lanthanide compound that has been structurally characterized is CeThC2 (Stecher et al., 1964). According to the phase diagram Th–Si (Fig. 3.6) four binary thorium silicides exist (Stecher et al., 1963; Chiotti et al., 1981; Gmelin, 1993b): Th3Si5, Th3Si2, ThSi, and ThSi2. The latter three are structurally known (Brauer and Mitius, 1942; Jacobson et al., 1956; Brown, 1961). ThSi2 is dimorphic and both the hexagonal (AlB2 type) and the tetragonal modifications show the thorium atoms in 12‐fold coordination of silicon atoms. In ThSi the silicon atoms are ˚ ) while Si2 dumbbells (2.33 A ˚ ) are linked to zigzag chains (Si—Si distance: 2.49 A found in Th3Si2. Further silicides have been reported, for example Th6Si11 (Brown and Norreys, 1961), but have not be confirmed up to now. Various ternary silicides of thorium are known (Table 3.5). The largest group among them contains compounds of the composition ThM2Si2 with M being a transition metal element. For M ¼ Cr, Mn, Fe, Co, Ni, Cu, and Tc, structure determinations have been performed (Ban and Sikirica, 1965; Leciejewicz et al., 1988; Wastin et al., 1993) and for part of the silicides, magnetic properties are known (Omejec and Ban, 1971; Ban et al., 1975). The compounds are isotypic with each other and have tetragonal symmetry. The stucture consists of layers of edge connected [ThSi8] cubes that are separated by the transition metal atoms. Other silicides have the composition Th2MSi3 (M ¼ M, Fe, Co, Ni, Cu, Ru, Rh, Pd, Os, Ir, Pt, Au) and are derived from the two modifications of ThSi2 by

Thorium

70

substitution of transition metal atoms for silicon atoms (Ban et al., 1975; Wang et al., 1985; Albering et al., 1994). In the same way, the silicides ThMSi (M ¼ Au, Pd, Ni) are derived from the hexagonal form of ThSi2 (Ban et al., 1975; Wang et al., 1985). Two new silicides of thorium have been reported recently with ThCo9Si2 and ThRe4Si2 (Albering and Jeitschko, 1995; Moze et al., 1996). In a few cases, quaternary compounds have also been investigated. For example the silicide–carbides Th2Re2.086SixC (x ¼ 1.914 and 1.904), ThOs2.04Si0.96C, and ThOs2.284Si0.716C have been reported (Hu¨fken et al., 1998, 1999), and the two lanthanide nitride carbides CeThNC and DyThNC are known (Ettmayer et al., 1980). 3.7.3

Oxides, hydroxides, and peroxides

Thorium oxides have received considerable attention in the recent decades. They have been reviewed in the Gmelin Handbook (Gmelin, 1976, 1978), but the diverse chemistry of the simple binary oxide of thorium has yielded 435 patents since these days, out of which 53 are related to the catalytic behavior of ThO2. An recent search of the Chemical Abstract Services database revealed over 540 journal articles and some 50 reports on catalysis. While ThO2 has been studied as a complement to CeO2 and HfO2 in its chemistry, ThO has been postulated as a defect form of the fluorite or a ZnS structure (Katzin, 1958; Ackermann and Rauh, 1973b). Table 3.6 lists the binary oxides and the other chalcogenides (cf. Section 3.7.5) with their lattice constants. Thorium monoxide has been reported to form on the surface of thorium metal exposed to air (Rundle et al., 1948b) but its preparation and isolation as a bulk black suspension was first reported in 1958 by Katzin as a result of the action of 2 to 12 N HCl solutions on thorium metal. The black powder reported appeared later to be a form of low‐valent thorium oxide stabilized by HCl and H2O. XRD studies ˚ and a pattern indicative revealed a cubic phase with a lattice constant of 5.302 A of an fcc lattice – either a defect fluorite or ZnS‐type (Ackermann and Rauh, 1973b). However, the ‘monoxide’ solid state compound appears to be a Th(IV) phase with the formula Th(H)(O)X, where X is a combination of OH− and Cl− (Katzin et al., 1962). This seemed to explain the reaction of the black solid upon heating to yield HCl, H2, H2O, and ThO2 under various conditions (Ackermann and Rauh, 1973b). This phase was also reported to be unstable to disproportionation under dynamic vacuum. Until now, however, there is no report on bulk‐phase ThO available that is without question. On the other hand, ThO was reported in the vapor phase above a mixture of Th and ThO2 at high temperatures (Darnell and McCollum, 1961; Ackermann and Rauh, 1973b; Hildenbrand and Murad, 1974a,b; Neubert and Zmbov, 1974). Thorium dioxide (thoria) is somewhat hygroscopic. Reaction with nitric or hydrochloric acids followed by evaporation yields hydrates that have in the past been thought to resemble the so‐called ‘metaoxides’ of tin and zirconium. The material may be dispersed as a positively charged colloid following evaporation

Space group

P4/mbm Pm3m P4122 R3m P2/m Fm3c

Pm3m Pbam Pbam Pbam Pbam Immm Cmmm P6/mmm P6/mmm

Fm3m C2/c C2/c C2/c I4/mmm Fm3m C2/m

Pnnm I4/m I41/amd

Compound

ThB4 ThB6 ThBC ThB2C Th3B2C3 ThB66.8O0.36

Na0.77Th0.23B6 Th2FeB10 Th2CoB10 Th2NiB10 ThCrB4 ThCr2B6 ThMoB4 ThIr3B2 ThRu3B2

ThC ThC2 ThC2 ThC1.97 ThC1.97 ThC1.97 ThCN

Th2Al2C3 ThAl4C4 ThFe11C1+x

5.406 8.231 10.20

5.346 6.53 6.684 6.692 4.221 5.806 7.0249

4.151 5.627 5.624 5.646 6.057 3.158 7.481 5.449 5.528

7.256 4.113 3.762 6.676 3.703 23.53

˚) a (A

3.5201 3.3273 6.61

7.2763

3.9461 11.556

6.56 6.735 6.744 5.394

4.183 4.185 4.173 3.640 8.364 3.771 3.230 3.070

25.246 11.376 9.146

4.113

˚) c (A

4.24 4.220 4.223

11.204 11.712 6.591 9.658

3.773

˚) b (A

Lattice parameters

b ¼ 95.67

b ¼104.0 b ¼ 103.91 b ¼ 103.1

b ¼ 100.06

Angles ( )

Gesing and Jeitschko (1996) Gesing and Jeitschko (1996) Isnard et al. (1992a)

Kemper and Krikorian (1962) Hunt and Rundle (1951) Jones et al. (1987) Bowman et al. (1968) Bowman et al. (1968) Bowman et al. (1968) Benz et al. (1972)

Blum and Bertaut (1954) Konrad and Jeitschko (1995) Konrad and Jeitschko (1995) Konrad and Jeitschko (1995) Konrad et al. (1996) Konrad et al. (1996) Rogl and Nowotny (1974) Ku et al. (1980) Hiebl et al. (1980)

Zalkin and Templeton (1950, 1953); Konrad et al. (1996) Konrad et al. (1996), Blum and Bertaut (1954) Rogl (1978) Rogl and Fischer (1989) Rogl (1979) Naslain et al. (1971)

References

Table 3.5 Crystallographic data of thorium borides, carbides, and silicides.

Space group

R3m I4/mmm Cmca C2/m Pm3m P4/mbm I43m P4/mbm I43m Fm3m

Pbnm P6/mmm I41/amd P6/mmm P4/mbm

Compound

Th2Fe17Cx Th2NiC2 Th3Ni4.96C4.79 Th4Ni2.88C6 ThRu3C Th2Ru6C5 Th11Ru12C18 Th2Ru6C5 Th11Ru12C18 ThCeC2

ThSi ThSi2 ThSi2 ThSi2 Th3Si2

5.89 4.136 4.126 3.985 7.835

8.6 3.758 13.961 15.369 4.227 9.113 10.764 9.096 10.754 5.280

˚) a (A

7.88

7.174 3.751

˚) b (A

Lattice parameters

4.15 4.126 14.346 4.220 4.154

4.177

4.186

12.5 12.356 7.07 7.628

˚) c (A

b ¼ 113.29

Angles ( )

Table 3.5 (Contd.)

Jacobson et al. (1956) Brown (1961) Brauer and Mitius (1942) Jacobson et al. (1956) Jacobson et al. (1956)

Isnard et al. (1992b) Moss and Jeitschko (1991b, 1989b) Moss and Jeitschko (1991b, 1989b) Moss and Jeitschko (1991a, 1989a) Wachtmann et al. (1995) Aksel’rud et al. (1990a) Aksel’rud et al. (1990b) Wachtmann et al. (1995) Wachtmann et al. (1995) Stecher et al. (1964)

References

ThCr2Si2 ThCr2Si2 ThMn2Si2 ThMn2Si2 ThMn2Si2 ThFe2Si2 ThFe2Si2 Th(Co0.5Si1.5) ThCo9Si2 ThCo2Si2 ThCo2Si2 ThNi2Si2 ThNi2Si2 ThCu2Si2 ThCu2Si2 ThTc2Si2 ThRe4Si2 ThAuSi

I4/mmm I4/mmm I4/mmm I4/mmm I4/mmm I4/mmm I4/mmm P6/mmm I41/amd I4/mmm I4/mmm I4/mmm I4/mmm I4/mmm I4/mmm I4/mmm Pnnm P6m2

4.043 4.0414 4.021 4.0225 4.019 4.038 4.038 4.043 9.7914 4.015 4.0128 4.076 4.0789 4.104 4.1031 4.184 7.294 4.260 15.500

10.577 10.588 10.493 10.475 10.483 9.820 9.812 4.189 6.3138 9.760 9.754 9.551 9.555 9.864 9.866 10.063 4.124 4.164

Ban and Sikirica (1965) Leciejewicz et al. (1988) Ban and Sikirica (1965) Leciejewicz et al. (1988) Ban et al. (1975) Ban and Sikirica (1965) Leciejewicz et al. (1988) Wang et al. (1985) Moze et al. (1996) Ban and Sikirica (1965) Leciejewicz et al. (1988) Ban and Sikirica (1965) Leciejewicz et al. (1988) Ban and Sikirica (1965) Leciejewicz et al. (1988) Wastin et al. (1993) Albering and Jeitschko (1995) Albering et al. (1994)

Thorium

74

Fig. 3.5

Fig. 3.6

Crystal structures of Th3B2C3 (left) and ThB2C (right).

Phase diagram of the thorium–silicon system (Chiotti et al., 1981).

Important compounds

75

Table 3.6 Crystallographic data of thorium chalcogenides. Lattice parameters ˚) a (A

˚) b (A

˚) c (A

Compound

Space group

ThO

cubic

ThO2 ThOS ThS Th2S3 Th7S12 ThS2 Th2S5

Fm3m P4/nmm Fm3m Pbnm P63/m Pmnb Pcnb

5.592 3.963 5.682 10.990 11.063 4.267 7.623

ThOSe ThSe Th2Se3 Th7Se12 ThSe2 Th2Se5

P4/nmm Fm3m Pbnm P63/m Pmnb Pcnb

4.038 5.875 11.36 11.570 4.420 7.922

ThSe3 ThOTe

P21/m P4/nmm

5.72 4.120

ThTe

Pm3m

3.827

Th2Te3

hexagonal

12.49

4.35

Th7Te12 ThTe2

P6 hexag. (?)

12.300 8.49

4.566 9.01

ThTe3

monoclinic

Angles ( )

5.302

6.14

6.747 10.850 7.264 7.677

3.960 3.991 8.617 10.141 7.019

11.59 7.611 7.937 4.21

10.44

4.28 4.230 9.065 10.715 9.64 9.563

4.31

b ¼ 97.05

b ¼ 98.4

References Katzin (1958); Ackermann and Rauh (1973b) Gmelin (1976, 1978) Zachariasen (1949c) Zachariasen (1949c) Zachariasen (1949c) Zachariasen (1949d) Zachariasen (1949c) No¨el and Potel (1982) D’Eye et al. (1952) D’Eye et al. (1952) D’Eye et al. (1952) D’Eye (1953) D’Eye (1953) Kohlmann and Beck (1999) No¨el (1980) D’Eye and Sellman (1954) D’Eye and Sellman (1954) Graham and McTaggart (1960) Tougait et al. (1998) Graham and McTaggart (1960) Graham and McTaggart (1960)

and the colloid can be ‘salted out’ by addition of electrolytes. The ignited oxide or the oxide sintered into larger particles is one of the most refractory substances known, showing limited reactivity with hot sulfuric acid or fusion with potassium hydrogen sulfate. Aqueous nitric acid with a few percentage of HF or sodium fluorosilicate provides a reasonable solution of the oxide (Smithells, 1922). Hot aqueous HF or gaseous HF at 250–750 C converts thoria to ThF4 (Newton et al., 1952b). Amorphous thoria is said to crystallize from a suitable flux, for example sodium carbonate, potassium orthophosphate, or borax (Nordenskjo¨ld and Chydenius, 1860; Nordenskjo¨ld, 1861; Chydenius, 1863; Rammelsberg, 1873; Troost and Ouvrard, 1889; Duboin, 1909a,b). However, the use of borax as a

76

Thorium

flux is questionable, because ThO2 is known to form ThB2O5 in the reaction with B2O3 (Baskin et al., 1961). Thorium dioxide has been studied as an active catalyst because of its reactivity with many gases, in addition to water. Dehydration of alcohols (Frampton, 1979; Siddham and Narayanan, 1979), dehydrogenation of alcohols (Thomke, 1977), and the hydration (Frampton, 1979) and hydrogenation of alkenes (Tanaka et al., 1978) have been demonstrated. Other examples include copper–thorium oxide catalysts studied for the selective hydrogenation of isoprene (Bechara et al., 1990a,b), decomposition of isopropanol (Aboukais et al., 1993), and the oxidative coupling of methane (Zhang et al., 2001). Indeed, the development of mixed‐metal rare earth/thorium/copper oxides based on a perovskite parent structure have been shown to decompose NOx (Gao and Au, 2000), to catalyze the reduction of NO by CO (Wu et al., 2000), and to dehydroxylate phenol (Liu et al., 1997). Lastly, thorium oxide, when heated, produces an intense blue light and mixed with ceria at 1%, produces a more intense white light. It is this property that was the basis for the thoriated gas mantle industry (Mason, 1964; Manske, 1965). Thorium hydroxide is formed as a gelatinous precipitate when alkali or ammonium hydroxide is added to a solution of a thorium salt. This precipitate dissolves in dilute acids and, when fresh, in ammonium oxalate, alkali carbonates, sodium citrate, or sodium potassium tartrate solutions (Chydenius, 1863; Glaser, 1897; Jannasch and Schilling, 1905; Sollman and Brown, 1907). The hydroxide is also precipitated by the action of sodium nitrate (Baskerville, 1901) or potassium azide (Dennis and Kortright, 1894; Glaser, 1897; Wyrouboff and Verneuil, 1898a). Electrolysis of thorium nitrates is also said to yield a precipitate of hydroxide at the anode (Angelucci, 1907). Material dried at 100 C has been reported to correspond closely in composition to Th(OH)4 (Cle`ve, 1874), but other reports claim to find higher hydrates even at higher temperatures (Wyrouboff and Verneuil, 1905). Two forms of ThO2·2H2O (¼Th(OH)4), from precipitation in basic aqueous solution, have been distinguished, one of which is amorphous (Guymont, 1977). Further studies indicate that Th(OH)4 is stable in the temperature range 260–450 C and is converted to the oxide at temperatures of 470 C and higher (Dupuis and Duval, 1949). Thermal analysis has shown that the decomposition of the hydroxide is a continuous process (Tiwari and Sinha, 1980). Thorium hydroxide absorbs atmospheric carbon dioxide very readily (Chydenius, 1863; Dennis and Kortright, 1894; Chauvenet, 1911). When boiled with thorium nitrate, Th(OH)4 forms a positively charged colloid (Mu¨ller, 1906). The colloid formation is also observed if thorium hydroxide is treated with hydrous aluminum chloride, ferric chloride, uranyl nitrate, or hydrochloric acid (Szilard, 1907). The solubility product of Th(OH)4 is discussed in Section 3.8.5. Thorium peroxide had been reportedly known since 1885 as the product of the reaction between hydrogen peroxide and salts of thorium in solution

Important compounds

77

(de Boisbaudran, 1885). The precipitate that forms can be a dense solid or a gelatinous paste. The solid has initially been described in the literature as hydrated thorium peroxide, ‘Th2O7’ (de Boisbaudran, 1885; Pissarsjewski, 1900; Schwarz and Giese, 1928). The existence of peroxide species was confirmed but it was pointed out that the respective anions of the initial thorium salt are part of the solid (Cle`ve, 1885; Wyrouboff and Verneuil, 1898a; Hamaker and Koch, 1952a,b; Johnson et al., 1965; Hasty and Boggs, 1971; Raman and Jere, 1973a,b; Jere and Santhamma, 1977). XRD studies revealed two phases if the precipitation occurs from thorium sulfate solution: Th(OO)SO4·3H2O precipitated from solutions of high H2SO4 concentration and a second phase is obtained from more weakly acidic solutions with a variable sulfate content and 3.0–3.8 peroxide oxygen atoms per thorium atom (Hamaker and Koch, 1952a). A Raman analysis of Th(OO)SO4·3H2O has been performed (Raman and Jere, 1973a,b) and suggests a formulation of the compound as ‘tetraaquo‐μ‐peroxydisulfatodithorium(IV)’, with two bridging sulfato groups. Raman investigations have been also carried out for the peroxide obtained from a nitrate solution (Raman and Jere, 1973b). According to these measurements thorium peroxide nitrate showed a ‘free’ (D3h) nitrate anion along with a bridging peroxide molecule between thorium atoms. However, also a nitrate‐free peroxide has been obtained from the reaction of a refluxing aqueous solution of Th (NO3)4·4H2O, urea, and 30% hydrogen peroxide (Gantz and Lambert, 1957). The precipitate, described as a granular light blue‐green powder, decomposes at 120 C to yield ThO2 and water. Chemical analysis revealed a formula of Th (OH)3OOH, equivalent to tin and zirconium analogs. The dried peroxide is insoluble in neutral solutions (aqueous) but is soluble in concentrated mineral acids. Thorium peroxide has also been reported by the action of hydrogen peroxide or sodium hypochlorite on thorium hydroxide, or by anodic oxidation of an alkaline thorium hydroxide suspension containing sodium chloride (Pissarsjewsky, 1902). Like the double salts of the halides, thorium dioxide will form a similar ‘double salt’ of oxide with BaO and alkali metal oxides (K2O, for example) in phases such as BaThO3 and K2ThO3 (Brunn and Hoppe, 1977); however, neither the Sr form nor the Li form of these structures have been reported (Hoffmann, 1935; Naray‐Szabo, 1951; Scholder et al., 1968; Fava et al., 1971; Nakamura, 1974). No reaction was seen with BeO (Ohta and Sata, 1974) and, although there is solid solution formation with the rare earth oxides, no reaction to form the ‘double salt’ phase Ln2ThO5 has been observed (Diness and Roy, 1969; Sibieude, 1970). Because of the reactivity of ThO2–CuO mixtures, reactions that have included other transition metal oxides have yielded a number of unique phases including tetragonal perovskite phases such as La1–xThxCoO3 (Tabata and Kido, 1987), La1–1.333xThxNiO3 (Yu et al., 1992), Na.6667Th.3333TiO3 (Zhu and Hor, 1995), and the Ruddlesden– Popper manganites Ca3–xThxMn2O7 (Lobanov et al., 2003).

Thorium

78

3.7.4 (a)

Halides

Binary halides

The halides of thorium had been treated comprehensively in 1968 by Brown (1968), and the fluorides in particular have been reviewed by Penneman et al. (1973) and Taylor (1976). In addition, a later volume of the Gmelin Handbook has discussed thorium halides (Gmelin, 1993a). The tetrahalides of thorium are known for the whole halogen series (Table 3.7). Thorium fluoride, ThF4, can be obtained by various procedures (Moissan and Martinsen, 1905; Duboin, 1908a; Chauvenet, 1911; Lipkind and Newton, 1952). Precipitation from aqueous Th4þ‐containing solutions leads to hydrates of ThF4 that are, however, not easily dehydrated due to the formation of hydroxide or oxide fluorides (Briggs and Cavendish, 1971). Under careful conditions, for example under streaming HF or F2 gas, dehydration to pure ThF4 is possible (Pastor and Arita, 1974). Alternative routes avoiding aqueous media are the reaction of thorium metal or thorium carbide with fluorine (Moissan and E´tard, 1896, 1897), or the action of hydrogen fluoride on other thorium halides, thorium oxide or hydroxide, and thorium oxalate or oxide carbonate (Newton et al., 1952a). As mentioned in the Section 3.7.1, the reaction of thorium hydrides with fluorine provides a route to ThF4 (Lipkind and Newton, 1952). An elegant way to obtain pure ThF4 is the reaction of ThO2

Table 3.7

Crystallographic data of binary thorium halides. Lattice parameters

Compound

Space group

˚) a (A

˚) b (A

˚) c (A

ThF4

C2/c

13.049

11.120

b‐ThCl4

I41/amd

8.491

7.483

a‐ThCl4

I41/a

6.408

12.924

b‐ThBr4

I41/amd

8.971

7.912

a‐ThBr4

I41/a

6.737

13.601

ThI4

P21/n

13.216

8.068

7.766

b‐ThI3

Cccm

8.735

20.297

14.661

b‐ThI2

P63/mmc

3.97

8.538

31.75

Angles ( )

References

b ¼ 126.31

Benner and Mu¨ller (1990) Brown et al. (1973) Mason et al. (1974a) Madariaga et al. (1993) Mason et al. (1974b) Zalkin et al. (1964) Beck and Strobel (1982) Guggenberger and Jacobson (1968)

b ¼ 98.68

Important compounds

79

with NH4HF2. Ammonium hydrogen fluoride serves as the fluorinating agent and is much easier to handle than hydrogen fluoride itself. The reaction yields the ternary fluoride NH4ThF5 that decomposes above 300 C to the tetrafluoride (Asprey and Haire, 1973). The disadvantage of the method compared to the direct hydrofluorination is that an eight‐fold excess of NH4HF2 is needed. The monoclinic crystal structure of ThF4 is isotypic with those of zirconium and hafnium fluoride and contains Th4þ ions in slightly distorted square antiprismatic coordination of fluoride ions (Zachariasen, 1949a; Asprey and Haire, 1973; Benner and Mu¨ller, 1990). Each of the fluorine atoms is attached to another thorium ion, leading to a three‐dimensional structure according to 3 ∞[ThF8/4]. Surprisingly, the thorium fluoride hydrate that can be precipitated from aqueous solution (Berzelius, 1829; Chydenius, 1863) has not been structurally characterized up to now. It is believed to be an octahydrate, which decomposes to a tetrahydrate on further drying and then finally to a dihydrate on heating (Chauvenet, 1911). The only hydrate of ThF4 that is structurally known is Th6F24·H2O (¼ThF4·1/6H2O) (Cousson et al., 1978). Similarly to the anhydrous fluoride it consists of three‐dimensionally connected square antiprisms [ThF8]. Six of these aniprisms are arranged in a way that empty voids are formed in which the water molecule resides having contact to two of the six Th4þ ions (Fig. 3.7). It is assumed that this compound can be obtained by

Fig. 3.7 Detail of the crystal structure of Th6F24·H2O; the H2O molecule resides in a void formed by six square antiprismatic [ThF8] polyhedra.

80

Thorium

careful dehydration of higher hydrates but usually hydrolysis is observed yielding Th(OH)F3·H2O and then finally ThOF2 (Marden and Rentschler, 1927; Zachariasen, 1949a; D’Eye, 1958). The structure of neither of the latter two compounds is known without some question. For ThOF2, however, an orthorhombic unit cell has been determined, which has a close relationship to the hexagonal one of LaF3. Probably the structure can be seen as an ordering variant of the LaF3‐type of structure. The treatment of ThOF2 with steam at 900 C will yield thoria (Chydenius, 1863; Cline et al., 1944). Thorium tetrachloride, ThCl4, can be crystallized from aqueous solution as an octahydrate, which is easily transformed to basic chlorides upon heating above 100 C (Chauvenet, 1911; Dergunov and Bergman, 1948; Knacke et al., 1972a,b). Dehydration has also been done by refluxing the hydrates with thionyl chloride but the product was hard to get free of SOCl2. Other routes have been employed to produce pure ThCl4 (Chydenius, 1863) including the reaction of ThH4 with HCl and the action of chlorine on thorium metal (Kru¨ss and Nilson, 1887a; Lipkind and Newton, 1952), ThH4, or thorium carbide (Nilson, 1876, 1882a,b, 1883; Moissan and E´tard, 1896, 1897; von Wartenberg, 1909). Furthermore mixtures of chlorine and carbon or S2Cl2 were used for the chlorination of ThO2 (Matignon and Bourion, 1904; Meyer and Gumperz, 1905; Bourion, 1909; von Wartenberg, 1909; Yen et al., 1963), and also carbon tetrachloride (Matignon and Delepine, 1901; von Bolton, 1908; Knacke et al., 1972a), phosgene (Baskerville, 1901; Karabasch, 1958), and phosphorus pentachloride (Smith and Harris, 1895; Matignon, 1908) were applied as chlorinating agents and mixtures of chlorine and CO or CO2 for the chlorination of thorium oxalate and nitrate, respectively (Dean and Chandler, 1957). A facile synthesis of ThCl4 is provided in the reaction of thorium metal with NH4Cl in sealed tubes (Schleid et al., 1987). Purification of ThCl4 can be achieved by sublimation. ThCl4 melts at 770 C (Moissan and Martinsen, 1905; Fischer et al., 1939) and boils at 921 C. The results of vapor pressure measurements as a function of the temperature have been compiled (Fuger et al., 1983). ThCl4 is dimorphic and exhibits a phase transition at 405 C (Mooney, 1949; Mucker et al., 1969; Mason et al., 1974a). The phase transition can only be observed under special conditions and in very pure samples. Usually the high‐ temperature phase b‐ThCl4 remains even at temperatures below 405 C as a metastable compound. Both the low‐temperature phase a‐ThCl4 and the high‐ temperature phase b‐ThCl4 are tetragonal and show eight‐fold coordinated Th4þ ions. The coordination polyhedra are slightly distorted dodecahedra that are connected via four edges to a three‐dimensional structure. Thus, each of the chloride ligands are connected to two Th4þ ions. The difference in the two polymorphs results from small differences in the orientation of the [ThCl8] polyhedra with respect to each other (Fig. 3.8). The symmetry decreases from I41/amd for b‐ThCl4 to I41/a for a‐ThCl4. The two modifications of ThCl4 are related in much the same way as are zicon (ZrSiO4) and scheelite (CaWO4).

Important compounds

81

Fig. 3.8 Projections of the crystal structures of a‐ThCl4 (right) and b‐ThCl4 (left) onto (001).

In fact the structures of ThCl4 result if the atoms in the tetrahedral centers (Si and W, respectively) are removed in the oxo‐compounds. More recent investigations gave some evidence that there is a third modification of ThCl4 below 70 K that has a complicated incommensurate structure related to that of a‐ThCl4 (Khan Malek et al., 1982; Bernard et al., 1983; Krupa et al., 1987). Structural data of ThCl4 hydrates are not known up to now but the enthalpies of formation of the di‐, tetra‐, hepta‐ and octahydrates have been evaluated (Fuger et al., 1983) from enthalpy of solution measurements (Chauvenet, 1911). Also the basic chlorides that are frequently observed as the products of the thermal treatment of the hydrates are poorly investigated (Bagnall et al., 1968). It is only for the oxychloride ThOCl2 that lattice parameters have been calculated from powder diffraction data based on the data given for PaOCl2 (Bagnall et al., 1968). The heat of formation of ThOCl2 has been reported several times (Yen et al., 1963; Korshunov and Drobot, 1971; Knacke et al., 1972b; Fuger et al., 1983) and will be discussed in proper context in Chapter 19. Chlorides of lower‐valent thorium have been reported to form by electrochemical reduction of a ThCl4/KCl melt (Chiotti and Dock, 1975) but these observations are still in need of confirmation. Analogous to the tetrachloride, ThBr4 can be obtained from aqueous solution, for example, by adding Th(OH)4 to aqueous HBr. Depending on the drying conditions various hydrates may form. The main disadvantage of the wet route for preparing ThBr4 is the contamination of the product with hydrolysis products like ThOBr2. Dry routes to ThBr4 include the action of bromine on thorium metal, ThH4, ThC, or on mixtures of ThO2 and C (Nilson, 1876; ´ tard, 1896, 1897; Matthews, 1898; Troost and Ouvrard, 1889; Moissan and E Moissan and Martinsen, 1905; Fischer et al., 1939; Young and Fletcher, 1939; Lipkind and Newton, 1952). Moreover, the reaction of gaseous HBr with ThH4 (Lipkind and Newton, 1952) and of a mixture of S2Cl2 and gaseous HBr with ThO2 have been employed (Bourion, 1907). Sublimation above 600 C in

82

Thorium

vacuum should be applied for purification. The temperature dependence of the vapor pressure has been investigated (Fischer et al., 1939) and melting (679 C) and boiling (857 C) points have been reported (Fischer et al., 1939; Mason et al., 1974b). As found for the tetrachloride, ThBr4 is also dimorphic (D’Eye, 1950; Brown et al., 1973; Fuger and Brown, 1973; Mason et al., 1974b; Guillaumont, 1983). Both modifications, b‐ThBr4 and a‐ThBr4, are isotypic to the respective chlorides. The transition temperature is slightly higher compared to ThCl4 and is determined to be 426 C. Again, the b‐phase is found to remain metastable even below 426 C. The phase transition has been investigated in detail by means of nuclear quadrupolar resonance (NQR) on the 79Br isotope (Kravchenko et al., 1975). According to these experiments, the time to achieve complete conversion is strongly dependent on the previous treatment of the sample and is reduced after one conversion cycle has passed. Analogous to ThCl4 another phase transition is found at lower temperature. According to NQR and electron paramagnetic resonance (EPR) measurements as well as neutron and X‐ray diffractions, the transition is second order and occurs at 92 K (Kravchenko et al., 1975). It is only observed in b‐ThBr4 and can be described as a continuous modulation of the bromide ions along the c‐axis, leading to a complicated incommensurate structure (Madariaga et al., 1993). The incommensurate low‐ temperature modifications of ThBr4 and ThCl4 have also been investigated spectroscopically on U4þ‐doped samples (Krupa et al., 1995). There are two reports on the low‐valent thorium bromides, ThBr3 and ThBr2 (Hayek and Rehner, 1949; Shchukarev et al., 1956). They have been prepared from the elements in the desired molar ratio or, in the case of ThBr3, by reduction of ThBr4 with hydrogen. These bromides are highly reactive and show disproportionation at higher temperatures. Unfortunately no structural data are known. More recently the molecular species, ThBr3, ThBr2 and ThBr, have been identified by mass spectrometry in the bromination of thorium between 1500 and 2000 K (Hildenbrand and Lau, 1990). None of the various hydrates of ThBr4 that have been reported to contain 12, 10, 8, and 7 molecules of water, respectively (Lesinsky and Gundlich, 1897; Rosenheim and Schilling, 1900; Rosenheim et al., 1903; Moissan and Martinsen, 1905; Chauvenet, 1911), are well characterized to date. The heat of solution has been determined in some cases and the thermal decomposition of the hydrates is known to lead to Th(OH)Br3 and finally to ThOBr2 (Chauvenet, 1911). The powder diffraction pattern of the oxybromide shows that this compound is not isotypic with ThOCl2 but seems to have a lower symmetry (Bagnall et al., 1968). ThBr4 is also known to form solvates with amines (Rosenheim and Schilling, 1900; Rosenheim et al., 1903), acetonitrile (Young, 1935), and trimethylphosphine (Al‐Kazzaz and Louis, 1978). Thorium tetraiodide (ThI4) is most conveniently prepared by the reaction of the elements in sealed silica ampoules (Nilson, 1876; Moissan and E´tard, 1896, 1897; Zalkin et al., 1964). It is very important to exclude any traces of water or

Important compounds

83

oxygen during the reaction to avoid contamination of the product with ThOI2 or even ThO2. Alternative procedures involve the reactions between ThH4 and HI, and between thorium metal and a H2/I2 mixture (Lipkind and Newton, 1952). If only small amounts of ThI4 are needed, the action of AlI3 on ThO2 might also be appropriate (Chaigneau, 1957). In the temperature range from 500 to 550 C, ThI4 can be sublimed for purification under dynamic vacuum yielding yellow crystals. Knudsen cell effusion studies of ThI4 have suggested dissociation through ThI3, ThI2, and ThI to thorium metal (Knacke et al., 1978). On heating, ThI4 reacts with ThO2 to form the basic iodide ThOI2 (Scaife et al., 1965; Corbett et al., 1969). ThI4 is not isotypic with the other tetrahalides. It has monoclinic symmetry and contains eight‐fold coordinated Th4þ ions (Zalkin et al., 1964). The coordination polyhedron can be seen as a distorted square antiprism. The polyhedra are linked in chains via two triangular faces leading to Th–Th distances of 4.48 ˚ . The chains are further connected via the two remaining iodine ligands into A layers. The connectivity may be formulated as 21 ½ThIf6=2 Ie2=2  (f ¼ face; e ¼ edge). These layers are held together only by van der Waals interactions (Fig. 3.9). Two lower‐valent thorium iodides, ThI3 and ThI2, are known. Both can be obtained by reduction reactions of ThI4 with appropriate amounts of thorium metal in sealed tantalum tubes (Anderson and D’Eye, 1949; Hayek and Rehner, 1949; Hayek et al., 1951; Clark and Corbett, 1963; Scaife and Wylie, 1964; Guggenberger and Jacobson, 1968). If hydrogen is used as the reducing reagent, the formation of iodide hydrides is observed (Struss and Corbett, 1978).

Fig. 3.9 Crystal structures of the thorium iodides ThI4 (left, as a projection onto the (101) plane), b‐ThI3 (middle, as a projection onto the (001) plane), and b‐ThI2 (right, as a projection onto the (110) plane).

Thorium

84

For the preparation of ThI2, another route has been developed. The electrolysis of thorium metal in a solution of iodine and tetraethyl ammonium perchlorate in acetonitrile affords ThI2·2CH3CN that can be decomposed into ThI2 in vacuuo (Kumar and Tuck, 1983). Depending on the time, the reaction of ThI4 and Th leads to two modifications of ThI3 (Beck and Strobel, 1982). After a short period of 2–3 days, thin shiny rods of a‐ThI3 were obtained while long heating times led to compact crystals of b‐ThI3 that show a slight green to brass‐colored luster. For a‐ThI3 only the lattice constants are known while a complete structure determination has been performed for b‐ThI3 (Beck and Strobel, 1982). It shows three crystallographically different thorium atoms in the unit cell, each of them in an eight‐ fold coordination of iodide ions. Two of the [ThI8] polyhedra are square antiprismatic, the third one is a slightly elongated cube. The [ThI8] cubes are connected via four rectangular faces to [ThI8] square antiprisms (Fig. 3.9). One half of the square antiprisms is further connected to other cubes and, the second half to other square antiprisms, leading to a three‐dimensional network. The Th–I bond distances suggest that thorium is in the tetravalent state in ThI3 and has to be formulated according to Th4þ(I−)3(e−) with the electrons delocalized or involved in metal–metal bonds. The latter assumption is supported by ˚. the relatively short Th–Th distances of 3.46 to 3.80 A ThI2 is also found to adopt two different crystal structures (Clark and Corbett, 1963; Scaife and Wylie, 1964). Lustrous gold crystals of b‐ThI2 are obtained at 700 to 850 C while a‐ThI2 forms at 600 C. Both compounds are hexagonal but a structure determination has been performed only for b‐ThI2 (Guggenberger and Jacobson, 1968). The structure can be seen as a stacking ˚) variant of the CdI2 structure (Fig. 3.9). It has a remarkable long c‐axis (31 A and the stacking sequence of the iodide ions is …ABCCBA… with the thorium atoms in octahedral and trigonal prismatic sites (Fig. 3.9). Judging from the Th–I bond distances, Th4þ is present in the structure and the free electrons, according to Th4þ(I−)2(e−)2, should be responsible for the electrical conductivity of the compound. The metal–metal distances, however, are remarkably longer than those found in ThI3. Both subiodides, ThI3 and ThI2, exhibit peritectic decomposition above 850 C caused by disproportionations to ThI4 and ThI2 or ThI4 and Th, respectively (Scaife and Wylie, 1964). The formation of pseudo‐halides of thorium (such as thiocyanate or selenocyanate) in organic solvents has been reported, but up to now, no binary compound is known (Golub and Kalibabchuk, 1967; Laubscher and Fouche´, 1971; Golub et al., 1974). (b)

Polynary halides

The systems AF/ThF4, where A is an alkali or another monovalent metal ion, have been widely investigated (Brunton et al., 1965). Phase diagrams of the

Important compounds

85

Fig. 3.10 Phase diagrams of three AF/ThF4 systems. (a) NaF/ThF4 (Thoma, 1972). (b) TlF/ThF4 (Avignant and Cousseins, 1970). (c) KF/ThF4 (Kaplan, 1956).

systems NaF/ThF4 (Thoma, 1972), KF/ThF4 (Kaplan, 1956), and TIF/ThF4 (Avignant and Cousseins, 1970) are given as examples in Fig. 3.10. Furthermore, the binary and also some ternary phase diagrams of ThF4 with several other fluorides were determined. Table 3.8 surveys the phases that are reported to exist along with those found in the other halide systems. Unfortunately, only very few of these phases have been carefully characterized. In some cases lattice parameters of the compounds were determined by powder diffraction; moreover,

Thorium

86

Table 3.8 Detected phases in the systems with ThX4 (X ¼ F, Cl, Br). System

Compounds

References

LiF–ThF4

Li3ThF7, LiThF5, LiTh2F9, LiTh4F17 Na4ThF8, Na3ThF7, Na2ThF6, Na3Th2F11, Na7Th6F31, NaThF5, NaTh2F9 K5ThF9, K2ThF6, K7Th6F31, KThF5, KTh2F9, KTh6F25

Thoma and Carlton (1961)

NaF–ThF4 KF–ThF4 RbF–ThF4

N2H5F–ThF4

Rb3ThF7, Rb2ThF6, Rb7Th6F31 RbTh3F13, RbTh6F25 Cs3ThF7, Cs2ThF6, CsThF5, Cs2Th3F14, CsTh2F9, CsTh3F13, CsTh6F25 (NH4)4ThF8, (NH4)3ThF7, (NH4)2ThF6 (N2H5)3ThF7, (N2H5)ThF5

NH3OH–ThF4

(NH3OH)ThF4

TlF–ThF4

Tl3ThF7, Tl2ThF6, Tl7Th6F31, TlThF5, TlTh3F13, TlTh6F25 Li4ThCl8 NaThCl5 K3ThCl7, K2ThCl6, KThCl5

CsF–ThF4 NH4F–ThF4

LiCl–ThCl4 NaCl–ThCl4 KCl–ThCl4 RbCl–ThCl4

BaCl2–ThCl4

Rb3ThCl7, Rb2ThCl6, RbThCl5, RbTh1.6Cl5.6 Cs3ThCl7, Cs2ThCl6, CsThCl5, CsTh3Cl13 Ba3ThCl10, Ba3Th2Cl14

NaBr–ThBr4

NaThBr5

KBr–ThBr4

K2ThBr6

RbBr–ThBr4

Rb2ThBr6

CsBr–ThBr4

Cs2ThBr6

CsCl–ThCl4

Thoma and Carlton (1961); Thoma (1972); Brunton et al. (1965) Thoma and Carlton (1961); Dergunov and Bergman (1948); Harris (1960) Thoma and Carlton (1961); Dergunov and Bergman (1948) Thoma and Carlton (1961); Brunton et al. (1965) Ryan et al. (1969); Penneman et al. (1971, 1976, 1968) Glavic et al. (1973); Sahoo and Patnaik (1961) Satpathy and Sahoo (1968); Rai and Sahoo (1974) Avignant and Cousseins (1970); Keller and Salzer (1967) Vdovenko et al. (1974) Vdovenko et al. (1974) Gershanovich and Suglobova (1980) Gershanovich and Suglobova (1980) Gershanovich and Suglobova (1980) Gorbunov et al. (1974) Gershanovich and Suglobova (1981) Gershanovich and Suglobova (1981) Gershanovich and Suglobova (1981) Gershanovich and Suglobova (1981)

careful structure determinations remain scarce. Known crystallographic data are summarized in Table 3.9. In the system LiF/ThF4 four compounds are known to exist (Brown, 1968; Cousson et al., 1977; Penneman et al., 1973; Taylor, 1976), namely Li3ThF7, LiThF5, LiTh2F9, and LiTh4F17. A complete structure analysis has been done for only one of these phases, namely Li3ThF7 (Cousson et al., 1978;

Space group Ccca P4/ncc I41/a tetragonal Fm3m P321 hexagonal I43m cubic R3 P3c1 P42/ncm P321 I4m2 P3 Fm3m P62m Cmc21 R3 R3m P21ma Fm3m P62m R3 R3m Fm3m P63/mmc

Compound

Li3ThF7 Li3ThF7 LiThF5 LiTh2F9 a‐(Na2ThF6)1.333 b2‐Na2ThF6 d-Na2ThF6 NaTh2F9 Na4ThF8 Na7Th6F31 Na3Li4Th6F31 Na3BeTh10F45 Na3ZnTh6F29 Li2CaThF8 KNaThF6 a‐(K2ThF6)1.333 b‐K2ThF6 K5ThF9 K7Th6F31 KTh6F25 RbTh3F13 Rb3ThF7 Rb2ThF6 Rb7Th6F31 RbTh6F25 Cs3ThF7 CsTh6F25

8.788 6.206 15.10 11.307 5.687 5.989 6.14 8.722 12.706 14.96 9.906 11.803 10.166 5.109 6.307 5.994 6.578 7.848 15.293 8.313 8.649 9.62 6.85 9.58 8.330 10.04 8.31

˚) a (A

8.176

10.840

8.768

˚) b (A

Lattice parameters

16.91

25.40

3.83

3.822 12.785 10.449 25.262 7.445

9.912 13.282 23.420 13.255 11.013 7.891

3.835 7.36

12.958 12.940 6.60 6.399

˚) c (A

a ¼ 106.9a

Angles ( )

Laligant et al. (1989) Cousson et al. (1978); Laligant et al. (1992) Keenan (1966) Harris et al. (1959) Zachariasen (1949a) Zachariasen (1948a) Zachariasen (1948b) Zachariasen (1948a, 1949b) Zachariasen (1948b) Keenan (1966) Brunton and Sears (1969) Brunton (1973) Cousson et al. (1979b) Vedrine et al. (1973) Brunton (1970) Zachariasen (1948b, 1949a) Zachariasen (1948a) Ryan and Penneman (1971) Brunton (1971a) Brunton (1972) Brunton (1971b) Dergunov and Bergman (1948) Harris (1960) Brunton et al. (1965) Brunton et al. (1965) Brunton et al. (1965) Brunton et al. (1965)

References

Table 3.9 Crystallographic data of polynary thorium halides (in italics: powder data).

Rb2ThBr6

C2/c trigonal tetragonal trigonal

In2ThBr6 K2ThBr6

8.791 7.52 11.478 7.58

7.614 8.16 8.31

8.610 9.895

P3m1 Orthorh. Orthorh.

Pnma I2/m

(SmTh2F11)1.333 Zr2ThF12

13.944 12.573 9.793 15.60 8.31

Cs2ThCl6 K2ThCl6 Rb2ThCl6

Pnma P213 P21/m R3 P63/mmc

(NH4)3ThF7 (NH4)7Th2F15·H2O Tl3ThF7 Tl7Th6F31 TlTh6F25

8.477

6.994 7.150 7.419 6.963 7.245 7.124

P1

(NH4)4ThF8

˚) a (A

CaThF6 SrThF6 BaThF6 CdThF6 PbThF6 EuThF6

Space group

Compound

14.670

14.13 14.39 9.046 11.80 7.94 12.24

6.038 8.62 8.74

7.171 7.313 7.516 7.109 7.355 7.360

7.225 7.856

10.712 10.84 16.86

8.464

4.137 10.488

7.041

7.308

˚) c (A

7.928

8.364

˚) b (A

Lattice parameters

b ¼ 91.15

b ¼ 117.20

a ¼ 88.38 b ¼ 96.08 γ ¼106.33

Angles ( )

Table 3.9 (Contd.)

Dronskowski (1995) Siegel (1956); Gershanovich et al. (1981); Brunton et al. (1965) Gershanovich and Suglobova (1981)

Siegel (1956) Gershanovich and Suglobova (1981) Gershanovich and Suglobova (1981)

Keller and Salzer (1967); Salzer (1966) Keller and Salzer (1967); Salzer (1966) Keller and Salzer (1967); Salzer (1966) Keller and Salzer (1967); Salzer (1966) Keller and Salzer (1967); Salzer (1966) Keller and Salzer (1967); Salzer (1966)

Abaouz et al. (1997) Taoudi et al. (1996)

Penneman et al. (1971) Penneman et al. (1968) Gaumet et al. (1995) Avignant and Cousseins (1970) Avignant and Cousseins (1970)

Ryan et al. (1969)

References

a

rhombohedral setting.

P4/nmm P31c Cmcm P31c P31c P31c Cmcm Cmcm Cmcm Cmcm Cmcm Cmcm

ThNI b‐PbThI6 γ‐PbThI6 b‐SnThI6 b‐PbGeI6 b‐CaThI6 γ‐GeThI6 γ‐SnThI6 γ‐CaThI6 γ‐SrThI6 γ‐BaThI6 γ‐EuThI6

4.107 7.748 4.387 7.748 7.526 7.697 4.248 4.376 4.278 4.455 4.685 4.420

9.764 9.878 9.992 9.143 9.191 11.488 11.507 11.605 11.390 11.376 11.470 11.376 15.764 17.524

Pmma Pmma Pmma Pmma Pmma Im3m Im3m Im3m Im3m Im3m Im3m Im3m Cmca Pnnm

CaThBr6 SrThBr6 BaThBr6 SnThBr6 PbThBr6 FeTh6Br15 CoTh6Br15 NaFeTh6Br15 Th6Br15H7 Th6Br15D7 Th6H7Br15 Th6D7Br15 Th6Br14C K(Th12N6Br29)

11.37 9.537

tetragonal trigonal

Cs2ThBr6

13.92 13.937 14.02 13.991 13.76 13.964

13.956

13.123 14.031

14.160 11.943 9.242 13.789 10.005 13.789 13.783 13.959 9.991 9.995 10.10 10.052 10.015 10.038

12.104 12.255 12.526 12.716 12.68

4.109 4.286 4.490 4.209 4.228

8.10

10.69

Juza and Sievers (1968) Beck et al. (1993) Beck et al. (1993) Beck et al. (1993) Beck et al. (1993) Beck et al. (1993) Beck et al. (1993) Beck et al. (1993) Beck et al. (1993) Beck et al. (1993) Beck et al. (1993) Beck et al. (1993)

Beck and Ku¨hn (1995) Beck and Ku¨hn (1995) Beck and Ku¨hn (1995) Beck et al. (1993) Beck et al. (1993) Bo¨ttcher et al. (1991a) Bo¨ttcher et al. (1991a) Bo¨ttcher et al. (1991a) Bo¨ttcher et al. (1991a) Bo¨ttcher et al. (1991a) Bo¨ttcher et al. (1991b) Bo¨ttcher et al. (1991b) Bo¨ttcher et al. (1991) Braun et al. (1995)

Siegel (1956); Gershanovich and Suglobava (1981) Brunton et al. (1965)

90

Thorium

Laligant et al., 1989; Pulcinelli and de Almeida Santos, 1989). It is dimorphic but the linkage of the monocapped square antiprisms [ThF9] is the same in the two modifications. They are connected via two common edges to layers according to the formulation 21 ½ThFe4=2 Ft5=1  (e ¼ edge, t ¼ terminal). The layers are stacked along the c‐axis. The different symmetry of the two modifications arises from the different positions of the Liþ ions in the interlayer spacings, and their positions are temperature‐dependent, making the compound a good ionic conductor (Laligant et al., 1992). According to powder diffraction measurements, LiThF5 is isotypic with LiUF5 and contains a three‐dimensional network of vertex‐connected monocapped square antiprisms [ThF9] that incorporate the Liþ in a six‐fold coordination (Keenan, 1966). The lattice parameter of the other two fluorides have been obtained by powder XRD (Harris et al., 1959; Cousson et al., 1978). The system NaF/ThF4 shows the formation of seven compounds (Table 3.8) (Rosenheim et al., 1903; Dergunov and Bergman, 1948; Brunton et al., 1965; Kaplan, 1956; Ryan and Penneman, 1971; Thoma, 1972). Na2ThF6 may either be cubic (a‐Na2ThF6) or trigonal (b2‐Na2ThF6) (Table 3.9). The cubic modification is a variant of the CaF2‐type of structure with Naþ and Th4þ occupying Ca2þ sites in a disordered fashion (Zachariasen, 1949b). The trigonal structure of Na2ThF6 is very similar to the structure of LaF3 and contains both the Naþ and the Th4þ ions in tricapped trigonal prismatic coordination of fluoride anions (Zachariasen, 1948b). The polyhedra are connected via triangular faces in the [001] direction and via common edges in the (001) plane. A third modification, d‐Na2ThF6, has been reported to be also trigonal but has not been proved yet (Zachariasen, 1948c; Penneman et al., 1973). In NaTh2F9 the Th4þ are nine‐fold coordinated by F− ions. The polyhedra are connected via vertices according to 31 ½ThF9=2 0:5 to a three‐dimensional network with the Naþ ions incorporated for charge compensation (Zachariasen, 1948b, 1949a). In the complex structure of Na7Th6F31 nine‐ and ten‐fold coordinated Th4þ ions are present (Keenan, 1966; Penneman et al., 1973). An X‐ray structure analysis is available for all of the six compounds that exist in the KF/ThF4 system (Kaplan, 1956), except for KThF5 (Table 3.9). a1‐K2ThF6 is isotypic with the respective sodium compound, while a slight difference is found between b1‐K2ThF6 and b1‐Na2ThF6 (Zachariasen, 1948c; Ryan and Penneman, 1971). The Th/F sublattice is the same in the two compounds, however, in the former the Kþ ions are located in tricapped trigonal prismatic voids, in the latter, Naþ occupies octahedral sites. The complex fluoride K7Th6F31 (Zachariasen, 1948c; Brunton, 1971a) shows isotypism to the sodium compound. K5ThF9, which has also been prepared from aqueous media (Wells and Willis, 1901), consists of monomeric distorted square antiprismatic [ThF8]4 anions that are connected via Kþ ions (Ryan and Penneman, 1971). Furthermore there are isolated F− ions in the structure that are not bonded to Th4þ. The structure of KTh6F25 is a polymorph of the CsU6F25‐type with the Th4þ ions in nine‐fold coordination by fluoride ions (Brunton, 1972).

Important compounds

91

The tricapped trigonal prismatic polyhedra are linked via shared edges and vertices. The resulting three‐dimensional network incorporates the Kþ ions in voids. Finally, a mixed sodium potassium fluoride is known: NaKThF6 (Brunton, 1970). Among the compounds found in the RbF/ThF4 system (Dergunov and Bergman, 1948; Thoma and Carlton, 1961), Rb2ThF6, Rb7Th6F31 and RbTh6F25 are isotypic to their respective potassium fluorides (Harris, 1960; Penneman et al., 1973). Rb3ThF7 has the same cubic structure as K3UF7 and shows a highly disordered fluoride sublattice (Dergunov and Bergman, 1948). The same is true for Cs3ThF7, which is one of the seven phases that are known to exist in the CsF/ThF4 system (Thoma and Carlton, 1961; Penneman et al., 1973). Unfortunately, lattice parameters are only available for one additional compound, CsTh6F25. It is isotypic to CsU6F25 and can be seen as a polymorph of the KTh6F25‐type wherein the Th4þ ions are in nine‐fold and the Csþ ions in 12‐fold coordination by fluoride ions (Brunton, 1971b; Penneman et al., 1973). Although the size of the ammonium ion is comparable to the radii of Kþ and Rbþ, the NH4F/ThF4 system contains only a few phases, namely (NH4)2ThF6, (NH4)3ThF7, and (NH4)4ThF8 (Ryan et al., 1969; Penneman et al., 1971). The latter two have been structurally characterized. (NH4)3ThF7 is not isotypic with the respective potassium or cesium compounds but crystallizes with orthorhombic symmetry (Penneman et al., 1971). It contains chains of edge‐sharing [ThF9] polyhedra with the formulation 11 ½ThF4=2 F5=1  that are separated by the NHþ 4 ions. Similar chains are found in the unique crystal structure of (NH4)4ThF8. This latter compound contains, however, an additional fluoride ion that is not coordinated to any Th4þ so that it should be formulated as (NH4)4[ThF7]F (Ryan et al., 1969). As far as structural data are known, the compounds found in the TlF/ThF4 system show a close relationship to the respective fluorides of the larger alkali metal ions (Avignant and Cousseins, 1970). Slight deviations may be observed as can be seen from the structure of Tl3ThF7 and are usually attributed to the stereochemical activity of the lone electron pair on Tlþ (Gaumet et al., 1995). Several other systems with ThF4 have been investigated with unusual components like N2H5F or even NH3OH (Table 3.8) (Sahoo and Patnaik, 1961; Satpathy and Sahoo, 1968; Glavic et al., 1973; Rai and Sahoo, 1974). Single crystal structures are not known in these cases. In addition, compounds with higher valent ions have been investigated. With divalent cations, a number of compounds are known that have essentially the LaF3 structure type, wherein the La3þ positions are filled by Th4þ and the divalent cation, respectively (Zachariasen, 1949a; Keller and Salzer, 1967; Brunton, 1973). Anion‐rich fluorides can be obtained when a small amount of Th4þ is doped in the CaF2 lattice and complicated phases with severe disorder in the cation and anion lattice are described for lanthanide‐containing compounds like SmTh2F11 (Abaouz et al., 1997). Finally, the zirconium thorium fluoride ThZr2F12 is completely ordered and contains layers of vertex‐shared [ZrF8] polyhedra that alternate with layers of Th4þ ions in nine‐fold coordination by F− ions (Taoudi et al., 1996).

92

Thorium

A few hydrates of ternary thorium fluorides are known. Probably the most remarkable hydrate has the composition (NH4)7Th2F15 · H2O (Penneman et al., 1968, 1976) and contains the dimeric anion [Th2F15(H2O)]7− in which the Th4þ ions are linked via three fluoride ions. Furthermore the lanthanide‐containing phases LaTh4F19 · H2O and ThEr2F10 · H2O have been reported in which the lanthanide and the Th4þ ions occupy the same sites (Guery et al., 1994; Le Berre et al., 2000). Finally, the fluoride hydroxide Li3Th5F22OH should be mentioned, which incorporates the Liþ ions in a three‐dimensional network of [ThF9] and [ThF8OH] polyhedra (Cousson et al., 1979a). Polynary thorium fluorides with more than one additional cation have been rarely characterized (Table 3.9). Structural data are available for Na3Li4Th6F31 (Brunton and Sears, 1969), KNaThF6 (Brunton, 1970), Li2CaThF8 (Vedrine et al., 1973), Na3BeTh10F45 (Brunton, 1973), and Na3ZnTh6F29 (Cousson et al., 1979b). Na3Li4Th6F31 has the same structure as Na7Th6F31, with some of the Naþ ions being substituted by Liþ. Similarly, the structure of KNaThF6 is closely related to the structure of the potassium‐only compound. Li2CaThF8 adopts the structure of CaWO4, even if the symmetry is slightly different. The Liþ ions occupy the tetrahedral positions of the tungsten atoms, while both Ca2þ and Th4þ are found on the calcium sites of CaWO4. Na3BeTh10F45 and Na3ZnTh6F29 (Fig. 3.11) have crystal structures wherein the Th4þ ions are found mainly in an eight‐fold coordination of fluoride ions (Brunton, 1973). The thorium polyhedra are linked in complicated three‐dimensional networks

Fig. 3.11 Crystal structure of the polynary Na3ZnTh6F29.

Important compounds

93

that incorporate the Naþ, Be2þ, and Zn2þ ions, respectively. The coordination number of the sodium ions range from six to eight. Be2þ is tetrahedrally coordinated, and Zn2þ is in the center of an octahedron. Mixed chloride–fluorides, namely LiThClF4, CsTh2ClF8, SrThCl2F4, and BaThCl2F8, have been reported but these compounds are in need of further characterization (Gudaitis et al., 1972; Desyatnik et al., 1974a,b). Compared to the respective fluorides the number of well‐characterized polynary thorium chlorides, bromides, or iodides is quite limited. According to phase diagram investigations containing ThCl4, the compounds included in Table 3.8 are known to exist (Vdovenko et al., 1974; Gershanovich and Suglobova, 1980). However, additional chlorides, which were not found in their respective phase diagrams, have been prepared by several authors (Rosenheim and Schilling, 1900; Rosenheim et al., 1903; Chauvenet, 1911; Siegel, 1956; Ferraro, 1957; Adams et al., 1963; Brown, 1966; Vokhmyakov et al., 1973; Gorbunov et al., 1974; Desyatnik and Emel’yanov, 1975). Unfortunately, the structure of only a few chlorides is known, all of them being exclusively hexachlorothorates containing the octahedral [ThCl6]2− anion. Alkaline metal ions, Tlþ and Cuþ, as well as divalent ions, for example Ba2þ or Pb2þ, may serve as counter‐ions (Binnewies and Scha¨fer, 1973, 1974; Gorbunov et al., 1974; Westland and Tarafder, 1983). Furthermore, alkyl ammonium ions can be used to crystallize the hexachlorothorate (Brown, 1966; Woodward and Ware, 1968). Occasionally, complex [ThCl5]− and [ThCl7]3− ions have been mentioned in the literature (Oyamada and Yoshida, 1975; Yoshida et al., 1978). The enthalpies of formation of several thorium–alkali metal ternary chlorides have been reported. Experimental data on these chlorides, together with those on other actinide ternary halides are assembled and briefly discussed in Chapter 19. Chloro compounds of thorium in which one or more chloride ions in ThCl4 are replaced by other ligands have been prepared. These ligands can be trimethysilylamide, benzaldehyde, and methylsalicylate, for example (Bradley et al., 1974). The phase diagrams of ThBr4 and the alkali metal bromides NaBr–CsBr show one compound to exist in each case (Ribas Bernat and Ramos Alonso, 1976; Ribas Bernat et al., 1977; Gershanovich and Suglobova, 1981). For sodium, NaThBr5 melts incongruently, and for the remaining alkali metals, the bromides A2ThBr6 (A ¼ K – Cs) melt congruently. The structure of the equivalent sodium compound is not known, but for the compounds with heavier alkali metals, the lattice parameters have been derived from powder diffraction data. Although the data are not in entire agreement, it seems very likely that these compounds are (nearly) isotypic with the respective iodides and thus contain the octahedral [ThBr6]2− anion. The same anion also occurs in the family of bromides, AThBr6, with A being a divalent cation (cf. Table 3.9) (Beck and Ku¨hn, 1995). An interesting exception is the unique crystal structure of In2ThBr6. It contains square antiprismatic [ThBr8] polyhedra that are linked in

94

Thorium

Fig. 3.12 Octahedral [Th6] cluster in the crystal structures of Th6Br15Co and Th6Br14H7, respectively. The cobalt atom as well as the hydrogen atoms are stabilizing the cluster, which are surrounded by 18 Br− ions. The hydrogen position are only occupied to 7/8.

chains along [001] according to the formula 11 ½ThBrF4=2 Br4=1  via shared edges. The chains are held together by nine‐fold coordinated Inþ ions (Dronskowski, 1995). A series of reduced thorium bromides containing octahedral [Th6] clusters has been described recently. They have been prepared from ThBr4 and thorium metal in the presence of either hydrogen, carbon, or a transition metal, leading to the compounds: MTh6Br15 (M ¼ Mn, Fe, Co, Ni), Th6Br14C, and Th6Br15H7 (Bo¨ttcher et al., 1991a,b). The transition metal and the carbon atom act as a stabilizing interstitial atom within the octahedron whereas the hydrogen atoms are located above the triangular faces of the empty octahedra. In each case, the [Th6] core is surrounded by 12 Br− ions that are bridging the edges of the octahedron, and six additional anions attached to the vertices. The linkage of the [(Th6Br12)Br6] units is different in Th6Br14C compared to the metal‐centered cubic phases, causing the slightly higher Th/Br ratio (Fig. 3.12). Another unique cluster compound is KTh12N6Br29. It shows a core of six [NTh4] tetrahedra that are connected by sharing edges (Fig. 3.13) (Braun et al., 1995). Ternary iodides containing the octahedral [ThI6]2− anion have been prepared with a number of different counter‐cations, for example alkali metal ions, tetraalkyl ammonium ions, or [As(C6H5)4]þ (Bagnall et al., 1965; Brown et al., 1970a, 1976; Brendel et al., 1985). The ThI4/AI2 systems with A being Ca, Sr, Sn, or Pb, have been investigated and for selected examples crystal structures have even been determined (Beck et al., 1993). Ternary iodides have also been synthesized by the fusion of the binary iodides at elevated temperature with other divalent cations (Beck et al., 1993). Finally, the mercury iodides Hg2ThI8·12H2O and Hg5ThI14·18H2O have been reported (Duboin, 1909a).

Important compounds

95

Fig. 3.13 [Th12N6] core in the crystal structure of KTh12N6Br29. The unit consists of six linked [NTh4] tetrahedra. It might also be seen as an [Th6] octahedron whith four of the six triangular faces capped by an additional thorium atom.

3.7.5

Chalcogenides

The heavier analogs of oxides, the chalcogenides S, Se, and Te, all form compounds with thorium (Table 3.6). While some are based on simple crystal structures such as fluorite or NaCl, the richness of the electronic structures of sulfur, selenium, and tellurium lend themselves to forming more complex structures than the oxides. Binary thorium sulfur compounds can be prepared by the action of H2S on the metal (Berzelius, 1829; Nilson, 1876; Moissan and E´tard, 1896, 1897), the metal halide (Kru¨ss and Volck, 1894; Duboin, 1908b), the metal hydride (Eastman et al., 1950; Lipkind and Newton, 1952), or on thoria itself in the presence of carbon (Eastman et al., 1950). Sulfur will react at elevated temperatures with the metal or thorium carbide and CS2 with thoria will also form the binary sulfides. There are six generally recognized structurally characterized sulfides (including ThOS, which is not isostructural with ThS2 or ThO2) listed in Table 3.6 (Shalek, 1963). The sulfide with the lowest sulfur content (Khan and Peterson, 1976), ThS, stands out against ThO as not being like ZnS but rather forming the NaCl structure type (Zachariasen, 1949c). However, as mentioned earlier, the characterization of ThO remains a puzzle. ThS is metallic in appearance with a density of 9.56 g cm−3. The compound

96

Thorium

sinters above 1950 C with no appreciable vapor pressure above its melting point (2200 C). The compound can be machined or polished and becomes superconducting near 0.5 K (Moodenbaugh et al., 1978). The disulfide of thorium, ThS2, is a purple‐brown solid with the PbCl2 structure and a density of 7.36 g cm−3. It is reported to melt at 1905 C with considerable decomposition starting at 1500 C (Eastman et al., 1950, 1951). Heating the disulfide in vacuum will yield a black phase, Th7S12, which melts around 1770 C (Zachariasen, 1949d; Eastman et al., 1950, 1951). This compound has been mislabeled as Th4S7. The sesquisulfide is a brown‐metallic phase, isotypic with stibnite, Sb2S3 (Zachariasen, 1949c). This phase also melts with no appreciable vapor pressure at high temperatures (2000 C), making it a useful high‐temperature crucible material. An orange‐brown material has been prepared via a lower‐temperature reaction (400 C) between thorium metal and sulfur or between the hydride and excess H2S. A ‘polysulfide’ phase was first identified as Th3S7 (Strotzer and Zumbusch, 1941) and later found (Graham and McTaggart, 1960) to evolve sulfur around 150 C to yield Th2S5, of tetragonal structure, although more recent studies found that it is correctly reported in the orthorhombic cell (Noe¨l and Potel, 1982). ThOS, a yellow phase prepared from the action of thoria and CS2 or thoria and sulfur (Kru¨ss, 1894; Heindl and Loriers, 1974), forms in the PbFCl structure type, analogous with the rare earth series of compounds (Zachariasen, 1949c). ThOS hydrolyzes in acid solutions as do all the other binary sulfides of thorium (Dubrovskaya, 1971). Selenium and tellurium form a series of compounds with thorium that are homologs of the sulfides. These compounds, listed in Table 3.6, are ThOSe, ThSe, Th7Se12, Th2Se3, ThSe2, Th2Se5, and ThSe3 (D’Eye et al., 1952; D’Eye, 1953; Graham and McTaggart, 1960; Noe¨l, 1980; Kohlmann and Beck, 1999). These phases have all been obtained by the reaction of selenium on thorium metal (D’Eye et al., 1952) on the carbide, the halide, or the silicide of thorium (Moissan and Martinsen, 1905). Thorium selenides have also been produced by the reaction of hydrogen selenide gas on thorium bromide (Moissan and Martinsen, 1905). It has been reported that ThSe becomes superconducting at 1.6 K (Moodenbaugh, 1978), in contrast to earlier observations (Bucher and Staundenmann, 1968). A selenium analog to the polysulfide phase may be Th7Se12 (D’Eye, 1953) or Th2Se5 (Graham and McTaggart, 1960). Another reported polyselenide is ThSe3 (Noe¨l and Potel, 1982), which is isotypic with USe3 (Ben Salem et al., 1984). Finally, the reaction of selenium with thoria yields ThOSe (D’Eye, 1953). The tellurides of thorium exist in phases of similar stoichiometry but with slightly differing structures from those of the sulfides or selenides. For example, ThTe is found in the CsCl structure rather than the NaCl‐type (D’Eye and Sellman, 1954). Several conflicting reports exist about the identity of a higher telluride, Th3Te8, although it has been confirmed to be ThTe3, in a structure type analogous to the low‐dimensional ZrSe3‐type (Graham and McTaggart, 1960). This same report also suggests that ThTe2 is hexagonal rather than

Important compounds

97

orthorhombic as in the PbCl2‐type found for ThSe2. Recently, the missing link in the series, Th7Te12, was prepared and characterized as isostructural with the selenide (Tougait et al., 1998). An early report on ‘Th3Te’ has not been confirmed up to now and seems to be not very reliable (Montignie, 1947). During the past decade, a series of interesting ternary and quaternary thorium chalcogenide phases have been prepared (Cody and Ibers, 1996; Wu et al., 1997; Tougait et al., 1998; Narducci and Ibers, 1998a,b, 2000; Choi et al., 1998; Briggs‐Piccoli et al., 2000, 2001, 2002; Hess et al., 2001). The series of layered tellurides and selenides of thorium, ATh2Te6, are based on the sesquiselenide or telluride structure type that has been, in effect, pried apart, reduced, and intercalated by an alkali metal (Cody and Ibers, 1996; Wu et al., 1997; Tougait et al., 1998). The review by Narducci and Ibers describes these reactions in detail (1998a). Indeed, a series of related transition metal compounds such as KCuThSe3, CuTh2Te6, and SrTh2Se5 have been prepared from the action of tellurium or selenium, or their alkali metal salts, on thorium metal (Narducci and Ibers, 1998a, 2000). Attempts were also made to prepare chalcophosphate analogs of the thorium phosphates discussed in Section 3.7.7e. The unique chemistry of thiophosphates and selenophosphates provided a rich set of compounds from homoleptic clusters of [Th2(PS4)6]10− (Briggs‐Piccoli et al., 2002) to complex three‐dimensional phases with a unique (P2Se9)6− anion building block in Cs4Th4P4Se26 (Briggs‐Piccoli et al., 2001). 3.7.6

Pnictides

The nitride of thorium, Th3N4, can be prepared by a variety of methods (Gmelin, 1987). One is the strong heating of the metal in the presence of N2. At the turn of the last century, there was significant debate about the composition and color (chestnut, citron yellow, maroon, and black) of the thorium nitride that could be obtained by heating the metal in presence of N2 (Matignon and Delepine, 1907; Du¨sing and Hu¨niger, 1931). The debate lingered into the 1960s and the variations in color have been attributed to vacancies in nitrogen and oxygen impurities. Indeed, the tan‐colored Th2N3 is actually Th2N2O (Aronson and Auskern, 1966; Benz and Zachariasen, 1966). The golden yellow ThN (Chiotti, 1952; Olson and Mulford, 1965) may likely be seen as a thin layer on the surface of Th3N4 as it is the thermally stable product of all decomposition reactions of the other thorium nitrides (Aronson and Auskern, 1966). ThN displays metallic character when prepared as a thin film (Gouder et al., 2002). The ThN phase is isotypic with all other actinide mononitrides and has the NaCl fcc structure (Auskern and Aronson, 1967; Benz et al., 1967). ThN is a superconductor at low temperatures with an inverse dependence of pressure on the critical temperature (Dietrich, 1974). The synthesis of the binary nitrides listed in Table 3.10 can be achieved most easily by the action of ammonia or nitrogen on heated thorium hydride

Thorium

98

Table 3.10 Crystallographic data of thorium pnictides. Lattice parameters

Compound

Lattice symmetry

ThN

cubic

5.180

Th3N4

rhombohedral

3.87

Th2N3

rhombohedral

3.883

ThP

cubic

5.840

Th3P4

cubic

8.600

Th2P11

monoclinic

17.384

10.104

19.193

ThP7

orthorhombic

10.218

10.401

5.671

ThAs Th3As4 ThAs2

cubic cubic tetragonal

5.978 8.843 4.086

8.575

ThSb Th3Sb4 ThSb2 ThBi2

cubic cubic tetragonal tetragonal

6.318 9.371 4.352 4.492

9.172 9.298

˚) a (A

˚) b (A

˚) c (A

Angles ( )

References

b ¼ 117.62

Evans and Raynor (1959) Bowman and Arnold (1971) Zachariasen (1949a) Gingerich and Wilson (1965) Meisel (1939); Zumbusch (1941) von Schnering et al. (1980) von Schnering and Vu (1986) Ferro (1955) Ferro (1955) Ferro (1955); Pearson (1985) Ferro (1956) Ferro (1956) Ferro (1956) Pearson (1985)

27.38 6.187

(Katzin, 1983). Metal powder heated in nitrogen will yield the nitrides; in the presence of ammonia, a hydride intermediate can be formed (Juza and Gerke, 1968). These hydrogen‐containing species might be nitride‐imides, nitride‐ amides, or pure amides of thorium, as investigations of the system Th–N–H have shown. Thoria treated with carbon and heated in a nitrogen atmosphere will also yield nitrides where a finely divided metal powder can be seen as an intermediate. The reaction of binary nitrides with thorium halides leads to the halide nitrides ThNX (X ¼ F, Cl, Br, I). They have been shown to adopt the BiOCl‐ type of structure (Juza and Sievers, 1968; Blunck and Juza, 1974). Complex metal nitrides such as Th2NOP can be prepared by heating binary nitrides with thoria and thorium phosphides (Benz and Zachariasen, 1969; Barker and Alexander, 1974). Heating the nitrides in oxygen generally yields thoria as the product and the nitrides are moisture‐sensitive. Several complex mixtures of double salts have been prepared recently, namely CaxTh3–x N4–2xO2x, SrxTh3–x N4–2xO2x, and SrxTh1–xNxO1–x (Brese and DiSalvo, 1995a). Ternary nitrides are the lithium compound Li2ThN2 (Palisaar and Juza, 1971) as well as the very unique nitride perovskite phase, TaThN3 (Brese and DiSalvo, 1995b).

Important compounds

99

This latter cubic perovskite was prepared by the action of Ta3N5 and Th3N4 at 1400 C as well as by the reaction of Ta2Th2O9 and Ca3N2 at 1500 C. The heavier pnictide analogs all form similar binary phases to the nitride that have been characterized by single crystal XRD analysis except for ThBi that is conspicuously absent (Ferro, 1957). Analogously to ThN, ThP, ThAs, and ThSb adopt the fcc NaCl structure (Ferro, 1955, 1956; Gingerich and Wilson, 1965; Javorsky and Benz, 1967; Baskin, 1969). The same structure has been reported for all of the actinide and lanthanide mononitrides and pnictides, respectively. Interestingly, the lattice constant has been shown to decrease when going from Th to U, then to increase through Cm, and finally to decrease again (Lam et al., 1974; Damien and de Novion, 1981) (Fig. 3.14). Adachi and Imoto reported that the cubic ThP could be made as ThP1–x where x varied from 0 to 0.6. This behavior dramatically affected the hardness of the phase as well as its conductivity (Adachi and Imoto, 1968). Indeed, at 1200 C, the phase ranges from ThP0.4 to ThP0.6. The non‐stoichiometric phases show a weak paramagnetism and the room temperature resistivity of the metallic ThP decreased with an increasing P/Th ratio for the ThP1–x phases. ThP forms a solid solution with UP and displays an antiferromagnetic phase transition at 23 K with up to 40% ThP (Adachi et al., 1973). ThP undergoes a

Fig. 3.14 Lattice constants of actinide and lanthanide monopnicnitides: mononitrides and monophosphides (a); monoantimonides and monoarsenides (b) (Damien and de Novion, 1981).

100

Thorium

structural phase transition from the NaCl‐type to the CsCl‐type at 30 GPa (Staun Olsen et al., 1988). The reaction between Th and Th3P4 at 1100 C will yield ThP (Gingerich and Wilson, 1965; Gingerich and Aronson, 1966; Javorsky and Benz, 1967). Th3P4 can be made by the direct combination of the elements (Gingerich and Wilson, 1965; Price and Warren, 1965), by heating ThCl4 with phosphorus vapors (Moissan and Martinsen, 1905), and by the reaction of the hydride with phosphine gas (Lipkind and Newton, 1952). This phase of phosphide is a dark gray material, unlike the black ThP, and is unreactive in water. It releases phosphine upon action by acids and can be ignited to thorium phosphate by heating in air (Strotzer et al., 1938; Meisel, 1939). Th3P4 is an n‐type semiconductor with a band gap of 0.4 eV (Henkie et al., 1976; Suzuki et al., 1982). A very unique, phosphorus‐rich Zintl phase was prepared by the action of phosphorus on thorium metal at 1040 C, yielding Th2P11 (von Schnering et al., 1980). This phase comprises chains of phosphorus atoms linked into two‐ dimensional nets comprising open and closed P6 rings. This black, semiconducting phase (band gap of 0.3 eV) decomposes to Th3P4 upon heating to 1040 C in vacuum. Other complex ternary phosphides are known including Th5Fe19P12, ThFe4P2, and Th2Mn12P7 (Albering and Jeitschko, 1992; Jeitschko et al., 1993). Finally, a dense, magnetoresistive skutterudite phase can be prepared from the elements to yield ThFe4P12 (Dordevic et al., 1999). In the thorium–arsenic system, ThAs and Th3As4 are black‐gray compounds that are isomorphous with the associated phosphides and nitrides (Benz, 1968). Th3As4 is an n‐type semiconductor with a band gap of 0.43 eV (Ferro, 1955; Warren and Price, 1964; Henkie and Markowski, 1978). In contrast to the Th–P system, a diarsenide, ThAs2, is formed, which displays two modifications: a low‐ temperature phase (a), with the PbCl structure and a high‐temperature phase (b) with the Fe2As structure (Ferro, 1955; Hulliger, 1966). More complex mixtures of ThAs and ThS or ThSe have yielded compounds such as ThAsSe that display unique anomalous Kondo‐like behavior (Henkie and Wawryk, 2002). Thorium antimony compounds form in the same structures as the arsenides, with ThSb, Th3Sb4, and ThSb2 (Ferro, 1956; Hulliger, 1966, Chiotti et al., 1981). Like the arsenide, ThSb undergoes a high‐pressure phase transition from NaCl to the CsCl‐type (Palanivel et al., 1995). Kondo‐like resistivity behavior was observed for solid solutions of USb and ThSb. The dilution of USb by ThSb lead to large modifications of the electrical transport properties, reflecting the change from antiferromagnetism to ferromagnetism with a concomitant decrease of the ordered magnetic moment per U atom (Frick et al., 1982). In the thorium–bismuth system, three binary compounds with familiar structures are found: ThBi, ThBi2, and Th3Bi4 (Ferro, 1957; Dahlke et al., 1969). ThBi was reported as part of an alloy structure although a single crystal structure has not been determined (Borzone et al., 1982). Another phase with the Mn5Si3‐type was observed as well but was not confirmed by elemental analysis (Borzone et al., 1982). Bismuth can be distilled from ThBi, yielding the thorium‐rich Th5Bi3 hexagonal structure. During the U.S. breeder reactor

Important compounds

101

program of the mid–1950s, breeder‐blanket liquid Bi with a slurry of ThBi2 suspended in the liquid bismuth showed promise but there was significant difficulty in suspending the inhomogeneous particles of ThBi2 (Bryner and Brodsky, 1959). 3.7.7

Complex anions

Thorium compounds with complex anions play an important role in various fields, for example in separation techniques (cf. Section 3.4) and nuclear waste disposal, to name only two of them. Thus, this chemistry has been widely investigated, although often not in very detail, what is especially true with respect to structural characterizations. In the following the most important and more recent findings are summarized. For each complex anion an extra subdivision has been created and reliable crystallograhic data are presented in Table 3.11. (a)

Perchlorates

Thorium perchlorate is highly soluble in water and crystallizes, generally from acidic solution, in the form of the tetrahydrate Th(ClO4)4·4H2O (Murthy and Patel, 1965). The structure of the tetrahydrate is not known, but the compound has been shown to decompose at 280 C to form ThO(ClO4)2 that finally forms ThO2 at 335 C (Murthy and Patel, 1965). The oxide–perchlorate apparently will dissolve in water, and from XRD this is interpreted to be due to the formation of a tetrameric species (Bacon and Brown, 1969). An elegant (but somewhat dangerous) route to prepare anhydrous Th(ClO4)4 is the reaction of ThCl4 with Cl2O6 (Koulke`s‐Pujo et al., 1982). From X‐ray powder diffraction, an orthorhombic lattice has been deduced with the space group probably being P21212 (Ramamurthy and Patel, 1963). Due to the weak coordination tendency of the ClO 4 ion, Th(ClO4)4 is frequently used to prepare coordination compounds of thorium in which the perchlorate anion in not included in the coordination sphere (Gmelin, 1985b, 1993a). (b)

Sulfates (VI, IV)

A detailed discussion of the older literature on thorium sulfates has been given by Mellor (1941). Thorium sulfates can be prepared by the reaction of various thorium salts, for example thorium nitrate, with concentrated sulfuric acid. Upon crystallization from aqueous solution, different hydrates can be obtained. At lower temperatures (0–45 C), Th(SO4)2·9H2O has the lowest solubility (Cle`ve, 1874; Roozeboom, 1890; Dawson and Williams, 1899). Nevertheless, the octahydrate is usually obtained even under these conditions (Cle`ve, 1874; Kru¨ss and Nilson, 1887b; Roozeboom, 1890; Koppel and Holtkamp, 1910). Furthermore, a hexahydrate has been mentioned and at higher temperature,

Space group P21/n Pnma C1 P21/c P21/c Fdd2 P21/n P21/c P21/n P21/c B11b P1 P212121 R3 Pa3 C2/c C2/c C2/c C2/c C2/c

Compound

Th(SO4)2·8H2O Th(OH)2SO4 K4Th(SO4)4·2H2O

Na2Th(SO4)3·6H2O Cs2Th(SO4)3·2H2O Th(NO3)4·5H2O Th(NO3)4·4H2O ThOH(NO3)3·4H2O (NH4)2Th(NO3)6 MgTh(NO3)6·8H2O

(C(NH2)3)6Th(CO3)5·4H2O Na6Th(CO3)5(H2O)12

(C(NH2)3)5(Th(CO3)3F3) Na6BaTh(CO3)6(H2O)6 Th(P2O7) KTh2(PO4)3 NaTh2(PO4)3 Pb0.5Th2(PO4)3 CuTh2(PO4)3 Na2Th(PO4)2 9.53 14.175 8.721 17.57 17.37 17.459 22.029 7.01

16.15 9.60

5.567 6.415 11.191 7.438 6.772 8.321 9.080

8.51 11.733 10.096

˚) a (A

9.11 8.605 8.138 8.13 8.1438 7.0191 9.12

6.863 6.81 6.8451 6.7430 21.50

13.23 13.64

15.76 13.078 10.579 9.183 13.769 13.097 13.610

13.46 7.059 9.762

˚) c (A

29.79

16.70 9.92

16.81 15.95 22.89 17.530 11.693 6.890 8.750

11.86 6.040 16.75

˚) b (A

Lattice parameters

b ¼ 101.77 b ¼ 101.13 b ¼ 101.25 b ¼ 108.58 b ¼ 111.02

γ ¼ 108.42 a ¼ 90.47 b ¼ 104.38 γ ¼ 95.52

b ¼ 99.72 b ¼ 102.63 b ¼ 91.55 b ¼ 97.03

Voliotis (1979) Yamnova et al. (1990) Burdese and Borlera (1963) Matkovic et al. (1968) Matkovic et al. (1970) El‐Yacoubi et al. (1997) Louer et al. (1995) Galesic et al. (1984)

Voliotis and Rimsky (1988) Voliotis and Rimsky (1975)

Habash and Smith (1990) Habash and Smith (1992) Taylor et al. (1966) Charpin et al. (1987) Johansson (1968a) Spirlet et al. (1992) Scavnicar and Prodic (1965)

Habash and Smith (1983) Lundgren (1950) Arutyunyan et al. (1963)

b ¼ 92.65 a ¼ 95.15 b ¼ 95.22 γ ¼ 91.00 b ¼ 91.925 b ¼ 90.88

References

Angles ( )

Table 3.11 Crystallographic data of thorium compounds with oxo anions.

P212121 P1 P21/c Pcam C2/c Pnnm I41/a I41/amd P21/n Pn21a Pbca P3 C2/c I41/a P1 I43d P63/m P21/m I41/amd P21/n I422 R3c

KTh(P3O10) Na6(Th(PO4)(P2O7))2

Na2Th(PO4)2 Th4(PO4)4(P2O7)

KTh2(VO4)3 ThV2O7 Pb0.5Th0.5(VO4) Pb0.5Th0.5(VO4) Pb0.5Th0.5(VO4) Th(VO3)2O

Th(MoO4)2‐I Th(MoO4)2‐II K2Th(MoO4)3 K4Th(MoO4)4 K8Th(MoO4)6

Cu2Th4(MoO4)9 CdTh(MoO4)3

Th(OH)2CrO4·H2O ThSiO4 ThSiO4 Ca2ThSi8O20 Na12Th3(Si8O19)4·18H2O 7.67 7.133 6.784 7.483 29.124

14.477 9.803

10.318 17.593 17.649 11.586 10.255

18.564 7.216 5.175 7.428 7.046 7.201

7.055 12.865

8.234 8.734

6.974

6.11

10.260

12.143

9.737

7.3089 22.771

7.157 6.964

21.66 10.437

10.187 8.931

6.94 6.319 6.500 14.893 17.260

6.350

14.475 6.238 5.3688 13.069 14.466

8.077 22.80 11.943 6.590 6.8066 6.945

9.095 7.0676

10.015 6.468

b ¼ 104.92

b ¼ 113.91

a ¼ 75.87 b ¼ 96.81 γ ¼ 118.43

b ¼ 105.76

b ¼ 101.05

a ¼ 93.33 b ¼ 108.29 γ ¼ 110.10 b ¼ 111.56

Lundgren and Sillen (1949) Taylor and Ewing (1978) Taylor and Ewing (1978) Szymanski et al. (1982) Li et al. (2000)

Launay et al. (1998) Launay and Rimsky (1980)

Cremers et al. (1983) Larson et al. (1989) Huyghe et al. (1991a) Huyghe et al. (1991b) Huyghe et al. (1993)

Quarton and Kahn (1979) Quarton et al. (1970) Andreetti et al. (1984) Andreetti et al. (1984) Andreetti et al. (1984) Launay et al. (1992)

Galesic et al. (1984) Be´nard et al. (1996)

Ruzic Toros et al. (1974) Kojic‐Prodic et al. (1982)

104

Thorium

Fig. 3.15 The [Th(SO4)2(H2O)6] molecule in the crystal structure of Th(SO4)2·8H2O.

a tetrahydrate is said to form (Roozeboom, 1890; Dawson and Williams, 1899; Wirth, 1912). A dihydrate was observed as an intermediate of the dehydration of higher hydrates (Rollefson, 1947) and Th(SO4)2·8H2O has been structurally characterized (Fig. 3.15). It shows the Th4þ ions in a ten‐fold coordination by oxygen atoms, which belong to six water molecules and two chelating sulfate ions. The coordination polyhedron is a distorted bicapped squared antiprism. The crystal structure is completed by two crystal water molecules (Habash and Smith, 1983). The formation of basic thorium sulfates has also been frequently observed but these compounds are not well characterized (Kru¨ss and Nilson, 1887b; Wyrouboff and Verneuil, 1898b, 1899; Meyer and Gumperz, 1905). ThOSO4 has been reported to form upon dehydration of ThOSO4·3H2O but none of these compounds has been further investigated (Wyrouboff, 1901; Wo¨hler et al., 1908; Hauser and Wirth, 1908; Barre, 1910, 1911; Halla, 1912). The structure is known only for Th(OH)2SO4, which has been thought to be ThOSO4·H2O (Lundgren, 1950). The thorium ions are connected as dimers by two OH− ions. The coordination sphere of Th4þ is completed by four monodentate sulfate groups and the dimeric [Th2(OH)2(SO4)8] units are linked into a three‐ dimensional network. Various polynary sulfates containing alkali metals are thought to exist (Colani, 1909; Barre, 1912). The phase diagram of Na2SO4/Th(SO4)2 has been determined recently wherein the compound Na12Th(SO4)8 is found (Fedorov and Fedorov, 2001). Solid state reactions of ThO2 with KHSO4, K2S2O8, and K2S2O7 afforded K4Th(SO4)4 (Keskar et al., 2000). Also the reactions of ThO2 with (NH4)2SO4, and mixtures of (NH4)2SO4 with NH4NO3 or NH4HF, have

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been studied (Singh Mudher et al., 1995). Furthermore, the rubidium compound, Rb2Th(SO4)3, has been synthesized. Despite these investigations no structural data of the anhydrous species have been reported until now. A little more information is available for the hydrated polynary sulfates (Cleve, 1874; Manuelli and Gasparinetti, 1902; Rosenheim et al., 1903; Barre, 1910, 1911). According to very old data, they may contain alkali and thorium metal ions in a ratio of 1:1, 2:1, 3:1, and 4:1, but newer investigations determined the compositions as A2Th(SO4)3·xH2O and A4Th(SO4)4·xH2O (A ¼ Na–Cs, NH4) (Gmelin, 1986b), where the water content x varies from 2 to 6. Additionally, M6Th(SO4)5·3H2O (M ¼ Cs, NH4) and (NH4)8Th(SO4)6·2H2O are known (Gmelin, 1986b). For several compounds, infrared spectroscopy (IR) data are available (Evstaf’eva et al., 1966) and structure determinations have been done for Na2Th(SO4)3·6H2O (Habash and Smith, 1990), Cs2Th(SO4)3·2H2O (Habash and Smith, 1992), and K4Th(SO4)4·2H2O (Arutyunyan et al., 1963). The sodium compound exhibits chains of 11 ½ThðH2 OÞ3=1 ðSO4 Þ6=2  running along [100] in which the Th4þ ions are surrounded by six monodentate SO2‐ 4 ions and three H2O molecules to form a tricapped trigonal prism. The chains are linked by the Naþ ions and three non‐coordinating water molecules are found in the unit cell. In Cs2Th(SO4)3·2H2O the [Th(H2O)2(SO4)5] polyhedra are linked to layers according to 21 ½ThðH2 OÞ2 ðSO4 Þ4=2 ðSO4 Þ1=1  that are connected by the Csþ ions. For the Th4þ ions a coordination number of nine arises due to the chelating nature of two of the SO2 4 groups. In K4Th(SO4)4·2H2O zigzag chains are found with the formula 11 ½ThðH2 OÞ2=1 ðSO4 Þ4=2 ðSO4 Þ2=1 . One of the SO2 4 ions acts as chelating ligand leading to a coordination number of 9 for Th4þ. Thorium sulfates containing other counter‐cations besides alkali metals are rarely described. They include the manganese compound MnTh(SO4)3·7H2O that was obtained from an aqueous solution of the binary sulfates at 30 C, the tin compound, Sn2Th(SO4)4·2H2O (Weinland and Ku¨hl, 1907), and the poorly characterized thallium sulfates (Fernandes, 1925). Finally, the organic guanidinium ion has been used for the precipitation of thorium sulfato complexes (Molodkin et al., 1964). With Th(SO3F)4, one fluorosulfate of thorium has been synthesized by the reaction of HSO3F with thorium acetate. According to IR measurements the anions act as bidentate ligands. The thermal decomposition of the compound yields SO2F2 and Th(SO4)2 (Paul et al., 1981). Thorium sulfate (IV), Th(SO3)2·xH2O, is said to form as a white precipitate when SO2 is passed through a solution containing Th4þ ions or when an alkali metal sulfite is added (Cle`ve, 1874; Chavastelon, 1900; Baskerville, 1901; Grossmann, 1905). Based on differential thermal analysis (DTA) investigations, the water content x is believed to be four (Golovnya et al., 1967a,b). Hydrolysis of the thorium sulfites or their thermal decomposition leads to basic compounds with different compositions (Golovnya et al., 1964, 1967a). Furthermore, various ternary sulfites containing alkali metal ions or the ammonium ion have been mentioned, but a more precise characterization is needed for these compounds

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(Chavastelon, 1900; Golovnya et al., 1967b,c). A number of organic solvates of thorium sulfites are reported, but again, further characterization is still needed (Golovnya et al., 1967b). (c)

Nitrates

Nitrates of thorium may be prepared by dissolving Th(OH)4 in nitric acid. Depending on the concentration of the acid, three different hydrates form upon evaporation. If the acid concentration is in the range between 1 and 54%, a pentahydrate crystallizes while a tetrahydrate is obtained at concentrations up to 75% (Ferraro et al., 1954). Both hydrates have molecular structures. The tetrahydrate contains [Th(NO3)4(H2O)4] molecules with all of the nitrate groups being attached in a chelating manner to the Th4þ ions, leading to a coordination number of 12 (Charpin et al., 1987). In the non‐centrosymmetric pentahydrate, Th(NO3)4 · 5H2O, there are also four chelating nitrate groups around Th4þ but only three additional H2O molecules, yielding a coordination number of 11. The remaining water molecules are held via hydrogen bonds in the structure so that the compound has to be formulated according to [Th(NO3)4(H2O)3] · 2H2O (Ueki et al., 1966). The structure of the pentahydrate has also been determined by neutron diffraction so that exact hydrogen positions are known (Taylor et al., 1966). Furthermore, thermodynamic data have been provided for the pentahydrate (Ferraro et al., 1956; Cheda et al., 1976; Morss and McCue, 1976). From nearly neutral solutions, a hexahydrate was said to crystallize (Fuhse, 1897; Misciatelli, 1930a,b). Unfortunately it has not been structurally characterized and due to the well‐known tendency of Th4þ compounds to hydrolyze, it might be possible that the hexahydrate is in fact a basic species. With ThOH(NO3)3 · 4H2O, another basic nitrate is known (Johansson, 1968a,b). As seen in Fig. 3.16, it contains the dimers [Th2(OH)2(NO3)6(H2O)6], with the Th4þ ions in an 11‐fold coordination by three H2O molecules, two hydroxide ions, and three chelating nitrate groups. The dimers are arranged in the lattice with additional crystal water molecules. The thermal decomposition of thorium nitrate hydrates leads to ThO2. According to DTA and thermogravimetry (TG) measurements, various intermediates can be observed (Tiwari and Sinha, 1980). Acidic thorium nitrates have been reported, for example H2Th(NO3)6·3H2O, but unfortunately they have not been characterized (Moseley et al., 1971). Also Th(NO3)4·2N2O5, which is said to form in highly concentrated HNO3, has not been investigated further (Kolb, 1913; Misciatelli, 1930a,b; Ferraro et al., 1954, 1955). Thorium nitrate is well soluble in water and various oxygen‐containing organic solvents such as alcohols, ketones, ethers, and esters (Imre, 1927; Misciatelli, 1929; Templeton and Hall, 1947; Rothschild et al., 1948; Yaffe, 1949; Bock and Bock, 1950). The solid solvate Th(NO3)4 · 3H2O · 3C2H5OCH2CH2OC2H5 has been crystallized from a solution of thorium

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Fig. 3.16 The dimeric unit [Th2(OH)2(NO3)6(H2O)6] in the crystal structure of ThOH(NO3)3·4H2O.

nitrate in the diethylether of ethyleneglycol (Katzin, 1948), and compounds with a variety of nitrogen bases in place of water are known (Kolb et al., 1908; Kolb, 1913). It is possible to extract thorium nitrate from aqueous solution with an immiscible organic solvent if the aqueous phase is extremely concentrated, or if it contains high concentrations of ammonium nitrate (Templeton and Hall, 1947; Rothschild et al., 1948; Hyde and Wolf, 1952; Newton et al., 1952b). Since the rare earth metal ions do not extract well under the same conditions, being almost totally restricted to the aqueous phase, the procedure finds application in the preparation of pure thorium salts from ores containing rare earth elements. A particularly useful liquid extractant is tri(n‐butyl)phosphate (TBP) (Warf, 1949; Anderson, 1950), as well as other phosphate esters (Peppard, 1966, 1971; Shoun and McDowell, 1980). These compounds differ from ordinary nucleophilic solvents in that they interact specifically with the metal ion through the oxygen atom of the phosphoryl group to form a very strong solvation bond. In the case of thorium nitrate, this results in the formation of very stable complexes in the organic phase, with two and three molecules of phosphate per molecule of thorium nitrate (Katzin et al., 1956). The TBP adduct is stable even against considerable dilution with ‘inert’ fluids such as benzene, CCl4, or aliphatic hydrocarbons, which are themselves not solvents for thorium nitrate (Anderson, 1950; Katzin et al., 1956). The coordination interaction of Th4þ in aqueous solution with phosphate esters is the basis of an important commercial

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process for the extraction and purification of thorium. Normally, addition of ammonia to the aqueous phase causes the formation of hydroxo complexes that reduce the efficiency of the thorium nitrate extraction. If this is coupled with addition of a neutral salting agent such as lithium nitrate, it is found that extraction is enhanced by formation of a hydroxynitrate of thorium. The polymeric complex has been formulated as [Th4(OH)10(NO3)6(TBP)4], thus contains one tri(n‐butyl)phosphate molecule per thorium atom in contrast to the monomeric unhydrolyzed thorium nitrate complex (Klyuchnikov et al., 1972). Thorium nitrate forms 1:1 or 1:2 complexes with crown ethers, depending on the size of the crown (Zhou et al., 1981; Rozen et al., 1982; Wang et al., 1982). These can also be used as extractants (Wang et al., 1983). Organic donor molecules such as butylamine, dimethylamine, aromatic amine N‐oxides, and others have been frequently used to prepare complexes with thorium nitrate (Rickard and Woolard, 1978). A compound with trimethylphosphine oxide, Th(NO3)4 · 3/8(Me3PO), has been crystallographically characterized (Alcock et al., 1978). It contains [Th(NO3)3(Me3PO)]þ cations and [Th(NO3)6]2− anions, a structural feature that is frequently displayed by transition metal–halide complexes (Katzin, 1966). A number of ternary thorium nitrates with mono or divalent counter‐cations are known (Jacoby, 1901; Meyer and Jacoby, 1901; Sachs, 1901). Those of the type A2Th(NO3)6 contains the complex anion [Th(NO3)6]2− that shows the Th4þ ion in 12‐fold coordination by oxygen atoms (Spirlet et al., 1992). The latter contains six chelating nitrate groups, as it was shown from the structure determination of the ammonium compound. The same complex anion is found in the nitrates BTh(NO3)6 · 8H2O with B ¼ Mg, Mn, Co, Ni, Zn (Geipel, 1992). In this case, the counter‐ions are octahedral [B(H2O)6]2þ complexes according to the formulation [B(H2O)6][Th(NO3)6] · 2H2O (Scavnicar and Prodic, 1965). Another series of ternary nitrates with monovalent cations includes members of the composition ATh(NO3)5·xH2O, with A ¼ NH4, Na, K. They have not been fully characterized, so the amount of crystal water is not known (Meyer and Jacoby, 1901; Molodkin et al., 1971; Volkov et al., 1974). Furthermore, the nitrates K3Th(NO3)7 and K3H3Th(NO3)10·4H2O have been reported, but again structural data are not known (Meyer and Jacoby, 1901; Molodkin et al., 1971). (d)

Carbonates

Thorium hydroxide absorbs CO2 readily (Berzelius, 1829; Chydenius, 1863; Cle`ve, 1885; Chauvenet, 1911), where the end product is the hydrated ThOCO3, and finally Th(CO3)2·0.5H2O under high CO2 pressures. The composition of this latter product has also been given as Th(OH)2CO3·2H2O (Kharitonov et al., 1969). Hydrates of the oxycarbonate are also produced by the action of sodium or ammonium carbonate on a solution of a thorium salt. The carbonate is somewhat soluble in excess alkali carbonate solution (Cle`ve, 1885) because of the formation of complexes strong enough to prevent

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precipitation of thorium by ammonia, fluoride, or phosphate. Sodium hydroxide, however, will bring about precipitation (Sollman and Brown, 1907). The nature of the carbonato complexes (Dervin and Faucherre, 1973a,b; Shetty et al., 1976) will be discussed in more detail in Section 3.8. Crystallization of these complexes is possible using various counter‐cations, and compounds with Naþ, Kþ, Tlþ, NH4 +, (HGua)þ (guanidinium), Ca2þ, Ba2þ, and [Co(NH3)6]3þ have been reported (Cle`ve, 1874; Rosenheim et al., 1903; Canneri, 1925; Rosenheim and Kelmy, 1932; Chernyaev et al., 1958; Kharitonov et al., 1969; Ueno and Hoshi, 1970; Dervin and Faucherre, 1973b; Dervin et al., 1973; Voliotis and Rimsky, 1975, 1988). All of the salts are hydrated and the sodium compound, Na6Th(CO3)5 · xH2O, has been reported to occur with a considerable range of hydration. In the crystal structures of Na6Th(CO3)5 · 12H2O and [C(NH2)3]6Th(CO3)5·4H2O, the Th4þ ions are in ten‐fold coordination by oxygen atoms (Voliotis et al., 1977). In the mineral tuliokite, Na6BaTh(CO3)6 · 6H2O, six chelating carbonate groups are attached to the Th4þ ion leading to a [ThO12] icosahedron (Yamnova et al., 1990). Carbonates containing additional anions have been reported, for example Na5Th(CO3)4OH · 9H2O, Na4Th(CO3)4 · 7H2O, (HGua)4Th(CO3)4 · 6H2O, (HGua)2Th(CO3)3 · 5H2O, K3Th(CO3)3(OH) · 5H2O, (NH4)2Th(CO3)3 · 6H2O, Na2Th(CO3)2(OH)2 · 10H2O, K2Th(CO3)2(OH)2 · 10H2O, and the fluoride carbonate (HGua)5Th(CO3)3F3 (Voliotis, 1979). (e)

Phosphates

Phosphates of thorium have been investigated for many years (Troost and Ouvrard, 1885; Johnson, 1889; Kauffmann, 1899; Hecht, 1928; King, 1945; Dupuis and Duval, 1949; Burdese and Borlera, 1963; Hubin, 1971; Laud, 1971). More recent studies were carried out in relation with the potential of phosphate matrices to be used as radioactive waste storage material, due to their resistance to radiation effects and their low solubilities (Baglan et al., 1994; Merigou et al., 1995; Genet et al., 1996; Dacheux et al., 1998; Volkov, 1999; Brandel et al., 2001a,b). The system ThO2/P2O5 has been studied in the 1960s and the phosphates Th3(PO4)4, (ThO3)(PO4)2, (ThO)2P2O7, ThP2O7, and ThO2·0.8P2O5 have been reported. Recent investigations, however, show that ThO2·0.8P2O5 and the orthophosphate, Th3(PO4)4, do not exist (Be´nard et al., 1996; Brandel et al., 1998). Instead, the phosphate–diphosphate Th4(PO4)4P2O7 has been obtained under similar conditions. Subsequently it has been shown that the compound can be synthesized applying dry or wet preparative routes and even single crystals have been grown. Besides ThP2O7 (Burdese and Borlera, 1963), the orthophosphate–disphosphate is the only structurally known binary thorium phosphate to date, although various other species, for example ThOH(PO4) and Th2(PO4)2HPO4·H2O, have been reported (d’Ans and Dawihl, 1929; Merkusheva, 1967; Molodkin et al., 1968a; Brandel et al., 2001a,b). In the crystal structure of the orthophosphate–diphosphate

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(Be´nard et al., 1996), Th4þ is surrounded by four monodentate and one chelating PO3 4 groups and one diphosphate ion. The latter suffers from a positional disorder. In ThP2O7, the Th4þ ions are octahedrally surrounded by six monodentate P2 O4 7 ions and the polyhedra are linked in a three‐dimensional cubic network. The compound is thought to exhibit a second modification that has unfortunately not been structurally characterized. Several ternary thorium phosphates are known, especially those with additional monovalent cations like alkali metals, silver, copper, and thallium (Wallroth, 1883; Palmer, 1895; Haber, 1897; Schmid and Mooney, 1964; Matkovic and Sljukic, 1965; Matkovic et al., 1966, 1968, 1970; Molodkin et al., 1970; Topic et al., 1970; Popovic, 1971; Lau¨gt, 1973; Ruzic Toros et al., 1974; Kojic‐Prodic et al., 1982; Galesic et al., 1984; Arsalane and Ziyad, 1996). Phosphates with the composition MTh2(PO4)3 (M ¼ Na, K) show ferroelectric properties and are thus of special interest. In the crystal structure, the Th4þ ions are nine‐fold coordinated by oxygen atoms that belong to seven PO3 4 ions. Two of the latter are chelating ligands. The linkage of the polyhedra leads to parallel layers (100) that are further linked into a three‐dimensional network in [100] direction. The Naþ or Kþ ions in MTh2(PO4)3 can be replaced by Pb2þ ions, leading to the composition Pb0.5Th2(PO4)3 without structural changes (El‐Yacoubi et al., 1997). The structure of CuTh2(PO4)3 is very similar, although the coordination number of Th4þ is lowered to eight. Another characteristic feature of the structure is the linear two‐fold coordination of the Cuþ ions (Louer et al., 1995). (f )

Vanadates

The vanadates of thorium have been investigated to a much lesser extent than the respective phosphates. They seem to parallel the structural chemistry of the phosphates (Le Flem and Hagenmuller, 1964; Le Flem et al., 1965; Quarton et al., 1970; Baran et al., 1974; Elfakir et al., 1987), but high‐quality structure determinations are rare. For example, such determinations have been performed for MTh2(VO4)3 (M ¼ K, Rb) and ‘ThV2O7’ (Quarton and Kahn, 1979; Elfakir et al., 1987, 1989; Nabar and Mangaonkar, 1991; Launay et al., 1992; Pai et al., 2002). The latter compound is not a divanadate but a mixed ortho‐vanadate–catena‐vanadate with the formula Th(VO4)(VO3) (Fig. 3.17). Other structurally characterized vanadates include BaMTh(VO4)3 (M ¼ La, Pr) that adopt the monazite structure type (Nabar and Mhatre, 2001) and the silver compound, AgTh2(VO4)3, in the zircon‐type (Elfakir et al., 1990). Monazite‐, scheelite‐, and zircon‐type structures have also been frequently observed for other ternary or quaternary thorium ortho‐vanadates, namely Pb0.5Th0.5(VO4) (Botto and Baran, 1981; Andreetti et al., 1984; Calestani and Andreetti, 1984), MLaTh(VO4)3 (M ¼ Sr, Pb) (Nabar and Mhatre, 1982), and CdMTh(VO4)3 (M ¼ La, Yb) (Nabar et al., 1981). Furthermore, a hydrogenvanadate, Th (HVO4)2·5H2O, is said to precipitate, when VO3 4 is added to solution of a thorium salt (Cle`ve, 1874; Volck, 1894; Neish, 1904).

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Fig. 3.17 Crystal structure of Th(VO4)(VO3) (or ThV2O7). The structure contains isolated ortho‐vanadate ions (drawn as tetrahedra) and catena‐vanadate strands.

(g)

Molybdates

One compound, Th(MoO4)2, is found in the system ThO2/MoO3 (Zambonini, 1923; Thoret et al., 1970; Page`s and Freundlich, 1971; Thoret, 1971, 1974). It can be obtained by fusion of the binary oxides or as a hydrate by adding ammonium or alkali metal molybdate to Th4þ solutions (Metzger and Zons, 1912; Banks and Diehl, 1947; Trunov and Kovba, 1963; Trunov et al., 1966; Thoret et al., 1968). Th(MoO4)2 is dimorphic. The orthorhombic low‐ temperature form shows the Th4þ ion in an eight‐fold coordination by eight monodentate MoO2‐ 4 groups (Thoret et al., 1970; Thoret, 1974). The molybdate tetrahedra are coordinated to four Th4þ ions, leading to a three‐dimensional

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network. In the high‐temperature trigonal modification, one set of thorium ions are coordinated by six oxygen atoms while the other set has tricapped trigonal‐prismatic coordination polyhedra (Cremers et al., 1983; Larson et al., 1989). With alkali metal molybdates, M2MoO4, Th(MoO4)2 forms a great variety of compounds (Barbieri, 1913; Thoret, 1971, 1974; Bushuev and Trunov, 1974). The compositions M2Th4(MoO4)9, M2Th2(MoO4)5, M2Th(MoO4)3, M4Th(MoO4)4, M6Th(MoO4)5, and M8Th(MoO4)6 have been reported, but only very few of them are properly characterized. In K2Th(MoO4)3 the Th4þ ions are coordinated by eight oxygen atoms that belong to one chelating and six monodentate MoO2 ions (Huyghe et al., 1991a). The [Th(MoO4)7] poly4 hedra are linked to chains along [001] that are held together by Kþ ions. K4Th(MoO4)4 consists of a three‐dimensional network with the formula 3 1 ½ThðMoO4 Þ8=2 , where the potassium ions are found in holes in the structure (Huyghe et al., 1991b). All of the MoO2 4 groups are monodentate, leading to a coordination number of eight for Th4þ. The potassium‐rich molybdate K8Th(MoO4)6 contains isolated [Th(MoO4)6]8− ions in which Th4þ attains a coordination number of eight due to the chelating nature of two of the six molybdate groups (Huyghe et al., 1993). The cadmium compound CdTh(MoO4)3 shows the Th4þ ions in tricapped trigonal‐prismatic coordination of nine monodentate MoO2 4 groups (Launay and Rimsky, 1980). The prisms are connected to columns along the c‐axis that are stacked in a hexagonal fashion. In this way channels are formed in which the Cd2þ ions reside in an octahedral coordination. Cu2Th4(MoO4)9 has a complicated three‐dimensional structure with nine‐fold coordinated thorium ions (Launay et al., 1998). (h)

Chromates

Upon addition of dichromate to a solution containing Th4þ, the thorium chromate Th(CrO4)2·3H2O precipitates at room temperature (Palmer, 1895; Haber, 1897; Britton, 1923). At higher temperatures, a monohydrate precipitates (Palmer, 1895). Both hydrates have been investigated by optical microscopy and seem to be hexagonal or rhombic (Vasilega et al., 1980). According to thermal investigations Th(CrO4)2·3H2O dehydrates by a three‐step mechanism (Vasilega et al., 1980). Above 280 C, the anhydrous chromate is obtained that remains stable up to 620 C where it decomposes to ThO2 and Cr2O3. Under acidic conditions, for example in concentrated chromic acid, Th(CrO4)2·CrO3·3H2O is found as the equilibrium solid in the system ThO2/CrO3/H2O (Palmer, 1895; Britton, 1923). None of these compounds is structurally characterized, but the basic chromate, Th(OH)2CrO4·H2O (Palmer, 1895; Britton, 1923), has been investigated by means of XRD (Lundgren and Sillen, 1949). Its crystal structure contains zigzag‐chains of hydroxo‐bridged Th4þ ions along [010]. Further linkage of the thorium ions is achieved through bonding to CrO2 4 ions.

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Miscellaneous oxometallates

A limited number of thorium compounds with oxo‐anions other than those discussed above have been mentioned in the literature. The arsenates of thorium are obviously related to the phosphates (Le Flem, 1967; Hubin, 1971; Chernorukov et al., 1974a,b), while the tungstates resemble the molybdates (de Maayer et al., 1972; Thoret, 1974). Thorium ortho‐germanate, ThGeO4, has been shown to be dimorphic (Bertaut and Durif, 1954; Perezy Jorba et al., 1961; Harris and Finch, 1972) and adopts either the zircon or the scheelite structure type (Ennaciri et al., 1986). This compound has been used as a host lattice for trivalent lanthanides (Gutowska et al., 1981). Besides the most important silicate minerals thorite, huttonite, and thorogummite already mentioned in Section 3.3, a number of complex silicate minerals is known, which are, however, often not characterized completely. Structural data are, for example, available for ekanite, Ca2ThSi8O20 (Szymanski et al., 1982), and Ca6Th4(SiO4)6O2, which has the apatite type of structure (Engel, 1978). Furthermore the structure of the mineral thornasite, Na12Th3(Si8O19)4·18H2O, has been reported recently (Li et al., 2000). One borate, Th(B2O5), has been struc4þ turally investigated. It contains B2 O4 5 ions and eight‐fold coordinated Th ions (Baskin et al., 1961; Cousson and Gasperin, 1991). Additional thorium compounds with transition metal oxo‐anions such as the perrhenates should be mentioned. Th(ReO4)4 · 4H2O was obtained from Th(OH)4 and HReO4 (Silvestre et al., 1971; Zaitseva et al., 1984). Its structure is not known but is has been shown to dehydrate in four steps yielding Th(ReO4)4, which finally decomposes to Th2O(ReO4)6 (Zaitseva et al., 1984). Th(ReO4)4 forms ternary compounds with alkali perrhenates and mixed anionic 2 species with WO2 4 and MoO4 (Silvestre, 1978). Other oxo‐metallates reported are the titanate ThTi2O6 (brannerite structure) (Perezy Jorba et al., 1961; Radzewitz, 1966; Ruh and Wadsley, 1966; Loye et al., 1968; Kahn‐Harari, 1971; Zunic et al., 1984; Mitchell and Chakhmouradian, 1999), the niobate ThNb4O12 (Keller, 1965; Trunov and Kovba, 1966; Alario‐ Franco et al., 1982), and the tantalates ThTa2O7, Th2Ta2O9 (Keller, 1965; Schmidt and Gruehn, 1989, 1990), Th2Ta6O19 (Busch et al., 1996), and Th4Ta18O53 (Busch and Gruehn, 1996) have been reported. Structurally, however, they are preferably described as double oxides rather than oxo‐metallates. Values for the enthalpies of formation of thorite, huttonite (Mazeina et al., 2005) and thorium brannerite (Helean et al., 2003) are given in Chapter 19. ( j)

Carboxylates and related organic salts

Carboxylate complexes of thorium have been frequently investigated with respect to the role they may play in solvent extraction processes. Carboxylates and related salts have also been employed in gravimetric analyses for thorium, either by direct weighing if the compound is stoichiometric, or after ignition to thorium dioxide. Thus, there are a large number of papers describing these

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compounds. Most of them have been mentioned in the Gmelin Handbook (Gmelin, 1988a), so only selected examples will be presented here. The most investigated groups among the carboxylates are formates and acetates. Formates and formato complexes can be obtained by the reaction of formic acid with ThCl4 or other salts of Th4þ. In acid solution, Th(OOCH)4, is formed, which has been shown to be polymorphic (Mentzen, 1969, 1971a,b; Greis et al., 1977) and may contain different amounts of crystal water (Claudel and Mentzen, 1966; Thakur et al., 1980). If the pH of the solution increases above 6, basic formates start to form. They may have different compositions like ThOH(OOCH)3, Th(OH)2(OOCH)2, and Th(OH)3(OOCH) (Gmelin, 1988a) but they have not been structurally characterized. Various metal ions have been used to crystallize formato complexes, such as MTh(OOCH)5 (M ¼ K, Rb, Cs, NH4) and MTh(OOCH)6 (M ¼ Sr, Ba). All these complexes have been characterized by thermal analysis and vibrational spectroscopy (Molodkin et al., 1968b; Gmelin, 1988a). The structural knowlegde of thorium acetates and acetato complexes is also quite limited, although quite a number of compounds have been described. The tetraacetate, Th(CH3COO)4, is said to be isotypic with the respective uranium acetate (Eliseev et al., 1967; Bressat et al., 1968; Gmelin, 1988a), and similar to the formates, various hydrates and basic salts are known. Derivatives of acetic acid such as CF3COOH, CCl3COOH, CHCl2COOH, CH2ClCOOH, C6H5CH2COOH, C6H5CH(OH)COOH, naphtyl acetic acid, and others, have been used to prepare the respective salts (Katzin and Gulyas, 1960; Gmelin, 1988a). Even bromo‐ and iodoacetates are known. Among the chloroacetates, one compound has been investigated crystallographically. It has the composition [Th6(CHCl2 COO)12(OH)12(H2O)2] and shows an octahedral [Th6] core surrounded by the ligands. With increasing complexity of the carboxylic acids, less is known structurally about their thorium compounds. The compounds prepared include glycolates, propionates, butyrates, and their derivatives. Furthermore, compounds with unsaturated mono carboxylic acids have been reported, for example crotonates and cinnamates. The largest group of thorium salts of dicarboxylic acids are the oxalates and oxalato complexes, for which some crystallographic data are available (Gmelin, 1988a). More complex dicarboxylic acids have been employed, and even the thorium salts of long‐chain acids like sebacic acid, HOOC(CH2)8COOH, are known. The latter has been used, along with m‐nitrobenzoic acid (Neish, 1904), picrolonic acid (Hecht and Ehrmann, 1935; Dupuis and Duval, 1949), or ‘ferron’ (7‐iodo-8‐hydroxyquinoline-5‐sulfonic acid), for analytical purposes (Dupuis and Duval, 1949). 3.7.8

Coordination compounds

Coordination compounds of thorium are of special interest because the knowledge of their behavior and their properties is fundamental for the understanding

Important compounds

115

of separation processes (for example, the thorium extraction [THOREX] process that involves tri(n‐butyl)phosphate complexes) (Peppard and Mason, 1963), see Chapter 24, the development of decontamination methods, and the treatment of radioactive waste. Thus, the number of compounds reported in literature is very large. The Gmelin Handbook provides a comprehensive overview of the compounds investigated until 1983 (literature closing date) (Gmelin, 1985b). A more recent review (Agarwal et al., 2000) covers thorium compounds with neutral oxygen donor ligands. These ligands can be divided with respect to the atom to which the oxygen donor is bonded: ligands containing a C–O group may, for example, be alcohols, phenols, ketones, esters, ethers, formamide, acetamide, those containing a N–O group are typically pyridine and quinoline N‐oxides or even nitrosyl chloride and P¼O, As¼O, and S¼O groups are known for the respective phosphine, arsine, and sulfoxides. The group of neutral oxygen donor ligands is probably the most investigated, but also a great number of complexes with neutral nitrogen donor ligands are known (Vigato et al., 1977). Besides NH3 (Matthews, 1898; von Bolton, 1908; Clark, 1924), the ligands are higher amines, hydrazine and its derivatives, and pyridine and its derivatives (Matthews, 1898;Adi and Murty, 1978; Al‐Daher and Bagnall, 1984). Coordination compounds with charged ligands besides the above‐mentioned carboxylates have been also frequently investigated. Among these ligands are the diketonates and related ligands, tropolone and its derivatives, and a great number of Schiff base ligands (Biradar and Kulkarni, 1972). One of the most important thorium coordination compounds is thorium tetrakis(acetylacetonate), Th(acac)4, which can be sublimed at temperatures below its melting point of 171 C (Urbain, 1896). This is also true for most of the substituted acetylacetonates, for example the trifluoromethylacetylacetonate, whose structure has been determined and that shows the thorium atoms in square antiprismatic coordination of oxygen atoms (Wessels et al., 1972). These compounds are generally efficiently extracted into water‐immiscible solvents, a property that has been used, for example, with thenoyltrifluoroacetone, to measure complexation of thorium with various anions (Calvin, 1944; Day and Stoughton, 1950). Another ligand that has been studied in more detail is 8‐hydroxyquinoline (‘oxine’) and its derivatives (Frazer and Rimmer, 1968; Abraham and Corsini, 1970; Corsini and Abraham, 1970; Singer et al., 1970; White and Ohnesorge, 1970). Also heteroleptic species involving oxine and another ligand, for example dimethylsulfoxide, are known (Singer et al., 1970; Andruchow and Karraker, 1973). As a thorium complex with eight‐fold thorium coordination with sulfur atoms, thorium(IV) tetrakis(N,N‐diethyldithiocarbamate) should be mentioned (Brown et al., 1970b). A path to related compounds is through intermediates such as Th(NEt2)4 (Bradley and Gitlitz, 1969; Watt and Gadd, 1973), which, when treated with CXY (X,Y ¼ O, S, Se etc.), gives carbamates, thiocarbamates, mixed compounds like Th[OSCN (CH3)2]4, and even Th(Se2CNEt2)4 (Bagnall and Yanir, 1974). It is very surprising that despite the large number of complexes that have been prepared, the number of structure determinations is very limited.

Thorium

116 3.7.9

Organothorium compounds

As Chapters 25 and 26 are devoted to the synthesis, the characterization and the properties of the organoactinide compounds, only selected examples shall be mentioned briefly here. Thorocene, Th(COT)2 (COT ¼ cyclo‐octatetraene), has been prepared by treating ThCl4 in tetrahydrofuran (THF) with K2(COT) at dry‐ice temperature (Streitwieser and Yoshida, 1969). The yellow crystals of Th(COT)2 sublime at 0.01 mmHg pressure and 160 C. Thorocene, isomorphous with U(COT)2 (uranocene) (Avdeef et al., 1972), is unstable in air, decomposes in water, and undergoes thermal decomposition without melting above 190 C. Gas‐phase photoelectron spectra have been used to elucidate the bonding in thoracene (Fragala et al., 1976; Clark and Green, 1977). This compound has also been prepared by treating ThF4 with Mg(COT) (Starks et al., 1974). In addition, a number of half‐sandwich Th(IV) complexes with COT have been reported (LeVanda et al., 1980; Zalkin et al., 1980). Numerous complexes with the cyclopentadienyl (Cp−) anion have been reported. Th(Cp)4 was first prepared by the reaction of ThCl4 with KCp (Fischer and Treiber, 1962). This compound sublimes between 250 and 290 C at 10−3 to 10−4 mmHg. Tris(cyclopentadienyl) halides and alkoxides of thorium have been synthesized (Ter Haar and Dubeck, 1964; Marks et al., 1976), and, in general, these air‐sensitive compounds sublime below 200 C and 10−3 to 10−4 mmHg pressure. Related tris(indenyl)thorium halides and alkoxides have been prepared (Laubereau et al., 1971; Goffart et al., 1975, 1977). The only bis (cyclopentadienyl)thorium dihalide reported is ThI2(Cp)2, prepared from ThI4 and Mg(Cp)2 (Reid and Wailes, 1966), whereas it is believed that the chloride analog would be unstable, similar to the uranium compound (Ernst et al., 1979). In contrast, the permethylated Cp derivative C5 ðCH3 Þ 5 (¼Cp*) has been used to prepare stable dichlorides, (Cp*)2ThCl2 (Manriquez et al., 1978; Blake et al., 1998). The CpTh trihalides have been described to exist as adducts with ethers, CpThX3 · 2L (L ¼ tetrahydrofurane or 1/2 dimethoxyethane [DME]) (Bagnall et al., 1978). Analogous indenyl (Goffart et al., 1980) and Cp* compounds have also been reported (Mintz et al., 1982). Tetrabenzylthorium, Th(CH2C6H5)4, is the best‐characterized thorium homoalkyl compound reported to date (Ko¨hler et al., 1974). The light‐yellow, air‐sensitive, crystalline compound decomposes slowly at room temperature. A second tetrahydrocarbyl thorium complex has been reported, Th(CH3)4(dmpe)2 (dmpe ¼ bis(dimethylphosphino)ethane), prepared by the reaction of ThCl4(dmpe)2 with CH3Li (Edwards et al., 1981). It is stable up to –20 C in the absence of air and moisture. These two thorium phosphine complexes, along with Th(OC6H5)4(dmpe)2 and Th(CH2C6H5)4(dmpe)2, were the first isolated and characterized species of their kind (Edwards et al., 1984). Tetraallylthorium, Th(C3H5)4, has been reported and decomposes slowly above 0 C (Wilke et al., 1966).

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117

The reaction of the Cp– (Marks and Wachter, 1976), indenyl– (Goffart et al., 1977), and Cp*–thorium chlorides (Fagan et al., 1981; Fendrick, 1984) with alkylating or arylating reagents has yielded the corresponding π‐ligand thorium hydrocarbyls. In a thermodynamic study on the series (Cp*)2ThR2, it was observed that the bond disruption enthalpies of the thorium–ligand σ‐bonds were about 250–335 kJ mol−1, significantly greater than similar transition metal bond enthalpies (Bruno et al., 1983). More recent investigations on organothorium chemistry were intended to introduce new ligands in that field and to synthesize low‐valent thorium compounds. For example, the bicyclic pentalene dianion C8 H2 6 has been used to prepare a new type of thorium sandwich complex. The crystal structure, as well as the photoelectron spectra, of [Th{C6H4(SiiPr3–1,5)2}2] was reported (Cloke and Hitchcock, 1997; Cloke et al., 1999). Another very interesting ligand, the dicarbollide anion C2 B9 H2‐ 11 , should be mentioned: it is found in the complexes [Li(THF)4]2[Th(Z5‐C2B9H11)2X2] (X ¼ Cl, Br, I) (Rabinovich et al., 1997). The number of potentially low‐valent organothorium complexes is still very limited. Two forms of Th(C5H5)3 have been reported. Purple Th(C5H5)3 was prepared by sodium naphtalide reduction of Th(C5H5)3Cl in THF. The latter was removed under vacuum (Kanellakopulos et al., 1974). According to X‐ray powder diffraction measurements, the compound is isotypic with the analogs of heavier 5f elements and has an effective magnetic moment of 0.331μB. The green form of Th(C5H5)3 was formed via photolysis of Th(C5H5)3[(CH(CH3)2] in benzene solution and has a magnetic moment of 0.404mB (Kalina et al., 1977). A recent example is [Th{COT(TBS)2}2][K(DME)2] – with COT(TBS)2 ¼ Z‐C8H6(tBuMe2Si)2–1,4 – that has been prepared by the reaction of a suspension of [Th{COT(TBS)2}2] in DME with elemental potassium (Parry et al., 1999). Furthermore, the first organometallic compounds of divalent thorium have been reported recently. They contain the complex Et8‐calix[4]tetrapyrrole ligand and are potentially divalent synthons (Korobkov et al., 2003).

3.8

SOLUTION CHEMISTRY

3.8.1

Redox properties

Thorium is known to have only one stable oxidation state in aqueous solution, the tetravalent state, Th4þ(aq) (Gmelin, 1988c). Th(III) has been recently claimed by Klapo¨tke and Schulz (1997) to be formed by reaction of ThCl4 with HN3 in slightly acidic solution and to be stable for at least 1 h. Reportedly, the reaction involved: Th4þ þ HN3 ! Th3þ þ 1:5N2 þ Hþ Yet, the reaction has been shown to be thermodynamically impossible by Ionova et al. (1998). First, the stabilization of d‐electrons by the crystal field effect is not

Thorium

118

sufficient to assign, as suggested by Bratsch and Lagowski (1986), a value of –3.0 V to the redox potential of the couple M4þ/M3þ. Besides, a value between –3.35 and –3.82 V, in the same range as the previously published one, –3.7 V (Nugent et al., 1973), is much more probable. Secondly, the reducing ability of HN3 has been overestimated and the authors concluded that the spectra published by Klapo¨tke and Schulz (1997), as a proof of the existence of Th3þ(aq) (broad absorption signal centered around 460 nm and intense peaks at 392, 190 and below 185 nm), correspond, in fact, to azido–chloro complexes of Th(IV). 3.8.2

Structure of the aqueous Th4þ ion

The LIII‐edge extended X‐ray fine structure (EXAFS) experiments on 0.03–0.05 M Th(IV) in 1.5 M HClO4 solutions have clearly defined the structure of the Th(IV) aqua ion (Moll et al., 1999). A least‐squares refinement of the data ˚ and a coordination number of leads to a Th–O distance of (2.45 ± 0.01) A (10.8 ± 0.5) which is larger than the older values estimated by Johansson et al. (1991) from low‐angle X‐ray scattering (LAXS) results (8.0 ± 0.5 water mole˚ ) or by Fratiello et al. (1970) from 1H NMR data at low cules at 2.485 A temperatures and higher concentrations (nine water molecules in the first hydration sphere). The results of Moll et al. are consistent with the structural parameters ˚) obtained in the same study for U4þ(aq) (CN ¼ 10 ± 1; R ¼ 2.42 ± 0.01 A 4þ and previously by Allen et al. (1997) for Np (aq) (CN ¼ 11.2 ± 0.4; R ¼ 2.40 ± ˚ ). A correlation between the hydration number (higher than 6) of highly 0.01 A charged metal ions and the bond distance shows also that a M–O distance of ˚ is in favor of a hydration number closer to 10 (Sandstro¨m et al., 2001). 2.45 A More precise systematics and correlation between the space around the cation and its charge have been proposed by David and Vokhmin (2003). They give consistent coordination numbers of Th4þ, U4þ, Np4þ, and Pu4þ: 11.0, 10.65, 10.2, and 10.0, respectively. The same authors have evaluated the corresponding ˚ for Th4þ, and a size of the coordinated water molecule ionic radii, 1.178 A ˚ of 1.335 A, by assuming a pure electrostatic bond. It would result in a ˚ . The observed difference with experilarger cation–oxygen distance of 2.51 A ˚ mental data (0.06 A) has been interpreted by a covalent effect and the effective charge of the Th4þ aquo ion has been evaluated to be 3.82 (David and Vokhmin, 2003). Finally, the same authors have determined the number of water molecules in a second hydration sphere as 13.4. 3.8.3

Thermodynamics of the Th4þ(aq) ion

The data on the standard enthalpy of formation, entropy, and corresponding Gibbs energy, adopted in this review and shown in Table 3.12, are those given in the compilation of Martinot and Fuger (1985), except for a small difference in the standard Gibbs energy of formation, due to the use of a more recent value for the entropy of Th(cr) (see Chapter 19).

Solution chemistry

119

Table 3.12 Main thermodynamic properties of the thorium aqueous ion at 25 C (see text for references). E (Th4+/Th) – (1.828 ± 0.015) V/NHE


f H  ðkJ mol1 Þ – (769.0 ± 2.5)


f G ðkJ mol1 Þ – (705.5 ± 5.6)

S (J K−1 mol−1) – (422.6 ± 16.7)

Thermodynamic models have been proposed recently by David and Vokhmin (2001) to evaluate the Gibbs hydration energy and the entropy of  the aquo ions. Corresponding values are
hyd G (Th4þ) ¼ –6100 kJ mol−1 and 4þ −1 −1  S (Th ,aq) ¼ –438 J mol K (David and Vokhmin, 2003). The entropy value is consistent with the experimental value, –(422.6 ± 16.7) J K−1 mol−1 (Martinot and Fuger, 1985). The standard state partial molar heat capacities and volumes of Th4þ(aq) have been recently determined from 10 to 55 C under conditions minimizing complications due to hydrolysis and ion‐pairing equilibria or ion–ligand complexation (measurements on aqueous solutions containing Th(ClO4)4 in dilute HClO4 (Hovey, 1997)). The values obtained at 25 C, Cp (Th4þ,aq) ¼ –(224 ± 3) J K−1mol−1 and V (Th4þ,aq) ¼ –(60.6 ± 0.5) cm3 mol−1, appear as more negative than those of any monoatomic aqueous ion. These results are also quite different from the previous estimations: Cp (Th4þ,aq) ¼ –(1 ± 11) J K−1 mol−1 (Morss and McCue, 1976) recalculated as – (60 ± 11) J K—1 mol−1 using a newer —1 Cp (NO mol−1 (Hovey, 1997) and V  (Th4þ,aq) ¼ 3 ,aq) value, –72 J K 3 −1 –53.5 and –54.6 cm mol from the values given in the International Critical Tables (1928) for the standard state partial molar volumes of ThCl4(aq) and Th(NO3)4(aq), respectively.

3.8.4

Hydrolysis behavior

Being the largest actinide tetravalent ion, Th4þ(aq) is also the least hydrolyzable of them (Onosov, 1971). Because of its size, it is less hydrolyzable than many other multi‐charged ions such as iron(III); tetravalent thorium may therefore be studied over a larger range of concentrations, at pH values up to 4. However, its tendency to undergo polynucleation reactions and colloid formation, as well as the low solubility of its hydroxide or hydrous oxide, limit the possibilities of investigation. For these reasons, the oxide/hydroxide solubility products and hydrolysis constants published in the literature show great discrepancies. Very recently, Neck and Kim (2001) have proposed a critical review and a comprehensive set of thermodynamic constants at zero ionic strength and 25 C. In the first part of their work, they compared the frequently accepted constants of Baes et al. (1965), Baes and Mesmer (1976), Brown et al. (1983), Grenthe and Lagerman (1991), and Ekberg and Albisson (2000). All these data, which are

120

Thorium

reported in Table 3.13, are based on potentiometric titrations at 15, 25, or 35 C with relatively low thorium concentrations (2  10−4 to 10−5 M). Ekberg and Albinsson have performed, in addition, solvent extraction experiments with a total concentration of Th(IV) in the range 10−5 to 10−7 M. It should be outlined that, under the conditions usually applied in potentiometric and solvent extraction studies ([Th]tot ¼ 2  10−4 to 2  10−2 M; pH ¼ 2.5–4; Kraus and Holmberg, 1954; Hietanen and Sillen, 1964; Baes et al., 1965; Nakashima and Zimmer, 1984), polynuclear species are of major importance and laser‐ induced breakdown detection (LIBD) has shown that a considerable amount of colloids were present at log[Hþ] ≤ –(1.90 ± 0.02) for log[Th]tot ¼ –(2.04 ± 0.02) and at log [Hþ] ≤ –(2.40 ± 0.03) for log[Th]tot ¼ –(4.05 ± 0.02) (Bundschuh et al., 2000). We can also cite the work of Moulin et al. (2001) who recently applied electrospray ionization–mass spectrometry to determine the hydrolysis of Th(IV) in dilute solution, but the equilibrium constants so‐determined    log K11 ¼ ð2:0 0:2Þ; log K12 ¼ ð4:5 0:5Þ; and log K13 ¼ ð7:5 1:0Þ are so large, compared to those obtained from the above‐cited well‐established methods, that it is difficult to consider them as reliable. As we can see from Table 3.13, the first mononuclear hydrolysis constants found by Brown et al. (1983) and Ekberg and Albinsson (2000) are about one order of magnitude higher than the constants derived by Baes and Mesmer (1976) and Grenthe and Lagerman (1991). Moreover, the hydrolysis constants þ reported for ThðOHÞ2þ 2 ; ThðOHÞ3 , and Th(OH)4(aq) differ between authors by several orders of magnitude. In order to select the best available data, Neck and Kim (2000) estimated the ‘unknown’ formation constants of ThðOHÞð4nÞþ by n two methods.The first one, method A, is based on the empirical intercorrelation between hydrolysis constants of actinide ions at different oxidation states. The second method, B, developed by the authors consists of applying a semiempirical approach, in which the decrease of the stepwise complexation constants for a given metal–ligand system is related to the increasing electrostatic repulsion between the ligands. From their results collected in Table 3.13, Neck and Kim  concluded that the higher log 11 values, in the range 11.7–11.9, and the lower   log 13 and log 14 values (Ekberg and Albinsson, 2000) should be preferred.  Consequently, their selected values are log 1n ¼ (11.8 ± 0.2), (22.0 ± 0.6), (31.0 ± 1.0), and (39.0 ± 0.5) for n ¼ 1, 2, 3, and 4, respectively (Neck and Kim, 2000). These data have been used to plot the speciation diagrams given in Fig. 3.18. Following a similar approach, Moriyama et al. (1999) analyzed the mononuclear hydrolysis constants of actinide ions by using a simple hard sphere model. Systematic trends were thus obtained, from which the values given in Table 3.13  have been deduced ðlog 1n ¼ 12.56, 23.84, 32.76, and 40.40 for n ¼ 1, 2, 3, and 4, respectively). These values are intermediate between the two series calculated by Neck and Kim (2000) and are in rather good agreement with the averages of  literature data (log 1n ¼ 11.27, 22.43, 33.41, and 40.94 for n ¼ 1, 2, 3, and 4, respectively) given by Moriyama et al. (1999).

(–4.13 ± 0.06) 12.42 ± 0.02c 12.58 ± 0.02c 10.9 ± 0.3 (–4.35 ± 0.09) 11.9 ± 0.2 (–3.3 ± 0.1) 12.56 13.4 11.9 11.8 ± 0.2

0.5 M KNO3 3 M NaClO4 0.1 M NaClO4 0.5 M NaClO4 3 M NaClO4 1 M NaClO4

solvent extraction potentiometry ThO2 solubility Th(OH)4 solubility potentiometry potentiometry and solvent extraction hard sphere model estimation A estimation B selection

b

Values based on the data of Kraus and Holmberg (1954). Values based on the data of Nabivanets and Kudritskaya (1964). c Not extrapolated to zero ionic strength. d Interpolated values (15–35 C).

a

Grenthe and Lagerman (1991) Ekberg and Albinsson (2000) Moriyama et al. (1999) Neck and Kim (2001)

Nakashima and Zimmer (1984) Bruno et al. (1987) Moon (1989)

11.7 ± 0.1 (–2.98 ± 0.07) 11.8 ± 0.2 (–3.28)

0.1 M KNO3

potentiometry

11.0 ± 0.2 (–4.12 ± 0.03)a

1 M NaClO4

(–2.65/ 0.1 M). Similarly, ThðClÞ2þ 2 is expected to be found only at pH < 4 and for [Cl−]tot > 0.5 M (Colin‐Blumenfeld, 1987). On the contrary, strong complexes of Th(IV) are formed with F− and SO2 4 and particularly with carbonate and phosphate ligands which are known to appreciably affect the speciation of Th(IV) in natural waters. A very strong complexation of Th(IV) by the HPO2 species is indicated by the stability 4 constants published by Moskvin et al. (1967) (see Table 3.16). These data are found in many databases used for geochemical modeling, but they were derived from solubility of an ill‐defined solid thorium phosphate in acidic phosphate media (hydrogen concentration of 0.35 M). They cannot explain the ThO2 ¨ sthols (1995). Moreover, extraction experiments solubility results obtained by O by acetylacetone in the two‐phase system 1 M Na(H)ClO4/toluene carried out by Engkvist and Albinsson (1994) at pH 8 and 9 (HPO2 4 being thus the dominant species) give cumulative stability constants of Th4þ/HPO2 4 much lower than the values published earlier; these new b values suffer, however, from large uncertainties. 4þ The stability constants known for Th4þ/H2 PO 4 and Th /H3PO4, and reported in Table 3.16, are those collected by Langmuir and Herman (1980). They have not been checked by subsequent studies, but their role is of minimal importance in the speciation of thorium in neutral and basic media. No data have been published on the complexation of Th4þ by the PO3 4 ions, except the ¨ sthols (1995): following equilibrium proposed by O 3 þ Th4þ þ 4H2 O þ PO3 4 $ ThðOHÞ4 PO4 þ 4H

log K ¼ ð14:90 0:36Þð0:35

MÞ

Finally, mention can be made of the study of Fourest et al. (1994). The solubility curves obtained by equilibrating solid thorium phosphate‐diphosphate and highly concentrated phosphate solutions have led to the determination of ThO(HPO4)3(H2PO4)5− and ThOðHPO4 Þ3 ðH2 PO4 Þ6 as the presumed 2 complex forms of Th(IV) at pH 6−7 and for 0.3 < [PO4]tot < 0.8 and 0.8 < [PO4]tot < 1.5 M, respectively.

Thorium

130

Table 3.16 Cumulative formation constants of the Th(IV) complexes formed with the main inorganic ligands at 25 C. Complex 3þ

ThF ThF22þ ThF3þ ThF4 ThCl3þ ThCl22þ ThCl3þ ThCl4 ThSO42þ Th(SO4)2 ThðSO4 Þ2 3 Th(SO4)4− ThNO3þ 3 ThðNO3 Þ2þ 2 ThðOHÞ4 PO3 4 Th(HPO4)2þ Th(HPO4)2 ThðHPO4 Þ2 3 ThH2 PO3þ 4 ThðH2 PO4 Þ2þ 2 ThH3 PO4þ 4 ThðOHÞ3 CO 3 ThðCO3 Þ6 5

a b

log b1xn

I (M)

References

8.03 14.25 18.93 22.31 1.09 0.80 1.65 1.26 5.45 9.73 10.50 8.48 0.94 1.97 –14.9 ± 0.36 10.8 (8.7 – 9.7) 22.8 (15 – 17.3) 31.3 (21–23) 4.52 8.88 1.9 41.5 21.6a 32.3 27.1b

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.35 0.35 1 0.35 1 0.35 1 0 0 2 0 0.05 0 0

Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) ¨ sthols (1995) O Langmuir and Herman (1980) Engkvist and Albinsson (1994) Langmuir and Herman (1980) Engkvist and Albinsson (1994) Langmuir and Herman (1980) Engkvist and Albinsson (1994) Langmuir and Herman (1980) Langmuir and Herman (1980) Langmuir and Herman (1980) ¨ sthols et al. (1994) O Joao et al. (1995) ¨ sthols et al. (1994) O Felmy et al. (1997)

¨ sthols et al. (1994) (see text) to be 33.2 in 1 M carbonate media. Recalculated by O  Derived by using the Ksp value of Ryan and Rai (1987) given in Table 3.15.

Despite the studies mentioned above, the thermodynamic database for tetravalent actinides remains rather poor for the complexation with inorganic anions, such as carbonate, phosphate, sulfate, fluoride, and chloride, which are dominant in natural aquatic systems. Consequently, a new semiempirical approach (based on an energy term describing the interligand electrostatic repulsion) has been developed by Neck and Kim (2000) with a first application for the mononuclear complexes with a high number of carbonate ligands. For such a ligand, this model predicts a slight decrease from log4 to log5 and a strong decrease from log5 to log6 . Hence the pentacarbonate complex is expected to be the limiting Th(IV)–carbonate complex at high carbonate concentration. Moreover, the existence of ThðCO3 Þ6 5 has been confirmed by several experiments using various methods: cryoscopy, conductometry, and ionic

Solution chemistry

131

exchange (Dervin and Faucherre, 1973a), solvent extraction followed by neutron activation (Joao et al., 1987, 1995), solubility of amorphous or microcrys¨ sthols et al., 1994) and X‐ray talline ThO2 (Rai et al., 1995; Felmy et al., 1997; O absorption (Felmy et al., 1997). The pentacarbonate complex structure is also well established in solid phase investigations (Voliotis and Rimsky, 1975). The stability constant values published in the frame of these works for the corresponding reaction: 6 Th4þ þ 5CO2 3 $ ThðCO3 Þ5

are collected in Table 3.16. The value obtained by Joao et al. (1987) recalculated by taking into account the complex really formed between Th(IV) and ethylene¨ sthols diaminetetraacetic acid (EDTA) at high pH (Th(OH)Y and not ThY) (O et al., 1994) is in general agreement with the value estimated by these authors. The estimation of Faucherre and Dervin (1962) from measurements of freezing point depressions is open to criticism, because only the dominant reaction is postulated and Th(IV) hydrolysis is neglected in the data treatment. The remain¨ sthols et al., 1994; Rai et al., 1995; Felmy et al., 1997) depend on ing values (O the hydrolysis constants applied for their evaluation. X‐ray absorption spectroscopy (XAS) data (Felmy et al., 1997) have clearly shown a change in speciation at low bicarbonate concentrations (0.01 M solution), but the total thorium concentration was too low to allow a definitive identification of the species. Solubility data of amorphous or microcrystalline ThO2 have been most satisfactorily explained by the introduction of a mixed ¨ sthols et al., 1994; Felmy et al., 1997) with logK  ¼ 41.5 ThðOHÞ3 CO3 (O 131 (see Table 3.16). (b)

Organic ligands

3 The organic species, such as oxalate (C2 O2 4 ), citrate (C6 H5 O7 ), and EDTA 4 (C10 H12 O8 N2 ), form strong complexes with thorium and ‘organic’ complexation can predominate in natural waters over ‘inorganic’ by orders of magnitude, even when the concentrations of organic ligands are low as compared with inorganic ones (Langmuir and Herman, 1980). The interaction of Th(IV) with citrate has been investigated both by potentiometry in 0.1 M chloride solution (Raymond et al., 1987) and solvent extraction (thenoyltrifluoro‐acetone [TTA] or dibenzoylmethane [DBM] in toluene) in perchlorate (0.1–14 M NaClO4; pH: 1.8–4.0) and chloride (0.1–5.0 M NaCl; pH: 3) solutions (Choppin et al., 1996). The former study covers a wider pH range (pH: 1–6) and a larger set of stability constants has been derived from the results than in the latter one. However, attention should be paid to the choice of hydrolysis constants used to fit the results. Moreover, the contribution of mixed hydroxy species, not yet identified, can be expected to be more important in basic media. Nevertheless, a relatively good agreement is observed for the two Th(Cit)þ formation constants (see Table 3.17).

Thorium

132

Table 3.17 Cumulative formation constants of the Th(IV) complexes with some organic ligands at 25 C. Complex

o log 1n

References

Th(Cit)+

16.17 14.13 13.7 ± 0.1 24.94 24.29 16.6 ± 0.1 31.9 ± 0.1 14.67 28.0 33.31 10.6 9.30 9.8 20.2 18.54 17.5 26.4 25.73 29.6 11.0 18.13 25.30 17.02

Nebel and Urban (1966) Raymond et al. (1987) Choppin et al. (1996) Nebel and Urban (1966) Raymond et al. (1987) Choppin et al. (1996) Choppin et al. (1996) Raymond et al. (1987) Raymond et al. (1987) Raymond et al. (1987) Moskvin and Essen (1967) Langmuir and Herman (1980) Erten et al. (1994) Moskvin and Essen (1967) Langmuir and Herman (1980) Erten et al. (1994) Moskvin and Essen (1967) Langmuir and Herman (1980) Moskvin and Essen (1967) Erten et al. (1994) Erten et al. (1994) Langmuir and Herman (1980) Langmuir and Herman (1980)

ThðCitÞ2 2 ThHðCitÞ 2 ThH2(Cit)2 ThðCitÞ2 ðOHÞ4 2 ThðCitÞ5 3 4 ThHðCitÞ3 ThC2 O2þ 4 Th(C2O4)2 ThðC2 O4 Þ2 3 ThðC2 O4 Þ4 4 Th(HC2O4)3+ ThðHC2 O4 Þ2þ 2 ThEDTA ThHEDTAþ

The Th(IV)/oxalate constants determined by using solvent extraction techniques (TTA and bis(2‐ethylhexyl)phosphoric acid [HDEHP] in toluene; pH: 1.3– 4.0; I ¼ 1, 3, 5, 7, and 9 M) (Erten et al., 1994) appear somewhat different from the values previously obtained from solubility measurements, but the approach of Moskvin and Essen (1967) has already been subjected to some criticism in the ¨ sthols, 1995). case of the phosphate ligands (O Other anions of organic acids, such as formate, acetate, chloroacetate, tartrate, malate, salicylate, sulfosalicylate, and so on, form complexes with Th(IV). They are too numerous to be listed in Table 3.16, but the corresponding stability constants can be found in various compilations: Sillen and Martell (1964, 1971), Perrin (1982), or the most recent database issued by the National Institute of Standards and Technology (NIST, 2002). Humic and fulvic acids have been identified as efficient complexing agents for ions such as Th4þ. Their influence on thorium mobilization in natural waters have been discussed in several publications (Choppin and Allard, 1985; Cacheris and Choppin, 1987; Miekeley and Ku¨chler, 1987). The Th(IV)–humate complex has been recently analyzed by X‐ray photoelectron spectroscopy (XPS)

Solution chemistry

133

(Schild and Marquardt, 2000). The XPS study corroborates EXAFS results (Denecke et al., 1999) according to which Th(IV) is predominantly bound to carboxylic groups of humic acids. 3.8.7

Analytical chemistry

As Chapter 30 is devoted to trace analysis of actinides in geological, environmental, and biological matrices, only summarized considerations will be given here, centered on the determination of thorium in natural waters. Extensive information on the techniques used in analytical chemistry of thorium, including the ‘classical’ gravimetric, titrimetric, and photometric methods, is also given in the Gmelin Handbook (1990b). Because of its low solubility and its ability to be sorbed as hydroxo complexes, the concentration of thorium in natural waters is, in general, below 0.1 μg L−1 and its quantitative determination is difficult. The most important analytical methods for the determination of Th(IV) in the range of low concentrations have been compiled and discussed by Hill and Lieser (1992). In most cases, a preconcentration step – coprecipitation, solvent extraction, and/or ion exchange separation – is performed prior to the measurement. Inductively coupled plasma mass spectrometry (ICP‐MS) is the most sensitive method with usual limits of detection around 0.01 μg kg−1 (Gray, 1985) and a reported limit value as low as 0.2 ng kg−1 (Chiappini et al., 1996), but this method needs costly pieces of equipment. Two other methods exhibit low detection limits (0.1 μg kg−1) and are well suited for routine analysis (Hill and Lieser, 1992):
Spectrophotometry, with the procedure described by Keil (1981) coupling

preliminary extraction and Th(IV) complexation with arsenazo;
Voltammetry, with the procedure reported by Wang and Zadeii (1986)

using a chelating reagent (with a concentration to be optimized). However, in practical applications, drawbacks are encountered with both methods due to the presence of uranium and aluminium, respectively. To avoid these drawbacks, a selective preconcentration of Th(IV) is thus necessary (Hill and Lieser, 1992). Gamma‐ and alpha‐spectrometries, with sensitivity around 1 μg kg−1 (Singh et al., 1979; Kovalchuk et al., 1982; Jiang and Kuroda, 1987), are essentially used for isotopic determinations. However, these standard radiochemical techniques require preconcentration and long counting times. 228Th can be determined from two successive gamma‐measurements of the 224Ra daughters, but a delay of 20 days is necessary to obtain reliable results for 228Th (Surbeck, 1995). The chemical separation techniques for the classical alpha‐spectrometry have been reviewed by De Regge and Boden (1984). These techniques often need optimization because around 50% of the initial activity can be lost at the chemical separation stage (Vera Tome´ et al., 1994). Liquid scintillation

134

Thorium

spectrometers, which allow discrimination between alpha and beta decays, and are commercially available, offer, in combination with selective extractive scintillators, a more advantageous solution to the problem of the isotopic determination of 232Th, 230Th, and 228Th, in spite of a low‐energy resolution compared to alpha‐spectrometry (Dacheux and Aupiais, 1997). With the PERALS (name registered to Ordela, Inc.) system, a limit of detection as low as 0.2 mg kg−1 can be reached for 232Th [value obtained for 250 mL and 3 days of counting (Dacheux and Aupiais, 1997)]. Moreover, PERALS spectrometry can be associated to six short liquid–liquid extraction steps to isolate Th from other actinides (U, Pu, Am, and Cm) prior to its detection at very low levels (the use of spikes during the chemical procedure is necessary for complex matrices).

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CHAPTER FOUR

PROTACTINIUM Boris F. Myasoedov, H. W. Kirby, and Ivan G. Tananaev 4.7

Simple and complex compounds 194 4.8 Solution chemistry 209 4.9 Analytical chemistry 223 List of abbreviations 231 References 232

4.1 4.2 4.3 4.4

Introduction 161 Nuclear properties 164 Occurrence in nature 170 Preparation and purification 172 4.5 Atomic properties 190 4.6 The metallic state 191

4.1

INTRODUCTION

Protactinium, element 91, is one of the most rare of the naturally occurring elements and may well be the most difficult of all to extract from natural sources. Protactinium is, formally, the third element of the actinide series and the first having a 5f electron. The superconducting properties of protactinium metal provide clear evidence that Pa is a true actinide element (Smith et al., 1979). Its chemical behavior in aqueous solution, however, would seem to place it in group VB of the Mendeleev’s table, below Ta and Nb. The predominant oxidation state is 5þ. Pa(V) forms no simple cations in aqueous solution and, like Ta, it exhibits an extraordinarily high tendency to undergo hydrolysis, to form polymers, and to be adsorbed on almost any available surface. These tendencies undoubtedly account for the many reports of erratic and irreproducible behavior of protactinium as well as for its frustrating habit of disappearing in the hands of inexperienced or unwary investigators. A useful review of the chemical properties of Pa important in an analytical context has been made by Pal’shin et al. (1970) and Myasoedov et al. (1978). The most important natural isotope is 231Pa, but the industrial importance of Pa stems chiefly from the role of its artificial isotope, 233Pa, as an intermediate in the production of fissile 233U in thorium breeder reactors. It was, in fact, the need for a relatively stable isotope that could be used for macroscopic chemical studies, which was responsible for the revival of interest in the recovery of 23IPa from natural sources (Katzin, 1952). The result has been a rapid growth in our 161

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understanding of Pa chemistry, as summarized in numerous critical review articles (Gmelin, 1942, 1977; Elson, 1954; Katz and Seaborg, 1957; Haı¨ssinsky and Bouissie`res, 1958; Kirby, 1959; Salutsky, 1962; Brown and Maddock, 1963; Sedlet, 1964; Guillaumont and deMiranda, 1966; Keller, 1966a; Brown and Maddock, 1967; Guillaumont et al., 1968; Brown, 1969; Muxart et al., 1969; Muxart and Guillaumont, 1974; Morgan and Beetham, 1990), books (Cotton et al., 1999) and presentations (Weigel 1978; Jung et al., 1993; Greenwood and Earnshaw 1997; Sime, 1997). 4.1.1

Discovery of protactinium

During the preparation of the periodic table Mendeleev (1872) placed in the vacant space in group V between Th(IV) and U(VI) an unknown hypothetical element No. 91 named ‘eka‐tantalum’ with atomic mass of about 235, and chemical properties similar to Nb and Ta. Forty years later, Russell (1913), Fajans (1913a,b), and Soddy (1913a,b) independently proposed the radioactive displacement principles, i.e. two simple rules for reconciling the chemical and radioactive properties of the 33 radioelements known at that time: (1) if a radioelement emits an a particle, its position in the Mendeleev’s table is shifted two places to the left, or (2) if it emits a b–-particle, its position is shifted one place to the right. When the rules were applied systematically, there was one obvious discrepancy: the only known link between 238U and 234U, both in group VI, was element UX, a b–‐emitter whose chemistry was identical with that of thorium, in group IV. It was necessary to postulate the existence of an unknown b–‐emitter, in the space in the periodic table reserved by Mendeleev (1872). Before the end of 1913, Fajans and his student, Go¨hring, had shown that element UX was actually a mixture of two distinct radioelements: UX1 (234Th) and UX2 (234mPa), which gave off hard b–‐rays, had a half‐life of 1.15 min, and was chemically similar to Ta (Go¨hring, 1914a,b). They named the new element, ‘brevium’ (Bv) (breˇvis (Latin): short, brief ), because of its short half‐life (Go¨hring, 1914b). An analogous problem existed with respect to the origin of actinium (Go¨hring, 1914a). It was clear that Ac could not be a ‘primary’ radioelement, because its half‐life was only about 30 years (Curie, 1911). On the other hand, although there was a constant ratio of Ac to U in nature (Boltwood, 1906, 1908), Ac could not be part of the main U–Ra series, because the ratio was far too low. According to the displacement laws, Ac, in group III, could only be the product either of a b–‐emitter in group II or of an a‐emitter in group V. The first possibility was eliminated when Soddy (1913b) proved that Ra, the only group II element in the U–Ra series, was not the parent of Ac. The only remaining alternative was an a‐emitting isotope of UX2. In 1913, Soddy had reported the growth of Ac in two lots of UX, separated from 50 kg of uranium 4 years earlier (Soddy, 1913a). This suggested that Ac was being produced from UX ‘through an intermediate substance’. Five years

Introduction

163

later Soddy and Cranston (1918) [see also Sackett (1960)] had confirmed the growth beyond doubt and had separated the parent of Ac by sublimation from pitchblende in a current of air containing CCl4 at incipient red heat. This method was later applied by Malm and Fried (1950, 1959) to the separation of 233Pa from neutron‐irradiated 232Th. Almost simultaneously, Hahn and Meitner (1918) reported their independent discovery of the parent of Ac in the siliceous residue resulting from the treatment of pulverized pitchblende with hot concentrated HNO3. They proposed the name, protactinium. Preliminary estimates indicated that the half‐life of the new isotope was between 1200 and 180 000 years. Since the name, brevium, was obviously inappropriate for such a long‐lived radioelement, Fajans and Morris (1913) proposed that the name of element‐91 be changed to protactinium (linguistic purists at first insisted on calling it protoactinium, because ‘proto is better Greek’ (Grosse, 1975), but the name protactinium (Pa) was restored officially in 1949 (Anonymous, 1949)). There was still no direct evidence as to the origin of protactinium. In 1911, Antonoff (1911) had separated uranium Y  UY (231Th) from a purified U solution. UY was chemically similar to Th and Antonoff (1913) suggested that this might be the point at which the Ac series branched off from the U series. In 1917, Piccard (1917) suggested that, in addition to the two known isotopes of uranium, uranium I and II (UI and UII), there might also exist a third long‐lived isotope, actinouranium (AcU). AcU would decay by a‐emission to yield UY, which, in turn, would decay by b–‐emission to give an isotope of brevium. Piccard’s hypothesis was confirmed experimentally in 1935, when Dempster (1935) discovered AcU (235U) by mass spectrography. 4.1.2

Isolation of protactinium

The new element was isolated for the first time in 1927, when Grosse (1927, 1928) reported that he had prepared about 2 mg of essentially pure Pa2O5. By the end of 1934, Grosse with Agruss had developed a process for the large‐scale recovery and purification of Pa (Grosse, 1934a; Grosse and Agruss, 1934, 1935a). They had isolated more than 0.15 g of Pa2O5, reduced it to the metal, and determined its atomic weight to be 230.6 0.5 (Grosse, 1934b). In the same year, Graue and Kading (1934a,b) recovered 0.5 g of pure Pa (as K2PaF7) from 5.5 tons of pitchblende residues, an achievement that would not be equaled, let alone surpassed, for the next quarter of a century. The development of atomic energy led to the processing of most of the world’s known reserves of high‐grade uranium ores and to the accumulation of vast stockpiles of process wastes. Among these, at the Springfields refinery of the United Kingdom Atomic Energy Authority (UKAEA) was the ‘ethereal sludge’, a siliceous precipitate that had separated during the ether extraction of U from dilute HNO3 solution. This material, amounting to some 60 tons, contained about 4 ppm of Pa, or more than ten times its equilibrium concentration in

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164

unprocessed pitchblende. Since the sludge also contained about 12 tons of U, it was economically attractive to recover both elements, with most of the development and production cost being borne by the U recovery. The process that was finally adopted yielded 127 g of 99.9% pure 231Pa (Goble et al., 1958; Nairn et al., 1958; Jackson et al., 1960a,b; Collins et al., 1962; Hillary and Morgan, 1964) at a cost of about US$500 000 (CRC Handbook, 1997). The UKAEA has generously made its stockpile of Pa available to the rest of the world at nominal cost, thereby touching off intensive investigation of Pa chemistry at many laboratories. Thanks to this concentrated effort, the new era in Pa research that started in the mid-1950s has now reached maturity. Three international conferences were convened, devoted entirely to the chemical, physical, and nuclear properties of Pa (Oak Ridge National Laboratory, 1964; Bouissie`res and Muxart, 1966; Born, 1971). 4.2

NUCLEAR PROPERTIES

At present, there are 29 known isotopes of Pa (Table 4.1), but only three are of particular significance to chemists. They are the naturally occurring isotopes, 231 Pa and 234Pa, and reactor‐produced 233Pa. The characteristics of a‐decay of Pa isotopes with mass numbers (A) till 224 were presented by Andreev et al. (1996b). Hyde (1961, undated) and Hyde et al. (1964) had exhaustively reviewed the nuclear properties of all the isotopes with A ranging from 225 to 237. A new nuclide 239Pa produced recently by multi‐nucleon transfer reactions 238 U(p,2n)239Pa (Yuan et al., 1996). Protactinium was chemically separated from the uranium target and other produced elements. From the 239Pa b–decay a half‐life of (106 30) min was observed. For details concerning the more recently discovered isotopes, the reader should consult the original references (Meitner et al., 1938; Ghiorso et al., 1948; Gofman and Seaborg, 1949; Hyde et al., 1949; Meinke et al., 1949, 1951, 1952, 1956; Harvey and Parsons, 1950; Barendregt and Tom, 1951; Keys, 1951; Browne et al., 1954; Crane and Iddings, 1954; Zijp et al., 1954; Wright et al., 1957; Hill, 1958; Arbman et al., 1960; Takahashi and Morinaga, 1960; Albridge et al., 1961; Baranov et al., 1962; Bjørnholm and Nielsen, 1962, 1963; Subrahmanyam, 1963; Wolzak and Morinaga, 1963; McCoy, 1964; Bastin et al., 1966; Bjørnholm et al., 1968; Hahn et al., 1968; Trautmann et al., 1968; Briand et al., 1969; Borggreen et al., 1970; dePinke et al., 1970; Laurens et al., 1970; Varnell, 1970; Holden and Walker, 1972; Sung‐Ching‐ Yang et al., 1972; Lederer and Shirley, 1978; Folger et al., 1995; Yuan et al., 1995, 1996; Andreev et al., 1996a; Nishinaka et al., 1997). 4.2.1

Protactinium-231

Pa, an a‐emitter with fixed atomic weight 231.03588 0.0002 (Delaeter and Heumann, 1991), is a member of the naturally occurring 235U decay (4n þ 3) chain. It is the daughter of 231Th and the parent of 227Ac, from which it derives

231

Table 4.1 Nuclear properties of protactinium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

a a a a a a a a a a a a

223

6 ms

a

224 225

0.9 s 1.8 s

a a

226

1.8 min

227

38.3 min

a 74% EC 26% a 85% EC 15%

228

22 h

EC 98% a 2%

229

1.5 d

230

17.7 d

231

3.28  104 yr

EC 99.5% a 0.48% EC 90% b– 10% a 3.2  10–3% a

232

1.31 d

b–

233

27.0 d

b–

234

6.75 h

b–

234 m

1.175 min

235

24.2 min

b– 99.87% IT 0.13% b–

a 8.270 a 8.236 a 8.116 a 8.170 a 7.865 a 8.340 a 10.160 a 9.614 (65%) a 9.900 a 9.15 a 9.080 a 8.54 (30%) 8.18 (50%) a 8.20 (45%) 8.01 (55%) a 7.49 a 7.25 (70%) 7.20 (30%) a 6.86 (52%) 6.82 (46%) a 6.466 (51%) 6.416 (15%) g 0.065 a 6.105 (12%) 6.078 (21%) g 0.410 a 5.669 (19%) 5.579 (37%) a 5.345 b– 0.51 g 0.952 a 5.012 (25%) 4.951 (23%) g 0.300 b– 1.29 g 0.969 b– 0.568 g 0.312 b– 1.2 g 0.570 b– 2.29 g 1.001 b– 1.41

182

218 219 220 221 222

5.1 ms 5.3 ms 17 ms 14 ms 0.2 s 4.9 ms 1.6 ms 0.12 ms 53 ns 0.78 ms 5.9 ms 5.7 ms

236

9.1 min

b–

237

8.7 min

b–

238

2.3 min

b–

239

106 min

b–

212 213 214 215 216 217

b– 3.1 g 0.642 b– 2.3 g 0.854 b– 2.9 g 1.014

W(35Cl,5n) Er(51V,8n) 170 Er(51V,7n) 181 Ta(40Ar,6n) 197 Au(24Mg,5n) 181 Ta(40Ar,4n) 170

206

Pb(16O,4n) Pb(19F,4n) 204 Pb(19F,3n) 209 Bi(16O,4n) 209 Bi(16O,3n) 206 Pb(19F,3n) 208 Pb(19F,4n) 205 Tl(22Ne,4n) 208 Pb(19F,3n) 232 Th(p,8n) 209 Bi(22Ne,a2n) 232 Th(p,7n) 204

232

Th(p,6n)

232

Th(p,5n) Th(p,3n)

230 230

Th(d,3n) Th(d,2n) 230 Th(d,2n) 232 Th(p,3n) 229

nature 231

Pa(n,g) Th(d,2n) 233 Th daughter 237 Np daughter nature 232

nature 235

Th daughter U(n,p) 236 U(n,p) 238 U(d,a) 238 U(g,p) 238 U(n,pn) 238 U(n,p) 235

18

O þ 238U

Protactinium

166

its name (Fig. 4.1). Reported half‐lives have ranged from 32 000 years 10% (Grosse, 1932) to (34 300 300) years (Van Winkle et al., 1949); three recent determinations (Kirby, 1961; Brown et al., 1968a; Robert et al., 1969) yield a weighted average of (32 530 250) years (at the 95% confidence level). Therefore 231Pa is the only isotope easy to access in multi‐gram quantities. The thermal‐neutron cross section is (211 2) barn (Simpson et al., 1962; Gryntakis and Kim, 1974). The spontaneous fission half‐life is 1.1  1016 years (Segre`, 1952), which gives the correlation of 0.3 of a fission per 1 g Pa per min. The complex fine structure of the 231Pa alpha‐spectrum can be resolved with a passivated implanted planar silicon detector (Fig. 4.2). Baranov et al. (1962, 1968), using a double‐focusing magnetic spectrometer, found at least 19 a‐groups with energies ranging from 4.51 to 5.06 MeV and additional low‐ abundance groups have been detected by a–g coincidence measurements (Lange and Hagee, 1968). Predictably, the g‐ray spectrum, as recorded with a high‐resolution Ge detector, is even more complex (Fig. 4.3): 92 g‐rays have been reported, with energies up to 609 keV (dePinke et al., 1970; Leang, 1970). A detailed level scheme is given in the critical compilation by Artna‐Cohen (1971). The prominent g photopeak at 27.35 keV is easily detectable even with a NaI(Tl) crystal; it uniquely identifies 231Pa in the presence of other naturally occurring g‐emitters (Fig. 4.4).

Fig. 4.1

Uranium–actinium series (4n þ 3).

Nuclear properties

Fig. 4.2 Alpha‐spectrum of detector (Ahmad, 2004).

231

167

Pa measured with a passivated implanted planar silicon

231

Pa can be separated from reprocessed U ores, or alternatively, produced by either of the two nuclear reactions: 232Th(n,2n)231Th (Nishina et al., 1938) or 230 Th(n,g)231Th (Hyde, 1948). In principle, this would eliminate many of the problems attendant on the isolation of 231Pa. However, neutron irradiation of 232 Th yields large amounts of 233Pa and other undesirable contaminants, but relatively little 231Pa (Table 4.2) (Schuman and Tromp, 1959; Codding et al., 1964). The 230Th route is only superficially more attractive, since the richest sources of 330Th found thus far in U refinery waste streams and residues have always been associated with at least eight times as much 232Th (Figgins and Kirby, 1966). Protactinium was not formed in the amalgam and could be also separated from thorium (David and Bouissie`res, 1966). 4.2.2 233

Protactinium-233

Pa is the only artificial isotope of Pa thus far produced in weighable amounts; the first gram was isolated in 1964 by a group at the National Reactor Testing Station in Idaho (Codding et al., 1964). 233Pa derives its importance from the

Protactinium

168

Fig. 4.3 g‐Ray spectrum of (Ahmad, 2004).

23l

Pa measured with a 25% efficiency germanium detector

Fig. 4.4 g‐Ray spectrum of 231Pa observed with a Nal(Tl) crystal: curve A, freshly purified 231 Pa; curve B, raw material (0.3 ppm 231Pa).

Nuclear properties

169

Table 4.2 Calculated composition of 100 g of 232Th after thermal‐neutron irradiation (Codding et al., 1964) (thermal flux ¼ 5  1014 n cm–2s–1; resonance flux ¼ (thermal flux)/12; nvt ¼ 1.2  1021 n cm–2). Nuclide

Amount

231

98.6 g 1 mg 950 mg 320 mg 65 mg 5 mg 60 mg

Pa Th 233 Pa 233 U 235 U 235 U fission products 232

Fig. 4.5 g‐Ray spectrum of 233Pa observed with a Ge(Li) detector. Reproduced from Crouthamel et al. (1970) with permission from Pergamon Press.

fact that it is an intermediate in the production of fissile 233U. The reaction, discovered in 1938 by Meitner et al. (1938) (Sime, 1997) is: 232 233

Th ðn; gÞ 233 Th ðb ; 22 minÞ ! 233Paðb ; 27 daysÞ ! 233U

Pa has largely replaced 234Pa as a tracer because of its favorable half‐life (26.95 0.06) days (Wright et al., 1957), its relative ease of preparation (cf. Table 4.2), and its readily detectable gamma spectrum (Fig. 4.5). Using this isotope a large volume of important data on protactinium chemistry had been provided.

Protactinium

170

Fig. 4.6

Genetic relationships of the UXl–UX2–UZ complex.

4.2.3

Protactinium-234

234

The nuclide Pa occurs naturally in two isomeric forms: 234mPa, discovered by Fajans and Go¨hring (1913a,b), and 234Pa, discovered afterward by Hahn (1921). Their genetic relationships are indicated in Fig. 4.6. Both are b–‐emitters, decaying to 234U, but 234mPa is metastable and, in 0.13% of its disintegrations, it decays to its ground state by isomeric transition, yielding 234Pa (Bjørnholm and Nielsen, 1963). The extraordinarily complex decay scheme of 234Pa (Ellis, 1970; Ardisson and Ardisson, 1975) is difficult to study, because the intense sources needed for high‐resolution spectrometry are not readily available. However, 0.8 Ci of 234Th was extracted from several tons of 238U, making possible the definitive study by Bjørnholm et al. (1967, 1968). The gamma‐spectrum of 234 Pa (in equilibrium with 238U and 234Th) is shown in Fig. 4.7 (Crouthamel et al., 1970).

4.3

OCCURRENCE IN NATURE

Since the half‐life of 231Pa is short in geological terms, its natural occurrence is closely tied to that of 235U, its primordial ancestor. Uranium isotopes are widely distributed in the Earth’s crust (Kirby, 1974). The average crustal abundance of U is 2.7 ppm (Taylor, 1964), of which 0.711 wt% is 235U (Grundy and Hamer, 1961); therefore, the natural abundance of 231Pa (calculated from its half‐life and that of 235U) is 0.87  10–6 ppm – only slightly less than that of 226 Ra. Assuming that the crustal mass (to a depth of 36 km) is 2.5  1025 g (Heydemann, 1969), the global inventory of 231Pa is 2.2  107 metric tons. The pronounced hydrolytic tendency of Pa is the basis of a method for dating marine sediments less than 106 years old (Sackett, 1960; Roshalt et al., 1961, 1962; Sakanoue et al., 1967; Thomson and Walton, 1971, 1972; Kirby, 1974). In an undisturbed geological formation, thematic Pa:U ¼ 3.2  10–7, but this ratio

Occurrence in nature

Fig. 4.7 g‐Ray spectrum of UX1–UX2–UZ in equilibrium with Crouthamel et al. (1970) with permission from Pergamon Press.

171

238

U. Reproduced from

is altered when the deposit is leached with groundwater and the U is carried to sea. At the pH of seawater, both Pa and Th hydrolyze and deposit together on 231 the ocean floor, leaving the U in solution as UO2þ Pa and 230Th 2 . Because decay moved at different rates, their ratio at various depths can be used to determine the rate of sedimentation. 231 Pa/235U ages were also determined for 17 carnotites from two areas in Israel (Kaufman et al., 1995). For the determination of 231Pa in solids, a new method, more than ten times more precise than those determined by decay counting, based on thermal ionization mass spectroscopy (TIMS) of protactinium in carbonates was created. Carbonates between 10 and 250 000 years old can now be dated with this 231Pa method. Barbados corals that have identical 231Pa and 230Th ages indicate that the timing of sea level change over parts of the last glacial cycle is consistent with the predictions of the Astronomical Theory (Edwards et al., 1997). 233 Pa has not itself been detected in nature, but traces of both 237Np, its parent, and 225Ac, its descendant, have been identified in a U refinery waste stream (Peppard et al., 1952). It may, therefore, be inferred that 233Pa is being continually formed in nature by the reaction: 238

U ðn; 2nÞ 237 U ðb ; 6:75 daysÞ ! 237 Np ða; 2:14  106 yearsÞ ! 233 Pa:

The natural neutron output in pitchblende is about 0.05 ng1 s–1, attributable about equally to spontaneous fission of 238U and (a,n) reactions of light elements (McKay, 1971).

Protactinium

172 4.4

PREPARATION AND PURIFICATION

No large‐scale separation of 231Pa has ever been made from virgin ores because the element has little commercial value. Weighable amounts of Pa have always been obtained from U refinery residues. Indeed, the economic realities are such that it is rarely possible even to optimize the segregation of Pa in a single waste stream or residue. More typically, the Pa is fractionated at every stage in the beneficiation and extraction of U from its ores. Before the development of atomic energy, pitchblende ores were processed primarily for their Ra content. The pulverized ore, after being roasted with Na2CO3, was leached with aqueous solutions of H2SO4 or HNO3 (or both) and the acid‐insoluble material was digested with NaOH or Na2CO3 solutions. The residue was then leached with hydrochloric acid to recover the Ra (Curie, 1913). The final residue retained a greater or lesser fraction of the original Pa according to the relative proportions of the acids used in the digestion; a higher H2SO4 concentration and higher total acidity favored the dissolution of Pa (Reymond, 1931). This Ru¨ckru¨cksta¨nde, or ‘residue of residues’, was the raw material used by Hahn and Meitner (1918) for their discovery of 231Pa, by Grosse (1927, 1928) in the isolation of the first milligram amounts, and by Graue and Kading (1934a) in the recovery of 0.5 g of the element. The analysis of one such residue is given in Table 4.3. During and after World War II, an ether extraction process was used for the purification of U. The acid solution resulting from the ore digestion was treated with Na2CO3 to precipitate some of the less basic metals, while leaving the U in solution as a carbonate complex. Katzin et al. (1950) found that the carbonate precipitate contained 0.30–0.35 ppm of Pa and subsequent processing of this material yielded about 25 mg of pure Pa (Kraus and Van Winkle, 1952; Larson et al., 1952; Thompson et al., 1952). When the process was modified to eliminate the carbonate precipitation, the Pa passed through the ether extraction step into the aqueous raffinate, from which Elson et al. (1951) recovered 35 mg of pure material. A later modification produced a precipitate in the aqueous waste stream, which, according to Salutsky et al. (1956), carried down nearly all the Pa. This material was periodically filtered off and eventually yielded a total of about 2 g of Pa (Kirby, 1959; Hertz et al., 1974; Figgins et al., 1975). The aqueous raffinate from the ether extraction was treated with lime and the filtered precipitate was stored for future recovery of U and other commercially valuable metals. The accumulated material was later treated by a process of which the relevant steps were: digestion with sulfuric acid, followed by extraction with bis(2‐ethylhexyl)phosphoric acid (HDEHP), and finally back‐ extraction with sodium carbonate solution. The waste solutions and residues were discharged to a tailings pond, where, for all practical purposes, much of the Pa and 230Th were irretrievably lost. In 1972, the process was modified by

Preparation and purification Table 4.3 Analyses of some Riickriicksta¨nde (Grosse and Agruss, 1935a) Constituent

U Fe Si Ba Zr Mo F– NHþ 4 Ca V Ti Pb Al P Sr Nb, Ta Mg, Ni, Cr, Co, Mn, & Sn Pa

173

Pa raw materials.

Ethereal sludge (Nairn et al., 1958)

Amount (% ) Constituent

SiO2 60 Fe2O3 22 PbO 8 Al2O3 5 MnO 1 CaO 0.6 MgO 0.5 Ti 0.3 Zr 0.1 HF and others – Graphite 0.1 Pa2O5 3  10–3

231

Cotter concentrate (Ishida, 1975)

Amount (% ) Constituent

Amount (% )

28.3 7.7 6.4 3 2.7 2.7 1.8 1.7 1.5 0.9 0.44 0.4 0.27 0.15 0.09 10 M HF, the Kd of Pa was more than an order of magnitude lower than that of Nb and they applied these observations to the separation of Nb and various alkali‐ and alkaline‐earth metal ions from 1 g of Pa2O5. The impure Pa was loaded on Dowex-1‐Ax10 in 2.5 M HF and eluted with 17 M HF; the product was contaminated only by 227Th, a decay product of 231Pa. Jenkins et al. (1975) have reported the purification of approximately 35 g of Pa by this method, with high decontamination factors for Si, Mg, Fe, Al, Cu, and Nb. The separation of Zr, Ha, Nb, Ta, and Pa was performed on a macroporous anion‐exchange resin BIO‐RAD AG MP1W in HF media (Monroy‐Guzman et al., 1996) and a mixture of 0.01–4.0 M NH4SCN and 0.05–3.0 M HF media to determine its analytical potential for the quantitative separation of these elements. It was found that the SCN– concentration in mixtures NH4SCN–HF had a strong influence on the adsorption of these ions. The Kd of these elements could be explained in terms of the formation of species: [MFx](n–x)–, [M(SCN)y](n–y)–,, or [MOFx](n–x–y)– and [MO(SCN)y](n–(2þy)–, and mixed fluorothiocyanates of the type [M(F)x(SCN)y](n–x–y)– anionic complexes (Monroy‐Guzman et al., 1997). El‐Sweify et al. (1985) calculated the distribution of Pa, other actinides, and fission products between the chelating ion exchanger Chelex–100 and certain carboxylic acid solutions. (c)

Solvent extraction and extraction chromatography

Pal’shin et al. (1970) have exhaustively reviewed the analytical applications of solvent extraction and Guillaumont and deMiranda (1971) have reviewed the published data as they relate to the ionic species of Pa and the mechanism of its extraction. At tracer levels ( Nb > Db) is likely to be due to an increasing tendency of these elements to form a non‐extractable polynegative complex species in concentrated HBr in the sequence Pa < Nb < Db (Gober et al., 1992). Milligram amounts of Pa(V) were extracted from H2SO4, HCl or HNO3 acid solutions by isoamyl alcohol containing 1% PAA or 4% benzeneseleninic acid; good separation from many impurities was reported (Myasoedov et al., 1966a, 1968a). Tetraphenylarsonium chloride has also been studied as a possible extractant for protactinium from hydrochloric or oxalic acid solutions (Abdel Gawad et al., 1976; Souka et al., 1976b). Other extraction agents have also been explored. Thus, l‐phenyl-2‐methyl-3‐hydroxy‐4‐pyridone dissolved in chloroform (Tamhina et al., 1976, 1978; Herak et al., 1979) quantitatively extracted Pa from hydrochloric acid solution, and Pa can be separated from uranium and/ or thorium by appropriate adjustment of the acidity. The antibiotic, tetracycline, was used in radiochemical analytical separations of protactinium from other actinide elements (Saiki et al., 1981) and 5,7‐dichloro-8‐hydroxyquinoline

Preparation and purification

183

Fig. 4.10 Purification scheme for 555 mg of Pa. (According to Brown et al., 1966a.) Reproduced with permission from Pergamon Press.

was investigated for the separation of protactinium from niobium, tantalum, and zirconium by solvent extraction (Vaezi‐Nasr et al., 1979). Myasoedov and Pal’shin (1963) and Davidov et al. (1966c) proposed an effective method for isolation of Pa from uranium ores and products of their reprocessing by liquid–liquid extraction with the chelating complexing reagent 3,6‐bis‐[(2‐arsenophenyl)azo]-4,5‐dihydroxy-2,7‐naphthalene disulfo acid (Arsenazo‐III) in isoamyl alcohol. It was shown that an effective extraction of Pa from strong acid media, even in the presence of a great amount of Al, Fe(III), Mn(II), rare earth metals, and other elements, took place. The growth of U, Zr, Th, and particularly Nb concentrations in the solutions led to a diminution of Pa isolation. This method was used for analytical control of the separation of gram amounts of Pa(V) under plant conditions.

184

Protactinium

Thenoyltrifluoroacetone (TTA) had been used for separation and purification of Pa from several elements (Meinke and Seaborg, 1950; Meinke, 1952; Bouissie`res et al., 1953; Moore, 1955, 1956; Brown et al., 1959; Moore et al., 1959; Poskanzer and Foreman, 1961a,b; Myasoedov and Muxart, 1962a). TTA extraction has been applied to the extraction of Pa from 10 M HCI in which PaOCl3 6 appears to be a principal species (Duplessis and Guillaumont, 1979). Triphenylphosphine oxide (TPPO), triphenylarsine oxide (Maghrawy et al., 1989), and mixtures of TTA and either TBP, TOPO, or TPPO have been investigated (Kandil et al., 1980); a combination of TTA and TOPO has found use in the separation of protactinium and thorium by solvent extraction (Kandil and Ramadan, 1978). TBP (Peppard et al., 1957; Souka et al., 1975b; Svantesson et al., 1979), HDEHP (Shevchenko et al., 1958a; Brown and Maddock, 1963; Myasoedov and Molochnikova, 1968; Myasoedov et al., 1968b; Maghrawy et al., 1988), and di-2‐ethyl‐hexyl isobutylamide (D2EHIBA) (Pathak et al., 1999a,b) have high capacities for Pa(V), but are relatively unselective. The extraction by N‐benzoylphenylhydroxylamine (BPHA) from HCl, and H2SO4 solutions was used for the separation of Pa(V) from other elements by Pal’shin et al. (1963) and Myasoedov et al. (1964). It was found that protactinium complexes with BPHA were extracted by benzene or other solvents from aqueous solutions with a wide range of acid concentrations. D’yachkova and Spitsyn (1964) studied the protactinium, zirconium, and niobium behavior by extraction with BPHA from sulfuric acid solutions. The isolation of the above elements was carried out with 0.2–0.5% solution BPHA in chloroform. The largest difference in extraction ability for these elements was observed with H2SO4 concentrations in the aqueous phase greater than 7 N. Rudenko et al. (1965) and Lapitskii et al. (1966) carried out the separation of protactinium from uranium and thorium by extraction with 0.1 M BPHA solution in chloroform from 4 M HCl. The Pa(V) extraction by cupferron (CP) had been studied by Maddock and Miles (1949). It was found that Pa was easily extracted by CP in both oxygen‐ containing and inert solvents from inorganic acid media. Spitsyn and Golutvina (1960) used the extraction with CP for the separation of 233Pa from large amounts of manganese. Rudenko et al. (1965) and Lapitskii et al. (1965) reported that the neocupferron (NCP), an analog of CP, can be also used for the separation of protactinium from uranium, thorium, and other elements. Uranium and thorium are not extracted by NCP from 2 M HCl solutions, whereas protactinium isolation by a 0.01 M solution of this reagent in chloroform is about 90%. These authors used NCP for isolation of 233Pa from irradiated thorium. The extraction of Pa by 1‐phenyl-3‐methyl-4‐benzoylpyrazolone (PMBP) in benzene solution from H2SO4 media effectively isolated this element from large amounts of Fe(III), La, Nb(V), Th(IV), and U(VI) (Pal’shin et al., 1970). Hence, Pa extraction and isolation by 0.1 M solution of PMBP in benzene from 5 N H2SO4 is greater than 98%. For the complete separation of Pa from Zr by this method, a 12% solution of H2O2 had been used.

Preparation and purification

185

The quantitative extraction of protactinium salicylate with acetone at pH 4 from saturated calcium chloride solutions was reported by Nikolaev et al. (1959). Under these conditions zirconium, thorium, uranium, and plutonium are extracted with protactinium. The extraction with salicylate can be used for the separation of protactinium from rare earth and other di‐ and tervalent elements. The quantitative extraction of protactinium oxychinolate with chloroform from solutions with pH 3–9 was described (Keller, 1966a). Extraction by tertiary amines in early work was explored only at levels of 10–4 M or less, but this procedure shows promise because it permits the extraction of Pa(V) from HF‐containing solutions (Moore, 1960; Muxart and Arapaki‐Strapelias, 1963; Guillot, 1966; Muxart et al., 1966b; Pal’shin et al., 1971; Moore and Thern, 1974). The extraction behavior of protactinium in mixtures of uranium, thorium, and neptunium with trilaurylamine from sulfonic acid solutions (Souka et al., 1975c) indicates low distribution coefficients at high acid concentrations; the addition of hydrochloric acid appreciably enhances extraction. The extraction of protactinium (V) with trioctylamine (TOA) dissolved in xylene from thiocyanate solutions containing uranium and thorium have been successfully accomplished (Nekrasova et al., 1975a); tracer amounts of Pa can exist in monomeric form in thiocyanate media for several months, but at Pa(V) concentrations greater than 10–6 M, polymers form and the efficacy of TOA as an extractant is seriously impaired (Nekrasova et al., 1975b). Columns impregnated with TOA in a liquid chromatographic system were also used for the separation of 262,263 Db in HCl–HF media from Pa and Nb. The data obtained confirm the non‐tantalum‐like behavior of dubnium in 0.5 M HCl and 0.01 M HF media, and corroborate previously suggested structural differences between the halide complexes of dubnium, niobium, and protactinium, on the one hand, and those of tantalum on the other hand (Zimmerman et al., 1993). Dubnium was shown to be adsorbed on the column from 12 M HCl and 0.02 M HF solutions together with its lighter homologs Nb, Ta, and the pseudohomolog Pa. In elutions with 10 M HCl and 0.025 M HF, 4 M HCl and 0.02 M HF, and 0.5 M HCl and 0.01 M HF, the extraction sequence Ta > Nb > Db > Pa was observed (Paulus et al., 1998, 1999). The formation of polymers of Pa(V) in the extractions by quaternary ammonium base Aliquat 336 from strongly alkaline solutions can be minimized by the addition of a hydroxycarboxylic acid or aminopolycarboxylic acid (Myasoedov et al., 1980). While the extractability of Pa(V) can be enhanced, the separations are poor. For the systematic study of halide complexation of the group V elements, new batch extraction experiments for Nb, Ta, and Pa were performed with the Aliquat 336 in pure HF, HCl, and HBr solutions. Based on these results, new chromatographic column separations were designed to study separately the fluoride and chloride complexation of Db with Automated Rapid Chemistry Apparatus II (ARCA II). In the system Aliquat 336‐HF, after feeding the activity onto the column in 0.5 M HF, dubnium did not elute in 4 M HF (Pa fraction) but showed a higher distribution coefficient close to that of

Protactinium

186

Nb (and Ta). In the system Aliquat 336‐HCl, after feeding onto the column in 10 M HCl, dubnium showed a distribution coefficient in 6 M HCl close to that of Nb establishing an extraction sequence Pa > Nb greater than or equal to Db > Ta, which was theoretically predicted by considering the competition between hydrolysis and complex formation (Paulus et al., 1998, 1999). Separation of 231Pa from U and other impurities has been provided by an extraction‐ chromatographic method using quaternary ammonium‐Kel‐F materials (Zhang Xianlu et al., 1993). Extraction of protactinium(V) chloro complexes by tricaprylamine and its separation from Th(IV), U(VI), and rare earths has been described (El‐Yamani and Shabana, 1985). (d)

Large‐scale recovery of protactinium-231

Brown and Whittaker (1978) have described a new, ‘relatively simple’ method for the recovery and purification of protactinium-231. It has been applied with signal success to the recovery of Pa from various residues containing 1.73 g of protactinium in a state of high chemical and radiochemical purity. Efficient separation of 231Pa was readily effected by dissolving the 231Pa‐containing residues in 5 M hydrofluoric acid. Excess ammonia is added to precipitate the hydrous oxides, which after several washes with water are redissolved in 2 M nitric acid. This precipitate is considerably enriched in 231Pa. Washing the precipitated hydrous oxides with 0.5–4.0 M HNO3 and/or 0.5 M HNO3 and 0.3 M H2O2, in which protactinium(V) hydrous oxide, is essentially insoluble, removes much of the impurities carried in the initial hydrous oxide precipitation. Repetition of this cycle twice more yields Pa2O5 of high purity. The final traces of silicon are then removed by dissolving the hydrous oxides in 20 M HF and evaporating the solution to dryness. Recovery yields range from 92 to 96% from initial samples containing 30–75 wt% 231Pa. The purity of the product is generally greater than 99%; it is also radiochemically pure. 4.4.6

Preparation of pure 234Pa and 234mPa

Because of its short half‐life, 1.17 min 234mPa is frequently used for classroom demonstrations of radioactive decay and growth (Booth, 1951; Carsell and Lawrence, 1959; Overman and Clark, 1960). Pure 234mPa (and its ground‐state isomer, 6.7 h 234Pa) can be coprecipitated directly from a 6 M HCl solution of (NH4)2U2O7 with BPHA (Cristallini and Flegenheimer, 1963). The procedure is rapid and gives a high degree of decontamination from both U and Th. However, most authors prefer to make a preliminary separation of 24.1 day 234 Th, from which the 234mPa (and 234Pa) can be repeatedly ‘milked’. The classical procedure of Crookes (1900) is still one of the most widely used for this purpose (Harvey and Parsons, 1950; Barendregt and Tom, 1951;

Preparation and purification

187

Bouissie`res et al., 1953; Forrest et al., 1960; Bjørnholm and Nielsen, 1963): 10–200 g of UO2(NO3)2 · 6H2O are dissolved in diethyl ether. The aqueous phase formed by the water of crystallization retains the 234Th and some U. Repeated extraction with fresh ether removes the remaining U. Alternatively, the 234Th is purified and concentrated by coprecipitation with Fe(OH)3 in the presence of (NH4)2CO3 (Hahn, 1921; Harvey and Parsons, 1950), by cation exchange from HCl solution (Zijp et al., 1954; Suner et al., 1974), by anion exchange from HNO3 solution (Bunney et al., 1959), or by extraction with tertiary amines (Moore and Thern, 1974; Carswell and Lawrence, 1959). Once the 234Th has been purified, the 234mPa and 234Pa quickly regain equilibrium and can be isolated by any of the methods described above for the purification of 231Pa, except, of course, carrier‐free precipitation. Solvent extraction is the most suitable, because of its speed and selectivity, at tracer levels, Pa(V) is rapidly and quantitatively separated from Th(IV) by extraction from 6 M HCl solution with any number of organic solvents, notably DIPK, DIBK, DIPC, and DIBC (Moore, 1955; Myasoedov et al., 1966a). The 234Th remains in the aqueous phase. To prepare 234mPa free of 234Pa, the first two or three organic extracts are discarded and, after 10–15 min, the re‐grown 234mPa is extracted with fresh solvent (Bjørnholm and Nielson, 1963). Fajans and Go¨hring (1913b) first separated brevium by selective adsorption on lead plates and by coprecipitation with Ta2O5. The addition of 232Th keeps the mixture of 234Th and 234mPa more quantitatively in solution (Guy and Russell, 1923; Jacobi, 1945). Hahn (1921) coprecipitated the mixture of 234Th and 234mPa with LaF3, leaving 234Pa in the filtrate. Zijp et al. (1954) concentrated 234Pa by MnO2 precipitations (Maddock and Miles, 1949), alternating with extraction by TTA (Meinke, 1952). Bjørnholm et al. (1967) milked 0.5–1 mCi of 234Pa from 0.8 mCi of 234Th by extraction into hexone (methyl isobutyl ketone, MIK) from 6 M HC1 solution. It is noteworthy, however, that many of the same problems were encountered in the initial concentration of 234Th from 2 tons of U metal as in scaling up laboratory procedures for the concentration of macroscopic amounts of 231Pa from natural sources.

4.4.7

Preparation of pure 233Pa

Irradiation of 1 g 232Th (as metal, oxide, chloride, nitrate, or basic carbonate) for 1 day in a thermal‐neutron flux of 2  1014 n cm2 s–1 will produce approximately 5 Ci of 233Pa (Schuman and Tromp, 1959). Detailed procedures for the isolation of 233Pa from Th targets are given in several review articles (Hyde and Wolf, 1952; Hyde, 1954, 1956; Haı¨ssinsky and Bouissie`res, 1958; Kirby, 1959; Pal’shin et al., 1970). In general, the target is dissolved in concentrated HCl or HNO3 (usually containing 0.01–0.1 M HF as a catalyst) and the 233Pa is separated from Th and other impurities by one, or a combination, of the

Protactinium

188

anion‐exchange and solvent extraction methods described above. Alternatively, 3 g of Th metal irradiated in a reactor with an irradiation time of 1 day in a thermal flux of 3  1013 n cm–2 s–1 are dissolved in nitric acid. The 233Pa is adsorbed on an anion‐exchange column, eluted, then is extracted by TOPO (Kuppers and Erdtmann, 1992). A preliminary concentration by coprecipitation (Katzin and Stoughton, 1956; Fudge and Woodhead, 1957; Katzin, 1958) is often used, and was, in fact, the method adopted by Codding et al. (1964) to isolate 1 gram of 233Pa after solvent extraction with MIK or DIPK gave unaccountably poor yields. Leaching the MnO2 with a mixture of HNO3 and H2O2 removed the Mn without loss of 233Pa, which was subsequently dissolved in 6 M H2SO4 and re‐ precipitated with HNO3. On the other hand, Schulz (1972) reported good extraction of 233Pa by DIBC from 7.4 M HNO3 solutions containing 1.4 M Th (NO3)4 and 480 Ci L–1 of 233Pa. Macroscopic amounts of 233Pa have also been recovered from HNO3 solutions of irradiated ThO2 by adsorption on powdered unfired Vycor glass and silica gel (Moore and Rainey, 1964; Goode and Moore, 1967); at tracer levels, 233Pa has been separated from Th targets by adsorption on silica gel (Davydov et al., 1965; Spitsyn et al., 1969; Chang et al., 1974; Chang and Ting, 1975b), on quartz sand (Sakanoue and Abe, 1967), and on activated charcoal saturated with PAA (Pal’shin et al., 1966). Separations with cation and chelating resins (Kurodo and Ishida, 1965; Myasoedov et al., 1969), by paper chromatography and paper electrophoresis (Vernois, 1958, 1959; Myasoedov et al., 1969), and by reversed‐phase partition chromatography (Fidelis et al., 1963) have also been reported.

4.4.8

Toxic properties

231

Pa is dangerous to organisms, similar to other a‐emitters with comparatively short half‐lives. Once in organisms it accumulates in kidneys and bones. The maximum amount of protactinium considered not harmful after absorption by an organism is 0.03 mCi. It corresponds to 0.5 mg 231Pa. Protactinium231, contained in the air as an aerosol, is 2.5  108‐fold more toxic than hydrocyanic acid at the same concentrations (Bagnall, 1966a). Therefore all operations with weighable amounts of 231Pa are carried out in special isolated boxes.

4.4.9

Applications of protactinium

Pa was used for the preparation of a scintillator for detecting X‐rays, comprising complex oxides of Gd, Pa, Cs, rare earth metals and other elements. This scintillator, which can significantly increase relative light emission outputs without increasing background, is used in for detecting X‐rays, particularly in an X‐ray computed tomography apparatus (Hitachi Metals, 1999). The coating

Preparation and purification

189

material for a color cathode ray tube with bright green fluorescence was created by doping wih Pa (Toshiba, 1995). Mixed oxides of Nb, Mg, Ga and Mn, doped with 0.005–0.52% Pa2O5, were used as high temperature dielectrics (up to 1300 C) for ceramic capacitors (Fujikawa et al., 1996). One of the important applications of Pa can be in the determination of ancient subjects using a 231Pa/235U dating method. This method was used for the dating of one of the Qafzeh human skulls, Qafzen 6, excavated in 1934 by Neuville and Stekelis and conserved at the Institut de Pale´ontologie Humaine in Paris, by non‐destructive gamma‐ray spectroscopy. A long‐term measurement resulted in an age of (94 10) Ka and confirmed the great antiquity of the Proto‐Cro‐Magnons of the Near East, contributing to the establishment of modern man’s chronology (Yokoyama et al., 1997). The Neanderthal hominid Tabun C1, found in Israel by Garod and Bate, was attributed to either layer B or C of their stratigraphic sequence. Gamma‐ray spectroscopy of the 231 Pa/235U ratios of two bones from this skeleton was used to determine their age. Calculations gave the age of the Tabun C1 mandible as 345 Ka. This suggests that Neanderthals did not necessarily coexist with the earliest modern humans in the region. The early age determined for the Tabun skeleton would suggest that Neanderthals survived as late in the Levant as they did in Europe (Schwarcz et al., 1998). Uranium‐series dating of bones and teeth from the Chinese Paleolithic sites has also been used (Chen and Yuan, 1988). As a result of the development of the nuclear industry (e.g. nuclear power engineering and nuclear powered fleets), a considerable amount of radioactive wastes and spent nuclear fuel is accumulating in the world. Geological disposal of solid and solidified nuclear waste is considered as being economical, technically and ecologically the most feasible approach to completion of the nuclear fuel cycle. Thus determination of chemical behavior of actinides elements, Pa included, is an important problem of environmental science. The sorption behavior of Pa, which is a decay product of uranium, was studied on the principal rock types from the potential areas selected for construction of a repository. The sorption distribution coefficients (Kd) of Pa were determined under ambient conditions in oxic and anoxic (N2) atmospheres using natural fresh and brackish groundwater; and the values obtained were 0.07–2.3 and 1.7–12 m3 kg–1, respectively (Kulmala et al., 1998). Pickett and Murrell (1997) presented the first survey of 231Pa/235U ratios in volcanic rocks; such measurements were made possible by new mass spectrometric techniques. It was shown that the high 231Pa/235U ratios in basalts reflect a large degree of discrimination between two incompatible elements, posing challenges for modeling of melt generation and migration. Fundamental differences in 231Pa/235U ratios among different basaltic environment are likely related to differences in melting zone conditions (e.g. melting rate). Strong disequilibria in continental basalts demonstrate that Pa–U fractionation is possible in both garnet and spinel mantle stability fields.

Protactinium

190 4.5

ATOMIC PROPERTIES

Experimental measurements (Marrus et al., 1961; Giaechetti, 1966; Richards et al., 1968) and theoretical calculations (Judd, 1962; Wilson, 1967, 1968) agree that the ground state configuration of the neutral Pa atom is almost certainly [Rn] 5f26d17s2. However, some unpublished calculations by Maly (cited by Cauchois (1971)) indicated that the total relativistic energy of that structure was 0.9 eV higher than that of a 5f 16d27s2 configuration, implying that the latter may be the more stable of the two. Giaechetti (1967) found that the ground state configuration of the first ion of Pa (Pa1þ) was 5f27s2 and this was confirmed by theoretical calculations, which also yielded 5f26d1, 5f2 and 5f1 as the ground state configurations of Pa2þ, Pa3þ and Pa4þ, respectively. Crystal structure stabilities and the electronic structure of Pa have been discussed by Wills and Ericsson (1992). The emission spectrum of Pa was first recorded by Schu¨ler and Gollnow (1934), who reported a large number of lines in the visible region, many of which showed hyperfine splitting patterns, indicating a nuclear spin of 3/2 for 231 Pa. Tomkins and Fred (1949) listed 263 lines in the ultraviolet region sensitive to copper spark excitation. The emission spectrum excited by a microwave discharge tube was measured by Richards and co‐workers (1963, 1968), who recorded some 14 000 lines between 3 mm and 400 nm, about half of which were fitted into a level scheme of about 200 even and 300 odd levels. Table 4.4 lists recommended X‐ray atomic energy levels, based on the X‐ray wavelengths re‐evaluated by Bearden (1967) and by Bearden and Burr (1967). The Mo¨ssbauer effect has been studied by Croft et al. (1968) with the 84.2 keV g‐ray of 231Pa, following b–-decay of 231Th; resonance absorption was detected Table 4.4 Recommended values of the atomic energy levels (eV ) of Pa (measured values of the X‐ray absorption energies are shown in parentheses) (Bearden and Burr, 1967). Level

Energy (eV )

Level

Energy (eV )

K LI

1 12 601.4 2.4 21 104.6 1.8 (21 128) 20 313.7 1.5 (20 319) 16 733.1 1.4 (16 733) 5366.9 1.6 5000.9 2.3 4173.8 1.8 3611.2 1.4 (3608) 3441.8 1.4 (3436)

NI NII

1387.1 1.9 1224.3 1.6

NIII

1006.7 1.7

NIV

743.4 2.1

NV NVI NVII OI OII OIII OIV OV

708.2 1.8 371.2 1.6 359.5 1.6 309.6 4.3

LII LIII MI MII MIII MIV MV

222.9 3.9 94.1 2.8

The metallic state

191

with absorbers of both Pa2O5 and PaO2. No isomer shift between the valence states was observed.

4.6

THE METALLIC STATE

Grosse (1934a) prepared metallic Pa by two methods: (1) Pa2O5 was bombarded for several hours with 35 kV electrons at a current strength of 5–10 mA and (2) the pentahalide (Cl, Br, I) was heated on a tungsten filament at a pressure of 106 to 10–5 torr. Later authors have prepared the metal by reduction of PaF4 with the vapors of Ba (Sellers et al., 1954; Bansal, 1966; Cunningham, 1966, 1971; Dod, 1972), Li (Fowler et al., 1965; Cunningham, 1971), or Ca (Marples, 1966). A Zn–Mg reductant is said to yield an impure Pa product (Lee and Marples, 1973). In the method used by Cunningham and his co‐workers at Berkeley (Cunningham, 1971; Dod, 1972), PaF4 is mixed with barium in a crucible fabricated from a single crystal of BaF2 (or LiF) and supported in a tantalum foil cylinder. The assembly is evacuated to below 10–6 torr and heated inductively to 1250–1275 C for 4–5 min. The BaF2 crucible is then melted by raising the temperature to 1600 C for 1.5 min and then molten Pa metal agglomerates as a small sphere at the bottom of the Ta support ring. Individual preparations are limited to about 15 mg. Subsequently, individual preparations of Pa metal of up to 0.5 g have been successfully executed by a modified Van Arkel technique (Baybarz et al., 1976; Brown et al., 1977; Bohet and Muller, 1978; Brown, 1982; Spirlet, 1982). The starting material is protactinium carbide obtained by reduction of Pa2O5 with carbon. Heating the protactinium carbide with I2 generates volatile PaI5, which is then decomposed on a heated tungsten filament or, better, a sphere (Spirlet, 1979) using induction heating. Protactinium can be precipitated from diluted HF, H2SO4 solutions as a fine film on several metal plates (Zn, Al, Mn, and other) (Camarcat et al., 1949; Haı¨ssinsky and Bouissie`res, 1958; Stronski and Zelinski, 1964). The electrolytic reduction of Pa from NH4F solutions in the presence of triethylamine at pH 5.8 and 10–20 mA cm–2 also has been realized (Emmanuel‐Zavizziano and Haı¨ssinsky, 1938). Preparation of a protactinium measurement source by the electroplating method also has been reported by Li Zongwei et al. (1998). The availability of pure, single‐crystal Pa metal has made possible the measurement of important physical parameters that cast light on the electronic structure of Pa and for the calculation of its optical properties (Gasche et al., 1996). A theoretical calculation by Soderling and Eriksson (1997) predicted that protactinium metal will undergo a phase transition to the a‐U orthorhombic structure below 1 Mbar (1 Mbar 100 GPa) pressure. At higher pressures, the b‐phase re‐enters into the phase diagram and at the highest pressures an ideal hcp structure becomes stable. Hence, Soderling and Eriksson expect Pa to

192

Protactinium

undergo a sequence of transitions, with the first transition taking place at 0.25 Mbar and the subsequent ones above 1 Mbar. The b!a‐U transition is triggered by the pressure‐induced promotion of the spd‐valence electrons to 5f states. In this regard Pa approaches uranium, which at ambient conditions has one more 5f electron than Pa at similar conditions. At higher compression of Pa, the 5f band broadens and electrostatic interactions in combination with Born–Mayer repulsion become increasingly important and drive Pa gradually to more close‐packed structures. At ultra‐high pressures, the balance between electrostatic energy, Born–Mayer repulsion, and one‐electron band energy stabilizes the hcp (ideal packing) structure. Recent experimental results (Haire et al., 2003) confirm that the stable room temperature and pressure phase of Pa metal is the body‐centered tetragonal (bct) phase. Under high pressure this phase is stable until 77(5) GPa (77 GPa 0.77 Mbar) where it is converted to orthorhombic, the a‐uranium phase, with a small (0.8%) volume collapse. The relative volume of the bct phase decreased smoothly from 1 atm down to a volume ratio of 0.7 before the high‐pressure phase transformation. Experiments continued to a pressure of 130 GPa with no further phase change but with a smooth decrease in the volume of the orthorhombic phase of 0.62. Haire et al. (2003) attribute the structural phase change to an increase in 5f bonding at the higher pressures. The superconducting properties of Pa metal have been described by Smith et al. (1979), who determined the superconducting transition temperature and upper critical magnetic field. Since the superconducting properties of Pa are markedly affected by its 5f electronic structure, it is now evident that Pa is a true actinide element. The heat capacity of a single Pa crystal in the temperature range 4.9–18 K has been reported (Stewart et al., 1980). The unit cell volume of Pa metal first decreases and then increases on cooling from 300 to 50 K (Benedict et al., 1979). The importance of the expansion coefficient in the explanation of specific‐heat parameters has been discussed by Mortimer (1979). A Mo¨ssbauer resonance of 231Pa at 84.2 keV in Pa metal has been reported; the electric field gradient in Pa metal is jeqZ j ¼ (2.05 0.15)  1018 V cm–2 (Friedt et al., 1978; Rebizant et al., 1979). The vapor pressure of liquid Pa metal in the temperature range 2500–2900 K has been measured by a combination of mass spectrometry and Knudsen effusion techniques; the vapor pressure (in Pascals) is given (Bradbury, 1981) by: log½PðPaðliqÞÞ ¼ ½ð31 328 375Þ=T þ ð10:83 0:13Þ: Pa metal is malleable and ductile (Zachariasen, 1952; Sellers et al., 1954). Other physical properties are summarized in Table 4.5. The enthalpy of sublimation of Pa(s) at 298 K has been calculated to be 660 (Bradbury, 1981) or 570 kJ mol–1 (Kleinschmidt et al., 1983). Metallic Pa is attacked by 8 M HCl, 12 M HF, or 2.5 M H2SO4, but the initial reaction ceases quickly, possibly because of the accumulation of a protective layer resulting from the hydrolysis of Pa(V) or Pa(IV) at the metal surface.

body‐centered tetragonal (14/mmm) high temp. form is fcc or bcc a ¼ 3.925 0.005, c ¼ 3.238 0.007 (RT) a ¼ 3.924 0.001, c ¼ 3.239 0.0005 (18 C) (a/c approaches 1 with increased temperature) a ¼ 3.929 0.001, c ¼ 3.241 0.002 (RT) a ¼ 3.921 0.001, c ¼ 3.235 0.001 (RT) a ¼ 5.02 (high temperature form fcc) a ¼ 5.018 (high temperature form fcc) a ¼ 3.81 (high temperature form bcc) 15.37 0.08 1.63 for coordination number 12 1575 20 1560 20 1565 20 1562 15 1  10–8 at 2400 K 5.1  10–5 at 2200 K (250 50)  10–6 (temperature‐independent) (268 14)  10–6 (temperature‐independent) (189 6.5)  10–6 (temperature‐independent) 1.4 ? 2 2

crystal structure

superconducting transition temperature (K)

magnetic susceptibility (emu mol–1; 20–298 K)

vapor pressure (atm)

X‐ray density (g cm–3) ˚) metallic radius (A  melting point ( C)

˚) lattice parameters (A

Observed or calculated value(s)

Property

Cunningham (1966) Bohet (1977) Asprey et al. (1971) Bohet (1977) Marples (1965) Zachariasen (1952) Zachariasen (1952) Marples (1966) Cunningham (1966) Cunningham (1971) Dod (1972) Cunningham (1971) Murbach (1957) Cunningham (1966) Bansal (1966) Dod (1972) Fowler et al. (1965, 1974) Smith et al. (1979) Francis and Theng‐Da Tchang (1935) Launay and Dolechek (1947)

Zachariasen (1952); Sellers et al. (1954) Marples (1966)

Zachariasen (1952); Asprey et al. (1971)

References

Table 4.5 Some physical properties of protactinium metal.

Protactinium

194

Table 4.6 Preparation and structure of protactinium–noble‐metal alloy phases (Erdmann, 1971; Erdmann and Keller, 1971, 1973).

Compound

Reduction temperature ( C)

Structure type

Pt3Pa Pt5Pa Ir3Pa Rh3Pa Be13Pa

1250 50 1200 50 1550 50 1550 50 1300 50

Cd3Mg (hex) Ni5U Cu3Au Cu3Au NaZn13

Lattice parameters ˚) (A a

c

5.704 7.413 4.047 4.037 10.26

4.957

The metal does not react with 8 M HNO3 even in the presence of 0.01 M HF. The most effective solvent found thus far is a mixture of 8 M HCl and 1 M HF (Cunningham, 1971). According to Dod (1972), metal samples exposed to air at room temperature show little or no tarnishing over a period of several months. A slight loss of metallic luster was observed when a sample of Pa metal was heated in air for 1 h at 100 C. Heating for 1 h at 300 C caused the sample to turn grayish white and begin to disintegrate. Pa metal exposed to O2, H2O, or CO2 at 300 and 500 C yielded Pa2O5; reaction with NH3 and H2 produced PaN2 and PaH3, respectively. The metal reacts quantitatively with excess I2 above 400 C to yield a sublimate of crystalline, black PaI5 (Sellers et al., 1954; Brown et al., 1967b). 4.6.1

Alloys

Erdmann and Keller (Erdmann, 1971; Erdmann and Keller, 1971, 1973) have prepared Pa–noble‐metal alloy phases by reduction of Pa2O5 with highly purified H2 in the presence of Pt, Ir, and Rh. Preparation conditions and some properties of these intermetallic compounds are listed in Table 4.6. Reaction of Pa2O5 with beryllium metal has been reported by Benedict et al. (1975) to form Be13Pa. 4.7

SIMPLE AND COMPLEX COMPOUNDS

4.7.1

Protactinium hydride

Perlman and Weisman (1951) and Sellers et al. (1954) reacted H2 with Pa metal at about 250 C and a pressure of about 600 torr, and obtained a black flaky substance, isostructural with b‐UH3. The compound was cubic, with a unit cell ˚ . However, Dod (1972) reported the formation constant a ¼ (6.648 0.005) A at 100, 200, and 300 C of a gray, powdered substance that is isostructural with ˚ for the product a‐UH3. The unit cell constant of a‐PaH3 is (4.150 0.002) A   ˚ obtained at 100 and 200 C and (4.154 0.002) A at 300 C. Subsequently, Brown (1982) prepared a‐ and b‐PaH3 at 250 and 400 C, respectively.

Simple and complex compounds 4.7.2

195

Protactinium carbides

Lorenz et al. (1969) prepared PaC by reduction of Pa2O5 with graphite at reduced pressure and temperatures above 1200 C. The product obtained at ˚. 1950 C was face‐centered cubic ( fcc) (NaCl type) with a ¼ (5.0608 0.0002) A  At 2200 C, some additional weak lines, attributable to PaC2, were observed; ˚ and c ¼ this structure was body‐centered tetragonal with a ¼ (3.61 0.01) A ˚ (6.11 0.01) A. According to Sellers et al. (1954), PaC was ‘probably’ prepared by the reduction of PaF4 with Ba in a carbon crucible. The magnetic susceptibility of PaC between 4 K and room temperature was measured by Hery et al. (1977). The magnetic susceptibility of PaC is weak (about 50  106 (emu cg).mol–1) and essentially independent of temperature, which may be taken to indicate the absence of 5f electrons and the presence of Pa(V) in the compound. Theoretical calculations by Maillet (1982) suggest that in ThC 5f electron participation in the bonding is minimal, but that in PaC the 5f electron bonding contribution is important.

4.7.3

Protactinium oxides

The known binary oxides of Pa are listed in Table 4.7. White Pa2O5 is obtained when the hydrated oxide, Pa2O5 · nH2O, and a wide variety of protactinium compounds as well are heated in oxygen or air above 500 C (Kirby, 1961) or 650 C (Sellers et al., 1954; Keller, 1977). Thermochemical studies (Kleinschmidt and Ward, 1986) and differential thermal analysis shows three endothermic peaks, with maxima at 80, 390, and 630 C, and an exothermic peak, whose maximum occurs at 610 C (Stchouzkoy et al., 1968). Several crystal modifications can be prepared, depending on the temperature to which the Pa2O5 is heated (Stchouzkoy et al., 1964, 1966b; Roberts and Walter, 1966). Black PaO2 is prepared by the reduction of Pa2O5 with H2 at 1550 C (Sellers et al., 1954). Pa dioxide did not dissolve in H2SO4, HNO3, or HCl solutions but reacted with HF because of the Pa(IV) oxidation to the pentavalent state by O2 (Pal’shin et al., 1970). Four intermediate phases have been identified by reduction of the pentoxide and oxidation of the dioxide (Roberts and Walter, 1966). A monoxide has been claimed to exist as a coating on metal preparations (Sellers et al., 1954). The heat of formation of Pa2O5 is about 106 kJ mol–1 as calculated by Augoustinik (1947). Pa2O5 did not dissolve in concentrated HNO3 (Jones, 1966), but dissolved in HF and in a HF þ H2SO4 mixture (Codding et al., 1964) and reacted at high temperatures with solid oxides of metals of groups I and II of the periodic table (Pal’shin et al., 1970). Ternary oxides and oxide phases of different compositions and structures have been prepared by reaction of PaO2 and Pa2O5 with the oxides of other elements (Table 4.8) (Keller, 1964a,b, 1965a–c, 1966a,b, 1971; Keller and Walter, 1965; Keller et al., 1965; Iyer and Smith, 1966).

Symmetry cubic (NaCl) fcc (CaF2) fcc fcc tetragonal tetragonal rhombohedral fcc tetragonal tetragonal hexagonal hexagonal orthorhombic rhombohedral

Composition

PaO PaO2 PaO2 PaO2.18–PaO2.21 PaO2.33 PaO2.40–PaO2.42 PaO2.42–PaO2.44 Pa2O5 Pa2O5 Pa2O5 Pa2O5 Pa2O5 Pa2O5 Pa2O5

4.961 5.509 5.505 5.473 5.425 5.480 5.449 5.446 5.429 10.891 3.820 3.817 6.92 5.424

˚) a (A

4.02

˚) b (A

Lattice constants

Table 4.7

5.503 10.992 13.225 13.220 4.18

5.568 5.416

˚) c (A

89.76

89.65

a (deg.)

Binary oxides of protactinium.

650–700 700–1000 700–1050 1050–1500 1000–1500 ? 1240–1400

Temp, range of existence ( C)

Sellers et al. (1954) Roberts and Walter (1966) Sellers et al. (1954) Roberts and Walter (1966) Roberts and Walter (1966) Roberts and Walter (1966) Roberts and Walter (1966) Sellers et al. (1954) Roberts and Walter (1966) Stchouzkoy et al. (1968) Stchouzkoy et al. (1968) Roberts and Walter (1966) Sellers et al. (1954) Roberts and Walter (1966)

References

Simple and complex compounds

197

Table 4.8 Polynary oxides of protactinium (Keller, 1966a, 1971; Palshin et al., 1970). Lattice constants Compound

Structure type

˚) a (A

LiPaO3 Li3PaO4 Li7PaO6 (2–4)Li2O Pa2O5 (2–4)Na2O Pa2O5 NaPaO3 Na3PaO4 KPaO3 RbPaO3 CsPaO3 BaPaO3a SrPaO3a Ba(Ba0.5Pa0.5)O2.75 GaPaO4 (La0.5Pa0.5)O2 Ba(LaO0.5Pa0.5)O3 a‐PaGeO4 b‐PaGeO4a a‐PaSiO4a b‐PaSiO4a Pa2O5/ThO2 PaO2 2Nb2O5a PaO2 2Ta2O5a Pa2O5 3Nb2O5 Pa2O5. 3Ta2O5

unknown tetragonal (Li3UO4) hexagonal (Li7BiO6) cubic (fluorite phase)

4.52 5.55

a

orthorhombic (GdFeO3) tetragonal (Li3SbO4) cubic (CaTiO3) cubic (CaTiO3) unknown cubic (CaTiO3) unknown cubic (Ba3WO6) unknown cubic (CaF2) cubic (Ba3WO6) tetragonal (CaWO4) tetragonal (ZrSiO4) tetragonal (ZrSiO4) monoclinic (CePO4) cubic (fluorite phase) tetragonal (Th0.25NbO3) tetragonal (Th0.25NbO3) hexagonal (UTa3O0.67) hexagonal (UTa3O10.67)

5.82 6.68 4.341 4.368

˚) b (A

˚) c (A

b (deg.)

8.48 15.84 5.97

8.36

6.92

11.38 6.509 6.288 6.54

4.45 8.932 5.525 8.885 5.106 7.157 7.068 6.76 7.76 7.77 7.48 7.425

104.83

7.81 7.79 15.81 15.76

Could not be prepared in the pure state; always contained varying amounts of Pa(V).

The pale yellow product, which precipitates upon addition of H2O2 to a solution of Pa(V) in 0.25 M H2SO4, has been assigned the formula Pa2O9 · 3H2O (Stchouzkoy et al., 1966b). It is considered to be an unstable peroxide with a composition that varies with time over the range Pa2Ox · 3H2O with 5 < x < 9. 4.7.4

Protactinium halides

Methods for preparing all the binary halides and many of the oxyhalides of Pa(IV) and Pa(V) are summarized schematically in Figs. 4.11, 4.12, and 4.13; those compounds which have been fully characterized are listed in Table 4.9. The preparative methods shown in Figs. 4.11 and 4.12 use an aqueous acid solution of Pa(V) as the starting material for the synthesis of binary protactinium halides. PaF5 can be prepared by fluorination of PaC at 570 K or PaCl5 at 295 K. The reaction products are isostructural with b‐UF5 (Brown et al., 1982a). PaF5 · 2H2O is prepared by the evaporation of Pa solution in 30% HF

198

Protactinium

Fig. 4.11 Preparation of some fluoride derivatives of Pa(IV) and Pa(V) (Muxart and Guillaumont, 1974; Pal’shin et al., 1968a).

(Grosse, 1934c). Protactinium carbide is also useful in the preparation of other binary penta‐ and tetrahalides. Brown et al. (1976a) treated PaC with I2 at 400 C, Br2 at 350 C, and SOCl2 at 200 C to obtain PaI5, PaBr5, and PaCl5, respectively. PaI4 was obtained by reaction of PaC with PaI5 at 600 C or by the treatment with HgI2 at 500 C. These compounds were also prepared by reactions of Pa2O5 with Cl2 þ CCl4 at 300 C (!PaCl5) (Pissot et al., 1966); CCl4 at 400 C (!PaCl4) (Sellers et al., 1954); AlBr3 at 317 C (!PaBr5); and AlI3 at 300 C (!PaI5) (D‘Ege et al., 1963) and so on. Protactinium pentafluoride is reduced to PaF4 by PF3 but no reaction occurs with AsF3. PaCl5 and PaCl4 are formed from PaF5 and PaF4 by reaction with PCl3 and SiCl4, respectively. PaF5 reacts with CCl4 to give PaClxF5–x (x probably 1), but no reaction is observed with PaF4 (O’Donnell et al., 1977). Whereas UF5 is very soluble in acetonitrile, PaF5 forms a sparingly soluble complex. An adduct PaF5 · 2Ph3PO forms on addition of TPPO to PaF5 in acetonitrile

Simple and complex compounds

199

Fig. 4.12 Preparation of some chlorides and oxychlorides of Pa(IV) and Pa(V) (Muxart and Guillaumont, 1974; Pal’shin et al., 1968a).

(Brown et al., 1982b). Brown (1979) found still another PaBr5 crystal structure, designated g, isostructural with b‐UCl5. Of the possible halides of Pa(III), only PaI3 has been reported so far (Scherer et al., 1967). It is a dark brown compound (not black as originally reported) (Wilson, 1967), prepared by heating PaI5, for several days at 10–6 torr and 360–380 C. Its tentative identification is based primarily on the similarity of its X‐ray powder pattern to that of CeI3. All the binary halides are volatile at moderate temperatures, a property that has been used for the separation of 233Pa from irradiated ThO2 as well as for the

200

Protactinium

Fig. 4.13 Preparation of some bromide and iodide derivatives of Pa(IV) and Pa(V) (Muxart and Guillaumont, 1974; Pal’shin et al., 1968a).

preparation of radiochemically pure 231Pa and 234Pa (Malm and Fried, 1950; Merinis et al., 1966; Brown, 1971). The vapor pressures of PaCl5 and PaBr5 have been measured by Weigel et al. (1969, 1974) in the temperature range 490–635 K; the boiling points, extrapolated to 760 torr, were 420 and 428 C, respectively. The thermal stability studies of Brown and co‐workers (1976b) show that PaI4 is stable up to a temperature of 330 C, and that PaI5 is stable to 200–300 C. Numerous alkali fluoro complexes of Pa(V) have been identified (Table 4.10) . The first, K2PaF7, was prepared by Grosse (1934a) for use in determining the atomic weight of 231Pa. Complexes of the form MPaF6 (M ¼ Li, Na, K, Rb, Cs, Ag, NH4) can be prepared by crystallization from aqueous HF solutions containing equimolar amounts of Pa(V) and the alkali fluorides, but LiPaF6 and NaPaF6 are best prepared by evaporating the equimolar mixture to dryness and

– Cmm2ðC11 20 Þ UCl4 C2/c Pbam UCl4 P21/c P21/n P1

C2 CeI3 – –

monoclinic

bcc cubic tetragonal

bcc

orthorhombic orthorhombic tetragonal

monoclinic orthorhombic tetragonal monoclinic monoclinic

triclinic

monoclinic orthorhombic

orthorhombic hexagonal

PaF4

Pa2F9 (or Pa4F17) PaF5

Pa2OF8

PaO2F Pa3O7F PaCl4

PaCl5 PaOCI2 PaBr4 a‐PaBr5 b‐PaBr5

g‐PaBr5

PaOBr3 PaI3(?) PaI4 PaI5 PaO2I 21.20

12.12 3.871 14.00

9.25 16.911 4.33 7.22 12.64

10.21(1)

12.82 11.205

12.31 17.903

12.043 12.030

10.88

˚) b (A

7.52(1)

10.35 15.332 8.824 12.69 8.385

6.894 6.947 8.377

11.525 11.53 8.406

b‐UF5 U2F9

8.507

12.86

˚) a (A

Lattice constants

U2F9

UF4

Symmetry

Compound

Structure type or space group

6.85 4.07

9.13 9.334 10.02

6.74(1)

4.143 4.203 7.479 7.482 8.82 4.012 7.957 9.92 8.950

5.218 5.19

8.54

˚) c (A

b ¼ 113.67

a ¼ 89.27(5); b ¼ 117.55(6); g ¼ 109.01(5)

b ¼ 108 b ¼ 91.1

b ¼ 111.8

Soddy and Cranston (1918); Sellers et al. (1954); Asprey et al. (1967) Brown (1966); Stein (1966)

b ¼ 126.34

D‘Ege et al. (1963) Brown et al. (1968b) Scherer et al. (1967) Brown et al. (1976b) Maddock (1960) Brown et al. (1967b)

Brown (1971) Stein (1964) Stein (1964) Brown and Easey (1970) Brown and Easey (1970) Brown and Easey (1970) Brown and Jones (1967c) Sellers et al. (1954) Brown and Maddock (1963) Dodge et al. (1968); Bagnall et al. (1968a) Brown and Jones (1967c) Brown and Petcher (1969) Brown et al. (1968b); Brown and Petcher (1969) Merinis et al. (1966)

References

Angle (deg.)

Table 4.9 Halides and oxyhalides of protactinium.

Structure type or space group LiUF5 Na7Zr6F3, Na7Zr6F3, Na7Zr6F31 – – RbPaF6 RbPaF6 Cmca RbPaF6 C2/c K2PaF7 P42212(D6) 14 mmm Fm3m Fm3m Fm3m

Symmetry

tetragonal rhombohedral rhombohedral rhombohedral monoclinic tetragonal orthorhombic orthorhombic orthorhombic orthorhombic monoclinic monoclinic tetragonal tetragonal fcc fcc fcc

Compound

LiPaF5 Na7Pa6F31 K7Pa6F31 Rb7Pa6F31 (NH4)4PaF8 NaPaF6 NH4PaF6 KPaF6 RbPaF6 CsPaF6 K2PaF7 Cs2PaF7 Li3PaF8 Na3PaF8 K3PaF8 Cs3PaF8 Rb3PaF8

14.96 9.16 9.44 9.64 13.18 5.35 5.84 5.64 5.86 6.14 13.760 14.937 10.386 5.487 9.235 9.937 9.6

˚) a (A

11.90 11.54 11.97 12.56 6.742 7.270

6.71

˚) b (A

Lattice constant

13.22 3.98 8.03 7.98 8.04 8.06 8.145 8.266 10.89 10.89

6.58

˚) c (A

b ¼ 125.17 b ¼ 125.32

a ¼ 107.09 a ¼ 107.15 a ¼ 107.00 b ¼ 17.17

Angle (deg.)

Table 4.10 Some fluoro complexes of Pa(IV) and Pa(V ).

Asprey et al. (1967) Asprey et al. (1967) Asprey et al. (1967) Asprey et al. (1967) Asprey et al. (1967) Asprey et al. (1966) Asprey et al. (1966); Brown (1973) Asprey et al. (1966); Brown (1973) Asprey et al. (1966); Brown (1973) Asprey et al. (1966); Brown (1973) Brown and Easey (1966) Brown et al. (1967a) Brown and Easey (1965, 1966) Brown and Easey (1965, 1966) Brown and Easey (1966) Brown and Easey (1966) Asprey et al. (1966); Brown (1973)

References

Simple and complex compounds

203

fluorinating the dried residue (Asprey et al., 1966). The heptafluoroprotactinates, M2PaF7 (M ¼ K, NH4, Rb, Cs), are precipitated by the addition of acetone to a 17 M HF solution containing Pa(V) and an excess of the appropriate alkali fluoride. NaF in a 3:1 molar ratio to Pa(V) yields Na3PaF8, but the other octafluoroprotactinates (V) are most easily prepared by the reaction: M2 PaF7 þ MF ! M3 PaF8 

at 450 C in an atmosphere of dry argon or by fluorination of the product obtained by evaporation of an HF solution containing 3:1 MF and Pa(V) (Brown and Easey, 1966). The fluoro complexes of Pa(IV) are prepared either by H2 reduction of a Pa(V) complex at 450 C or by heating stoichiometric amounts of the alkali fluoride with PaF4 in a dry argon atmosphere (Asprey et al., 1967). Pa2O5 · nH2O reacts vigorously with SOCl2 at room temperature to yield stable solutions containing up to 0.5 M Pa(V). The product is probably SO(PaCl6)2 which decomposes at 150 C under vacuum. Hexa‐ and octachloroprotactinates (V) are precipitated when CS2 is added to SOCl2 solutions containing equal amounts of PaCl5 and MCl (M ¼ N(CH3)4, N(C2H5)4, NH2(CH3)2, and (C6H5)4As). Hexachloro complexes with Csþ and NHþ 4 precipitate when the component halides are reacted in SOCl2/ICl mixtures (Bagnall and Brown, 1964). Hexabromoprotactinate (V) complexes, MPaBr6 (M ¼ N(CH3)4, N(C2H5)4), have been prepared by vacuum evaporation of stoichiometric quantities of PaBr5 and the tetraalkylammonium bromide dissolved in anhydrous CH3CN (Brown and Jones, 1967b). Axe and co‐workers (Axe, 1960, Axe et al., 1960, Axe et al., 1961) observed the paramagnetic resonance spectrum of Pa4þ in single crystal of Cs2ZrCl6, crystallized from a melt containing approximately 500 mg of 231PaCl4. The 5f1 structure was confirmed, as was the nuclear spin of 3/2. The resonance spectrum was found to be isotropic, with a spectroscopic splitting factor g ¼ –1.14. Hendricks et al. (1971) measured the magnetic susceptibility of PaCl4 from 3.2 to 296 K and found a ferromagnetic transition at about 182 K. PaCl4 is virtually insoluble in SOCl2, but hexachloro‐ and hexabromoprotactinates (IV), M2PaX6 (X ¼ Cl, Br; M ¼ N(CH3)4 and N(C2H5)4), have been prepared by reaction of PaX4 with the tetraalkylammonium halide in CH3CN. Cs2PaCl6 is precipitated on the addition of CsCl to a solution of PaCl4 in concentrated HCl. The hexaiodo complex, [(C6H5)3CH3As]2PaI6, was also prepared from the component iodides dissolved in CH3CN (Brown and Jones, 1967a). The electronic structures and optical transition energies of PaX2 6 (X ¼ F, Cl, Br, I) were calculated by quasi‐relativistic density functional methods (Kaltsoyannis and Bursten 1995; Kaltsoyannis 1998). Analysis of the 4þ 5f1!6d1 transitions in PaX2 was reported by 6 (X ¼ Cl, Br) and ThBr4:Pa 4þ Edelstein et al. (1988), and the EPR spectra of ThBr4:Pa in the incommensurate phase was detected (Zwanenburg et al., 1988). The fluorescence and absorption spectra between the ground 5f1 and the excited 6d1 configurations of

Protactinium

204

Pa4þ diluted into a single crystal of Cs2ZrCl6 were analyzed (Piehler et al., 1991; Edelstein et al., 1992). Numerous halide complexes of Pa(IV) and Pa(V) are formed with oxygen donor ligands, such as substituted phosphine oxides (Brown et al., 1966b, 1970a,b), hexamethylphosphoramide (Brown and Jones, 1966a), DMSO (Bagnall et al., 1968b), tropolone (Brown and Rickard, 1970), N,N‐dimethylacetamide (Bagnall et al., 1969), acetylacetone (Brown and Rickard, 1971b), and N,N‐diethyldithiocarbamate (Heckley et al., 1971). In addition, complexes with sulfur and selenium donors have been reported (Brown et al., 1971).  The ground state electronic structures of PaX2 6 (X ¼ F, Cl, Br, I), UX6 (X ¼ F, Cl, Br), and NpF6 have been calculated using both non‐relativistic and relativistic implementations of the discrete‐variational X alpha (DV‐X alpha) method. A significant amount of metal–ligand covalent bonding is found, involving both 6d and 5f metal orbitals. The 5f contribution to the bonding  levels increases significantly from PaX2 6 to UX6 to NpX6 but remains approxi mately constant as the halogen is altered in PaX2 6 and UX6 . In contrast, the 6d atomic orbital character of the halogen‐based levels increases from UF 6 to 2 UBr and a similar, though less marked, trend is observed in PaX . The 6 6 electronic transition energies have been calculated using the transition‐state method. The relativistic calculations are far superior to the non‐relativistic ones in both qualitatively and quantitatively describing the electronic spectra. The stabilization of the metal 5f atomic orbitals with respect to the halogen np levels from Pa to Np results in the more energetic f!f transitions in NpF6 being masked by the onset of a ligand‐to‐metal charge transfer band. In the remaining molecules, the f!f transitions occur well removed from charge transfer bands (Kaltsoyannis, 1998). Several chloro complexes and one bromo complex for which crystallographic data are available are listed in Table 4.11. 4.7.5

Protactinium pnictides

Protactinium pnictide compounds have been prepared and constitute a new category of Pa compounds that have several features of more than usual interest. The protactinium phosphide, PaP2, was prepared by reaction of elemental phosphorus with protactinium hydride; thermal dissociation of PaP2 forms Pa3P4 (Table 4.12) (Wojakowski et al., 1982). The diarsenide, PaAs2, can be obtained by heating together PaH3 and elemental arsenic at 400 C; heating PaAs2 to 840 C results in decomposition of PaAs2 to form Pa3As4 (Hery et al., 1978). PaAs2 has a tetragonal structure of the anti‐Fe2As type, and Pa3As4 crystallizes in a body‐centered structure of the Th3P4‐type (Table 4.12). Single crystals of PaAs2, Pa3As4, PaAs, and Pa3Sb4 were prepared from the elements by a Van Arkel procedure using vapor transport; iodine was the transporting agent and deposition occurred on an induction‐heated tungsten support (Calestani et al., 1979a,b). Hery and co‐workers (1979) have obtained Pa3Sb4 and PaSb2 by heating PaH3 with antimony.

trigonal fcc orthorhombic fcc triclinic monoclinic monoclinic

Cs2PaCl6 (NMe4)2PaCl6 (NEt4)2PaCl6 (NMe4)2PaBr6 Pa(Trop)4Cl,DMSO

(NEt4)2PaOCl5

Pa(Acac)2Cl3

8.01

14.131

7.546 13.08 14.22 13.40 9.87

˚) a (A

23.42

18.63

13.235

15.96

12.60 14.218

13.35

6.056

˚) c (A

14.75

˚) b (A

Me, methyl; Et, ethyl; Trop, tropolonate; DMSO, dimethyl sulfoxide; Acac, acetylacetonate.

Symmetry

Compound

Lattice constants

b ¼ 98.9

a ¼ 119.8; b ¼ 103.6; g ¼ 103.0 b ¼ 91.04

Angle (deg.)

Table 4.11 Some chloro and bromo complexes of Pa(IV) and Pa(V).

Brown and Rickard (1971a); Brown et al. (1972) Bagnall et al. (1969)

Brown and Jones (1967a) Brown and Jones (1967a) Brown and Jones (1966a,b) Brown and Jones (1967a,b) Brown and Rickard (1970)

References

Trop, tropolone.

hexagonal hexagonal tetragonal tetragonal tetragonal tetragonal fcc monoclinic orthorhombic tetragonal tetragonal

H3PaO(SO4)3 H3PaO(SeO4)3 PaOS [N(C2H5)4]4Pa(NCS)8 [N(C2H5)4]4Pa(NCSe)8 Pa(HCOO)4 HPaOP2O7 (PaO)4(P2O7)3 Pa2O5·Pa2O5 PaP2 a Pa(Trop)5

a

Symmetry

Compound 9.439 9.743 3.832 11.65 11.82 7.915 5.92 12.23 5.683 3.898 9.759

˚) a (A

13.44 12.06

˚) b (A

Lattice parameters

8.96 14.34 7.845 9.46

5.506 5.679 6.704 23.05 23.49 6.517

˚) c (A

113.88

g (deg.)

Bagnall et al. (1965) Bagnall et al. (1965) Sellers et al. (1954) Al‐Kazzaz et al. (1972) Al‐Kazzaz et al. (1972) Bohres (1974); Greis et al. (1977) LeCloarec (1974) LeCloarec (1974); Lux et al. (1980) LeCloarec (1974); Lux et al. (1980) Bhandari and Kulkarni (1979) Bhandari and Kulkarni (1979)

References

Table 4.12 Crystallographic data for some miscellaneous compounds of protactinium.

Simple and complex compounds

207

The magnetic susceptibility of PaAs2 and PaSb2 has been measured from 4 K to room temperature. PaAs, PaAs2, and PaSb2 exhibit temperature‐independent paramagnetism (Hery et al., 1978). Self‐consistent band structure calculations show that PaN and PaAs have about one f‐electron, and hence they are expected to be paramagnetic; these results have been confirmed by experiment (Hery, 1979; Brooks et al., 1980). 4.7.6

Miscellaneous compounds

Pa2O5 is insoluble in nitric acid but the freshly prepared hydroxide, the pentachloride, the pentabromide, and the complex SO(PaCl6)2 all dissolve in fuming HNO3 to form stable solutions of at least 0.5 M Pa(V). Vacuum evaporation of such solutions yields PaO(NO3)3 · xH2O (1 < x < 4). The reaction of Pa(V) halides with N2O5 in anhydrous CH3CN yields Pa2O(NO3)4 · 2CH3CN. Complexes of the type MPa(NO3)6 (M ¼ Cs, N(CH3)4, N(C2H5)4) have been prepared by reaction of the hexachloroprotactinates (V) with liquid N2O5 at room temperature (Brown and Jones, 1966b; Jones, 1966). When a solution of Pa(V) in a mixture of HF and H2SO4 is evaporated until all F– ion has been eliminated, H3PaO(SO4)3 crystallizes almost quantitatively. The analogous selenato complex, more stable in acid (6 M HCl) or basic (NH4OH) media, is obtained from HF/H2SeO4 mixtures. The sulfato‐complex decomposes to HPaO(SO4) at 375 C (Bagnall et al., 1965; Bagnall, 1966b) and to Pa2O5 at 750 C (Pal’shin et al., 1968b). The binary chalcogenides, b‐PaS2 and g‐PaSe2, have been prepared by Hery (1979). PaOS was obtained by the reaction of PaCl5 with a mixture of H2S and CS2 at 900 C (Sellers et al., 1954). PaF2SO4 · 2H2O is precipitated when a solution of Pa(IV) in 4.5 M H2SO4 is added to 3 M HF (Stein, 1966). Crystallographic data for some S and Se compounds are given in Table 4.12. The addition of hydrochloric acid to a solution of Pa(V) oxalate causes the precipitation of PaO(C2O4)(OH) · xH2O (x 2) (Muxart et al., 1966a). On the other hand, the addition of acetone instead of acid yields Pa(OH)(C2O4)2 · 6H2O (Davydov and Pal’shin, 1967). Phenylarsonic acid forms a white flocculent precipitate with Pa(V) in neutral or acid solutions. The compound is believed to have the composition H3PaO2(C6H6AsO3)2 (Myasoedov et al., 1968c). Complexes of the type [N(C2H5)4]4PaR8 (R ¼ NCS or NCSe) have been prepared by reaction of PaCl4 with stoichiometric amounts of KCNS or KCNSe in anhydrous CH3CN (Table 4.12) (AI‐Kazzaz et al., 1972). The bis(phthalocyaninato)complexes of Pa(IV), (C32H16N8)2Pa, have been prepared by neutron irradiation of the corresponding thorium 233ThPc2 complex by the reactions (Lux et al., 1970, 1971): 232

ThPc2 ðn; gÞ 233 ThPc2 ! 233PaPc2 þ b

Spectroscopically pure bis(phthalocyaninato)protactinium(IV) (PaPc2) was prepared by reaction between PaI4 · 4CH3CN and o‐phthalic dinitrile in

208

Protactinium

1‐chloronaphthalene followed by purification by sublimation. PaPc2 is isostructural with ThPc2 and UPc2 (Lux et al., 1980). Tetrakis(cyclopentadienyl)Pa(IV), (C5H5)4Pa, was prepared by treating Pa2O5 with a mixture of Cl2 þ CCl4 in an argon stream at 600 C, then fusing the reaction product with Be(C2H5)2 at 65 C (Keller, 1964b; Baumgartner et al., 1969). Protactinium(IV) tropolone, Pa(Trop)4, has been prepared by reaction of PaCl4 or PaBr4 with lithium tropolonate, Li(Trop) in methylene chloride; in the presence of excess Li (Trop) in dimethyl formamide, LiPa(Trop)5 is formed (Brown and Richard, 1970). However, when protactinium pentethoxide, which is obtained by reaction of PaCl5 with sodium ethoxide in anhydrous alcohol (Maddock and Pires deMatos, 1972; Bagnall et al., 1975), is treated with tropolone, the complex Pa (Trop)5 is obtained. Pa(Trop)5 has been crystallized and its crystal structure parameters are determined (Table 4.12) (Bhandari and Kulkarni, 1979). Complexes of the actinide elements with cyclooctatetrene have been obtained by reaction of an actinide halide with cyclooctatetrene anion. The bis(Z8‐tetramethylcyclooctatetradiene) complex of Pa has been prepared by reaction of Pa borohydride, Pa(BH4)4, with tetramethylcyclooctatetrene dianion (Solar et al., 1980). The preparation of the anhydrous tetraformate, Pa(HCOO)4, has been reported by the reaction of PaCl4 with O2‐free HCOOH at 60 C in an argon atmosphere for 4 h (Table 4.12) (Bohres, 1974; Bohres et al., 1974). Freshly precipitated Pa(V) hydroxide or peroxide dissolves readily in 14 M H3PO4. However, upon aging, the hydrated orthophosphate, PaO(H2PO4)3 · 2H2O, crystallizes out. Calcination of this product yields, successively: the anhydrous orthophosphate, PaO(H2PO4)3 between room temperature and 300 C; the trimetaphosphate, PaO(PO3)3, stable to 900 C; the pyrophosphate, (PaO)4(P2O7)3, at 1000 C; and an unidentified phase with the gross composition Pa2O5 · P2O5 at 1200 C (LeCloarec et al., 1970, 1976; LeCloarec and Muxart, 1971; LeCloarec, 1974). Crystallographic data for several phosphates are given in Table 4.12. Protactinium(V) perrhenate, PaO(ReO4)3 · xH2O, has been prepared by reaction of Pa2O5 and Re2O7 (Silvestre et al., 1977). Protactinium(IV) borohydride, Pa(BH4)4, has been prepared by treating PaF4 with aluminum borohydride, Al(BH4)3. It is a relatively unstable solid at 20 C, but exhibits high volatility as do other actinide borohydrides. Pa(BH4)4 is isostructural with U(BH4)4 (Banks et al., 1978; Banks, 1979; Banks and Edelstein, 1980). The molecular compound, Pa(BH3CH3)4, has been synthesized from the reaction of PaCl5 or PaCl4 with Li(BH3CH3). Its optical and NMR spectra have been obtained. Because of the Td symmetry at the Pa4þ site, the dipolar shift is zero and the temperature‐dependent proton and 11B shifts are attributed to spin delocalization mechanisms. The 1H NMR peaks of both the bridging and terminal protons shift to lower field as the temperature is decreased. These observations are inconsistent with a spin‐polarization mechanism, which assumes that the temperature‐dependent shifts are proportional to the average value of the electron spin in the 5f orbitals. In addition, new synthetic routes to Pa(BH4)4 and Pa(MeCp)4 (MeCp ¼ methylcyclopentadienyl) are described. They are simpler and more convenient than the earlier

Solution chemistry

209

published methods and take advantage of the unexpected solubility of PaCl5 in aromatic hydrocarbons (Kot and Edelstein, 1995). The 5f–6d absorption spectrum of Pa4þ/CsZrCl6 (Edelstein et al., 1992) and magnetic data of tetravalent protactinium(IV) (Edelstein and Kot, 1993) also were reported.

4.8

SOLUTION CHEMISTRY

Two oxidation states, Pa(IV) and Pa(V), have been definitely established in aqueous solution (Haı¨ssinsky and Bouissie`res, 1948, 1951; Bouissie`res and Haı¨ssinsky, 1949), but all attempts to demonstrate the existence of Pa(III) in solution have led to negative or inconclusive results (Elson, 1954; deMiranda and Maddock, 1962; Musikas, 1966). Both Pa(IV) and Pa(V) show strong tendencies to hydrolyze in the absence of complexing agents and most studies of the ionic species of Pa in aqueous solution have therefore been carried out at the tracer level. Furthermore, the instability of Pa(IV) toward reoxidation has made it difficult to obtain reproducible data on this oxidation state, so that, until quite recently, little quantitative information has been available about the aqueous chemistry of Pa(IV). The behavior of protactinium in aqueous solution has been very thoroughly reviewed by Guillaumont, Bouissie`res, and Muxart (Guillaumont et al., 1968; Bouissie`res, 1971; Muxart and Guillaumont, 1974) and by Pal’shin et al. (1970); those reviews should be consulted for more detail than can be given here. For a general discussion of the techniques used in the determination of stability constants, see Rossotti and Rossotti (1961), Fronaeus (1963), or Ahrland et al. (1973). 4.8.1

Hydrolysis of Pa (V) in non‐complexing media

The hydrolytic behavior of Pa(V) has been studied by a large number of investigators (Jakovac and Lederer, 1959; Guillaumont, 1966a, 1971; Liljenzin and Rydberg, 1966; Scherff and Hermann, 1966; Suzuki and Inoue, 1966, 1969; Kolarich et al., 1967; Mitsuji and Suzuki, 1967; D’yachkova et al., 1968a; Mitsuji, 1968; Liljenzin, 1970; Cazaussus et al., 1971) whose conclusions are summarized schematically in Figs. 4.14 and 4.15 (Bouissie`res, 1971). The hydrolysis of Pa(V) is usually studied in perchloric acid solutions, because ClO 4 is considered to be a non‐complexing anion. However, the presence of small amounts of weakly complexing anions does not affect the results. Thus, Br > I > NO3  ClO4 Ionic species of Pa(V) in nitric acid solution

In general, NO 3 is a poor complexing anion for Pa(V) but freshly prepared solutions, in which [Pa(V)]  10–5 M and [HNO3]  1 M, are fairly stable. Such

Solution chemistry

213

systems contain monomeric nitratohydroxo complexes of the form [Pa (OH)n(NO3)m]5–n–m, where n  2 and m  4 (Hardy et al., 1958). The transition from cationic to anionic forms occurs at [HNO3] 4–5 M. Stability constants for several suggested species in this medium are listed in Table 4.15. (b)

Ionic species of Pa(V) in hydrochloric acid solution

Solutions of Pa(V) in hydrochloric acid are generally unstable with respect to hydrolytic condensation when [Pa] 10–3 M, although complete precipitation may take as long as several weeks (Kirby, 1966). If the freshly precipitated hydroxide is dissolved in 12 M HCl and then diluted to [Pa] 10–4 M and 1 M < [HCl] < 3 M, the solution is reasonably stable and will then contain a mixture of monomeric chloro complexes in thermodynamic equilibrium. It is generally agreed that, for [HCl] < 1 M and [Pa] < 10–5 M, the species present are the same as those described above for perchloric acid media, while, for [HCl] 3 M, the predominant species is PaOOHClþ. The complexes that have been proposed to explain the solvent extraction and ion‐exchange behavior of Pa(V) at higher acidities are summarized in Table 4.16. The study of complex formation of Pa in aqueous HCl solutions of medium and high concentrations and the electronic structures of anionic complexes of [PaCl6]–, [PaOCl4]–, [Pa(OH)2Cl4]–, and [PaOCl5]2– have been calculated using the relativistic Dirac–Slater discrete‐ variational method. The charge density distribution analysis has shown that protactinium has a slight preference for the [PaOCl5]2– form or for the pure halide complexes with coordination number higher than six under these conditions. On the other hand, Ta occupies a specific position in the group and has the highest tendency to form the pure halide complex [TaCl6]–; niobium has equal tendencies to form the NbCl6 and [NbOCl5]2– species (Pershina et al., 1994). There are no data on the species of protactinium in HBr and HI solutions. Goble and co‐workers (1956, 1958) suggested on the basis of 231Pa extraction from HBr and HI aqueous solutions that bromide and iodide complexes of protactinium are less stable than the chloride complexes. (c)

Fluoro complexes of Pa(V)

The solubility of Pa(V) is relatively high at all concentrations of hydrofluoric acid; thus, 0.05 M HF dissolves 3.9 g L–1 of 231Pa and 20 M HF dissolves at least 200 g L–1 of the pentoxide (Bagnall et al., 1965). The solubility of Pa(V) is estimated to be 11.2 g L–1 in 8 M HCl and 0.6 M HF and at least 125 g L–1 in 8 M HCl and 5 M HF (Chilton, 1964). Solutions of Pa(V) in aqueous HF are very stable with respect to hydrolysis and are probably the only systems that contain no polymeric species. A great many complexes have been proposed to explain the behavior of Pa(V) in aqueous HF (deMiranda and Muxart, 1965; Bukhsh et al., 1966a,b;

2

4

1

6

6

5

2

4

1

6

6

5–6

K2 ¼ 3.0 K4 ¼ 11.93 K1 ¼ 0.79 K2 ¼ 0.74 K1 ¼ 0.63 K2 ¼ 0.21 K1 ¼ 1.43 K2 ¼ 0.07

[PaOx(OH) 4–2x(NO3)2]– [PaOx(OH) 2–2x(NO3)3]–

0.4–5

3–6

1–3

1

1

K6 ¼ 0.141 K7 ¼ 1.09 K1 ¼ 17 K2 ¼ 127 K3 ¼540 K4 ¼ 1380

[Pa(NO3)6]– [Pa(NO3)7]2– [Pa(OH)2(NO3)]2þ [Pa(OH)2(NO3)2]þ [Pa(OH)2(NO3)3]0 [Pa(OH)2(NO3)4]–

(PaNO3)4þ [Pa(NO3)2]3þ [Pa(NO3)5]0

K1 ¼ 0.68

[PaOx(OH)4–2xNO3]

1

1

Stability constants

Suggested species

Stability constants for some suggested nitrate complexes of Pa(V).

[NO 3 ] (M)

Table 4.15

Only the ratio [Pa]:[NO 3 ] was determined.

1

1

a

[H ] (M)



þ

Spitsyn et al. (1964); Khlebnikov et al. (1966)

Stanik and Ilmenkova (1963)

Kolarich et al. (1967)

Nowikow and Pfrepper (1963)a

References

Solution chemistry

215

Table 4.16 Suggested chloro complexes of Pa(V) as a function of HCl concentration (after Guillaumont et al., 1968). [HCl ] (M)

PaðOHÞn Clm5nm

1 2 3

PaOOH2þ PaOOHClþ PaO2 Cl 2

4

PaOþ 3

5 6 7 8 >8

PaOCl 4 PaOHCl2 6 PaCl 6 PaCl2 7 PaCl3 8 or POHCl3 7 Scherff and Herrman (1966)

References

PaOOH2þ PaOOHClþ PaOOHCl2 PaOCl3 POOHCl 3 PaOCl 4 PaOCl2 5

PaOCl3 6 Guillaumont (1966c); Muxart et al. (1966a,b)

PaðOHÞClþ 3 Pa(OH)2Cl3 PaðOHÞCl4 PaðOHÞ2 Cl 4 PaðOHÞCl 5 PaCl 6 PaCl2 7 Casey and Maddock (1959a,b)

PaðOHÞClþ 3 Pa(OH)3Clþ PaðOHÞ2 Clþ 2 Pa(OH)2Cl3 Pa(OH)Cl4 PaðOHÞ2 Cl 4 PaðOHÞCl 5 PaCl 6

Shankar et al. (1963)

deMiranda, 1966; Guillaumont, 1966a,c; Guillaumont and deMiranda, 1966; Guillot, 1966; Kolarich et al., 1967; Bonnet and Guillaumont, 1969; Plaisance and Guillaumont, 1969); their regions of existence are summarized in Fig. 4.17. Those for which stability constants have been determined are listed in Table 4.17. Only two species exist in a pure state: PaF2 7 , which is present over the range 10–3 M < [HF] < 4–8 M, and PaF3 , which can exist only when 8 [F–] > 0.5 M and 10–7 M < [Hþ]< 10–2 M. In more acid media, 1 M < [Hþ] < 3 M and [F–] 10–4 M, the dominant heptafluoro complex is HPaF 7 ; this species would also exist in 10–12 M HF, because the [F–] is limited to about 10–2 M by the equilibrium constants: K1 ¼ ([HF]/([Hþ] [F–])) ¼ 935 M–1 and K2 ¼ ([HF2]/ ([HF] [F–])) ¼ 3.12 M–1 (Plaisance and Guillaumont, 1969). At [HF] < 10–3 M, PaF2 7 is replaced by complexes of successively lower F:Pa ratios, then by oxo and hydroxyfluoro complexes and, finally, by uncomplexed species.

(d)

Behavior of Pa(V) in sulfuric acid solution

Freshly precipitated Pa(V) hydroxide is readily soluble in moderately concentrated H2SO4 and permanently stable solutions, containing up to 90 g L–1 of 231 Pa in approximately 2.5 M H2SO4, have been reported (Thompson, 1952; Kirby, 1959, 1966; Brown et al., 1961; Campbell, 1964; Bagnall et al., 1965; Takagi and Shimojima, 1965; Kirby and Figgins, 1966). The solubility falls off sharply at both ends of the acid concentration range, yielding amorphous hydrated oxides or colloids in U > Np > Pu owing to decreasing ionic size and increasing actinide–oxygen bond strength. The solubilities of U(V) and U(IV) are also affected by alkali content due to variation in bond strength. Uranium(IV) and U(V) are generally incompatible with magmatic systems and tend to partition strongly into late stage formed minerals, such as zircon, titanite, or apatite. Farges et al. (1992) suggest that if melts have a heterogeneous distribution of bonding oxygens (BO) and NBO, uranium will become enriched in the NBO‐enriched regions. With increasing magmatic differentiation,15 the BO content of the melt increases, as a consequence U(IV) will partition to late crystallizing minerals, such as pyrochlore or zircon. Farges et al. (1992) determined the U–O bond lengths in U(VI)‐containing ˚ and U–Oeq 2.18–2.25 A ˚ , characteristic silicate glasses as U–Oax 1.77–1.85 A Oxygen bonded to one Si4+ and an indeterminate number of other cations (Ellison et al., 1994). Oxygen bonded exclusively to cations other than Si4+. 15 The process of chemical and mechanical evolution of a magma in the course of its crystallization such that different rock types are formed from the same original magma. 13 14

Occurrence in nature

277

of the uranyl species. U(VI) is the dominant oxidation state observed in radioactive borosilicate waste glasses. XPS measurements performed on SON68‐type borosilicate waste glass by Ollier et al. (2003) revealed two oxidation states in the glass: about 20% U(IV) and 80% U(VI) present in two different environments, uranate‐ and uranyl‐sites, respectively. As a consequence of bond strength considerations, U(VI) also bonds primarily to NBO and NFO in both crystalline and amorphous silicates. U(V) is six‐coordinated with a mean U–O ˚ (Farges et al., 1992). bond distance of 2.19–2.24 A Karabulut et al. (2000) have investigated the local structure of uranium in a series of iron phosphate glasses with EXAFS and determined that the all uranium was present as U(IV). (d)

Uranium niobates, tantalates, and titanates

There are a number of complex tantalum, niobium, and titanium oxides that may contain uranium as an essential element. These phases are mainly observed in granitic rocks and granite pegmatites16 and have been difficult to characterize as they commonly occur in the aperiodic metamict state owing to their age and radionuclide content. A common feature of these minerals is that niobium, tantalum, and titanium atoms occupy octahedral sites, and a structural framework that is formed by octahedral corner or edge sharing (Finch and Murakami, 1999). The structures of the ixiolite, samarskite, and columbite groups, ideally A3þB5þO4, are all derivatives of the a‐PbO2 structure. Ishikawaite {(U4þ,Fe, Y,Ce)(Nb,Ta)O4} is the U‐rich variety of samarskite and calciosamarskite is the Ca‐rich variety. Because these minerals are chemically complex, metamict, and pervasively altered, their crystal chemistry and structure are poorly understood (Hanson et al., 1999). Many of these phases are of interest because of their occurrence in designer crystalline ceramic waste forms for immobilization of actinides (Giere´ et al., 1998; Ewing, 1999). In particular, zirconolites, pyrochlores, and brannerites have been proposed for immobilizing transuranics. These phases will be discussed in more detail. (i) Zirconolite Zirconolite is an accessory mineral crystallizing under different geological conditions and in a wide range of generally SiO2‐poor rock types (Giere´ et al., 1998). Zirconolite has been found in mesostasis areas of ultrabasic cumulates, in granitic pegmatites, in carbonatites,17 in nepheline syenites, and in other igneous formations. Zirconolite has been observed commonly in lunar late‐stage

16 17

Late stage crystallization from an igneous intrusion. Rock consisting of >50% carbonate minerals.

Uranium

278

mesostasis areas of lunar basalts.18 It is also a common constituent of designer titanate ceramic waste forms (Giere´ et al., 1998; Ewing, 1999). Natural zirconolite is a reddish‐brown mineral with an appearance similar to that of ilmenite; however, the grains are typically anhedral and 10–2.2 atm, rutherfordine becomes the stable uranium phase with respect to dehydrated schoepite; however, the schoepite– rutherfordine equilibrium indicates that pCO2 must be >10–1.9 atm before schoepite becomes unstable with respect to rutherfordine. Schoepite is thus expected

290

Uranium

to be the U‐solubility‐controlling phase in waters exposed to atmospheric conditions. Rutherfordine would be expected to replace schoepite in environments where the pCO2 pressure is higher, possibly in a repository environment or in saturated soils. Replacement of schoepite by rutherfordine has been observed at the Shinkolobwe U‐deposit (Finch and Ewing, 1992). The structure of rutherfordine was elucidated by Finch et al. (1999b) and can be represented by an anion topology that consists of edge‐sharing hexagons that share corners, creating pairs of edge‐sharing triangles. The rutherfordine sheet is obtained by populating all the hexagons in the anion topology with uranyl ions and one half of the triangles are populated with CO3 groups. The sheets are held together via van der Waals forces. An identical sheet structure occurs in synthetic (UO2)(SeO3). Burns and Finch (1999) reported the structure of a mixed uranium valence mineral, wyartite that contains U(V) and U(VI). The structure of wyartite contains three symmetrically distinct U positions. The U1 and U2 cations are each ˚ , consistent strongly bonded to two O atoms with U–O bond lengths of 1.8 A with a linear uranyl ion, whereas the U3 site has seven anions at the corners of a ˚ . A bond pentagonal bipyramid, with U–O bond lengths of 2.07 and 2.09 A valence analysis showed that the U3 site is coordinated by six O atoms and one H2O group. Two of the O atoms of the bipyramid are shared with a CO3 group and the sum of bond valences incident at the U3 site is 5.07, in agreement with the assignment of U(V) in this site. Urancalcarite is structurally similar to wyartite and commonly associated with wyartite in nature. Finch and Murakami (1999) suggest that wyartite may oxidize to uranocalcarite. Schindler and coworkers (Schindler and Hawthorne, 2004; Schindler et al., 2004) proposed the formation of the mixed U(V)–U(VI) mineral, wyartite II, on surface of calcite during interaction of acidic and basic uranyl‐bearing solutions with calcite. The structure of fontanite, {Ca[(UO2)3(CO3)2O2](H2O)6, has been refined by Hughes and Burns (2003) as a monoclinic phase that consists of two symmetrically distinct Urf5 units, one Urf6 unit, and two CO3 triangles. It is observed in the weathered zone of the Rabejac uranium deposit in Lode`ve, He´rault, France, where it is associated with billietite and uranophane. Both fontanite and roubaultite possess anion topologies similar to phosphuranylite {KCa(H3O)3(UO2) [(UO2)3(PO4)2O2]2(H2O)8}. Several uranyl carbonates that contain lanthanides have been described. Bijvoetite is found in association with uraninite, sklodowskite, and uranophane in the oxidized zone at the Shinkolobwe mine (Li et al., 2000). The structure of bijvoetite is extremely complex and contains 16 unique carbonate groups, 39 symmetrically distinct H2O groups, and 8 unique M3þ sites that are occupied by variable amounts of yttrium, dysprosium, and other lanthanides. Astrocyanite {Cu2(Ce,Nd,La)2UO2(CO3)5(OH)2 · 1.5H2O}, is another rare earth‐bearing uranyl carbonate that is observed as an oxidation product of uraninite. These complex rare earth uranyl carbonates may play an important role in the long‐term behavior of released transuranic elements following corrosion of nuclear materials in a geologic repository.

Occurrence in nature

291

The occurrence of trace amounts of uranyl ions in natural calcite has posed a long‐standing problem in crystal chemistry because of speculation that the size and shape of the uranyl ion may preclude its incorporation in a stable lattice position in calcite. The incorporation of uranium in calcite and aragonite provides the basis for U‐series age‐dating which are commonly adopted for marine and terrestrial carbonates. Uranium is enriched in aragonite relative to calcite owing to the nature of the coordination environment in U‐bearing aragonite. Reeder et al. (2000) have demonstrated using EXAFS that the dominant aqueous species UO2 ðCO3 Þ4 3 is retained by the uranyl in aragonite, essentially intact. In contrast, a different equatorial coordination occurs in calcite, characterized by fewer nearest oxygens at a closer distance, reflecting that the CO3 groups are monodentate. The uranyl ion has a more stable and well‐defined local environment when co‐precipitated with aragonite; however, Reeder et al. (2000) argue that as aragonite is metastable with respect to calcite, retention of U(VI) by calcite is likely to be temporary. In contrast, Kelly et al. (2003) examined a 13 700‐year‐old U‐rich calcite from a speleothem in northernmost Italy. X‐ray absorption spectroscopy data indicated substitution of U(VI) for a Ca2þ and two adjacent CO2 3 ions in calcite. This data implied that uranyl has a stable lattice position in natural calcite and suggested that uranium may become incorporated in calcite over long time scales. Sturchio et al. (1998) reported the occurrence of U4þ in calcite based on XANES core spectroscopic analysis and concluded that this explained the anomalously high concentrations of uranium observed in calcite in reducing environments. Substitution of Ca2þ by Naþ was suggested as a possible mechanism to charge balance the structure. The calculated U–O distances reported by ˚ and (2.78 0.03) A ˚ for U4þ in calcite, Sturchio et al. (1998) were (2.21 0.02) A ˚ and U–Oax as 1.80 A ˚. whereas Reeder et al. (2001) estimated U–Oeq to be 2.33 A Interestingly, Sturchio et al. (1998) showed a good match of their measured U–O bond lengths with a natural brannerite, where U–O bond lengths were ˚ . However, natural brannerite minerals have recently reported as 2.28 and 2.82 A been shown to be U(V) phases (Finnie et al., 2003; Colella et al., 2005). (h)

Uranyl sulfates

Uranyl sulfates are important in systems where sulfides (e.g. pyrite) are being oxidized. Initial oxidation causes an increase in acidity of the system; however, the acidity may be buffered by the dissolution of carbonate in the surrounding rock, leading to the formation of gypsum. Uranyl sulfates usually occur where uranyl carbonates are absent (and vice versa), owing to the different pH conditions where these minerals will dominate. Uranyl sulfate minerals typically occur as microcrystalline crusts, finely intergrown with other uranyl sulfates and/or monocarbonates. They are common at uranium mines where they form during evaporation of acid sulfate‐rich mine drainage waters. Burns (2001a) and Burns et al. (2003) have performed structural refinements on a number of monoclinic zippeite‐group U(VI) phases, including zippeite

Uranium

292

{K3(H2O)3[(UO2)4(SO4)2O3(OH)]}, sodium‐zippeite {Na5(H2O)12[(UO2)8 (SO4)4O5(OH)3]}, Mg‐zippeite {Mg(H2O)3.5[(UO2)2(SO4)O2]}, Zn‐zippeite {Zn(H2O)3.5[(UO2)2(SO4)O2]}, and Co‐zippeite {Co(H2O)3.5[(UO2)2(SO4)O2]. Each structure contains the zippeite‐type layers that consist of chains of edge‐ sharing Urf5 units that are cross‐linked by vertex sharing with sulfate tetrahedra. Marecottite, {Mg3(H2O)18[(UO2)4O3(OH)(SO4)2]2(H2O)10}, is based on uranyl layers composed of chains of edge‐sharing Urf5 biyramids that are linked by vertex‐sharing sulfate tetrahedra, identical to zippeite (Brugger et al., 2003). Marecottite and zippeite can co‐exist as has been observed in samples from the Ja´chymov mine in the Czech Republic. Uranopilite is the only known uranyl sulfate mineral to form chains. The structure consists of clusters of six distinct Urf5 bipyramids that are linked together into a chain by sulfate tetrahedra bonded to two oxygens from each cluster. Adjacent chains are only hydrogen‐bonded (Burns, 2001a). (i)

Uranyl silicates

Because of the ubiquity of dissolved silica in most groundwaters, uranyl silicates are the most abundant U(VI) minerals. The uranyl silicates are divided into three groups based on their U:Si ratios (Stohl and Smith, 1981). Accordingly, the structural trends in the uranyl silicates are also dependent on the U:Si ratio (Stohl and Smith, 1981; Finch and Murakami, 1999; Burns, 2001b). In phases with the U:Si ratio of 2:1 and 1:1, no polymerization of the SiO4 tetrahedra occurs, whereas phases with 1:3 ratios contain chains of vertex‐sharing silica tetrahedra. As the U:Si ratio approaches 1:4, the structures contain sheets of SiO4 tetrahedra. In soddyite, with a ratio of 2:1, each silica tetrahedron shares two of its edges with other uranyl polyhedra, but in structures with the ratio 1:1, only one edge of each silica tetrahedron is shared with a second uranyl polyhedron and each silica tetrahedron is linked to other uranyl polyhedra by vertex sharing. Uranophane is one of the most common uranyl minerals, and its ubiquity suggests that the uranyl silicates are important phases controlling uranium concentrations in groundwater (Finch and Ewing, 1992). a‐Uranophane and b‐uranophane have distinctly different crystallographic data and stabilities. Differences in stability were amply illustrated in the study by Cesbron et al. (1993) where they failed to synthesize b‐uranophane whereas a‐uranophane was produced. Both calcium uranyl silicates are common in most oxidized uranium deposits. The 1:3 silicates (weeksite and haiweeite) are only known from Si‐rich environments such as tuffaceous rocks but are commonly observed during the laboratory weathering of borosilicate waste glasses (Ebert et al., 1991; Feng et al., 1994). The structure of weeksite, originally described by Outebridge et al. (1960), has been refined by Jackson and Burns (2001). Haiweeite, named for the Haiwee reservoir, California, USA, has been identified at the Nopal I deposit in Pen˜a Blanca, Mexico, where it is associated with uranophane. The structure of weeksite consists of chains of edge‐sharing Urf5 pentagonal bipyramids that share edges with SiO4 tetrahedra. The chains are linked through

Occurrence in nature

293

disordered SiO4 tetrahedra to form complex sheets, which in turn form a framework through linkage with SiO4 tetrahedra (Burns, 1999b). The only known thorium uranyl silicate mineral, coutinhoite, has been described by Atencio et al. (2004) as being isostructural with weeksite. The open channels created by the silicate framework structure are thought to permit the incorporation of Th4þ. Oursinite, {(Co0.86Mg0.10Ni0.04) · O2 · UO2 · 2SiO2 · 6H2O}, was first reported by Deliens and Piret (1983b) from Shinklolobwe. The phase formed from the oxidation of Co‐ and Ni‐bearing sulfides and demonstrates the ability for U(VI) phases to incorporate a range of elements. Lepersonnite, {CaO(Gd,Dy)2O3 · 24UO3 · 8CO2 · 4SiO2 · 60H2O}, is a pale yellow uranyl silicate from the Shinkolobwe mine that was first described by Deliens and Piret (1982). The reported compositions of oursinite, lepersonnite, and coutinhoite have immediate implications for radioactive waste disposal for the possible retention of radionuclides, including plutonium, in the environment. Soddyite is the only known mineral with a U:Si ratio of 2:1; it is also the most common of the uranyl minerals that have structures based on frameworks of polyhedra of higher valence. The structure of soddyite consists of Urf5 units that share equatorial edges to form chains. The chains are cross‐linked by sharing edges with SiO4 tetrahedra in such a way that each tetrahedron shares two of its edges with adjacent chains (Burns, 1999b). Based on observations at the Nopal I site, Pearcy et al. (1994) suggested that the precipitation of soddyite may be kinetically more favorable than the formation of other U6þ silicates. Soddyite may form from uranophane exposed to dilute metoric waters that are low in carbonate and with a pH below 7. Uranosilite, {(Mg,Ca)4 (UO2)4(Si2O5)5.5(OH)5 · 13H2O}, has only been reported in nature at a site in Menzenschwand, Germany (Walenta, 1983). Burns et al. (2000) reported the occurrence of a new U(VI) silicate from the corrosion of a borosilicate glass with formula {KNa3(UO2)2(Si4O10)2(H2O)4}, with a U:Si ratio of 1:4. This phase was demonstrated to be structurally distinct from the phase synthesized by Plesko et al. (1992). Burns and co‐authors suggested that this novel U(VI) silicate may incorporate Np(V). (j)

Uranyl phosphates and arsenates

Uranyl phosphates and arsenates constitute about one‐third of the 200 described uranium minerals (see Table 5.3); yet only a fraction of these have 2 well‐defined structures. In groundwaters where logf½PO3 4 T =½CO3 T g > 3:5, uranyl phosphate complexes dominate over uranyl carbonate complexes (Sandino and Bruno, 1992). Finch and Ewing (1992) suggested that the occurrence of uranyl phosphates in the most weathered zones of the Koongarra U‐deposit indicated that higher oxidation potentials may be necessary for uranyl phosphate precipitation, as uranyl silicates were observed at depth. However, sale´eite (Mg(UO2)2(PO4)2 · 10H2O) was observed on the surface of apatite where the groundwater was undersaturated with respect to sale´eite, indicating that the mineralization occurred by local saturation (Murakami et al., 1997).

Uranium

294

Laboratory studies have demonstrated that surface mineralization of sale´eite on fluoro‐apatite where localized release of Ca and P facilitates autunite formation and U6þ uptake (Ohnuki et al., 2004). Uranyl arsenates are often structurally analogous to the corresponding uranyl phosphates; e.g. the isostructural mineral species abernathyite, {K[(UO2) (AsO4)](H2O)3}, and meta‐ankoleite, {K[(UO2)(PO4)](H2O)3}. Many of the natural uranyl phosphates and arsenates may exhibit complete solid solution formation between end‐members. However, in hu¨gelite, {Pb2[(UO2)3 O2(AsO4)2](H2O)5}, the presence of arsenic makes the unit cell four times larger than that reported for dumontite, {Pb2[(UO2)3(PO4)2(OH)4](H2O)5} (Locock and Burns, 2003b). Both structures possess the phospuranylite anion topology. In hu¨gelite, the interlayer contains four symmetrically distinct Pb2þ cations. Unlike the lead uranyl oxyhydroxides, hu¨gelite contains only Urf5 and Urf6 polyhedra; yet, it possesses a high U:Pb ratio. Uranyl arsenates and phosphates may be divided into groups depending on the U:P or U:As ratio. However, a structural classification is more encompassing. The uranium phosphates and arsenates can be separated into four groups: (i) autunite structure; (ii) 3:2 phosphuranylite structure; (iii) uranophane structure; and (iv) chain structures. (i)

Autunite structures

The most important uranyl phosphates in terms of natural abundance are the autunites and meta‐autunite groups. The autunite group of minerals is tetragonal uranyl arsenates and phosphates. The group possesses the general formula M(UO2)2(XO4)2 · 8–12H2O where M may be Ba, Ca, Cu, Fe2þ, Mg, Mn2þ or 1 2(HAl) and X is As or P. Takano (1961) obtained unit cell parameters for an ˚ and c ¼ 20.63 A ˚ ). autunite specimen from Ningyo Pass, Japan (a ¼ 6.989 A These were virtually identical to those obtained by Locock and Burns (2003a) on a synthetic autunite. The Pb uranyl oxide hydrate, curite is commonly associated with uranium phosphates such as autunite, torbernite, and parsonsite (Vochten and Deliens, 1980). Finch and Ewing (1992) suggested that the (010) face of curite consists of ðUO2 Þ  OHþ 2 surface species that may provide a reactive pathway for attachment of (HPO4)2– groups, forming (UO2)‐ OPO3‐H3O0. This species, once deprotonated, would have the equivalent stoichiometry of chernikovite. Heinrichite {Ba[(UO2)(AsO4)]2(H2O)10} was originally assumed by Gross et al. (1958) to be tetragonal, despite the observation of biaxial optical properties. Locock et al. (2005b) have refined the structures of several of the barium‐bearing phases that possess the autunite sheet structure, including heinrichite and meta‐uranocircite {Ba[(UO2)(PO4)]2(H2O)7} type I and II. There is only the loss of one H2O group and a slight decrease in ˚ to d020 ¼ 8.43 A ˚ from going from the interlayer spacing, from d020 ¼ 8.82 A meat‐uranocircite I to II; however, there is a significant re‐arrangement in the Ba atomic positions. Table 5.3 lists new refinements from Locock et al. (2005b) for these autunite structures; however, because of the difficulties in obtaining

Occurrence in nature

295

suitable natural specimens, some are based synthetic phases and predictions. These have been listed owing to the apparent inconsistencies in earlier published data. Locock et al. (2005c) have published a refinement of uranospathite {Al1‐x□x[(UO2)(PO4)]2(H2O)20þ3x F1‐3x} with 0 < x < 0.33 and confirmed the presence of fluorine, the absence of H3Oþ, and a higher Al content in the structure; the empty square in the formula indicates a vacancy. Locock et al. (2005c) have described uranospathite as the ‘‘Dogwood sandwich’’ of the ˚ , possessing 21 H2O autunite group with an interlayer spacing, d200 of 15.01A groups per formula unit (pfu). The discovery that uranospathite and other aluminum uranyl phosphates possess a number of different hydration states has called into question the traditional division of these minerals into autunite and meta‐ autunite sub‐groups based on the 10‐12 H2O pfu and 6‐8 H2O pfu, respectively. (ii)

Phosphuranylite structures

The phosphuranylite group consists of mainly orthorhombic phases with structure sheets of the composition [(UO2)3(O,OH)2(PO4)2]. Phosphuranylite is remarkable because it contains all three types of Ur polyhedra. The Urf5 and Urf6 occur in the uranyl sheet and the Urf4 occur in the interlayer (Burns, 1999a). It is one of the few minerals with uranium in an interlayer position. Torbernite and meta‐torbernite are hydrous copper uranium phosphates, the only difference between the two being the number of water molecules present; the length of the c‐axis depends on the water content. The structure of monoclinic bergenite, the barium phosphuranylite phase {Ca2Ba4[(UO2)3O2(PO4)2]3 (H2O)16}, has been refined by Locock and Burns (2003c). (iii)

Uranophane structures

The uranophane structure type occurs in only a few uranium phosphates and arsenates. Ulrichtite, Cu[Ca(H2O)2(UO2)(PO4)2](H2O)2, and the mixed valence arsenite–arsenate uranyl mineral, Se´elite, {Mg(UO2)(AsO3)0.7(AsO4)0.3 · 7H2O}. The name ulrichite was once used as a term for pitchblende; however, the structure of this Ca–Cu2þ mineral has now been refined by Kolitsch and Giester (2001).20 The structure consists of elongated CuO6 octahedra that are corner linked by two PO4 octahedra, edge‐ and corner‐sharing Urf5, CaO8, and PO4 polyhedra. These form heteropolyhedral sheets parallel to (001) that are linked by the elongated CuO6 octahedra. (iv) Chain structures Chain structures occur in walpurgite, orthowalpurgite, phosphowalpurgite, hallimondite, and parsonsite. Burns (2000) solved the structure of parsonsite Problems with the ulrichite structure as described by Birch et al. (1988) were recognized by Burns (1999a).

20

296

Uranium

Fig. 5.3 Parsonsite, the chain uranyl phosphate phase (adapted from Locock and Burns, 2003).

and found that it was composed of uranyl phosphate chains rather than sheets as observed in the autunite and phosphuranylite minerals. The structure consists of Urf5 polyhedra edge‐sharing dimers that are cross‐linked with two distinct phosphate tetrahedra by edge‐ and vertex‐ sharing. Two symmetrically distinct Pb2þ cations link the uranyl phosphate chains (see Fig. 5.3). One of the Pb positions, Pb(1) is coordinated by 9 oxygen atoms, with Pb–O ˚ . Pb(2) is coordinated by 6 oxygens bond lengths ranging from 2.35 to 3.16 A with a distinctly one‐sided polyhedral geometry owing to the presence of a lone pair of electrons on the Pb cation. The Pb(2)–O bond lengths range from 2.28 to ˚ . Common to other uranium phases, the lone pair distortion may be 3.15 A responsible for the formation of chains rather than sheets. Based on structural refinements and infrared spectroscopy, Locock et al. (2005a) have shown that parsonsite does not contain any structural water. In most uranyl phosphates and arsenates, water occurs as a hydrate H2O, either coordinating interlayer cations, or occurring as interstitial H2O groups. Although Locock et al. (2005a) detected water in hallimondite, this was determined not to be critical to structural integrity. (v)

Synthetic uranyl phosphates and arsenates

Synthetic varieties have also revealed structural differences between phosphate and arsenate uranyl phases that contain the large alkali cations cesium and rubidium. These phosphate and arsenate phases are not isostructural. For

Occurrence in nature

297

example, cesium uranyl arsenates are not isostructural with cesium uranyl phosphates, but show a homeotypic framework with identical coordination geometries and polyhedral connectivity. The presence of arsenic expands the framework relative to phosphorus and so the cesium uranyl arsenate has a unit‐cell volume 7% greater than the corresponding phosphate. (vi) Uranium(VI) phosphates in the environment Because of their low solubilities, phosphate and arsenate minerals are of considerable environmental importance for understanding the mobility of uranium in natural systems and they may control the concentration of uranium in many groundwaters. In alkaline environments, dewindite {Pb (UO2)3(PO4)2(OH)2 · 3H2O} is stable at low lead concentrations; whereas dumontite is the stable phase in Pb‐rich environments. In acid environments, parsonsite is prevalent at high lead levels and przhevalskite {Pb2(UO2)3 (PO4)2(OH)4 · 3H2O} occurs under low lead concentrations (Nriagu, 1984). Jerden and Sinha (2003) examined the long‐term sequestration of uranium by U(VI) phosphate mineral precipitation at the Coles Hill uranium deposit in Virginia, USA where uranium is released by the oxidation and chemical weathering of an apatite‐rich, coffinite–uraninite orebody. Meta‐autunite was observed by Buck et al. (1996) and Morris et al. (1996) in contaminated soils from a former uranium processing plant at Fernald, Ohio, USA. Significant uraniferous phosphorite deposits occur in Tertiary sediments in Florida, Georgia, and North and South Carolina and in the Hahotoe´‐Kpogame´ U‐deposits in Togo, West Africa (Gnandi and Tobschall, 2003). The Florida Phosphorite Uranium Province has yielded large quantities of uranium as a by‐product of the production of phosphoric acid fertilizer (Finch, 1996). The discovery that bacteria can reduce U(VI), which appears to precipitate as uraninite, has led to the concept of in situ bioremediation of U‐contaminated groundwater; however, another possible microbial process for uranium immobilization is the precipitation of U‐phosphates. Macaskie et al. (2000) have demonstrated that Citrobacter sp. will bioprecipitate uranyl phosphate with exocellularly produced phosphatase enzyme. In a similar study by Basnakova et al. (1998) a nickel uranyl phosphate was observed in experiments with Citrobacter sp. (k)

Uranyl vanadates

Uranyl vanadates comprise some of the most insoluble uranyl minerals, forming whenever dissolved uranium comes in contact with dissolved vanadate anions. The K‐bearing uranyl vanadate, carnotite, is possibly the most important source of secondary (U6þ) uranium ore minerals, providing 90% of the uranium production from secondary deposits. It is a lemon‐yellow mineral with an earthy luster, a yellow streak, and a specific gravity of about 4. It occurs most commonly in soft, powdery aggregates of finely crystalline material or in thin films or stains on rocks or other minerals. The most noted occurrences of

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carnotite are in the Colorado Plateau (Zhao and Ewing, 2000), on the western edge of the Black Hills, South Dakota, USA, and in the Ferghana basin in Kyrgyzstan. It occurs in sandstones in flat‐lying, irregular, partially bedded ore bodies. If present in sufficient quantity, carnotite will color the rock bright yellow; but in poorer deposits, particularly below 0.20 percent U3O8, it may be difficult to distinguish the uranium mineral from the sandstone itself. Using solid state reactions, Dion et al. (2000) synthesized two new alkali uranyl vanadates, M6(UO2)5(VO4)2O5 with M ¼ Na, K, by and determined their structures from single‐crystal XRD. Both structures consisted of [(UO2)5(VO4)2O5]6 corrugated layers parallel to the (100) plane. The layers contained VO4 tetrahedra, Urf5 pentagonal bipyramids, and distorted Urf4 octahedra. The Urf5 units were linked by sharing opposite equatorial edges to form zigzag infinite chains parallel to the c‐axis. These chains were linked together on one side by VO4 tetrahedra and on other side by Urf4 and Urf5 corner‐sharing units. (l)

Uranyl selenites and tellurites

In nature, uranyl selenite minerals form where Se‐bearing sulfides are undergoing oxidative dissolution. Selenium occurs as Se(IV), in the selenite anion, SeO2 3 , however, Finch and Murakami (1999) suggested that Se(VI) minerals may be expected under sufficiently oxidizing conditions. Natural uranyl selenites and tellurites include the minerals derriksite, demesmaekerite, guilleminite, larisaite {Na(H3O)(UO2)3(SeO3)2O2 · 4H2O} (Chukanov et al., 2004), and marthozite, {Cu[(UO2)3(SeO3)2O2](H2O)8}. The three known uranyl tellurites are cliffordite {UO2(Te3O7)}, moctezumite {PbUO2(TeO3)2}, and schmitterite {UO2(TeO3)}. The selenites and tellurites are based upon infinite chains of polymerized polyhedra of higher valence. The chain structures observed with moctezumite and derriksite contains Urf5 and Urf4 bipyramids as well as Te4þO3 and Se4þO3 triangles. They are strongly distorted owing to the presence of a lone pair of electrons on the cation. The crystal structure of marthozite has been refined by Cooper and Hawthorne (2001). There are two unique selenium sites, each occupied by Se4þ and coordinated by three O atoms, forming a triangular pyramid with Se at the apex, indicative of the presence of a stereo‐ ˚ . The structure possesses one active lone pair. The Se–O bond length is 1.70 A Cu site coordinated by 4 H2O groups and two O atoms. The structural unit is a sheet of composition [(UO2)3(SeO3)2O2], which is topologically identical to the structural unit in guilleminite {Ba[(UO2)3(SeO3)2O2](H2O)3}. Adjacent sheets are linked through interstitial Cu2þ cations via Cu2þ‐O bonds and via H‐bonds that involve both (H2O) groups bonded to Cu2þ and interstitial (H2O) groups. A number of uranyl selenites containing alkaline metals (Almond et al., 2002), as well as Ag and Pb (Almond and Albrecht‐Schmitt, 2002) have been prepared. The structures consist of [(UO2)(SeO3)2]2– sheets constructed from Urf5 units that are linked by SeO2 3 anions, similar to the natural minerals. Synthetic Sr[(UO2)3(SeO3)2O2] 4H2O prepared in supercritical water was

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found to possess the same anion topology as is found in guilleminite and marthozite; however, this phase could not be prepared under ambient or hydrothermal conditions (Almond and Albrecht‐Schmitt, 2004). (m)

Uranyl molybdates

Uranyl molybdates are common minerals formed by weathering of uraninite and Mo‐bearing minerals (Finch and Murakami, 1999). Umohoite {[(UO2) (MoO2)](H2O)4}, is commonly partially replaced by iriginite {[(UO2) (MoO3OH)2(H2O)](H2O)}, which also consists of polyhedra sheets. Iriginite, however, has a distinctive anion‐topology arrangement of chains of pentagons and squares that share edges, and zigzag chains of edge sharing squares and triangles (Krivovichev and Burns, 2000a). In the structure of iriginite, each pentagon of the anion topology is populated by an Urf5 polyhedron, two‐thirds of the squares are populated with Mo6þO6 octahedra that occur as edge‐sharing dimers; the triangles, as well as one‐third of the squares, are empty. There have been reports of substantial variability of the c dimension of umohoite possibly due to variation of the H2O content or polytypism that may account for the observed variation in unit‐cell parameters (Krivovichev and Burns, 2000b). The sheets of uranyl and molybdate polyhedra in iriginite and umohoite have features in common. The umohoite to iriginite transformation during alteration of U–Mo deposits, corresponding to a change of the U:Mo ratio from 1:1 to 1:2, involves a change of anion topology to one with a smaller number of edges shared between coordination polyhedra. The uranophane anion‐topology is the basis of the umohoite sheet. Construction of the anion topology requires the U and D arrowhead chains as well as the R chain, with the chain‐stacking sequence URDRURDR... The iriginite anion‐topology contains the same chains as the umohoite (uranophane) anion‐topology, but the chain‐stacking sequence is DRRRURRRDRRRURRR... The ratio of arrowhead (U and D) chains to R chains in the umohoite and iriginite anion topologies is 1:1 and 1:3, respectively. In the umohoite sheet, all rhombs of the R chains are populated with Mo6þ cations, whereas in the iriginite sheet, only two‐thirds of the rhombs contain Mo6þ, with the remaining third empty. The result is U:Mo ratios of 1:1 and 1:2 in the umohoite and iriginite sheets, respectively. The iriginite anion‐ topology may be derived from that of umohoite by expansion of the umohoite anion‐topology along a vector within the sheet that is perpendicular to the arrowhead chain, together with the insertion of two additional R chains between adjacent arrowhead chains. This transformation mechanism requires addition of Mo6þ to populate the rhombs of the R chains. Another mechanism for obtaining the iriginite anion‐topology from that of umohoite is the replacement of every second URD sequence in the umohoite anion‐topology with an R chain. This mechanism requires the removal of the U6þ that populated the D and U arrowhead chains. Krivovichev and Burns (2000a,b) have suggested that this may appear to be the most likely mechanism of the umohoite‐to‐iriginite transformation (see Fig. 5.4).

Fig. 5.4 Diagram showing a possible mechanism for the umohoite to iriginite transformation (adapted from Krivovichev and Burns, 2000a,b). The iriginite structure can be obtained from umohoite through the replacement of every second URD sequence in the unmohoite anion topology with an R chain. This mechanism requires removal of the U6þ that occupied the D and U arrowhead chains.

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Mourite {U4þMo6þ5O12(OH)10}, is a rare U4þ mineral containing molybdenum that is observed in oxidized zones in association with umohoite occurring as dark violet crusts and scaly aggregates in the Kyzylsai uranium deposit in Kazakhstan associated with umohoite. Krivovichev and Burns (2002a–c, 2003a) have described several synthetic uranyl molybdates, including Rb, Cs, Ag, and Tl species, respectively. (n)

Uranyl tungstates

Only one natural uranium tungstate is known, uranotungstite {(Fe2þ,Ba,Pb) (UO2)2WO4(OH)4(H2O)12}; however, there are a wealth of synthetic U(IV) and U(VI) tungstates that have been reported in the literature. The phase UO2WO4 is isostructural with UO2MoO4, suggesting that the W6þ cations are tetrahedrally coordinated by O atoms. Given the structural similarities of Mo(VI) and W(VI), it might be expected that a variety of U(VI)–W(VI) phases should form. The phases UO2W3O10 and Na2UO2W2O8, has been described but their structures are unknown. U(IV) tungsten bronzes have received considerable attention. The structures consist of ReO3‐type slabs of corner‐sharing W6þO6 octahedra. A number of lithium uranyl tungstates ion conductors, such as Li2(UO2)(WO4)2 and Li2(UO2)4(WO4)4O, have been prepared by high‐temperature solid state reactions (Obbade et al., 2004). (o)

Uranium association with clay minerals and zeolites

Chisholm‐Brause et al. (2001) have identified four distinct uranyl complexes on montmorillonite that co‐exist under certain conditions. Inner sphere and exchange‐site complexes persist over a range of solution conditions. The uranyl ion sorbs onto montmorillonite at low pH via ion exchange, leaving the inner‐ sphere uranyl aquo‐ion structure intact (Dent et al., 1992; Sylwester et al., 2000). At near neutral pH and in the presence of a competing cation, inner‐sphere complexation with the surface predominates. Adsorption of the uranyl onto silica and g‐alumina surfaces appears to occur via an inner‐sphere, bidentate complexation with the surface, with the formation of polynuclear surface complexes occurring at near‐neutral pH (Sylwester et al., 2000). Pabalan et al. (1993) have performed laboratory tests on the sorptive properties of zeolitic materials for uranium; the sorption is strongly dependent on pH. At near neutral pH U(VI) was strongly sorbed but under conditions where carbonate‐ and ternary hydroxyl‐carbonate‐complexes are present the sorption decreased substantially. Della Ventura et al. (2002) have discovered a new lanthanide borosilicate minerals of the hellandite group where uranium appears to be incorporated into a borosilicate cage structure. The phase, called ciprianiite {Ca4[(Th,U)(REE)] Al2(Si4B4O22)(OH,F)2]}, formed with a syenitic ejectum21 collected close at

21

Literally, the violent volcanic explosion of mainly alkali feldspar (syenite) intrusive rock.

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Tre Croci within a pyroclastic formation belonging to the Vico volcanic complex (Latium, Italy). Uvarova et al. (2004) reported another U4þ bearing silicate, arapovite {U(Ca,Na)2(K1–x□x)Si8O20} from the Dara‐i‐Pioz moraine, Tien‐Shan Mountains, Tajikistan. The thorium and uranium uptake from their aqueous solutions by pristine and NaCl‐pretreated zeolite‐bearing volcanoclastic rock samples from Metaxades (Thrace, Greece) has been studied using a batch‐type method (Misaelides et al., 1995). The concentration of the solutions varied between 50 mg L–1 and 20 g L–1. The NaCl pretreatment of the materials improved the thorium, but not the uranium, uptake. The absolute thorium uptake by the pretreated material, determined using neutron activation and X‐ray fluorescence techniques, reached 12.41 mg g–1, whereas the uranium uptake by the raw material was 8.70 mg g–1. The distribution coefficients (Kd) indicated that the relative thorium and uranium uptake is higher for initial concentrations below 250 mg L–1. The zeolitic materials were very stable despite the initial low pH of the solutions used; however, the pH increased significantly with time due to the simultaneous hydrogen‐ion uptake. The thorium and uranium uptake is a complex function of the aqueous chemistry of the elements, the nature of the constituent minerals, and the properties of the zeolitic rock specimens. The various metal species are bound through different sorption processes such as ion‐exchange, adsorption, and surface precipitation. Microporous minerals (zeolites, phyllosilicates) are mainly responsible for the large sorption capacity of the rock samples studied.

5.4

ORE PROCESSING AND SEPARATION

Because of the complexity of many uranium ores and the usual low concentrations of uranium present, the economic recovery of uranium often poses a difficult problem for the chemist. Physical concentration methods (flotation, gravitational, electromagnetic, etc.) have met with only limited success for uranium. The chemical methods used for the recovery of uranium from ores thus have to be designed to treat large ore volumes economically. Because of this and because uranium is a very electropositive metal, most direct pyrochemical methods are not applicable and processes usually involve modern aqueous extractive metallurgy. In this section the more important aspects of the extractive metallurgy of uranium will be described with emphasis on the chemical principles involved. Uranium ores vary in chemical complexity from the relatively simple pitchblendes, which are accompanied by perhaps 10 other minerals, to exceedingly complex and refractory uranium‐bearing titanites, niobates, and tantalates containing rare earths and many other metals. Included are uranium minerals accompanied by major admixtures of ill‐defined organic compounds. Some pitchblende ores may have as many as 40 elements present from which

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uranium must be separated. Many uranium deposits are variable in composition, resulting in an almost daily variation in the composition of the starting materials. Such variations are minimized by stockpiling methods. Nevertheless there have been many ad hoc procedures elaborated to meet special chemical situations. Most such highly specialized methods will have little interest for this discussion. The general features common to most procedures will, however, be pertinent. All methods that have been commonly used comprise the following steps: (1) pre‐concentration of the ore; (2) a leaching operation to extract the uranium into an aqueous phase – this step frequently being preceded by roasting or calcination to improve the extraction; and (3) recovery of the uranium from the pregnant leach liquors by ion exchange, solvent extraction, or direct precipitation, and in the case of ion‐exchange or solvent extraction products by a final precipitation. Special methods may be used for recovery of by‐product uranium. The product of these operations is a high‐grade concentrate, which is usually further purified at a site other than the uranium mill. The extractive metallurgy of uranium has been discussed in detail in various books (Vance and Warner, 1951; Clegg and Foley, 1958; Harrington and Ruehle, 1959; Chervet, 1960; Bellamy and Hill, 1963; Gittus, 1963; Galkin and Sudarikov, 1966; Merritt, 1971) and in collections of papers (United Nations, 1955, 1958, 1964; IAEA, 1966, 1970). There is also a bibliography on feed materials (Young, 1955). The most comprehensive collection of data is the multi‐volume supplement to the Gmelin Handbook of Inorganic Chemistry (Gmelin, 1975–1996), more particularly its volume (A3) on Technology and Uses (Gmelin, 1981a). Many other references can be found in these sources. 5.4.1

Pre‐concentration

Most uranium ores contain only small amounts of uranium, and because leaching is a relatively expensive operation, much effort has been expended to reduce the magnitude of the leaching operation by pre‐concentration of the ore. Physical concentration methods (gravitational, electrostatic, flotation) and various sorting methods have been either used or proposed for upgrading of uranium ores. Unfortunately such beneficiation methods have not achieved great success, only a few of the uranium ores processed being amenable to physical beneficiation processes. Only in a few cases can appreciable concentration of uranium be achieved without excessive loss to tailings. Uranium minerals as well as other minerals, with which they are closely associated, are denser than many gangue materials and successful gravity separation methods are sometimes possible. Such gravity separations are complicated by the fact that uranium minerals tend to concentrate in the fines upon crushing or grinding of some ores. This property has been used to some advantage in that a certain degree of mechanical concentration can be achieved by a gentle grinding followed by screening. Electrostatic methods generally give low recoveries or low concentration factors. Magnetic separation methods have

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generally been used to remove gangue materials such as magnetite, ilmenite, garnet, etc. Flotation methods have received considerable laboratory attention although they do not appear to have been widely applied. Flotation of undesirable gangue materials such as sulfides has met with some success, but no flotation agents have been developed for uranium minerals that give concentration factors approaching those obtained in the processing of sulfide minerals. Flotation has met with some success in splitting carbonate‐containing ores into a carbonate and a non‐carbonate fraction so that the former fraction can be leached by the carbonate method and the other with sulfuric acid. Both manual and mechanical sorting methods have been applied to the upgrading of uranium ores. In this procedure individual lumps of ore are sorted either by hand or by mechanical devices usually on the basis of radiation readings for the individual lumps. Merritt (1971) reviewed various mechanical upgrading techniques in some detail. 5.4.2

Roasting or calcination

It is frequently desirable to subject ores to high‐temperature calcination prior to leaching. Several functions can be performed by such roasting operations. An oxidizing roast can remove carbonaceous material and put the uranium in soluble form. It can oxidize sulfur compounds to avoid subsequent polythionate and sulfur poisoning of ion‐exchange resins. It removes other reductants, which might consume oxidant during the leaching step. Reducing roasts can convert uranium to the reduced state and prevent dissolution of uranium during by‐product recovery. Roasting also improves the characteristics of many ores. Many of them contain clays (particularly of the montmorillonite class), which cause thixotropic slurries and create problems in leaching, settling, and filtering. Dehydration of these clays alters their physical properties and decreases these problems. Roasting with sodium chloride is commonly used with vanadium‐containing ores to convert the vanadium to a soluble form. Sodium vanadate is formed, which is believed to form soluble uranyl vanadates (Merritt, 1971). Salt roasting has also been used to convert silver to silver chloride for easier separation from soluble components. 5.4.3

Leaching or extraction from ores

The object of this procedure is to extract the uranium present in the ore into solution, usually aqueous, from which the recovery and purification of the uranium from accompanying metals can be carried out. The leaching operation is usually the first of the chemical manipulations to which the ore is subjected, and all present chemical processing methods for any type of ore involve digestion of the ore with either acid or alkaline reagents. The acid reagent may be

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generated in situ by bacterial or high‐pressure oxidation of sulfur, sulfides and Fe(II) in the ore to sulfuric acid and ferric [Fe(III)] species. The choice of a reagent for a particular case will be determined primarily by the chemical nature of the uranium compounds present in the ore and the gangue materials that accompany them. The extraction of uranium from the majority of the ores is generally more complete by acid leaching than with alternative leaching procedures and is therefore used in most mills. While other acids can be used, sulfuric acid is employed because of its lower price, except when hydrochloric acid is available as a by‐product of salt roasting. As a general principle only uranium (VI) minerals are readily dissolved in sulfuric acid. For uranium minerals, such as uraninite, pitchblende, and others, containing uranium in lower oxidation states, oxidizing conditions must be provided to ensure complete extraction. Oxidizing conditions are provided by agents such as manganese dioxide, chlorate ion, ferric ion, chlorine, or molecular oxygen. Manganese dioxide and chlorate ion are most commonly used and iron must be present in solution as a catalyst in order for either of them to be effective. Manganese dioxide to the extent of perhaps 5 kg per ton (but typically about one‐half of this in U.S. practice) or up to 1.5 kg NaClO3 per ton of ore are usually adequate for all but the very refractory ores. Free ferric‐ion concentrations larger than 0.5 g L–1 generally give adequate dissolution rates. Sufficient iron is normally provided by the ores themselves and by the ore‐grinding process. Typical dissolution reactions are 2þ UO2 þ 2Fe3þ ! UO2þ 2 þ 2Fe

2Fe2þ þ MnO2 þ 4Hþ ! 2Fe3þ þ Mn2þ þ 2H2 O þ 3þ þ Cl þ 3H2 O 6Fe2þ þ ClO 3 þ 6H ! 6Fe

To avoid excessive consumption of oxidant this is in general not added to the acidified ore until the reaction with free iron and sulfides is practically complete. Manganese can be recovered at later stages as manganese(II) hydroxide followed by ignition in air at 300 C to the dioxide. When only a small fraction of the uranium is in reduced form, agitation with air is often sufficient to maintain oxidation by ferric ion. Various other oxidants are effective, including chlorine, permanganate, bromine, etc., but cost or difficulty of handling (corrosiveness, etc.), have relegated their use to very special situations. Proper addition of oxidizing agent can be controlled by an empiric potentiometric measurement of the redox potential. If the potential between a platinum and a calomel electrode inserted into the digesting ore mixture is adequately controlled, the iron will be present principally as Fe3þ and suitable oxidizing conditions will have been imposed (Woody and George, 1955). The most common form in which acid leaching is applied is in the form of aqueous leaching with agitation. The sulfuric acid concentration is adjusted so that it close to pH 1.5 at the end of the leaching period; the period of extraction

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is generally 4–48 h, in U.S. practice typically 4–24 h. Elevated temperatures and higher acid concentrations increase the rate of extraction but are often uneconomic and result in higher reagent consumption, increased corrosion, and increased dissolution of non‐uranium minerals. Counter‐current leaching in several stages is sometimes used but is less common than single stage processes. Recycle circuits have also been devised to use the acid leachant more efficiently. A less common procedure is acid pugging, in which a small amount of dry, ground ore is mixed with a more concentrated acid to form a plastic mass, which is allowed to cure and then leached with water. Percolation leaching, in which solution percolates slowly through an ore bed, is well‐suited to ores in which the uranium minerals occur as coatings on sand grains, particularly when the ore is of low grade. A variation of percolation leaching that has important application to low‐grade ores is heap leaching, in which 5–10 m deep piles of ore of about 100 m length are leached by slow percolation of an acid solution that is collected in the pile drainage. In situ leaching is another method that has been applied to certain ore bodies with low permeability of the rock underlying the deposit and adequate porosity of the ore body itself. In this procedure, wells are drilled into the ore body and leachant is pumped into some of these while the enriched solutions are pumped from other wells. Two acid leaching methods require no reagent addition in some ores containing sulfides or sulfur. These methods are pressure leaching, in which air is the oxidant at elevated temperatures (150 C) and pressures, and bacterial leaching, where air is also the oxidant but at temperatures near ambient. In both cases uranium dissolution is brought about by the oxidation of iron and sulfur compounds to Fe3þ and sulfuric acid. Typical reactions in pressure leaching are 4FeS2 þ 15O2 þ 2H2 O ! 2Fe2 ðSO4 Þ3 þ 2H2 SO4 UO2 þ Fe2 ðSO4 Þ3 ! UO2 SO4 þ 2FeSO4 4FeSO4 þ 2H2 SO4 þ O2 ! 2Fe2 ðSO4 Þ3 þ 2H2 O Similar overall reactions occur in bacterial leaching through the action of bacteria, such as Thiobacillus ferrooxidans and others, on ferrous ion, sulfur, and sulfides. Although there are several reported advantages of high‐pressure leaching, such as improved extraction and shorter extraction times, particularly with refractory ores, there is also larger corrosion and higher maintenance costs and the method has received little actual use. Bacterial leaching appears to be particularly attractive as a low‐cost recovery method for very low‐grade ores when used with heap or in situ leaching. While acid leaching is excellent for many ores, and is essential for primary refractory ores such as euxenite, davidite, and brannerite, it is subject to certain limitations. Most uranium minerals are soluble in dilute sulfuric acid with an oxidant present, but many ores contain other minerals such as calcite, dolomite, and magnesite, which consume sufficient amounts of acid to make

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acid leaching uneconomic. In such cases, carbonate solutions are used to extract uranium. Carbonate leaching is usually carried out with sodium carbonate. The utility of carbonate solutions arises from the high stability of the uranyl(VI) tricarbonate ion, UO2 ðCO3 Þ4 3 , in aqueous solution at low hydroxide‐ion concentration. Uranium(VI) is thus soluble in carbonate solution, unlike the vast majority of other metal ions, which form insoluble carbonates or hydroxides in these solutions. The sodium carbonate leaching is thus inherently more selective than the sulfuric acid procedure. In general, compounds of uranium(VI) are readily soluble in carbonate leach solutions although silicates dissolve, albeit with some difficulty. Minerals containing uranium in its lower oxidation states are insoluble in carbonate solutions, and oxidants are required. Under oxidizing conditions, simple uranium oxides and some other uranium(IV) minerals such as coffinite can be leached, particularly at elevated temperature. In addition to the advantage of low reagent consumption in carbonate‐ containing ores, carbonate leaching is relatively (but not completely) specific for uranium and carbonate solutions, which are moderately non‐corrosive. Disadvantages include lower uranium extraction than by acid leaching and that the method is not suitable for ores having high gypsum or sulfide content. Important refractory minerals such as euxenite, brannerite, and davidite are not attacked significantly without a prior fusion step. Since few ore components other than uranium minerals are attacked to any appreciable extent by carbonate solutions, any uranium imbedded in gangue will escape leaching. A carbonate leach thus requires sufficiently fine grinding to liberate the uranium. Economics dictate that the reagents must be recovered and recycled in the carbonate leach process. Oxygen (often under pressure) is the commonly used oxidant in carbonate leaching and the dissolution of simple uranium oxide follows the reactions (Merritt, 1971). 2UO2 þ O2 ! 2UO3 4  UO3 þ H2 O þ 3CO2 3 ! UO2 ðCO3 Þ3 þ 2OH 2 OH þ HCO 3 ! CO3 þ H2 O

As shown in the equations above, bicarbonate is used to prevent increase in the hydroxide concentration, which would result in precipitation of uranates or polyuranates by the reaction  þ 2 2UO2 ðCO3 Þ4 3 þ 6OH þ 2Na ! Na2 U2 O7 þ 6CO3 þ 3H2 O

The detailed dissolution mechanisms are more complex than represented here and several possible alternatives have been proposed (Clegg and Foley, 1958; Wilkinson, 1962; Merritt, 1971). Although air is the most commonly used oxidant in carbonate leaching, other oxidants have been used. Potassium permanganate was commonly used in the past but was expensive and replaced

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by pressurized leaching at 95–120 C in air. This was followed by the use of cupric–ammonia complexes, a catalyst for air oxidation, but current practice is toward simply using air at atmospheric pressure and longer dissolution times at about 75–80 C in Pachuca‐type (air‐agitated) tanks (Merritt, 1971). Pure oxygen has been used (Woody and George, 1955) in place of air with some advantages. Other oxidants that have been considered are NaOCl, H2O2, and K2S2O8. Various catalysts such as MgCl2, Ag2SO4, K3Fe(CN)6, copper–cyanide complexes, and copper–, nickel–, and cobalt–ammonia complexes have also been studied. Although sodium carbonate is the only reagent used commercially in alkaline leaching, ammonium carbonate has been extensively tested in the laboratory and pilot plant (Merritt, 1971). Since the concentrations of sodium carbonate and bicarbonate used are typically 0.5–1.0 M, the recovery of reagents is necessary. The specificity of carbonate leaching for uranium is such that the uranium can usually be recovered from the leach solution by precipitation as sodium polyuranates (‘diuranate’) with sodium hydroxide. The filtrate is then treated with carbon dioxide to regenerate the desired carbonate/bicarbonate ratio. While the amounts of carbonate, bicarbonate, and oxygen consumed during leaching are usually very small, side reactions may occur with other constituents of the ores, which consume substantial amounts of carbonate. Particularly important parasitic reactions are due to sulfide minerals and gypsum and, at higher temperatures and pressures, silica and alumina: 2  2FeS2 þ 15=2O2 þ 8CO2 3 þ 7H2 O ! 2FeðOHÞ3 þ 4SO4 þ 8HCO3 2 CaSO4 þ CO2 3 ! CaCO3 þ SO4 2  SiO2 þ H2 O þ 2CO2 3 ! SiO3 þ 2HCO3   Al2 O3 3H2 O þ 2CO2 3 ! 2AlO2 þ 2HCO3 þ 2H2 O

Flotation may be used to reduce the initial sulfide content to tolerable limits. Organic materials in some ores cause difficulties in the carbonate leach process and various schemes for handling this problem are reviewed by Merritt (1971). A simplified flow sheet for carbonate leaching is shown in Fig. 5.5. Clarification is the separation of ore slimes from the aqueous uranium extract and constitutes the final step in ore extraction of uranium. It is a necessary step except when the resin‐in‐pulp ion‐exchange process is used, in which case only partial clarification is necessary, and when in situ, heap, or percolation leaching has been used, since the ore itself acts as an effective filter medium in these leaching techniques and clear solutions are obtained. Solution clarification has in the past been one of the most difficult problems in uranium recovery, but flocculants have been developed (Clegg and Foley, 1958) to improve settling of clays and other slimy ore constituents. These have greatly improved liquid–solid separation technology and most ores can now be handled satisfactorily in liquid–solid separation equipment with the proper choice and use of flocculants.

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Fig. 5.5 Flow sheet of raw ore leach for unoxidized or primary uranium of Eldorado Mining and Refining Ltd, Beaverlodge, Saskatchewan (Stephens and McDonald, 1956).

Flocculants used include polyacrylamides, guar gums, and animal glues. For the resin‐in‐pulp process, only the coarser ore particles (325 mesh) are removed and slime contents of 5% to as high as 20% solids can be handled depending on exact process design. Clegg and Foley (1958) and Merritt (1971) review clarification in detail. 5.4.4

Recovery of uranium from leach solutions

The recovery of uranium from leach solutions can be achieved by a variety of methods including ion exchange, solvent extraction, and chemical precipitation. Each of the various procedures listed above can be applied to acid or alkaline

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leach liquors, although in general they will not be equally applicable. Although various precipitation methods were extensively used in the past, they were generally cumbersome and complex if significant uranium purification was to be achieved. Currently operating uranium mills, with the exception of some that employ carbonate leaching, all use ion exchange or solvent extraction, or both, to purify and concentrate the uranium before a final product precipitation. Because of the selectivity of carbonate leaching, precipitation from carbonate leach solutions produces a fairly pure uranium concentrate, but for acid leach solutions, ion exchange or solvent extraction is always employed. (a)

Ion exchange

The recovery of uranium by ion exchange is of great importance. Uranium(VI) is selectively absorbed from both sulfate and carbonate leach solutions as anionic complexes using anion‐exchange resins. The loaded resin is rinsed, and the uranium eluted with a sodium chloride or an acid solution. The uranium is then precipitated from the eluate and recovered as a very pure uranium concentrate. This process can be carried out with either stationary columns of ion‐exchange resin through which clarified leach liquors are passed; alternatively the resin may be moved through the leach liquor in agitated baskets. This resin‐in‐pulp process does not require complete clarification of the leach liquor. The degree of purification of the uranium by these ion‐exchange processes is related to the selectivity of the anion‐exchange resins for the anionic uranyl sulfate or carbonate complexes relative to that of impurity species. Cationic impurities are not absorbed and many anionic species are absorbed less strongly than are the uranyl complexes and are displaced by them. The impurities can be left in the ion exchangers during uranium elution, but often they are so strongly absorbed as to act as exchanger poisons that require elaborate removal steps. The uranyl species absorbed by the exchangers from carbonate solution appears to be exclusively the UO2 ðCO3 Þ4 3 complex, but from sulfate solutions more than one species is absorbed (Ryan, 1962). Although it has been reported (OECD‐NEA, 1982) that below pH 2 the only uranyl sulfate complex in the resin is UO2 ðSO4 Þ4 3 , spectral studies of the resin phase (Ryan, 1962) indicate that, although UO2 ðSO4 Þ4 3 is present over at least the pH range 0.5–4.5, it is not the only uranyl species. The ratio of uranyl species in the resin phase changes with pH but is almost unaffected by change in total aqueous phase sulfate concentration at any given pH. Even if the affinity of anion‐exchange resins for complex anions may be very high, high distribution coefficients do not necessarily mean that an appreciable fraction of the uranium is present as anionic species in the aqueous phase. Both weak‐base or strong‐base resins can be used with the sulfate system, but only the strong‐base resins in the basic carbonate solutions. In practice, the resin choice is governed by several factors, including absorption and elution kinetics, resin particle size, the physical and

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chemical stability of the resin, the selectivity and ease of removal of resin poisons, hydraulic characteristics, and exchange capacity. Typically, resins of moderately low cross‐linking and moderately large particle size are used and several resins have been marketed specifically for uranium processing. Elution of the uranium from anion‐exchange resins in either the sulfate or the carbonate processes is normally made with approximately 1 M sodium or ammonium chloride or nitrate solutions. In the sulfate process the eluent is acidified, and in the carbonate process some carbonate or bicarbonate is added to prevent hydrolysis. Special elution techniques are used for vanadium recovery when it is co‐absorbed in the carbonate process (Merritt, 1971). Although uranyl sulfate and carbonate complexes have a higher affinity for the resin than most impurity ions, they are not extremely strongly sorbed and some impurity ions are more strongly absorbed. In the acid system such ions include pentavalent vanadates, molybdenum sulfate complexes, polythionates, and in South African ores treated for gold recovery, cobalt cyanide complexes and thiocyanate. Vanadates are more strongly absorbed than uranium in the carbonate process except at high pH values. In addition, some other weakly sorbed ions may be present in sufficiently high concentration to compete for resin sites, resulting in decreased uranium loading; some of these may also alter absorption kinetics. Some of the strongly held ions and others such as silicate, titanium, thorium, hafnium, niobium, antimony, and arsenate and phosphate complexes, which polymerize or hydrolyze in the resin phase, are not readily removed during the normal elution process. They gradually build up in the resins where they act as poisons and require special removal procedures (Merritt, 1971). Merritt (1971) and Clegg and Foley (1958) have reviewed the uranium ion‐ exchange processes in detail along with the various specialized problems encountered and their treatment. They have discussed specific flow sheets, processing rates, back‐cycle methods for reagent conservation, and processing equipment for fixed‐bed, moving‐bed, basket resin‐in‐pulp, and continuous resin‐in‐pulp ion‐exchange processes. (b)

Solvent extraction

Solvent extraction has a distinct advantage over ion exchange for uranium purification from leach liquors because of the ease with which it can be operated in a continuous counter‐current flow process. It has a disadvantage, however, in the incomplete phase separation, due to emulsion formation, third-phase formation, etc. In addition solvent losses constitute both a monetary loss and a potential pollution problem in the disposal of spent leach liquor. Because solvent losses are related to overall solution volume, solvent extraction usually has an advantage for leach solutions with concentrations above about 1 g U per liter, and ion exchange has an advantage for low‐grade solutions with concentrations appreciably less than 1 g U per liter (Merritt, 1971). Solvent extraction

312

Uranium

processes are not economically advantageous for carbonate leach solutions. Two types of alkyl phosphoric acids and secondary and tertiary alkylamines, have been used industrially for uranium extraction from sulfate leach liquors. These extraction reagents are normally used as relatively dilute solutions in an inert diluent such as kerosene. Modifiers such as long‐chain alcohols and neutral phosphate esters are typically added to prevent third‐phase formation to increase amine salt solubility in the diluent, and to improve phase separation. Amine extraction from sulfate leaching is analogous to anion exchange in that anionic uranyl sulfate complexes are extracted by the alkylammonium cations. The species extracted, at least by tertiary amines, is predominantly the UO2 ðSO4 Þ4 3 complex in the pH range (1 < pH < 2) normally used in commercial processing. The concentration of other uranyl species increases with decreasing pH (Ryan, 1962). There is considerable variation in affinity and selectivity for uranium with the structure of the amine. Typical commercially used tertiary amines give extraction coefficients of 100–140, whereas N‐benzylheptadecylamine gives extraction coefficients as high as 8000 (Merritt, 1971). Such specialized amines, if made available at a reasonable cost, will be capable of recovering uranium from very dilute leach solutions but might require more complex stripping procedures. Amines extract other anions to varying degree and thereby decrease uranium extraction efficiency. Nitrate interference is severe and chloride interference is more severe for secondary than for tertiary amines. These factors are important for the choice of stripping agent and the recycling of solutions. Molybdenum is extracted more strongly than uranium. It builds up as a poison in the amine, finally causing serious problems by precipitating at the organic–aqueous interface, and special molybdenum stripping procedures are used to counteract this problem (Merritt, 1971). Vanadium is also extracted to some extent. Various ions are effective in stripping uranium from the solvent. Nitrate has such high affinity for the amine that it must be removed in the carbonate or hydroxide regeneration step before the next extraction cycle; however this is not necessary in solutions containing chloride, except with secondary amines having high chloride affinity. Another procedure uses ammonium sulfate with pH carefully controlled in the range 4.0–4.3, since poor stripping or poor phase separation occurs outside this range. Direct precipitation of uranium from the organic phase has been proposed (Brown et al., 1958). The alkylphosphoric acid extractants have the advantage over amines of fewer phase separation problems due to suspended solids and of having good extraction efficiency in the presence of dilute nitrate, chloride, and sulfate. On the other hand, they suffer from lower selectivity for uranium since the alkyl phosphates extract cations and many of the impurities including iron in the leach solutions. Special methods for removing or rendering these impurities non‐extractable have been devised. Alkylphosphoric acid extraction has been referred to as ‘liquid cation exchange’. The dialkyl phosphates appear to be

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dimers and four dialkyl phosphates are required to extract one uranyl ion (Baes et al., 1958; Blake et al., 1958). Addition of neutral phosphate esters increases the uranium extraction coefficient of alkylphosphoric acids (synergistic effect). Stripping of bis(2‐ethylhexyl)phosphoric acid is normally carried out with carbonate solution, but monodecylphosphoric acid requires 10 M HCl for stripping. In addition to the solvent extraction procedures discussed above, mixed amine–alkylphosphoric acids have also been used. Other processes include both ion‐exchange and solvent‐extraction steps as well as special methods for removing and in some cases recovering interfering ions such as molybdenum. Solvent extraction methods have also been studied in cases where the leach solution is not clarified, solvent‐in‐pulp, but solvent losses are then very high. Merritt (1971) has reviewed the commercial practice in detail and gives many further references. (c)

Chemical precipitation

Before the use of ion‐exchange and solvent extraction methods for the removal and purification of uranium from leach liquors, precipitation techniques were used on clarified leach liquors. Much effort was spent during the late 1940s to develop selective precipitation processes; most of these techniques are obsolete and will not be discussed here but they are reviewed by Wilkinson (1962) and by Merritt (1971). The product from typical acid process anion‐exchange or solvent extraction processes is an acid solution of mixed nitrate or chloride and sulfate. The two principal methods of precipitation of uranium from these are neutralization with sodium hydroxide, magnesia, or ammonia, or the precipitation of the peroxide UO4 · xH2O in the pH range 2.5–4.0 with hydrogen peroxide. In the neutralization procedure a preliminary pH adjustment to 3.5–4.2 is made to precipitate and remove iron if it exceeds specifications. Phosphate, if present, is also removed in this step as iron phosphate. Uranium precipitation is then accomplished at a pH of 6.5–8.0. Since the cations used (Naþ, M2þ, or NH4þ) contaminate the product by formation of insoluble polyuranates, the choice of precipitant will depend on cost, physical nature of the precipitate formed, product specifications, etc. Most U.S. plants now use ammonia, which can be removed by heating of the product, but there is also some use of magnesia. The peroxide precipitation process is more specific although the cost is somewhat higher, a higher‐purity product is obtained. Ferric ions must be removed to a concentration less than 0.5 g L–1 in order to prevent catalytic decomposition of hydrogen peroxide in a preliminary precipitation step; alternatively the decomposition is prevented by precipitation from very cold solutions or by complexing the iron. The precipitates (‘yellow cake’) are dried, and in the case of the ammonia, precipitated material of composition approximately (NH4)2U2O7 (ammonium diuranate) may be heated to form U3O8 or UO3, depending on

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314

temperature. The magnesium and sodium polyuranates are stable to low‐temperature calcination. Precipitation from alkaline solution is carried out with either clarified carbonate leach solution or with alkaline eluting or stripping solutions from ion exchange or solvent extraction. The three methods include addition of strong base, acidification followed by CO2 removal and neutralization, and reduction to U(IV). The latter method is the only one capable of direct recovery of any vanadium present; the other ones do not result in complete recovery or complete separation. Sodium hydroxide does not completely precipitate uranium from carbonate solution; despite this, the filtrate is recarbonated and recycled. The product consists of sodium polyuranates. Acidification, carbon dioxide removal by boiling, and neutralization (usually with ammonia or magnesia) is preferred for the high‐uranium‐concentration carbonate strip solutions from solvent extraction since the volume is low and recycling of reagents is not so important. Reduction of uranyl(VI) carbonate solutions results in precipitation of hydrated U(IV) oxide. Reduction methods include hydrogen reduction under pressure in the range 100–200 C with appropriate catalyst, electrolytic reduction, and sodium amalgam reduction. Vanadium is reduced and co‐precipitated with uranium. Merritt (1971) has reviewed precipitation conditions, flow sheets, and plant practice in detail.

(d)

By‐product uranium

In South Africa, uranium is recovered as a by‐product of gold recovery by conventional methods after the recovery of gold by cyanide leaching. Uranium has also been recovered as a by‐product from crude phosphoric acid by both ion exchange and solvent extraction methods. In anion exchange, U(VI) is absorbed and concentrated by absorption of uranyl phosphate complexes, but resin capacities are uneconomically low. Solvent extraction has normally involved use of alkyl pyrophosphate extraction of U(IV) (Greek et al., 1957), but other schemes utilize extraction of U(VI) and synergistic combinations of phosphates. References to previous work in this field are given in a paper on this subject (Deleon and Lazarevic´, 1971).

(e)

Refining to a high‐purity product

The normal product of uranium milling operations, ‘yellow cake’ or calcined ‘yellow cake’, is not sufficiently pure to be of nuclear grade and is normally further refined to produce nuclear‐grade material (IAEA, 1980). There has been some emphasis on further upgrading in the mill to produce a high‐grade product by using multiple stages of solvent extraction and/or ion exchange, special stripping methods, more selective precipitation methods, or combinations of these (see Merritt, 1971 for further detail). The usual refining operation has

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normally been carried out either by tri(n‐butyl)phosphate (TBP) extraction from nitric acid solutions or by distillation of uranium hexafluoride, since this is the feed for isotope enrichment plants. Solvent extraction and fluoride volatility processes are currently used for uranium refining. A schematic flow diagram of a typical TBP/kerosene extraction process is shown in Fig. 5.6; a fluoride volatility process flow sheet is shown in Fig. 5.7. The TBP extraction from nitric acid solution makes use of the very selective tendency of actinides to form nitrate‐ or mixed nitrate–solvent complexes, as discussed further in Chapters 23 and 24. This process replaces the earlier and more hazardous diethyl ether extraction from nitrate solution. The extraction reaction is UO2 ðNO3 Þ2x þ ð2  xÞNO 3 þ 2TBP ! UO2 ðNO3 Þ2 ðTBPÞ2 x where x ¼ 0–2. Thorium is the only normally encountered impurity element having an appreciable distribution coefficient into a kerosene-TBP phase from nitric acid solution, but its distribution is sufficiently low that it can be transferred to the aqueous phase by high uranium loading of the organic phase.

Fig. 5.6 Schematic flow diagram: TBP/kerosene extraction system at the Fernald refinery (Harrington and Ruehle, 1959).

316

Uranium

Fig. 5.7 Overall process flow diagram for fluoride volatility process for the refining of ore concentrates (Ruch et al., 1959).

The purified uranium is stripped from the organic phase with water, converted to UO3, reduced with hydrogen to UO2, and converted to UF4 with hydrogen fluoride at elevated temperatures. The UF4 can either be reduced to uranium metal for natural uranium reactors or be fluorinated to UF6 for isotopic

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enrichment for production of other types of reactor fuel. The fluoride volatility process makes use of reduction to UO2 followed by direct fluorination, using the cheaper hydrogen fluoride to make UF4 followed by F2 to prepare UF6. The UF6 is fractionally distilled to produce a high‐purity UF6 for isotopic enrichment. The chemistry and operating conditions of the TBP refining process, the conversion to UO3, UO2, and finally to UF4 are reviewed in detail in the book edited by Harrington and Ruehle (1959). Ruch et al. (1959) have described the refining of ore concentrates by uranium hexafluoride distillation. Hyman et al. (1955) have converted uranium ore concentrates to UF6 by means of liquid‐phase fluorination using bromine trifluoride, BrF3 (b.p. 126 C). While not applicable to raw ore, the procedure may be readily applied to concentrates. Results of experiments along these lines are summarized in Table 5.4. Since fluorine in the form of BrF3 is rather expensive, it is worthwhile to introduce as much fluorine as possible via the inexpensive reagent hydrogen fluoride (which cannot, of course, be used to convert lower uranium fluorides to uranium hexafluoride), and then to complete the fluorination process with bromine trifluoride. This reduction of fluorine consumption may be readily accomplished by a preliminary hydrofluorination at 600 C. This treatment fluorinates silica and other gangue materials present in the ore concentrate and converts uranium(IV) to UF4. Thus, two‐thirds of the fluorine in the final UF6 product is introduced by the relatively inexpensive hydrogen fluoride rather than by bromine trifluoride. Since uranium hexafluoride is used for the isotope separation of uranium, chlorination procedures have not received nearly as extensive investigation, because of the serious corrosion problems created by the use of chlorine at elevated temperatures.

Table 5.4 Fluorination of various ore concentrates with BrF3 (Hyman et al., 1955). Ore concentrate Source rand concentrate rand concentrate intermediate plant concentrate intermediate plant concentrate a

U content (%)

Uranium retained by residuea,b (%)

F2 consumptiona,c (cm3 F2(STP) per g U)

68.1 68.1 23.3

0.16, 0.07 0.73, 0.10d 1.45, 0.81

383, 419 133, 138d 805, 767

32.6

0.55, 1.00

552, 735

Duplicate runs are given for each sample and treatment. (Grams U in residue/grams U in initial concentrate)  100. c To form UF6 from 1 g U as metal requires 282.5 cm3 F2; to form UF6 from 1 g U as UF4 requires 94.2 cm3 F2. d After hydrofluorination. b

Uranium

318 5.5

PROPERTIES OF FREE ATOMS AND IONS

Uranium, being one of the elements with the largest atomic number, has a very complex electronic structure. This is manifested in its spectral properties as they appear in the X‐ray, UV/visible and fluorescence spectra. Details of the electronic energy levels deduced experimentally and from quantum chemical calculations are discussed in detail in Chapter 16 and in the following sections where the properties of compounds and complexes are described. The focus in Section 5.9 is on the interpretation of solid state spectra using the crystal field model and in Section 5.10 on solution spectra, including fluorescence spectroscopy of uranyl(VI) species.

5.6

URANIUM METAL

Uranium metal was used in earlier reactor systems but is now largely replaced in commercial reactors by ceramic uranium dioxide. Large‐scale production of uranium metal requires elevated temperature where the high reactivity of uranium with most common refractory materials and metals makes the selection of reaction vessels a difficult problem. Finely divided uranium reacts even at room temperature with all the components of the atmosphere except the noble gases. However, contrary to the situation with titanium and zirconium, the introduction of small amounts of oxygen or nitrogen does not have an adverse effect on the mechanical properties of the metal. There are three different phases of metallic uranium below the melting point, a‐, b‐, and g‐uranium, each with its specific structure and physical properties. A detailed discussion of the physical properties is given in Chapter 21 on actinide metals and a short description on uranium metal and alloys in the following section.

5.6.1

Preparation of uranium metal

The element uranium is strongly electropositive, resembling aluminum and magnesium in this respect; consequently uranium metal cannot be prepared by reduction with hydrogen. Uranium metal has been prepared in a number of ways: reduction of uranium oxide with strongly electropositive elements, such as calcium, electro‐deposition from molten‐salt baths, thermal decomposition, decomposition of uranium halides (van Arkel de Boer ‘hot wire’ method), and reduction of uranium halides (UCl3, UCl4, UF4) with electropositive metals (Li, Na, Mg, Ca, Ba). Only the last method is of current importance. For details, the reader is referred to two comprehensive surveys (Katz and Rabinowitch, 1951; Warner, 1953) and of older work to a review by Wilkinson (1962) and to the Gmelin Handbook of Inorganic Chemistry (1981a).

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319

Both uranium tetrafluoride and tetrachloride are reducible with calcium and magnesium, while uranium dioxide can be reduced with calcium and probably magnesium. Finely divided uranium is pyrophoric and a massive metal product is therefore desired; this can be achieved by ensuring that the entire reaction mixture is fluid for a sufficiently long time for uranium metal to collect; this requires a slag with a moderately low melting point. Calcium oxide and magnesium oxide slags have melting points well above 2500 C, and are therefore less useful than calcium fluoride and magnesium fluoride, with melting points 1423 C and 1261 C, respectively. Uranium tetrachloride is very hygroscopic, and subject to oxidation in air and therefore the much more stable uranium tetrafluoride is preferred. Magnesium is the reagent of choice for reduction, since it is available in large quantities with a high degree of purity and can also be handled in air without special precautions. Details of a process based on these considerations are described by Wilhelm (1956) and in the books by Warner (1953) and by Harrington and Ruehle (1959). For small‐scale production of 233U or 235U in metallic state the batch size is limited by their critical mass of these isotopes and calcium is the preferred reductant. Bertino and Kirchner (1945), have described the special procedures for 233U, and Patton et al. (1963) and Baker et al. (1946) those for 235U. Uranium ore concentrates are first purified by solvent extraction with TBP in kerosene as the immiscible solvent in the manner described in Section 5.4.4e. The purified uranyl nitrate is then decomposed thermally to UO3. The trioxide is reduced with hydrogen to the dioxide, which in turn is converted to uranium tetrafluoride, ‘green salt’, by high‐temperature hydrofluorination. The tetrafluoride is then reduced to metallic uranium with magnesium. A flow sheet of the production of uranium from ore concentrates is given in Fig. 5.8. The temperature reached during the reduction reaction exceeds 1300 C where magnesium metal has a very high vapor pressure; hence, the reaction must be carried out in a sealed container (bomb). Such bombs are made in various sizes from standard seamless pipes. Their lengths range from 91.4 to 114.3 cm (36 to 45 in.), their diameters up to 33 cm (13 in.). Uranium prepared by the metallothermic processes described above is of sufficient purity for most purposes. However, it may be further purified by molten‐salt electrolysis (Slain, 1950; Noland and Marzano, 1953; Niedrach and Glamm, 1954; Blumenthal and Noland, 1956) using alkali or alkaline‐ earth chloride as electrolytes. UF4, UCl4, or UCl3 are dissolved in these electrolytes. The material to be purified is used as the anode, molybdenum, or tantalum as the cathode; a diaphragm, usually of a sintered, porous ceramic material, separates the anode and the cathode. Other methods that have been employed in uranium purification include zone melting (Whitman et al., 1955; Antill, et al., 1961) and hot‐wire deposition (Fine et al., 1945; Prescott et al., 1946). Because of the low melting point of uranium, the latter method is only of limited value.

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320

Fig. 5.8 Flow sheet for the production of uranium metal by reduction of UF4 with magnesium (Kelley, 1955).

(a)

Physical properties of uranium metal

(i)

Crystal structure

Uranium metal has three crystalline phases below the melting point at (1134.8 2.0) C. The a‐phase is the room‐temperature modification of uranium; it is orthorhombic with space group No. 63, Cmcm and unit cell parameters ˚ , b ¼ 5.87 A ˚ , and c ¼ 4.955 A ˚ (Barrett et al., 1963; Lander and a ¼ 2.854 A Mu¨ller, 1970) and one uranium at the site 4c in the space group. The structure consists of corrugated sheets of atoms, parallel to the ac‐plane and perpendicular to the b‐axis. Within the sheets the atoms are tightly bonded, whereas the forces between atoms in adjacent sheets are relatively much weaker (Fig. 5.9). This arrangement is highly anisotropic and resembles the layer structures of arsenic, antimony, and bismuth. In the a‐uranium structure, ˚ and between adjacent layers the U–U distances in the layer are (2.80 0.05) A

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321

Fig. 5.9 The structure of a‐uranium from Lander and Mu¨ller (1970). It is a layer structure with puckered ac‐layers perpendicular to the b‐axis; the uranium–uranium distances in the ˚ and between the layers 3.26 A ˚. layer are (2.80 0.05) A

˚ . The physical properties of the a‐phase are a reflection of its structure, 3.26 A e.g. the strongly anisotropic coefficient of thermal expansion. The average value of the thermal expansion coefficient over the temperature range 25–325 C is 26.5, –2.4, and 23.9  10–6  C–1, respectively, along a, b, and c. A chemical consequence of the unique orthorhombic structure of a‐uranium is that the formation of solid solutions with metals of the common structure types is severely restricted. The b‐phase of uranium exists between 668 and 775 C; it has a complex structure with six crystallographically independent atoms in the tetragonal unit cell (Donohue and Einspahr, 1971). The space group is P42/mnm, P42nm, ˚ and b ¼ c ¼ 10.759 A ˚ . The lattice or P4n2, with unit cell parameters a ¼ 5.656 A parameters were determined in an alloy with 1.4% chromium at 720 C, and in uranium powder in the temperature range where the phase is stable. The tetragonal lattice is a stacked layer structure with layers parallel to the ab plane of the unit cell at c/4, c/2, and 3c/4. Additional high‐precision measurements are required to solve the structure completely (Donohue and Einspahr, 1971). The g‐phase of uranium is formed at temperatures above 775 C; it has a ˚ ; the body‐centered cubic (bcc) structure with the cell parameter a ¼ 3.524 A phase stabilized at room temperature by the addition of molybdenum that forms an extensive series of solid solutions with g‐uranium. (b)

General properties

Foote (1956), Holden (1958), and Wilkinson and Murphy (1958) have described the physical metallurgy of uranium and Oetting et al. (1976) and Rand and Kubaschewski (1963) the thermodynamic properties of uranium metal. A number of physical and thermal properties of elemental uranium are collected in Table 5.5. Uranium is not a refractory metal like chromium, molybdenum, or tungsten; it is among the densest of all metals, being exceeded in this respect only by some of the platinum metals and by a‐Np and a‐Pu.

Uranium

322 Table 5.5

Physical and thermal properties of uranium (Oetting et al., 1976).

melting point vapor pressure 1720–2340 K (Pattoret et al., 1964) 1480–2420 K (Ackerman and Rauh, 1969) X‐ray density (a‐uranium) (Lander and Mu¨ller, 1970) enthalpy of sublimation DfH (U, g, 298.15 K) enthalpy H (298.15 K) – H (0 K) entropy S (298.15 K) heat capacity Cp ð298:15 KÞ transformation points a to b b to g enthalpies of transformation DtrsH (a to b) DtrsH (b to g) DfusH (g to liq) enthalpy and specific heat functions a‐uranium (298–942 K)

b‐uranium (942–1049 K) g‐uranium (1049–1408 K) uranium (liquid) thermal conductivity at 298.15 K (Ho et al., 1972) electrical resistivity (300 K) (Arajs and Colvin, 1964) a

(1408 2) K log p(atm) ¼ (26210 270) T –1 þ (5.920 0.135) log p(atm) ¼ (25230 370) T 1 þ (5.71 0.17) 19.04 g cm–3 (533 8) kJ mol–1a 6364 J mol–1 (50.20 0.20) J K–1 mol–1a (27.669 0.050) J K–1 mol–1 (942 2) K (1049 2) K 2791 J mol–1 4757 J mol–1 9142 J mol–1 HT – H298 ¼ 26.920T – 1.251  10–3T2 þ 8.852  10–6T3 þ 0.7699  105T–1 8407.828 (J mol–1) Cp ¼ 26.920 – 2.502  10–3T þ 26.556  10–6T2 – 0.7699  105T–2 (J K–1 mol–1) HT – H298 ¼ 42.920T – 14326.020 (J mol–1) Cp ¼ 42.92(J K–1 mol–1) HT – H298 ¼ 38.280T – 4698.690 (J mol–1) Cp ¼ 38.28 (J K–1 mol–1) HT – H298 ¼ 48.650T – 10137.120 (J mol–1) Cp ¼ 48.65 (J K–1 mol–1) 27.5 J m–1 s–1 K–1 28  10–8 O m

CODATA key value (Cox et al., 1989).

The electrical resistivity of uranium is about 16 times higher than that of copper, 1.3 times that of lead and approximates that of hafnium (Gale and Totemeier, 2003). An important mechanical property (Table 5.6) of uranium is its plastic character, allowing easy extrusion. The mechanical properties are very sensitive

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323

Table 5.6 Average mechanical properties of uranium (Grossman and Priceman, 1954; Wilkinson and Murphy, 1958). modulus of elasticity Poisson ratio at zero stress shear modulus bulk modulus proportional limit yield strength 0.1% offset 0.2% offset compressibility b100 b010 b001 bv

1758  106 kPa 0.20 73.1  106 kPa 97.9  106 kPa 2.068  104 kPa 1.8617  105 kPa 2.2754  105 kPa 0.758 7% 0.296 16% 0.141 16% 1.195 6%

to the pre‐history of the sample, and are strongly dependent on crystal orientation, fabrication, and heat treatment. Despite its plastic nature, uranium has a definite yield point with a well‐defined, but very low, proportional limit. The ultimate tensile strength of uranium varies between 3.44  105 and 13.79  105 kPa, depending on the cold working and previous thermal history of the sample. Uranium rapidly loses strength at elevated temperatures, the tensile strength falling from 1.862  105 kPa at 150 C to 0.827  105 kPa at 600 C. The Brinell hardness of rolled polycrystalline a‐uranium varies between 2350 and 2750 MN m–2 at 23 C (Samsonov, 1968). The hardness is strongly affected by impurities. Cold working increases the hardness with up to 50%. Above 200 C, the hardness falls off rapidly. g‐Uranium is so soft as to make fabrication difficult, while the b‐phase is harder and considerably more brittle than the a‐phase. (c)

Magnetic susceptibility and related properties

The solid‐state properties of uranium have been the subject of a relatively recent exhaustive review (Lander et al., 1994). Some pertinent physical properties taken from this review are given here. Although many measurements have been performed on uranium metal, the description and full understanding of its properties is still not complete. Uranium metal is weakly paramagnetic and exhibits almost temperature‐independent paramagnetism with a room temperature value of 390  10–9 emu mol–1. (Fournier and Troc´, 1985). a‐Uranium exhibits an anomaly at 43 K apparent in the magnetic susceptibility data and in other measurements. This anomaly and further phase transformations observed at 37 and 23 K have been attributed to charge density waves. a‐Uranium exhibits a superconducting transition at low temperatures that can be described by the Bardeen–Cooper–Schreiffer (BCS) theory. The maximal Tc value for

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324

Table 5.7 Components of uranium resistivity tensor at 273 K. References

r[100] (mO cm)

r[110] (mO cm)

r[110] (mO cm)

Brodsky et al. (1969) Berlincourt (1959) Pascal et al. (1964) Raetsky (1967)

36.1 0.2 39.4 39.1 34.7

20.6 0.2 25.5 23.6 23.6

26.0 0.2 26.2 30.2 20.3

Fig. 5.10 Resistivity–temperature curve for a‐uranium along the [010] axis (Brodsky et al., 1969).

a‐uranium is 2–2.3 K at a pressure of 1.0–1.1 GPa. The 0.1013 MPa (1 atm) value of Tc is taken as 0.1 K. (d)

Electrical and related properties

The temperature dependence of the resistivity of uranium single crystals has been measured by a number of authors and the components of the resistivity tensor are given in Table 5.7. The resistivity–temperature curve for a‐uranium along the [010] direction is shown in Fig. 5.10. Many other physical properties of elemental uranium have been determined, such as elastic moduli, heat capacity, de Haas‐van Alphen measurements, transport properties and others. The reader is referred to Lander et al. (1994) and to Chapter 21 for further discussion.

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325

Table 5.8 Reactions of uranium with various metals (Saller and Rough, 1955; Rough and Bauer, 1958; Chiotti et al., 1981). IS and SS denote intensely studied and slightly studied, respectively. Class

Behavior

I

form intermetallic compounds

IS

II

form solid solutions but no intermetallic compounds form neither solid solutions nor intermetallic compounds

SS

Al, As, Au, B, Be, Bi, Cd, Co, Cu, Fe, Ga, Ge, Hg, Ir, Mn, Ni, Os, Pb, Pd, Pt, Rh, Ru, Sb, Sn In, Re, Tc, Tl, Mo, Nb, Pu, Ti, Zr

IS SS

Ag, Cr, Mg, Ta, Th, V, W lanthanides, Li, Na, K, Ca, Sr, Ba

III

5.6.3

Metals

Uranium intermetallic compounds and alloys

The most noticeable features of the behavior of uranium with other metals are the formation of intermetallic compounds with a wide variety of alloying metals and the extensive ranges of solid solutions in a‐ and b‐uranium. Table 5.8 summarizes the alloying behavior with the metallic elements. Saller and Rough (1955), Pfeil (1956), Rough and Bauer (1958), Hansen and Anderko (1958), Elliott (1965), Shunk (1969), and Wilkinson (1962) have given comprehensive and informative descriptions of the general behavior of the alloying elements, including numerous phase diagrams. The thermodynamics of uranium alloy systems was reviewed by Chiotti et al. (1981). A large number of intermetallic compounds have been characterized by X‐ray crystallographic methods and by conventional metallographic techniques. The Gmelin Handbook of Inorganic Chemistry gives a comprehensive review of the properties of the uranium alloys with alkali metals, alkaline earths, and elements of main groups III and IV (Gmelin, 1989, vol. B2), with transition metals of groups IB to IVB (Gmelin, 1994, vol. B3), and with transition metals of groups VB to VIIB (Gmelin, 1995a, vol. B4), including the effects of irradiation, which are also discussed in the volume on technology and uses of uranium (Gmelin, 1981a, vol. A3). Among uranium intermetallic phases of interest may be mentioned the transition‐metal compounds U6Mn, U6Fe, U6Co, and U6Ni, which are distinguished by their hard and brittle nature. Uranium forms intermetallic phases with noble metals and the phase diagrams for U–Ru, U–Rh, U–Pd, U–Os, U–Ir, and U–Pt systems have been assessed by Chiotti et al. (1981), a compilation that also provides information on a number other intermetallic phases. The compounds of uranium with the light platinum metals, Ru, Rh, and Pd, are of interest in the pyrometallurgical reprocessing of metallic fuels, because the

326

Uranium

Fig. 5.11 Phase diagram of the uranium–molybdenum system (Chiotti et al., 1981).

noble metals form alloys that remain with the uranium when the fuel is processed for fission‐product removal by oxidative slagging. Elements of class III in many cases form simple eutectic systems. Molybdenum, titanium, zirconium, niobium, and plutonium form extensive solid solutions with uranium at elevated temperatures. No intermediate phases are detected for the U–Nb system, whereas the U–Mo, U–Pu, U–Ti, and U–Zr systems all show metastable phases. The uranium–molybdenum system is shown in Fig. 5.11 and illustrates the general features of the small but important class of true alloying elements. The uranium alloys have unusual physical properties that are discussed in Chapter 21.

Uranium metal

327

Table 5.9 Chemical reactions of uranium metal. Reactant

Reaction temperaturea ( C)

Products

H2 C N2 P O2 S F2 Cl2 Br2 I2 H2O HF(g) HCl(g) NH3 H2S NO N2H4 CH4 CO CO2

250 1800–2400 700 1000b 150–350 500 250 500 650 350 100 350b 300b 700 500b 400 25 635–900b 750 750

a‐ and b‐UH3 UC; U2C3; UC2 UN, UN2 U3P4 UO2, U3O8 US2 UF6 UCl4, UCl5, UCl6 UBr4 UI3, UI4 UO2 UF4 UCl3 UN1.75 US, U2S3, US2 U3O8 UO2(NO3)2 · 2NO2 UC UO2 þ UC UO2 þ UC

a

Reaction temperature with massive metal. Reaction temperature with powdered uranium (from decomposition of UH3). b

5.6.4

Chemical properties of uranium and its alloys

Uranium metal is a highly reactive substance that can react with practically all of the elements in the periodic table with the exception of the noble gases. Some of the more important chemical reactions of uranium are listed in Table 5.9. Wilkinson (1962) has discussed in detail the corrosion of massive uranium by various gaseous agents, such as dry oxygen, dry air, water vapor, carbon monoxide, carbon dioxide, and others, as well as the pyrophoricity of this element. Totemeier (1995) has written a more recent review of the corrosion and pyrophoricity behavior of uranium (and plutonium) with oxygen, water vapor, and aqueous solutions in terms of reaction rates, products, and reaction mechanisms. From a practical point of view, the reactions of uranium with oxygen, nitrogen, and water are probably the most significant. Uranium metal exposed to oxygen, water, or air undergoes reaction even at room temperature. The kinetics of corrosion of uranium by various reagents such as dry and moist oxygen, dry and moist air, water vapor and hydrogen, and the pyrophoricity of uranium, as well as that of plutonium, are discussed in detail in Chapter 29

Uranium

328

devoted to handling, storage, and disposal of these elements and their relevant compounds. Uranium dissolves very rapidly in aqueous hydrochloric acid. The reaction frequently yields considerable amounts of a black solid, presumably a hydrated uranium oxide but very likely containing some hydrogen. The addition of a small amount of fluorosilicate ion prevents the appearance of the black solid during dissolution in hydrochloric acid. Non‐oxidizing acids, such as sulfuric, phosphoric, and hydrofluoric, react only very slowly with uranium, whereas nitric acid dissolves massive uranium at a moderate rate. With finely divided uranium, the dissolution in nitric acid may approach explosive violence. Uranium metal is inert to alkalis. Addition of oxidizing agents such as peroxide to sodium hydroxide solution leads to the dissolution of uranium and to the formation of ill‐defined water‐soluble peroxyuranates.

5.7

COMPOUNDS OF URANIUM

Ever since the discovery of uranium in 1789, its compounds have been synthesized and studied, so that a wealth of information has accumulated over the years. Much of this information may be found in the books by Katz and Rabinowitch (1951, 1958) and in the various volumes of the Supplement Series of the Gmelin Handbook of Inorganic Chemistry (1975–1996), which constitute probably the most comprehensive collection of information on uranium compounds. For obvious reasons, such as lack of space, it is impossible to give a complete account of every uranium compound known to date. Rather, representative examples will be discussed with emphasis on preparation, structure, and chemical properties; information and discussion of thermodynamic properties of uranium and other actinide compounds are found in Chapter 19. In its compounds, uranium exhibits the oxidation states 3þ, 4þ, 5þ, and 6þ, with 4þ and 6þ as the predominant ones. Also, mixed valence and non‐stoichiometric compounds are known. While general features of the structures of uranium compounds, both from coordination and chemical points of view, will be discussed in Section 5.9, structures pertaining to each family of compounds will be described in the following subsections.

5.7.1

The uranium–hydrogen system

The uranium–hydrogen system has been reviewed by Katz and Rabinowitch (1951), Mallett et al. (1955), Libowitz (1968), Flotow et al. (1984), and Ward (1985). An extensive review has been given in the Gmelin Handbook (Gmelin, 1977, vol. C1). The kinetics of the reaction of hydrogen on uranium is discussed

Compounds of uranium

329

in detail in Chapter 29, describing the handling, storage, and disposition of plutonium and uranium. This topic will therefore not be developed here. (a)

Preparative methods

b‐UH3 forms rapidly as fine black or dark gray powder when uranium turnings or powder, as well as large massive lumps, are heated to 250 C in a vacuum followed by the introduction of H2 gas into the reaction system (Spedding et al., 1949; Libowitz and Gibb. Jr, 1957). Crystalline b‐UH3 may be prepared as gray, fibrous crystals at 30 atm H2 and 600–700 C in an autoclave using a uranium nitride crucible as the primary container inside the pressure vessel. a‐UH3 can only be prepared by slow reaction at temperatures below about 80 C. The a‐phase is unstable, and the products are usually a mixture with more than 50% b‐UH3 (Mulford et al., 1954; Abraham and Flotow, 1955). Purer a‐UH3 has been obtained by the diffusion method: Fine reactive uranium metal powder, formed by thermal decomposition of b‐UH3, was kept below 78 C in an Ar (or He) filled cryostat at a pressure of 0.25–0.40 atm, to which H2 was introduced with an adequately low rate (reaction period: 20 days). More than 80% of the product was a‐UH3 (Wicke and Otto, 1962). (b)

Crystal structures

a‐UH3 is cubic with space group Pm3n. Two uranium atoms occupy (0,0,0) and (1/2,1/2,1/2), and six hydrogen atoms (1/4,0,1/2), (1/2,1/4,0), and (0,1/2,1/ 4) positions. The crystallographic data are listed in Table 5.10. b‐UH3 also has a cubic structure with space group Pm3n, the same as in a‐UH3, but with different atom positions, 2UI in (0,0,0) and (1/2,1/2,1/2), and Table 5.10 Crystallographic data of uranium hydrides.

˚) a (A

z

X‐ray density (g cm–3)

Compound

Symmetry

Space group

a‐UH3

cubic

Pm3n

4.160(1)

2

11.12

a‐UD3

cubic

Pm3n

4.153(2) 4.150

2

11.34

a‐UT3 b‐UH3 b‐UD3 b‐UT3

cubic cubic cubic cubic

Pm3n Pm3n Pm3n Pm3n

4.147(3) 4.142(2) 6.6444(8) 6.633(3) 6.625(3)

2 8 8 8

11.36 11.55 10.92 11.11 11.29

References Mulford et al. (1954); Wicke and Otto (1962); Caillat et al. (1953) Wicke and Otto (1962); Grunzweig‐Genossar et al. (1970); Johnson et al. (1976) Johnson et al. (1976) Rundle (1947, 1951) Rundle (1947, 1951) Johnson et al. (1976)

330

Uranium

Fig. 5.12 Hydrogen pressure versus composition isotherms for the system U–UH3–H2. Formation and decomposition curves at 369 C: Wicke and Otto (1962); 450 and 500 C curves: Libowitz and Gibb, Jr. (1957); 595.9, 712, and 846.2 C curves: Northrup, Jr. (1975).

6UII in (1/4,0,1/2) and their equivalent positions. The hydrogen position was determined by neutron diffraction of b‐UD3 (Rundle, 1951). The hydrogen atoms are located in the 24(k) position, where each hydrogen atom is equidistant from four uranium neighbors within the experimental error, i.e., 12HI in (5/16,0, 5/32) and 12HII in (11/32, 1/2,3/16). (c)

Phase relations and dissociation pressures

A pressure–composition (isotherm) diagram of the U–UH3–H2 system is shown in Fig. 5.12; the region of the existence of a‐hydride phase is not given because this phase is unstable and transforms irreversibly to b‐UH3 at higher

Compounds of uranium

331

Fig. 5.13 Phase diagram of the uranium–hydrogen system in the range H/U ¼ 2.3–3.0 ( from Flotow et al., 1984). UHs (a, b, and g) represent uranium metal phases (a, b, and g), respectively, with dissolved hydrogen.
: Besson and Chevallier (1964); ○: Libowitz and Gibb, Jr. (1957); □: Northrup, Jr. (1975); 4: Lakner (1978). Reproduced by the permission of the Atomic Energy Agency, Vienna.

temperatures. The equilibrium H2 pressure over a‐UH3 is much higher than that over b‐UH3, but no quantitative data are available. The rate of the a ! b transformation is relatively low; a‐UH3 changes to b‐UH3 in a few hours at 250 C (Wicke and Otto, 1962). The b‐hydride phase, b‐UH3–x, has a relatively wide range of hydrogen hypostoichiometry at higher temperatures. The slight hyperstoichiometry at 846.2 C shown in Fig. 5.12 is an experimental artefact caused by hydrogen permeation from the sample vessel (Northrup, Jr., 1975). Fig. 5.13 shows the hypostoichiometric range for uranium trihydride up to 1300 K (Flotow et al., 1984). At 1280 K, the lower limit of the b‐hydride phase attains to UH2.3. The solubility of hydrogen in uranium metal increases with increasing temperature (Fig. 5.12). The data determined by Mallett and Trzeciak (1958) obey Sieverts law. a‐U: log SðH=UÞ ¼ 1=2 log pH2 ðatmÞ  2:874  388 T 1 ðT < 942 KÞ; b‐U: log SðH=UÞ ¼ 1=2 log pH2 ðatmÞ  1:778  892 T 1 ð942 < T < 1049 KÞ; g‐U: log SðH=UÞ ¼ 1=2 log pH2 ðatmÞ  2:238  227 T 1 ð1049 < T < 1408 KÞ; Liquid U: log SðH=UÞ ¼ 1=2 log pH2 ðatmÞ  1:760  587 T 1 ðT > 1408 KÞ;

Uranium

332

where S is the solubility measured as the atom ratio. It may be noteworthy that finely divided uranium chemisorbs much larger amounts of hydrogen than those given by the previous equations (e.g. about 100 times larger at 295 C and 0.15 mmHg H2). Below 400 C the hydrogen pressure for formation of hydrides is not the same as that for the decomposition in the region of two solid phases (plateau region). Spedding et al. (1949) reported that the decomposition and formation pressures at 357 C were 0.176 and 0.188 atm, respectively. Wicke and Otto (1962) indicated that this difference is 170% at 369 C as shown in Fig. 5.12. Various explanations of the hysteresis and the dip in the decomposition process have been proposed (Libowitz, 1968; Condon and Larson, 1973); there is a possibility that traces of oxygen play a role. Using very pure uranium samples, no evidence of hysteresis was found and the time to attain equilibrium was quite short (Meusemann and von Erichsen, 1973; Condon, 1980). The plateau hydrogen pressures are given by the equation ln pðatmÞ ¼ A  BT 1 where A ¼ 14.55 and B ¼ 10233 for UH3 in the temperature range 298–942 K (Chiotti, 1980). For uranium trideuteride, UD3, Flotow et al. (1984) assessed the measured data by Spedding et al. (1949), Wicke and Otto (1962), Destriau and Se´riot (1962), and Carlson (1975), and recommended the values A ¼ 15.046 and B ¼ 10362 (500–800 K), which were obtained by averaging the results of Spedding et al. (1949) and Wicke and Otto (1962). The data for uranium tritritide, UT3, are meager. The recommended A and B values (Flotow et al., 1984) are those obtained by averaging the results of Flotow and Abraham (1951) and of Carlson (1975); they are A ¼ 14.57 and B ¼ 9797 in the temperature range 600–800 K. The above equilibrium pressures are considerably lower than the pressures derived from calorimetric data for UH3, UD3, and UT3 (Flotow et al., 1984). (d)

Thermodynamic properties

The heat capacity, entropy, and enthalpy of formation of UH3, UD3, and UT3 (b forms) at 298 K are listed in Table 5.11.

Table 5.11 Heat capacity, entropy, and enthalpy of formation of b‐UH3, b‐UD3, and b‐UT3 at 298.15 K (Flotow et al., 1984). Compound

C p ð298:15 KÞ (JK–1 mol–1)

So (298.15 K) (JK–1 mol–1)

D f H o (298.15K) (kJ mol–1)

b‐UH3 b‐UD3 b‐UT3

49.29 0.08 64.98 0.08 74.43 0.75

63.68 0.13 71.76 0.13 79.08 0.79

– 126.98 0.13 – 129.79 0.13 –130.29 0.21

Compounds of uranium

333

Flotow and Osborne (1967) and Flotow et al. (1959) have measured the low‐temperature heat capacity of UH3(b) from 1.4 to 23 K and from 5 to 350 K, respectively. Abraham et al. (1960) have reported the low‐temperature heat capacity of UD3 from 5 to 350 K and Ward et al. (1979) that from 4 to 17 K. Although no experimental heat capacity data have been published for UT3(b), Flotow et al. (1984) obtained the estimated Cp values using semiempirical equations to estimate the optical mode contributions of the hydrogen lattice vibrations. Abraham et al. (1960) found that the sum of the lattice heat capacity associated with the acoustic modes, the electronic heat capacity, and the magnetic heat capacity, agreed within 0.08 JK–1 mol–1 for UH3(b) and UD3(b), which means that this part of heat capacity is virtually the same for UH3, UD3, and UT3. Moreover, they showed that this could be represented by a linear function of temperature. On this basis, Flotow et al. (1984) calculated the optical mode contributions of UT3 by using the Einstein heat capacity function to estimate the heat capacity of UT3. The heat capacity of UH3 and UD3 up to 800 K was also obtained by this method as shown in Fig. 5.14. The sharp anomaly in the vicinity of 170 K is due to the ferromagnetic–paramagnetic transition of the b‐hydride phases. (e)

Electrical resistivity

The electrical resistivity, r, of b‐hydride increases with increasing temperature as in metals. Ward et al. (1979) measured the electrical resistivity of b‐UD3 from 2.4 to 300 K. The r vs T curve has an anomaly due to a magnetic transition at 166 K. These resistivities are in good agreement with the unpublished data of Flotow for b‐UH3 communicated to Grunzweig‐Genossar et al. (1970). The resistivity of b‐hydride is about ten times higher than that of uranium metal. (f)

Magnetic properties and the nature of bonding

The history of magnetic studies of uranium hydrides is described in the review of Troc´ and Suski (1995). In the earlier work, a‐UH3 was considered to be ferromagnetic at low temperatures with TC the same as, or close to that of b‐UH3. However, the neutron diffraction study on a‐UD3 (Lawson et al., 1991) revealed the a‐hydride phase to be non‐magnetic at least above 15 K, i.e. the apparent ferromagnetism was due to b‐hydride impurities in the a‐hydride samples. b‐Hydride is ferromagnetic at low temperatures. The magnetic data for b‐UH3 and b‐UD3 are shown in Table 5.12. At the Curie temperature, the l‐type heat capacity anomaly has also been observed at 170.5 and 167.6 K for b‐UH3 and b‐UD3, respectively (Fig. 5.14). The lower Curie temperature in the deuteride is associated with the somewhat shorter U–U distance, resulting in a change of the exchange integrals for the Weiss field (Ward, 1985). The electrical

334

Uranium

Fig. 5.14 Heat capacities of UH3(b), UD3(b), and UT3(b) (Flotow et al., 1984).

resistivity for b‐UD3 changed at the Curie temperature (166 K) (Ward et al., 1979). Andreev et al. (1998) report that the Curie temperature of b‐UH3 decreases with increasing external pressure from 175 K (0 kbar) to 169 K (8 kbar). In Table 5.12, the saturation uranium magnetic moments obtained by neutron diffraction are far larger than those obtained by magnetization measurements, possibly a result of a large magnetic anisotropy in b‐UH3 (Bartscher et al., 1985). The neutron diffraction studies of b‐UH3 carried out at the ferromagnetic temperatures revealed that the two UI and six UII atoms, which occupy different crystallographic positions in space group Pm3n, are magnetically equivalent giving the same magnetic moment; no (110) reflection peak was observed in the diffraction patterns (Wilkinson et al., 1955; Bartscher et al., 1985; Lawson et al., 1990). Increased external pressure lowers the saturation magnetic moment of uranium from 1mB (0 kbar) to 0.985mB (10 kbar) at 4.2 K (Andreev et al., 1998). The effective uranium moments in Table 5.12 are those obtained from the slope of the Curie–Weiss curves in the paramagnetic range of temperatures.

173 180 176

172 175.2 166

172

177.5

b‐UD3

ND: neutron diffraction.

178

174

174 173 181 168 181 175 175

b‐UH3

Hydride

Paramagnetic Curie temperature yp ðKÞ

Ferromagnetic Curie temperature TC ðKÞ

0.87 (5.34 T) 1.39 (ND) 1.45 (ND, 10 K)

0.98 (6 T, 1.3 K)

0.65 (80 K) 0.9 (78 K) 0.9 (2.1 T, 4.2 K) 1.18 (6 T, 1.3 K) 0.7 1.0 (40 T, 4.2 K) 1.39 (ND) 1.45 (NMR) 1.54 (ND)

Saturation uranium moment mS ðmB Þ

2.24 2.26

2.44

2.24

2.44 2.79

Effective paramagnetic uranium moment meff ðmB Þ

Table 5.12 Magnetic data for b‐UH3 and b‐UD3.

Trzebiatowski et al. (1954) Gruen (1955) Lin and Kaufmann (1956) Henry (1958) Karchevskii and Buryak (1962) Andreev et al. (1998) Shull and Wilkinson (1955) Barash et al. (1984) Lawson et al. (1990) Trzebiatowski et al. (1954) Henry (1958) Karchevskii and Buryak (1962) Ward et al. (1979) Wilkinson et al. (1955) Bartscher et al. (1985)

References

Uranium

336

Grunzweig‐Genossar et al. (1970) assume that uranium is composed of uranium ions and protons (deuterons) in a high‐density interacting electron gas. The magnetic moments arise from 5f electrons. The uranium ions are magnetically coupled through the polarized conduction electrons by the RKKY interaction, which can explain the ferromagnetic ordering below 180 K and the large Knight shift obtained by their nuclear magnetic resonance (NMR) measurement, i.e. K ¼ 0:40wM , where wM is the molar magnetic susceptibility. The second moment and line‐shape data suggest that the 5f electrons (Z  2.5 conduction electrons per uranium atom) are localized and do not form a band as in metallic uranium. Cinader et al. (1973) measured the NMR spin‐lattice relaxation time in the paramagnetic state at 189–700 K. In addition to the time‐dependent dipolar interaction through hydrogen diffusion, the relaxation time was dependent on (1) the direct interaction between the conduction electrons and the protons (deuterons) causing Korringa relaxation, and (2) the indirect RKKY (Ruderman-Kittel-Kasuya-Yosida) interaction. The density of states of the s‐type conduction electrons at the Fermi level was 1.65 states per eV. A model with a spherical Fermi surface and free electron behavior in the RKKY interaction, results in U3þ and H– as the ionic species. (g)

Chemical properties

Uranium hydride is very reactive and, in most respects its reactions resemble those of the finely divided uranium metal; in fact, reactions that occur at temperatures where the hydrogen decomposition pressures are high may be those of the metal. Uranium hydride ignites spontaneously in air, but gradual oxidation at low oxygen pressures at room temperature results in the formation of a protective film of oxide on the surface of hydride particles, which prevents the hydride from ignition. Adsorption of a variety of electron‐pair‐donor compounds can reduce the pyrophoric properties. Uranium hydride is used as a starting material in many reactions, including the preparation of finely divided uranium metal. Hydrogen, deuterium, and tritium may be stored as UH3, UD3, and UT3, respectively. These gases are released when the compounds are heated to the decomposition temperatures. Gram quantities of UH3 reacts slowly with water, but larger samples react violently and produce high temperatures (Newton et al., 1949). UH3 reacts slowly with solution of non‐oxidizing acids such as HCl and weak acids such as CH3COOH, but vigorously with HNO3. UH3 reacts with H2SO4 to form S, SO2, and H2S, and with H3PO4 to form UPO4. UH3 is unstable in strong bases and reduces aqueous solutions of AgNO3 and HgCl2. At elevated temperatures, UH3 reacts with O2, hydrogen halides, H2S, HCN, NH3, N2, CO2, CH4, and C2H2 (acetylene), but not with liquid hydrocarbons and chlorinated solvents, although an explosive reaction occurs with CCl4. The reactions of UH3 with most compounds are thermodynamically favored, and many cases where the

Compounds of uranium

337

Table 5.13 Reactions of uranium hydride. Reagent O2 H2O H2S N2 NH3 PH3 Cl2 CCl4 HCl HF Br2 HBr CO2

Reaction temperature ( C) ignites at room temperature 350 400–500 250 250 400 250 250 possibility of explosion at 25 C 250–300 200–400 300–350 300 300

Product U3O8 UO2 US2 U2N3 U2N3 UP UCl4 UCl4 UCl3 UF4 UBr4 UBr3 UO2

reactions do not proceed are a result of kinetic inhibition (Haschke, 1991). Typical reactions of uranium hydride are given in Table 5.13.

(h)

Other uranium hydride compounds

(i) Uranium(IV) borohydride, U(BH4)4 The volatile U(BH4)4 is obtained as dark green crystals by the reaction UF4 þ 2AlðBH4 Þ3 ! UðBH4 Þ4 þ 2AlðBH4 ÞF2 : Purification is made by vacuum sublimation (Schlesinger and Brown, 1953). U(BH4)4 is tetragonal with space group P43212 having four formula units ˚ and c ¼ in the unit cell. The lattice parameters are a ¼ (7.49 0.01) A ˚ (13.24 0.01) A. The positions of U, B, and H have been determined by X‐ray and neutron diffraction analyses (Bernstein et al., 1972a,b). In vacuo and in an inert‐gas atmosphere, U(BH4)4 is fairly stable, but it is immediately decomposed by oxygen or moisture. Bernstein and Keiderling (1973) determined the molecular structure from optical and nuclear magnetic resonance spectra. The vapor pressure of U(BH4)4 is given by the equation log pðmmHgÞ ¼ 13:354  4265T 1 : U(BH4)3 is a red solid, which has been observed as a by‐product in the synthesis of U(BH4)4. Because of its pyrophoric properties, it has not been well characterized (Schlesinger and Brown, 1953).

338 (ii)

Uranium UNiAlHy and related compounds

The intermetallic compounds UXAl (X ¼ Ni, Co, Mn) absorb hydrogen on heating in the temperature range 20–250 C at high H2 pressures. The maximum hydrogen content attained at 20 C corresponds to UNiAlH2.74 (pH2 ¼ 55 atm), UCoAlH1.2 (40 atm), and UMnAlH0.15 (40 atm) (Drulis et al., 1982). UNiAl absorbs the largest amount of hydrogen in these compounds, though lower maximum hydrogen absorption values have been reported, at room temperature and 70 atm viz. UNiAlH2.5 (Jacob et al., 1984), and UNiAlD2.2 at 30 C and 50 atm D2 (Yamamoto et al., 1998). The lower limit of the hydride phase is y ¼ 0.7–0.8 (Yamamoto et al., 1994, 1998; Yamanaka et al., 1999). The hydrogen solubility in the UNiAl metal appears to obey Sieverts law in the hydrogen concentration region below 0.02 H per formula unit UNiAl (Yamanaka et al., 1999). The symmetry and space group of UNiAlHy are the same as those for UNiAl. The structure consists of alternate planes containing three Al (in 3f) and two Ni (2c) atoms at z ¼ 0 and three U (3g) and one Ni (1b) atoms at z ¼ 1/2. The hydrogen atoms are located in the center of one of the adjacent U3Ni tetrahedra, in the bipyramid U3Al2, and in the bipyramid Al3Ni2 (Kolomiets et al., 2000). The lattice parameter a increases whereas b decreases slightly with increasing value of y (Drulis et al., 1982; Jacob et al., 1984; Yamamoto et al., 1994; Yamanaka et al., 1999; Kolomiets et al., 2000). This variation, expressed ˚ , is approximately represented by the equations a ¼ 6.736 þ 0.187y and c ¼ in A 4.037 – 0.028y in the range 0.8  y  2.7. The hydrogenation of UNiAl is accompanied by a volume change. The quotient DV =V attains a value of 0.124 for both hydride (y ¼ 2.3) and deuteride (y ¼ 2.1). In addition, the X‐ray diffraction peak intensities indicate a positional shift of the U atoms from (0.572, 0, 1/2) in UNiAl to (2/3, 0, 1/2) in UNiAlH2.3. These changes are supposed to favor the accommodation of a larger amount of hydrogen (Kolomiets et al., 2000). The desorption isotherms of UNiAlHy have two sloping plateaus, which suggests the existence of two hydride phases (Jacob et al., 1984). The partial molar enthalpy and entropy of hydrogen for the non‐stoichiometric UNiAlHy –1   varies with the y value. DHðH and 2 Þ and DSðH2 Þ were –53 kJ (mol H2) –1 –1 –88 J K (mol H2) , respectively, for UNiAlH1.35, and –41 kJ (mol H2)–1 and –95 J K–1 (mol H2)–1 for UNiAlH2.30 (Drulis et al., 1982). The values measured by Jacob et al. (1984) are comparable with the above values: –1   DHðH and –90 J K–1 (mol H2)–1, res2 Þ and DSðH2 Þ were 64 kJ (mol H2) 1.2 pectively, for UNiAlH , and 47 kJ (mol H2)–1 and –94 J K–1 (mol H2)–1, respectively, for UNiAlH2.0. The incorporation of hydrogen into UNiAl leads to a large increase in the antiferromagnetic ordering temperature from 19 K to 90–100 K. The transition temperatures for UNiAlH2.3 and UNiAlD2.1 are 99 and 94 K, respectively (Kolomiets et al., 2000). According to Zogal et al. (1984), UNiAlH1.9 has

Compounds of uranium

339

magnetic transitions at 122 and 34 K, where the second transition possibly refers to the hydride at the lower phase limit. The magnetic susceptibility in the paramagnetic region is represented by the modified Curie–Weiss equation. The effective moment, meff ; the paramagnetic Curie temperature, yp ; and the temperature‐independent susceptibility, wo ; are 2.42 mB =f:u:; –42 K and 7  109 m3 mol1 ; respectively, for UNiAlH2.3. The values are 2.43 mB =f:u:; –50 K and 8  109 m3 mol1 ; respectively, for UNiAlD2.1 (Kolomiets et al., 2000). U(Fe1–xNix)Al with x  0.7 absorbs hydrogen forming U(Fe1–xNix)AlHy hydrides. Raj et al. (2000) studied the magnetic properties of U(Fe0.3Ni0.7) AlHy, and found that no other hydride phase was formed above or below y ¼ 0.8. U(Fe0.3Ni0.7)AlHy is ferromagnetic with TC ¼ 15 K (y ¼ 0) and 90 K (y ¼ 0.8). Magnetization of U(Fe0.3Ni0.7)Al at 5.5 T gave a saturation moment of ffi 0:3mB =f:u: The value for the hydride ( y ¼ 0.8) was much higher, ffi 0:9mB =f:u:, indicating considerable increase in the ferromagnetic correlations. Other intermetallic hydrides, e.g. U5Ni4PdH1.0 (Drulis et al., 1982), UCoH2.7 (Andreev et al., 1986; Yamamoto et al., 1991), and UTi2Dy (Yamamoto et al., 1995) have also been studied. 5.7.2 (a)

The uranium–oxygen system

Binary uranium oxides

(i) Preparative methods Comprehensive information on the preparation of actinide oxides including uranium oxides is given in a monograph by Morss (1991). UO(s) Although UO gas is one of the main species over U(l)þUO2–x at high tempera˚ ) with NaCl‐type structure is very unstable tures, solid UO (Fm 3m, a ¼ 4.92 A and its formation has not been definitely established. When UO2 was heated with uranium metal at high temperatures, a fcc phase was produced only in cases of considerable carbon contamination (Rundle et al., 1948). Carbon is thought to promote the reaction. It is possible that UC or UN must be present for the formation of the UO phase (Rundle et al., 1948; Cordfunke, 1969). UO2(s) UO2 is prepared by hydrogen reduction of UO3 or U3O8 between 800 and 1100 C (Katz and Rabinowitch, 1951; Belle, 1961; Wedermeyer, 1984). The H2 gas used for this purpose should not contain impurity of O2 in order to avoid oxidation to hyperstoichiometric UO2þx, which occurs on cooling at temperatures below 300 C. The UO2 pellets for reactor fuel are reduced at much higher temperatures around 1700 C in order to approach the theoretical density. For laboratory use, other reductants such as CO, C, CH4, and C2H5OH may be

340

Uranium

used, but they offer no advantages over H2 (Katz and Rabinowitch, 1951; Wedermeyer, 1984; Roberts and Walter, 1966). NH3 is not suitable (Belle, 1961). Commercial methods of UO2 synthesis start from the peroxide UO4 · 2H2O, ammonium diuranate with the approximate composition (NH4)2U2O7 or ammonium uranyl carbonate (NH4)4UO2(CO3)3 followed by air calcination at 400–500 C. Subsequent H2 reduction at 650–800 C yields UO2 with high surface area. The nuclear fuel pellets are produced by cold pressing of these powders, followed by sintering. U4O9(s) U4O9 can be prepared from the stoichiometric amounts of UO2 and U3O8 according to the reaction 5UO2 þ U3O8 ¼ 2U4O9. The reactants are ground in an agate mortar and the mixture is sealed in an evacuated quartz ampoule, and then heated at 1000 C for about 2 weeks until the sample is completely homogenized. The sample is slowly cooled to room temperature over a period of 2 weeks (Gotoo and Naito, 1965; Westrum, Jr. et al., 1965). U4O9 has three phases: a‐U4O9 that transforms into b‐U4O9 on heating to 350 K, and b‐U4O9 that transforms into g‐U4O9 at 850 K (Labroche et al., 2003b). These transformations are reversible. U3O7(s) Three polymorphs of a, b, and g are known for U3O7; all of them are tetragonal. a‐U3O7 with c/a ratios 0.986–0.991 is prepared by oxidizing UO2 at temperatures below 160 C (Hoekstra et al., 1961; Westrum, Jr. and Grønvold, 1962). To prepare a single phase with O/U 2.33, the use of reactive UO2, which is obtained by low‐temperature reduction of UO3 by H2, is recommended (Hoekstra et al., 1961). Oxidation of UO2 in air at 200 C yields b‐U3O7 with c/a ratios between 1.027 and 1.032 (Garrido et al., 2003). The oxidation of standard uranium dioxide ceases at UO2.33 at temperatures below 200 C and no formation of U3O8 takes place (Hoekstra et al., 1961). Allen and Tyler (1986) report that well‐crystallized single‐phase b‐U3O7 was obtained by oxidation at 230 C for 16 h. The g‐U3O7 (U16O37) phase, which has c/a ratios of 1.015–1.017 and smaller O/U ratios of 2.30–2.31 (Hoekstra et al., 1961; Westrum, Jr. and Grønvold, 1962; Hoekstra et al., 1970; Nowicki et al., 2000), is formed when U4O9 is oxidized at 160 C (Hoekstra et al., 1961). This compound has also been prepared as a mixture with monoclinic U8O19 on heating a pellet of mixed UO2 and UO3 at 400 C under high pressures (15–60 kbar) (Hoekstra et al., 1970). U2O5(s) High‐pressure syntheses by Hoekstra et al. (1970) identified three U2O5 phases (a‐U2O5, b‐U2O5 and g‐U2O5). a‐U2O5 was prepared by heating a mixture of UO2 and U3O8 at 400 C and 30 kbar for 8 h. At 500 C, a pressure of 15 kbar was enough to prepare a‐U2O5. Hexagonal b‐U2O5 is formed at 40–50 kbar pressure at temperatures higher than 800 C. Monoclinic g‐U2O5 was sometimes

Compounds of uranium

341

Fig. 5.15 Flow sheet for the preparation of various UO3 modifications: Bold lines refer to high O2 pressure (Hoekstra and Siegel, 1961; Cordfunke, 1969).

obtained when the UO2 and U3O8 mixture was heated above 800 C at a pressure of 60 kbar. U3O8(s) a‐U3O8 is prepared by oxidation of UO2 in air at 800 C followed by slow cooling (Loopstra, 1970a). b‐U3O8 is prepared by heating a‐U3O8 to 1350 C in air or oxygen, followed by slow cooling (cooling rate: 100 K per day) to room temperature (Loopstra, 1970b). UO3(s) Seven modifications are known for UO3: A, a, b, g, d, ε, and z‐UO3. The methods of their syntheses are outlined in the flow sheet of Fig. 5.15 (Hoekstra and Siegel, 1961; Cordfunke, 1969). Amorphous UO3 (A‐UO3) forms when any of the compounds UO4 · 2H2O (washed with H2O), UO3 · 2H2O, UO2C2O4 · 3H2O and (NH4)4UO2(CO3)3 is heated in air at 400 C. Because of the difficulty to remove residual traces of nitrogen and carbon, it is preferable to use either of the first two of the above

342

Uranium

compounds (Hoekstra and Siegel, 1961). a‐UO3 is prepared by crystallization of A‐UO3 at 485 C for 4 days. The heating time can be shortened at 500 C but a pressure of 40 atm oxygen is then needed (Hoekstra and Siegel, 1961). b‐UO3 is prepared by heating ‘ammonium diuranate’ or uranyl nitrate rapidly in air at 450–500 C. The crystallinity of b‐UO3 is improved by keeping the sample at 500 C (not higher) for 4–6 weeks (Debets, 1966). This compound is also obtained by heating at 500–550 C under 30–40 atm O2. g‐UO3 is formed slowly at 500–550 C in 6–10 atm O2. At 650 C and 40 atm O2, all a, b, d, and ε‐UO3 compounds convert to the g‐phase. g‐UO3 can be prepared directly in air by heating uranyl nitrate hexahydrate to 400–600 C (Hoekstra and Siegel, 1958; Engmann and de Wolff, 1963). Stoichiometric d‐UO3 is obtained by heating b‐UO2(OH)2 (¼ b‐UO3 · H2O) at 375–400 C for more than 24 h (Hoekstra and Siegel, 1961). At 415 C, the oxygen‐deficient d‐phase forms (Wait, 1955). ε‐UO3 is prepared by oxidizing U3O8 at 350 C in NO2(g). The reaction goes to completion in a few seconds (Gruen et al., 1951). At a temperature of 400 C, the reaction rate levels off as the stability limit of ε‐UO3 is approached (Hoekstra and Siegel, 1961). The high‐pressure modification z‐UO3 forms at 30 kbar and 1100 C (Hoekstra et al., 1970). UO3 hydrates The existence of six compounds, i.e. UO3 · 2H2O, a‐UO3 · 0.8H2O, a‐ UO2(OH)2, b‐UO2(OH)2, g‐UO2(OH)2, and U3O8(OH)2, has been confirmed in the UO3–water system. UO3 · 2H2O is prepared by exposure of anhydrous UO3 to water at 25–75 C. An alternative method is to add 0.65 g La(OH)3 to 50 mL 0.2 M UO2(NO3)2 solution. The hydroxide dissolves slowly, accompanied by an increase in solution pH from 2.2 to 4.0. Digestion of the clear solution at 55 C causes a gradual precipitation of a portion of the uranium as bright yellow crystals of UO3 · 2H2O (Hoekstra and Siegel, 1973). Water‐deficient a‐phase monohydrate, a‐UO3 · 0.8H2O, was prepared by heating UO3 · 2H2O in air at 100 C or by heating either UO3 · 2H2O or UO3 in water at 80–200 C (Dell and Wheeler, 1963). Stoichiometric a‐UO2(OH)2 (¼ a‐UO3 · H2O) was prepared in hydrothermal experiments at temperatures approaching 300 C (Harris and Taylor, 1962; Taylor, 1971). Stoichiometric b‐UO2(OH)2 (or b‐UO3 · H2O) is prepared by the action of water on UO3 · 2H2O or UO3 at 200–290 C in a sealed reactor (Dawson et al., 1956). It is also formed by the hydrolysis of uranyl salt solutions (cf. g‐UO2(OH)2). g‐UO2(OH)2 (or g‐UO3 · H2O) is obtained when 0.65 g La(OH)3 is added to 50 mL of 0.2 M UO2(NO3)2 and subsequent heating of the solution to 80–90 C; digestion of the solution leads to slow precipitation of g‐UO2(OH)2 (Hoekstra and Siegel, 1973). There may be no region of true thermodynamic stability for the g‐phase. Continued digestion for several weeks eventually gives b‐UO2(OH)2 as the sole product. U3O8(OH)2 (¼ UO3 · 1/3H2O or H2U3O10, i.e. hydrogen triuranate) is prepared by hydrothermal reaction of UO3 · 2H2O or UO3 at temperatures between 300 and 400 C. Although no solid solution range

Compounds of uranium

343

has been observed for this compound, appreciable variations in water content from 0.33 to 0.50 have been reported (Siegel et al., 1972). Uranium peroxide tetrahydrate, UO4 · 4H2O, is obtained when the precipitate, grown from the uranyl nitrate solution of pH ¼ 2 on addition of hydrogen peroxide solution, is dried at room temperature (Silverman and Sallach, 1961); the dihydrate, UO4 · 2H2O, is prepared by heating UO4 · 4H2O at 90 C. (ii)

Preparation of single crystals

The basic method to prepare single crystals of UO2 is to melt UO2 powders. Arc melting (Brit and Anderson, 1962) and solar furnace heating (Sakurai et al., 1968) techniques have been adopted for this purpose. The vapor deposition method has also been used, where an electric current was passed through a hollow cylinder of UO2. UO2 sublimed from the hot central part of the inner surface of the cylinder and deposited at the cooler end, forms large hemispherical single crystals of 4–12 mm (van Lierde et al., 1962). Recrystallization also yields single crystals in the central part of UO2 rod when the current is directly passed through the specimen (Nasu, 1964). Single crystals of the length 5 cm have been prepared by means of the floating zone technique. In this case, the preheated UO2 rods were heated by induction eddy‐currents (Chapman and Clark, 1965). Robins (1961) obtained single crystals of 3 mm length by electrolysis of uranyl chloride in fused alkali chloride melts. Formation of single crystals by chemical transport reactions has been studied by a number of researchers. Naito et al. (1971) examined the transport of UO2, U4O9, and U3O8 from 1000 to 850 C in sealed quartz tubes using the transporting agents HCl, Cl2, I2, Br2, and Br2þS2. Although the transport rate was very low in I2 (0.002 mg h–1), it was high enough in Cl2 of 4 mmHg pressure (23 mg h–1) and in Br2þS2 with partial pressures (2.5 ± 0.2) mmHg (12.5 mg h–1) to obtain single crystals. Single crystals of UO2 were deposited on UO2 substrates with (100) and (111) orientations by the chemical transport method using Cl2 as the transporting agent (Singh and Coble, 1974). At Cl2 pressures below 10 mmHg and high substrate temperatures (>950 C), good single crystals free from cracking caused by epitaxial growth were obtained. Faile (1978) reported the formation of large single crystals of UO2 by the use of TeCl4 as transport agent. UO2 was transported in a sealed fused quartz tube from the source end at 1050 C over a temperature gradient to the deposition end at 950 C. The maximum weight of the obtained single crystals was 1 g. TeCl4 has also been used successfully for the preparation of single crystals of other actinide dioxides (Spirlet et al., 1979). (iii)

Crystal structures

The crystal structures of uranium oxides in the composition range 2.00  O/U  2.375, which includes UO2 and polymorphs of U4O9 and U3O7, are closely related to the fluorite structure. On the other hand, the crystal structures of

344

Uranium

U3O8 and many of the UO3 polymorphs are based on the layer structures, which are characterized by the existence of UO2þ 2 uranyl groups arranged normal to the plane of the layers. The lattice parameters of the uranium oxides are shown in Table 5.14. UO2, UO2þx Stoichiometric uranium dioxide crystallizes in a fcc structure (space group Fm 3m), where the uranium atoms occupy the positions 0,0,0; 1/2,1/2,0; 1/2, 0, 1/2 and 0, 1/2, 1/2 and the oxygen atoms occupy the 1/4, 1/4, 1/4 and its equivalent positions. As the temperature is raised, the anisotropic thermal vibration causes the oxygen atoms to move to the 1/4 þ d, 1/4 þ d, 1/4 þ d positions, where d ¼ (0.016 0.001) at 1000 C (Willis, 1964a). In the hyperstoichiometric uranium dioxide, UO2þx, the interstitial oxygen atoms occupy two different sites of the UO2 lattice, which are displaced by ˚ along the and directions from the cubic coordinated about 1 A interstitial position. These oxygen atoms are denoted as O0 and O00 , respectively. Together with these interstitial atoms, it was observed that vacancies were formed at the normal oxygen sites, although the uranium sublattice remained undisturbed (Willis, 1964b). Willis (1978) later analyzed the neutron diffraction data for UO2.12 at 800 C by taking into account the anharmonic contribution to the Debye–Waller factor. The occupancy numbers of O0 and O00 and the vacant lattice oxygens were calculated to be equal within one standard deviation, indicating that the defect complex has a 2:2:2 configuration of oxygen defects. The two O00 oxygen atoms displace two normal oxygen atoms forming two O0 atoms and two oxygen vacancies. A model that assumes a chain‐like coordination of the 2:2:2 clusters along directions has been proposed (Allen et al., 1982). However, it failed to give a satisfactory agreement between the observed and calculated neutron intensities (Willis, 1987). There may be a similarity between the clusters present in UO2þx and Fe1–xO. In the non‐stoichiometric Fe1–xO, the Roth clusters (Roth, 1960) or Koch–Cohen clusters (Koch and Cohen, 1969) are thought to be statistically distributed. These clusters have different structures but their compositions are close to that of Fe3O4 (Anderson, 1970), which is formed as an ordered phase when the concentration of clusters exceeds a certain value. In the case of UO2þx, the possibility of disordered arrangement of cuboctahedral clusters exists, as U4O9 might be composed of ordered cuboctahedral clusters. U4O9 The low‐temperature phase a‐U4O9 transforms to b‐U4O9 at 340–350 K, which is accompanied by an anomaly in the specific heat at 348 K (Westrum, Jr. et al., 1965) or 330 K (Gotoo and Naito, 1965) and of a dilatation at 293–359 K (Grønvold, 1955). The lattice parameter decreases with increasing temperature in this range (Ferguson and Street, 1963), but no anomaly was observed in the

tetragonal monoclinic

black

black

black

black

black

black

b‐U3O7

g‐U3O7 (U16O37) a‐U2O5

b‐U2O5

g‐U2O5

U13O34

Cmcm (or Cmc or Ama)

tetragonal

black

a‐U3O7

orthorhombic

monoclinic

hexagonal

tetragonal

tetragonal monoclinic

black black

bcc

I 43d

U16O37(*) U8O19(*)

fcc

Fm3m

U4O9

3138

brown to black black

Symmetry

Space group

UO2

m.p.(K)

Color

Formula

6.740

5.410

3.813

12.40

5.407

5.383

5.447

5.407 5.378

5.441  4

5.4704

˚) a (A

3.96413

5.481

5.074

5.559

˚) b (A

Lattice parameters

4.1432

5.410

13.18

5.675

5.497

5.547

5.400

5.497 5.378

˚) c (A

b¼ 90.49

b¼ 99.2

b¼ 90.27

Angle (deg)

4

2

2

4

64

4

Z

Table 5.14 Physical properties of the stoichiometric uranium oxides.

10.76 to 11.38 10.36

10.5

10.60

10.62

11.34

10.95

Exp.

Density (g cm3)

8.40

11.51

11.15

10.47

11.366 11.402

10.299

10.964

X‐ray or ND

Spitsyn et al. (1972)

Hoekstra et al. (1970)

Hoekstra et al. (1970); Spitsyn et al. (1972) Hoekstra et al. (1970)

Hoekstra et al. (1961); Westrum, Jr. and Grønvold (1962) Hoekstra et al. (1961); Garrido et al. (2003) Hoekstra et al. (1970)

IAEA (1965); Winslow (1971) IAEA (1965); Ishii et al. (1970a); Bevan et al. (1986) Hoekstra et al. (1970) Hoekstra et al. (1968)

References

723(d) 803(d) 923(d) 673(d)

beige

orange

yellow

deep red

brick red

brown

a‐UO3

b‐UO3

g‐UO3

d‐UO3

ε‐UO3

z‐UO3

orthorhombic

Cmcm

orthorhombic cubic

Fddd Pm3m

P212121

monoclinic

P21

orthorhombic

triclinic

orthorhombic

(C222 derived)

amorphous

orthorhombic

orthorhombic

orthorhombic orthorhombic

Pmma Pnma (or Pna2) C2mm

(d): decomposes. (*): Parameters for these phases refer to a pseudo‐cell.

673(d)

723(d)

A‐UO3

U12O35(*)

b‐U3O8

green black green black olive green orange

a‐U3O8

U8O21 U11O29

7.511

4.002

4.16

9.813

10.34

6.84

6.91

7.069

6.716

6.796 6.765

5.466

3.841

19.93

14.33

43.45

3.92

11.445

11.960

3.9588 3.95611

5.224

4.165

9.711

3.910

4.157

4.16

8.303

4.147

4.1452 4.1402

a¼ 98.10 b¼ 90.20 g¼ 120.17

b¼ 99.03

4

1

1

32

10

19

2

4

2

4 4

8.62

8.54

6.69

7.80

8.25

7.30

6.80

7.72

8.86

8.67

6.60

8.00

8.30

7.44

8.39

8.326

8.395

8.341 8.40

Siegel et al. (1966); Hoekstra et al. (1970)

Hoekstra and Siegel (1961) Siegel and Hoekstra (1971a); Greaves and Fender (1972) Hoekstra and Siegel (1961); Debets (1966) Hoekstra and Siegel (1961); Siegel and Hoekstra (1971b) Wait (1955); Hoekstra and Siegel (1961) Hoekstra and Siegel (1961); Kovba et al. (1963)

Hoekstra et al. (1970)

Loopstra (1970b)

Loopstra (1970b)

Spitsyn et al. (1972) Spitsyn et al. (1972)

Compounds of uranium

347

magnetic susceptibility (Gotoo and Naito, 1965). The transition was claimed to be due to disordering of oxygen with U4þ–U5þ rearrangement (Naito et al., 1967; Fournier and Troc´, 1985). Belbeoch et al. (1967) reported that a‐U4O9 has a rhombohedral structure, slightly distorted from a cubic structure with the lattice parameters a ¼ 5.4438n (n: an integer) and a ¼ 90.078 at 20 C. The transition is possibly of order–disorder type coupled with a small change in crystal structure. Another transition from b‐U4O9 to g‐U4O9 occurs at higher temperatures around 850 K. An X‐ray diffraction analysis showed the transition temperature to be 823–973 K (Blank and Ronchi, 1968), while the heat capacity measurement gave 900–950 K (Grønvold et al., 1970). A transition between 813–893 K was observed for the specimens of 2.228O/U2.25 (Naito et al., 1973) using X‐ray diffraction and electrical conductivity measurements. This b/g transition is assumed to be based on the order–disorder mechanism (Blank and Ronchi, 1968; Naito et al., 1973). According to Seta et al. (1982), there was no clear anomaly or variation in the heat capacity curves in the above temperature range. Instead they observed two small peaks for hypostoichiometric U4O9–y (UO2.22 and UO2.235) at 1000 and 1100 K. The crystal structure of a‐U4O9 has not yet been solved, but it is supposed to be closely related to that of strictly cubic b‐U4O9, with the space group I 43d. Electron diffraction measurements on a‐U4O9 showed that the superlattice reflections all obeyed the special extinction rules for the 4 sites of the space group I  43d (Blank and Ronchi, 1968). Bevan et al. (1986) suggest that a‐U4O9 consists of cuboctahedral clusters centered on 12(a) or 12(b) sites similar to the crystal structure of b‐U4O9, although the anion sublattice may be perturbed. Bevan et al. (1986) collected single‐crystal neutron diffraction data for b‐U4O9 at 230 and 500 C. A partial Patterson synthesis obtained using only the superlattice reflections supported the cuboctahedral cluster model. Fig. 5.16 shows a sketch of the cuboctahedral oxygen cluster formed by 12 anions located at the vertices of a cuboctahedron and with a 13th oxygen atom situated in its center. The cube surrounding the cluster has an edge length close to the lattice parameter of the fcc cell of the uranium sublattice (the individual cations are not shown in the figure). In b‐U4O9, the discrete U6O37 cuboctahedral clusters are arranged on  4 axes with positions 12(b) of I 43d:The displacement of oxygen in the cluster gives rise to the O0 interstitial atoms of Willis. The cuboctahedral cluster contains the Willis 2:2:2 clusters as a component. The structure contains twelve U6O37 clusters per unit cell. There are 60 extra anions per unit cell, and the composition is then U256O572, i.e. the b‐U4O9 phase has the composition U4O9–y with y ¼ 0.062. U 3O 7 The U3O7 polymorphs all crystallize in the tetragonal system but none of their space groups have been specified. The axial ratio c/a is here an important parameter to classify the different polymorphs. a‐U3O7, which is prepared by

348

Uranium

Fig. 5.16 A schematic diagram of the cuboctahedral cluster. Eight oxygen anions inside the cationic cube are replaced by 12 anions located along the directions from the center C. ( from Garrido et al. (2003), reproduced by the permission of Elsevier).

oxidation of UO2 in air at temperatures of 120–175 C, has c/a ratios less than 1 (0.986–0.991) (Pe´rio, 1953b; Westrum, Jr. and Grønvold, 1962). The c/a ratios for b‐U3O7, prepared by oxidizing UO2 in air at temperatures 160–250 C, are 1.027–1.032 (Hoekstra et al., 1961; Simpson and Wood, 1983; McEachern and Taylor, 1998). In the range of O/U ratios between 2.26 and 2.33, the c/a ratio of a‐U3O7 did not vary in a systematic way between 0.986 and 0.989, while that of b‐U3O7 seemed to increase very slightly with increasing O/U ratio (Hoekstra et al., 1961). The g‐U3O7 (U16O37) phase with c/a ratios of 1.015–1.016 appears in a range where the O/U ratios are 2.30–2.31 (Westrum, Jr. and Grønvold, 1962; Hoekstra et al., 1970; Tempest et al., 1988), which are significantly smaller than those of a‐U3O7 and b‐U3O7. In the recent studies on b‐U3O7, it was found that all the uranium atoms and 70% of the oxygen atoms were hardly affected by the oxidation of UO2 to U3O7; however, the remaining 30% of the oxygen atoms changed their location to new ˚ along h110i vectors from the holes in the fluorite sites which are shifted 0.31 A framework of UO2. This result, based on a neutron diffraction analysis, is consistent with the assumption that the excess oxygen atoms in b‐U3O7 are accommodated in the cuboctahedral oxygen clusters (Garrido et al., 2003) as in the case of b‐U4O9. According to a theoretical study by Nowicki et al. (2000), the crystal structures of U3O7 differ from that of UO2 by the presence of the cuboctahedral

Compounds of uranium

349

Fig. 5.17 Atom arrangements on the sections perpendicular to the c‐axis (Loopstra, 1970b). (a) a‐U3U8; (b) hypothetical ‘ideal’ UO3; (c) b‐U3O8. The dots in the figure represent the actual positions. Isolated dots: uranium atoms; dots connected by full‐drawn lines denote oxygen atoms. In (a), the section is at z ¼ 0, and in (c), the origin is shifted b/3 at z ¼ 1/4. Reproduced by permission of the International Union of Crystallography.

clusters centered at specified ordered positions, and the arrangement of the clusters can be expressed as a stacking of identical polyatomic modules. A single module contains clusters arranged inpaffiffiffiffiffiffi square pattern. The square sides have a length ffi ˚ . The thickness of the modules is approximately equal to R1 ¼ 2:5aUO2 0:86 A ˚ close to 1:5aUO2 0:82 A. The various polytypes found in U3O7 can be rationalized with different stacking order of these modules; the small change in the energy of formation of the crystal reflects the interaction between the clusters. U 3O 8 ˚ , b ¼ 11.96 A ˚ , c ¼ 4.1469 A ˚ ; z ¼ 2) a‐U3O8 is orthorhombic (C2mm; a ¼ 6.716 A ˚, b ¼ (Loopstra, 1962). b‐U3O8 is also orthorhombic (Cmcm; a ¼ 7.069 A ˚ , c ¼ 8.303 A ˚ ; z ¼ 4) (Loopstra, 1970b), and the crystal structures of 11.445 A these two modifications are very similar. Fig. 5.17 depicts the relation of a‐ and b‐U3O8 with the hypothetical ‘ideal’ UO3 structure. The idealized a‐U3O8 structure (Fig. 5.17a) is derived from a layer of the hypothetical ‘ideal’ UO3 (Fig. 5.17b) by removing one oxygen atom from every third row. The idealized b‐U3O8 structure is obtained by replacing two oxygen atoms by a single one, located halfway between them (Fig. 5.17c). Fig. 5.17a and c show that the actual structures are only slightly distorted from the hypothetical ideal positions, which are represented in Fig. 5.17 by small circles (uranium atoms) and large circles (oxygen atoms). In a‐U3O8, all uranium atoms are coordinated with oxygen atoms forming pentagonal bipyramids. In b‐U3O8 the layers are stacked along the c‐axis so that a set of chains of uranium atoms is formed at x ¼ 0, y ¼ 0 and x ¼ 1/2, y ¼ 1/2. The other uranium atoms form chains in the c direction, in which the oxygen coordination is alternately pentagonal bipyramidal and distorted octahedral.

350

Uranium

a‐U3O8 shows a l‐type anomaly in the specific heat at 208.5 C (Girdhar and Westrum, Jr., 1968). At this first‐order phase transformation temperature, the orthorhombic pseudo‐hexagonal a‐U3O8 changes to a hexagonal structure ˚ , c ¼ 4.142 A ˚ ; z ¼ 1) (Loopstra, 1970a). Although the (P 62m; a ¼ 6.812 A high‐ and low‐temperature phases are closely related, there is an essential difference in the atom arrangement. In the high‐temperature phase the uranium atoms occupy a single three‐fold position, whereas at room temperature (in the low‐temperature phase) they are located at two‐fold and four‐fold positions making it possible for the uranium atoms to have different localized charges. Allen and Holmes (1995) pointed out the resemblance in the crystal structures of UO2 and a‐U3O8. The UO2 fluorite structure can be transformed to the layer structure of a‐U3O8 by displacing the (111) planes in UO2. A displacement of ˚ along the h112i direction in the (111) plane brings the outermost uranium 2.23 A layer directly above the second layer of the structure of a‐U3O8. UO3 ˚, The crystal structure of a‐UO3 was first reported as trigonal (P3m1; a ¼ 3.971 A ˚ ) (Zachariasen, 1948a). However, the later neutron powder diffracc ¼ 4.170 A tion data could not be adequately described in this way. Loopstra and Cordfunke (1966) published a structure assignment using an orthorhombic ˚ , b ¼ 6.860 A ˚ , c ¼ 4.166 A ˚ ). This structure is unit cell (C2mm; a ¼ 3.961 A close to the former one, since in both cases there are linear chains of O–U–O–U–O with the uranium surrounded by six additional oxygen atoms lying approximately in a plane normal to the chains. The reassignment to the orthorhombic cell reduced the R‐value from 0.35 to 0.19, but this is still high. Neither of the structures proposed could explain the abnormally low experimental density and the infrared absorption spectrum; the experimental densities were 7.25 g cm–3 (Loopstra and Cordfunke, 1966) or 7.30 g cm–3 (Siegel and Hoekstra, 1971a), which are much lower than the X‐ray density of 8.39 g cm–3. Strong infrared absorption was observed around 930 cm–1 (Hoekstra and Siegel, 1961; Carnall et al., 1966). This is typical of the antisymmetric stretching vibration of the ˚ (Jones, 1959), linear uranyl group with the U–O bond distance of about 1.7 A but isolated uranyl groups do not exist in either of the above crystal structures. A characteristic feature of a large number of solid uranium(VI) oxides is that they contain uranyl groups (UO2þ 2 ) with collinear atom arrangement (O–U–O) (Zachariasen, 1954b). The U–O bond (primary bond) of the uranyl group is a strong covalent bond (cf. Section 5.8.3c), giving short bond distances of 1.7–1.9 ˚ . The antisymmetric vibration of OI–U–OI, where OI denotes the oxygen A atoms in the uranyl group, gives rise to a strong infrared absorption in the frequency range of 600–950 cm–1. The oxygen atoms (OII), bound to uranium in a plane perpendicular to the linear uranyl group, form secondary bonds which are weaker than the U–OI bonds. The U–OII bond distances are longer, usually ˚ . The uranyl groups are often seen in the uranium oxides between 2.1 and 2.5 A having layer structures. The collinear axis of the uranyl group is along the c‐axis of such crystals with the four to six U–OII bonds formed in the a–b plane.

Compounds of uranium

351

Greaves and Fender (1972) carried out a structure refinement based on the assumption that a‐UO3 is formed by introducing statistically distributed vacancies into the uranium sublattice of a‐U3O8 so as to re‐establish an O/U ratio of three. For each missing uranium atom there were two displaced oxygen atoms in the z‐direction. Refinement of diffraction data using this model for the a‐U3O8 structure (space group C222) of Andresen (1958) decreased the R‐value to 0.031 and the theoretical density to 7.44 g cm–3; the U–O distance in the ˚ . The same refinement based on the C2mm space group uranyl groups was 1.64 A of Loopstra (1962) yielded fairly reasonable values of the uranium occupation ˚ , but the R‐value (0.13) and the number, 0.82, and the U–O distance, 1.58 A uranium and oxygen temperature factors were somewhat higher. The superlattice reflections observed in both the neutron and electron diffraction patterns ˚, could be indexed on an orthorhombic unit cell with dimensions a ¼ 6.84 A ˚ , and c ¼ 4.157 A ˚. b ¼ 43.45 A The crystal structure of high‐pressure phase, z‐UO3, is orthorhombic ˚ , b ¼ 5.466 A ˚ , c ¼ 5.224 A ˚ ) (Siegel et al., 1966). There (P212121; a ¼ 7.511 A are no uranium vacancies in this UO3 modification as shown by the agreement of the measured density (8.62 g cm–3) with the X‐ray density (8.85 g cm–3). In this structure each uranium atom is bonded to seven oxygen atoms, leading to shared [UO7] configurations with bridging oxygen atoms in the plane perpendicular to the UO2‐axis, identified by two short collinear bonds of 1.80 and ˚ . The other five coordinated oxygen atoms form a puckered pentagonal 1.85 A coordination geometry around the uranyl groups. (iv) Phase relations There have been numerous reports on the phase relations and thermodynamic properties of the uranium–oxygen system. Rand et al. (1978) made an assessment of thermodynamic data and presented a phase diagram of this system. Recently, Chevalier et al. (2002) and Gue´neau et al. (2002) published critical reviews. In two recent papers Labroche et al. (2003a,b) critically assessed the composition range and oxygen potential of uranium oxides in the UO2–U3O8 region taking into account the uncertainties of the published data. Uranium–uranium dioxide region Hypostoichiometric UO2–x exists as a single phase or as a mixture with liquid. Since the formation energy of an oxygen vacancy in UO2 is much higher than that of interstitial oxygen, the lower phase boundary of single phase UO2–x is very close to O/U ¼ 2.0 up to 1500 K. In the phase diagram of Rand et al. (1978), this phase boundary has been obtained up to 2500 K by using the relation lnx ¼ (3.877 0.094) – (13130 210)T –1 proposed by Winslow (1973) based on examination of the relevant experimental data. In the recent critical review on the thermodynamic properties in the uranium–oxygen system, Chevalier et al. (2002) presented the phase diagram of the U–UO2 region by careful selection of the experimental data from Blum et al. (1963),

352

Uranium

Fig. 5.18 Partial phase diagram of the U–UO2 system assembled from values in Rand et al. (1978), Chevalier et al. (2002), and Gue´neau et al. (2002).

Bates (1964, 1966), Martin and Edwards (1965), Edwards and Martin (1966), Guinet et al. (1966), Bannister (1967), Tetenbaum and Hund (1968, 1970), Ackermann et al. (1969), Latta and Fryxell (1970), Ackermann and Rauh (1972), Garg and Ackermann (1977, 1980), and Gue´neau et al. (1998). Gue´neau et al. (2002) presented the phase diagram of this region using the data from Cleaves et al. (1945), Martin and Edwards (1965), Edwards and Martin (1966), Bannister (1967), Hein et al. (1968), Ackermann et al. (1969), Kjaerheim and Rolstad (1969), Latta and Fryxell (1970), Tachibana et al. (1985), and Gue´neau et al. (1998). Fig. 5.18 shows a phase diagram of the U–UO2 region (1.2  O/U  2.0) and the UO2þx region with x  0.25 drawn by using the selected values from Rand et al. (1978), Chevalier et al. (2002), and Gue´neau et al. (2002). The monotectic temperatures for the reaction L2 ¼ UO2–x þ L1 are (2773 30) K (Edwards and Martin, 1966), (2743 30) K (Guinet et al., 1966) and (2693 70) K (Bannister, 1967). The reported compositions of the liquid L2 phase at the monotectic temperature are O/U ¼ (1.3 0.1) (Edwards and Martin, 1966), 1.18 (Guinet et al., 1966), (1.53 0.05) (Bannister, 1967) and

Compounds of uranium

353

1.46 (Latta and Fryxell, 1970). The measured composition of the liquid L1 phase at this temperature was O/U ¼ 0.05 (Edwards and Martin, 1966; Latta and Fryxell, 1970). The O/U ratios of solid UO2–x are in reasonable agreement: 1.67 (Latta and Fryxell, 1970; Rand et al., 1978), 1.64 (Edwards and Martin, 1966), 1.60 (Guinet et al., 1966), and (1.62 0.06) (Bannister, 1967). The ratio O/U is decreased to 1.67 at the lower phase boundary of single phase UO2–x at the monotectic temperature. Above the monotectic temperature the O/U ratio at the lower phase boundary increases to UO2.00, until the maximum melting temperature is reached. At the monotectic temperature, three condensed phases, i.e. oxygen‐saturated liquid uranium metal L1 (UO0.05), liquid L2 of a composition UO1.39, and solid UO2–x (UO1.67) coexist in equilibrium. UO2.00–UO2.25 region Stoichiometric uranium dioxide, UO2, shows a first‐order transition at 30.8 K. This is a magnetic transition, and below that temperature UO2 is antiferromagnetic, with a structure of type I (Fournier and Troc´, 1985), accompanied by an internal distortion in the oxygen sublattice (Faber, Jr. and Lander, 1976). At the transition temperature, a discontinuity in the lattice parameter vs temperature curve (Marples, 1976) and a sharp anomaly in the heat capacity with an entropy increment of 3.6 J K1 mol1 (Westrum, Jr. and Grønvold, 1962; Huntzicker and Westrum, Jr., 1971) were observed. Uranium dioxide is stoichiometric at low temperatures, but exhibits a hyperstoichiometric (UO2þx) homogeneity range above 500 K; this range increases with increasing temperature. The upper phase boundary of single phase UO2þx has been extensively studied at temperatures between 500 and 1950 K. The boundary increases with increasing temperature up to (1398 8) K (Blackburn, 1958; Roberts and Walter, 1961; Anthony et al., 1963; Belbeoch et al., 1967; Blank and Ronchi, 1968; van Lierde et al., 1970; Dode´ and Touzelin, 1972; MacLeod, 1972; Matsui and Naito, 1975; Labroche et al., 2003b), at which the U4O9 phase decomposes to UO2þx and U3O8–z (UO2.61) peritectoidally. The upper phase boundary of UO2þx above that temperature increases only slightly with increasing temperature up to 1950 K. The phase diagram in the region 2.0  O/U  3.0 is shown in Fig. 5.19, where the upper phase boundary of UO2þx was obtained by referring to the literature (Blackburn, 1958; Schaner, 1960; Aronson et al., 1961; Roberts and Walter, 1961; Kiukkola, 1962; Markin and Bones, 1962a; Hagemark and Broli, 1966; Kotlar et al., 1967a; Bannister and Buykx, 1974; Saito, 1974; Picard and Gerdanian, 1981; Labroche et al., 2003b). The U4O9 phase has a narrow homogeneity range; the reported lower phase boundary is located between the O/U ratios of 2.228 and 2.235 (Blackburn, 1958; Schaner, 1960; Roberts and Walter, 1961; Kotlar et al., 1968; van Lierde et al., 1970; Inaba and Naito, 1973; Picard and Gerdanian, 1981; Labroche et al., 2003b). This boundary is almost unchanged with temperature from room temperature to the peritectic temperature. The reported upper phase boundaries have the O/U values mostly between

354

Uranium

Fig. 5.19 Phase diagram of the U–O system in the region 2.0  O/U  3.0.

2.24 and 2.25 (Blackburn, 1958; Schaner, 1960; Roberts and Walter, 1961; Kotlar et al., 1968; van Lierde et al., 1970; Inaba and Naito, 1973; Picard and Gerdanian, 1981; Labroche et al., 2003b), and many of the papers indicate the uppermost composition to have O/U ¼ 2.242. It is generally assumed that also the upper phase boundary does not change substantially with temperature. U4O9 shows no low‐temperature anomaly in the heat capacity due to a magnetic transition observed for UO2. This is interesting if one considers the close resemblance in the crystal structures between U4O9 and UO2. Instead, the low‐temperature modification a‐U4O9 undergoes a non‐magnetic second‐order transition to b‐U4O9 at 340–350 K giving rise to a l-type specific heat anomaly. The enthalpy and entropy increments of this transition for U4O9-y with O/U ¼ 2.246–2.254 are 630–710 J mol1 and 1.9–2.2 J K1 mol1, respectively (Gotoo and Naito, 1965; Westrum, Jr., et al., 1965; Grønvold et al., 1970; Inaba and Naito, 1973). b‐U4O9 transforms into g‐U4O9 at around 850 K. According to Bevan et al. (1986), the maximum O/U atom ratio of the b‐U4O9 phase should be 2.2345 (cf. section on U4O9), which supports the hypostoichiometries at the upper phase boundary observed for U4O9. The phase transitions a/b and b/g are reversible, as described in the crystal structure section.

Compounds of uranium

355

UO2.25–UO2.667 region Most compounds in the composition range of 2.25  O/U  2.5, i.e. a‐ and b‐U3O7, g‐U3O7 (U16O37), U8O19, and b‐ and g‐U2O5 have fluorite‐type structures. a‐, b‐, and g‐U3O7 have been prepared under ambient atmosphere, but U8O19 and a‐, b‐, and g‐U2O5 were formed only at high pressures (15–60 kbar). On this basis, U8O19 and U2O5 are regarded as metastable phases, which are thermodynamically unstable at atmospheric pressure (Hoekstra et al., 1970). The phases for which the stability has not been established are indicated in Fig. 5.19 by broken lines. U3O7 decomposes at 700 C in air to U4O9 and U3O8 (Pe´rio, 1953a; Grønvold, 1955). Although b‐U3O7 shows no low‐temperature transitions, a‐U3O7 exhibits a small l‐type anomaly at 30.5 K with enthalpy and entropy increments of 11 J mol1 and 0.4 J K1 mol1, respectively. This transition is assumed to be of magnetic origin (Westrum, Jr. and Grønvold, 1962). The other oxides U13O34 (UO2.615) and U11O29 (UO2.636) have been described (Kovba et al., 1972; Spitsyn et al., 1972), but no information is given for their stability at low temperatures and pressures. Two modifications of U3O8, i.e. a‐ and b‐U3O8, crystallize both in orthorhombic system and their crystal structures are very similar. These compounds are not based on the fluorite structure but are composed of the layer structures related to the hypostoichiometric ‘ideal’ UO3 structure (Section 5.7.2a(iii)), which has uranyl bonds perpendicular to the layer planes. The difficulty to rearrange the oxygen atoms in these infinite layer structures is probably the reason for the slow equilibration between U3O8 and the gas phase at different temperatures and the oxygen partial pressures. The O/U ratio of the U3O8 phase varies with the experimental methods (Gerdanian and Dode´, 1965; Fujino et al., 1981; Srirama Murti et al., 1989). Labroche et al. (2003a) suggested that the reason for the scattered data is dissolution of atmospheric nitrogen in the oxides. Although the measured data at the lower phase boundary of U3O8 phase are not in good agreement above 1000 K (Labroche et al., 2003b), the ratios O/U are in general between 2.595 and 2.62 (Blackburn, 1958; Hagemark and Broli, 1966; Kotlar et al., 1967b; Ackermann and Chang, 1973; Caneiro and Abriata, 1984). This phase boundary does not change with temperature up to 1600 K. Above 1000 K, the upper phase boundary was observed to have O/U ¼ 2.667 (stoichiometric U3O8) up to 1400 K (Ackermann and Chang, 1973; Caneiro and Abriata, 1984). At an ambient pressure of 0.21 atm O2, however, the compound becomes hypostoichiometric above 873 K (Cordfunke and Aling, 1965; Rodriguez de Sastre et al., 1967; Ackermann and Chang, 1973). On the other hand, at lower temperatures of 773–873 K, freshly prepared U3O8 samples often show hyperstoichiometry with O/U ¼ 2.670. Moreover, a hysteresis is seen in the O/U ratio in heating and cooling cycles. Repetition of the heating and cooling cycle results in formation of compounds of lower O/U ratios (Dharwadkar et al., 1975; Fujino et al., 1981). Similar hysteresis phenomena for U3O8–z have also been observed in oxygen partial pressure vs O/U ratio isotherms (Caneiro and Abriata, 1984) and the electrical conductivity (Ishii et al., 1970b;

356

Uranium

Dharwadkar et al., 1978). Slow formation of another phase in a‐U3O8 may take place at temperatures of 1273–1573 K; according to Hoekstra et al. (1955); this is possibly the U8O21 phase with a homogeneity range extending between the compositions UO2.60 and UO2.65. A slightly different composition range, UO2.617– UO2.655, has also been reported (Caneiro and Abriata, 1984). It is possible that the proper stoichiometry of b‐U3O8 is U8O21, since b‐U3O8 has been prepared by heating a‐U3O8 to 1623 K followed by slow cooling to room temperature (Loopstra, 1970b). However in the majority of reports, the phase in this region of compositions is considered to be hypostoichiometric U3O8 (i.e. U3O8–z) (Kotlar et al., 1967a; Ackermann and Chang, 1973; Labroche et al., 2003a,b). a‐U3O8 shows a l‐type transition in the heat capacity at 25.3 K with associated enthalpy and entropy increments of 50 J mol–1 and 2.3 J K–1 mol1, respectively (Westrum, Jr. and Grønvold, 1959, 1962). This is due to a para‐ antiferromagnetic transition (Leask et al., 1963). a‐U3O8 shows three other transitions at higher temperatures: 490, 570, and 850 K. The reported temperature for the 490 K transition varies between 480 and 490 K (Girdhar and Westrum, Jr., 1968; Maglic and Herak, 1970; Inaba et al., 1977; Naito et al., 1982). For the 570 K transition, the reported temperatures are between 562 and 576 K (Inaba et al., 1977; Naito et al., 1982, 1983). The 850 K transition has been observed in one study using adiabatic calorimetry (Inaba et al., 1977). Naito et al. (1983) proposed an electronic ordering on uranium atoms with displacement of oxygen atoms as the origin of the above transitions. UO2.667–UO3 region Hoekstra and Siegel (1961) regard the UO2.9 phase (U12O35), which is formed by partial decomposition of amorphous UO3, as a distinct compound because on heating amorphous UO3 the O/U ratio remains virtually constant over a 100 K temperature interval from 450 to 550 C. The pycnometric density measured for UO2.9 is considerably lower than the theoretical density. This is similar to the ˚, b ¼ case of a‐UO3 assigned to a C2mm orthorhombic cell with a ¼ 3.961 A ˚ , and c ¼ 4.166 A ˚ (Loopstra and Cordfunke, 1966). Thus the crystal 6.860 A structure of UO2.9 may also have vacant uranium sites as in the a‐UO3 structure. For UO3, one amorphous and six crystalline modifications are known. When a‐UO3 is heated in air with a constant heating rate, it decomposes to U3O8 passing through a non‐stoichiometric range with the O/U ratios between 3.0 and ca. 2.95 (Hoekstra and Siegel, 1961). The d‐ and ε‐UO3 compounds convert to U3O8 at about 450 C in air with no evidence of a non‐stoichiometric oxide range. However, if the heating rate is low, they do not decompose directly, instead re‐oxidation of the partially reduced oxides to g‐UO3 takes place. Also in the g‐UO3 there is no measurable oxygen non‐stoichiometry. The g‐phase is more stable and decomposes to U3O8 at higher temperatures of 620–700 C. z‐UO3 is formed by heating U3O8 at 500 C under high pressures of 15–60 kbar interval produced by a pyrophyllite tetrahedral assembly. This compound is unstable at the ambient pressure (Hoekstra et al., 1970). No magnetic transition has been observed for UO3 (Jones et al., 1952).

Compounds of uranium

357

In the uranium trioxide–water system, six compounds have been well established (Dawson et al., 1956; Harris and Taylor, 1962; Debets and Loopstra, 1963; Dell and Wheeler, 1963; Cordfunke and Debets, 1964; Bannister and Taylor, 1970; Taylor, 1971; Siegel et al., 1972; Hoekstra and Siegel, 1973; Vita et al., 1973; Tasker et al., 1988). The physical properties for these compounds are listed in Table 5.15 together with those for uranium peroxide hydrates. (v)

The heat capacity of UO2

The low‐temperature heat capacity of UO2 shows a very sharp l‐type anomaly of magnetic origin (Fournier and Troc´, 1985) at 30.44 K (Huntzicker and Westrum, Jr., 1971) or 28.7 K (Jones et al., 1952). The entropy increment is 3.6 J K1 mol1 (Westrum, Jr, and Grønvold, 1962). Faber, Jr. and Lander (1976) carried out a neutron diffraction and scattering study on this transition. They showed that the anomaly took place at 30.8 K and that it could be explained as a first‐order transition from the low‐temperature antiferromagnetic state of type I, associated with an internal distortion of the oxygen sublattice, to the paramagnetic state. The low‐temperature (5–346 K) heat capacity data of Huntzicker and Westrum, Jr. (1971) are in good agreement with those of Grønvold et al. (1970) (304–1006 K) in the range of overlapping temperatures. The high‐temperature heat capacity of UO2 has been studied extensively because of the importance of this compound as nuclear fuel; several critical reviews have also been published (Browning, 1981; Browning et al., 1983; Naito, 1989; Ronchi and Hyland, 1994; Fink, 2001; Carbajo et al., 2001). The selected data of heat capacities are shown in Fig. 5.20 together with the correlations calculated by the MATPRO equation (Hagrman, 1995) and by the Fink equations with functional and polynomial forms. In the figure two sets of data of Ronchi et al. (1999) are shown for high temperatures, and the data of Huntzicker and Westrum, Jr. (1971) and Grønvold et al. (1970) are shown for low and intermediate temperatures. Since the heat capacities of the functional and polynomial equations differ by at most 1%, the latter equation is recommended because of its simplicity (Fink, 2001). This equation, which is based on a combined analysis of the reported data (Moore and Kelley, 1947; Hein and Flagella, 1968; Hein et al., 1968; Ogard and Leary, 1968; Leibowitz et al., 1969; Fredrickson and Chasanov, 1970; Grønvold et al., 1970; Huntzicker and Westrum, Jr., 1971; Ronchi et al., 1999), for 298.15  T  3120 K is: Cp ðTÞðJ K1 mol1 Þ ¼ 52:1743 þ 87:951 t  84:2411 t2 þ 31:542 t3  2:6334 t4  0:71391 t2 ; where, t ¼ TðKÞ=1000: The MATPRO equation (Hagrman, 1995) gives somewhat lower Cp values at higher temperatures. The l‐type transition found by Bredig (1972) at 2670 K has been confirmed by other researchers (Hutchings et al., 1984; Ralph and Hyland, 1985; Hiernaut et al., 1993). Hiernaut et al. (1993) modeled the transition in UO2.00 as

orthorhombic

Pbna

bright yellow

violet

pale yellow pale yellow

UO2(OH)2 · H2O (¼UO3 · 2H2O) (schoepite)

U3O8(OH)2

UO4 · 4H2O

UO4 · 2H2O

monoclinic

P21/c

gray‐ chamois

g‐UO2(OH)2 (¼g‐UO3 · H2O)

C2, Cm or C2/m Immm

orthorhombic

Pbca

yellow‐ green

b‐UO2(OH)2 (¼b‐UO3 · H2O)

orthorhombic

monoclinic

triclinic

orthorhombic

orthorhombic

Symmetry

Cmca

Space group

greenish yellow

Color

6.502

11.85

6.802

13.977

6.419

5.6438

4.242

4.27–4.30

˚) a (A

4.216

6.78

7.417

16.696

5.518

6.2867

10.19– 10.24 10.302

˚) b (A

Lattice parameters

8.778

4.245

5.556

14.672

5.561

9.9372

6.86– 6.96 6.868

˚) c (A

a ¼ 108.5 b ¼ 125.5 g ¼ 88.2 b ¼ 93.47

b ¼ 112.77

Angle (deg)

2

2

1

32

2

4

4

4

Z

5.15

5.00

5.56

5.73

6.73

6.63

Exp.

6.85

X‐ray or ND

Density (g cm3)

Physical properties of the uranium trioxide hydrates and of the uranium peroxide hydrates.

a‐UO2(OH)2 (¼a‐UO3 · H2O)

a‐UO3 · 0.8H2O

Formula

Table 5.15

Debets (1966)

Debets (1966)

Dawson et al. (1956) Taylor (1971); Hoekstra and Siegel (1973) Bannister and Taylor (1970); Hoekstra and Siegel (1973) Cordfunke and Debets (1964); Hoekstra and Siegel (1973) Debets and Loopstra (1963); Tasker et al. (1988); Hoekstra and Siegel (1973) Siegel et al. (1972)

References

Compounds of uranium

359

▴

Fig. 5.20 Recommended equations and data for the heat capacity of UO2 (Fink, 2001). : Table data of Ronchi et al. (1999); □: Graph data of Ronchi et al. (1999); e Grønvold et al. (1970); ○: Huntzicker and Westrum, Jr. (1971); –––: Functional form equation (Fink, 2001); –––: Polynomial form equation (Fink, 2001); ‐‐‐‐‐‐: Phase transition; — — —: MATPRO equation (Hagrman, 1995).

a second‐order transition involving oxygen Frenkel disorder. The transition temperature of hypostoichiometric uranium dioxide (UO2–x) increases with increasing x. Their model explains the shift as due to the change from a l‐transition to a first‐order phase transition in UO2–x. The discussion on the heat capacity of UO2 can be divided into the following four regions (Ronchi and Hyland, 1994): (1) Room temperature – 1000 K region. The increase in the heat capacity is caused by the harmonic lattice vibrations with a smaller contribution from thermal excitation of localized electrons of U4þ in the crystal field. (2) 1000–1500 K region. The heat capacity increases with increasing anharmonicity of the lattice vibrations as shown by thermal expansion. (3) 1500–2670 K region. The heat capacity increase in this region is mainly ascribed to the formation of lattice and electronic defects. The Cp peak at 2670 K is due to the oxygen Frenkel defects as determined by neutron scattering measurements. (4) Region above 2670 K. The peak of the heat capacity drops sharply by rapid saturation of the defects. At temperatures from 2700 K to the melting point, the concentration of Schottky defects increases.

Uranium

360 (vi)

Oxygen potential and other thermodynamic properties

A large number of reports have been published on the partial molar thermody   namic quantities DGðO 2 Þ, DHðO2 Þ, and DSðO2 Þ for non‐stoichiometric uranium oxides. These studies have been carried out mainly by means of thermogravimetric method (Gerdanian, 1964; Gerdanian and Dode´, 1965; Hagemark and Broli, 1966; Kotlar et al., 1967b; Ugajin, 1983; Matsui and Naito, 1985a) and emf method (Aronson and Belle, 1958; Kiukkola, 1962; Markin and Bones, 1962a,b; Marchidan and Matei, 1972; Saito, 1974; Nakamura and Fujino, 1987); however, tensimetric (Roberts and Walter, 1961), quenching (Anthony et al., 1963), and Knudsen effusion (Blackburn, 1958) techniques have also been used. In the two‐phase regions of solid oxides, the equilibrium oxygen pressure over uranium oxides, pO2 ðatmÞ, which is related with the oxygen potential of the  2 Þ by the equation DGðO  2 Þ ¼ RT ln pO , is a function of only oxides DGðO 2 temperature. For the UO2þx–U4O9–y two‐phase region, Saito (1974) showed that log pO2 is: log pO2 ðatmÞ ¼ 105:7  5136 T 1 þ 33:46 log T

ð5:1Þ

The previous equation describes the measured data from the literature (Aronson and Belle, 1958; Blackburn, 1958; Roberts and Walter, 1961; Kiukkola, 1962; Markin and Bones, 1962b; Kotlar et al., 1967b; Marchidan and Matei, 1972; Saito, 1974; Nakamura and Fujino, 1987), although it gives gradually too low values at temperatures above 1323 K (Roberts and Walter, 1961; Nakamura and Fujino, 1987). For the U4O9–U3O8–z two‐phase region, log pO2 is represented by (Saito, 1974) log pO2 ðatmÞ ¼ 7:996  16 330 T 1

ð5:2Þ

or (Roberts and Walter, 1961) log pO2 ðatmÞ ¼ 8:27  16 760 T 1 :

ð5:3Þ

The difference in log pO2 of equations (5.2) and (5.3) is 0.20 at T ¼ 900 K, which decreases to 0.033 at T ¼ 1400 K. The oxygen potential of UO2þx in the single‐phase region is a function of  the composition x and temperature. A number of experimental DGðO 2 Þ isotherms plotted against O/U ratio of UO2þx for various temperatures in the range 1173–1773 K have been reported (Aukrust et al., 1962; Markin and Bones, 1962a,b; Hagemark and Broli, 1966; Ugajin, 1983; Matsui and Naito,  1985a). The scatter in the experimental DGðO 2 Þ data seems to increase as the  O/U ratio decreases in the composition range below 2.01, where DGðO 2 Þ rapidly decreases with decreasing O/U ratio.  Fig. 5.21 shows DGðO 2 Þ for UO2þx as a function of the O/U ratio expressed by an equation which consists of component equations giving experimental values in polynomial forms (Nakamura and Fujino, 1987) with small modifications for

Compounds of uranium

Fig. 5.21

361

Oxygen potential as a function of O/U ratio. Curve 1, 1173 K; curve 2, 1373 K.

 DGðO 2 Þ below O/U ¼ 2.02. The lowest O/U ratio shown in the figure is 2.003,  below which the DGðO 2 Þ values approach those at x ¼ 0, i.e. –633.3 and –588.4 kJ mol–1 for 1173 and 1373 K, respectively. These values are obtained from the 1  equation DGðO at x ¼ 0 assessed by Lindemer 2 Þ¼ 8 97 000 þ 224:8 T J mol and Besmann (1985) for temperatures between 873 and 1673 K.   The partial molar entropy of oxygen, DSðO 2 Þ ¼ dDGðO2 Þ=dT, was in most papers regarded as temperature independent and on this basis differentiation of  DGðO 2 Þ was made without specifying temperature. There have been rather wide  scattering in the reported values of the partial molar enthalpy of oxygen, DHðO 2 Þ,   and the entropy, DSðO Þ. This is significantly reduced when D SðO Þ is treated as 2 2  2Þ ¼ C  p ðO2 ÞdT=T where C  p ðO2 Þ is a temperature‐dependent quantity: dDSðO the partial molar heat capacity of oxygen expressed as a polynomial of logx  (Nakamura and Fujino, 1987). In this case, DHðO 2 Þ also becomes temperature‐  2 Þ þ TDSðO   dependent because of the relation DHðO2 Þ ¼ DGðO 2 Þ.  Fig. 5.22a compares the calculated DHðO2 Þ vs x curves obtained by using  p ðO2 Þ values with the literature data. Fig. 5.22b compares the the above C   DSðO2 Þ vs x curves. The derived DHðO 2 Þ curve at 1323 K is in good agreement

 2 Þ, respectively, with composition x  2 Þ and DSðO Fig. 5.22 (a) and (b): Variation of DHðO at 873, 1073, 1323, and 1673 K in the region 0  x  0.25 (Nakamura and Fujino, 1987). $: sample a (Nakamura and Fujino, 1987); I: sample b (Nakamura and Fujino, 1987);  2 Þ curves (Nakamura and Fujino 1987); –––:  2 Þ and DSðO — — —: least squared DHðO Picard and Gerdanian (1981) at 1323 K; ○: Markin and Bones (1962a,b); 4: Kiukkola (1962);
: Saito (1974); ▴: Gerdanian and Dode´ (1965); : Hagemark et al. (1962, 1966); ▾: Marchidan and Matei (1972); : Aronson and Belle (1958); : Ugajin (1983); □: Roberts and Walter (1961); ‐‐‐‐‐: Rand and Kubaschewski (1963) at 1273 K; — — —: Rand et al. (1978). Reproduced by the permission of Elsevier.

4

Compounds of uranium

363

with the measured curve of Picard and Gerdanian (1981). Most reported values of   the temperature‐independent DHðO 2 Þ and DSðO2 Þ are within the curves derived   using temperature‐dependent DHðO2 Þ and DSðO 2 Þ in the range 1073–1323 K. Labroche et al. (2003a) made a critical assessment of the thermodynamic data for UO2þx taking into account the uncertainties in the measurements. The result showed that log pO2 could be represented by equations of the form log pO2 ¼ A  B T 1 with A and B varying with the O/U ratio in the range 2.01–2.23. On the other hand, this treatment revealed that the x dependence of log pO2 could not be given with adequate accuracy by the above simple formulas if the temperature range is larger.  Gerdanian and Dode´ (1968) determined DHðO 2 Þ by measuring the evolved heat when a small amount of oxygen was passed over UO2þx in a Calvet‐type  microcalorimeter. This technique made it possible to measure DHðO 2 Þ close to the stoichiometric composition as shown in Fig. 5.23.  In this figure, DHðO 2 Þ increased very sharply with increasing O/U ratio from 0, and smaller than 1 for x < 0. Since one of the electronic defects always has a concentration higher than that of the ionic defects and the electronic mobilities are much higher, the ionic conductivity is insignificant. The conductivities for nominally stoichiometric UO2 with x  10–3 can be represented by the above equation (Bates et al., 1967; Winter, 1989). At x ¼ 0, the intrinsic conductivity by the U5þ and U3þ charge carriers produced by a disproportionation reaction 2U4þ ¼ U5þþ U3þ becomes important. The above reaction parameters were given by a band gap of 2 eV and a vibrational entropy of 2k (Winter, 1989). For UO2þx at 500–1400 C, the electrical conductivities plotted against x decrease nearly linearly with decreasing x below x ¼ 0.1 in the direction s ! 0. The conductivity changes in the different measurements, but there is a fairly good consistency in the s values of the samples having larger x values: For x ¼ 0.1 at 1000 C, for example, s 30 O–1 cm–1 (Aronson et al., 1961), which is close to the conductivity obtained by Dudney et al. (1981). The other reported values are 10 O–1 cm–1 (Matsui and Naito, 1985b) and 1.5 O–1 cm–1 (Ishii et al., 1970c), while the measured values of Lee (1974) are much lower. U3 O8z There are no large differences in the electrical conductivity between U3O8–z and UO2þx. The conductivities for U3O8–z are s 10–1 and 10–3 O1 cm1 at 730 and 230 C, respectively, when the oxygen partial pressure is 150 mmHg. Contrary to the conduction behavior of UO2þx, however, s for U3O8–z increases with decreasing pO2 (in the range 102 to 10–2 mmHg O2), suggesting that the main carriers are electrons (George and Karkhanavala, 1963). A change of slope in the log s vs 1/T plots, resulting from a phase transition, was observed at 723 K. The activation energies of conduction were 0.64 and 1.10 eV below and above the transition, respectively. The transition temperature varies with nonstoichiometry from 658 K (UO2.667, i.e. stoichiometric U3O8) to 923 K (UO2.558 to UO2.650) (Ishii et al., 1970b). At higher temperatures of 1111–1190 K, another s anomaly has been measured, presumably due to the formation of U8O21þx (Dharwadkar et al., 1978). (x)

Chemical properties

UO2 is oxidized to U3O8 on heating in air at temperatures of 600–1300 C. When UO3 is heated in air above 600 C, the compound is reduced to U3O8. U3O8 has been used as a standard material for chemical analysis of uranium oxides

Uranium

370 Table 5.16

Reactions of uranium oxides. Products of the following oxides

Reagent

Temperature ( C)

UO2

U3O8

UO3

H2(g) CO(g) HF(g) F2(g) CCl4(g) SOCl2(g) H2S(g) C(s) C(s) þ Cl2(g) C(s) þ CS2(g) C(s) þ N2(g)

>750 >750 550 400 400 450 1000 1500–1700 1000 1000 1700–1900

— — UF4 UF6 (>500 C) UCl4 UCl4 UOS UC (UC2) UCl4 US2 UN

UO2 UO2 UO2F2 þ UF4 UF6 UCl4 þ UCl5 UCl4 UOS UC (UC2) UCl4 US2 UN

UO2 UO2 UO2F2 UF6 UCl4 þ UCl5 UCl4 UOS UC (UC2) UCl4 US2 UN

because of its high stability in air. However, U3O8 is now recognized as a compound that is rather difficult to obtain in strictly stoichiometric composition; the O/U ratio deviates significantly from 8/3 depending on the heating temperature, time, and thermal history. Stoichiometric UO2 can be obtained by heating uranium oxides in H2 or CO gas streams at temperatures 750–1700 C (Table 5.16). However, if the H2 gas contains an O2 impurity, the formed UO2 is oxidized to non‐stoichiometric UO2þx during the cooling process at temperatures below 300 C. The reaction of UO2 with air at room temperature deserves special attention, as the reaction is dependent on particle size and reactivity. Very fine UO2 powder formed by the hydrogen reduction at lower temperatures below 800 C may be pyrophoric. Even though large particles are usually not pyrophoric, the O/U ratio increases steadily with time of exposure to air. UO2 can take up appreciable quantities of oxygen for particle diameters of about 0.05–0.08 mm. When the particle size is 0.2–0.3 mm or larger, UO2 is fairly stable to oxidation (Belle, 1961). UO2 pellets sintered at around 1700 C are not oxidized for years due to protection by slightly oxidized thin surface films. Some reactions of uranium oxides with chemical reagents are shown in Table 5.16. For the reaction with C(graphite), the product is UC if the mixing mole ratio of carbon and UO2 is C/UO2 ¼ 3, and UC2 if C/UO2 ¼ 4. An interesting reaction between uranium oxides and liquid N2O4 has been observed (Gibson and Katz, 1951). Anhydrous uranium oxides react with liquid N2O4 to yield UO2(NO3)2 · N2O4. A similar reaction with N2O5 (Gibson et al., 1960) may be used to prepare anhydrous UO2(NO3)2. It was found that the reaction between metal and liquid N2O4 also gives UO2(NO3)2 · N2O4 (Addison and Hodge, 1961). Uranium oxides dissolve in mineral acids such as HNO3, HClO4, HCl, and H2SO4. In HCl, H2SO4, and strong phosphoric acid, the mean valence of

Compounds of uranium

371

uranium does not change from that in the solid state before dissolution. Sintered UO2 pellets dissolve in HNO3 with a slow rate, but the dissolution can be accelerated if a small amount of NH4F is added, due to the formation of fluoro‐complexes of uranium. The addition of a small amount of H2O2 to HNO3 is also effective to enhance the dissolution rate of UO2 in laboratory experiments; in this way no contamination of the solution takes place. The mechanism of dissolution of UO2 in H2O2 aqueous solution has been studied by a number of researchers. It is regarded as a second‐order reaction with a rate constant 810–7 m min–1 (based on the surface‐to‐solution volume ratio) (Ekeroth and Jonsson, 2003). The plausible mechanism is a slow electron
transfer step producing UOþ 2ðsurfaceÞ þ OH followed by a rapid reduction of the
 þ
radical OH to OH . The UO2ðsurfaceÞ ions are oxidized to UO2þ 2ðsurfaceÞ by OH or by disproportionation (Shoesmith and Sunder, 1994; Ekeroth and Jonsson, 2003). Carbonate ions increase the solubility of UO2þ 2ðsurfaceÞ (Grenthe et al., 1984). The above mechanism is consistent with the results by other oxidants,  

viz. IrCl2 6 , MnO4 , FeðEDTAÞ , CO3 , HO2 , and O2 (Bard and Parsons, 1985; Wardman, 1989; Huie et al., 1991). (b)

Alkali metal uranates and alkaline‐earth metal uranates

In Table 5.17, some physico‐chemical properties and crystal structures are shown for ternary alkali metal uranates and alkaline‐earth metal uranates. (i) Uranates(VI) The most frequently encountered uranates(VI) are a series of compounds of þ 2þ 2þ types Mþ 2 Un O3nþ1 (M : alkali metals) and M Un O3nþ1 (M : alkaline‐earth þ 2þ metals), but other compounds such as M4 UO5 ; M2 UO5 ; M2þ 3 UO6 , and M2þ U O are also well known. 3 11 2 Preparation Carbonates, nitrates, or chlorides of alkali or alkaline‐earth elements are mixed with the calculated amounts of U3O8 or UO3. Uranates(VI) are obtained by heating the mixtures in air or oxygen at temperatures 500–1000 C. Because of higher volatility of rubidium and cesium oxides, the uranates of these elements are prepared by heating at lower temperatures of 600–700 C (Hoekstra, 1965). The alkaline‐earth oxides are also used as starting materials. Reaction temperatures above 1000 C can be used for the preparation of alkaline‐earth uranates on account of very low vapor pressures of alkaline‐earth oxides. A number of stoichiometric sodium uranates (a‐ and b‐Na2UO4, Na2U2O7, a‐Na4UO5, etc.) have been prepared following a procedure described by Jayadevan et al. (1974) by calcining well‐characterized thermally labile double sodium uranium salts such as carbonates, oxalates, and acetates. This technique avoids high‐temperature treatment and decreases losses by vaporization. This is

orthorhombic

Imma

yellow. not hygroscopic, infrared spectra

MgUO4

tetragonal

I4/mmm

orange. very hygroscopic. infrared spectra

Cs2UO4

tetragonal

tetragonal

I4/mmm

yellow. hygroscopic. infrared spectra

Rb2UO4

a‐phase: I4/mmm

orthorhombic

orthorhombic

hexagonal

orthorhombic

Symmetry

orthorhombic pseudo‐cubic

yellow. hygro‐ scopic. infrared spectra

K2UO4

a‐phase: Cmmm b‐phase: (Fmmm) Pnma

a‐phase: (Fmmm) Pnma b‐phase:

Space group

b‐phase:

yellow. hygroscopic. infrared spectra

not hygroscopic. a!b transformation 1573 K. excitation and infrared spectra

Physico‐chemical properties

Na2UO4

U(VI) compounds Li2UO4

Formula

6.595

6.592

6.499

6.91

5.807 5.804

5.73

5.11 6.065

˚) b (A

6.520

4.39 4.3917

4.354 4.353

4.344 4.335 7.98 4.32

5.98 11.708

9.76

(6.04 10.547 3.912

˚) a (A

Lattice parameters

6.921

6.924

14.82 14.803

13.86 13.869

13.13 13.13 19.78

11.70 5.970

3.50

10.52) 5.134 16.52

˚) c (A

Angle (deg) Z

4.52

4.66

5.51

5.71

6.13

Exp

7.28

6.02

X‐ray or ND

Density (g cm–3)

Zachariasen (1946); Kovba et al. (1958); Efremova et al. (1959, 1961c); Neuhaus and Recker (1959); Spitsyn et al. (1961a); Bereznikova et al. (1961); Prigent and Lucas (1965); Hoekstra (1965); Ohwada (1970a); Kovba (1971a); O’Hare and Hoekstra (1974b); Hauck (1974); Krol (1981); Volkovich et al. (1998) Wisnyi and Pijunowski (1957); Spitsyn et al. (1961a,b); Kovba et al. (1961a); Scholder and Glser (1964); Hoekstra (1965); Ohwada (1970a); Kovba (1971a); Cordfunke and Loopstra (1971); O’Hare and Hoekstra (1973); Osborne et al. (1974); Gebert et al. (1978); Volkovich et al. (1998) Hoekstra and Siegel (1956); Wisnyi and Pijunowski (1957); Spitsyn et al. (1961a,b); Hoekstra (1965); Ohwada (1970b); Kovba (1971a); O’Hare and Hoekstra (1974b); Volkovich et al. (1998) Spitsyn et al. (1961a,b); Hoekstra (1965); Ohwada (1970b); Kovba and Trunova (1971); O’Hare and Hoekstra (1974b) Spitsyn et al. (1961a,b); Hoekstra (1965); Ohwada (1970b); O’Hare and Hoekstra (1974a); van Egmond (1976b) Zachariasen (1954a); Lambertson and Mueller (1954); Ru¨dorff and Pfitzer (1954); Klı´ma et al. (1966); Jakesˇ and Schauer (1967); Ohwada (1972); Jakesˇ and Krˇivy´ (1974); O’Hare et al. (1977)

References

Table 5.17 Some physico‐chemical properties and crystal structures for alkali and alkaline earth metal uranates.

a‐phase: orange red. b‐phase: yellow, infrared and Raman spectra

orange yellow. infrared spectra

a, b, and g‐phases (Li2O · 1 . 60UO3 ¼ Li22U18O65) yellow. existence confirmed. electronic and infrared spectra

orange colored. infrared and far‐ infrared spectra

infrared and far‐ infrared spectra. possibility of two phases

SrUO4

BaUO4

LiU0.83O3

Na2U2O7

K2U2O7

Li2U2O7

yellow, not hygroscopic, infrared and far infrared spectra

CaUO4

hexagonal orthorhombic monoclinic

hexagonal

a‐phase: R3m

rhombohedral orthorhombic

orthorhombic

orthorhombic

hexagonal‐ indexing orthorhombic

rhombohedral

hexagonal‐ indexing

rhombohedral

C2/m

Pbcm

b‐phase: Pbcm (isostructural with BaUO4)

a‐phase: R3m (isostructural with CaUO4)

R3m

3.99 3.985 3.998

3.94 3.725 12.796

20.4

20.382

5.751 5.7553 5.744

5.4896

6.54 6.551 3.991

6.266 6.2683 3.87 3.876

6.660 7.822

11.6

11.511

8.135 8.1411 8.136

7.9770

19.71 19.643 19.77

17.80 11.88 6.896

11.1

11.417

8.236 8.2335 8.237

8.1297

18.361

17.54 17.558

b ¼ 111.42

a ¼ 35.53 a ¼ 34.82

a ¼ 36.03 a ¼ 36.04

2

4

1

6.6

7.84

6.66

7.26

Zachariasen (1948b); Wisnyi and Pijunowski (1957); Leonidov (1960); Kovba et al. (1961b); Anderson and Barraclough (1963); Carnall et al. (1965); Jakesˇ et al. (1966); Loopstra and Rietveld (1969); Voronov et al. (1972) Zachariasen (1948b); Ru¨dorff and Pfitzer (1954); Ippolitova et al. (1959, 1961b); Keller (1962a); Klı´ma et al. (1966); Reshetov and Kovba (1966); Cordfunke and Loopstra (1967); Loopstra and Rietveld (1969); Ohwada (1970a); Brisi (1971); Sawyer (1972); Voronov et al. (1972); Fujino et al. (1977); Tagawa and Fujino (1977); Tagawa et al. (1977) Samson and Sille´n (1947); Ru¨dorff and Pfitzer (1954); Wisnyi and Pijunowski (1957); Ippolitova et al. (1961c); Allpress (1964); Klı´ma et al. (1966); Reis, Jr. et al. (1976) Kovba (1971b); Hauck (1974); Prins and Cordfunke (1983); Griffiths and Volkovich (1999) Efremova et al. (1961c); Kovba et al. (1961b); Spitsyn et al. (1961c); Hoekstra (1965); Kovba (1971b); Toussaint and Avogadro (1974); Hauck (1974); Prins and Cordfunke (1983); Volkovich et al. (1998); Griffiths and Volkovich (1999) Sutton (1955); Neuhaus (1958); Kovba et al. (1961b); Spitsyn et al. (1961c); Hoekstra (1965); Carnall et al. (1965, 1966); Kovba (1970, 1972a); Cordfunke and Loopstra (1971); Battles et al. (1972); Volkovich et al. (1998) Kovba et al. (1958, 1961b); Ippolitova and Kovba (1961); Spitsyn et al. (1961c); Hoekstra (1965); Carnall et al. (1965); Allpress et al. (1968); Anderson (1969); Kovba (1972a); Volkovich et al. (1998)

yellow or orange green. infrared spectra

magnetic susceptibility. infrared spectra yellow. infrared spectra infrared spectra

infrared spectra

no existence claimed yellow or orange yellow. infrared spectra existence not confirmed yellow. decomposes at 1473 K forms by Cs2CO3þ 4UO3 at 873 K

CaU2O7

SrU2O7

Li2U3O10

K2U3O10

Cs2U3O10

CaU4O13

Cs2U4O13

Rb2U4O13

K2U4O13

MgU3O10

tan colored. decomposes to CaU2O7 at 1333 K in air

orange yellow. infrared spectra

Cs2U2O7

BaU2O7

decomposes at 1473 K. infrared spectra

Physico‐chemical properties

Rb2U2O7

Formula

tetragonal

hexagonal orthorhombic

Pb3/m (or Pb3) Cmcm orthorhombic

hexagonal

hexagonal

tetragonal monoclinic monoclinic

P63

a‐phase: P21/c b‐phase: P2

I41/amd

monoclinic monoclinic hexagonal

hexagonal

R3m

a‐phase: C2/m b‐phase: C2/m g‐phase: P6/mmc two orthogonal axes with 14.06 ˚ exist and 4.00 A

Symmetry

Space group

6.656

13.494

14.307

14.29

3.79 7.57

5.63 6.821 6.805

7.127

14.528 14.516 4.106

4.01 4.00 4.004

˚) a (A

4.161

15.476

18.91 19.067

4.2638 4.3199

˚) b (A

Lattice parameters

4.030

39.56

14.298

14.014

4.080 16.32

12.28 7.300 7.250

11.95

7.605 7.46 14.58

20.81 20.57 20.83

˚) c (A

Table 5.17 (Contd.)

b ¼ 121.56 b ¼ 121.12

b ¼ 112.93 b ¼ 113.78

Angle (deg)

8

2

Z

6.8

6.85

6.7

6.85

6.62

6.33

Exp

6.88

7.0

6.6

7.62 7.35 7.32

6.50

X‐ray or ND

Density (g cm–3)

Efremova et al. (1959); Allpress et al. (1968); Anderson (1969); Kovba (1970) Ippolitova et al. (1961a); Spitsyn et al. (1961c); Kovba and Trunova (1971) Efremova et al. (1959); Spitsyn et al. (1961c); Cordfunke (1975); Cordfunke et al. (1975); van Egmond (1976a) Cordfunke and Loopstra (1967)

Kovba et al. (1961b); Spitsyn et al. (1961c); Hoekstra (1965); Allpress et al. (1968); Anderson (1969); Kovba and Trunova (1971) Hoekstra (1965); Kovba and Trunova (1971); Kovba et al. (1974); Cordfunke et al. (1975); van Egmond (1976c) Hoekstra and Katz (1952); Bereznikova et al. (1961); Jakesˇ et al. (1966); Cordfunke and Loopstra (1967); Brochu and Lucas (1967) Hoekstra and Katz (1952); Klı´ma et al. (1966); Cordfunke and Loopstra (1967); Brochu and Lucas (1967) Hoekstra and Katz (1952); Allpress (1964, 1965) Efremova et al. (1961c); Spitsyn et al. (1961c); Hoekstra (1965); Kovba (1970, 1972c); Prins and Cordfunke (1983); Volkovich et al. (1998) Prigent and Lucas (1965); Anderson (1969) Efremova et al. (1961b); Cordfunke et al. (1975) Ru¨dorff and Pfitzer (1954); Polunina et al. (1961); Klı´ma et al. (1966)

References

gold colored. hygro‐ scopic. excitation and infrared spectra

red to salmon pink. very hygroscopic. infrared spectra

possibility of no existence remains preparation Rb2CO3 þ UO3 at 1273 K yellow. infrared spectra

Cs2U7O22

Li4UO5

Na4UO5

K4UO5

yellow. infrared spectra pale yellow. decomposes at 1773 K. infrared spectra

Li6UO6

Ca3UO6

yellow. infrared and Raman spectra

Sr2UO5

Ca2UO5

Rb4UO5

decomposes at 1273 K

Rb2U7O22

dark purple. decomposes to Sr2U3O11 at 1403 K solid solution with Cs2U4O13 decomposes to Li2U2.7 O9 at 1263 K existence doubtful

forms by the reaction of K2CO3 and UO4 · nH2O decomposes at 1273 K

K2U7O22

K2U6O19

Li2U6O19

Cs2U5O16

SrU4O13

orthorhombic orthorhombic

tetragonal

tetragonal

Pbam Pbam I4/m

I4/m

hexagonal monoclinic

P21 (cryolite structure)

monoclinic

P21/c

a‐phase:

monoclinic

P21/c

tetragonal

othorhombic

orthorhombic

Pbam

5.7275

8.338

8.1043

7.9137

8.18

3.50

7.576 7.536

6.736 6.720

6.949

6.958

6.945

6.95

6.701

othorhombic orthorhombic

13.465

6.734

monoclinic (pseudo‐ orthorhombic) monoclinic

5.9564

5.6614

5.4409

8.58

19.711

19.590

19.533

3.90

4.01

15.561

4.193

8.2982

7.352

11.9185

11.4482

13.73

12.95

4.641 4.630

4.45 4.451

7.3955

7.279

7.215

7.19

4.148

15.928

4.065

b ¼ 90.568

b ¼ 108.985

b ¼ 108.803

2

5.1

6.08

5.55

4.95

5.28

7.1

5.34

6.34

5.67

6.00

4.19

5.11

5.41

7.485

7.32

7.11

Bereznikova et al. (1961); Sawyer (1963); Jakesˇ et al. (1966); Cordfunke and Loopstra (1967); Loopstra and Rietveld (1969) Sawyer (1963); Keller (1964); Cordfunke and Loopstra (1967); Loopstra and Rietveld (1969); Allen and Griffiths (1977) Scholder and Glser (1964); Hauck (1973); Prins and Cordfunke (1983) Ru¨dorff and Pfitzer (1954); Ippolitova et al. (1959); Bereznikova et al. (1961); Jakesˇ et al. (1966); Rietveld (1966); Brisi (1969); Loopstra and Rietveld (1969); Voronov et al. (1972); Kemmler‐Sack and Seemann (1975)

Efremova et al. (1959); Spitsyn et al. (1961c); Kovba and Trunova (1971) Efremova et al. (1959); Spitsyn et al. (1961c); Cordfunke et al. (1975); van Egmond (1976b) Scholder (1958); Efremova et al. (1959, 1961c); Kovba (1962); Hoekstra and Siegel (1964); Reshetov and Kovba (1966); Ohwada (1971); Hauck (1974); Krol (1981) Findley et al. (1955); Efremova et al. (1959); Kovba (1962); Hoekstra and Siegel (1964); Cordfunke and Loopstra (1971); Ohwada (1971); Battles et al. (1972) Efremova et al. (1959, 1961a); Hoekstra and Siegel (1964) Efremova et al. (1959); Ippolitova et al. (1961a)

Cordfunke et al. (1975); van Egmond (1976a) Kovba (1970); Hauck (1974); Fujino et al. (1983) Efremova et al. (1959); Kovba (1961); Spitsyn et al. (1961c); Allpress et al. (1968); Anderson (1969) Kovba (1961, 1970)

b ¼ 92.78 6.82

Cordfunke and Loopstra (1967)

b ¼ 90.16

pale yellow. stable up to high temperatures. infrared and charge transfer spectra ocher. decomposes to CaU2O7 and CaUO4 at 1173 K cognac colored. stable to 1573 K. infrared and Raman spectra orange. stable to 1773 K. infrared spectra

Ba3UO6

NaUO3

red brown. magnetic susceptibility. electronic spectra. no existence of uranyl group

U(V) and U(IV) compounds black purple. LiUO3 magnetic properties. electronic spectra

Ba2U3O11

Sr2U3O11

Ca2U3O11

pale yellow. infrared and Raman spectra

Physico‐chemical properties

Sr3UO6

Formula monoclinic

cubic

P21

Fm3m (NH4)3FeF6 type structure

rhombohedral

orthorhombic

R3c LiNbO3 type

Pbnm GdFeO3 type

triclinic

tetragonal orthorhombic triclinic

Symmetry

Space group

5.775 5.776

5.901

6.484

8.922 8.90 6.825 44.63 6.186

5.9588

˚) a (A

5.905 5.910

6.523

44.31 6.212

6.1795

˚) b (A

Lattice parameters

8.25 8.283

6.484

8.943 8.973 6.186

8.5535

˚) c (A

Table 5.17 (Contd.)

a ¼ 54.60

a¼g¼ 37.12 b ¼ 37.56 a¼g¼ 35.44 b ¼ 36.10

b ¼ 90.192

Angle (deg)

1

2

Z

7.46

6.75

Exp

7.33

7.67

6.98

6.17

X‐ray or ND

Density (g cm–3)

Ru¨dorff and Leutner (1957); Ru¨dorff and Menzer (1957); Kovba (1960); Ru¨dorff et al. (1962); Kemmler (1965); Kemmler‐Sack et al. (1967); Kemmler‐ Sack (1968b); Keller (1972); Selbin et al. (1972a) Ru¨dorff and Leutner (1957); Ru¨dorff and Menzer (1957); Ippolitova et al. (1961d); Ru¨dorff et al. (1962); Prigent and Lucas (1965); Kemmler‐Sack et al. (1967); Kemmler‐Sack and Ru¨dorff (1967); Kemmler‐Sack (1968b); Bartram and Fryxell (1970); Cordfunke and Loopstra (1971); King (1971); Battles et al. (1972); Keller (1972); Selbin et al. (1972a); Lyon et al. (1977)

Allpress (1964)

Cordfunke and Loopstra (1967); Allen and Griffiths (1977)

Ru¨dorff and Pfitzer (1954); Scholder and Brixner (1955); Ippolitova et al. (1959); Sleight and Ward (1962); Rietveld (1966); Cordfunke and Loopstra (1967); Loopstra and Rietveld (1969); Kemmler‐Sack and Seemann (1975); Allen and Griffiths (1977) Ru¨dorff and Pfitzer (1954); Scholder and Brixner (1955); Ippolitova et al. (1959, 1961c); Rietveld (1966); Kemmler‐Sack and Seemann (1975) Cordfunke and Loopstra (1967)

References

ocher colored. magnetic susceptibility. electronic spectra

Li3UO4

Ba3UO5

Ba2UO4

Sr2UO4

Ca2UO4

Ba2.67U1.33O6

a‐phase: b‐phase: Fm3m

deformed CaTiO3 type

tetragonal

tetragonal cubic

cubic

4.49

6.291 8.915

8.901

6.023

5.974

6.178

same crystal structure as Ca2.5U1.33O5.83. brown. magnetic susceptibility. electronic spectra forms by the reaction of CaOþUO2 below 2023 K forms by heating Sr2UO5 in H2. forms by the same method as Sr2UO4. possibility of no existence no existence reported

Sr2.5U1.33O5.83

5.767

electronic spectra

Ca2.5U1.33O5.83

8.60 6.18

monoclinic

brown. magnetic susceptibility

BaUO3

6.101 6.03

monoclinic

(deformed CaTiO3 type)

dark brown

SrUO3

10.727

11.90

4.40 4.387 (pseudo‐cubic) 4.411

Iam Mn2O3 type

black. no existence claimed

CaUO3

4.323

4.290 4.299

3.955

6.718

cubic

cubic (high pressure form: ˚) fcc, a ¼ 5.38 A orthorhombic

Pm3m

pale brown. RbxUO3 (0.8  x  1). magnetic susceptibility. electronic spectra

RbUO3

Pm3m CaTiO3 type

cubic

Pm3m CaTiO3 type

brown. magnetic susceptibility. electronic spectra

KUO3

orthorhombic (Na0.025UO3–x) hexagonal (Na0.10UO3) cubic

green. 0 < x  0.14

NaxUO3

8.5

8.982

8.629

8.349

6.17 8.62

4.163

4.142

7.34

6.51 7.10

6.10 6.33

b ¼ 89.8

7.63

6.84

7.69

8.29

b ¼ 89.8

7.98

7.5

6.85

7.2

8.0

Trzebiatowski and Jablon´ski (1960); Keller (1964); Charvillat et al. (1970); Braun et al. (1975) Scholder (1960); Scholder and Glser (1964); Blasse (1964); Kemmler‐Sack et al. (1967); Kemmler‐Sack (1968b)

Scholder and Brixner (1955); Trzebiatowski and Jablon´ski (1960)

Scholder and Brixner (1955)

Alberman et al. (1951)

Kemmler‐Sack and Wall (1971)

Kemmler‐Sack and Seemann (1974)

Ippolitova et al. (1961d); Ru¨dorff et al. (1962); Kemmler‐Sack et al. (1967); Kemmler‐Sack and Ru¨dorff (1967); Kemmler‐Sack (1968b); Selbin et al. (1972a) Ippolitova and Kovba (1961); Ru¨dorff et al. (1962); Kemmler‐Sack et al. (1967); Kemmler‐Sack and Ru¨dorff (1967); Kemmler‐Sack (1968b); Selbin et al. (1972a) Alberman et al. (1951); Young and Schwartz (1963); Brochu and Lucas (1967) Scholder and Brixner (1955); Lang et al. (1956); Furman (1957); Brisi (1960); Keller (1964) Ru¨dorff and Pfitzer (1954); Scholder and Brixner (1955); Lang et al. (1956); Furman (1957); Trzebiatowski and Jablon´ski (1960); Fujino and Naito (1969); Braun et al. (1975) Kemmler‐Sack and Seemann (1974)

Greaves et al. (1973)

black. magnetic susceptibility

black. magnetic susceptibility

black. magnetic susceptibility (85–300 K)

CaU2O6

SrU2O6

BaU2O6

Ba2U2O7

CaU3O9

MgU2O6

non‐stoichiometric region in CaU3O9–x magnetic susceptibility. electronic spectra

a ! b at 898 K, and b ! g at 968 K. stable in air up to 1523 K black. magnetic susceptibility. electronic spectra. Mg and U atoms statistically distributed.

Cs2U4O12

Li7UO6

pale brown. low temperature Cp. high temperature Cp (298–1200 K). formula claimed to be Na11U5O16 pale green. magnetic susceptibility. electronic spectra

Physico‐chemical properties

Na3UO4

Formula cubic

cubic cubic

Fm3m NaCl type P4232 Fd3m

cubic

cubic

cubic

Fm3m CaF2 type Fm3m CaF2 type Fm3m CaF2 type

monoclinic (pseudo tetragonal)

cubic

rhombohedral monoclinic cubic cubic

a‐phase: R3m b‐phase: P21 g‐phase: Fd3m Fm3m CaF2 type

rhombohedral (hexagonal indexing)

Symmetry

Space group

˚) b (A

˚) c (A

Angle (deg)

8.002

11.56

11.31

super-structure line

5.63

5.452

5.379

10.9623 7.886 11.2295 5.284 5.275 5.281

6.61 5.52 5.55

11.56

10.793

15.80 15.76

b 90

a ¼ 89.402 b ¼ 92.62

a ¼ 53.27

4.77 4.79–4.80 4.74 9.543 (to explain superstructure lines) 9.574

˚) a (A

Lattice parameters

Table 5.17 (Contd.)

Z

7.46

6.5

Exp

7.58

9.07

8.71

X‐ray or ND

Density (g cm–3)

Kemmler‐Sack and Ru¨dorff (1967); Kemmler‐Sack (1968a,b)

Scholder (1960); Pepper (1964); Scholder and Glser (1964); Addison (1969); Bartram and Fryxell (1970); Marcon (1972); O’Hare et al. (1972); Osborne and Flotow (1972); Fredrickson and Chasanov (1972) Scholder and Glser (1964); Keller et al. (1965); Kemmler‐Sack et al. (1967); Kemmler‐Sack (1968b); Hauck (1969); Selbin et al. (1965) Cordfunke et al. (1975); Cordfunke (1975); van Egmond (1975); Cordfunke and Westrum, Jr. (1979) Hoekstra and Katz (1952); Keller (1964); Kemmler‐Sack et al. (1967); Kemmler‐Sack and Ru¨dorff (1967); Kemmler‐Sack (1968b); Fujino and Naito (1970); Selbin et al. (1972a); Fujino (1972) Hoekstra and Katz (1952); Hoekstra and Siegel (1956); Brochu and Lucas (1967) Hoekstra and Katz (1952); Hoekstra and Siegel (1956); Brochu and Lucas (1967); Tagawa et al. (1977) Hoekstra and Katz (1952); Scholder and Brixner (1955); Hoekstra and Siegel (1956); Keller (1964); Brochu and Lucas (1967) Young and Schwartz (1962, 1963)

References

Compounds of uranium

379

Fig. 5.25 Schematic atom arrangement around a uranyl group (Zachariasen, 1954b); the notation is as follows: : the inner filled circles show U in the plane of the page; the outer empty circles denote OI , one above and the other below the plane of the page; : denotes OII in the plane of the page; : denotes OII slightly above the plane of the page and : denotes OII slightly below the plane. (a) Hexagonal coordination by six OII atoms (b‐ Li2UO4, CaUO4, a‐SrUO4). Each uranium atom is coordinated with six oxygen atoms in an approximately planar arrangement. The axis of the collinear UI –U–OI group is normal to the plane of the page. (b) Tetragonal coordination by four OII atoms forming an infinite plane (BaUO4). Uranium is octahedrally coordinated by four OII atoms and two OI atoms. Each octahedron shares four corners with adjacent octahedra forming a layer structure extended in the bc plane. The Ba atoms are located between the layers and link them by electrostatic force. (c) Tetragonal coordination by four OII atoms forming an infinite chain (MgUO4). The octahedra share two opposite edges, resulting in formation of chains along the a‐axis. Reproduced by the permission of the International Union of Crystallography.

discussed in Tso et al. (1985). Note that the technique is also discussed by Keller (1972) for BaU2O7 and Ba2U3O11. Crystal structures 2þ An important feature of Mþ 2 Un O3nþ1 and M Un O3nþ1 type uranates(VI) is their layer structure and the existence of the uranyl groups, UO2þ 2 , in the crystals. The structure of monouranates (n ¼ 1) is characterized by the layer planes; the oxygen atoms on this plane are coordinated to uranium atoms forming secondary bonds. The primary bonds between the uranium and oxygen atoms of the uranyl group, OI–U–OI, are collinear and perpendicular to the layer plane. The atom arrangements around the uranyl groups are schematically drawn in Fig. 5.25 (Zachariasen, 1954b). For b‐Li2UO4 (Zachariasen, 1945), CaUO4 and a‐SrUO4 (Zachariasen, 1948b), each uranium atom is coordinated to six oxygen atoms (cf. Fig. 5.25a, viewed from the c‐axis). The axis of the UO2þ 2 group in the figure is normal to ˚ above and the page, while three of six OII atoms are located about 0.5 A ˚ below the plane through uranium and remaining three OII atoms about 0.5 A perpendicular to the UO2þ 2 axis. The oxygen atoms coordinated to uranium in

380

Uranium

BaUO4 and MgUO4 form a deformed octahedron, where each OII oxygen atom acts as a bridge between two adjacent uranium atoms. In BaUO4 the octahedra share corners (Fig. 5.25b), but in MgUO4 they share edges (Fig. 5.25c). As a consequence, infinite layers are formed in BaUO4 and infinite chains in MgUO4. The alkali or alkaline‐earth metals occupy the positions between the layers and bind them together by electrostatic force (Zachariasen, 1954b). There are no uranyl groups in Li4UO5 and Na4UO5, and the structure instead ˚ in both contains four orthogonal planar U–OI bonds (with the distance 1.99 A 2 Li4UO5 and Na4UO5), yielding UO4 ; in addition, there are also two collinear ˚ ; Na4UO5: 2.32 A ˚ ) (Hoekstra and Siegel, 1964). U–OII bonds (Li4UO5: 2.23 A The octahedra produced in this way are linked to bridges through the diagonally located OII atoms, resulting in formation of a structure containing octahedral chains running along the c‐axis. M2þ 3 UO6 ‐type compounds (M ¼ Ca, Sr, Ba) crystallize into distorted perovskite structures (2[M1/4U1/4][M5/4U1/4]O3), where the alkaline‐earth atoms and uranium atoms corresponding to [M1/4U1/4] occupy the octahedral sites in an ordered manner (Keller, 1964; Morss, 1982; Williams et al., 1984). Physicochemical properties Alkali metal monouranates(VI) are hygroscopic except for Li2UO4, and mostly yellow colored; some diuranates are orange or red‐orange. The uranates(VI) of the heavy alkali metals are volatile on heating in air. The antisymmetric stretching vibration of UO2þ 2 in uranates(VI) gives a strong absorption in the IR range of 600–900 cm–1. The frequency changes depending on the bonding strength of the coordinated oxygen atoms. Since the U–OI bonds of the uranyl group are much stronger, this vibration can be treated approximately as an isolated linear three‐atom system of CO2‐type (Jones, 1958). The U–OI distances calculated from the infrared frequencies using the empirical Badger equation are mostly in good agreement with those obtained by diffraction experiments (Hoekstra and Siegel, 1964; Allpress, 1965; Hoekstra, 1965; Carnall et al., 1966). A phase transformation coupled with oxygen non‐stoichiometry has been observed for SrUO4 and CdUO4 (Tagawa and Fujino, 1978, 1980). a‐SrUO4 can be reduced to non‐stoichiometric SrUO4–x with the maximum x value of 0.2–0.3. On heating a‐SrUO4 at different oxygen partial pressures from 10 to 600 mmHg and heating rates of 1–5 K min–1, the compound is rapidly reduced to SrUO3.8–3.9 at about 800 C. The solid is then immediately re‐oxidized to stoichiometric composition by absorbing oxygen from the gaseous phase. At the same time, it transforms into b‐SrUO4. The atom rearrangement in the phase transformation may be accelerated by the formation of vacancies in the oxygen sublattice of a‐SrUO4. Magnetic susceptibilities have been measured for MgUO4, SrUO4, BaUO4, CaU2O7, SrU2O7, and BaU2O7 (Brochu and Lucas, 1967). In these compounds U(VI) is expected to be diamagnetic, but a weak paramagnetism was observed; this is ascribed to covalency in the uranyl group (Bell, 1969).

Compounds of uranium (ii)

381

Uranates (V) and (IV)

Uranates(V) of MþUO3 (M ¼ Li, Na, K, Rb), Mþ 3 UO4 (M ¼ Li, Na), and M2þU2O6 (M ¼ Mg, Ca, Sr, Ba) types are the most well known, as are the uranates(IV) of M2þUO3 (M ¼ Ca, Sr, Ba) type. Preparation To prepare uranates(V), a symproportionation reaction is widely used, where the uranates(IV) and (VI) are first mixed in 1:1 uranium atom ratio, after which the mixture is heated in an evacuated sealed quartz ampoule. An example is the reaction Li2UO4 þ UO2 ¼ 2LiUO3, which takes place at 650–750 C. Another method is to reduce uranates(VI) by H2 at elevated temperatures; the reaction condition should be carefully defined in order to form uranates(V). Since the uranates of alkaline‐earth metals are not volatile, the high‐ temperature reduction method by H2 can be used to prepare the corresponding uranates(IV). For some uranates(VI) having high equilibrium oxygen pressures, uranates(V) can be prepared by heating the uranate(VI) in a vacuum at high temperature. The M2þU2O6 compounds are prepared by the reaction M2þ U2 O7 ¼ M2þ U2 O6 þ 1=2O2 at 1100 C (M ¼ Mg, Ca, Sr, Ba). It is, however, rather difficult to obtain stoichiometric uranates(V) by this method. Crystal structures Uranates(V) and (IV) do not contain uranyl groups and as a result, their crystal structures are in general not of the layer type and in many cases simpler. The compounds of MþUO3 and M2þUO3, with the exception of CaUO3 (cubic Mn2O3‐type structure), have perovskite or deformed perovskite‐type structures. LiUO3 crystallizes into a rhombohedrally distorted LiNbO3 structure, as a result of the small ionic radius of Liþ. NaUO3 has an orthorhombic GdFeO3 structure with small distortions from cubic perovskite structure. KUO3 and RbUO3 have cubic perovskite structures, and BaUO3 a cubic or pseudo‐cubic perovskite structure. In the uranates(V) of Mþ 3 UO4 ‐type, Li3UO4 crystallizes in a tetragonally distorted NaCl‐type structure, in which the lithium and uranium atoms are located in the cation sites in an ordered manner with an atom ratio of 3:1. All M2þU2O6 compounds have cubic fluorite‐type structures, where the alkaline‐ earth metal atoms and uranium atoms are statistically distributed with an atom ratio of 1:2 over the cation sites. Physico‐chemical properties Most uranates(V) and (IV) are brown to black. An exception is the pale green Li7UO6. Uranates(V) and (IV) dissolve in dilute mineral acids. The dissolution rate in HNO3 is higher than those in HCl and H2SO4 (Trzebiatowski and

Uranium

382

Jablon´ski, 1960; Scholder and Gla¨ser, 1964; Brochu and Lucas, 1967). Li3UO4 is oxidized to Li2UO4 in air even at room temperature. Na3UO4 absorbs significant amounts of oxygen, water, and CO2 at room temperature. On heating the uranates(V) or uranates(IV) in air, they are readily oxidized to uranates(VI). Electronic spectra have been measured for LiUO3, NaUO3, KUO3, RbUO3, MgU2O6, CdU2O6, Li3UO4, Li7UO6, Ba2U2O7, etc. in the range 4000–40000 cm–1 (Kemmler‐Sack et al., 1967). The crystal field parameters were determined for LiUO3 and Li3UO4 from the optical absorption electronic spectra (Lewis et al., 1973; Kanellakopulos et al., 1980; Hinatsu et al., 1992a,b). For KUO3 and RbUO3, the octahedral crystal field around a U5þ atom was consistently calculated with a spin–orbit coupling constant of 1770 cm–1 (Kemmler‐Sack et al., 1967; Selbin et al., 1972a). Magnetic susceptibilities have been measured for LiUO3, NaUO3, KUO3, RbUO3, Li3UO4, Li7UO6, MgU2O6, CdU2O6, and Ba2U2O7 at temperatures 85–473 K (Ru¨dorff and Menzer, 1957; Kemmler‐Sack, 1968a). In the paramagnetic temperature range, the Curie constant changed with the coordination number. The magnetic susceptibilities for MþUO3 (M ¼ Li, Na, K, Rb) were measured in a wider temperature range from 4.2 K to room temperature (Keller, 1972; Miyake et al., 1979, 1982; Kanellakopulos et al., 1980). The electron paramagnetic resonance (EPR) spectra for U5þ ions doped in LiNbO3, which has the same crystal structure as LiUO3, gave a signal at g ¼ 0.727 (Lewis et al., 1973). The EPR signals were also observed for pure MþUO3 but they were very broad (Miyake et al., 1979, 1982). LiUO3 showed a ferromagnetic transition at 16–17 K (Miyake et al., 1979, 1982; Hinatsu et al., 1992b). Li3UO4 has a distorted NaCl‐type structure and its magnetic properties have been studied by measuring the EPR spectra and magnetic susceptibility in an extended temperature range down to 4.2 K (Keller, 1972; Lewis et al., 1973; Kanellakopulos et al., 1980; Miyake et al., 1982; Hinatsu et al., 1992a). The experimental magnetic susceptibility can be well described by assuming the 5f1 electron of U5þ in an octahedral crystal field with a small tetragonal distortion with the crystal field parameters obtained from the electronic spectra (Hinatsu et al., 1992a). NaUO3 gives a magnetic transition at 32 K (Miyake et al., 1977) or 35 K (Keller, 1972), for which a l‐type anomaly has also been observed in the heat capacity (Lyon et al., 1977). The EPR and magnetic susceptibility studies for M2þU2O6 (M ¼ Mg, Ca, Cd, Sr) have been carried out (Brochu and Lucas, 1967; Miyake et al., 1993; Miyake and Fujino, 1998). The anomalies of magnetic origin have been observed at 4–7 K. (iii)

Non‐stoichiometry

The non‐stoichiometry in uranates can be classified into three types. The first type occurs when part of the alkali metal in the uranate is lost as an oxide by vaporization on heating, viz. Na2–2xU2O7–x is formed from Na2U2O7 by the loss of xNa2O (0  x  0.07) (Carnall et al., 1966; Anderson, 1969). The second type

Compounds of uranium

383

is caused by non‐stoichiometric dissolution of alkali metal in a uranium oxide. An example is NaxUO3 (0  x  0.14) (Greaves et al., 1973). The third type is the most common non‐stoichiometry, i.e. the oxygen non‐stoichiometry. Examples of such uranates are Na2U2O7–x (0  x  0.5) (Anderson, 1969), K2U2O7–x (Spitsyn et al., 1961b), Cs2U4O13–x (Cordfunke et al., 1975), CaUO4–x (0 x  0.5) (Anderson and Barraclough, 1963), a‐SrUO4–x (0  x  0.5) (Tagawa and Fujino, 1977), CaU2O7–x (0  x  0.13) and SrU2O7–x (0  x  0.4) (Hoekstra and Katz, 1952), SrU4O13–x (Cordfunke and Loopstra, 1967; Tagawa et al., 1977). Rhombohedral CaUO4 and a‐SrUO4, which crystallographically are very similar to ionic UO2, show a wide range of non‐stoichiometries, while b‐SrUO4 and BaUO4 with increased covalency have virtually no non‐stoichiometry. Examples of the third type of non‐stoichiometric compounds derived from uranate(V) are MgU2O6þx (–0.16  x  0.03), CaU2O6þx (–0.05  x  0.05), SrU2O6þx (–0.05  x  0.40.6), and BaU2O6þx (x  0.86) (Hoekstra and Katz, 1952). The non‐stoichiometric uranates are produced by heating in reducing atmospheres, but generally the U(VI) state is more stable in ternary uranates than in binary uranium oxides. This trend is more pronounced for the uranates with higher M/U ratios (M ¼ alkali metals or alkaline‐earth metals). The experimental fact that alkali and alkaline‐earth metal uranates(VI) strictly without U(V) and U(IV) are formed under certain conditions when heated in air was utilized for the determination of oxygen in uranium oxides (Fujino et al., 1978b). (c)

Transition metal uranates

Table 5.18 shows the crystallographic properties of ternary transition metal uranates. In this section the uranates of some non‐transition metals such as Sb, Tl, Pb, and Bi are included because of the resemblance of their properties. Here we present an overview of preparation methods and crystal structures. For more detailed information, the reader is referred to the following review articles (Hoekstra and Marshall, 1967; Keller, 1972, 1975). (i) Preparative methods The most general ‘dry’ method for preparation is to heat thoroughly ground mixtures of transition metal oxides and UO3 (or U3O8) in air. CrUO4, MnUO4, and CoUO4 can be synthesized by heating the mixed oxides for 1 day at 1000– 1100 C (Hoekstra and Marshall, 1967). CuUO4 is obtained by heating below 875 C. Triuranates, MU3O10 (M ¼ Mn, Co, Ni, Cu, Zn), are prepared by heating the mixtures of M/U ¼ 1/3 at 875 C. Although Ni, Cu, and Zn triuranates are readily obtained as stoichiometric compounds, Mn and Co triuranates tend to remain oxygen‐deficient. Nitrates, viz. M(NO3)2 þ UO2(NO3)2 (Weigel and Neufeldt, 1961), can also be used as starting materials for preparing MUO4 (M ¼ Cu, Zn, Cd, Hg),

dark brown

CoUO4

brownish yellow

a‐CdUO4

orthorhombic

orthorhombic

Imma

bright red

orthorhombic

Imma

ZnUO4

orthorhombic

Pbcn

monoclinic

orthorhombic

Imma

P21/n

orthorhombic

Pbcn

coffee brown

orthorhombic

Imma

7.01

6.492

5.475

6.472

4.820

6.497

4.888

6.645

4.871

6.020 7.727 7.739 3.78–3.81

orthorhombic tetragonal tetragonal cubic orthorhombic

˚) a (A

Symmetry

Pbcn

Space group

CuUO4

b‐NiUO4

a‐NiUO4

black

dark brown

brown brown

Color

FeUO4

MnUO4

EuUO3 U0.25NbO3 U0.25TaO3 UxWO3 (x 0 regardless of the M metal. (ii)

The solid solution regions

M 4þ y U 1y O2þx The solubility data on this system are diverse. The Zr solid solution with y ¼ 0.15 was obtained by heating at 1500 C (Une and Oguma, 1983a); at 1750 C, solid solutions with y values up to 0.3 were obtained (Aronson and Clayton, 1961). The solid solution with the highest y value, 0.35, has been obtained by heating the mixture of UO2(NO3)2 · 6H2O and ZrOCl2 · 8H2O in H2 at 1650 C (Hinatsu and Fujino, 1985). The Zr solid solution is regarded as metastable at lower temperatures.

Zr SOLID SOLUTIONS

Th solid solutions are formed continuously from y ¼ 0 to 1 for x ¼ 0. However, for x > 0, there is an upper limit in the solubility. According to Paul and Keller (1971), the single‐phase solid solutions under 1 atm O2 exist below y ¼ 0.45, 0.40, and 0.36 at 1100, 1400, and 1550 C, respectively. The lower limits at pO2 ¼ 0.2 atm are y ¼ 0.383, 0.359, 0.253, and 0.068 for 700, 1200, 1400, and 1500 C, respectively (Gilpatrick et al., 1964), which is in agreement with the value of y ¼ 0.22 below 1400 C reported by Anderson et al. (1954). The maximum x value is 0.25 at temperatures between 1250 and 1550 C for y  0.5. At lower temperatures of 600–1100 C, the upper limit of x decreases to 0.12–0.14 for y values below 0.4 (Cohen and Berman, 1966; Paul and Keller, 1971). Th SOLID SOLUTIONS

Table 5.19 Lattice parameter change with composition of solid solutions MyU1–yO2þx (Fujino and Miyake, 1991). Element

@a=@y

Zr

–0.302 –0.301 0.163 (y  0.05) 0.127 (0.1  y  0.5) –0.146 –0.0747 (x ¼ 0) –0.0727 (x < 0)

Th Np Pu

Sc Y La

Ce

Pr Nd

Sm Eu Gd Ho Yb Lu Mg

–0.438 –0.521 –0.233 –0.254 –0.266 0.094 (x > 0) 0.06 (x < 0) 0.073 (x ¼ 0) –0.067 –0.06 –0.057 (x ¼ 0)

–0.007 –0.015 –0.047 –0.057 –0.058 –0.075 –0.118 –0.121 –0.138 –0.144 –0.151 –0.164 –0.171 –0.173 –0.267 –0.315 –0.356 –0.568 –0.546 –0.559

@a=@x

References

–0.14 (x > 0)

Cohen and Schaner (1963); Hinatsu and Fujino (1985) Cohen and Berman (1966)

–0.345 (x < 0)

Tabuteau et al. (1984) Schmitz et al. (1971);

–0.313 (x < 0) –0.274 (x < 0)

–0.131 (x > 0) –0.2 (x < 0) –0.285 (x < 0)

–0.321 (x < 0) –0.288 (y ¼ 0.282, –0.015x < 0) –0.127 (x > 0) –0.397 (x < 0) –0.112 (x > 0)

–0.30 (x < 0)

–0.30 (x < 0) –0.24 (x < 0)

–0.117 (x > 0)

Martin and Shinn (1971); Mignanelli and Potter (1986) Hinatsu and Fujino (1986); Keller et al. (1972) Fukushima et al. (1981); Weitzel and Keller (1975); Ohmichi et al. (1981) Hinatsu and Fujino (1987); Weitzel and Keller (1975); Hill et al. (1963) Mignanelli and Potter (1983); Lorenzelli and Touzelin (1980); Hinatsu and Fujino (1988a); Markin et al. (1970); Norris and Kay (1983) Yamashita et al. (1985); Hinatsu and Fujino (1988c) Hinatsu and Fujino (1988b); Fukushima et al. (1983); Weitzel and Keller (1975); Ohmichi et al. (1981); Wadier (1973) Fukushima et al. (1983); Ru¨dorff et al. (1967) Fukushima et al. (1983); Ohmichi et al. (1981); Fujino et al. (1990) Fukushima et al. (1982); Ru¨dorff et al. (1967); Ohmichi et al. (1981) Weitzel and Keller (1975) Ru¨dorff et al. (1967) Weitzel and Keller (1975) Fujino and Naito (1970); Kemmler‐Sack and Ru¨dorff (1967); Keller (1964)

Uranium

392

Table 5.19 (Contd.) Element

@a=@y

@a=@x

Ca

–0.310

Sr

–0.213 –0.289 –0.098

–0.102 (x > 0) –0.190 (x < 0) –0.10 (x > 0)

Mn Cd

–0.055 –0.499 –0.340

Bi

0.149

References

–0.109 (x > 0) –0.244 (x < 0)

Yamashita and Fujino (1985); Hinatsu and Fujino (1988d); Loopstra and Rietveld (1969) Fujino et al. (1988); Hoekstra and Katz (1952) Kemmler‐Sack and Ru¨dorff (1967) Keller (1962b); Kemmler‐Sack and Ru¨dorff (1967) Ru¨dorff et al. (1967)

M 4þ3þ U 1y O2þx y Ce solid solutions are formed continuously from y ¼ 0 to 1 for x ¼ 0. For x < 0, the region of the single‐phase solid solution is restricted to y  0.35 (Markin et al., 1970) or y  0.2 (Lorenzelli and Touzelin, 1980). Above this value up to y ¼ 0.7, the products are two phases (Ce,U)O2.00 and (Ce,U)O2–x at room temperature. Further reduction results in formation of single‐phase solid solutions. The x values for the single‐phase solid solutions are x < –0.04, –0.12, –0.19, and –0.24 for y ¼ 0.1, 0.3, 0.5, and 0.7, respectively (Lorenzelli and Touzelin, 1980). In the hyperstoichiometric range of 0  x  0.18, the solid solutions with y < 0.5 are a single phase at room temperature. Air‐oxidized hyperstoichiometric solid solutions crystallize in a fluorite‐type single phase in the region of high Ce concentrations (Hoch and Furman, 1966). Single‐phase regions exist in y ¼ 0.56–1.0 (1100 C), 0.43–1.0 (1250  C), and 0.26–1.0 (1550 C) (Paul, 1970). Single phases with y ¼ 0.6–1.0 at 1100 C have also been reported (Tagawa et al., 1981a). Ce SOLID SOLUTIONS

M nþ y U 1y O2þx ðn ¼ 3 and 2Þ The solid solutions obtained by heating in reducing atmospheres are generally hypostoichiometric. The x values are highly negative when strong reductants such as H2 or CO are used. The single‐phase regions of fcc solid solutions with M metals (M ¼ rare‐earth elements, alkaline‐earth metals, and Cd) are shown in Table 5.20. In reducing atmosphere, the single‐phase solid solution forms essentially in a range starting from y ¼ 0. For M2þ metals, the maximum y values are around 1/3. If the monoxides of Mg and Ba are heated with UO2 in a vacuum, the solubility is very low even at high temperatures due to shortage of oxygen (cf. Table 5.20).

SOLID SOLUTIONS IN REDUCING ATMOSPHERE

0–33 (CdUO4þUO2, vacuum sealed tube)

Cd



Ba

0–30 (SrUO4þU3O8þUO2, 1200–1400 C, 1 Pa O2) 33 (SrU2O7, vacuum)

0–20 (1300 C) 33 (BaU2O7, 1200 C, vacuum) 33 (BaU2O7, 600 C, NH3)

Sr

0–33 (CaUO4þU3O8þUO2, 1100–1300 C, vacuum)

Ca 3–33 (1200–1400 C, He)

0–33 (MgUO4þMgU3O10þUO2, 1100–1300 C, He)

Mg

Gd

0–70 (1350 C, vacuum) 0–42 (Ar)

0–2.1

Pr Eu

0–1.8

1400

0–82

0–1.6

Sc Y

1250

La

1100

Element

Temperature ( C)

0–50 (H2) 0–65 (2000 C, vacuum)

1700

0–3 (BaOþUO2, vac.)

0–20(CaOþUO2, 1650 C, vac.)

0–5 (MgOþUO2, 2350 C, vac.) 0–40 (2000 C)

0–53 (1600 C, vacuum) 0–5060 (vacuum) 0–80 (H2) 0–50 (Ar)

0–54 (1750 C, vacuum) 0–75 (1750 C, H2 or vac.)

0–2.9 (H2)

1550

Fujino and Naito (1970); Anderson and Johnson (1953) Brisi et al. (1972); Voronov and Sofronova (1972); Yamashita and Fujino (1985); Alberman et al. (1951) Fujino et al. (1988); Hoekstra and Siegel (1956); Ippolitova et al. (1961b); Brisi et al. (1972) Hoekstra and Siegel (1956); Brochu and Lucas (1967); Kleykamp (1985) Kemmler‐Sack and Ru¨dorff (1967)

Yamashita et al. (1985) Berndt et al. (1976); Grossman et al. (1967); Fujino et al. (1990) Beals and Handwerk (1965)

Diehl and Keller (1971); Wilson et al. (1961); Hill et al. (1963)

Keller et al. (1972) Bartram et al. (1964); Ferguson and Fogg (1957)

References

Table 5.20 Single phase regions of fcc solid solutions MyU1–yO2þx with M elements (rare‐earth elements, alkaline‐earth elements and Cd ) prepared in reducing atmospheres. Concentrations of the M elements are shown in mol%.

Uranium

394

The single‐phase regions of fcc solid solutions prepared in oxidizing atmospheres are shown in Table 5.21. UO2 is oxidized to U3O8 when heated in oxidizing atmospheres unless mixed with the M elements. Hence, the lower limit of the fcc single phase is not y ¼ 0 but at higher values. The x value changes with y value in a rather simple way for rare‐earth solid solutions: For Nd solid solutions heated under pO2 ¼ 1 atm at 1100 C for example, the mean uranium valence remains constant (þ5) when the y value is in a region between 0.3 and 0.5, i.e. x changes as x¼1/2y. The uranium valence then increases linearly from þ5 to þ6 when y increases from 0.5 to 0.67, during which x ¼ 0. For the solid solutions in a higher y range, 0.67– 0.75, the uranium valence is U(VI). Here, the x value decreases linearly from 0 to –0.125 (x¼13y/2) with increasing y value in order to satisfy the charge neutrality condition (Keller and Boroujerdi, 1972).

SOLID SOLUTIONS IN OXIDIZING ATMOSPHERE

(iii)

Oxygen potentials

M 4þ y U 1y O2þx The oxygen potential of ZryU1–yO2þx solid solution is  lower than that of UO2þx. At 1250 K, the DGðO 2 Þ value for Zr solid solution –1 with y ¼ 0.3 is –270 kJ mol at x ¼ 0.05 (Aronson and Clayton, 1961), while  that for UO2þx at x ¼ 0.05 is ca. –210 kJ mol–1. The low DHðO 2 Þ of ZryU1–y  O2þx has been suggested to explain the low DGðO2 Þ of this solid solution. The –1  DHðO for ZryU1–yO2þx, 2 Þ values vary between –480 and –355 kJ mol which are significantly lower than those between –355 and –270 kJ mol–1 for ThyU1–yO2þx (Aronson and Clayton, 1960, 1961; Une and Oguma, 1983a). Zr SOLID SOLUTIONS

 Dissolution of Th causes an increase in DGðO 2 Þ with  increasing value of y. The difference in DGðO2 Þ between Th solid solution and UO2þx is small if the concentration of Th is low (viz., y ¼ 0.1). However, at  high Th concentration with y ¼ 0.71 (x ¼ 0.05), DGðO 2 Þ of the solid solution at –1 1250 K is as high as –150 kJ mol (Aronson and Clayton, 1960). This value is  60 kJ mol–1 higher than DGðO 2 Þ of UO2.05 at the same temperature. There have been other thermodynamic studies on this solid solution (Tanaka et al., 1972; Ugajin, 1982; Ugajin et al., 1983; Matsui and Naito, 1985a). Th SOLID SOLUTIONS

M 4þ3þ U 1y O2þx y Because two oxidation states, Ce3þ and Ce4þ, are possible for Ce in oxides, the oxygen potential of Ce solid solution changes over a wide range of x‐values from negative to positive values, giving rise to a   rapid (‘vertical’) change of DGðO 2 Þ at x ¼ 0. The shape of the DGðO2 Þ curve is  very similar to that of PuyU1–yO2þx, but the DGðO Þ values of CeyU1–yO2þx 2  are markedly higher. Namely, DGðO Þ for Ce U O is as high as –460 0.25 0.75 1.95 2 kJ mol–1 at 1200 C, compared to the value of –570 kJ mol–1 for Pu0.25U0.75O1.95. Ce SOLID SOLUTIONS

Gd Dy Ho Er Tm Yb Lu Mg

Sm Eu

Nd

Pr

La

1300

48.4–74.9 47.0–64.0 49.0–62.5 48.5–64.0 48.5–64.5 48.0–65.5

44.1–72.8 (1250 C) 43.0–64.0 (1250 C) 45.0–62.5 (1250 C) 45.0–64.0 (1250 C) 45.0–64.5 (1250 C) 45.0–65.5 (1250 C) 36–39 (1300 C, air)

35.0–72.8 33.0–64.0 41.0–62.5 34.0–64.0 38.5–64.5 43.0–65.5 12–39 (1500 C, air)

30–72

50–60 (1000 C, air) 39–72 36–72 (1250 C) 38–64 (air)

35.0–74.5

25–81

43.2–69.0

25–82

45.5–64.9

1400

33–81 (1250 C)

32–71 (1350 C, air)

41.4–70.2

77–82

26.5–75

48.5–64.0 (1250 C)

1200

33–60 (1000 C, air) 30–65 (air) 31.5–51.5 28.5–55 68.5 63.5–69.5 79.5–82 79–82 30–45, 70–90 (1000 C, air) 38.6–71.9 39.9–71.2 30–60 (1250 C)

49.5–63.8

Sc

Y

1100

Element

Temperature ( C)

30–60 (1700 C, air) 14.2–72.2 (1550 C) 19.0–64.0 (1550 C) 21.5–62.5 (1550 C) 15.0–64.0 (1550 C) 16.5–64.5 (1550 C) 41.0–65.5 (1550 C) 0–39 (1600 C, air) max. 37 (1600– 1700 C, air)

25–72

13–81 (1550 C)

45.3–67.1

30–80 (1650 C)

24–82 (1550 C)

42.1–65.5 (1510 C) 0–65.7 (1550 C)

1500

Hill et al. (1963); Tagawa et al. (1983) de Alleluia et al. (1981); Jocher (1978); Yamashita et al. (1985) Boroujerdi (1971); Keller and Boroujerdi (1972) Tagawa et al. (1981b) Tanamas (1974); Haug and Weigel (1963) Beals and Handwerk (1965) de Alleluia et al. (1981) Keller et al. (1969) Keller et al. (1969) Keller et al. (1969) Keller et al. (1969) Keller et al. (1969) Sugisaki et al. (1973); Budnikov et al. (1958)

Bartram et al. (1964); Hund et al. (1965) Diehl and Keller (1971);

Keller et al. (1972)

References

Table 5.21 Single‐phase regions of fcc solid solutions MyU1–yO2þx with M elements (rare‐earth elements and Mg) prepared in oxidizing atmospheres. Atmosphere is O2 (1 atm) unless otherwise described. Concentrations of the M elements are shown in mol%.

396

Uranium

 This difference has been attributed to the higher DGðO 2 Þ value of CeO2–x (Panlener et al., 1975) compared with that of PuO2–x (Woodley, 1981). The  DGðO 2 Þ measurements of the Ce solid solutions have been carried out by a number of researchers (Hoch and Furman, 1966; Markin and Crough, 1970; Ducroux and Baptiste, 1981; Norris and Kay, 1983; Nagarajan et al., 1985). The Pr solid solutions have lower values of 3þ  DGðO rare‐earth ions, because of the 2 Þ than the solid solutions with solely M 3þ 4þ two possible oxidation states, Pr and Pr (Jocher, 1978; Fujino and Miyake,  1991). The situation is the same for Am solid solutions, although their DGðO 2Þ values are markedly higher than those of Pu and Ce solid solutions (Bartscher and Sari, 1983).

Pr AND Am SOLID SOLUTIONS

M 3þ y U 1y O2þx A large number of oxygen potential measurements for the M3þ solid solutions have been carried out. These comprise solid solutions of Y (Aitken and Joseph, 1966; Hagemark and Broli, 1967; Nakajima et al., 2002), La (Hagemark and Broli, 1967; Stadlbauer et al., 1974; Matsui and Naito, 1986), Pr (Jocher, 1978; Fujino and Miyake, 1991), Nd (Wadier, 1973; Une and Oguma, 1983c), Eu (Tanamas, 1974; Lindemer and Brynestad, 1986; Fujino et al., 1990, 1999), and Gd (Une and Oguma, 1982, 1983b; Lindemer and Sutton, Jr. 1988). 3þ  DGðO 2 Þ for My U1y O2þx can be defined from x ¼ y/2 to positive x values; the measured oxygen potential increases with increasing x value, passing  through an inflection point at x ¼ 0, where DGðO 2 Þ increases very rapidly.  The dissolution of M3þ metals enhances DGðO Þ more than do the M4þ metals. 2   The DGðO 2 Þ value increases with increasing y, but the DGðO2 Þ curve gradually levels off at high M3þ concentrations. In a series of rare‐earth solid solutions,  the La solid solution shows the highest DGðO 2 Þ values, which is assumed to be associated with the fact that La3þ has the largest ionic radius of these M3þ ions.  With increasing atomic number of the lanthanides, DGðO 2 Þ is lowered, although  the DGðO Þ difference between the Nd and Gd solid solutions is small. Fig. 5.26 2 shows the oxygen potential of GdyU1–yO2þx as a function of O/(GdþU) ratio (¼2 þ x).  The Eu solid solutions show a much higher value of DGðO 2 Þ than the other M3þ solid solutions (Lindemer and Brynestad, 1986). This is possibly due to the coexistence of Eu2þ and Eu3þ in the solid solutions (Fujino et al., 1990). It is  noteworthy that the inflection point of DGðO 2 Þ for Eu solid solutions is shifted to a range of x < 0 values. This is also observed for M2þ y U1y O2þx , supporting the presence of Eu2þ in the Eu solid solutions. M 2þ y U 1y O2þx The oxygen potential of MgyU1–yO2þx (Fujino and Naito, 1970; Fujino et al., 1978a; Tateno et al., 1979) is significantly higher than those of M3þ y U1y O2þx .  Moreover, the x values at which the ‘vertical’ change of DGðO Þ 2 takes place,

Compounds of uranium

397

Fig. 5.26 Oxygen potential of GdyU1–yO2þx as a function of O/(GdþU) ratio (Fujino and Miyake, 1991). Solid lines: Une and Oguma (1983b); Broken lines: Lindemer and Sutton, Jr. (1988). Reproduced by the permission of Elsevier.

which are also the inflection points, are negative in contrast to the M4þ and M3þ solid solutions, where the value of x at the inflection is zero. This negative shift for MgyU1–yO2þx becomes more pronounced at higher values of y, viz., x ¼ 0.07 at y ¼ 0.3 (1200–1500 C) (Sugisaki and Sueyoshi, 1978).  The high DGðO 2 Þ values are supposed to be rationalized by a configurational entropy change. Dissolution of M2þ metals in UO2 results in formation of a larger number of U5þ ions in the solid solution crystals, which increases the number of ways, W, of arranging the cations on the cation sites. The entropy,  2 Þ; described by the relation DSðO  DSðO 2 Þ ¼ 2R @ ln W =@ðxNÞ; where N is the Avogadro’s number (Aronson and Clayton, 1960; Hagemark and Broli, 1967; Fujino and Miyake, 1991), shows therefore a significant decrease. For the Mg  solid solutions Fujino et al. (1992, 1995, 1997b) claim that the DGðO 2 Þ shift is explained if the charge complexes of the form, (M2þ2U5þ), in which the corresponding cations have their normal sites, are formed together with (M2þU5þ) complexes. In the oxygen potential curves for (Mg,Gd,U)O2þx (Fujino et al., 2001a) and (Mg,Ce,U)O2þx (Fujino et al., 2001b), the shift to negative x values is even larger than in the Mg solid solution.

Uranium

398

When the oxygen partial pressure is very low, high concentrations of Mg cannot dissolve in UO2. The solubility of Mg is in a range 0.1 < y < 0.15 for pO2 ¼ 10–1510–19 atm at 1200 C (Fujino et al., 1997a).

5.7.3

Uranium borides, carbides, silicides, and related compounds

Non‐oxide p‐block compounds of uranium represent a large family that share certain similarities with oxides in that non‐stoichiometric compounds exist; these are especially well noted for the heavy p‐block elements of a semi‐metallic nature (e.g. Sb and Te). Oxidation state assignment for uranium in some of these compounds can be very tedious, owing to the presence of homoatomic bonding between main group elements where the E ··· E (E ¼ main group element) contacts between main group elements is intermediate in length between a full single bond and a van der Waals contact. This phenomenon is particularly common in antimonides and tellurides. Full descriptions of all known binaries and especially of ternary and quaternary phases are not possible in the present context. Further historical details can be found in Waber et al. (1964), Eding and Carr (1961), Freeman and Darby (1974), and in a series of IAEA bibliographies (Maximov, 1963, 1965, 1967).

(a)

Uranium–boron system

The only known binary uranium borides are UB2, UB4, and UB12. The crystal structure data for these compounds are given in Table 5.22. The former compounds have been prepared by direct reaction of the elements at high temperatures (Wedekind and Jochem, 1913). Mixtures of UB12 and UB4 have also been deposited by fused‐salt electrolysis (Andrieux, 1948; Andrieux and Blum, 1949). It has recently been demonstrated that UB4 can be prepared by the solid‐state metathesis reaction of UCl4 with MgB2 at 850 C (Lupinetti et al., 2002). UCl4 þ 2MgB2 ! UB4 þ 2MgCl2 A view of the structure of UB4 is shown in Fig. 5.27. The phase diagram of the U–B system is shown in Fig. 5.28 (Howlett, 1959, 1960; Elliott, 1965; Chiotti et al., 1981). In addition, there is mass spectroscopic evidence that supports the existence of UB and UB2 in the gas phase (Gingerich, 1970). The dissociation energies Do0 were reported as (318 33) kJ mol–1 for UB and (949 42) kJ mol–1 for UB2. Uranium borides are remarkably inert, and borides have been proposed as a potential form for storing transuranium waste generated from the nuclear fuel cycle (Lupinetti et al., 2002). There are some differences in reactivity of the uranium borides with respect to one another. UB4 is generally more reactive

Compounds of uranium

Fig. 5.27 clarity.

399

A view down the c‐axis of the structure of UB4. U–B bonds have been omitted for

than UB12. For example, boiling HF, HCl, and H2SO4 attack UB12 very slowly, but react more rapidly with UB4, allowing for the separation of the two compounds. Both UB4 and UB12 can be dissolved in HNO3–H2O2 mixtures. Ternary uranium borides have been extensively investigated for their rich variation in bonding and their complex physical properties. Compounds in this class include U5Mo10B24, which contains three different kinds of B polyanions: two‐dimensional puckered sheets formed from six‐ and eight‐membered rings, planar ribbons composed of six‐membered B rings, and chains of condensed eight‐membered rings (Konrad and Jeitschko, 1996). UNi4B has been extensively investigated and is a geometrically frustrated antiferromagnetic compound that partially orders below TN ¼ 20 K (Mentink et al., 1998). (b)

Uranium–carbon system

The uranium–carbon system has been studied by a number of teams including Rundle et al. (1948), Esch and Schneider (1948), Litz et al. (1948), Wilhelm et al. (1949), and Mallett et al. (1952). The uranium–carbon system bear some similarities with that of uranium with other first‐row p‐block elements in that in addition to discrete, stoichiometric compounds, there are three known phases, UC, UC2, and U2C3 that can be of variable composition. The complex phase diagram of the uranium–carbon system is shown in Fig. 5.29. Among other things this diagram demonstrates that UC and UC2 are completely miscible with one another at elevated temperatures and under these conditions the entire range UC–UC2 is homogeneous. At lower temperatures, miscibility is much more limited and the exact extent of variability in composition for each of the carbides is still to be determined.

400

Uranium

Fig. 5.28 Phase diagram of the uranium–boron system (Chiotti et al., 1981).

Litz et al. (1948) were the first to study the preparation of UC and UC2. U2C3 is an unusual compound in that it has not been prepared by the direct reaction of the elements at high temperatures; this reaction invariably yields UC and UC2 (Mallet et al., 1952). However, U2C3 is obtained when a mixture of UC and UC2 is heated in the range 1250–1800 C in vacuo. It is essential that the fused mixture be given a certain amount of stressing and cold working to initiate the nucleation necessary for the formation of the U2C3 phase; once formed it is stable at room temperature. Table 5.22 lists some of the crystallographic data for the uranium carbides. An illustration of the structure of UC2 is shown in Fig. 5.30.

tetragonal fcc fcc cubic tetragonal cubic cubic tetr. bc hexagonal orthorhombic tetragonal tetr. bc cubic orthorhombic orthorhombic hexagonal hexagonal

P4/mbm Fm3m Fm3m I43d I4/mmm Pm3m I41/amd P6/mmm Pbnm P4/mbm I4/mcm Pm3m Cmmm Pbcm P63/mcm P63/mcm

metallic metallic

gray‐black black light gray light gray

silvery

silvery black

UB4 UB12

UC(d1) U2C3 UC2(z) UC2(d2)

USi3(1) USi1.88(Z)d

U3Si5(t)e USi(z)f

UGe3 UGeg2 UGej U5 Gek4 U3Ge3 U5 Gel;m 3 U7Ge h,m

metallic metallic metallic metallic metallic

hexagonal

P6/mmm

metallic

UB2

U3Si2(ε) U3Si(d)

Symmetry

Space group

Color

Formula

8.58

4.2062 4.036 9.827 8.744

7.3299 6.029

4.060 3.948 3.930 3.843 5.66

4.961 8.088 3.5266 5.488

3.1293b 3.1314c 7.075 4.4773

14.928 8.932

7.67

5.79

4.116 5.841 5.863

3.9004 9.696

13.67 14.06 4.069 3.91

6.0023

3.9893b 3.9857c 3.979

2

1 4 12 2

2 4

1 4

1 4

4 8 2 4

4 4

1

Z

11.31

7.27 9.30

7.27

9.32 5.65

12.8

12.66

10.37 10.26 12.07 12.67

12.20 15.58

9.25 10.40

8.15 8.98

13.63 12.88 11.68

9.38 5.825

12.82

X‐ray

Meas.

˚) c (A

˚) a (A

˚) b (A

Density (g cm–3)

Lattice parameters

Table 5.22 Crystallographic data for the stoichiometric binary uranium compounds with boron and group IV elements (Chiotti et al., 1981).a

metallic metallic

metallic metallic

USn3 U3Sn5 U5Sn4

UPbg3 UPbg,i cubic tetr. bc tetr. fc

cubic

Pm3m

Fm3m

Symmetry

Space group

˚) c (A Z

4.7915 11.04 4.579

4.626

10.60 5.259

1

13.27

12.93

10.0

X‐ray

Meas.

˚) b (A

˚) a (A

b

a

Unless otherwise mentioned, the data are taken from Chiotti et al. (1981). Boron‐rich phase. c Boron‐poor phase. d USi1.88 is also referred to as a‐USi2. e U3Si5 is also referred to as b‐USi2. f According to Laugier et al. (1971), USi is tetragonal. The orthorhombic structure is due to oxygen. g Boulet et al., (1997a). h Existence of these compounds deduced from vapor pressure data taken by Alcock and Grieveson (1962, 1963). i The different lattice constants are due to different interpretations of powder patterns. j Boulet et al. (1997b). k Boulet et al. (1997c). l Marakov and Bykov (1959). May be the same phase as U5Ge4. m The existence of U5Ge3 and U7Ge has been called into question (Boulet et al., 1997c), and they are likely mixture of U5Ge4 and U metal dissolving 3% of germanium.

Color

Formula

Density (g cm–3)

Lattice parameters

Table 5.22 (Contd.)

Compounds of uranium

403

Fig. 5.29 Phase diagram of the uranium–carbon system (Wilkinson, 1962).

The uranium carbides can undergo a number of hydrolysis reactions; finely divided UC2 is pyrophoric. The carbides react with water to yield a variety of products. Lebeau and Damien (1913) found that upon hydrolysis of UC2, in addition to hydrogen, methane, and ethane, significant amounts of liquid and

404

Uranium

Fig. 5.30 A view down the a‐axis of the structure of UC2.

solid hydrocarbons are produced. Litz (1948) made an exhaustive study of the hydrolysis of UC and UC2, the value of which is limited by the fact that he worked only at temperatures above 83 C and did not measure the quantity of gas evolved or analyze the solid residue for carbon compounds. Bradley and Ferris (1962, 1964) made a very careful study of the hydrolysis of arc‐melted UC (1962) and of UC2, U–UC mixtures, and UC–UC2 mixtures (1964) at temperatures between 25 and 99 C. In the case of UC, the hydrolysis yielded a gelatinous, hydrous uranium(IV) oxide and a gaseous mixture (93 mL (STP) per gram UC), which consisted of 86 vol% methane, 11 vol% hydrogen, 1.8 vol% ethane, and small quantities of saturated C3–C6 hydrocarbons. The gaseous products contained all the carbon originally present in the carbide. The total amount of carbon originally present in the carbide was also recovered in the hydrocarbon hydrolysis products of UC2, U–UC, and UC–UC2 mixtures. In the case of arc‐melted UC(1.85 0.03), 36 different hydrocarbons were identified. The reaction product contained 15 vol% methane, 28 vol% ethane, 7 vol% C3–C6 alkanes, 8 vol% alkenes, 0.6 vol% alkynes, 1 vol% unidentified un‐saturates, and 40 vol% hydrogen. Approximately 25% of the total carbon was found as a water‐insoluble wax. In the hydrolysis of UC–UC2 mixtures, a linear decrease of the volume percentage of CH4 and linear increases of the percentages of hydrogen and the C2–C8 hydrocarbons were observed as the combined C/U atom ratio increased from 1.0 to 1.85. For UC–UC2 mixtures, less methane than expected was evolved. This indicates that some polymerization of C units had occurred. Bunnell et al. (1975) studied the hydrolysis of bare and defect‐coated UC2 fuel bead cores by water vapor at pH2O ¼ 24–76 mmHg. They studied the reaction products by optical and scanning electron microscopies, identified hydrogen, methane, and ethane as the major reaction products, and measured the activation energy to be (25.4 2.9) kJ mol–1.

Compounds of uranium

405

In air, UC2 decomposes completely in a week, presumably as a result of hydrolysis. According to Mallet et al. (1952), U2C3 does not react appreciably with water even at 75 C. UC2 appears to be stable in air at 300 C, but is completely converted to oxide in air within 4 h at 400–500 C. UC2 reacts at 1100 C with nitrogen to form uranium nitride. Since the reactions of the carbides are greatly affected by the particle size of the solid and the previous thermal history of the sample, no far‐reaching conclusions should be drawn regarding the relative reactivity of the uranium carbides. The uranium carbides have found an important application as nuclear fuels in fast reactors. This type of application and related properties has been discussed in a number of uranium carbide conferences (see Proceedings, 1960a,b, 1961, 1963). One of the problems with reprocessing the spent fuels from these reactors is that oxalic acid is also produced in the dissolution of mixed uranium and plutonium carbides in HNO3. Complexation of UO2þ 2 by oxalate can account for the problems of incomplete uranium and plutonium extraction in the PUREX process for fuel reprocessing (Choppin et al., 1983). Ternary carbides, such as U2Al3C4, can be prepared by melting the elements in a carbon crucible in a high‐frequency radiofrequency (RF) furnace (Gesing and Jeitschko, 1995). The structure of U2Al3C4 is closely related to that of Al4C3. Much like binary uranium carbides, U2Al3C4 undergoes hydrolysis reactions in dilute HCl resulting in the formation of 74 (wt.)% methane, 8% ethane and ethylene, and 18% saturated and unsaturated higher hydrocarbons. Laser‐ablated U atoms react with CO in a noble gas matrix to form CUO (Li et al., 2002). This molecule exhibits different stretching frequencies in a solid Ar matrix from those in a solid Ne matrix. Further experiments suggest that Ar atoms interact directly with CUO molecules to form an actinide–noble gas compound. The combination of experimental and theoretical methods suggests that multiple Ar atoms interact with a single CUO molecule. (c)

Uranium–silicon system

The uranium–silicon system is remarkably rich and a large number of uranium silicides including U3Si, U3Si2, USi, U3Si5, USi1.88, and USi3 have been prepared and crystallographically characterized (Zachariasen, 1949a; Kaufman et al., 1957). The phase diagram, shown in Fig. 5.31, is based on earlier work reported in the compilations by Hansen and Anderko (1958), Elliott (1965), and Shunk (1969), and in the paper by Vaugoyeau et al. (1971), which has been assessed and discussed by Chiotti et al. (1981). Further details on the composition ranges of the two phases U3Si5 and USi1.88 are given by Vaugoyeau et al. (1971). U3Si5 melts congruently at 2043 K (1770 C) and has a composition range USi1.71 to USi1.78 (63–64 at % Si) in the temperature range 1000–1300 C. The phase USi1.88, in the same temperature range, has a composition span USi1.79 to USi1.84 (64–64.8 at % Si).

406

Uranium

Fig. 5.31 Phase diagram of the U–Si system (Chiotti et al., 1981).

The two‐phase region between the two compounds is very narrow. The compound USi was shown to decompose peritectically at 1580 C and has a narrow homogeneity range. The eutectic between U3Si2 and USi occurs at 1540 C and 46 at % Si. As can be inferred from this information and from the data in Table 5.22, the U–Si phase diagram is very complicated. However, the uranium silicides are of technical importance. For instance, compounds such as U(Al,Si)3 are formed in the layer between the uranium metal and the aluminum can in natural uranium fuel elements (Cunningham and Adams, 1957). Because of the chemical inertness of some of the uranium silicides, these compounds promise more applications. Crystal structures of the U–Si compounds are also summarized in Table 5.22. Ternary uranium silicides are well established from compounds such as UCu2Si2 (Fisk et al., 2003), U2Nb3Si4 (Le Bihan et al., 2000), and URu2Si2 (Sugiyama and Onuki, 2003). Single crystals of UCu2Si2 prepared from a Cu flux undergo a 50 K antiferromagnetic transition below the 100 K ferromagnetic transition (Fisk et al., 2003). U2Nb3Si4 is weakly ferromagnetic below 35 K (Le Bihan et al., 2000). Finally, URu2Si2 is one of the most studied heavy fermion materials (Sugiyama and Onuki, 2003).

Compounds of uranium (d)

407

Uranium–germanium, uranium–tin, and uranium–lead systems

The uranium–germanium system is as complex as that of uranium silicides. U7Ge (vide infra), U5Ge3 (vide infra), U5Ge4, UGe2, and UGe have all been characterized and subjected to extensive physical property measurements (Onuki et al., 1992). The compound originally formulated as U3Ge4 has been shown to be a mixture of UGe and U3Ge5. Detailed studies including magnetic structure determination via neutron diffraction have been performed on UGe2, which is an unusual example of a ferromagnetic superconductor (Saxena, 2000; Sheikin et al., 2000; Nishioka et al., 2002). This compound was originally reported to crystallize in the ZrSi2 (Cmcm) structure type, but in fact crystallizes in the ZrGa2 (Cmmm) type (Oikawa et al., 1996; Boulet et al., 1997a). U5Ge3 and U7Ge both undergo a transition to a superconducting phase below 2 K (Onuki et al., 1990). However, the existence of both of these compounds has been called into question (Boulet et al., 1997c), and they are likely mixture of U5Ge4 and U metal dissolving 3% of germanium. The uranium–tin phase diagram has been described by Palenzona and Manfrinetti (1995). U5Sn4 (Ti5Ga4‐type), USn (ThIn‐type), USn2 (ZrGa2‐ type), U3Sn7 (Ce3Sn7‐type), and USn3 (AuCu3‐type) were identified from this work. Dhar et al. (1998) have assessed the magnetic properties of these compounds. U5Sn4 and USn are ferromagnetically ordered below 62 and 49 K, respectively; USn2 and U3Sn7 attain an antiferromagnetic state near 80 K. Shunk (1969) and Chiotti et al. (1981) have reported the phase diagram for the uranium–lead system.

5.7.4

Uranium pnictides

The systems U–N, U–P, U–As, U–Sb, and U–Bi have been studied in great detail. In particular, the monopnictides UN, UP, and UAs have found major interest because of their solid‐state properties, which are relatively easy to study because of their cubic (NaCl) structure. Physical and crystallographic data of the pnictides are summarized in Table 5.23. The thermodynamic properties of uranium and other actinide nitrides are briefly summarized in Chapter 19. Additional information on uranium nitrides and heavier pnictides is available in Gmelin (1981b, vol. C7; 1981d, vol. C14).

(a)

Uranium–nitrogen system

Rundle et al. (1948) established the existence of the following uranium nitride phases: UN, U2N3, and UN1.75, while the phase UN2 could not be confirmed. Berthold et al. (1957) and Berthold and Delliehausen (1966) succeeded, however, in preparing a phase UN1.90 by reacting uranium hydride with ammonia at

metallic

UN UNb a‐U2N3 b-U2 Nc3 UN1.45 UNdx UN1.76 UN1.90

metallic grey

metallic metallic

UAs U3As4

metallic

UP UPb U3P4 UP2

black black

black

Color

Formula fcc rhombohedral cubic hexagonal

Fm3m R3m Ia3 P3m1

fcc rhombohedral bcc tetragonal fcc bcc

Fm3m R3m I43d P4/nmm Fm3m I43d

2705e

bcc

Symmetry

Space group

2610

2850

m.p. ( C)



5.7788 8.507

5.5889 7.583 8.207 3.808

10.628

4.889 3.170 10.678 3.700 10.700

˚) a (A

7.780

9.433

5.825

8.635

˚) c (A

Lattice parameters

4 4

4 12 4 2

4 3 16

Z

10.77

10.23 11.41

14.32 16.7 11.24 12.45

X‐ray

Density Exp.

Table 5.23 Crystallographic data of uranium pnictides (Rough and Bauer, 1958; Hansen and Anderko, 1958; Waber et al., 1964; Elliot, 1965; Shunk, 1969).a

metallic metallic metallic metallic metallic metallic metallic metallic

U5 Sbg4

1400–1450e 1150f 1010f

1850 1695f 1335f

P63/mcm Fm3m I43d P4/mmm Fm3m P4/nmm I43d P4/nmm

P4/nmm hexagonal fcc bcc tetragonal cubic tetr.bc bcc tetragonal

tetragonal 9.237 6.203 9.113 4.272 6.364 11.12 9.350 4.445

3.954

8.908

10.55

8.759

6.211

8.116 2 4 4 2 4 24 4 2

2

10.84 10.04 11.52 13.6 12.57 12.38

12.14

9.8

12.8 12.36

10.7 10.5

a Unless otherwise mentioned, the data are taken from Rough and Bauer (1958), Hansen and Anderko (1958), Waber et al. (1964), Elliot (1965), Shunk (1969). b High‐pressure phase (Olsen et al., 1985, 1988). c Masaki and Tagawa (1975). d ˚. Solid solutions ranging from UN1.45 through UN1.76, lattice constant decreasing from 10.700 to 10.628 A e With decomposition. f With peritectic decomposition. g Paixa˜o et al. (1994). This phase was originally formulated as U4Sb3.

USb U3Sb4 USb2 a‐UBi(d1) b‐UBi(d2) U3Bi4 (ε) UBi2

metallic

UAs2

410

Uranium

elevated temperatures. Bugl and Bauer (1964) have studied the U–N system in detail. The nitrides can be prepared by reaction of very pure uranium metal (or uranium hydride prepared from such metal) with nitriding agents. The surface of the uranium metal has to be pickled with nearly concentrated HNO3, and then washed with organic solvents to remove even traces of oxide and oil films, which might lead to the formation of oxide or carbide contaminants. The nitriding agents also have to be of high purity. Uranium mononitride can be prepared (i) by reaction of uranium metal (or uranium hydride) with nitrogen or ammonia, (ii) by the thermal decomposition of higher nitrides at or above 1300 C, or (iii) by the reduction of higher nitrides with uranium metal. U2N3 can be prepared by reacting UC with NH3 or a N2/H2 gas mixture (Nakagawa et al., 1997). The reaction with ammonia is advantageous because NH3 acts as both a nitriding agent and as a carbon‐clearing agent. Fitzmaurice and Parkin (1994) report that various uranium nitrides could be prepared from the self‐propagating reaction of UCl4 with Li3N. Mallett and Gerds (1955) made a kinetic study of the reaction of uranium metal with nitrogen in the temperature range 550–900 C and at atmospheric pressure. Surface reaction products were identified by X‐ray diffraction methods. At 775–900 C it was found that all three nitride phases were present. The intermediate nitride U2N3 is prepared by similar methods or by reduction of UN1.75 with hydrogen. Since U2N3 loses nitrogen above 700 C in vacuo, the preparative procedure must take this into account. The nitride UN1.75 cannot be prepared at all by reaction of the metal with nitrogen, unless a high pressure of nitrogen is used. There appears to be a two‐phase region between UN and U2N3, but the region between U2N3 and UN1.75 appears to be homogeneous. A tentative phase diagram of the system is shown in Fig. 5.32. All of the higher uranium nitrides are thermally unstable relative to UN. UN is easily oxidized by air and is decomposed by water vapor; it is not attacked by either hot or cold hydrochloric or sulfuric acids, but is attacked by molten alkali. U2N3 can be used for the catalytic cracking of ammonia (Rizzo da Rocha et al., 1995). Schmitz‐Dumont et al. (1954) described the interesting uranium compound uranyl amide, UO2(NH2)2. This compound can be prepared by the reaction of potassium uranyl nitrate, KUO2(NO3)3, with potassium amide in liquid ammonia. Uranyl amide is a brown, amorphous substance that is unaffected by dry oxygen at room temperature. Moisture, however, converts the amide to ammonium diuranate. The uranium amido chlorides, UNH2Cl2 and U(NH2)2Cl, can be obtained by reacting UCl3 with ammonia at 450 to 500 C. Increased heating of these compounds results in their conversion to U(NH)Cl and then UN1.73–1.75 (Berthold and Knecht, 1965a). The reaction of Li3N with UH3 at 900 C results in the formation of LiUN2 (Jacobs et al., 2003). The structure is related to the anatase type with the octahedral sites occupied by Li. Ca3UN4 can be prepared by reacting Ca (NH2)2 and UH3 between 600 and 1000 C (Heckers et al., 2003). X‐ray and

Compounds of uranium

411

Fig. 5.32 Phase diagram of the U–N system (Shunk, 1969).

neutron diffraction studies on this phase show that it crystallizes in the NaCl structure type with statistical occupation of the cation site by three Ca atoms and one U atom. (b) Uranium–phosphorus, uranium–arsenic, and uranium–antimony, and uranium–bismuth systems In the systems U–P, U–As, U–Sb, and U–Bi, the compounds UX, U3X4, and UX2 (where X ¼ P, As, Sb, or Bi) have been reported. Compounds UX have the cubic NaCl structure for all X, with the exception of b‐UBi, which is tetragonal body‐centered. U3X4 is body‐centered cubic and UX2 tetragonal for all X. At least four methods have been applied for preparation of the pnictides: direct synthesis from the elements in an autoclave (Albutt et al., 1964) or in a sealed tube, for instance (Iandelli, 1952). 2U þ P4 ! 2UP2 the reaction of uranium hydride with phosphine or arsine, for instance

Uranium

412

UH3 þ PH3 ! UP þ 3H2 and finally by circulating gaseous phosphine or arsine over slightly heated hydride (Baskin and Shalek, 1964; Baskin, 1969). For the preparation of the phosphides, a PH3‐loaded stream of argon is passed over the hydride, which is heated at 400–500 C. For the preparation of the arsenides, AsH3 is reacted with UH3 at 300 C. The reaction products are annealed at 1200–1400 C. Single crystals of UAs2 have been grown by reacting uranium metal with a Cs3As7 flux (Albrecht‐Schmitt et al., 2000). Finally, uranium phosphides, arsenides, and antimonides can be prepared from the reaction of UCl4 with sodium pnictides (Fitzmaurice and Parkin, 1994). Buhrer (1969), Spirlet (1979), and Vogt (1982) succeeded in growing single crystals of most uranium pnictides by gas‐phase transport, using TeCl4, I2, and other transporting agents. The crystals grown in this manner allow the determination of physical properties such as magnetic susceptibilities, magnetic phase diagrams (Busch et al., 1979a), or the measurement of the de Haas–van Alphen effect (Henkie et al., 1981); the uranium pnictides are particularly well suited for such measurements. Normally, they should exhibit isotropic behavior because of their structure, but the presence of anisotropy in the cubic crystals suggests the formation of magnetic domains. U3P4 and U3As4 are both metallic ferromagnets with itinerant 5f electrons (Inada et al., 2001). The binary compounds of the systems U–Sb and U–Bi may be prepared directly from the elements, or by reacting uranium with alkali metal antimonide and bismuthide fluxes. The binary phase diagram of U–Sb was originally investigated by Beaudry and Daane (1959). Among the binary compounds discovered in this system was a uranium‐rich phase (d) that forms a eutectic with USb at 1770 C. This compound was originally formulated as U4Sb3. Magnetic susceptibility measurements on a compound with this nominal composition show ferromagnetic behavior below 86 K (Troc´, 1992). However, later microprobe analysis, neutron scattering, and single crystal X‐ray diffraction data were utilized to establish that the actual composition of this phase is U5Sb4 (Paixa˜o et al., 1994); this compound crystallizes in the Ti5Ga4 structure type. Paixa˜o et al. (1994) have demonstrated that U5Sb4 shows highly anisotropic ferromagnetic behavior below 86 K. 5.7.5

Uranium chalcogenides

The binary, ternary, and quaternary uranium sulfides, selenides, and tellurides have been the subject of intense investigation for more than 160 years. U–Po compounds are currently unknown owing to the high radioactivity and rarity of polonium. A significant number of the chalcogenide phases deduced before 1980 were reinvestigated over the past two decades, primarily by single‐crystal X‐ray diffraction, as a number of previously known compounds were assigned incorrect space groups, unit cells, and compositions.

Compounds of uranium (a)

413

Uranium–sulfur system

Uranium sulfide in the form of US2 was first prepared in the mid‐1800s (Pe´ligot, 1842; Herrmann, 1861). This compound was followed by the preparation of US and U2S3, which were identified by Alibegoff (1886); these studies pre‐date the discovery of X‐rays. Systematic X‐ray powder diffraction investigations did not take place until 1943 (Strotzer et al. 1943), when seven distinct phases were identified from their powder patterns, but these were not indexed. The phase diagram of the uranium–sulfur system is shown in Fig. 5.33. Based on later systematic studies of the uranium–sulfur system by Eastman et al. (1950), Zachariasen (1949b) was able to elucidate the crystal structures of many of the previously synthesized phases. Mills (1974) has compiled thermodynamic data for these phases. Crystal structure data for the uranium chalcogenides and oxychalcogenides are given in Table 5.24. The uranium sulfides can be prepared by heating uranium or uranium hydride with H2S, or by heating the elements together in a sealed tube. Lower sulfides may be obtained by thermal decomposition of the higher sulfides in vacuo at high temperatures. g‐US2 can be prepared from what is thought to be a topotactic reaction of U3S5 with sulfur (Kohlmann and Beck, 1997). a‐UX2 compounds (X ¼ S, Se) were previously reported to crystallize in I4/ mcm, but based on single crystal X‐ray data they are now known to crystallize in P4/ncc (Noe¨l and Le Marouille, 1984). U3S5 has been the subject of a large number of studies that have concluded that the compound is mixed‐valent, containing both U3þ and U4þ; it can be formulated as (U3þ)2(U4þ)(S2–)5 (Noe¨l and Prigent, 1980; Kohlmann and Beck, 2000). A view of the structure of U3S5 is shown in Fig. 5.34.

Fig. 5.33 Tentative phase diagram of the U–S system (Cordfunke, 1969).

monoc.

tetrag. fcc cubic

P21/m

P4/nmm Fm3m I43d

Black, shiny

blackc

Black

Black, shiny

US3

UOSe

USe

U3Se4

1680d

hexag.

P62m

Steel gray

g‐US2

b‐US2

1850 orthor.

Steel gray

a-USb2

orthor.

cubic orthor.

Fm3m Pbnm

Pbab

Blue‐black

U3S5

2462 1850

tetrag.

P4/nmm

Steel gray

silvery black Blue‐black

US U2S3

Symmetry

Space group

tetrag.

Black

UOS

m.p. ( C)

P4/ncc

Color

Formula 3.483

8.820

5.7399

3.9035

5.40

7.236

4.4803

10.293

7.42

5.484 10.34

a

3.90

7.439

8.11

10.58

b

Lattice parameters

3.885

6.697

6.9823

18.26

4.062

4.1209

6.374

11.74

c

80.5

b

4

4

2

4

3

4

10

4

4 4

2

Z

10.07

10.40

5.9

8.12

8.07

8.16

8.94

Obs.

9.97

11.13

10.38

5.86

8.17

8.09

8.01

8.26

10.87 8.96

9.64

Calc.

Density (g/cm3)

Table 5.24 Crystallographic data for uranium chalcogenides and oxychalcogenides.a

Murasik et al. (1968) Kruger and Moser (1967) Khodadad (1960); Khodadad (1961); Noe¨l (1985a)

Picon and Flahaut (1968) Zachariasen (1949b) Picon and Flahaut (1968) Potol et al. (1972) Noe¨l and Le Marouille (1984) Suski et al. (1972) Picon and Flahaut (1968); Daoudi et al. (1996); Kohlmann and Beck (1997) Picon and Flahaut (1968); Marcon (1969)

References

orthor. hexag.

monoc.

tetrag.

tetrag. fcc

cubic cubic

Pnma P62m

P21/m

P4/nmm

I4/m Fm3m

I43d I43d

1740

1540d

blackf

Black

Black, shiny

Gray‐black

Gray‐black

Gray‐black

Black

Black, shiny

g‐USe2

USe3

UOTe

U2O2Te

UTe

U3Te4

a‐U2Te3

b‐USe2

tetrag.

1160d

1460

I4/mcm

Black

a-USee2

hexag.

P63/m

Black

U7Se12

orthor.

Pnma

1560d

Black

U3Se5

orthor.

Pnma

1610

Black

U2Se3

9.3960

9.3980

6.150

3.9640

4.004

5.652

7.6376

7.455

10.765

11.385

12.292

10.94

4.056

4.2320

8.459

11.33

12.564

7.491

10.469

4.1924

8.964

6.660

4.099

7.799

4.06

4

4

4

2

2

2

3

4

10

1

4

4

9.02

9.80

10.37

10.55

7.25

9.07

9.08

9.04

9.42

9.81

9.81

10.55

7.25

9.31

9.3

9.03

9.14

9.40

Khodadad (1959, 1961) Breeze and Brett (1972) Breeze and Brett (1972) Noe¨l and Le Marouille (1984) Breeze and Brett (1972); Noe¨l et al. (1996) Breeze and Brett (1972); Kohlmann and Beck (1997) Breeze and Brett (1972); Ben Salem et al. (1984) Klein‐Haneveld and Jellinek (1964); Breeze et al. (1971) Breeze et al. (1971) Kruger and Moser (1967); Klein‐Haneveld and Jellinek (1964) Matson et al. (1963) Matson et al. (1963)

Black

UTe1.78

orthor.

tetrag.

P4/nmm

Black

UTe1.77

U7Te12

orthor.

hexag.

Black

g‐U3Te5

1300d

P6

Black

b‐U3Te5

hexag.

Black

Black

a‐U3Te5

orthor.

Pnma

1500d

orthor.

Black

b‐U2Te3

Symmetry

Space group

m.p. ( C)

Pnma

Color

Formula

4.162

4.243

12.312

16.098

7.99

12.25

12.175

a

6.134

4.210

8.73

4.370

b

Lattice parameters

Table 5.24 (Contd.)

13.973

8.946

4.260

14.060

12.88

4.23

11.828

c b

4

2

1

4

4

Z Obs.

9.8

9.49

9.42

9.06

Calc.

Density (g/cm3)

Suski et al. (1976); Tougait et al. (1998b) Ellert et al. (1975) Slovyanskikh et al. (1977) Tougait et al. (1998a) Breeze et al. (1971); Breeze and Brett (1971); Tougait et al. (1998c) Klein‐Haneveld and Jellinek (1969); Klein‐Haneveld and Jellinek (1970) Breeze et al. (1971)

References

Black

Black

Black

Black

a‐UTe3

b‐UTe3

U2Te5

U0.9Te3g UTe5

monoc.

orthor. monoc. monoc. orthor.

Cmcm C2/m Cmcm Pnma

orthor.

Pnnn

P21/m

orthor.

Immm

4.3537 17.915

34.42

4.338

6.0987

4.24

4.1619

24.792 10.407

4.181

24.743

4.2229

6.16

6.1277

4.3541 4.220

6.074

4.338

10.325

14.52

13.961

95.4

98.2

4 4

4

4

2

4

4

8.4

8.5

8.85

7.83

8.68

9.20

Klein‐Haneveld and Jellinek (1970); Boehme et al. (1992) Ellert et al. (1971) Montignie (1947) Breeze et al. (1971); Boehme et al. (1992); Stoewe (1996a) Noe¨l and Levet (1989) Stoewe (1996b); Tougait et al. (1997) Stoewe (1997a) Slovyanskikh et al. (1967); Noe¨l (1985b)

b

Compiled from Gmelin (1981, vol. C11, 1984, vol. C10) and from original literature. Old sources listing a‐US2 refer to US1.80‐US1.93. The single crystal structure of a‐US2 is known. c Most of the selenides and tellurides, if prepared in sealed tubes, are obtained as free‐running black powders. In some cases, single crystals have been prepared by gas‐phase transport. d Peritectic decomposition temperature of the solid‐state phase. e a‐USe2 can refer to the phase USe1.88 and has variable lattice parameters. f Obtained as black crystals with metallic luster. g This compound has been previously reported in the literature as UTe3.38. Powder diffraction data suggests that the uranium content may equal U0.724Te3 (Boehme et al., 1992).

a

935d

Black

U3Te7

490d

950d

Black

b‐UTe2

1180d

Dark gray

a‐UTe2

418

Uranium

Fig. 5.34 A view down the a‐axis of the structure of U3S5. This is a mixed valence compound and should be formulated as (U3þ)2(U4þ)(S2–)5.

(b)

Uranium–selenium and uranium‐tellurium systems

The selenides and tellurides of uranium have also been studied extensively. A large number of individual phases have been identified and characterized by their X‐ray patterns. The crystallographic data of the individual phases have also been summarized in Table 5.24. The phase diagrams of the systems U–Se and U–Te are shown in Figs. 5.35 and 5.36, respectively. The b modification of UTe3, which was originally thought to adopt the NdTe3 structure type, has been shown to be non‐stoichiometric with uranium defects, giving rise to a formulation of U0.9Te3 (Stoewe, 1997a). This compound is identical to the previously known binary uranium telluride, formulated as UTe3.38, and shows variable composition with U content ranging from 0.87 to 0.93. X‐ray powder diffraction data suggest even a larger defect concentration consistent with a formula of U0.724Te3 (Boehme et al., 1992). Te–Te bonding exists in a number of uranium telluride phases, making oxidation state assignment difficult. For example, one‐dimensional tellurium chains exist in UTe2. Therefore the compound is not (U4þ)(Te2–)2 but rather (U3þ)(Te2–)(Te1–) (Stoewe, 1997b). A view of the structure of UTe2 is shown in Fig. 5.37. The selenides and tellurides can be prepared by similar methods as the sulfides, i.e. reaction of uranium powder prepared from the hydride with H2Se or H2Te, synthesis from the elements at controlled temperatures in sealed tubes, or thermal decomposition of the higher selenides or tellurides. For a more detailed description of the solid‐state properties of USe and UTe,

Compounds of uranium

419

Fig. 5.35 Phase diagram of the U–Se system (Klein‐Haneveld and Jellinek, 1964).

Fig. 5.36 Phase diagram of the U–Te system (Slovyanskikh et al., 1977).

Uranium

420

Fig. 5.37 A view down the a‐axis of the structure UTe2. There are one‐dimensional chains formed from Te–Te bonding, leading to the composition (U3þ)(Te)(Te2).

see Gmelin (1981c, vol. C11) and the Proceedings of the International Conference on the Physics of Actinides and Related 4f Materials (Wachter, 1980). U2Te5 has been prepared from the direct reaction of the elements, and single crystals grown by using TeBr4 as a chemical transport reagent (Stoewe, 1996b). Uranium chalcogenides can also be prepared by reacting UCl4 with Li2X (X ¼ S, Se, Te) (Fitzmaurice and Parkin, 1994). Narducci and Ibers (1998) have reviewed the ternary and quaternary uranium chalcogenides. These compounds range from simple perovskite‐type compounds with ABX3 (X ¼ S, Se, Te) formula to complex, tellurium‐deficient compounds such as one‐dimensional Cs8Hf5UTe30.6 (Cody et al., 1995; Cody and Ibers, 1995). The oxidation state of uranium in these compounds is often called into question due to the presence of ˚ , which are considerably shorter than the Te ··· Te contacts on the order of 3 A ˚ van der Waals distance (4.10 A), but longer than a full Te–Te single bond ˚ ). This results in a formal oxidation state for the tellurium with a non‐ (2.76 A integral value; hence, the oxidation state of uranium is ambiguous. 5.7.6

Uranium halides and related compounds

The halides and complex halides are one of the most thoroughly studied classes of uranium compounds. They have found use in many industrial applications, uranium hexafluoride, tetrachloride, and trichloride in large‐scale isotope separation of 235U and uranium tetrafluoride as a component of molten‐salt reactor fuels as well as for the preparation of uranium metal. The most stable halides are formed with uranium in the 6þ and 4þ oxidation states. Experimental investigations gave evidence for increasing U 5f participation in the chemical bonds in the more covalent compounds. Ionicity is largest for halides with uranium in higher oxidation states and with the more electronegative halogens. An exception to this rule is UF3, which is reported to be more covalent than UCl3 (Thibaut et al., 1982). Uranium in oxidation states 5þ and 6þ forms linear 2þ uranyl groups UOþ 2 and UO2 . These possess covalent, substitution inert bonds and act like single species with respect to the halogen atoms. Lau and Hildenbrand (1982, 1984) have presented thermochemical data for gaseous

Compounds of uranium

421

U–Fn and U–Cln species (where n ¼ 1, 2, 3, 4, or 5), obtained from mass spectrometric investigations of high‐temperature reaction equilibria. The chemistry of uranium halides has been reviewed in numerous papers and books, e.g. Katz and Sheft (1960), Hodge (1960), Pascal (1962–1970), Bagnall (1967, 1987), Caillat (1961), Chatalet (1967), Brown (1968, 1972, 1973, 1979), Johnson et al. (1974), Manes (1985), and Eick (1994). Several reviews were devoted to particular aspects of the halides: the crystallographic data of actinide halides have been reported by Taylor (1976a) and of their binary compounds with non‐metallic elements by Benedict (1987); the results of spectroscopic investigations were presented by Carnall (1982), Carnall and Crosswhite (1985), Baer (1984), and Wilmarth and Peterson (1981); the magnetism of actinide compounds by Santini et al. (1999); EPR by Kanellakopulos (1983); the thermodynamic data by Kubaschewski and Alcock (1979), Fuger et al. (1983), Grenthe et al. (1992), and Guillaumont et al., (2003); the industrial production of uranium hexafluoride by Hellberg and Schneider (1981), and the properties of uranium in molten salts and metals by Martinot (1984, 1991). A number of review papers have been also devoted to a particular oxidation state or group of uranium halides, e.g. Structural systematics in actinide fluoride complexes (Penneman et al., 1973), Verbindungen mit Fluor (Bacher and Jacob, 1980), Actinide fluorides (Freestone and Holloway, 1991), Uranium hexafluoride. Its chemistry related to its major application (Bacher and Jacob, 1986), Compounds of uranium with chlorine, bromine, iodine (Brown, 1979), Heptavalent actinides (Keller, 1985), Complex compounds of uranium (Bagnall, 1979), Comprehensive coordination chemistry II – The Actinides (Burns et al., 2004), Magnetochemistry of uranium(V) complexes and compounds (Miyake, 1991), Chemistry of tervalent uranium (Droz˙dz˙yn´ski, 1991). In order to keep the reference number at a reasonable limit these review articles will be frequently cited as the source of chemical and physical properties of the compounds. In each of the following subsections the uranium halides and related compounds are discussed in order of increasing valence state and some of their physical properties summarized in subsequent tables. Although references to original literature data have been kept in these tables, the citation of thermodynamic data have been limited to the most important binary compounds as Chapter 19 of this work is devoted to thermodynamic properties of the actinides. (a)

Tervalent halides and complex halides

The first tervalent uranium compound, UCl3, was prepared by Pe´ligot (1842), and until the end of the 1960s the binary trihalides have been almost the only ones investigated. The crucial reason was the large sensitivity to oxidation and very poor solubility in aprotic organic solvents of all at that time known uranium(III) compounds. During the last 30 years the development of new experimental methods made it possible to prepare almost 150 uranium(III)

422

Uranium

compounds (Droz˙dz˙yn´ski, 1991). However, the uranium trihalides and complex halides still remain the only relatively well‐investigated group. The stability of the trihalides decreases with increase in the atomic number of the halide. Apart from UF3, all the halides are more or less hygroscopic and easily oxidized in air. In aqueous solutions they are rapidly oxidized but in pure, thoroughly deoxygenated solvents the U3þ ions are fairly stable. Concentrated hydrochloric acid gives intensely deep‐red solutions, characteristic of the [UCln]3–n complex anions. With the exception of UF3, UCl3 and uranium(III) fluoro complexes, the halides are also readily soluble in some more polar solvents. The compounds exhibit a variety of colors (see Table 5.25). The preparation of somewhat more stable hydrated uranium(III) complexes have also been reported. Since all of them are readily soluble in water they are efflorescent in a humid atmosphere. For binary halides the following anion polyhedra have been identified: five capped trigonal prism (UF3), tricapped trigonal prism (UCl3, UBr3), and bicapped trigonal prism (UI3). The synthesis of uranium(III) halides and complex halides requires a rather complex equipment and strictly oxygen‐free conditions. At temperatures higher than 600 C the syntheses ought to be carried out in tantalum or molybdenum tubes in order to avoid side reactions with silica; Droz˙dz˙yn´ski (1991) has reported a survey of the preparation methods. Trivalent uranium has a [Rn] 5f3 electronic configuration with the 4I9/2 ground state. A number of crystal‐field analyses of high‐resolution low‐temperature absorption spectra have been reported for U3þ‐doped single crystals of LiYF4 (S4) (Simoni et al., 1995), LaCl3 (C3h) (Crosswhite et al., 1980; Carnall, 1989; Karbowiak et al., 2002a), LaBr3 (C3h) (Sobczyk et al., 2005), RbY2Cl7 (C2v) (Karbowiak et al., 1997), K2UX5 (Cs) (X ¼ Cl, Br or I) (Karbowiak et al. 1998a), Cs2NaYCl6 (Oh) and Cs2LiYCl6 (Oh) (Karbowiak et al., 1998b), Ba2YCl7 (C1) Karbowiak et al., 2002b, Cs2NaYBr6 (Karbowiak et al., 2003a), CsCdBr3 (Karbowiak et al., 2003b), Cs3Lu2Cl9(C3v) and Cs3Y2I9 (C3v) (Karbowiak et al. 2005a). Such analyses have been also performed for polycrystalline samples of UCl3 and UBr3 (C3h) (Sobczyk et al., 2003), UCl3 · 7H2O (Ci) (Karbowiak et al., 2001), CsUCl4 · 3H2O (Cs), NH4UCl4 · 4H2O (C2) (Karbowiak et al., 2000), and ZnCl2‐based glass (Deren´ et al., 1998). However, only the U3þ‐doped single crystals of LaCl3 and LiYF4 exhibit suitable site symmetry for precise energy‐level investigations, using selection rules for electric and magnetic dipole transitions. The energy levels of the U3þ ion in the different site symmetries were assigned and fitted to a semiempirical Hamiltonian representing the combined atomic and crystal‐field interactions. Ab initio calculations made it possible to use a simplified parametrization and the determination of the starting values in the angular overlap model in cases where the U3þ ion had the lowest site symmetry (Karbowiak et al., 2000). The free ion and crystal‐field parameters obtained from an analysis of low‐temperature absorption spectra of thin films of UF3, UCl3, and UBr3 are presented in Table 5.25. In addition, an analysis of low‐temperature absorption, luminescence, and excitation

Selected properties and physical datab

grey to black powder or purplish black crystals. density: 8.9 g cm3; disproportionates above 1000 C UF3(cr): Df Gom ¼ 1432.5 (4.7){, o ¼ 123.4 Df Hmo ¼ 1501.4(4.7){, Sm { { o (0.4) ; Cp;m ¼ 95.1(0.4) . UF3(g): Df Gom ¼ 1062.9 (20.2){, Df Hmo ¼ o 1065.0 (20){, Sm ¼ 347.5(10){; { o Cp;m ¼ 76.2(5.0) . log p(mm Hg) ¼ 4187T 1 þ3.945 meff. ¼ 3.67 B.M. (125–300K)d; y ¼ 110 K. meff. ¼ 3.66 B.M. (293– 723K)d; y ¼ 98 K, Atomic and crystal‐field parameters: Eavg ¼ 20 006 (30), F2 ¼ 38068 (108), F 4 ¼ 32256 (177), F 6 ¼ 16372 (198), z5f ¼ 1613 (11); a ¼ 26.1 (6), b ¼ 793 (40), g ¼ 2085 (104); T 2 ¼ [298.0], T 3 ¼ [48.0], T 4 ¼ [255.0], T 6 ¼ [–285.0], T 7 ¼ [332.0], T 8 ¼ [305.0]; M0 ¼ [0.67], M2 ¼ [0.37], M4 ¼ [0.26]; P2 ¼ [1276], P 4 ¼ [608], P6 ¼ [122];B 20 ¼ 216(60), B 22 ¼ 319(49), B 40 ¼ 1479 (78), B 42 ¼ 679(62), B 44 ¼ 1615(62), B 60 ¼ 2373 (79), B 62 ¼ 2201 (62), B 64 ¼ 1631(630), B 66 ¼ 1106 (63); n ¼ 75; rms ¼ 33.6.

Formula

UF3

3 , P63cm, No. 185; hexagonal; C6v Z ¼ 6; or trigonal: P 3c1, D43d , No. 165; Z ¼ 6, CN ¼ 11, a ¼ 7.173, c ¼ 7.341; d(calc.) ¼ 8.95 to 8.99; d(exp.) ¼ 9.18. LaF3 structure type; The bond lengths to the corresponding prism atoms in P 3cl are 3.01 (2), 2.48 (2) and 2.63 (2) and in P63cm these are 2.53 (2), 2.81 (2), 2.45 and 3.09, respectively. The cap atoms in both structures have fit firmly (bond lengths 2.42–2.48.)

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm3)c

X‐ray single‐crystal and neutron diffraction data (Zalkin et al., 1967; Taylor 1976a; Zachariasen, 1975); Synthesis (Runnals, 1953; Warf, 1958; Friedman et al., 1970; Berndt, 1973); absorption spectra (Schmieder et al., 1970); photoelectron spectra (Thibaut et al., 1982); crystal‐field analysis (Droz˙dz˙yn´ski et al., 2002); mechanical and thermal properties (Bacher and Jacobs, 1980); EPR, NMR and magnetic susceptibility data (Berger and Sienko, 1967; Dao, Nguyen Nghi et al., 1964; Kanellakopulos, 1983); fused‐salt systems (Martinot, 1984); thermodynamic properties (Brown, 1973, 1979; Grenthe et al., 1992; Guillaumont et al., 2003)

Remarks regarding information available and references

Table 5.25 Properties of selected uranium(III) halides and complex halides.a

peritectic decomposition point of a‐NaUF4: 775 C; a–b transformation temp. 595 C

NaUF4

purple‐brown, extremely moisture sensitive

purple‐brown, extremely moisture sensitive

Rb3UF6

Cs3UF6

RbUF4

peritectic point: 750 C

purple‐brown, extremely moisture sensitive

K3UF6

K3U2F9

dark‐blue peritectic point: 848 C

KUF4 K2UF5

Na2UF5

Selected properties and physical datab

Formula

cubic, face centered; a ¼ 10.6

cubic; CaF2structure type ; a ¼ 6.00 (1); Z ¼ 0.8; d(calc.) ¼ 4.67 hexagonal; KYF4 structure type ; a ¼ 8.54(1), c ¼ 10.72(2); Z ¼ 6, d(calc.) ¼ 5.84 cubic, face centered; a ¼ 9.5074

cubic; CaF2 structure type ; a ¼ 6.62 (1); Z ¼ 1.6; d(calc.) ¼ 3.74 cubic, face centered; a ¼ 9.20

1 hexagonal, C3h , P 6, No. 174; a ¼ 6.167, c ¼ 3.770; d(calc.) ¼ 5.92; tricapped trigonal prism sharing ends to form chain cubic, space centered, Z ¼ 4; a ¼ 7.541(6); d(calc.) ¼ 5.87

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm3)c

Table 5.25 (Contd.)

X‐ray powder diffraction data; fused salt systems (D’Eye and Martin, 1957; Bacher and Jacob, 1980) (Bacher and Jacob, 1980) X‐ray powder diffraction data; fused salt systems (Volkov et al., 1979) X‐ray powder diffraction data; fused salt systems (Thoma and Penneman, 1965; Thoma et al., 1966) X‐ray powder diffraction data; fused salt systems (Volkov et al., 1979) X‐ray powder diffraction data; fused salt systems (Boraopkova et al., 1971) X‐ray powder diffraction data; fused salt systems (Thoma and Penneman, 1965; Thoma et al., 1966; Chirkst, 1981) X‐ray powder diffraction data; fused salt systems (Thoma and Penneman, 1965; Thoma et al., 1966; Chirkst, 1981)

X‐ray powder diffraction data; fused salt systems (Brunton et al., 1965; Bacher and Jacob, 1980)

Remarks regarding information available and references

reddish‐brown, slowly oxidizes in air at room temperature; meff. ¼ 3.80 B.M. (100–300 K)d; y ¼ –85 K

slowly oxidizes in air at room temperature. meff. ¼ 3.90 B.M. (100–300 K)d; y ¼ –101 K

dark red needles or fine crystalline olive‐green powder; hygroscopic; soluble in acetic acid.m.p. ¼ 835 C; b.p. ¼ 1657 oC; density: 5.51 g cm3; Oxidizes in air at room temperatures; UCl3(cr): Df Gom ¼ 796.1 (2.0){, o ¼ 158.1 Df Hmo ¼ 863.7 (2.0){, Sm o (0.5){; Cp;m ¼ 95.10 (0.5){. UCl3(g): Df Gom ¼ 521.7 (20.2){, Df Hmo ¼ o ¼ 380.3 (10.0){; 523.0(20 ){, Sm { o Cp;m ¼ 82.4 (5.0) . log p(mmHg) ¼ 11149 T 1þ8.90 (590–790 K) log p(mmHg) ¼ 11552T 1þ8.97 (>790 K); Atomic and crystal‐field parameters: meff. ¼ 3.76 B.M. (70–300 K)d; y ¼ 75 K; TN ¼ 20 K; meff. ¼ 3.03 B.M. (350–509 K)d; y ¼ 29 K; Eavg ¼ 19 331(42), F2 ¼ 37719(154), F 4 ¼ 30370 (202), F 6 ¼ 19477(218), z5f ¼ 1606(13); a ¼ 31(5), b ¼ 939(40), g ¼ 2087 (115); T 2 ¼ 460(81); T 3 ¼ 59(25), T 4 ¼ 159(39), T 6 ¼ 144(46), T 7 ¼ 356(42), T 8 ¼ [300]; M0 ¼ [0.663]; P2 ¼ 1639(65); B 20 ¼ 370(42), B 40 ¼ 359(76), B 60 ¼ 1704(74); B 66 ¼ 935 (60); n ¼ 58; rms ¼ 35.8

UZrF7

UZr2F11

UCl3

2 , P63/m, No. 176; the hexagonal; C6h coordination polyhedron is a symmetrically tricapped trigonal prism arranged in columns in the c‐direction; a ¼ 7.452(6), c ¼ 4 .328 (4); d(U–Cl) ¼ 2.928(3), (6); d(U– Cl) ¼ 2.934(5), (3); d(U–Cl) ¼ 4.816 (4) (to neighbor chain); d(Cl–Cl) ¼ 3.342(5); d(Cl–Cl) ¼ 3.410(3); (face atom‐cape atom); d(calc.) ¼ 5.51

monoclinic, isotypic with SmZrF7, a ¼ 6.1000(6), b ¼ 5.833(8) c ¼ 8.436 (10); b ¼ 102.69(7); Z ¼ 2; V ¼ 292.81; d(calc) ¼ 5.25; d(exp.) ¼ 5.40. monoclinic; a ¼ 5.308(6), b ¼ 6.319 (8), c ¼ 8.250(8), b ¼ 105.41(5) , Z ¼ 2; V ¼ 266.81; d(calc.) ¼ 5.22 X‐ray powder diffraction data; magnetic susceptibility data (Fonteneau and Lucas, 1974). general properties (Bacher and Jacob, 1980) X‐ray single crystal data (Schleid et al., 1987; Murasik et al., 1985; Taylor and Wilson, 1974f); synthesis (Brown, 1968, 1979; Droz˙dz˙yn´ski, 1991, 1988a); thermodynamic properties (Rand and Kubaschewski, 1963; Brown, 1973, 1979; Grenthe et al., 1992; Guillaumont et al., 2003). magnetic susceptibility data, (Handler and Hutchison, 1956; Jones et al., 1974; Dawson, 1951); NIR, visible and UV low temperature absorption spectra and crystal‐field analysis of UCl3 and U3þ:LaCl3, (Carnall, 1989; Karbowiak et al., 2002; Sobczyk et al., 2003); photoelectron spectra (Thibaut et al., 1982)

X‐ray powder diffraction data; magnetic susceptibility data (Fonteneau and Lucas, 1974)

UCl3·7H2O

Formula

grayish‐ink‐blue needles, readily soluble in numerous organic solvents; relatively resistant to oxidation by air at temperatures lower than 15 C; loses some of its crystallization water at higher temperatures or at high vacuum; may be completely dehydrated at 260 C. meff. ¼ 2.95 B.M. (10–300 K)d; y ¼ 32.7 K; Atomic and crystal‐ field parameters: Eavg ¼ 19827(17), F2 ¼ 40488(58), F 4 ¼ 32544(81), F 6 ¼ 22866(75), z5f ¼ 1622(10); a ¼ 28(5), b ¼ 622(35), g ¼ 1148; T 2 ¼ 306, T 3 ¼ 42, T 4 ¼ 188, T 6 ¼ –242, T 7 ¼ 447, T 8 ¼ 300; M0 ¼ 0.672, M2 ¼ 0.372, M4 ¼ 0.258; P2 ¼ 1216, P 4 ¼ 608, P6 ¼ 122; B 20 ¼ 126(76), B 21 ¼ [–109], ImB 21 ¼ 423(47), B 22 ¼ 209 (53), ImB 22 ¼ 350(55), B 40 ¼ 188 (106), B 41 ¼ [–99], ImB 41 [–81], B 42 ¼ [–66], ImB 42 ¼ [–238], B 43 ¼ [136], ImB 43 ¼ 529(83), B 44 ¼ [374], ImB 44 ¼ [–491], B 60 ¼ [–130], B 61 ¼ 428(90), ImB 61 ¼ [–77], B 62 ¼ [171], ImB 62 ¼ 133 [100], B 63 ¼ [–251], ImB 63 ¼ [–14], B 64 ¼ 489(110), ImB 64 ¼ 1832(81), B 65 ¼ [160], ImB 65 ¼ 1197(96), B 66 ¼ 498(98), ImB 66 ¼ 241(91); rms ¼ 36; n ¼ 94

Selected properties and physical datab triclinic; P 1, Ci1 , No.2; a ¼ 7.902(1); b ¼ 8.210(2), c ¼ 9.188(2); a ¼ 70.53 (3); b ¼ 73.14(3); g ¼ 81.66(3); V ¼ 537.0(2); Z ¼ 2; d(calc.) ¼ 2.910. The crystals are built up from separate [U2Cl2(H2O)14]4þ units and Cl ions. The characteristic features of this structure are dimers, formed by two uranium ions connected through the (Cl1) bridging chlorine atoms. d(U–Cl) ¼ 2.915(1) and 2.894(1); d(U–O) ¼ from 2.515(3) to 2.573(3)

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm3)c

Table 5.25 (Contd.)

X‐ray single crystal data (Mech et al., 2005); magnetic susceptibility data; NIR and visible absorption spectrum, decomposition (Droz˙dz˙yn´ski, 1985); crystal‐field analysis, low temperature absorption spectrum (Karbowiak et al., 2001)

Remarks regarding information available and references

deep‐red; soluble in polar organic solvents; IR (cm1): 2260m, 2270sh (n2, symm. C N stretching); 1367 (n3, symm. CH3 deform.); 926m (n4, symm. C–C stretching); 2298 (n3 þ n4, combination band); 1035 (n7, degenerate CH3 rocking); meff. ¼ 3.39 B.M .(65–300 K)d, C ¼ 1.430 emu·K·mol1, y ¼ 65.7 K, TN ¼ 12 K deep dark reddish needles

UCl3·CH3CN· 5H2O

UCl3·2H2O· 2CH3CN

purple plates

UCl3·6H2O

P 1, Ci1 , No.2; a ¼ 7.153(1), b ¼ 8.639 (2), c ¼ 10.541(2); a ¼ 108.85(3), b ¼ 105.05(3), g ¼ 93.57(3); V ¼ 587.6(3); Z ¼ 2; d(calc.) ¼ 2.61; d(U–Cl) ¼ 2.775; d(U–Cl) to the bridging anions ¼ 2.860–2.901; d(U–O) ¼ 2.468–2.485; d(U–U) ¼ 4.605.

monoclinic; P12/nl; a ¼ 9.732(2), b ¼ 6.593(1), c ¼ 8.066(2), a ¼ 90, b ¼ 93.56(3); g ¼ 90; V ¼ 516.51; Z ¼ 2; d(calc.) ¼ 2.909; The basic units of the crystal structure are Cl anions and [UCl2(H2O)6]þ cations. The U as well as O(1), O(2) and O(3) atoms are each eight‐coordinated, whereas the Cl(2) and Cl(1) chloride atoms are seven and six coordinated, respectively. The characteristic feature of this structure is the existence of hydrogen bonds, which link the uranium eight–coordinated polyhedra, forming a three– dimensional network monoclinic; a ¼ 12.96(2), b ¼ 12.98 (3), c ¼ 6.62(1); b ¼ 101.7(2); Z ¼ 4, V ¼ 1007.2; d(calc.) ¼ 3.14

X‐ray single crystal data (Mech et al., 2005)

X‐ray powder diffraction data; magnetic susceptibility data; IR, NIR and visible absorption spectra; decomposition, (Zych and Droz˙dz˙yn´ski, 1986)

X‐ray single crystal data (Mech et al., 2005)

deep ink‐blue; soluble in polar organic solvents; meff. ¼ 3.16 B.M. (60–300 K)d; y ¼ 36 K; C ¼ 1.2146 emu K mol1

purple; soluble in polar organic solvents, m.p. ¼ 608 C – congruently; meff. ¼ 3.77 B.M. (130– 300K)d); y ¼ 33.5 K; TN ¼ 13.2 K; IR(cm1): n( U–Cl, stretching) ¼ 140–220

K2UCl5

Selected properties and physical datab

CsUCl4

Formula

orthorhombic; D16 2h , Pnm, No. 62; Z ¼ 4; Monocapped trigonal prisms [UCl7] are connected via two opposite common edges to chains; a ¼ 12.7224(7), b ¼ 8.8064(6), c ¼ 7.9951(5); V ¼ 1348.8(1); d(calc.) ¼ 3.68

The U3þ ion is eight coordinated by five chloride ions, two water molecules and one methyl cyanide, which are forming a distorted bicapped trigonal prism The characteristic feature of this structure is the link of the uranium atoms through the two common edges of the Cl1 and Cl3 chlorine atoms into an infinitive zigzag chain in the [010] direction could not be unambiguously indexed

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm3)c

Table 5.25 (Contd.)

X‐ray powder diffraction data; magnetic susceptibility data; NIR, Vis, and UV absorption spectra (Karbowiak and Droz˙dz˙yn´ski, 1998a) single crystal and X‐ray powder diffraction data; IR, NIR, and Vis absorption spectra; magnetic susceptibilities (Droz˙dz˙yn´ski and Miernik, 1978; Kra¨mer et al., 1994); luminescence and low temperature spectra of U3þ:K2LaCl5 (Andres et al., 1996); magnetic phase transitions (Keller et al., 1995); crystal‐field analysis (Karbowiak et al., 2000); fused salt systems (Suglobova and Chirkst, 1981)

Remarks regarding information available and references

[(CH3)3N]3· UCl6

SrUCl5

(NH4)2UCl5

Cs2UCl5

Rb2UCl5

dark violet‐blue; IR (cm1): 110m [d(UCl6) Au]; 123m,b [d(UCl6) Eu] 203s [lattice or cation vib.]; 236s [ns(UCl6) Au]; 259s [nas(UCl6) Eu]. Raman (cm1): 79sh [lattice]; 89w [d(UCl6) Eg]; 104w [d(UCl6) Bg]; 131m [lattice or cation vib.]; 226vs [nas(UCl6) Ag]; 237sh [n0 (UCl6) Ag]; 268w [ns(UCl6) Bg]; meff. ¼ 3.36 B.M. (200–300K)d; y ¼ 17; TN ¼ 4.8 K; C ¼ 1.5058 emu·K·mole1

violet; meff. ¼ 3.54 B.M. (17–220 K)d; y ¼ 26.0 K; meff. ¼ 3.47 B.M. (220– 300 K)c; y ¼ 37.5 K; TN ¼ 7.8 K; IR(cm1): n(U–Cl, stretching) ¼ 140–260 deep olive‐green; meff. ¼ 3.65 B.M. (90–300 K)d C ¼ 1.653 emu·K·mole1, y ¼ 127 K

m.p. ¼ 370 C – decomposition in solid state

violet‐red; soluble in polar organic solvents; m.p. ¼ 575 C incongruently; meff. ¼ 3.44 B.M. (150– 300 K)d; y ¼ 32.0 K; TN ¼ 8.6 K; IR (cm1): n(U–Cl, stretching) ¼ 100–260

tetragonal; a ¼ 13.020, c ¼ 7.825; Z ¼ 2; V ¼ 1326.48; d(calc.) ¼ 1.68

could not be indexed

orthorhombic; D16 2h , Pnma, No. 62; Z ¼ 4; Monocapped trigonal prisms [UCl7] are connected via two opposite common edges to chains; a ¼ 13.1175(8), b ¼ 8.9782(6), c ¼ 8.1871(7); V ¼ 1451.19(2); d(calc.) ¼ 4.04; d(U–Cl) ¼ 2.774 to 2.846; d(U– U) ¼ 4.651 (interchain); d(U–U) ¼ 7.88 (intrachain) rhombic; a ¼ 12.03, b ¼ 9.76, c ¼ 9.37; Z ¼ 4, d(calc.) ¼ 4.08

X‐ray powder diffraction data; magnetic susceptibility data; NIR and Vis absorption spectra, (Karbowiak and Droz˙dz˙yn´ski, 1998b) X‐ray powder diffraction data; IR, Raman, NIR and Vis absorption spectra; magnetic susceptibility data (Karbowiak et al., 1996a)

X‐ray powder diffraction data; fused salt systems (Suglobova and Chirkst, 1981) IR, NIR,and Vis absorption spectra; magnetic susceptibilities (Droz˙dz˙yn´ski and Miernik, 1978)

X‐ray powder diffraction data; IR, NIR and visible absorption spectrum; magnetic susceptibilities (Droz˙dz˙yn´ski and Miernik, (1978); Kra¨mer et al., 1994); fused salt systems (Suglobova and Chirkst, 1981)

pale‐brown; soluble in polar organic solvents; IR (cm1):281s, 271s, 210s, 202vs, 195sh, 190vs, 181vs, 169vs, 150sh [n(U–Cl)]; 130m, 125m, 114m, 90m [d(Cl–U–Cl)]; 83sh, 70m, 55w [T’(Rb/U)]; RS (in cm1): 262w, 227 s,b, 189s,165s [n(U–Cl)]; 142m, 120m, 95w [d(Cl–U–Cl)]; 85m, 62m T’(Rb/ U); meff. ¼ 3.76 B.M., C ¼ 1.750 emu·K·mole1, y ¼ 80 K

deep black‐brown; soluble in polar organic solvents; meff. ¼ 3.25 B.M., (105–300 K)d, C ¼ 1.310 emu·K·mole1, y ¼ 95 K

deep ink‐blue; meff. ¼ 3.56 B.M. (85–300)d; C ¼ 1.571 emu·K·mole1, y ¼ 103 K

Ba2UCl7

Cs2LiUCl6

Selected properties and physical datab

RbU2Cl7

Formula

regular; O5h , Fm3m, No. 225; a ¼ 10.671; Z ¼ 4; V ¼ 1218.03; d(calc.) ¼ 3.9444

5 , P21/c, No. 14; a ¼ monoclinic; C2h 7.20, b ¼ 15.61, c ¼ 10.66; b ¼ 91.1 , V ¼ 1197; d(calc.) ¼ 4.22

rhombic; a ¼ 12.86(5), b ¼ 6.89(1), c ¼ 12.55(2); Z ¼ 4, d(calc ) ¼ 4.80(3), RbDy2Cl7 structure type

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm3)c

Table 5.25 (Contd.)

X‐ray powder diffraction data (Suglobova and Chirkst, 1981); Volkov et al., 1987); NIR and Vis low temperature absorption spectrum; magnetic susceptibility data; IR transmission and Raman spectra (Karbowiak et al., 1996b); luminescence and excitation spectra (Karbowiak et al., 1996d); low temperature absorption spectrum and crystal‐field analysis of U3þ:RbY2Cl7 (Karbowiak et al., 1997) X‐ray powder diffraction data (Volkov et al., 1987); Suglobova and Chirkst, 1981); magnetic susceptibility data; IR, NIR and Vis absorption spectra (Karbowiak and Droz˙dz˙yn´ski, (1998b) X‐ray powder diffraction data, NIR, Vis and UV absorption spectra, magnetic susceptibilities (Karbowiak and Droz˙dz˙yn´ski, 1998a); absorption, vibronic and emission spectra; crystal‐ field analysis (Karbowiak et al., 1996e; Karbowiak et al., 1998b)

Remarks regarding information available and references

KUCl4·4H2O

NaU2Cl6 or (Naþ)(U3þ)2 (e)(Cl)6

Cs2NaUCl6

Rb2NaUCI6

K2NaUCI6

violet‐red; soluble in polar organic solvents; IR (cm1): 650, 610 (U– OH2 rocking); 470s (U–OH2 wagging); 300w n(U–OH2 stretching); 222sh, 214s, 198s n(U–Cl, stretching); 166s n(U–Cl–U, stretching or lattice); 130s d(Cl–U– Cl, stretching or lattice); 107s, 88sh (lattice modes); meff. ¼ 3.72 B.M. (100–300 K)d; C ¼ 1.716 emu·K·mole1; y ¼ 69.3 K

ink‐blue; soluble in polar organic solvents; meff. ¼ 2.49 B.M. (4–20)d; y ¼ 0.53 K. meff. ¼ 2.92 B.M. (25–50)d; y ¼ 9.6 K

2 hexagonal; C6h , P63/m., No 176; a ¼ 7.5609(3), c ¼ 4.3143(3); Z ¼ 1; d(U–Cl) ¼ 2.945(6) and 2.977(3 ), d(Na–Cl) ¼ 2.878(6)]. orthorhombic; a ¼ 6.971, b ¼ 6.638, c ¼ 11.317; Z ¼ 2; V ¼ 523.6; d(calc.) ¼ 3.11

1 hexagonal; C3v , P3m1, No.156; isostructural with a‐K2LiAlF6; a ¼ 7.28(1), c ¼ 17.79(2); Z ¼ 3; V ¼ 816.53; d(calc.) ¼ 3.35(1) trigonal; a ¼ 7.27(2), c ¼ 35.51(10); Z ¼ 6; d(calc.) ¼ 3.93(3), d(exp.) ¼ 3.98(2); Rb2LiAlF6 and Cs2NaCrF6 structure type cubic; O5h , Fm3m, No.225; a ¼ 10.937 (1); V ¼ 1308.3(5); Z ¼ 4, d(U–Cl) ¼ 2.723(9), d(U–U) ¼ 7.734; d(calc.) ¼ 3.754

X‐ray powder diffraction data; magnetic susceptibility data; IR, NIR and Vis spectra (Droz˙dz˙yn´ski, 1988b)

X‐ray powder diffraction data (Volkov et al., 1987; Aurov et al., 1983); thermodynamic data (Aurov and Chirkst, 1983) X‐ray powder diffraction data (Volkov et al., 1987; Aurov et al., 1983); thermodynamic data (Aurov and Chirkst, 1983) single crystal data (Spirlet et al., 1988); magnetic properties (Hendricks et al., 1974); thermodynamic properties (Aurov and Chirkst, 1983; Schoebrechts et al., 1989); NIR, Vis and UV low temperature absorption and luminescence spectra; crystal‐field analysis (Karbowiak et al., 1998b); IR spectra (Mazurak et al., 1988). single crystal data (Schleid and Meyer, 1989)

NH4UCl4· 4H2O

RbUCl4· 4H2O

Formula

violet‐red; soluble in polar organic solvents; IR (cm1): 660 (U–OH2, rocking); 486s (U–OH2, wagging); 300sh, 290ms [n(U–OH2), stretching]; 228s, 216sh, 197s [n(U–Cl) stretching]; 165ms [n(U–Cl–U), stretching or lattice]; 130s [d(Cl–U– Cl), bending]; 99 ms (lattice modes); meff. ¼ 3.74 B.M. (100–300 K)d; C ¼ 1.734 emu·K·mole1, y ¼ 66.2 K dark red‐violet; soluble in polar organic solvents; IR (cm1): 650, 610 (U–OH2, rocking); 494s (U–OH2, wagging); 299ms [n(U–OH2) stretching]; 222s, 202s n(U–Cl, stretching); 175ms [n(U–Cl–U), stretching or lattice]; 130s [d(Cl–U– Cl), bending]; 114ms, 84sh (lattice modes); meff. ¼ 3.53 B.M. (100–240 K)d; C ¼ 1.560 emu·K·mole1, y ¼ 72.5 K. Atomic and crystal‐field parameters: F2 ¼ 39911(85), F 4 ¼ 33087(149), F 6 ¼ 22048(160), z5f ¼ 1627.3(8.8); a ¼ 33.0(3.7), b ¼ 973.1( 29.3), g ¼ 1316.9(85.4); T 2 ¼ 306, T 3 ¼ 42, T 4 ¼ 188, T 6 ¼ –242, T 7 ¼ 447, T 8 ¼ 300;

Selected properties and physical datab

X‐ray powder diffraction data; magnetic susceptibility data; IR, NIR and Vis absorption spectra (Droz˙dz˙yn´ski, 1988b)

single crystal diffraction data; magnetic susceptibility data; IR, NIR and Vis low temperature absorption spectra (Droz˙dz˙yn´ski, 1988b); low temperature absorption spectra and crystal‐field analysis (Karbowiak et al., 2000)

orthorhombic; D32 , P21212, No. 18; a ¼ 7.002(2), b ¼ 11.354(3), c ¼ 6.603 (2); Z ¼ 2; V ¼ 524.94(14). The U3þ cation is coordinated by four Cl, ions and four H2O molecules. The crystal is build up from eight‐ coordinated U3þ polyhedrons, which are connected together by O‐H··Cl hydrogen bonds. d(U–Cl) (2) ¼ 2.845(4); d(U–Cl) ) (2) ¼ 2.847(4); d(U–O) (2) ¼ 2.510(11); d(U–O) (2) ¼ 2.568(10); d(calc.) ¼ 2.973, d(exp.) ¼ 2.97

Remarks regarding information available and references

orthorhombic; a ¼ 6.999, b ¼ 6.673, c ¼ 11.375; Z ¼ 2; V ¼ 531.3; d(calc.) ¼ 3.36

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm3)c

Table 5.25 (Contd.)

RbUCl4· 3H2O

KUCl4·3H2O

M0 ¼ 0.672, M2 ¼ 0.372, M4 ¼ 0.258; P2 ¼ 1216, P 4 ¼ 608, P6 ¼ 122; B 20 ¼ 721(47) / [698], B 22 ¼ 428 (39) / [403], ImB 22 ¼ 460 (39) / [–515], B 40 ¼ [–814], B 42 ¼ [–858], ImB 42 ¼ [118], B 44 ¼ [–670], ImB 44 ¼ [–22], B 60 ¼ [–403], B 62 ¼ [–612], ImB 62 ¼ [838], B 64 ¼ [–549], ImB 64 ¼ [–197], B 66 ¼ [–1063], ImB 66 ¼ [–96], rms ¼ 30, n ¼ 83 green; hygroscopic and air sensitive; IR(cm1): n(U–OH2, rocking) ¼ 635s, 575s; n(U–OH2, wagging) ¼ 480; n(U–OH), stretching ¼ 425, 280sh; n(U–Cl), stretching ¼ 260s, 238, 202; n(U–Cl–U), stretching or lattice ¼ 169, 125; d(Cl–U–Cl), bending ¼ 144, 125; n(stretching and bending modes of coordinated water) ¼ 1600; (3170, 3215, 3360, 3420); meff. ¼ 3.70 B.M. (150–300 K)d; C ¼ 1.7033 emu·K·mole1, y ¼ 80 K greenish‐brown to brown; hygroscopic and air sensitive; IR (cm1): n(U–OH2, rocking) ¼ 650, 615, 600; n(U–OH2, wagging) ¼ 485; n(U–OH), stretching ¼ 380, 285sh; n(U–Cl), stretching ¼ 255s, 220, 190; n(U–Cl–U), stretching or lattice ¼ 151, 157; d(Cl–U–Cl), bending ¼ 132, 127, 121, 118; n(stretching and bending modes of coordinated water) ¼ 1565, 1580, 1605, 3470; (93180, 3210, 3350, 3420, 3470); meff. ¼ 3.57 B.M. (100–300 K)d, C ¼ 1.5766 emu·K·mole1, y ¼ 64 K X‐ray powder diffraction data; IR, NIR and Vis absorption spectra; magnetic susceptibility data (Karbowiak and Droz˙dz˙yn´ski, 1993)

X‐ray powder diffraction data; IR, NIR and Vis absorption spectra; magnetic susceptibility data (Karbowiak and Droz˙dz˙yn´ski, 1993)

monoclinic; a ¼ 6.9373, b ¼ 7.2658, c ¼ 9.5209; b ¼ 96.71; Z ¼ 2; V ¼ 476.62; d(calc.) ¼ 3.30

monoclinic; a ¼ 8.8986, b ¼ 6.9738; c ¼ 8,0517; b ¼ 100; Z ¼ 2; V ¼ 490.75; d(calc.) ¼ 3.51

NH4UCl4· 3H2O

CsUCl4· 3H2O

Formula

brown‐green; soluble in polar organic solvents; CsUCl4·3H2O; meff. ¼ 3.39 B.M., C ¼ 1.430 emu·K·mole1, y ¼ 67.7 K. Free ion and crystal‐field parameters: F2 ¼ 39876(58), F 4 ¼ 33279(77), F 6 ¼ 23598(68), z5f ¼ 1648.3(10.3); a ¼ 26.2(4.3), b ¼ 889(38), g ¼ 1131 (94); T 2 ¼ 306, T 3 ¼ 42, T 4 ¼ 188, T 6 ¼ –242, T 7 ¼ 447, T 8 ¼ 300; M0 ¼ 0.672, M2 ¼ 0.372, M4 ¼ 0.258; P2 ¼ 1216, P 4 ¼ 608, P6 ¼ 122; B 20 ¼ 411(46) / [–390], B 22 ¼ 614(45) / [573], ImB 22 ¼ 610(46) / [614], B 40 ¼ [–699], B 42 ¼ [–398], ImB 42 ¼ [–525], B 44 ¼ [–1039], ImB 44 ¼ [–49], B 60 ¼ [–1046], B 62 ¼ [–58], ImB 62 ¼ [794], B 64 ¼ [–119], ImB 64 ¼ [–173], B 66 ¼ [–27], ImB 66 ¼ [–691], rms ¼ 34; n ¼ 77 greenish‐brown to brown; hygroscopic and air sensitive; IR (cm1): n(U–OH2, rocking) ¼ 615sh, 590s; n(U–OH2, wagging) ¼ 470s; n(U–OH), stretching ¼ 385, 290sh; n(U–Cl), stretching ¼ 266s, 232; n(U– Cl–U), stretching or lattice ¼ 172; d(Cl–U–Cl), bending ¼ 147, 128; n(stretching and bending modes

Selected properties and physical datab

single crystal diffraction data (Kra¨mer et al., 1991); synthesis, magnetic susceptibility data; IR, NIR and Vis low temperature absorption spectra; crystal‐field analysis (Karbowiak et al., 1993, 2000)

X‐ray powder diffraction data; IR, NIR and Vis absorption spectra; magnetic susceptibility data (Karbowiak and Droz˙dz˙yn´ski, 1993)

monoclinic; a ¼ 13.7693, b ¼ 8.8990, c ¼ 7.8643; b ¼ 95.65; Z ¼ 4; V ¼ 956.95; d(calc.) ¼ 3.12

Remarks regarding information available and references

2 , P21/m., No. 11; a ¼ monoclinic; C2h 7.116(1), b ¼ 8.672(2), c ¼ 8.071(2); b ¼ 99.28(3); Z ¼ 4; V ¼ 956.96; d(U–Cl) ¼ 2.957(3), d(U–O) ¼ 2.552 (3) (mean values); tricapped trigonal prism consisting of six Cl and three O atoms (representing the water molecules)

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm3)c

Table 5.25 (Contd.)

UBr3

Cs2U[Cl9 O3(TaCl)6]

U(NH)Cl

UOCl

reddish‐brown; air sensitive; soluble in acetic acid, dimethylacetamid; density: 6.53 g cm3; m.p. ¼ 835 C, b.p. ¼ 1537 C UBr3(cr): Df Gom ¼ 673.2 (4.2){, o ¼ 192.98 Df Hmo ¼ 698.7 (4.2){, Sm o ¼ 105.83 (0.50){. (0.50){; Cp;m UBr3(g): Df Gom ¼ 408.1 (20.5){, o ¼ 403.0 Df Hmo ¼ 371 (20){, Sm { o (15.0) ; Cp;m ¼ 85.2 (5.0){. logp(mmHg) ¼ 16420T 1 þ 22.95 – 3.02 logT (298–1000 K). logp(mmHg) ¼ 15000T 1 þ 27.54 – 5.03 logT (1000–1810 K)

of coordinated water) ¼ 1585, 1600; n4(NH4) ¼ 1404 vs; n2(NH4) ¼ 1670, n4 þ n6(NH4) ¼ 1770, 2n4 – n5(NH4) ¼ 2710, n1(NH4) ¼ 3040, n3(NH4) ¼ 3110vs. meff. ¼ 3.71 B.M. (75–300 K)d; C ¼ 1.7073 emu·K·mole1, y ¼ 54 K red; UOCl (cr): Df Gom ¼ 785.7 o ¼ (4.9){, Df Hmo ¼ 833.9(4.2){, Sm o 102.5 (8.4){; Cp;m ¼ 71.0 (5.0){. meff. ¼ 3.40 B.M. (240–300 K)d; y ¼ 145 K

tetragonal; D74h , P4/nmm, No.129; a ¼ 3.972(5), b ¼ 3.972(5), c ¼ 6.81 (1); Z ¼ 2; V ¼ 107.44; d(calc.) ¼ 8.91 trigonal/rhombohedral; D23d , P 31c, No.163; a ¼ 9.1824(5), c ¼ 17.146(2); Z ¼ 2; V ¼ 1252.01; d(calc.) ¼ 5.75 hexagonal, (UCl3 type of structure), 2 , P63m, No.176; a ¼ 7.942(2), c ¼ C6h 4.441(2), (a ¼ 7.9519, c ¼ 4.448; Z ¼ 2, CN ¼ 9; d(calc.) ¼ 6.54; d(U–Br) ¼ 3.145 (3.150) to the three capping Br atoms, d(U–Br) ¼ 3.062(3.069) to the six Br atoms at the prism vertices, d(Br–Br) ¼ 3.652(3.663) at the trigonal prism face edge and d(U–U) ˚ (4.448) along the c‐ ¼ 4.441A direction. The face Br–U–Br angle is 73.21(73.3). Values in parentheses were taken from Kra¨mer and Meyer (1989)

tetragonal; D74h , P4/nmm, No. 129; (PbFCl type of unit cell); a ¼ 4.043, c ¼ 6.882; Z ¼ 2; CN ¼ 9; d(U–Cl) ¼ 2.373(2), d(U–Cl) ¼ 3.074(1 ), d(U–Cl) ¼ 3.150(4)

structural and theoretical studies of bondings in the cluster (Ogliaro et al., 1998) X‐ray single crystal data (Levy et al., 1975; Kra¨mer and Meyer, 1989); magnetic susceptibility data: (Jones et al., 1974); thermodynamic properties (Rand and Kubaschewski, 1963; Grenthe et al., 1992; Guillaumont et al., 2003); NIR, Vis and UV absorption spectra; fused salt systems (Sobczyk et al., 2003; Karbowiak et al., 2003a; Brown, 1979); photoelectron spectra (Thibaut et al., 1982)

single crystal diffraction data (Schleid and Meyer; 1988; Brown and Edwards, 1972); IR and magnetic susceptibility data (Levet and Noe¨l, 1981); photo‐electron spectra (Thibaut et al., 1982); themodynamic data (Grenthe et al., 1992; Guillaumont et al., 2003) crystallographic data (Berthold, and Knecht, 1966)

dark violet; Polar organic solvents; m.p. ¼ 625 C – congruently; n(U–Br) stretching vibrations (cm1): 110m, 124m, and 145s,br

violet; polar organic solvents; m.p. ¼ 600 C – congruently; n(U–Br) stretching vibrations (cm1): 111m, 124m, and 144s,br

Rb2UBr5

meff. ¼ 3.57 B.M. (25–76K)d; y ¼ 54 K, TN ¼ 15 K; meff. ¼ 3.29 B.M. (350–483K)d; y ¼ 25K, TN ¼ 15 K; Atomic and crystal‐field parameters: Eavg ¼ 19213(74), F 2 ¼ 37796(265), F 4 ¼ 30940(313), F 6 ¼ 20985(315), z5f ¼ 1604(19); a ¼ 27(8), b ¼ 823 (54), g ¼ 1647(168); T 2 ¼ 374(125), T 3 ¼ 29(34), T 4 ¼ 262(58), T 6 ¼ 258(77), T 7 ¼ 264(60), T 8 ¼ [300]; M0 ¼ [0.6630]; P2 ¼ 1707(89); B 20 ¼ 410(50), B 40 ¼ 452(86), B 60 ¼ 1637 (77), B 66 ¼ 722(63); n ¼ 47; rms ¼ 36.5 red

Selected properties and physical datab

K2UBr5

UBr3·6H2O

Formula

orthorhombic; D16 2h , Pnma, No. 62; a ¼ 13.670(1), b ¼ 9.3900(8), c ¼ 8.6046(4); Z ¼ 4; V ¼ 1663.1(2). CN ¼ 6

monoclinic; P2/n; a ¼ 10.061, b ¼ 6.833, c ¼ 8.288; b ¼ 92.99; V ¼ 285.00 orthorhombic; D16 2h , Pnma, No. 62; a ¼ 13.328(1), b ¼ 9.2140(7), c ¼ 8.4337(5), Z ¼ 4, V ¼ 1559.5(2); CN ¼ 6; d(calc.) ¼ 4.53

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm3)c

Table 5.25 (Contd.)

X‐ray powder diffraction and thermal decomposition data (Brown et al., 1968) X‐ray powder diffraction data; magnetic data; NIR, Vis an UV absorption spectra (Kra¨mer et al., 1993, 1994); magnetic phase transitions (Keller et al., 1995); IR and thermodynamic data (Suglobova and Chirkst, 1978a; Fuger et al., 1983); melting point diagrams (Vdovenko et al., 1974a) X‐ray powder diffraction data; magnetic data; NIR, Vis an UV absorption spectra (Kra¨mer et al., 1994); IR and thermodynamic data:

Remarks regarding information available and references

P‐cubic; Th6 , Pa3, No. 205; Z ¼ 4, a ¼ 11.439(2), d(calc.) ¼ 4.44 tetragonal; (PbFCl type of unit cell), D74h , P4/nmm, No.129; a ¼ 4.063(1), c ¼ 7.447(2); CN ¼ 9

–

meff. ¼ 3.67 B.M. (250–300K)d; y ¼ 140 K

brown‐red

blue‐violet

Cs2NaUBr6

UOBr

K2UBr5· 2CH3CN· 6H2O

Rb2UBr5· CH3CN· 6H2O

tetragonal; D34h , P4/nbm, No. 125; a ¼ 10.81(1), c ¼ 11.30(1); Z ¼ 4, d(calc.) ¼ 4.09, d(exp.) ¼ 4.04

cubic; face centered; a ¼ 11.03(2), d(calc.) ¼ 4.79 cubic; face centered; a ¼ 11.51(2); d(calc ) ¼ 4.83

rhombic; isostructural with Cs2DyCl5; a ¼ 15.79(4), b ¼ 9.85(5), c ¼ 7.90(1); Z ¼ 4, CN ¼ 6, d(calc. ) ¼ 4.85(4)

–

dark‐violet; m.p. ¼ 695 C, congruently dark‐violet; m.p. ¼ 758 C, congruently;

violet; m.p. ¼ 420 C, congruently; n (U–Br) stretching vibrations(cm1): 110m, 124m, and 149s,br

K2NaUBr6

Cs3UBr6

Rb3UBr6

Cs2UBr5

(Suglobova and Chirkst, 1978a; Fuger et al., 1983); melting point diagrams (Vdovenko et al., 1974a) X‐ray powder diffraction data (Volkov et al., (1987); IR and thermodynamic data (Suglobova and Chirkst, 1978a,b; Fuger et al., 1983); melting point diagrams (Vdovenko et al., 1974a) X‐ray powder diffraction data (Vodovenko et al., 1974a). X‐ray powder diffraction data; thermodynamic properties (Aurov and Chirkst, 1983) X‐ray powder diffraction and thermodynamic data (Aurov et al., 1983); thermodynamic properties (Aurov and Chirkst, 1983) X‐ray powder diffraction and thermodynamic data (Aurov et al., 1983); thermodynamic properties (Aurov and Chirkst, 1983) X‐ray powder diffraction data; IR and magnetic susceptibility data (Levet and Noe¨l, 1981; photoelectron spectra (Thibaut et al., 1982) magnetic susceptibility data; decomposition; IR, NIR and Vis and UV absorption spectra (Zych and Droz˙dz˙yn´ski, 1991) magnetic susceptibility data; decomposition; IR, NIR and Vis absorption spectra (Zych and Droz˙dz˙yn´ski, 1991)

(NH4)[UBr2· (CH3CN)2· (H2O)5]Br2

Formula

grayish‐green to brown crystalline solid; air sensitive; soluble in organic solvents like methanol, ethanol, formic acid, dimethyl‐formamide, tributhylphosphate etc. IR (cm1): n(H2O) with hydrogen bond character ¼ 3325s,b; (3114s,b; 2952w); n(CH3) ¼ 2921w; (2851w); combination band ¼ 2307w; ns(C N) ¼ 2273w; d(HOH) ¼ 1606m; das(CH3) ¼ 1399s; (1378s); ds(CH3) ¼ 1189w, 1144w; d(U–OH2) ¼ 1078w; r(CH3) ¼ 1044w; n(C–C) ¼ 971w, 938w, 922w; r(U–OH2) ¼ 887w, 770w,721w; o(U–OH2) ¼ 663vs,b, 670vs,b, 400– 590s,vb; n(U–OH2) ¼ 387m, 306m; n(UN2) ¼ 202m; n(UBr2) ¼ 157m,b, 115sh; d(UBr2) ¼ 82w; (62w, 59w,47w, 37w) Raman; ns(C N) ¼ 2280m; d(HOH) ¼ 1631m;das(CH3) ¼ 1415w; (1356m); ds(CH3) ¼ 1261w, 1186w; d(U–OH2) ¼ 1123m; r(CH3) ¼ 1063m; n(C–C) ¼ 952w, 826w;

Selected properties and physical datab orthorhombic; D16 2h , Pnma No. 62; a ¼ 8.98(2), b ¼ 9.99(2), c ¼ 20.24(4); ˚ 3; Z ¼ 4; V ¼ 1816(7) A d(U–Br1) ¼ 3.074(4) (2), d(U–O1) ¼ 2.538(12) (2), d(U–O2) ¼ 2.549(14) (2), d(U–N1) ¼ 2.517(30) (1), d(U–N2) ¼ 2.688(26) (1), d(U–O3) ¼ 2.652(20) (1), d(calc.) ¼ 2.74

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm3)c

Table 5.25 (Contd.)

single crystal diffraction data; magnetic susceptibility data; IR, Raman, NIR, Vis and UV spectra; factor group analysis (Zych et al., 1993; Zych and Droz˙dz˙yn´ski, 1990b)

Remarks regarding information available and references

dark‐brown

dark‐purple

UI3·4CH3CN

UI3(THF)4

UI3

r(U–OH2) ¼ 729w; o(U–OH2) ¼ 651w, 611w, 536w; n(U–OH2) ¼ 536w, 455m,b, 326w; n(UN2) ¼ 282w; n(UBr2) ¼ 195sh, 149 black; extremely moisture sensitive, soluble: methanol, ethanol, ethyl acetate, dimethyl‐acetamide, acetic acid; m.p. ¼ 766 C; UI3(cr): Df Gom ¼ 466.1 (4.9){, Df Hmo ¼ 466.9 (4.2){, o o ¼ 221.8 (8.4){; Cp;m ¼ 112.1 (6.0){; Sm o UI3(g): Df Gm ¼ 198.7 (25.2){, Df Hmo o ¼ 137 (25){, Sm ¼ 431.2 (10.0){; { o Cp;m ¼ 86.0 (5.0) . meff. ¼ 3.65 B.M. (25–200 K)d; y ¼ 34 K, TN ¼ 3.4K; meff. ¼ 3.31 B.M. (350–394 K)d; y¼5K orthorhombic; (TbCl3 and PuBr3 structure type ); D17 2h , Cmcm, No. 63; a ¼ 4.334(6), b ¼ 14.024(18), c ¼ 10.013(13); Z ¼ 4. The coordination polyhedron is a bicapped trigonal prism the third capping Br anion being withdrawn by bonding with another U atom; d(U–I1) ¼ 3.165(12) (2) and d(U–I2) ¼ 3.244(8) (4) (to the prism iodine atoms ), d(U–I2) (2) ¼ 3.456(11) (to the cap iodine ˚ and atoms), d(I2–I2) ¼ 3.679(18) A ˚ . d(calc.) ¼ 6.78 d(U–U) ¼ 4.328(5) A monoclinic; a ¼ 9.6168, b ¼ 8.7423, c ¼ 7.1858; b ¼ 92.99; Z ¼ 2; V ¼ 603.31; d(calc.) ¼ 4.08; d(U–Il) ¼ 3.165(12) (2) and d(U–I2) (4) ¼ 3.244(8) (to prism iodines), d(U–I2) (2) ¼ 3.456(11) (to cap iodine atoms), d(I2–I2) ¼ 3.679(18) and ˚ d(U–U) ¼ 4.328(5) A 5 monoclinic; C2h , P21/c; No. 14; a ¼ 8.750(3), b ¼ 16.706(16), c ¼ 17.697 (16); b ¼ 93.64(3); Z ¼ 4; V ¼ 2582

synthesis and reactivity; single crystal X‐ray diffraction data; thermal gravimetric analysis; vibrational spectrum; 1H NMR spectrum; electronic absorption spectrum (Avens et al., 1994)

X‐ray powder diffraction data; magnetic susceptibility data; IR, NIR, Vis and UV absorption spectra (Droz˙dz˙yn´ski and du Preez, 1994)

X‐ray single crystal and neutron diffraction data (Zachariasen, 1948a; Levy et al., 1975; Murasik et al., 1981); thermodynamic data (Brown, 1979; Guillaumont et al., 2003); e diffuse reflectance spectra (Barnard et al., 1973); magnetic data (Dawson, 1951; Jones et al., 1974; Murasik et al., 1981; 1985)

orthorhombic; D16 2h , Pnma, No.62; a ¼ 14.546(2), b ¼ 9.249(1), c ¼ ˚, 10.026(2); Z ¼ 4; V ¼ 2031.1(5)A CN ¼ 6 tetragonal; (PbFCl type of unit cell), D74h , P4/nmm; No. ¼ 129; a ¼ 4.062 (1), c ¼ 9.208(2); CN ¼ 9

blue‐violet

deep blue; meff. ¼ 3.56 B.M. (220– 300K)d); y ¼ 150 K

black with a greenish tinge; m.p. ¼ 800 C; UBrCl2(cr): Df Gom ¼ 760.3 o ¼ (9.8){, Df Hmo ¼ 812.1(8.4){, Sm 175.7(16.7)

Rb2UI5

UOI

UBrCl2

orthorhombic; D16 2h , Pnma, No. 62; monocapped trigonal prisms [UCl7] are connected via two opposite common edges to chains; CN ¼ 6; a ¼ 14.293(1), b ¼ 9.8430(5), c ¼ 9.1067(5); Z ¼ 4; V ¼ 1929.1(2); d(U–I) ¼ 3.182 to 3.275; d(U–U) ¼ 5.143 (interchain); d(U–U) ¼ 7.778 (intrachain)

deep‐blue

Selected properties and physical datab

K2UI5

Formula

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm3)c

Table 5.25 (Contd.)

X‐ray powder diffraction data, magnetic data, NIR, Vis an UV absorption spectra, magnetic phase transitions (Kra¨mer et al., 1994; Keller et al., 1995); low temperature absorption spectrum of U3:K2Lal5: (Andres et al., 1996); crystal‐field analysis (Karbowiak et al., 1998a); IR and thermodynamic data (Suglobova and Chirkst, 1978) X‐ray powder diffraction data; magnetic data; NIR, Vis and UV absorption spectra (Kra¨mer et al., 1994); IR and thermodynamic data (Suglobova and Chirkst, 1978) X‐ray powder diffraction data;IR and magnetic susceptibility data (Levet and Noel, 1981) thermodynamic data (MacWood, 1958; Brown, 1979; Grenthe et al., 1992; Guillaumont et al., 2003)

Remarks regarding information available and references

black with a greenish tinge; m.p. ¼ 775 C; UBr2Cl(cr) Df Gom ¼ 714.4 o ¼ (9.8){, Df Hmo ¼ 750.6 (8.4){, Sm 192.5 (16.7){ extremely moisture sensitive; (i) black, m.p. 750; (ii) black, m.p. 725; (iii) black, m.p. 700; (iv) black, m.p. 690

thermodynamic data (MacWood, 1958; Brown,1979; Grenthe et al., 1992; Guillaumont et al., 2003)

a

{

Estimated values. Values recommended by the Nuclear Energy Agency (Guillaumont et al., 2003). Values have been selected in part from review articles (Brown, 1979; Bacher and Jacob, 1980; Freestone and Holloway, 1991; Grenthe et al.,1992; Guillaumont et al., 2003). b m.p. ¼ melting point ( C); b.p.. ¼ boiling point ( C); (cr) ¼ crystalline; (g) ¼ gaseous; thermodynamic values in kJ mol1, or J K1 mol1 at 298.15 K, o , standard molar entropy; unless otherwise mentioned; Df Gom , standard molar Gibbs energy of formation; Df Hmo , standard molar enthalpy of formation; Sm o (J K1 mol1), standard molar heat capacity; log p (mmHg) ¼ –AT 1 þ B – C logT: vapor pressure equation for indicated temperature range; IR ¼ Cp;m infrared active; lat. ¼ lattice vibrations; val. ¼ valence vibrations; def. ¼ deformation vibrations; all values in cm1; vs: very strong;ps:ffiffiffiffistrong; m: medium; ms: medium strong; w: weak; sh: shoulder; b: broad; C, Θ, paramagnetic constants from the Curie Weiss law C ¼ w;M (T‐Θ); meff ¼ 2.84 C ‐ effective magnetic moment; TN, ordering temperature; atomic and crystal‐field parameters; F k and z5f ¼ electrostatic and spin–orbit interaction; a, b, g; ¼ two‐body correction terms; T iti (i ¼ 2,3,4,6,7,8) ¼ three‐particle configuration interaction; M j (j ¼ 0, 2 and 4) ¼ spin–spin and spin–other–orbit relativistic corrections; P k (k ¼ 2, 4 in ibrackets indicate parameter errors; parameters in square and 6) ¼ electrostatically correlated spin‐orbit perturbation; B kq , crystal‐field parameters; values h 1=2 brackets were kept constant during the final fitting procedure; standard deviation: rms ¼ P ðDi Þ2 =ðn  pÞ [cm1], where Di is the difference between the observed i and calculated energies, n is the number of levels fitted and p is the number of parameters freely varied. c ˚ and angles are in degrees; d, density [g cm3 ]; CN, coordination number, V ¼ molar volume [cm3 mol1]. All values are in A d Temperature range with linear relationship of w;M1 against T.

*

other mixed halides: (i) UCl2I; (ii) UClI2; (iii) UBr2I; (iv) UBrI2.

UBr2Cl

442

Uranium

spectra of co‐doped (U4þ,U3þ):Ba2YCl7 single crystals has been also reported (Karbowiak et al., 2003c) Efficient luminescence was observed at 7 K from both the 4G7/2 and 4F9/2 levels of the U3þ ions and from the 1D2 and 1I6 levels of U4þ. For the U4þions a very strong anti‐Stokes emission was noticed due to energy transfer processes. Contrary to U4þ for which emission was observed even at room temperature the emission of U3þ ions is strongly quenched by temperature. Owing to the presence of U3þ and U4þ ions in the host crystal, an energy transfer between these ions has been proved. Analyses of the nephelauxetic effect and crystal field splittings of the K2UX5 (X ¼ Cl, Br or I) series of compounds have also been reported (Karbowiak et al., 1998a). The absorption spectra of NH4UCl4 · 4H2O and CsUCl4 · 3H2O recorded at 298 and 4.2 K, presented in Fig. 5.38 (Karbowiak et al., 2000) are typical for most uranium(III) compounds. In the 4000–15800 cm–1 region the spectra consist of relatively intense, sharp, and well‐separated absorption lines. A comparison of the spectra shows significant differences in the visible range connected with the appearance of strong and broad f–d bands, allowed by the Laporte rule. For CsUCl4 · 3H2O the first f–d bands are located at about 23000 cm–1, while in NH4UCl4 · 4H2O they are shifted about 5000 cm–1 toward the infrared region. For the isostructural series of complex halides of the composition U3þ:K2LaX5 (X ¼ Cl, Br, I), the substitution of the Cl– by I– results in a significantly smaller shift of about 1000 cm–1 (Karbowiak et al., 1998a). Droz˙dz˙yn´ski (1985, 1991) and Karbowiak et al. (1996c) report a close relationship between the increase of covalence/decrease of the uranium– halogenide distances, and the red shift of the first intense f–d bands. The crystal‐ field symmetry is another factor, which can influence the position of the f–d bands. However, this seems to be a minor factor, since there is no simple dependence of the energy of the first f–d transition on the site symmetry of the U3þ ion. For example in K2UCl5 (Cs) and Cs2NaUCl6 (Oh) (Karbowiak et al., 1998a,b) the first f–d transitions occur at similar energies of 14300 and 15000 cm–1, respectively, while for UCl3 (D3h) they appear at 23000 cm–1 (Karbowiak et al., 2002a). An extensive analysis of the 5f3!5f26d1 transitions in low temperature absorption spectra of U3þ ions incorporated in various single crystals were reported by Seijo and Barandiran (2001), Karbowiak and Droz˙dz˙yn´ski (2004) and Karbowiak (2005a,b). Temperature‐induced line broadening and line shift measurements have been chosen as method for the determination of the electron–phonon coupling parameters for U3þ doped in K2LaCl5 (Ellens et al., 1998), LaCl3 and LaBr3 single crystals (Karbowiak et al., 2003d). The value of the electron–phonon coupling parameter,  a, was found to be considerably lower in LaCl3 than in K2LaCl5 but larger than that of Nd3þ in LaCl3. The electron–phonon coupling is also stronger for U3þ in the tribromide as compared with the trichloride host; this has been attributed to a larger covalency of the first compound. Intensity calculations of 5f3!5f3 transitions in tervalent uranium, based on the Judd–Ofelt theory were performed both for solution (Droz˙dz˙yn´ski, 1978, 1984) and solid‐state spectra (Droz˙dz˙yn´ski and Conway, 1972, Karbowiak and

Compounds of uranium

443

Fig. 5.38 Absorption spectra of thin films of CsUCl4 · 3H2O (a) and NH4UCl4 · 4H2O recorded at 4.2 and 298 K (from Karbowiak et al., 2000 reproduced by the permission of Elsevier).

Droz˙dz˙yn´ski, 2003). The analyses have shown a rather poor agreement between the observed and calculated oscillator strengths. So far, a relatively small r.m.s. deviation, of the order 10–6 to 10–7, has been obtained only for the absorption spectra of UCl3 in hexamethylphosphortriamide (Droz˙dz˙yn´ski and Kamenskaya, 1978) and of UCl3‐doped ZnCl2‐based glass (Deren´ et al., 1998). For almost all the halides and complex halides, magnetic susceptibility measurements were carried out over wide temperature ranges. The paramagnetic

444

Uranium

constants from the Curie–Weiss law w0 m. ¼ C/(T – y) and the effective magnetic moments meff ¼ 2:84mB were determined for a large number of compounds (see Table 5.25). The trihalides show remarkable cooperative effects, which were studied both experimentally (Murasik et al., 1980, 1985, 1986) and theoretically (Łyz˙wa and Erdo¨s, 1987; Plumer and Caille´, 1989). UCl3 and UBr3 undergo an unusual magnetic phase transition for actinide compounds. A one‐dimensional, short‐range magnetic order along the z‐axis of the hexagonal lattice develops at about 15 K for UBr3 and 22 K for UCl3, which results from strong antiferromagnetic interactions between the nearest neighbors. A three‐dimensional ordering appears in UBr3 and UCl3 when the uranium magnetic moments order to a ‘0þ–’ configuration in each plane perpendicular to the z‐axis at TN ¼ 6.5 and 5.3 K, respectively. At temperatures below Tt ¼ 2.7 K for UBr3 and Tt ¼ 2.5 K for UCl3 the magnetic moments exhibit smaller values and become oriented parallel to the equivalent x‐ or y‐axis. The observed reorientation of the moments is reported to be rare in the actinide ions due to a usually strong anisotropy, which determines the direction of the moment (Santini et al., 1999). An extensive physical analysis of the magnetic interactions and magnetic ordering phenomena, as well as the crystal‐field splitting in the K2UX5 (X ¼ Cl, Br or I) series of compounds, were performed on the basis of the Ising model (Keller et al., 1995). The application of elastic and inelastic neutron scattering experiments along with specific heat measurements made it possible to obtain a consistent picture of the magnetic phases. An analysis of the IR and Raman spectra of this series of compounds and of RbU2Cl7 is also available (Karbowiak et al., 1996a; Hanuza et al., 1999). Droz˙dz˙ynski (1991) has summarized paramagnetic resonance measurements for U3þ ions substituted in CaF2, SrF2, and LaCl3 single crystals. Some physical properties of tervalent uranium halides and related compounds are collected in Table 5.25. (i)

Uranium trifluoride and uranium(III) fluoro complexes

Uranium trifluoride Uranium trifluoride is most conveniently prepared by reduction of UF4 with metallic aluminum or finely powdered uranium. In the former case the reagents are placed in a graphite crucible and heated up to 900 C where the reaction proceeds smoothly and the excess of aluminum and by‐products sublime from the reaction zone (Runnals, 1953). In the latter one, stoichiometric quantities of cleaned uranium turnings and UF4 are placed in a nickel tube and heated to about 250 C in a stream of pure hydrogen (Warf, 1958). The finely divided UH3 was decomposed at 400 C, after which the tube should be shaken in order to obtain an intimate mixture that was then heated to 700–900 C to give the pure trifluoride (Friedman et al., 1970). The reduction with other metals such as Be, Mg, Ti, or Zr, as well as UN or U2N3, at 900–950 C has also been found suitable for the synthesis. The use of the nitrates has some technical advantages since they prevent the formation of corrosive by‐products. Reduction with Li,

Compounds of uranium

445

Na, Cs, Mg, Ca, Sr, and Ba yields metallic uranium. The preparation of ultrapure UF3 by reduction of UF4 with hydrogen at 1020 to 1050 ( 20) C has been reported by Berndt and Erdman (1973). Uranium trifluoride is a gray to black solid. Separate crystals show a deep‐violet color under the microscope. As compared to other uranium(III) compounds the trifluoride is remarkably stable on air at room temperature. At higher temperatures UF3 oxidizes and at 900 C it is quantitatively converted into U3O8. The compound is thermally unstable even in an inert atmosphere and disproportionates to UF4 and U at about 1000 C and to a smaller extent (0.1% per hour) also at 800 C. UF3 is insoluble in water and cold aqueous acids but slowly undergoes oxidation. This proceeds with the formation of uranium(IV) and uranyl compounds at 100 C. UF3 dissolves rapidly in nitric acid–boric acid mixtures. Chlorine, bromine, and iodine react to give UF3X (X ¼ Cl, Br or I). UF3 has the LaF3‐type structure but the symmetry is reported to be either trigonal (space group P 3c1, D43d , No. 185) or hexagonal (space group P63cm, 3 C 6v , No. 165). Two coordination numbers 9 and 11 are also taken into consideration (Taylor, 1976a). Both structures may be considered as distorted ideal polyhedra with a bimolecular hexagonal cell (space group P63/mmc) (Schlyter, 1953). The polyhedra are fully capped trigonal prisms in which fluorine atoms (CN ¼ 11) are located on all corners and outside the two triangular and the three square boundary planes. The main difference between the different structures is a slight displacement of the atoms forming the prism and the atoms outside the triangular surfaces normal to c‐axis (Taylor, 1976a). Other crystallographic data are listed in Table 5.25. A good quality absorption spectrum of UF3 was obtained by means of the teflon disk technique (Schmieder et al., 1970) and in chlorinated naphthalene at 4.2 K (Droz˙dz˙yn´ski and Karbowiak, 2005). For the latter data a crystal‐field analysis has also been performed. There is a large shift of the L0 S0 J0 multiplets towards higher wave numbers, as compared with other UIII low‐temperature spectra. Some absorption spectra were also recorded in fused‐salt systems: LiF–Be2, LiF–BeF2–ZrF4, and LiF–NaF–KF (Martinot, 1984). The magnetic susceptibility of UF3 has been measured between 2 and 300 K (Berger and Sienko, 1967) and between 293 and 723 K (Nguyen‐Nghi et al., 1964). For both temperature ranges a linear relationship of 1/w0 M vs T was reported. The effective magnetic moment of 3.67 BM is close to the free ion value. Uranium trifluoride monohydrate and uranium(III) fluoro complexes UF3 · H2O was prepared from an uranium(III) solution in 1 M HCl or in anhydrous methanol by precipitation with ammonium fluoride (Barnard et al., 1973). The green gelatinous precipitate appears in the latter case to be brown after drying due to some U(IV) impurities. The hydrate is reported to be far more reactive than the anhydrous fluoride and is immediately oxidized in air, giving a pale green uranium(IV) substance. The compound was characterized by magnetic susceptibility measurements, but the results may not be reliable.

446

Uranium

The formation of a number alkali fluorouranates(III) and complexes of UF3 with ZrF4 has been known for a long time (Bacher and Jacob, 1980). KUF4, K2UF5, K3UF6, Rb3UF6, and Cs3UF6 were prepared by heating UF4 and metallic uranium with the appropriate alkali fluoride at 1000 C (Thoma et al., 1966). NaUF4 and Na2UF5 were identified during investigations of the binary fused‐salt system NaF–UF3. Some of the complex fluorides were characterized by X‐ray powder diffraction (Table 5.25) but more detailed information is still not available. UZrF7 was prepared by reduction of a mixture of UF4 and ZrF4, either with metallic zirconium or with metallic uranium at about 800 C; UZr2F11 was identified in a systematic study of the UZrF7–ZrF4 binary system (Fonteneau and Lucas, 1974). The fluorides are not stable and slowly oxidize even at room temperature. The compounds were characterized by magnetic susceptibility measurements in the 100–300 K range and by X‐ray powder diffraction analyses (Table 5.25). (ii)

Uranium trichloride and uranium(III) complex chlorides

Uranium trichloride Uranium trichloride may be prepared by a number of methods (Brown, 1979; Droz˙dz˙yn´ski, 1991). One of the most convenient is the action of gaseous hydrogen chloride on uranium hydride. Attractive alternative methods involve the reduction of uranium tetrachloride with zinc, metallic uranium, or uranium hydride. 350 C

UH3 þ 3HCl ! UCl3 þ 3H2 400 C

3UCl4 þ Al ! 3UCl3 þ AlCl3 Small amounts of pure UCl3 may also be prepared by thermal vacuum decomposition of NH4UCl4 · 4H2O (Droz˙dz˙yn´ski, 1988a, 1991). The compound obtained by the latter method is reactive and tractable for synthetic purposes, in contrast to that obtained by reduction with metals. Uranium trichloride is obtained either in the form of a fine olive‐green powder or as dark‐red crystals. It is not soluble in anhydrous organic solvents but it dissolves somewhat in glacial acetic acid, showing a characteristic transient red color. UCl3 dissolves in polar organic solvents, provided the compound or the solvents have absorbed some gaseous hydrogen chloride before. In aqueous solutions it is more or less rapidly oxidized. UCl3 reacts with chlorine to form a mixture of higher valence chlorides, and with bromine and iodine to yield UBrCl3 and UCl3I, respectively. The reaction with ammonia, acetonitrile, tetrahydrofuran (THF), and phenazine yields a number of unstable adducts. UCl3 is hygroscopic, but in contrast to other uranium halides no absorption of water is reported at pH2 O less than 320 Pa (2.4 mmHg). It is a strong reducing agent both in solution and in solid state. Several metals such as calcium or

Compounds of uranium

447

lithium reduce UCl3 to metallic uranium but the reaction has not been widely applied. UCl3 melts at 837 C and disproportionates to U and UCl4 at 840 C. A number of fused‐salt systems containing UCl3 have been investigated and the formation of some chloro complexes has also been reported (Bacher and Jacob, 1980). Uranium trichloride has hexagonal symmetry (Zachariasen, 1948a,c; Murasik et al., 1985; Schleid et al., 1987) with the space group P63/m – C26h . The coordination polyhedron is a symmetric tricapped trigonal prism arranged in columns in the c‐direction. Each column is surrounded trigonally by three others at 1/2c in such a manner that the prism atoms of one chain become the cap atoms of the neighboring one. The packing view of UCl3 along the [001] direction is shown on Fig. 5.39. The trichlorides Ac–Am and La–Nd have the same type of structure; some of the crystal data are listed in Table 5.25. High‐resolution polarized absorption spectra of LaCl3:U3þ single crystals (Karbowiak et al., 2002) and unpolarized spectra of a polycrystalline UCl3 sample in chlorinated naphathalene have been recorded at 4.2 K in the 4000– 30000 cm–1 range (Sobczyk et al., 2003). The experimental energy levels of the U3þ ion in the compounds were fitted to a semi‐empirical Hamiltonian employing free‐ion operators, one‐electron crystal‐field operators, and two‐particle correlation crystal‐field (CCF) operators, resulting in the determination of crystal‐field parameters and the assignment/reassignment of the recorded 5f3!5f3 transitions. The effects of selected CCF operators on the splitting of

Fig. 5.39 The tricapped trigonal prism configuration of halogen atoms in UCl3 and UBr3 ˚ are for UCl3; after Murasik et al., 1985). (distances in A

448

Uranium

some specific U3þ multiplets have also been investigated. The so far most accurate analysis of the band intensity, based on the Judd–Ofelt theory (Karbowiak and Droz˙dz˙yn´ski, 2003), has been based on the obtained electronic wave functions and a room temperature absorption spectrum of UCl3. A good agreement between the observed and calculated oscillator strengths has been obtained by combining the recorded band areas of some multiplets. In order to check the correctness of the calculations, the obtained intensity parameters, Ol, have been used for the determination of transition probabilities and these in turn for the calculations of radiative lifetimes. A good‐quality UCl3 absorption spectrum has been obtained also by means of teflon disk technique (Schmieder et al., 1970). The magnetic properties of uranium trichloride have been the subject of extensive investigations (Santini et al., 1999; Droz˙dz˙yn´ski, 1991). The inverse magnetic susceptibility as a function of the temperature follows the Curie‐Weiss law in two different temperature ranges and exhibits an antiferromagnetic transition at 22 K. Neutron diffraction studies revealed the existence of three‐dimensional long‐range anti‐ferromagnetic ordering below the Ne´el temperature TN ¼ 6.5K (Murasik et al., 1981, 1985). Uranium trichloride hydrates and hydrated uranium(III) chloro complexes Two hydrates of UCl3 are known, the heptahydrate, UCl3 · 7H2O and the hexahydrate, UCl3 · 6H2O. The heptahydrate was obtained by reduction of an UCl4 solution consisting of acetonitrile, propionic acid, and water (Droz˙dz˙yn´ski, 1985) with liquid zinc amalgam in an inert atmosphere whereas the reduction is most conveniently accomplished in an all glass apparatus with provisions for precipitation, filtration, and drying in an inert gas atmosphere (Droz˙dz˙yn´ski, 1979). It is interesting to note that a few years earlier Habenschuss and Spedding (1980) predicted the possible formation of this compound on the basis of ionic size considerations. UCl3 · 7H2O is a crystalline ink‐blue solid, readily soluble in numerous organic solvents. The compound is relatively resistant to oxidation by air at temperatures lower than 15 C. At higher temperatures it loses some of its crystallization water and in high vacuum it may be completely dehydrated at 200 C (Droz˙dz˙yn´ski, 1985). X‐ray single crystal analyses of the heptahydrate and of the less hydrated UCl3 · 6H2O compound have been reported (Mech et al., 2005) (see Table 5.25). In the heptahydrate the crystals are built from separate [U2Cl2(H2O)14]4þ units and Cl– ions. The characteristic features of this structure are dimers, formed by two uranium ions connected through the (Cl1) bridging chlorine atoms. Whereas the basic units of the crystal structure of UCl3 · 6H2O are Cl– anions and [UCl2(H2O)6]þ cations. The basic units of the crystal structure of UCl3 · 6H2O are Cl– anions and [UCl2(H2O)6]þ cations. The U atom is eight‐coordinated through six water molecules and two chlorine atoms. In this structure the characteristic feature is the existence of hydrogen bonds, which link the uranium eight‐coordinated polyhedra, forming a three‐dimensional network.

Compounds of uranium

449

The presence of water molecules in the inner coordination sphere was also confirmed by the solid‐state absorption spectrum of UCl3 · 7H2O, which is very similar with that of the U3þ aquo ion (Droz˙dz˙yn´ski, 1978) and exhibits significant differences in comparison to those of the less hydrated uranium(III) complex chlorides (Zych and Droz˙dz˙yn´ski, 1986; Droz˙dz˙yn´ski, 1988b). A detailed crystal‐field level analysis, based on a very good quality low‐temperature spectrum, is also available (Karbowiak et al., 2001). The heptahydrate exhibits Curie–Weiss dependence in the temperature range 10 to 300 K. The derived magnetic moment meff. ¼ 2.95 B.M. is much lower than the ‘free ion’ value of ca. 3.7 B.M., presumably due to the crystal field of the water molecules. The synthesis and characterization of a number of hydrated complex chlorides of the formulas MUCl4 · 5H2O (Barnard et al., 1972b), MUCl4 · 4H2O (M ¼ K, Rb or NH4) (Droz˙dz˙yn´ski, 1988b; Karbowiak and Droz˙dz˙yn´ski, 1993), MUCl4 · 3H2O (M ¼ Cs, K, Rb, or NH4) (Karbowiak and Droz˙dz˙yn´ski, 1993, 1999), and UCl3 · CH3CN · 5H2O (Zych and Droz˙dz˙yn´ski, 1986) have been reported. The pentahydrates were prepared by shaking a U(III) solution in 11 M HCl with the appropriate halide MCl (M ¼ K, Rb, or NH4 ) at 0 C. The UIII solution was prepared either by dissolving U2(SO4)3 · 8H2O or by dissolving a uranium (III) double sulphate in 11 M HCl (Barnard et al., 1972a). The preparation of the tetrahydrates can be achieved using a general route reported by Droz˙dz˙yn´ski (1979). In this method the reduction of a solution of UCl4, methyl cyanide, propionic acid, and water with zinc amalgam in anaerobic conditions generates an immediate precipitation of the tetrachlorouranate(III) tetrahydrate (Droz˙dz˙yn´ski, 1988b). The formation of the pentahydrates has not been confirmed by X‐ray investigations. Apart from some expected similarities between the compounds of the series, one can also note differences, e.g. that the tetrahydrates are reported to be readily soluble in dry methanol or ethanol, in contrast to the pentahydrates. The tetrahydrates are also much more resistant to oxidation and hydrolysis in dry air and temperatures below 15 C, and can be easily transformed into the anhydrous salts by thermal dehydration at high vacuum. One may note also a red shift of the 5f3!5f3 transitions and relatively large differences in the plots of the reciprocal susceptibilities as well as in the derived effective magnetic moments. Structure investigations revealed that (NH4)UCl4 · 4H2O belongs to the orthorhombic system, space group P21212. The crystal is built up from separate [U 3þ (H2O)4Cl4]– and NHþ polyhedra are 4 ions. The eight‐coordinated U connected by O–H · · · Cl hydrogen bonds forming a three‐dimensional network (Karbowiak et al., 1996c). X‐ray powder diffraction patterns show that the other members of the series could also be indexed on the basis of the orthorhombic cell (Karbowiak et al., 1996c). (NH4)UCl4 · 4H2O is an excellent starting material for the preparation of numerous other uranium(III) compounds.

450

Uranium

The MUCl4 · 3H2O series of compounds was also obtained by reduction of appropriate acetonitrile solutions of UCl4 and MCl (where M ¼ K, Rb, Cs, or NH4) with liquid zinc amalgam, but using somewhat different conditions than those used to prepare the tetrahydrates (Karbowiak and Droz˙dz˙yn´ski, 1993). In contrast to the deep purple‐red colors of the penta‐ and tetrahydrates the latter ones show green to brown colors. In this series the first broad and strong 5f3!5f26d1 bands were observed in the absorption spectra at wavenumbers higher than 21000 cm–1. Single‐crystal X‐ray analysis is available for CsUCl4 · 4H2O (Kra¨mer et al., 1991). The compound crystallizes in the monoclinic system, space group: P21/m (Table 5.25). Uranium has a coordination number of nine (tricapped trigonal prism) consisting of six chlorine atoms and three oxygen atoms (representing ˚ , respectively. Cesium is water) with mean distances of 2.957 and 2.552 A surrounded by eight chlorine atoms in the shape of a distorted cube, which is ˚ . One capped by two non‐bonded water ligands at a mean distance of 3.602 A can view the structure as a linking of the polyhedra [U(Cl1)4(Cl2)2(H2O)3] through two common edges of chloride (Cl1) ligands at two triangular faces of the trigonal prism of chloride ions to an infinite zigzag chain in the [010] direction. X‐ray powder diffraction analyses show that the remaining three members of the series could be indexed on the basis of the same monoclinic cell, and that they presumably are isostructural. For the tri‐ and tetrahydrates the first broad and strong 5f3! 5f26d1 bands are observed in the absorption spectra at about 21500 and 16000 cm–1, respectively. The red shift of these bands has been attributed to the formation of inner sphere complexes with some of the uranium–ligand bond lengths of a markedly more covalent character than that of the U3þ aqua‐ion, e.g. in UCl3 · 7H2O (Droz˙dz˙yn´ski, 1991; Karbowiak et al., 1996c). The magnetic susceptibility constants from the Curie–Weiss law are listed in Table 5.25. Anhydrous uranium(III) chloro complexes The largest group of well‐characterized uranium(III) compounds is formed by chloro complexes such as CsUCl4 (Karbowiak and Droz˙dz˙yn´ski, 1998c), M2UCl5 (M ¼ K, Rb, Cs. or NH4) (Droz˙dz˙yn´ski and Miernik, 1978; Meyer et al., 1983), SrUCl5 (Karbowiak and Droz˙dz˙yn´ski, 1998b), [(CH3)3N]3UCl6 (Karbowiak et al., 1996a); MU2Cl7 (M ¼ K, Rb, Ph4As or Ph4P) (Droz˙dz˙yn´ski, 1991; Karbowiak et al., 1996b); Ba2UCl7 (Karbowiak et al. 1998d); M2NaUCl6 (M ¼ K, Rb or Cs) (Aurov et al., 1983; Volkov et al., 1987), and Cs2LiUCl6 (Karbowiak and Droz˙dz˙yn´ski, 1998a). Most of the complex chlorides can be conveniently prepared by heating stoichiometric amounts of the component halides in graphite‐coated quartz tubes. The (NH4)2UCl5, Ph4AsU2Cl7, and Ph4PU2Cl7 compounds were obtained by reduction of appropriate uranium tetrachloride solutions in

Compounds of uranium

451

acetonitrile with liquid zinc amalgam (Droz˙dz˙yn´ski, 1991; Droz˙dz˙yn´ski and Miernik, 1978). Also the complexes with the general formulas M2UCl5 and MU2Cl7 can be prepared in this way (Droz˙dz˙yn´ski, 1979). All the syntheses were carried out in an inert atmosphere or high vacuum of ca. 10–4 Pa. Spectroscopic studies and crystal‐field analysis of U3þ:RbY2Cl7 and U3þ:Li2NaYCl6 single crystals were reported by Karbowiak et al. (1996b, 1977) and Karbowiak et al. (1996e, 1998b), respectively. The formation of number of uranium(III) chloro complexes has also been observed during investigations of binary and ternary phase systems (Brown, 1979). The complexes display a variety of colors (Table 5.25). All of them are hygroscopic but are somewhat resistant to oxidation in dry air. Unlike UCl3 the complex chlorides are readily soluble in numerous polar organic solvents. K2UCl5 and Rb2UCl5 crystallize in the orthorhombic system and are isotypical with the K2PrCl5/Y2HfS5 structures, their space group is Pnma, Z ¼ 4 (Kra¨mer et al., 1994). The coordination polyhedron is a monocapped trigonal prism [UCl7], connected via two opposite common edges to chains, [UCl11/1Cl21/1Cl31/1Cl44/2]–2, that run in the [010] direction of the unit cell. The relatively short U3þ–U3þ distance through the common edge, equal to ˚ , is assumed to be responsible for antiferromagnetic transitions at 8.6 4.556 A to 13.2 K. The temperature dependence of the inverse molar susceptibilities in the 20–300 K range follows the Curie–Weiss law in two temperature ranges, separated by a slight but apparent break at 130, 150, and 220 K, respectively, for K2UCI5, Rb2UCl5, and (NH4)2UCl5. The effective magnetic moments range from 3.47 B.M. for (NH4)2UCl5 to 3.99 B.M. for K2UCI5 (Droz˙dz˙yn´ski and Miernik, 1978). Some other magnetic susceptibility constants determined from the Curie–Weiss law are listed in Table 5.25. Solid‐state electronic spectra of thin mulls of the compounds show all characteristic features of the uranium(III) complex anions with strong 5f3!5f26d1 bands starting at ca. 18000 cm–1. The complexes exhibit very similar far‐IR spectra with one broad and not well‐resolved band in the region 100–240 cm–1 assigned to U‐Cl stretching modes. An analysis of magnetic phase transitions and crystal‐field splittings in the K2UX5 (X ¼ Cl, Br, or I) series of complex halides is reported by Keller et al.(1995). Single‐crystal X‐ray data show that Cs2NaUCl6 (Spirlet et al., 1988) crystallizes with the ideal cryolite arrangement. Each of the uranium or sodium ions is octahedrally surrounded by six chloride ions at the distance of 2.723(9) and ˚ , respectively. The cesium ions (site symmetry Td) are surrounded by 2.746(9) A ˚ (for other data see 12 equidistant chloride ions with d(Cs–Cl) ¼ 3.867(8) A Table 5.25). The enthalpies of formation of the hexachloro complexes are also available (Aurov and Chirkst, 1983; Schoebrechts et al., 1989). It is interesting to note the preparation of a reduced metallic uranium chloride which has been formulated as NaU2Cl6 or (Naþ)(U3þ)2(e–)(Cl–)6 (Schleid and

452

Uranium

Meyer, 1989). The extra electrons provided by the incorporation of the sodium atom are reported to occupy the 6d band of uranium. The compound is isostructural with NaPr2Cl6 and may be described as a stuffed derivative of UCl3 (hexagonal symmetry, space group P63/m). Other available information about the compounds is compiled in Table 5.25. Complexes of UCl3 with neutral donor ligands Ammonia adducts of the composition UCl3 · 7NH3 and UBr3 · 6NH3 were obtained by treatment of the halides with gaseous ammonia at room temperature and a pressure of 1013 hPa (Eastman and Fontana, 1958; Berthold and Knecht, 1965b, 1968). Since heating in a stream of nitrogen up to 45 C formed a relatively stable UCl3 · 3NH3 complex, indicating that the compounds contain some loosely bound ammonia. At higher temperatures this adduct decomposes into UCl3 · NH3, which is stable up to 300 C. According to MacCordick and Brun (1970) the heating of UCl3 with an excess of acetonitrile in sealed tube at 80 C results in the separation of a brown, hygroscopic solid of the formula UCl3 · CH3CN. However, an attempt to repeat the preparation was unsuccessful (Barnard et al., 1973). A purple adduct of the composition UCl3(THF)x has been prepared by reduction of a UCl4 solution in THF with stoichiometric amounts of NaH or an excess of Na2C2. The obtained purple solution of UCl3(THF)x is reported to be a useful starting material for numerous syntheses (Moody and Odom, 1979; Andersen, 1979; Moody et al., 1982). Hart and Tajik (1983) have reported the preparation of numerous air sensitive uranium(III) complexes with cyclic polyethers and aromatic diamines by reduction with liquid zinc amalgam in acetonitrile or acetonitrile/propionic acid solutions of UCl4 and the appropriate ligand, e.g. (UCl3)3(benzo‐15‐crown‐ 5)2 · 1.5CH3CN (yellow‐orange), (UCl3)3(benzo‐15‐crown‐5)2 (deep red), UCl3 (cyclohexyl‐15‐crown‐5) (red‐purple), (UCl3)3(18‐crown‐6)2 (red‐brown), (UCl3)5(dibenzo‐18‐crown‐6)3 (deep‐red), (UCl3)5(cis‐syn‐cis‐dicyclohexyl‐18‐ crown‐6)3 (red), UCl3(1,10 phenantroline)2 (violet‐purple) and UCl3(2,20 ‐bipyridile)2. The complexes are insoluble or react with common organic solvents. The preparation of several trivalent uranium complexes with crown ethers, oxygen donor or amine ligands has also been reported by other authors e.g. UCl3(15‐ crown‐5)(red), UCl3(18‐crown‐6), UCl3(benzo‐15‐crown‐5) (red) by Moody et al. (1979, 1982), as well as (UCl3)3(18‐crown‐6)2 (red‐brown), (UCl3)2(2,20 ‐ bipyridine)3 (bright‐green) and (UCl3)2(dimethoxyethane)3 (brown) by Rossetto et al. (1982). All complexes are hygroscopic and more or less rapidly oxidized by atmospheric air. They exhibit some characteristic features of U(III) absorption spectra with very intense f–d transitions in the visible and/or ultraviolet region. Infrared data are indicative to decide if the coordination takes place through the ligand nitrogen or oxygen atoms. Some of the complexes have also been characterized by magnetic susceptibility measurements at 298 K (Hart and Tajik, 1983).

Compounds of uranium (iii)

453

Uranium tribromide and uranium(III) bromo complexes

Uranium tribromide Uranium tribromide can most conveniently be prepared by the reaction of uranium hydride with gaseous hydrogen bromide at 300 C. The method is also suitable for a large‐scale preparation (Brown, 1979). Alternative methods include the reduction of UBr4 by metallic zinc or finely divided uranium at about 600 C. Since UBr3 reacts with quartz at that temperature, the reaction ought to be performed in a sealed tantalum or molybdenum vessel. In small quantities it may be readily prepared by thermal vacuum decomposition of NH4UBr4 · 5CH3CN · 6H2O (Zych and Droz˙dz˙ynski, 1990a). Other preparation procedures such as a direct combination of the elements or the reaction between uranium oxalate and gaseous hydrogen bromide seem to be less convenient (Brown, 1979). UBr3 is a dark‐brown substance, much more hygroscopic and sensitive to oxidation in air than UCl3. Rapid oxidation occurs on dissolution in water and in numerous organic solvents. It gives, however, somewhat more stable solutions in formamide, methyl acetate, dimethylacetamide, and acetic acid. Reactions with chlorine and bromine yield UCl4 and UBr4, respectively. UBr3 is reduced by calcium to metallic uranium at high temperatures. Uranium tribromide is isostructural with UCl3. The unit cell data are given in Table 5.25. The interatomic distances of the tricapped trigonal prismatic coordination polyhedron obtained from neutron diffraction studies (Levy et al., 1975) and by Kra¨mer and Meyer (1989) (values in parentheses) are: ˚ (3.150 A ˚ ) to the three capping Br atoms, d(U–Br) ¼ 3.062 d(U–Br) ¼ 3.145 A ˚ ˚ ˚ A (3.069 A) to the six Br atoms at the prism vertices, d(Br–Br) ¼ 3.652 A ˚ ˚ ˚ (3.663 A) at the trigonal prism face edge and d(U–U) ¼ 4.441 A (4.448 A) along the c‐direction. Using low‐temperature, high‐resolution absorption and fluorescence spectra of UBr3 doped into single crystals of LaBr3 (Paszek, 1978) and K2LaBr5 (Karbowiak et al., 1998a) a complete crystal‐field analysis in the 4000–22000 cm–1 absorption range has been performed. Magnetic susceptibility measurements in the 4.5–483 K range show an antiferromagnetic transition at TN ¼ (15 0.5) K. The effective magnetic moments equal to 3.92 and 3.57 B.M. have been determined from the temperature ranges where a plot of 1/wM against T is linear. Uranium tribromide hexahydrate Uranium tribromide may be converted to the hexahydrate by controlled exposure to oxygen‐free water vapor (Brown et al., 1968). On prolonged pumping the obtained red‐colored hexahydrate slowly loses most of the coordinated water until the composition approximates UBr3 · H2O. Complete dehydration occurs with a slow and gradual increase of temperature to about 100 C. X‐ray powder diffraction pattern shows that UBr3 · 6H2O is isostructural with the

454

Uranium

monoclinic lanthanide trihalide hexahydrates (Table 5.25). Further information is not available. Uranium(III) bromo complexes Bromouranates(III) of the composition M2UBr5 and M3UBr6 (M ¼ K, Rb or Cs) have been identified during investigations of the binary fused‐salt systems (Vdovenko et al., 1974a; Volkov et al., 1987). The pentabromouranates(III) may also be prepared by fusion of the appropriate components. Complexes of the M3UBr6 type are high‐temperature phases and decompose on cooling into the alkali bromide and the corresponding pentabromouranate(III). The melting points and regions of existence of the hexabromouranates(III) increase with an increase in the atomic number of the alkali metal. An opposite tendency is observed in the series of pentabromouranates(III) (Vdovenko et al., 1974a). Suglobova and Chirkst (1978a) have reported the thermodynamic properties of some of the bromo complexes. X‐ray powder diffraction analyses reveal that the hexabromouranates(III) have a face‐centered cubic symmetry whereas the pentabromouranates(III) are isostructural with the rhombic Tl2AlF6. On this basis, it has been assumed (Suglobova and Chirkst, 1978b) that the structure of the pentabromouranates (III) contains distorted UBr6 octahedra, which combine into parallel chains through common vertices. Aurov et al. (1983) and Aurov and Chirkst (1983) have reported X‐ray powder diffraction and thermodynamic data for K2NaUBr6 and Cs2NaUBr6 by (Table 5.25). A royal‐blue UBr3(THF)4 adduct has been obtained by a gentle dissolution of uranium metal turnings in THF at a reaction temperature near 0 C (Avens et al., 1994). The compounds K2UBr5 · 2CH3CN · 6H2O, Rb2UBr5 · CH3CN · 6H2O and (NH4)[UBr2(CH3CN)2(H2O)5]Br2 were obtained from acetonitrile solutions of UBr4 and the appropriate ammonium or alkali metal bromide, by reduction with liquid zinc amalgam (Zych and Droz˙dz˙yn´ski, 1990b, 1991; Zych et al., 1993). All compounds are well characterized by various physical methods (Table 5.25). Single crystal X‐ray data are available for (NH4)[UBr2(CH3CN)2(H2O)5]Br2, (Zych et al., 1993). (iv)

Uranium(III) iodide and uranium(III) iodo complexes

Uranium triiodide A convenient and widely used method for the preparation of uranium triiodide involves the action of iodine vapors on finely divided uranium metal, either in sealed or flow systems at 570 and 525 C, respectively. Large quantities of high purity UI3, in the form of black crystals, are collected in the 375–450 C condensing zone of a flow system apparatus first reported by Gregory (1958). Alternative procedures employ the reduction of uranium tetraiodide with zinc metal or finely divided uranium metal, reaction between uranium hydride and

Compounds of uranium

455

methyl iodide, and vacuum thermal decomposition of UI4 at 225–235 C (Brown, 1979). UI3 is a jet‐black, highly hygroscopic crystalline solid, sensitive to oxidation in air. Even at elevated temperatures the triiodide is corrosive and attacks glass, which at 800 C is reduced to silicon. The compound reacts with iodine, methylchloride, and uranium tetrachloride to yield UI4, UCl4, and UClI3, respectively. UI3 dissolves in aqueous solutions, methanol, ethanol, ethyl acetate, dimethylacetamide, and acetic acid forming unstable U(III) solutions. Spontaneous oxidation within 1 min was observed in organic solvents like dioxan, pyridine, acetonitrile, dimethylformamide, or acetone (Barnard et al., 1973). UI3 possesses the orthorhombic PuBr3‐type structure (Zachariasen, 1948a). The structure (space group Ccmm ‐ D17 2h ) was studied in detail also by neutron diffraction profile analysis (Levy et al., 1975; Murasik et al., 1981). The coordination polyhedron is a distorted bicapped trigonal prism layered in planes perpendicular to the a‐axis. Diffuse reflectance spectra have been reported in the 4000–30000 cm–1 range at room temperature and 90 K (Barnard et al., 1973). In the series of uranium (III) halides one may observe a pronounced red shift of the first 5f3!5f26d1 bands from about 23000 cm–1 in the spectrum UF3 to about 13400 cm–1 forUI3. Magnetic susceptibility measurements have shown an antiferromagnetic transition at TN ¼ (3.4 0.2) K as well as a second susceptibility maximum at 1.5 K. UI3 exhibits a first‐order magnetic phase transition. The compound orders antiferromagnetically at TN ¼2.6 K, resulting in the appearance of a magnetic sublattice (Parks and Moulton, 1968). Neutron scattering investigations reveal hysteresis of the integretated neutron intensity of the magnetic reflections versus temperature, which confirms that the phase transition is of the first order (Murasik et al., 1986). Complexes with neutral donor ligands The reaction of elemental iodine with an excess of oxide‐free uranium metal turnings in appropriate coordinating solvents at 0 C yields dark purple UI3(THF)4, purple UI3(dme)4, black UI3(py)4 (Avens et al., 1994), and a dark brown UI3(CH3CN)4 (Droz˙dz˙yn´ski and du Preez, 1994) (THF, tetrahydrofuran; dme, 1,2‐dimethoxyethane; py, pyridine). These organic‐solvent soluble Lewis base adducts are reported to be key starting materials for the preparation of variety of inorganic and organometallic uranium complexes. Single‐crystal X‐ray diffraction data show that UI3(THF)4 is mononuclear with a pentagonal bipyramidal coordination geometry about the uranium ion. Two iodide atoms, ˚ are axially coordinated. The third with an average U–I lengths of 3.111(2) A iodide atom and the four THF ligands lie in the equatorial plane with the U–I ˚ and average U–O distances of 2.52(1) A ˚ (Avens et al., distance of 3.167(2) A 1994). Other available information is listed in Table 5.25.

456

Uranium

(v) Uranium(III) oxide halides and mixed halides The uranium(III) oxide halides UOCI, UOBr, and UOI were prepared by heating stoichiometric mixtures of UO2X2, UO2, and U or UX4, U3O8 and U (X ¼ Cl, Br or I), for 24 h at 700 C (Levet and Noe¨l, 1981). The chemical properties of UOCI, UOBr, and UOI have not been reported. The X‐ray powder diffraction patterns are consistent with the tetragonal PbFCl‐type of structure (P4/nmm). In a recent investigation, the structure was refined by single‐crystal X‐ray analysis and the atomic positions were determined (Schleid and Meyer, 1988). A plot of the inverse paramagnetic susceptibility against temperature follows the Curie–Weiss law from about 220 to 300 K with meff of 3.40, 3.67, and 3.56 B.M. for UOCl, UOBr, and UOI, respectively. All of the oxide halides are weak ferromagnets with nearly the same transition temperatures ranging from 190 to 183 K. Some IR data are also available (Levet and Noe¨l, 1981). The preparation of a number of uranium(III) mixed halides with the general formulas UXY2 and UX2Y, where X ¼ Cl or Br and Y ¼ Cl or I were reported (Gregory, 1958), but very little information about their properties is available. UClBr2 was obtained by reduction of UCl3Br with hydrogen at 400 C. The UBr3 by‐product is removed from the substance by treatment with iodine. One of the most convenient methods for the preparation of UCl2Br is reported to be the fusion of a 2:1 molar ratio of UCl3 and UBr3 at 850 C. The solid‐state reaction between UCl3 and UI3 has been also applied successfully for the preparation of UClI2. The remaining mixed halides, i.e. UCl2I, UBr2I, and UBrI2 have usually been obtained by thermal decomposition of UCl2I2 and UBr2I2 at 400 C, and of UBrI3 at 375 C (see also Table 5.25).

(b)

Tetravalent halides and complex halides

Uranium tetrahalides and complex halides have so far been the most extensively investigated group of uranium compounds besides those in the 6þ oxidation state. The tetrahalides are not stable on exposure to air however with some exceptions, e.g. that of UF4. They are more or less hygroscopic and after a time the compounds get oxidized in air. The large chemical stability of UF4 is mainly due to its high lattice energy. Apart from the fluorides most of the compounds are readily soluble in polar solvents. Aqueous solutions are slowly oxidized to U(VI) species, but in pure and thoroughly deoxygenated solvents U4þ is fairly stable. The typical colors vary from pale olive green to deep bluish‐green. In few cases black, brown, and blue colors have also been noticed (Table 5.26). The synthesis of binary uranium(IV) halides usually requires strictly oxygen‐free conditions. The coordination polyhedra in the binary tetrahalides are more or less distorted forms of a square antiprism (UF4), a dodecahedron (UCl4), or a pentagonal bipyramid (UBr4). The tetrahalides form stable solid complexes with a large variety of ligands, e.g. of the UX4L2‐type (X ¼ Cl. Br, or I)

UF4

Formula emerald green; non‐volatile; almost insoluble in water and organic solvents; soluble in oxidizing solutions; m.p. ¼ 1036 C; density: 6.70 g cm–3; meff. ¼ 3.28 B.M.; y ¼ –116 K (77–500 K)d; meff. ¼ 2.83 B.M.; y ¼ –146 K (75–295K)d; meff. ¼ 2.79 B.M; (1–300 K)d UF4(cr): Df Gom ¼ –1823.5 (4.2){, o ¼ 151.7 Df Hmo ¼ –1914.2 (4.2){, Sm { { o (0.2) ; Cp;m ¼ 116.0 (0.1) . UF4(g): Df Gom ¼ –1576.9 (6.7){, Df Hmo ¼ o ¼ 360.7 (5.0){; –1605.2 (6.5){, Sm { o Cp;m ¼ 95.1 (3.0) . logp(mmHg) ¼ 22.60–16400T–1 – 3.02 logT (298– 1309 K). log p(mmHg) ¼ 28.05– 15300·T–1 –5.03 logT (1309–1755 K); IR (cm–1): 404(s)[n(U–F)]; 194 (s) [n(F–U–F), bending]; Energy levels parameters (cm–1): F2 ¼ 44 784, F4 ¼ 43107, and F6 ¼ 25654; z5f ¼ 1761.0(3.4), a ¼ 34.74, b ¼ –767.3, and g ¼ 913.9; P2 ¼ 2715 (94); B20 ¼ 1183(28), B22 ¼ 29(27), B40 ¼ –2714(99), B42 ¼ 3024(71), B44 ¼ –3791(53), B60 ¼ –1433 (148),B62 ¼ 1267(101), B64 ¼ –1391 (93) and B66 ¼ 1755(82); rms ¼ 31; n ¼ 69

6 monoclinic; C2h , C2/2, No. 15; a ¼ 12.73 [12.7941], b ¼ 10.753 [10.7901]; c ¼ 8.404 [8.3687 90]; b ¼ 126.33 [126.25]; [V ¼ 931.68]; Z ¼ 12; d(calc.) ¼ 6.71], d(exp.) ¼ 6.71; d(U–F) distances: 2.23– 2.354. Antiprism linked in 3‐dimensions by sharing all corners. Each uranium atom has eight fluorine neighbours arranged in a slightly distorted square antiprism. In square brackets are given the data of Kern et al., (1994)

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm–3)c

synthesis (Halstead et al., 1982; Bacher and Jacob, 1980, Freestone and Holloway, 1990); crystallographic data and temperature variation of structural parameters, (Larson et al., 1964; Keenan and Asprey, 1969; Kern et al., 1994); thermodynamic data (Grenthe et al., 1992; Guillaumont et al., 2003); magnetic data, IR, NIR; Raman spectra; Photo‐ acoustic spectra, ESCA spectra; redox reactions; applications for nuclear fuel (Conway, 1959; Bacher and Jacob, 1980; crystal‐ field spectra (Carnall et al., 1991); Vis and UV spectra (Conway, 1959; Bacher and Jacob, 1980); photo‐electron spectra (Thibaut et al., 1982)

Remarks regarding information available and references

Properties of selected uranium(IV) halides and complex halides.a

Selected properties and physical constants b

Table 5.26

IR (cm–1): 2950, 3365, and 3840

slightly soluble in water (0.1g L–1), soluble in dimethylammonium acetate; stable up to 100 C; UF4·2.5H2O (cr): Df Gom ¼ –2440.3 (6.2){, Df Hmo ¼ –2671.5(4.3){, o o ¼ 263.5(15.0){; Cp;m ¼ 263.7 Sm (15.0){

UF4·4/3H2O

UF4·2H2O

UF4·2.5H2O

LiUF5

dark‐green; m.p. 605 C*

grass‐green

Formula

UF4·7H2O

Selected properties and physical constantsb

(Contd.)

cubic; O5h , Fm 3m, No.225; a ¼ 5.65 (1); V ¼ 180.36; Z ¼ 2; d(calc.) ¼ 6.01 6 tetragonal; C4h , I41/a; No.88; a ¼ 14.8592(96), c ¼ 6.5433(9); Z ¼ 16; V ¼ 90.3; d(calc.) ¼ 6.23; the U atom is surrounded by nine F ions in a tricapped trigonal prismatic array. Adjacent prisms share edges and corners to form network

monoclinic; d ¼ 5.79. The water molecules are bonded through O–H–F bridges cubic; O5h , Fm 3m, No.225; a ¼ 5.701(0.012); d(calc.) ¼ 6.32; Z ¼ 2; d(U–U) ¼ 2.465, d(F–F) ¼ 2.846 orthorhombic; D16 2h , Pnam, No.62; a ¼ 12,75, b ¼ 11.12, c ¼ 7.05; d(calc.) ¼ 4.74; Z ¼ 8; d(U1–F) (5) ¼ 2.29; d(U1–O) (4) ¼ 2.63–2.84; d(U2—F) (9) ¼ 2.39

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm–3)c

Table 5.26

crystallographic data (Brunton, 1966; Keenan, 1966; Penneman et al., 1973)

crystallographic data (Dawson et al., 1954; Borisov and Zaniedporovski, 1971; Zadneporovskii and Borisov, 1971);1H‐NMR, 19F‐NMR, IR data, thermodynamic data (Bacher and Jacob, 1980; Grenthe et al., 1992; Guillaumont et al., 2003). crystallographic data (Dawson et al., 1954)

crystallographic data (Dawson et al., 1954; Bakakin, 1965), NMR data (Gabuda et al., 1969)

crystallographic data (Gagarinskii et al., 1965; Khanaev et al., 1967)

Remarks regarding information available and references

b2‐Na2UF6

a‐Na2UF6

Li2CdUF8

Li2CaUF8

LiU4F17

Li4UF8

Li3UF7

blue; m.p. ¼ 673 C; IR(cm–1): n(U–F) ¼ 375(s); n(F–U–F), bending ¼ 192(s); 258(m), n(Na–F) ¼ 258(m); other: 146w

yellowish‐green or green square prism; 775 C*

m.p. ¼ 496 C (incongr.)

trigonal/rhombohedral; D23 , P321, No 150; a ¼ 5.95(1), c ¼ 3.7(1); Z ¼ 1; V ¼ 114.97; d(calc.) ¼ 5.75; tricapped trigonal prism sharing ends to form chain

tetragonal; D92d , I  4m2, No. 119; a ¼ 5.2290(12), c ¼ 11.0130(18); Z ¼ 2; V ¼ 301.12; d(exp.) ¼ 4.85, d(calc.) ¼ 4.9. tetragonal; D92d , I  4 (or I  4m2), No.119; a ¼ 5.222(0.002), c ¼ 10.952(0.005); Z ¼ 2; d(exp.) ¼ 4.85, d(calc.) ¼ 4.86. 3m, No 225; a ¼ cubic; O5h , Fm 5.565(4); Z ¼ 4; V ¼ 172.34; d(calc.) ¼ 5.11

tetragonal; D74h , P4nmn, No.129; a ¼ 6.132, c ¼ 6.391 orthorhombic; D16 2h , Pnma; No.62; a ¼ 9.960, b ¼ 9.883, c ¼ 5.986; Z ¼ 4; d(calc.) ¼ 4.71; V ¼ 589.23; the coordination polyhedron is a triangular prism with pyramids on two of the prism faces; each U atom has 8 F– neighbours at 2.29 (0.02) and a ninth at 3.30(0.03); CN. ¼ 8 a ¼ 8.990, c ¼ 11.387

crystallographic data (Zachariasen, 1948d)

crystallographic data (Zachariasen, 1948d; Mighell and Ondik, 1977)

crystallographic data (Ve´drine et al., 1973)

crystallographic data (Jove and Cousson, 1977; Cousson et al., 1977) crystallographic data (Ve´drine et al., 1973; 1979)

crystallographic data (Thoma and Penneman, 1965) crystallographic data; IR spectra (Barton et al., 1958; Brunton, 1967)

NaU2F9

Na3UF7

d‐Na2UF6

g‐Na2UF6

Formula

geenish‐blue; m.p. ¼ 629 C; meff. ¼ 3.40 B.M.; y ¼ 290 K (74–300 K)d or meff. ¼ 3.30 B.M.; y ¼ 81 K meff. ¼ 3.38 B.M.; y ¼ 290 K; (for 195–473 K range). IR (cm–1): n(U–F) ¼ 380(s); n(F–U–F), bending ¼ 217(s); n(Na–F) ¼ 240 (m); other, 146w yellowish‐green; m.p. ¼ 660 C (dec.); IR (cm–1): n(U–F) ¼ 360(s); n(F–U–F), bending ¼ 194(s); n(Na‐F) ¼ 260(m); other, 145w

m.p. ¼ 648 C

meff. ¼ 3.13 to 3.23 B.M.; y ¼ –84 to –89 K (14–300 K)d

Selected properties and physical constantsb

(Contd.)

orthorhombic; D25 2h , Immm, No 71; a ¼ 5.56, b ¼ 4.01, c ¼ 11.64; the coordination geometry in UF9 chains is a tricapped trigonal prism (structure type of b1‐K2UF6) hexagonal; C31 , P3, No.143; a ¼ 6.112(2), c ¼ 7.240(2); Z ¼ 2; V ¼ 234.23; d(calc.) ¼ 5.64; in the asymmetric unit cell are two U ions; each has nine nearest F– ions at the corners of capped trigonal prisms; d(U–F) ranges from 2.23 to 2.42(1) tetragonal; D17 4h , I4/mmm, No.139; a ¼ 5.488, c ¼ 10.896

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm–3)c

Table 5.26

IR data (Ohwada et al., 1972)

crystallographic data (Zachariasen, 1948a; Mighell and Ondik, 1977); magnetic data (Bacher and Jacob, 1980)

crystallographic data (Brunton et al., 1965; Cousson et al., 1979)

crystallographic data (Zachariasen, 1948d; Mighell and Ondik, 1977); magnetic data (Bacher and Jacob, 1980)

Remarks regarding information available and references

b1‐K2UF6

green; meff. ¼ 3.45 B.M.; y ¼ –108K (74–300 K)d; IR(cm–1): n(U–F)val. ¼ 360s, 292s; n(F–U–F)def. ¼ 217sn; 161m, n(F–U–F)def. or n(K–F)lat. ¼ 147m; n(K–F)lat. ¼ 84w drab olive; m.p. ¼ 755 C*; stable between 608 –and 755 C; below 608 C decomposes to K3UF7 þ K7U6F31

a‐K2UF6

 hexagonal; D33h , P62m, No.189; a ¼ 6.5528(2), c ¼ 3.749(1); Z ¼ 1; V ¼ 139.41; d(calc.) ¼ 5.1235; tricapped trigonal prisms share the triangular faces perpendicular to the three fold axis of the ideal polyhedron to form infinite chains

 No.148; rhombohedral; C3i2 , R3, a ¼ 14.72, c ¼ 9.84; Z ¼ 3; V ¼ ˚ 3; CN ¼ 8; isostructural 615.5 A with Na7Zr6F31 in which the basic coordination geometry about central ion is approx. square antiprismatic, and six antiprisms share corners to form an octahedral cavity which encloses the additional F atom. hexagonal; C31 , P3, No.143; a ¼ 6.24, c ¼ 7.80; Z ¼ 2; d(calc.) ¼ 5.23 hexagonal; C31 , P3, No. 143; a ¼ 6.29, c ¼ 8.13; Z ¼ 2; d(calc.) ¼ 5.49 cubic with disordered cations; O5h , Fm 3m, No 225; a ¼ 5.946(1); Z ¼ 4; V ¼ 210.22; d(calc.) ¼ 4.53

green; m.p. ¼ 718 C; IR(cm–1): n(U–F) ¼ 383(s); n(F–U–F), bending ¼ 193(s); n(Na–F) ¼ 241(m)

pale green, purple interference

orthorhombic; D23 2h , Fmmm, No.69; a ¼ 17,7, b ¼ 29.8, c ¼ 12.7 cubic; a ¼ 5.589

green

NaRbUF6

NaKUF6

Na7U6F31

Na5U3F17

Na7U2F15

crystallographic data (Zachariasen, 1948a; Brunton, 1969a, Penneman et al., 1973; Bacher and Jacob, 1980; IR spectra (Soga et al., 1972)

crystallographic data (Brunton et al., 1965); optical data (Bacher and Jacob, 1980) crystallographic data (Zachariasen, 1948d); magnetic data (Bacher and Jacob, 1980)

crystallographic data (Brunton et al., 1965)

crystallographic data (Thoma et al., 1963; Mighell and Ondik, 1977) crystallographic data (Thoma et al., 1963). crystallographic data (Thoma et al., 1963; Mighell and Ondik, 1977)

b2‐K2UF6

KU2F9

K7U6F31

b‐K3UF7 green; m.p. ¼ 789 C (congr.); IR: n(U–F)val. ¼ 380s, 319m; 244sh, 200m; n(F–U–F) def. ¼ 244sh, 200m; n(F–U–F) def. or n(K–F) lat. ¼ 153m, 114m; n(K–F) lat. ¼ 80w green; m.p. ¼ 765 C (incongr.) with formation of UF6; IR (cm–1): n(U–F)val. ¼ 360s, 331s, 290sh; n(F–U–F) def. ¼ 235m, 204m; n(F–U–F)def. or n(K–F)lat. ¼ 160m, 148m, 118w; n(K–F)lat. ¼ 85w

deep‐green; m.p. ¼ 957 C; IR (cm–1): n(U–F)val. ¼ 362s; n(F– U–F)def. ¼ 206s; n(F–U–F)def. or n(K–F)lat. ¼ 120m; n(K–F)lat. ¼ 80w

green

Formula

a‐K3UF7

Selected properties and physical constantsb

(Contd.)

hexagonal; D23 , P321, No.150; a ¼ 6.54(2); c ¼ 4.04; Z ¼ 1; V ¼ 150.02; d(calc.) ¼ 4.76. tricapped trigonal prism sharing ends to form chain 3m, No.225; a ¼ 9.22 cubic; O5h , Fm (2); Z ¼ 4; V ¼ 783.78, d(calc.) ¼ 4.14; the seven F atoms are statistically distributed over fluorite lattice sites orthorhombic; D13 2h , Pmmn, No.59 7 , No. 31; or Pmn21, C2v a ¼ 6.58, b ¼ 8.31, c ¼ 7.22 3, No. 148; rhombohedral; C3i2 , R a ¼ 9.376, a ¼ 107.20; Z ¼ 1; CN ¼ 8; d(calc.) ¼ 5.58; isostructural with Na7Zr6F31; square antiprisms sharing corners, with one fluorine atom in a cavity orthorhombic; D16 2h , Pnma, No 62; a ¼ 8.7021, b ¼ 11.4769, c ¼ 7.0350; Z ¼ 4; V ¼ 702.61; CN ¼ 9; d(calc.) ¼ 6.4851; tricapped trigonal prism, sharing ends and edges; d(U–F) ¼ 2.29–2.39

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm–3)c

Table 5.26

X‐ray powder diffraction and single crystal data, IR spectra (Brunton et al., 1965; Brunton, 1969b); IR spectra (Soga et al., 1972).

crystallographic data, IR spectra (Brunton et al., 1965); IR spectra (Soga et al., 1972)

crystallographic data, IR spectra (Zachariasen, 1954c; Burns and Duchamp, 1962; Bacher and Jacob, 1980); IR spectra (Soga et al., 1972) crystallographic data (Burns and Duchamp, 1962)

crystallographic data (Zachariasen, 1948d); IR spectra (Soga et al., 1972)

Remarks regarding information available and references

green; m.p. ¼ 818 C (incongr)

pale green; m.p. ¼ 995 C (congr.)

green; m.p. ¼ 675 C (incongr.)

Rb3UF7

Rb7U6F31

deep‐green; m.p. ¼ 832 C (incongr. with formation of UF4)

metastable

Rb2UF6

RbU6F25

KU6F25

hexagonal; D46h , P63/mmc, No.194; a ¼ 8.18, c ¼ 16.42; d(calc.) ¼ 6.73; Z ¼ 2; tricapped trigonal prism, sharing edges and corners to form double rings of six polyhedra each hexagonal; D46h , P63/mmc, No.194; a ¼ 8.195, c ¼ 16.37; Z ¼ 2; d(calc.) ¼ 6.908; tricapped trigonal prism, sharing edges and corners to form double rings of six polyhedra each orthorhombic; D17 2h , Cmcm, No.63; a ¼ 6.958(2), b ¼ 12.042(5), c ¼ 7.605(5); Z ¼ 4; V ¼ 637.21; d(calc.) ¼ 5.45; the structure is of the K2ZrF6 type and consists of infinitive chains of UF8 polyhedra in the form of dodecahedra with triangular faces (ideal symmetry D2d) cubic; O5h , Fm 3m, No.225; a ¼ 9.5667; the seven F atoms are statistically distributed over fluorite lattice sites rhombohedral; C3i2 , R 3, No. 148; a ¼ 9.595; a ¼ 107.67, Z ¼ 1; CN ¼ 8; d(calc.) ¼ 6.02; structure type of Na7Zr6F31; square antiprisms sharing corners, with one fluorine atom in a cavity crystallographic data (Burton et al., 1965; Thoma et al., 1958); IR spectra (Soga et al., 1973)

crystallographic data (Bacher and Jacob, 1980); IR spectra (Soga et al., 1973)

X‐ray powder and single crystal diffraction data (Kruse, 1971; Kruse and Asprey, 1962); IR spectra (Soga et al., 1973)

crystallographic data (Mighell and Ondik, 1977; Brunton et al., 1965); IR spectra (Soga et al., 1973)

crystallographic data (Burton et al., 1965; Zachariasen, 1948d); IR spectra (Soga et al., 1972)

CsU6F25

CsU2F9

other complex fluorides with rubidium: RbUF5 (green blue, m.p. ¼ 735 C; IR(cm–1):nUF ¼ 370, 330, 302 cm–1, RbU3F13, Rb2U3F14 (m.p. ¼ 722 C*) CsUF5

Formula

deep‐green; m.p. ¼ 867 C (incongr.) with formation of UF4

greenish‐blue (or sky blue); m.p. ¼ 735 C. deep‐green crystals

Selected properties and physical constantsb

(Contd.)

6 monoclinic; C2h , C2/c, No.15; a ¼ 15.649(3), b ¼ 7.087(1), c ¼ 8.689 (2); b ¼ 118,11(2); Z ¼ 4, V ¼ 849.98; CN ¼ 8 1/2 (effective); d(exp.). ¼ 6.4; d(calc.) ¼ 6.09; tricapped trigonal prism, one prism corner statistically only half‐occupied. Contains 8‐coordinate U in edge‐sharing polyhedra forming U4F16 sheets hexagonal; D46h , P63/mmc, No.194; a ¼ 8.2424(4), c ¼ 16.4120(20); Z ¼ 2; V ¼ 965.61; d(calc.) ¼ 7; tricapped trigonal prism, sharing edges and corners to form double rings of six polyhedra each

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm–3)c

Table 5.26

crystallographic data (Brunton et al., 1965, 1971)

crystallographic data (Rosenzweig et al., 1973)

general properties (Bacher and Jacob, 1980)

Remarks regarding information available and references

Cs3UF7

NH4U3F13

(NH4)4UF8

g‐(NH4)2UF6

b‐NH4UF5

decomposes in vacuum at 300–400 C to UF4

deep green; over 130 C decomposes in air to NH4F þ (NH4)2UF6

decomposes under He over 220 C to NH4Fþ(NH4)7U6F31

polymeric

over 190 C decomposes partly to b‐NH4UF5

pale blue; m.p. ¼ 970 C

Cs2U3F14

a‐NH4UF5

greenish‐ blue to light blue; m.p. ¼ 800 C* bluish‐green; m.p. ¼ 737 C (incongr.) with formation of Cs2U3F14

Cs2UF6

5 monoclinic; C2h , P21/c, No.14; a ¼ 7.799(5), b ¼ 7.158(5), c ¼ 8.762 (7); b ¼ 116.45; Z ¼ 4; V ¼ 437.94; d(calc.) ¼ 5.32; CN ¼ 9 2 orthorhombic; C2v , Pmc21, No.26 5 or D2h , Pmcm, No.51; a ¼ 4.05, b ¼ 7.03, c ¼ 11.76; Z ¼ 2; d(calc.) ¼ 3.9 6 monoclinic; C2h , C2/c, No.15; a ¼ 13.126, b ¼ 6.692, c ¼ 13.717; b ¼ 121.32; Z ¼ 4; CN ¼ 8; d(exp.) ¼ 2.96; d(calc.) ¼ 2.982; d(U–F) ¼ 2.25–2.33; discrete distorted tetragonal antiprismatic array 2 orthorhombic; C2v , Pmc21, No. ¼ 26; a ¼ 8.045(2), b ¼ 8.468(2), c ¼ 7.375(2); V ¼ 502.42; Z ¼ 2; d(calc.) ¼ 6.47

cubic; O5h , Fm 3m, No.225; a ¼ 9.90; CN ¼ 7; structure type of K3UF7; d(calc.) ¼ 7.92. rhombohedral; C3i2 , R 3, No.148; a ¼ 9.55; a ¼ 107.4

2 monoclinic; C2h , P21/m, No.11 or P21, C22 , No.4; a ¼ 8.39, b ¼ 8.46, c ¼ 20.88; b ¼ 119.89

crystallographic data (Abazli et al., 1980)

X‐ray powder and single crystal data; (Rosenzweig and Cromer, 1970); thermodynamic data, magnetic and optical data (Bacher and Jacob, 1980)

crystallographic data (Benz et al., 1963; Penneman et al., 1974); magnetic susceptibilities (Bacher and Jacob, 1980) crystallographic data (Penneman and Ryan, 1974) magnetic susceptibilities (Bacher and Jacob, 1980) crystallographic data (Penneman et al., 1964a); magnetic and optical data (Bacher and Jacob, 1980)

general properties (Bacher and Jacob, 1980) crystallographic data (Brunton et al., 1965); magnetic susceptibilities (Bacher and Jacob, 1980) crystallographic data (Penneman et al., 1973; Brunton et al., 1965)

other complex fluorides with hydrazinium: (N2H5)2UF6, (N2H5)3UF7 UN0.95 F1.2

[N(C2H5)4]2UF6

N2H5UF5

(NH3OH)UF5

(NH4)7U6F31

Formula

uranium oxidation number ¼ þ4.05

white cryst.; air and moisture sensitive; IR (cm–1):n(U–F) ¼ 405; F2 ¼ 49699, ς5f ¼ 1970; B40 ¼ 10 067(113), B60 ¼ 22(72); rms ¼ 67

m.p. > 150 C (dec.); under He gas to UF4; exists in a, b, g and d forms

Selected properties and physical constantsb

(Contd.)

tetragonal; D52h , P4/n, No.85; a ¼ 3.951 c ¼ 5.724; Z ¼ 2; V ¼ 89.35; d(calc.) ¼ 10.19

rhombohedral; C3i2 , R 3, No.148; a ¼ 9.55; a ¼ 107.4; CN ¼ 8; square antiprisms sharing corners, with one fluorine atom in a cavity; structure type of Na7Zr6F31. orthorhombic; D12 , P222, No.16; 1 , Pmm2, No.25 or D12h , Pmmm, C2v No.47; a ¼ 10.963, b ¼ 14.9024, c ¼ 10.4391 1 orthorhombic; D12 , P222, or C2v , Pmm2; a ¼ 7.941, b ¼ 6.372, c ¼ 7.478; Z ¼ 4

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm–3)c

Table 5.26

crystallographic data (Jung and Juza, 1973)

crystallographic data (Ratho and Patel, 1968); thermodynamic data; magnetic susceptibilities; IR spectra, decomposition data. (Bacher and Jacob, 1980) general properties (Ryan et al., 1974); electronic spectra, crystal‐ field parameters (Wagner et al., 1977) general properties (Bacher and Jacob, 1980)

crystallographic data (Benz et al., 1963; Penneman et al., 1964a); thermodynamic data, magnetic and optical properties (Bacher and Jacob, 1980) crystallographic data (Ratho et al., 1969)

Remarks regarding information available and references

m.p. ¼ 598 C (eutec.) m.p. ¼ 542 C (incongr.)

Tl2UF6

Tl3UF7

TlU3F13

m.p. ¼ 674 C (incongr)

m.p. ¼ 317 C*

m.p. ¼ 640 C

other complex fluorides with lead: Pb3U2F14, Pb6UF16. TlUF5

Tl4UF8 Tl7U6F31

green

green; meff. ¼ 3.25 B.M.; y ¼ –101 (74–300 K)d

PbUF6

BaUF6

SrUF6

CaUF6

Ca0.925 U0.075 F2.15

orthorhombic; a ¼ 8.49, b ¼ 8.04, c ¼ 7.38.; Z ¼ 2; d(calc.) ¼ 7.68

hexagonal; a ¼ 15.39, c ¼ 10.80; Z ¼ 3; d(calc.) ¼ 7.74

5 monoclinic; C2h , P21/c; No.14; a ¼ 8.222(2), b ¼ 13.821(4), c ¼ 8.317(5); b ¼ 102.53(3); Z ¼ 8; V ¼ 922.6; d(calc.) ¼ 7.74; tricapped trigonal prismatic at U orthorhombic; a ¼ 4.07, b ¼ 6.97, c ¼ 11.56; Z ¼ 2; d(calc.) ¼ 7.54 cubic; a ¼ 9437; Z ¼ 2; d ¼ 7.92

cubic; O5h ; Fm 3m; No.225; a ¼ 5.507(3), Z ¼ 4; V ¼ 167.01; d(calc.) ¼ 3.81 hexagonal (LaF3 type); D43d , P 3c1; No.165; a ¼ 6.928, c ¼ 7.127; d(calc.) ¼ 6.59 hexagonal (LaF3 type); D43d , P 3c1; No.165; a ¼ 7.122, c ¼ 7.293; d(calc.) ¼ 6.83 hexagonal (LaF3 type); D43d , P 3c1; No.165; a ¼ 7.403, c ¼ 7.482; d(calc.). ¼ 6.86 hexagonal (LaF3 type); D43d , P 3c1; No.165; a ¼ 7.245, c ¼ 7.355; d(calc.) ¼ 8.33

crystallographic data (Avignant and Cousseins, 1977; Avignant et al., 1977) crystallographic data (Avignant et al., 1977)

crystallographic data (Avignant and Cousseins, 1971) crystallographic data (Avignant and Cousseins, 1971)

infrared spectra (Soga et al., 1973); crystallographic data (Avignant et al., 1980, 1982)

general properties Bacher and Jacob (1980)

crystallographic data (Keller and Salzer, 1967)

crystallographic data (Keller and Salzer, 1967)

crystallographic data (Keller and Salzer, 1967) magnetic data (Bacher and Jacob, 1980) crystallographic data (Keller and Salzer, 1967)

neutron diffraction data (Laval et al., 1987)

InU2F11

CoU2F10·5H2O

MnUF6·8H2O

ZnUF6·5H2O

CuU2F10·8H2O

LuUF7

YbUF7

TmUF7

YUF7

TlUO3F11

TlU6F25

Formula

Selected properties and physical constantsb

(Contd.)

hexagonal; a ¼ 8.18, c ¼ 16.46; d ¼ 7.19 monoclinic; Cs3 , Cm, No. 8; a ¼ 14.051(3), b ¼ 8.106(3), c ¼ 8.389 (2), b ¼ 90.00(3); Z ¼ 4; V ¼ 955.49; d(calc.) ¼ 7.95 monoclinic; a ¼ 8.19, b ¼ 8.27, c ¼ 11.17; b ¼ 92.66 monoclinic; a ¼ 8.19, b ¼ 8.27, c ¼ 11.19; b ¼ 92.73 monoclinic; a ¼ 8.18, b ¼ 8.25, c ¼ 11.20; b ¼ 92.70; d(calc.) ¼ 6.93 monoclinic; a ¼ 8.17, b ¼ 8.24, c ¼ 11.18; b ¼ 92.48 orthorhombic; a ¼ 8.73, b ¼ 7.16, c ¼ 20.78, Z ¼ 4, d(calc.) ¼ 4.48. orthorhombic; a ¼ 14.34, b ¼ 15.72, c ¼ 8.05; Z ¼ 8; d(calc.) ¼ 3.71 monoclinic; a ¼ 12.37, b ¼ 6.98, c ¼ 8.06; b ¼ 93.33; Z ¼ 4; d(calc.) ¼ 4.41 monoclinic; a ¼ 11.07, b ¼ 7.10, c ¼ 8.81; b ¼ 94.17; Z ¼ 2; d(calc.) ¼ 4.16 monoclinic; a ¼ 5.430, b ¼ 6.407, c ¼ 8.402, b ¼ 104.62(4)

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm–3)c

Table 5.26

crystallographic data (Champarnaud‐Mesjard and Gaudreau, 1976)

crystallographic data (Charpin et al., 1968)

crystallographic data (Charpin et al., 1969)

crystallographic data; magnetic properties (Denes et al., 1973) crystallographic data; magnetic properties (Denes et al., 1973) crystallographic data; magnetic properties (Denes et al., 1973) crystallographic data; magnetic properties (Denes et al., 1973) crystallographic data (Charpin et al., 1968) crystallographic data (Charpin et al., 1969)

crystallographic data (Avignant et al., 1977) crystallographic data (Hsini et al., 1986)

Remarks regarding information available and references

UCl4

UOF2·H2O

UO2F0.25

UOF2

NiU2F10·8H2O

light green needles or dark‐green octahedra; m.p. ¼ 590 C; b.p. ¼ 789 C; density: 4.725 g cm–3; meff. ¼ 3.29 B.M.; y ¼ –65 K (90 – 551 K)d hygroscopic; soluble in polar organic solvents; insoluble in ethyl acetate, chloroform and benzene. UCl4(cr): Df Gom ¼ –929.6 (2.5){, Df Hmo ¼ –1018.8 (2.5){, o o ¼ 197.200(0.8){; Cp;m ¼ 121.8 Sm (0.4){. UCl4(g): Df Gom ¼ –789.4 (4.9){, Df Hmo ¼ –815.4 (4.7){, o o ¼ 409.3 (5.0){; Cp;m ¼ 103.5 Sm { (3. 0) log p (mmHg) ¼ –11350T–1 þ 23.21 – 3.02 logT (298–863 K) log p(mmHg) ¼ –9950 T–1 þ 28.96 – 5.53 logT (863–1062 K); IR and Raman vibrations(cm–1): 311 (R), 270 (R, IR), 240 (R, IR),

UOF2·H2O(cr): Df Gom ¼ –1674.5 (4.1){, Df Hmo ¼ –1802.0(3.3){, o ¼ 161.1(8.4){ Sm

UOF2(cr): Df Gom ¼ –1434.1 (6.4){, o ¼ 119.2 Df Hmo ¼ –1504.6 (6.3){, Sm {. (4.2) dark grey to black; mixed valence compound (UIV and UV); oxidation state 4.25

tetragonal; D19 4h , I41/amd, No.141; a ¼ 8.3018(4), c ¼ 7.4813(6), Z ¼ 4; d(calc.) ¼ 4.87; each uranium atom is bonded to eight chlorine atoms; the coordination polyhedron is a dodecahedron ( 42m); d(U–Cl) ¼ 2.889(1) and 2.644(2) (4 times each); Cl–U–Cl angles: 3.141(8) and 3.540(1). The Cl–Cl approaches are 3.141(8), 3.097(8) and 3.540(1); structure refined data: a ¼ 8.3018(4), b ¼ 8.3018(4), c ¼ 7.4813(6); V ¼ 515.61; d(calc.) ¼ 4.89

octahedral; fluorite type of structure; a ¼ 5.49; Z ¼ 4; d(exp.) ¼ 11.0. One anion per unit cell is occupying inter‐net places

monoclinic; a ¼ 11.05, b ¼ 7.08, c ¼ 8.86; b ¼ 93.33; Z ¼ 2; d(calc.) ¼ 4.17

IR spectra (Jacob and Bacher, 1980); thermodynamic properties, (Grenthe et al., 1992; Guillaumont et al., 2003) crystallograhic data (Brown, 1979; Taylor and Wilson, 1973a); structural transitions anticipating melting (Bros et al., 1987); structure refinement (Schleid et al., 1987) temperature absorption spectra, crystal‐field energy level structure (Malek et al., 1986a,b); Brown, 1979; Hecht and Gruber, 1974; Clifton et al., 1969; ˙ ołnierek McLaughlin, 1962; Z et al., 1984; thermodynamic data (Rand and Kubaschewski, 1963 ; Grenthe et al., 1992; Brown, 1979; Guillaumont et al., 2003); magnetic properties (Hendricks et al., 1971; Dawson, 1951; Gamp et al., 1983); electrical and optical properties (Brown, 1979); IR and

thermodynamic data (Grenthe et al., 1992; Guillaumont et al., 2003) (Kemmler‐Sack, 1967, 1969)

crystallographic data (Charpin et al., 1968)

Li2UCl6

UCl4(CH3CN)4

Formula

m.p. ¼ 448.8 oC ; IR (cm–1): n(U–Cl) ¼ 232w, 258, 287w

172 (R), 153 (R, IR), and 102(R, IR); meff. ¼ 3.29; y ¼ –62 K Energy level parameters: F2 ¼ 42561(235), F4 ¼ 39440(634), and F6 ¼ 24174(185); z5f ¼ 1805 (8), a ¼ 30.9(1), b ¼ –576(168); B20 ¼ –903(151), B40 ¼ 766(220), B44 ¼ –3091(185), B60 ¼ –1619(482) and B64 ¼ –308(280). F2 ¼ 172.6, F4 ¼ 38.79, F6 ¼ 2.565; M0 ¼ [0.99], M2 ¼ [0.55] and M4 ¼ [0.38]; P2 ¼ P4 ¼ P6 ¼ [500] grey‐green cryst; soluble in CH3CN; loses CH3CN in vacuo >40 C; IR (cm–1): n(CN) ¼ 2278; meff. ¼ 2.89 B.M.; y ¼ –158 K

Selected properties and physical constantsb

(Contd.)

6 , C2/c, No.15; a ¼ monoclinic; C2h 14.677(4); b ¼ 8.452(2); c ¼ 13.9559(3); b ¼ 91.77(2); Z ¼ 4; d(calc.) ¼ 2.087; d(U–Cl) ¼ 2.624 (2) and 2.614(2); d(U–N) ¼ 2.599 (6) and 2.567(6). The U atom is eight‐coordinated with a dodecahedral arrangement. The C atoms occupy the dodecahedral B sites and the N atoms the A site hexagonal; D46h , P63/mmc, No. 194; a ¼ 11.191(5), b ¼ 11.191(5), c ¼ 6.0365(1); Z ¼ 3; V ¼ 654.72; d(calc.) ¼ 3.53

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm–3)c

Table 5.26

crystal structure from multiphase powder neutron profile refinement (Bendall et al., 1983); magnetic properties (Trzebiatowski and Mulak, 1970); thermodynamic data Vdovenko et al., 1974b; Fuger et al., 1983)

crystallographic data (Cotton et al., 1984; Van den Bossche et al., 1986); infrared data (Kumar and Tuck, 1984)

Raman spectra (Bohres et al., 1974); photoelectron spectra (Thibaut et al., 1982)

Remarks regarding information available and references

Cs2U[O3Cl9(Nb Cl)6]

crystal structure (Cordier et al., 1997)

crystallographic data (Vdovenko et al., 1972b); structure refinement (Schleid et al., 1987) IR and Raman data (Shamir and Silberstein, 1975; Shamir et al., 1975)

trigonal; a ¼ 7.50, c ¼ 12.00; d(calc.) ¼ 4.04; (for a rapidly quenched sample); for the refined structure: trigonal/rhombohedral; D33d ,P 3m1; No.164; a ¼ 7.5037(3), b ¼ 7.5037(3), c ¼ 6.0540(4); Z ¼ 1; V ¼ 295.21; 95.21 trigonal/rhombohedral; D23d , P 31c, No.163; a ¼ 9.2080(7), c ¼ 17.0950(30); Z ¼ 2; V ¼ 1255.25; d(calc.) ¼ 4.34

b‐Cs2UCl6

green crystals; m.p. ¼ 670 C; IR and Raman data (cm–1): n1 ¼ 307, n3 ¼ 262, n4 ¼ 115, n5 ¼ 125, n6 ¼ 88; Energy level parameters (Td): F2 ¼ 189.358, F4 ¼ 33.469, F6 ¼ 3.927, F2 ¼ 42605, F 4 ¼ 36447, F6 ¼ 28909; ς5f ¼ 1800.104; Ao4 hr4 i ¼ 901.381 Ao6 hr6 i ¼ 85.426; B40 ¼ 7211.0, B44 ¼ (4309) B60 ¼ 1366.8 B64 ¼ (–2554); rms ¼ 163; n ¼ 21 appears in a polymorphic transition at 510 C; IR and Raman data: n1 ¼ 308, n2 ¼ 230, n3 ¼ 267, n4 ¼ 116, n5 ¼ 126, n6 ¼ 89

 No.166; a ¼ trigonal; D53d , R3m, 7.34, c ¼ 5.89; d(calc.) ¼ 3.68; each U atom is surrounded by six Cl atoms at the vertices of an octahedron 3m, No 166; a ¼ trigonal; D53d , R 7.478, c ¼ 6.026; each U atom is surrounded by six Cl atoms at the vertices of an octahedron

IR (cm–1):n(U–Cl) ¼ 267; 285w

Rb2UCl6

a‐Cs2UCl6

crystal structure from multiphase powder neutron profile refinement (Bendall et al., 1983); magnetic properties (Trzebiatowski and Mulak, 1970); thermodynamic data Vdovenko et al., 1974b; Fuger et al., 1983) crystallographic data (Vdovenko et al., 1972a); magnetic properties (Trzebiatowski and Mulak, 1970); thermodynamic data (Vdovenko et al., 1974b; Fuger et al., 1983) crystallographic data (Siegel, 1956); IR and Raman data (Brown et al., 1975; Brown, 1979); crystal‐field spectra (Johnston et al., 1966); magnetic properties (Trzebiatowski and Mulak, 1970); thermodynamic data Vdovenko et al., 1974b; Fuger et al., 1983)

trigonal/rhombohedral; D33d ,  P3m1, No.164; a ¼ 11.8062(9), b ¼ 11.8062(9), c ¼ 6.3243(2); Z ¼ 3; V ¼ 763.42; d(calc.) ¼ 3.24

m.p. ¼ 445.6 oC; IR (cm–1): n(U–Cl) ¼ 240w, 260, 286w

Na2UCl6

UCl(PO4)2H2O

UCl(H2PO2)3(H2O)2

[P(C6H5)3C2H5]2UCl6

[N(C2H5)4]2UCl6

[N(CH3)4]2UCl6

Formula green cryst.; soluble in CH3CN, H2O; IR and Raman data (cm–1): n1 ¼ 284, n2 ¼ 230, n5 ¼ 123, n6 ¼ 87 green cryst.; soluble in CH3CN, H2O; crystals undergo reversible phase change at 94 C; IR and Raman data (cm–1): n1 ¼ 293, n3 ¼ 254, n4 ¼ 110, n5 ¼ 110, n6 ¼ 78; F2 ¼ 43170(2181), ς5f ¼ 1774(35); B40 ¼ 7463(432), B60 ¼ 992(258); rms ¼ 168

Selected properties and physical constantsb

(Contd.)

crystallographic data (Benard‐ Rocherulle et al., 1997)

synthesis, structure, vibrational spectra (Tanner et al., 1992)

crystallographic data (Caira et al., 1978)

triclinic; C11 , P 1, No.2; a ¼ 10.53 (1), b ¼ 10.95(1), c ¼ 10.31(1); a ¼ 113.22(5)o, b ¼ 105.20(5), g ¼ 80.40(5); Z ¼ 1; d(calc.) ¼ 1.631, d(exp.) ¼ 1.64; d(U‐Cl): ¼ 2.621 (2), 2.627(1) and 2.623(1) orthorhombic; D11 2h , Pbcm, No.57; a ¼ 7.559(2), b ¼ 10.111(2), c ¼ 14.680(2); Z ¼ 4; V ¼ 1121.98, d(calc.) ¼ 2.99 5 tetragonal; C4h , I4/m, No.87; a ¼ 14.631(2), b ¼ 14.631(2), c ¼ 6.662 (1); Z ¼ 8; V ¼ 1426.11; d(calc.) ¼ 3.77

orthorhombic; D23 2h , Fmmm, No.69; a ¼ 14.23, b ¼ 14.73, c ¼ 13.33; d(calc.) ¼ 1.693

crystallographic data (Staritzky and Singer, 1952); IR and Raman data (Silberstein, 1972; Brown, 1979) crystallographic data (Staritzky and Singer, 1952); IR and Raman data (Brown et al., 1975; Brown, 1979); electronic spectra, crystal‐ field parameters (Wagner et al., 1977)

Remarks regarding information available and references

cubic face centered; a ¼ 13.06; d(calc.) ¼ 1.788, d(exp.) ¼ 1.791

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm–3)c

Table 5.26

UNCl

other uranium(IV) chloro complexes: (i) KUCl5; (ii) RbUCl5; (iii) CsUCl5, (iv) K2UCl6; (v) Cs2UCl6 (vi) Ag2UCl6; (vii) KNaUCl6; (viii) SrUCl6; (ix) BaUCl6; (x) Rb4UCl8; (xi) KU3Cl13; (xii) KNaUCl6; (xiii) CsU2Cl9; (xiv) Cs3U2Cl11 UOCl2 green; moisture sensitive; insoluble in organic solvents; soluble in H2O; b.p.>400 C; UOCl2(cr): Df Gom ¼ –998.5 (2.7){, o ¼ Df Hmo ¼ –1069.3 (2.7){, Sm o ¼ 95.06 138.32 (0.21){; Cp;m (0.42){; paramagnetic meff. ¼ 3.13 B.M. (above 40 K); exhibits magnetic ordering below 31 K

(i) m.p. ¼ 345 C* (ii) m.p. ¼ 360 C* (iii) (iv) IR (cm–1):n(U–Cl) ¼ 250w, 263, 286w (v) green cryst.; m.p. 670 C o ¼ 35.4 (vi) m.p. ¼ 407 C; DHfus (2.1) (vii) (viii) m.p. ¼ 560 C (ix) m.p. ¼ 382 C* (x) m.p. ¼ 406.3 C (xi) (xii) (xiii) orthorhombic; D92h , Pbam, No.55; a ¼ 15.255, b ¼ 17.828, c ¼ 3.992; d(U(1)–O) ¼ 2.20–2.40; d(U(1)– Cl) ¼ 2.66–3.15; d(U(2)–O) ¼ 2.17–2.33; d(U(2)–Cl) ¼ 2.88– 3.01; d(U(3)–O) ¼ 2.22–2.35; d(U(3)–Cl) ¼ 2.70–3.51; the arrangement around U(1) is dodecahedral (CN ¼ 8; 3O, 5Cl); that around U(2) is trigonal (CN ¼ 7; 3O, 4Cl) and that around U (3) is approx. dodecahedral‐1 (C.N. ¼ 7; 3O, 4Cl) tetragonal; D74h , P4/nmm, No.129; a ¼ 3.979, c ¼ 6.811; Z ¼ 2; V ¼ 107.83; d(calc.) ¼ 8.85; d(exp) ¼ 8.78. The compound is isostructural with PbFCl;

crystallographic data (Juza and Sievers, 1965; Juza and Meyer, 1969; Yoshihara et al., 1971)

crystallographic data, neutron diffraction data (Bagnall et al., 1968; Taylor and Wilson, 1974a); infrared spectra (Bagnall et al., 1968) thermodynamic data (Brown, 1979; Grenthe et al., 1992;Guillaumont et al., 2003); magnetic properties, ir spectra (Levet.and Noe¨l, 1979); photoelectron spectra (Thibaut et al., 1982)

thermodynamic and IR data (Brown, 1979; Suglobova and Chirkst, 1978a, Vdovenko et al., 1974b; Fuger et al., 1983); magnetic properties (Brown, 1979)

UBr4

other chloride fluorides: (i) UCl2F2, (ii) UCl3F.

UClF3

Formula

emerald green cryst.; m.p. ¼ 444 C*; b.p. ¼ 550–650 C (in vacuo subl.) UClF3(cr): Df Gom ¼ –1606 (5.){, Df Hmo ¼ –1690 (5){, o o ¼ 185.4 (4.2){; Cp;m ¼ 120.9 Sm (4.2){ (i) green; m.p. ¼ 460 C*. UCl2F2(cr): Df Gom ¼ –1376(6){, o ¼ 174.1 Df Hmo ¼ –1466 (5){, Sm { o (8.4) ; Cp;m ¼ 119.7 (4.2){. (ii) m.p. ¼ 530 C*; UCl3F(cr): Df Gom ¼ –1147(5){, Df Hmo ¼ –1243 o ¼ 162.8 (4.2){; (5){, Sm o Cp;m ¼ 118.8(4.2){ brown to black‐brown cryst; moisture sensitive; soluble in Me2CO, EtOH; m.p. ¼ 519 C; b.p. ¼ 777 C; sublimes in a Br2‐N2 stream. meff. ¼ 3.12 B.M; y ¼ –35 K; (77–569 K)d . UBr4(cr): Df Gom ¼ –767.4 (3.5){, Df Hmo ¼ o ¼ 238.5 (8.4){; –802.1 (2.5){, Sm o ¼ 128.0 (4.2){. UBr4(g): Cp;m Df Gom ¼ –634.6 (5.0){, Df Hmo ¼

Selected properties and physical constantsb

(Contd.)

3 monoclinic; C2h , C2/m, No.12; a ¼ 10.92(2), b ¼ 8.69(3), c ¼ 7.05(1); b ¼ 93.9(1); Z ¼ 4; d(calc.) ¼ 5.55, d(exp.) ¼ 5.35. The Br anions form a pentagonal bipyramid around the U atom. The bipyramids are linked into two‐ dimensional sheets by double bromide bridging of the U cations. d(U–Br) ¼ 2.85(2) to 2.95(2)

d(U–Cl1) ¼ 3.17 (4); d(U–N) ¼ 2.30; d(Cl1–Cl1) ¼ 3.98; d(Cl1–Cl2) ¼ 3.23; d(N–Cl) ¼ 3.29; d(N–N) ¼ 2.81 17 orthorhombic; Abam or C2v , Aba2, No.41; a ¼ 8.673(2), b ¼ 8.69(1), c ¼ 8.663(5); Z ¼ 8; d(calc.) ¼ 6.72

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm–3)c

Table 5.26

synthesis (Brauer, 1981) crystallographic data (Douglass and Staritzky, 1957; Taylor and Wilson, 1974d,e; Levy et al., 1975; Korba, 1983); thermodynamic data; (Grenthe et al., 1992; Guillaumont et al., 2003); magnetic data (Dawson, 1951; Hendricks, 1971); photoelectron spectra (Thibaut et al., 1982)

crystallographic data (Savage, 1956; Staritzky and Douglass, 1956); thermodynamic data; fused salt system (Brown, 1979; Grenthe et al., 1992; Guillaumont et al., 2003) thermodynamic data; fused salt system (Brown, 1979; Grenthe et al., 1992; Guillaumont et al., 2003)

Remarks regarding information available and references

K2UBr6

Na2UBr6

Li2UBr6

[UBr(H2O)8]Br3(H2O)

m.p. ¼ 672 C; n(U–Br)as. ¼ 185, 208w

m.p. ¼ 533 C; n(U–Br)as. ¼ 164w, 180, 202w

o –605.6 (4.7){, Sm ¼ 451.9 (5.0){; o ¼ 106.9 (3.0){. logp Cp;m (mmHg) ¼ –10800 T–1 þ23.15– 3.02 logT (298–792 K) log p (mmHg) ¼ –8770 T–1 þ 27.93 – 5.53 logT (792–1050 K); Energy level parameters: F2 ¼ 191, F4 ¼ 34, F6 ¼ 4, z5f ¼ 1976, A(r4) ¼ – 490 and A(r6) ¼ –15 (in cm–1); nU–Br ¼ 233 cm–1 (vapor)

trigonal; a ¼ 10.94, c ¼ 10.67; d(calc.) ¼ 4.11, d(exp.) ¼ 4.12

triclinic; Ci1 , P 1, No.2; a ¼ 8.234 (4), b ¼ 12.781(7), c ¼ 7.168(2), a ¼ 97.76(3), b ¼ 98.36(2) g ¼ 85.38(4); Z ¼ 2; V ¼ 738.07; d(calc.) ¼ 3.24 trigonal/rhombohedral; D23d , P 31c; No ¼ 163; a ¼ 6.8896(4), c ¼ 12.6465(9); g ¼ 120; Z ¼ 2; V ¼ 519.86 trigonal/rhombohedral; D33d , P 3m1; No. ¼ 164; a ¼ 12.4368(1), c ¼ 6.6653(2); V ¼ 892.83; Z ¼ 3

(in the pentagonal ring) and 2.78 (3) and 2.61(4) (to the apical bromides); the axial Br–U–Br angle ¼ 177(1)o

crystallographic data (Vdovenko et al., 1973b; Bogacz et al., 1980); thermodynamic data (Vdovenko et al., 1973a, 1974c; Fuger et al., 1983); Visible and, IR data (Brown, 1979; Suglobova and Chirkst, 1978) crystallographic data (Vdovenko et al., 1973b); thermodynamic data (Vdovenko et al., 1973a, 1974c; Fuger et al., 1983); Visible and IR data (Suglobova and Chirkst, 1978a; Brown, 1979)

crystallographic data; phase transitions by neutron diffraction (Maletka et al., 1998)

crystallographic data (Rabinovich et al., 1998)

(Contd.)

m.p. ¼ 756 C; vibrational modes (cm–1): n1(R) ¼ 197, n2(R) ¼ (155), n3(IR) ¼ 195, n4 ¼ (IR) ¼ 84, n5(R) ¼ 87, L ¼ 5; F2 ¼ 84.112, F4 ¼ 35.542, F6 ¼ 3.818, z5f ¼ 1792.306, B40 ¼ 6593, B60 ¼ 1195

Rb2UBr6

vibrational modes (cm–1): n3(IR) ¼ 181; n(U–Br) ¼ 190–195 IR (cm–1): n(U–Br) ¼ 178; energy level parameters: F2 ¼ 181.63(12) (or F2 ¼ 40867), z5f ¼ 1756(41), B40 ¼ 6946(609), B60 ¼ 999(252); rms ¼ 176

[N(CH3)4]2UBr6

[N(C2H5)4]2UBr6

UNBr

tetragonal; D74h , P4/nmm, No.129; a ¼ 3.944, c ¼ 7.950; Z ¼ 2; d(calc.) ¼ 8.913; d(exp.) ¼ 8.64; The compound is isostructural with BiOCl; d(U–Br) ¼ 3.234; d(U–N) ¼ 2.280 cubic face centered; O5h , Fm 3m, No.225; a ¼ 13.37; d(calc.) ¼ 2.405

 cubic face centered; O5h , Fm3m, No.225; a ¼ 11.07; V ¼ 1356.57. The U atoms are surrounded by an octahedral array of Br atoms at distances of 2.767; d(Br–Br) ¼ 3.914; d(calc.) ¼ 4.78, d(exp.) ¼ 4.74

m.p. ¼ 722 C*; n(U–Br)as. ¼ 192

Formula

Cs2UBr6

cubic face centered; O5h , Fm 3m, No.225; a ¼ 10.94; V ¼ 1309.34. The U atoms are surrounded by an octahedral array of Br atoms at distances of 2.74; d(calc.) ¼ 4.48, d(exp.) ¼ 4.048

Selected properties and physical constantsb

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm–3)c

Table 5.26

IR and energy level analyses (Brown, 1966; Wagner et al., 1977)

crystallographic data (Brown, 1966)

crystallographic data (Vdovenko et al., 1973a; Maletka et al., 1996b); thermodynamic data (Vdovenko et al., 1973a, 1974c; Fuger et al., 1983); visible‐near IR data (Suglobova and Chirkst, 1978a; Brown, 1979) crystallographic data, (Vdovenko et al., 1973a); thermodynamic data (Vdovenko et al., 1973a, 1974c; Fuger et al., 1983); visible and IR spectral data (Johnston et al., 1966; Chodos, 1972; Suglobova and Chirkst, 1978a; Brown, 1979); crystal‐field analysis (Johnston et al., 1966) crystallographic data; (Juza and Meyer, 1969)

Remarks regarding information available and references

UBr3Cl

UBr2Cl2

UBrCl3

UBr(PO4)(H2O)2

UBr(PO2H2)3·2H2O

[P(C6H5)4]2[UBr6]· 4CH3CN

[P(C6H5)3C2H5]2UBr6

greenish brown; hygroscopic; m.p. ¼ 521 C; b.p. ¼ 784 C; UBrCl3(cr): Df Gom ¼ –893.5 (9.2){, o ¼ 213.4 Df Hmo ¼ –967.3 (8.4){, Sm (12.6){ dark green; hygroscopic; m.p. ¼ 510 C; b.p. ¼ 1053 oC; UBr2Cl2 (cr): Df Gom ¼ –850.9 (9.8){, o ¼ 234.3 Df Hmo ¼ –907.9 (8.4){, Sm (16.7){ greenish brown; hygroscopic; m.p. ¼ 502 C; b.p. ¼ 774 C UBr3Cl(cr): Df Gom ¼ –807.1 (9.8){, o ¼ 238.5 Df Hmo ¼ –852.3 (8.4){, Sm (16.7){

green crystals; extremely sensitive towards oxygen and moisture

2 monoclinic; C2h , P21/m, No.11; a ¼ 10.45(1), b ¼ 13.51(1), c ¼ 15.46(1); b ¼ 96.67(5); Z ¼ 2; d(calc.) ¼ 1.990, d(exp). ¼ 1.96; d(U–Br): ¼ 2.757(2), 2.776 (2) and 2.777(2) 5 monoclinic; C2h , P21/c, No.14; a ¼ 9.818(3), b ¼ 20.101(4), c ¼ 15.493 (3), b ¼ 98.79(2); Z ¼ 2; V ¼ 3022; d(calc.) ¼ 1.72; d(U–Br1) ¼ 2.754 (1); d(U–Br2) ¼ 2.778(1); d(U–Br3) or O ¼ 2.768(1); Br(1)–U–Br(2) ¼ 89.2(1); Br(1)– U–Br(3) (or O) ¼ 90.4(1); Br(2)– U–Br(3) (or O) ¼ 89.6(1). orthorhombic; D11 2h , Pbcm, No. 57; a ¼ 7.488(5), b ¼ 10.192(2), c ¼ 15.203(5); Z ¼ 2; V ¼ 1160.26. 5 tetragonal; C4h , I4/m, No.87; a ¼ 14.7480(7), c ¼ 6.6810(4) ; V ¼ 1453.14; Z ¼ 8; d(calc.) ¼ 4.1. tetragonal; a ¼ 8.434, c ¼ 7.690

thermodynamic data (MacWood, 1958; Brown, 1979; Grenthe et al., 1992; Guillaumont et al., 2003)

thermodynamic data (MacWood, 1958; Brown, 1979; Grenthe et al., 1992; Guillaumont et al., 2003)

thermodynamic data (MacWood, 1958; Brown, 1979; Grenthe et al., 1992; Guillaumont et al., 2003)

X‐ray crystallographic and spectroscopic structural studies (Tanner et al., 1993) crystallographic data (Benard‐ Rocherulle et al., 1997)

synthesis and crystallographic data (Bohrer et al., 1988)

crystallographic data (Caira et al., 1978)

Li2UI6

UI4

UOBr2

Formula

black lustrous crystals; moisture sensitive; m.p. ¼ 506 C; density: 5.6 g cm–3; m.p. ¼ 506 C; b.p. ¼ 757 C; meff. ¼ 2.98 B.M; (1–300 K)d . UI4(cr): Df Gom ¼ –512.7 (3.8){, Df Hmo ¼ –518.3 (2.8){, o o ¼ 263.6 (8.4){; Cp;m ¼ 126.4 Sm (4.2){. UI4(g): Df Gom ¼ –369.6 (6.2){, Df Hmo ¼ –305.0 (5.7){, o o ¼ 499.1 (8.0){; Cp;m ¼ 108.8 Sm (4.0){. log p (mmHg) ¼ –12330 T–1 þ 26.62 – 3.52 logT (298–779 K), log p (mmHg) ¼ –9310 T–1 þ 28.57 – 5.53 logT (779–1030 K): IR data (cm–1): 178m, 165s, 132,s, 122m, 104vw, 92m, 55m

greenish yellow: UOBr2(cr): Df Gom ¼ –929.6 (8.4){, Df Hmo ¼ –973.6 o o ¼ 157.57 (0.29){; Cp;m ¼ (8.4){, Sm 98.0 (0.4){

Selected properties and physical constantsb

(Contd.)

trigonal/rhombohedral; D23d , P 31c, No. ¼ 163; a ¼ 7.3927(8), c ¼ 13.826(2); V ¼ 654.39; Z ¼ 2; d(U–I) ¼ 3.013

6 , C2/c, No. 15; a ¼ monoclinic; C2h 13.967(6), b ¼ 8.472(4), c ¼ 7.510 (3); b ¼ 90.54(5); Z ¼ 4; V ¼ 888.7; d(calc.) ¼ 5.57. Close‐ packed hexagonal iodine atoms form zigzag chains of edge‐sharing octahedra (UI2I4/2). d(U–I(1) bridging) ¼ 3.08(2) and 3.11(2); d(U‐I(2) terminal) ¼ 2.92(2)(2); d(U—U) ¼ 4.55

Lattice symmetry, lattice constants ˚ ), conformation and density (A (g cm–3)c

Table 5.26

neutron diffraction and electrical conductivity data (Maletka et al., 1996a)

thermodynamic data (Greenberg and Westrum, 1956; Rand and Kubaschewski, 1963; Brown, 1979; Grenthe et al., 1992; Guillaumont et al., 2003); photoelectron spectra (Thibaut et al., 1982) crystallographic and neutron diffraction data (Levy et al., 1980, Taylor, 1987); thermodynamic data; (Fuger and Brown, 1973; Brown, 1979; Guillaumont et al., 2003)

Remarks regarding information available and references

UNI

UOI2

M2UI6 (M ¼ N (C2H5)4, N(C4H9)4, N(C6H5)(CH3)3, As (C6H5)4).

BaUI6

EuUI6

Na2UI6

red; extremely moisture sensitive; soluble in anhydrous methyl cyanide and acetone; vibrational mode in (cm–1)UI62 : n1 ¼ 143 to 156; n2 ¼ 119, n3 ¼ 135 to 143; n4 ¼ 60 to 65, n5 ¼ 62 to 66; n6 ¼ 44 to 47; energy level parameters for [N(C2H5)4]2UI6: F2 ¼ 38188 (2422), z5f ¼ 1724(39), B40 ¼ 6338(676), and B60 ¼ 941 (289) rose‐brown cryst; decomposes slowly at room temp; hygroscopic; soluble in H2O; U–O vibrations (cm–1): 520(w), 475(m), 420 (m), 280(w), and 250(sh); paramagnetic; meff. ¼ 3.34 B.M

crystallographic data; magnetic susceptibility data, infrared spectra (Levet and Noe¨l, 1979)

crystallographic data; (Juza and Meyer, 1969)

tetragonal; D74h , P4/nmm, No.129; a ¼ 3.990, c ¼ 9.206; Z ¼ 2;

electronic and IR spectra; crystal‐ field analysis; magnetic susceptibility data (Wagner et al., 1977; Brown, 1979)

X‐ray powder diffraction data (Beck and Kuehn, 1995)

X‐ray powder diffraction data (Beck and Kuehn, 1995)

crystallographic data (Maletka et al., 1992, 1995)

orthorhombic; D92h , Pbam, No.55; isostructural with UOCl2 (PaOCl2 struct. type); a ¼ 17.853(5), b ¼ 20.05(2), c ¼ 4.480(5)

trigonal/rhombohedral; C3i2 , R 3, No.148; a ¼ 7.7001(6), c ¼ 20.526; Z ¼ 3; V ¼ 1053.97; d(U–I) ¼ 2.992 monoclinic; Cs4 , Cc, No.9; a ¼ 8.006(4), b ¼ 12.998(5), c ¼ 15.194 (5); b ¼ 106.2(1); V ¼ 1518.34; Z ¼ 4; d(U–I) ¼ 3.035 to 3.218 monoclinic; Cs4 , Cc, No.9; a ¼ 8.845(5), b ¼ 13.834(7), c ¼ 15.753 (8); b ¼ 107.5(1); V ¼ 1838.35; Z ¼ 4; d(U–I) ¼ 3.164 to 3.241

(i) UF3I; (ii) UClI3; (iii) UCl2I2; (iv) UCl3I; (v) UBrI3; (vi) UBr2I2; (vii) UBr3I; (viii) UCl2BrI; (ix) UClBr2I.

Formula

(i) brownish black; (ii) black, m.p.j rij

k where F k(nl, nl), with k ¼ 0, 2, 4, 6, are the Slater radial integrals for the radial part of the electrostatic interaction, which is defined as: Z 1Z 1 k
  2 r< F k ðnl; nl Þ ¼ e2 ½Rnl ðri Þ 2 Rnl rj dri drj ð18:19Þ kþ1 0 0 r> The value of F k may be calculated using the Hartree–Fock method, but in analyses of actinide‐ion spectra, F k is considered as an experimentally determined parameter. The angular part of the matrix element in equation (18.18) is defined as



* +

X

N 0 0 0

ðkÞ ðkÞ N fk ðl; lÞ ¼ l tLS

C ðiÞ  C ðjÞ l t L S : ð18:20Þ

i>j

2028

Optical spectra and electronic structure

Using the Wigner–Eckart theorem, the matrix elements in equation (18.20) are best handled by introducing the tensor operator U(k). In combination with the symmetry properties of angular momentum, fk can be expressed in terms of the reduced matrix elements of U(k) as:  l k l 2 1 fk ðl; lÞ ¼ ð2l þ 1Þ2 2 0 0 0 ( ) ð18:21Þ

ðkÞ N 0 0 E

2 1 X

D N N

l tLS  :

l tLS U 2L þ 1 0 0 2l þ 1 tL

In the particular case of k ¼ 0, it is easy to find that f0 ðl; lÞ ¼ NðN  1Þ=2:

ð18:22Þ

For the dN and fN configurations, the values for the reduced matrix elements of tensor operator U(k) have been tabulated (Nielson and Koster, 1963). Because of the symmetry properties of the 3j symbol, fk(l,l) has nonzero values only if lþl k |ll|; and k is even. For f‐electrons, l ¼ 3, thus fk vanishes except for k ¼ 0, 2, 4, 6. As defined in equation (18.4), the Hamiltonian for spin–orbit coupling for N‐electrons in an actinide ion is a linear summation of the independent spin–orbit interaction for a single electron. In LS coupling, the N‐equivalent electronic matrix element of the spin–orbit interaction is expressible in terms of the tensor operator V(11). Hence the matrix element of spin–orbit interaction for N‐equivalent electrons can be expressed as N

X   N xðri Þl i  si nl N t0 L0 S0 J 0 ¼ znl Anl ðlsÞ; nl tLSJ

ð18:23Þ

i¼1

where znl is the spin–orbit interaction parameter defined as a radial integral Z 1 znl ¼ ½Rnl ðrÞ 2 xðrÞdr: ð18:24Þ 0

where Rnl(r) is the radial wave function. The spin–orbit parameter can be evaluated numerically using the Hartree– Fock central field potential, but it is usually adjusted to obtain the experimentally observed energies. The matrix element in equation (18.23) can be expressed as (Sobelman, 1972) 0 pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi Anl ðlsÞ ¼ ð1ÞLþS þJ ð2l þ 1Þðl þ 1Þl dJJ 0 dMM 0   ð18:25Þ

0 0 0E L S J D tLS Vð11Þ t L S ; 0 0 S L 1

Modeling of free‐ion interactions

2029

where f. . .g is a 6j symbol, and the values for the reduced matrix elements of the tensor operators V(11) have been tabulated by Slater (1960), Sobelman (1972), and Nielson and Koster (1963). The electrostatic and spin–orbit interactions usually give the right order for the energy level splitting of the fN configurations. However, these primary terms of the free‐ion Hamiltonian do not accurately reproduce the experimentally measured energy level structures. The reason is the parameters F k and znf, which are associated with interactions within a fN configuration, cannot absorb all the effects of additional mechanisms such as relativistic effects and configuration interactions. Introduction of new terms in the effective‐operator Hamiltonian is required to better interpret the experimental data. It was demonstrated (Judd and Crosswhite, 1984) that, in fitting the experimental free‐ion energy levels of Pr3þ ( f2 configuration), the standard deviation between observed and calculated f‐state energies could be reduced from 733 to 24 cm1 by adding nine more parameterized effective operators into the Hamiltonian. Among several corrective terms included in the effective‐operator Hamiltonian, a significant contribution to the fN energy level structure is from configuration interactions between configurations of the same parity. This contribution can be taken into account by a set of three two‐electron operators (Wybourne, 1965a): H

c1

¼ aLðL þ 1Þ þ bGðG2 Þ þ gGðR7 Þ

ð18:26Þ

where a, b, and g are the parameters associated with the continuous groups G(G2) and G(R7) (Rajnak and Wybourne, 1963, 1964) the latter being eigenvalues of Casimir operators for the groups G2 and R7 (Judd, 1963a). For fN configurations of N 3, three‐body interaction terms were introduced by Judd (1966) and Crosswhite et al. (1968) as X H c2 ¼ T i ti ð18:27Þ i¼2;3;4;6;7;8

where T i are parameters associated with three‐particle operators ti. This set of effective operators scaled with respect to the total spin S and total orbital angular momentum L are needed in the Hamiltonian to represent the coupling of the fN states to those in the higher energy configurations (d, p, s) via inter‐ electron Coulombic interactions. It is common to include six three‐electron operators ti ði ¼ 2; 3; 4; 6; 7; 8Þ. When perturbation theory is carried beyond the second order, an additional eight three‐electron operators ti (11  i  19, with i ¼ 13 excluded) are required (Judd and Lo, 1996). A complete table of matrix elements of the 14 three‐electron operators for the f‐shell have been published (Hansen et al., 1996). In addition to the magnetic spin–orbit interaction parameterized by znf, relativistic effects including spin–spin and spin–other–orbit, both being

Optical spectra and electronic structure

2030

parameterized by the Marvin integrals M0, M2, and M4 (Marvin, 1947), are included as the third corrective term of the effective‐operator Hamiltonian (Judd et al., 1968). X H c3 ¼ M i mi ; ð18:28Þ i¼0;2;4

where mi is the effective operator and Mi is the radial parameter associated with m i. As demonstrated (Judd et al., 1968; Carnall et al., 1983), for improving the parametric fitting of the f‐element spectra, two‐body effective operators can be introduced to account for configuration interaction through electrostatically correlated magnetic interactions. This effect can be characterized by introducing three more effective operators as X H c4 ¼ Pi pi ; ð18:29Þ i¼2;4;6 i

where pi is the operator and P is the radial parameter. In summary, 20 effective operators are utilized for fitting spectra, including those for two‐ and three‐electron interactions. The total effective‐operator Hamiltonian for free‐ion interactions is X H FI ¼ F k fk þ znl Anl þ aLðL þ 1Þ þ bGðG2 Þ þ gGðR7 Þ k¼0;2;4;6

X

þ

i¼2;3;4;6;7;8

T i ti þ

X

M i mi þ

i¼0;2;4

X

pi Pi :

ð18:30Þ

i¼2;4;6

This effective‐operator Hamiltonian has been used as the most comprehensive free‐ion Hamiltonian in previous spectroscopic analyses of f‐element ions in solids (Crosswhite, 1977; Crosswhite and Crosswhite, 1984; Carnall et al., 1989; Liu, 2000). The 20 parameters associated with the free‐ion operators are adjusted in the fitting of experimental energy levels. 18.3.4

Reduced matrices and free‐ion state representation

In equation (18.30), all effective operators for the free‐ion interactions have well‐defined group‐theoretical properties (Judd, 1963b; Wybourne, 1965a). Within the intermediate coupling scheme, all matrix elements can be reduced, using the Wigner–Eckart theorem, to new forms that are independent of J, viz. htSLJ jH i jt0 S0 L0 J 0 i ¼ Pi dJJ 0 cðSLS 0 L0 J ÞhtSLkOi kt0 S 0 L0 i; 0

0

ð18:31Þ

where Pi is the parameter, cðSLS L J Þ is a numerical coefficient, and htSLkOi kt0 S 0 L0 i is the reduced matrix element of the effective‐operator Oi. Once the reduced matrix elements are calculated, it is not difficult to diagonalize the entire free‐ion Hamiltonian with the wave functions in the LS basis set. The free‐ion eigenfunctions are thus obtained in the form of the intermediate

Modeling of free‐ion interactions

2031

coupling representation. All matrix elements of the effective‐operator Hamiltonian are evaluated in terms of the parameters of the effective operators. Because the reduced matrix elements are independent of J, the matrix of the free‐ion Hamiltonian thus can be reduced into a maximum of 13 independent submatrices for J ¼ 0; 1; 2; . . . ; 12 for even N and J ¼ 12 ; 32 ; 52 ; . . . ; 25 2 for odd N in an fN configuration. The number of submatrices and their size can be determined from the values of NJ (the number of J levels for a given SL multiplet) given in Table 18.3. Separation of the free‐ion matrix into submatrices greatly facilitates the evaluation of free‐ion energy levels. However, evaluation of matrix elements is still a considerable effort, particularly with inclusion of the corrective terms in the Hamiltonian. For an fN configuration with 3 < N < 11, there are more than 104 free‐ion matrix elements and each of them may have as many as 20 terms to be evaluated on the basis of angular momentum operations. Fortunately, several groups have calculated the matrix elements that are available on web sites (http://chemistry.anl.gov) from which one may download a MS‐Windows based computer program named SPECTRA to calculate the eigenvalues and eigenfunctions of the free‐ion Hamiltonian defined in equation (18.30). As discussed in the following sections, SPECTRA can also be used for nonlinear least‐squares fitting of observed levels to determine values of the Hamiltonian parameters. Due to the SLS 0 L0 mixing in the intermediate coupling scheme, labeling a multiplet as 2Sþ1LJ is incomplete. In most cases, the nominal labeling of a free‐ ion state as 2Sþ1LJ only indicates that this multiplet has a leading component from the pure LS basis jLSJ i. Diagonalization of each of the submatrices produces free‐ion eigenfunctions in the form of equation (18.15). As an example, the leading LS terms for the free‐ion wave functions of the nominal 4I9/2 ground state of the 4f3 ion Nd3þ and the 5f3 ion U3þare: Cð4f 3 ; 4 I9=2 Þ ¼ 0:984 4 I  0:174 2 H  0:0172 G þ etc: Cð5f 3 ; 2 I9=2 Þ ¼ 0:912 4 I  0:391 2 H  0:081 2 G þ 0:048 4 G þ 0:032 4 F þ etc: In general, SLS0 L0 mixing becomes more significant in the excited multiplets. 18.3.5

Parameterization of the free‐ion Hamiltonian

In an empirical approach to interpretation of the experimentally observed energy level structure of an f‐element ion in solids, establishing accurate parameters for the model Hamiltonian essentially relies on systematic analyses that encompass theoretical calculations for incorporating trends of parameter variation across the f‐element series. In the previous work that led to the establishment of the free‐ion parameters for the trivalent actinide ions (Carnall, 1992) and the tetravalent actinide ions (Carnall et al., 1991; Liu et al., 1994b), the results of analyses of simpler spectra were carried over to more complex ones through consideration of their systematic trends and symmetry properties.

2032

Optical spectra and electronic structure

Table 18.4 lists values of the free‐ion interaction parameters obtained from analyses of the spectra of An3þ:LaCl3. In early attempts to develop a systematic interpretation of trivalent actinide and lanthanide spectra, initial sets of F k and znf for some members of the series had to be estimated. This was done by a linear extrapolation based on the fitted parameters that were available from the analyses of other individual spectra. As more extensive data and improved modeling yielded better determined and more consistent F k and znf values for the 3þ actinides (and lanthanides), it became apparent that the variation in the parameters was nonlinear, as indicated for F2(5f,5f) in Fig. 18.4. This nonlinearity could also be observed in the values of parameters of the ab initio calculations. The difference between the ab initio and fitted values of parameters (DF) appears to exhibit a much more linear variation with Z than do the parameter values. Consequently, DF has been adopted as the basis for a useful predictive model. For the trivalent actinides, the values of DF are not constant over the series, but use of a single average value over a group of four or five elements is not an unreasonable approximation. Thus, in developing a predictive model for the F k and znf parameters, an attempt is made to establish average values of DF for a particular valence state and type of crystal‐field interaction. The energy level structure computation based on the predicted parameters can be compared to that observed, and then appropriate modifications sought by a fitting procedure where necessary. Detailed results of Hartree–Fock calculations on f‐electrons were previously analyzed (Carnall et al., 1983; Crosswhite and Crosswhite, 1984). The most important trends are those of the electrostatic‐interaction parameters F k and spin–orbit parameters znf which increase with the number of f‐electrons, N. The experimentally determined values of F k and znf for trivalent actinides in LaCl3 are shown as a function of N in Figs. 18.4 and 18.5, respectively. These values were obtained from the systematic analyses of experimental spectra (Carnall, 1992). Fig. 18.5 also shows the systematic trends for znf for the trivalent actinide ions that were obtained from Hartree–Fock calculations. Although the Hartree–Fock calculations predict the same trends across the series, the Hartree–Fock values for F k and znf are always larger than the empirical parameters obtained by allowing them to vary in fitting experimental data. The relativistic Hartree–Fock (HFR) values of znf agree remarkably well with empirical values, whereas the F k values remain considerably larger than the empirical values. Presumably, this is because, in addition to relativistic effects, f‐electron coupling with orbitals of higher‐lying energies reduces the radial integrals assumed in the HFR approximation. Moreover, the experimental results are obtained for ions in condensed phases, not in a gaseous phase, which leads on average to an ~5% change (Crosswhite, 1977). Because of the absence of mechanisms that absorb these effects in the HFR model, HFR values of F ks cannot be used directly as initial parameters for the least‐squares fitting process. Scaling of HFR values to the experimentally determined ones is

39 611(222) 32 960(418) 23 084(352) 1626(3) 29.26(0.44) –824.6(29) 1093(105) 306(64) 42(14) 188(20) –242(40) 447(61) [300] [0.672] [0.372] [0.258] 1 216(77) 287(32) –662(93) –1 340(89) 1070(63) 29 82

45 382(80) 37 242(215) 25 644(196) 1937(2) 31.78(0.30) –728.0(18) 840.2(61) [200] 45(7) 50(6) –361(18) 427(23) 340(17) [0.773] [0.428] [0.297] 1009(30) 164(26) –559(44) –1 673(49) 1033(34) 22 167

Np3þ 48 679(89) [39 333 R] 27 647(89) 2242(2) 30.00(0.16) –678.3(12) 1022(31) 190(8) 54(10) [45] –368(19) 363(14) 322(10) [0.877] [0.486] [0.388] 949(24) 197(22) –586(38) –1723(39) 1011(34) 18 193

Pu3þ [51 900] [41 600] [29 400] 2564(3) 26.71(0.31) –426.6(42) 977.9(28) 150(20) [45] [45] –487(31) 489(28) 228(32) [0.985] [0.546] [0.379] 613(42) 242(34) –582(80) –1 887(83) 1122(49) 21 79

Am3þ [55 055] 43 938(148) 32 876(154) 2889(4) 29.42(0.32) –362.9(51) [500] [275] [45] [60] –289(22) 546(95) 528(52) [1.097] [0.608] [0.423] 1054(36) [280] [–884] [–1 293] [990] 23 84

Cm3þ [57 697] [45 969] [32 876] 3210(4) 29.56(0.42) –564.9(47) 839.8(28) 127(15) 24(59) 70(54) –388(44) 525(29) 378(34) [1.213] [0.672] [0.468] 667(83) 280(40) –884(62) –1293(68) 990(40) 22 83

Bk3þ [60 464] [48 026] [34 592] 3572(2) 27.36(0.26) –587.5(21) 753.5(14) 105(11) 48(11) 59(21) –529(31) 630(34) 270(14) [1.334] [0.738] [0.514] 820(42) 306(29) –1062(56) –1441(48) 941(36) 19 110

Cf 3þ 63 174(142) [50 034 R] [36 199 R] 3944(3) 30.21(1.1) –761.0(55) 488.2(39) [110] [45] [50] –256(43) 648(66) 408(44) [1.458] [0.807] [0.562] 506(102) [306] [–1062] [–1441] [941] 22 47

Es3þ 65 850 52 044 37 756 4326 30 –600 450 100 45 50 –300 640 400 1.587 0.878 0.612 600 306 –1062 –1441 941

Fm3þ

1.720 0.951 0.662 600 306 –1062 –1441 941

68 454 54 048 39 283 4715 30 –600 450 100

Md3þ

The values in parentheses are errors in the indicated parameters. The values in brackets were either not allowed to vary in the parameter fitting, or if followed by an R, were constrained: For Pu3þ, F 4/F2 ¼ 0.808; for Es 3þ, F 4/F2 ¼ 0.792, F6/F 2 ¼ 0.573. All parameters for Fm3þ and Md3þ are extrapolated values. b P2 was varied q freely, P4 and Pffi6 were constrained by ratios P4¼ 0.5P2, P6¼ 0.1P2. ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi P 2 c Deviation s ¼ Di =ðn  pÞ, where i is an index that runs over the assigned levels, Di is the difference between observed and calculated energies for the ith i assigned level, n is the number of levels fit, and p is the number of parameters freely varied.

a

F2 F4 F6 z a b g T2 T3 T4 T6 T7 T8 M0 M2 M4 P2b B20 B04 B06 B66 sc c

U3þ

Table 18.4 Energy‐level parameters for trivalent actinide ions in LaCl3 (in cm1), from Carnall (1992).a

2034

Optical spectra and electronic structure

Fig. 18.4 Variation of the parameters F2, F4, F6, DF2, DF4, DF6 where DFN ¼ FN (HFR) F4 (expt) in cm1 for An3þ:LaCl3 as a function of atomic number. (Reprinted with permission from Carnall, 1992. Copyright 1992, American Institute of Physics.)

Fig. 18.5 Variation of the parameter z(expt), z(expt), and Dz(expt) in cm1 for An3þ: LaCl3 as a function of atomic number. (Reprinted with permission from Carnall, 1992. Copyright 1992, American Institute of Physics.)

Modeling of free‐ion interactions

2035

necessary to establish a systematic trend for a specific parameter. With this procedure, linear extrapolations of model parameters from one ion to another lead to values consistent with those obtained in the actual fitting process. In addition to HFR calculations of F ks and znf, estimated values for M k ðk ¼ 0; 2; 4Þ can also be computed using the HFR method (Judd et al., 1968). These parameters do not vary dramatically across the f‐series. In practice, experience has shown that they can be taken as given or varied as a single parameter while maintaining the HFR ratios M2/M0 ¼ 0.56 and M4/M0 ¼ 0.31 (Carnall, 1989). For actinide ions, the ratio M4/M0 may be maintained at 0.380.4 (see Table 18.4). For the rest of the free‐ion effective operators introduced above, no direct Hartree–Fock calculated values can be derived. Only a term‐by‐term HFR calculation is possible to give additional guidance for parameter estimates. For example, the HFR values of P ks for Pr2þ and Pr3þ have been determined by Copland et al. (1971). In establishing systematic trends of parameters for An3þ:LaCl3, Carnall (1989) constrained the P k parameters by the ratios P4 ¼ 0.5P2 and P6 ¼ 0.1P2 whereas P2 was varied freely along with other parameters. These ratios are consistent with the HFR estimation. The variation of these parameters across the series is not significant, and no obvious systematic trends have been established. Once the systematic trends of free‐ion parameters are established, constraints can be imposed on other parameters that are relatively insensitive to the available experimental data. Some parameters such as T i, M k, and P k do not vary significantly across the series and as a good approximation can be fixed at the same values for neighboring ions in the same series. In fact, most of the free‐ion parameters are not host sensitive. Typically, there are changes of ~1% in the values of the free‐ion parameters between different lattice environments. The free‐ion parameters given in Table 18.4 can be used as initial inputs for least‐ squares fitting of the energy level structure of a trivalent f‐element ion in any crystalline lattice. If there is a limited number of experimentally determined levels, one may allow only the F k and znf parameters to vary freely along with the crystal field parameters and keep the other free‐ion parameters fixed. For further improvement of the fits, a, b, and g can be released. For a final refinement, M0 and P2 may be varied freely with M2,4 and P4,6 varied following M0 and P2, respectively, at fixed ratios. Multiconfiguration calculations have shown that similar values of these effective‐operator parameters are to be expected at both ends of the lanthanide sequence (Morrison, 1972), and empirical evaluations are in agreement with this for both the lanthanides and actinides. For three (or 11) electrons, similar arguments show the need for additional (three‐body) operators to parameterize the electrostatic interactions completely. If consideration is limited to the interactions arising from second‐order perturbation theory, only six new operators are needed (Judd et al., 1968; Judd and Suskin, 1984), and their experimental

2036

Optical spectra and electronic structure

evaluation is consistent with results expected from first‐principles calculations (Poon and Newman, 1983). Similar arguments hold for corrections to the spin–orbit interaction, as well as additional terms of relativistic origin such as the spin–other–orbit and spin– spin interactions. Hartree–Fock calculations give good estimates of the Marvin radial integrals M k ðk ¼ 0; 2; 4Þ associated with spin–other‐orbit and spin–spin interactions (Judd et al., 1968). Experimental investigations are needed for evaluation of the magnetic corrections associated with configuration interactions, but experience has shown that a single set of parameters  Pk k ¼ 2; 4; 6 with P4 ¼ 0:75P2 and P6 ¼ 0:50P2 accounts for a large part of this class of corrections (Judd et al., 1968). Use of sets of all of the foregoing parameters has been explored in detail for all of the trivalent ions from U3þ through Es3þ, and values are shown in Table 18.4 for An3þ: LaCl3.

18.4 MODELING OF CRYSTAL‐FIELD INTERACTION

When an actinide or lanthanide ion occurs in a condensed‐phase medium, the spherical symmetry of its electronic structure is destroyed, and ionic energy levels shift and split under the influence of the electric field produced by the crystalline environment. The energy level shifts and splittings depend on the nature and strength of the interaction with the environment. Some of this interaction can be absorbed by the nominal ‘free‐ion’ parameters themselves and a measure of this contribution would give clues as to the nature of the interactions. Unfortunately, mainly because of the different methods by which the free‐ion and condensed‐phase levels are determined, there are very few cases in which both sets of parameters are known well enough for meaningful comparisons to be drawn. In addition to modifications of the atomic parameters, there are medium‐ related effects that must be taken into account explicitly. The broken spherical symmetry that normally results when an isolated free gaseous ion is placed in a ligand field gives rise to a splitting of the free‐ion level into a maximum of (2Jþ1) components. A single‐particle crystal field model has had remarkable success for lanthanide ions and a somewhat qualified, but nevertheless satisfactory, success for the trivalent actinide ions in providing an interpretation of experimental data (Dieke, 1968; Hu¨fner, 1978; Carnall, 1992; Liu, 2000). The degree to which the 2Jþ1 fold degeneracy of a free‐ion state is removed depends only on the point symmetry about the ion. The magnitude of crystal‐field splittings is determined primarily by the crystal field strength that is expressed in terms of the crystal field parameters of the effective‐operator Hamiltonian. The 5f electrons of actinide ions, which participate primarily in ionic bonding with surrounding ligands, have localized states that are conventionally described in the framework of crystal field theory (Stevens, 1952; Wybourne, 1965a). Using effective‐operator techniques and the parameterization method,

Modeling of crystal‐field interaction

2037

the framework of crystal field theory has been developed with the same basis set of eigenfunctions of the effective‐operator Hamiltonian for the free‐ion interactions discussed in Section 18.3.5. Because electronic interactions in solids are complex, various interaction mechanisms that influence the electronic states of an actinide ion in a solid environment may not be accurately calculated in the framework of current crystal field theory. Evaluation of the crystal field parameters, however, is theoretically much more difficult than predicting the number of energy levels for each free‐ion state. To date, an empirical approach has been the most effective method for evaluation of the crystal field parameters of f‐states of actinide ions (Krupa, 1987; Carnall, 1992; Liu et al., 1994b). Phenomenological modeling and ab initio calculations of ion–ligand interactions are able to provide theoretical guidance for the analysis of crystal field spectra. From theoretical approaches, analytical expressions of crystal field parameters using phenomenological models are available for calculating the crystal field parameters of actinide and lanthanide ions in a specific crystalline lattice. The exchange charge model (Malkin et al., 1970; Malkin, 1987) and the superposition model (Newman, 1971; Newman and Ng, 1989a) are two crystal field models that have achieved significant success and are useful for guiding spectral analyses. In addition, ab initio calculations of the solid‐state electronic energy level structure have advanced significantly along with the rapid development of computer technology and are likely to be increasingly important in future studies (Matsika et al., 2001; Seijo and Barandiaran, 2001). 18.4.1

Correlation of free‐ion and condensed‐phase energy level structures

It was pointed out earlier that, because of the different techniques used in studying condensed‐phase and free‐ion spectra, the configurations available for direct comparison in the two cases have very little overlap. When crystals or solutions are cooled to near 4 K so that only the lowest (ground) electronic state is populated, the resultant absorption spectrum is directly interpretable in terms of energy levels, and, except for complications of superimposed vibronic bands and the added perturbations of crystal field effects themselves, the analysis can proceed to energy level assignments and parametric fitting. In free‐ion emission studies, on the other hand, many overlapping transition arrays between the multiple configurations displayed in Fig. 18.1 are obtained simultaneously, and one must first analyze this complex structure. This can only be done with the aid of additional tags on the energy levels such as isotope shift, hyperfine structure, or Lande´ g‐factor information, which requires that multiple experiments be performed. Of the many configurations that finally result, most are too heavily involved with s‐, p‐, and d‐orbitals for easy comparison with the f‐shell cases discussed here. See Chapter 16 for a detailed discussion of free‐ atom and free‐ion spectra. Nevertheless, with some assistance from theory,

Optical spectra and electronic structure

2038

cases are available from which to begin constructing a useful interpretative and predictive model. Considering the analogous lanthanide situation, nearly all the 4f2 atomic levels are known for Pr3þ as a free‐ion (Pr IV; Crosswhite et al., 1965) and as an ion in LaCl3 (Crosswhite et al., 1965; Rana et al., 1984) and LaF3 (Carnall et al., 1969, 1989) hosts. The corresponding parametric results are given in Table 18.5. This is the only example now available in either the lanthanide or actinide series for which this direct comparison can be made. For this reason, this case will be examined more closely. Columns 2 (free‐ion) and 3 (LaCl3 crystal) in the upper part of Table 18.5 give the results found for the parametric model. Comparing the two cases line‐by‐line, significant differences can be seen for the major parameters F k and z4f, and lesser ones for a and b. Any possible differences in the M k and P k values are masked by the statistical uncertainties. The parameter shifts attributed to the Pr3þ environment are given in column 4 and the relative change of the crystal values, compared to those of the free ion, in column 5. Note that the most important change, nearly 5%, occurs for F2, and about half of this for F 4, F 6, and z4f. Also a is in the same range, but with a large uncertainty. The most striking change seems to be for b, which shows an increase in magnitude of some 1015%. The 5f2 free‐ion configurations are completely known for both Th III (deBruin et al., 1941) and U V (Wyart et al., 1980; Van Deurzen et al., 1984), but the Th2þ condensed‐phase analog is not known, and analyzed data for U4þ are limited in scope. The 4f3 Pr III configuration is nearly completely known (Suger, 1963), but

Table 18.5 Medium shift of free‐ion parameters for selected f‐element ions.

F2 F4 F6 a b z M0 P2

F2 F4 F6 z

Pr IV (cm1)

Pr3þ:LaCl3 (cm1)

Medium shift (cm1)

Relative change (%)

71 822(41) 51 829(112) 33 889(72) 23 939(322) –599(19) 766(3) 2.0(0.4) 168(58)

68 498(20) 50 317(50) 33 127(38) 22 866(173) –678(9) 749(1) 1.7(0.2) 248(32)

–3324 –1512 –762 –1073 –79 –17 0 0

–4.63  0.08 –2.92  0.33 –2.25  0.32 –4.5  2.1 þ13  5 –2.0  0.5

Pu II 5f57s2 (exp.) (cm1)

Pu IV 5f5 (est.) (cm1)

Pu3þ:LaCl3 (exp.) (cm–1)

Medium shift (cm–1)

Relative change (%)

49 066(770) 39 640(719) 26 946(785) 2275(27)

50 015 40 322 27 466 2305

48 670(154) 39 188(294) 27 493(153) 2241(2)

–1345(924) –1134(1 013) þ27(938) –64(29)

–2.7  1.8 –2.8  2.5 þ0.1  3.4 –2.8  1.3

Modeling of crystal‐field interaction

2039

there is no corresponding divalent crystal case for comparison. On the other hand, both the Nd3þ:LaCl3 (Crosswhite et al., 1976) and U3þ:LaCl3 (Crosswhite et al., 1980) spectra are very well documented, but experimental work for both Nd IV and U IV are incomplete. In fact, except for thorium, no doubly or triply ionized actinide free‐ion analyses are known. Although the parametric analyses are incomplete, enough free‐ion data are available in a few cases to permit a determination of one or both of the major parameters F k and znf. For the actinides, these are all neutral atomic and singly ionized cases, for which, again, no condensed‐phase analogs are available. These are U I 5f47s2, U II 5f37s2, Pu I 5f67s2, Pu II 5f57s2, and Cf I 5f107s2, all of which contain the closed shell 7s2. Using Hartree–Fock (Cowan and Griffin, 1976) results to make corrections for the removal of the 7s2 shells, parametric values for the divalent U III, Pu III, and Cf III, and trivalent U IV and Pu IV cases can be inferred. The best example is for Pu IV. A comparison of estimated free‐ ion parameters with the Pu3þ:LaCl3 results is given in Table 18.5. Although the statistical uncertainties are large, the relative changes are consistent with those for Pr3þ in the same host. Because the shifts due to the crystalline environment and those due to the addition of the 7s2 shell are nearly the same, it has turned out that, for initial identification, the crystal absorption lines can be related directly to the free‐ion spectral lines, at least in those cases for which the crystal field can be treated in the weak‐field approximation. 18.4.2

Crystal‐field Hamiltonian and matrix element evaluation

Based on the concept that the crystal‐field interaction can be treated approximately as a point‐charge perturbation on the free‐ion energy states, which have their eigenfunctions constructed with the basis of spherical harmonic functions, the effective operators of crystal‐field interaction may be defined with the tensor operators of the spherical harmonics C(k). Following Wybourne’s formalism (Wybourne, 1965a,b), the crystal field potential may be defined by: X H CF ¼ Bkq CqðkÞ ðiÞ; ð18:32Þ k;q;i

where the summation involving i is over all the equivalent electrons of the open ðkÞ shell of the ion of interest; where the Bkq are crystal field parameters and the Cq ðkÞ are components of the tensor operators C that transform like spherical harmonics. In addition to Wybourne’s formalism for crystal   field parameters, the Stevens’ notation of crystal field parameters Aqk rk are often found in the literature. The crystal‐field interaction is often characterized by quantitative comparison of the crystal field strength defined as (Wybourne, 1965a; Auzel and Malta, 1983):

2040

Optical spectra and electronic structure 2

 2 31=2 Bkq X 61 7 Nv ¼ 4 5 ; 4p q;k 2k þ 1

ð18:33Þ

With tensor operators, evaluation of the crystal field matrix elements can be performed with the same methods used for the free‐ion matrix elements. Upon application of the Wigner–Eckart theorem, the matrix elements of the crystal‐ field interaction can be expressed with the reduced matrix elements of a unit tensor U(k) (Wybourne, 1965a; Weissbluth, 1978):



* + 

X

J k J0

0 0 0 0 JM k ltSLJM

Cq ðiÞ lt L J M ¼ ð1Þ

i

M q M 0 ð18:34Þ

E D

ðkÞ 0 0 0 0 0 ED

ðkÞ ltSLJ U l t S L J l C l : In LS coupling, the matrix elements of the unit tensor can be further reduced to D E

0 1=2 ltLSJ UðkÞ lt0 L0 S0 J 0 ¼ ð1ÞSþL þJþk ½ð2J þ 1Þð2J 0 þ 1Þ

  E ð18:35Þ

J J0 k D ltLS U ðkÞ lt0 L0 S0 0 L L S With equations (18.34) and (18.35), the reduced matrix elements of the crystal‐ field Hamiltonian can be written as:  X J k J0 JM 0 0 0 0 0 k Bq ð1Þ DkJ ; ð18:36Þ hltSLJM jH CF jlt S L J M i ¼ M q M 0 k;q

where 0

DkJ ¼ ð1ÞSþL þJþk ½ð2J þ 1Þð2J 0 þ 1Þ 1=2



J

J0

k

L0 L S  D E

l k l ltSL UðkÞ lt0 S 0 L0 ð1Þl ð2l þ 1Þ 0 0 0

 ð18:37Þ

where l ¼ 3 for fN configurations. Since all the coefficients, including the values of the 3j and 6j symbols and the doubly reduced matrix elements of the unit tensor, are known for a given free‐ion multiplet, it is obvious that evaluation of crystal‐field splittings can be performed by fitting the crystal field parameters Bkq . The doubly reduced matrix elements of U(k) may be obtained directly from Nielson and Koster (1963) or from the SPECTRA program. The values of the 3j ( ) and 6j { } symbols can be obtained from the compilation of Rotenberg et al. (1959) or by direct computer evaluation. The values of k and q for which the matrix elements are nonzero are determined by the symmetry of the crystal

Modeling of crystal‐field interaction

2041

field and the f‐electron angular momentum. For fN configurations (l ¼ 3), the 3j symbols in equation (18.37) require that k ¼ 0, 2, 4, 6, and jqj  k. The values of q are also restricted by the point group of the f‐ion site, because the crystal‐field Hamiltonian has to be invariant under all symmetry operations of the point group. Restrictions due to point group symmetry properties on the nonzero matrix elements of the crystal‐field Hamiltonian are discussed later in this section. For the matrix element of k ¼ q ¼ 0, the zero‐order of crystal‐field interaction is spherically symmetric and does not split the free‐ion energy levels, but induces a shift to all energy levels in the same fN configuration. In general, B00 is not included in evaluation of the crystal‐field splitting. Therefore, its contribution to energy level shift is combined with the spherically symmetric component of the free‐ion electrostatic interactions. One parameter, namely F 0, absorbs contributions from spherically symmetric components of free‐ion and crystal‐field interactions. Once the matrix elements in equation (18.36) are evaluated, the Hamiltonian of the crystal‐field interaction may be diagonalized together with the free‐ion Hamiltonian to obtain the crystal‐field splittings as a function of crystal field parameters. For spectral analysis, the free‐ion parameters may also be considered as variables for fitting an experimental spectrum. As a result of the crystal‐field interactions, each of the 2Sþ1LJ multiplets splits into crystal field levels. Because the off‐diagonal matrix elements of the crystal field between different J‐multiplets may not be zero, crystal field operators induce J‐mixing. In consequence, for actinide ions in crystals, both J and M are no longer good quantum numbers. As a result of J‐mixing, the eigenfunction of a crystal field level is expressed as X aJM jJM i; ð18:38Þ jmi ¼ J;M

where, in principle, the summation is over all JM terms of a given fN configuration. However, inclusion of all J‐multiplets results in extremely large matrices, particularly, for the configurations with 4  N  10. Diagonalization of the effective‐operator Hamiltonian on the entire LSJM basis could be very time‐ consuming in an analysis of an experimental spectrum from optical spectroscopy. Such spectra usually cover energy levels that are less than 40 000 cm1 above the ground state (Carnall, 1992; Liu et al., 1994b). Off‐diagonal matrix elements between free‐ion states separated by a large energy gap are small. As an approximation, crystal field calculations without including J‐mixing is appropriate only for the isolated multiplets, such as the first 5D1 excited state of Am3þ or the 8S7/2 ground state of Cm3þ. In practice, the crystal field energy level structure of a 5fN configuration is usually calculated over the restricted energy region in which experimental data are available. Free‐ion multiplets with energy

Optical spectra and electronic structure

2042

levels far from this region usually are not be included in the calculation. Namely, the free‐ion eigenfunction basis may be truncated before diagonalizing the matrix of crystal‐field Hamiltonian. Theoretically, this truncation of free‐ion states is justified because crystal‐field coupling diminishes between two free‐ion multiplets as their energy gap increases. From the perturbation point of view, the leading contribution of J‐mixing to the energy level splitting of the J‐multiplets is proportional to 1/DEJJ0 . Given that the crystal‐field splitting of a free‐ion multiplet is about 1001000 cm1, multiplets that are separated by 104 cm1 should have no significant influence on each other. In computational analyses of experimental spectra, one may truncate the free‐ ion states whose energy levels are far from the region of interest. This is readily accomplished after diagonalization of the free‐ion matrix to produce a calculated free‐ion energy level structure. These levels are considered to be the centers of gravity for the crystal‐field splitting (Carnall et al., 1983; Carnall, 1992). One chooses the numbers of J‐multiplets to be included in the crystal‐field matrices for each J‐value. Therefore, the chosen J‐multiplets are still complete sets of free‐ion eigenfunctions that contain all SL components of the given J. This way of free‐ion state truncation ensures that no contribution from the free‐ion interactions is lost when constructing the free‐ion wave functions for each J‐multiplet. One example is the 8S7/2 ground state of ions in a 5f7 configuration for Am2þ, Cm3þ, or Bk4þ in which both diagonal and off‐diagonal matrix elements of the crystal field operators vanish (Wybourne, 1966; Newman, 1970; Liu et al., 1993; Newman and Ng, 2000). The observed crystal‐field splittings must be attributed to the contributions of the mixture of other LS terms in the ground state free‐ ion wave function and nonzero off‐diagonal matrix elements between different J values (Liu et al., 1993, 1998; Murdoch et al., 1996, 1998). Because of large energy gaps from the ground state to the excited multiplets (16 000 cm1), J‐mixing is negligible in this case. It has been shown that for the 8S7/2 ground state splitting, the leading contributions are from the fourth and higher orders of the coupled matrix elements between the spin–orbit (V(11)) and crystal field (U(k)) operators (Liu et al., 1993; Brito and Liu, 2000). Without inclusion of J‐mixing, the leading contributions to the crystal‐field splitting of the 8S7/2 multiplet of an f7 configuration are from the mixed matrix elements such as D



ED

ED

ED

E S Vð11Þ 6 P 6 P Uð2Þ 6 D 6 D Uð2Þ 6 P 6 P Vð11Þ 8 S D

ED6 ð11Þ 6 ED6 ð6Þ 6 ED6 ð11Þ 8 E 8 ð11Þ 6 SV P P U I I U P P V S : 8

ð18:39Þ

It is obvious that truncation of LS terms in the J ¼ 7/2 multiplets should affect the scale of the coupled matrix elements, and thus affect the calculated crystal‐field splitting. The same situation occurs for the off‐diagonal matrix elements between different J‐levels, but is less important because of the large energy gap between the ground state and the first excited state.

Modeling of crystal‐field interaction 18.4.3

2043

Symmetry rules

The geometric properties of the crystal field operators will now be discussed in more detail. In addition to the angular momentum of the f‐ions that restricts k and q for a set of nonvanishing crystal field operators, the site symmetry in a crystalline lattice also imposes limits on crystal field operators. The tensor operators for the crystal‐field interaction must be invariant under the point group symmetry operations imposed by the site symmetry of the ion in question. Here the interest is to identify the nonvanishing components of crystal field operators and their matrix elements. First, for states of the same parity, namely l ¼ l0 , k must be even. It is also required that Bkq must be real in any symmetry group that contains a rotation operation about the y‐axis by p or a reflection through the xz plane; otherwise Bkq (q 6¼ 0) is complex. In the latter case, one of the Bkq can be made real by a rotation of the coordinate system about the z‐axis. The Bkq for q < 0 are related to those of q > 0 by Bkq ¼ ð1Þq Bk q :

ð18:40Þ

Also under the invariant conditions of the point group theory, the crystallographic axis of the lowest symmetry determines the values of q for the nonvanishing crystal field operators. For example, at a site of C3v symmetry, there is a three‐fold axis of rotational symmetry with a reflection plane that contains the C3 axis (Tinkham, 1964; Hu¨fner, 1978). The ligand field must exhibit this symmetry. Hence, if a 2p/3 rotation is performed on the crystal field potential followed by a reflection with regard to the plane, the potential is invariant only if q ¼ 0, 3, and 6. Thus, within an fN configuration, the crystal‐field Hamiltonian may be written as X ð2Þ ð4Þ ð4Þ ð4Þ ½B20 C0 ðiÞ þ B40 C0 ðiÞ þ B43 ðC3 ðiÞ  C3 ðiÞÞ H ðC3v Þ ¼ i

ð6Þ

ð6Þ

ð6Þ

ð6Þ

ð6Þ

þ B60 C0 ðiÞ þ B63 ðC3 ðiÞ  C3 ðiÞÞ þ B66 ðC6 ðiÞ þ C6 ðiÞÞ : ð18:41Þ If the reflection plane is perpendicular to the C3 axis, the site symmetry becomes C3h, which occurs for doped fN impurity ions in lanthanum ethylsulfate, LaCl3, and LaBr3 (Morosin, 1968). This potential invariant property requires q = 0, 6 only, but, since there is no rotation symmetry about the y‐axis by p or a reflection through the x–z plane for the C3h site, there is an imaginary noncylindrical term in the Hamiltonian: X ð2Þ ð4Þ ð6Þ ð6Þ ½B20 C0 ðjÞ þ B40 C0 ðjÞ þ B60 C0 ðjÞ þ B66 ðC6 ðjÞ H ðC3h Þ ¼ j ð18:42Þ 0 ð6Þ ð6Þ ð6Þ 6 þ C6 ðjÞÞ þ iB6 ðC6 ðjÞ  C6 ðjÞÞ : D3h is a symmetry group that includes all rotation and reflection operations of C3h (Tinkham, 1964; Hu¨fner, 1978). The crystal field operators for ions at a

2044

Optical spectra and electronic structure ð6Þ

ð6Þ

D3h site are the real terms for C3h without the imaginary term iB06 6 ðC6  C6 Þ. The nonvanishing terms of crystal field operators for various lattice sites of f‐ions in crystals are listed in Table 18.6. The free‐ion degeneracy in M may be partially or completely removed by the crystal‐field interaction. In the crystal‐field energy matrix using the JM ðkÞ basis set, the terms for which MM0 ¼ q for the operator Cq are nonzero. Otherwise the crystal‐field matrix elements are zero. Based on this property, the crystal‐field matrix may be reduced into several independent submatrices, each of which is characterized by a crystal quantum number m (or g). Each m represents a group of M, such that MM0 ¼ q(0, 2, 3, 4, 6) belongs to the same submatrix (Hu¨fner, 1978). All matrix elements between the submatrices are zero. The crystal field quantum number may be used to classify the crystal field energy levels even when J and M are not good quantum numbers. Considering C3h (and D3h) as an example, the JM and J0 M 0 (J may be equal to J0 ) with MM0 ¼ 6 belong to the same crystal field submatrix. For an even number of f‐electrons, there are four independent submatrices, and for an odd number of f‐electrons, there are three independent submatrices. The parameters of nonvanishing crystal field terms for symmetries of common crystal hosts of f‐element ions are given in Table 18.6 along with the numbers of reduced crystal‐field matrices. Without a magnetic field, the electrostatic crystal field alone does not completely remove the free‐ion degeneracy for the odd‐numbered electronic configurations. Known as Kramers’ degeneracy (Kramers, 1930; Hu¨fner, 1978), all crystal field levels are at least doubly degenerate. The crystal quantum number and JM classification schemes are given for D3h symmetry in Table 18.7. In calculation of energy level structure for degenerate doublets, one may cut off half of the submatrix elements. In many cases, calculations of crystal field energy levels have been carried out usefully by assuming a higher site symmetry than the real one so that fewer parameters are required. In some cases, this approach was used because actinide ions in many solids occupy a low‐ symmetry site and the limited number of observed energy levels could not accurately determine a large number of crystal field parameters (Carnall et al., 1991). In other cases, a crystal lattice that does not have mirror symmetries in its coordinates requires complex crystal field parameters for the q 6¼ 0 terms (Table 18.6). If one uses as an approximation only the real part of the crystal field operators, energy level calculation becomes much easier. Because the use of high symmetry as an approximation is equivalent to upgrading a lower‐symmetry site to a higher one within the same crystal symmetry group, this approach has been called the descent‐of‐symmetry method (Go¨rller‐Walrand and Binnemans, 1996). This method may be applied to the groups of monoclinic, trigonal, and tetragonal structures listed in Table 18.6. For example, the C3h symmetry of LaCl3 was replaced by D3h (Morrison and Leavitt, 1982); the S4 site symmetry of trivalent lanthanide ions in LiYF4 is often treated as D2d (Esterowitz et al., 1979; Go¨rller‐Walrand et al., 1985; Liu et al., 1994a). Similarly, the actual C2 symmetry of LaF3 was replaced by C2v (Carnall et al., 1989).

Cs, C2,C2h C2v, D2, D2h C3, S6(C3i) C3v, D3, D3d C4, S4, C4h D4,C4v, D2d, D4h C6,C3h, C6h,D6, C6v, D3h, D6h T, Td, Th, O, Oh

monoclinic rhombic trigonal

e

d

c

b

a

1/2, 3/2 (D) 1/2, 3/2, 5/2 (D)

0, 2 (S), 1 (D) 0, 3 (S), 1, 2 (D)

 e B04 ; B60 ; Re B44 ; B64

CeO2

1/2, 7/2 (D), 3/2 (Q)

1/2, 3/2 (D)

0 (S), 1 (D)

0, 4 (S), 2, 6 (D), 1 (T)

1/2 (D)

0, 1 (S)

B20 ; B04 ; B60 ; ReðB22 Þ; B24 ; B62 ; B44 ; B64 ; B66   B20 ; B04 ; B60 ; Re B22 ; B24 ; B62 ; B44 ; B64 ; B66 B20 ; B04 ; B60 ; ReðB34 Þ; B63 ; B66   B20 ; B04 ; B60 ; Re B34 ; B63 ; B66   B20 ; B04 ; B60 ; Re B44 ; B64   B20 ; B04 ; B60 ; Re B44 ; B64   B20 ; B04 ; B60 ; Re B66

LaF3 Y3Al5O12 LiNbO3 Y2O2S LiYF4 YPO4 LaCl3

m for odd Nd

m for even Nd

Bkc q

Example

Morrison and Leavitt (1982). Hu¨fner (1978).   For q 6¼ 0, Bkq are complex except for the real terms Re Bkq . S, singlet; D, doublet; T, qffiffitriplet; Q, quartet. ffi B04 ; B64 ¼  72B60 B44 ¼ p5ffiffiffi 70

cubic

hexagonal

tetragonal

Site symmetry

Crystal structure

Table 18.6 Nonvanishing terms of crystal field (CF ) parameters Bkq , numbers of reduced matrices and crystal field quantum number m for f N configurations in crystals of various symmetries.a,b

Optical spectra and electronic structure

2046

Table 18.7 Classification of crystal field energy levels for D3h symmetry. (a) Even number of electrons m ¼ 0 (1G1, 2)

m ¼  1 (2G5)

m ¼  2 (2G6)

m ¼ 3 (1G3, 4)

J

M

M

M

M

0 1 2 3 4 5 6 7 8

0 0 0 0 0 0 6, 0, 6 6, 0, 6 6, 0, 6

1 1 1 1 1; 5 1; 5 7; 1; 5 7; 1; 5

2 2 2; 4 2; 4 2; 4 2; 4 8; 2; 4

3, 3 3, 3 3, 3 3, 3 3, 3 3, 3

No. levels

1 2 3 5 6 7 9 10 11

(b) Odd number of electrons m ¼  1/2 (2G7)

m ¼  3/2 (2G8)

m ¼  5/2 (2G9)

J

M

M

M

1/2 3/2 5/2 7/2 9/2 11/2 13/2 15/2

1/2 1/2 1/2 1/2 1/2 1/2,  l1/2 13/2, 1/2, l1/2 13/2, 1/2, l1/2

3/2 3/2 3/2 3/2, 9/2 3/2, 9/2 3/2, 9/2 15/2, 3/2, 9/2

5/2 5/2, 7/2 5/2, 7/2 5/2, 7/2 5/2, 7/2 5/2, 7/2

No. levels

1 2 3 4 5 6 7 8

In general, use of the descent‐of‐symmetry method may have more complicated consequences than that of the above examples. For a specific symmetry modification, one may estimate the changes in crystal field parameters based on the rotational symmetry of point charges in polar coordinates (y,f) and assuming that the ligand ions in each coordination shell are at the same distance from the f‐element ion. For an arbitrary rotation, the Bk0 parameters should only depend on the y‐coordinates, whereas the Bkq parameters (q 6¼ 0) depend on both y‐ and f‐coordinates. Changes in the f‐coordinates have no influence on Bk0 and jBkq j ¼ ½ðReBkq Þ2 þ ðImBkq Þ2 1=2 . Descent‐of‐symmetry operations that have this property are Cnh ! Dnh, S4 ! D2d, and Cn ! Cnv. The symmetry changes that incorporate a change in y‐coordinates will change all parameters, such as Dnh ! Cnv and Dnh ! Cn. If the symmetry of the f‐element site is lowered, not only are additional parameters required, but there are also changes in the crystal field parameters found in the higher symmetry. In consequence, there is far less rationale for using Dn has an approximation for Cn and Cnv.

Modeling of crystal‐field interaction

2047

Site distortion is a common phenomenon when f‐element ions are doped into crystals. A dopant ion may have site symmetry lower than that of the host ion it replaces. This is especially true if the charge on the dopant ion and/or its ionic radius is different from that of the host ion. Accordingly, both the sign and magnitude of crystal field parameters are subject to change. As discussed above, different crystal structures may undergo different types of distortion that reflect the properties of the specific coordination polyhedron in a given crystal. Go¨rller‐Walrand and Binnemans (1996) give a detailed description of the effects of structural distortion in terms of changes in the y‐ and f‐coordinates. However, changes in radial distances may occur as well. For ions at a distorted site that further reduces the degeneracy of electronic states, analyses of crystal field spectra must be conducted using a lower symmetry. 18.4.4

Empirical evaluation of crystal field parameters

Extensive mixing of SL‐basis states, brought about by the spin–orbit and crystal‐field interactions for each J‐multiplet, can result in the least‐squares method for empirical evaluation of crystal field parameters converging to a false solution. A false solution can be recognized if there is sufficient characterization of the states from supplementary data, such as Zeeman splitting factors or polarized spectra. However, this in itself may not produce the true solution. The latter can only be found if sufficiently accurate initial parameters are available for the least‐squares fitting process to be effective. Therefore, establishing accurate parameters for the model Hamiltonian essentially relies on systematic analyses that encompass theoretical calculations for incorporating trends of parameter variation across the f‐element series (Carnall, 1989; Liu et al., 1994b; Liu, 2000). The results of analyses of simpler spectra are carried over to more complex ones through consideration of their symmetry properties. For f‐element ions in crystals of well‐defined site symmetry, crystal field theory is widely used along with group theory for predicting the number of energy levels and determining selection rules for electronic transitions between crystal field levels. Whereas the number of nonvanishing crystal field parameters can be determined by the symmetry arguments, their values are usually determined by analyzing the experimentally observed crystal‐field splittings. Experimental data that carry supplementary spectroscopic information, such as polarized transitions allowed by electric or magnetic dipolar selection rules, ensure the accuracy of the experimentally fitted crystal field parameters (Liu et al., 1992, 1994a, 1998). In addition, the temperature dependence of observed crystal‐field splittings may be analyzed to distinguish pure electronic lines from vibronic features. Properties such as magnetic susceptibility as a function of temperature may be calculated from the empirical wave functions as a further check on the accuracy of the crystal field parameters. If multiple sites exist, site‐resolved spectra are required to distinguish energy levels of ions at different sites (Tissue and Wright, 1987; Liu et al., 1994b; Murdoch et al., 1996). Accordingly, as a procedure of

2048

Optical spectra and electronic structure

parametric modeling, correct assignment of observed energy levels is crucial to avoid a false solution. For spectra that lack sufficient experimental information to achieve unambiguous assignment, this procedure may involve several iterations of trial calculations and analyses that require a firm understanding of the basics of crystal‐field splitting of free‐ion states (Carnall, 1989, 1992). For setting initial parameters of the crystal‐field Hamiltonian to be fit by observed energy levels, one may simply use the previously established parameters for different f‐element ions in the same or similar host materials. For the series of trivalent actinide ions in LaCl3, one of the most extensively studied host crystals, the parameters of free‐ion and crystal‐field interactions are listed in Table 18.4. Comprehensive summaries of previously studied lanthanide systems are given (Morrison and Leavitt, 1982; Go¨rller‐Walrand and Binnemans, 1996). Alternatively, the signs and magnitudes of crystal field parameters can be predicted according to the coordination of the f‐element ion using the point charge model of the electrostatic crystal field potential. For this purpose, only the nearest ligand (NL) atoms need to be considered. As a function of the radial and angular coordinates, the expressions for the Bkq parameters are given in the following section. The signs of the crystal field parameters are determined by the angular part of the electrostatic potential and may be obtained by symmetry analysis. The predicted signs are important for checking the signs of the parameters obtained by the fitting procedure. Some sign combinations may correspond to a coordination that is physically impossible. Generally, determination of the magnitudes requires more quantitative calculations of the overlap integrals between the f‐electrons and the electrons of the ligands. The electrostatic interactions beyond the nearest ligands may bring about significant contributions to the parameters with k ¼ 2. For these parameters, the total contribution from the long‐range interactions may exceed that of the NL so that a change in the sign of B2q determined by the NL atoms is possible (Zhorin and Liu, 1998). Moreover, the electrostatic point charge model is not realistic in describing the short‐range interactions between the f‐element ion and its nearest ligands. Charge exchange interactions including covalency may dominate the crystal field parameters with k ¼ 4 and 6. For these reasons, an empirical approach with theoretical guidance is necessary to ensure that the parameterization is within the limitations of physical interactions. In a nonlinear least‐squares fitting process, the magnitudes and signs of crystal field parameters are varied to best reproduce the observed energy level structure. This is actually a process of optimizing crystalline structure within a given restriction through variation of the crystal field parameters. The parameters that have higher weight are better determined than the parameters that have less influence on the observed energy levels. Adding an imaginary parameter may only change the real part of the term that has the same q and k but does not have much influence on other parameters. If the values of the crystal field parameters for a system of higher symmetry are used as initial values of the parameters for a different system of lower symmetry, the fitting may either

Modeling of crystal‐field interaction

2049

fall into a false solution or leave the added parameters less accurately determined. In this case, one should assign the unambiguously observed energy levels, most likely the isolated multiplets, and only allow the most significant crystal field parameters to vary freely. Once these weighted parameters converge, further fitting should be performed on the entire set of crystal field parameters, along with the variation of the free‐ion parameters. 18.4.5

Theoretical evaluation of crystal field parameters

Quantum mechanical calculations of crystal field energies and corresponding crystal field parameters for f‐element ions in compounds with different chemical characteristics were carried out by several groups in the framework of the cluster approximation. For an f‐ion and its nearest ligands (chlorine, fluorine, or oxygen ions), the fully antisymmetric and orthonormalized wave functions of zero‐order are constructed as linear combinations of products of individual ion wave functions, and the energy matrix is built with the complete Hamiltonian that contains one‐ and two‐electron operators including the interaction with the electrostatic field created by the rest of the crystal. The first‐order contributions to the energy matrix include integrals over one‐electron wave functions of the occupied states of the cluster. Higher‐order contributions correspond to configuration mixing. The procedure and details of calculations have been described in several original and review papers (Newman, 1971; Eremin, 1989; Garcia and Faucher, 1995; Shen and Bray, 1998; Zhorin and Liu, 1998; Newman and Ng, 2000). Here we present only a brief description of the results of ab initio simulations that are important for modeling of the main physical mechanisms responsible for crystal‐field splittings. The first‐order terms in the energy matrix include Coulombic, exchange, and overlap integrals over 5f orbitals of the actinide ion and outer orbitals of ligand ions. From these terms, the 5f‐electron energy in the electrostatic field of the ligand point multipole moments and the charge penetration contribution may be singled out. The second‐order terms may be classified according to intermediate (virtual) excited states of the cluster. In this regard, the following electronic excitations should be considered: (1) Intra‐ion excitations from the filled electronic shell of the actinide ion to the empty excited shell (in particular, 6p6 ! 6p56d1). These processes shield the inner valence 5fN shell and may be accounted for, at least partly, by introducing shielding (or antishielding) moments

multipole  k  factors into  the  of the valence electron 5f r 5f ! ð1  sk Þ 5f rk 5f (Rajnak and Wybourne, 1964). (2) Intra‐ion excitations from the valence shell into empty shells and from the filled shells into the valence shell (in particular, 5fN ! 5fN16d1 or 6p6 ! 6p55fNþ1). These processes contribute to the linear shielding and cause additional corrections to parameters of the effective Hamiltonian bilinear in parameters of the electrostatic field.

2050

Optical spectra and electronic structure

(3) Inter‐ion excitations, mainly into the charge‐transfer states of the actinide ion with the extra electron in the valence shell promoted from the outer‐filled shell of the ligand. Actually, mixing of the ground configuration with the charge‐transfer states corresponds to a partially covalent character in the chemical bonding between an actinide ion and its ligands. It should be noted that the effective‐operator Hamiltonian (equation (18.32)) with a single set of crystal field parameters, operating within the total space of wave functions of 5fN configuration, can be introduced if all excited configurations of the cluster under consideration are separated from the ground configuration by an energy gap that is much larger than the width of the energy spectrum of the ground configuration. Otherwise the crystal field parameters become term (LSJ) dependent. In particular, a crystal field analysis carried out on an extended basis containing the ground 4f2 and excited 4f5d, 4f6p configurations of Pr3þ in YPO4 (Moune et al., 2002) greatly improved the agreement between the experimental data and the calculated energy levels. For the 5fN configurations, the inter‐configuration coupling is anticipated to be much stronger because of smaller gaps between the ground and excited state configurations, particularly, for the lighter actinides in the first half of the 5fN series. A general conclusion about the dominant role of overlap and covalent contributions to the crystal field parameters Bq4 and Bq6 follows from all ab initio calculations carried out up to the present time. When Hartree–Fock one‐ electron wave functions of free ions are used in simulations, relative differences between the theoretical and experimental values of these parameters do not exceed 50%. However, for the quadrupole component of the crystal field parameters B2q , contributions from the long‐range interactions of valence electrons with point charges, dipole, and quadrupole moments of ions in the crystal lattice are comparable to contributions from the interactions with the nearest ligand ions, and the theoretical estimations differ substantially from the experimental data. Whereas the free‐ion parameters vary smoothly across the 5f series, trends in crystal field parameters, particularly Bq4 and Bq6 , usually break at the f7 configuration. Experimental evidence for this effect is evident in the systematic analysis of the spectra of trivalent actinides doped into single‐crystal LaCl3 (Carnall, 1992) and trivalent lanthanides in LaF3 (Carnall et al., 1989). An abrupt change in the magnitude of parameters with k ¼ 4 and 6 occurs at the center of the series. Judd (1979) has interpreted this effect as a problem of the one‐electron operators of the crystal‐field Hamiltonian. One‐electron operators, Uk, change sign at the center of the series. Inclusion of two‐electron operators in the crystal‐field Hamiltonian would likely remove this discontinuity. Although extensive Hartree–Fock calculations have been utilized for establishing systematic trends of free‐ion interactions that lead to the determination of the parameters of the effective‐operator Hamiltonian, most analyses of crystal‐field interactions are carried out with the crystal field parameters determined by the fitting of experimental data. Attempts to calculate the crystal field

Modeling of crystal‐field interaction

2051

parameters from first principles may not be realistic. Given the complexity of electronic interactions in solids, ab initio calculations of electronic structure of heavy element ions in solids currently are not capable of achieving accuracy that is comparable to experimental results. Therefore, theoretical models, more or less phenomenological on the basis of the point‐charge approximation, are essential in providing a clear theoretical understanding of electronic interactions of the f‐element ions in solids. Model calculations do not only generate the phenomenological crystal field parameters that provide guidance to parametric modeling of the crystal field spectra of f‐element ions in solids, but also reveal more fundamental aspects of the ion–ligand interactions that are poorly characterized by the point‐charge approximation itself. Among the crystal field models introduced in the literature, the angular overlap model (Jørgensen et al., 1963), the exchange charge model (Malkin et al., 1970; Malkin, 1987), and the superposition model (Newman, 1971; Newman and Ng, 1989b, 2000) have been used for calculations of crystal field parameters for both 4f elements and 5f elements in various crystals. Detailed discussions of the superposition model of the crystal field and its application to analysis of experimental spectra were provided by Newman and Ng (1989b, 2000). The superposition model neglects the ligand–ligand overlap effects and reflects the total crystal‐field interaction as a linear ‘superposition’ of local ion–ligand pair‐wise electrostatic interactions. The crystal field parameters are expressed as a sum of individual contributions from ions in the host crystal lattice, X  k ðRL Þgk;q ðyL ; ’L Þ; Bqk ¼ B ð18:43Þ L

where gk,q are normalized spherical harmonic functions, and RL, yL, ’L locate the position of ligand L in the lattice coordination environment. The distance‐  k ðRL Þ are referred to as intrinsic crystal field paradependent parameters B meters, which by definition are dependent only on the radial distance between the f‐ion and the ligand L. Based on the assumption of the point charge model that the ion–ligand electrostatic interaction has a specific power law dependence, the intrinsic parameters can be defined as  k ðRÞ ¼ B  k ðR0 ÞðR0 =RÞtk ; B

ð18:44Þ

where R0 is the distance between the f‐ion and a reference ligand located on the z‐axis of the crystalline lattice, and tk are power law exponents that reflect the distance dependence of the ion–ligand interaction (Newman and Ng, 2000).  k ðR0 Þand tk can be empirically determined as phenomenological parameters. B It should be noted that the parameters tk are not generally in agreement with the electrostatic power law components t2 ¼ 3, t4 ¼ 5, t6 ¼ 7. For chloride ligands, in particular, t4 ¼ 12  16, t6 ¼ 5  7 for different RE ions (Reid and Richardson, 1985). Values of the rank 4 and 6 parameters quickly decrease with R, and the corresponding sums (equation (18.43)) are limited to the nearest neighbors of the f‐ion. Because of their long‐range effect, values of the rank 2

2052

Optical spectra and electronic structure

parameters are often difficult to determine. One may break the rank 2 operator into two terms, labeled as p and s (Levin and Cherpanov, 1983):  2 ðRL Þ ¼ B  p ðR0 ÞðR0 =RL Þ3 þ B  s ðR0 ÞðR0 =RL Þ10 B 2 2

ð18:45Þ

to represent, respectively, the ligand point charge contribution and the short‐ range contribution. Apparently, model calculations of crystal field parameters result in less discrepancies for some systems than for others. This is mainly due to uncertainties in structure information to which crystal field calculations, particularly of the rank 4 and 6 parameters, are extremely sensitive. Crystal lattice constants determined from X‐ray diffraction or neutron scattering may be of very high resolution only for intrinsic sites. For impurity f‐element ions doped into host materials, an unknown structural distortion is induced in most cases. The doping‐induced site distortion depends in part on the ionic radius difference between the host ion and the doped f‐element ion. If a model calculation is conducted based on the structure of the host, the calculated crystal field parameters are expected to be more or less different from those determined by fitting experimental data for the system. The exchange charge model (ECM) (Malkin et al., 1970; Larionov and Malkin, 1975; Malkin, 1987) is an extension of the angular overlap model (Jørgensen, 1962). It considers both long‐range and short‐range interactions between the actinide or lanthanide ion and lattice ions. The effective crystal‐field Hamiltonian is assumed to be a sum H

CF

¼H

pm

þH

ec

ð18:46Þ

where the first term corresponds to the electrostatic interaction of valence electrons localized on the f‐element ion with point multipole moments of the lattice ions. The second term approximates all contributions due to the spatial distribution of electron density. Both terms have the form of equation (18.44) with ðpmÞk ðecÞk parameters Bq and Bq . Matrix elements of the effective‐operator Hamiltoec nian H in the basis of one‐electron wave functions of the metal ion interacting with spherical ligand ions may be calculated (Malkin et al., 1970; Malkin, 1987). To gain a greater insight into the energy level calculations, it is instructive to compare contributions to the electrostatic crystal field parameters with those from overlap and covalency effects. The ECM introduces the renormalization of the parameters of the electrostatic crystal field only and does not change the structure of the Hamiltonian H pm. This renormalization may be considered to be a result of the ‘nonlocal’ interaction of the valence electron with the exchange charges localized at the bonds connecting the metal ion with its nearest neighbor ions. The concept of exchange charge, for which the crystal field model under consideration was named, and was first introduced by Dick and Overhauser (1958) in the theory of dielectric properties of solids. Values of exchange charges are proportional to the linear combinations of the overlap integrals and depend on the rank k of the corresponding tensor B(k) of crystal field parameters. It is

Modeling of crystal‐field interaction Table 18.8

B20 B04 B06 ReB44 ReB46 ReB66 ImB66 a b c

2053

Crystal field parameters from ECM calculation and experimental fit (cm1).a Nd 3þ:LaCl3

(C3h symmetry)

Cm3þ:LuPO4

(D2d symmetry)

Calculated b

Experimental ( fit to D3h)

Calculated c

Experimental c

78(39) 78(57) 44(41)

81 42 44

450(180) 370(230) 2500(2050) 2400(1200) 200(185)

399 363 2470 2261 167

299(279) 239(226)

439

b

The values in parentheses are the contribution from exchange‐charge interactions. Zhorin and Liu (1998). Liu et al. (1998).

important that the ECM allows for consideration of both even and odd components of the crystal field. In particular, integral intensities of spectral lines in the intra‐configurational 5fN5fN spectra and their frequencies may be fitted in the framework of a single model. As an example of ECM calculation, Table 18.8 lists the values of crystal field parameters calculated by using the ECM in comparison with the experimentally determined ones. It is evident that the dominant contributions to B2q are from electrostatic interactions, whereas those to Bq4 and Bq6 are from short‐range interactions. It is generally realized that the second‐order parameters Bkq with k = 2 are less accurately determined by the model calculation, particularly for a disordered lattice. This is because the second‐order parameters characterize the long‐range electrostatic interactions that are difficult to calculate accurately. It should be noted that the contradiction between the calculated and experimental values of the B20 parameter in Nd3þ:LaCl3 (in particular, different signs) may be removed when taking into account large contributions due to point dipole and quadrupole moments of chlorine ions (Eremin, 1989). 18.4.6

Corrections to the crystal‐field Hamiltonian

As described in earlier sections, the parameterization approach is able to reproduce the crystal field energy level structures of actinide or lanthanide ions in satisfactory agreement with high‐resolution absorption and luminescence spectra. The standard deviation in a nonlinear least‐squares fit to experimental spectra in the low‐lying energy levels (40 000 cm1) can be less than 10 cm1 for lanthanide ions (Liu et al., 1994a). However, crystal field modeling of energy levels for some particular states in the 4f configurations is invariably poor as, for instance, in the cases of the 2H11/2 multiplet of Nd3þ and 3K8 of Ho3þ. The discrepancies are much larger for the actinides in 5fN configurations

Optical spectra and electronic structure

2054

(Edelstein, 1979; Carnall, 1992; Liu et al., 1994b; Murdoch et al., 1997; Liu, 2000). Faucher et al. (1996) reported in energy level analysis of U4þ in the octahedral sites of Cs2UBr6 and Cs2ZrBr6 evidence of strong interaction between the 5f2 and 5f17p1 configurations. Adjustment of the parameters in the free‐ion Hamiltonian does not result in much improvement. This problem is primarily due to the exclusion of the electron correlation effect in the one‐ electron crystal field model. The effects of electron–electron interaction cannot be completely absorbed into the effective‐operator Hamiltonian of the one‐ electron crystal field model. Reid and coworkers (Reid, 2000) have reviewed progress in the modification of the one‐electron crystal field theory with inclusion of correlation crystal field operators in the Hamiltonian. There are various physical mechanisms that contribute to multiplet‐dependent crystal‐field splittings that can be described generally as correlation effects. The two obvious mechanisms, namely, the spin‐correlated crystal field potential (Newman, 1971; Judd, 1977b) and the anisotropic ligand polarization effect, also known as nephelauxetic effect (Jørgensen, 1962; Gerloch and Slade, 1973), have been identified as large contributors, although, it is not clear what physical mechanisms produce the dominant contribution to shift the f‐electron energy levels. To correct the discrepancy that appears in analyses of optical spectra with the one‐electron crystal field model, it becomes necessary to introduce a full parameterization of the anisotropic two‐electron interaction. To facilitate calculations of the matrix elements with the same basis for the one‐electron ðkÞ operator Hamiltonian, Judd’s giq operators (Judd, 1977a), which are orthogoN nal over the complete f basis sets, are used to define the correlation crystal field (CCF) Hamiltonian (Reid, 1987): X ðkÞ H CCF ¼ Gkiq giq ; ð18:47Þ ikq

Gkiq

are parameters of CCF. The index k runs through the even integers where from 0 to 12 (4l, for fN configurations). The parameter q is restricted by ðkÞ symmetry, and the number of operators varies with k. The operators gi with k ¼ 0 correspond to Coulomb interactions and those with i ¼ 1 to one‐electron ðkÞ operators, in fact g1  UðkÞ . The main problem in the application of the CCF Hamiltonian is the very large number of parameters that are necessary to account for electron–electron correlation. However, the successful parameterization of f‐ion crystal field energy level structure is largely dependent on the accuracy and the number of observed and properly assigned energy levels. In general, nonlinear least‐square fitting requires that the number of assigned energy levels should be much larger than the total number of freely varied parameters. Expansion of the effective‐ operator Hamiltonian by including the operators for the correlation crystal‐ field interaction is effective only if there are sufficient experimental data and correctly determined parameters for the free‐ion and one‐electron crystal‐field Hamiltonian for initial input. Otherwise, fits may fall into false minima and

Modeling of crystal‐field interaction

2055

produce inconsistent parameters. To correct the one‐electron crystal field discrepancy by adding more terms to the crystal‐field interaction, one should always consider restrictions on operators and introduce constraints based on physical relationships to reduce the number of freely varied parameters. As discussed in Section 18.3, the effective‐operator Hamiltonian for the free‐ ion interaction includes a corrective term (equation (18.26)) due to configuration interaction. In crystal field theory, the effect of configuration interaction was also considered (Rajnak and Wybourne, 1964). For a configuration of equivalent electrons lN, most mechanisms of configuration interaction lead to a simple scaling of the crystal field parameters Bkq . However, a one‐electron excitation, either from the lN shell to unfilled orbitals or from closed shells into the lN shell, also results in effects that cannot be accommodated by a scaling of the Bkq parameters alone. As a result, the crystal field parameters are expected to vary from one multiplet to another. For the weak crystal‐field interaction of the f‐element ions in crystals, the usual method of a second‐order perturbation theory can be used to characterize the configuration interaction (Judd, 1963a; Rajnak and Wybourne, 1963, 1964). ðkÞ The single particle operator Cq in equation (18.32) can only couple configurations that differ by the excitation of a single electron. Thus, for an nlN‐type configuration, only three types of configurations are coupled: 0

0

0

0

ð1Þ nl N n0 l 4l þ1 with nl N n0 l 4l þ1 n0 l 00 ; ð2Þ nl N with nl N1 n0 l 0 ; 0 0 0 0 ð3Þ nl N n0 l 4l þ2 with nl Nþ1 n0 l 4l þ2 . As a result of the interaction between these configurations, each matrix element of equation (18.32) must be replaced by



D E



ð1 þ DÞ l N tSLJM Bkq CqðkÞ l N t0 S0 L0 J; M 0 ð18:48Þ where D is known as the configuration interaction correction factor. This factor is the sum of two terms D1 and D2, where    1 X nl N cjH CF jm mjH CF jnl N c0 D1 ¼ ; ð18:49Þ E m hnl N cjH CF jnl N c0 i and

   2 X nl N cjH CF jm mjH C jnl N c0 D2 ¼ E m hnl N cjH CF jnl N c0 i

ð18:50Þ

and E is the mean excitation energy of the excited electron, m is a state of the perturbing configuration, H CF is the crystal‐field Hamiltonian, and H C is the Coulomb interaction in the free‐ion Hamiltonian. The first correction factor D1 corresponds to configuration mixing purely by the crystal field, whereas the second factor D2 represents an electrostatically correlated crystal‐field interaction between the configurations. Methods for

2056

Optical spectra and electronic structure

evaluating the matrix elements have been discussed in detail in previous work (Judd, 1963a; Rajnak and Wybourne, 1964). It has been shown that the primary effect of configuration interaction is simply to scale the crystal field parameters Bkq . The individual parameters are shielded (or antishielded) by different amounts depending on the perturbing configuration. This overall scaling effect is absorbed into the crystal field parameters determined from the experimental data. However, it has been shown that the second factor D2 may be different for different SL states. This means that the crystal field parameters are no longer independent of free‐ion states. If this mechanism is important, the crystal field parameters determined in fitting observed states in the narrow energy range of the low‐lying multiplets give an inadequate description of the crystal‐field splittings of the multiplets at higher energies.

18.5 INTERPRETATION OF THE OBSERVED SPECTRA OF TRIVALENT ACTINIDE IONS

Most of the actinide elements may be easily stabilized as trivalent ions in solids. Accordingly, a majority of the spectroscopic studies of actinides has been performed on the trivalent ions in 5fN configurations. Whereas higher oxidation states can be stabilized for the lighter members in the first half of the actinide series, the 3þ oxidation state is most stable for the spectroscopically studied heavier actinides in condensed phases. Spectroscopic analyses and empirical modeling of the free‐ion and crystal‐field Hamiltonian were successfully conducted first on the trivalent ions using the model Hamiltonian reviewed in Section 18.4.6. Similarities are found between the series of trivalent actinide and lanthanide ions in terms of free‐ion interactions and crystal‐field splittings of the energy levels of the f‐electrons. When the results of a Hartree–Fock calculation are compared to those of a parametric analysis of experimentally identified levels for a given element, the magnitude of the computed energies, particularly those for F k, are generally found to be too high. For a more realistic Hamiltonian, using parametric approach, one can apply subtractive corrections to the estimates derived from ab initio calculations. These corrections turn out to be essentially constant over the series and almost identical for both 4fN and 5fN shells (Crosswhite, 1977; Liu, 2000). The significance of this is that mixing with high configurations can be taken as essentially a fixed contribution to a global parametric model (Crosswhite and Crosswhite, 1984; Carnall, 1992; Liu et al., 1994b). Many of the early spectroscopic studies of actinides in solids were conducted on actinide chlorides or trivalent actinide ions doped into crystals of LaCl3 (Carnall, 1992), which can incorporate the actinide series from U3þ through Es3þ as impurities that substitute at the La3þ lattice site (C3h symmetry). These studies, supplemented by Zeeman‐effect studies of the influence of applied magnetic fields on the energy levels, provided the basis for experimental

Interpretation of the observed spectra of trivalent actinide ions

2057

characterization of the observed transitions in terms of the free‐ion SLJ and crystal field quantum numbers. The available data for the 5fN energy levels of trivalent actinide ions in LaCl3 and actinide chlorides have enabled a systematic analysis and modeling of the 5fN energy level structure (Carnall, 1992). The significance of such a systematic analysis and theoretical modeling, like that for the lanthanide series in LaCl3 and LaF3, is to provide a fundamental understanding of the electronic properties of actinides in solids along with values of free‐ion interaction parameters that can be used for analyzing the spectra of the actinide ions in other compounds and solutions. The relative energies of some of the low‐lying states in U3þ:LaCl3 are shown in Fig. 18.6 (Crosswhite et al., 1980). As indicated, each free‐ion state is split by the crystal field. When measured at the temperature of liquid He (4 K), only transitions from the lowest state (taken as the zero of energy and having a

Fig. 18.6 Absorption spectrum of the crystal‐field splittings of U3þ:LaCl3 in the range 11 000–11 800 cm1at 4 K. (Reprinted with permission from Crosswhite et al., 1980. Copyright 1980, American Institute of Physics.)

2058

Optical spectra and electronic structure

crystal field quantum number m ¼ 5/2 in this case) are observed. Most of the experimental results that have been reported were photographed using high‐resolution grating spectrographs. Transitions to only three levels 4I11/ 2 were readily observed in absorption; that to a m ¼ 1/2 state (found by other techniques near 4580 cm1) were too weak to be apparent. Fig. 18.6 shows the absorption spectrum of U3þ:LaCl3 in the range of 11 000 cm1. Lines in this spectrum are attributed the multiplets of 4G5/2, 4I15/2, 4S3/2, and 4F7/2 (Carnall, 1992). Electric dipole selection rules between the ground (m=5/2) and excited (m=5/2) states show that absorption transitions are forbidden, so the levels that would have corresponded to absorption transitions at 4556 and 4608 cm1 had to be established by fluorescence methods. Assigning energies corresponding to the centers of these components, thus defining the ‘free‐ion’ levels for the ion in a particular medium yields the energy level scheme indicated at the left in Fig. 18.7. Although the levels are shifted to somewhat lower energies than those of the true gaseous free‐ion states, the basic structure appears to be preserved and is usually only moderately changed from medium to medium for trivalent lanthanides and actinides. For example, the center of gravity of the 4 I11/2 state in U3þ:LaCl3 in Fig. 18.7 is 4544 cm1. As the energies of the components of various groups are established experimentally, the model free‐ion and crystal field parameters that reproduce the splittings can be computed by a suitable (nonlinear least‐squares) fitting procedure. The computed values are then used to predict the splitting patterns in other groups where not all of the allowed components can be observed. Thus in the analysis of such spectral data there is a continual interplay between theory and experiment. When large numbers of levels have been experimentally confirmed, most (in some cases, all) of the parameters of the model can be varied simultaneously to establish the final values (Table 18.4). Fig. 18.8 shows the calculated energy levels that result from crystal‐field splitting for An3þ in LaCl3 (Carnall, 1992). In typical analyses of actinide and lanthanide spectra in condensed phases, the range of observation may extend well into the near‐ultraviolet region. The number of assignments made to different multiplets and states is usually sufficient to determine most of the energy level parameters. However, in Fig. 18.8 some of the observations on which this diagram is based were limited to less than 50% of the total extent of the fN configurations. The accuracy of predicted energy level in the ultraviolet range clearly remains to be thoroughly tested. The Slater parameters in An3þ are typically only two‐thirds as large as those for the Ln3þ, but z5f is a factor of 2 larger than z4f ; so while the total energy range of the 5fN configuration is reduced, the states are significantly more mixed in character because of the increased spin–orbit interaction. The lanthanide orthophosphates, such as LuPO4 and YPO4, are good hosts for the incorporation of dilute fN impurities. A wide variety of lanthanide and actinide ions, diluted in these materials, have been produced to carry out fundamental spectroscopic investigations (Morrison and Leavitt, 1982; Go¨rller‐Walrand and Binnemans, 1996). For the actinide series, Cm3þ doped

Interpretation of the observed spectra of trivalent actinide ions

2059

Fig. 18.7 Energy level structure for U3þ:LaCl3.

into LuPO4 and YPO4, has been the most extensively studied system (Murdoch et al., 1996, 1997; Liu et al., 1998). The greater spatial extent of the 5f electron shell results in a smaller electrostatic interaction between equivalent electrons in the 5f shell than in the 4f shell. Thus for Cm3þ, the energy level of the first excited multiplet (J ¼ 7/2) is at 16 000 cm1. Utilizing this metastable emitting state, excited state absorption studies allowed the collection of data to

2060

Optical spectra and electronic structure

Fig. 18.8 Energy level structure of An3þ:LaCl3 based on computed crystal field energies in the range 0–40 000 cm1. (Reprinted with permission from Carnall, 1992. Copyright 1992, American Institute of Physics.)

40 000 cm1 using two visible lasers (Murdoch et al., 1997). The ground term multiplet splitting is small, because the largest component of the ground multiplet has zero angular momentum. Early detailed studies of the Cm3þ optical spectra were performed with the 244Cm isotope. During the past decade or so, multimilligram quantities of 248Cm have become available. Several single crystals were doped with the 248Cm isotope and optical studies of these samples

Interpretation of the observed spectra of trivalent actinide ions

2061

were performed using laser‐selective excitation and fluorescence techniques. Edelstein (2002) has recently published a review of the spectroscopic studies of Cm3þ in various hosts. The free‐ion model based on studies of the 3þ actinide ions in LaCl3 has been used in analysis of the optical spectra of Cm3þ in LuPO4. For the crystal‐field splitting, because the metal ion site is D2d in the phosphates instead of C3h in LaCl3, a different set of crystal field parameters must be established. Fig. 18.9 shows the excitation spectra of Cm3þ in LuPO4 (Fig. 18.9a) and YPO4

Fig. 18.9 Excitation spectra of transitions from the 8S7/2 ground state multiplets to the 6 D7/2 excited state of the Cm3þ ion in (a) LuPO4 and (b) YPO4 at 4 K. (Reprinted with permission from Liu et al., 1998. Copyright 1998, American Institute of Physics.) The emission was monitored at 16 563.0 cm–1 for Cm3þ:YPO4 and 16 519.5 cm–1 for Cm3þ: LuPO4. The insert shows the crystal‐field splitting of the ground state of Cm3þ in YPO4.

2062

Optical spectra and electronic structure

(Fig. 18.9b) in which the crystal field energy levels for the first excited multiplet (nominal 6D7/2) were observed to extend from 16 560 to 17 200 cm1. In addition to the zero‐phonon lines (ZPL) indicated by the vertical arrows, vibronic sidebands have intensities comparable to those of the upper ZPLs. The insert in Fig. 18.9b shows the crystal‐field splitting in the ground state which also is a J ¼ 7/2 (nominal 8S7/2). Whereas the excited state crystal‐field splitting is more than 800 cm1, the ground state splitting is only 12 cm1. As pointed out in Section 18.4.2, the crystal‐field interaction vanishes in the ground state of an f7 configuration unless a fourth‐order coupling to the excited states is considered (Liu et al., 1993). Although the excited 6D7/2 also has no first‐order crystal‐field splitting, the more significant mixture of LS terms in its wave functions results in much larger crystal‐field splitting. Many experimental results of the ground state splitting of actinide ions in the 5f7 configuration, which include Am2þ, Cm3þ, and Bk4þ in different crystalline hosts, have been reported (Edelstein and Easley, 1968; Liu et al., 1996; Murdoch et al., 1996; Brito and Liu, 2000). In different hosts, the values for the An3þ free‐ion parameters listed in Table 18.4 may vary 1% or less. In fitting the Cm3þ:LuPO4 (or YPO4) data, the parameters of three‐body coupling operators, T k, were kept fixed at the values for Cm3þ in LaCl3 (Murdoch et al., 1996, 1997). The energy levels of Cm3þ in LuPO4 up to 35 000 cm1 were probed by high‐resolution techniques using two‐ step excited state absorption and one color two‐phonon absorption methods (Murdoch et al., 1997). The modeling of the Cm3þ:LuPO4 energy level structure with the experimental data up to 35 000 cm1 did not result in significant changes in the free‐ion parameters determined in the systematic analysis of the 5fN ions in LaCl3. This consistency leads to two important conclusions as regards the applications of the free‐ion and crystal field model: (a) the free‐ion interaction parameters are relatively insensitive to host lattice; and (b) the parameters determined by analysis of the low‐lying energy states can reproduce energy levels of high‐lying states with satisfactory accuracy. In appropriate hosts, the 5D1 state of Am3þ (5f 6 configuration) is a metastable emitting state as is the 6D7/2 state of Cm3þ (5f7 configuration) (Carnall, 1992). In such cases, both ions emit visible luminescence so they are very suitable for laser‐induced fluorescence excitation studies. In addition to LaCl3 and LuPO4, these two ions in other crystalline hosts such as Cs2NaYCl6 (Murdoch et al., 1998), ThO2 (Hubert et al., 1993; Thouvenot et al., 1993a, 1994), and CaWO4 (Liu et al., 1997a,b) have been investigated using laser spectroscopic methods. These studies showed that Am3þ and Cm3þ exhibit spectroscopic properties that are similar to those found in studies in LaCl3, although the strength of the crystal‐field interaction may be significantly different. Table 18.9 provides a comparison between the free‐ion and crystal‐field interactions of Eu3þ and Am3þ both of which have the f 6 configuration. The ratios of free‐ion interactions and crystal field strength for the 4f and 5f ions listed in Table 18.9 indicate that the electrostatic interaction is reduced approximately to 60% and the spin–orbit coupling is increased by 190%

Interpretation of the observed spectra of trivalent actinide ions Table 18.9 Comparison of interaction parameters of Am

3þ

F 2(Eu3þ) F 2(Am3þ) F 2(Am3þ)/F2(Eu3þ) z4f (Eu3þ) z5f (Am3þ) z5f (Am3þ)/z4f (Eu3þ) Nn(Eu3þ) Nn(Am3þ) Nn(Am3þ)/Nn(Eu3þ) a b

2063

(5f ) and Eu (4f ) (cm1). 6

3þ

6

LaCl3a

ThO2b

84 400 51 900 0.62 1 328 2 564 1.93 329 628 1.9

80 335 48 038 0.60 1 337 2 511 1.88 1 231 2 953 2.4

Carnall (1992) and Crosswhite (1977). Hubert et al. (1993).

Fig. 18.10 Comparison of the parameter ratios for trivalent lanthanide and actinide ions in LaCl3 (Data from Crosswhite, 1977 and Carnall, 1992).

(Edelstein and Easley, 1968) for the values of the lanthanide analogs in the same fN configuration. These changes are attributed to the more extended 5f orbitals of Am3þ in comparison with the 4f orbitals of Eu3þ. In addition, the strength of the crystal‐field interaction is doubled for the actinide ion. This trend of

2064

Optical spectra and electronic structure

variations is shown systematically in Fig. 18.10 for the two series of ions in the LaCl3 crystal lattice (Liu, 2000). Edelstein and Easley (1968) observed the trivalent state for 243Am and 244Cm doped into CaF2 when the crystals were initially grown. However, due to the high level of radioactivity caused mainly by the alpha decay of 244Cm (t1/2 ¼ 18.1 years) part of the Am3þ was reduced to Am2þ and part of the Cm3þ was oxidized to Cm4þ. It was observed that the ratio of Am2þ to Am3þ in the cubic sites of CaF2 was approximately 10:1. The energy level structures of Am2þ and Cm3þ in CaF2 were probed and analyzed based on the crystal field model for 5f7 configuration (Edelstein et al., 1966; Edelstein and Easley, 1968). A recent study (Beitz et al., 1998) reported that Es3þ (5f10) can be stabilized in LaF3 and its spectroscopic properties in terms of free‐ion interactions are very similar to Es3þ in LaCl3, although a crystal field strength approximately twice of that for Ho3þ (4f10) in LaF3 is expected. Although the spectra of several organometallic 3þ actinides, such as plutonium tricyclopentadienide, have been measured, the analysis of data is still quite incomplete (Carnall, 1979b). Nevertheless, it seems apparent that now the energy level parameters for such systems can be approximated by those characteristics of the trivalent actinide in the LaCl3 host. There have been several recent laser spectroscopic studies on U3þ ions in various ternary chloride and bromide crystalline systems. Because of relatively low‐phonon energies of lattice vibration, strong luminescence from U3þ can be observed in these crystals. Using effective‐operator Hamiltonian and parameterization method, Karbowiak and colleagues have analyzed the absorption and emission spectra of U3þ in Ba2YCl7, CsCdBr3, and Cs2NaYBr6, respectively. Both U3þ and U4þ were observed in the Ba2YCl7 system, which possesses monoclinic symmetry. For uranium ions at a C1 site, a total of 27 crystal field parameters are required to calculate the energy levels (Karbowiak et al., 1997, 2003). Using time‐resolved and site‐selected laser excitation methods, this group has investigated the spectroscopic and excited state dynamics of U3þ in RbY2Cl7. The strength of the free‐ion and crystal‐field interaction in these systems is generally consistent with that for the U3þ:LaCl3 systems. A general correlation between the magnitudes of crystal field parameters and the U3þ luminescence decay rate has been realized in the analyses of the site‐selected spectra and luminescence dynamics.

18.6 INTERPRETATION OF THE OBSERVED SPECTRA OF TETRAVALENT ACTINIDE IONS

It is well known that a major difference between the lanthanide and actinide series is the greater stability of 4þ and higher valance states of the actinides, particularly in the first half of the respective series. There have been numerous analyses of the spectra of tetravalent uranium compounds, whereas the number

Interpretation of the observed spectra of tetravalent actinide ions

2065

of published spectroscopic analyses rapidly decreases as heavier members of the actinide series in the 4þ valence states are considered. The reasons are, first of all, differences in stability of the tetravalent state for actinide compounds are such that reducing and then oxidizing conditions become necessary as the actinide atomic number increases. Secondly, the low specific radioactivity of uranium of natural isotopic abundance makes the doped crystalline materials easy to handle and limits radiolytic degradation. Moreover, the f2 configuration of U4þ provides experimental features that are suitable for theoretical analyses and constitute a useful basis for extending the interpretation of spectra of other An4þ ions in condensed media. There is a series of crystalline hosts, notably ThX4 and Cs2MX6 (M ¼ Zr, Th; X ¼ Cl, Br), ThSiO4, and ZrSiO4, in which Pa4þ(5f) and U4þ(5f2) can be doped for spectroscopic studies (Krupa, 1987). In addition, Np4þ, Pu4þ, and Am4þ have been successfully doped into ThSiO4 (Krupa et al., 1983; Krupa and Carnall, 1993). However, in contrast to most other binary compounds, the tetravalent actinides as fluorides are sufficiently stable and PaF4 through CfF4 can be prepared and are isostructural to UF4 and CeF4 (Brown, 1968; Morss, 2005). Since 1986, significant progress in analyses of the crystal field spectra of tetravalent actinide ions in solids has been reported. The structural characteristic of f!f transitions has been observed and analyzed using the theoretical model of free‐ion and crystal‐field interactions that was discussed in Sections 18.3 and 18.4. The observations are consistent with trends indicated in Fig. 18.1, which suggest that transitions to the fN1d configurations in An V will lie even higher in energy relative to the lowest‐energy fN state than in the corresponding transitions for An IV. The lowest f!d transition in the atomic spectrum of U V was assigned at 59 183 cm1 (Van Deurzen et al., 1984). Consequently, broad and intense band structure in the spectra of An4þ compounds beginning near 40 000–45 000 cm1 would be consistent with the onset of f!d transitions. The energy level structure of the free‐ion U4þ (5f2) configuration has provided a valuable basis for comparison in developing the analysis of An4þ spectra in solids. Krupa (1987) reviewed spectroscopic properties of Pa4þ(5f1), U4þ(5f2), and Np4þ(5f3) in crystalline host ThBr4, ThCl4, and ThSiO4. For Pa4þ in Cs2ZrCl6, electron paramagnetic resonance and near‐infrared absorption spectra were measured and the data analyzed by Axe et al. (1961) in terms of the crystal‐ field and spin–orbit interactions for a 5f1 electron. Additional optical studies have been reported for pure Pa4þ hexahalo compounds and Pa4þ diluted into Cs2ZrCl6 (Brown et al., 1974, 1976; Edelstein et al., 1974, 1992; Piehler et al., 1991). For this one‐electron system, there are no electrostatic terms for the free‐ ion interactions, thus the splitting of the free‐ion energy states, which consist of the 2F5/2 ground state and the 2F7/2 excited state, is solely due to spin–orbit coupling. Crystal‐field splittings in the tetravalent ions are much larger than those of the trivalent ions. Table 18.10 lists the spectroscopic parameters of Pa4þ in ThCl4 and ThBr4 in D2d symmetry (Malek and Krupa, 1986; Krupa,

Optical spectra and electronic structure

2066

Table 18.10 Energy parameters of Pa4þ and U4þ in ThCl4, ThBr4, and ThSiO4 in D2d symmetry (cm1).a Pa4þ ThCl4 F F4 F6 z a b g B20 B04 B44 B06 B46 nb sb

U 4þ ThBr4

2

a b

1524.4(5)

1532.8(5)

1405(50) 1749(94) 2440(98) 2404(607) 195(267) 7 23.6

1047(52) 1366(138) 1990(102) 1162(541) 623(174) 7 19.4

ThCl4

ThBr4

ThSiO4

42 752(162) 39 925(502) 24 519(479) 1808(8) 30.4(2) 492(84) [1200] 1054(117) 1146(200) 2767(147) 2315(404) 312(227) 25 46

42 253(127) 40 458(489) 25 881(383) 1783(7) 31(1) 644(75) [1200] 1096(80) 1316(146) 2230(85) 3170(379) 686(246) 26 36

43 110(245) 40 929(199) 23 834(639) 1840(2) 32.3(0.4) 663(144) [1200] 1003(127) 1147(281) 2698(251) 2889(557) 208(333) 25 71

Krupa (1987). Number of assigned levels (n) and deviation (s), see Table 18.4, footnote c.

1987). The data for Pa4þ in Cs2ZrCl6 are considerably better than for the ThX4 systems. Also some data are given for the excited 6d system. Analysis of the spectra of U4þ in both high‐symmetry (Oh) and relatively low‐ symmetry (D2d and D2) sites have been published. Somewhat in contrast to observations made with trivalent ions, the magnitude of the crystal‐field splitting in the two cases differs significantly. An example of the high‐symmetry case is that of U4þ in Cs2UCl6 (Johnston et al., 1966a,b). The low‐symmetry (D2d) case is illustrated in the analysis of U4þ:ThBr4 (Delamoye et al., 1983). Recently, spectroscopic analyses were reported by Karbowiak et al. (2003) for U4þ in Ba2YCl7. In this work, values of the 27 crystal field parameters of the Hamiltonian were determined in fitting a total of 60 observed crystal field energy levels to the model Hamiltonian. The crystal‐field splitting in the Cs2UCl6 is over twice as large as that in U4þ:ThBr4. As a result, much more complex structure caused by the mixing of states of different J in close proximity occurs within a given energy range in Cs2UCl6 compared to the U4þ:ThBr4 case. In the analyses of the crystal field spectrum of U4þ on the octahedral sites of Cs2UBr6 and Cs2ZrBr6, Faucher et al. (1996) reported that there is a strong coupling between the 5f2 and 5f17p1 configurations. Therefore, additional effective operators for the configuration interaction are necessary to better interpret the observed energy level structure. The extensive analysis of the data for U4þ:ThBr4 and the similar crystal field parameters deduced for Pa4þ:ThCl4 (Krupa et al., 1983) have provided a new

Interpretation of the observed spectra of tetravalent actinide ions

2067

basis for examining other An4þ spectra. As Auzel and coworkers have shown (Auzel et al., 1982), band intensities in the spectrum of aquated U4þ can be assigned in terms of crystal‐field split SLJ levels similar to those deduced for U4þ:ThBr4. Using the method of extrapolation discussed in Sections 18.3 and 18.4, energy level parameters that are consistent with those for Pa4þ:ThCl4 and U4þ:ThBr4 can be extrapolated to obtain a set for Np4þ, and a good correlation is found between this energy level structure and the band structure observed for aquated Np4þ. That the apparent correlation between band structure observed for the iso‐f‐electron configurations of aquated An4þ and aquated An3þ ions continues along the series is evident when comparing the spectra of aquated Pu4þ and aquated Np3þ. Jørgensen called attention to this apparent correlation in the band structure observed for the iso‐f‐electron configurations An3þ and An4þ spectra at a time when little was known about the extent of the ligand fields involved (Jørgensen, 1959). Concern that the data for aquated An4þ should be interpreted in terms of large ligand‐field splitting characteristic of Cs2UCl6, instead of a weaker‐field case may have been partially responsible for the slow pace in exploration of Jørgensen’s insight. Of course, development of this An3þ/An4þ spectral correlation also required an understanding of the energy level structures in An3þ, which was not well understood in 1959. Adopting the electrostatic and spin–orbit parameters for U4þ:ThBr4 as a basis for estimating parameters for the An4þ ions, the general character of the spectra of the An4þ ions can be interpreted (Conway, 1964). In solid compounds such as Cs2UCl6, where the 4þ ions occupy sites of inversion symmetry, the observed structure is almost exclusively vibronic in character, as contrasted with the electronic transitions characteristic of 3þ compounds. The electronic origins were deduced from progressions in the vibronic structure, because the electronic transitions themselves were symmetry‐forbidden. An analysis of the intensities of vibronic bands has been reported (Satten et al., 1983; Reid and Richardson, 1984). Other extensive analyses of the spectra of U4þ in crystalline hosts include those for U4þ:ZrSiO4 (Richman et al., 1967; Mackey et al., 1975). Because of much stronger ion–lattice coupling for the 6d orbitals, in contrast to the 5f5f transitions in which vibronic coupling is relatively weak, the spectra of 5f$6d transitions, however, are often dominated by the vibronic bands associated with the fd electronic transitions in both absorption and emission spectra even when there is no inversion symmetry. The assignment and analyses of the crystal field spectra become difficult, because the pure electronic transitions (ZPL) may be obscured by the broad and intense vibronic sidebands. Fig. 18.11 shows the emission spectrum of the 6d2D3/2 (G8g) !5f2F5/2 (G8u) electronic transition of Pa4þ:Cs2ZrCl6, with the zero‐phonon line at 17 847 cm1 accompanied by various vibronic sidebands (Piehler et al., 1991). From the optical spectra, the vibrational frequencies of different modes can be measured and assigned to the local and lattice modes that couple to the electronic transitions. In the 5f6d spectra (see Fig. 18.11), and also in charge‐transfer spectra

2068

Optical spectra and electronic structure

Fig. 18.11 The emission spectrum of the 6d 2 D3=2 ðG8g Þ ! 5f 2 F5=2 ðG8u Þelectronic vibronic transitions for Pa4þ in Cs2ZrCl6 at 4.2 K (experimental data from Piehler et al., 1991). The energy of the zero‐phonon line of the electronic transition is 17 847 cm1. The vibrational frequencies obtained from fitting the spectrum are n1(A1g) ¼ 310 cm1, n5 (T2g) ¼ 123 cm1, nL1 (T1g ) ¼ 35 cm1, and nL2 (T2g ) ¼ 55 cm1.

(discussed later), certain vibrational progression frequencies have harmonics up to fifth order, whereas others appears only to first order. Liu et al. (2002) demonstrated recently that the progressions of multiple vibrational frequencies can be simulated using a modified model of the Huang–Rhys theory of electron– phonon interaction (Huang and Rhys, 1950). The dashed line in Fig. 18.11 is a model fit to the experimental spectrum. A systematic analysis of crystal field spectra has been reported for tetravalent actinide ions from U4þ through Bk4þ in AnF4 and An4þ:CeF4 (Carnall et al., 1991; Liu et al., 1994b). The tetravalent fluorides were chosen because An4þ (An ¼ U to Cf) can be stabilized and they all, including CeF4, which has no f‐electron in the lowest‐energy configuration, are isostructural. The absorption spectrum of UF4 is plotted in Fig. 18.12 in comparison with that of U4þ ion in aqueous solution, and the liquid helium temperature absorption spectra of NpF4 and PuF4 are shown in Fig. 18.13 (Carnall et al., 1991). Crystal structure data for UF4 established that there are two different low‐symmetry sites, C1 and C2, for the An4þ ion. Both sites have eight nearest neighbor fluorine ions arranged in a slightly distorted antiprismatic configuration; however, there are twice as many C1 as C2 sites in the unit cell which aids in identifying sites in the site‐resolved spectra. The site‐selective excitation spectra of the 7F05L6 transitions are shown in Fig. 18.14 for a 0.1% Cm4þ:CeF4 sample at 4.3 K. Crystal field modeling was conducted based on an approximate C2 site symmetry. The spectra have similar characteristics as those of An3þ ions in crystals

Interpretation of the observed spectra of tetravalent actinide ions

2069

Fig. 18.12 Absorption spectra of (a) UF4 in a KBr pellet at 4 K; (b) aquated U4þ at 298 K both in the near‐infrared to visible range. (Reprinted with permission from Carnall et al., 1991. Copyright 1991, American Institute of Physics.)

(see Fig. 18.9 for Cm3þ:LuPO4). Sharp ZPL are resolved in the low‐energy region and broad vibronic transitions that span 800 cm1 with the strongest features 400 cm1 above the first ZPL are also found. The vibronic lines in the An4þ spectra are relatively stronger than those in An3þ spectra. This suggests a stronger ion–ligand coupling for tetravalent ions, which is consistent with the larger crystal‐field splittings in the An4þ systems. Optical spectroscopic data, including low‐temperature absorption (see Figs. 18.12 and 18.13) and laser excitation and luminescence spectra of tetravalent actinides in fluoride compounds, have provided adequate experimental information for a systematic analysis and parameterization of the free‐ion and crystal‐field interactions. The Hamiltonian of the free‐ion and crystal‐field interactions has been established through the same parameterization method used for the trivalent ions that was discussed in Section 18.5. The Hamiltonian parameters for An4þ in CeF4 are listed in Table 18.11. The parameterization method ensures a consistent set of free‐ion and crystal field parameters from one ion to the next. Given the limited number of energy levels that could be assigned

2070

Optical spectra and electronic structure

Fig. 18.13 Absorption spectra of (a) NpF4 in a KBr pellet at 4 K; (b) PuF4 in KBr pellet at 4 K in the range 4000–30 000 cm1. (Reprinted with permission from Carnall et al., 1991. Copyright 1991, American Institute of Physics.)

without ambiguity, the observed spectra of AnF4 were modeled based on the standard model crystal field with constrained parameters. For instance, the three‐body parameters T i were fixed at average values determined in the analysis of An3þ:LaCl3 spectra (Carnall, 1992). The Mh values were assigned in each case based on ab initio calculations and were not varied. Although P2 was varied, in all cases P4 and P6 were constrained by the ratios P4 ¼ 0.5P2 and P6 ¼ 0.1P2. In fitting experimental data, the modeling, therefore, relied on the systematic variations of Fk and z5f. In UF4, it was pointed out that the magnitude of the crystal‐field interaction was relatively large, and J‐mixing was very significant in higher energy states, the ground crystal field state remained more than 95% pure in terms of J‐character. Although the excited states above 50 000 cm1 were truncated in the construction of the free‐ion wave functions for Pu4þ, Am4þ, Cm4þ, and Bk4þ, the ground state eigenfunctions had relatively pure J‐character, fully consistent with the results for U4þ and Np4þ. The nominal 6 H5/2 ground state in Am4þ is more than 96% J ¼ 5/2, whereas the 7F0 ground state in Cm4þ is more than 98% J ¼ 0 character. Thus the experimental problem of interpreting magnetic susceptibility measurements in CmF4 where temperature‐dependent results are not consistent with a J ¼ 0 ground state (Nave

Interpretation of the observed spectra of tetravalent actinide ions

2071

Fig. 18.14 Site‐elective excitation spectra of the 7F05L0 transitions in 0.1% Cm4þ:CeF4 at 4.3 K. (a) The spectrum of Cm4þ ions on site A recorded with emission at 16 603 cm1; (b) the spectrum of Cm4þ on site B recorded with emission at 16 584 cm1; and (c) the excitation spectrum without emission selection. The broad features in the high‐energy range are due to vibronic transitions. (Reprinted with permission from Liu et al., 1994b. Copyright 1994, American Institute of Physics.)

et al., 1983) seems unlikely to be rationalized by assuming appreciable J‐mixing. For Bk4þ, the J ¼ 0 character is more than 99.5%, but the contribution from the pure 8S7/2 is reduced to 75.5% (Brito and Liu, 2000). Systematic analysis of the free‐ion and crystal‐field interactions in AnF4 (An ¼ U–Bk) provides a useful comparison of the trends in free‐ion parameter values between those that would have been expected based on parameters computed using ab initio methods and those obtained from fitting the experimental data. As shown in Fig. 18.15, when plotted as a function of atomic number, the model free‐ion parameters for An4þ exhibit similar increasing trends as those predicted by Hartree–Fock calculations. However, the normalized Hartree–Fock‐based values of F k were typically found to show a steeper slope than those obtained in fitting the experimental data.

Optical spectra and electronic structure

2072

Table 18.11 Energy‐level parameters for tetravalent actinide ions in actinide tetrafluorides (in cm–1) (Liu et al., 1994a,b).a U 4þ

Np4þ

Pu4þ

Am4þ

Cm4þ

Bk4þ

F2 F4

44 784 43 107

53 051(38) 0.893F 2

55 300 0.88F 2

25 654

0.61F 2

0.619F 2

0.60F 2

z a b g T2 T3 T4 T6 T7 T8 M 0,b M2 M4 P 2,c B20 B22 B04

1761(3) 34.74 767.3 913.9

0.775 0.434 0.294 2715(94) 1183(28) 29(27) 2714(99)

50 000 44 500 (0.89F 2) 30 500 (0.61F 2) 2315(7) 35 740 900 200 50 50 360 425 340 0.984 0.546 0.381 2200 1127 45 2818

51 824(47) 0.89F 2

F6

2604(6) 35 740 900 200 50 50 360 425 340 1.094 0.608 0.424 1623(71) 1302(59) 45 2822

3017(5) 35 740 900 200 50 50 360 425 340 1.204 0.671 0.468 633(96) 1209(75) 45 2820

3244 34 740 1000 200 50 50 360 425 340 1.314 0.733 0.512 1064 1150 45 2720

B24

3024(71)

3090

3219(135)

3304(99)

3000

B44

3791(53)

3584

3337(101)

3243(90)

3275

B60

1433(148)

1427

1500

1500

1700

B26 B46

1267(101) 1391(93)

1267 1147

1400 1147

1400 1142

1500 1200

B66

1755(82)

1819

1819

1820

1800

sd nd

31 69

47 630 42 702 (0.896F 2) 29 623 (0.622F 2) 2021(4) 34.89 743.2 890.7 200 50 50 360 425 340 0.877 0.489 0.340 2700 1127(92) 45 2818 (193) 3090 (171) 3584 (170) 1427 (382) 1267 1147 (181) 1819 (129) 41 57

30 23

31 61

28 38

27 25

a b c d

The values in parentheses are errors in the indicated parameters. The M k values were assigned in each case based on ab initio calculation and were not varied. P 2 was varied freely, P 4 and P 6 were constrained by ratios P 4 ¼ 0.5P 2, P6 ¼ 0.1P 2. Deviation (s) and number of assigned levels (n), see Table 18.4, footnote c.

It has been shown that a significant change in the ratios of F 4/F 2 and F 6/F 2 from U4þ to Np4þ is required to fit the experimental data (Carnall et al., 1991; Liu et al., 1994b). However, in the analysis of the transneptunium ions, the ratios of F 4/F 2 and F 6/F 2 could be held constant. In this context, values of F2

Interpretation of the observed spectra of tetravalent actinide ions

2073

Fig. 18.15 Systematic trends in free‐ion parameters of the effective‐operator Hamiltonian for AnF4 (An ¼ U through Bk). The dots (
) connected by the dashed lines are calculated using Hartree–Fork methods, and the squares (□) connected by solid lines are from fitting experimental data. All values are normalized to those for NpF4. (Reprinted with permission from Liu et al., 1994a,b. Copyright 1994, American Institute of Physics.)

for all the ions studied exhibited a functional (but not linear) increase with atomic number. It is important to note that the values of F2 for all transneptunium members of the AnF4 series would be poorly estimated based solely on linear projections from U4þ or Np4þ. Similar to the An3þ series, a regular behavior appears to be characteristic of the transneptunium actinide tetrafluorides. The computed values of z5f from fitting the experimental data are generally quite consistent with ab initio values normalized to agree with the empirical value for NpF4. In comparison to the An3þ series, the slope found for the variation of F k for An4þ as a function of atomic number is reduced. This is particularly evident for F2 in Fig. 18.15 and provides the rationale for increasingly similar energies found in the lower energy free‐ion states of iso‐f‐electron An3þ and An4þ spectra as a function of increasing atomic number. The parametric free‐ion electrostatic interaction parameters F k for UF4 and NpF4 are a few percent larger than those that have been determined by fitting spectroscopic data for the tetravalent chlorides and bromides listed in Table 18.10, and those for UF4 are smaller than the gaseous free‐ion values for UV

2074

Optical spectra and electronic structure

(Van Deurzen et al., 1984), as expected. Indeed all the free‐ion parameter values used in the analysis of AnF4 spectra are fully consistent with those available from other analysis of An4þ spectra in a variety of crystal environments (Krupa, 1987). For tetravalent actinide ions, it is useful to emphasize that the crystal field is no longer a small interaction relative to that of the free ion, but is capable of radically transforming the energy level scheme without any change in magnitude in the free‐ion interaction parameters. This is readily evident in comparing the parameters and energy level schemes for UCl4 and Cs2UCl6. One of the consequences of this change in the hierarchy of interactions that comprise the theoretical model is that there is a decreased sensitivity in energy level structure calculations to the values of the F k integrals in the analysis of An4þ compared to An3þ and Ln3þ spectra. This is a direct result of the stronger crystal‐field and spin–orbit interactions. Recognition of this fact is important because it explains the relatively uncertain F k values obtained from fitting experimental data. In most cases, very few free‐ion states are actually included in the calculation. Indeed, those states that are included tend to be the lowest‐energy states in the configuration and to exhibit the smallest J‐mixing that would aid in defining the parameters. Most of the experimental data from absorption spectra include contributions from An4þ ions on two crystallographic sites. One of the basic aspects of modeling the AnF4 crystal field spectra is the reliance, not only on the results of a model calculation of the crystal field parameters in the actual C2 symmetry, but also the assumption that for purposes of interpreting the observed energy level structure, it is possible to use an approximate C2v symmetry. It was shown that the predictions that were made as a result of this approximation could be directly related to the observed structure and were consistent with the few available measurements that had been obtained independently. In fact, as shown in Table 18.11, very little change in crystal field parameter values over the series was required. This again confirms the arguments in Section 18.4.3 on using the descent‐of‐symmetry method to simplify the analysis of crystal field spectra of lanthanide and actinide ions in crystals of low symmetry. In the history of f‐element spectroscopy, theoretical interpretations of the crystal‐field splitting of the 8S7/2 ground state in a half‐filled shell of the f7 configuration have been contradictory. The lanthanides in such a configuration are Eu2þ, Gd3þ, and Tb4þ; and the actinide ions include Am2þ, Cm3þ, and Bk4þ. Early arguments were focused on the Gd3þ ion because the ground state crystal‐field splitting observed in EPR experiments was less than 0.5 cm1 (Hubert et al., 1985) and could not be interpreted by the crystal field theory. A series of mechanisms were considered but failed to provide a consistent interpretation (Wybourne, 1966; Newman, 1970, 1975). However, the 8S7/2 ground‐state splittings in the actinide ions is much larger than that of the Gd3þ. For Am2þ and Cm3þ, the observed splitting varies from 2 to 20 cm1

Interpretation of the observed spectra of tetravalent actinide ions

2075

Fig. 18.16 Partial energy level diagrams of Gd3þ, Cm3þ, and Bk4þ based on computed and experimental crystal field energies. (Reprinted with permission from Brito and Liu, 2000. Copyright 2000, American Institute of Physics.)

(Edelstein and Easley, 1968; Liu et al., 1993; Murdoch et al., 1996; Edelstein, 2002), while for Bk4þ it is on the order of 60 cm1 (Liu et al., 1994b; Brito and Liu, 2000). As a summary of previous work on the 5f7 ion, a comparison of the crystal‐ field splittings of Gd3þ, Cm3þ, and Bk4þ ions including the ground‐state splitting is shown in Fig. 18.16. For the 5f7 systems, no additional mechanisms other than the crystal‐field interaction are needed to provide a satisfactory interpretation to the observed splitting in the 8S7/2 ground state of actinide ions (Liu et al., 1993; Brito and Liu, 2000). As indicated in Section 18.4.2, the observed crystal‐field splittings must be attributed to the contributions of the mixture of other LS terms into the ground state free‐ion wave function (see equation (18.39)) and nonzero off‐diagonal matrix elements between different J‐multiplets. Because of the large energy gaps from the ground state to the excited multiplets of Gd3þ, the excited state LS components in the ground state is small, and J‐mixing is also negligible in this case. However, for the actinide ions in 5fN configurations, as discussed in Section 18.3, the ground‐state wave

2076

Optical spectra and electronic structure

functions contains considerable LS components of the excited states, and thus lead to much larger splittings that should not occur for a pure S‐state.

18.7 SPECTRA AND ELECTRONIC STRUCTURE OF DIVALENT ACTINIDE IONS AND ACTINIDES IN VALENCE STATES HIGHER THAN 4þ

Although spectra of actinide compounds and solutions exhibiting other than the 3þ and 4þ valence states are well known, systematic analyses of the electronic structure in other valence states are very tentative now. Extensive analysis is limited to a few isolated cases. However, tabulations of electrostatic (Varga et al., 1970) and spin–orbit integrals (Lewis et al., 1970), computed using ab initio methods, have been published, and the relative energies of electronic configurations occurring within the usual spectral range of interest to chemists have been estimated from free‐ion spectra (Brewer, 1971a,b). The electrostatic and spin–orbit interactions in any given valence state are expected to vary systematically across the series. However, in the trivalent and tetravalent series it was necessary to introduce effective operators to explicitly screen the effects of configuration interaction to obtain good correlation with the experiment. In the absence of these correction terms, the values of the Slater integrals obtained in fitting the data exhibited a much more erratic behavior when plotted as a function of Z. In the discussion of 2þ and high valent actinides, it should be noted that the role of second‐order correction terms has not been studied in detail for these oxidation states. What is clear is that the importance of both spin–orbit coupling and crystal‐field interactions relative to the electrostatic interaction increases with increasing valence. One of the reasons for introducing the theoretical interpretation of trivalent and tetravalent spectra in some detail was to provide the basis for discussing models appropriate to other valence states. Although detailed models have yet to be constructed, and may lead to revision of some of the values given here, it is advantageous to introduce a generalizing element into the discussion and relate available spectra to this central theme rather than approach each different actinide ion as a unique entity. It has been realized for An2þ that the interactions appear to be of the same relative magnitude as for An3þ; however for An4þ and An5þ the crystal‐field interaction becomes, relatively, much more important, and extraction of well‐ defined parameters for the free‐ion and crystal‐field interactions becomes more difficult. In An3þ spectra, the correction terms Hcorr act mainly on the electrostatic part of the free‐ion Hamiltonian, although some provision for second‐ order magnetic effects are included. In this discussion it is assumed that it is not necessary to modify the magnitudes of the terms associated with Hcorr in treating other valence states. Since the crystal‐field splitting is computed using a single‐particle model, corrections to Ecf may be required as the relative magnitude of the crystal field increases.

Spectra and electronic structure of actinide ions in various valence states 2077 In early attempts to develop a systematic interpretation of trivalent actinide and lanthanide spectra, initial sets of F k and znf for some members of the series had to be estimated. This was done by linear extrapolation based on the fitted parameters that were available from the analyses of other individual spectra. As more extensive data and improved modeling yielded better determined and more consistent F k and znf values for the 3þ actinides (and lanthanides), it became apparent that the variation in the parameters was nonlinear, as indicated for F2 (5f,5f) in Fig. 18.4. This nonlinearity could also be observed in the values of parameters obtained from the ab initio calculations. The difference between the ab initio and fitted values of parameters (DP) appears to exhibit a much more linear variation with Z than do the parameter values. Consequently, DP has been adopted as the basis for a useful predictive model (Carnall et al., 1966; Crosswhite, 1977; Crosswhite and Crosswhite, 1984). For the trivalent actinides the values of DP are not constant over the series, but use of a single average value over a group of four or five elements is not an unreasonable approximation. Thus, in developing a predictive model for the F k and znf parameters, an attempt is made to establish average values of DP for a particular valence state and type of crystal‐field interaction. The energy level structure computation based on the predicted parameters can be compared to that observed, and then appropriate modifications sought by a fitting procedure where necessary. 18.7.1

Divalent actinide‐ion spectra

Efforts to prepare divalent actinide compounds and analyze their spectra have been less successful than was the case for lanthanides, where the divalent ion for each member of the series could be stabilized in CaF2 (McClure and Kiss, 1963). In both Am2þ:CaF2 and Es2þ:CaF2 (Edelstein et al., 1966, 1967, 1970; Baybarz et al., 1972), intense absorption bands were observed. These bands could be attributed to either f!d or charge‐transfer transitions. The presence of divalent actinide ions in these cases was established by measurements of the electron paramagnetic resonance spectra, not on the basis of the observed optical spectra. In contrast to the more intense absorption bands reported for Es2þ: CaF2, weak absorption bands consistent with the intensities expected for f!f transitions were identified in the 10 000–20 000 cm1 region in both EsCl2 and Es2þ:LaCl3 (Fellows et al., 1978). The relatively narrow band structure exhibited by the Es2þ halides was also found to be characteristic of the Cf2þ halides (Peterson et al., 1977; Wild et al., 1978). Although it was not possible to stabilize Cm2þ in CaF2 under the same conditions that yielded for Am2þ:CaF2, evidence for the formation of both Am2þ and Cm2þ has been obtained in solution in pulse radiolysis studies; however, as in the spectrum of Am2þ:CaF2, the absorption bands were broad and intense. The nature of the absorption process is therefore not clear. A charge‐transfer process cannot be excluded (Sullivan et al., 1976).

2078

Optical spectra and electronic structure

Because the available spectroscopic results for divalent actinides are fragmentary, a consistent interpretation that accounts for all observations and predicts the energies of other bands that might be accessible to observation will be adopted. The basic aspects of this tentative model can be deduced in part from available data for divalent lanthanide spectra. The free‐ion spectra of Ce III and Pr IV are known. Initial estimates of F k and z4f values appropriate to Ln2þ in condensed phases can be made by assuming that the change observed in these parameters for iso‐f‐electron couples such as Ce III/Pr IV (both 4f2) will also be characteristic of the couple Ce2þ/Pr3þ in condensed phases. This suggests a reduction of 20–30% in comparing values of F k and z4f for divalent compared to isoelectronic trivalent‐ion cases. Comparing the results for Eu2þ:CaF2 (Downer et al., 1983) with those for Gd3þ: LaF3 (Carnall et al., 1971), the parameters for Eu2þ (4f7) are 82–86% of those for Gd3þ (4f7). The little information available on divalent lanthanide ion crystal‐field splitting (Dieke, 1968) suggests that the crystal‐field interaction is even smaller than for the trivalent case. This also was suggested in an analysis of Eu2þ in strontium fluoride (Downer et al., 1983). Based on the small crystal‐field splitting indicated for the divalent lanthanides, it is reasonable to assume as a first‐order approximation that the corresponding actinide crystal‐field splitting will be small. Although fragmentary, available spectroscopic data for An2þ appear to be consistent with this estimate. The initial model can consequently be limited to free‐ion considerations. The initial F k and z5f parameters for An2þ may be estimated to be 85–90% of those for the iso‐f‐electronic An3þ:LaCl3 ion. The effects of configuration interaction for An2þ can be taken to approximate those for An3þ. The resulting model energy level schemes for An2þ are plotted in Fig. 18.17 where the overlap of the 5fN16d and 5fN configurations is also indicated (Brewer, 1971a,b). Examining the range of energies in which f!f transitions might be observed, it is seen from the figure that the largest ‘optical windows’ are expected in Am2þ, Cf2þ, and Es2þ. In Np2þ, Pu2þ, Cm2þ, and Bk2þ, it is probable that f!f transitions will only be observed in the infrared range. This of course assumes that the 5fN is consistently the ground state configuration. Transitions resulting from the promotion of f!d would be expected to result in intense (allowed) absorption bands such as those observed in Ln2þ spectra (McClure and Kiss, 1963). The much weaker f!f transitions occurring in the same energy range as the allowed transitions would be masked, so the optical window corresponding to the pure f!f energy spectrum will be somewhat smaller than that for the gaseous free‐ion f!d transition energies indicated in Fig. 18.17 (Brewer, 1971a,b). The computed level structure for Cf2þ and Es2þ agree with the experimental results, but indicate the existence of bands not yet reported. Systematic energy level calculations are of considerable importance in predicting the energies at which luminescence might be observed. In general, the longest‐lived luminescence will originate from the state with the largest energy gap between it and the next lower‐energy state. Based on the computed large

Spectra and electronic structure of actinide ions in various valence states 2079

Fig. 18.17 Estimated ranges of energies in which 5f–5f transitions in An2þ may be experimentally observed.

energy gap between the ground (8S7/2) and first excited (6P7/2) states in Am2þ (5f7), isolated Am2þ sites would be expected to exhibit luminescence near 14 000 cm1 (Edelstein et al., 1966; Edelstein and Easley, 1968; Edelstein, 1991). 18.7.2

Spectra of actinide ions in the pentavalent and hexavalent states

The actinide ions with well‐defined valence states greater than VI are confined to the light half of the 5f series. A large number of stable compounds are known, and spectra have been recorded in solution, in solids, and in gas phase. However, there have been relatively few attempts to develop detailed energy level analyses. Although Hartree–Fock type calculations of F k and znf can be carried out for any arbitrary state of ionization of an actinide ion, the relative importance of the ligand (or crystal) field must also be established to develop a correlation for experimentally observed transition energies. Ab initio models of the ligand field are characteristically very crude. The spectra of penta‐ and higher‐valent actinides are strong crystal field cases and the development of correction terms for first‐order crystal field model may well be essential to any detailed analysis. Two types of ionic structure are normally encountered in the higher‐valent 2þ species: the actinyl ions AnOþ 2 and AnO2 (Denning, 1992; Matsika and Pitzer,

Optical spectra and electronic structure

2080

2001; Denning et al., 2002), and halides such as UCl5, CsUF6, and PuF6. Mixed oxohalide complexes are also known. In the actinyl ions (An ¼ U, Np, Pu, Am) the axial field imposed by the two nearest‐neighbor (y1) oxygen atoms plays a dominant role in determining the observed energy level structure (Eisenstein and Pryce, 1966; Bell, 1969). The analysis of spectra of higher‐valent actinide halides is also based on a strong ligand‐field interaction, but the symmetry is frequently found to be octahedral or distorted octahedral (Goodman and Fred, 1959; Eisenstein and Pryce, 1960; Kugel et al., 1976; Eichberger and Lux, 1980). Typical iso‐f‐electronic penta‐ and higher‐valent actinide species are shown in Table 18.12, where X is a halide ion. 2þ Aqueous solution spectra characteristic of the NpOþ 2 and PuO2 ions, both 2 having the 5f electronic structure, are shown in Fig. 18.18. Some qualitative similarities in band patterns for these iso‐f‐electronic ions appear to exist, but detailed analysis of the observed structure in terms of a predictive model is tentative. Charge‐transfer bands for NpO2þ (20 800 cm1), PuO2þ (19 000 2 2 1 1 2þ cm ), and AmO2 (18 000 cm ) have been identified (Jørgensen, 1970). Spectra of the actinyl ions and the molar absorptivities of the more intense bands in aqueous solution have been tabulated (Carnall, 1973, 1982). The charge‐transfer transitions in crystalline CsNpO2Cl4 and CsNpO2(NO3) as reported by Denning et al. (1982) are apparently much lower than that predicted 1 for NpO2þ 2 (20 800 cm ). In their analysis, Denning et al. (1982) assigned five charge‐transfer bands of CsNpO2Cl4 and CsNpO2(NO3) between 13 000 and 20 000 cm1. Attempts to interpret the spectra of the penta‐ and hexahalides of the actinides have used the effective‐operator Hamiltonian discussed in Sections 18.3 and 18.4. However, the results are limited primarily to U5þ and Np6þ, both having the 5f1 configuration and Np5þ and Pu6þ with the 5f2 configuration. The magnitude of the spin–orbit interaction is known for U V. Its free‐ion spectrum has been interpreted in terms of a coupling constant, z5f ¼ 2173.9 cm1, based on a 2F5/2! 2F7/2 energy difference of 7608.6 cm1 (Kaufman and Radziemski, 1976). The optical properties of Np and Pu ions and compounds were analyzed by Edelstein (1992). The spectra of several complex pentavalent uranium halide

Table 18.12 Some iso‐f‐electron penta‐ and higher‐valent actinide species.a Number of 5f electrons ¼

0

1

2

3

4

UO2þ 2 Np VIII

UOþ 2

PuO2þ 2 NpOþ 2 PuF6 NpX 6

AmO2þ 2 PuOþ 2  PuX6

AmOþ 2

UF6 UCl6

a

X, halide ion.

NpO2þ 2 Pu VIII NpF6 UX 6 UF5

Spectra and electronic structure of actinide ions in various valence states 2081

6þ 5þ þ Fig. 18.18 Aqueous solution absorption spectra of PuO2þ 2 (Pu ) and NpO2 (Np ).

compounds appear in the literature and, based on representative crystallographic determinations, the site symmetry usually is close to octahedral. The combined effect of the spin–orbit and octahedral ligand‐field interactions is to split the parent 2F state into five components whose irreducible double group labels are indicated in Fig. 18.19. The energy level structures of several actinide 4þ, 5þ, and 6þ compounds with the 5f1 ion at a site of octahedral (or approximated as octahedral) symmetry are compared in Table 18.13. As indicated in Table 18.13, there has been considerable variation in the ligand field parameters deduced by different investigators from absorption spectra in which the energies of observed features are surprisingly consistent. The case of UCl5, which has a dimeric structure that gives rise to approximately octahedral U5þ sites, is particularly interesting because the spectra of solutions (UCl5 in SOCl2) (Karraker, 1964), of a single crystal (Leung and Poon, 1977), and of the vapor phase, (UCl5)2 or UCl5 · AlCl3 (Gruen and McBeth, 1969), all give absorption features that are similar to both the relative intensities of the transitions and their energies. The importance of the nearest‐neighbor coordination sphere in determining the spectra, essential

2082

Optical spectra and electronic structure

Fig. 18.19 Comparison of crystal‐field splittings of the 5f 1 states of actinide ions in various hosts.

to the exclusion of the effects of long‐range order, is consistent with the behavior expected for strong octahedral bonding. However, more evidence is needed to justify the assignments and to establish uniquely the limits over which the ligand field parameters may vary. The spectra of CsUF6 (Reisfeld and Crosby, 1965) and CsNpF6 (Hecht et al., 1979) have been reported and analyzed, and that of CsPuF6 has been measured (Morss et al., 1983). However, the treatment of CsUF6, which has been considered to be a model for other cases of distorted octahedral symmetry, has been questioned both experimentally (Ryan, 1971) and on theoretical grounds. Both Leung (1977) and Soulie (1978) have pointed out that there is actually a very significant distortion of the Oh symmetry originally assumed for CsUF6 (Reisfeld and Crosby, 1965), with D3d symmetry providing the basis for a much improved interpretation. If electrostatic interaction parameters of the same order of magnitude as those suggested by Poon and Newman (1982) are utilized for CsNpF6, together with the D3d ligand field parameters for CsUF6, and further extrapolation of these results is carried out to provide values for the CsPuF6 case, the resulting energy level structure is that indicated in Fig. 18.20. The general aspects of this predicted structure appear to be consistent with available experimental data. Aside from the structure of the ground state, a relatively isolated 3F2 state in CsNpF6 should be observed. However, with the

Spectra and electronic structure of actinide ions in various valence states 2083 Table 18.13 Energy parameters for An4þ, 5þ, 6þ compounds (in cm1).a (5f1) Pa4þ: Cs2ZrCl6b

(5f 2) CsNpF6f

(5f 2) PuF6g

(5f 3) CsPuF6f

F2

48 920

51 760

F4

42 300

F6

27 700

36 026 (2 472) 72 458 (3 054) 40 535 (3 877) 2551 (46) [35 500] [664] [744]

z

1539.6

(5f 1) UCl5c

1559 (115)

a b g B20 B04

6945.3

B60

–162.7

sh

13 479 (1 125) –158.6 (745) 370

(5f 1) CsUF6d

1910.2 (13)

534.2 (139) –14 866 (66) 3305 (78) 33

(5f 1) NpF6e

2448.4 (33)

2200 30 000 660 700 534.2

44 553 (211) 7992 (105) 73

44 200 29 120 2510 30 000 660 700 543.2

–14 866

48 377(803)

14 866

3305

8690(180)

3305

54.2

a

Values in parentheses are errors in the indicated parameters. Values in brackets were not allowed to vary in the parameter fitting. Piehler et al. (1991). c Leung and Poon (1977). d Ryan (1971). e Goodman and Fred (1959). f Estimated parameter values shown. In addition to those parameters tabulated, the following were included: P 2 ¼ 500, P 4 ¼ P 6 ¼ 0 (for both CsNpF6 and CsPuF6); T2 ¼ 200, T 3 ¼ 50, T 4 ¼ 100, T 6 ¼ –300, T 7 ¼ 400, T 8 ¼ 350 (for CsPuF6 only). g Edelstein (1992). M 0 ¼ 0.987, M 2 ¼ 0.55, M 4 ¼ 0.384, P 2 ¼ 573, P 4 ¼ 524, P 6 ¼ 1173. h Deviation as defined in footnote c of Table 18.4. b

exception of this 3F2 state, neither the spectrum of CsNpF6 nor that of CsPuF6 is expected to exhibit any extensive, easily recognizable band structure. A relatively high density of excited states is predicted and detailed analysis will be difficult. The actinide hexafluorides, UF6, NpF6, and PuF6, form a unique group of volatile actinide molecular species. They are not regarded as strongly bonded ˚ ) (Claassen, since the metal–fluorine distances tend to be rather large (1.98 A 1959). The combination of well‐characterized spectroscopic and magnetic (Goodman and Fred, 1959; Hutchison and Weinstock, 1960; Edelstein, 1992) results for NpF6 and PuF6 has served to establish a reasonable basis for the energy level analysis in octahedral symmetry summarized in Table 18.13. A consistent set of F k and z5f parameters can be combined with the crystal field for NpF6 to yield an estimate of the parameters set for PuF6 and AmF6. However, in terms of the free‐ion interaction parameters, no consistent results have been

2084

Optical spectra and electronic structure

Fig. 18.20 Computed energy levels schemes for CsUF6, CsNpF6, and CsPuF6. The cross‐ hatched areas indicate that a relative dense energy structure is predicted.

achieved when the parameters are varied in fitting of the observed energy levels of PuF6 (Edelstein, 1992). As listed in Table 18.13, the value of F2 for PuF6 is reduced by greater than 50% from its Hartree–Fock value and F 4 is greater than the calculated Hartree–Fock value (Wadt, 1987). In comparison with Hartree– Fock values and the parameters for NpF6, the empirical values for F 6 and z seem to be of reasonable magnitude. The energies of some of the lower‐lying states in NpF6 and PuF6 are shown in Fig. 18.21. The two upper levels of NpF6 at 23 500 and 28 000 cm1 were not well resolved in absorption spectra (Steindler and Gerding, 1966) and the uncertainty in assigning these two levels could result in uncertainties in the spin–orbit and crystal field parameters. The indicated structure is consistent with the principal features in the absorption spectrum of PuF6 (Kugel et al., 1976) as shown in Fig. 18.22. Detection of luminescence in the selective excitation of NpF6 and PuF6 and at energies in

Spectra and electronic structure of actinide ions in various valence states 2085

Fig. 18.21 Comparison of observed and computed energy level schemes for NpF6 (data from Goodman and Fred, 1959) and PuF6 (data from Edelstein, 1992). Analysis of near‐ infrared spectra of matrix‐isolated NpF6 was also reported (Mulford et al., 1991)

agreement with the energy gaps between the predicted ground and first excited states in both spectra has been reported (Beitz et al., 1982). 18.7.3

Charge‐transfer transitions and structure of actinyl ions

In addition to electronic transitions from 5fN to excited configurations, an electron may be excited from a ligand to a 5f orbital, creating a charge‐transfer state, with a configuration consisting of 5fNþ1 plus a ligand ‘hole’. The spectra 7þ of UO2þ shows typical charge‐transfer transitions for the 2 , UF6, and Np actinide series since, in contrast to the transitions between states within the 5fN configuration which characterize most of the actinide spectra discussed in previous sections; the above species contain no f‐electrons in open shells. The energies of these states are highly ligand‐dependent and, especially in organic systems, they can be at a lower energy than the 5fN16d states. For lighter actinide ions in oxygen environments, actinyl ions are formed through charge‐ transfer bonding (Jørgensen, 1957). The most extensive studies of ion‐to‐ligand charge transfer have been conducted on uranyl ðUO2þ 2 Þ ion in various solutions and compounds (Denning et al., 1982, 2002; Denning, 1992). Fig. 18.23 shows

2086

Optical spectra and electronic structure

Fig. 18.22 The absorption spectrum of PuF6. Arrows indicate regions reported to show vibrational structure. Bars indicate regions examined by intra‐cavity laser absorption: I, 455–470; II, 550–574; III, 697–729; IV, 786–845; V, 918–971 nm. At the top is a densitometer trace of the high‐resolution absorption spectrum of PuF6 in the 781–830 nm region obtained in multipass experiments. Data from Kugel et al. (1976).

the energy level structure of UO2þ 2 charge‐transfer states in comparison with that of the U6þ and O2 ions. The lowest‐energy level of the excited charge‐ transfer states starts at (20 000 cm1 for uranyl ion and at (14 000 cm1 for neptunyl ion (NpO2þ 2 ), which is below the energy levels of several 5f states of the Np6þ core (Denning et al., 1982, 2002). In the neptunyl case, energy levels of different origins, namely 5fN, 5fN16d, and ion–ligand charge transfer, may overlap in the same energy region, and thus make spectrum analysis difficult. Emission from charge‐transfer states of actinide ions in condensed phase is relatively rare except for the case of uranyl ðUO2þ 2 Þ ions, which often exhibit a strong luminescence in solution. This is because of the large energy gap between its ground and excited charge‐transfer states that suppresses quenching due to nonradiative phonon relaxation (Riseberg and Moos, 1968). The spectra of UO2þ 2 compounds with a characteristic structure in the visible– ultraviolet range below 400 nm are commonly observed charge‐transfer

Spectra and electronic structure of actinide ions in various valence states 2087

Fig. 18.23

Illustration of electronic energy level scheme of uranyl ion UO2þ 2 .

transitions in the actinide series. Analyses of crystal spectra such as that for Cs2UO2Cl4 are now available (Denning et al., 1980, 1982; Denning, 1992). Because of the energy gap between the emitting and ground states as shown in Fig. 18.23 is much larger than the vibration energies, in many cases including uranyl species in solutions, fluorescence emission is often the dominant channel of relaxation from the lowest level of the excited charge‐transfer states. Fig. 18.24(a) shows the fluorescence spectrum of UO2 Cl2 4 : Cs2 ZrCl6 single crystal at 20 K (Metcalf et al., 1995). The ZPL is accompanied by a progression of vibronic lines due to the O–U–O stretching and bending modes, which characterize the uranyl structure and are relatively insensitive to the environment of the uranyl ion in the equatorial plane. Usually, the linear dioxo cation O–U–O is coordinated by an additional four to six ligand ions in its equatorial plane. The vibrational frequencies of different modes of the complexed ion can be determined directly from the spectrum. They are typically 820, 900, and 240 cm1 for the symmetric, asymmetric, and bending modes of the UO2þ 2 ion, respectively. As to the nature of the uranyl bonding, variation of the vibrational frequencies is correlated with the energy levels of the charge‐ transfer states (Denning, 1992). The spectrum of the uranyl ion in single crystals of UO2 Cl2 4 : Cs2 ZrCl6 exhibits extremely sharp line widths, indicating that the uranyl ions in the crystal have highly identical local structure so that

2088

Optical spectra and electronic structure

Fig. 18.24 Spectra of uranyl charge‐transfer vibronic transitions: (a) fluorescence spectrum of UO2þ 2 in Cs2ZrCl6 at 20 K (data from Metcalf et al., 1995) and (b) fluorescence spectra of UO2þ 2 in B2O3 glass at 4 and 295 K.

inhomogeneous line broadening induced by structure defects is not significant. If structure variation and impurity phases exist, inhomogeneous line broadening would obscure the features due to different vibrational modes. Fig. 18.24(b) shows the emission spectra of uranyl in B2O3 glass matrix at 4 and 295 K. In comparison with Fig. 18.24(a), the lines become much broader, whereas the changes in the overall spectral profile and line locations are insignificant. Given the nature of charge‐transfer states, it is apparent that the energy levels of charge‐transfer states are more sensitive to local structure disordering than that of the 5f5f transitions. Therefore, in structurally disordered environments such as glasses and solutions, inhomogeneous line broadening obscures

Radiative and nonradiative electronic transitions

2089

observation of separated lines of the asymmetric and bending modes. Only the progression of the symmetric mode, up to five quanta of phonon sidebands, is often observed. Based on the theory of ion–phonon interaction (Huang and Rhys, 1950), the spectra of charge‐transfer vibronic transitions of uranyl species may be theoretically simulated using a model proposed by Liu et al. (2002). The Huang–Rhys parameter of the uranyl vibronic coupling is typically in the range of 1.0–1.5. For the closely related case of NpO2þ ion doped into single‐crystal 2 Cs2UO2Cl4, detailed spectroscopic studies have identified a single electronic transition belonging to the 5f1 configuration, but the other structure observed is similar in origin to that reported for UO2þ 2 , i.e. transitions to molecular‐ orbital states (Stafsudd et al., 1969; Jørgensen, 1982; DeKock et al., 1985). Extensive analyses of the absorption and fluorescence spectra of UF6 have been published, and are covered in a review (Carnall, 1982). In the visible to near‐ultraviolet range, the character of the spectrum is similar to that of UO2þ 2 .

18.8 RADIATIVE AND NONRADIATIVE ELECTRONIC TRANSITIONS

18.8.1

Intensity of 5f–5f transitions

A systematic understanding of the energy level structure for An3þ serves as a foundation upon which to base the interpretation of other physical measurements. Considerable success has now been achieved in developing a parameterized model of f ! f transition intensities. The intensity of an absorption band can be defined in terms of the area under the band envelope normalized for the concentration of the absorbing ion and the path length of light in the absorbing medium. A proportional quantity, the oscillator strength P, has been tabulated for trivalent actinide‐ion absorption bands in aqueous solution. The experimentally determined oscillator strengths of transitions can in turn be related to the mechanisms by which light is absorbed (Condon and Shortley, 1963; Reid, 2000):  8p2 mcs  2 2 P¼ wF þ nM ð18:51Þ 2 3he ð2J þ 1Þ where F and M are, respectively, the matrix elements of the electric dipole and magnetic dipole operators joining the initial state J to a final state J0 , w ¼ (n2þ2)2/9n and n is the refractive index of the medium, s is the energy of the transition (cm1), and the other symbols have their usual meanings. Only a few transitions observed for the 3þ actinide ions have any significant  2 can be evaluated magnetic dipole character; however, the matrix elements of M directly from the knowledge of the eigenvectors of the initial (CJ) and final (C0 J0 ) states. Following the results of Condon and Shortley (1963), the magnetic dipole operator is given as

2090

Optical spectra and electronic structure M¼

e X ðli þ 2si Þ: 2mc i

ð18:52Þ

The matrix elements of the operator in equation (18.51) can then be written as 2

M ¼

e2 2 hCJ kL þ 2S kC0 J 0 i : 4m2 c2

ð18:53Þ

The nonzero matrix elements, which should be calculated in the intermediate coupling scheme, will be those diagonal in the quantum numbers t, S, and L. The selection rule on J is D J ¼ 0, 1. The Judd–Ofelt theory (Judd, 1962; Ofelt, 1962) has successfully addressed 2 the problem of computing the matrix elements of F , and can be written in the form: D E2 X

2 F ¼ e2 Ok CJ UðkÞ C0 J 0 ð18:54Þ k¼2;4;6

where Ok are three parameters which in practice are evaluated from measured band intensities. These parameters involve the radial parts of the fN wave functions, the wave functions of perturbing configurations such as 5fN16d, and the interaction between the central ion and the immediate environment. Since the Ok parameters contain many contributions, model calculations are not possible. Nevertheless, the relative simplicity of the intensity calculations using equation (18.51) have resulted in extremely useful analyses of experimental data. The matrix elements in equation (18.54) may be calculated using the SPECTRA program. For the trivalent actinide ions, the matrix elements of U(k) have been tabulated (Carnall, 1989) for states of 5f3 to 5f12 configurations with energies up to 40 000 cm1. It should be noted that the intensity theory presented here is applied only to the free‐ion multiplets, and the empirical values for the intensities of these multiplets are obtained by integrating over the band intensities in solution. Judd (1962) showed that the theory could successfully reproduce the observed intensities of bands of Nd3þ and Er3þ in aqueous solution (RE(H2O)x where x is 8 or 9) throughout the optical range, and that the intensity parameters Ok computed from first principles were consistent with those derived from fitting experimental data. Later systematic treatments of the intensities observed in the spectra of all aquated Ln3þ ions have confirmed and extended the original correlation (Carnall et al., 1968; Carnall, 1979a) and, more recently, it was found that a similar systematic treatment of band intensities for aquated An3þ‐ion spectra could be successfully carried out with only O4 and O6 treated as variables (Carnall et al., 1984). The emphasis on aquated fN‐ion spectra comes from the ability to identify many relatively isolated bands with single or very limited numbers of SLJ states, the corresponding unambiguous quantitative nature of the oscillator‐strength calculation, and the wide range of data

Radiative and nonradiative electronic transitions

2091

available, i.e. most members of the 4f and 5f series can be readily obtained as trivalent aquated ions in dilute acid solution. Intensity correlations for Ln3þ ion in many different host crystals, as well as in vapor complexes, have been developed (Beitz, 1994b; Reid, 2000). For the actinides, systematic and quantitative examination of transition intensities is presently restricted to aquated An3þ. Examination of Fig. 18.8 shows that, particularly for U3þ, Np3þ, and Pu3þ, the density of states is high and few of the observed bands can be uniquely identified. Both the relative intensities of observed transitions and the density of states decrease in magnitude with increasing atomic number. Starting with aquated Cm3þ, the heavy‐actinide aquated‐ion spectra are all amenable to intensity analyses with excellent correlation found between observed oscillator strengths and intensities computed using the Judd parameterization (Carnall et al., 1983). The oscillator strengths of aquated An3þ bands tend to be a factor of 10100 greater than those observed for the lanthanides, Starting with aquated Bk3þ, there is an apparent transition to a heavy‐lanthanide‐like character in the spectra, with no bands being disproportionately intense. Analysis reveals that the trends in the intensity parameter values over the series can be correlated with the extent to which higher‐lying opposite‐parity configurations like fN1d are mixed into the fN configuration. There is much less mixing of fN1d states into 5f8(Bk3þ) than in 5f3(U3þ) which it is consistent with the energy level structures of the fN1d and fN configurations of the two ions. An example of the type of correlation obtained between experiment and theory for aquated An3þ was previously discussed for aquated Cm3þ (Carnall and Rajnak, 1975). Figs. 18.25 and 18.26 compare the observed absorption spectra of U3þ and Cf3þ in dilute perchloric acid, respectively. These spectra are from the work of Carnall (1992) and have been published, along with those of other An3þ ions, with split abscissa scales to highlight weakly absorbing transitions (Beitz, 1994b). Also shown in Figs. 18.25 and 18.26 as vertical bars are the centers of gravity expected for the actinide ion’s 5f electron states based on the free‐ion parameters established for trivalent actinide ions in single crystals of lanthanum trichloride. It is evident in Fig. 18.26 that the free‐ion states provide an excellent basis for interpretation and assignment of the parity‐forbidden f–f absorption bands of Cf3þ. The very strong absorption bands that occur in the blue and ultraviolet spectral ranges of the U3þ spectrum can be assigned as arising from parity‐allowed transitions. In addition, it is evident that the f–f absorption bands of U3þ at longer wavelengths are significantly more intense than those of the comparatively heavy actinide ion Cf3þ. Qualitatively, the high intensity of U3þ f–f transitions can be attributed to interaction with the low‐lying opposite‐ parity states of U3þ. Put another way, the f‐electron states of light actinide ions contain a larger contribution from opposite‐parity states than is the case for heavier actinide ions. Band intensities of spectra such as those shown in Figs. 18.25 and 18.26 have been analyzed systematically (Carnall and Crosswhite, 1985; Carnall et al., 1985;

2092

Optical spectra and electronic structure

Fig. 18.25 Optical absorption spectrum of U3þ in dilute acid solution (shaded curve) compared to the 5f electron free‐ion state energies from studies on U3þ in LaCl3 (vertical bars). Data from Carnall (1992).

Fig. 18.26 Optical absorption spectrum of Cf 3þ in dilute acid solution (shaded curve) compared to the 5f electron free‐ion state energies from studies on Cf 3þ in LaCl3 (vertical bars). Data from Carnall (1992).

Radiative and nonradiative electronic transitions

2093

Fig. 18.27 Trends in the values of the Judd–Ofelt theory O4 and O6 parameters across the trivalent actinide ion series. (Data from Carnall and Crosswhite, 1985; Carnall et al., 1985; Beitz, 1994b).

Beitz, 1994b) from the f–f transition intensities using the Judd–Ofelt formalism (see equation (18.54)). The results of these analyses for aquated U3þ through aquated Es3þ, based on a fixed value of the Judd–Ofelt parameter O2 at 1  1020 cm2, are shown in Fig. 18.27. The difficulty in uniquely determining band areas for the strongly overlapping bands of light actinide ions results in large error estimates for these ions. The Judd–Ofelt parameters for aquated trivalent lanthanide ions become nearly constant in value beginning at neodymium and continuing across the series of lanthanide elements (Carnall, 1979a). A similar trend is evident in Fig, 18.27 beginning at Bk3þ for aquated trivalent actinide ions. Few opportunities exist for experimentally establishing O2 values for trivalent actinide ions. One such case is found in the branching ratios for emission from the 5D1 state of aquated Am3þ. Partial measurement of those ratios led Beitz (1994a) to conclude that an O2 value of 7  1020 cm2 was consistent with the O4 and O6 values shown in Fig. 18.27 (Beitz, 1994a). Go¨rller‐ Walrand and Binnemans (1998) have reviewed the application of Judd–Ofelt theory to lanthanide and actinide f–f transitions.

18.8.2

Florescence lifetimes

One reason of interest for determining absorption intensity correlations is that, once the parameters of the Judd–Ofelt theory are evaluated, they can be used to compute the radiative lifetime of any excited state of interest via the Einstein expression

2094

Optical spectra and electronic structure AðCJ; C0 J 0 Þ ¼

 64p2 s3  0 2 2 w F þ n3 M 3hð2J þ 1Þ

ð18:55Þ

where jCJ i and jC0 J 0 i are the initial and final states, A is the rate of relaxation 2 2 of CJ by radiative processes, and F and M are the terms defined in equations (18.52) and (18.54). The observed fluorescent lifetime of a particular excited state, tT, is determined by the sum of the inverse of the radiative and nonradiative lifetimes. Usually the nonradiative relaxation mechanisms are dominant. Thus ðtT Þ1 ¼ AT ðCJ Þ þ W ðCJ Þ

ð18:56Þ

where AT (CJ) is the total radiative relaxation rate from state jCJ i, that is, the sum of the rates of radiative decay to all states with energy less than that of jCJ i. If tR (calc) is the (computed) total radiative lifetime of jCJ i, then tR (calc) ¼ [A (CJ)]–1. Similarly, WT(CJ) is a total rate summed over all nonradiative relaxation processes. The magnitude of the energy gap between a fluorescing state and the next lower‐energy state appears to play a major role in determining the nonradiative lifetime of that state; shorter empirical fluorescent lifetimes are correlated with narrower gaps for the same fluorescing level in different systems. On the basis of the existence of relatively large energy gaps in the spectra of some of the heavier actinides (Fig. 18.8), experiments were initiated and luminescence lifetimes were successfully measured in solution for some of the excited states of aquated Bk3þ and Es3þ (Beitz et al., 1981), as well as aquated Cm3þ (Beitz and Hessler, 1980) and aquated Am3þ (Beitz et al., 1987). As indicated in Fig. 18.28, which shows the lower energy level structure for the heavier aquated

Fig. 18.28 Energy level schemes and selected branching ratios for radiative relaxation for Cm3þ through Es3þ.

Radiative and nonradiative electronic transitions

2095

An3þ ions, only in aquated Cm3þ does the observed lifetime of 1.2 ms in D2O (Kimura et al., 2001) compare well with the computed radiative lifetime, tR ¼ 1.3 ms. With smaller energy gaps, the nonradiative relaxation rate clearly becomes rate‐determining. Inability to observe a luminescing state for aquated Cf3þ in preliminary experiments suggests that lifetimes may be in the nanosecond time range (Beitz et al., 1981; Carnall et al., 1983). In addition to computing radiative lifetimes, it is instructive to establish the most probable pathway for fluorescence from a given state. Thus the branching ration, bR, from a given relaxing state to a particular final state is bR ðCJ; C0 J 0 Þ ¼

AðCJ; C0 J 0 Þ : AT ðCJ Þ

ð18:57Þ

As indicated in Fig. 18.28 for Cf3þ, bR ¼ 0.47 for emission from an excited (J ¼ 5/2) state to a lower‐lying (J ¼ 11/2) state, whereas bR ¼ 0.14 for emission to the ground state. In the case of J ¼ 5/2 state, it would be appropriate to monitor for luminescence near 13 000 cm1 as well as near 20 000 cm1.

18.8.3

Nonradiative phonon relaxation

The identification of the mechanisms of nonradiative relaxation of actinide ions in solution as well as in solids remains an important area for research (Hessler et al., 1980; Liu and Beitz, 1990a,b). The nonradiative relaxation rate between crystal field energy levels belonging to different multiplets is predominantly determined by temperature, the energy gap, and the lattice phonon modes of the particular host crystal (Riseberg and Moos, 1968; Miyakawa and Dexter, 1970). With the assumption that the phonons involved are of equal energy, a commonly used expression for the temperature‐dependent multiphonon relaxation rate is (Riseberg and Moos, 1968)  expðhom =kT Þ DE=hom W ð T Þ ¼ W ð 0Þ ; ð18:58Þ expðhom =kT Þ  1 where hom is the maximum phonon energy the lattice vibrations that couples to the electronic transition of the metal ion, DE is the energy gap between the populated state and the next low‐lying state, and W(0) is the spontaneous transition rate at T ¼ 0 when the phonon modes are all initially in their ground state. At low temperatures where hom kT , nonradiative relaxation rate is dominated by W(0), which can be expressed as a simple exponential function depending on the energy gap, DE W ð0Þ ¼ C expðaDE=hom Þ;

ð18:59Þ

where C and a are empirical parameters which are characteristic of the particular crystal. Known as the energy gap law, this exponential dependence of the transition rate on the energy gap has been used to describe quite generally the

2096

Optical spectra and electronic structure

energy gap dependence of multiphonon transitions rates for the 4f and 5f states (Riseberg and Moos, 1967, 1968). Extensive experimental results for lanthanide systems are available for comparison with those obtained for actinide ions. It should be possible to explore bonding differences between selected actinides and lanthanides by examining their excited state relaxation behavior. Because of smaller electrostatic interaction and larger spin–orbit coupling and crystal‐field splittings, the energy gaps between different J‐multiplets of actinide ions are much smaller than that of the isoelectronic lanthanide ions. Therefore, phonon‐induced nonradiative relaxation in actinide systems is more efficient than in the lanthanide systems. Except for a few cases, such as the 6D7/2 state of Cm3þ and Bk4þ, that have a large energy gap to the low‐lying states, the lifetime of most 5f–5f electronic transitions of actinide ions in solids and solutions are predominantly determined by nonradiative relaxation. A direct comparison of the use of the energy gap law for Cm3þ in LaCl3 and the trivalent rare earth ions in LaCl3 has been reported (Illemassene et al., 1997). A comparison of the emitting state lifetimes of Cm3þ in various crystals is given in Fig. 18.16. A summary of spectroscopic studies of Cm3þ in crystals LaCl3, LuPO4, ThO2, Cs2NaYCl6, and CsCdBr3 was given in a review paper (Edelstein, 2002). The lifetimes of the actinide ions with the 5f7 configuration (Cm3þ, Bk4þ) are roughly consistent with the energy gap law in that for the hosts LuPO4, ThO2, and in CeF4, only one or at most two levels luminesce. For the heavier halide hosts, the vibrational spread is small and the crystal field strength is relatively small so many more levels luminesce. Early studies on multiphonon relaxation of 5f states of aquated trivalent actinide ions have been reviewed (Yusov, 1993; Beitz, 1994a) and compared to similar work on 4f states of aquated trivalent lanthanide ions (Beitz, 1994b). Aquated ions are those whose inner coordination sphere consists only of water molecules. Systematic studies of the 5f state luminescence lifetimes of aquated trivalent actinide ions began in 1980 with the work of Beitz and Hessler (1980) who reported the luminescence emission spectra of 248Cm3þ in dilute perchloric or hydrochloric acid as well as luminescence lifetimes in H2O and D2O solutions. They assigned the emission as arising from the electronically excited 6 D7/2 state of Cm3þ based on a study of the solution absorption spectrum of Cm3þ in perchloric acid (Carnall and Rajnak, 1975). A subsequent study by Beitz and coworkers on the luminescence of 244Cm3þ in dilute acid solution showed that speciation studies on ultratrace levels of Cm3þ could be carried out using elementary laser‐induced fluorescence techniques (Beitz et al., 1988). Laser‐induced luminescence studies also have been reported on Am3þ (Beitz et al., 1987; Yusov, 1990; Thouvenot et al., 1993b; Kimura and Kato, 1998), Bk3þ (Carnall et al., 1984) and Es3þ (Beitz et al., 1983) in dilute acid solutions and as well as additional studies on aquated Cm3þ (Yusov, 1987; Kimura and Choppin, 1994; Kimura et al., 1996, 1997). In all cases, the observed luminescence bands were assigned as arising from a 5f state lying at or below the energy

Radiative and nonradiative electronic transitions

2097

of the exciting photons and that, among all such states, in addition possessed the largest DE value. The reported 5f state emission spectra of aquated trivalent actinide ions are in good agreement with the calculated free‐ion states of trivalent actinide ions doped into lanthanum trichloride (Carnall, 1992). Aquated actinide ions are prototypical species for the investigation of coordination complexes that form as ligands other than water become associated with an actinide ion. It should be appreciated that the coordination sphere of trivalent actinide ions is dynamic unless there is an exceptionally strong ligand bonding. For example, using nanosecond laser excitation, there are no reports of emission from aquated actinide ions that differ as to the number of coordinated water molecules, which suggests that the coordination environment of aquated actinide ions reaches equilibrium on the submicrosecond timescale. In the case of aquated actinide ions, interest naturally exists as to the number of inner‐sphere coordinated water molecules, and luminescence studies have been reported that provide a measure of that number. Kimura and Choppin (1994) doped Cm3þ into a series of solid‐hydrated lanthanum compounds and determined the influence of the number of inner‐ sphere coordinated water molecules on the observed Cm3þ luminescence lifetimes. Their data are plotted in Fig. 18.29 where the solid line expresses the resulting correlation as nH2 O ¼ 0:65kobs  0:88

ð18:60Þ

Fig. 18.29 Observed 248Cm3þ luminescence decay rate, kobs, from Cm3þ doped into a series of solid‐hydrated lanthanum compounds at Cm:La = 1:6.9  103 as a function of the number of inner‐sphere coordinated water molecules, nH 2 O . Data from Kimura and Choppin (1994).

2098

Optical spectra and electronic structure

where nH2 O is the number of inner‐sphere coordinated water molecules and kobs is the measured luminescence lifetime in units of ms1. Analysis of the data in Fig. 18.29 using equation (18.60) results in a calculated 95% confidence limit of  0.74 for nH2 O values, if one assumes that there is no error as to the number of inner‐sphere coordinated water molecules in a given compound. The correlation embodied in equation (18.60) should be valid as long as there is no contribution from ligands other than H2O or HDO to de‐excitation of the emitting state and the purely radiative decay rate of the emitting state remains essentially unchanged across the series of compounds. The value of nH2 O for aquated Cm3þ reported by Kimura and Choppin was 9.2  0.5 water molecules. Subsequently, Kimura and Kato (1998) studied aquated and complexed 241 Am3þ luminescence via its 5D1 ! 7F1 transition. They reported kobs ¼ 24.6  0.6 ns for aquated Am3þ in H2O and 162  4 ns for Am3þ in 99.9% D2O. They adopted a different analysis procedure based on the assumption that the number of inner‐sphere water molecules is 9 for aquated Am3þ and aquated Cm3þ. With that assumption and from the linear correlation they observed between the observed luminescence decay rate, kobs, and the deuterium mole fraction in H2O–D2O mixtures, they determined nH2 O ¼ 2:56  104 kobs  1:43 for the case of aquated Am

3þ

and

nH2 O ¼ 0:612 kobs  0:48 3þ

ð18:61Þ ð18:62Þ

for the case of aquated Cm . Subsequently, Kimura and coworkers studied the luminescence lifetimes of Am3þ and Cm3þ of unstated actinide isotopic composition at 25 C (Kimura et al., 2001). They reported lifetime values for aquated Am3þ in H2O of 25  0.75 and 160  5 ns for aquated Am3þ in 99.95% D2O along with the values of 65  2 ms for aquated Cm3þ in H2O and 1200  36 ms for aquated Cm3þ in 99.95% D2O. These values together with equations (18.61) and (18.62) give nH2 O ¼ 8:9 for aquated Cm3þ and nH2 O ¼ 8:8 for aquated Am3þ. On the basis of preferential solvation in the nonaqueous solutions, an estimate of the Gibbs free energy of transfer of Am3þ and Cm3þ ions from aqueous to nonaqueous solutions also was obtained using the observed luminescence lifetimes in mixtures of water and organic solvents. Due to its spectroscopy and photophysics, Cm3þ is the trivalent actinide ion most commonly studied in solution using luminescence techniques. As noted earlier, luminescence from three other aquated trivalent actinide ions has been reported. Selected lifetime values from these studies are shown in Table 18.14. In nearly all cases where the stated measurement errors were 5% or less of the observed value and the lifetime was at least a factor of 10 longer than the excitation pulse width, the reported lifetime values are concordant at the 95% confidence level. The seeming exception occurs for Cm3þ in D2O solution. Beitz and Hessler (1980) reported that the luminescence lifetime of Cm3þ in 1 M DClO4 solution was 940  40 ms, whereas Kimura and coworkers reported

Radiative and nonradiative electronic transitions

2099

Table 18.14 Selected 5f state luminescence lifetimes, t, for actinide ions in dilute acid solution at ambient temperature.a Actinide ion

Emitting stateb

t in H2O

U4þ Am3þ Cm3þ Bk3þ Es3þ

1

2.00 are known, and the thermodynamic properties of most of them are well established (see Table 19.6). The room temperature values for g‐UO3 and U3O8 are CODATA Key Values (Cox et al., 1989); those of the other binary uranium compounds have been reviewed

Thermodynamic properties of actinides and actinide compounds

2136

Table 19.6 Thermodynamic properties of the crystalline binary actinide oxides with O/An >2.00; estimated values in italics.

g‐UO3 b‐UO3 a‐UO3 d‐UO3 ε‐UO3 am‐UO3 a‐UO2.95 U3O8 a‐U3O7 b‐U3O7 U4O9 NpO3 Np2O5 a b c

Cp(298.15 K) (J K–1 mol–1)

S (298.15 K) (J K–1 mol–1)

DfH (298.15 K) (kJ mol–1)

81.67  0.16 81.34  0.16 81.84  0.30

96.11  0.40 96.32  0.40 99.4  1.0

–1223.8  1.2 –1220.3  1.3 –1212.41  1.45 –1213.73  1.44 –1217.2  1.3 –1207.9  1.4 –1211.28  1.28 –3574.8  2.5

237.93  0.48 214.26  0.90 215.52  0.42 293.36  0.45 – –

282.55  0.50 246.51  1.50 250.53  0.60 334.12  0.68 100  10 174  20

–3423.0  6.0 –4512.0  6.8 –1070  6 –2162.7  9.5

References a,b a a a a a a a a a a c a,c

NEA‐TDB (Grenthe et al., 1992; Lemire et al., 2001; Guillaumont et al., 2003). Cox et al. (1989). Morss and Fuger (1981).

by Grenthe et al. (1992). Pa2O5 and Np2O5 are the only other well‐known binary oxide with O/An > 2.00. None of the thermodynamic properties of Pa2O5 have been measured. Those of Np2O5 are fairly well established through enthalpy of formation measurements (Belyaev et al., 1979; Merli and Fuger, 1994) and high‐ temperature enthalpy increment measurements (Belyaev et al., 1979) that have been reviewed by Lemire et al. (2001). Because of the better stoichiometry and better thermochemical cycle used by Merli and Fuger, the DfH (Np2O5,cr) derived from that work has been accepted. No lanthanide comparison for these compounds can be made because there are no lanthanide oxides with O/Ln > 2.00. Recently the existence of PuO2þx with x up to 0.5 has been claimed (Haschke et al., 2001) and its thermodynamic properties have been estimated (Haschke and Allen, 2002). 19.5.2 (a)

Dioxides

Enthalpy of formation

The dioxides from ThO2 through CfO2 are all known, but many of these have not been studied thermodynamically (see Table 19.7). Because the enthalpy of formation values of ThO2, UO2 (CODATA Key Values, see Cox et al., 1989) and NpO2 to CmO2 are based on a sound experimental basis, the values for the other actinide dioxides can be estimated with reasonable accuracy.

Oxides and complex oxides

2137

Table 19.7 Thermodynamic properties of the crystalline actinide dioxides at 298.15 K; estimated values are in italics.

ThO2 PaO2 UO2 NpO2 PuO2 AmO2 CmO2 BkO2 CfO2 a b c d

Sexs (J K–1 mol–1)

S (298.15 K) (J K–1 mol–1)

DfH (298.15 K) (kJ mol–1)

0 14.90 9.34 14.15 1.55 12.46 0.00 17.29 21.3

65.23  0.20 80  5 77.03  0.20 80.30  0.40 66.13  0.26 78  5 65  5 83  5 87  5

–1226.4  3.5 –1107  15 –1085.0  1.0 –1074.0  2.5 –1055.8  1.0 –932.3  2.5 –912.1  6.8 –1023  9 –857  14

References a b a c c c,d d b b

Cox et al. (1989). Estimated in the present work. NEA‐TDB (Silva et al., 1995; Lemire et al., 2001; Guillaumont et al., 2003). Konings (2001b).

Morss and Fuger (1981) established that the reaction enthalpy of the idealized dissolution reaction AnO2 ðcÞ þ 4Hþ ðaqÞ ! An4þ ðaqÞ þ 2H2 OðlÞ

ð19:9Þ

varies regularly in the actinide series. The enthalpy of this reaction represents in part the difference between the lattice enthalpy of the crystalline dioxide and the enthalpy of hydration of its ionic components. Both these properties are difficult to calculate and change substantially as a function of ionic properties, whereas their difference (the enthalpy of solution) should change slowly and smoothly as a function of ionic size. Because the enthalpies of formation of Hþ(aq) and H2O(l) are constant in this equation, the quantity {DfH (MO2, cr)DfH (M4þ, aq)} can be used for establishing relationships. Fig. 19.12 shows the relation with the molar volume of the unit cell. Ionic radii could have been used, because these are tabulated as a function of coordination number, but often they are reliable to only two significant figures. The values for PaO2, BkO2, and CfO2 can be derived by interpolation or extrapolation of the linear relationship. These values are included in Table 19.7. (b)

Entropy

The low‐temperature heat capacities have been measured for the solid dioxides from ThO2 to PuO2 and standard entropies for these compounds are known (see Table 19.7). The values for ThO2 and UO2 are CODATA Key Values (Cox et al., 1989), those for NpO2 and PuO2 have been evaluated by the NEA‐TDB (Lemire et al., 2001). Konings (2001a) estimated the entropies of AmO2 and CmO2, proposing that the S (298.15 K) of these compounds can be adequately

2138

Thermodynamic properties of actinides and actinide compounds

Fig. 19.12 The difference between the enthalpies of formation of f‐element dioxides and the corresponding M4þ aqueous ions; lanthanides (
), actinides (○), and estimated values ().

described as the sum of a lattice component and an excess component arising from f‐electron excitation: S ¼ Slat þ Sexs

ð19:10Þ

Slat was assumed to be the value for ThO2 and Sexs was calculated from the crystal field energies of these compounds (Krupa and Gajek, 1991; Krupa, 2001). Good agreement with the experimental values for UO2, NpO2, and PuO2 was found and the description explains the significantly lower entropy value of PuO2 among these compounds. This estimation procedure was adopted in the recent evaluation of the entropies of Am compounds by the NEA‐TDB project (Guillaumont et al., 2003). In a subsequent study, Konings (2004a) argued that the experimental data give evidence that Sexs is composed of two terms, the f‐electron excitation and a residual term: Sexs ¼ Sf þ Sres

ð19:11Þ

We have used a similar method to estimate the entropies of PaO2, BkO2, CfO2, and EsO2, where in absence of crystal field data, the excess contribution was calculated from the degeneracy of the unsplit ground state, which probably overestimates the entropy somewhat. (c)

High‐temperature properties

The high‐temperature properties of the major actinide dioxides (UO2, ThO2, PuO2) have been reviewed by many authors. The data are mostly restricted to the solid phase, except for UO2, which has been studied in detail in the crystal,

Oxides and complex oxides

2139

liquid, and gas phases (up to 8000 K) for obvious reasons. Fink (2000) reviewed the thermophysical properties of UO2 recently and presented recommended values for a large number of thermodynamic and thermophysical properties. Numerous equations of state for UO2 have been published, the most recent and complete one by Ronchi et al. (2002). Also the high‐temperature properties of thorium oxide in the crystal phase are reasonably well established (Bakker et al., 1997). The melting points of the actinide dioxides are shown in Fig. 19.13 along with those for the lanthanide and actinide sesquioxides. The high‐temperature heat capacities of ThO2, UO2, and PuO2 are shown in Fig. 19.14. The heat capacity approaches the Dulong–Petit value (9R ¼ 74.8 J K1 mol1) between 500 and 1500 K. In this temperature range the lattice contributions dominate the heat capacity with a minor but significant

Fig. 19.13 The melting points of the lanthanide sesquioxides (
), the actinide sesquioxides (○) and actinide dioxides (□); estimated values are indicated by ().

Fig. 19.14

The high‐temperature heat capacity of the actinide dioxides (see Table 19.9).

2140

Thermodynamic properties of actinides and actinide compounds

contribution of 5f electron excitations. Peng and Grimvall (1994) showed that for ThO2 and UO2 the harmonic lattice contributions dominate up to about 500 K; above that temperature, the anharmonic contributions should be included. As discussed in Section 19.5.2(b), the difference between the heat capacity of ThO2 and the other actinide dioxides in the temperature range up to 1500 K is mainly due to the excess contribution arising from the population of excited f‐electron levels of the An4þ ions: Cp ¼ Clat þ Cexs

ð19:12Þ

Thus the heat capacity of the other actinide dioxides can be approximated by adding Cexs, which can be calculated from electronic energy levels. Above 1500 K, the heat capacity strongly increases towards the melting point. In this temperature range, l‐type phase transitions have been observed for UO2 (Hiernaut et al., 1993) as well as ThO2 (Ronchi and Hiernaut, 1996) at about 0.85Tfus, which are related to order–disorder anion displacements in the oxygen sublattice. Below the phase transition, the formation of Frenkel lattice defects is the main cause of the rapid increase of the heat capacity; above the phase transition, Schottky defects become more important. The experimental data for PuO2 by Ogard (1970) suggest a similar effect above 2400 K, but it has been attributed to partial melting of PuO2 through interaction with the tungsten container (Fink, 1982; Oetting and Bixby, 1982). Because no clear evidence exists for this interaction, it has been included in the recommended equations given in this work (unlike in Cordfunke and Konings, 1990; Lemire et al., 2001). The experimental heat capacity data for NpO2 (Arkhipov et al., 1974) are in poor agreement with the low‐temperature data and with the values estimated by Yamashita et al. (1997) and Serizawa et al. (2001). These authors calculated the lattice heat capacity from the phonon and dilatation contributions using Debye temperature, thermal expansion, and Gru¨neisen constants, and the electronic contributions from crystal field energies. No experimental data are known for PaO2 and AmO2. CmO2 is unstable above 653 K. As shown in Fig. 19.13 the melting points of the dioxides steadily decrease from ThO2 to PuO2, the change being more than 1200 K. This strong variation is accompanied by a strong increase in the oxygen pressure as the dioxides start to lose oxygen according to the reaction x MO2 ðcÞ ¼ MO2x ðsÞ þ O2 ðgÞ ð19:13Þ 2 which for PuO2 and AmO2 is already significant below the melting point, which means that the melting points are only defined in an oxygen atmosphere. The decrease of stability is related to the strong changes in stability of the 4þ oxidation states. Only the melting enthalpy of UO2 is known with some accuracy. The values for the other dioxides have been estimated assuming that the entropy of melting is constant along the AnO2 series.

Oxides and complex oxides

2141

Fig. 19.15 The oxygen potential of UO2x at 1500 K (solid line) and 1250 K (broken line) as a function of x calculated from the Lindemer and Besmann (1985) model; note that the hyperstoichiometric range is given with negative values.

Recommended equations for the high‐temperature heat capacity are given in Table 19.8. (d)

Nonstoichiometry

The actinide dioxides are well known for their wide ranges of nonstoichiometry. Hypostoichiometry has been reported for all actinide dioxides. Hyperstoichiometry is only known for UO2 although recent studies have presented evidence that it could also occur in PuO2 (Haschke et al., 2001). Lindemer and Besmann (1985) presented a thermochemical model to represent the oxygen potential–temperature–composition data for AnO2x assuming a solution of two fluorite structures with different O/An ratios. The reaction can be represented by

 2a 2 ð19:14aÞ AnO2 þ O2 ¼ Ana Ob b  2a b  2a for the hyperstoichiometric range and

 2 2a Ana Ob þ O2 ¼ AnO2 2a  b 2a  b

ð19:14bÞ

for the hypostoichiometric range. In these equations, AnaOb is a hypothetical end‐member of the fluorite solid solution AnO2x. The oxygen potential can then be represented by: RT lnðpO2 Þ ¼ Dr H  TDr S þ RTf ðxÞ þ Ef 0 ðxÞ

ð19:15Þ

(cr) (cr) (cr)

U3O8 UO3 NpO2 PuO2 Pu2O3 AmO2 Am2O3

Cm2O3 Bk2O3 Cf2O3

e

d

c

b

a

–0.71391 1328.8 –3.9602 –3.9602 –4.3116 –1.00903 –0.8969 0.34759 –1.75053 1.9285 1.071 9.8742 –1.3489

–0.574031

55.9620 61.76 52.1743 0.25136 319.163 319.163 279.267 88.701 73.662 36.2952 130.6670 84.739 113.93 153.13 123.532

b

49.691 49.691 27.480 14.4896 8.8125 152.25 18.4357 10.72 59.37 3.573 14.550

87.951

51.2579

c (103)

0.8159 0.2301 2.372

127.255

–84.2411

–36.8022

d (106)

36.289

31.542

9.2245

e (109)

Bakker et al. (1997). Fink (2000). NEA‐TDB (Grenthe et al., 1992; Lemire et al., 2001; Guillaumont et al., 2003). Fit of the estimated data by Serizawa et al. (2001). Konings (2004b).

U4O9

UO2

(cr) (liq) (cr) (l) (a) (b) (cr) (g) (cr) (cr) (cr) (cr) (cr)

ThO2

a (10–6)

–2.6334

f (1012)

70  4

3110  10

63  6 60  10 113  20

2.594 11.9

82  10

3651  17

348 1400m 2000m 1200m 2820  60 2633  40 2358  25 2000m 1000m 2000m 2543  25 2196  25 1875  30

DtrsH (kJ mol–1)

T (K)

e

c

c

c

e

e

d

c

c

c

c

b

b

a

a

References

Table 19.8 High‐temperature heat capacity of the binary actinide oxides; Cp /(J K–1 mol–1) ¼ a(T/K)–2 þ b þ c(T/K) þ d(T/K)2 þ e(T/K)3 þ f(T/K)4 (estimated values are in italics); temperature T indicates the transition or melting temperatures except marked with m, when it indicates the maximum valid temperature of the polynomial equation.

Oxides and complex oxides

2143

where f(x) and f 0 (x) are functions of x that follow from the mass balance, and E is a temperature‐dependent interaction energy term that was used in modeling the experimental data: E ¼ DHe  TDSe

ð19:16Þ

Lindemer and Besmann (1985) analyzed the vast amount of experimental data and showed that hyperstoichiometric UO2þx can be represented as a mixture of UO2 and U3O7 for oxygen potentials above RTln(p) ¼ 26 6700 þ 16.5(T/K), or U2O4.5 below this limit; hypostoichiometric UO2x as a mixture of UO2 and the hypothetical end‐member compound U1/3. Besmann and Lindemer (1985, 1986) showed that PuO2x can be represented as a mixture of PuO2 and Pu4/3O2. Also for the Np–O, Am–O, Cm–O, Bk–O, and Cf–O systems, the Tp(O2)x relations have been measured. The Np–O system was studied by Bartscher and Sari (1986) using the gas equilibrium technique, the other systems by Eyring and coworkers (Chikalla and Eyring, 1967; Turcotte et al., 1971, 1973, 1980; Haire and Eyring, 1994) using oxygen decomposition measurements, and the Am–O system by Casalta (1996) using a galvanic cell. The data of most of these systems, however, do not allow a detailed description of the Tp(O2)x relations due to insufficient knowledge of the composition of the solid phase. An exception is the Am–O system and Thiriet and Konings (2003) applied the Lindemer–Besmann approach to the results of Chikalla and Eyring (1967), showing that AmO2x can be represented as a mixture of Am5/4O2 and AmO2. 19.5.3 (a)

Sesquioxides

Enthalpy of formation

Unlike the 4f elements, for which sesquioxides are ubiquitous, only the sesquioxides of Ac and Pu through Es have been prepared (Haire and Eyring, 1994). Experimental data from solution calorimetry are available for Am2O3, Cm2O3, and Cf2O3 and the enthalpies of formation of these three compounds are well established (although by only one set of measurements). Their values, the former taken from the most recent assessments (Silva et al., 1995; Konings, 2001b) and Cf2O3 from the original paper (Morss et al., 1987), are given in Table 19.9. As discussed for the dioxides, a systematic approach to the prediction of the enthalpies of formation of other sesquioxides can be made on the basis of the reaction enthalpy of the idealized dissolution reaction An2 O3 ðcrÞ þ 6Hþ ðaqÞ ! 2An3þ ðaqÞ þ 3H2 OðlÞ

ð19:17Þ

The enthalpy of this reaction can be used for establishing a relationship with molar volume, which was chosen as a parameter because there are three different sesquioxide structures with different coordination numbers and numbers of molecules per unit cell, as shown in Fig. 19.16. It is evident that, for all the three structure types, the enthalpies of solution of actinide sesquioxides are

f

e

d

c

b

a

DfH (298.15 K) (kJ mol–1) –1756 –1456 –1522 –1656  10 –1690.4  8.0 –1684  14 –1694 –1653  10 –1696 –1694 –1535 –1260 –1766

S (298.15 K) (J K–1 mol–1)

141.1  5.0

176  5.0 173  5.0 163.02  0.65 133.6  5.0 167.0  5.0 173.8  5.0 176.0  5.0 180.0  5.0

a

a

a

a

a

a,e

a

d

b,c

b

a

a

a

References

Estimated in the present work. NEA‐TDB (Silva et al., 1995; Lemire et al., 2001; Guillaumont et al., 2003). Konings (2001b, 2002). Konings (2001a). Morss et al. (1987). Cordfunke and Konings (2001c).

Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

An La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Ln 127.32 148.8 160.5 158.45 158.0 150.62 137.4 152.73 159.2 149.78  0.42 158.16 153.13  0.42 139.75 133.05  0.42 109.96

S (298.15 K) (J K–1 mol–1) –1791.6  2.0 –1813.0  2.0 –1809.9  3.0 –1806.9  3.0 –1811  21 –1823.0  4.0 –1650.4  4.0 –1819.7  3.6 –1865.2  6.0 –1863.4  5.0 –1883.3  8.2 –1900.1  6.5 –1889.3  5.7 –1814.5  6.0 –1877.0  7.7

DfH (298.15 K) (kJ mol–1)

c,f

c,f

c,f

c,f

c,f

c,f

c,f

c,f

c,f

c,f

c,f

c,f

c,f

c,f

c,f

References

Table 19.9 Standard entropies and enthalpies of formation of the crystalline actinide and lanthanide sesquioxides; estimated values are in italics.

Oxides and complex oxides

2145

Fig. 19.16 The enthalpy of solution (reaction 19.17) of the f‐element sesquioxides; closed symbols, lanthanides; open symbols, actinides; (
, ○), hexagonal, (~, ~), monoclinic, (&, □), cubic.

significantly less exothermic than for structurally similar lanthanide sesquioxides. With the exception of the enthalpy of formation of Pu2O3 (see below), the enthalpies of formation of the other sesquioxides were estimated from Fig. 19.16, taking in account their known or expected structural type. Using the calculated enthalpies of formation of the sesquioxides of U and Np, it can be shown that these sesquioxides are thermodynamically unstable with respect to disproportionation to the metals and the much more stable dioxides, e.g. using enthalpies of formation and estimated entropies: 2Np2 O3 ðcÞ ¼ 3NpO2 ðcÞ þ NpðcÞ;

DG ¼ 162 kJ mol1 1

ð19:18Þ

The corresponding U reaction has DG ¼ 322 kJ mol . The case of Pu2O3 deserves special mention. Its enthalpy of formation has been estimated as (1710  13) kJ mol1 (IAEA, 1967) from high‐temperature EMF measurements, as (1685  21) kJ mol1 (Chereau et al., 1977) from high‐temperature calorimetry, and as 1656 kJ mol1 (Besmann and Lindemer, 1983) from earlier measurements and more recent heat capacity values. The last value is adopted in Lemire et al. (2001). Because there is an experimentally derived standard entropy of Pu2O3, we can calculate its Gibbs energy of reaction (19.17), 289 kJ mol1, for comparison with that of the structurally similar Nd2O3, 332 kJ mol1. Actinide sesquioxides appear to be more stable than structurally similar lanthanide sesquioxides in comparison with the corresponding aqueous solutions, so that nuclear waste oxide matrices that accept lanthanide ions should bind corresponding trivalent actinides (Pu3þ, Am3þ) even more strongly. The reason for this behavior is not clear; a rationalization is that the 5f covalence is stronger to oxygen in solid oxides than in hydrated ions.

2146

Thermodynamic properties of actinides and actinide compounds

Recommended values for the standard enthalpies of formation and entropies of the actinide and lanthanide sesquioxides are assembled in Table 19.9. (b)

Entropy

Low‐temperature heat capacity measurements have been reported for Pu2O3 only (Flotow and Tetenbaum, 1981). This value was used to derive the entropies of Am2O3 and Cm2O3 (Konings, 2001a; Konings et al., 2005) using equation (19.10), calculating the excess entropy from known crystal field energies. Because information on the lattice component in the actinide sesquioxide series is missing, and the lattice component was obtained by scaling the values derived from the isostructural lanthanide series (Fig. 19.17). In this series the lattice entropy can be described by a simple linear relation between La2O3 and Gd2O3, for which the lattice values are well known due to the f0 and f7 configurations. (c)

High‐temperature properties

High‐temperature properties of the actinide sesquioxides have hardly been studied. The phase transitions in the sesquioxides have been determined and it has been shown that the sesquioxides exhibit a polymorphism: bcc ! monoclinic ! hexagonal. The cubic to monoclinic transition is, however, irreversible, and the monoclinic form is thought to be the thermodynamically stable phase. The measured melting points of Pu2O3, Am2O3, Cm2O3, and Bk2O3 are plotted in Fig. 19.13 and show a maximum at Cm2O3. The only measurements of high‐temperature properties are for Pu2O3, Am2O3, Cm2O3, and Bk2O3. The most extensive are the studies made for 244Cm2O3,

Fig. 19.17 The entropy of the hexagonal/monoclinic lanthanide sesquioxides (
), showing the linear lattice component derived for the f 0 and f 7 configuration as a dotted line. The entropies of the actinide sesquioxides (○) are calculated for a parallel lattice component based on the Pu2O3 value ().

Oxides and complex oxides

2147

which was considered as an isotopic heat source in the 1970s. Vapor pressure studies (see Section 19.5.5) and thermal conductivity and thermal diffusivity measurements were reported. To convert the latter measurements to thermal conductivity, Gibby et al. (1970) estimated the heat capacity of Cm2O3. As discussed by Konings (2001a), these values are very high when compared to the lanthanide sesquioxide data. Since reliable high‐temperature heat capacity data for the lanthanide sesquioxides are available, the functions of the actinide sesquioxides can be estimated from those by simple correlation (equation (19.13)). 19.5.4

Monoxides

Solid monoxides of Th and of U through Am have been reported as surface layers on the metals, as the reduction product of PuO2 with Pu or C, or as the product of reaction of Am with HgO. However, these solid ‘monoxides’ may be oxycarbides (Larson and Haschke, 1981). Usami et al. (2002) claim the formation of AmO by lithium reduction of AmO2. The product was, however, not characterized but its formation was deduced from a mass balance. The authors estimated its Gibbs energy of formation as 481.1 kJ mol1 at 923 K. Among the reported lanthanide monoxides, only EuO is well characterized, impure YbO can be prepared with difficulty, and ‘metallic’ (trivalent) monoxides of La, Ce, Pr, Nd, and Sm can be synthesized at high temperature and pressure. Earlier reports of lanthanide monoxides as surface phases are believed to be oxynitrides, oxycarbides, or hydrides (Morss, 1983). Thermodynamic calculations have shown how marginally stable the few lanthanide monoxides are, even under the exotic conditions of their preparation, and that classical (divalent) CfO should be unstable with respect to disproportionation (Morss, 1983). Thus the only hope of synthesis of actinide monoxides would appear to be the high‐pressure route for AmO and CfO, an extremely demanding synthetic procedure. 19.5.5

Oxides in the gas phase

Gaseous actinide oxide molecules of the types AnO, AnO2, and AnO3 have all been identified in Knudsen cell effusion or matrix isolation experiments of vapors above the solid oxides. The experimental work is restricted to the oxides of Th to Cm. Thorium dioxide principally vaporizes to give ThO2 molecules. Numerous vapor pressure studies have been performed for the solid–gas equilibrium, none of them, however, with techniques to confirm the vapor composition. Ackermann and Rauh (1973a) as well as Belov and Semenov (1980) reported the existence of the monoxide ThO in the vapor phase using mass spectrometry. Ackermann and Rauh (1973b) derived enthalpies of formation of the two molecules from the existing studies by correcting the vapor pressure studies for the ThO contribution. The thermal functions of the gaseous molecules have

Thermodynamic properties of actinides and actinide compounds

2148

been calculated from molecular parameters (Rand, 1975). The properties of the ThO molecule are based on experimental results as summarized by Rand (1975) and have been confirmed by quantum chemical calculations (Ku¨chle et al., 1994). ThO2 is a bent molecule, as was derived from matrix‐isolation and molecular beam deflection studies (Linevsky, 1963; Kaufman et al., 1967; Gabelnick et al., 1974). In the Pa–O system the monoxide and dioxide species have been identified in the vapor above PaO2x (Kleinschmidt and Ward, 1986) and above Pa metal in the presence of small amounts of oxygen (Bradbury, 1981). The situation for uranium is more complex. The binary molecules UO, UO2, and UO3 coexist above solid and liquid UO2, and at very high temperatures even dimeric molecules of these species and ionic species contribute to the vapor pressure. The UO2 molecule does not have a bent structure, like ThO2, but is linear; UO3 is planar with a T‐shaped geometry (Green, 1980). The relative fractions of these species are highly dependent on the temperature and O/U ratio of the condensed phase. Ronchi et al. (2002) have presented a detailed analysis of these complex equilibria, for which a large number of studies has been made up to very high temperatures, and their recommended values for the enthalpies of formation and entropies are listed in Table 19.10. Ackermann et al. (1966a) measured the vapor pressure of NpO2 by the Knudsen effusion technique. Mass spectrometric measurements confirmed that NpO2 is the dominant vapor species but that NpO(g) also has a significant contribution to the vapor. Ackermann and Rauh (1975) studied the isomolecular

Table 19.10 Thermodynamic properties of the gaseous polyatomic actinide oxides; estimated values are in italics.

UO3 ThO2 UO2 NpO2 PuO2 ThO UO NpO PuO CmO

S (298.15 K) (J K–1 mol–1)

DfH (298.15 K) (kJ mol–1)

309.5  2.0 281.7  4.0 266.4  4.0 276.5  5.0 278.0  5.0 240.1  2.0 248.8  2.0 257.9  5.0 248.1  3.0 261.9  10.0

–795.0  10.0 –455.2  10.0 –476.2  10.0 –444  20 –410  20 –20.9  10.0 24.7  10.0 9  5 –60.0  10.0 –175  15

References a b a e c b a e c d

Ronchi et al. (2002). IVTAN‐THERMO Database of the Institute for High Temperatures of the Russian Academy of Sciences. c Glushko et al. (1978). d Konings (2002). e Ackermann et al. (1966a). a

b

Oxides and complex oxides

2149

exchange reactions with La and Y by mass spectrometry. In addition, Ackermann and Rauh (1975) studied the NpO vapor pressure over the univariant system (NpO2(cr)þNp(l)þvapor) by Knudsen effusion technique. This approach yields results that are within the limits of uncertainty of the analysis of the isomolecular exchange reactions. The selected enthalpies of formation are derived from these studies. In the Pu–O system, it has been thought for a long time that only PuO2 and PuO exist as binary molecular species, but recently the existence of the PuO3 molecule has been reported (Ronchi et al., 2000). Matrix‐isolation spectroscopy (Green and Reedy, 1978a,b) has established the linear molecular structure of PuO2 and yielded values for the vibrational stretching frequencies. Archibong and Ray (2000) calculated the molecular properties of PuO2 using quantum 5 chemical techniques. They found that the 5 Sþ g and the Fu states are both candidates for the ground state, being almost equal in energy, the former preferred because of somewhat better agreement with the experiments for the two stretching frequencies. However, the data for the internuclear distance and the bending frequency for the 5 Sþ g state differ considerably from the estimates by Green (1980) on basis of the UO2 data, whereas the data for the 5Fu state agree reasonably. The enthalpies of formation of PuO and PuO2 are taken from Glushko et al. (1978). The vapor pressure of americium oxides has been deduced from measurements of plutonium oxides containing small amounts of 241Am as decay product using Raoult’s law (Ackermann et al. 1966b; Ohse, 1968). Although no direct measurement of the vapor species was made in either study, it was assumed that the AmO and AmO2 molecules are present. These data do not, however, allow the derivation of formation properties. For the Cm–O system, Knudsen cell effusion measurements have been performed (Smith and Peterson, 1970) from which it was concluded that Cm2O3 vaporizes according to the reaction: Cm2 O3 ðcr; lÞ ¼ 2 CmOðgÞ þ OðgÞ

ð19:19Þ

which is analogous to the lanthanide sesquioxides. Hiernaut and Ronchi (2004) recently measured the vapor pressure of (Cm,Pu)2O3 by Knudsen effusion mass spectrometry, confirming the results and conclusions of Smith and Peterson (1970). The dissociation energy of the actinide monoxides are plotted in Fig. 19.18 together with those of the lanthanide monoxides (Pedley and Marshall, 1983). The pattern that emerges for the actinide monoxides is parallel to that of the lanthanide monoxides and the dissociation energies of AmO can be estimated. Haire (1994) discussed this pattern in more detail, and extended the estimates to the heaviest actinides. He described the dissociation energy by a base energy D0,base and a DE value (as proposed by Murad and Hildenbrand (1980)): D0 ¼ D0;base þ DE

ð19:20Þ

2150

Thermodynamic properties of actinides and actinide compounds

Fig. 19.18 Dissociation energy of lanthanide (
) and actinide (○) monoxides; estimated values (see text) are indicated by ().

A ds‐state was assumed for these molecules, which means that a promotion energy of a f‐electron to a d‐state is required. This is the origin of the DE value, which can be derived from theoretical calculation (Brooks et al., 1984). The D0 base value was represented by interpolation of the LaO–GdO–LuO line, i.e. those lanthanides that already have one d‐electron. In transposing this relationship to the actinides, Haire assumed that the base relation is the same in the 4f and 5f series but the value for CmO adopted here (the actinide analog of GdO) suggests that there is a systematic difference of about 70 kJ mol1 (Fig. 19.18). We have corrected Haire’s values for this difference and the data for the monoxides beyond CmO thus obtained are shown in Fig. 19.18. Recently Santos et al. (2002a,b) suggested that the excited ‘bonding’ state is obtained by promotion of an s‐electron to a d‐level to create the double bond. The lowest‐lying excited states to be considered are 4f n35d26s and 4f n25d6s. Gibson (2003) showed how the energy required to promote gaseous lanthanide atoms to the excited ‘bonding’ state is responsible for the trends in the LnO dissociation energies. He defined the intrinsic Ln¼O bond energy as ‘‘the bonding interaction between an oxygen atom and a lanthanide atom, Ln*, that has an electron configuration suitable for formation of the covalent formally double bond in the Ln¼O molecule.” He identified the 4f n35d26s configuration as the appropriate one for bonding and the two 5d electrons as the electrons that provide bonding with the oxygen. Thus the trend was explained as: D0 ðLnOÞ ¼ D0 ðLnOÞ ¼ DE ½ground ! bonding configuration 19.5.6 (a)

ð19:21Þ

Complex oxides

Ternary and quaternary oxides with alkali metal ions

An extensive number of thermodynamic studies of the alkali uranates have been reported and the existing thermochemical data have been assessed by Cordfunke and O’Hare (1978) and Grenthe et al. (1992), the latter study

Oxides and complex oxides

2151

updated by Guillaumont et al. (2003). These thermochemical data are, however, much fewer than the large number of phases existing in the A2O–UO3–UO2 phase diagrams (Lindemer et al., 1981). And no thermodynamic studies exist for ternary compounds with the alkali ions containing tetravalent actinide ions. Thermochemical measurements have also been reported for a few ternary oxides of alkali metals and Np(VI). No thermochemical measurements have been reported for compounds of the alkali metal with other actinide oxides, surprisingly not even for the sodium plutonates. (i) Enthalpy of formation The enthalpies of formation of the alkali uranates are generally derived from enthalpy of solution measurements in hydrochloric or nitric acid, often involving very complex reaction cycles to compensate the oxidation of uranium. The measurements have been made for mixed compounds of the general formulas nA2O · mUO3 (hexavalent U) and nA2O · mUO2.5 (pentavalent U). All existing literature have been reviewed by Grenthe et al. (1992) and Guillaumont et al. (2003) using currently accepted auxiliary data. Johnson (1975) as well as Lindemer et al. (1981) discussed correlations and methods to estimate unknown enthalpies of formation for the complex alkali uranates up to high n/m ratios (e.g. Cs2O · 15UO3), but their procedures are quite arbitrary. For the alkali metal neptunates(VI) with the general formulas A2NpO4, A2Np2O7, and A4NpO5, the enthalpies of formation were derived from the enthalpies of solution of the compounds in hydrochloric acid. These results were recently assessed by Lemire et al. (2001). The values of the enthalpies of formation of all these compounds are given in Table 19.11. (ii)

Entropy

Only a few low‐temperature heat capacity measurements have been made for the alkali uranates, and they are restricted to sodium and cesium compounds (see Table 19.11). Lindemer et al. (1981) estimated the entropy values for the other alkali uranates assuming that DrS for the formation reaction from the oxides is zero. The experimental results show that this is not the case and that the values for DrS strongly depend on the crystallographic modification and tend to be slightly positive. For these reasons, the values by Lindemer et al. (1981) have not been included in the present tabulations. (iii)

High‐temperature properties

High‐temperature enthalpy increment measurements have been made for a few alkali uranates. These are essentially the same compounds for which low‐temperature measurements have been performed. Most of the early data have been reviewed by Cordfunke and O’Hare (1978) and Cordfunke and Konings (1990) and they are summarized in Table 19.13. In the 1990s, the

b

a

133.0  6.0

Beta form. Alpha form.

M4NpO5

M2Np2O7

M2NpO4

M6U7O24

M3UO4

M2U4O12

M2U3O10

M2U2O7

MUO3

M2UO4

M4UO5

Na

K

Rb

Cs

–1828.2  5.8

–1522.3  1.8 –3213.6  5.3 –4437.4  4.1

–2639.4  1.7 –1968.2  1.3

198.2  0.4

132.84  0.40 275.9  1.0

166.0  0.5b

–2024 8 –10841.7  10.0 –1763.8  5.7b –1748.5  6.1a –2894  11 –2315.4  5.7a

–2457.0  2.2a –1897.7  3.5b –1884.6  3.6a –1494.9  10.0 –3203.8  4.0 180  8

–2932  11

–1784.3  6.4

–1522.9  1.7 –3250.5  4.5

–1920.7  2.2

203  8

–2914  12

–1520.9  1.8 –3232.0  4.3

–1922.7  2.2

526.4  3.5

327.75  0.66

219.66  0.44

–1788.1  5.7

–5571.8  3.6

–3220  10

–1928.0  1.2

S DfH S DfH S DfH S DfH S DfH (298.15 K) (298.15 K) (298.15 K) (298.15 K) (298.15 K) (298.15 K) (298.15 K) (298.15 K) (298.15 K) (298.15 K) (J K–1 mol–1) (kJ mol–1) (J K–1 mol–1) (kJ mol–1) (J K–1 mol–1) (kJ mol–1) (J K–1 mol–1) (kJ mol–1) (J K–1 mol–1) (kJ mol–1)

Li

Table 19.11 Entropies and enthalpies of formation of crystalline complex alkali actinide oxides, from NEA‐TDB (Grenthe et al., 1992; Lemire et al., 2001; Guillaumont et al., 2003); see text for explanation.

Oxides and complex oxides

2153

Indian group led by Venugopal and coworkers measured the enthalpy increments of a number uranates of potassium, rubidium, and cesium. They were reviewed by Guillaumont et al. (2003), and some of their recommendations have been included in Table 19.13.

(b)

Ternary and quaternary oxides with alkaline‐earth ions

(i) Enthalpy of formation The following perovskites with alkaline‐earth ions containing tetravalent actinide ions have been studied thermodynamically: BaUO3 (Williams et al., 1984; Cordfunke et al., 1997), BaPuO3 (Morss and Eller, 1989), BaAmO3 and SrAmO3 (Goudiakas et al., 1990), BaCmO3, and BaCfO3 (Fuger et al., 1993). Efforts to obtain the strontium analog of BaUO3, SrUO3, resulted in a perovskite phase with the empirical formula Sr2UO4.5 (crystallographic formula Sr2(Sr2/3U1/3)UO6) (Cordfunke and IJdo, 1994). Also BaUO3 cannot be prepared with a Ba/U ratio of exactly 1, as was found independently by Barrett et al. (1982), Williams et al. (1984), and Cordfunke et al. (1997). The latter two groups determined the enthalpy of the ideal composition by extrapolating the data for different Ba/U ratios and found excellent agreement [(1690  10) kJ mol1 and (1680  10) kJ mol1]. However, there are several reports of studies on materials claimed to be SrUO3 and BaUO3. Huang et al. (1997a) derived the enthalpy of formation of SrUO3.1 from Knudsen effusion mass spectrometric measurements. Ali et al. (2001) used a comparable method (but a complex reaction) for SrThO3. Using the Goldschmidt tolerance factor t, expressed as t ¼ (RBa þ RO)/(21/2) (RAn þ RO), where RBa, RO, and RAn represent the ionic radii of Ba2þ, O2, and the actinide 4þ ion, respectively, Morss and Eller (1989) showed that the enthalpy of formation of the complex oxides from BaO and AnO2 becomes less favorable as t decreases. This correlation was extended by Fuger et al. (1993) to a large number of complex oxides of the general formula MM0 O3 (M ¼ Ba, and M0 ¼ Ti, Hf, Zr, Ce, Tb, U, Pu, Am, Cm, and M ¼ Sr, and M0 ¼ Ti, Mo, Zr, Ce, Tb, Am) and allowed the prediction of the enthalpy of formation of yet unprepared actinide(IV) complex oxides with BaO and SrO. This correlation was in accordance with the inability to obtain stoichiometric BaUO3. Cordfunke et al. (1997) suggested that a continuous series exists between BaUO3–Ba1þyUO3þx–Ba3UO6. The oxidation of U4þ ions is accompanied by the formation of metal vacancies on the Ba and U sites, and Ba substitution on the U‐vacancies, finally resulting in Ba2(Ba,U)O6. Ba2U2O7 does not belong to this series, which is explained by the fact that Ba2U2O7 is a complex oxide containing pentavalent uranium. For the system Sr–U–O it was shown by Cordfunke et al. (1999) that the enthalpies of formation of the U(VI) compounds linearly depend on the Sr/U ratio (Fig. 19.19). The data fall into two groups, the

2154

Thermodynamic properties of actinides and actinide compounds

pseudo‐hexagonal types (Sr3U11O36, Sr2U3O11, SrUO4, and UO3) and the perovskite types (Sr5U3O14, Sr2UO5, Sr3UO6). Takahashi et al. (1993) studied the enthalpies of formation of SrUO4y (0 y 0.5) also finding an almost linear relationship. Complex oxides of the formula nAO · mAnO3 with alkaline‐earth ions containing hexavalent actinides are well known. AUO4 compounds have been identified and thermochemically characterized for magnesium, calcium, strontium, and barium. Also the enthalpies of formation of many A3AnO6 (An ¼ U, Np, Pu) and quaternary Ba2A0 AnO6 (A0 ¼ Mg, Ca, Sr and An ¼ U, Np, Pu) compounds have been determined (see Table 19.12). All the values listed have been taken from the NEA assessments (Grenthe et al., 1992; Silva et al., 1995; Lemire et al., 2001; Guillaumont et al., 2003) except for those on curium and californium compounds (Fuger et al., 1993). The enthalpy of formation from the binary oxides, here called the enthalpy of complexation DcplxH, is an excellent measure for the stability of these compounds. It can be calculated easily for the uranates, but not for complex Np(VI) oxides or for complex Pu(VI) oxides, because NpO3(c) and PuO3(c) are unknown. For the construction of Fig. 19.20, we have therefore utilized the value estimated in Section 19.5.1. The exothermic enthalpy effect of the reactions indicated in Fig. 19.20 implies that the compounds are thermodynamically stable at room temperature, assuming a negligible entropy change upon the formation of the complex oxides from the binary oxides. Extrapolation of the trends indicated that the beryllium compounds are not stable under these conditions.

Fig. 19.19 The enthalpy of formation in the strontium uranates in the Sr–U VI–O system (after Cordfunke et al., 1999).

b

a

338.6  1.0

–3159.3  7.9 –3067.5  8.9

–3096.9  8.2 –2995.8  8.8

–2002.3  2.3

–3305.4  4.1 –3295.8  5.9

121.1  0.17

–3245.9  6.5

131.95  0.17 –1857.3  1.5

Alpha form (rhombohedral). Beta form (orthorhombic).

MU2O7 MU3O10 M2UO4.5 MU4O13 M2UO5 M2U2O7 M2U3O11 M3UO6 Ba2MUO6 M3U2O9 M3U11O36 M5U3O14 M3NpO6 Ba2MNpO6 MPuO3 M3PuO6 Ba2MPuO6 MAmO3 MCmO3 MCfO3

MUO3 MUO4



153.15  0.17a



Sr

DfH (298.15 K) S (298.15 K) DfH (298.15 K) S (298.15 K) (kJ mol–1) (J K–1 mol–1) (kJ mol–1) (J K–1 mol–1)



S (298.15 K) (J K–1 mol–1)

Ca





Mg

S (298.15 K) DfH (298.15 K) (J K–1 mol–1) (kJ mol–1)

Ba

–3042.1  7.9 –3023.3  9.0 –1539.0  7.9

–5243.7  5.0 –3263.4  3.0 –3257.3  5.7 –4620.0  8.0 –15903.8  16.5 –7248.6  7.5 –3125.8  5.9 –3122.5  7.8

–2494.0  2.3 –5920  20 –2632.9  1.9

298  15

296  15

–1544.6  3.4 –1517.8  7.1 –1477.9  5.6

–1654.2  8.3 –2997  10

–3085.6  9.6

–3210.4  8.0

–3740.0  6.3

–1672.6  8.6 –1690  10 –1989.6  2.8a 153.97  0.31 –1993.8  3.3 –1988.4  5.4b 260  15 –3237.2  5.0

DfH (298.15 K) (kJ mol–1)



Table 19.12 Entropies and enthalpies of formation of crystalline complex alkaline‐earth actinide oxides, from NEA-TDB (Grenthe et al., 1992; Silva et al., 1995; Lemire et al., 2001; Guillaumont et al., 2003) except for those on curium and californium compounds (Fuger et al., 1993).

2156

Thermodynamic properties of actinides and actinide compounds

Fig. 19.20 Enthalpies of complexation of complex actinide(VI) oxides where A represents a alkali or alkaline earth and An an actinide ion.

There are, as of the time of writing, no thermochemical data on complex oxides containing trivalent actinides (e.g. AmAlO3 or SrAm2O4). Indeed, such measurements are still lacking for the lanthanides. (ii)

Entropy

Low‐temperature heat capacity measurements have been reported for a few alkaline‐earth uranates. The data for the AUO4 monouranates of the series A ¼ Mg to Ba (Table 19.12) need some further discussion. The two measurements for BaUO4 are discordant, though made by well‐known research groups. The results of Westrum et al. (1980) give S (298.15 K) ¼ 177.84 J K1 mol1 whereas the results of O’Hare et al. (1980) gave 153.97 J K1 mol1. In most assessments the latter value is selected because the sample was better characterized. However, the values for the other alkaline‐earth monouranates are from the same set of measurements by Westrum et al. (1980) and the reported data indicate a regular trend with molar volume for the orthorhombic compounds (A ¼ Mg, Sr, Ba). The value of O’Hare et al. (1980) does not fit in the series, which would imply that the values for the other compounds measured by Westrum et al. (1980) are in error, which is not considered in the NEA‐TDB selections (Grenthe et al., 1992). Another way of looking at this problem is to consider the entropy of complexation from the oxides. The values for the orthorhombic monouranates derived from the measurements of Westrum et al. (1980) all suggest that the quantity DcplxS (298.15 K) is positive which is

Halides

2157

the case for most orthorhombic complex oxides. The result for BaUO4 from O’Hare et al. (1980) in contrast, suggests a negative value. Clearly further measurements are required to solve this problem. (iii)

High‐temperature properties

High‐temperature heat capacity data have been measured for the AUO4 compounds of the series A ¼ Mg to Ba and have been evaluated by Cordfunke and O’Hare (1978); the resulting recommended equations are summarized in Table 19.13. They agree with the less exhaustive selections of the NEA assessment (Grenthe et al., 1992). Melting points of these compounds are not known. The high‐temperature properties of the other alkaline‐earth compounds are poorly known. Recently, Japanese researchers have extensively studied materials claimed to be stoichiometric BaUO3 and SrUO3. The heat capacity (Matsuda et al., 2001), thermal expansion, thermal conductivity and melting point (Yamanaka et al., 2001), and the vaporization behavior (Huang et al., 1997a) were measured. Vaporization measurements have also been made for SrUO3 (Huang et al., 1997b) and BaPuO3 (Nakajima et al., 1999b). Dash et al. (2000) reported enthalpy increments of Sr3U11O36 and Sr3U2O9. The relevant thermodynamic data extracted from these studies are listed in Table 19.12. (c)

Other ternary and quaternary oxides/oxysalts

Enthalpies of formation data for uranium carbonates, nitrates, phosphates, arsenates, and silicates have been measured and the available data were reviewed and summarized in the NEA‐TDB assessments (Grenthe et al., 1992; Guillaumont et al., 2003). Heat capacity and entropy data have hardly been measured for these compounds and only estimates are available. The data are summarized in Table 19.14. Also included are the enthalpies of formation of several actinide (Th,U) bearing mineral phases reported by Helean et al. (2002, 2003) and by Mazeina et al. (2005) using high temperature solution calorimetry. Data for complex oxides or oxyacids of other actinides are not known with sufficient accuracy for inclusion in this chapter.

19.6 HALIDES

Because of the fundamental and applied interest in the many actinide halides, their thermodynamic properties have received much attention. The authoritative assessment by Fuger et al. (1983), which formed the basis for the data in the second edition of this work, is still the major source of information though parts of it have been updated in the NEA‐TDB series on Chemical Thermodynamics (U through Am).

f

e

d

c

b

a

(a) (b) (a)

(a) (b)

(a) (b)

0.64475 –4.6201 –0.3954 –2.7776 –0.142

–1.52851 –1.13403 –5.4375

–2.08007 –3.54904

–1.0966 –2.09664

Cordfunke et al. (1982). Cordfunke and O’Hare (1978). Cordfunke and Konings (1990). Guillaumont et al. (2004). Dash et al. (2000). Matsuda et al. (2001); Yamanaka et al. (2001).

SrUO4 Sr3U2O9 Sr3U11O36 BaUO4 BaUO3

KUO3 K2U2O7 Cs2UO4 Cs2U2O7 Cs2U4O12 MgUO4 CaUO4

Na3UO4 Na2U2O7

NaUO3 Na2UO4

a (10–6) 115.491 162.5384 224.6743 188.901 262.831 280.571 133.258 149.084 164.8814 221.532 423.7262 110.2681 115.6039 113.0100 102.7703 319.18 962.72 153.7812 126.6

b

12.558 269.5 17.0232 75.3158 71.9406 66.7959 46.819 52.6347 69.0394 116.02 355.26 9.1788 16.1

25.1788 14.6532

19.1672 25.8857

c (103)

23.4381

d (106)

2450

[1000]

1025

[800] [800]

[1000] 1193

T (K)

0.920

20.92

DH (kJ mol–1)

f

c

e

e

c

b

b

b

c

c

c

d

d

a

a

c

b

b

a

References

Table 19.13 High‐temperature heat capacity of selected crystalline complex actinide oxides; Cp/(J K–1 mol–1) ¼ a(T/K)–2 þ b þ c(T/K) þ d(T/K)2 (estimated values are in italics, maximum temperatures in brackets).

Halides

2159

Table 19.14 Thermodynamic properties of selected crystalline miscellaneous actinide oxyacids and oxysalts. S (298.15 K) (J K–1 mol–1) Th(NO3)4 Th(NO3)4 · 4H2O Th(NO3)4 · 5H2O ThTi2O6 ThSiO4 (thorite) ThSiO4 (huttonite) UO2CO3 UO2(NO3)2 UO2(NO3)2 · 2H2O UO2(NO3)2 · 3H2O UO2(NO3)2 · 6H2O UO3 · 1/2NH3 · 1⅔H2O UO3 · ½NH3 · 1½H2O UO3 · ⅔NH3 · 1⅓H2O USiO4 U0.97Ti2.03O6 Ca1.46U0.69Ti1.85O7 (UO2)3(PO4)2 (UO2)2P2O7 UPO5 UP2O7 UO2SO4 UO2SO4 · 2.5H2O UO2SO4 · 3H2O UO2SO4 · 3.5H2O U(SO4)2 U(SO4)2 · 4H2O U(SO4)2 · 8H2O (UO2)3(AsO4)2 (UO2)2As2O7 UO2(AsO3)2 NpO2(NO3)2 · 6H2O PuTi2O6 a b c

543.1  0.4

144.2  0.3 241  9 327.5  8.8 367.9  3.3 505.6  2.0

118  12 410  14 296  21 137  10 204  12 163.2  8.4 246.1  6.8 274.1  16.6 286.5  6.6 180  21 359  32 538  52 387  30 307  30 231  30 516.3  8.0

DfH (298.15 K) (kJ mol–1) –1445.6  12.6 –2707.0  12.6 –3007.9  4.2 –3096.5  4.3 –2117.6  4.2 –2110.9  4.7 –1691.3  1.8 –1351.0  5.0 –1978.7  1.7 –2280.4  1.7 –3167.5  1.5 –1770.3  0.8 –1741.3  0.8 –1705.8  0.8 –1991.3  5.4 –2977.9  3.5 –3610.6  4.1 –5491.3  3.5 –4232.6  2.8 –2064  4 –2852  4 –1845.1  0.84 –2607.0  0.9 –2751.5  4.6 –2901.6  0.8 –2309.6  12.6 –3483.2  6.3 –4662.6  6.3 –4689.4  8.0 –3426.0  8.0 –2156.6  8.0 –3008.2  5.0 –2909  8

References a a a b b b c c c c c a a a c b b c c c c c c c c c c c c c c c b

Cordfunke and O’Hare (1978). Helean et al. (2002, 2003); Mazeina et al. (2005). NEA‐TDB (Grenthe et al., 1992; Silva et al., 1995; Lemire et al., 2001; Guillaumont et al., 2003).

19.6.1 (a)

Hexahalides

Solid hexahalides

The enthalpy of formation of UF6 is a key value for the U–F thermochemistry. This value is well established by fluorine combustion calorimetry (Johnson, 1979). The heat capacity of UF6 has been measured accurately up to the melting point and beyond (Brickwedde et al., 1948), from which the entropy can be

Thermodynamic properties of actinides and actinide compounds

2160

Table 19.15 Thermodynamic properties of the crystalline hexa‐ and pentahalides at 298.15 K; estimated vales are given in italics.

UF6 UCl6 NpF6 PuF6 PaCl5 PaBr5 UF5(a) UF5(b) UCl5 UBr5 NpF5

Cp(298.15 K) (J K–1 mol–1)

S (298.15 K) (J K–1 mol–1)

DfH (298.15 K) (kJ mol–1)

166.8  0.2 175.7  4.2 167.44  0.40 168.1  2.0 – – 132.2  4.2 132.2  12.0 150.6  8.4 160.7  8.0 132.8  8.0

227.6  1.3 285.5  1.7 229.09  0.50 221.8  1.1 238  8 289  17 199.6  3.0 179.5  12.6 242.7  8.4 292.9  12.6 200  3

–2197.7  1.8 –1066.5  3.0 –1970  20 –1861  20 –1147.8  14.4 –866.8  14.9 –2075.3  5.9 –2083.2  4.2 –1039.0  3.0 –810.4  8.4 –1941  25

References a a a a b b a a a a a

NEA‐TDB (Grenthe et al., 1992; Lemire et al., 2001; Guillaumont et al., 2003). Fuger et al. (1983) taking in account the enthalpy of dissolution of the standard state of the metal (Fuger et al., 1978) and more recent auxiliary values. a

b

derived. The resulting values are summarized in Table 19.15. Unfortunately the situation is different for NpF6 and PuF6. Low‐temperature heat capacity measurements have been made for NpF6, also into the liquid range, but a determination of its enthalpy of formation is lacking. Lemire et al. (2001)   derived this  quantity from the estimated difference Df H  ðMF6 ; crÞ  Df H  MO2þ 2 ; aq obtained by interpolation in the AnF6 series. For PuF6, no thermodynamic measurements of the solid phase have been made except for the vapor pressure. But since the properties of the gas phase are well established (see below), the enthalpy of formation and the standard entropy can be derived with reasonable accuracy. UCl6 is the only known solid actinide hexachloride. Its thermochemical properties were intensely studied in the World War II period. Thereafter Gross et al. (1971) and Cordfunke et al. (1982) performed enthalpy‐of‐solution studies on this compound and derived the enthalpy of formation. As discussed by Grenthe et al. (1992) the values for UCl6 from these two studies disagree (unlike similar work for UCl5) and the results of Cordfunke et al. (1982) were selected. The heat capacity and entropy for UCl6 at low temperature were measured by Ferguson and Rand in the early 1940s, as reported in Katz and Rabinowitch (1951); the high‐temperature heat capacity of UCl6 is an estimate by Barin and Knacke (1973). The high‐temperature heat capacity equations plus the melting data of the hexahalides are summarized in Table 19.16. (b)

Gaseous hexahalides

The gaseous hexafluorides of U, Np, and Pu were studied extensively in the 1950s and 1960s. Gas‐phase electron diffraction, Raman, and infrared studies

Halides

2161

have established the octahedral structure (Oh symmetry) and the molecular and vibrational parameters. From these data the entropies can be calculated accurately; the major uncertainty coming from neglect of excited electronic states for incompletely filled f‐shells. The enthalpies of formation of these species can then be obtained from analyses of the vapor pressure measurements that have been performed and such data have been derived in the NEA‐TDB series (Grenthe et al., 1992; Lemire et al., 2001; Guillaumont et al., 2003). The molecular properties of AmF6, and thus the entropy, can be extrapolated from those of the other actinide hexahalides (Kim and Mulford, 1990). Its enthalpy of formation is derived from the extrapolation of the mean bond enthalpy of the other actinide hexahalides, which linearly varies along the actinide series. Except for UCl6, no other gaseous hexachlorides are known. The molecular properties of UCl6 have not been determined experimentally. Estimates (Hildenbrand et al., 1985) have been used in the NEA assessments (Grenthe et al., 1992; Guillaumont et al., 2003) but more recently reliable results from quantum chemical calculations have become available (Han, 2001). An approximate value for the enthalpy of formation of UCl6 is derived from vapor pressure measurements performed in the 1940s (see Grenthe et al. (1992)). 19.6.2 (a)

Pentahalides

Solid pentahalides

Fuger et al. (1983) accepted the enthalpies of formation of PaCl5, PaBr5, and a‐UF5 and b‐UF5 (as well as some intermediate uranium fluorides) to be well established based upon single reliable thermochemical studies by Fuger and Brown (1975) for the Pa compounds, and by O’Hare et al. (1982) for the UF5 modifications. For UCl5, Fuger et al. (1983) discussed the results of three different studies, but these gave an unclear picture. The discrepancy seems to be resolved by the measurements of Cordfunke et al. (1982). Properties of UBr5 are based on high‐temperature heterogeneous equilibria and have large uncertainties when extrapolated to 298.15 K. The other pentahalides (PaF5, NpF5) have not been studied thermochemically. The properties of PaF5 cannot yet be estimated because of insufficient experimental data. Those of NpF5 have been approximated by Lemire et al. (2001) on the basis of the experimental observation that NpF5 does not disproportionate to NpF6(g) and NpF4(cr) below 591 K (Malm et al., 1993). The experimental basis for the entropies of the actinide pentahalides is very poor. Low‐temperature heat capacity measurements have only been reported for UF5 (Brickwedde et al., 1951), but the sample contained 17% UF4 and UO2F2. Fuger et al. (1983) adjusted the result for S (298.15 K) by þ11.3 J K1 mol1, to be consistent with dissociation pressure measurements in the U–F system. Fuger et al. also gave (rough) estimates of the entropies of PaCl5, PaBr5, and UCl5, based on a systematic difference between MX4 and MX5 compounds.

NpCl4

PaCl4 UCl4

NpF4 PuF4 ThCl4

UF4

UF5 UF5 PaCl5 UCl5 PaBr5 ThF4

PuF6 UCl6

NpF6

UF6

cr l cr l cr cr l b a cr cr cr cr l cr l cr cr cr l cr cr l cr –0.11

–0.0900

–0.83646 –1.091 –0.615

–0.41316

–1.255

–0.1926 –0.1926

–0.7406

–2.87646

a (106)

106.859 162.34 112.5

122.173 133.9 114.5194 174.0 122.635 127.53 120.290 167.4

35.564

140.164

36

48.6448

9.684 3.114 23.267

20.5549

8.37

35.0619 30.2085 30.2085

383.798 1.9962 352.547 110.076

c (103)

52.318 215.338 62.333 150.344 168.1 173.427 214 125.478 125.478

b

49.8

950 863

59.6

47 47 61.5

1305 1300 1043

811

44.79

1309

31.5 35.6 35.4 41.8

17.0 20.9

317 452 398 621 579 600 556 1383

17.520

19.196

DtrsH (kJ mol–1)

327.91

337.20

Ttrs (K)

a

a

a

b

b

b

a

a

c

c

b

b

b

a

b

a

a

b

b

a

a

a

a

a

References

Table 19.16 High‐temperature heat capacity of the actinide halides; Cp /(J K–1 mol–1) ¼ a(T/K)–2 þ b þ c(T/K) þ c(T/K)2 (estimated values in italics); Tmin ¼ 298.15 K; Ttrs and DtrsH refer to transition or fusion, as can be deduced from the phase indicators.

f

e

d

c

b

a

b l cr l cr cr l cr l cr cr cr cr cr cr cr cr cr cr cr cr cr cr 31.120 27.5 24 26.360 20.68 15.0 24.2672

97.971 101.23 104.5 105.018

–0.32 –0.638

0.70542 0.812 0.707

9.9579

30 12.97

29.7064

15.1

87.78 89.6 91.35

127.6 171.5 119.244 172 119 129.7 176 145.603 165.7 106.541 105.2 104.078

0.4583 0.36 0.24

–1.0355 –1.0 –1.0355

–1.97485

–0.6067

–0.62

NEA‐TBD (Grenthe et al., 1992; Lemire et al., 2001; Guillaumont et al., 2003). Fuger et al. (1983). Rand (1975). Burnett (1966). Weigel and Kohl (1985). Peterson and Burns (1973).

UF3 NpF3 PuF3 AmF3 CmF3 UCl3 NpCl3 PuCl3 AmCl3 CmCl3 UBr3 NpBr3 PuBr3 UI3

UI4

NpBr4 ThI4

UBr4

ThBr4

38

779

49.0 50 55 48.1  0.4 47.9  0.4 43.9 48 47.1

36.8 36.1 35.4

50 48

800 843

1768 1735 1700 1666  20 1679  20 1115 1075 1041 990  5 997  5 1003 975 935 800

36  5

54.4

791

952

a

a

a

a

d,e

d,e,f

a

a

a

e

e

a

a

a

b

a,b

b

b

a

b

a

c

c

Thermodynamic properties of actinides and actinide compounds

2164

Their value for PaCl5 is, however, significantly lower than that derived by Kova´cs et al. (2003) by combining the entropy of sublimation from the work of Weigel et al. (1969) with the entropy of the gas obtained from quantum chemical data. A comparison to other MCl5 compounds showed that this value for solid PaCl5 is unexpectedly high compared to UCl5 and the transition metal pentahalides, which Kova´cs et al. attributed to the distinctly different crystal structure of PaCl5 (pentagonal bipyramidal). However, no calorimetric measurements have been performed for any of the pentachloride compounds, and all entropies have been derived from (other complex) solid–gas equilibria. The selected solid pentahalide data are listed in Table 19.15. (b)

Gaseous pentahalides

PaCl5, PaBr5, UF5, UCl5, UBr5, and PuF5 are the only gaseous pentahalides that have been studied experimentally. Vapor pressure measurements for the protactinium pentahalides were reported by Weigel et al. (1969, 1974) from which the enthalpy of formation of PaCl5 has been derived (see Table 19.17). The interpretation of the UF5 vapor pressure measurements is complicated due to the existence of dimeric molecules and dissociation reactions. The enthalpy of formation of UF5 can also be derived from molecular equilibrium measurements by mass spectrometry. At least six such studies have been performed. They were reviewed in the NEA‐TDB (Grenthe et al., 1992; Guillaumont et al., 2003) and the recommended values from that work are included in Table 19.17. Also for UCl5(g) and UBr5(g), molecular equilibrium studies have been performed. The derived enthalpies of formation are included in Table 19.17. An approximate value for the enthalpy of formation of PuF5 was calculated indirectly from ionization potential measurements by Kleinschmidt (1988), but since this value is rather uncertain, it is not included. Table 19.17 Thermodynamic properties of the gaseous hexa‐ and pentahalides; estimated values are given in italics.

UF6 UCl6 NpF6 PuF6 AmF6 PaF5 PaCl5 UF5 UCl5 UBr5 a b

S (298.15 K) (J K–1 mol–1)

DfH (298.15 K) (kJ mol–1)

References

376.3  1.0 438.0  5.0 376.643  0.500 368.90  1.00 399.0  5.0 385.6 440.8 386.4  10.0 438.7  5.0 498.7  5.0

–2148.6  1.9 –985.5  5 –1921.66  20.00 –1812.7  20.1 –1606  30 –2130  50 –1042  15 –1913  15 – 900  15 –648  15

a

NEA‐TDB (Grenthe et al., 1992; Lemire et al., 2001; Guillaumont et al., 2003). Kova´cs et al. (2003).

a a a a b b a a a

Halides

2165

Little experimental information exists on the molecular properties of the actinide pentahalides. Spectroscopic experiments of matrix‐isolated UF5 molecules (Kunze et al., 1976; Paine et al., 1976; Jones and Ekberg, 1977) indicate a tetragonal pyramidal structure (C4v). Quantum chemical calculations (Wadt and Hay, 1979; Onoe et al., 1997) showed that energy barrier between the C4v and the trigonal bipyramidal structure (D3h) is small ( cos f  j2 F7=2 G07 > sin f and f is determined by the relative magnitudes of the crystal field parameters. There are four electronic transitions (Oh symmetry) that should be observed in these systems. Three optical and/or near‐infrared transitions between the J ¼ 5/2 and J ¼ 7/2 states have been reported for most of these octahedral complexes. In some cases the G7!G8 transition of the J ¼ 5/2 state that occurs in the infrared or near‐infrared region has also been observed. These electronic absorption data plus the EPR data on the ground state allow the parameters (including orbital reduction factors) of the Eisenstein–Pryce model (Eisenstein and Pryce, 1960; Hecht et al., 1971; Edelstein, 1977; Eichberger and Lux, 1980) for an octahedral f1 system to be evaluated as shown in Table 20.1. Note the much different ground state g‐values for various compounds. A careful study of the magnetic susceptibility of NpF6 and NpF6 diluted in UF6 (very slightly distorted Oh symmetry) in the temperature range 4.2–336.9 K has been reported by Hutchison et al. (1962). The g‐value extrapolated to infinite dilution was found to be 0.605  0.004. The g‐value was found to vary as a function of the mole fraction of NpF6 (six different samples of varying mole fractions were measured), with a maximum value of 0.694  0.011 at a mole fraction of 0.34. No explanation has been given for these observations. The magnetic measurements agree with EPR measurements of NpF6 diluted in UF6 (Hutchison and Weinstock, 1960) and with the calculations of Eisenstein and Pryce (1960). Analysis of the fluorine superhyperfine structure measured by electron‐nuclear double resonance (ENDOR) in single crystals of NpF6 diluted in UF6 (Butler and Hutchison, 1981) indicates that 5f orbital covalency effects are approximately an order of magnitude larger in NpF6 than in 4f complexes. This is consistent with the larger radial extension of 5f orbitals as compared to 4f orbitals. Similarly, a series of papers on the EPR of U5þ in complexes of the type MUF6 (M ¼ Li, Na, Cs, NO) measured at 77 K have been reported (Rigny and Plurien, 1967; Drifford et al., 1968; Rigny et al., 1971a). These octahedral complexes showed a small g‐value anisotropy due to axial distortions. The data have been analyzed on this basis. Other, similar complexes with M ¼ K, NH4, Rb, Ag, and Tl showed no EPR spectra at 77 K, which has been attributed to larger distortions of theUF 6 octahedra. Selbin and coworkers (Selbin et al., 1972; Selbin and Sherrill, 1974) have measured and analyzed the room‐temperature EPR spectra of a number of polycrystalline salts of the type

2244

Magnetic properties

   2  UX 6 and UOX5 (X ¼ F , Cl , Br , no signal observed for UF6 ). Their analysis was based on an extension of the standard octahedral theory to include a tetragonal distortion. Although observations of the room temperature signals for the UOX2 species have been questioned (Lewis et al., 1973), 5 the magnitude of the g‐value obtained is consistent with that of other 5f1 hexahalide or distorted hexahalide complexes. Some EPR and optical measurements have been reported or reanalyzed for NpF6, UX 6 (X ¼ F, Cl, Br) (Eichberger and Lux, 1980), and PaX2 6 (X ¼ F, Cl, Br, I) (Brown et al., 1976) (see Table 20.1). Early studies on the optical and magnetic properties have been reported for 5f1 ions in uranates, neptunates, and one plutonate (Keller, 1972; Miyake et al., 1977a, 1979, 1982, 1984; Kanellakopulos et al., 1980a). For these compounds, the magnetic ions (U5þ, Np6þ, Pu7þ) are surrounded by an octahedral or distorted octahedral array of oxygen atoms. Hinatsu, in a series of recent papers, has reanalyzed earlier data and provided new measurements on some compounds plus other distorted actinide perovskites. He has given a consistent analysis of this body of data (Hinatsu and Edelstein, 1991; Hinatsu et al., 1992a,b; Hinatsu, 1994a,b). Hinatsu’s results are consistent with the g‐values of about 0.7 reported by Lewis et al. (1973) from EPR measurements for U5þ diluted in LiNbO3, LiTaO3, and BiNbO4. The latter study could not find any verifiable EPR spectra due to U5þ in a number of magnetically concentrated crystals including NaUO3 and LiUO3. In an interesting paper, Bickel and Kanellakopulos (1993) compiled magnetic data on a number of 5f1 ternary actinide oxides that they analyzed in terms of a temperature‐dependent term and a temperature‐independent term (see equation 20.8). Table 20.4 lists the results of the magnetic measurements and some crystallographic data for a number of compounds. The compounds studied have the 5f1 ion at the center of a more or less distorted AnO6 anionic array. For U5þ and Np6þ compounds in this symmetry, the first excited level is more than 4000 cm1 higher in energy. Therefore the room‐temperature moment should reflect the value of 1.24mB obtained from a G7 ground state. Table 20.4 shows the experimental values, all of which are lower than the theoretical value. Bickel and Kanellakopulos (1993) argue that this can be interpreted, along with the observed TIP for these compounds, as due to the degree of covalency. They also point out that the observation of low‐temperature magnetic transitions in these compounds, due to exchange interactions, depends on the shortest An–An distance. This behavior is reminiscent of that found in actinide metals and alloys. In that case, when the actinide ion–actinide ion distance is less than ˚ , the matea certain critical distance (the Hill parameter), approximately 3.5 A rial exhibits itinerant behavior (TIP). At a distance greater than the critical distance, localized magnetism is found. For the ionic compounds discussed by Bickel and Kanellakopulos, the equivalent behavior is exchange interactions at shorter distances vs no magnetic ordering at larger distances. See Chapter 21 for further discussion.

7þ 5f 1 2F5/2; Th3þ ð6d1Þ, Pa4þ, U5þ, Np6þ, NpO2þ 2 , Pu

2245

Table 20.4 Magnetic and crystallographic data for 5f ternary actinide oxides. All data are taken from Bickel and Kanellakopulos (1993). 1

Compound LiUO3 NaUO3 KUO3 RbUO3 Li3UO4 Li7UO6 Na2NpO4 K2NpO4 Li4NpO5 Na4NpO5 Li6NpO6 Na6NpO6 Ba3NpO6 Sr3NpO6 Ca3NpO6 BaNpO4 Li5PuO6

Crystal symmetry

Shortest An–An distance (pm)

wTIP (106 emu mol1)

meff ( 300 K) (mB)

rhombohedral orthorhombic cubic cubic tetragonal hexagonal orthorhombic tetragonal tetragonal tetragonal hexagonal hexagonal orthorhombic orthorhombic orthorhombic orthorhombic

400 413 429 432 449 615 444 423 443 459 520 567 627 598 574 404

364 395 440 280 238 372

1.117 1.125 1.216 1.216 0.922 0.873 1.053

331 342 389 376 340 283 347 335 300

0.994 1.018 1.083 1.005 1.012 0.933 1.089 1.089 0.955

T0 (K)* 16.9 31.1 16.0 32.0 6

a

7 19.5 20

a a a a a a

18.3

* Ordering temperature. a No ordering observed above 4.2 K.

A recent report of a newly synthesized U5þ hexakisamido complex (Meyer et al., 2000) reported g ¼ 1.12 as measured by EPR at 20 K with a meff ¼ 1.16 BM from 5 to 35 K. This complex has six N atoms arranged in octahedral coordination around the U5þ ion from each of six dbabh groups (dbabh ¼ 2,3:5,6‐dibenzo‐7‐azabicyclo[2.2.1]hepta‐2,5‐diene) and its g‐value is in accord with those measured for hexahalogenated U5þ complexes. The magnetic susceptibility of UCl5 (a dimeric compound with a pseudo‐ octahedral array of chlorine atoms, two of which are bridging) as a function of temperature was first reported by Handler and Hutchison (1956) and later by Fuji et al. (1979). The latter authors have also reported the g‐value as measured by EPR (Miyake et al., 1977b). They have combined the magnetic data with optical measurements by Leung and Poon (1977) and fitted all the data with a crystal field model based on a weak C2v distortion of the predominantly octahedral (Oh) crystal field. However, they calculated an isotropic g‐value on the basis of octahedral symmetry when in fact their model predicts an anisotropic g‐tensor. Soulie and Edelstein (1980) have adopted a different point of view by noting the large difference in distances between the two bridging chlorines (U– ˚ ) and the four nonbridging chlorines (U–Cl 2.43 A ˚ ) in the crystal Cl 2.68 A structure. They used the Newman superposition model (Newman, 1971) and fitted the optical and magnetic data. Their best fit gave gx ¼ 0.226 and gy  gz  1.186, as observed. This gx‐value could not be experimentally observed because

2246

Magnetic properties

of the large magnetic field necessary to do so. However the derived spin–orbit coupling constant of 1196 cm1 is much smaller than that observed in any U5þ compound and the calculated meff 0.85mB is lower than the measured value of 1.08mB. In the eight‐fold cubic coordination of Na3UF8, Lewis et al. (1973) measured a g‐value of 1.2 at 7 K. The magnetic susceptibilities of M3UF8 (M ¼ Na, Cs, Rb, and NH4) have been measured from 8 to 300 K (Rigny et al., 1971b). The experimental data were fitted very satisfactorily with a model that assumed a trigonal (D3d) distortion to the eight‐fold cubic coordination of the fluorine atoms. An interesting EPR study of six organouranium(V) complexes (five organouranium amides and one organouranium alkoxide) in dilute frozen solutions at 15 K has been published (Gourier et al., 1997). From an interpretation of the anisotropic g‐values obtained from the EPR spectra, a picture of the bonding was established for these compounds. The major assumption made was that all ligands, with the exception of the alkoxide ligands, were bound only weakly with the 5f orbitals of the U(V) ion so that only the ground J ¼ 5/2 crystal field state has to be considered. With this assumption the experimental g‐values of the organouranium(V) amide complexes could be quantitatively fit. This model did not work with the organouranium(V) alkoxide compound. This was attributed to a strong U(V) 5f‐OR (where R is the alkyl group on the alkoxide) interaction so that the above weak field approximation is not valid. The magnetic uranium bis‐cycloheptatrienyl sandwich compound [K(C12H24O6)][U(
7 ‐C7H7)2] has been synthesized (Arliguie et al., 1995). The ionic configuration of the U ion should be 5f3 since the formal charge on each of the cycloheptatrienyl rings is 3. However, theoretical calculations by Li and Bursten (1997) have shown that the U ion has a localized 5f1 configuration. Thus this molecule can be considered as the 5f1 analog of uranocene because the molecular orbitals of the C7H7 rings have the same group theoretical symmetries as the cyclooctatetraenyl rings of uranocene. The EPR spectrum of a frozen solution of this compound in methyl‐tetrahydrofuran (THF) was measured below 15 K and the ENDOR spectrum was measured at selected fields at 4 K (Gourier et al., 1998). From an analysis of the measured g‐tensor they concluded that the strong participation of the 5fd orbitals in bonding and spin–orbit effects were responsible for the f‐orbital composition of the singly occupied molecular orbital. The proton ENDOR measurements allowed a lower limit of rp  4  102 to be set for the positive spin density on the 2pp carbon orbitals of the cycloheptatrienyl ligands in this compound. Two bimetallic, pentavalent uranium derivatives [(MeC5H4)3U]2[m‐1,4‐ N2C6H4] and [(MeC5H4)3U]2[m‐1,3‐N2C6H4] have been synthesized and magnetic measurements have been performed from room temperature to 5 K (Rosen et al., 1990). In each of these dimers, the two U atoms are coupled to the imido N atoms on the substituted benzene rings. The U‐dimer coupled by the [m‐1,4‐N2C6H4] moiety can form a conjugated ring while the other U‐compound

5f 2 3H4; U 4þ, Np5þ, Pu6þ

2247

Table 20.5 Magnetic data for some U(V) compounds. The values given below are for the range of temperatures where the Curie–Weiss formula approximately holds. The references should be checked for details. Compound

T range (K)

y (K)

meffa (mB)

References and notes

[(Me3Si)2N]3UN(p‐C6H4CH3)

5–40 140–240

–1.3 –98

1.49 2.26

Stewart and Andersen (1998)

[(Me3Si)2N]3UNSiMe3

5–40 140–280

–3.6 –54

1.61 2.04

Stewart and Andersen (1998)

(C5H5)3UNSiMe3

5–40 140–280

–0.7 –82

1.19 1.83

Rosen et al. (1990)

(MeC5H4)3UNPh

5–40 140–280

1.03 –110

1.25 1.96

Rosen et al. (1990)

[(MeC5H4)3U]2[m‐1,3‐N2C6H4]

5–40 140–280

–3.95 –134

1.30 2.12

Rosen et al. (1990)

[(MeC5H4)3U]2[m‐1,4‐N2C6H4]

5–40 140–280

–147

2.08

Rosen et al. (1990). This compound becomes antiferromagnetic at 20 K. See discussion in text

a

All magnetic data are given per U atom. To obtain the value per formula unit for dimeric compounds multiply by the sqrt(2).

cannot. From room temperature down to 40 K the magnetic susceptibility measurements of these two compounds were similar. Below 40 K an antiferromagnetic coupling was observed for the [2m‐1,4‐N2C6H4] coupled dimer but no such coupling was observed from the [m‐1,3‐N2C6H4] coupled dimer. A value of the exchange constant J, of –19 cm1, was obtained for the magnitude of the exchange interaction by a fit of the observed magnetism to that calculated for an isolated one‐dimensional dimer as a model for the [m‐1,4‐N2C6H4] coupled dimer. Table 20.5 lists the magnetic properties of some U(V) imide compounds. 20.4 5f 2 3H4; U 4þ, Np5þ, Pu6þ

U(IV) compounds have been widely studied. The total crystal‐field splitting for the 3H4 ground term of the 5f2 configuration is usually of the same order as or greater than 200 cm1 (kT at room temperature). Thus only the ground crystal field state or perhaps the two or three lowest‐lying states will provide first‐order contributions to the observed magnetic susceptibility. Measurements over

2248

Magnetic properties

as wide a temperature range as possible are clearly desirable. For most U4þ compounds, few optical data are available so magnetic data are usually interpreted by considering only the ground 3H4 term, determining the crystal‐ field splittings for a particular point symmetry group (usually from crystallographic data), choosing a ground state either empirically or by calculation (e.g. point‐charge or angular‐overlap model), and then calculating the susceptibility. A J ¼ 4 state in a point group symmetry lower than tetragonal will split into nine singlet states. In higher symmetries, there will be some singlet states and some doubly and/or triply degenerate states. If a singlet state lies lowest there will be a range of temperatures for which the compound will exhibit only TIP. Some examples from the voluminous literature follow. One of the few cases for which anisotropic magnetic susceptibility measurements of a single crystal have been reported is UCl4 (Gamp et al., 1983). In this compound, the anisotropy of the susceptibility is very large (w⊥ > wk) which makes powder measurements difficult because the crystallites tend to reorient in a static homogeneous magnetic field with the axis of greatest susceptibility parallel to the field. This effect is stronger at low temperatures and depends on the magnitude of the applied field. Gamp et al. (1983) found it impossible to obtain reliable powder susceptibility data for UCl4 at temperatures below 20 K, even with a field as small as 0.05 T. The powder reoriented slowly and the measured susceptibility data increased with time until it reached the value of w⊥ measured in the single crystal. This is illustrated in Fig. 20.5. Using the available optical data, Gamp et al. (1983) obtained a reasonable fit between the calculated single crystal susceptibilities and the experimental values. The fit could easily have been improved with only minor changes in the crystal field parameter set or the introduction of orbital reduction factors. The UCl4 crystal field scheme was examined directly by neutron inelastic scattering by Delamoye et al. (1986). The first excited state (G4 ! G5) was found at 92(1) cm1, which is in disagreement with the 109 cm1 deduced from susceptibility (Gamp et al., 1983). The neutron study also observed the next  higher level G05 at 1125(3) cm1. This last level is in good agreement with the predictions of the susceptibility. Here is an example where the susceptibility predicts a value of the crystal field energy splitting too large compared to that measured by neutrons. As in PuO2 (see below), one could invoke the exchange interaction (Colarieti‐Tosti et al., 2002), but there appears a more direct explanation in terms of coupling between the magnetic and lattice modes (phonons). This is illustrated by the most unusual behavior of the temperature dependence of the G4 ! G5 excitation as shown in Fig. 20.6. From simple Boltzmann statistics, the peak should decrease by only 20% of its strength between 10 and 50 K. Instead it has lost 70% of its intensity, broadened considerably, and shifted to lower energy. At 160 K (where the peak should still be 40% of its 10 K value), it has lost about 90% of its intensity and shifted to 75 cm1, a decrease in frequency of almost 20%. The only explanation for these effects is that there is strong coupling to the lattice vibrations (phonons). It is not

5f 2 3H4; U 4þ, Np5þ, Pu6þ

2249

Fig. 20.5 The values of wk and w⊥ obtained from measurements on a single crystal of UCl4 and the calculated average magnetic susceptibility of polycrystalline UCl4 derived from these measurements. The calculated average susceptibility is compared with susceptibility measurements on a polycrystalline sample of UCl4 at 0.5 T. For the polycrystalline sample in a magnetic field, a strong force is applied along the strong magnetic axis of the crystallites and tends to reorient the crystallites. Thus the measured value of a powdered sample has a susceptibility greater than that calculated from the values of wk and w⊥ obtained from the single crystal measurements. See Gamp et al. (1983) for details.

surprising, therefore, that simple predictions of the crystal‐field splittings from the susceptibility should not agree with the neutron measurements, as interactions with the phonons are not considered. Efforts to include configuration interaction to explain the discrepancy between simple models and the experiments may also have to be taken into account (Zolnierek et al., 1984), but before these large interactions with the lattice modes are understood, such an effort would appear premature. Another interesting experiment was performed on UCl4 to look for covalency effects between the U and Cl atoms (Lander et al., 1985). In these experiments a single crystal is placed in a high magnetic field (4.6 T in this case) and then from the scattering of polarized neutrons the magnetization in the unit cell is deduced. If, for example, there would be strong mixing of the U 5f and Cl p‐states then one might expect to observe a reduced spin density at the Cl site. Naively, it would be expected that covalency is small in compounds such as UCl4, and such mixing of the 5f states unlikely. This indeed was the case, and no spin density was found at the Cl site. However, a small spin density midway between the

2250

Magnetic properties

Fig. 20.6 The temperature dependence of the intensities of the neutron inelastic scattering of the G4 ! G5 excitation in UCl4. The shift in energy and the loss of intensity provide evidence for strong electronic–phonon coupling. Reprinted from Delamoye et al. (1986). Copyright 1986 with permission from Elsevier.

U and Cl ions was modeled as an electron transfer from the 5f to the 6d antibonding orbital, and then a covalent bond formed between the U 6d and Cl p‐states. Given the interesting possibilities for covalency in 5f compounds, it is perhaps surprising that experiments such as these have not been more common in the actinides. The difficulty is that single crystals are required (and they must be at least 10 mm3) and their low‐temperature properties must be well‐ known. For example, an experiment was reported on UCp3Cl, where the covalency effects would be expected to be much larger than in the tetrachloride. Unfortunately, although good crystals were available, on cooling to low temperature many phase transitions occurred (Raison et al., 1994a,b). Such complexities made it impossible to examine the spin densities and learn the details of the covalency. New efforts along these lines would seem worthwhile, especially

5f 2 3H4; U 4þ, Np5þ, Pu6þ

2251

as neutron intensities have increased (which means that smaller crystals can be used), available magnetic fields have increased (now up to 10 T and in special cases to 15 T), and local‐spin‐density‐approximation methods can be used to calculate the expected covalency effects. Blaise et al. (1986) have measured the temperature‐dependent magnetic susceptibility of a single crystal of tetrakis(1,1,1‐trifluoro‐4‐phenylbutane‐2,4‐dionato) U(IV). The data were fit with a crystal field model based on distorted cubic symmetry. Optical and magnetic studies on U(NCS)8(NEt4)4 (Et ¼ C2H5) have been published by several groups (Folcher et al., 1976; Soulie and Goodman, 1976, 1979; Carnall et al., 1980; Kanellakopulos et al., 1980c). In this compound the uranium ion is at a site of cubic symmetry (in cubic symmetry no magnetic anisotropy is possible) in the first coordination sphere surrounded by eight nitrogen atoms from the thiocyanate groups. By fitting the measured magnetic susceptibility in the temperature range 4.2–290 K, Soulie and Goodman (1976, 1979) evaluated the appropriate free‐ion and crystal field parameters. They found good agreement above 30 K with the measured susceptibility but with significant deviations below this temperature. These deviations were attributed to a slight D4h distortion of the cubic symmetry (confirmed by Raman spectra), which was not taken into account in their calculations. Subsequently Kanellakopulos and coworkers (Carnall et al., 1980; Kanellakopulos et al., 1980c) determined another set of empirical parameters using cubic crystal field parameters obtained from the assignment of the optical spectrum. They then took into account the lower symmetry by using perturbation theory to split the ground triplet state in cubic symmetry into a singlet state and a higher‐lying doublet state. The use of this model and the introduction of an orbital reduction factor resulted in satisfactory agreement between the calculated and experimental susceptibility data. The optical spectra of U(BD4)4 diluted in Zr(BD4)4 were measured by Bernstein and Keiderling (1973) and reinterpreted by Rajnak et al. (1984b). The U4þ ion in the U(BD4)4 molecule in this host crystal has tetrahedral symmetry (Td) but the pure compound is polymeric with a lower site symmetry at the metal ion. Shinomoto et al. (1983) synthesized the U(BH3CH3)4 compound which is monomeric and has the same (Td) symmetry found for U(BD4)4 diluted in Zr(BD4)4. The magnetic susceptibility of U(BH3CH3)4 has been measured from 2 to 330 K. Using the eigenvectors obtained from the reanalysis of the Keiderling data, the magnetic data could be fit. However in order to get the best fit, Rajnak et al. (1984b) empirically adjusted the energy splitting between the ground E‐state and the first excited T1 state (Td) and included an orbital reduction factor of k ¼ 0.85. In addition to the magnetic susceptibility, the temperature dependence of the solution shifts of the 1H, 11B, and 13C NMR have been obtained for the M(BH3CH3)4 (M ¼ Pa, Th, U, Np) (Gamp et al., 1987; Kot and Edelstein, 1995). Because of the high symmetry at the paramagnetic actinide metal ion, there is no contribution due to the metal ion dipolar term. Thus the measured NMR shifts should arise from the unpaired spin

2252

Magnetic properties

density transferred from the metal ion to the ligand orbitals. The traditional equation used to determine the unpaired spin density is: DH b A ¼ hSz i H0 3kT gðh=2pÞ

ð20:15Þ

where DH=H0 is the NMR shift, b is the Bohr magneton, k is the Boltzmann constant, A is the hyperfine constant in energy units, g is the nuclear gyromagnetic ratio, and h is Planck’s constant. hSz i is the thermal average of the spin operator and can be calculated from the eigenvectors obtained from the optical analyses. The usual assumptions made in these types of analyses is that the above equation is valid for all crystal field states using the same value of A, and that each of the f‐orbitals is equally effective in transferring spin into ligand orbitals. Difficulties were encountered in analyzing the NMR shifts in the actinide methylborohydrides. McGarvey (1998) has shown that the data can be explained if it is assumed that each of the f‐orbitals contributes a different amount of spin into the ligand orbitals. The temperature dependence of the magnetic susceptibility of three U4þ sulfates, U(SO4)2 · 4H2O, U6O4(OH)4(SO4)6, and U(OH)2SO4, in the temperature range 4.2–300 K has been reported by Mulak (1978). These three compounds have a similar antiprismatic coordination about the U4þ ion by oxygen anions with almost the same U–O distances. Using a simplified model of the U4þ ion with a 3H4 ground term, J ¼ 4 as a good quantum number in a D4d crystal field, and only the energy splittings between the two lowest crystal field states as empirical parameters, the temperature dependence of the magnetic susceptibility was fitted. A further low‐symmetry distortion has to be introduced (which split the energy levels that were doubly degenerate in D4d symmetry) in order to obtain satisfactory agreement. Despite the very similar coordination environment about the U4þ ion in the three compounds, there are significant differences in the low‐temperature magnetic behavior. In particular, the magnetic susceptibility for U(OH)2SO4 from 4.2 to 21 K is approximately constant while above 21 K the susceptibility decreases with a temperature dependence typical of a paramagnetic compound with a degenerate ground state. This low‐temperature behavior was attributed to a crystallographic transition induced by the cooperative Jahn–Teller effect. Hinatsu et al. (1981) reported the temperature dependence from 1.8 to 300 K of a crystalline uranium(IV) sulfate that showed a broad maximum in the susceptibility at 21.5 K. They assumed a one‐dimensional chain structure with U atoms linked by hydroxyl groups (or possibly oxygen atoms) and fitted their data to an exchange interaction between uranium atoms along this one‐ dimensional chain. The synthesis of the organometallic ‘sandwich’ compound uranocene, U(C8H8)2, by Mu¨ller‐Westerhoff and Streitwieser (1968) led to a renaissance in the organometallic chemistry of the actinide series (Seyferth, 2004). Magnetic susceptibility measurements have played an important role in the discussions

5f 2 3H4; U 4þ, Np5þ, Pu6þ

2253

of the electronic structure of these types of compounds. Karraker et al. (1970) initially reported the temperature‐dependent susceptibility of U(C8H8)2 and interpreted the data on the basis of a crystal field of C8h symmetry acting on the 3H4 ground term. The data were fitted with a Jz ¼ 4 ground state and the inclusion of an orbital reduction factor to account for covalency. This model also fitted the experimental results for Np(C8H8)2 and Pu(C8H8)2. Hayes and Edelstein (1972) then proceeded to calculate the necessary crystal field parameters using molecular orbital theory and the Wolfsberg–Helmholz approximation. From the calculated crystal field parameters and published free‐ion parameters they found the ground crystal field state to be the Jz ¼ 3 level. More careful measurements by Karraker (1973) have shown that the susceptibility of U(C8H8)2 at low temperature became temperature independent and was attributed by Hayes and Edelstein as being due to a possible low‐temperature crystal structure phase transition causing the U4þ ion to be at a symmetry site lower than C8h. This model was disputed by Amberger et al. (1975). They recalculated the crystal field parameters for uranocene in three ways: using the purely electrostatic approach, the angular overlap model, and a molecular orbital model. Assuming rigorous D8h symmetry, they found that a crystal‐ field splitting with a singlet ground state (Jz ¼ 0) and an excited doublet state at 17 cm1 (Jz ¼ 1) gave the best agreement with their molecular orbital calculation and the experimental data. Subsequently, Edelstein et al. (1976) showed that some uranocene‐type molecules with alkyl or phenyl groups attached to the cyclooctatetraene rings showed the temperature‐dependent behavior expected for a degenerate ground state down to 4.2 K. This behavior is inconsistent with the Amberger et al. model. Warren (1977) has discussed the magnetic properties of uranocene‐type compounds in his extensive review on ligand field theory of f‐orbital sandwich complexes. Later experimental and theoretical papers have utilized the magnetic data as tests of the validity of their data and/or calculations (Dallinger et al., 1978; Boerrigter et al., 1988; Chang and Pitzer, 1989). Another class of organometallic U(IV) compounds that have been thoroughly studied is tetrakis(cyclopentadienyl)uranium(IV), UCp4, and its tris(cyclopentadienyl) derivatives, Cp3UR, where R ¼ BH4, BF4, OR, F, Cl, Br, I, etc (Kanellakopulos, 1979). These compounds have been divided into two categories: those showing a small dipole moment and a small range of temperature‐ independent susceptibilities; and a second category exhibiting larger dipole moments and a more extended range of temperature‐independent susceptibilities. These differences have been attributed to an increasing trigonal distortion in the second category of compounds. Amberger et al. (1976) have used three different semiempirical calculations to estimate the two crystal field parameters needed for the assumed Td symmetry of UCp4. The temperature‐dependent magnetic susceptibility of UCp4 was then fitted assuming a weak crystal field of lower symmetry that split the tetrahedral energy levels. The tetrahedral wave functions were used for the calculations and the energy differences of four levels

2254

Magnetic properties

plus one scaling parameter were varied. Satisfactory agreement with the experimental data was obtained. Amberger (1976a,b) also analyzed optical spectra of UCp4 and Cp3UCl assuming Td symmetry. He further analyzed the fine structure of the spectrum and determined the crystal‐field splitting of the ground 3H4 term. Using tetrahedral wave functions and the crystal‐field splitting of the ground term he was able to satisfactorily fit the observed susceptibility using only one scaling parameter. Magnetic data for a number of Cp3UR compounds have been given by Aderhold et al. (1978). A number of other structurally characterized U(IV) compounds were synthesized and magnetic measurements are reported. Some results are listed in Table 20.6. Most of these compounds are monomeric, but a number of dimers and even some higher oligomers have been found. Compounds with amido, amidoamine, alkoxide, and other ligands were characterized and are given in Table 20.6. In general for U(IV) compounds Curie–Weiss behavior is found at higher temperatures with the susceptibility tending toward temperature‐independent behavior at the lowest temperatures. The U4þ ion is a non‐Kramers’ ion with two 5f electrons and will usually have an orbital singlet ground state at low temperatures (this depends on the point symmetry at the U4þ ion and will generally be true for lower‐symmetry groups) which is the reason for the temperature‐independent behavior. For dimeric U4þ compounds and higher ˚ ) or if the bridging oligomers, if the U–U distances are short (less than 3.6 A ligand(s) facilitate electron exchange, deviations from this type of behavior suggest magnetic interactions between the two U centers. Le Borgne et al. (2002) reported the syntheses, crystal structures, and magnetic properties of heteronuclear trimetallic compounds of the type [{ML (py)}2U] (M ¼ Co, Ni, Zn) and [{CuL(py)}M0 {CuL}] (M0 ¼ U, Th, Zr) where L ¼ N,N0 ‐bis(3‐hydroxysalicylidene)‐2,2‐dimethyl‐1,3‐propanediamine and py is pyridine. The crystal structures show that the two ML fragments are orthogonal and linked to the central U ion by two pairs of oxygen atoms from each of the Schiff base ligands. In each of the compounds the three metal ions are linear and the eight oxygen atoms exhibit similar dodecahedral geometry around the U ion. The magnetic susceptibilities of the Co2U, Ni2U, and Cu2U compounds were measured and compared with that of the appropriate Zn2U derivative, where the paramagnetic 3d ion was replaced by the diamagnetic Zn2þ ion. By subtracting the magnetic data of the U–3d diamagnetic ion complexes from similar data for the U–paramagnetic 3d ion complexes (in the temperature range from 300 to 2 K), a weak antiferromagnetic coupling was observed between the Ni2þ and the U4þ ions, and a ferromagnetic interaction was found between the Cu2þ and U4þ ions. In a later paper (Salmon et al., 2003), this same group synthesized and magnetically and structurally characterized [ML2(py)U(acac)2] and [(ML2)2U], where M ¼ Cu and Zn and L2 ¼ N, N0 ‐bis(3‐hydroxysalicylidene)‐2‐dimethyl‐1,3‐propanediamine, and acac is acetylacetonate (C5H7O2). Again the Cu, U compounds and the Cu, Zn analogs

Table 20.6 Magnetic data for some U(IV) and neptunyl(V) compounds. The values given below are for the range of temperatures where the Curie–Weiss formula approximately holds. At lower temperatures more complex magnetic behavior is observed. The references should be checked for details. Compound

T range (K) y (K)

Cp3UOH [Cp3U]2O Cp3USH [Cp3U]2S Cp{2UCl2 Cp{2UF2 FU[N(Me3Si)2]3 MeU[(Me3Si)2N]3

110–300 140–300 110–300 120–300 100–300 100–300 5–280 25–100 120–280 5–140 140–280 5–40 160–280 80–280 5–120 140–280 5–90 100–200 120–300 100–300 110–300 120–300 110–300 20–100 30–102 27–84 40–90 4.6–100 20–300 20–300 20–300 150–300 150–300 40–350 40–350 40–350 40–350 15–40 50–300 10–70 150–300

Te{U[N(Me3Si)2]3}2 {U[N(Me3Si)2]2}2[mN(p‐tolyl)]2 MeU[OC(CMe3)3]3 U[OC(CMe3)2H]4 U[OSi(CMe3)3]4 [(MeC5H4)3U]2[m‐CS2] [(MeC5H4)3U]2[m‐S] [(MeC5H4)3U]2[m‐Se] [(MeC5H4)3U]2[m‐Te] [(MeC5H4)3U]2[m‐PhNCO] U[N(CH2CH3)2]4 U[N(CH2CH2CH3)2]4 U[N(CH2CH2CH2CH3)2]4 U[N(C6H5)2]4 [U(CH3NCH2CH2NCH3)2]3 (H3N(CH2)3NH3)U2F10 · 2H2O (H3N(CH2)4NH3)U2F10 · 3H2O (H3N(CH2)6NH3)U2F10 · 2H2O (C5H14N2)2U2F12 · 2H2O (C2H10N2)U2F10 [(C5N2H14)2(U2F12) · 2H2O] [(C5N2H14)2(H3O)(U2F11)] [(C4N2H12)2(U2F12) · H2O] [(C6N2H14)2(U3O4F12)] (NpO2)2C2O4 · 4H2O [NpO2(O2CH)(H2O] (NpO2)2(O2C)2C6H4 · 6H2O

meff* (mB)

2.45  0.01 2.17  0.01 2.65  0.01 2.64  0.01 3.32 3.11 2.91 2.99 3.18 3.10 3.28 4.37 3.34 –54 3.15 –17 2.59 –33 2.71 –11 2.69 –22 2.82 –12.5 3.01 –84.5 2.93 –72.2 2.85 –11.8 3.02 –89.5 2.87 –4.8 2.74 7.2 2.69 2.2 2.44 24.8 2.84 –30.5 2.5 –24.7  1.3 4.00 –30.9  0.4 3.47 –41.7  1.1 3.94 –1.3 3.09 þ21 3.24 14.7 3.59 78.8 3.72 15.7 3.35 153.6 4.01 12.5 2.71 12.7 2.81 7.75 2.54 29.8 2.29

–125 –108 –83 –62.5 –7.6 –137 –7 –14 –32 –19 –40

References and notes a a a a b b c c c c c c c d d d d d e e e e f g g g h h i i i j k l m

* All magnetic data are given per U atom. To obtain the value per formula unit for dimeric compounds multiply by the sqrt(2). a Spirlet et al. (1996). Cp ¼ C5H5.

2256

Magnetic properties

were shown to be very similar structurally so that the magnetism of the appropriate Zn, U compound could be subtracted from the magnetism of the Cu, U compound to obtain the influence of the Cu2þ ion on the exchange interactions between the Cu and U ions. For the dimeric compound the difference in wT vs T was approximately constant from 300 to 100 K with a value of 040  0.05 cm3 mol1 K, similar to that of an isolated Cu2þ ion. Below 100 K the difference in magnetic behavior is indicative of antiferromagnetic exchange between the U4þ – Cu2þ ions. Similar experiments were performed with the trimetallic [(ML2)2U] complexes and it was found that the low‐temperature magnetic behavior of the [(CuL2)2U] compound was also antiferromagnetic. The low‐ temperature magnetism in the latter compound is different from ferromagnetic interaction found in the somewhat structurally similar [{CuL(py)}U{CuL}] described earlier. A similar type of experiment has been reported for an oxalate‐bridged U(IV)– Mn(II) compound, K2MnU(C2O4)4 · 9H2O (Mortl et al., 2000). In this compound the U(IV) ion is linked to four Mn(II) ions by each of the oxalate ligands and each of the Mn(II) ions are also linked by the oxalate ligands to four U(IV) ions. The magnetic susceptibility of this compound has been measured from 2 to 300 K. For this compound, the experimental magnetic measurements have been interpreted as the sum of the individual U(IV) and Mn(II) contributions. No indication of magnetic coupling has been found between the U(IV) ion and the Mn(II) ion down to 2 K. A number of complex U4þ fluoride compounds have been synthesized and structurally characterized. As part of the determination of their physical properties, the temperature‐dependent magnetic susceptibilities have been measured and analyzed (over the appropriate temperature range using the Curie–Weiss equation). Table 20.6 lists magnetic data for some structurally diverse U(IV) complex fluoride compounds.

Lukens et al. (1999). Cp{ ¼ 1,3‐(Me3C)2C5H3. Stewart (1988). If no y values are given, the data are not very linear (1/w vs T) in the given range and the meff values are approximate. d Brennan et al. (1986). e Reynolds and Edelstein (1977). f Reynolds et al. (1977). Three uranium atoms form a linear chain with the central U atom linked to the two terminal U atoms by a triple nitrogen bridge. g Francis et al. (1998). h Almond et al. (2000). i Allen et al. (2000). The data (1/w vs T) are not very linear in the 40–350 K range, the meff values are approximate. j IV Allen et al. (2000). This compound is formulated as a (UVI 2 U O4 F12 ) complex, the meff given is for the formula unit or per the U(IV) atom, and is an approximate value due to the nonlinearity of the 1/w vs T data. k Jones and Stone (1972). l Nakamoto et al. (1999). m Nakamoto et al. (2001). b c

5f 3 4I9/2; U 3þ, Np4þ, Pu5þ

2257

There have been a few measurements performed on NpOþ 2 compounds. The compounds that are formulated as having dimeric neptunyl ðNpOþ 2 Þ2 units exhibit complex magnetic behavior at low temperatures. Metamagnetism, that is the field‐induced transformation of a compound from an antiferromagnetic state to a ferromagnetic state, was originally reported by Jones and Stone (1972) for the neptunyl(V) oxalate complex, (NpO2)2C2O4 · 4H2O. This compound exhibited Curie–Weiss behavior above 15 K (see Table 20.6). The susceptibility displayed a peak characteristic of an antiferromagnetic transition with TN ¼ 11.6  0.1 K. However the susceptibility maximum shifted to lower temperatures as the external magnetic field was increased, and above 0.075 T the susceptibility peak disappeared and ferromagnetic saturation was observed. From these observations, it was concluded that this compound was metamagnetic. Recent magnetic studies have been reported for neptunyl(V) formate and phthalate compounds [NpO2(O2CH)(H2O)] and (NpO2)2(O2C)2C6H4 · 6H2O (Nakamoto et al., 1999, 2001). The formate complex, which forms infinite two‐dimensional sheets linked by NpOþ 2 bonding, follows the Curie–Weiss law from 50 K to room temperature (see Table 20.6). Below 50 K, this neptunyl compound exhibits complex magnetic behavior that is attributed to ferromagnetic ordering with Tc ¼ 12 K. The authors note the situation in the neptunyl(V) formate complex is similar to that found earlier in the neptunyl(V) oxalate complex and attributed in the earlier work to metamagnetism. The neptunyl phthalate magnetic data can be fit in two regions with the Curie–Weiss law as shown in Table 20.6. Below 4.5 K, complex magnetic ordering is found that is attributed to the existence of two kinds of Np sublattices, one is ferromagnetic and the other is antiferromagnetic. 20.5 5f 3 4I9/2; U 3þ, Np4þ, Pu5þ

UH3 has a ferromagnetic transition at approximately 172 K and a saturation magnetic moment in the temperature range 63–196 K of approximately 1mB (Gruen, 1955). The magnetic susceptibilities of the uranium(III) halides are listed in Table 20.7 (Berger and Sienko, 1967; Jones et al., 1974). UF3 followed the Curie–Weiss law down to about 125 K, below which temperature the susceptibility increased more rapidly than expected from the higher‐temperature data (Berger and Sienko, 1967). Jones et al. (1974) reported the magnetic susceptibilities of U trihalides (Cl, Br, and I). For the most part, the properties could be understood on the basis of crystal field calculations. Of special interest was the report of antiferromagnetic magnetic ordering (as judged by a maximum in the susceptibility) at 22.0, 15.0, and 3.4 K in the U‐trihalides Cl, Br, and I. Extensive neutron studies have also been performed on these compounds (Murasik and Furrer, 1980; Murasik et al., 1981, 1985, 1986; Schmid et al., 1990). Neutron diffraction confirmed the hexagonal crystal structure for UCl3 and UBr3, but then surprisingly found that the assumed TN values of Jones et al. were not

Magnetic properties

2258

Table 20.7 Magnetic data for some M(III) actinide halides, M ¼ U3þ, Np3þ, and Pu3þ.

Compound

T range (K)

y (K)

meff (mB)

125–293 25–117 25–76 5–14 25–200 3.5–50

–110  5 –89 –54 –9.1 –34

3.67  0.06 3.70  0.08 3.57  0.08 2.67  0.10 3.65  0.05

NpCl3 a‐NpBr3

75–240 10–30

–83.5

2.81  0.09

a‐NpBr3 NpI3

50–125 3–15

–86

3.26  0.40

NpI3 PuCl3 PuBr3 PuBr3 PuI3

25–60 5–100 2.2–20 25–60 5–50

–42 –7.9 –0.55 –10.5 þ4.15

3.17  0.40 1.11  0.04 0.81  0.08 1.01  0.10 0.88  0.08

UF3 UCl3 UBr3 UI3 UI3 NpCl3

TN (K)

wTIP (106 emu mol1)

References a

22.0  1.0 15.0  0.5 3.4  0.2

4.5  0.5

b,c b,c b,c b

6400  100

b

10 850  320

b,d

17 000  7 000

b

b

b

b b b b

4.75  0.10

b,e

a

Berger and Sienko (1967). Jones et al. (1974). c Further magnetic ordering in these compounds have been observed from neutron scattering experiments (Murasik et al., 1986; Schmid et al., 1990). d Sample is estimated to contain 5% NpOI2 impurity. e Low‐temperature phase is ferromagnetic. b

correct. The actual ordering temperatures in UCl3 and UBr3 are 6.5 and 5.4 K, respectively. The ordered moments are 2mB for both systems. However, at lower temperatures there is a second transition (3.8 K for UCl3 and 3.0 K for UBr3) to a more complex magnetic structure. On cooling, the moments are initially parallel to the crystallographic c‐axis, but then rotate to perpendicular to c‐axis at low temperature, and with a magnetic moment of only about 0.8mB. These lower‐temperature transitions were not apparently observed by Jones et al. (1974). The neutron work also determined the crystal field transitions that range from about 20 to 400 cm1. From the crystal field level scheme they showed that many of the properties could be understood on the basis of the extreme magnetic anisotropy. There is antiferromagnetic exchange only along the chains of U atoms along the c‐axis. The peak in the susceptibility in this case is actually not an indication of the antiferromagnetic order, but rather the competition between the exchange and anisotropic contributions to the susceptibility. All these measurements, both the original magnetic and more recent neutron studies, were performed on polycrystalline samples, which makes the amount of information extracted in the neutron study quite remarkable.

5f 3 4I9/2; U 3þ, Np4þ, Pu5þ

2259

Furthermore, a relatively sharp mode was observed at 32 cm1 in both UCl3 and UBr3 at low temperature and was assigned to one‐dimensional spin–wave excitations along the c‐axis. These studies would be most interesting to continue with single crystals. The whole question of one‐dimensional magnetism is now much in fashion; the exchange interactions in actinides are usually stronger than in the lanthanides, thus making the examples more interesting. It is furthermore a salutary lesson in making a simple interpretation of the susceptibility curves. EPR measurements have been reported for surprisingly few U3þ compounds and the data up to 1977 were discussed by Boatner and Abraham (1978). Crosswhite et al. (1980), from their analysis of the optical spectrum of U3þ diluted in LaCl3, have calculated gk ¼ –4.17, which agrees well with the magnetic resonance value of |gk| ¼ 4.153 (Hutchison et al., 1956). Magnetic susceptibility data for Cs2NaUCl6 (Hendricks et al., 1974) (Table 20.2) as a function of temperature have been given. A recent optical study of U3þ diluted in Cs2NaYCl6 has given the energy levels for this system and shown that a G8 (Oh) state is lowest in energy (Karbowiak et al., 1998) consistent with the magnetic data. The temperature‐dependent magnetic susceptibility of a number of substituted tris‐cyclopentadienyl U and Nd compounds and their Lewis base adducts has been measured and are listed in Table 20.8. The EPR spectra of these compounds also have been measured as powders or frozen glasses and compared with the corresponding Nd3þ compounds (4f3 configuration) (Lukens, 1995).

Table 20.8 Magnetic data for some Cp003 M and Cp003 M L complexes (M ¼ Nd, U).a,b

Cp003 Nd Cp003 Nd · (C6H11NC) Cp003 Nd · (tBuNC) Cp003 U Cp003 U · (C6H11NC) Cp003 U · (tBuNC) Cpz3 U a

meffc (5 K) (mB)

meffd (200–300 K) (mB)

g1e

g2e

g3e

mefff (5 K) (mB)

1.65 1.75 1.69 2.03 1.76 1.78 2.13

3.70 3.60 3.91 3.32 3.25 3.14 3.37

2.48 (48) 2.51 (21) 2.25 (19) 3.41 (50) 2.51 (96) 2.41 (12) 3.60 (16)

2.08 (1.29) 1.76 (29) 2.08 (11) 1.65 (2.08) 1.59 (1.17) 1.75 (9) 2.36 (34)

0.18 (0.69) 0.88 (7) 0.86 (9) 0.85 (75) 0.72 (1.76) 0.29 (65) 0.70 (0.98)

1.62 1.60 1.59 1.94 1.53 1.49 2.21

From Lukens (1995). Cp00 ¼ 1,3‐(Me3Si)2C5H3, Cp{ ¼ 1,3‐(Me3C)2C5H3. c Calculated directly from measured magnetic susceptibility value at 5 K, w ¼ C/T, meff ¼(8C)1/2. d w ¼ C/(T–y), meff ¼(8C)1/2, y values are not given. e Values obtained by fitting EPR spectra obtained from powders at 5 K. The g3 component has been obtained for some complexes solely from the least squares fit. In cases where the error is greater than the value, g3 is considered unreliable. f Calculated from the EPR g‐values. b

Magnetic properties

2260

Table 20.9 Magnetic data for some U(III) compounds. The values given below are for the range of temperatures where the Curie–Weiss formula approximately holds. At lower temperatures more complex magnetic behavior is observed. The references should be checked for details. Compound

T range (K)

y (K)

meffa (mB)

References and notes

90–300

–127

3.65

Ba2UCl7

105–300

–95

3.25

CsUCl4

60–300

–36

3.16

Cs2LiUCl6

85–300

–103

3.56

210–300

–80

3.74

Karbowiak and Drozdzynski (1998a) Karbowiak and Drozdzynski (1998a) Karbowiak and Drozdzynski (1998b) Karbowiak and Drozdzynski (1998b) Karbowiak et al. (1996) Stewart and Andersen (1998) Stewart (1988)

SrUCl5

RbU2Cl7 [(Me3Si)2N]3U

35–280

–12  1

3.37  0.02

{U[N(Me3Si)2]2}2 [mN(H) (2,4,6‐Me3C6H2)]2

80–280 9–60

–71 –22.5

3.53 2.87

a

All magnetic data are given per U atom. To obtain the value per formula unit for dimeric compounds multiply by the sqrt(2).

Magnetic susceptibility results for some other U(III) compounds are given in Table 20.9. Two interesting dimeric molecules were reported by Korobkov et al. (2001). One of these two dimeric molecules, [Li(THF)4]2{U2[(–CH2–)5]4‐calix[4]tetrapyrrole}[m‐I]4 had two U(III) ions held together by the [(–CH2–)5]4‐calix[4]tetra˚ . The second compound pyrrole ligand with a short U–U distance of 3.4560(8) A [Li(THF)2]2(m‐Cl)2{U2[(‐CH2‐)5]4‐calix[4]tetrapyrrole}Cl2 · THF, formally a mixed valence U(III)–U(IV) dimer with a similar geometry as the first dimer, ˚ . The magnetic moment of the also had a short U–U distance of 3.365(6) A U(III)–U(III) dimer was 1.99mB (per U) at 300 K falling to 0.55mB (per U) at 2 K. For the U(III)–U(IV) dimer the magnetic moment at 300 K was 3.04mB (per mole) and 1.03mB (per mole) at 2 K. The authors suggest that the low moment for the U(III)–U(III) dimer could be due to antiferromagnetic behavior at low temperatures while the U(III)–U(IV) dimer could be explained by the sum of the magnetic moments of two isolated U(III) and U(IV) compounds (no magnetic exchange). Clearly much further work has to be done to determine whether magnetic exchange takes place in these dimers. NpCl4 (Table 20.7) was reported to have a ferromagnetic transition at 6.7 K (Stone and Jones, 1971). Kanellakopulos et al. (1980c) reported the temperature dependence of the magnetic susceptibility data for NpCl4 and ((C2H5)2N)4Np (NCS)8 and presented an analysis of these data. This group (Stollenwerk et al., 1979; Dornberger et al., 1980; Stollenwerk, 1980) also measured and discussed

5f 4 5I4; Np3þ, Pu4þ

2261

the optical spectra and magnetic susceptibilities of Cp4Np (Cp ¼ C5H5) and Cp3NpX where X ¼ Cl, Br, and I. Low‐temperature magnetic susceptibility data for NpBr4 are given in Table 20.7. From magnetic susceptibility measurements (Karraker and Stone, 1980) and EPR measurements (Bernstein and Dennis, 1979; Edelstein et al., 1980) of hexachloro complexes of Np4þ, the ground state of the 4I9/2 term was shown to be G8 (Oh). Limits on the ratios of the fourth‐ to the sixth‐order crystal field parameters have been determined, and these limits are consistent in the 4þ 4þ 4þ isostructural series MCl2 6 ; M ¼ Pa ; U ; Np : Depending on the cation 1 involved, the G8 state may be split by 5–10 cm due to small deviations from Oh symmetry. The free‐ion g‐value ( 0.6) for Np4þ deduced from the data are much reduced from the value of 0.77 obtained from optical data. Warren (1983) has suggested that the rather large value of the orbital reduction factor needed to fit the EPR data could be due to the occurrence of the Ham effect (which would change the value of the ratios of the crystal field parameters needed to fit the data). However EPR data obtained at liquid‐helium temperatures for Np (BH4)4 and Np(BD4)4 diluted in the corresponding Zr(BH4)4 and Zr(BD4)4 hosts show that the doublet G6 state (Td) of the 4I9/2 term is lowest (Rajnak et al., 1984a). Again the free‐ion g‐value (0.515) is much lower than expected. Richardson and Gruber (1972) claimed that they observed the EPR spectrum of Np4þ diluted in ThO2. EPR and optical spectra of Np4þ diluted in ZrSiO4 at 4.2 K were obtained by Poirot et al. (1988) with measured ground G6 state (D2d symmetry) g‐values of |gk| ¼ 0.8 (6) and |g⊥| ¼ 2.59 (2), consistent with the optical analysis. SrNpO3 and BaNpO3 show magnetic transitions at 31 and 48 K, respectively (Kanellakopulos et al., 1980b; Bickel and Kanellakopulos, 1993). A sharp increase in magnetization was observed below the transition temperature, which suggests a complicated magnetic structure.

20.6

5f 4 5I4; Np3þ, Pu4þ

The magnetic susceptibility and magnetization of NpHx (x ¼ 2.04, 2.67, and 3) have been measured in the temperature range 4–700 K (Aldred et al., 1979). The dihydride data could be fitted with a crystal field model based on cubic symmetry (Oh) for the Np3þ, 5f 4 configuration, with a nominal 5I4 ground state split into a ground G3 doublet and a G4 and a G5 triplet at 512 and 549 cm1, respectively. The G1 singlet is calculated to be at 1851 cm1 above the G5 state. Magnetic data for Cs2NaNpCl6 (Hendricks et al., 1974) are shown in Table 20.2 and were assigned as due to the magnetic properties of the G5 (Oh) ground state. The magnetic properties of NpX3 (X ¼ Cl, Br, and I) are given in Table 20.7 (Jones et al., 1974). Magnetic susceptibilities from 2.5 to 50 K for Pu4þ in three hexachloro complexes were reported by Karraker (1971). Surprisingly, one of the compounds,

2262

Magnetic properties

Cs2PuCl6, had a temperature‐dependent paramagnetism at low temperatures, which means a non‐Kramers doublet is the lowest state. The other two PuCl2 6 complexes had temperature‐independent susceptibilities at the lowest temperatures, which arises from a singlet state being the ground state. These data have been interpreted on the basis of a model based on the distorted Oh symmetry of the PuCl2 6 octahedron. Magnetic susceptibility measurements have been reported for Pu(C8H8)2 and Pu(C8H7R)2, where R is an alkyl group (Karraker et al., 1970; Karraker, 1973). These compounds were reported to be diamagnetic. However, the susceptibility is expected to exhibit TIP for the 5I4 state in C8h symmetry if the Jz ¼ 0 state is lowest.

20.7 5f5 6H5/2; Pu3þ, Am4þ

The magnetic properties of PuHx (2.0 x 3) have been measured between 4 and 700 K (Aldred et al., 1979). The cubic PuH2 appears to order antiferromagnetically at 30 K. Cubic Pu compounds with higher hydrogen concentrations order ferromagnetically with higher transition temperatures as x increases. A maximum is reached at T ¼ 66 K and x ¼ 2.7. Hexagonal PuH3 becomes ferromagnetic at 101 K. The temperature dependence of the magnetic susceptibility indicates that the ground state configuration is Pu3þ, 5f5. The magnetic properties of PuX3 (X ¼ Cl, Br, and I) (Jones et al., 1974) are given in Table 20.7. PuCl3 shows an antiferromagnetic transition at 4.5 K while PuI3 has a ferromagnetic transition at 4.75 K. For PuCl3, magnetic susceptibility calculations using wave functions obtained from optical data on Pu3þ diluted in LaCl3 reproduce the observed susceptibility. Magnetic data for the octahedral complex Cs2NaPuCl6 (Hendricks et al., 1974) are given in Table 20.2. EPR measurements of |gk| ¼ 0.585 (2) and |g⊥| ¼ 0.875 (1) were reported for 239 Pu3þ diluted in LaCl3 at 4.2 K by La¨mmermann and Stapleton (1961). These values agreed well with the results obtained from a subsequent optical analysis of this system (La¨mmermann and Conway, 1963). Kot et al. (1993b) measured the EPR spectra of Pu3þ in LuPO4 at 4.2 K and found |gk| ¼ 0.772(2) and |g⊥| ¼ 0.658(2). Pu2O3 becomes antiferromagnetic at TN ¼ 19 K, as judged by the specific heat (Flotow and Tetenbaum, 1981). Magnetic susceptibility and neutron diffraction measurements (T ¼ 4–300 K) also indicate that hexagonal b‐Pu2O3 becomes antiferromagnetic at T 19 K (McCart et al., 1981) with a second transition at 4 K. Neutron diffraction was not initially able to determine the magnetic configurations, but in subsequent neutron work by Wulff and Lander (1988) the configuration with a moment of 0.60mB/Pu and the moments aligned parallel to the unique c‐axis of the hexagonal structure were determined. The ground state moment is consistent with that from the Kramers doublet jJ ¼ 5=2; Jz ¼ 3=2i and the valence state is (as expected) trivalent Pu.

5f 6 7F0; Am3þ, Cm4þ

2263

Table 20.10 Measured g‐values for 5f ions at cubic sites in crystals with the fluorite structure. For each type of host or ion, the matrices are listed in order of increasing lattice constant, or decreasing CF. Data taken at 5 K (Kolbe et al., 1974). 5

Matrix

Ion 3þ

Pu Pu3þ Pu3þ Pu3þ Pu3þ Pu3þ Am4þ Am4þ

CeO2 ThO2 CaF2 SrF2 BaF2 SrCl2 CeO2 ThO2

|g| 1.333 (1) 1.3124 (5) 1.297 (2) 1.250 (2) 1.187 (4) 1.1208 (5) 1.3120 (5) 1.2862 (5)

EPR measurements on Pu3þ and Am4þ at liquid‐helium temperatures in various cubic hosts have been summarized by Boatner and Abraham (1978). For both Pu3þ and Am4þ with a nominally 6H5/2 ground state, strong intermediate‐coupling effects cause the G7 state (Oh) to be the ground crystal field state, rather than the G7 (Oh) state as expected for pure Russell–Saunders coupling (Edelstein et al., 1969). Crystal field mixing between the ground state and the excited J‐states makes the measured g‐value a very sensitive indicator of the magnitude of the crystal field (Lam and Chan, 1974). Table 20.10 illustrates the effect of the decreasing crystal field strength on the measured ground state g‐values. For each type of crystal or ion, the crystal field decreases (the lattice constant of the host matrix increases) as one scans down Table 20.10, and the magnitude of g decreases also. In the limit of zero crystal field mixing of excited multiplets, the ground state g‐value should be |g| ¼ 0.700. ENDOR measurements on Pu3þ in CaF2 have shown the interaction with the nearest neighbor fluorine ions is much stronger than found for the 4f series (Kolbe and Edelstein, 1971). The magnetic data for Am4þ given above have been utilized in conjunction with optical data for Am3þ in ThO2 to estimate the crystal field parameters for AnO2 series (Hubert et al., 1993). The magnetic susceptibility of the high‐Tc superconductor‐related compound Pb2Sr2AmCu3O8 has been measured from 4 to 300 K. The data can be fit with an effective moment for the Am4þ ion of 0.94mB after subtracting off the contribution from the Cu sublattice. This compound shows no superconductivity (Soderholm et al., 1996).

20.8

5f 6 7F0; Am3þ, Cm4þ

A 7F0 ground term has a singlet ground state that is expected to show TIP. The magnitude of the TIP depends on the energy differences to the excited states. Measurements on some Am3þ and Cm4þ compounds sometimes show a

Magnetic properties

2264

Table 20.11 Magnetic susceptibility of Am metal, and some Am3þ and Cm4þ compounds. If more than one set of data are given, the results are from different samples. Temp. range (K)

TIP (106 emu mole1)

Am metal Am metal

102–848

50–300

881 (62) 675

Am metal

100–300

780 (10), 880 (40) 720

Compound 241 241 241 241

Am3þ in solution 243 Am(C5H5)3

room temperature 30–300

Cs2Na243AmCl6 Cs2Na243AmCl6 243 Am2O3 243 AmF3 248 CmF4

15–70 40–300 5–300

4.2–280

4.2–280

Ba248CmO3

4.2–300

248

CmO2

4.2–300

248

CmO2

5–125

meff (mB)

715 (14) 5400 (400) 660 (40) 640 (20) 714 328 (144), 1700 (527), 2800 (224) 2130 (213), 988 (20) 1900 (171), 4100 (164), 2464 (1232)

0.63 3.24 (4), 3.49 (7), 3.04 (3) 1.63 (6), 1.71 (1) 1.63 (4), 1.96 (3), 2.27 (20) 3.36 (6)

References and comments Cunningham (1962) Nellis and Brodsky (1974) Kanellakopulos et al. (1975) Howland and Calvin (1950) Kanellakopulos et al. (1978) Hendricks et al. (1974) Soderholm et al. (1986) Soderholm et al. (1986) Nave et al. (1983) Nave et al. (1983) Nave et al. (1983) Nave et al. (1983) Morss et al. (1989)

temperature dependence that is not understood. In order to analyze these data, a modified Curie law has been utilized and is given in equation (20.8). The few available data for these ions are given in Table 20.11. Karraker et al. measured the magnetic susceptibility of Cs2NaAmCl6 (Hendricks et al., 1974) and found the susceptibility was temperature independent, as expected for a J ¼ 0 ground state, but the magnitude found was much larger than that calculated considering only the second‐order Zeeman effect to the optically determined J ¼ 1 state at 2720 cm1. Subsequent measurements on Cs2NaAmCl6 and Am2O3 agreed much better with the calculated value (Soderholm et al., 1986). Am metal was found to exhibit TIP, suggesting a localized 5f6 configuration plus conduction electrons (Cunningham, 1962; Nellis and Brodsky, 1974; Kanellakopulos et al., 1975). The susceptibility of 248CmO2 should also be temperature‐independent but exhibits Curie–Weiss behavior (Nave et al., 1983; Morss et al., 1989). Nave et al. (1983) also have measured two other 248 Cm4þ compounds and have found complex magnetic behavior that they have analyzed using equation (20.8). Their measurements were performed on samples of mass 50–1000 mg and it should be noted that measurements of different samples of nominally the same material were not very reproducible. A recent

5f 7 8S7/2; Am2þ, Cm3þ, Bk4þ

2265

calculation of the Cm magnetic moment in CmO2 gave 3.39mB/atom. The authors suggested that an itinerant magnetism model based on delocalized electrons might be more appropriate for this system rather than the usual crystal field theory (Milman et al., 2003). See Section 20.14.5 for a more detailed discussion of CmO2. 20.9 5f 7 8S7/2; Am2þ, Cm3þ, Bk4þ

In the limit of pure Russell–Saunders coupling an f7‐configuration has an 8 S7/2 ground term. A crystal field interaction will not split the orbitally non‐ degenerate S state. For the 4f7 ion, Gd3þ, it is indeed found that crystal‐field splittings of the ground J ¼ 7/2 term are of the order of about 0.2 cm1. However, the ground term for Cm3þ is only 87% 8S7/2 because spin–orbit coupling mixes in substantial amounts of the 6P7/2, 6D7/2, and higher terms that result in crystal‐field splittings of about 5–100 cm1. Early EPR studies have been reviewed by Boatner and Abraham (1978). The first authentic identification of the EPR spectra of the Cm3þ ion was by Abraham et al. (1963) in single crystals of lanthanum ethylsulfate and lanthanum trichloride. The strongest observed EPR resonance for Cm3þ in LaCl3 was assigned as the ground state with Jz ¼ 1/2. Later calculations based on optical data conflicted with this assignment (Carnall, 1992). High‐resolution laser spectroscopy measurements (Liu et al., 1993) have shown the total ground term J ¼ 7/2 splitting is

2 cm1 and that the Jz ¼ 1/2 level is not the ground state but the first excited state, in agreement with the Carnall’s assignments. Am2þ ions have approximately the same magnetic properties as Cm3þ, and it was this fact that was used for the first identification of Am2þ as a chemically stable oxidation state (Edelstein et al., 1966). A considerable amount of EPR studies have been performed on the Cm3þ and Am2þ ions at cubic symmetry sites in single crystals with the fluorite structure MX2 (M ¼ Ca, Sr, Ba; X ¼ F), SrCl2, ThO2, and CeO2. For a 5f7 ion in this symmetry, the ground state is an isotropic G6 state and the first excited state is a G8 state. If the splitting between these two states is of the order of magnitude of the magnetic splittings, these states can be mixed by the magnetic field in the EPR experiment and will result in the ground G6 state showing anisotropy as the crystal orientation is changed with respect to the magnetic field. From the magnitude of the anisotropy, the G6–G8 splitting can be deduced. Later optical measurements on Cm3þ in ThO2 confirmed the G6–G8 splitting of 15.5 (3) cm1 found for this system (Thouvenot et al., 1994). The measured ground state g‐values and splittings are shown in Table 20.12. Detailed EPR measurements have been reported for Cm3þ in YPO4 and LuPO4 (Abraham et al., 1987; Kot et al., 1993a). Interestingly, for the Cm3þ diluted into LuPO4 system, EPR measurements at 300 K were observed for the Cm3þ ion. Subsequent high‐resolution optical measurements showed the zero‐field splittings deduced from the EPR spectra were not accurately determined

Magnetic properties

2266

Table 20.12 EPR g‐values and zero‐field splittings for Cm3þ and Am2þ ions in cubic sites in fluorite‐type crystals. Under Oh symmetry, a J ¼ 7/2 state will split into a ground G6 state, a G8 state, and the highest energy G7 state. Crystal

Ion

DE (G6–G8)

gJa

g(G6)b

References

1.928 (2)

Kolbe et al. (1972)

SrCl2

3þ

Cm

5.13 (5)

SrF2 CaF2

Cm3þ Cm3þ

11.2 (4) 13.4 (5)

1.9257 (10) 1.926 (1)

g100 ¼ 4.501 (2) g111 ¼ 4.473 (2) g110 ¼ 4.482 (2) 4.493 4.492 (2)

ThO2

Cm3þ

15.5 (3)

1.9235 (20)

4.484 (2)

CeO2

Cm3þ

17.8 (3)

1.918

4.475 (2)

SrCl2

Am2þ

5.77 (5)

1.9283 (8)

SrF2 CaF2

Am2þ Am2þ

15.2 (4) 18.6 (5)

1.9254 (10) 1.926 (1)

g100 ¼ 4.504 (3) g111 ¼ 4.481 (3) g110 ¼ 4.489 (3) 4.493 4.490 (2)

ThO2

Bk4þ

>50

1.923

4.488

a b c

c

Kolbe et al. (1972) Edelstein and Easley (1968) Kolbe et al., (1972); Abraham et al. (1968) Abraham et al. (1968); Kolbe et al. (1973) Abraham et al. (1970) Kolbe et al. (1972) Edelstein and Easley (1968) Boatner et al. (1972)

Derived free‐ion g‐value. Measurements at 9.2 GHz and 4.2 K. For Cm3þ in SrCl2 DE(G8–G7) ¼ 15.3 (4) cm1.

(Murdoch et al., 1996). In the Cm3þ:LuPO4 system, the energy levels occur in pairs with two lowest levels separated by 3.49 cm1 and the two highest levels separated by 1.39 cm1. The splitting between these pairs of levels is 4.64 cm1. This splitting was not determined accurately in the EPR measurements because the data were not sensitive to small perturbations of the first‐order Zeeman splitting of each of the Kramers’ doublets that occurs between Kramers’ doublets separated by such a large energy gap. There has been one early study of the magnetic properties of AmI2, a divalent Am compound. The results are given in Table 20.13 along with values for Cm metal and some trivalent Cm compounds. As discussed earlier, Cm3þ compounds are expected to have ground term crystal‐field splittings of less than 50 cm1. Thus at temperatures where all the ground term levels are populated, meff should equal the free‐ion value of 7.64mB. Early work on the preparation of Cm compounds and the metal were performed with 244Cm, t1/2 ¼ 18.1 years. Later studies have been conducted with 248Cm, t1/2 ¼ 340000 years. Studies with 248Cm should, in principle, be more reliable as problems from radiation damage and the growth of daughter isotopes are minimized. Magnetic susceptibility measurements of Cm3þ diluted in Cs2NaLuCl6 (Table 20.2) suggested a crystal‐field splitting of 5–10 cm1. Recent optical studies on the related system, Cm3þ diluted in Cs2NaYCl6, have

5f 7 8S7/2; Am2þ, Cm3þ, Bk4þ

2267

Table 20.13 Summary of magnetic susceptibility data for 5f compounds and Cm metal. 7

Compound

T range (K) meff (BM) Y (K)

243

AmI2 Cm metal 244 Cm metal 248 Cm metal

37–180 145–550 100–300 270–307

6.7 (7) 7.99 (15) 8.07, 8.8 5.5

248

200–300 300–340 140–300 77–298 77–298

30–280 77–298 7.5–25 25–45 20–80 100–300 50–300 4.2–300

50–300 50–300 120–320 30–90

6.2 7.7 6.0 7.7 7.7 7.67 7.6 7.90 (10) 7.48 (50) 8.20 7.89 7.74 7.51 8.9 (3) 7.89 (5) 8.7 (2) 7.8 (2)

244

Cm metal Cm metal 244 Cm metal 244 CmF3 · 1/2H2O 244 CmF3 in LaF3 248 CmF3 244 CmOCl 244 Cm3þ:Cs2NaLuCl6 244 Cm3þ:Cs2NaLuCl6 248 Cm2O3 248 Cm2O3 248 Cm2O3 248 Cm2O3 248 CmBa2Cu3O7 248 CmCuO4 Pb2Sr2248CmCu3O8 Pb2Sr2248CmCu3O8 248

To (K)

References and comments a b

–386, –560 52 (1) 176 TN ¼ 65 K, To ¼ 200 K 202 138 72.2 –5 –6 3.6 –22 –4 –1 –149 –130 –130 TN 15 K –110 TN ¼ 22 TN ¼ 25 –96.8 TN ¼ 18

c d e e f g g h g i i j j h h k l m m

Baybarz et al. (1972). Marei and Cunningham (1972). The Cm metal sample measurement was repeated four times with widely varying Y values. c Kanellakopulos et al. (1975) and Fournier et al. (1977). The first value of Y is associated with the first value of meff, etc. d Huray et al. (1980) dhcp phase. e Huray et al. (1980). fcc phase, another more complex analysis is also given. f Fujita et al. (1976). g Marei and Cunningham (1972). h Nave et al. (1983). i Hendricks et al. (1974). j Morss et al. (1983). k Soderholm et al. (1989) and Soderholm (1992). Includes a contribution from the Cu2þ ions to meff. l Soderholm et al. (1999). No value of Y is given, low‐temperature neutron diffraction indicates the spins order ferromagnetically within the a–b plane and are antiferromagnetically ordered along the c‐axis. m Skanthakumar et al. (2001). The large value of meff above 100 K is attributed to a local paramagnetic moment on Cu2þ plus that of the Cm3þ ion. It is suggested that Cu2þ moment ordering occurs below 100 K resulting in the expected Cm3þ free‐ion moment. a

b

reported a 4.8 cm1 splitting between the ground state and the first excited state. Because the ionic radius of the Lu3þ ion is less than that of the Y3þ ion, the crystal‐field splitting in the Lu system should be larger, in accord with the susceptibility measurement. Above 7.5 K, there is reasonably good agreement

2268

Magnetic properties

with the calculated free‐ion moment. The temperature‐dependent magnetic susceptibility of BkO2 diluted in ThO2 showed the ground state to be a G6 (Oh) and the excited G8 (Oh) state to be at about 80 cm1 (Karraker, 1975b). The g‐value of the ground state was 5.04, about 10% higher than the more accurate value of 4.488  0.004 measured by EPR (Boatner et al., 1972). The total overall splitting of the ground J ¼ 7/2 state was estimated to be about 300 cm1. A possible antiferromagnetic transition at 3 K has been suggested to account for the anomalous magnetic behavior of these samples below 10 K. This transition would require segregation of the BkO2 in the host ThO2 matrix. Nave et al. (1983) measured the magnetic susceptibility of a 56.6 mg sample of BkO2 (containing a 3% Cf impurity at the time of the measurement) and find Curie– Weiss behavior from 4.2 to 300 K with meff ¼ 7.92mB and y ¼ –250 K. Their value agrees with the calculated value for an 8S7/2 state. However, it does conflict with the EPR results and Karraker’s results which indicate a considerable splitting of the ground J ¼ 7/2 term. Interactions involving Cm3þ may be judged from a very complete work on Cm2CuO4 by Soderholm et al. (1999), where meff ¼ 7.89 (5)mB, TN ¼ 25 K, and the ordered moment is 4.8 (2)mB at 15 K. This is a lower moment than expected, which might be due to measurements being made at an elevated temperature compared to TN, but also may be caused also by covalency effects. The sample used for the neutron experiments was 42 mg (248Cm), and the magnetic structure is the same as found for Gd2CuO4, which orders at 6.4 K. As far as known this is the only observation of magnetism in a Cm compound with neutrons. Cm2CuO4 is isostructural with the famous high‐Tc‐related La2CuO4 and it would be interesting to know what is the value of the moment on the Cu atom in the Cm compound. Unfortunately, this was below their experimental cut‐off. Another similar study (but without neutrons) was done by Skanthakumar et al. (2001) on the compound Pb2Sr2Cm1–xCaxCu3O8 with x ¼ 0 and 0.5. Again, these materials are related to high‐Tc analogs with rare earths, although none of the Cm‐doped compounds becomes superconducting. A number of magnetic susceptibility measurements have been reported for Cm metal (Table 20.13), but reports by various investigators disagree (Marei and Cunningham, 1972; Kanellakopulos et al., 1975; Fournier et al., 1977; Huray et al., 1980). The Soderholm group has been using the Cm3þ ion as a probe to study the influence of magnetic electrons on the superconductivity of some high‐Tc‐related oxides (Soderholm, 1992). In the course of this work, some new Cm compounds have been synthesized and their susceptibilities determined as shown in Table 20.13. 20.10 5f8 7F6; Bk3þ, Cf4þ

The magnetic data for 249Bk3þ diluted in Cs2NaLuCl6 are given in Table 20.2 (Hendricks et al., 1974). The magnetic susceptibility is temperature independent, which shows that a singlet state is the ground state. From the systematics

5f 9 6H15/2; Cf 3þ

2269

of the crystal field parameters for the host crystal, the ground state is assigned as a G1 (Oh) state, and from the magnitude of the susceptibility, the first excited state is calculated to be a triplet G4 (Oh) state at about 85 cm1. Magnetic measurements for other 249Bk compounds and the metal are listed in Table 20.14. The theoretical value for the 5f8 ground term free‐ion g‐value in intermediate coupling is 1.446 (1.50 for the pure 7F6 ground term). From the magnetic susceptibility of Bk3þ adsorbed on ion‐exchange beads, Fujita (1969) measured from 9.3 to 298 K (Table 20.14) a meff ¼ 9.40(6)mB, which corresponds to a free ion g ¼ 1.452 (8) in excellent agreement with the expected value. The magnetic susceptibility of 249BkF3 has also been reported and is in agreement with the free‐ion value. The results of measurements of the magnetic susceptibility of Bk metal (Fujita, 1969; Nave et al., 1980) are also given in Table 20.14. These measurements were performed on very small amounts (mg) of 249Bk metal. Since t1/2 of 249Bk is only 320 days, there were varying amounts of 249Cf metal (although corrections were applied for the amount of Cf) in the samples. Thus it is not surprising that different 249Bk samples showed different magnetic behavior, especially at lower temperatures. Clearly these very difficult measurements need to be repeated. Measurements have been reported for 249CfO2 and for 249Cf7O12. The latter compound can be thought of as comprising 40% Cf3þ and 60% Cf 4þ and, assuming that susceptibilities can be simply added, the free‐ ion moment should be 9.7mB. As can be seen from Table 20.14, the measured higher temperature values are slightly lower than the expected free‐ion values.

20.11

5f 9 6H15/2; Cf 3þ

The EPR spectrum of 249Cf3þ in Cs2NaLuCl6 powder has been observed at 4.2 K (Edelstein and Karraker, 1975). From the measured isotropic g‐value of 6.273 (10), the ground crystal field was identified as the G6 (Oh) state and a free‐ion g‐value of 1.255 was deduced as compared with a calculated intermediate‐ coupling g‐value of 1.279 for the nominally 6H15/2 term. For the 4f 9 analog, Dy3þ, the free‐ion g‐value is 1.333. The magnetic susceptibility of 249Cf3þ ( 2.4 mg) diluted into octahedral Cs2NaYCl6 (Table 20.2) was reported in the temperature range from 2.2 to 100 K (Karraker and Dunlap, 1976). From an analysis of the data, the G6 state was determined to be the ground state, in agreement with EPR measurements, with a G18 level as the first excited level at about 50 cm1. The total crystal‐field splitting was calculated to be about 860 cm1. Limits were set for the ratio of B40 B60 , which were consistent with those previously determined  for the trivalent actinide compounds Cs2 NaMCl6 M ¼ U3þ ; . . . ; Bk3þ : EPR measurements of |gk| ¼ 3.56(2) and |g⊥| ¼ 7.79(3) were reported for Cf3þ diluted in LuPO4 at 4.2 K by Kot et al. (1993b). Table 20.14 also lists magnetic susceptibility data for 249Cf3þ compounds and for 249Cf metal. From the magnetic susceptibility of Cf3þ adsorbed on ion‐exchange beads (Fujita, 1969) measured from 77 to 297 K (Table 20.14),

Table 20.14 Magnetic data for 5f 8 and 5f 9 metals, ions, and compounds. References and notes

Compound

T range (K)

y (K)

meff (mB)

TN (K)

249

170–350 50–298 100–298 70–300 70–300

10–300 4.2–300

80–320

80–320 150–340 150–340 28–298 22–298 100–340 77–298

80–320

80–320

80–320 90–300 150–340 100–340 60–340 2.2–14 20–100

64.4 –72.7 –33.0 –101.6 –84.4 –11.0 (1.9) –77.9 –70 (10) 95 (15) –51 (3) –33 (3) 3.24 –3.00 40 (3) –5.6 (3.2) –210 (20) –80 (15) –115 (15) –80 (10) –20 (3) 37 (10) 13 (5) –2.8 (1) –13.5 (4)

8.23 8.52 8.83 9.69 8.82 9.40 (6) 9.38 9.1 (2) 9.5 (2) 9.4 (1) 9.1 (1) 9.84 9.67 9.7 (2) 9.14 (6) 9.2 (2) 10.1 (2) 9.8 (2) 9.7 (2) 10.2 (1) 10.3 (2) 10.1 (2) 7.36 (20) 10.0 (1)

To ¼ 140 (15) 35 (3)

a

34

34

d

Bk metal Bk metal 249 Bk metal 249 Bk metal 249 Bk metal 249 Bk3þ 249 BkF3 249 CfO2 249 Cf7O12 249 CfF4 249 CfF4 249 Cf metal 249 Cf metal 249 Cf metal 249 Cf3þ Ba249CfO3 249 Cf2O3 249 Cf2O3 249 Cf2O3 249 CfF3 249 CfCl3 249 CfCl3 Cs2Na249CfCl6 Cs2Na249CfCl6 249

b c e f g

7 (2) 8 (2)

h

9–12

k

i j l l

To ¼ 51 (2)

m

7 (2) 8 (2) 19 (2)

o

6–7 13 7

s

n p q r t u v v

Fujita (1969) predominantly fcc, mass 1.669 mg, 20% 249Cf, possible ferromagnetic impurities. Fujita (1969) predominantly dhcp, mass 5.629 mg, 16% 249Cf. c Fujita (1969) approximately equal amounts of the dhcp and fcc phases, mass 1.725 mg, 1.7% 249Cf. d Nave et al. (1980) dhcp, 12% 249Cf, 21.0 (3) mg. e Nave et al. (1980) mainly dhcp, some fcc, 16% 249Cf, 19.0 (3) mg, indication of a second transition (small amplitude) at 42 K. f Bk3þ absorbed on ion‐exchange beads, two samples of 0.546 and 1.012 mg, less than 0.8 and 0.4 at % 249Cf respectively in the two samples. Average value is given. g Nave et al. (1981) 143 mg sample. h Moore et al. (1986) fcc, two samples of 6 and 53 mg. i Moore et al. (1986) rhombohedral, three samples of 25, 42, and 100 mg. j Chang et al. (1990) monoclinic, results for two of three freshly prepared samples of mass ranging from 30 to 90 mg. k Chang et al. (1990) monoclinic, results for two aged and one of three freshly prepared samples of mass ranging from 30 to 90 mg. The aged samples showed antiferromagnetic behavior. l Fujita et al. (1976) fcc, two samples of 8.85 (top) and 5.64 mg (next). m Nave et al. (1985) dhcp, two samples of 73.0 and 98.0 mg, average value is given. n Fujita (1969) Cf3þ absorbed on ion‐exchange beads, three samples of 0.342, 0.806, and 1.190 mg, average value is given. o Moore et al. (1986) perovskite type, 24 mg sample. p Moore et al. (1986) monoclinic, two samples of 11 and 22 mg. q Moore et al. (1986) bcc, 31 mg sample. r Morss et al. (1987) bcc, two samples of 3.097 and 1.23 mg, the numbers given in the table are the recommended average of measurements on the two samples, no indication of magnetic ordering was observed down to 2 K. s Chang et al. (1990) one hexagonal and three orthorhombic samples, masses ranging from 30 to 90 mg, high temperature results did not depend on the age of the samples. a

b

5f 10; 5I8; Es3þ

2271

a meff ¼ 9.14(6)mB was obtained. This value is significantly lower than the expected free‐ion value of 10.21mB for the 6H15/2 ground term. The magnetic susceptibilities of a number of compounds of Cf3þ have been measured. For the most part, the high‐temperature data that could be fit by the Curie–Weiss law gave effective moments that were close to the free‐ion value. However, as found before for small samples of highly radioactive isotopes, the low‐temperature data were quite complex and sample dependent. Magnetic susceptibility measurements of 249Cf metal samples were reported by two groups and are listed in Table 20.14. The high‐temperature results are in fair agreement although one group reported complex low‐temperature data for the metal. 20.12 5f 10; 5I8; Es3þ

Very few measurements have been reported for trivalent Es compounds because of the difficulties associated with measurements on materials with short‐lived isotopes. The most abundant isotope of Es is 253Es with t1/2 ¼ 20.4 days. A magnetic susceptibility measurement was reported for Es2O3 in the temperature range 4.2–180 K on an amorphous sample. The data fit the Curie–Weiss law with meff ¼ –10.5mB and Y ¼ –53 K. Correcting for the growth of 249Bk (the sample was 4 days old and contained 13% Bk) gave a value of 10.5mB, consistent with the free‐ion value. Measurements were reported for a 3.25 mg sample of EsF3 in the temperature range 4.2–200 K 10 days after separation and preparation, which meant there was 31% 249Bk in the sample. The data were fit with the Curie–Weiss law with meff ¼ –10.9mB and Y ¼ –37 K. After correction for the Bk content, the effective moment was 11.4mB. These measurements on Es samples should be treated conservatively as the true sample temperatures, the container corrections, and 249Bk corrections lead to large uncertainties (Huray and Nave, 1987). Elements beyond Es have half‐lives that are too short to permit magnetic measurements of metals or compounds by conventional methods discussed here. 20.13 5f11; 4I15/2; Es2þ

The only reported Es metal (a divalent metal) magnetic measurement was made on a 0.25 mg sample. The purity of this sample is questionable since the preparative method may have resulted in an Au–Es alloy. Data were taken for

t Nave et al. (1987) and Moore et al. (1988) orthorhombic form obtained after melting the hexagonal samples, two polycrystalline samples of mass of 12.3 and 19.3 mg, exhibits metamagnetic behavior at low temperatures. u Nave et al. (1987) and Moore et al. (1988) hexagonal, two microcrystalline samples of mass of 12.3 and 19.3 mg, exhibits metamagnetic behavior at low temperatures. v Karraker and Dunlap (1976) 2.37 mg of 249Cf3þ diluted in 0.2 g of polycrystalline Cs2NaYCl6.

Magnetic properties

2272

this sample with apparent temperature readings from 4.2 to 90 K. In this interval, a local moment of 11.3mB was obtained, higher than the 10.2mB free‐ ion value. The authors note the small sample size, large corrections for the sample holder, and uncertainty in the sample temperature due to self‐heating as well as corrections for 249Bk growth lead to a large uncertainty in the measured value (Huray and Nave, 1987). The EPR spectrum at 4.2 K of 253Es2þ diluted in CaF2 was reported by Edelstein and coworkers (Edelstein et al., 1970; Edelstein, 1971) and used to identify the stabilization of this oxidation state by the CaF2 host. The measured g‐value of 5.809  0.005 identified the ground state as a G6 (Oh) state. Subsequently, Boatner et al. (1976) found that the ground state of 253Es2þ diluted in SrCl2 had a g‐value of 6.658  0.003, which was assigned to the G7 (Oh) state. Boatner et al. (1976) also reported the EPR spectrum of 253Es2þ diluted in BaF2, which was similar to that of Es2þ in CaF2. Thus, the ratio of the crystal field parameters changed on going from CaF2 or BaF2 to SrCl2, causing the ground state to switch. Analogous behavior had been found for the 4f11 ion, Ho2þ, in the same host crystals. The magnitude of the measured g‐values is smaller than expected, and has been attributed primarily to covalency effects (Edelstein, 1971; Boatner et al., 1976).

20.14

THE ACTINIDE DIOXIDES

Starting with the actinide oxides, AnO2, one would intuitively expect that the situation might be relatively simple. If one takes oxygen as divalent, then an ionic compound can be made with An4þ and 2O2. Indeed, from many considerations this appears a good approximation. All compounds have the well‐ known fcc CaF2 fluorite structure. (See Chapter 15, Table 15.9, for a list of lattice constants.) This apparently simple cubic structure belies the complications that occur for the different oxides. As in so many cases, the devil is in the details. Despite half a century of effort, there remain many puzzles in the actinide dioxides, and they will be discussed at some length in this article. The magnetic properties should reflect this ionic nature, i.e. for UO2 a 5f2 configuration is anticipated with a crystal‐field splitting that gives a well‐defined ground state. 20.14.1

Uranium dioxide

Early work on the magnetic susceptibilities of solid solutions of UO2 in ThO2 (cubic symmetry) was interpreted as showing ‘spin only’ behavior for the d2 configuration on extrapolation to infinite dilution. Subsequently Hutchison and Candela (1957) showed that a model based on the 5f2 configuration with a strong spin–orbit interaction and the ratio of the crystal field parameters such that the G5 (Oh) triplet state is lowest would also fit the observed magnetism. Ordered magnetism of UO2 was first suggested by Jones et al. (1952) from their

The actinide dioxides

2273

Fig. 20.7 Heat capacities of ThO2, UO2, and NpO2. Figure reprinted with permission from Osborne and Westrum (1953). Copyright 1953 by the American Institute of Physics.

heat capacity measurements. Within a year, the heat capacities of ThO2, UO2, and NpO2 were measured (Osborne and Westrum, 1953) and are reproduced in Fig. 20.7. These showed important anomalies for UO2 and NpO2, at 30 and 25 K, respectively. The assumption, of course, was that both materials exhibited a phase transition to a magnetically ordered state. Although magnetic susceptibility measurements were made on UO2 in 1950, the best data were presented by Arrott and Goldman (1957). They showed that the magnetic phase transition disappeared when additional oxygen entered the lattice to the level of UO2.07. Almost a decade then passed before the microscopic proof of antiferromagnetism was given by neutron diffraction. Two papers were published essentially simultaneously, Willis and Taylor (1965) and Frazer et al. (1965). Both reported work on single crystals and showed that UO2 has a first‐order transition to an antiferromagnetic state at 30.8 K. The uranium moments (of 1.75mB at 5 K) are aligned in alternating ferromagnetic (100) sheets in a sequence þ – þ –. The magnetic repeat may be characterized by a wave vector of k ¼ 1, i.e. the magnetic and chemical unit cells are the same. The magnetic moments are perpendicular to the propagation direction, i.e. m ⊥ k, in what may be described as a transverse structure (Fig. 20.8). These experiments, the availability of single crystals, and the increasing interest in f‐electron magnetism ushered in the ‘golden era’ of experiments on UO2, essentially the period from 1965 to 1980. Blume (1966), assuming a model where the electronic structure of U4þ consisted of a nonmagnetic singlet ground state with a low‐lying magnetic triplet state and including bilinear isotropic exchange interactions, was able to account semiquantitatively for the first‐order magnetic phase transition (see also

2274

Magnetic properties

Fig. 20.8 Magnetic structure of UO2. The open circles are oxygen and the closed circles are uranium. In the arrangement shown the propagation direction k ¼ [001], (k and t are equivalent) and the moments are transverse to this direction. There are two domains, one with m k [100], and the other with m k [010]. Figure reprinted with permission from Faber and Lander (1976). Copyright 1976 by the American Physical Society.

Alessandrini et al., 1976). Rahman and Runciman (1966) showed that this was unlikely, their full manifold calculation showed that the crystal field ground state was most probably the triplet G5. This could also explain the moment (which should be 2.0mB for a pure 3H4 ground state) as the mixing of higher L and S components would tend to reduce the ordered moment. They obtained crystal field parameters V4 ¼ 409 meV and V6/V4 0.06. They could not easily explain the first‐order phase transition, but did predict a splitting of

171 meV between the ground state and the doublet G4 and 630 meV to the next excited crystal field state. Neutron inelastic scattering was incapable of verifying these energy splittings in the 1960s and the opaque character of UO2 make the optical technique of limited value. However, on a lower energy scale, neutrons had already been used to measure the complete phonon dispersion spectra at room temperature (Dolling et al., 1965). At lower temperature, the neutron inelastic experiments by Cowley and Dolling (1968) showed a possible strong interaction between the magnons and the lattice, and this was reinforced by the elastic constant measurements as measured by Brandt and Walker (1967, 1968). Interestingly, they showed that the c44 elastic mode actually started to soften just below room temperature, and showed a strong minimum at the phase

The actinide dioxides

2275

transition. Within a year, in two remarkable papers, Allen (1968a,b) proposed a theory for the spin–lattice interaction in UO2 that was based on a Jahn–Teller (JT) interaction and first introduced the idea of quadrupole interactions in the actinides. Allen proposed that the quadrupoles ordered and would thus give rise to an internal strain that would lead to a change in the position of the oxygen atoms without giving rise to an external change in the symmetry of UO2. No measurements had found evidence for a large external (i.e. a lowering of the overall cubic symmetry) crystallographic distortion at the phase transition. Pirie and Smith (1970), using X‐rays, searched for possible shifts of the U‐atoms, but in such a measurement any oxygen shift would have been impossible to observe. Following the work of Allen, an important paper was published by Sasaki and Obata (1970) giving new insights into the Jahn–Teller effects that might occur in the oxides. Their essential contribution was to realize that there could also be a dynamic JT effect that could occur at temperatures above the phase transition, and by coupling to the lattice this would explain the anomalies found in both the elastic constant work of Brandt and Walker (1967, 1968), and the susceptibility measurements of Arrott and Goldman (1957). There is no evidence that the neutron experts understood the theory of Allen, which was advanced for its time, or Sasaki and Obata’s work. It was not until 1975 that the internal distortion of the oxygen cage was discovered with neutron diffraction in the course of precise measurement of the intensities from a single crystal (Faber et al., 1975; Faber and Lander, 1976). The experiment was designed to study something completely different, the magnetic form factor of U4þ at high values of Q, and the observation of the oxygen internal distortion was accidental! The full theory of this distortion was published by Siemann and Cooper (1979). The exact internal modes proposed by Allen are incorrect, but other modes are found. This does not distract from the originality of Allen’s ideas. The coupling of magnetism and internal modes is illustrated in Fig. 20.9. ˚ . That such a The oxygen displacement from the equilibrium position is 0.014 A small movement of the oxygen atoms could be measured is an example of how the neutrons are sensitive to light atoms in the presence of heavy ones. The next step in the UO2 saga came with the experiments on many actinide compounds at the Commissariat a` l’Energie Atomique (CEA) in Grenoble, France during the period 1977–87 under the leadership of J. Rossat‐Mignod. This group determined that many of the NaCl‐type actinide compounds had a more complicated form of magnetic structure than originally proposed (Rossat‐ Mignod et al., 1984). Instead of having a single k propagation vector in a certain volume of the crystal, a number of symmetry equivalent k vectors coexist in the same volume of the crystal. UO2 was determined to have a triple k magnetic structure both by cooling the material in a magnetic field, as well as by applying uniaxial stress to the sample. This does not change the understanding of the magnetic structure or internal distortion, as long as one realizes that only one component of the moment and distortion are shown in Figs. 20.8 and 20.9. It did, however, lead to a reinterpretation of the magnon dispersion curves of

2276

Magnetic properties

Fig. 20.9 The (001) projection of the fluorite structure. The large circles represent oxygen atoms at z ¼ 1/4 and 3/4 displaced from the ideal fluorite structure (indicated by the dashed ˚ . The smaller closed lines). The shift of the oxygen atoms is not drawn to scale, D ¼ 0.014 A and open circles represent the uranium atoms at z ¼ 0 and 1/2, respectively. The arrows indicate the directions of moments for the four sublattice antiferromagnetic structure. Figure reprinted with permission from Faber and Lander (1976). Copyright 1976 by the American Physical Society.

Cowley and Dolling (1968) and Giannozzi and Erdos (1987). However, efforts to reproduce the dispersion of the magnons (discussed later), despite the 3k‐ structures were not successful. Apparently some element was still missing in the understanding of these curves. During this period many other experiments were, of course, conducted on UO2. It is a semiconductor with a band gap of 2 eV, and much of the electronic structure aspects were reviewed by Schoenes (1980) and by Brooks et al. (1984). There is little doubt from photoemission that the 5f states are considerably removed from the Fermi level EF in UO2. They are measured at 1.4 eV below EF, a strong indication of the localization of the 5f2 state. Kelly and Brooks (1987) have shown that the local density approximation can account for the lattice parameter and estimate the width of the valence band. However, these electronic structure calculations show also that the simple concept of an ionic solid is not a good approximation in any of the light actinide oxides. There is appreciable mixing of the actinide 6p states with the 2p states of oxygen resulting in a measure of covalency for all actinide oxides. In examining the optical properties (Schoenes, 1980) the localized nature of the 5f electrons in UO2 also became apparent, and many features of the

The actinide dioxides

2277

electronic structure were observed as interband transitions. One extraordinary effect, shown in Fig. 20.10a was the presence below TN of intense and sharp peaks at 151 and 154 meV. Schoenes identified these as two‐phonon excitations as they are at exactly double the highest energy longitudinal optic (LO) modes involving principally oxygen atoms as measured by Dolling et al. (1965). The question is why they should be so strong and temperature dependent

Fig. 20.10 (a) The absorption coefficient of UO2 measured in optical spectroscopy for various temperatures above and below TN ¼ 30.8 K. The sharp peaks at 151 and 154 meV are thought to be multiphonon excitations. (b) The temperature dependence of the area of the 154 meV peak compared to the normalized sublattice magnetization as measured by neutrons. Reprinted from Schoenes (1980), Copyright 1980 with permission from Elsevier.

2278

Magnetic properties

(see Fig. 20.10b)? As found from the experiments that will be described for NpO2 (see below), it now appears that these excitations are a consequence of the LO phonon coupling to the quadrupolar distortion induced by the 5f quadrupole moment around the uranium nucleus. The fact that the T‐dependence is continuous rather than discontinuous, as seen in the sublattice magnetization, suggests that the quadrupole coupling is a higher‐order effect, and the dipole ordering is the primary‐order parameter. It would seem worthwhile to measure this LO phonon as a function of temperature with neutron inelastic scattering. Rahman and Runciman (1966) utilized the crystal field model to predict that there was a large splitting of the 3H4 ground state manifold, with the first excited state being at least 150 meV above the ground state. With the advent of spallation neutron sources in the early 1980s, these types of crystal field energies became accessible, and the first indication for crystal field excitations in UO2 was published in 1985 (Kern et al., 1985). Two excitations were observed at 155 and 172 meV, whereas only one was expected according to the Rahman and Runciman calculation. These authors suggested that the R&R calculations might still be correct but that the V6/V4 ratio might be rather different from the –0.06 suggested by Rahman and Runciman. Three years later, using the more powerful spallation source ISIS near Oxford in UK, Osborn et al. (1988) showed that the crystal field spectra of UO2 consisted of four excitations spread over the range 152–183 meV; these are shown for various temperatures in Fig. 20.11. They also searched up to energy transfers of 800 meV, but found no evidence of further transitions. The first point to note is that in the crystal field model for the 3H4 multiplet there should be only two transitions in the ground state multiplet. (Transitions from G5 to G3 and G4 are allowed, but not to G1.) Since the overall multiplet is now within 180 meV, rather than the 700 meV proposed by Rahman and Runciman, the crystal field interaction is much weaker than in the Rahman and Runciman model. In a detailed paper, Amoretti et al. (1989) showed that V4 –123 meV, less than 1/3 that was proposed by Rahman and Runciman, and V6/V4 ¼ –0.21. The extra lines (above the two expected) arise from the lowering of the symmetry due to the internal distortion of the oxygen cage (Fig. 20.9). Amoretti et al. (1989) were able to show that the spectra are better explained with a 3k magnetic structure (physical displacements along h111i) rather than a 2k model (physical displacements along h110i). Interestingly, one can see that the four lines are still present above TN, whereas there is no longer a static distortion of the oxygen cage. However, dynamic effects are still present, as pointed out by Sasaki and Obata (1970), and these will give rise to a splitting of the crystal field levels, although it is noticeable that the transitions are starting to broaden in width by 35 K. Following this direct measurement of the crystal‐field splitting, the theorists returned to the fray and showed that the smaller value of V4 (as compared to the original calculations of Rahman and Runciman) could be understood (Gajek et al., 1988; Rahman, 1998). The latter paper shows that the ground state is

90% 3H4, justifying the approximations made in interpreting the neutron

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Fig. 20.11 Neutron spectra measured with an incident energy of 290 meV for different temperatures between 6.5 and 35 K, where TN ¼ 30.8 K. The smooth line is the fit to four Gaussian line shapes and a sloping background. These five components are shown by the dashed lines. Figure reprinted with permission from Amoretti et al. (1989). Copyright 1989 by the American Physical Society.

spectra. The moment calculated is 1.94mB, only a small reduction from the 2.00mB in the simple Russell–Saunders coupling for the G5 ground state. The reduction from 1.94 to 1.75mB is thus due to the JT effect, as discussed above. All of this established beyond doubt that the ground state was the triplet G5. For the ground states of the heavier actinides, more mixing of excited states into the ground state is expected, but this work on UO2 shows that although taking into account intermediate coupling (mixing of excited L and S values) is necessary, J‐mixing is probably not so important for any ground state properties of the actinides. This result suggests many of the earlier calculations, e.g. Chan and Lam (1974) were not relevant. Furthermore, this has important implications for studies of intermetallics compounds, which are not covered in this review (but see Chapter 21 and Vol. 17, 19, and 32 of Handbook of Physics and Chemistry of the Rare‐Earths). Because the conduction‐electron states in intermetallic compounds are known to shield the crystal field interactions, the crystal field parameters are expected to be lower than in the actinide oxides. Thus it is expected that crystal‐field splittings in intermetallics should be in the range 20–50 meV, as compared to 150 meV in UO2. The range for intermetallics is thus excellently matched to neutron spectroscopy, and in practice this has been found (Holland‐Moritz and Lander, 1994). However, when the crystal field transitions in intermetallics are not observed with neutron spectroscopy, it

2280

Magnetic properties

cannot be argued that the crystal field transitions are outside the range of neutron spectroscopy. More subtle interactions, due to the hybridization of the 5f electrons with the conduction‐electron states, are involved. An elegant NMR study has been performed at low temperature on both the 235 U and 17O NMR nuclei in UO2 (Ikushima et al., 2001). The results lend support to the idea of a 3k magnetic structure in UO2 below TN. Furthermore, Ikushima et al. (2001) give strong evidence for a local distortion driven by the U quadrupoles, and an excitation spectrum that shows the presence of magnon–phonon coupling. The understanding of UO2 is almost complete, but there are still the magnon dispersion curves, first measured in 1968, that still defy a complete theoretical interpretation, despite the realization of the 3k state. Again, new neutron technology has come into play, in this case in the ability to have enough neutron intensity to analyze the polarization of the scattered neutrons. Briefly, when a neutron is scattered from a magnetic moment the spin state of the neutron is changed; on the other hand, when the neutron is scattered from a nucleus, the spin state is unchanged. With a sufficiently large single crystal of UO2, it proved possible to examine the magnon dispersion curves with polarization analysis, and the results are shown in Fig. 20.12 (Caciuffo et al., 1999). The hope in these

Fig. 20.12 Magnon dispersion curves of UO2 measured at 16.5 K along the principal crystallographic directions. The broken lines and crosses correspond to acoustic phonon branches measured at 270 K. Open symbols indicate a qualitatively smaller magnon intensity than the filled points. In all measurements the neutron spin state was spin flip, i.e. changed, and the nonspin‐flip cross section was found negligible. Figure reprinted with permission from Caciuffo et al. (1999). Copyright 1999 by the American Physical Society.

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experiments was that a ‘mixed’ mode would be found to identify the famous magnon–phonon coupling first proposed by Cowley and Dolling (1968). No sign of this  interaction was found. However, if it occurs in the region x 0.5 in the 00
2x zone, then it is difficult to observe as the intensity drops to almost zero, for reasons that are not immediately clear. Theory is still unable to reproduce the magnon dispersion curves. This is certainly the most important question to resolve before a complete understanding of the magnetism of UO2 is achieved. In this long story of the magnetism of UO2 not a word has been said about the new technique of RXS. In a sense this technique came too late! One discovery still needing confirmation in UO2 is the presence of the quadrupole moments. Rather than treat this here, it is more appropriate to raise it after the discussion of NpO2 (below). However, one interesting story using synchrotrons is worth recounting. The signal from uranium in resonant magnetic scattering is so strong (see Fig. 20.2 and discussion) that it opens the possibility for doing different kinds of experiments. One of these is the possibility of observing the scattering from surface magnetism in UO2. Experiments of this sort to study the surface charge arrangements are common with synchrotrons, but are extremely rare for magnetism because they require scattering from a very small magnetic volume near the surface of the material. After many efforts involving surface preparation and different experiments, surface magnetic scattering was observed from UO2 (Watson et al., 1996). Strictly speaking, the parameters investigated have little specific to UO2; they concern what happens near the surface of an antiferromagnet that undergoes a discontinuous phase transition in which the magnetism melts. One of the more interesting aspects is that as emphasis is put more and more on the surface layers it is found that the phase transition is in fact continuous. The crucial data are shown in Fig. 20.13. Although it is not strictly correct to interpret the different values of the L index in Fig. 20.13 as representing different depths into the antiferromagnet, as a first approximation it is acceptable. The bulk magnetism signal (similar to that observed with neutrons) is shown at (001). The model of magnetism near the surface in UO2 is that near the phase transition, the top few surface layers lose their magnetism, and below them is an interfacial layer of reduced moments that grows in spatial extent as the temperature approaches TN. These results are in agreement with some of the theories, based on symmetry arguments, but in disagreement with a simple melting transition, which is observed for ferromagnets. That there is a difference is perhaps not surprising as a ferromagnet has a net magnetization, which couples to the lattice, whereas such an interaction is absent in an antiferromagnet. More recent experiments have gone on to study the roughening of the magnetic order just before the phase transition. Interestingly, such studies are relevant to a current problem in magnetic multilayers, viz. the interplay of charge and magnetic roughness in defining the interfacial structure of the multilayers.

2282

Magnetic properties

Fig. 20.13 Temperature dependence of the magnetic scattering at the (001) bulk Bragg reflection (solid circles, which agrees with neutrons) and at various positions along the (01L) magnetic truncation rod (open symbols). Essentially one can think of these data having a greater component of the surface as L increases. Data are normalized to unity at low temperature. Inset: log–log plot of the scattering intensity at two different positions along the (01L) rod as a function of reduced temperature. Figure reprinted with permission from Watson et al. (2000). Copyright 2000 by the American Physical Society.

20.14.2

Neptunium dioxide

Progress in understanding was slow and steady over the last 50 years in the study of UO2. Not so with NpO2. The problem turned out to be considerably more complicated. The story starts with the same paper on the heat capacity from Osborne and Westrum (1953) (Fig. 20.7). Since NpO2 has a 5f3:Np4þ configuration, the ground state is 4I9/2, a Kramers’ ion in which the lowest ground state must be a magnetic doublet. This means given even the smallest amount of magnetic exchange the compound should order magnetically as no crystal field interaction can induce a singlet (nonmagnetic) state. The transition at To ¼ 25 K in the heat capacity was thus assumed to be due to magnetic ordering. Note that the entropy at the transition (area under the curve) is very similar for both UO2 and NpO2, reinforcing the supposition of

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ordered magnetism in both. Magnetic susceptibility measurements by Ross and Lam (1967) showed a strong peak at To, again suggesting antiferromagnetic order, as in UO2. The first surprise came when neutron diffraction (on polycrystalline samples) by Cox and Frazer (1967) and Heaton et al. (1967) failed to find any change in the diffraction pattern on cooling below 25 K. They put an upper limit of 0.4mB on any possible moment, much less than expected from the 5f3 ground state quartet. This limit was drastically reduced by the Mo¨ssbauer experiments of Dunlap et al. (1968) that showed that there was a very small amount of line broadening developing below To. When interpreted in terms of magnetic dipole ordering, this line broadening suggested a moment of

0.01mB. At that time, in the 1960s, a moment so small was unheard of, so the problem remained unsolved. The discovery of the internal distortions in UO2 in the mid‐1970s led those involved, especially theorists, to return to the unsolved mystery of NpO2. Erdos and coworkers published a number of papers trying to explain the low‐temperature magnetic properties of NpO2 (Erdos et al., 1980; Solt and Erdos, 1980). The essential point was to introduce a quadrupole interaction and allow this to cause an internal distortion. The magnetism was then ‘removed’ by postulating an unusual ground state or other assumptions about the presence of Np3þ ions. Since the UO2 studies had shown that small extra diffraction peaks were present at low temperature as a consequence of the rearrangement of the oxygen atoms, an effort was made to see whether similar peaks could be found from NpO2. Boeuf et al. (1983) reported a null effect, but the crystals of NpO2 were small (no crystals larger than 2 mm3 have ever been produced), so these experiments could not be as sensitive as in the case of UO2. Given the sensitivity of the Mo¨ssbauer signal from the 237Np ion, it was not surprising that Friedt et al. (1985) returned to this technique and made a series of precise measurements down to 1.5 K, including applying a magnetic field. They suggested that there was no dipole magnetism at all, and that all the effects could be explained by a JT distortion of the oxygen cage. However, since this had not been observed in the experiments of Boeuf et al. (1983), they suggested that the distortion should be dynamic in nature. If it were, then this should give rise to a change in the phonon spectra, which might be reflected in the thermal parameters at low temperatures. Caciuffo et al. (1987) searched for any such changes, but without success. By this time experimentalists were unenthusiastic about working on NpO2, but it seemed at least important to establish the crystal field parameters, as there had been the suggestion that NpO2 was not even Np4þ (Zolnierek et al., 1981). The first attempts by Kern et al. (1988) showed that any crystal field peaks were broad, much broader than the experimental resolution. The problem needed the higher intensity of the ISIS (UK) source and this experiment was performed by Amoretti et al. (1992). The data and fits are shown in Fig. 20.14. Clearly these are less convincing than those found for UO2 (Fig. 20.11). Any crystal field scheme with Np4þ predicts the highest G6 state at well over 200 meV and the matrix element is small. The transition(s) observed, therefore, must be between

2284

Magnetic properties

Fig. 20.14 Neutron inelastic magnetic scattering cross section for NpO2 as a function of temperature. The incident neutron energy was 180 meV and the average scattering angle 5 . The phonon contribution, which is small at these angles, has been subtracted. The full curve is a fit to the data of two Gaussians (shown as broken curves) plus a background. Reprinted from Amoretti et al. (1992). Copyright 1992 with permission from Elsevier.

the two G8 states. The extent of this splitting, around 55 meV, with evidence for a splitting of the peak as observed in UO2, is completely consistent with the V4 parameter deduced for UO2, after taking into account the change in the cation. Amoretti et al. (1992) also made measurements at lower energy and saw an interesting effect as the temperature was lowered through To, which is shown in Fig. 20.15. The transition must correspond to the splitting of the ground state G8 quartet below To. It thus appeared after these measurements that the crystal field parameters were as expected (based on UO2) for NpO2 and one really had a Np4þ ion (as the chemists and the Mo¨ssbauer spectroscopists insisted all the time!) and there was a need for a new idea. Muon spectroscopy (Kalvius et al., 2001) is also sensitive to the presence of dipole moments. The difficulty with this method is that there is always some uncertainty about at which point the muon annihilates, giving rise to the measured signal. However, Kopmann et al. (1998) showed that the signal from magnetic ordering was readily observed in UO2 and went on to observe a small effect in NpO2. Again, as with the neutron signal shown in Fig. 20.15, there is an ‘effect’ at To, but if it was dipole moment ordering, then the Mo¨ssbauer spectroscopy would have observed it. Given the huge sensitivity to magnetism in 5f shells that was discussed in connection with RXS (see Fig. 20.2), one of the first samples to try with this

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Fig. 20.15 Evolution of the spin‐flip scattering (i.e. the neutron spin state is changed on scattering indicating a magnetic cross section) as the temperature is lowered through the ˚ 1 and the sample is 25 K transition in NpO2. The momentum transfer is Q ¼ 1.3 A polycrystalline. The solid lines are fits to the data with a Gaussian function. The transition energy is 6.3 meV. Reprinted from Amoretti et al. (1992). Copyright 1992 with permission from Elsevier.

technique was NpO2, once the problem of looking at transuranium samples at the ESRF in Grenoble was solved. A large signal was indeed observed below To by Mannix et al. (1999). Because Mannix et al. (1999) did not have all the necessary tools to analyze the polarization of the scattered photons, they were cautious in ascribing this signal to dipole ordering, and, of course, the RXS technique cannot relate the intensity of the scattering to the magnitude of the dipole moment. They did, however, measure the dependence of the scattered intensity on the photon energy, and this is shown for UO2 and NpO2 in

2286

Magnetic properties

Fig. 20.16 The energy dependence of the integrated intensity from UO2 and NpO2 as a function of incident photon energy. Note that the signal for UO2 is fit to simple Lorentzian curves, as was the case for UAs, shown in Fig. 20.2. On the other hand, the NpO2 spectra, especially that at the strong M4 cannot be fit to a Lorentzian and requires a Lorentzian‐ squared function to fit the observed variation. Notice also the different energies for the M4,5 edges for U and Np. This allows the RXS technique to be element selective, and one can look at mixed (U,Np)O2 oxides and probe independently the magnetism on the two types of cations. For a study like this see Normile et al. (2002). Reprinted from Lander (2002). Copyright 2002 with permission from Elsevier.

Fig. 20.16. The energy dependence, which was not published by Mannix et al. (1999), as it was not understood, suggested that perhaps the scattering was not simple dipole. At the same time that these experiments were in progress, Santini and Amoretti (2000) proposed   that the ordering in NpO2 was not dipole hMi but rather of an octupole M3 nature. These can be best understood in terms of the shapes of the resulting charge distributions. For dipole ordering the magnetic moment is a vector quantity but it does not require a distortion of the charge density, which can then remain spherical around the atom. For quadrupole

The actinide dioxides 2287  2 ordering M there is no net magnetic moment as the (even) operator does not destroy time reversal symmetry, however, it does change the shape of the charge density of the electrons around the nucleus. Shapes such as prolate or oblate are typical symmetries of quadrupoles. For octupole moments hM3i time reversal symmetry is broken as the operator is odd; in addition, the charge distributions become even more aspherical. Santini and Amoretti (2000, 2002) proposed this model for NpO2 to explain the essentially ‘zero’ of Mo¨ssbauer spectroscopy, and yet to have a magnetic operator that would break time‐reversal symmetry to explain the results of the muon experiments. As the capabilities increased at the ESRF synchrotron, it became important to return to these experiments on NpO2. The new capabilities allowed the polarization of the scattered photons to be analyzed and, at the same time, the crystal to be rotated about the scattering vector while the intensity was monitored. This proved crucial. The scattering at the (001) and (003) reflections, first reported by Mannix et al. (1999), were found to originate totally from quadrupole charge distributions. This can be understood by both the azimuthal and polarization dependence, see Paixa˜o et al. (2002). Furthermore, the absence of either internal or external lattice distortions in NpO2 implies that the configuration involves 3k quadrupole ordering. A schematic picture of this is shown in Fig. 20.17. It is important to realize that the scattering observed here is not magnetic in origin. It arises from the aspherical nature of the charge distribution

Fig. 20.17 Crystal structure of NpO2 in the antiferromagnetic‐quadrupole state. The ellipsoids represent the orientation of the local symmetry axis at the Np position, not the actual charge distributions. The oxygen atoms are shown as spheres. Figure reprinted with permission from Paixa˜o et al. (2002). Copyright 2002 by the American Physical Society.

Magnetic properties

2288

of the 5f states. The local symmetry around the Np atoms is broken by the quadrupole distribution of the 5f states, and this gives rise to new reflections that are not allowed by the original space group. RXS is a particularly powerful tool as it tells us the nature of the electrons that make up the quadrupole distribution. In this case the strong energy dependence (Fig. 20.16) is related to the particular matrix elements that give rise to the scattering. This particular feature of RXS is becoming more important, and has also been used in the 3d series, see for example, Zimmerman et al. (2001). In general this is called Templeton scattering, after the pioneering crystallography of Templeton and Templeton (1985) even before tunable synchrotron beams were available. This section on NpO2 will finish by returning to UO2 and asking whether it would not also be possible to demonstrate directly the presence of the quadrupoles. Indeed, it would be, but in the case of UO2 there is also strong dipole scattering. If both of these occur at the same place in the reciprocal lattice then distinguishing the much weaker quadrupole effects becomes difficult. As far as known, NpO2 is the only material that exhibits quadrupolar ordering without an ordering of dipoles at the same or a lower temperature. On the other hand, the observation of a temperature‐independent susceptibility (Erdos et al., 1980) and the asymmetry in the muon experiments suggests that there exists an operator that lifts time reversal. (This cannot be done by the quadrupole operator as it is even in M.) The only possibility is that there is simultaneous ordering of an octupole moment, but a symmetry analysis has shown that it must be a different type from that proposed by Santini and Amoretti (2000). Observing this is almost impossible with the RXS technique and 5f electrons because the matrix elements will be small. Thus, the saga of NpO2 is not over completely, but at least the field now is illuminated, as opposed to the darkness surrounding research on NpO2 for almost 50 years! 20.14.3 4þ

4 5

Plutonium dioxide

The electronic state of Pu is 5f : I4 and relatively simple considerations lead to the suggestion that the crystal field ground state might be a singlet G1. (In a simple picture, the crystal field states for Pu4þ are simply the inverse of those for U4þ.) This idea was strongly reinforced by the first reported measurement of the susceptibility of stoichiometric PuO2 by Raphael and Lallement (1968). Remarkably they showed that the susceptibility was completely independent of temperature up to 1000 K, with a value 0.54  103 emu mol1 (after correcting for the small diamagnetism of the radon core). In order to calculate the above value of the TIP from the simple crystal field model, the necessary crystal‐field splitting between the ground state (singlet) G1 and first excited (triplet) G4 was found to be 280 meV. (If w is temperature independent up to 1000 K, then the magnetically active triplet state must be at least 2000–3000 K away in energy). The resulting V4 is approximately –320 meV, and this is not far from the value first proposed for UO2 (Rahman and Runciman, 1966) of V4 –400 meV.

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Yet, as discussed above, this value was found to be much smaller from experiments on UO2. Performing crystal field measurements on PuO2 with neutrons proved much harder than on UO2. For these measurements, samples of 30–80 g of materials are needed; moreover, it is quite impossible to use the 239Pu isotope for inelastic scattering, so one has to use samples with the rare isotope 242Pu. Still, these measurements were clearly of great importance, and finally a suitable sample (79 g, triply encapsulated) was transported to Intense Pulsed Neutron Source (IPNS) at Argonne and the experiment performed. At least two peaks were seen, spread over 85–125 meV. In the crystal field scheme only one transition is expected as the matrix elements for transitions from the G1 singlet state are zero except for the one transition G1 ! G4. However, by examining the Q‐ dependence of the scattering it became clear that most of the observed peaks increased in intensity with Q, whereas electronic transitions should decrease with Q. In fact only the transition at 120 meV appeared electronic and the others were assigned to H‐modes from an impurity, probably from water in the PuO2 (Kern et al., 1990). (Neutron scattering is extremely sensitive to hydrogen and, although these impurities were later detected by infrared spectroscopy, neutrons are still a wonderful analytical tool – if rather expensive – for free or bound H.) This was rather an unfortunate situation, and it took almost a decade to get the sample purified at Los Alamos, and then actually run on the Los Alamos spallation source. However, the result (Kern et al., 1999) merited the wait. A single peak at 123 (4) meV was observed, but with a width significantly greater than the experimental resolution (Fig. 20.18). By calibrating the spectrometer with the known scattering from vanadium, Kern et al. (1999) were able to put the scattering on an absolute scale. They then took the crystal field parameters (V4 and V6) from UO2 and extrapolated them to PuO2 where they predicted a single transition at 115 meV. Moreover, the absolute calculated intensity of the transition also agreed perfectly with the experiment, so this gives considerable confidence to the crystal field parameters. However, there is now a major discrepancy between w as determined by Raphael and Lallement (1968) and w calculated from the crystal field scheme. Using the observed V4 and V6 parameters, the calculated w ¼ 0.90  103 emu mol1, a value almost twice as great as measured! Many thought that the 1968 measurement must be wrong, but any impurities in the Pu would normally lead to a larger value, and the amount of diamagnetic impurities (e.g. ThO2) to make the difference exceeded 10% and appeared unreasonable. Recently, this value of the experimental w has been remeasured (Kolberg et al., 2002) and found to be correct. Earlier attempts by Goodman (Kern et al., 1990) to question the crystal field scheme and develop a so‐called strong coupling approach are still a possibility to explain these results (and those for CmO2 as discussed below), but they have not yet been fully developed. More recently, Colarieti‐Tosti et al. (2002) have reported on a first principles calculation of the crystal field scheme, and they

2290

Magnetic properties

Fig. 20.18 Neutron inelastic spectra from PHAROS of 29 g of 242PuO2 at T ¼ 30 K. The incident neutron energy was 184 meV. The resolution of the instrument is 4 meV at these energy transfers, but the Gaussian fit gives a width of 11 meV. No other electronic signal was found between 10 and 100 meV. Figure reprinted with permission from Kern et al. (1999). Copyright 1999 by the American Physical Society.

arrive at an energy separation G1 ! G4 99 meV, which is relatively close to the observed value of 123 meV. These authors went on to consider the discrepancy between the measured and calculated susceptibility, and they introduced the idea that there is an antiferromagnetic exchange interaction between the Pu4þ ions, mediated by the admixture of the actinide 6d states into valence band. Knowing that UO2 orders antiferromagnetically, a rough value of the exchange parameter may be deduced, and then scaled to the case of Pu. The resulting calculations (demonstrated with other data in Fig. 20.19) are in good agreement with experiment, except that they show some curvature for T > 400 K. It is still difficult to understand what appeared to be the amazingly uninteresting susceptibility of PuO2 first measured in 1968. Recently Kolberg et al. (2002) have suggested that the dynamical JT effect may play a role also in (U,Pu)O2 materials, as discussed earlier for pure UO2. Indeed, with this additional interaction agreement between theory and experiment might be possible. All this work shows that the complications in PuO2 have, like those in the other oxides, now stretched over almost half a century. The broadening of the crystal field transition remains so far unexplained. However, a slight broadening of the excited G4 state could either come from antiferromagnetic exchange or the dynamic JT effect.

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Fig. 20.19 The magnetic susceptibility of PuO2. The measurements are the T‐independent straight dotted line. The calculated bare susceptibility with a single G1 ! G4 excitation energy of 284 meV fits the data at T ¼ 0 and is shown as the dashed line labeled G14 (284). The corresponding bare susceptibility with G1 ! G4 ¼ 123 meV, which fits the neutron experiment, is the dotted line labeled G14 (123). Adding additional CF transitions to the 123 meV model produces the improvement shown by the solid line labeled CEF (123). Similarly the CEF (99) line uses all the CF transitions with G1 ! G4 ¼ 99 meV. The effect of using the antiferromagnetic molecular field deduced from that of UO2 to enhance the bare susceptibility is given by the curves labeled CEFþI. Figure reprinted with permission from Colarieti‐Tosti et al. (2002). Copyright 2002 by the American Physical Society.

20.14.4

Americium dioxide

For the heavier elements starting with Am, experiments become really sparse. Am4þ in AmO2 should have a ground 5f5:6H5/2 state, i.e. a Kramers’ ion so that the degeneracy cannot be lifted by a crystal field interaction (the same as Np in

Magnetic properties

2292

NpO2). EPR studies of Am4þ doped into ThO2 and CeO2 establish the G7 doublet as the ground state (Abraham et al., 1971; Kolbe et al., 1974) with a geff ¼ 1.27. Karraker (1975a) has made susceptibility measurements (on a sample with 224 mg of 243Am and a radiation field of 150 roentgen h1 at the sample!) and found an effective moment of 1.31mB at low temperature. Since S ¼ 5/2, this gives g ¼ 0.44 which is in excellent accord with the value for a 5f5 state when intermediate coupling is taken into account (Lander, 1993). With an effective spin of Seff ¼ 1/2, corresponding to the G7 doublet, one obtains geff ¼ 1.51, in reasonable agreement with the EPR work. Karraker (1975a) also found clear evidence for a phase transition at To ¼ 8.5 K. The susceptibility shows a peak and then decreases as the temperature decreases. This was puzzling at the time, as a Mo¨ssbauer experiment (Kalvius et al., 1969) had found no evidence for any phase transition. Later, Boeuf et al. (1979) prepared another sample of 243AmO2 and performed neutron scattering experiments at the Institute Laue Langevin in Grenoble. They observed no magnetic diffraction peaks below To in agreement with the Mo¨ssbauer results. No further experiments have been reported on the low‐temperature properties of AmO2 since 1979. Of course, given what happens in the case of NpO2 (the ordering of the quadrupoles) in a Kramers ion with an odd number of 5f electrons (Paixa˜o et al., 2002), it is easy to suggest that the same thing happens in AmO2. This would make a really beautiful experiment with RXS, but one would need a single crystal, even if only of 20 mg. 20.14.5

Curium dioxide

With Cm the ground state should be a 5f6 7F0 state. Since L ¼ |S| ¼ 3, there should be no sign whatsoever of magnetism, particularly in the susceptibility. The splitting to the first excited state is at 400 meV, so the susceptibility should be temperature‐independent and small. The difficulty is that Cm3þ is more stable thermodynamically than Cm4þ so it is not difficult to imagine small amounts of Cm3þ in the CmO2 matrix. Cm3þ has the 5f7 8S7/2 configuration and so it could contribute 7mB of magnetism. Many early efforts on CmO2 reported a sloping susceptibility, but in all cases it was expected that was a consequence of contamination with Cm3þ. In 1986 Morss at Argonne set out to make stoichiometric CmO2 from the rare isotope 248Cm. This had the advantage that the radiation from 248Cm is relatively small compared to the more abundant 244Cm so that radiation damage and production of defects, which could convert Cm4þ into Cm3þ, were reduced. The sample ( 55 mg) was then studied with neutron diffraction at the IPNS spallation source at Argonne. The small sample and the relatively modest flux at IPNS meant that the strongest powder diffraction peak in CmO2 gave 1 ct min1, with a peak/background ratio of 0.6. (Part of the background came from the neutrons emitted from the 248Cm sample itself.) Despite these difficulties, 4þ

The actinide dioxides

2293

Rietveld analysis was successful and gave a Cm:O stoichiometry of 1.97 (3), which is statistically insignificant from the stoichiometric composition (Morss et al., 1989). The X‐ray pattern from CmO2 is, of course, totally dominated by the scattering from the Cm, so this is a good illustration of the power of neutrons, where the scattering from curium and oxygen have almost equal scattering lengths. In agreement with X‐rays, no evidence of additional phases was found. Susceptibility measurements were then made and showed, once again, a slope, which corresponded to meff ¼ 3.36 (6)mB. More than 10 years have gone by since this work and no suggestion has been made to resolve the difficulty between simple crystal field theory (with a 7F0 ground state) and the finite effective moment. However, taking the theory, developed for another even 5f electron material (Pu with four 5f electrons), can be utilized by assuming that the susceptibility is affected by the exchange and possibly also JT interactions as found in another even‐f system, UO2. Although J ¼ 0, there is an S quantum number of 3 (6f electrons) and the spin state of Cm will give rise to antiferromagnetic exchange via coupling to the excited (magnetic) J ¼ 1 state. Detailed calculations for this have not been made, but should be. Furthermore, this effect is not expected to give a constant meff for all Cm4þ ions. The antiferromagnetic exchange passes through the actinide 6d states and their mixing with the oxygen p‐states. This will change depending on the anions involved, for example it will be different for CmO2 than CmF4. More experiments on these materials would be interesting and should further increase our understanding of the interactions in the ionic actinide systems. As discussed in Section 20.8, Milman et al. (2003) performed density functional theory (DFT) calculations for Cm compounds and suggested that an itinerant magnetism model might be appropriate for CmO2. 20.14.6

Summary of the magnetic properties of the actinide dioxides

Many physicists have been kept busy for the last half a century studying the properties of the actinide dioxides. Initially it was expected that the data would be relatively straightforward to analyze because of the very simple fcc structure. As happens frequently in actinide research, the trail has been tortuous, and in all cases there are still experiments to be done, although a general understanding of the ground state magnetic properties now appears reasonably sound. Neutron inelastic scattering has played an important role in establishing the crystal field interactions and showing that the earlier theoretical models were incorrect. The crystal field ground states are then perturbed by higher‐order interactions, notably the quadrupolar ones, and this is a consequence of the aspherical nature of the 5f electron states. The effect is particularly apparent in NpO2 (5f3), in which the quadrupoles order at 25 K, presumably because of their interactions with the lattice, and there is no accompanying dipole ordering (at least down to 1.5 K). For the moment NpO2 appears unique in this respect, but no doubt

2294

Magnetic properties

other materials will be found; AmO2 appears a good candidate. The interactions with the lattice are very strong for all the oxides, and give rise to a number of effects. Most notably, the Jahn–Teller interactions cause an internal static distortion in UO2, but can be dynamic in nature as well (Sasaki and Obata, 1970). If the susceptibility of PuO2 (5f 4) is reasonably well explained by the indirect exchange through the oxygen p‐states (thus implying a measure of covalency in these materials), the situation in CmO2 (5f 6) is more complicated. Perhaps some of the same arguments can be used, together with the JT effect, but it is still not possible to exclude the presence of Cm3þ ions in the compound, and these would give a large susceptibility term, as they are 5f7. The detailed exchange interactions (measured by neutron inelastic scattering on single crystals, Caciuffo et al., 1999) in UO2 still are not understood from first principles, illustrating the complexity of the interactions that occur in these oxides.

ABBREVIATIONS

AF bcc BM (b) t Bu CEA CF cm1 Cp dhcp DFT ENDOR EPR or epr Et fcc IPNS JT LO Me meV mK NMR or nmr RXS Tc TIP TN

antiferromagnetic body‐centered cubic Bohr magneton t butyl – tertiary butyl – (CH3)3C Commissariat a` l’Energie Atomique crystal field wave numbers cyclopentadienyl – C5H5 double hexagonal close‐packed density functional theory electron‐nuclear double resonance electron paramagnetic resonance ethyl – C2H5 – CH3CH2 face‐centered cubic Intense Pulsed Neutron Source Jahn–Teller longitudinal optic methyl – CH3 millielectron volts milli‐Kelvin nuclear magnetic resonance resonant X‐ray scattering temperature below which superconductivity occurs temperature‐independent paramagnetism Neel temperature

References To XMCD

2295

Temperature at and below which a magnetically ordered phase appears X‐ray magnetic circular dichroism UNITS

Two different energy units are used in this review depending on the discussion. The units are meV and cm1. The conversion between these units is as follows: (1 eV ¼ 8065.479 cm1); (1 meV ¼ 0.001 eV ¼ 8.065 cm1); (1 cm1 ¼ 1.2399  104 eV or 0.12399 meV). It is useful to note that kT (where k is the Boltzmann constant) at 300 K ¼ 25.85 meV ¼ 208.34 cm1. REFERENCES Abragam, A. and Bleaney, B. (1970) Electron Paramagnetic Resonance of Transition Ions, Clarendon Press, Oxford. Abraham, M. M., Judd, B. R., and Wickman, H. H. (1963) Phys. Rev., 130, 611–12. Abraham, M. M., Finch, C. B., and Clark, G. W. (1968) Phys. Rev., 168, 933. Abraham, M. M., Boatner, L. A., Finch, C. B., Reynolds, R. W., and Zeldes, H. (1970) Phys. Rev. B, 1, 3555–60. Abraham, M. M., Boatner, L. A., Finch, C. B., and Reynolds, R. W. (1971) Phys. Rev. B, 3, 2864 Abraham, M. M., Boatner, L. A., Finch, C. B., Kot, W. K., Conway, J. G., Shalimoff, G. V., and Edelstein, N. M. (1987) Phys. Rev. B, 35, 3057–61. Aderhold, C., Baumgartner, F., Dornberger, E., and Kanellakopulos, B. (1978) Z. Naturforsch., 33a, 1268–80. Aldred, A. T., Cinader, G., Lam, D. J., and Weber, L. W. (1979) Phys. Rev. B, 19, 300–5. Alessandrini, V. A., Cracknell, A. P., and Przystawa, J. A. (1976) Commun. Phys., 1, 51–5. Allen, S. J. (1968a) Phys. Rev., 167, 492–6. Allen, S. J. (1968b) Phys. Rev., 166, 530–9. Allen, S., Barlow, S., Halasyamani, P. S., Mosselmans, J. F. W., O’Hare, D., Walker, S. M., and Walton, R. I. (2000) Inorg. Chem., 39, 3791–8. Almond, P. M., Deakin, L., Porter, M. J., Mar, A., and Albrecht‐ Schmitt, T. E. (2000) Chem. Mater., 12, 3208–13. Amberger, H. ‐D., Fischer, R. D., and Kanellakopulos, B. (1975) Theor. Chim. Acta, 37, 105–27. Amberger, H.‐D. (1976a) J. Organomet. Chem., 116, 219–29. Amberger, H.‐D. (1976b) J. Organomet. Chem., 110, 59–66. Amberger, H.‐D., Fischer, R. D., and Kanellakopulos, B. (1976) Z. Naturforsch., B31, 12–21. Amoretti, G., Blaise, A., Caciuffo, R., Fournier, J. M., Hutchings, M. T., Osborn, R., and Taylor, A. D. (1989) Phys. Rev. B, 40, 1856–70. Amoretti, G., Blaise, A., Caciuffo, R. C., Di Cola, D., Fournier, J. M., Hutchings, M. T., Lander, G. H., Osborn, R., Severing, A., and Taylor, A. D. (1992) J. Phys. Condensed Matter, 4, 3459–78.

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APPENDIX I

NUCLEAR SPINS AND MOMENTS OF THE ACTINIDES Nuclear spins and nuclear moments are used to test the single‐particle models and nuclear quadrupole moments provide the deformation of the nucleus. In the following table, we present measured values of ground state spin in units of h, magnetic dipole moment (m) in units of nuclear magneton, and spectroscopic
quadrupole moment (Q) in units of barns. The data have been taken from Raghavan (1989) and Firestone and Shirley (1996).

Nuclide 217

Ac Ac 229 Th 228 Pa 230 Pa 231 Pa 233 Pa 233 U 235 U 237 Np 238 Np 239 Np 239 Pu 241 Pu 241 Am 242 Am 242m Am 243 Am 243 Cm 245 Cm 247 Cm 249 Bk 249 Cf 253 Es 254m Es 227

Nuclear spin (ħ)

Nuclear magnetic moment (nuclear magneton)

9/2 3/2 5/2 3 2 3/2 3/2 5/2 7/2 5/2 2 5/2 1/2 5/2 5/2 1 5 5/2 5/2 7/2 9/2 7/2 9/2 7/2 2

þ3.825(45) þ1.1(1) þ0.46(4) þ3.48(33) þ2.00(29) þ2.01(2) þ3.39(70) 0.59(5)
0.38(3) þ3.14(4) þ0.203(4)
0.683(15) þ1.61(3) þ0.3879(15) þ1.00(5) þ1.61(4) 0.41 0.5 (1) 0.37 2.0(4)
0.28 þ4.10(7) 2.90(7)

Electric quadrupole moment (barns) þ1.7(2) þ4.3(9) –1.72(5)
3.0 3.663(8) 4.936(6) þ3.886(6)

þ5.6(20) þ4.2(13)
2.4(7) þ6.5(20) þ4.30(3)

þ5.79 6.7(8) 3.7(5)

Firestone, R.B. and Shirley, V.S. (eds.) (1996). Table of Isotopes, 8th edn. John Wiley, New York. Raghavan, P. (1989) At. Nucl. Data Tables, 42, 189–291.

3441

APPENDIX II

NUCLEAR PROPERTIES OF ACTINIDE AND TRANSACTINIDE NUCLIDES Irshad Ahmad

DISCUSSION

In this appendix, an elementary discussion of the nuclear properties of heavy elements is presented. For a better understanding of the subject, the reader should refer to nuclear chemistry textbooks (Krane, 1988; Choppin et al., 2002) and for the information on decay data, the Table of Isotopes (Firestone and Shirley, 1996) or the Table of Radioactive Isotopes (Browne and Firestone, 1986) or Nuclear Data Sheets (Tuli, 2004) should be consulted. Isotopes of all elements with Z  89 are radioactive. The most common mode of decay for these nuclei is by the emission of alpha particles (4He ions). Alpha decay energies have been experimentally measured (Browne and Firestone, 1986; Firestone and Shirley, 1996) for most nuclides and these can also be calculated from atomic masses (Wapstra et al., 2003). The a decay of a nucleus with atomic number Z and atomic mass A produces a daughter nucleus with atomic number Z–2 and atomic mass A–4. During the a decay, about 2% of the available decay energy is imparted to the recoiling daughter nucleus and the remaining energy is carried off by the fast moving a‐particle. Several groups of a‐particles are emitted by a sample of a nuclide, each with a definite energy. For the actinide nuclides, a‐particle energies range from about 4 to 11 MeV. As a rule, a‐particle energy increases with increasing Z, and for a given element, it decreases with increasing mass number. The a‐decay half‐life decreases exponentially with increasing energy. As a guide, every 50 keV increase in the decay energy reduces the half‐life by a factor of 2. The dependence of the a‐decay half‐life on the decay energy is given by the well‐known Geiger–Nuttall law and more recently by Viola–Seaborg formula. A very useful quantity that facilitates the understanding of the mechanism of a‐decay is the concept of hindrance factor. It is defined as the ratio of the experimental partial a‐decay half‐life to the theoretical half‐life calculated on the assumption that the a‐particle pre‐exists in the nucleus and during its emission, it carries no angular momentum. An alpha transition in which the 3442

Nuclear properties of actinide and transactinide nuclides

3443

ground state configuration of the parent nucleus remains unchanged is called ‘favored transition’. All alpha transitions between the ground states of even– even nuclei are favored transitions and are assigned a hindrance factor of one. Like elements of lower Z, each actinide element has one or more b‐stable isotopes. Isotopes heavier than the b‐stable isotope decay by the emission of b
particles (electrons) and isotopes lighter than the b‐stable isotopes decay by electron capture (EC). Electron capture decay is usually accompanied by the emission of K x‐rays of the daughter nuclide. These x‐rays provide a signature of the decaying nuclide. In heavy nuclei, bþ/EC ratio is very small and, as a consequence, positron (bþ) emission has been observed only in a few nuclei. The b‐decay energy increases as the mass of the isotope gets further away from the line of b‐stability. A quantity denoted by log ft is very useful in classifying the b transitions and estimating the b‐decay half‐lives of unknown nuclei. The ft value, also called the reduced b transition probability, is the energy‐independent transition rate. Spontaneous fission is a decay process in which a nucleus breaks up into two almost equal fragments. Each fission event is accompanied by the release of about 200 MeV energy and the emission of two to four neutrons. More than hundred nuclides are produced in fission of a nuclide sample and the mass yields and charge distributions have been measured for many fissioning systems (Wahl, 1989; Ahmad and Phillips, 1995). The fission half‐life depends on the fissility parameter Z2/A and is the major decay mode for many isotopes of element 100 and beyond. Nuclides with reasonable fission branch and available for experiments and industrial use are 248Cm (t1/2 ¼ 3.40 105 years) and 252Cf (t1/2 ¼ 2.64 years). The isotope 252Cf is widely used as a neutron source in industry and research. Another rare mode of decay for heavy elements is the decay by the emission of intermediate mass fragments. These fragments are heavier than a particles but smaller than fission fragments. The branching ratio for this kind of radioactivity is extremely small (10
10). Examples of such radioactivity are the 24Ne emission by 231Pa and 232U (Price, 1989). Alpha and b transitions usually populate excited states in addition to the ground states of the daughter nuclei. The excited states then decay to the ground state by emission of g rays and conversion electrons. Typical half‐lives of the excited states range from 10
9 to 10
14 s. However, in some cases, the decay of an excited state is forbidden for fast magnetic dipole (M1), electric dipole (E1), or electric quadrupole (E2) transitions because of the angular momentum selection rule. Such states have half‐lives between nanoseconds and years. An excited state that has a half‐life value greater than a nanosecond is called a ‘metastable’ state or ‘isomer’. The isomeric state either de‐excites to the ground state of the same nucleus by an internal transition (IT) or it decays by the usual mode of disintegration. Most isomers occur because of the large difference between the spins of the excited state and the ground state. However, there are isomers which result not

3444

Discussion

by the difference in the spins of the states but by the difference in the shapes. These isomers decay by fission and are called ‘fission isomers’ or ‘shape isomers’ and have half‐lives between 10
9 and 10
3 s. These isomers have deformations that are twice as large as the deformations of the ground states. More than 50 fission isomers have been discovered (Vandenbosch, 1977). Very neutron‐deficient nuclides decay predominantly by electron capture (EC). In some of these nuclei, the EC decay energy is quite large (> 4 MeV) and hence states at high excitation energy are populated in the daughter nucleus and a small fraction of these excited states decay by fission. Delayed fission of many nuclei has been observed (Hall and Hoffman, 1992). Nuclear structure studies of actinide nuclides have been performed using a variety of techniques. These include high‐resolution alpha, electron and gamma‐ray spectroscopy, charged‐particle transfer reaction spectroscopy, and Coulomb excitation studies. These investigations have provided significant information on the shape, size, and single‐particle potential of actinide nuclei. The available data establish a spheroidal shape for nuclei with A  225, with major to minor axes ratio of 1.25. The intrinsic quadrupole moments of actinide nuclei have been measured to be about 10–23 e cm2 and the nuclear radii are about 10
12 cm. Although most actinide nuclei have spheroidal shapes, there are indications that some neutron‐deficient Ac and Pa nuclei have small octupole deformation in their ground states. These nuclei are pear‐shaped and are axially symmetric but they are reflection asymmetric. Examples of such nuclei are 229Pa and 225Ac (Ahmad and Butler, 1993). In nuclei, nucleons (neutrons and protons) move in orbits under the influence of the central nuclear potential. Nilsson (1955) and others (Chasman et al., 1977) have calculated the eigenvalues and eigenfunctions of nucleons in a deformed potential as a function of the deformation b. Plots of the eigenvalues versus the deformation, commonly known as Nilsson diagrams, are extremely useful in understanding the single‐particle properties of actinide nuclei. Each Nilsson state is characterized by a set of quantum numbers O p, N, Nz, and L. The quantum number O is the projection of the single‐particle angular momentum on the nuclear symmetry axis and p is the parity of the wavefunction. The asymptotic quantum numbers N, Nz and L denote the oscillator shell number, the number of the oscillator quanta along the symmetry axis, and the projection of the orbital angular momentum on the symmetry axis, respectively. In heavy nuclei, neutrons (protons) fill each orbital above the closed shell of 126 (82) pairwise and thus the ground state of an odd‐mass nucleus is simply the orbital occupied by the last unpaired nucleon. All even–even nuclei have ground state spin‐parity of 0þ. A spheroidal nucleus rotates about an axis perpendicular to the nuclear symmetry axis. The projection, K, of the total angular momentum, I, on the symmetry axis is the same as O. The rotation of a spheroidal nucleus generates a rotational band with spin sequence K, Kþ1, Kþ2, . . . . The

Nuclear properties of actinide and transactinide nuclides

3445

rotational energy EI of a level with spin I is given by the expression EI ¼

h
2 IðI þ 1Þ; 2=

where
h is Planck’s constant and = is the nuclear moment of inertia. Typical values of
h2/2= are 7.0 keV for even–even actinide nuclei and 6.0 keV for odd‐ mass nuclei. The ground state band of an even–even nucleus has spin‐parity sequence 0þ, 2þ, 4þ . . .; odd spin values are not allowed. Qualitative and quantitative analysis of actinide samples can be performed by using a variety of techniques (Knoll, 2000). Gross counting with a 2p (50%) geometry gas proportional counter can be used to determine the a or b
count rate in a sample. These counters have very low background for a particles but somewhat higher background for electrons. Background of 0.1 a count per minute can be easily achieved for these counters. Alpha pulse height analysis can be used to identify nuclides in a sample. Alpha spectra are measured either by Au–Si surface barrier detectors or passivated implanted planar silicon (PIPS) detectors. For best resolution (full width at half maximum), which can be as low as 9.0 keV, extremely thin sources are required. Precise energies and intensities of alpha groups have been tabulated by Ritz (1991). Gamma‐ray spectroscopy with high‐resolution germanium spectrometers provides a powerful technique for qualitative and quantitative analysis of actinide samples. For high‐energy g rays in the range of 200 keV to 1.5 MeV, large volume Ge detectors provide the best sensitivity. Resolutions (FWHM) of less than 2.0 keV at the 60Co 1332.5 keV line are easily achieved. In actinide nuclei, K x‐ray energies lie in the 80–160 keV range and can be measured with high‐resolution low-energy planar spectrometers (LEPS). K x‐rays are produced when a vacancy in the K shell of an atom, created by electron capture or internal conversion, is filled by an electron from a higher shell. These K x‐rays energies depend on the atomic number and there is sufficient separation between the energies of adjacent elements for them to be clearly identified. The Cm K x‐ray spectrum produced in the alpha decay of 251Cf and measured with a high‐ resolution LEPS is displayed in Fig. A.2.1. The resolution (FWHM) of the spectrometer is about 500 eV. Measurements of gamma ray spectrum and K x‐ray spectrum are very useful in identifying and quantifying odd‐mass nuclei. L x‐rays of actinide nuclei, which are produced when a vacancy in the L subshell of an atom is filled by an electron from a higher shell, have energies in the 10–30 keV range. Spectra of L x‐rays can be measured with lithium‐ drifted silicon, Si(Li), detectors with resolutions (FWHM) of 300 eV. A Np L x‐ray spectrum from 241Am alpha decay, measured with a Si(Li) spectrometer, is shown in Fig. A.2.2. These spectra are also characteristic of the element but are more complex. The definition of x‐ray components is given in (Firestone and Shirley, 1996). Even–even nuclei decay to excited levels of daughter nuclei which de‐excite by highly L converted transitions generating L x‐rays. Thus even–even

3446

Discussion

Fig. A.2.1 K X‐ray spectrum of Cm, produced in the alpha decay of a 2 cm2 1 cm LEPS spectrometer.

251

Cf, measured with

nuclei, which do not have any intense g rays, can be analyzed by L X‐ray spectroscopy. Fissioning nuclides like 252Cf can be assayed by measuring the gamma‐ray spectrum with large‐volume Ge detectors and using the intensities of gamma rays emitted in the decay of the abundant fission fragments (Ahmad et al., 2003). Some actinide nuclides have very long half‐lives and hence they occur in nature. These include 232Th, 235U and 238U which decay through a series of isotopes terminating at stable Pb isotopes. Isotopes of Ac, Th, and Pa are usually separated from the parent nuclides and used in the chemical and nuclear studies of these elements. Transuranium isotopes are produced by long irradiations in nuclear reactors. In the US, there is a national program for the production and isolation of transuranium isotopes utilizing the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory. The heaviest nuclide produced in this program is the 100 day 257Fm. Neutron‐deficient actinide isotopes are usually produced by nuclear reactions in charged particle accelerators. All data in the tables of nuclear properties given in the preceding chapters and in this appendix have been taken from Browne and Firestone (1986), Firestone and Shirley (1996), Nuclear Data Sheets (Tuli, 2004) and from the

Nuclear properties of actinide and transactinide nuclides

Fig. A.2.2 L X‐ray spectrum of Np, produced in the alpha decay of a 1 cm diameter and 5 mm thick Si(Li) detector.

241

3447

Am, measured with

web sites at the Isotope Project, Lawrence National Berkeley Laboratory (http://www.lbl.gov) and at the Nuclear Data Center, Brookhaven National Laboratory (http://www.nndc.bnl.gov). For the heaviest elements, data were taken from Armbruster (2000) and Hofmann and Mu¨nzenberg (2000). The cut‐off date for literature survey was June 2004. The notations for decay modes in the tables are: a for alpha decay, b
for b
decay, bþ for positron decay, EC for electron capture decay, IT for isomeric transition, and SF for spontaneous fission. The letter m after a mass number represents an isomer. Isomers with half‐lives of less than 1 s (except for the heaviest elements) and fission isomers are omitted from the tables. Energies and intensities are given for the most abundant a groups and most intense g rays; for b
particles, the maximum energy bmax is given. In the last column of Table A2.1, only the convenient methods of production are given; ‘nature’ denotes that the nuclide occurs in nature and ‘multiple neutron capture’ means that the nucleus is produced by multiple neutron capture in a high‐flux reactor such as HFIR. The specific activity S in disintegrations per minute per microgram was calculated using the expression S¼

4:17449 1017 ; t1=2 A

3448

References

where t1/2 is half‐life of the nuclide in minutes and A is the atomic mass in atomic mass units. The half‐lives and atomic masses were taken from the references mentioned earlier in this text.

REFERENCES Ahmad, I. and Butler, P. A. (1993) Annu. Rev. Nucl. Part. Sci., 43, 71–117. Ahmad, I. and Phillips, W. R. (1995) Rep. Prog. Phys., 58, 1415–63. Ahmad, I., Moore, E. F., Greene, J. P., Porter, C. E., and Felker, L. K. (2003) Nucl. Instrum. Methods, A505, 389–92. Armbruster, P. (2000) Annu. Rev. Nucl. Part. Sci., 50, 411–79. Browne, E. and Firestone, R. B. (1986) Table of Radioactive Isotopes (ed. V. S. Shirley), John Wiley, New York. Chasman, R. R., Ahmad, I., Friedman, A. M., and Erskine, J. R. (1977) Rev. Mod. Phys., 49, 833–91. Choppin, G. R., Liljenzin, J.‐O., and Rydberg, J. (2002) Radiochemistry and Nuclear Chemistry, 3rd edn., Butterworth‐Heinemann, Woburn. Firestone, R. B. and Shirley, V. S. (eds.) (1996) Table of Isotopes, 8th edn., John Wiley, New York. Hall, H. L. and Hoffman, D. C. (1992) Annu. Rev. Nucl. Part. Sci., 42, 147–75. Hofmann, S. and Mu¨nzenburg, G. (2000) Rev. Mod. Phys., 72, 733–67. Knoll, G. F. (2000) Radiation Detection and Measurement, John Wiley, New York. Krane, K. S. (1988) Introductory Nuclear Physics, John Wiley, New York. Nilsson, S. G. (1955) Kgl. Dansk Videnskab. Selskab. Matt.‐Fys. Medd., 29, 16. Price, P. B. (1989) Annu. Rev. Nucl. Part. Sci., 39, 19–42. Ritz, A. (1991). At. Data Nucl. Data Tables, 47, 205–39. Tuli, (ed.) J. K. (2004) Nuclear Data Sheets, Academic Press, San Diego, CA. Vandenbosch, R. (1977) Annu. Rev. Nucl. Sci., 27, 1–35. Wahl, A. C. (1989) At. Nucl. Data Tables, 39, 1–156. Wapstra, A. H., Audi, G., and Thibault, C. (2003) Nucl. Phys., A729, 129–336.

3449 TABLES

In the following tables we reproduce the tables in each of the chapters 2 through 14 that contain the nuclear properties of the actinide and transactinide isotopes. We then give a table of specific activities of these isotopes.

Nuclear properties of actinium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

a a a a a a a

a 7.750 a 7.790 a 7.712 a 7.572 a 7.758 a 7.59 a 7.46

175

Lu(40Ar,9n)

175

Lu(40Ar,8n) Lu(40Ar,7n)

209 210

33 ms 22 ms 22 ms 95 ms 25 ms 0.10 s 0.35 s

211

0.25 s

a

a 7.48

212

0.93 s

a

a 7.38

213

0.80 s

a

a 7.36

214

8.2 s

215

0.17 s

a 7.214 (52%) 7.082 (44%) a 7.604

216 216 m

0.33 ms 0.33 ms

a  86% EC 14% a 99.91% EC 0.09% a a

217 218 219 220

69 ns 1.08 ms 11.8 ms 26.4 ms

a a a a

221

52 ms

a

222

5.0 s

a

222 m

63 s

223

2.10 min

224

2.78 h

a > 90% EC  1% IT < 10% a 99% EC 1% EC  90% a  10%

206 207 208

a 9.072 a 9.108 (46%) 9.030 (50%) a 9.650 a 9.20 a 8.66 a 7.85 (24%) 7.68 (21%) 7.61 (23%) a 7.65 (70%) 7.44 (20%) a 7.00 a 7.00 (15%) 6.81 (27%) a 6.662 (32%) 6.647 (45%) a 6.211 (20%) 6.139 (26%)

175 197

Au(20Ne,8n) Au(20Ne,7n) 203 Tl(16O,9n) 197 Au(20Ne,6n) 203 Tl(16O,8n) 203 Tl(16O,7n) 197 Au(20Ne,5n) 197 Au(20Ne,4n) 203 Tl(16O,6n) 203 Tl(16O,5n) 197 Au(20Ne,3n) 203 Tl(16O,4n) 209 Bi(12C,6n) 209 Bi(12C,5n) 197

208

Pb(14N,5n) Pa daughter 223 Pa daughter 208 Pb(15N,3n) 224 Pa daughter 222

205

Tl(22Ne,a2n) Pb(18O,p4n) 226 Ra(p,5n) 208 Pb(18O,p3n) 208 Pb(18O,p3n) 209 Bi(18O,an) 208

227

Pa daughter

228

Pa daughter

3450 Nuclear properties of actinium isotopes. (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

225

10.0 d

a

225

Ra daughter

226

29.37 h

226

Ra(d,2n)

227

21.772 yr

b
83% EC 17% a 6 10
3% b
98.62% a 1.38%

228

6.15 h

b


229

62.7 min

b


230

122 s

b


231

7.5 min

b


232 233 234

119 s 145 s 44 s

b
b
b


a 5.830 (51%) 5.794 (24%) g 0.100 (1.7%) a 5.399 b
1.10 g 0.230 (27%) a 4.950 (47%) 4.938 (40%) b
0.045 g 0.086 b
2.18 g 0.991 b
1.09 g 0.165 b
1.4 g 0.455 b
2.1 g 0.282

nature

nature 229

Ra daughter Th(g,p2n) 232 Th(g,pn) 232

232

Th(g,p) Th(n,pn) 238 U þ Ta 238 U þ Ta 238 U þ Ta 232

Nuclear properties of thorium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

209 210 211 212 213 214 215

3.8 ms 9 ms 37 ms 30 ms 140 ms 100 ms 1.2 s

a a a a a a a

32

216 217 218

28 ms 0.237 ms 0.109 ms

a a a

a 8.080 a 7.899 a 7.792 a 7.82 a 7.691 a 7.686 a 7.52 (40%) 7.39 (52%) a 7.92 a 9.261 a 9.665

219 220 221

1.05 ms 9.7 ms 1.68 ms

a a a

222

2.8 ms

a

a 9.34 a 8.79 a 8.472 (32%) 8.146 (62%) a 7.98

S þ 182W Cl þ 181Ta 35 Cl þ 181Ta 176 Hf(40Ar,4n) 206 Pb(16O,9n) 206 Pb(16O,8n) 206 Pb(16O,7n) 35

206

Pb(16O,6n) Pb(16O,5n) 206 Pb(16O,4n) 209 Bi(14N,5n) 206 Pb(16O,3n) 208 Pb(16O,4n) 208 Pb(16O,3n) 206

208

Pb(16O,2n)

3451 Nuclear properties of thorium isotopes. (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

223

0.60 s

a

208

Pb(18O,3n)

224

1.05 s

a

228

U daughter Pb(22Ne,a2n)

225

8.0 min

a  90% EC  10%

226

30.57 min

a

227

18.68 d

a

228

1.9116 yr

a

229

7.340 103 yr

a

230

7.538 104 yr

a

231

25.52 h

b


232 233

1.405 1010 yr > 1 1021 yr 22.3 min

a SF b


234

24.10 d

b


235 236

7.1 min 37.5 min

b
b


a 7.32 (40%) 7.29 (60%) a 7.17 (81%) 7.00 (19%) g 0.177 a 6.478 (43%) 6.441 (15%) g 0.321 a 6.335 (79%) 6.225 (19%) g 0.1113 a 6.038 (25%) 5.978 (23%) g 0.236 a 5.423 (72.7%) 5.341 (26.7%) g 0.084 a 4.901 (11%) 4.845 (56%) g 0.194 a 4.687 (76.3%) 4.621 (23.4%) g 0.068 b
0.302 g 0.084 a 4.016 (77%) 3.957 (23%) b
1.23 g 0.086 b
0.198 g 0.093

237 238

5.0 min 9.4 min

b
b


g 0.111

208 229 231 230

U daughter Pa(p,a3n) U daughter

nature nature 233

U daughter

nature nature Th(n,g) nature

230

232

Th(n,g)

nature 238

U(n,a) U(g,2p) 238 U(p,3p) 18 O þ 238U 18 O þ 238U 238

Nuclear properties of protactinium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

212 213 214

5.1 ms 5.3 ms 17 ms

a a a

a 8.270 a 8.236 a 8.116

182

W(35Cl,5n) Er(51V,8n) 170 Er(51V,7n) 170

3452 Nuclear properties of protactinium isotopes. (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

a a a a a a a a a

223

6 ms

a

224 225

0.9 s 1.8 s

a a

226

1.8 min

227

38.3 min

a 74% EC 26% a 85% EC 15%

228

22 h

EC 98% a 2%

229

1.5 d

230

17.7 d

231

3.28 104 yr

EC 99.5% a 0.48% EC 90% b– 10% a 3.2 10–3% a

232

1.31 d

b–

233

27.0 d

b–

234

6.75 h

b–

234 m

1.175 min

235

24.2 min

b– 99.87% IT 0.13% b–

a 8.170 a 7.865 a 8.340 a 10.160 a 9.614 (65%) a 9.900 a 9.15 a 9.080 a 8.54 (30%) 8.18 (50%) a 8.20 (45%) 8.01 (55%) a 7.49 a 7.25 (70%) 7.20 (30%) a 6.86 (52%) 6.82 (46%) a 6.466 (51%) 6.416 (15%) g 0.065 a 6.105 (12%) 6.078 (21%) g 0.410 a 5.669 (19%) 5.579 (37%) a 5.345 b– 0.51 g 0.952 a 5.012 (25%) 4.951 (23%) g 0.300 b– 1.29 g 0.969 b– 0.568 g 0.312 b– 1.2 g 0.570 b– 2.29 g 1.001 b– 1.41

181

218 219 220 221 222

14 ms 0.2 s 4.9 ms 1.6 ms 0.12 ms 53 ns 0.78 ms 5.9 ms 5.7 ms

236

9.1 min

b–

237

8.7 min

b–

238

2.3 min

b–

239

106 min

b–

215 216 217

b– 3.1 g 0.642 b– 2.3 g 0.854 b– 2.9 g 1.014

Ta(40Ar,6n) Au(24Mg,5n) 181 Ta(40Ar,4n) 197

206

Pb(16O,4n) Pb(19F,4n) 204 Pb(19F,3n) 209 Bi(16O,4n) 209 Bi(16O,3n) 206 Pb(19F,3n) 208 Pb(19F,4n) 205 Tl(22Ne,4n) 208 Pb(19F,3n) 232 Th(p,8n) 209 Bi(22Ne,a2n) 232 Th(p,7n) 204

232

Th(p,6n)

232

Th(p,5n) Th(p,3n)

230 230

Th(d,3n) Th(d,2n) 230 Th(d,2n) 232 Th(p,3n) 229

nature 231

Pa(n,g) Th(d,2n) 233 Th daughter 237 Np daughter nature 232

nature 235

Th daughter U(n,p) 236 U(n,p) 238 U(d,a) 238 U(g,p) 238 U(n,pn) 238 U(n,p) 235

18

O þ 238U

3453 Nuclear properties of uranium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

217 218 219 222 223 224 225 226 227

16 ms 1.5 ms 42 ms 1.0 ms 18 ms 0.9 ms 59 ms 0.35 s 1.1 min

a a a a a a a a a

a 8.005 a 8.625 a 8.680 a 9.500 a 8.780 a 8.470 a 7.879 a 7.430 a 6.87

182

228

9.1 min

a  95% EC 5%

229

58 min

EC  80% a  20%

230

20.8 d

a

231

4.2 d

232

68.9 yr  8 1013 yr

EC > 99% a 5.5 10
3% a SF

233

1.592 105 yr 1.2 1017 yr

a SF

234

2.455 105 yr 2 1016 yr 7.038 108 yr 3.5 1017 yr

a SF a SF

a 6.68 (70%) 6.60 (29%) g 0.152 a 6.360 (64%) 6.332 (20%) g 0.123 a 5.888 (67.5%) 5.818 (31.9%) g 0.072 a 5.46 g 0.084 a 5.320 (68.6%) 5.264 (31.2%) g 0.058 a 4.824 (82.7%) 4.783 (14.9%) g 0.097 a 4.777 (72%) 4.723 (28%) a 4.397 (57%) 4.367 (18%) g 0.186

25 min 2.3415 107 yr 2.43 1016 yr 6.75 d

IT a SF b


239

4.468 109 yr 8.30 1015 yr 23.45 min

a SF b


240

14.1 h

b


242

16.8 min

b


235 235 m 236 237 238

a 4.494 (74%) 4.445 (26%) b
0.519 g 0.060 a 4.196 (77%) 4.149 (23%) b
1.29 g 0.075 b
0.36 g 0.044 b
1.2 g 0.068

W(40Ar,5n) Au(27Al,6n) 197 Au(27Al,5n) W(40Ar,xn) 208 Pb(20Ne,5n) 208 Pb(20Ne,4n) 208 Pb(22Ne,5n) 232 Th(a,10n) 232 Th(a,9n) 208 Pb(22Ne,3n) 232 Th(a,8n) 197

230 232 230 231

Th(3He,4n) Th(a,7n) Pa daughter Pa(d,3n)

230

Th(a,3n) Pa(d,2n) 232 Th(a,4n) 231

233

Pa daughter

nature nature 239 235

Pu daughter U(n,g)

236

U(n,g) Pu daughter nature

241

238

U(n,g)

244

Pu daughter

244

Pu(n,2pn)

3454 Nuclear properties of neptunium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

226 227 228 229

31 ms 0.51 s 61.4 s 4.0 min

a 8.044 a 7.677

209

2.144 106 yr >1 1018 yr

EC, a EC, a EC, a a  50% EC 50% a > 99% EC 0.97% EC < 99% a > 1% EC EC < 99% a10–3% EC 99.95% bþ 0.05% EC > 99% a 1.6 10
3% b
50% EC 50% EC 87% b
13% a SF

230

4.6 min

231

48.8 min

232 233

14.7 min 36.2 min

234

4.4 d

235

396.1 d

236a

22.5 h

236a

1.54 105 yr

237 238

2.117 d

b


239

2.3565 d

b


240

1.032 h

b


240 m

7.22 min

b


241

13.9 min

b


242 g or m

5.5 min

b


242 g or m

2.2 min

b


243 244

1.85 min 2.29 min

b
b


a

Not known whether ground‐state nuclide or isomer.

a 6.890

Bi(22Ne,5n) Bi(22Ne,4n) 209 Bi(22Ne,3n) 233 U(p,5n) 209

a 6.66

233

a 6.28 g 0.371 g 0.327 a 5.54 g 0.312 g 1.559

233

a 5.022 (53%) 5.004 (24%) b
0.54 g 0.642 g 0.163

235

U(d,2n)

235

U(d,n)

235

U(d,n)

a 4.788 (51%) 4.770 (19%) g 0.086 b
1.29 g 0.984 b
0.72 g 0.106 b
2.09 g 0.566 b
2.05 g 0.555 b
1.31 g 0.175 b
2.7 g 0.786 b
2.7 g 0.736 g 0.288 g 0.681

237

U daughter Am daughter

U(p,4n)

U(d,4n) U(d,6n) 233 U(d,3n) 233 U(d,2n) 235 U(d,4n) 235 U(d,3n) 235

241 237

Np(n,g)

243

Am daughter U daughter 238 U(a,pn) 239

240

U daughter U(a, pn) 238 U(a,p) 244 Pu(n,p3n) 244 Pu(n,p2n) 242 Pu(n,p) 242 U daughter 238

136 136

Xe þ 238U Xe þ 238U

3455 Nuclear properties of plutonium isotopes. Mass number

Half‐life

228 229 230 231

1.1 s – 2.6 min 8.6 min

232

33.1 min

233

20.9 min

234

8.8 h

235

25.3 min

236

2.858 yr 1.5 109 yr 45.2 d

237 238

Mode of decay

Main radiations (MeV)

Method of production

a a EC, a EC 90% a 10% EC 80% a 20% EC 99.88% a 0.12% EC 94% a 6% EC > 99.99% a 3 10
3% a SF EC > 99.99% a 4.2 10
3%

a 7.772 a 7.460 a 7.055 a 6.72

198

a 6.600 (62%) 6.542 (38%) a 6.30 g 0.235 a 6.202 (68%) 6.151 (32%) a 5.85 g 0.049 a 5.768 (69%) 5.721 (31%) 5.356 (17.2%) 5.334 (43.5%) g 0.059 a 5.499 (70.9%) 5.457 (29.0%) a 5.157 (70.77%) 5.144 (17.11%) 5.106 (11.94%) g 0.129 a 5.168 (72.8%) 5.123 (27.1%) a 4.896 (83.2%) 4.853 (21.1%) b
0.021 g 0.149 a 4.902 (76.49%) 4.856 (23.48%) b
0.58 g 0.084 a 4.589 (81%) 4.546 (19%) b
0.878 (51%) g 0.327 (25.4%) b
0.15 (91%) g 0.224 (25%)

233

U(a,5n)

233

U(a,4n)

233

U(a,3n)

87.7 yr 4.77 1010 yr 2.411 104 yr 8 1015 yr

a SF a SF

6.561 103 yr 1.15 1011 yr 14.35 yr

a SF b
> 99.99% a 2.4 10
3%

3.75 105 yr 6.77 1010 yr 4.956 h

a SF b


245

8.08 107 yr 6.6 1010 yr 10.5 h

a 99.88% SF b


246

10.84 d

b


239

240 241

242 243 244

247

2.27 d




b

Pt(34S,4n) Pb(26Mg,4n) 208 Pb(26Mg,4n) 233 U(3He,5n) 207

235

U(a,4n) U(a,2n) 235 U(a,3n) 236 Np daughter 235 U(a,2n) 237 Np(d,2n) 233

242

Cm daughter Np daughter 239 Np daughter 238

multiple n capture multiple n capture

multiple n capture multiple n capture multiple n capture 244

Pu(n,g)

multiple n capture multiple n capture

3456 Nuclear properties of americium isotopes. Mass number 232 233 234 235 236

Half‐life

Mode of decay

237 238

1.63 h

239

11.9 h

240

50.8 h

EC > 99% a 1.9 10–4%

241

432.7 yr 1.15 1014 yr

a SF

242

16.01 h

242 m

141 yr 9.5 1011 yr

b
82.7% EC 17.3% IT 99.5% SF a (0.45%)

243

7.38 103 yr 2.0 1014 yr

a SF

244

10.1 h

b


244 m

26 min

245

2.05 h

b
> 99% EC 0.041% b


246a

25.0 min

b


246a

39 min

b


b
0.895 g 0.253 (6.1%) b
2.38 g 0.799 (25%) g 0.679 (52%)

247

24 min

b


g 0.285 (23%)

Not known whether ground‐state nuclide or isomer.

Method of production 230

1.4 min 3.2 min 2.6 min 15 min 4.4 min 3.7 min 1.22 h

a

SF isomer a EC EC EC EC EC > 99% a 0.025% EC > 99% a 1.0 10–4% EC > 99% a 0.010%

Main radiations (MeV ) a 6.780

a 6.042 g 0.280 (47%) a 5.94 g 0.963 (29%) a 5.776 (84%) 5.734 (13.8%) g 0.278 (15%) a 5.378 (87%) 5.337 (12%) g 0.988 (73%) a 5.486 (84%) 5.443 (13.1%) g 0.059 (35.7%) b
0.667 g 0.042 weak a 5.207 (89%) 5.141 (6.0%) g 0.0493 (41%) a 5.277 (88%) 5.234 (10.6%) g 0.075 (68%) b
0.387 g 0.746 (67%) b
1.50

Th(10B, 8n) U(6Li, 6n) 230 Th(10B, 6n) 238 Pu(1H, 4n) 235 U(6Li, 5n) 237 Np(6He, 4n) 237 Np(a, 4n) 237 Np(3He, 3n) 237 Np(a, 3n) 238

237 239 237 239

Np(a, 2n) Pu(d, 2n) Np(a, n) Pu(d, n)

241

Pu daughter multiple n capture

241

Am(n, g)

241

Am(n, g) Am(n, g)

241

multiple n capture 243

Am(n, g)

243

Am(n, g)

245

Pu daughter

246

Pu daughter

244

Pu(a, d) Pu(3He, p) 244 Pu(a, p) 244

3457 Nuclear properties of curium isotopes. Mass number

Half‐life

237 238

– 2.3 h

239 240

2.9 h 27 d 1.9 106 yr 32.8 d

241 242

Mode of decay

Main radiations (MeV)

Method of production

EC, a EC < 90% a > 10% EC a SF EC 99.0% a 1.0%

a 6.660 a 6.52

237

g 0.188 a 6.291 (71%) 6.248 (29%) a 5.939 (69%) 5.929 (18%) g 0.472 (71%) a 6.113 (74.0%) 6.070 (26.0%) a 5.785 (73.5%) 5.741 (10.6%) g 0.278 (14.0%) a 5.805 (76.7%) 5.764 (23.3%) a 5.362 (93.2%) 5.304 (5.0%) g 0.175 a 5.386 (79%) 5.343 (21%)

239

a 5.266 (14%) 4.869 (71%) g 0.402 (72%) a 5.078 (82%) 5.034 (18%) b
0.9 g 0.634 (1.5%)

multiple n capture

162.8 d 7.0 106 yr 29.1 yr

a SF a 99.76% EC 0.24%

18.10 yr 1.35 107 yr 8.5 103 yr

a SF a

246

4.76 103 yr 1.80 107 yr

247

1.56 107 yr

a SF b stable a

248

3.48 105 yr

249

64.15 min

a 91.61% SF 8.39% b


250 251

8.3 103 yr 16.8 min

SF b


243 244 245

b
1.42 g 0.543 (12%)

239

239 239

Np (6Li,6n) Pu(a,5n) Pu(a,4n) Pu(a,3n) Pu(a,2n)

239

Pu(a,n) Am daughter 242 Cm(n,g) 242

multiple n capture Am daughter multiple n capture

244

multiple n capture

multiple n capture 248

Cm(n,g)

multiple n capture Cm(n,g)

250

Nuclear properties of berkelium isotopes. Mass number

Half‐life

Mode of decay

238 240 241 242

2.4 min 4.8 min 4.6 min 7.0 min

EC EC EC EC

243

4.5 h

EC 99.85% a 0.15%

Main radiations (MeV)

Method of production 241

Am(a,7n) Th(14Ne,6n) 239 Pu(6Li,4n) 232 Th(14N,4n) 232 Th(15N,5n) 243 Am(a,4n) 232

g 0.2623 a 6.758 (15%) 6.574 (26%)

3458 Nuclear properties of berkelium isotopes. (Contd.) Mass number

Half‐life

244

4.35 h

EC > 99% a 6 10
3%

245

4.94 d

EC 99.88% a 0.12%

246 247

1.80 d 1.38 103 yr

EC a

248a

23.7 h

248a 249

> 9 yr 330 d

b
70% EC 30% decay not observed b
> 99% a 1.45 10
3%

250

3.217 h

b


251

55.6 min

b


a

Mode of decay

Main radiations (MeV) g 0.755 a 6.667 (50%) 6.625 (50%) g 0.218 a 6.349 (15.5%) 6.145 (18.3%) g 0.253 (31%) g 0.799 (61%) a 5.712 (17%) 5.532 (45%) g 0.084 (40%) b
0.86 g 0.551 a 5.417 (74.8%) 5.390 (16%) b
0.125 g 0.327 weak b
1.781 g 0.989 (45%) b
1.1 g 0.178

Method of production 243

Am(a,3n)

243

Am(a,2n)

243

Am(a,n) Cf daughter 244 Cm(a,p) 247

248

Cm(d,2n)

246

Cm(a,pn) multiple n capture

254

Es daughter Bk(n,g) 255 Es daughter 249

Not known whether ground‐state nuclide or isomer.

Nuclear properties of californium isotopes. Mass number

Half‐life

Mode of decay

239 240 241 242

39 s 1.1 min 3.8 min 3.5 min

a a a a

243

10.7 min

244

19.4 min

EC 86% a 14% a

245

43.6 min

246

35.7 h 2.0 103 yr

247

3.11 h

EC 70% a 30% a SF b stable EC 99.96% a 0.035%

Main radiations (MeV)

Method of production

a 7.63 a 7.59 a 7.335 a 7.385 (80%) 7.351 (20%) a 7.06

243

a 7.210 (75%) 7.168 (25%) a 7.137

244

a 6.758 (78%) 6.719 (22%) a 6.296 (95%) g 0.294 (1.0%)

Fm daughter U(12C,5n) 233 U(12C,4n) 233 U(12C,3n) 235 U(12C,5n) 235 U(12C,4n) 233

Cm(a,4n) U(12C,4n) 244 Cm(a,3n) 238 U(12C,5n) 244 Cm(a,2n) 246 Cm(a,4n) 236

246 244

Cm(a,3n) Cm(a,n)

3459 Nuclear properties of californium isotopes. (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

a 6.258 (80.0%) 6.217 (19.6%)

246

Cm(a,2n)

a 6.194 (2.2%) 5.812 (84.4%) g 0.388 (66%) a 6.031 (83%) 5.989 (17%) a 5.851 (27%) 5.677 (35%) a 6.118 (84%) 6.076 (15.8%) a 5.979 (95%) 5.921 (5%) a 5.834 (83%) 5.792 (17%)

249

Bk daughter

248

334 d 3.2 104 yr

249

351 yr 6.9 1010 yr

a SF b stable a SF

250 251

13.08 yr 1.7 104 yr 898 yr

a SF a

252

2.645 yr

253

17.81 d

254

60.5 d

255 256

1.4 h 12.3 min

a 96.91% SF 3.09% b 99.69% a 0.31% SF 99.69% a 0.31% b
SF

multiple n capture multiple n capture multiple n capture multiple n capture multiple n capture 254 254

Cf(n,g) Cf(t,p)

Nuclear properties of einsteinium isotopes. Mass number

Half‐life

241 242 243 244

8s 13.5 s 21 s 37 s

245

1.1 min

246

7.7 min

247

4.55 min

248

27 min

249

1.70 h

250a 250a

8.6 h 2.22 h

Mode of decay

Main radiations (MeV)

Method of production

a a a EC 96% a  4% EC 60% a 40% EC 90% a 10% EC  93% a  7% EC 99.7% a  0.3% EC 99.4% a 0.57% EC EC

a 8.11 a 7.92 a 7.89 a 7.57

245

a 7.73

Md daughter U(14N,5n) 233 U(15N,5n) 233 U(15N,4n) 237 Np(12C,5n) 237 Np(12C,4n) 233

a 7.35

241

a 7.32

241

a 6.87 g 0.551 a 6.770 g 0.380 g 0.829 g 0.989

Am(12C,a3n)

Am(12C,a2n) U(14N,5n) 249 Cf(d,3n) 238

249

Cf(d,2n)

249

Cf(d,n) Cf(d,n)

249

3460 Nuclear properties of einsteinium isotopes. (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

251

33 h

EC 99.5% a 0.49%

249

Bk(a,2n)

252

471.7 d

a 78% EC 22%

249

Bk(a,n)

253

20.47 d 6.3 105 yr

254 g

275.7 d > 2.5 107 yr

a SF b stable a SF

254 m

39.3 h > 1 105 yr

a 6.492 (81%) 6.463 (9%) g 0.177 a 6.632 (80%) 6.562 (13.6%) g 0.785 a 6.633 (89.8%) 6.592 (7.3%) g 0.389 a 6.429 (93.2%) 6.359 (2.4%) g 0.062 a 6.382 (75%) 6.357 (8%)

255

39.8 d

256a 256a

25.4 min 7.6 h

a

b
99.6% SF a 0.33% EC 0.08% b
92.0% a 8.0% SF 4 10–3% b
b


multiple n capture multiple n capture 253

a 6.300 (88%) 6.260 (10%)

Es (n,g)

multiple n capture 255 254

Es(n,g) Es(t,p)

Not known whether ground‐state nuclide or isomer.

Nuclear properties of fermium isotopes. Mass number

Half‐life

Mode of decay

242 243 244

0.8 ms 0.18 s 3.3 ms

SF a SF

245 246

4.2 s 1.1 s

247a

35 s

247a 248

9.2 s 36 s

249

2.6 min

a a 92% SF 8% a  50% EC 50% a a 99.9% SF 0.1% a

250

30 min

250 m

1.8 s

a SF 5.7 10–4% IT

Main radiations (MeV)

Method of production 204

a 8.546 a 8.15 a 8.24 a 7.93 ( 30%) 7.87 (70%) a 8.18 a 7.87 (80%) 7.83 (20%) a 7.53 a 7.43

Pb(40Ar,2n) Pb(40Ar,3n) 206 Pb(40Ar,2n) 233 U(16O,5n) 233 U(16O,4n) 235 U(16O,5n) 239 Pu(12C,5n) 239 Pu(12C,4n) 206

239 240 238

Pu(12C,4n) Pu(12C,4n)

U(16O,5n) Cf(a,4n) 249 Cf(a,3n) 238 U(16O,4n) 249 Cf(a,3n) 249

3461 Nuclear properties of fermium isotopes. (Contd.) Mass number

Half‐life

251

5.30 h

252

25.39 h

253

3.0 d

254

3.240 h

255

20.07 h

256

2.63 h

257

100.5 d

258 259 260

0.37 ms 1.5 s 4 ms

a

Mode of decay

Main radiations (MeV)

Method of production

EC 98.2% a 1.8% a SF 2.3 10–3% EC 88% a 12%

a 6.834 (87%) 6.783 (4.8%) a 7.039 (84.0%) 6.998 (15.0%) a 6.943 (43%) 6.674 (23%) g 0.272 a 7.192 (85.0) 7.150 (14.2%) a 7.022 (93.4%) 6.963 (5.0%) a 6.915

249

Cf(a,2n)

249

Cf(a,n)

252

Cf(a,3n)

a > 99% SF 0.0592% a SF 2.4 10–5% SF 91.9% a 8.1% a 99.79% SF 0.21%

a 6.695 (3.5%) 6.520 (93.6%) g 0.241

SF SF SF

254m

Es daughter

255

Es daughter

256

Md daughter Es daughter multiple n capture

256

257

Fm(d,p) Fm(t,p) 260 Md decay product 257

Not known whether ground‐state nuclide or isomer.

Nuclear properties of mendelevium isotopes. Mass number 245

Half‐life

248

0.4 s 0.9 ms 1.0 s 1.12 s 0.27 s 7s

249

24 s

250

52 s

251

4.0 min

252

2.3 min

253 254a 254a 255

6 min 10 min 28 min 27 min

246 247

Mode of decay

Main radiations (MeV)

Method of production

a SF a a 80% SF EC  80% a  20% EC 80% a  20% EC 94% a 6% EC  94% a 6% EC > 50% a < 50% EC EC EC EC 92%

a 8.680

209

Bi(40Ar,4n)

a 8.740 a 8.424

209

Bi(40Ar,3n) Bi(40Ar,2n)

a 8.36 (25%) 8.32 (75%) a 8.03

241

a 7.830 (25%) 7.750 (75%) a 7.55

243

a 7.73

209

Am(12C,5n) Pu(14N,5n) 241 Am(12C,4n) 239

Am(12C,5n) Pu(15N,5n) 243 Am(12C,4n) 240 Pu(15N,4n) 243 Am(13C,4n) 240

238

U(19F,4n) Es(a,3n) 253 Es(a,3n) 253 Es(a,2n) 253

a 7.333

3462 Nuclear properties of mendelevium isotopes. (Contd.) Mass number

Half‐life

256

1.27 h

257

5.52 h

258a

51.5 d

258a 259 260

57.0 min 1.60 h 31.8 d

a

Mode of decay

Main radiations (MeV)

Method of production

a 8% EC 90.7% a 9.9% EC 90% a 10% a

g 0.453 a 7.205 (63%) 7.139 (16%) a 7.069

254

254

Es(a,n)

a 6.790 (28%) 6.716 (72%)

255

Es(a,n)

EC ? SF SF > 73% EC < 15%

253

Es(a,3n) Es(a,n)

255

Es(a,n) No daughter 254 Es(18O,12C) 259

Not know whether ground state nuclide or isomer.

Nuclear properties of nobelium isotopes. Mass number

Half‐life

Mode of decay

251

0.25 ms 39.2 ms 0.76 s

SF SF a

252

2.27 s

253

1.62 min

a 73% SF 27% a

a 8.68 (20%) 8.60 (80%) a 8.415 ( 75%) 8.372 ( 25%) a 8.01

254

51 s

a

a 8.086

254 m

0.28 s

IT

255

3.1 min

256

2.91 s

257

25 s

a 61.4% EC 38.6% a  99.7% SF  0.3% a

258 259

1.2 ms 58 min

260 262

106 ms 5 ms

250

SF a  75% EC  25% SF, a SF

Main radiations (MeV)

a 8.121 (46%) 8.077 (12%) a 8.43

Method of production 233

U(22Ne,5n)

244

Cm(12C,5n)

244

Cm(12C,4n) Pu(18O,5n) 246 Cm(12C,5n) 242 Pu(16O,5n) 246 Cm(12C,4n) 242 Pu(16O,4n) 246 Cm(12C,4n) 249 Cf(12C,a3n) 248 Cm(12C,5n) 249 Cf(12C,a2n) 248 Cm(12C,4n) 239

a 8.27 (26%) 8.22 (55%)

248

Cm(12C,3n)

248

a 7.551 (22%) 7.520 (25%)

248

Cm(13C,3n) Cm(18O,a3n)

254 262

Es(18O,x) Lr daughter

3463 Nuclear properties of lawrencium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

252 253 m 253 254 255

0.36 s 1.5 s 0.57 s 13 s 21.5 s

a a a a a, EC

256

256

25.9 s

a, EC

257

0.65 s

a, EC

258

3.9 s

a

259 260 261 262

6.2 s 3.0 min 39 min 3.6 h

a, SF a, EC SF SF, EC

a 9.018 (75%) a 8.722 a 8.794 a 8.460 (64%) a 8.43 (40%) 8.37 (60%) a 8.52 (19%) 8.43 (37%) a 8.86 (85%) 8.80 (15%) a 8.621 (25%) 8.595 (46%) a 8.45 a 8.03

Db daughter Db daughter 257 Db daughter 258 Db daughter 243 Am(16O,4n) 249 Cf(11B,5n) 243 Am(18O,5n) 249 Cf(11B,4n) 249 Cf(11B,3n) 249 Cf(14N,a2n) 248 Cm(15N,5n) 249 Cf(15N,a2n) 248 Cm(15N,4n) 248 Cm(15N,3n) 254 Es(22Ne,x) 254 Es(22Ne,x) 257

Nuclear properties of transactinide elements. Mass number

Half‐life

rutherfordium (Rf) 253  48 ms 254 22.3 ms 255 1.64 s 256 257

6 ms 4.7 s

258 259

12 ms 3.1 s

260 261

20 ms 75.5 s 4.2 s 2.1 s 47 ms

262

Mode of decay SF SF a 48% SF 52% SF, a a 80% SF 2% EC 18% SF a 93% SF 7% SF a a, SF SF SF

Main radiations (MeV)

Method of production 206

Pb(50Ti,3n) Pb(50Ti,2n) 207 Pb(50Ti,2n) 206

a 8.722 (94%) a 8.79 a 9.012 (18%) 8.977 (29%)

208

Pb(50Ti,2n) Pb(50Ti,n) 249 Cf(12C,4n) 208

246

a 8.87 (40%) 8.77 (60%) a 8.28 8.52

Cm(16O,4n) Cf(13C,3n) 248 Cm(16O,5n) 248 Cm(16O,4n) 248 Cm(18O,5n) 249

248

Cm(18O,4n)

3464 Nuclear properties of transactinide elements. (Contd.) Mass number

Half‐life

dubnium (Db) 256 1.6 s 257 1.5 s 257 m 0.76 s 258 4.4 s 259 260

0.51 s 1.5 s

261

1.8 s

262

34 s

263 268

27 s 16 h

seaborgium (Sg) 258 2.9 ms 259 0.48 s 260 3.6 ms 261 0.23 s 262 6.9 ms 263 265 266

0.9 s 0.3 s 7.4 s 21 s

Mode of decay

Main radiations (MeV)

Method of production

EC, a a, SF a, SF a

a 9.014 (67%) a 8.967, 9.074 9.163 a: 9.19 9.07 a 9.7 a: 9.082 (25%) 9.047 (48%)

209

a 8.93

243

a a  90% SF 9.6% EC 2.5% a  75% SF  25% a > 67% SF þ EC < 33% a, SF SF SF a a, SF a, SF a 22% SF > 78% a a a a

a 8.66 (20%) 8.45 (80%) a 8.36

Bi(50Ti,3n) Bi(50Ti,2n) 209 Bi(50Ti,2n) 262 Bh daughter 209

241

Am(22Ne,4n) Cf(15N,4n) 243 Am(22Ne,5n) 249

Am(22Ne,4n) Bk(16O,4n) 249 Bk(18O,5n) 249

249

Bk(18O,4n) 115 decay product 209

Bi(51V,2n) Pb(54Cr,3n) 208 Pb(54Cr,2n) 208 Pb(54Cr,n) 270 110 decay product

a 9.62 (78%) a 9.77 (83%) a 9.56 (60%)

208

a 9.06 (90%) a 9.25 a 8.84 (46%) a 8.77, 8.52

249

Cf(18O,4n)

248

Cm(22Ne,5n) Cm(22Ne,4n)

209

248

bohrium (Bh) 261 12 ms 262 0.1 s 8.0 ms 264 1.0 s 266 1 s 267 17 s 272 9.8 s

a a a a a a a

a 10.10 (40%) a 10.06, 9.91, 9.74 a 10.37, 10.24 a 9.48, 9.62 a 9.3 a 8.85 a 9.02

Bi(54Cr,2n) Bi(54Cr,n) 209 Bi(54Cr,n) 111 decay product 249 Bk(22Ne,5n) 249 Bk(22Ne,4n) 115 decay product

hassium (Hs) 264 0.26 ms 265 1.7 ms 0.8 ms

a, SF a a

a 10.43 a 10.30 (90%) a 10.57 (63%)

207

209

Pb(58Fe,n) Pb(58Fe,n) 208 Pb(58Fe,n) 208

3465 Nuclear properties of transactinide elements. (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

266 267 269 270

2.3 ms 59 ms 14 s 4 s

a a a a

a 10.18 a 9.88, 9.83, 9.75 a 9.23, 9.17

270

meitnerium (Mt) 266 1.7 ms 268 42 ms 276 0.72 s

a a a

a 10.46, 11.74 a 10.10, 10.24 a 9.71

209

darmstadtium (Ds) 267 3.1 ms 269 0.17 ms 270 0.10 ms 6.0 ms 271 56 ms 1.1 ms 273 0.15 ms 280 7.6 s

a a a a a a a SF

a 11.6 a 11.11 a 11.03 a 12.15 a 10.71 a 10.74, 10.68 a 11.08

209

roentgenium (Rg) 272 1.6 ms 280 3.6 s

a a

a 11.0 a 9.75

209

element 112 277 0.6 ms 283 3 min

a a, SF

a 11.65, 11.45

208

284

a

a 9.15

Pb(70Zn,n) U(48Ca,3n); 114 daughter 114 daughter

element 113 284 0.48 s

a

a 10.00

115 daughter

element 114 287 5s 288 2.6 s

a a

a 10.29 a 9.82

242 244

Pu(48Ca,3n) Pu(48Ca,4n)

element 115 288 87 ms

a

a 10.46

243

Am(48Ca,3n)

element 116 292 53 ms

a

a 10.53

248

Cm(48Ca,4n)

0.75 min

110 daughter 110 daughter 112 decay product 248 Cm(26Mg,4n) 271

Bi(58Fe,n) 111 daughter 115 decay product

Bi(59Co,n) Pb(62Ni,n) 207 Pb(64Ni,n) 207 Pb(64Ni,n) 208 Pb(64Ni,n) 208

112 daughter 114 decay product Bi(64Ni,n) 115 decay product

238

3466 Specific activities of actinide and transactinide nuclides. Major decay modea

Half‐life

209 210 211 212 213 214 215 216 216 m 217 218 219 220 221 222 222 m 223 224 225 226 227 228 229 230 231 232 233 234

a a a a a a a a a a a a a a a a a a a a a a EC a b
b
b
b
b
b
b
b
b


33 ms 22 ms 22 ms 95 ms 25 ms 0.10 s 0.35 s 0.25 s 0.93 s 0.80 s 8.2 s 0.17 s  0.33 ms 0.33 ms 69 ns 1.08 ms 11.8 ms 26.4 ms 52 ms 5.0 s 63 s 2.10 min 2.78 h 10.0 d 29.37 h 21.772 yr 6.15 h 62.7 min 122 s 7.5 min 119 s 145 s 44 s

209 210 211 212 213 214 215 216 217 218 219 220 221

a a a a a a a a a a a a a

3.8 ms 9 ms 37 ms 30 ms 140 ms 100 ms 1.2 s 28 ms 0.237 ms 0.109 ms 1.05 ms 9.7 ms 1.68 ms

Nuclide Ac

206 207 208

Th

b

Sc (dis min–1 mg–1) 3.68 1018 5.50 1018 5.50 1018 1.27 1018 4.82 1018 1.20 1018 3.41 1017 4.75 1017 1.27 1017 1.47 1017 1.43 1016 6.85 1017 3.51 1020 3.51 1020 1.67 1024 1.06 1023 9.69 1021 4.31 1018 2.18 1018 2.26 1016 1.79 1015 8.91 1014 1.12 1013 1.29 1011 1.048 1012 1.6058 108 4.96 1012 2.91 1013 8.92 1014 2.41 1014 9.67 1014 7.41 1014 2.43 1015 3.15 1019 1.3 1019 3.21 1018 3.94 1018 8.40 1017 1.17 1018 9.71 1016 4.14 1018 4.87 1020 1.05 1024 1.09 1023 1.17 1022 6.75 1019

Sd (Ci g–1)

5.80 104 72.332

3467 Specific activities of actinide and transactinide nuclides. (Contd.) Major decay modea

Half‐life

Sc (dis min
1 mg
1)

222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238

a a a a a a a a a b
a b
b
b
b
b
b


2.8 ms 0.60 s 1.05 s 8.0 min 30.57 min 18.68 d 1.9116 yr 7.340 103 yr 7.538 104 yr 25.52 h 1.405 1010 yr 22.3 min 24.10 d 7.1 min 37.5 min 5.0 min 9.4 min

4.03 1019 1.87 1017 1.06 1017 2.32 1014 6.042 1013 6.836 1010 1.8208 109 4.721 105 4.577 104 1.180 1012 0.2435 8.03 1013 5.140 1010 2.50 1014 4.72 1013 3.52 1014 1.87 1014

212 213 214 215 216 217 g 217 m 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 234m 235 236 237

a a a a a a a a a a a a a a a a a EC EC EC a b
b
b
b
b
b
b


5.1 ms 5.3 ms 17 ms 14 ms 0.2 s 3.8 ms 1.08 ms 0.12 ms 53 ns 0.78 ms 5.9 ms 2.9 ms 5.1 ms 0.79 s 1.7 s 1.8 min 38.3 min 22 h 1.50 d 17.4 d 3.276 104 yr 1.31 d 26.967 d 6.70 h 1.17 min 24.5 min 9.1 min 8.7 min

2.32 1019 2.22 1019 6.88 1018 8.32 1018 5.8 1017 3.04 1019 1.07 1020 9.57 1020 2.16 1024 1.46 1023 1.92 1022 3.89 1019 2.20 1019 1.42 1017 6.55 1016 1.03 1015 4.80 1013 1.39 1012 8.44 1011 7.24 1010 1.049 105 9.54 1011 4.6129 1010 4.44 1012 1.52 1015 7.25 1013 1.94 1014 2.02 1014

Nuclide

Pa

b

Sd (Ci g
1)

820.20 0.2127 0.02062 1.097 10–7

0.04724 2.0779 104

3468 Specific activities of actinide and transactinide nuclides. (Contd.) Major decay modea

Nuclide

U

Np




Half‐life

b

Sc (dis min
1 mg
1)

Sd (Ci g
1)

7.62 1014 1.64 1013

238 239

b b


2.3 min 106 min

217 218 219 222 223 224 225 226 227 228 229 230 231 232 233 234 235 235 m 236 237 238 239 240 242

a a a a a a a a a a EC a EC a a a a IT a b
a b
b
b


16 ms 1.5 ms 42 ms 1.0 ms 18 ms 0.9 ms 59 ms 0.35 s 1.1 min 9.1 min 58 min 20.8 d 4.2 d 68.9 yr 1.592 105 yr 2.455 105 yr 7.038 108 yr 25 min 2.3415 107 yr 6.75 d 4.468 109 yr 23.45 min 14.1 h 16.8 min

7.21 1018 7.66 1019 2.72 1021 1.13 1023 6.24 1021 1.2 1020 1.89 1018 3.17 1017 1.67 1015 2.01 1014 3.14 1013 6.06 1010 2.99 1011 4.96 107 2.139 104 1.381 104 4.798 7.10 1013 1.4361 102 1.81 1011 0.7462 7.447 1013 2.06 1012 1.03 1014

226 227 228 229 230 231 232 233 234 235 236 236 237 238 239 240 240 m 241 242

EC, a EC, a EC, a a a EC EC EC EC EC EC, b
EC a b
b
b
b
b
b


31 ms 0.51 s 61.4 s 4.0 min 4.6 min 48.8 min 14.7 min 36.2 min 4.4 d 396.1 d 22.5 h 1.54 105 yr 2.144 106 yr 2.117 d 2.3565 d 1.032 h 7.22 min 13.9 min 5.5 min

3.57 1018 2.16 1017 1.79 1015 4.56 1014 3.94 1014 3.70 1013 1.22 1014 4.95 1013 2.82 1011 3.114 109 1.31 1012 2.18 104 1.562 103 5.752 1011 5.1461 1011 2.808 1013 2.41 1014 1.25 1014 3.14 1014

22.4 9.724 10–3 6.223 10–3 2.161 10–6 3.20 107 6.4687 10–5 3.361 10–7

7.035 10–4

3469 Specific activities of actinide and transactinide nuclides. (Contd.) Major decay modea

Nuclide

Pu

Am

Cm




Half‐life

b

Sc (dis min
1 mg
1)

Sd (Ci g
1)

7.83 1014 9.28 1014 7.47 1014

242 243 244

b b
b


2.2 min 1.85 min 2.29 min

228 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247

a EC, a EC, a EC EC EC EC a EC a a a b
a b
a b
b
b


1.1 s 2.6 min 8.6 min 33.1 min 20.9 min 8.8 h 25.3 min 2.858 yr 45.2 d 87.7 yr 2.411 104 yr 6.564 103 yr 14.35 yr 3.733 105 yr 4.956 h 8.08 107 yr 10.5 h 10.84 d 2.27 d

1.0 1017 6.98 1014 2.10 1014 5.44 1013 8.57 1013 3.38 1012 7.02 1013 1.177 109 2.71 1010 3.80 107 1.377 105 5.037 105 2.295 108 8.784 103 5.776 1012 4.02 101 2.70 1012 1.087 1011 5.17 1011

232 233 234 235 236 236 237 238 239 240 241 242 242 m 243 244 244 m 245 246 246 247

EC EC, a EC, a EC, a EC, a EC EC EC EC EC a b– IT a b– b– b– b– b– b–

1.32 min 3.2 min 2.32 min 10.3 min 3.6 min 2.9 min 1.22 h 1.63 h 11.9 h 50.8 h 432.2 yr 16.02 h 141 yr 7.37 103 yr 10.1 h 26 min 2.05 h 25.0 min 39 min 23.0 min

1.36 1015 5.60 1014 7.69 1014 1.72 1014 4.91 1014 6.10 1014 2.41 1013 1.79 1013 2.45 1012 5.71 1011 7.618 106 1.794 1012 2.33 107 4.43 105 2.82 1012 6.58 1013 1.38 1013 6.79 1013 4.35 1013 7.35 1013

238 239

EC EC

2.3 h 2.9 h

1.27 1013 1.00 1013

17.1 0.06203 0.2269 103.4 3.957 10–3 1.81 10–5

3.432 0.1996

3470 Specific activities of actinide and transactinide nuclides. (Contd.)

Half‐life

240 241 242 243 244 245 246 247 248 249 250 251

a EC a a a a a a a b
SF b


27 d 32.8 d 162.8 d 29.1 yr 18.10 yr 8.5 103 yr 4.76 103 yr 1.56 107 yr 3.48 105 yr 64.15 min 8.3 103 yr 16.8 min

4.47 1010 3.67 1010 7.356 109 1.12 108 1.797 108 3.81 105 6.78 105 2.06 102 9.19 103 2.613 1013 3.82 105 9.10 1013

238 240 241 242 243 244 245 246 247 248 248

2.4 min 4.8 min 4.6 min 7.0 min 4.5 h 4.35 h 4.94 d 1.80 d 1.38 103 yr 23.7 h >9 yr

7.31 1014 3.62 1014 3.8 1014 2.46 1014 6.36 1012 6.55 1012 2.39 1011 6.55 1011 2.33 106 1.18 1012 < 3.6 108

249 250 251

EC EC EC EC EC EC EC EC a b– decay not observed b– b– b–

330 d 3.217 h 55.6 min

3.53 109 8.648 1012 2.99 1013

237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254

EC, SF EC, SF a a a a EC a EC a EC a a a a a b
SF

2.1 s 21 ms 39 s 1.06 min 3.8 min 3.7 min 10.7 min 19.4 min 45.0 min 35.7 h 3.11 h 333.5 d 351 yr 13.08 yr 898 yr 2.645 yr 17.81 d 60.5 d

5.03 1016 5.01 1018 2.69 1015 1.64 1015 4.56 1014 4.66 1014 1.61 1014 8.82 1013 3.79 1013 7.92 1011 9.05 1012 3.504 109 9.08 106 2.426 108 3.52 106 1.190 109 6.431 1010 1.89 1010

Nuclide

Bk

Cf

Sc (dis min
1 mg
1)

Major decay modea

b

Sd (Ci g
1)

3.314 103 50.5 80.93 0.172 0.305 9.28 10–5 4.14 10–3

1.05

1.59 103

4.09 109.3 1.59 536.2

3471 Specific activities of actinide and transactinide nuclides. (Contd.) Major decay modea

Nuclide

Es

Fm

Md




Half‐life

b

Sc (dis min
1 mg
1)

255 256

b SF

1.4 h 12.3 min

1.95 1013 1.33 1014

241 242 243 244 245 246 247 248 249 250a 250a 251 252 253 254 g 254 m 255 256 256

a a a EC EC EC EC EC EC EC EC EC a a a b
b
b
b


8s 13.5 s 21 s 37 s 1.1 min 7.7 min 4.55 min 27 min 1.70 h 8.6 h 2.22 h 33 h 471.7 d 20.47 d 275.7 d 39.3 h 39.8 d 25.4 min 7.6 h

1.3 1016 7.66 1015 4.91 1015 2.77 1015 1.55 1015 2.20 1014 3.71 1014 6.23 1013 1.64 1013 3.24 1012 1.25 1013 8.40 1011 2.438 109 5.596 1010 4.138 109 6.97 1011 2.86 1010 6.42 1013 3.57 1012

242 243 244 245 246 247 247 248 249 250 250 m 251 252 253 254 255 256 257 258 259 260

SF a SF a a a a a a a IT EC a EC a a SF a SF SF SF

0.8 ms 0.18 s 3.3 ms 4.2 s 1.1 s 35 s 9.2 s 36 s 2.6 min 30 min 1.8 s 5.30 h 25.39 h 3.0 d 3.240 h 20.07 h 2.63 h 100.5 d 0.37 ms 1.5 s 4 ms

1.3 1020 5.72 1017 3.11 1019 2.43 1016 9.25 1016 2.90 1015 1.10 1016 2.80 1015 6.45 1014 5.56 1013 5.56 1016 5.23 1012 1.087 1012 3.82 1011 8.451 1012 1.359 1012 1.03 1013 1.122 1010 2.62 1020 6.44 1016 2.4 1019

245

a SF

0.4 s 0.9 ms

2.6 1017 1.14 1020

Sd (Ci g
1)

1.098 103 2.521 104 1.864 103 1.286 104

6.122 105 5.054 103

3472 Specific activities of actinide and transactinide nuclides. (Contd.) Sc (dis min
1 mg
1)

Major decay modea

Half‐life

246 247 248 249 250 251 252 253 254 254 255 256 257 258 258 259 260

a a EC EC EC EC EC EC EC EC EC EC EC a EC SF SF

1.0 s 1.12 s 7s 24 s 52 s 4.0 min 2.3 min 6 min 10 min 28 min 27 min 1.27 h 5.52 h 51.5 d 57.0 min 1.60 h 31.8 d

1.02 1017 9.05 1016 1.4 1016 4.19 1015 1.93 1015 4.16 1014 7.20 1014 2.8 1014 1.64 1014 5.87 1013 6.06 1013 2.14 1013 4.90 1012 2.18 1010 2.84 1013 1.68 1013 3.50 1010

250 251 252 253 254 254 m 255 256 257 258 259 260 262

SF SF a a a a IT a a a SF a SF, a SF

0.25 ms 39.2 ms 0.76 s 2.27 s 1.62 min 51 s 0.28 s 3.1 min 2.91 s 25 s 1.2 ms 58 min 106 ms 5 ms

4.01 1020 2.55 1018 1.25 1017 4.38 1016 1.02 1015 1.93 1015 3.52 1017 5.28 1014 3.36 1016 3.90 1015 8.09 1019 2.78 1013 9.08 1017 1.9 1019

Lr

252 253 m 253 254 255 256 257 258 259 260 261 262

a a a a a, EC a, EC a, EC a a, SF a, EC SF SF, EC

0.36 s 1.5 s 0.57 s 13 s 21.5 s 25.9 s 0.65 s 3.9 s 6.2 s 3.0 min 39 min 3.6 h

2.76 1017 6.60 1016 1.74 1017 7.58 1015 4.57 1015 3.78 1015 1.50 1017 2.49 1016 1.56 1016 5.35 1014 4.10 1013 7.37 1012

Rf

253 254

SF SF

 48 ms 22.3 ms

 2.1 1021 4.42 1021

Nuclide

No

b

Sd (Ci g
1)

3473 Specific activities of actinide and transactinide nuclides. (Contd.)

Nuclide 255 256 257 258 259 260 261 262

Major decay modea

Half‐life

Sc (dis min
1 mg
1)

a SF, a a SF a SF a a, SF SF SF

1.64 s 6 ms 4.7 s 12 ms 3.1 s 20 ms 75.5 s 4.2 s 2.1 s 47 ms

5.99 1016 1.63 1019 2.07 1016 8.08 1018 3.12 1016 4.82 1018 1.271 1015 2.28 1016 4.55 1016 2.03 1018

b

Db

256 257 257 m 258 259 260 261 262 263 268

EC, a a, SF a, SF a a a a SF a, SF SF

1.6 s 1.5 s 0.76 s 4.4 s 0.51 s 1.5 s 1.8 s 34 s 27 s 16 h

6.11 1016 6.50 1016 1.28 1017 2.21 1016 1.90 1017 6.42 1016 5.33 1016 2.81 1015 3.53 1015 1.62 1012

Sg

258 259 260 261 262 263

SF a a a, SF SF a a a a

2.9 ms 0.48 s 3.6 ms 0.23 s 6.9 ms 0.9 s 0.3 s 7.4 s 21 s

3.35 1019 2.01 1017 2.67 1019 4.17 1017 1.38 1019 1.06 1017 3.2 1017 1.28 1016 4.48 1015

a a a a a a a

12 ms 0.1 s 8.0 ms 1.0 s 1 s 17 s 9.8 s

8.0 1018 9.6 1017 1.19 1019 9.5 1016 9.4 1016 5.52 1015 9.40 1015

a a a a a a a

0.26 ms 1.7 ms 0.8 ms 2.3 ms 59 ms 14 s 4 s

3.65 1020 5.56 1019 1.18 1020 4.09 1019 1.59 1018 6.65 1015 2.3 1016

265 266 Bh

261 262 264 266 267 272

Hs

264 265 266 267 269 270

Sd (Ci g
1)

3474 Specific activities of actinide and transactinide nuclides. (Contd.)

Nuclide

Major decay modea

Half‐life

b

Sc (dis min
1 mg
1)

Mt

266 268 276

a a a

1.7 ms 42 ms 0.72 s

5.54 1019 2.22 1018 1.26 1017

Ds

267 269 270

273 280

a a a a a a a SF

3.1 ms 0.17 ms 0.10 ms 6.0 ms 56 ms 1.1 ms 0.15 ms 7.6 s

3.02 1022 5.47 1020 9.27 1020 1.54 1019 1.65 1018 8.40 1019 6.11 1020 1.18 1016

Rg

272 280

a a

1.6 ms 3.6 s

5.75 1019 2.48 1016

112

277 283 284

a SF a

0.6 ms 3 min 0.75 min

1.51 1020 4.9 1014 1.96 1015

113

284

a

0.48 s

1.84 1017

114

287 288

a a

5s 2.6 s

1.7 1016 3.34 1016

115

288

a

87 ms

1.00 1018

116

292

a

53 ms

1.62 1018

271

Sd (Ci g
1)

a Decay modes are denoted by: a for alpha decay, b
for beta decay, EC for electron capture, IT for isomeric transition, and SF for spontaneous fission. The decay mode given in this column represents either the major decay mode or the only observed decay mode. b 1 year ¼ 365.243 days. c Specific activity is given in units of disintegrations per minute per microgram and contains one more significant figure than the half‐life in order to avoid rounding‐off errors. d For commonly used isotopes, specific activities are also given in units of Curies per gram. 1 Ci ¼ 2.22 1012 disintegrations per minute ¼ 3.7 1010 Bq.

SUBJECT INDEX Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440. Page numbers suffixed by t and f refer to Tables and Figures respectively.

AAS. See Atomic absorption spectrometry Ab initio model potentials (AIMP) for actinyl spectroscopic study, 1930 for electronic structure calculation, 1908 Absorption cross section, neutron scattering and, 2233 Absorption spectra of actinides, cyclopentadienyl complexes, 1955 of americium, 1364–1368 americium (III), 1364–1365, 1365f americium (IV), 1365 americium (V), 1366, 1367f americium (VI), 1366, 1367f americium (VII), 1367–1368, 1368f of berkelium, 1455 berkelium (III), 1444–1445, 1455, 1456f berkelium (IV), 1455 of californium, 1515–1516 californium (III), 2091, 2092f compounds, 1542–1545, 1544f halides, 1545 organometallic, 1541 in solution, 1557–1559, 1557t, 1558f, 1559t of curium curium (III), 1402–1404, 1404f curium (IV), 1402–1404, 1405f of einsteinium, 1600–1602, 1601f in borosilicate glass, 1601–1602, 1602f–1603f intensity of, 2089–2093 of liquid plutonium, 963 of neptunium, 763–766, 763f, 786–787 neptunium (VII) ternary oxides, 729 tetrafluoride, 2068, 2070f of neptunyl ion, aqueous solution, 2080, 2081f of plutonium hexafluoride, 1088, 1089f, 2084–2085, 2086f ions, 1113–1117, 1116t plutonium (IV), 849 polymerization, 1151, 1151f tetrachloride, 1093–1094, 1094f

tribromide, 1099t, 1100 trichloride, 1099, 1099t of plutonyl ion, aqueous solution, 2080, 2081f of protactinium protactinium (V), 212, 212f protactinium (V) sulfates, 216, 218f in solution, 1604–1605, 1604f of uranium bromide complexes, 496–497 halides, 442, 443f, 529, 557 hexachloride, 567 hexafluoride, 561 iodide complexes, 499 oxochloride, 526 pentavalent and complex halides, 501 pentavalent oxide fluorides and complexes, 521 tetrabromide, 495 tetrafluoride, 2068, 2069f trichloride, 447 trichloride hydrates, 449–450 trifluoride, 445 uranium (III), 2057–2058, 2057f, 2091, 2092f uranium oxobromo complexes, 573 uranium pentachloride, 523, 523f of uranium dioxide, 2276–2278, 2277f of uranium tetravalent halides, 482–483, 483f Absorption spectroscopy, resonance effects in, 2236 Accelerator mass spectrometry (AMS) applications of, 3318–3319 components of, 3316, 3317f development of, 3317–3318 for environmental actinides, 3059t, 3062–3063 fundamentals of, 3316–3318, 3317f historical development of, 3316 for mass spectrometry, 3310 of neptunium, 790 overview of, 3315–3316 problems of, 3329 requirements for, 3317

I-1

I-2

Subject Index Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440

Accelerator mass spectrometry (AMS) (Contd.) sensitivity of, 3316 TIMS v., 3329 for trace analysis, 3315–3319 Accelerator transmutation, of SNF, 1812 Accelerator transmutation of waste (ATW), overview of, 2693–2694 Acetates of actinide elements, 1796 of americium, 1322, 1323t coordination with, glycolate v., 590 of plutonium, 1177, 1180 structural chemistry of, 2439t–2440t, 2440–2445, 2444f of thorium, 114 properties of, 114 of uranium, 603–605, 604t Acetone derived compounds, of americium, 1322, 1323t, 1324 protactinium extraction with, 185 Acetonitrile, with uranium trichloride, 452 Acetylacetonates, of thorium, 115 Acetylacetones actinide complexes with, 1783 californium extraction with, 1513 SFE separation with, 2680 Acid decomposition, 3279–3281 acids for, 3280 description of, 3279–3280 systems for, 3280–3281 Acid leaching, for uranium ore, 305 limitations of, 306–307 Acid pugging, of uranium ore, 306 Acid redox speciation of americium (III), 3114t, 3115 of berkelium (IV/III), 3109–3110 of californium (III), 3110, 3114t, 3115 of curium (III), 3110, 3114t of environmental samples, 3100–3124 EXAFS, 3100–3103 monatomic An (III) and An (IV) ions, 3100–3118 triatomic An (V) and An (VI) ions, 3118–3124 of neptunium neptunium (III), 3111t–3112t, 3116–3117 neptunium (IV), 3106–3108, 3111t–3112t neptunyl (V), 3111t–3112t, 3121–3122 neptunyl (VI), 3111t–3112t, 3122–3123 of plutonium of plutonium (III), 3113t, 3117–3118 of plutonium (IV), 3108–3109, 3113t plutonyl (VI/V), 3113t, 3123–3124 of thorium (IV), 3103–3105, 3103t of uranium, 3100–3103, 3101t–3102t uranium (III), 3101t–3102t, 3116

uranium (IV), 3105–3106 uranyl (VI), 3101t–3102t, 3118–3121 Acidic extractants, for solvent extraction, 2650–2652, 2651f Acids for acid decomposition, 3280 for Purex process, 711 for solvent extraction, 839 uranium metal reactions with, 328 Actinide cations complexes of, 2577–2591 with inorganic ligands, 2578–2580, 2579t, 2581t with inorganic oxo ligands, 2580–2584, 2582t with organic ligands, 2584–2591, 2585t–2586t, 2588f, 2589t correlations in, 2567–2577 Gibbs energy, 2568–2570, 2568f–2569f ligand basicity, 2567–2568 hydration of, 2528–2544 in concentrated solution, 2536–2538, 2537f hexavalent, 2531–2532 in non-aqueous media, 2532–2533 overview, 2528 pentavalent, 2531–2532 tetravalent, 2530–2531 thermodynamic properties, 2538–2544, 2540t–2541t, 2542f, 2543t, 2544f trivalent, 2528–2530, 2529f, 2529t TRLF technique, 2534–2536, 2535f, 2535t–2536t hydrolysis of, 2545–2556, 2545f hexavalent, 2553–2556, 2554f–2555f, 2554t–2555t pentavalent, 2552–2553 tetravalent, 2547–2552, 2549t–2550t, 2551f–2552f trivalent, 2546, 2547f, 2547t–2548t inner v. outer sphere complexations, 2563–2566, 2566f, 2567t oxidation states of, 2525–2527, 2525f stability constants of, 2558–2559 correlations, 2567–2577 trivalent, 2562, 2563t Actinide chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Actinide chemistry actinide element properties, 1753–1830 biological behavior, 1813–1818 electronic structure, 1770–1773 environmental aspects, 1803–1813 experimental techniques, 1764–1769 metallic state, 1784–1790 oxidation states, 1774–1784 practical applications, 1825–1829 solid compounds, 1790–1803

Subject Index

I-3

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 sources of, 1755–1763 toxicology, 1818–1825 actinium, 18–44 applications of, 42–44 atomic properties of, 33–34 compounds of, 35–36 metallic state of, 34–35 nuclear properties of, 20–26 occurrence in nature of, 26–27 preparation and purification of, 27–33 solution and analytical chemistry of, 37–42 americium analytical chemistry and spectroscopy, 1364–1370 aqueous solution chemistry, 1324–1356 atomic properties, 1295–1297 compounds, 1302–1324 coordination chemistry and complexes, 1356–1364 history of, 1265 isotope production, 1267–1268 metal and alloys, 1297–1302 nuclear properties of, 1265–1267 separation and purification of, 1268–1295 in animals and man, 3339–3424 binding in bone, 3406–3412 in bone, 3400–3406 clearance from circulation, 3367–3387 initial distribution, 3340–3356 in liver, 3395–3400 tissue deposition kinetics, 3387–3395 transport in body fluids, 3356–3367 in vivo chelation, 3412–3423 berkelium analytical chemistry, 1483–1484 compounds, 1462–1472 free atom and ion properties, 1451–1457 history of, 1444–1445 ions in solution, 1472–1483 metallic state, 1457–1462 nuclear properties, availability, and applications, 1445–1447 production, 1448 separation and purification, 1448–1451 californium, 1499–1563 applications, 1505–1507 compounds, 1527–1545 electronic properties and structure, 1513–1517 gas-phase studies, 1559–1561 metallic state, 1517–1527 preparation and nuclear properties, 1502–1504 separation and purification, 1507–1513 solution chemistry, 1545–1559 complexation and kinetics in solution, 2524–2607 bonding, 2556–2563

cation hydration, 2528–2544 cation hydrolysis, 2545–2556 cation-cation complexes, 2593–2596 complexation reaction kinetics, 2602–2606 complexes, 2577–2591 correlations, 2566–2577 inner v. outer sphere, 2563–2566 redox reaction kinetics, 2597–2602 ternary complexes, 2591–2593 curium, 1397–1434 analytical chemistry of, 1432–1434 aqueous chemistry of, 1424–1432 atomic properties of, 1402–1406 compounds of, 1412–1424 history of, 1397–1398 metallic state of, 1410–1412 nuclear properties of, 1398–1400 production of, 1400–1402 separation and purification of, 1407–1410 einsteinium, 1577–1613 atomic and ionic radii, and promotion energies, 1612–1613 compounds, 1594–1612 electronic properties and structure, 1586–1588 metallic state, 1588–1594 nuclear properties, 1579–1583 production, 1579–1583 purification and isolation, 1583–1585 electronic structures of compounds of, 1893–1998 actinyl ions and oxo complexes, 1914–1933 halide complexes, 1933–1942 matrix-isolated, 1967–1991 organometallics, 1942–1967 relativistic approaches, 1902–1914 speciated ions, 1991–1992 unsupported metal-metal bonds, 1993–1994 environmental identification and speciation, 3013–3073 background, 3013–3021 combining and comparing analytical techniques, 3065–3071 sampling, handling, treatment, and separation, 3021–3024 specifics of, 3024–3065 fermium, 1622–1630 atomic properties of, 1626, 1627t isotopes of, 1622–1624, 1623t metallic state, 1626–1628 preparation and purification of, 1624–1625, 1625f solution chemistry, 1628–1630 handling, storage, and disposition, 3199–3266

I-4

Subject Index Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440

Actinide chemistry (Contd.) compound formation and properties, 3204–3215 disposition options, 3262–3266 hazard assessment, 3248–3259 hazard mitigation, 3259–3262 kinetic considerations, 3201–3204 plutonium compound reaction kinetics, 3215–3223 plutonium metal corrosion kinetics, 3223–3238 radiolytic reactions, 3246–3248 uranium compounds and metal corrosion kinetics, 3238–3246 lawrencium, 1641–1647 atomic properties, 1643–1644 isotopes, 1642 metallic state, 1644 preparation and purification, 1642–1643 solution chemistry, 1644–1647 magnetic properties, 2225–2295 5f0 compounds, 2239–2240 5f1 compounds, 2240–2247 5f2 compounds, 2247–2257 5f3 compounds, 2257–2261 5f4 compounds, 2261–2262 5f5 compounds, 2262–2263 5f6 compounds, 2263–2265 5f7 compounds, 2265–2268 5f8 compounds, 2268–2269 5f9 compounds, 2269–2271 5f10 compounds, 2271 5f11 compounds, 2271–2272 actinide dioxides, 2272–2294 mendelevium, 1630–1636 atomic properties, 1633–1634 isotopes, 1630–1631 metallic state, 1634–1635 preparation and purification, 1631–1633 solution chemistry, 1635–1636 metallic state and 5f-electron phenomena, 2307–2373 basic properties, 2313–2328 cohesion properties, 2368–2371 general observations, 2328–2333 magnetism, 2353–2368 overview of, 2309–2313 strong correlations, 2341–2350 strongly hybridized, 2333–2339 superconductivity, 2350–2353 weak correlations, 2339–2341 neptunium, 699–795 analytical chemistry and spectroscopic techniques, 782–795 in aqueous solution, 752–770 compounds of, 721–752 coordination complexes in solution, 771–782

history of, 699–700 isotope production, 702–703 metallic state of, 717–721 in nature, 703–704 nuclear properties of, 700–702 separation and purification, 704–717 nobelium, 1636–1641 atomic properties, 1639 isotopes, 1637–1638 metallic state, 1639 preparation and purification, 1638–1639 solution chemistry, 1639–1641 optical spectra and electronic structure, 2013–2103 divalent and high valence states, 2076–2089 modeling of crystal-field interaction, 2036–2056 modeling of free-ion interactions, 2020–2036 radiative and nonradiative electronic transitions, 2089–2103 relative energies of, 2016–2020 tetravalent spectra interpretation, 2064–2076 trivalent spectra interpretation, 2056–2064 organoactinide catalytic processes, 2911–3006 alkyne dimerization, 2930–2947 alkyne hydroamination, 2981–2990 alkyne oligomerization, 2923–2930 amine, silane reactions, 2978–2981 azide and hydrazine reduction, 2994–2996 heterogeneous, 2999–3006 intramolecular hydroamination, 2990–2993 olefin hydrogenation, 2996–2997 olefin hydrosilylation, 2953–2978 olefin polymerization, 2997–2999 reactivity, 2912–2923 terminal alkyne cross dimerization, 2947–2952, 2948f–2949f organoactinide chemistry, 2799–2894 bimetallic complexes, 2889–2893 carbon-based ancillary ligands, 2800–2867 heteroatom-based ancillary ligands, 2876–2889 heteroatom-containing ancillary ligands, 2868–2876 neutral carbon-based donor ligands, 2893–2894 plutonium atomic properties of, 857–862 compounds of, 987–1108 metal and intermetallic compounds of, 862–987

Subject Index

I-5

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 natural occurrence of, 822–824 nuclear properties of, 815–822 separation and purification of, 826–857 solution chemistry of, 1108–1203 protactinium, 161–232 analytical chemistry of, 223–231 atomic properties of, 189–191 metallic state of, 191–194 nuclear properties of, 164–170 occurrence in nature of, 170–171 preparation and purification of, 171–189 simple and complex compounds of, 194–209 solution chemistry of, 209–223 separation of, 2622–2769 applications, 2725–2767 future of, 2768–2769 historical development of, 2627–2631 systems for, 2631–2725 spectra and electronic structures of, 1836–1887 actinide parameters, 1864–1866 configuration summary, 1866–1872 einsteinium electrodeless lamps, 1885–1886 electronic structures, 1852–1860 empirical analysis, 1841–1852 experimental spectroscopy, 1838–1841 ionization potentials with laser spectroscopy, 1873–1875 ionization potentials with resonance ionization mass spectrometry, 1875–1879 laser spectroscopy, 1873 laser spectroscopy of super-deformed fission isomers, 1880–1884 new properties from, 1872–1873 radial parameters, 1862–1863 theoretical term structure, 1860–1862 structural chemistry of, 2380–2495 coordination compounds, 2436–2467 metals and inorganic compounds, 2384–2436 organoactinide compounds, 2467–2491 solid state structural techniques, 2381–2384 thermodynamic properties, 2113–2213 carbides, 2195–2198 chalcogenides, 2204–2205 complex halides, oxyhalides, and nitrohalides, 2179–2187 elements, 2115–2123 halides, 2157–2179 hydrides, 2187–2190 hydroxides and oxyhydrates, 2190–2195 ions in aqueous solutions, 2123–2133 ions in molten salts, 2133–2135 other binary compounds, 2205–2211

oxides and complex oxides, 2135–2157 pnictides, 2200–2204 thorium, 52–134 atomic spectroscopy of, 59–60 compounds of, 63–117 history of, 52–53 metal of, 60–63 nuclear properties of, 53–55 occurrence of, 55–56 processing and separation of, 56–59 solution chemistry of, 117–134 trace analysis, 3273–3330 atomic spectrometric techniques, 3307–3309 chemical procedures, 3278–3288 mass spectrometric techniques, 3309–3328 nuclear techniques, 3288–3307 transactinide elements and future elements, 1652–1739 elements 104–112 chemical property measurements, 1690–1721 elements 104–112 chemical property predictions, 1672–1689 elements beyond 112, 1722–1739 nuclear properties, 1661 one-atom-at-a-time chemistry, 1661–1666 relativistic effects on chemical properties, 1666–1671 transfermium elements, 1621–1622 uranium, 253–639 analytical chemistry of, 631–639 chemical bonding of, 575–578 compounds of, 328–575 free atom and ion properties, 318 history of, 253–639 metal of, 318–328 natural occurrence of, 257–302 nuclear properties of, 255–257 ore processing and separation, 302–317 organometallic and biochemistry of, 630–631 solution chemistry of, 590–630 structure and coordination chemistry of, 579–590 X-ray absorption spectroscopy, 3086–3184 future direction, 3183–3184 sorption studies, 3140–3183 terrestrial aquatic environment, 3095–3140 Actinide complexes, 2577–2591 bonding in, 2556–2563 coordination numbers, 2558–2560, 2559f covalent contribution to, 2561–2562, 2563t ionicity of f-element, 2556, 2557f steric effects in, 2560

I-6

Subject Index Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440

Actinide complexes (Contd.) strength of, 2560–2561 thermodynamics of, 2556–2557, 2558t cation-cation, 2593–2596, 2596f, 2596t complexation kinetics, 2602–2606, 2605f, 2606t americium, 2604–2605 Eigen mechanism, 2602–2603 multidentate ligands, 2603–2604 simple v. complex, 2602 trivalent complexes, 2605–2606, 2605f, 2606t fluorides, 2578 halides, 2578–2580, 2581t hexafluorides, 1933–1939 with inorganic ligands, 2578–2580, 2579t, 2581t with inorganic oxo ligands, 2580–2584, 2582t carbonates, 2583 complex, 2583–2584 nitrates, 2581 phosphates, 2583 sulfates, 2581–2582, 2582t with organic ligands, 2584–2591, 2585t–2586t, 2588f, 2589t carboxylates, 2584, 2585t–2586t, 2586–2587, 2590 catecholamine, 2590–2591 crown ether, 2590 fulvic acid, 2590–2591 humic acid, 2590–2591 hydroxypyridonate, 2590–2591 siderophores, 2590–2591 overview of, 2577 redox reaction kinetics, 2597–2602 An-O bond breakage, 2598–2600, 2599t complexation effect, 2601–2602, 2602t disproportionation reactions, 2600–2601, 2600t electron exchange reactions, 2597–2598 ternary, 2591–2593 hydrolytic behavior of, 2592–2593 modeling of, 2593 overview of, 2591–2592 use of, 2592–2593 Actinide compounds electronic structure of, 1893–1998 actinyl ions and oxo complexes, 1914–1933 actinyl complexes, 1920–1928 ‘bare’ species and ions in solids, 1928–1932 high oxidation oxygen species, 1932–1933, 1932t uranyl ion and related species, 1914–1920

halide complexes, 1933–1942 oxyhalides, 1939–1942 uranium hexafluoride and related complexes, 1933–1939 matrix-isolated, 1967–1991 binary carbonyls, 1984–1987 carbide oxides, 1976–1984 description of, 1968 developments of, 1969 dioxides, 1970–1976 nitride-oxides, 1989–1991 nitrides, 1987–1989 overview of, 1968–1970 organometallics, 1942–1967 actinocenes, 1943–1952 cyclopentadienyl complexes, 1952–1959 miscellaneous, 1965–1967 six- and seven-membered ring complexes, 1959–1962 uranium (III) complexes, 1962–1965 relativistic approaches, 1902–1914 double groups, 1910–1914 excited electronic states, 1909–1910 Hartree-Fock and density functional approaches, 1902–1904 RECPs, 1907–1909 relativistic effects, 1904–1907 speciated ions, 1991–1992 unsupported metal-metal bonds, 1993–1994 magnetic properties of, 2361–2362 thermodynamic properties of, 2113–2213 antimonides, 2197t, 2203–2204 arsenides, 2197t, 2203–2204 carbides, 2195–2198 chalcogenides, 2203t, 2204–2205 complex halides, 2179–2182 group IIA elements, 2205, 2206t–2207t group IIIA elements, 2205–2206, 2206t–2207t, 2208f group IVA elements, 2206–2208, 2206t–2207t halides, 2157–2179 hydrides, 2187–2190 nitrides, 2200–2203 nitrohalides, 2182–2185 oxides, 2192–2195 oxides and complex oxides, 2135–2157 oxyhalides, 2182–2187 oxyhydroxides, 2193–2195 phosphides, 2197t, 2203–2204 pnictides, 2200–2204 selenides, 2203t, 2204–2205 sulfides, 2203t, 2204, 2204f

Subject Index

I-7

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 tellurides, 2203t, 2204–2205 transition elements, 2208–2211 trihydroxides, 2190–2192 transition metal characteristics of, 2333–2334 Actinide concept history of, 3, 1754–1755 periodic table and, 10–11 Actinide-CU. See DIPEX resin Actinide elements, 1753–1830 absorption cross section of, 2233 atomic volumes of, 922–923, 923f biological behavior, 1813–1818 bioremediation, 1817–1818 in body fluids, 1814–1815 bone uptake, 1817 general considerations, 1813–1814 liver uptake, 1815–1816 in bone, 1817, 3400–3406 americium (III), 3403 binding of, 3406–3412 blood supply of, 3402 composition of, 3406 as deposition site, 3344–3445 neptunyl ion, 3404 plutonium (IV), 3403 retention of, 3404–3406 surfaces of, 3401–3402 uranyl ion, 3403 cyclopentadienyl complexes of, 1952–1959 3 ligands þ X, 1956–1957 4 ligands, 1953–1954 ‘base-free’ 3 ligands, 1954–1956, 1955f metal-metal bonds, 1958–1959 mixed ligands, 1957–1958 overview of, 1952–1953, 1953f structure of, 1953, 1953f definition of, 18 discovery of, 4, 5f–7f, 8–10 divalent, 2525–2526 electronic structures of, 2024, 2024t observed spectra of, 2077–2079 electronic structures of, 1770–1773, 1842t–1850t, 1851–1860, 1851f, 1894–1897, 1896f–1897f, 1896t–1897t crystal-field interaction, 2036–2056 determination of, 1858–1860, 1860f energies of, 1853–1858, 1854f, 1855t, 1856f, 1859f free-ion interactions, 2020–2036 general considerations, 1770 periodic table position, 1773, 1774f redox potentials v., 1859–1860, 1860f relative energies, 2016–2020 relativistic approaches for, 1902–1914 relativistic effects on, 1898–1900 spectroscopic studies, 1770–1771 structure, 1771–1773, 1772t, 1773f electrorecovery of, 2719–2721

elution of, 1625f entropy of, 2539, 2542f, 2543t in environment, 3013–3014, 3015f analytical techniques for, 3018–3020, 3019t anthropogenic, 3016 dispersal of, 3016–3017 mining, 3017 natural occurrence, 3014–3016, 3015f separation of, 3021 environmental aspects of, 1803–1813 in hydrosphere, 1807–1810 man-made, 1805–1807 of natural origin, 1804–1805 nuclear waste disposal, 1811–1813 overview of, 1803 sorption and mobility, 1810–1811 experimental techniques, 1764–1769 column partition chromatography, 1769 hazards, 1764–1765 ion-exchange chromatography, 1767–1768, 1768f liquid-liquid extraction, 1768–1769 long-lived nuclides, 1765–1766 tracer techniques, 1766 ultramicrochemical manipulation, 1767 extraction of DIDPA, 1276 HDEHP, 1275 organophosphorus and carbamoylphosphonate reagents, 1276–1278 reductive, 2719 stripping of, 1280–1281 TRPO, 1274–1275 f-d promotion energies of, 1560, 1561f, 1586–1588, 1587f ground state configuration of, 1895, 1897t heptavalent, 2527 hexavalent, 2527 cyclopentadienyl complexes, 2847–2851 energy levels, 2081–2082, 2083t, 2084f hydrolytic behavior of, 2553–2556, 2554f–2555f, 2554t–2555t observed spectra of, 2079–2085, 2080t stability constants of, 2571–2572, 2573f ionization potentials of by laser spectroscopy, 1873–1875, 1874t by RIMS, 1875–1879, 1877t, 1878f–1879f lanthanide elements v., 2, 10–11 atomic volume, 1578–1579, 1578f bonding in, 584–585 extraction from, 1286–1289, 1407 free-ion interaction and crystal-field strength, 2062–2064, 2063t ligand displacement series for, 2806 phonon energy relaxation, 2096

I-8

Subject Index Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440

Actinide elements (Contd.) relativistic effects on, 1898, 1899f separation from, 2635, 2635f lanthanide separation from, 2669–2677, 2757–2760 Cyanex 301, 2675–2676 dithiophosphinic acids, 2676 LIX–63, 2759–2760 process applications, 2670–2671 separation factors for, 2669–2670, 2670t soft-donor complexants for, 2670–2671, 2673 sulfur donor extractants, 2676–2677, 2677t TALSPEAK, 2671–2673, 2672f, 2760 TPTZ, 2673–2675, 2674t TRAMEX process, 2758–2759, 2759f laser spectroscopy of, 1873 ionization potentials by, 1873–1875, 1874t super-deformed fission isomers of americium, 1880–1884, 1881f, 1883f–1884f, 1883t ligand bonding of, 1900–1901 long-lived, 1763, 1764t lowest level of configurations of, 1841, 1842t–1850t magnetism in, 2354–2356 in mammalian tissues, 3339–3424 binding in bone, 3406–3412 bone, 3400–3406 liver, 3395–3400 matrix-isolated, 1967–1991 binary carbonyls, 1984–1987 carbide oxides, 1976–1984 description of, 1968 developments of, 1969 dioxides, 1970–1976 nitride-oxides, 1989–1991 nitrides, 1987–1989 overview of, 1968–1970 metallic state and 5f-electron phenomena of, 2307–2373 basic properties, 2313–2328 cohesion properties, 2368–2371 general observations, 2328–2333 magnetism, 2353–2368 overview of, 2309–2313 strong correlations, 2341–2350 strongly hybridized, 2333–2339 superconductivity, 2350–2353 weak correlations, 2339–2341 metallic state of, 1–2, 964, 1784–1790 crystal structure, 1785–1787, 1786t electronic structures, 1788–1789, 1789f polymorphic transformation, 1787 preparation, 1784–1785

properties of, 1786t superconductivity, 1789–1790 natural occurrence of, 1755–1756, 1804–1805, 3014–3016, 3273, 3274t–3275t, 3276 new properties of, 1872–1873 optical spectra and electronic structure of, 2013–2103 crystal-field interaction, 2036–2056 divalent, 2077–2079 free-ion interactions, 2020–2036 penta- and hexavalent, 2079–2085, 2080t tetravalent, 2064–2076 trivalent, 2056–2064 f orbital in, 1894–1895, 1896f, 1896t overview of, 1–2, 2f oxidation states, 1774–1784 complex-ion formation, 1782–1784 hydrolysis and polymerization, 1778–1782 ion types, 1777–1778, 1777t, 1779f, 1780t ions in aqueous solution, 1774–1776, 1775t parameters of, 1864–1866 least-squares fitted values, 1864–1865, 1864f radial integral comparisons, 1865, 1866 pentavalent, 2526–2527 circulation clearance of, 3376–3379 cyclopentadienyl complexes, 2845–2847 energy levels, 2081–2082, 2083t, 2084f hydrolytic behavior of, 2552–2553 initial distribution in mammalian tissues, 3350–3354 observed spectra of, 2079–2085, 2080t plutonium oxidation and reduction by ions of, 1133–1137, 1134t–1135t practical applications, 1825–1829 medical and other, 1828–1829 neutron sources, 1827–1828 nuclear power, 1826–1827 portable power sources, 1827 production of, 2729–2736 bismuth phosphate process, 2730 BUTEX process, 2731 CMPO, 2738–2752 DHDECMP, 2737–2738 DIDPA, 2753–2756 DMDBTDMA, 2756 extractant comparisons, 2763–2764, 2763t methods under development, 2760–2763 neptunium partitioning, 2756–2757 PUREX process, 2732–2733 REDOX process, 2730–2731 THOREX process, 2733–2736 TLA process, 2731–2732 trivalent actinide/lanthanide group separation, 2757–2760

Subject Index

I-9

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 TRPO, 2752–2753 around the world, 2764–2767 in pyroprocessing, 2694 quadrupole moments of, 1884, 1884f questions of, 14–15 separation of, rare earth metals, 2719, 2720t, 2721f six- and seven-membered ring complexes of, 1959–1962, 1961f solid compounds, 1790–1803 binary, 1790, 1791t–1795t crystal structure and ionic radii, 1798, 1799t introductory remarks, 1790 organoactinide, 1800–1803 other, 1796 oxides and nonstoichiometric systems, 1796–1798 sorption studies of, 1810–1811, 3140–3183 bacterial interactions, 3177–3183 carbonate incorporation, 3159–3164 iron-bearing mineral phases, 3164–3169 natural soil samples, 3171–3177 overview of, 3140, 3151 phosphates, 3169–3171 silicates, 3151–3158 sources of, 1755–1763 atomic weights, 1763 heavy-ion bombardment, 1761–1763 natural, 1755–1756 neutron irradiation, 1756–1761 spin-orbit coupling in, 1899–1900, 1899f structures of, 2369f, 2370–2371, 2371f superconductivity of, 1789–1790, 2239 synthesis of, 2630, 2631t systematics of, 10–13 tetravalent, 2526 circulation clearance of, 3376–3379 cyclopentadienyl complexes, 2814–2845 electronic structures of, 2024, 2024t energy levels, 2081–2082, 2083t, 2084f hydrolytic behavior of, 2547–2552, 2549t–2550t, 2551f–2552f initial distribution in mammalian tissues, 3350–3354 observed spectra of, 2064–2076 stability constants of, 2571–2572, 2573f thermodynamic properties of, 2113–2223 in aqueous solutions, 2123–2133, 2128t in condensed phase, 2115–2118, 2119t–2120t, 2121f in gas phase, 2118–2123, 2119t–2120t in molten salts, 2133–2135 toxicology, 1818–1825 ingestion and inhalation, 1818–1820 plutonium acute toxicity, 1820–1821 plutonium long-term effects, 1821–1822 removal of, 1822–1825

trivalent, 2526 circulation clearance of, 3370–3376 cyclopentadienyl complexes, 2800–2814 electronic structures of, 2024, 2024t energy levels of, 2032, 2033t hydrolytic behavior of, 2546, 2547f, 2547t–2548t initial distribution in mammalian tissues, 3341t–3347t, 3345–3350, 3348f observed spectra of, 2056–2064 stability constants of, 2571–2572, 2573f Wigner-Seitz radius of, 2310–2312, 2311f Actinide ions absorption cross section of, 2233 in aqueous phase, 2123–2133 electrode potentials, 2127–2131 enthalpy of formation, 2123–2125, 2124f–2125f entropies, 2125–2127 heat capacities, 2132–2133 EPR measurements of, 2226 for SFE, 2683–2684 speciated, 1991–1992, 1992f thermodynamic properties of in aqueous solutions, 2123–2133, 2128t in molten salts, 2133–2135 Actinide metals Bloch states in, 2316 cohesion properties of, 2368–2371 magnetism in, 2353–2368 electronic transport and, 2367–2368 exchange interactions and magnetic anisotropy, 2364–2366, 2365f–2366f general features of, 2353–2354 intermetallic compounds, 2356–2361 magnetic structures, 2366–2367 orbital moments, 2362–2364, 2363f other compounds, 2361–2362 in pure elements, 2354–2356 overview of, 2309–2313 crystal structure of, 2312–2313, 2312f electrical resistivity of, 2309, 2310f Wigner-Seitz radius of, 2310–2312, 2311f properties of, 2313, 2314t–2315t Brillouin zones, 2317–2318 complex and hybridized bands, 2318–2319, 2318f density functional theory, 2326–2328 density of states, 2318f, 2319 electrical resistivity, 2324 electron-electron correlations, 2325–2326 electronic heat capacity, 2323 Fermi energy and effective mass, 2319–2322 Fermi surface, 2322–2323 formation of energy bands, 2313–2317 one-electron band model, 2324–2325

I-10

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Actinide metals (Contd.) strongly hybridized 5f bands in, 2333–2339 Fermi surface measurements, 2334 photoemission measurement background, 2334–2336 strong correlations, 2341–2350 UIr3 PES, 2336–2339, 2337f weak correlations, 2339–2341 structural chemistry of, 2384–2388 actinium, 2385 americium, 2386–2387 berkelium, 2388 californium, 2388 curium, 2387–2388 einsteinium, 2388 neptunium, 2385–2386 overview, 2384–2385, 2384f plutonium, 2386, 2387f protactinium, 2385 thorium, 2385 uranium, 2385 superconductivity of, 2350–2353 Actinide oxides, structure of, 2390 Actinide oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Actinide phosphates, structural chemistry of, 2430–2433, 2431t–2432t Actinium applications of, 42–44 as geochemical tracer, 44 as heat sources, 42–43 as neutron sources, 43 for tumor radiotherapy, 43–44 atomic properties of, 33–34 compounds of, 35, 36t enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t half-life of, 20 heat capacity of, 2119t–2120t, 2121f history of, 19–20 ionization potentials of, 33, 1874t isotopes of, 18–19, 22t–23t, 31–32 lanthanide elements v., 2 lanthanum v., 18, 40 metallic state of, 34–35 structure of, 2385 nuclear properties of, 20–26 actinium–225, 22t–23t, 24f, 25–26 actinium–227, 20–24, 21f, 22t–23t, 25f–26f actinium–228, 22t–23t, 23f, 24–25 occurrence in nature of, 26–27, 162 origin of, 162 oxidation states of

in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t preparation and purification of, 27–33 gram quantities, 32–33 by ion-exchange chromatography, 30–32 purification of, 28–30 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f solution and analytical chemistry of, 37–42 complexation, 40, 41t radiocolloid formation, 41–42 redox behavior, 37–38 solubility, 38–40, 39t sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f from uranium–235, 42–44 Actinium (III) detection of, limits to, 3071t energy level structure of, 2058, 2059f hydration of, 2528–2530, 2529f, 2529t in mammalian tissues, circulation clearance of, 3368f, 3370–3371 Actinium (I), electron configurations of, 2018–2019, 2018f Actinium sesquioxide formation enthalpy of, 2143–2146, 2144t, 2145f structure of, 2390 Actinium trihalides, structural chemistry of, 2416, 2417t Actinium-225 as bismuth-231 generator, 44 decay series of, 24f, 25 identification of, 42 properties of, 22t–23t, 25–26 from protactinium–233, 171 in radiotherapy, 43–44, 1829 synthesis of, 28 actinium-227 decay series of, 20, 21f detection of limits to, 3071t αS, 3029 as geochemical tracer, 44 identification of, 20–24, 25f–26f, 42 from neutron irradiation, 1756 nuclear properties of, 3274t–3275t, 3298t occurrence in nature, 26–27 properties of, 20–24, 22t–23t from protactinium–231, 164, 166f purification of, 28–31, 29f, 31f gram quantities of, 32–33 synthesis of, 27 Actinium-228 decay series of, 23f, 24 identification of, 42

Subject Index

I-11

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 nuclear properties of, 3274t–3275t, 3298t properties of, 22t–23t, 24 purification of, 29, 29f synthesis of, 28 Actinocenes, 1943–1952 bonding in, 2853–2854, 2854f electronic configurations, ground states, and oxidation states of, 1946–1948 electronic transitions in, 1949–1952 protactinocene, 1949–1951 thorocene and uranocene, 1951–1952 geometric structures of, 1943–1944, 1944t, 1945f history of, 1943 metal-ring covalency, 1948–1949, 1948f optimized metal-ring distances, 1943, 1944t orbital interactions in, 1944–1945, 1946f Actinometer, history of, 626 Actinouranium (AcU). See Uranium–235 Actinyl ions complexes of, 1920–1928, 2578–2580, 2579t, 2581t aqua, 1921–1925 bidentate ligands, 1926–1928, 1928t chlorides, 2579–2580, 2581t hydroxide complexes, 1925–1926 oxyhalides, 1939–1942 compounds, structural chemistry of, 2399–2402 species and ions in solids, 1928–1932 structure of, 2085–2089 XAFS of, 2532 AcU. See Uranium–235 Adsorption behavior of californium, 1524 of fermium, 1628 of oxidation states, 3287 of protactinium, 176 of rutherfordium, 1696 Adsorption enthalpy of dubnium, 1705 of element 112, 1721 gas-phase chromatography for, 1663 of nobelium, 1705 of rutherfordium, 1693, 1694f of tantalum, 1705 transactinide predictions of, 1684 AE calculations. See All-electron calculations Aerosol release fraction (ARF) description of, 3252 plutonium release of, 3253 AES. See Atomic emission spectrometry; Auger electron spectroscopy Aging of plutonium, metal and intermetallic compounds, 979–987 AIMP. See Ab initio model potentials

Air plutonium hydrides reaction with, 3218 plutonium metal reaction with, 3225–3238, 3231–3232 uranium corrosion by, 3242–3245, 3243f, 3244t Air samples actinide handling in, 3021–3022 treatment of, 3022 Albumin, actinide distribution with, 3362–3363 Aliquat 336 actinium extraction with, 30 americium extraction with, 1293 curium extraction with, 1410 dubnium extraction with, 1705 fermium extraction with, 1624 neptunium extraction with, 714–715, 715f protactinium extraction with, 185–186 Alkali metals actinide oxides with, 2150–2153 enthalpy of formation, 2151 entropy, 2151, 2152t high-temperature properties, 2151–2153 cyclopentadienyl complexes with, 2844 neptunium (IV) ternary oxides, 730 neptunium (V) ternary oxides, 730 neptunium (VI) ternary oxides, 729–730 neptunium (VII) ternary oxides, 728–729 oxoplutonates of, preparation of, 1056–1057 for pyrochemical processes, 2692 with thorium molybdates, 112 with thorium sulfates, 104–105 uranates (V) and (IV) of, 380–382 crystal structures of, 381 non-stoichiometry in, 382–383 physicochemical properties of, 372t–378t, 381–382 preparation of, 381 uranates (VI) of, 371–380 non-stoichiometry in, 382–383 physicochemical properties of, 372t–378t, 380 preparation of, 371, 379 in uranium mixed halogeno-complexes, 575 with uranium selenites, 298–299 Alkaline earth metals actinide chelation v. sequestration of, 1823–1824 actinide oxides with, 2153–2157 enthalpy of formation, 2153–2156, 2154f, 2155t, 2156f entropy, 2155t, 2156–2157 high-temperature properties, 2157, 2158t mendelevium separation with, 1633 neptunium (IV) ternary oxides, 730 neptunium (V) ternary oxides, 730

I-12

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Alkaline earth metals (Contd.) neptunium (VI) ternary oxides, 729–730 neptunium (VII) ternary oxides, 728–729 nobelium v., 1639–1640 oxoplutonates of, preparation of, 1057–1059 for pyrochemical processes, 2692 uranates (V) and (IV) of, 380–382 crystal structures of, 381 non-stoichiometry in, 382–383 physicochemical properties of, 372t–378t, 381–382 preparation of, 381 uranates (VI) of, 371–380 non-stoichiometry in, 382–383 physicochemical properties of, 372t–378t, 380 preparation of, 371, 379 Alkaline solutions, actinide separations from, 852, 2667–2668 Alkane, activation of, 3002–3006, 3004t Alkenes, hydrosilylation of activity data for, 2970t kinetic studies of, 2972–2974 organoactinide complex promotion, 2969–2974 products of, 2971 Alkoxides, of plutonium, 1185–1186 Alkyl ligands, 2866–2867 complexation with, 2866–2867 cyclopentadienyl complexes with, tetravalent, 2539f, 2819–2820, 2820f, 2837–2839 of plutonium, 1186 preparation of, 2866 stabilization of, 2867 structure of, 2867, 2868f Alkylamines, fermium complexes with, 1629 Alkylphosphoric extraction of curium, 1407 for uranium leach recovery, 312–313 Alkylpyrocatechols, actinide separation with, 1408 Alkyne complexes, 2866 cross dimerization of, 2947–2952, 2948f–2949f dimerization of, 2930–2947 external amines in, 2943–2944 hydroamination and, 2944–2945 promotion of, 2938–2947, 2940f–2941f terminal, 2930–2935 terminal ansa-organothorium promotion, 2935–2937 hydroamination of, 2981–2990 kinetic studies, 2986–2990 rates of, 2985 regioselectivities, 2984

scope and mechanistic studies, 2981–2986 thermodynamics of, 2982–2984 hydrosilylation of active species formation, 2957–2961 alkyne:silane ratio, 2956 bridged complex promotion, 2964–2969 cationic complex promotion, 2974–2978 kinetic studies, 2957, 2965–2966 mechanism, 2961–2963 neutral organoactinide promotion, 2953–2964 with primary silanes, 2966–2969 scope at room temperature, 2953–2954 scope of catalysis at high temperature, 2954–2955 thermodynamics, 2963–2966 oligomerization of, 2923–2930 bisacetylide organoactinide, 2924–2925 cross, 2929–2930 key intermediate complex in, 2926, 2926f kinetic, thermodynamic, and thermochemical data in, 2926–2929 regioselective, 2945–2947 terminal, 2925–2926, 2928f stoichiometric reactions of, with pentamethyl-cyclopentadienyl and silanes, 2916–2918, 2917f Allanite, thorium in, 56t All-electron (AE) calculations, of uranyl, 1918 Allotropes of plutonium, 1, 877–890, 880f, 881t α phase, 879–882, 882f–884f, 884t β phase, 882, 882f–883f, 885t δ phase, 882–883, 882f–883f, 886f, 892–897, 899, 916–917 δ0 phase, 882f–883f, 883 e phase, 882f–883f, 883 γ phase, 882, 882f–883f transformations, 886–890, 888f–889f ζ phase, 882f–883f, 883, 890, 891f of uranium α-phase, 320–326, 328–339, 344 β-phase, 321–323, 325–326, 328–339, 344, 347 γ-phase, 321–323, 347 Alloys of americium, 1302, 1304t of berkelium, 1461–1462 of californium, 1526 of curium, 1411–1412, 1413t–1415t of einsteinium, 1592–1593 magnetic studies of, 2238 mechanical properties of, 972–973 of neptunium, 719–721 tellurium, 742 of plutonium, 862–987, 3213 aluminum, 894, 895f–896f, 919–920, 920f applications of, 862

Subject Index

I-13

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 α and β stabilizers, 897 δ field expansion, 892–897 electronic structure, theory, and modeling, 921–935 eutectic-forming elements, 897 gallium, 892–894, 893f–896f, 899, 916–917, 916f–917f, 917–919, 918f history of, 862 indium, 896, 896f interstitial compounds, 898 microsegregation in δ-phase alloys, 899, 916–917 nature of, 863 oxidation and corrosion, 973–979 phase transformations, 891–921 phase transformations in δ-phase alloys, 917–921 physical and thermodynamic properties of, 935–968 thallium, 896, 896f theory and modeling of, 925–929, 926f of protactinium, 194, 194t of thorium, 63 of uranium, 325–326, 325t Allyl ligands, 2865 Alpha decay actinium actinium–225, 25–26, 43–44 actinium–227, 20–23, 25f americium, 1265–1267, 1266t americium–241, 1267, 1337–1338 americium–243, 1337–1338 ARCA and measurement of, 1665 of bohrium, detection with, 1711 californium, californium–252, 1505 curium curium–242, 1432 curium–243, 1432 curium–244, 862, 1432 of dubnium detection with, 1705 dubnium–262, 1703–1704 einsteinium, einsteinium–253, 1594 element 112, 1719 of hassium, detection with, 1714 lawrencium, 1641 lawrencium–257, 1641–1642 lawrencium–258, 1642 neptunium, neptunium–237, 712, 782–785 nobelium, 1637 plutonium decay, 980 hexafluoride, 1090–1092 redox behavior of, 1143–1146, 1146t transmutation products from, 984–987, 985f protactinium, 164 protactinium–231, 164, 166, 167f, 224

protactinium–233, 162–163 in radioactive displacement principle, 162 rutherfordium, 1639 detection with, 1701 rutherfordium–261, 1698 of seaborgium, detection with, 1708 superactinide elements, 1735 uranium, uranium–232, 256 α-Phase of plutonium, 879–882, 882f–884f, 884t americium influence on, 985 atomic volume, 923, 923f density of, 936t, 937 diffusion rate, 958–960, 959t elastic constants, 942–943, 944t electrical resistivity of, 2309–2310, 2310f, 2345–2347, 2346f fine-grain plasticity, 968, 970–971, 970f ground state, 924 heat capacity, 947–949, 947f, 950t–951t, 952f lattice changes in, 981–982, 982f, 982t, 984 magnetic properties of, 2355 thermal conductivity, 957 thermal expansion, 938t, 939–942, 940f thermoelectric power, 957–958, 958t of uranium electrical properties of, 324 general properties of, 321–323, 322t–323t hydrogen system of, 328–339, 329t, 334f intermetallic compounds and alloys, 325–326, 325t magnetic susceptibility of, 323–324 β phase transformation of, 344 physical properties of, 320–321, 321f resistivity-temperature curve of, 324, 324f Alpha spectroscopy (αS) of actinium, 20–23, 25f advantages/disadvantages of, 3329 americium, 3295–3296 of americium, 1364 applications of, 3292–3296, 3294f curium, 3296 for environmental actinides, 3026t, 3029–3031, 3030f fundamentals of, 3291–3292, 3291f ICPMS v., 3329 βS and, 3070 of neptunium, 783–785, 3294–3295 overview of, 3289 performance of, 3292 of plutonium, 3295 of protactinium, 3294 protactinium–231, 224 of thorium, 133–134, 3293–3294 TIMS v., 3329 for trace analysis, 3289–3296

I-14

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Alpha spectroscopy (αS) (Contd.) tracers for, 3289–3291, 3290t uranium, 3293 bioassay with, 3293 α−α Correlation for rutherfordium identification, 1701–1702 for seaborgium identification, 1708 for transactinide identification, 1659, 1662 Alpha-spectrometers, multi-channel, for protactinium–231, 224 Aluminates, actinide adsorption on, 3158 Aluminum actinide compounds with, thermodynamic properties of, 2205–2206, 2206t–2207t for arene preparation, 2859 in curium complex, 1413t–1415t, 1422–1423 for neptunium halide preparation, 738 in plutonium alloy, 894, 895f–896f damage recovery of, 983–984, 983f δ-phase lattice, 930f, 932–933 elastic constants, 943, 944t heat capacity, 948 oxidation of, 976, 977t solubility ranges, 930, 930f transformation of, 919–920, 920f protactinium extraction with, 176–178, 177f uranium v., 318 Amberlite XAD–4, for actinide extraction, 715–716 Americium analytical chemistry and spectroscopy, 1364–1370 radioanalytical chemistry, 1364 spectroscopy, 1364–1370 aqueous solution chemistry, 1324–1356 complexation reactions, 1338–1356, 1339t oxidation states, 1324–1338 atomic properties, 1295–1297 atomic and ionic radii, 1295–1296 electron configuration, 1295 emission spectra, 1296 ionization potentials, 1296 Mo¨ssbauer spectrum, 1297 photoelectrom spectrum, 1296–1297 x-ray spectrum, 1296 in biological systems in bone, 1817 health hazard of, 1814 ingestion and inhalation of, 1818–1820 in liver, 1815–1816 in organs, 1815 complexes of cyclopentadienyl, 2803 tris-cyclopentadienyl, 2470–2476, 2472t–2473t compounds of, 1302–1324 acetate, 1322, 1323t

acetone, 1322, 1323t, 1324 arsenate, 1321 borides, 1321 carbides, 1305t–1312t, 1319 carbonates, 1305t–1312t, 1319 chalcogenides, 1305t–1312t, 1316–1319 chromates, 1321 cyclooctatetraene, 1323t, 1324 cyclopentadiene, 1323t, 1324 formate, 1322, 1323t halides, 1305t–1312t, 1314–1316 hydrides, 1305t–1312t, 1314 hydroxides, 1303, 1305t–1312t, 1313–1314 inorganic, 1303–1321, 1305t–1312t molybdate, 1321 organic, 1322–1324, 1323t oxalate, 1322, 1323t oxides, 1303, 1305t–1312t, 1313–1314 phosphates, 1305t–1312t, 1319–1321, 1355 pnictides, 1305t–1312t, 1316–1319 silicates, 1321 sulfates, 1305t–1312t, 1319–1321 tungstate, 1321 coordination chemistry and complexes, 1356–1364 inorganic ligands, 1356–1361 organic ligands, 1361–1364 discovery of, 5t, 8 enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f history of, 8, 1265 ionization potentials of, 1296, 1874t isotope production, 1267–1268 isotope shifts of, 1882–1884, 1883f, 1883t isotopes of, 9–10, 12, 1265–1267, 1266t lanthanide elements v., 2 laser spectroscopy of super-deformed fission isomers, 1880–1884, 1881f, 1883f–1884f, 1883t magnetic properties of, 2355–2356 metal and alloys, 1297–1302 metal preparation, 1297 properties of, 1297–1302, 1298t, 1301f metallic state of, structure of, 2386–2387 MSE oxidation of, 869 natural occurrence of, in marine organisms, 1809 nuclear properties of, 1265–1267 oxidation states of, 2526 in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t α-phase plutonium influence of, 985 in plutonium alloy δ-phase lattice, 930–931, 930f

Subject Index

I-15

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 neptunium v., 931, 931f solubility ranges, 930, 930f from plutonium decay, 985, 985f production of, 1758–1759 pyrochemical methods for, molten chlorides, 2699–2700 quadrupole moments of, 1884, 1884f reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f separation and purification of, 1268–1295 from curium, 2672–2673 DDP, 2706 from europium, 2676–2677, 2677t extraction chromatographic processes, 1293–1295 history of, 1268–1269 ion-exchange processes, 1289–1293 from plutonium, 869–870, 877, 878f precipitation processes, 1270–1271 pyrochemical processes, 1269–1270 solvent extraction processes, 1271–1289 TALSPEAK for, 2672–2673 sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f superconductivity of, 1789 synthesis of, 8–9 Americium (II) electrode potentials of, 1328, 1329t magnetic properties of, 2265–2268 oxidation of, by water, 1337 preparation of, 1325 stabilization of, 2077 Americium (III) absorption spectra of, 1364–1365, 1365f autoreduction of, 1330–1331 chlorides of, magnetic data, 2229–2230, 2230t complexes of, 1321 carbonate, 1340–1341 formation constants of, 1273 organic ligands, 1341, 1342t–1352t, 1353–1354, 1353f strengths of, 1353 compounds of carbides, 1319 halides, 1315 sulfates, 1320 detection of limits to, 3071t UVS, 3037 electrode potentials of, 1328–1329, 1329t extraction of, 1274 bis(2,3,4-trimethylpentyl)dithiophosphinic acid, 1286–1287 Cyanex 301, 1287–1289, 1288f, 2675–2676 DBBP, 1274 DHDECMP, 1277–1278, 2737–2738

from europium (III), 1283, 1287–1289, 2665–2666, 2667t HDEHP, 1275–1276, 1409 organophosphorus and carbamoylphosphonate reagents, 1276–1278 from picric acid, 1284 separation factors for, 2669–2670, 2670t TBP, 1271–1272 TPEN, 2675 TPTZ and HDNNS, 1286–1287, 2673–2675, 2674t from trivalent lanthanides, 1286–1289, 1288f formation constants of, 1338, 1339t hydration numbers of, 2534, 2535t hydrolysis, 1339–1340 hydrolytic behavior of, 2546, 2547f, 2547t–2548t in hydrosphere, 1807–1810 interaction parameters of, 2062–2064, 2063t ligands for, 3420–3421 luminescence of, 1368–1369, 1369f, 2098 magnetic properties of, 2263–2265 in mammalian tissues bone, 3403 bone binding, 3409 circulation clearance of, 3368–3369, 3368f–3375f, 3371–3376 glycoproteins, 3410–3411, 3411t initial skeletal fractions of, 3349 transferrin binding to, 3365 peroxydisulfate oxidation of in acid media, 1333–1334, 1333f in carbonate media, 1335 preparation of, 1325 purification of, 1290–1293 anion-exchange, 1291–1292 cation-exchange, 1290–1291 from curium (III), 1410 inorganic exchangers, 1292–1293 zirconium based sorbents, 1409 radii of, 1295–1296 separation of, HDEHP for, 2651, 2651f speciation of, 3114t, 3115 TIP of, 2263–2264 XANES of, 3087, 3089f Americium (IV) absorption spectra of, 1365 autoreduction of, 1331 complexes of, carbonate, 1341 compounds of, halides, 1315 disproportionation of, 1331 electrode potentials of, 1328–1329, 1329t hydrolysis, 1340 magnetic properties of, 2262–2263 peroxydisulfate oxidation of, in nitric acid, 1334

I-16

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Americium (IV) (Contd.) preparation of, 1325–1326 radii of, 1295–1296 stabilization of, 1355–1356 XANES of, 3087, 3089f Americium (V) absorption spectra of, 1366, 1367f autoreduction of, 1330–1331 complexes of, carbonate, 1341 compounds of carbides, 1319 halides, 1315 sulfates, 1320–1321 disproportionation of, 1332, 1332f electrode potentials of, 1329, 1329t hydrolysis, 1340 preparation of, 1326 reduction of by hydrogen peroxide, 1335–1336 by neptunium (IV), 1336 by neptunium (V), 1336–1337 in sodium hydroxide, 1336 by uranium (IV), 1337 uranium (VI) interaction with, 1356 Americium (VI) absorption spectra of, 1366, 1367f in americium precipitation, 1271 autoreduction of, 1331 complexes of, carbonate, 1341 compounds of halides, 1315 sulfates, 1321 electrode potentials of, 1329, 1329t extraction of, HDEHP, 1275 hydrolysis, 1340 preparation of, 1326–1327 reduction of by hydrogen peroxide, 1335 by other reductants, 1335 TBP extraction of, 1272 Americium (VII) absorption spectra of, 1367–1368, 1368f electrode potentials of, 1329, 1329t preparation of, 1327 Americium antimonide, 1318 Americium bismuthide, 1318 Americium carbide entropy of, 2196, 2197t formation enthalpy of, 2195–2196, 2197t high-temperature properties of, 2198, 2198f, 2199t Americium (V) carbonate, in americium precipitation, 1271 Americium carbonates, structural chemistry of, 2426–2427, 2427t Americium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t

Americium dibromide, structure of, 2415 Americium dichloride, 2179, 2180t structure of, 2415 Americium diiodide magnetic properties of, 2266 structure of, 2415 Americium dioxide, 1303, 1313 enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 EPR of, 2292 heat capacity of, 2138–2141, 2139f, 2142t magnetic properties of, 2291–2292 phase relations of, 2396 phase transformation of, 2292 Americium (III) fluoride, stability constants of, 1354–1355 Americium hexafluoride, thermodynamic properties of, 2164t Americium hydrides entropy of, 2188, 2189t formation enthalpy of, 2187–2188, 2187t, 2189t, 2190f high-temperature properties of, 2188–2190, 2190t structure of, 2404 Americium monoxide, structure of, 2395 Americium nitride, 1317–1319 Americium oxalate, in americium precipitation, 1270–1271 Americium oxides phase relations of, 2395–2396 structure of, 2395–2396 Americium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Americium phosphates, structural chemistry of, 2430–2433, 2431t–2432t Americium phosphide, 1318 Americium pnictides, structure of, 2409–2414, 2410t–2411t Americium sesquioxide formation enthalpy of, 2143–2146, 2144t, 2145f high-temperature properties of, 2139f, 2146–2147 structure of, 2395, 2396t Americium sesquisulfide, 1316–1317 Americium sulfates, structural chemistry of, 2433–2436, 2434t Americium tetrahalides, structural chemistry of, 2416, 2418t Americium (III) thiocyanate, 1355 Americium trichloride, thermodynamic properties of, 2170t, 2172, 2173t Americium trihalides, structural chemistry of, 2416, 2417t Americium tritelluride, 1317

Subject Index

I-17

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Americium–240 deformation of, 1880 isotope shift of, 1882–1884, 1883f, 1883t Americium–241 applications of, 1267–1268, 1828 autoreduction of, 1330–1331 curium–242 from, 1267, 1397, 1401–1402 detection of γS, 3301–3302 ICPMS, 3328 limits to, 3071t αS, 3295 environmental hazards of, 1807 importance of, 1267 isotope shift of, 1882–1884 laser spectroscopy of, 1873 neutrons from, 1827 nuclear properties of, 3277t production of, 1265, 1268 radiolysis of, 1337–1338 separation and purification of, pyrochemical processes, 1269–1270 study of, 1765 Americium–242 isotope shift of, 1882–1884, 1883f, 1883t laser spectroscopy of, 1880–1882, 1881f nuclear properties of, 3277t production of, 1267 Americium–243 applications of, 1267–1268 autoreduction of, 1330 curium from, 1400 detection of MBAS, 3043 MBES, 3028 importance of, 1267 isotope shift of, 1882–1884 laser spectroscopy of, 1873 nuclear properties of, 3277t production of, 1268 radiolysis of, 1337–1338 study of, 1765 Americium–244, isotope shift of, 1882–1884, 1883f, 1883t Americyl ion, complexes of cation-cation, 2594 structure of, 2400–2402 Amide extractants, for americium, 1285–1286 Amides complexes of, with cyclopentadienyl complexes, 2832 of plutonium, 1184–1185 Amidinate ligands, 2873–2875 Amine extractants for americium, 1284 quaternary ammonium salts, 1284 tertiary amine salts, 1284

for berkelium, 1448–1449 for separation, 2660, 2661f Amine extraction, for uranium leach recovery, 312 Amine, silane reactions with, 2978–2981 Amines, with terminal alkyne complexes cross dimerization, 2952 dimerization, 2943–2944 Aminex A6 for rutherfordium extraction, 1699 for seaborgium extraction, 1710 Aminopolycarboxylate americium and curium extraction with, 1286 complexes of, 2587, 2588f, 2589t californium, 1554 Ammonia plutonium processing with, reduction and oxidation reactions, 1141–1142 with uranium trichloride, 452 Ammonium carbonate, for uranium carbonate leaching, 308 Ammonium citrate, for californium separation, 1508 Ammonium lactate, for californium separation, 1508 Ammonium nitrate, actinium solubility in, 38–39 Ammonium oxalate, actinide stripping with, 1280 Amperometric method, for protactinium, 227 AMS. See Accelerator mass spectrometry Analytical chemistry for actinide elements, 3018, 3019t requirements for, 3018–3020 separation for, 3021 of actinium, 42 comparing techniques for, 3065–3071 of neptunium, 782–795 of thorium, 133–134 of uranium, 631–639 chemical techniques, 631–635 nuclear techniques, 635–636 spectrometric techniques, 636–639 Angle-resolved photoemission spectroscopy (ARPES) description of, 2336 of UIr3, 2336–2339, 2337f Angular coefficients, of actinide elements, 1863 Angular function, of f-orbitals, 1895, 1896t Angular momentum of band structure, 2319 spin-orbit coupling with, 1911 Animals actinide clearance from circulation, 3367–3387 dioxo ions, 3379–3387

I-18

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Animals (Contd.) rates of, 3367–3369, 3368f–3375f tetravalent and pentavalent, 3376–3379 trivalent, 3370–3376 actinide elements in, 3339–3424 binding in bone, 3406–3412 bone, 3400–3406 liver, 3395–3400 in vivo chelation, 3412–3423 desferrioxamine, 3414 polyaminopolycarboxylic acids, 3413–3414 siderophores, 3414–3423 initial distribution in, 3340–3356 access to, 3340–3341 beagle dogs, 3343t dioxo ions, 3354–3356 ionic radii and stability constants, 3346, 3347t Kenya baboons, 3345t Macaque monkeys, 3344t mice, 3343t pentavalent, 3350–3354 rats, 3341t–3342t skeletal fraction, 3346–3349, 3348f soft tissues, 3349–350 tetravalent, 3350–3354 trivalent, 3345–3350 tissue deposition kinetics, 3387–3395 in mice, 3388–3395, 3389f–3392f, 3394t in rats, 3387–3388 transport in body fluids, 3356–3367 extracellular fluid circulation, 3357–3359 loose connective tissue, 3359 plasma and tissue fluid composition, 3356–3357, 3357t–3358t plasma distribution of, 3357t–3358t, 3359–3361 Anion exchange historical development of, 2635–2637, 2635f, 2642 for trace analysis, 3283, 3286f Anion-exchange chromatography for actinium purification, 31 for americium purification, 1291–1292 chloride solutions, 1291–1292 thiocyanate solutions, 1291 for californium separation, 1509 for curium separation, 1409, 1433 for einsteinium separation, 1585 flow sheet for, 849, 850f improvements of, 851 liquid, 851–852 for neptunium extraction, 714 operation of, 850–851 for plutonium concentration, 848–851, 850f plutonium (IV), 848–849, 848f for protactinium purification, 187–188

for rutherfordium extraction, 1695–1696, 1700 Anisotropic ligand polarization effect, crystalfield splittings and, 2054 Annealing, of plutonium, after selfirradiation, 982–983, 983f Ansa-organoactinide complexes dimerization of, 2935–2937 synthesis of, 2918–2920, 2920f Ansa-organothorium complexes alkyne complexes, dimerization of, 2935–2937 terminal alkyne complexes, dimerization of, 2935–2937 Anthropogenic actinides, 3015f, 3016 Antimonides of americium, 1318 of neptunium, 743–744 of plutonium, 1022–1023 preparation of, 1022 structure of, 1023, 1024f thermodynamic properties of, 2197t, 2203–2204 of uranium, 411–412 Antimony protactinium compound of, 204 thorium compound of, 98t, 100 uranium oxides with, preparative methods of, 383–389, 384t–387t Apatite, thorium in, 56t Aqueous phase actinide ions in, 1774–1776, 1775t, 2123–2133 electrode potentials, 2127–2131 enthalpy of formation, 2123–2125, 2124f–2125f entropies, 2125–2127 heat capacities, 2132–2133 separation in, 2638, 2649, 2649f, 2666–2667 for transactinide elements, measured v. predicted, 1717, 1718t Aqueous raffinate, protactinium enrichment with, 175–176 Aragonite uranium in, 291 uranyl in, 3160–3161, 3161t ARCA. See Automated Rapid Chemistry Apparatus Arene complexes, structural chemistry of, 2489–2491, 2490t–2491t, 2493f Arene ligands, 2858–2860 bond distances, 2860 bonding of, 2859 bridging, 2859–2860, 2861f hydrogenation of, 2999–3000 kinetic data, 3002 overview of, 2858–2859 preparation of, 2859, 2860f

Subject Index

I-19

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 AREP. See Average RECP ARF. See Aerosol release fraction Argon uranium carbide oxide in matrix of, 1978–1980 uranium carbonyl in matrix of, 1985 uranium dioxide in matrix of, 1971–1976 uranium nitride in matrix of, 1988–1989 ARPES. See Angle-resolved photoemission spectroscopy Arrhenius curves for plutonium corrosion, 3225–3226, 3226f for uranium corrosion, in air and water vapor, 3242–3243, 3243f, 3244t Arsenates of actinide elements, 1796 of americium, 1321 structural chemistry of, 2430–2433 of thorium, 113 of uranium, 265t–266t autunite structures, 294–295 chain structures, 295–296 groups of, 294 natural occurrence of, 293 phosphuranylite structures, 295 synthetic, 296–297 uranophane structures, 295 Arsenazo-III. See 3,6-Bis-[(2-arsenophenyl) azo]–4,5-dihydroxy–2,7-naphthalene disulfo acid Arsenides of neptunium, 743 of plutonium, 1022 of protactinium, 204, 206t preparation of, 204 properties of, 207 thermodynamic properties of, 2197t, 2203–2204 of thorium, 98t, 100 of uranium, 411–412 Aryls, cyclopentadienyl complexes with, tetravalent, 2539f, 2819–2820, 2820f, 2837–2839 αS. See Alpha spectroscopy Ascorbate, for plutonium removal, 1823 Atomic absorption spectrometry (AAS) for environmental actinides, 3034t, 3036 overview of, 3307–3308 of uranium, 636 Atomic emission spectrometry (AES) for electronic structure, 1770 overview of, 3307–3308 of plutonium, oxides, 3208 of uranium, 636–637 Atomic properties of actinium, 33–34 of americium, 1295–1297 atomic and ionic radii, 1295–1296

electron configuration, 1295 emission spectra, 1296 ionization potentials, 1296 Mo¨ssbauer spectrum, 1297 photoelectrom spectrum, 1296–1297 x-ray spectrum, 1296 of curium absorption spectra, 1402–1404, 1404f–1405f electronic structure, 1404–1405 fluorescence spectroscopy, 1405–1406, 1406f of einsteinium, 1586–1588, 1589t–1590t of fermium, 1626, 1627t of lawrencium, 1643–1644 of mendelevium, 1633–1634, 1634t of nobelium, 1634t, 1639 of plutonium, 857–862 core-level spectra, 861 ionization potentials, 859 Mo¨ssbauer spectra, 861–862 optical emission spectra, 857–859, 858f, 860t x-ray spectra, 859–861 of protactinium, 189–191 emission spectrum, 190 ground state configuration, 190 Mo¨ssbauer effect, 190–191 X-ray atomic energy levels, 190, 190t of transactinide elements, 1672–1676 electronic structures of, 1672–1673, 1672t ionic radii and polarizability, 1674f, 1675–1676, 1676t oxidation state stabilities and IPs, 1673–1675, 1673t, 1674f–1675f Atomic radii of americium, 1295–1296 of berkelium, 1458 of californium, 1519–1521 of einsteinium, 1612–1613 of element 119, 1729, 1730f of element 120, 1729, 1730f Atomic spectroscopy of actinide elements, 2016–2018, 2018f overview of, 3307–3308 of thorium, 59–60 for trace analysis, 3307–3309 Atomic vapor laser isotope separation (AVLIS), history of, 1840 Atomic volumes of actinides, 922–923, 923f of einsteinium, 1578–1579, 1578f of lawrencium, 1644 of plutonium, 886, 887t in alloys, 934, 934f of δ-plutonium, 2345–2347, 2346f of rare earths, 922–923, 923f of transition metals, 922–923, 923f

I-20

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Atomic-beam magnetic resonance technique for electronic structure, 1770 for fermium, 1626 ATW. See Accelerator transmutation of waste Auger electron spectroscopy (AES), for environmental actinides, 3049t, 3051 Automated Rapid Chemistry Apparatus (ARCA) dubnium study with, 1704–1705 overview of, 1665 rutherfordium study with, 1695, 1698 seaborgium study with, 1710 Automated systems for superactinide element chemical studies, 1734–1735 for transactinide element chemical studies, 1663 Autoradiography (RAD) of actinide elements in bones, 1817 for environmental actinides, 3026t, 3031, 3032f Autunite at Oklo, Gabon, 271–272 uranium in, 259t–269t of uranium phosphates and arsenates, 294–295 Average RECP (AREP), for scalar relativistic mode, 1907–1908 AVLIS. See Atomic vapor laser isotope separation Azide complexes of, 2580, 2581t cyclopentadienyl complex reaction with, 2809 of neptunium, equilibrium constants for, 773t organouranium catalytic reduction of, 2994–2996 of uranium, 602, 603t B. sphaericus, plutonium adsorption, 3182–3183 Bacterial interactions, sorption studies of, 3177–3183 DMRB, 3178, 3181 examples, 3182–3183 overview, 3177–3178, 3179t–3180t reduction potentials, 3181 solubility and mobility, 3181–3182 surface complexation model, 3182 Bacterial leaching, of uranium ore, 306 Bacterial reduction, of uranium (VI), 297 Band structure filling of, 2320 free-electron model with, 2324 metal properties from, 2320, 2321f of uranium metal, 2318, 2318f

Barium, in curium metal production, 1411–1412 Base redox speciation in carbonate solution systems, 3129–3137 in hydroxide solution systems, 3124–3129 of neptunium neptunium (IV), 3111t–3112t, 3135–3136 neptunium (VII/VI), 3111t–3112t, 3124, 3125 of neptunyl (V), 3111t–3112t, 3133–3134 of plutonium plutonium (IV), 3113t, 3136 of plutonium (VII/VI), 3126 of plutonyl (VI), 3113t, 3134 of tetravalent ions, 3134–3135 of thorium thorium (IV), 3136–3137 of thorium (IV), 3129 uranium (IV), 3101t–3102t, 3136 of uranyl (VI), 3101t–3102t, 3126–3133 Bassetite at Oklo, Gabon, 271–272 uranium in, 259t–269t Bastnasite ore, plutonium–244 in, 824 Becquerelite at Shinkolobwe deposit, 273 uranium in, 259t–269t Bentonite, thorium and uranyl complexes of, 3157–3158 Benzamidinate ligands, 2875 Benzene, actinide complexes of, 1959–1960, 1961f Benzoates, structural chemistry of, 2439t–2440t 4-Benzoyl–2,4-dihydro–5-methyl–2phenyl–3H-pyrazol–3-thione, for americium/europium extraction, 2676–2677, 2677t N-Benzoylphenylhydroxylamine (BPHA), protactinium extraction with, 184 Berkeley. See Lawrence Berkeley National Laboratory Berkeley Gas-filled Separator (BGS) pre-separation by, 1666 hassium, 1713 rutherfordium, 1701 superactinide element, 1734 SISAK with, 1666 Berkelium analytical chemistry, 1483–1484 complexes of, tris-cyclopentadienyl, 2470–2476, 2472t–2473t compounds, 1462–1472, 1464t–1465t chalcogenides, 1470 coordination, 1471 general summary of, 1462–1463 halides, 1467–1470 hydrides, 1463 magnetic behavior of ions, 1472, 1473f

Subject Index

I-21

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 organometallic, 1471 other inorganic, 1470–1471 oxides, 1466–1467 pnictides, 1470 discovery of, 5t, 8 einsteinium separation from, 1584, 1584f enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t free atom and ion properties, 1451–1457 electronic energies, 1452–1453 emission spectra, 1453–1454 ion-molecule reactions in gas phase, 1455–1457, 1457f solid-state absorption spectra, 1455, 1456f thermochromatographic behavior, 1451 Gibbs formation energy of hydrated ion, 2539, 2540t half-life of, 1445–1447, 1446t heat capacity of, 2119t–2120t, 2121f history of, 1444–1445 ionization potentials of, 1452, 1874t ions in solution, 1472–1483 hydrolysis and complexation behavior, 1475–1479, 1477t–1478t oxidation states, 1472–1473, 1485 redox behavior and potentials, 1479–1482, 1481t, 1482f spectra in solution, 1473–1475, 1475f–1476f thermodynamic properties, 1482–1483, 1483t isotopes of, 9–10, 1445–1447, 1446t lanthanide elements v., 2 magnetic properties of, 2355–2356 metallic state of, 1457–1462 alloys, 1461–1462 chemical properties, 1460–1461 intermetallic compounds, 1461 physical properties, 1458–1460 preparation of, 1457–1458 structure of, 2388 theoretical treatment, 1461 nuclear properties, availability, and applications, 1445–1447, 1446t oxidation states of in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t production, 1446t, 1448 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f separation and purification, 1448–1451 TALSPEAK for, 2672 sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f synthesis of, 8–9

Berkelium (II) absorption spectra of, 1475 overview of, 1473 Berkelium (III) absorption spectra of, 1444–1445, 1473–1475, 1475f chlorides of, magnetic data, 2229–2230, 2230t compounds of β-diketonate, 1471 cyclopentadienyl, 1471 halides, 1468 orthophosphate, 1470–1471 oxalate, 1479 electronic spectra of, 1475 extraction of, 1479 hydrolytic behavior of, 2546, 2548t initial skeletal fractions of, 3349 ionic radii values of, 1463 magnetic properties of, 2268–2269, 2270t overview of, 1472–1473 oxidation of, 1448 redox behavior of, 1479–1482, 1481t, 1482f separation and purification of, 1448–1451 speciation of, 3109–3110, 3114t stability constants of, 1475–1476, 1477t–1478t Berkelium (IV) absorption spectra of, 1474–1475, 1476f californium (III) separation from, 1508–1509 compounds of fluorides, 1467–1468 halides, 1468 iodate, 1479 electronic spectra of, 1475 energy levels of, 2075–2076, 2075f hydration of, 2531 ionic radii values of, 1463 magnetic properties of, 2265–2268 overview of, 1472–1473 redox behavior of, 1479–1482, 1481t, 1482f speciation of, 3109–3110, 3114t Berkelium (V), overview of, 1472 Berkelium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Berkelium dioxide enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 heat capacity of, 2138–2141, 2139f, 2142t magnetic susceptibility of, 2268 structure of, 2398 Berkelium hydride, 1463, 1464t–1465t structure of, 2404 Berkelium orthophosphate, 1470–1471

I-22

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Berkelium oxide identification of, 1466 metal production with, 1457–1458 oxygen decomposition of, 1466 structure of, 2397–2398, 2398t Berkelium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Berkelium pnictides, structure of, 2409–2414, 2410t–2411t Berkelium sesquioxalate, 1471 high-temperature properties of, 2139f, 2146–2147 Berkelium sesquioxide, 1466–1467 formation enthalpy of, 2143–2146, 2144t, 2145f structure of, 2397, 2398t Berkelium tetrafluoride metal production with, 1457 properties of, 1467–1468 Berkelium tetrahalides, structural chemistry of, 2416, 2418t Berkelium tribromide, 1469 structural chemistry of, 2416, 2417t Berkelium trichloride monitoring of, 1469–1470 properties of, 1468–1469 Berkelium trifluoride, 1469 metal production with, 1457 Berkelium trihalides, structural chemistry of, 2416, 2417t Berkelium triiodide, 1469 Berkelium–249 adsorption of, 1451 availability of, 1445 californium alloy with, 1462 californium–249 from, 1504, 1511, 1766 decay of, 1447 dubnium production from, 1703 from einsteinium–253, 1579 electron-binding energies of, 1452 emission spectrum of, 1453–1454 lawrencium–260 from, 1642 physical properties of, 1445–1447 production of, 1444, 1448, 1504 for transactinide element production, 1661–1662 Berkelium–250 adsorption of, 1451 decay of, 1447 Beryllium foil, berkelium separation from, 1450 thermodynamic properties of actinide compounds with, 2205, 2206t–2207t Beta decay actinium as, 19–20 actinium–225, 25–26 actinium–227, 20 actinium–228 as, 24

americium, 1265–1267, 1266t berkelium berkelium–249, 1461 in study of, 1446 californium–253, 1582 neptunium as neptunium–238 as, 861 neptunium–239 as, 814 plutonium as plutonium–241, 825 plutonium–243, 825 protactinium as, 164 protactinium–233, 225–226 protactinium–234, 162, 225 in radioactive displacement principle, 162 uranium as uranium–237, 256 uranium–239, 825, 825f β-Phase of plutonium, 882, 882f–883f, 885t density of, 936t diffusion rate, 958–960, 959t fine-grain plasticity, 969–970 lattice changes in, 981–982, 982f, 982t magnetic properties of, 2355 thermal conductivity, 957 thermoelectric power, 957–958, 958t of uranium general properties of, 321–323, 322t–323t hydrogen system of, 328–339, 329t, 334f, 335t intermetallic compounds and alloys, 325–326, 325t α phase transformation of, 344 γ phase transformation of, 347 physical properties of, 321 thermal expansion, 938f Beta spectroscopy (βS) for environmental actinides, 3026t, 3028–3029 ICPMS v. αS and, 3070 BGS. See Berkeley Gas-filled Separator Bicarbonates, in plasma, 3361 for uranyl ion, 3380–3381 Bijvoetite natural occurrence of, 290 structure of, 290 Billietite at Shinkolobwe deposit, 273 uranium in, 259t–269t Bimetallic complexes, 2889–2893 bond distance in, 2893 bridging ligands in, 2889 cyclopentadienyl complexes and, 2890 metal-metal interaction in, 2891–2892, 2893f metathesis reactions for, 2889 overview of, 2889

Subject Index

I-23

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 phosphine groups in, 2890 phospholyl ligand in, 2890–2892, 2892f Binding energy of fermium, 1626, 1627t of uranium carbide oxides, 1980 Biochemistry, of uranium, 630–631 Biocolloids, formation of, 3181 Biokinetics studies, of actinides, 3339–3340 Biologic effects of berkelium, 1445 of californium, californium–252, 1507 of einsteinium, 1579 Biological behavior, of actinide elements, 1813–1818 bioremediation, 1817–1818 in body fluids, 1814–1815 bone uptake, 1817 general considerations, 1813–1814 liver uptake, 1815–1816 Biological matrices, trace analysis in, 3273–3330 atomic spectrometric techniques, 3307–3309 chemical procedures, 3278–3288 mass spectrometric techniques, 3309–3328 nuclear techniques, 3288–3307 Bio-Rad AG MP–1, for rutherfordium extraction, 1700 Biosorption solubility and mobility with, 3181–3182 of uranium and thorium by RA, 2669 Biotechnology, for neptunium extraction, 717 3,6-Bis-[(2-arsenophenyl)azo]–4,5dihydroxy–2,7-naphthalene disulfo acid (Arsenazo-III), protactinium compound with, 219 extraction with, 183, 2666–2667 in spectrophotometric methods, 228 Bisacetylide organoactinide complexes magnetic properties of, 2925 synthesis of, 2924–2925 Bis(trimethylsilyl)amide, 2876–2879 geometry of, 2876–2877 hydride compounds, 2877 metallacycles, 2877, 2878f organoimido complexes, 2877–2879 tetravalent complexes of, 2877 trivalent homoleptic complexes with, 2876 Bis-cyclopentadienyl complexes, structural chemistry of, 2476–2482, 2478f, 2479t–2480t, 2481f–2483f Bis(2,3,4-trimethylpentyl)-dithiophosphinic acid, americium (III) extraction with, 1287 Bismuth phosphate for coprecipitation, 2634 for plutonium coprecipitation, 835

Bismuth phosphate process, for actinide production, 2730 Bismuth, uranium oxides with, 383–389, 384t–387t Bismuth–214, nuclear properties of, 3298t Bismuth–231, actinium–225 generation of, 44 Bismuthides of americium, 1318 of neptunium, 744 thorium compound of, 98t, 100 of uranium, 411–412 Bis(2-ethyl)orthophosphoric acid, californium extraction with, 1513 Bisphosphine oxide, lanthanide extraction with, 2657 Bis(2-ethylhexyl)phosphoric acid (HDEHP) actinide extraction with, 1769 actinium extraction with, 30, 1293 americium extraction with, 1275–1276, 2671 berkelium extraction with, 1448–1450, 1450f californium extraction with, 1509 curium extraction with, 1407, 1434, 2672 einsteinium extraction with, 1585 lawrencium extraction with, 1646–1647 mendelevium extraction with, 1633 neptunium extraction with, 708–709 nobelium extraction with, 1638–1640 protactinium extraction with, 172, 184 separation with, 2639–2640, 2641t, 2650–2651, 2651f, 3282 Bistriazinylpyridine (BTP), americium extraction with, 2674–2675, 2674t Bloch states in actinide metals, 2316 overview of, 2316 representation of, 2317 Body fluids, actinide transport in, 3356–3367 plasma and tissue fluid composition, 3356–3357, 3357t–3358t Bohrium berkelium–249 in production of, 1447 chemical properties of, 1691t, 1711–1712 discovery of, 6t, 1653, 1653t, 1762 electronic structures of, 1676–1682, 1677f–1678f, 1680t–1681t, 1682f ionic radii of, 1674f, 1675–1676, 1676t ionization potential of, 1674, 1674f isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, in aqueous solution, 1774–1776, 1775t relativistic orbital energies for, 1669f solution chemistry of complexation of, 1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f

I-24

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Bohrium–264, from meitnerium–268, 1717 Bohrium–267 decay chains of, 1711 discovery of, 1735 production of, 1711 Boiling point, of californium, metal, 1523 Bomb reduction furnace, for plutonium metal production, 866, 867f Bond lengths of actinide nitride oxides, 1990, 1990t of actinide nitrides, 1988, 1989f of actinyl complexes, 1926–1927, 1928t of plutonium, 884t of superactinide elements, 1732 of uranium hexafluroride, 1935–1937, 1937t oxides, 1973, 1974t–1975t of uranium and oxygen, in silicate glass, 276–277 Bond valence approach for crystal structure, 286 expression for, 3093 for uranyl (VI), 3093–3094, 3094f Bonding in actinide complexes, 2556–2563 coordination numbers, 2558–2560, 2559f covalent contribution to, 2561–2562, 2563t ionicity of f-element, 2556, 2557f steric effects in, 2560 strength of, 2560–2561 thermodynamics of, 2556–2557, 2558t in actinide compounds, 1894 relativistic effects on, 1898, 1899f in actinocenes, 2853–2854, 2854f in berkelium, 1452, 1455–1457, 1457f of cyclopentadienyl complexes, tetravalent, 2815–2817, 2816f, 2816t, 2818f DFT for, 923–924 in f-orbital, 1915–1916 in halides, 2415 in metallic state, 2308, 2319 oxidation state, coordination numbers and distance in, 3093 in plutonium, 1191–1203 dioxide, 1196–1199, 1197f, 1200f hexafluoride, 1194–1196, 1195f ionic and covalent, 1191–1192 plutonocene, 1199–1203, 1201f–1202f specific examples, 1192–1203 in transactinide elements, 1677 in uranium hexafluoride and pentafluoride, 576–575 hydrides, 333–336, 334f, 335t in uranyl polyhedra, 280–281 Bone accumulation of protactinium–231, 188 actinide binding in, 3406–3412

glycoproteins, 3410–3411 in vitro, 3407–3409 in vivo, 3406–3407 actinide elements in, 1817, 3400–3406 americium (III), 3403 neptunyl ion, 3404 plutonium (IV), 3403 retention of, 3404–3406 uranyl ion, 3403 blood supply of, 3402 composition of, 3406 as deposition site, 3344 liver v., 3344–3345 surfaces of, 3401–3402 transuranium elements in, 12 Borates, of thorium, 113 Borides of americium, 1321 of plutonium, 996–1003 history of, 997 phase diagram, 997, 997f preparation of, 998 properties of, 1002–1003 solid-state structures of, 998–1002, 999t, 1000f–1002f structural chemistry of, 2405–2408, 2406t of thorium, 66–67, 71t–73t structure of, 66–67 ternary, 67, 74f of uranium, 398–399, 399f, 401t–402t phase diagram of, 398, 400f preparation of, 398 properties of, 398–399, 401t–402t structure of, 398, 399f Boron, thermodynamic properties of actinide compounds with, 2205–2206, 2206t–2207t Born equation, for complexation, 2574–2577 Borohydrides of plutonium, 1187 structural chemistry of, 2404–2405, 2405f Borosilicate glass einsteinium in, 1601–1602, 1602f–1603f SNF disposal in, 1812–1813 BPHA. See N-Benzoylphenylhydroxylamine Brannerites natural occurrence of, 280 uranium in, 269t, 274, 280 Bravais lattice, description of, 2317 Breit effects, on element 121, 1669 Brevium. See Protactinium Brillouin zones of actinide metals, 2317–2318 in crystal structure, 2321 description of, 2317 in magnetism, 2367 Brinell hardness, of uranium metal, 323

Subject Index

I-25

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Bromates, of actinide elements, 1796 Bromides of actinide elements, 1796 of berkelium, 1469 of californium, 1533 of curium, 1413t–1415t, 1417–1418 of dubnium, 1703, 1705–1706 of einsteinium, 1599 of neptunium, 737–738 equilibrium constants for, 772t tetrabromide, 737 tribromide, 737–738 of plutonium, 1092–1100 preparation of, 1092–1095 properties of, 1087t, 1098–1100 solid-state structures of, 1084t, 1096–1097, 1096f–1098f protactinium derivatives of, 197–199, 207 of uranium bromo complexes, 454 dioxide monobromide, 527–528 oxide and nitride, 497, 500 oxide tribromide, 527 oxobromo complexes, 572–574 pentabromide, 526 ternary and polynary compounds, 495–497 tetrabromide, 494–495 tribromide, 453 tribromide hexahydrate, 453–454 of uranyl bromide, 571–572 hydroxide bromide and bromide hydrates, 572 βS. See Beta spectroscopy BTP. See Bistriazinylpyridine Butenouranocene, structure of, 2487, 2488t, 2489f BUTEX process for actinide production, 2731 REDOX process v., 2731 BUTEX process, PUREX process v., 842 t-Butylbenzene (TBB), americum extraction with, 2673–2675, 2674t Tert-Butylhydrazine (tert-BHz), neptunium (VI) reduction with, 761 By-product, uranium as, 314 Cadmium nitridation in, 2725 with thorium molybdates, 112 Calcination, of uranium ore, 304 Calcite uranium in, 289–291, 3160 natural occurrence of, 3163 surface site incorporation of, 3162 uranyl in, 3160–3161, 3161t

Calcium in DOR process, 866–867 in einsteinium alloy, 1592 reduction, plutonium production, 2722 for uranium reduction, 319 Calcium carbonate, for oxidation state speciation, 2726 Calculation of phase diagrams (CALPHAD), application of, 927–928 Californium, 1499–1563 applications, 1505–1507 berkelium alloy with, 1461–1462 complexes of, tris-cyclopentadienyl, 2470–2476, 2472t–2473t compounds of, 1527–1545, 1530t–1531t chalcogenides, 1539–1540 dipivaloylmethanato complex, 1541 general comments, 1527–1529, 1530t–1531t halides, 1529–1534, 1532f, 1542–1545, 1544f hydrides, 1540–1541 magnetic properties of, 1541–1542 organometallic, 1541 other, 1538–1541 oxides, 1534–1538 oxyhalides, 1529–1534, 1532f oxysulfates, 1541 pnictides, 1538–1539 solid-state absorption spectra, 1542–1545, 1544f sulfates, 1549 thiocyanates, 1554 discovery of, 5t, 8–9 einsteinium separation from, 1585 einsteinium v., 1613 electronic properties and structure, 1513–1517, 1514t emission spectra, 1516 x-ray emission spectroscopy, 1516–1517 fermium separation from, 1624–1625 gas-phase studies, 1559–1561 Gibbs formation energy of hydrated ion, 2539, 2540t half-life of, 1503–1504 ionization potentials of, 1874t isotopes of, 9–10, 12, 1499–1502, 1500t lanthanide elements v., 2 lawrencium from, 1641 magnetic properties of, 2355–2356 metallic state of, 1517–1527 chemical and mechanical properties of, 1525–1526 physical properties of, 1519–1525, 1520t preparation of, 1517–1519 structure of, 2388 theoretical treatments of, 1526–1527

I-26

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Californium (Contd.) nobelium v., 1640 nuclear properties of, 1499, 1500t, 1502–1504 oxidation states of, 1528, 1545, 1548, 1562, 2526 in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t preparation of, 1499–1500, 1502–1504 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f separation and purification, 1507–1513, 1510f solution chemistry, 1545–1559 absorption spectra, 1557–1559, 1557t, 1558f, 1559t complexation chemistry, 1549–1555, 1550t–1553t general comments, 1545–1546 redox reactions, 1546–1549, 1547t thermodynamic data, 1555–1557, 1556t sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f synthesis of, 8–9 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t heat capacity of, 2119t–2120t, 2121f Californium (II) absorption spectra of, 1516, 1543–1544 existence of, 1547 overview of, 1501 preparation of, 1534, 1537 Californium (III) absorption spectra of, 1515–1516, 1543–1544, 2091, 2092f berkelium (IV) separation from, 1508–1509 compounds of halides and oxyhalides, 1529–1534, 1532f oxides, 1534–1538 EPR of, 2269 extraction procedures for, 1512–1513 hydration of, 2528–2530, 2529f, 2529t hydrolytic behavior of, 1554, 2546, 2548t magnetic properties of, 2269–2271, 2270t magnetic susceptibility of, 2269–2271, 2270t in mammalian tissues circulation clearance of, 3368–3369, 3368f–3375f, 3371–3376 initial skeletal fractions of, 3349 transferrin binding to, 3365 overview of, 1501 oxidation of, 1546 reduction of, 1548 speciation of, 3110, 3114t, 3115

Californium (IV) compounds of, oxides, 1534–1538 magnetic properties of, 2268–2269, 2270t Californium (V), generation of, 1549 Californium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Californium dibromide, 1533 Californium dichloride, 1533–1534 absorption spectra of, 1542–1544, 1544f structure of, 2416 Californium diiodide, 1533 structure of, 2416 Californium dioxide, 1536 enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 structure of, 2399 Californium monoxide, 1535 Californium oxides, structure of, 2398–2399, 2398t Californium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Californium pnictides, structure of, 2409–2414, 2410t–2411t Californium sesquioxide, 1535–1537, 1535f formation enthalpy of, 2143–2146, 2144t, 2145f structure of, 2398, 2398t Californium tetrafluoride, 1529 Californium tetrahalides, structural chemistry of, 2416, 2418t Californium tribromide, 1533 thermodynamic properties of, 2170t, 2172, 2173t Californium trichloride, 1532 Californium trifluoride, 1529, 1532 Californium trihalides, structural chemistry of, 2416, 2417t Californium triiodide, 1533 Californium–242, production of, 1502 Californium–249 from berkelium–249, 1446, 1461, 1511, 1579 in compounds, 1462 curium–245 from, 1401 energy spectrum of, 1516 IS of, 1872 lawrencium from, 1641–1642 metal production from, 1517–1518, 1518f nuclear magnetic moments of, 1872 production of, 1504 study of, 1766 for transactinide element production, 1661–1662 Californium–250 half-life of, 1504 IS of, 1872

Subject Index

I-27

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Californium–251 IS of, 1872 nuclear magnetic moments of, 1872 production of, 1504 Californium–252 for cancer treatment, 1829 curium–248 from, 1400, 1765–1766 decay of, 1766 energy spectrum of, 1516 half-life of, 1503 IS of, 1872 metal production from, 1518 neutrons from, 1827–1828, 3302–3303 production of, 1401, 1501, 1503–1504 spontaneous fission of, 1505 Californium–253, production of, 1504 Californium–254, spontaneous fission of, 1505 Calixarenes description of, 2456 structural chemistry of, 2456–2463 3 coordination, 2459–2460 4 coordination, 2460, 2461f 5 coordination, 2460–2461 8 coordination, 2461, 2462f 12 coordination, 2461–2462, 2463f other coordination, 2461 CALPHAD. See Calculation of phase diagrams CAM. See Catecholamine Cancer treatment, californium–252 for, 1829 Capillary electrophoresis, ICPMS with, 3069 Carbamoylmethylenephosphine oxide (CMPO), americium extraction with, 1278–1284 Carbamoylphosphonate reagents americium extraction with, 1276–1278 in solvating extraction systems, 2653 Carbide oxides, of actinides, matrix-isolated, 1976–1984 Carbides of americium, 1305t–1312t, 1319 of neptunium, 744 of plutonium, 1003–1009 chemical properties of, 1007–1008 crystal structures of, 1004–1007, 1005t, 1006f–1007f phase diagram of, 1003–1004, 1003f preparation of, 1004 ternary phases, 1009 thermodynamic properties of, 1008–1009 of protactinium, 195 structural chemistry of, 2405–2408, 2406t thermodynamic properties of, 2195–2198 gaseous, 2198 solid, 2195–2198 of thorium, 67–69, 68f, 71t–73t halogens with, 68

structures of, 67–69, 68f ternary, 68–69, 74f of uranium, 399–405, 401t–402t, 403f–404f application of, 405 hydrolytic behavior of, 403–405 phase diagram of, 399, 403f preparation of, 400 structure of, 400, 404f ternary, 405 Carbocyclic ligands, 2858–2865 arene ligands, 2858–2860 bond distances, 2860 bonding of, 2859 bridging, 2859–2860, 2861f overview of, 2858–2859 preparation of, 2859, 2860f cycloheptatrienyl ligand, 2860–2862 bonding in, 2862, 2863f formation of, 2860–2861 structure of, 2861–2862, 2862f fullerenes, 2864–2865 electronic structure of, 2864–2865 overview of, 2864 pentalene, 2862–2864 bond lengths in, 2864 derivation of, 2862 use of, 2863 Carbon dioxide reactions, with cyclopentadienyl complexes, 2824 uranium mineral adsorption and, 3158 Carbon, hydrogen, oxygen, nitrogen principle (CHON principle), actinide extraction by, 1285, 1287 Carbonate leaching, of uranium ore, 307–309, 309f, 632 benefits of, 307 flow chart of, 308, 309f oxygen for, 307–308 Carbonates of actinide elements, 1796 actinide speciation in, 3159 of actinyl complexes, 1926, 1928t, 1929f of americium, 1305t–1312t, 1319, 1340–1341 common mineral phases of, 3159, 3159t complexes of, 2583 of neptunium, 745 equilibrium constants for, 774t–775t in plasma, 3361 of plutonium, 1159–1166 application of, 1159 formation constants, 1160–1161t heptavalent, 1163–1165 hexavalent, 1165–1166 tetravalent, 1162–1163 trivalent, 1159 precipitation

I-28

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Carbonates (Contd.) with DDP, 2706, 2707f protactinium enrichment with, 174–175 sorption studies of, 3159–3164 structural chemistry of, 2426–2427, 2427t, 2428f of thorium, 108–109 crystallization of, 109 with fluoride, 109 as ligands, 129 solubility and, 127–128 synthesis of, 108–109 of uranium, 261t–263t EXAFS of, 3160–3161, 3161t formation of, 289 natural occurrence of, 291 properties of, 289–290 structures of, 290 Carbonyl complexes of actinides, 1987–1987 of d-transition metals, 2893 Carboxylates complexes of, 2584, 2585t–2586t, 2586–2587, 2590 entropy change, 2557, 2558t of curium, 1429 of neptunium (IV), EXAFS investigations of, 3137–3140, 3147t–3150t organophosphorus ligands v., 2585t–2586t, 2588 of plutonium, 1176–1181, 1178t structural chemistry of, 2437–2448, 2438f, 2439t–2443t, 2443f–2447f acetates, 2439t–2440t, 2440–2445, 2444f di-, 2441t–2443t, 2445–2448, 2445f–2447f dipicolinates, 2441t–2443t, 2446–2447, 2446f formates, 2437–2440, 2439t–2440t malonates, 2441t–2443t, 2447–2448 mono-, 2438–2445, 2439t–2440t, 2444f overview of, 2437 oxalate, 2441t–2443t, 2445–2446, 2445f tetra- and hexa, 2443t, 2448 of thorium, 113–114 EXAFS investigations of, 3137–3140, 3147t–3150t in solvent extraction, 113–114 of uranyl (VI), EXAFS investigations of, 3137–3140, 3141t–3150t Carnotite description of, 297–298 natural occurrence of, 297–298 plutonium in, 822 uranium production with, 297 Catalytic processes, by organoactinides, 2911–3006 alkyne dimerization, 2930–2947 promotion of, 2938–2947, 2940f–2941f

terminal, 2930–2935 terminal ansa-, 2935–2937 alkyne hydroamination, 2981–2990 kinetic studies of, 2986–2990 neutral organoactinide complex promotion, 2981–2986 alkyne oligomerization, 2923–2930 bisacetylide organoactinide, 2924–2925 cross, 2929–2930 key intermediate complex in, 2926, 2926f terminal, 2925–2926, 2928f amine, silane reactions, 2978–2981 azide and hydrazine reduction, 2994–2996 constrained-geometry hydroamination, 2990–2994 heterogeneous, 2999–3006 active site assessment, 3000–3002 alkane activation, 3002–3006 arene hydrogenation, 2999–3000 olefin hydrogenation, 2996–2997 olefin hydrosilylation, 2953–2978 of alkenes, 2969–2974 promotion for alkynes, 2974–2978 promotion for terminal alkynes, 2964–2969 of terminal alkynes, 2953–2964 olefin polymerization, 2997–2999 reactivity, 2912–2923 activation modes, 2912–2913 alkyne and silane stoichiometric reactions of, 2916–2918, 2917f [(Et2N)3U][BPh4], 2922–2933 stoichiometric reactions of, 2913–2916, 2914f–2915f synthesis of ansa- complexes, 2918–2920, 2920f synthesis of high-valent organouranium complexes, 2920–2922, 2921f terminal alkyne cross dimerization, 2947–2952, 2948f–2949f Catalyzed ignition, of plutonium, 3236–3237 Catcher foil. See Foil Catecholamine (CAM) complexes of, 2590–2591 for plutonium removal, 1824 Catecholate ligands, as chelating agents, 3414–3416, 3415f Cation exchange of berkelium, 1449–1450 of californium, 1512 of curium, 1433 historical development of, 2636–2641, 2637f for trace analysis, 3282–3283 of uranium, 633 Cation-cation interaction actinide complexes of, 2593–2596, 2596f, 2596t model of, 2593–2595

Subject Index

I-29

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 structures of, 2595, 2596f thermodynamic properties of, 2595–2596, 2596t in neptunium (V) coordination complexes, 748 in pentavalent and hexavalent actinides, 1356 Cation-exchange chromatography for actinium purification, 30–32, 31f for americium purification, 1290–1291 chromatographic elution schemes, 1290–1291 distribution coefficients, 1290 for dubnium extraction, 1704–1705 for fermium purification, 1629 for lawrencium extraction, 1643, 1645 for rutherfordium extraction, 1699–1700 for seaborgium extraction, 1710–1711 CC. See Complexant concentrate CCF. See Correlation crystal-field CCSDs. See Single double coupled cluster excitations Central field approximation effective-operator Hamiltonian with, 2027 for free-ion interactions modeling, 2020–2023 overview of, 2020 Ceramic capacitors, protactinium in, 189 Cerium americium interaction with, 1302 berkelium separation from, 1449 extraction of, TALSPEAK for, 2672 Cerium (IV), detection of, VOL, 3061 Cerocene, thorocene v., 1947 Cesium, with thorium sulfates, 105 CF. See Crystal-field Chain structures factors in, 579 in soddyite, 293 in studtite, 288–289 of uranium phosphates and arsenates, 295–296 in uranyl minerals, 281 selenites and tellurites, 298 in weeksite, 292–293 Chalcogenides of americium, 1305t–1312t, 1316–1317 coordination of, 1358–1359 of berkelium, 1464t–1465t, 1470 preparation of, 1460 of californium, 1530t–1531t, 1539–1540 of curium, 1413t–1415t, 1420–1421 cyclopentadienyl complexes with, 2837 of neptunium, 739–742 selenides, 740–741 sulfides, 739–740 tellurides, 741–742 of plutonium, 1023–1077

oxides, 1023–1052 sulfides, tellurides, and selenides, 1052–1056 ternary and polynary, 1056–1069 ternary oxides, 1069–1070 structural chemistry of, 2409–2414, 2412t–2413t, 2414f thermodynamic properties of, 2203t, 2204–2205 of thorium, 75t, 95–97 structures of, 95–96 of uranium, 412–420, 414t–417t Charge-density waves, quantization of, 2317–2318 Charge-transfer transitions of actinide ions, 2085–2089 of neptunyl, 2089 overview of, 2085–2086 of uranyl, 2086–2089 Chelate chromatography, neptunium extraction with, 714–716, 715f Chelate formation, by glycolate and acetate, 590 Chelating agents desferrioxamine, 3414 for plutonium removal examples of, 1822–1823 new, 1824–1825 problems with, 1823–1824 polyaminopolycarboxylic acids, 3413–3414 siderophores, 3414–3423 Chemical methods for transactinide elements, 1734–1735 of uranium ore processing, 302 Chemical precipitation, for uranium leach recovery, 313–314 history of, 313 materials for, 314 process of, 313–314 Chemical reactions, of uranium metal, 327, 327t Chemical reactivity of neptunium hexafluoride, 733–734 of thorium, 63 Chemical transport reactions, for uranium oxide preparation, 343 Chernikovite at Oklo, Gabon, 271–272 uranium in, 259t–269t Chitosan, uranyl adsorption on, 2669 Chloride solutions, for americium purification, 1291–1292 Chlorides of actinide elements, 1796 of berkelium, 1468–1470 of californium, 1532–1534 absorption spectra of, 1542–1544, 1544f complexes of, 2579–2580, 2581t

I-30

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Chlorides (Contd.) of curium, 1413t–1415t, 1417–1418 of dubnium, 1703, 1705 of einsteinium, 1595 Gibbs energy of formation for, 2710t of neptunium, 736–737 equilibrium constants for, 772t tetrachloride, 736–737 trichloride, 737 of plutonium, 1092–1100 preparation of, 1092–1095 properties of, 1087t, 1098–1100 solid-state structures of, 1084t, 1096–1097, 1096f–1098f of protactinium derivatives of, 197–199, 198f, 207 protactinium (V), 213, 215t in pyrochemical methods, 2694–2700 americium, 2699–2700 curium and transcurium, 2700 neptunium, 2697–2698 plutonium, 2698–2699, 2699f protactinium, 2695 thorium, 2694–2695 uranium, 2695–2696, 2697f of seaborgium, 1707 TRUEX processing of waste, 2742, 2742f of uranium anhydrous complexes, 450–452 complexes, 492–493, 523–524 dioxide dichloride, 567–569 hexachloride, 567 nitride, 500 oxide, 524–525 oxochloride, 525–526 pentachloride, 522–523 perchlorates, 494 perchlorates and related compounds, 570–571 tetrachloride, 490–492 trichloride, 446–448, 447f trichloride hydrates, 448–450 Chlorination, of dubnium, 1705 Chlorinator-electrolyzer, for DDP, 2707 Chlorine, from radiolysis, 1145–1146, 1146t Chloroplutonate compounds application of, 1104 phase diagram of, 1104, 1108f preparation of, 1104 properties of, 1108, 1109t CHON principle. See Carbon, hydrogen, oxygen, nitrogen principle Chromates of americium, 1321 of neptunium, equilibrium constants for, 775t of thorium, 112 structure of, 112 synthesis of, 112

Chromatography, overview of, 3067 CI. See Configuration interaction Circulation. See Plasma Citrates in plasma, 3360–3361 for plutonium removal, 1823 for separation, 2638–2639, 2639t of thorium, as ligands, 131, 132t Citrobacter sp., uranyl phosphate precipitation by, 297 Clarification, in uranium ore processing, 308–309 Clarkeite, transformation of, 288 Clay groups of, 3151–3152 silicates in, 3151 for SNF storage, 1813 Cliffordite, as uranyl tellurite, 298 CMPO. See Carbamoylmethylenephosphine oxide; n-Octyl(phenyl)-N,N-diisobutylcarbamoyl methylphosphine oxide Cobalt, plutonium melting point and, 897 Coffinite natural occurrence of, 275–276 at Oklo, Gabon, 271–272 structure of, 586, 587f uranium in, 259t–269t, 274 Cohesion properties of actinide metals, 2368–2371 in transplutonium materials, 2370–2371 COL. See Colorimetry COLD. See Cryo On-Line Detector ‘Cold’ fusion, element production by, 1737 Colloidal materials, actinide association with, 3287–3288 Color of actinium, 34–35 of protactinium, 194 of thorium, 61 Color cathode ray tube, protactinium for, 188–189 Colorant, uranium as, 254 Colorimetry (COL), for environmental actinides, 3034t, 3035 Column partition chromatography. See Partition chromatography Comilling, of plutonium and uranium oxides, 1074 Complexant concentrate (CC), TRUEX process for, 2740 Complexation of actinide elements, 1782–1784, 2524–2607 bonding, 2556–2563 cation hydration, 2528–2544 cation hydrolysis, 2545–2556 cation-cation complexes, 2593–2596 complexation reaction kinetics, 2602–2606

Subject Index

I-31

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 complexes, 2577–2591 correlations, 2566–2577 in hydrosphere, 1808–1809 inner v. outer sphere, 2563–2566 redox reaction kinetics, 2597–2602 ternary complexes, 2591–2593 of actinium, 40, 41t of americium, 1338–1356, 1339t by carbonate, 1340–1341 hydrolysis, 1339–1340 by organic ligands, 1341, 1342t–1352t, 1353–1354, 1353f by others, 1354–1356 of berkelium, 1475–1479, 1477t–1478t of californium, 1549–1555, 1550t–1553t of dubnium, 1705 effect of, 2601–2602, 2602t of einsteinium, 1607–1609 of fermium, 1629 inner v. outer sphere, 2563–2566, 2566f, 2567t kinetics of, 2602–2606, 2605f, 2606t americium, 2604–2605 Eigen mechanism, 2602–2603 multidentate ligands, 2603–2604 simple v. complex, 2602 trivalent complexes, 2605–2606, 2605f, 2606t in mammalian body, 3340 of mendelevium, 1635 of plutonium, 1156–1182 carbonates, 1159–1166, 1160t–1161t carboxylates, 1176–1181, 1178t cation-cation, 1181–1182 halides, 1181 iodates, 1172–1173 nitrates, 1160t–1161t, 1167–1168 overview of, 1156–1158 oxalates, 1173–1175 oxoanions, 1158–1176 perchlorates, 1173 peroxide, 1175–1176 phosphates, 1160t–1161t, 1170–1172 sulfates, 1160t–1161t, 1168–1170 of seaborgium, 1710–1711 of thorium, 129–133, 130t coordination compounds for, 115 formation constants, 131, 132t inorganic ligands, 129–131, 130t solubility curves of, 129 stability constants, 129, 130t study of, 130–131 of transactinide elements, 1687–1689 Complexation enthalpy of complex halides, 2182, 2183t–2184t, 2185f of halides, 2578–2580, 2579t, 2581t

Composition-pressure-temperature relationship, of plutonium dioxide, 1031, 1031f Compreignacite at Shinkolobwe deposit, 273 uranium in, 259t–269t Condensed phase actinide thermodynamic properties in, 2115–2118, 2119t–2120t, 2121f entropy, 2115–2116, 2116f high-temperature properties, 2116–2118, 2117t, 2119t–2120t, 2121f energy levels and free-ion correlation with, 2037–2039, 2038t ion electronic structures in, 2036–2037 Configuration interaction (CI) of actinide elements, 1852 cyclopentadienyl complexes, 1958 for excited state energy calculations, 1910 for relativistic correlation effects, 1670 Congruently vaporizing composition (CVC), of uranium oxides, 365 Conversion chemistry, precipitation and crystallization for, of plutonium, 836–839 plutonium (III) oxalate precipitation, 836–837 plutonium (IV) oxalate precipitation, 837 plutonium (IV) peroxide precipitation, 837–838 Coordination chemistry of cyclopentadienyl complexes, trivalent, 2804 water in, 3096 Coordination compounds of berkelium, 1471 of neptunium, 745–750 structural chemistry of, 2436–2467 calixarenes, 2456–2463, 2457t–2458t, 2459f, 2461f–2463f with carboxylic acids, 2437–2448, 2438f, 2439t–2443t, 2443f–2447f crown ethers, 2448–2456 overview of, 2436–2437 porphyrins and phthalocyanines, 2463–2467, 2464t, 2466f–2467f of thorium, 114–115 ligands of, 115 properties of, 115 Coordination geometry in actinide complex bonding, 2558–2560, 2559f of americium, 1327, 1328f chalcogenides, 1358–1359 cyclopentadienyl and cyclooctatetraenyl compounds, 1363–1364 halides, 1356–1357, 1358f inorganic ligands, 1356–1361

I-32

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Coordination geometry (Contd.) nitrogen-donor ligands, 1363 others, 1361 oxides, 1357–1358, 1358f oxoanionic ligands, 1359–1360, 1360f oxygen-donor ligands, 1361–1362 pnictides, 1358–1359 silicides, 1359 sulfur-donor ligands, 1363 bond distance and oxidation states with, 3093 hexagonal bipyramidal of uranyl (V), 588–589 of uranyl (VI), 580–581, 580f, 582f–583f of neptunium in biological systems, 1814 metallic state, 719 pentagonal bipyramidal of uranyl (V), 589 of uranyl (VI), 580, 581f–582f peroxide complexes, of uranyl (VI), 583–584, 584f of plutonium, 883, 887t, 1112, 1157 anions, 1158–1159 six-coordination, of uranyl (VI), 582, 583f structure and, 579 of uranium hydroxide complexes, 600 uranium (III), 610 uranium (IV), 595, 610 uranium (V), 610 uranium (VI), 610 uranyl (VI), 580–584, 580f–584f, 3132 Copper spark method, for protactinium, 226 Copper, with thorium molybdates, 112 Coprecipitation bismuth phosphate for, 2634 of californium, 1547–1548 historical development of, 2627–2628 of mendelevium, 1633, 1635 methods of, 3281–3282 of neptunium, 716 for oxidation state extraction, 3287 of plutonium, 833–835 bismuth phosphate process, 835 lanthanum fluoride method for, 833–835 oxides with uranium oxides, 1074 for sample concentration, 3023 for separation, 2633–2634, 3281–3282 of uranium oxides with plutonium oxides, 1074 of uranyl ion, with iron-bearing mineral phases, 3168–3169 Core-level spectra, of plutonium, 861 Correlation crystal-field (CCF), Hamiltonian of, 2054–2055 Corrosion of curium metal, 1412

nitrogen in, 3212 of plutonium catalyzed, 3236–3237 dry, 3227–3228 hydrogen- and hydride-catlyzed, 977–979 kinetic behavior, 3225–3227 metal and intermetallic compounds of, 973–979, 3223–3238, 3226f, 3227t, 3229t salt-catalyzed, 3238 thermal ignition, 3232–3235 unalloyed, 3231–3232 by water vapor, 3228–3230 rates of, 3200–3201 plutonium metal, 3225–3226, 3226f of uranium with hydrogen, 3239–3242, 3240f, 3241t kinetics of, 3239–3246 metal, 327–328, 327t with oxygen, water, and air, 3242–3245, 3243f, 3244t uranyl with water, 3239 COUL. See Coulometry Coulomb repulsion, in actinide metals, 2325 Coulometry (COUL) for berkelium, 1484 for californium, 1548–1549 for environmental actinides, 3049t, 3052 for mendelevium, 1636 for neptunium, 757–759, 758f determination of, 790–791 Coulopotentiogram, of neptunium, 758–759, 758f Counter-current leaching, of uranium ore, 306 Coutinhoite, description of, 293 Covalency in actinide complex bonding, 2561–2562, 2563t in actinocene, 1948–1949, 1948f in plutonium, 1191–1192 dioxide, 1196–1199, 1197f, 1200f hexafluoride, 1193–1196 of uranium tetrachloride, 2249–2251 in uranocene, 2854, 2855f in uranyl ion, 1915–1916 CP. See Cupferron Critical mass, of americium, 1268 Critical parameters, plutonium–239, 820–821, 821t Cross-relaxation, of luminescence, 2103 Crown ether, complexes of, 2590 description of, 2448–2449 structural chemistry of, 2448–2456 Cryo On-Line Detector (COLD), for hassium study, 1713, 1714f Cryo-Thermochromatographic Separator (CTS), for hassium study, 1712–1713

Subject Index

I-33

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Crystal chemistry site distortion in, 2047 of uranium (IV), 281 Crystal morphology, prediction of uranium (IV) sheets, 286–287 Crystal structure. See also Structure of actinide elements metallic state, 1785–1787, 1786t solid compounds, 1798 of actinide metals, 2312–2313, 2312f, 2320 low-symmetry, 2330–2331, 2331t, 2369–2370 of actinocenes, 1943–1944, 1944t, 1945f Brillouin zones in, 2321 mechanical properties and, 968 of neptunium dioxide, 2287–2288, 2287f optimization of, 2048–2049 of plutonium, 879, 881t dioxide, 2289–2290 Crystal-field (CF), ground state of magnetic susceptibility and, 2226 uranium dioxide, 2274 Zeeman interaction and, 2225–2226 Crystal-field Hamiltonian corrections to, 2053–2056 ECM with, 2052–2053, 2053t free-ion Hamiltonian with, 2041 matrix element evaluation with, 2039–2042 parameters of, 2054–2055 initial, 2048 symmetry rules for, 2043 of trivalent ions, 2056 Crystal-field interactions of 5f1 compounds, 2242–2243 of 5f7 compounds, 2265 of actinide fluorides, 2071, 2073f of actinide ions, importance of, 2076 crystal field parameters empirical evaluation, 2047–2049 theoretical evaluation, 2049–2053 crystal-field Hamiltonian corrections to, 2053–2056 matrix element evaluation and, 2039–2042 free-ion and condensed phase correlation, 2036–2039, 2038t free-ion interactions with, 2044, 2062–2064, 2063t magnetic field with, 2044 modeling of, 2036–2056 symmetry rules, 2043–2047 tensor operators for, 2040 weak in crystals, 2055 Crystal-field operators geometric properties of, 2043 for ions, 2043–2044 Crystal-field parameters, 2044, 2045t accuracy of, 2047

calculation of, 2050–2052 computation of, 2058 effective-operator Hamiltonian with, 2050 empirical evaluation of, 2047–2049 expression of, 2051 free-ion states and, 2056 tetravalent ions, 2074 of neptunium dioxide, 2284 quantum mechanical calculations of, 2049 rank 2, 2051–2052 rank 4, 2052 rank 6, 2052 signs of, 2048–2049 theoretical evaluation, 2049–2053 of uranocene, 2253 Crystal-field splittings of 5f states of actinide ions, 2081, 2082f computation of, 2076 contributions to, 2054 of curium (III), 2266 of f-element spectroscopy, 2074–2075 of plutonium dioxide, 2288–2289 of tetravalent actinides, 2075–2076 of uranium dioxide, 2278–2279 tetrachloride, 2249 uranium (III), 2057–2058, 2057f uranium (IV), 2247–2248 Crystal-field theory for f-element ions in crystals, 2047–2048 for uranium dioxide, 2278, 2279f Crystallization of einsteinium, 1607 of mendelevium, 1636 of plutonium, 831–839 conversion chemistry, 836–839 precipitation v., 832–833 Crystallography, of organometallic actinide compounds, 1800 CTS. See Cryo-Thermochromatographic Separator Cupferron (CP), protactinium extraction with, 184 Cupferronates, of protactinium, gravimetric methods with, 230–231 Cuprosklodowskite at Shinkolobwe deposit, 273 uranium in, 259t–269t Curie law for 5f6 compounds, 2264 for magnetic susceptibility data, 2230 Curie-Weiss law for einsteinium (III), 2271 for magnetic susceptibility data, 2230–2231 of UBe13, 2342, 2343f for uranium (IV) compounds, 2254

I-34

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Curite anion topology of, 283, 284f–285f from clarkeite, 288 at Koongarra deposit, 273 uranium in, 259t–269t with uranium phosphates, 294 Curium, 1397–1434 analytical chemistry of, 1432–1434 analysis of, 1432–1433 separations, 1433–1434 aqueous chemistry of, 1424–1432 inorganic, 1424–1430, 1426t–1428t organic, 1426t–1428t, 1430–1432 atomic properties of, 1402–1406, 1403t absorption spectra, 1402–1404, 1404f–1405f electronic structure, 1404–1405 fluorescence spectroscopy, 1405–1406, 1406f in biological systems, ingestion and inhalation of, 1818–1820 complexes of cyclopentadienyl, 2803 tris-cyclopentadienyl, 2470–2476, 2472t–2473t compounds of, 1412–1424 chalcogenides, 1413t–1415t, 1420–1421 general, 1412–1416, 1413t–1415t halides, 1413t–1415t, 1417–1418 hydrides, 1413t–1415t, 1416–1417 organometallics, 1413t–1415t, 1423–1424 oxides, 1413t–1415t, 1419–1420 pnictides, 1413t–1415t, 1421 difficulty of working with, 1397–1398 discovery of, 5t, 8 half-life of, 1399t, 1400 history of, 8, 1397–1398 ionization potentials of, 1874t isotopes of, 9–10, 12, 1397–1400, 1399t lanthanide elements v., 2 magnetic properties of, 2355–2356 metallic state of, 1410–1412 chemical properties of, 1412 magnetic susceptibility, 2266, 2267t, 2268 physical properties of, 1410–1411, 1413t–1415t preparation of, 1411–1412 structure of, 2387–2388 natural occurrence of, in marine organisms, 1809 nuclear properties of, 1398–1400, 1399t oxidation states of, 1416, 2526 in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t in plutonium alloy δ-phase lattice, 930f, 931–932 elastic constants, 943

solubility ranges, 930, 930f thermal conductivity, 957 plutonium v., 935 production of, 1400–1402, 1758–1759 pyrochemical methods for, molten chlorides, 2700 quadrupole moments of, 1884, 1884f reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f separation and purification of, 1407–1410 from americium, 2672–2673 DDP, 2706 ion exchange, 1409–1410 precipitation, 1410 solvent extraction, 1407–1409 TALSPEAK for, 2672 synthesis of, 8–9 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f UO2 solid solutions with oxygen potentials of, 394–396, 395t properties of, 391t–392t, 392 Curium (II), 1430 stabilization of, 2077 Curium (III) absorption spectra of, 1402–1404, 1404f aqueous chemistry of, 1424–1432, 1426t–1428t chlorides of, magnetic data, 2229–2230, 2230t complexation of, 1424–1430, 1426t–1428t TTA, 2532 detection of limits to, 3071t TRLF, 3037 UVS, 3037 electronic structure of, 1404–1405 energy levels of, 2075–2076, 2075f energy levels, structure of, 2059–2061 excitation spectra of, 2061–2062, 2061f extraction of, 1431 aminopolycarboxylic acid, 1286 HDEHP, 1409 organophosphorus and carbamoylphosphonate reagents, 1276–1278 fluorescence decays of, 2101–2102, 2101f hydration numbers of, 2534, 2535f, 2535t–2536t in concentrated solutions, 2536–2538, 2537f

Subject Index

I-35

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 hydration of, 2528–2530, 2529f, 2529t hydrolytic behavior of, 2546, 2548t in hydrosphere, 1807–1810 luminescence of, 2096–2097, 2097f study of, 2098–2099 magnetic properties of, 2265–2268 in mammalian tissues circulation clearance of, 3368–3369, 3368f–3375f, 3371–3376 glycoproteins, 3410–3411, 3411t initial skeletal fractions of, 3349 transferrin binding to, 3365 oxidation of, 1416, 1429–1430 purification of from americium (III), 1410 zirconium based sorbents, 1409 separation from americium, 1271 solution reactions of, 1424–1425, 1425f speciation of, 3110, 3114t stability constants of, 1425, 1426t–1428t TRLF of, 2534–2535, 2536t Curium (IV) absorption spectra of, 1402–1404, 1405f complex of, 1416 electronic structure of, 1404–1405 excitation spectra of, 2068, 2071f magnetic properties of, 2263–2265 magnetic susceptibility of, 2264–2265 TIP of, 2263–2264 preparation of, 1429–1430 uranium (IV) v., coordination numbers, 585–586 Curium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Curium dioxide, 1413t–1415t, 1419 enthalpy of formation, 2136–2137, 2137t, 2138f heat capacity of, 2138–2141, 2139f, 2142t IPNS of, 2292–2293 magnetic properties of, 2292–2293 magnetic susceptibility of, 2293 structure of, 2397 Curium hydrides entropy of, 2188, 2189t formation enthalpy of, 2187–2188, 2187t, 2189t, 2190f high-temperature properties of, 2188–2190, 2190t structure of, 2404 Curium monoxide dissociative energy of, 2149–2150, 2150f structure of, 2396 Curium nitrate, 1413t–1415t, 1422 Curium oxalate, 1413t–1415t, 1419, 1421–1422 Curium oxides, structure of, 2396–2397 Curium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Curium oxysulfate, 1413t–1415t, 1420

Curium peroxide, in americium separation, 1271 Curium phosphates, 1413t–1415t, 1422 structural chemistry of, 2430–2433, 2431t–2432t Curium pnictides, structure of, 2409–2414, 2410t–2411t Curium sesquioxide, 1413t–1415t, 1419–1420 formation enthalpy of, 2143–2146, 2144t, 2145f in gas-phase, 2148t, 2149 high-temperature properties of, 2139f, 2146–2147 structure of, 2396–2397, 2396t Curium sesquiselenide, 1413t–1415t, 1420 Curium sesquisulfide, 1413t–1415t, 1420 Curium sulfate, 1413t–1415t, 1422 Curium tetrafluoride, 1413t–1415t, 1418 Curium tetrahalides, structural chemistry of, 2416, 2418t Curium tribromide, 1413t–1415t, 1417–1418 Curium trichloride, 1413t–1415t, 1417 Curium trifluoride, 1413t–1415t, 1417 Curium trihalides, structural chemistry of, 2416, 2417t Curium trihydroxide, 1413t–1415t, 1421 Curium–242 alpha decay of, 1432 from americium–242, 1759 applications of, 1398–1400 californium–244 from, 1499 detection of, limits to, 3071t heat output of, 1398 history of, 1397–1398 nuclear properties of, 3277t plutonium–238 from, 817 production of, 1401–1402 solutions of, 1424–1425, 1425f study of, 1765 Curium–243 alpha decay of, 1432 detection of, αS, 3296 nuclear properties of, 3277t Curium–244 alpha decay of, 1432 from americium–244, 1759 applications of, 1398–1400 detection of ICPMS, 3328 limits to, 3071t αS, 3296 half-life of, 1759 heat output of, 1398 history of, 1398 isolation of, 1401–1402 nobelium from, 1636–1637 nuclear properties of, 3277t plutonium–240 from, 862

I-36

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Curium–244 (Contd.) production of, 1400–1401 radioactivity of, 1759 study of, 1765 Curium–245, production of, 1400–1401 Curium–246, production of, 1400 Curium–247, production of, 1400 Curium–248 berkelium alloy with, 1462 from californium–252, 1505 for hassium production, 1713 history of, 1398 lawrencium from, 1641 neutron emission from, 1505 production of, 1400–1401 study of, 1765–1766 for transactinide element production, 1661–1662 Curium–249, decay of, 1447 Curium–252, detection of, NAA, 3055–3057, 3056t, 3058f Cyanates, of actinide elements, 1796 Cyanex 301 americium (III) extraction with, 1287–1289, 1288f, 2675–2676 concerns of, 1288–1289 disadvantages of, 1289 for solvent extraction, 2665 trivalent actinide/lanthanide separation, 2762–2763 Cyanides, of actinide elements, 1796 Cycloheptatrienyl complexes, of uranium, 2253–2254 Cycloheptatrienyl ligand, 2860–2862 bonding in, 2862, 2863f formation of, 2860–2861 structure of, 2861–2862, 2862f Cyclooctadienyl compounds, americium ligands of, 1363–1364 Cyclooctatetraene complexes of americium, 1323t, 1324 of plutonium, 1188–1189 structural chemistry of, 2485–2487, 2488t, 2489f Cyclooctatetraenyl complexes, 2851–2858 americium ligands of, 1363–1364 bonding in, 2853–2854, 2854f bridging in, 2857, 2857f cationic derivatives of, 2857–2858 chemistry of, 2851, 2856–2857 electron transfer rates in, 2856 metathesis reactions, 2857 pentavalent, 2858 ring dynamics of, 2854–2855 single ring, 2856–2857 synthesis of, 2851–2852 trivalent derivatives of, 2855–2856 uranocene derivatives, 2851–2853, 2852f

Cyclooctatetraene compounds, of neptunium, 751–752 Cyclopentadiene complexes, of americium, 1323t, 1324 Cyclopentadienyl complexes, 2800–2851 of actinide elements, 1801–1803, 1952–1959 3 ligands þ X, 1956–1957 4 ligands, 1953–1954 ‘base-free’ 3-ligand, 1954–1956, 1955f metal-metal bonds, 1958–1959 mixed ligands, 1957–1958 overview of, 1952–1953, 1953f structure of, 1953, 1953f of berkelium, 1464t–1465t, 1471 bimetallic complexes and, 2890 of californium, 1544 dicarbollide complexes v., 2868 hexavalent, 2847–2851 adamantylimido complex, 2850 bis(imido), 2848–2850 geometry of, 2847–2848 heteroatom substitution, 2850–2851 prevalence of, 2847 reactivity of, 2847–2850 structure of, 2847, 2849f synthesis of, 2847–2849, 2848f of neptunium, 750–751 pentavalent, 2845–2847 electronic structure, 2847 preparation of, 2845–2847, 2846f prevalence of, 2845 structure of, 2846f, 2847 phospholyl complexes v., 2869 of plutonium, 1189–1191 pyrazolylborate v., 2880 structural chemistry of, 2468–2485 bis, 2476–2482, 2478f, 2479t–2480t, 2481f–2483f mono, 2482–2485, 2484t, 2485f–2487f tetrakis, 2469, 2469t, 2470f tris, 2470–2476, 2472t–2473t, 2474f–2475f, 2477f tetravalent, 2814–2845 alkali metal reagents, 2844 alkyl or aryl ligands, 2539f, 2819–2820, 2820f, 2837–2839 amide complexes, 2832 bis(indenyl) complex, 2827 bonding and structure of, 2815–2817, 2816f, 2816t, 2818f carbon dioxide reactions, 2824 carbon monoxide reactions, 2821–2824 cationic species, 2818–2819 chalcogenide complexes, 2837 dialkyl complexes, 2840 Group 14 derivatives, 2820–2821 history of, 2815 importance of, 2814–2815

Subject Index

I-37

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 indenyl complexes, 2844 isocyanide ligand insertion, 2825, 2826f metal-carbon bond in, 2825–2826 metathesis and protonation routes for, 2819, 2831–2833, 2845 mono-ring complexes, 2843–2844 organoimido complexes, 2833–2835 pentamethyl- ligand, 2827–2829, 2829f phosphide complexes, 2832–2833 phosphine imide complex, 2825 phosphinidene complexes, 2833, 2834f–2835f, 2835 phosphorylide complex, 2826, 2828f polypnictide complexes, 2836 pyrazole adduct, 2830 reaction patterns, 2841–2843, 2842f reactions for, 2817–2818 stabilization of, 2829–2830, 2831f thermochemistry, 2821, 2822t, 2840–2841, 2840t thiolate complexes, 2836–2837 of thorium, 116 trivalent, 2800–2814 anionic reactions of, 2806 cationic complex, 2812 chalcogen transfer reagents, 2808 coordination chemistry of, 2804 dimeric, 2812, 2813f dioxygen reaction, 2808 electronic structure of, 2803 metal-to-ligand donation, 2806, 2807f monomeric adducts, 2810–2812, 2811f oxidation reactions, 2807–2809, 2814 permethylated, 2803–2804 reduction of, 2801–2802 solubility of, 2802 starting material for, 2802 structure of, 2802 synthesis of, 2800–2801, 2801t, 2803 trimeric, 2809–2810 of uranium (III), 2812, 2813f uranium triiodide THF, 2813–2814 D2EHIBA. See Di–2-ethylhexyl isobutylamide DAAP. See Diamyl(amyl)phosphonate Damage recovery, of plutonium, 982–983, 983f Darmstadtium chemical methods for, 1720–1721 chemical properties of, 1717–1721 discovery of, 6t, 1653 electronic structures of, 1682–1684 half-life of, 1719 isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659

oxidation states of, 1720 production of, 1719–1720 relativistic orbital energies for, 1669f solution chemistry of complexation of, 1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f Darmstadtium–292, half-life of, 1736 Dating, with protactinium–231, 231 and thorium–230, 170–171 and uranium–235, 189 DBBP. See Dibutyl butylphosphonate DBM. See Dibenzoylmethane DCB. See Dirac-Coulomb-Breit Hamiltonian DCTA. See 1,2-Diaminocyclohexane tetraacetic acid DDCP. See Dibutyl-N,Ndiethylcarbamylphosphonate DDP. See Dimitrovgrad Dry Process de Haas-van Alphen frequencies, of UIr3, 2334, 2335f 4n þ 2 decay chain thorium–230 from, 53 thorium–234 from, 53 uranium–238 in, 255–256 Decay chains of actinium, 20–26, 21f–26f of berkelium–249, 1447 of berkelium–250, 1447 of bohrium–267, 1711 of einsteinium–253, 1447 of hassium–269, 1714 of hassium–270, 1714 of plutonium, 1143–1146 of uranium, 21f Decay process, heat generation in, 985–986 Decomposition acid, 3279–3281 fusion, 3278–3279 for trace analysis, 3278–3281 Decontamination, of irradiated nuclear fuel, 826, 828–830 DEH. See N,N-Diethyl hydroxylamine Delayed neutron activation analysis (DNAA), for environmental actinides, 3056t, 3057 δ-Phase, of plutonium, 882–883, 882f–883f, 886f 5f-electrons, 925 atomic volume, 923, 923f density of, 935–937, 936t DFT predictions of, 2329–2330, 2330f diffusion rate, 958–960, 959t, 961f elastic constants, 942–943, 944t, 946f electrical resistivity of, 955–957, 955f–956f, 2345–2347, 2346f field expansion, 892–897 heat capacity, 945–947, 950t–951t

I-38

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 δ-Phase, of plutonium (Contd.) heavy-fermion behavior of, 2342 lattice changes in, 981–982, 982f, 982t, 984 magnetic properties of, 2355 magnetic susceptibility, 949, 953–954, 953f microsegregation, 899, 916–917 phase transformations, 917–921, 918f–920f self-irradiation defects in, 986 solid solubility of, 927 solubility ranges of, 930, 930f stability and alloying of, 928–929 strength of, 968f, 970–971 thermal conductivity, 957 thermal expansion, 938t, 939–942, 940f thermoelectric power, 957–958, 958t uranium and neptunium influence on, 985 Demesmaekerite, as uranyl selenite, 298 Density functional theory (DFT) of actinide metals, 2326–2328 of actinocenes, 1947–1948 basis of, 1903 charge density with, 2330 δ-phase plutonium and, 925, 929, 2329–2330, 2330f developments of, 1904 electronic structure and bonding properties with, 923–924 for ground state properties calculation, 1671 in HF calculations, 1903 of neptunium neptunium (III), 3116 neptunium (VII/VI), 3125 for thorium, 3105 total energy functional of, 2327–2328 of uranium dioxide, 1973 hexafluoride, 1935–1937, 1936t of uranyl, 1920–1921 hydroxide complexes, 1925 Density, of plutonium, 935–937, 936t oxides with uranium oxides, 1075–1076 Density of states (DOS) of actinide metals, 2318f, 2319 description of, 2316–2317 Fermi-Dirac distribution function with, 2320 of UIr3, 2338, 2338f Depleted uranium (DU) description of, 1755 in environment, 3173–3174 scope of concern of, 3202 Derriksite, as uranyl selenite, 298 Descent-of-symmetry method complications of, 2046 use of, 2044 Desferrioxamine (DFO) as chelating agents, 3414

iron removal with, 1824 for plutonium removal, with DTPA, 1824 Deuterides, of plutonium, 989–996 applications, 995–996, 996f electronic structure of, 995, 995t history of, 989 physical properties of, 990, 995, 995t preparation and reactivity of, 989–990 solid state structures, 992–994, 993f, 993t stoichiometry and phase relationships, 990–992, 991f–992f storage and handling of, 989 Dewar-Chatt-Duncanson model, of synergic bonding, 1956 Dewindite, description of, 297 DF. See Dirac-Fock DΦDBuCMPO. See Diphenyl-N,Ndibutylcarbamoylmethylenephosphine oxide DF-LCAO. See Dirac-Fock linear combination of atomic orbitals DFO. See Desferrioxamine DFT. See Density functional theory DHDECMP. See Dihexyl-N,Ndiethylcarbamoylmethyl phosphonate DHHA. See Di-n-hexyl hexanamide Di–2-ethylhexyl isobutylamide (D2EHIBA) protactinium extraction with, 184 for THOREX process, 2736 Dialkyl complexes, with cyclopentadienyl, 2840 Dialysis, for sample concentration, 3023 DIAMEX process, for actinide extraction, 1769, 2657–2658 Diamide extractants actinide extraction with, 1285–1286, 1408 overview of, 1285 1,2-Diaminocyclohexane tetraacetic acid (DCTA) fermium complexes with, 1629 mendelevium complexes with, 1635 Diamyl(amyl)phosphonate (DAAP) for THOREX process, 2736 in U/TEVA•Spec, 3284 1,3-Diazidobenzene, cyclopentadienyl complex reaction with, 2809, 2810f 1,4-Diazidobenzene, cyclopentadienyl complex reaction with, 2809, 2810f DIBC, protactinium extraction with, 182, 188 Dibenzoylmethane (DBM), actinide extraction with, 3287 Dibenzyl sulfoxide, for protactinium extraction, 181–182 DIBK, protactinium extraction with, 182 Dibutyl butylphosphonate (DBBP), americium extraction with, 1274 Dibutyl-N,N-diethylcarbamylphosphonate (DDCP), extraction with, 3282

Subject Index

I-39

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Dibutylphosphoric acid (HDBP), separation with, 2650 Dicarbollide ligands, 2868–2869 cyclopentadienyl v., 2868 generation of, 2868–2869 geometry of, 2868 Dicarboxylic acids, in plasma, 3360–3361 5,7-Dichloro–8-hydroxyquinoline, californium extraction with, 1513 DIDPA. See Diisodecylphosphoric acid N,N-Diethyl hydroxylamine (DEH), neptunium (VI) reduction with, 761 Diethylenetriamine pentaacetate (DTPA) americium separation with, 2671–2672 in bone binding study, 3408–3409 as chelating agent, 3413–3114 curium separation with, 1409, 2672 extraction with, 3282 plutonium complex with, 1176–1177, 1178t, 1179–1181 for removal, 1823 for plutonium removal, with DFO, 1824 separation with, 2640–2641 Differential pulse polarography (DPP), for environmental actinides, 3049t, 3052, 3053f Differential pulse voltammetry (DPV), for environmental actinides, 3049t, 3052, 3053f Diffusion rates of einsteinium, 1606 of plutonium, 958–960, 959t Diglycolamides, for solvating extractant system, 2659–2660 Dihalides structural chemistry of, 2415–2416 thermodynamic properties of, 2178–2179, 2180t–2181t, 2181f gaseous, 2179 solid, 2178–2179 Dihexyl-N,N-diethylcarbamoylmethyl phosphonate (DHDECMP) in actinide production, 2737–2738 americium extraction with, 1277–1278 extractant comparison with, 2763–2764, 2763t in solvating extractant system, 2655, 2656t Di-isobutylketone (DIPK), protactinium extraction with, 176, 178, 182, 188 Diisodecylphosphoric acid (DIDPA) actinide extraction with, 2753–2756 flow sheet for, 2755, 2755f overview of, 2753–2755, 2755f tests for, 2755–2756 americium extraction with, 1276 extractant comparison with, 2763–2764, 2763t neptunium extraction with, 713

Di-isopropylcarbinol (DIPC), protactinium extraction with, 175 β-Diketone complexes of actinide elements, 1783 of californium, 1554 of fermium, 1629 for oxidation state speciation, 2726 separation with, 2632, 2680 TTA v., 2650 Dimethyl oxalate, actinium precipitation with, 38 Dimethyl sulfoxide (DMSO), for protactinium extraction, 181–182 1,1-Dimethylhydrazine (DMHz), neptunium (VI) reduction with, 761 N,N-Dimethyl-N0 ,N0 -dibutyl–2hexoxyethylmalonamide, actinide extraction with, 1769 N,N-Dimethyl-N,N-dibutyl–2-tetradecyl malonamide (DMDBTDMA) actinide extraction with, 1285–1286, 2658–2659, 2756 extractant comparison with, 2763–2764, 2763t N,N0 -Dimethyl-N,N0 -dibutyldodecyloxyethyl malonamide (DMDBDDEMA), actinide extraction with, 2658 N,N0 -Dimethyl-N,N0 -dioctylhexyloxyethyl malonamide (DMDOHEMA), actinide extraction with, 2658 Dimitrovgrad Dry Process (DDP) applications, separation efficiency in, 2707–2708 dissolution for, 2705 minor actinide behavior in, 2706–2707, 2707f for MOX fuel reprocessing, 2692–2693 uranium and plutonium recovery, 2705–2706 Di-n-hexyl hexanamide (DHHA), for THOREX process, 2736 Dinonylnapthalene sulfonic acid (HDNNS), americum extraction with, 1286–1287, 2673–2675, 2674t Dioxide dichloride, of uranium, 567–570 Dioxides magnetic properties of, 2272–2294 americium, 2291–2292 curium, 2292–2293 neptunium, 2282–2288 plutonium, 2288–2290 uranium, 2272–2282 of plutonium, reactions of, 3219–3222 thermodynamic properties of, 2136–2143 enthalpy of formation, 2136–2137, 2137t, 2138f entropy, 2137–2138

I-40

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Dioxides (Contd.) high-temperature properties, 2138–2141, 2139f, 2142t nonstoichiometry, 2141–2143 Dioxouranium (V), aqua ions of, 594t, 595 Dioxouranium (VI), aqua ions of, 594t, 596, 596f DIPC. See Di-isopropylcarbinol DIPEX resin for americium extraction, 1294 for separation, 3284–3285 Diphenyl sulfoxide, for protactinium extraction, 181–182 Diphenyl-N,Ndibutylcarbamoylmethylenephosphine oxide (DΦDBuCMPO), in TRUEX process, 1283, 2739 Diphonix resin for actinide extraction, 716 for americium extraction, 1293–1294 for ion exchange, 2642–2643, 2643f Dipicolinates, structural chemistry of, 2441t–2443t, 2446–2447, 2446f Dipivaloylmethanato complex, of californium, 1541 DIPK. See Di-isobutylketone Dirac equation, for relativistic methods, 1904–1905 Dirac-Coulomb-Breit (DCB) Hamiltonian, for relativistic treatments, 1670 Dirac-Fock (DF) for electronic structure calculation, 1670, 1900 element 113–184 ground state configurations, 1722, 1722t RECPs with, 1907–1908 Dirac-Fock linear combination of atomic orbitals (DF-LCAO), for electronic structure calculation, 1670–1671 Dirac-Hartree-Fock calculations, on uranyl, 1917–1918 Dirac-HF methods, equations for, 1905 Dirac-Kohn-Sham methods, equations for, 1905 Dirac-Slater discrete-variational method (DS-DV method), for electronic structure calculation, 1671 Dirac-Slater (DS) method, for electronic structure calculation, 1670 Direct oxide reduction (DOR) MSE v., 869 for plutonium metal production, 866–869, 868f–869f furnace for, 868f process for, 866–868 results of, 868–869, 869f

in pyroprocessing, 2694 pyroredox v., 875 use of, 2692 Di-S-butylphenyl phosphonate (DSBPP), uranium extraction with, 175 Disposition options for, 3262–3266 interim storage, 3266 issues of, 3262–3263 metals and oxides, 3263–3266 of plutonium, 3199–3266 by ceramification, 3265–3266 immobilization, 3264 metal, 3263 as MOX fuel, 3263–3264 by vitrification, 3265 of uranium, 3199–3266 Disproportionation reactions of actinide complexes, 2600–2601, 2600t of americium, 1331–1332 redox behavior v., 2601 Dissimilatory metal-reduction bacteria (DMRB), redox behavior of, 3178, 3181 Dissociative energy, of actinide monoxides, 2149–2150, 2150f Dissolution, in RTILs, 2690 Distribution coefficients for americium purification, 1290 of californium, 1554 of fission products, 842, 842t of lawrencium, 1645 Dithiophosphinic acids, as trivalent actinide and lanthanide separating agent, 1289, 1408, 2676 DMDBDDEMA. See N,N0 -Dimethyl-N,N0 dibutyldodecyloxyethyl malonamide DMDBTDMA. See N,N-Dimethyl-N,Ndibutyl–2-tetradecyl malonamide DMDOHEMA. See N,N0 -Dimethyl-N,N0 dioctylhexyloxyethyl malonamide DMFT. See Dynamical mean-field theory DMHz. See 1,1-Dimethylhydrazine DMRB. See Dissimilatory metal-reduction bacteria DMSO. See Dimethyl sulfoxide DNA footprinting, photochemical oxidation for, 630–631 DNAA. See Delayed neutron activation analysis Dolomite, uranium in, 3160 DOR. See Direct oxide reduction DOS. See Density of states Double groups, for electronic structure calculations, 1910–1914 Double perovskites, solid state structures of, 1060t–1061t, 1062–1063, 1063f

Subject Index

I-41

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Dowex 1, for separation, 2636, 2636f Dowex 50 actinide elution with, 1624, 1625f for actinium purification, 30–31 for californium purification, 1508 for curium separation, 1433–1434 for fermium separation, 1624 for nobelium purification, 1639 for separation, 2636–2638, 2637f Dowex–1 anion-exchange column, protactinium separation on, 180, 180f DPP. See Differential pulse polarography DPV. See Differential pulse voltammetry DS method. See Dirac-Slater method DSBPP. See Di-S-butylphenyl phosphonate DS-DV method. See Dirac-Slater discretevariational method DTPA. See Diethylenetriamine pentaacetate DU. See Depleted uranium Dubna seaborgium production at, 1706–1707 transactinide element claims of LBNL v., 1659–1660 Dubnium chemical properties of, 1666, 1691t, 1703–1706 discovery of, 6t, 1653, 1653t electronic structures of, 1676–1682, 1677f–1678f, 1680t–1681t, 1682f gas-phase chemistry of, 1705–1706 history of, 1703 ionic radii of, 1674f, 1675–1676, 1676t ionization potential of, 1674, 1674f isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, in aqueous solution, 1774–1776, 1775t relativistic effects in, 1666–1667, 1667f relativistic orbital energies for, 1669f solution chemistry of, 1703–1705 complexation of, 1688–1689 hydrolysis, 1686–1687, 1687t oxidation states of, 1703–1704 redox potentials, 1685–1686, 1685f–1686f volatility of, 1664 Dubnium–258, chemical properties of, 1666 Dubnium–260 lawrencium–256 from, 1644 from meitnerium–268, 1717 Dubnium–261, study of, 1703 Dubnium–262, gas-phase chemistry of, 1705–1706 Dynamical mean-field theory (DMFT) plutonium magnetism with, 2355 SIM v., 2344 Dysprosium, californium v., 1545

ECF. See Extracellular fluid ECM. See Exchange charge model ECPs. See Effective core potentials EDL. See Electrodeless discharge lamp EDS. See Energy-dispersed X-ray spectroscopy EDTA. See Ethylenediaminetetraacetate EELS. See Electron energy loss spectroscopy Effective core potentials (ECPs), for scalarrelativistic methods, 1906–1907 Effective mass, of actinide metals, 2319–2322 Effective moment, for magnetic susceptibility data, 2230–2231 Effective-operator Hamiltonian, 2026–2030 corrective terms for, 2029–2030, 2055 crystal field parameters with, 2050 crystal field theory with, 2036–2037 expansion with CCF, 2054–2055 free-ion parameters in, 2071–2072, 2073f for penta- and hexavalent actinides, 2080–2081 use of, 2030 EHEH. See N,N-Ethyl (hydroethyl) hydroxylamine Eigen mechanism, in complexation, 2602–2603 Eigenfunctions of crystal field level, 2041–2042 free-ion, 2042 magnetic data for, 2226 magnetic susceptibility for, 2226 for N-electron ion, 2022 Eigen-Wilkins mechanism ligand substitution and, 608–610 organic and inorganic ligand formation and, 615–616 Einsteinium, 1577–1613 atomic and ionic radii, and promotion energies, 1612–1613 complete spectrum of, 1872–1873 compounds of, 1594–1612 crystal data, 1594–1600, 1596t oxychloride, 1595 sesquioxide, 1595–1599 solids other results of, 1602–1603 solids spectrometry of, 1600–1602, 1601f solutions related studies, 1605–1609, 1606t solutions spectrometry of, 1604–1605, 1604f trichloride, 1595 in vapor state, 1609–1612 discovery of, 5t, 9, 1577, 1761 in electrodeless lamps, 1885–1886, 1885f electronic properties and structure of, 1586–1588, 1587f, 1589t–1590t, 1864–1865, 1864f fermium separation from, 1624–1625

I-42

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Einsteinium (Contd.) half-life of, 1579 ionization potentials of, 1588, 1590f, 1874t isotopes of, 10, 1579, 1581t, 1582 lanthanide elements v., 2 metallic state of, 1588–1594, 1591t alloys of, 1592–1593 other actinide metals v., 1591–1592, 1591t production of, 1590, 1593–1594 properties of, 1590–1591, 1591t structure of, 2388 thermodynamic properties of, 1592–1593 nuclear properties, 1580–1583, 1581t oxidation states of, 2526 in aqueous solution, 1774–1776, 1775t production of, 1577–1578, 1580–1583 purification and isolation, 1583–1585 chromatographic methods for, 1583–1584 overview of, 1583 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f synthesis of, 9 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f Einsteinium (III) absorption spectra of, 1604–1605, 1604f hydration of, 2528–2530, 2529f, 2529t hydrolytic behavior of, 2546, 2548t interaction parameters of, 2062–2064, 2063t ionic radius of, 1613 magnetic properties of, 2271 in mammalian tissues circulation clearance of, 3368–3369, 3368f–3375f, 3371–3376 initial skeletal fractions of, 3349 reduction of, 1602 Einsteinium (I), atomic properties of, 1588, 1589t Einsteinium (VI), existence of, 1611 Einsteinium (II), magnetic properties of, 2271–2272 Einsteinium oxides, structure of, 2399, 2399t Einsteinium oxychloride, 1595, 1596t Einsteinium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Einsteinium sesquioxide, 1595–1599 bond dissociation of, 1611 electron diffraction pattern of, 1597, 1597f formation enthalpy of, 2143–2146, 2144t, 2145f

lanthanides v., 1613 production of, 1595–1597 properties of, 1596t, 1597–1598, 1599f self-irradiation and, 1598 structure of, 1598–1599, 2399, 2399t Einsteinium tetrafluoride, formation of, 1611–1612 Einsteinium tribromide, 1599 Einsteinium trichloride, 1595, 1596t Einsteinium trifluoride, tetrafluoride from, 1611–1612 Einsteinium trihalides, structural chemistry of, 2416, 2417t Einsteinium–253 atomic properties of, 1588, 1589t–1590t in borosilicate glass, 1601–1602, 1602f–1603f from californium–253, 1504 decay of, 1447 discovery of, 1580 half-life of, 1580 mendelevium–256 from, 1630–1631 production of, 1582–1583 in rutherfordium extraction, 1700 from rutherfordium–261, 1695 Einsteinium–254 production of, 1582–1583 thermochromatography of, 1611–1612 Einsteinium–255 discovery of, 1580 fermium–255 from, 1622 half-life of, 1580 production of, 1582–1583 Eisenstein-Pryce theory, optical transitions to, 2227t Ekanite, structural data for, 113 Elastic constants of plutonium, 942–943, 944t, 945f–946f role of, 943 Elastic recoil detection analysis (ERDA), for environmental actinides, 3059t, 3065 Eldorado mine, uraninite at, 274 Electrical conductivity, of uranium, oxides, 368–369 Electrical properties of plutonium hydrides, 3205 of uranium metal, 324, 324f, 324t Electrical resistivity of actinide metals, 2309, 2310f, 2324 of americium, 1298t, 1299 of Fermi liquid, 2340–2341, 2341f of plutonium, 954–957, 954f–956f, 2345–2347, 2346f δ-phase, 955–957, 955f–956f unalloyed, 954–955, 954f of UBe13, 2342, 2343f of uranium hydrides, 333 metallic state, 322

Subject Index

I-43

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Electrochemical methods for neptunium determination of, 790–792 electrolysis, 761–762 for protactinium, 227 gravimetric methods, 229–231 polarographic, 227 potentiometric and amperometric, 227 spectrophotometric methods, 227–228 Electrochemical separation, of uranium, 632–633 Electrode potentials of actinide ions, 2127–2131, 2130f–2131f of americium, 1328–1330, 1329t of einsteinium, 1606 of element 113, 1725 Electrodeless discharge lamp (EDL) for actinide spectroscopy, 1839 design and construction of, 1839, 1885–1886, 1885f Electrodeposition of neptunium, 717 in RTILs, 2690–2691 Electrolysis of actinium, 38 of neptunium, 761–762 of protactinium, 220 of thorium, 60–61 Electrolytes, plasma and urine concentrations of, 3356–3357, 3357t Electrolytic behavior, of neptunium, 755–759 coulometric behavior, 757–759, 758f voltammetric behavior, 755–757, 756t, 757f Electromagnetic separation, of plutonium isotopes, 821–822 Electrometallurgical technology (EMT) overview of, 2693 in pyroprocessing, 2694 Electron behavior in actinides, 1–2 parameters for, 2054 Electron diffraction techniques, for einsteinium, 1595–1598, 1597f Electron energy loss spectroscopy (EELS), for environmental actinides, 3049t, 3051–3052 Electron exchange reactions, of actinide complexes, 2597–2598 Electron microprobe analysis (EMPA), for environmental actinides, 3049t, 3050 Electron microscopy, for actinide element study, 14 Electron paramagnetic resonance (EPR) of 5f1 compounds, 2241 of 5f7 compounds, 2265 actinide ion measurements with, 2226 of americium

americium (IV), 2263 dioxide, 2292 of californium (III), 2269 of cyclopentadienyl complexes, trivalent, 2803 of einsteinium, 1602 einsteinium (II), 2272 for electronic structure, 1770 Kramers degeneracy and, 2228 of neptunium hexafluoride, 2243 tetrachloride, 2258t, 2261 neutron scattering v., 2232 non-Kramers degeneracy and, 2228 of organouranium (V) complexes, 2246 of plutonium (III), 2262–2263 of thorium dioxide, 2265 thorium (III), 2240 of uranium bis-cycloheptatrienyl, 2246 tris-cyclopentadienyl, 2259, 2259t uranium (III), 2259 Electron repulsion, spin-orbit coupling v., 1928–1929 Electron transfer rates, in cyclooctatetraenyl complexes, 2856 Electron-electron correlations in actinide metals, 2325–2326 Fermi surface in, 2334 Hartree term and, 2328 Electronic energies of berkelium, 1452–1453 of californium, 1513–1515, 1514t Electronic spectra. See also Absorption spectra of actinides, 1950–1951 of berkelium, 1475 of plutonium, ions, 1113–1114, 1115f of uranium dioxide, 1973 Electronic structures of actinide compounds, 1893–1998 actinyl ions and oxo complexes, 1914–1933 divalent, 2024, 2024t halide complexes, 1933–1942 matrix-isolated, 1967–1991 organometallics, 1942–1967 relativistic approaches, 1902–1914 speciated ions, 1991–1992 tetravalent, 2024, 2024t trivalent, 2024, 2024t unsupported metal-metal bonds, 1993–1994 of actinide elements, 1770–1773, 1842t–1850t, 1851–1860, 1851f, 1894–1897, 1896f–1897f, 1896t–1897t

I-44

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Electronic structures (Contd.) charge-transfer transitions and actinyl structures, 2085–2089 configuration, 1771–1773, 1772t, 1773f crystal-field interaction, 2036–2056 determination of, 1858–1860, 1860f divalent, 2077–2079 energies of, 1853–1858, 1854f, 1855t, 1856f, 1859f free-ion interactions, 2020–2036 general considerations, 1770 metallic state, 1788–1789, 1789f penta- and hexavalent, 2079–2085, 2080t periodic table position, 1773, 1774f redox potentials v., 1859–1860, 1860f relative energies, 2016–2020 relativistic approaches to, 1902–1914 spectroscopic studies, 1770–1771 structure, 1771–1773, 1772t, 1773f tetravalent, 2064–2076 theoretical term structure, 1860–1862 trivalent, 2056–2064 of actinide metals, 2318–2319, 2318f of actinocenes, 1946–1948 of americium, 1295 of berkelium, 1452–1453, 1461 berkelium (III), 1445 of curium curium (III), 1404–1405 curium (IV), 1404–1405 of cyclopentadienyl complexes pentavalent, 2847 trivalent, 2803 DFT for, 923–924 of dubnium, 1703 of einsteinium, 1586–1588 of element 113, 1722t, 1723–1725 of element 114, 1722t, 1725–1727 of element 115, 1722t, 1727–1728 of fullerenes, 2864–2865 of ion in condensed-phase medium, 2036–2037 Kramers degeneracy, 2228 of lawrencium, 1643 of mendelevium, 1633–1634, 1634t of 5f orbital, determination of, 2019–2020 of 6d orbital, determination of, 2020 of plutonium, 857, 921–935, 922–923, 923f, 1191–1203 alloy theory and modeling, 925–929, 926f α-phase, 923–924, 923f δ-phase, 923f, 925 hydrides and deuterides, 995, 995t ionic and covalent bonding models, 1191–1192 lattice effects and local structure, 930–935 novel interactions of, 921–922, 922f

plutonium dioxide, 1044, 1196–1199, 1197f, 1976 plutonium hexafluoride, 1194–1196, 1195f pnictides, 1023 radial probability densities, 1192, 1193f specific examples, 1192–1203 of thorium, 1869, 1870t carbide oxide, 1982, 1983t of transactinide elements calculation of, 1670 gas-phase compounds, 1676–1684, 1677f–1678f, 1680t–1681t, 1682f of tris(amidoamine) complexes, 2888 of uranium carbide oxide, 1977–1978, 1977t, 1982, 1983t metallic state, 2318–2319, 2318f uranium dioxide, 1973 uranyl ion, 1915 Electronic transition spectroscopy, for electronic structure, 1770–1771 Electronic transitions in actinocenes, 1949–1952 protactinocene, 1949–1951 thorocene and uranocene, 1951–1952 radiative and nonradiative, 2089–2103 5f–5f transitions, 2089–2093 fluorescence lifetimes, 2093–2095 ion-ion interaction and energy transfer, 2101–2103 nonradiative phonon relaxation, 2095–2100 Electronic transport, and magnetism, 2367–2368 Electron-nuclear double resonance (ENDOR) fluorine structure measurement by, 2243 of uranium bis-cycloheptatrienyl, 2246 Electroplating, for sample concentration, 3023–3024 Electrorecovery, of actinide elements, 2719–2721 Electrorefining (ER), 2712–2717 electro-transport in, 2714–2715 historical development of, 2712–2713 IFR and, 2713 reprocessing in, 2713–2714 for plutonium metal production, 870–872, 873f–875f equipment for, 871–872, 873f–874f process for, 870 product of, 872, 875f pyroredox after, 872–876 use of, 2692 separation efficiencies in, 2715–2717, 2718t Electrospray ionization mass spectroscopy (ESMS), for environmental actinides, 3049t, 3052–3055, 3054f

Subject Index

I-45

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Electrostatic concentration methods, for uranium ore, 303 Electrostatic integrals, of actinide elements, 1862–1863 divalent and 5þ valent, 2076 Electrothermal vaporization (ETV), for ICPMS, 3323 Element 112 chemical methods for, 1720–1721 chemical properties of, 1717–1721 discovery of, 1653–1654 electronic structures of, 1682–1684 isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, 1720 production of, 1719, 1720 relativistic orbital energies for, 1669f solution chemistry of complexation of, 1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f Element 113 chemical properties of, 1723–1725, 1724t electronic structure of, 1722t, 1723–1725 ionization potentials of, 1723, 1726t isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1659 production of, 1737 relativistic orbital energies for, 1669f Element 114 chemical properties of, 1724t, 1725–1727 electronic structure of, 1722t, 1725–1727 ionization potentials of, 1725, 1726t isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1659 oxidation states of, 1727 production of, 1738 relativistic orbital energies for, 1669f Element 114–287, discovery of, 1735 Element 114–288, discovery of, 1735 Element 114–289, discovery of, 1735–1736 Element 114–298, half-life of, 1736 Element 115 chemical properties of, 1724t, 1727–1728 electronic structure of, 1722t, 1727–1728 ionization potentials of, 1725f, 1726t, 1727 isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1659 oxidation states of, 1727–1728 relativistic orbital energies for, 1669f Element 116 chemical properties of, 1724t, 1728–1729 ionization potentials of, 1726t, 1728 isotopes of, 1657f–1658f

nuclear properties of, 1655t–1656t orbital filling in, 1659 oxidation states of, 1728 production of, 1737–1738 relativistic orbital energies for, 1669f Element 116–292, discovery of, 1736 Element 117 chemical properties of, 1724t, 1728–1729 ionization potentials of, 1726t, 1728 orbital filling in, 1659 oxidation states of, 1728 relativistic orbital energies for, 1669f Element 118 chemical properties of, 1724t, 1728–1729 ionization potentials of, 1726t, 1728–1729 orbital filling in, 1659 oxidation states of, 1729 relativistic orbital energies for, 1669f Element 118–293 decay of, 1737 production of, 1737 Element 119 chemical properties of, 1724t, 1729–1731 ionization potentials of, 1729, 1730f orbital filling in, 1659 Element 119–294, production of, 1737 Element 120 chemical properties of, 1724t, 1729–1731 ionization potentials of, 1729, 1730f orbital filling in, 1659 Element 120–295, production of, 1737 Element 121 breit effects on, 1669 chemical properties of, 1724t, 1729–1731 orbital filling in, 1659 Element 122 elements beyond, 1659, 1731–1734 orbital filling in, 1659 Element 164, chemical properties of, 1732 Element 165, properties of, 1732–1733 Element 166, properties of, 1732–1733 Element 171, properties of, 1733 Element 172, properties of, 1733 Element 184, properties of, 1733 El’kon District deposit, brannerite at, 280 Elution chromatography, in ion-exchange chromatography, 1289–1290 Embrittlement, of plutonium, 981 from radiogenic helium, 986 Emission spectrum of americium, 1296 of berkelium, 1453–1454, 1484 of californium, 1516 of plutonium, 857–859, 858f, 860t of protactinium, 190, 226 protactinium (IV), 2067–2068, 2068f EMPA. See Electron microprobe analysis EMT. See Electrometallurgical technology

I-46

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 ENAA. See Epithermal neutron activation analysis Endocytosis, actinide elements in liver and, 1816 ENDOR. See Electron-nuclear double resonance Energy bands in actinide metals, 2313–2317 energy levels in, 2316–2317 Energy-dispersed X-ray spectroscopy (EDS), for environmental actinides, 3049t, 3051–3052 Energy levels of 5f electrons, 2347, 2348f–2349f of 5f1 compounds, 2241, 2242f of actinide cyclopentadienyl complexes, 1954, 1955f of actinide ions in crystals, 2013, 2014t of actinium (III), 2058, 2059f of crystal fields, 2044, 2046t of curium (III), 2059–2061, 2266 deduction of, 2019 effective-operator Hamiltonian for, 2026–2027 in energy band, 2316–2317 of free-ions, 2042 condensed phase correlation and, 2037–2039, 2038t magnetic data for, 2226 in metallic state, 2308 of neptunium hexafluoride, 2083–2085, 2083t, 2085f neptunium (IV), 2067 of f orbitals, 2014–2016, 2015f 5f, 2019–2020 6d, 2020 Hamiltonian of, 2031–2032 of plutonium hexafluoride, 2083–2085, 2083t, 2085f of protactinium (IV), 2065–2066, 2066t of radiative relaxation, 2094–2095, 2094f for RIMS analysis, 3319, 3320f for tetra-, penta-, and hexavalent ions, 2081–2082, 2083t, 2084f of tetravalent actinide ions, 2070, 2072t, 2075–2076, 2075f of thorium carbide oxide, 1981, 1982f carbonyl, 1986, 1987f of trivalent actinide elements, 2032, 2033t, 2058–2061, 2058f–2060f of uranium carbide oxides, 1980f charge-transfer, 2086, 2087f hexafluoride, 1934–1935, 1934f, 1936t oxides, 1973, 1975f uranium (III), 2058, 2058f uranium (IV), 2066–2067, 2066t

Enthalpy. See also specific enthalpies of alkyne complexes oligomerization, 2627f, 2926–2929 of americium, 1328–1330, 1329t of berkelium, 1459–1460 of californium metal, 1523–1524, 1524f oxides, 1537 of curium dioxide, 1419 sesquioxide, 1419 of cyclopentadienyl complexes, tetravalent, 2821, 2822t–2823t of electron exchange reactions, 2597 of fermium, 1627–1628 of halides, 2578–2580, 2579t, 2581t of lawrencium, 1644 of mendelevium, 1634–1636 of metal-ligand bonds, 2912–2913 of plutonium oxides with uranium oxides, 1076 tribromide, 1100 Enthalpy of formation. See Formation enthalpy Entropy of actinide elements, 2115–2116, 2116f, 2539, 2542f, 2543t of actinide ions, 2125–2127 of actinide oxides with alkali metals, 2151, 2152t with alkaline earth metals, 2155t, 2156–2157 of americium, 1298t, 1299 of californium, 1527 of carbides, 2196, 2197t of curium, 1411 of dihalides, 2179, 2180t–2181t of dioxides, 2137–2138 of electron exchange reactions, 2597 of halides, 2578–2580, 2579t, 2581t of hexahalides, 2159–2160, 2160t, 2164t of hydrides, 2188, 2189t of mendelevium, 1635 of monohalides, 2179, 2180t–2181t of nitrides, 2197t, 2201–2202 of oxyhalides, 2182, 2183t–2184t, 2186t–2187t of pentahalides, 2160t, 2161, 2164, 2164t of sesquioxides, 2146, 2146f of tetrahalides, 2166t, 2167, 2168f of thorium, 119, 119t of transition metal compounds, 2206t, 2210–2211 of trihalides, 2170t, 2176 tribromides, 2172f, 2174t, 2176 trichlorides, 2172f, 2173t, 2176 trifluorides, 2171t, 2172f, 2176 triiodides, 2172f, 2175t, 2176

Subject Index

I-47

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 of trihydroxides, 2191, 2191t Environment actinide species in, 3013–3014, 3015f analytical techniques for, 3018–3020, 3019t anthropogenic, 3016 dispersal of, 3016–3017 humic and fulvic acids with, 3139–3140 mining, 3017 natural occurrence, 3014–3016, 3015f separation of, 3021 depleted uranium in, 3173–3174 identification and speciation in, 3013–3073 background, 3013–3021 combining and comparing analytical techniques, 3065–3071 electron-photon, -electron, -ion techniques, 3047–3055 ion-photon, -electron, -neutron, -ion techniques, 3058–3065 neutron-photon, -electron, -neutron, -ion techniques, 3055–3057 passive techniques, 3025–3033 photon-phonon, -electron, -neutron, -ion techniques, 3043–3047 photon-photon techniques, 3033–3043 specifics of, 3024–3065 sampling, handling, treatment, and separation in, 3021–3024 issues with, 3021 sample and data collection in, 3021–3022 treatment and separation of, 3022–3024 trace analysis in, 3273–3330 atomic spectrometric techniques, 3307–3309 chemical procedures, 3278–3288 mass spectrometric techniques, 3309–3328 nuclear techniques, 3288–3307 Environmental aspects, of actinide elements, 1803–1813, 2769 in hydrosphere, 1807–1810 man-made, 1805–1807 of natural origin, 1804–1805 nuclear waste disposal, 1811–1813 overview of, 1803 separation techniques for, 2725–2727 sorption and mobility, 1810–1811 Environmental problems actinide chemistry for, 3 of neptunium, 782–783, 786 of nuclear power, 1826 transuranium elements released, 1807, 1808t, 3095 of uranium, 270 Environmental sample collection of, 3021–3022

issues with, 3021 sorption studies on, 3140–3183 bacterial interactions, 3177–3183 carbonate incorporation, 3159–3164 iron-bearing mineral phases, 3164–3169 natural soil samples, 3171–3177 overview of, 3140, 3151 phosphates, 3169–3171 silicates, 3151–3158 synchrotron XAS for, 3086–3087, 3095–3140 acid redox speciation, 3100–3124 base redox speciation, 3124–3137 organic acids, 3137–3140 overview, 3095–3100 treatment and separation of, 3022–3024 coprecipitation, 3023 dialysis of, 3023 electroplating, 3023–3024 gel electrophoresis, 3024 liquid-liquid partitioning, 3024 liquid-solid partitioning, 3024 Epidote, thorium in, 56t Epithermal neutron activation analysis (ENAA), description of, 3303 EPR. See Electron paramagnetic resonance e-Phase, of plutonium, 882f–883f, 883 density of, 936t diffusion rate, 958–960, 959t strength of, 968f, 970 thermal expansion, 938t, 939 thermoelectric power, 957–958, 958t Equilibrium constants of neptunium inorganic ligands, 771, 772t–775t, 781 organic ligands, 776t–780t, 781–782 of plutonium, 1158 hexafluoride, 1088–1090, 1091f of protactinium (V), 211, 211t of uranium hydroxide complexes, 598, 599t inorganic ligand complexes, 601t, 602 organic ligand complexes, 603–605, 604t ternary complexes, 605–606, 606t uranium (III), 598, 601t, 604t ER. See Electrorefining ERDA. See Elastic recoil detection analysis Erythrocytes, actinide association with, 3366–3367 ESMS. See Electrospray ionization mass spectroscopy Ethereal sludge, protactinium enrichment from, 176–178, 177f N,N-Ethyl (hydroethyl)hydroxylamine (EHEH), neptunium (VI) reduction with, 760–761 Ethylene sulfide, cyclopentadienyl complex oxidation by, 2814

I-48

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Ethylenediaminetetraacetate (EDTA) actinide element complexes with, 1783–1784 in bone binding study, 3407–3409 californium separation with, 1509 as chelating agent, 3413 complexes of, 2587, 2588f, 2589t stability constants, 2257f, 2556 curium separation with, 1409 neptunium extraction with, 708 plutonium complex with, 1176–1179, 1178t, 1181 for removal, 1823 separation with, 2639–2640, 2641t of thorium, as ligands, 131 with uranium, 603–605, 604t 2-Ethylhexylphenylphosphonic acid (HEMΦP), einsteinium extraction with, 1585 ETV. See Electrothermal vaporization Europium in einsteinium alloy, 1592 einsteinium v., 1578–1579 extraction of from americium, 2676–2677, 2677t TALSPEAK for, 2672 UO2 solid solutions with, oxygen potentials of, 395t, 396 Europium (III) extraction of, 1274 americium (III), 1283, 1287–1289, 2665–2666, 2667t separation factors for, 2669–2670, 2670t hydration numbers of, 2534, 2535t in concentrated solutions, 2536–2538, 2537f separation factors for, 2669–2670, 2670t XANES of, 3087, 3088f Europium (II), XANES of, 3087, 3088f EXAFS. See Extended X-ray absorption fine structure analysis Exchange charge model (ECM) calculation of, 2053, 2053t with crystal-field Hamiltonian, 2052–2053 Excitation schemes, of actinide elements, 1876–1877, 1877t, 1878f Excitation spectra of curium (III), 2061–2062, 2061f of curium (IV), 2068, 2071f Extended X-ray absorption fine structure analysis (EXAFS) for acid redox speciation, 3100–3103 of actinyl complexes, 1921 hydroxides, 1925 water, 1923 of americium (III), 3115 of californium (III), 3110, 3115 for coordination number analysis, 586, 588, 602, 3087–3088

of curium (III), 3110 FT data with, 3090–3091, 3092f of iron-bearing phases, 3165–3167 LAXS v., 589 of neptunium (III), 3116–3117 of neptunium (IV), 3106–3107, 3135–3136 carboxylates, 3137–3140, 3147t–3150t of neptunium (VII/VI), 3124–3125 of neptunyl (V), 3133–3134 for obtaining structural information, 589 organic acid analyses with, 3137–3140 model systems, 3138–3139 natural systems, 3139–3140 of plutonium dioxide, 1041–1042, 1043f plutonium (III), 3117–3118 plutonium (IV), 3108–3109, 3136 plutonium (VII/VI), 3126 of plutonyl plutonyl (V), 3210 plutonyl (VI), 3134 plutonyl (VI/V), 3123–3124 problems with, coordination numbers, 3103 of tetravalent ions, 3134–3135 of thorium (IV), 3104–3105, 3129, 3136–3137 carboxylates, 3137–3140, 3147t–3150t of thorium, silicate adsorption, 3152–3154 of uranium in carbonates, 3160–3161, 3161t silicate adsorption, 3154–3155 silicate phosphate, 3170 uranium (III), 3116 of uranium (IV), 3105–3106, 3136 in silicate glass and, 276 of uranyl (V), 3122 of uranyl (VI), 3118–3123, 3126–3129, 3131–3133 carboxylates, 3137–3140, 3141t–3150t use of, 3090–3091 of XAS, 3087, 3088f Extracellular fluid (ECF) circulation of, 3357–3359 clearance from of mice, 3388–3395, 3389f–3392f, 3394t of rats, 3387–3388 Extraction chromatography for americium purification, 1293–1295 for berkelium extraction, 1449 for californium separation, 1509 for curium purification, 1434 for einsteinium extraction, 1585 n-Octyl(phenyl)-N,N-diisobutyl-carbamoyl methylphosphine oxide for, 2748–2749 overview of, 844–845, 1293 plutonium extraction with, 844–845 protactinium purification with, 181–186, 183f

Subject Index

I-49

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 resins for, 3284–3285 of rutherfordium, 1692 for trace analysis, 3284–3285, 3286f use of, 845 Extractive metallurgy, of uranium, 303 FA. See Fulvic acid FAAS. See Flame source atomic absorption spectrometry Fast breeder reactors (FBR), plutonium and uranium oxides for, 1070 FBR. See Fast breeder reactors 0 5f Compounds magnetic properties of, 2239–2240 magnetic susceptibilities of, 2240f 5f1 Compounds energy levels of, 2241, 2242f EPR of, 2241 magnetic properties of, 2240–2247 oxides, 2244, 2245t magnetic susceptibility of, 2241 optical data for, 2227t 5f2 Compounds magnetic interactions on, 2228, 2229f magnetic properties of, 2247–2257, 2255t 6 5f Compounds magnetic properties of, 2263–2265, 2264t TIP of, 2263–2264 5f7 Compounds magnetic properties of, 2265–2268, 2266t–2267t magnetic susceptibility of, 2266, 2267t, 2268 5f3 Compounds, magnetic properties of, 2257–2261, 2258t–2260t 5f4 Compounds, magnetic properties of, 2261–2262 5f5 Compounds, magnetic properties of, 2262–2263, 2263t 5f8 Compounds, magnetic properties of, 2268–2269, 2270t 5f9 Compounds, magnetic properties of, 2269–2271, 2270t 5f10 Compounds, magnetic properties of, 2271 5f11 Compounds, magnetic properties of, 2271–2272 f-d promotion energies of actinides, 1560, 1561f, 1586–1588, 1587f, 1609–1610, 1609f–1610f, 1859–1860, 1860f of tetravalent ions, 2065 FEFF role of, 3091–3092 for XAS, 3089 5f-Electron. See 5f Orbital Fermi energy of actinide metals, 2319–2322

electronic heat capacity with, 2323 in free-electron model, 2320–2321 Fermi liquid, 2339–2441 electrical resistivity of, 2340–2341, 2341f plutonium as, 2345–2347 Fermi surface in actinide metals, 2322–2323 description of, 2322 in electron-electron correlations, 2334 in Luttinger theorem, 2334 in magnetism, 2367 topology of, 2322–2323 UIr3 measurements of, 2334 Fermi-Dirac distribution function with DOS, 2320 Pauli exclusion principle with, 2323 Fermium, 1622–1630 atomic properties of, 1626, 1627t chemical properties of, 1628–1630, 1646t discovery of, 5t, 9, 1622, 1761 einsteinium separation from, 1585 ionization potential of, 1877 isotopes of, 10, 1622–1624, 1623t lanthanide elements v., 2 mendelevium separation from, 1632–1633 metallic state of, 1626–1628 nobelium v., 1640 oxidation states of, 2526 in aqueous solution, 1774–1776, 1775t preparation and purification of, 1624–1625, 1625f reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f solution chemistry, 1628–1630 synthesis of, 9, 1622 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t Fermium (III) hydration of, 2528–2530, 2529f, 2529t hydrolytic behavior of, 2546, 2548t Fermium–251, X-rays emitted by, 1626 Fermium–253, in rutherfordium extraction, 1700 Fermium–255 availability of, 1624 from einsteinium–255, 1582 production of, 1622 Fermium–257 availability of, 1624 production of, 1582, 1623–1624 Ferrihydrate, uranium (VI) adsorption on, 3166–3167 Ferritin, in liver, 3397 Ferrocene, history of, 1952

I-50

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 FES. See Flame emission spectrometry f-f transitions of actinyl ions, 1930 of divalent ions, 2078, 2079f intensity of, 2089–2093 Judd-Ofelt theory for, 2093 of tetravalent ions, 2065, 2067 of uranyl, 2088–2089 FI. See Flow injection Filtration for actinide speciation, 3069 for oxidation state speciation, 2726 Fission process history of, 3–4, 2628 of plutonium, 815 plutonium–239, 820 products of, 826, 827t–828t, 828 of uranium, 1804–1805 Fission track analysis (FTA) applications of, 3307 description of, 3303 Flame emission spectrometry (FES), overview of, 3307–3308 Flame source atomic absorption spectrometry (FAAS), of uranium, 636 Floating zone technique, for uranium oxide preparation, 343 Flocculants, for uranium ore processing, 309 Flotation concentration methods, for uranium ore, 303–304 Flow coulometry, for neptunium, 757–759, 758f Flow injection (FI), for separation, 3281 Fluorescence of actinide elements, history of, 1894 of americium (III), 1368–1369 of berkelium, 1454 intensity of, 626 lifetimes of, 2093–2095 overview of, 625, 625f phosphorescence v., 625 quenching of, 625 of uranyl, 2087–2088, 2088f uranyl (VI), 624–630 Fluorescence spectroscopy of curium, 1405–1406, 1406f, 1433 laser-induced, 628–629 of neptunium, 786–787 photochemical studies and, 627 Fluorescence spectrum, of uranium, uranium oxobromo complexes, 573 FLUOREX, for plutonium separation, 856–857 Fluorides of actinide elements, 1796 free-ion and crystal-field interactions of, 2071, 2073f of berkelium, 1457, 1467–1469

of californium, 1529, 1532, 1546 complexes of, 2578 of curium, 1413t–1415t, 1417–1418, 1429 of dubnium, 1705 of mendelevium, 1635 of neptunium, 730–736 equilibrium constants for, 772t hexafluoride, 732–734 pentafluoride, 731–732 tetrafluoride, 730–731 trifluoride, 730 optical spectroscopic data of, 2069–2070, 2069f–2070f precipitation with, 2633–2634 plutonium, 836, 838 of protactinium (V), 213–215, 216f, 217t protactinium derivatives of, 197–199, 198f, 207 alkali, 200–203, 202t in pyrochemical methods, 2700–2701 of rutherfordium, extraction of, 1699–1700 of seaborgium, 1710–1711 with thorium carbonates, 109 as thorium ligand, 129 of uranium, 444–446, 484–489, 518–521, 557–564 fluoro complexes, 445–446, 487–489, 520–521, 520t, 563–564, 564t hexafluoride, 557–563 hexavalent oxide fluoride complexes, 566–567 oxide difluoride, 565–566 oxide tetrafluoride, 564–565 oxides and nitrides of, 489–490 pentafluoride, 518–520 pentavalent oxide fluorides and complexes, 521 polynuclear, 579 tetrafluoride, 484–486 tetrafluoride hydrates, 486–487 trifluoride, 444–445 trifluoride monohydrate, 445–446 Fluorination of dubnium, 1705 of einsteinium, 1611 of plutonium, 1080–1082, 1081f for plutonium metal production, 866, 867f of rutherfordium, 1699–1700 of seaborgium, 1710–1711 of uranium, 315–317, 316f, 317t by uranium hexafluoride, 561 Fluorination reactors, for plutonium fluorination, 1080–1081, 1081f Fluorometry applications of, 3308 fundamentals of, 3308 of uranium, 636–637

Subject Index

I-51

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Fluoroplutonate compounds preparation of, 1103–1104 properties of, 1104, 1105t–1107t Fluxed fusion decomposition, of uranium, 631–632 FOD. See 6,6,7,7,8,8,8-Heptafluoro–2,2dimethyl–3,5-octanedione Foil for lawrencium capture, 1643 for mendelevium capture, 1632–1633 for nobelium capture, 1638–1639 for one-atom-at-a-time chemistry, 1663 Foldy-Wouthuysen transformation, for electronic structure calculation, 1906 Formates of americium, 1322, 1323t of neptunyl, 2257 structural chemistry of, 2437–2440, 2439t–2440t of thorium, 114 synthesis of, 114 Formation constants for americium, 1338, 1339t americium (III), 1273 for plutonium, 1158, 1160t–1161t Formation enthalpy. See also Complexation enthalpy of actinide ions, 2123–2125, 2124f–2125f, 2539, 2541t of actinide oxides with alkali metals, 2151 with alkaline earth metals, 2153–2156, 2154f, 2155t, 2156f of carbides, 2195–2196, 2197t of dihalides, 2179, 2180t–2181t of dioxides, 2136–2137, 2137t, 2138f of hexahalides, 2159–2160, 2160t, 2164t of hydrides, 2187–2188, 2187t, 2189t, 2190f of hydroxides, 2193–2195, 2194t between Lewis acid and Lewis base, 2576–2577 of monohalides, 2179, 2180t–2181t of nitrides, 2197t, 2200–2201, 2201f of oxyhalides, 2182, 2183t–2184t, 2186t–2187t of pentahalides, 2160t, 2161, 2164t of plutonium oxides, 1971 of sesquioxides, 2143–2146, 2144t, 2145f of tetrahalides, 2165–2167, 2166t, 2168f of transition metal compounds, 2206t, 2208–2210, 2210f of trihalides, 2169–2172, 2170t tribromides, 2169–2172, 2172f, 2174t trichlorides, 2169–2172, 2172f, 2173t trifluorides, 2169–2172, 2171t, 2172f triiodides, 2169–2172, 2172f, 2175t of trihydroxides, 2190–2191, 2191t

Fourier transform ion resonance mass spectrometry (FTIRMS), of californium, 1560 Fourier transform spectrometers (FTS), actinide element infrared spectra with, 1840 Fourier transform spectrum (FT) of berkelium, 1474 EXAFS with, 3088, 3090–3091, 3092f of plutonium, 858, 858f Fourmarierite anion topology of, 282–283, 284f–285f at Oklo, Gabon, 271–272 at Shinkolobwe deposit, 273 uranium in, 259t–269t Fractional crystallization, for actinium and lanthanum separation, 18 Francium–223, from actinium–227, 20 Franc¸oisite at Oklo, Gabon, 271–272 uranium in, 259t–269t Free-electron model band structure with, 2324 Fermi energy in, 2320–2321, 2323 Free-ion Hamiltonian adjustment of, 2054 correction terms on, 2076 Coulomb interaction of, 2055 crystal field theory with, 2036–2037 crystal-field Hamiltonian with, 2041, 2054 matrix of, 2031 parameterization of, 2031–2036 parameters of, 2054–2055 of trivalent ions, 2056 Free-ion interactions of actinide fluorides, 2071, 2073f condensed-phase v., 2037–2039, 2038t crystal-field interactions with, 2044, 2062–2064, 2063t of f orbital, 2024, 2025t–2026t HF calculations of, 2022–2023, 2050 modeling of, 2020–2036 central field approximation, 2020–2023 effective-operator Hamiltonian, 2026–2030 LS coupling and intermediate coupling, 2023–2026 parameterization of free-ion Hamiltonian, 2031–2036 reduced matrices and free-ion state representation, 2030–2031 Free-ion parameters of actinide elements, 2038–2039, 2038t computation of, 2058 crystal field parameters and, 2050 tetravalent ions, 2074 in effective-operator Hamiltonian, 2071–2072, 2073f

I-52

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 FTA. See Fission track analysis FTIRMS. See Fourier transform ion resonance mass spectrometry FTS. See Fourier transform spectrometers Fullerenes, 2864–2865 electronic structure of, 2864–2865 overview of, 2864 Fulvic acid (FA) americium (III) complexation with, 1353–1354 complexes of, 2590–2591 environmental actinides and, 3139–3140 for thorium complexation, 132–133 Fusion decomposition, 3278–3279 description of, 3278–3279 disadvantage of, 3279 Gadolinium (III), energy levels of, 2075–2076, 2075f Gadolinium, UO2 solid solutions with, oxygen potentials of, 395t, 396, 397f Gallium in plutonium alloy, 892–894, 893f–896f δ-phase lattice, 930f, 932–933 δ-phase self-irradation damage, 986–987, 987f elastic constants, 942–943, 944t, 946f electrical resistivity, 955–957, 955f–956f hardness of, 971–972, 971f–972f heat capacity, 947–948, 950t–951t magnetic susceptibility, 949, 953–954, 953f microsegregation, 899, 916–917, 916f–917f solubility ranges, 930, 930f thermal conductivity, 957 thermal expansion, 937–942, 940f–941f transformations in, 917–919, 918f thermodynamic properties of actinide compounds with, 2205–2206, 2206t–2207t γ-Phase of plutonium, 882, 882f–883f density of, 936t diffusion rate, 958–960, 959t strength of, 968f, 970 thermal expansion, 938t thermoelectric power, 957–958, 958t of uranium β transformation of, 347 general properties of, 321–323, 322t–323t physical properties of, 321 Gamma radiation, from berkelium–249, 1447 Gamma source, americium as, 1267 Gamma-ray spectroscopy (γS) of actinium actinium–227, 23–24, 26f

actinium–228, 24–25 detector for, 3299–3300 advantages of, 3329 of americium, 1364 applications of, 3300–3302 for environmental actinides, 3025–3028, 3026t, 3028f fundamentals of, 3297–3300, 3299f of neptunium, 783–785 neptunium–237, 784–785 overview of, 3296–3297, 3299f of protactinium protactinium–231, 166, 168f, 224–225 protactinium–233, 225–226 protactinium–234, 170, 171f of thorium, 133–134 for trace analysis, 3296–3302 tracers for, 3297, 3298t Gas adsorption chromatography, for lawrencium, 1643 Gas transport systems, for transactinide element chemical studies, 1663 Gas-jet method of mendelevium production, 1632 of nobelium production, 1638–1639 Gas-phase of californium, 1559–1561 of dubnium, 1705–1706 of einsteinium, 1586–1588, 1609–1610 with laser ablation technique, 1612 of rutherfordium, 1693, 1694f of seaborgium, 1707–1709 of superactinide elements, 1734 thermodynamic properties in, 2118–2123, 2119t–2120t of actinide compounds, 2147–2150, 2148t, 2150f of halides, 2160–2161, 2164–2165, 2169, 2177–2179 of transactinide compounds, 1676–1685 electronic structures, 1676–1684, 1677f–1678f, 1680t–1681t, 1682f volatility predictions, 1684–1685 for transactinide elements, 1663–1665 measured v. predicted, 1715, 1716t GDMS. See Glow discharge mass spectrometer Gel electrophoresis, of environmental sample, 3024 General Purpose Heat Source-Radioisotope Thermoelectric Generators (GPHSRTGs) pellet-formation for, 1032–1033 plutonium–238 in, 818–819, 819f Generalized gradient approximations (GGA), for HF calculations, 1904 Generalized least-squares (GLS), for actinides, 1865

Subject Index

I-53

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Geochemical tracer, actinium–227 as, 44 Geological matrices, trace analysis in, 3273–3330 atomic spectrometric techniques, 3307–3309 chemical procedures, 3278–3288 mass spectrometric techniques, 3309–3328 nuclear techniques, 3288–3307 Geometries, of uranyl polyhedra, 281–282, 284f–286f Germanates, of thorium, 113 Germanium thermodynamic properties of actinide compounds with, 2206–2208, 2206t–2207t uranium compounds with, 407 Gesellschaft fu¨r Schwerionenforschung (GSL), darmstadtium discovery at, 1653 GFAAS. See Graphite furnace source atomic absorption spectrometry GGA. See Generalized gradient approximations Gibbs energy of actinide cation correlations, 2568–2570, 2568f–2569f, 2572–2574 chemical reaction and, 3202 of complexation, 2577 of halides, 2578–2580, 2579t, 2581t of electron exchange reactions, 2597 of formation, 2539, 2540t for chlorides, 2710t of hydration, 2539, 2540t of thorium, 119, 119t of reactions, of oxyhalides, 2182 of transfer, for americium and curium, 2098 Globulins, actinide distribution with, 3362–3363 Gloved boxes, for actinide element study, 11–12, 11f Glow discharge mass spectrometer (GDMS), for mass spectrometry, 3310 GLS. See Generalized least-squares Glycine, of uranium, 603–605, 604t Glycolate coordination with, acetate v., 590 of uranium, 603–605, 604t Glycolates, structural chemistry of, 2439t–2440t Glycoproteins actinide bone binding by, 3410–3411 in plutonium fixation, 1817 Gold foil berkelium separation from, 1450 mendelevium capture on, 1632 GPHS-RTGs. See General Purpose Heat Source-Radioisotope Thermoelectric Generators

Graphite furnace source atomic absorption spectrometry (GFAAS), of uranium, 636 GRAV. See Gravimetry Gravimetric methods for protactinium, 229–231 cupferronate, 230–231 hydroxide, 229 iodate, 230 peroxide, 230 phenylarsonate, 229–230 for uranium, 634–635 Gravimetry (GRAV), for environmental actinides, 3026t, 3029 Gravitational concentration methods, for uranium ore, 303 Ground crystal field state, Zeeman interaction and, 2225–2226 Ground state configuration of actinide elements, 1895, 1897t, 2016–2018, 2018f cyclopentadienyl complexes, 1955 three-electron configurations, 2018–2019, 2018f of actinide metals, 2328 of actinocenes, 1946–1948 of actinyl, 1929–1930, 1930t of cerocene, 1947 DFT calculation of, 1671 of element 184, 1722t, 1733 of heavy fermions, 2342 of neptunocene, 1946 of neptunyl, 1931 of 5f orbital, 2042 of plutonium, 924 compounds, 2345–2347 dioxide, 2288 of plutonyl, 1931 of protactinium, 190 of protactinocene, 1946 scalar-relativistic methods for, 1900 of superactinide elements, 1722, 1722t, 1731 of thorium carbonyl, 1986, 1988f thorium (III), 2240–2241 of thorocene, 1947 of transactinide elements, 1722, 1722t, 1895, 1897t of uranium carbide oxide, 1978–1979, 1979f dioxide, 1972–1973, 2279 hexavalent and complex halides, 557 of uranyl, 1972, 2086–2087, 2087f Group 14 ligands in actinide chemistry, 2894 cyclopentadienyl complex derivatives of, 2820–2821

I-54

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Group IIA elements, thermodynamic properties of, 2205, 2206t–2207t Group IIIA elements, thermodynamic properties of, 2205–2206, 2206t–2207t, 2208f Group IVA elements, thermodynamic properties of, 2206–2208, 2206t–2207t γS. See Gamma-ray spectroscopy GSL. See Gesellschaft fu¨r Schwerionenforschung Guilleminite, as uranyl selenite, 298 HA. See Humic acid Hafnium dubnium v., 1703 extraction with TTA, 1701 rutherfordium v., 1692–1693, 1694f, 1702 extraction of, 1696–1700 studies of, 1696 Hafnium–169, rutherfordium–261 study with, 1696 Half-life of actinide isotopes, 1764t of actinium actinium–227, 20 actinium–228, 24 of americium, 1265–1267, 1266t of berkelium, 1445–1447, 1446t of californium, 1503–1504 of curium, 1399t, 1400 curium–244, 1759 of darmstadtium, 1719 of einsteinium, 1579 einsteinium–253, 1580 einsteinium–255, 1580 of lawrencium, 1642, 1642t lawrencium–260, 1645 of meitnerium–271, 1718 of mendelevium, 1630–1631, 1631t of nobelium, 1637, 1638t of plutonium, 815 isotopes, 822–823 plutonium–24, 822–823 plutonium–238, 815, 817 plutonium–239, 820, 822–823 of protactinium, 162–163 protactinium–231, 166, 170 protactinium–233, 169 protactinium–233 (IV), 221 protactinium–234, 186 of roentgenium, 1719 of superactinide isotopes, 1735–1737 of transactinide isotopes, 1661 Halide slagging, 2709–2710 description of, 2709, 2710t results of, 2709–2710

Halide volatility processes overview of, 855 for plutonium separation, 855 Halides of actinide elements, 1790, 1791t–1795t, 1933–1942 oxyhalides, 1939–1942 uranium hexafluoride and related complexes, 1933–1939 of americium, 1305t–1312t, 1314–1316 coordination of, 1356–1357, 1358f overview of, 1315–1316 preparation of, 1314–1315 of berkelium, 1464t–1465t, 1467–1470 berkelium (III), 1464t–1465t, 1468–1470 berkelium (IV), 1464t–1465t, 1467–1468 of californium, 1529–1534, 1530t–1531t, 1532f complexes of, 2578–2580, 2579t, 2581t of curium, 1413t–1415t, 1417–1418 high-temperature properties of, 2162t–2163t of neptunium, 730–739 preparation of, 730–739 structures of, 731t of plutonium, 1077–1108 chlorides, bromides, and iodides, 1092–1100 fluorides, 1077–1092 oxyhalides of, 1100–1102 as sigma-bonded ligands, 1182–1184 stability of, 1077 ternary halogenoplutonates, 1102–1108 of protactinium, 197–204, 201t alkali, 200–203, 202t preparation of, 197–199, 198f–199f properties of, 199–200 structural chemistry of, 2414–2421, 2417t–2418t, 2419f, 2420t–2421t bonding in, 2415 dihalides, 2415–2416 hexahalides, 2419, 2421, 2421t overview of, 2414–2415 pentahalides, 2416, 2419, 2419f, 2420t tetrahalides, 2416, 2418t trihalides, 2416, 2417t thermodynamic properties of, 2157–2179 complex, 2179–2182, 2183t–2184t, 2185f di- and monohalides, 2178–2179, 2180t–2181t, 2181f hexahalides, 2159–2161 pentahalides, 2161–2165 tetrahalides, 2165–2169 trihalides, 2169–2178 of thorium, 78–94 binary, 78–84, 78t crystallographic data of, 87t–89t fluoride, 78–80, 78t, 79f

Subject Index

I-55

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 nitride reaction with, 98–99 phases of, 84–86, 85f, 86t polynary, 84–94 tetrabromide, 81–82, 81f tetrachloride, 78t, 80–81, 81f tetraiodide, 78t, 82–84, 83f of uranium, 420–575. See also Uranium halides applications of, 420 chemistry of, 421 oxidation states in, 420–421 tervalent and complex, 421–456 Hamiltonian. See also Pauli Hamiltonian crystal-field ECM with, 2052–2053 free-ion Hamiltonian with, 2041 initial parameters of, 2048 matrix element evaluation with, 2039–2042 symmetry rules for, 2043 effective-operator, 2026–2030 corrective terms for, 2029–2030 use of, 2030 free-ion crystal-field Hamiltonian with, 2041, 2054 matrix of, 2031 parameterization of, 2031–2036 for N-electron ion, 2021 for spin-orbit coupling, 2028 Handling atmosphere for, 3259–3260 hazard assessment, 3248–3259 case studies, 3256–3259 chemical property uncertainty, 3255 metal incidents, 3256–3257 nuclear criticality, 3255–3256 nuclear material release and dispersal, 3252–3255 oxide incidents, 3257–3258 potential hazards, 3248–3256 residue incidents, 3258–3259 thermal hazards, 3251–3252 hazard mitigation, 3259–3262 atmosphere for, 3259–3260 conditions for, 3260–3262 of plutonium, 3199–3266 alloys, 3213 hydrides, 3204–3206 metals, 3223–3238 other compounds, 3212–3213 oxides, 3206–3212 reaction kinetics, 3215–3223 scope of concerns, 3201–3202 radiolytic reactions, 3246–3248 of uranium, 3199–3266 compounds, 3213–3215 scope of concerns, 3201–3202

Hartree-Fock (HF) calculations of actinide elements, 1852 with central field approximations, 2020–2023 of crystal-field interactions, 2050–2051 developments of, 1904 of electronic structure calculation, 1900, 1902–1904 of f electrons, 2032, 2034f, 2035 of free-ion interactions, 2022–2023, 2050 of free-ion parameters, 2039 hybrid approach to, 1904 one-electron band structures from, 2325 of plutonium, 1857–1858, 1857f of trivalent ions, 2056 of uranium hexafluoride, 1935–1937, 1936t of uranyl, 1920 Hartree-Fock-Slater (HFS) approach, 1903 Hartree-Fock-Wigner-Seitz band calculation of berkelium metal, 1461 of californium, 1513, 1514t of lawrencium, 1643 of nobelium, 1640 Hassium chemical properties of, 1712–1715, 1715f chemical studies of, 1664 discovery of, 6t, 1653, 1653t, 1762 electronic structures of, 1676–1682, 1677f–1678f, 1680t–1681t, 1682f ionic radii of, 1674f, 1675–1676, 1676t ionization potential of, 1674, 1674f isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, in aqueous solution, 1774–1776, 1775t production of, 1662, 1713 relativistic orbital energies for, 1669f solution chemistry of complexation of, 1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f Hassium–269 decay chains of, 1714 discovery of, 1735 production of, 1713 Hassium–270 decay chains of, 1714 discovery of, 1735 production of, 1713 Hausmannite, plutonium (VI) reactions with, 3176–3177 HAW. See High-level aqueous raffinate waste Hazards assessment of, 3248–3259 case studies, 3256–3259 chemical property uncertainty, 3255 metal incidents, 3256–3257

I-56

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Hazards (Contd.) nuclear criticality, 3255–3256 nuclear material release and dispersal, 3252–3255 oxide incidents, 3257–3258 potential hazards, 3248–3256 residue incidents, 3258–3259 thermal hazards, 3251–3252 mitigation of, 3259–3262 atmosphere for, 3259–3260 conditions for, 3260–3262 of plutonium, 3200 alloys, 3213 corrosion, 3204 hydrides, 3204–3206 hydroxides, 3213 metals, 3223–3238 nitrides, 3212–3213 oligomerized, 3210–3211 other compounds, 3212–3213 oxides, 3206–3212, 3219–3222 reaction kinetics of, 3215–3223 surface chemistry, 3209–3210 radiolytic reactions, 3246–3248 rate-controlling factors and mechanisms in, 3202–3204 scope of concerns, 3201–3202 storage for, 3199 of uranium, 3200 compounds, 3213–3215 HDBP. See Dibutylphosphoric acid HDEHP. See Bis(2-ethylhexyl)phosphoric acid HDNNS. See Dinonylnapthalene sulfonic acid Heap leaching, of uranium ore, 306 Heat capacity of actinide elements, 2116–2118, 2117t, 2119t–2120t, 2121f of actinide ions, 2132–2133 of actinide metals, 2323 of americium, 1298t, 1299 of carbides, 2198, 2198f, 2199t of dioxides, 2138–2141, 2139f, 2142t of hydrides, 2188–2190, 2190t of neptunium dioxide, 2272–2273, 2273f hydrides, 723–724 of nitrohalides, 2182, 2187t of oxyhalides, 2182, 2187t of plutonium, 945–949 history of, 945–947 oxides, 1076 of protactinium, 192, 193t of tetrahalides, 2166t, 2167, 2168f of thorium, dioxide, 2272–2273, 2273f of transition metal compounds, 2206t, 2210–2211

of trihalides, 2170t, 2176 tribromides, 2172f, 2174t, 2176 trichlorides, 2172f, 2173t, 2176 trifluorides, 2171t, 2172f, 2176 triiodides, 2172f, 2175t, 2176 of uranium dioxide, 2272–2273, 2273f hydrides, 333–334, 334f oxide difluoride, 565 oxides, 1076 Heat source actinium as, 42–43 plutonium–238 as, 703, 817 oxides, 1023–1025 Heavy Element Volatility Instrument (HEVI) for isothermal chromatographic systems, 1664 for rutherfordium study, 1693, 1694f Heavy fermions behavior of, 2342–2343, 2343f description of, 2341–2342 ground states of, 2342 magnetic properties of, 2360 Heavy-ion bombardment problems with, 1761–1762 as source of actinide elements, 1761–1763 HEDPA. See 1-Hydroxyethylene–1,1diphosphonic acid HE-EELS. See High-energy electron energy loss spectroscopy HEHA. See 1,4,7,10,13,16Hexaazacyclohexadecane-N,N0 ,N00 , N000 ,N0000 -hexaacetic acid Helium, from plutonium decay, 980, 985–987, 985f, 987f accumulation of, 986 amount of, 985 study of, 986–987, 987f HEMΦP. See 2-Ethylhexylphenylphosphonic acid Hemosiderin, in liver, 3397–3398 6,6,7,7,8,8,8-Heptafluoro–2,2-dimethyl–3,5octanedione (FOD), separation with, 2632, 2680 HEU. See Highly enriched uranium HEVI. See Heavy Element Volatility Instrument 1,4,7,10,13,16-Hexaazacyclohexadecane-N, N0 ,N00 ,N000 ,N0000 -hexaacetic acid (HEHA), for tumor radiotherapy, 43 Hexafluorides of actinide elements, 2083–2085, 2083t, 2084f–2085f complexes of, 2578 Hexafluoroacetylacetone (HFA), SFE separation with, 2680 Hexahalides structural chemistry of, 2419, 2421, 2421t

Subject Index

I-57

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 thermodynamic properties of, 2159–2161, 2160t gaseous, 2160–2161, 2164t solid, 2159–2160, 2160t HF calculations. See Hartree-Fock calculations HFA. See Hexafluoroacetylacetone HFIR. See High-Flux Isotope Reactor HFO. See Hydrous ferric oxide HFS approach. See Hartree-Fock-Slater approach α-HIBA. See α-Hydroxyisobutyric acid High resolution inductively coupled plasma mass spectrometry (HR-ICPMS), 3324–3326, 3325f High-energy electron energy loss spectroscopy (HE-EELS), for plutonium study, 967 Highest occupied molecular orbit (HOMO) of thorocene, 1946 of uranyl, 1916–1917, 1917f High-Flux Isotope Reactor (HFIR) berkelium–249 from, 1445, 1448 californium production in, 1501, 1503 einsteinium production in, 1582 neutron irradiation at, 1759–1760 plutonium–239 in, 821 target preparation for, 1401 for transcurium element production, 9 for transfermium element production, 12 High-flux nuclear reactors, for transplutonium element production, 9 High-level aqueous raffinate waste (HAW), TRUEX process for, 2743–2744 High-level liquid waste (HLLW), actinide recovery from, 2717 High-level waste (HLW) electrodeposition for, 717 ‘light glass’ v., 1273 long-lived actinides in, 2729, 2729t neptunium in intermetallic compounds, 721 neptunium–237 in, 702, 783 partitioning of, 712–713, 2756–2757 problem of, 2728–2729 reprocessing of, 704 DMDBTDMA, 2756 n-Octyl(phenyl)-N,N-diisobutylcarbamoyl methylphosphine oxide for, 1407–1408 Purex process for, 710–712, 710f, 1273–1276, 1285 TRPO for, 2753, 2754t TRUEX process for, 1275, 2740–2745 uranium in, 270 Highly enriched uranium (HEU) description of, 1755 production and use of, 1755–1758

High-performance liquid chromatography (HPLC) ARCA with, 1665 berkelium separation with, 1449–1450, 1450f curium separation with, 1433 einsteinium separation with, 1585 ICPMS and, 3068–3069, 3068f for separation, 3281 High-purity germanium detector (HPGe) for gamma-spectroscopy, 3297–3299, 3299f for uranium analysis, 635 High-purity product refinement, of uranium ore, 314–317, 315f–316f, 317t High-temperature properties of carbides, 2198, 2198f, 2199t of dioxides, 2138–2141, 2139f, 2142t of halides, 2162t–2163t of hexahalides, 2162t–2163t of hydrides, 2188–2190, 2190t ions in condensed phase, 2116–2118, 2117t, 2119t–2120t, 2121f of nitrides, 2199t, 2202 of oxides with alkali metals, 2151–2153 with alkaline earth metals, 2157, 2158t of oxyhalides, 2182, 2183t–2184t, 2186t–2187t of pentahalides, 2162t–2163t of sesquioxides, 2139f, 2146–2147 of tetrahalides, 2166t, 2167–2168 of transition metal compounds, 2207t, 2208f, 2211 of trihalides, 2162t–2163t, 2176–2177, 2177f Hill plot, for uranium compounds, 2331–2333, 2332f HLLW. See High-level liquid waste HLW. See High-level waste HOMO. See Highest occupied molecular orbit HOPO. See Hydroxypyridonate ‘Hot fusion’, element production by, 1738 Hot-wire deposition, for uranium metal preparation, 319 HPGe. See High-purity germanium detector HPLC. See High-performance liquid chromatography HR-ICPMS. See High resolution inductively coupled plasma mass spectrometry Hu¨ckel calculations, on cyclopentadienyl complexes, 1957–1959 Human actinide elements in, 3339–3424 binding in bone, 3406–3412 bone, 3400–3406 liver, 3395–3400 clearance from circulation, 3367–3387 dioxo ions, 3379–3387 rates of, 3367–3369, 3368f–3375f

I-58

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Human (Contd.) tetravalent and pentavalent, 3376–3379 trivalent, 3370–3376 in vivo chelation, 3412–3423 desferrioxamine, 3414 polyaminopolycarboxylic acids, 3413–3414 siderophores, 3414–3423 initial distribution in, 3340–3356 access to, 3340–3341 adult men, 3346t dioxo ions, 3354–3356 ionic radii and stability constants, 3346, 3347t pentavalent, 3350–3354 skeletal fraction, 3346–3349, 3348f soft tissues, 3349–350 tetravalent, 3350–3354 trivalent, 3345–3350 tissue deposition kinetics, 3387–3395 tissue sample, DIPEX resin for, 3284 transport in body fluids, 3356–3367 extracellular fluid circulation, 3357–3359 loose connective tissue, 3359 plasma and tissue fluid composition, 3356–3357, 3357t–3358t plasma distribution of, 3357t–3358t, 3359–3361 Humic acid (HA) americium (III) complexation with, 1353–1354 complexes of, 2590–2591 environmental actinides and, 3139–3140 for thorium complexation, 132–133 Huttonite, thorium in, 55–56 Huzinaga-Cantu equation, RECPs v., 1908 Hydration enthalpy, calculation of, 2538–2539 Hydration numbers of actinide cations, 2532–2533, 2533t hexavalent, 2531–2532 pentavalent, 2531–2532 tetravalent, 2530–2531 trivalent, 1605, 2528–2530, 2529f, 2529t of americium, 1327, 1328f americium (III), 2534, 2535t of curium (III), 2534, 2535f, 2535t–2536t in concentrated solutions, 2536–2538, 2537f of einsteinium, 1605 of europium (III), 2534, 2535t in concentrated solutions, 2536–2538, 2537f of neodynium (III), 2534, 2535t of neptunyl ion, 2531 of thorium, 118 of uranyl ion, 2531–2532

Hydration, of actinide cations, 2528–2544 in concentrated solution, 2536–2538, 2537f hexavalent, 2531–2532 in non-aqueous media, 2532–2533 overview, 2528 pentavalent, 2531–2532 tetravalent, 2530–2531 thermodynamic properties, 2538–2544, 2540t–2541t, 2542f, 2543t, 2544f trivalent, 2528–2530, 2529f, 2529t Hydrazine organouranium catalytic reduction of, 2994–2996 plutonium processing with, 1142 Hydrides of actinide elements, 1790, 1791t–1795t of americium, 1305t–1312t, 1314 of berkelium, 1463, 1464t–1465t preparation of, 1460 of californium, 1540–1541 of curium, 1413t–1415t, 1416–1417 of neptunium, 722–724 chemical behavior, 724 heat capacity, 723–724 physical properties of, 722, 723f, 724t thermodynamic properties, 722–723 of plutonium, 989–996 air reaction with, 3218 applications, 995–996, 996f corrosion, 977–979 electrical properties of, 3205 electronic structure of, 995, 995t history of, 989 hydrogen reaction with, 3215–3216 magnetic properties, 3205–3206 nitrogen reaction with, 3217–3218 oxygen reaction with, 3216–3217 phase diagram of, 990, 991f–992f physical properties of, 990, 995, 995t preparation and reactivity of, 989–990 solid state structures, 992–994, 993f, 993t stoichiometry and phase relationships, 990–992, 991f–992f storage and handling of, 989 thermodynamic properties of, 3205, 3206t water reaction with, 3219 of protactinium, 194 structural chemistry of, 2402–2404 americium, 2404 berkelium, 2404 curium, 2404 neptunium, 2403–2404 plutonium, 2403–2404 protactinium, 2402–2403 thorium, 2402 uranium, 2403

Subject Index

I-59

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 thermodynamic properties of, 2187–2190 enthalpy of formation, 2187–2188, 2187t, 2189t, 2190f entropy, 2188, 2189t high-temperature properties, 2188–2190, 2190t of thorium, 64–66, 66t decomposition of, 65 formation of, 64–65 properties of, 64 reaction with, 65 structure of, 64 ternary, 65–66, 66t of uranium, 328–339, 3213–3214 chemical properties of, 336–337, 337t crystal structures of, 329–330, 329t electrical resistivity, 333 magnetic properties and bonding of, 333–336, 334f, 335t other compounds of, 337–339 phase relations and dissociation pressures of, 330–332, 330f–331f preparative methods for, 329 reactions of, 337, 337t thermodynamic properties, 332–333, 332t use of, 333 Hydrobiotite, uranyl-loaded, 3156 Hydrobromic acid, rutherfordium extraction with, 1697–1698 Hydrocarbyls, of neptunium, 752 Hydrochloric acid curium separation in, 1409 dubnium separation in, 1705 plutonium processing in, 836 rutherfordium extraction with, 1696–1699 uranates (V) and (IV) dissolution in, 381–382 uranium compound dissolution in, 632 metal reactions with, 328 oxide reactions with, 370–371 Hydrofluoric acid protactinium (IV) precipitation by, 222 as protactinium solvent, 176, 178–179 rutherfordium extraction with, 1699–1700 Hydrofluorination, of uranium, 319, 320f Hydrogen plutonium corrosion by, 977–979 hydrides reaction with, 3215–3216 metal reaction with, 3223–3225, 3224f and water formation of, 3250 radiolytic formation of, 3246–3247 hazards of, 3248–3249 uranium metal solubility of, 330f, 331–332 reaction with, 3239–3242, 3240f, 3241t Hydrogen peroxide berkelium extraction with, 1448

protactinium extraction with, 175, 179 reduction by americium (V), 1335–1336 americium (VI), 1335 UO2 dissolution in, 371 Hydrolytic behavior of actinide cations, 2545–2556, 2545f hexavalent, 2553–2556, 2554f–2555f, 2554t–2555t pentavalent, 2552–2553 tetravalent, 2547–2552, 2549t–2550t, 2551f–2552f trivalent, 2546, 2547f, 2547t–2548t of actinide complexes, ternary, 2592–2593 of actinide elements, 1555, 1778–1782, 1810–1811 of americium, 1339–1340 of berkelium, 1475–1479, 1477t–1478t of californium, californium (III), 1554 in mammalian body, 3340 of neptunium, 766–770 neptunium (III), 768 neptunium (IV), 768–769 neptunium (V), 727, 769–770 neptunium (VI), 770 neptunium (VII), 770 tendency towards, 766, 767t of 5f orbital, 3100 of plutonium characterization of, 1146–1147 importance of, 1146 ions, 1110–1111 nitrides, 1019 plutonium (III), 1147–1149, 1148t plutonium (IV), 1148t, 1149–1150, 1781 plutonium (V), 1154–1155 plutonium (VI), 1155–1156 plutonium (VII), 1156 stability of, 1146–1156 of protactinium, 170–171, 179 protactinium (IV), 222, 1780 protactinium (V), 209–212, 210f, 211t, 212f, 1782 of rutherfordium, 1701 of seaborgium, 1711 sorption process v., 1810 of thorium, 119–120, 121t, 122f of transactinide elements, 1686–1687, 1687t of uranium aqueous complexes, 597–600, 599t carbides, 403–405 pentavalent and complex halides, 501 uranium (IV), 585–586, 1780–1781 Hydrometallurgy, 2727–2729 long-lived actinides in HLW, 2729, 2729t problem for, 2728–2729 SNF overview, 2727–2728

I-60

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Hydrosilylation, organometallic intermediates in, 2916–2918, 2917f Hydrosphere, actinide elements in, 1807–1810 Hydrous ferric oxide (HFO), uranyl interaction with, 3166 Hydroxamic acid, for plutonium removal, 1824 Hydroxides of actinide elements, 1796 of actinyl, 1925–1926, 1926t, 1927f of americium, 1303, 1305t–1312t, 1313–1314 history of, 1313 preparation of, 1313–1314 of mendelevium, 1635 of neptunium, 724–730 heptavalent, 726–727 hexavalent, 727 pentavalent, 727 tetravalent, 727–728 of plutonium, 3213 precipitation with, 836, 838 precipitation with, 2633–2634 of protactinium, 207–208 gravimetric methods with, 229 of seaborgium, 1709 thermodynamic properties of, 2190–2192 enthalpy of formation, 2190–2191, 2191t entropy, 2191, 2191t solubility products, 2191–2192 of thorium, 76 of uranium, 259t of uranyl, 1925–1926, 1926t, 1927f Hydroxycarboxylic acids, fermium complexes with, 1629 1-Hydroxyethylene–1,1-diphosphonic acid (HEDPA), actinide stripping with, 1280–1281 α-Hydroxyisobutyric acid (α-HIBA) berkelium separation with, 1449–1450, 1450f californium separation with, 1508 curium separation with, 1409 dubnium separation with, 1704–1705 fermium separation with, 1624, 1629 lawrencium separation with, 1643, 1645 separation with, 2639–2641, 2640f, 2641t, 2650 α-Hydroxyl–2-methyl butyrate, californium extraction with, 1512 Hydroxylamine, plutonium processing with, reduction and oxidation reactions, 1140–1141 Hydroxypyridinonate ligands, as chelating agents, 3415f, 3416–3417, 3417f–3418f Hydroxypyridonate (HOPO) complexes of, 2590–2591 for plutonium removal, 1824–1825, 1825f

8-Hydroxyquinoline actinide complexation with, 1783 californium extraction with, 1513 Ianthinite at Pen˜a Blanca, Chichuhua District, Mexico, 272–273 uranium in, 259t–269t ICPAES. See Inductively coupled plasma atomic emission spectrometry ICPMS. See Inductively coupled plasma mass spectrometry ID analysis. See Isotope dilution analysis IDA. See Iminodiacetate Identification electron-photon, -electron, -ion techniques for, 3047–3055 AES, 3049t, 3051 COUL, 3049t, 3052 DPV and DPP, 3049t, 3052, 3053f EDS, 3049t, 3050–3051 EELS, 3049t, 3051–3052 EMPA, 3049t, 3050 ESMS, 3049t, 3052–3055, 3054f overview of, 3047, 3049t, 3050 SEM, 3049t, 3050, 3051f SSMS, 3049t, 3055 in environment, 3013–3073 background, 3013–3021 combining and comparing analytical techniques, 3065–3071 sampling, handling, treatment, and separation, 3021–3024 specifics of, 3024–3065 ion-photon, -electron, -neutron, -ion techniques for, 3058–3065 AMS, 3059t, 3062–3063 ERDA, 3059t, 3065 ICPMS, 3059t, 3061–3062 NRA, 3059t, 3061 overview of, 3058–3060, 3059t PIGE, 3059t, 3061 PIXE, 3059t, 3060–3061 RBS, 3059t, 3063–3064, 3064f SIMS, 3059t, 3062, 3063f VOL, 3059t, 3061 neutron-photon, -electron, -neutron, -ion techniques for, 3055–3057 DNAA, 3056t, 3057 NAA, 3055–3057, 3056t, 3058f overview of, 3055–3057, 3056t passive techniques for, 3025–3033 βS, 3026t, 3028–3029 GRAV, 3026t, 3029 γS, 3025–3028, 3026t, 3028f ISEs, 3026t, 3029

Subject Index

I-61

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 LSC, 3026t, 3031, 3032f MBES, 3026t, 3028 NS, 3026t, 3029 overview of, 3025, 3026t RAD, 3026t, 3031, 3032f αS, 3026t, 3029–3031, 3030f XS, 3025, 3026t photon-phonon, -electron, -neutron, -ion techniques for, 3043–3047 LAICPMS, 3044t, 3046–3047 LAMMA, 3044t, 3046 LIBS, 3044t, 3045 LIPAS, 3043–3045, 3044t, 3045f overview of, 3043 PHOTN, 3044t, 3046 RIMS, 3044t, 3047, 3048f RIS, 3044t, 3047 SEXAS, 3044t, 3046 TIMS, 3044t, 3046–3047 UPS, 3044t, 3045 XPS, 3044t, 3045–3046 photon-photon techniques for, 3033–3043 AAS, 3034t, 3036 COL, 3034t, 3035 IRS, 3033–3035, 3034t LAICPOES, 3034t, 3036–3037 MBAS, 3034t, 3043 NIR-VIS, 3034t, 3035 NMR, 3033, 3034t overview of, 3033, 3034t PCS, 3034t, 3035–3036 PHOTA, 3034t, 3043 RAMS, 3034t, 3035, 3036f TOM, 3034t, 3040–3043, 3042f TRLF, 3034t, 3037, 3038f UVS, 3034t, 3037 XANES, 3034t, 3039, 3040f XAS, 3034t, 3037–3039, 3040f XRF, 3034t, 3039, 3041f Ignition of plutonium catalyzed, 3236–3237 thermal, 3232–3235, 3233f of uranium, thermal, 3245–3246 Iminodiacetate (IDA) plutonium complex with, 1176–1177, 1178t, 1180–1181 of uranium, 603–605, 604t Immobilization, of SNF, 1812–1813 In situ leaching, of uranium ore, 306 INAA. See Instrumental neutron activation analysis Indenyl complexes with cyclopentadienyl, 2844 structural chemistry of, 2487–2489, 2490t–2491t Indium, in plutonium alloy, 896, 896f

Inductively coupled plasma atomic emission spectrometry (ICPAES), overview of, 3307–3308 Inductively coupled plasma mass spectrometry (ICPMS) with AES, 636, 1770 αS v., 3329 βS and, 3070 applications of, 3326–3328 capillary electrophoresis with, 3069 components of, 3323–3324, 3324f development of, 3329 for electronic structure, 1770 for environmental actinides, 3059t, 3061–3062 fundamentals of, 3323–3326, 3324f HPLC and, 3068–3069, 3068f HR, 3324–3326, 3325f INAA v., 3329 for mass spectrometry, 3310 MC, 3326–3327 nebulizers for, 3323 neptunium neptunium–237 determination, 789, 790f separation with, 783, 784f, 793 overview of, 3322 requirements of, 3323 spectra from, 3324–3326, 3325f for thorium, 133 for trace analysis, 3322–3328 of uranium, 637–639 Infrared spectroscopy (IRS) of actinide dioxides, 1971 of actinide nitrides, 1988–1989 of americium, 1369 of californium, 1544–1545 of cyclopentadienyl complexes, tetravalent, 2814–2815 for environmental actinides, 3033, 3034t of neptunium, 764 overview of, 2014 of plutonium halides, 1183 of thorium disulfide, 1976 of uranium cyclopentadienyl complexes, 2807, 2807t of uranium oxides, 1971 XRD and, 3065 XRF and RAMS with, 3069 Ingestion, of actinide elements, 1818–1820 Inhalation, of actinide elements, 1818–1820 Inner sphere, complexation, 2563–2566, 2566f, 2567t confusion over, 2564 conversion to, 2564–2565 stability constant, 2565, 2566f thermodynamic data, 2566, 2567f

I-62

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 In-situ Volatilization and On-line detection apparatus (IVO), for hassium study, 1713, 1714f Instrumental neutron activation analysis (INAA) applications of, 3303–3305 description of, 3303 ICPMS v., 3329 RNNA v., 3305–3306 sensitivity of, 3305 for uranium, 636 Integral fast reactor (IFR) electrorefining with, 2713 reprocessing in, 2713–2714 Intense Pulsed Neutron Source (IPNS) of curium dioxide, 2292–2293 of plutonium dioxide, 2289, 2290f Intermediate coupling for free-ion interactions modeling, 2023–2026 overview of, 2023 Intermetallic compounds of americium, 1302, 1304t of berkelium, 1461 magnetic studies of, 2238, 2356–2361 heavy-fermion materials, 2360 high uranium content, 2357 itinerant ferromagnets, 2358–2359 low uranium concentration, 2359 lower uranium content, 2358 other compounds, 2360–2361 very low uranium concentration, 2359–2360 of plutonium, 862–987 applications of, 862 crystal structure data for, 899, 900t–915t electronic structure, theory, and modeling, 921–935 history of, 862 mechanical properties, 968–973 nature of, 863 overview of, 898–899 oxidation and corrosion, 973–979 physical and thermodynamic properties of, 935–968 of uranium, 325–326, 325t hydrides as, 338–339 molybdenum, 326, 326f noble metals, 325–326 transition-metal compounds, 325 x-ray crystallography for, 325 Iodates of actinide elements, 1796 of neptunium, equilibrium constants for, 773t of plutonium, 1172–1173 of protactinium, gravimetric methods with, 230

Iodides of actinide elements, 1796 of berkelium, 1469 of californium, 1533 of neptunium, 738 equilibrium constants for, 773t triiodide, 738 of plutonium, 1092–1100 preparation of, 1092–1095 properties of, 1087t, 1098–1100 solid-state structures of, 1084t, 1096–1097, 1096f–1098f protactinium derivatives of, 197–199, 207–208 of uranium complexes, 498–499 oxide and nitride, 499–500 uranium tetraiodide, 497–498 uranium triiodide, 454–455 Ion exchange chromatography for actinide and lanthanide separation, 2669–2670 for actinide element study, 1767–1768, 1768f actinium purification by, 18, 30–32 for americium purification, 1289–1293 anion-exchange resin systems, 1291–1292 cation-exchange resin systems, 1290–1291 inorganic exchangers, 1292–1293 ARCA for microscale, 1665 for berkelium extraction, 1449 for californium separation, 1508–1509, 1510f, 1512 for curium separation, 1409–1410 deployment of, 846 for einsteinium separation, 1585 flow sheet for, 849, 850f improvements of, 851 for metal ion separation, 846 methods for anion exchange, 2635–2637, 2635f, 2642 in aqueous phase, 2638 cation exchange, 2636–2641, 2637f citric acid for, 2638–2639, 2639t Diphonix, 2642–2643, 2643f EDTA and HDEHP for, 2639–2640, 2641t α-HIBA for, 2639–2641, 2640f, 2641t historical development of, 2634–2635 lactic acid for, 2639, 2639t, 2641t NTA and DTPA for, 2640–2641 trivalent actinides from lanthanides, 2635, 2635f for neptunium extraction, 714 operation of, 850–851 overview of, 845–846 for plutonium concentration, 845–852 after extraction, 846–847

Subject Index

I-63

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 history of, 851 overview of, 847 plutonium–238, 817 for protactinium purification, 180–181, 180f for rutherfordium extraction, 1699 for trace analysis, 3282–3283 for transfermium element identification, 13 for uranium leach recovery, 310–311 problems with, 311 process for, 310 solvent extraction v., 311 species absorbed, 310–311 Ion pair formation systems, for extraction, 2660, 2661f Ionic radii of actinide elements, 1798, 1799t of actinide (III) ions, 1605–1607 in mammalian tissues, 3346, 3347t of americium, 1295–1296 of californium, 1528–1529, 1528f of einsteinium, 1604, 1605–1607 importance of, 1612–1613 sesquioxide, 1598 of lawrencium, 1645 of mendelevium, 1635 of nobelium, 1640 oxidation states and, 2558 skeletal fraction v., 3349 stability constants and, 2574, 2575f Ion-ion interaction of actinides, 2101–2103 nonexponential luminescence decay from, 2102–2103 Ionium. See Thorium–230 Ionization potentials (IP) of actinide elements by laser spectroscopy, 1873–1875, 1874t by RIMS, 1875–1879, 1877t, 1878f–1879f of actinium, 33, 1874t of americium, 1296, 1874t of berkelium, 1452, 1874t breit effect on, 1669 of californium, 1874t of curium, 1874t of einsteinium, 1588, 1590f, 1874t of element 113, 1723, 1726t of element 114, 1725, 1726t of element 115, 1725f, 1726t, 1727 of element 116, 1726t, 1728 of element 117, 1726t, 1728 of element 118, 1726t, 1728–1729 of element 119, 1729, 1730f of element 120, 1729, 1730f of fermium, 1877 of neptunium, 1874t, 1875 of plutonium, 859, 1874t of protactinium, 1874t

of superactinide elements, 1731 of thorium, 59–60, 1874t of transactinide elements, 1673–1675, 1673t, 1674f–1675f of uranium, 1874t Ion-selective electrodes (ISEs), for environmental actinides, 3026t, 3029 IP. See Ionization potentials IPNS. See Intense Pulsed Neutron Source Iriginite umohoite transformation to, 299, 300f uranium molybdates in, 299 Iron in aqueous environment, 3097, 3097f in curium complex, 1413t–1415t, 1422 in environment, 3164–3165 in plutonium alloy, 972 reduction, 1138–1139 plutonium melting point and, 897, 898f protactinium separation from, 179–180, 180f sorption on mineral phases of, 3164–3169 with carbonates, 3168 with citrates, 3167–3168 neptunium, 3165, 3165t uranium, 3165, 3165t, 3167 in transferrin, 3363–3364 uranate preparation with, 388 Iron (II), analyses of ISEs, 3029 VOL, 3061 Iron (III), analyses of, ISEs, 3029 IRS. See Infrared spectroscopy IS. See Isotope shift ISEs. See Ion-selective electrodes Island of stability overview of, 14 SHEs v., 1653 substantiation of, 1735–1736, 1736f Isocyanide ligand, cyclopentadienyl complexes insertion of, 2825, 2826f Isothermal chromatographic systems for gas-phase chemistry, 1663–1665, 1705 for seaborgium study, 1708–1709, 1709f for superactinide elements, 1734 Isotope dilution (ID) analysis for ICPMS, 3326 with TIMS, 3313 of uranium, 638 Isotope dilution mass spectrometry, for protactinium–231, 231 Isotope shift (IS) of actinide elements, 1841, 1842t–1850t, 1851–1852, 1853f, 2015–2016 of americium, 1882–1884, 1883f, 1883t of californium, 1872

I-64

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Isotopes of actinium, 18–19, 22t–23t, 31–32 of americium, 9–10, 12, 1265–1267, 1266t of berkelium, 9–10, 1445–1447, 1446t of bohrium, 1657f–1658f of californium, 9–10, 12, 1499–1502, 1500t of curium, 9–10, 12, 1397–1400, 1399t of darmstadtium, 1657f–1658f of dubnium, 1657f–1658f of einsteinium, 10, 1579, 1581t, 1582 of element 112, 1657f–1658f of element 113, 1657f–1658f of element 114, 1657f–1658f of element 115, 1657f–1658f of element 116, 1657f–1658f of fermium, 10, 1622–1624, 1623t of hassium, 1657f–1658f of lawrencium, 1642, 1642t, 1657f–1658f longer-lived, 14 of meitnerium, 1657f–1658f of mendelevium, 1630–1631, 1631t of neptunium, 9–10, 12, 700–702, 701t production of, 702–704 of nobelium, 1637, 1638t of plutonium, 4, 8–10, 12, 815–817, 816t decay of, 1143–1146 formation of, 821, 825–826, 825f from nuclear power reactors, 826, 827t–828t, 828 separation of, 821–822, 828–831 of protactinium, 161–162, 164–170, 165t of roentgenium, 1657f–1658f of rutherfordium, 1657f–1658f of seaborgium, 1657f–1658f of thorium, 53–55, 54t–55t of transactinide elements, 1657f–1658f of uranium, 4, 8–10, 255–257, 256t, 258t Isotopomers, for matrix-isolated actinide molecules, 1968 Itinerant electron behavior, in actinides, 1–2 IVO. See In-situ Volatilization and On-line detection apparatus Ja´chymov mine, marecottite and zippeite in, 292 Jahn-Teller effect, low-symmetry structures from, 2369 JINR. See Joint Institute for Nuclear Research J-j coupling for coupling spin and angular momenta, 1911 LS coupling transition to, 1912–1914 Joint Institute for Nuclear Research (JINR), darmstadtium discovery at, 1653 Joint Working Party (JWP), darmstadtium analysis by, 1653

JT effect, on plutonium dioxide, 2290 Judd-Ofelt theory absorption spectra analysis with, 2091–2093, 2092f–2093f for fluorescence lifetime calculation, 2093–2095 matrix elements computation with, 2090–2091 JWP. See Joint Working Party Kidneys accumulation of protactinium–231, 188 actinide elements in, 1815 uranium in, 1820–1821 uranyl ion in, 3380 complexes, 3382–3383 Kinetics considerations for handling, storage, and disposition, 3201–3204 rate-controlling factors and mechanisms, 3202–3204 scope of concerns, 3201–3202 of corrosion plutonium metal, 3223–3227, 3226f, 3227t, 3237 uranium metal and compounds, 3239–3246 of hydroamination by organoactinide complexes, 2990–2993 terminal alkyne complexes, 2986–2990 of hydrogenation, arene ligands, 3002 of hydrosilylation, terminal alkyne complexes, 2957, 2965–2966 of plutonium reactions, 3215–3223 of tissue deposition, 3387–3395 in mice, 3388–3395, 3389f–3392f, 3394t in rats, 3387–3388 Kohn-Sham (KS) orbitals, with HF equations, 1903 Koongarra deposit, uranium deposits at, 273 Kopmans’ theorem, overview of, 2335–2336 Kramers degeneracy, description of, 2228 Kramer’s degeneracy, overview of, 2044 KS orbitals. See Koshn-Sham orbitals Kyzylsai deposit, mourite in, 301 Laboratoire Aime´ Cotton (LAC), FTS at, 1840 Lactic acid, for separation, 2639, 2639t, 2641t LAICPMS. See Laser ablation inductively coupled plasma mass spectroscopy LAICPOES. See Laser ablation inductively coupled plasma optical spectroscopy LAMMA. See Laser ablation micro mass analysis

Subject Index

I-65

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 LAMS. See Laser ablation mass spectrometry Lanthanide elements actinide elements relativistic effects on, 1898, 1899f actinide elements v., 2, 10–11 atomic volume, 1578–1579, 1578f bonding in, 584–585 extraction from, 1286–1289, 1407 free-ion interaction and crystal-field strength, 2062–2064, 2063t ligand displacement series for, 2806 phonon energy relaxation, 2096 separation from, 2635, 2635f thermodynamic properties of hydration, 2542–2544, 2544t actinide separation from, 2669–2677, 2757–2760 Cyanex 301, 2675–2676 dithiophosphinic acids, 2676 LIX–63, 2759–2760 process applications, 2670–2671 separation factors for, 2669–2670, 2670t soft-donor complexants for, 2670–2671, 2673 sulfur donor extractants, 2676–2677, 2677t TALSPEAK, 2671–2673, 2672f, 2760 TPTZ, 2673–2675, 2674t TRAMEX process, 2758–2759, 2759f bisphosphine oxide extraction of, 2657 elution of, 1625f fermium separation from, 1624–1625 ionic radii of, 1528–1529, 1528f oxides with plutonium oxides, 1069–1070 Wigner-Seitz radius of, 2310–2312, 2311f Lanthanocenes, properties of, 1947 Lanthanum actinium v., 18, 40 americium interaction with, 1302 separation from, 1271 in californium metal production, 1517 fluoride, for plutonium coprecipitation, 833–835 Large-Angle X-ray Scattering (LAXS) for coordination number analysis, 586 EXAFS v., 589 for obtaining structural information, 589 Larisaite, as uranyl selenite, 298 Laser ablation inductively coupled plasma mass spectroscopy (LAICPMS), for environmental actinides, 3044t, 3046–3047 Laser ablation inductively coupled plasma optical emission spectroscopy (LAICPOES), for environmental actinides, 3034t, 3036–3037

Laser ablation mass spectrometry (LAMS), for mass spectrometry, 3310 Laser ablation micro mass analysis (LAMMA), for environmental actinides, 3044t, 3046 Laser ablation technique, in gas-phase studies, of einsteinium, 1612 Laser fluorescence spectroscopy for actinide element study, 14 of californium, 1544 of hydrolytic behavior, 2546 Laser spectroscopy of actinide elements, 1873 ionization potentials by, 1873–1875, 1874t super-deformed fission isomers of americium, 1880–1884, 1881f, 1883f–1884f, 1883t of uranium (III), 2064 Laser-induced breakdown spectroscopy (LIBS) for environmental actinides, 3044t, 3045 neptunium study with, 766 Laser-induced isotope enrichment, of uranium hexafluoride, 1933 Laser-induced photoacoustic spectroscopy (LIPAS) americium study with, 1880 for environmental actinides, 3043–3045, 3044t, 3045f neptunium study with, 766, 787 Lattice constant of berkelium berkelium–249, 1462 metallic state, 1458 of neptunium, hydrides, 722, 724t of plutonium, 2329–2330, 2329f gallium alloys, 939, 941t of thorium nitrides, 99 Lattice parameters of berkelium chalcogenides, 1470 of californium metal, 1519–1521, 1520t pyrochlore oxides, 1538, 1540f sesquioxide, 1536–1537 of curium pnictides, 1421 of einsteinium sesquioxide, 1598–1599, 1599f of neptunium coordination compounds, 746t–747t hexafluoride, 731t, 732 metallic state, 719 sulfides, 740 tellurides, 742 of plutonium, 935–937 alloys and, 930, 930f intermetallic compounds, 899, 900t–915t oxides with uranium oxides, 1071–1073, 1072f self-irradiation damage to, 981–984

I-66

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Lattice parameters (Contd.) of uranium dioxide, 390, 391t–392t halides, 422, 423t–441t, 530t–556t oxide, 344, 345t–346t oxides with plutonium oxides, 1071–1073, 1072f Lawrence Berkeley National Laboratory (LBNL) darmstadtium discovery at, 1653 hassium study at, 1712–1713 rutherfordium production at, 1701 transactinide element claims of Dubna v., 1659–1660 Lawrence Livermore National Laboratory (LLNL), seaborgium production at, 1707 Lawrencium, 1641–1647 atomic properties, 1643–1644 berkelium–249 in production of, 1447 chemical properties of, 1644–1647, 1646t discovery of, 6t, 13, 1641 half-life of, 1642, 1642t isotopes of, 1642, 1642t, 1657f–1658f lanthanide elements v., 2 metallic state of, 1644 oxidation states of, in aqueous solution, 1774–1776, 1775t preparation and purification, 1642–1643 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f solution chemistry, 1644–1647 synthesis of, 13, 1641 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t Lawrencium–255, production of, 1641, 1642t Lawrencium–256 half-life of, 1642, 1642t isolation of, 1642–1643 production of, 1641–1642 x-ray emission of, 1644 Lawrencium–257 half-life of, 1641–1642, 1642t production of, 1641 Lawrencium–258 from dubnium–262, 1704 half-life of, 1642, 1642t Lawrencium–260 half-life of, 1645 production of, 1642 LAXS. See Large-Angle X-ray Scattering Layer structures. See Sheet structures LBNL. See Lawrence Berkeley National Laboratory

LCAO. See Linear combinations of atomic orbitals LDA. See Local density approximation Lea, Leask, and Wolf method, application of, 2229–2230 Leaching calcination prior to, 304 of uranium ores, 303 forms of, 305–306 object of, 304 oxidizer for, 305 reagent for, 304–305 recovery of, 309–317 Lead element 164 v., 1732 thermodynamic properties of actinide compounds with, 2206–2208, 2206t–2207t in uraninite, 274 uranium compounds with, 407 oxides, 383–389, 384t–387t uranyl oxyhydroxides with, 287–288 Lead–212, nuclear properties of, 3298t Lead–214, nuclear properties of, 3298t Least-squares fitted values, of actinide elements, 1864–1865, 1864f Lepersonnite, description of, 293 Lermontovite, uranium in, 259t–269t, 275 LEU. See Low-enriched uranium Lewis acids, actinide elements as, 1901 Ligands actinide element bonding of, 1900–1901 carbon-based, 2800–2867 alkyl, 2866–2867 allyl, pentadienyl and related, 2865–2866 cyclooctatetraenyl, 2851–2858 cyclopentadienyl, 2800–2851 other carboxylic, 2858–2865 in coordination number, 2558 for thorium in coordination compounds, 115 inorganic, 129–131, 130t ‘Light glass,’ radioisotopes in, 1273 Light water reactor (LWR) fuel recovery from calcium reduction, 2722 lithium reduction, 2722–2723 pyrochemical methods for, 2721–2723 plutonium in, 826 uranium oxides with, 1070 Light Weight Radioisotope Heater Units (LWRHUs) fuel formation for, 1032–1034 plutonium–238 in, 819, 820f Linear combinations of atomic orbitals (LCAO), MO levels as, 1902 LINEX process, overview of, 2724–2725

Subject Index

I-67

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 LIPAS. See Laser-induced photoacoustic spectroscopy Lipofuscin, americium binding to, 1816 Liquid anion-exchange chromatography, 851–852 Liquid plutonium, 960–963 melting point of, 960–962 properties of, 962–963 Liquid scintillation counting (LSC), for environmental actinides, 3026t, 3031, 3032f Liquid scintillation spectrometry for neptunium, 785 for thorium, 133–134 Liquid-liquid extraction (LLE). See also Solvent exchange for actinide elements study, 1768–1769 in RTILs, 2691 of rutherfordium, 1702, 1702f SFE v., 2678 of superactinides, 1735 for trace analysis, 3282 of uranium, 633 Liquid-liquid partitioning, of environmental sample, 3024 Liquid-solid partitioning, of environmental sample, 3024 Lithium in californium metal production, 1517 in curium metal production, 1411–1412 protactinium compounds with, 208 reduction of, for electrorefining, 2722–2723 Lithium chloride curium extraction in, 1407, 1409 einsteinium extraction in, 1585 in electrorefining, 2714–2715 lanthanide, actinide separation with, 1407 Liver actinide elements in, 1815–1816, 3395–3400 stored iron association with, 3398–3399 uptake, 3399–3400 blood supply to, 3396 as deposition site, 3344 bone v., 3344–3345 iron storage in, 3397–3398 actinide elements with, 3398–3399 ferritin, 3397 hemosiderin, 3397–3398 metal transport into, 3396–3397 microanatomy of, 3396 LIX–63, for actinide/lanthanide separation, 2759–2760 LLE. See Liquid-liquid extraction LLNL. See Lawrence Livermore National Laboratory Local density approximation (LDA) for actinide metals, 2328 δ-phase plutonium and, 925

electron density and gradient with, 924 for excited state energies, 1910 Localized electron behavior, in actinides, 1–2 Loose connective tissue, actinides in, 3359 Low-enriched uranium (LEU), description of, 1755 LS coupling for coupling spin and angular momenta, 1911 for free-ion interactions modeling, 2023–2026 j-j coupling transition of, 1912–1914 overview of, 2023 spin-orbit coupling with, 2024–2026 in tetravalent actinide ions, 2075–2076 truncation of, terms, 2042 Luminescence of actinide cations, 2536–2538, 2537f of americium, 1368–1369, 1369f americium (III), 2098 of berkelium, 1453–1454 of curium, 1425, 1429 curium (III), 2096–2097, 2097f decay of, 2101–2102, 2101f of einsteinium, 1579, 1580f, 1602 energy transfer in, 2102–2103 lifetimes of, 2098–2100, 2099t, 2100f measurement of, neptunium, 787–788 of neptunium hexafluoride, 2084–2085 overview of, 627 of plutonium hexafluoride, 2084–2085 Luminescence decay, for hydration study, 2528 Lungs actinide elements in, 1819–1820 transuranium elements in, 12 Lutetium, lawrencium v., 1644 Luttinger theorem, Fermi surface in, 2334 LWR. See Light water reactor LWRHUs. See Light Weight Radioisotope Heater Units Lymphatic system, actinide elements in, 1815 Lysosomes, actinide element uptake with, 1816 MACS. See Magnetically assisted chemical separation Madelung energy, loss of, 2369 Magnesium UO2 solid solutions with, oxygen potentials of, 395t, 396–397 for uranium reduction, 319 uranium v., 318 Magnetic anisotropy exchange interactions in, 2364–2366, 2365f–2366f large groups, 2365–2366

I-68

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Magnetic anisotropy (Contd.) overview of, 2364–2365 two-ion, 2365, 2365f–2366f Magnetic concentration methods, for uranium ore, 303–304 Magnetic dipole moment, neutron scattering and, 2232 Magnetic moment of californium metal and compounds, 1542, 1543t of uranium hydrides, 334–336, 335t Magnetic polyamine-epichlorohydrin resin (MPE resin), americium purification with, 1292–1293 Magnetic properties, 2225–2295 5f0 compounds, 2239–2240 5f1 compounds, 2240–2247 5f2 compounds, 2247–2257 5f3 compounds, 2257–2261 5f4 compounds, 2261–2262 5f5 compounds, 2262–2263 5f6 compounds, 2263–2265 5f7 compounds, 2265–2268 5f8 compounds, 2268–2269 5f9 compounds, 2269–2271 5f10 compounds, 2271 5f11 compounds, 2271–2272 of actinide dioxides, 2272–2294 of actinide elements, 1541–1542, 1542t of actinide metals, 2353–2368 electronic transport and, 2367–2368 exchange interactions and magnetic anisotropy, 2364–2366, 2365f–2366f general features of, 2353–2354 intermetallic compounds, 2356–2361 magnetic structures, 2366–2367 orbital moments, 2362–2364, 2363f other compounds, 2361–2362 in pure elements, 2354–2356 of americium, 2355–2356 americium (II), 2265–2268 americium (III), 2263–2265 americium (IV), 2262–2263 of anhydrous uranium chloride complexes, 451 of berkelium, 2355–2356 berkelium (III), 2268–2269, 2270t berkelium (IV), 2265–2268 ions, 1472, 1473f metallic state, 1460 of californium, 2355–2356 californium (III), 2269–2271, 2270t californium (IV), 2268–2269, 2270t compounds, 1541–1542, 1542t metal, 1525 of curium, 2355–2356 curium (III), 2265–2268 curium (IV), 2263–2265

metallic state, 1411 pnictides, 1421 of dioxides, 2272–2294 americium, 2291–2292 curium, 2292–2293 neptunium, 2282–2288 plutonium, 2288–2290 uranium, 2272–2282 of einsteinium, 1602–1603 einsteinium (II), 2271–2272 einsteinium (III), 2271 of fermium, 1626 of heavy fermions, 2360 of lanthanides, 1541–1542, 1542t of neptunium, 2356–2357 alloys, 719–720 chalcogenides, 742 neptunium (III), 2261–2262 neptunium (IV), 2257–2261 neptunium (V), 2247–2257 neptunium (VI), 2240–2247 neptunium dioxide, 2236–2237, 2237f tetrachloride, 2258t, 2260–2261 of neptunyl ion, 2240–2247, 2255t of plutonium, 949–954, 2355–2357 hexafluoride, 1086–1088 hydrides, 3205–3206 intermetallic compounds, 2361 phosphides, 1022 plutonium (III), 2262–2263 plutonium (IV), 2261–2262 plutonium (V), 2257–2261 plutonium (VI), 2247–2257 plutonium (VII), 2240–2247 pnictides, 1023 silicides, 1015–1016 susceptibility, 949, 953–954, 953f trichloride, 2262 of plutonocene, 1946 of protactinium, 192, 193t carbides, 195 halides, 203 pnictides, 207 protactinium (IV), 2240–2247 protactinium (V), 2239–2240 quantization of, 2317–2318 source of, 2225–2226 superconductivity and, 2238–2239 of thorium, 61–63 antimony, 100 borides, 67 phosphides, 99–100 thorium (III), 2240–2247 thorium (IV), 2239–2240 of thorocene, 1946 of uranium, 2354–2357 arsenide, 2234–2235, 2235f bromide complexes, 496

Subject Index

I-69

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 dioxide solid solutions, 389–390 halides, 443–444, 483 hexafluoride, 561, 2239–2240 hydrides, 333–336, 334f, 335t intermetallic compounds, 2357–2360 iodide complexes, 499 oxides, 389–390 pentavalent and complex halides, 501, 518 silicides, 406 tetrachloride, 491–492, 2248–2251 tetravalent halides, 483 tribromide, 453 trichloride, 448 trifluoride, 445 trihydride, 2257 triiodide, 455 UNiAlHy, 338–339 uranium (III), 2257–2261 uranium (IV), 2247–2257, 2255t uranium (V), 2240–2247, 2247t uranium (VI), 2239–2240 uranium pentachloride, 523 uranium tetrachloride, 491–492 of uranyl ion, 2239–2240 Magnetic scattering of neptunium dioxide, 2283–2284, 2284f of uranium dioxide, 2281, 2282f Magnetic spin-orbit interaction, with effective-operator Hamiltonian, 2029–2030 Magnetic susceptibility of 5f0 compounds, 2240f of 5f1 compounds, 2241 of 5f7 compounds, 2266, 2267t, 2268 of berkelium berkelium (III), 1445, 2268–2269 dioxide, 2268 ions, 1472, 1473f metallic state, 1460 of californium californium (III), 2269–2271, 2270t metal, 1525 of curium curium (IV), 2264–2265 dioxide, 1419, 2293 fluorides, 1418 sesquioxide, 1419 for eigenfunctions, 2226 from empirical wave functions, 2047 of neptunium dioxide, 2283 hexafluoride, 2243 tetrachloride, 2258t, 2260–2261 of plutonium, 2345–2347, 2346f dioxide, 2290, 2291f plutonium (IV), 2261–2262

of protactinium tetrachloride, 2241 tetraformate, 2241 representation of, data, 2230–2231 temperature dependence of, 2365–2366, 2366f of UBe13, 2342, 2343f of uranium dioxide, 2272–2273 hexachloride, 2245–2246 metallic state, 323–324 oxides, 380, 382 sulfates, 2252 tetrachloride, 2248, 2249f tribromide, 2257–2258, 2258t trichloride, 2257–2258, 2258t trifluoride, 2257, 2258t triiodide, 2257–2258, 2258t uranium (III), 2260, 2260t of uranocene, 2252–2253 Magnetically assisted chemical separation (MACS) CMPO in, 2751–2752 design of, 2751, 2751f historical development of, 2750–2751 Magnetite, thorium in, 56t Magnon dispersion curves, of uranium dioxide, 2280–2281, 2280f Malonamide extractants new compounds as, 2659 for solvating extractant system, 2657–2659 Malonates, structural chemistry of, 2441t–2443t, 2447 Mammalian tissues actinide elements in, 3339–3424 binding in bone, 3406–3412 bone, 3400–3406 liver, 3395–3400 clearance from circulation, 3367–3387 dioxo ions, 3379–3387 rates of, 3367–3369, 3368f–3375f tetravalent and pentavalent, 3376–3379 trivalent, 3370–3376 in vivo chelation, 3412–3423 desferrioxamine, 3414 polyaminopolycarboxylic acids, 3413–3414 siderophores, 3414–3423 initial distribution in, 3340–3356 access to, 3340–3341 beagle dogs, 3343t dioxo ions, 3354–3356 ionic radii and stability constants, 3346, 3347t Kenya baboons, 3345t Macaque monkeys, 3344t mice, 3343t pentavalent, 3350–3354

I-70

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Mammalian tissues (Contd.) rats, 3341t–3342t skeletal fraction, 3346–3349, 3348f soft tissues, 3349–350 tetravalent, 3350–3354 trivalent, 3345–3350 tissue deposition kinetics, 3387–3395 in mice, 3388–3395, 3389f–3392f, 3394t in rats, 3387–3388 transport in body fluids, 3356–3367 extracellular fluid circulation, 3357–3359 loose connective tissue, 3359 plasma and tissue fluid composition, 3356–3357, 3357t–3358t plasma distribution of, 3357t–3358t, 3359–3361 Manganese plutonium melting point and, 897 protactinium separation from, 188 sorption studies of, 3176–3177 with thorium sulfates, 105 Manganese dioxide, for uranium leaching, 305 Manganite, plutonium (VI) reactions with, 3176–3177 Many-body perturbation theory (MBPT), for relativistic correlation effects, 1670 Marecottite, uranium sulfates in, 292 Marine organisms, actinide elements in, 1809 Marthozite, as uranyl selenite, 298 Mass spectrometry of berkelium, 1455–1457, 1457f, 1484 of californium, 1560 historical development of, 3309–3310 of neptunium, 788–790 of protactinium and thorium, 231 radiometric techniques v., 3309 techniques for, 3310 for trace analysis, 3309–3328 AMS, 3315–3319 ICPMS, 3322–3328 RIMS, 3319–3322 TIMS, 3311–3315 of uranium, 636–637 for uranium–235, 255 Mass spectrometry time-of-flight, of californium, 1560 Mass spectroscopy, for actinide element study, 14 Matrix elements of absorption intensity calculations, 2089–2090 Judd-Ofelt theory computation of, 2090–2091 Matrix-isolated actinide elements, 1967–1991 binary carbonyls, 1984–1987 carbide oxides, 1976–1984 description of, 1968 developments of, 1969

dioxides, 1970–1976 nitride-oxides, 1989–1991 nitrides, 1987–1989 overview of, 1968–1970 MBES. See Mo¨ssbauer emission spectroscopy MBPT. See Many-body perturbation theory MCDF. See Multi-configuration Dirac-Fock MC-ICPMS. See Multicollector inductively coupled plasma mass spectrometry MD calculations. See Molecular dynamics calculations Mechanical hardening, of plutonium, 981 Mechanical properties of alloys, 972–973 of californium, 1525–1526 of plutonium, metal and intermetallic compounds of, 968–973 of uranium metal, 322–323, 323t Medical applications of actinide elements, 1828–1829 of californium, 1502 californium–252, 1505–1507 of curium, 1398–1400 Meitnerium chemical methods for, 1720–1721 chemical properties of, 1717–1721 discovery of, 6t, 1653, 1653t electronic structures of, 1682–1684 half-life of, 1661 isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, 1720 in aqueous solution, 1774–1776, 1775t production of, 1720 relativistic orbital energies for, 1669f solution chemistry of complexation of, 1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f Meitnerium–268, half-life of, 1661, 1717 Meitnerium–271 half-life of, 1718 production of, 1717–1718 Melt refining historical development of, 2708 under molten salts, 2709–2710 oxide slagging in, 2709 process for, 2708–2709 Melting behavior, of plutonium oxides, 1045 with uranium oxides, 1074–1075, 1075f Melting point of actinide dioxides, 2139, 2139f of berkelium, sesquioxide, 1467 of californium, metal, 1522 of einsteinium, metal, 1592 mechanical properties and, 968

Subject Index

I-71

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Mendelevium, 1630–1636 atomic properties, 1633–1634, 1634t chemical properties of, 1635–1636, 1646t discovery of, 5t, 13 half-life of, 1630–1631, 1631t isotopes, 1630–1631, 1631t lanthanide elements v., 2 metallic state of, 1634–1635 oxidation states of, 2526 in aqueous solution, 1774–1776, 1775t preparation and purification, 1631–1633 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f solution chemistry, 1635–1636 synthesis of, 13 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t Mendelevium (III), hydration of, 2528–2530, 2529f, 2529t Mendelevium–256 importance of, 1630–1631 production of, 1631 Mendelevium–258, half-life of, 1630, 1631t Mercury americium interaction with, 1302 element 112 v., 1720–1721 element 164 v., 1732 Mesothorium II. See Actinium–228 Metabolic effects, of berkelium, 1445 Metallic conduction with thorium boride, 67 with thorium hydride, 64 Metallic radii of actinides, 2313 of americium, 1295 of californium, 1527 of lawrencium, 1644 of plutonium, 886, 887t Metallic state. See also Actinide metals 5f-electron phenomena in, 2307–2373 basic properties, 2313–2328 cohesion properties, 2368–2371 general observations, 2328–2333 magnetism, 2353–2368 overview of, 2309–2313 strong correlations, 2341–2350 strongly hybridized, 2333–2339 superconductivity, 2350–2353 weak correlations, 2339–2341 of actinide elements, 1–2, 964, 1591–1592, 1591t, 1784–1790 crystal structure, 1785–1787, 1786t electronic structures, 1788–1789, 1789f

polymorphic transformation, 1787 preparation, 1784–1785 properties of, 1786t superconductivity, 1789–1790 of actinium, 34–35 of americium, 1297–1302 phases of, 1297–1299 preparation of, 1297 properties of, 1297–1302, 1298t, 1301f structure of, 1300 of berkelium, 1457–1462 chemical properties, 1460–1461 physical properties, 1458–1460 preparation of, 1457–1458 theoretical treatment, 1461 of californium, 1517–1527 chemical and mechanical properties of, 1525–1526 physical properties of, 1519–1525 preparation of, 1517–1519 theoretical treatments of, 1526–1527 of curium, 1410–1412 chemical properties of, 1412 physical properties of, 1410–1411, 1413t–1415t preparation of, 1411–1412 of einsteinium, 1588–1594, 1591t alloys of, 1592–1593 other actinide metals v., 1591–1592, 1591t problems of, 1588 production of, 1590, 1593–1594 properties of, 1590–1591, 1591t thermodynamic properties of, 1592–1593 of element 164, 1732 of fermium, 1626–1628 of lawrencium, 1644 magnetic studies of, 2238 of mendelevium, 1634–1635 of neptunium, 717–721 history of, 717 lattice parameters, 719 production of, 717–718 properties of, 718 thermodynamic properties of, 718–719 of nobelium, 1639 of plutonium, 862–987 applications of, 862, 996, 996f corrosion kinetics of, 3223–3238 electronic structure, theory, and modeling, 921–935 hazards of, 3202, 3256–3257 history of, 862 mechanical properties, 968–973 nature of, 863 oxidation and corrosion, 973–979, 3226f, 3227–3235, 3227t, 3229t physical and thermodynamic properties of, 935–968

I-72

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Metallic state (Contd.) preparation of, 863–864, 995–996, 996f pyrochemical preparation and refining, 865–877 safe storage, 3260–3262, 3261f strength of, 968, 969f of protactinium, 191–194 physical parameters of, 191–194, 193t preparation of, 191 of thorium, 60–63 of uranium, 318–328 chemical properties of, 327–328, 327t corrosion kinetics, 3239–3246 electrical properties, 324, 324f, 324t general properties of, 321–323, 322t hazards of, 3202 intermetallic compounds and alloys, 325–326, 325t magnetic susceptibility, 323–324 physical properties of, 320–321, 321f preparation of, 318–324, 320f safe storage, 3262 Metallothermic process, for uranium metal preparation, 319, 320f Metal-metal interaction, in bimetallic complexes, 2891–2892, 2893f Metal-metal processes, of pyrochemical methods, 2708–2709 Metamagnetism, of neptunyl, 2255t, 2257 Metamictization, of uraninite, 275 Metathesis, of cyclopentadienyl complexes, 2819 Methane, radiolytic formation of, 3246–3247 Methyltrioctylammonium chloride. See Aliquat 336 MHW-RTGs. See Multihundred Watt Radioisotope Thermoelectric Generators MIBK, lawrencium extraction with, 1645 Mice initial distribution in, 3343t tissue deposition kinetics in, 3388–3395, 3389f–3392f, 3394t Microcracking, of plutonium, 890 Microsegregation, in plutonium gallium alloy, 899, 916–917, 916f–917f Micro-XANES. See Micro-X-ray absorption near-edge structure spectroscopy Micro-XAS. See Micro-X-ray absorption spectroscopy Micro-X-ray absorption near-edge structure spectroscopy (Micro-XANES), of solid samples, sorption studies of, 3174 Micro-X-ray absorption spectroscopy (Micro-XAS), of solid samples, sorption studies of, 3172–3173 MIK, protactinium extraction with, 188 Military purposes, plutonium for, 4

Mineralogy, of uranium, 257, 259t–269t, 270–273 Minerals, with uranium, 259t–269t, 274–275 bonding in, 280–281 crystal morphology prediction, 286–287 geometry of, 281–282, 284f–285f Mixed oxide fuel (MOX) DDP for, 2692–2693, 2707–2708 production of, 1070 transmutation with, 1812 MO levels. See Molecular orbital levels Moctezumite, as uranyl tellurite, 298 Molecular dynamics (MD) calculations, on thorium ion, 1991 Molecular orbital (MO) levels of actinocene, 1949 excited-state energies with, 1910 in HF calculations, 1902 seaborgium predictions of, 1707 of thorium carbonyl, 1986, 1988f in transactinide elements, 1677, 1677f of U2, 1994, 1995f of uranium molecules, 1969–1970, 1970f Molecular volumes, for actinide sesquioxides, 1535–1536, 1539f Møller-Plesset perturbation theory fourth-order (MP4), in HF calculations, 1902 Møller-Plesset perturbation theory secondorder (MP2), in HF calculations, 1902 Molten metal-salt extraction Argonne salt transport process, 2710–2712, 2712f other applications, 2712 Molten salt breeder reactor (MSBR), molten salt-metal extraction at, 2712 Molten salt extraction (MSE) for plutonium metal production, 868f, 869–870 use of, 2692 Molten salts actinide ions in, thermodynamic properties of, 2133–2135, 2134t, 2135f for pyrochemical processes, 2692 Molybdates of americium, 1321 in pyrochemical methods, 2702–2703 of thorium, 111–112 with alkali metals, 112 structure of, 111–112 synthesis of, 111 tungstates v., 113 of uranium, 266t natural occurrence of, 299 uranium (IV), 275 Molybdenum in uranium amine extraction, 312 in uranium intermetallic compound, 326, 326f

Subject Index

I-73

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Monazite processing of, 56–58, 57f–59f thorium in, 56t Monocarbides, structural chemistry of, 2406t, 2407 Mono-cyclopentadienyl complexes, structural chemistry of, 2482–2485, 2484t, 2485f–2487f Monohalides, thermodynamic properties of, 2178–2179, 2180t–2181t, 2181f gaseous, 2179 solid, 2178–2179 Monopicolinates, structural chemistry of, 2439t–2440t Monoxides dissociative energy of, 2149–2150, 2150f thermodynamic properties of, 2147 Monte Carlo program for bohrium study, 1711–1712 for hassium study, 1713–1715 for isothermal chromatographic systems, 1665 for rutherfordium study, 1693 Montmorillonite thorium complexes, 3156–3157 uranium complexes on, 301–302 uranyl-loaded, 3155–3156 Mo¨ssbauer absorption spectroscopy (MBAS), for environmental actinides, 3034t, 3043 Mo¨ssbauer effect of neptunium–237, 792 of protactinium, 190–192 Mo¨ssbauer emission spectroscopy (MBES), for environmental actinides, 3026t, 3028 Mo¨ssbauer spectroscopy of americium, 1297 of neptunium–237, 792–793 neutron scattering v., 2232 of plutonium, 861–862 Mourite, uranium molybdates in, 301 MOX. See Mixed oxide fuel MP2. See Møller-Plesset perturbation theory second-order MP4. See Møller-Plesset perturbation theory fourth-order MPE resin. See Magnetic polyamineepichlorohydrin resin MSE. See Molten salt extraction Multicollector inductively coupled plasma mass spectrometry (MC-ICPMS), 3326–3327 RNAA v., 3329 Multi-configuration Dirac-Fock (MCDF) for electronic structure calculation, 1670 of rutherfordium, 1692–1693

Multihundred Watt Radioisotope Thermoelectric Generators (MHWRTGs), plutonium-238 in, 818, 818f NAA. See Neutron activation analysis Natural occurrence of actinide elements, 1755–1756, 1804–1805, 3014–3016, 3273, 3274t–3275t, 3276 of actinium, 26–27 actinium-227, 26–27 uranium v., 162 of bijvoetite, 290 of brannerite, 280 of carnotite, 297–298 of coffinite, 275–276 of neptunium, 703–704, 1804 neptunium-237, 782–783, 1756 neptunium-239, 704, 1756 of parsonsite, 297 of pitchblende, 1804–1805 of plutonium, 822–824, 823t, 1804, 3016 plutonium-239, 822–824, 823t, 1756 plutonium-244, 822, 824 of protactinium, 161, 231 protactinium-231, 170 protactinium-233, 171 of pyrochlore, 279 of sale´eite, 293 of thorite, 275–276 of thorium, 133, 1804 thorium-232, 3273, 3276 of transactinide elements, 1661, 1755–1756 of uranium, 170, 255, 256t, 257–302, 1804 arsenates, 293 in calcite, 3163 carbonates, 291 molybdates, 299 phosphates, 293 selenites, 298 silicates, 292 uranium-234, 255, 256t uranium-235, 26–27, 170, 255–256, 256t, 3273, 3276 uranium-238, 255, 256t, 3273, 3276 of uranophane, 292 of zirconolite, 277–278 Natural uranium, description of, 1755 NCP. See Neocupferron NCRW. See Neutralized cladding removal waste Near-infrared and visible spectroscopy (NIR-VIS), for environmental actinides, 3034t, 3035 Nebulizers, for ICPMS, 3323 Neocupferron (NCP), protactinium extraction with, 184 Neodymium, in pitchblende, 1804

I-74

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Neodymium tris-cyclopentadienyl, magnetic susceptibility of, 2259, 2259t Neodynium (III), hydration numbers of, 2534, 2535t Neptunium, 699–795 analytical chemistry and spectroscopic techniques, 782–795 electrochemical methods, 790–792 luminescence methods, 787–788 mass spectrometry, 788–790 miscellaneous methods, 793–795 Mo¨ssbauer spectroscopy, 792–793 radiometric methods, 782–786 spectrophotometric methods, 786–787 XRF, 788 in aqueous solution, 752–770 control of oxidation states, 759–763, 760t diproportionation of neptunium dioxide, 759 electrolytic behavior, 755–759 hydrolysis behavior, 766–770 optical spectroscopy, 763–766 oxidation states of ions, 752–763 in biological systems in bone, 1817 health hazard of, 1814 in liver, 1815–1816 in organs, 1815 complexes of cyclopentadienyl, 2803 mono-cyclopentadienyl, 2482–2485, 2484t, 2485f tetrakis-cyclopentadienyl, 2814–2815 compounds of, 721–752 antimonides, 743–744 arsenides, 743 bismuthides, 744 bromides, 737–738 carbides, 744 carbonates, 745 chalcogenides, 739–742 chlorides, 736–737 coordination, 745–750, 746t–747t fluorides and complexes, 730–736, 735t–736t halides, 730–739, 731t hydrides, 722–724 hydrocarbyl, 752 hydroxides, 724–730 iodides, 738 nitrides, 742–743 nonstoichiometric, 1797–1798 organometallic, 750–752 overview of, 721–722 oxides, 724–730 oxychlorides, 738 oxyfluorides, 734–736, 736t oxyhalides, 738

oxyiodides, 738 oxyselenides, 741 oxysulfides, 740 oxytellurides, 741–742 phosphates, 744–745 phosphides, 743 pnictides, 742–744 selenides, 740–741 sulfates, 745 sulfides, 739–740 tellurides, 741–742 coordination complexes in solution, 771–782 inorganic ligands, 771, 772t–775t, 781 organic ligands, 776t–780t, 781–782 d transition elements v., 2 discovery of, 4, 5t, 699–700 history of, 4, 699–700 ionization potentials of, 1874t, 1875 isotopes of, 9–10, 12, 700–702, 701t production of, 702–704 laser spectroscopy of, 1873 magnetic properties of, 2356–2357 metallic state of, 717–721 alloys and intermetallic compounds, 719–721 metal, 717–719 structure of, 2385–2386 natural occurrence of, 703–704, 1756, 1804 in marine organisms, 1809 nuclear properties of, 700–702 oxidation states of, 2526–2527 in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t partitioning of, in HLW, 712–713, 2756–2757 as plutonium α- and β-phase stabilizer, 897 in plutonium alloy, americium v., 931, 931f plutonium and δ-phase plutonium influence of, 985 from plutonium decay, 985, 985f pyrochemical methods for, molten chlorides, 2697–2698 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f, 2525, 2525f in RTILs, 2689 separation and purification, 704–717 biotechnology, 717 chromatography, 714–716 coprecipitation, 716 electrodeposition, 717 solvent extraction, 705–713, 706f–708f, 709t studies on, 11 synthesis of, 4 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t

Subject Index

I-75

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f Neptunium (III) in acidic media, 753 chlorides of, magnetic data, 2229–2230, 2230t coordination compounds of, 745, 746t–747t cyclooctatetraene, 751–752 cyclopentadienyl, 750 halide complexes of, 739 hydrolytic behavior of, 768, 2546, 2548t magnetic properties of, 2261–2262 with pyrochemical processes, 2697–2698 redox behavior of, Nernst plot for, 3099f, 3100, 3108 speciation of, 3111t–3112t, 3116–3117 Neptunium (IV) absorption spectra of, 764–766 in acidic media, 753 carboxylates, EXAFS investigations of, 3137–3140, 3147t–3150t coordination complexes of, 745, 746t–747t, 748 preparation of, 745, 748 separation of, 748 coulometry for, 791 cyclooctatetraene, 751 cyclopentadienyl, 750–751 energy level of, 2067 equilibrium constants of, 771, 772t–775t, 781 fluoro complexes of, 734, 735t halide complexes of, 739 hydration of, 2531 hydrolytic behavior of, 768–769 hydroxide, synthesis of, 727–728 isomer shift of, 793–794, 794f magnetic properties of, 2257–2261 in mammalian tissues circulation clearance of, 3368–3369, 3368f–3375f, 3377 initial distribution, 3342t, 3352 transferrin binding to, 3365 with pyrochemical processes, 2697–2698 redox behavior of, Nernst plot for, 3099f, 3100, 3108 reduction of, 762 by americium (V), 1336 to neptunium (III), 745 speciation of, 3106–3108, 3111t–3112t, 3135–3136 Neptunium (V) absorption spectra of, 764–765 in acidic media, 753 adsorption, Pseudomonas fluorescens, 3182

coordination complexes of, 746t–747t, 748–749 cation-cation interaction in, 748 preparation of, 748–749 properties of, 748–749 detection of limits to, 3071t RAMS, 3035, 3036f VOL, 3061 equilibrium constants of, 771, 772t–780t, 781–782 fluoro complexes of, 734, 735t halide complexes of, 739 hydrolytic behavior of, 727, 769–770 in hydrosphere, 1807–1810 hydroxide, synthesis of, 727 isomer shift of, 793–794, 794f magnetic properties of, 2247–2257 mobility of, 1814 Mo¨ssbauer spectroscopy of, 793 oxidation of, 762 polarography for, 791–792 with pyrochemical processes, 2697–2698 redox potential of, 756–757 reduction of, 762 by americium (V), 1336–1337 separation of, HDEHP for, 2651, 2651f speciation with XAFS, 795 Neptunium (VI) absorption spectra of, 764 in acidic media, 753 coordination complexes of, 746t–747t, 749 coulometry for, 791 detection of RAMS, 3035 VOL, 3061 equilibrium constants of, 771, 772t–775t, 781 fluoro complexes of, 734, 735t halide complexes of, 739 hydrolytic behavior of, 770 hydroxide, synthesis of, 727 infrared spectra of, 764 isomer shift of, 793–794, 794f magnetic properties of, 2240–2247 oxidation of, 761–762 redox potential of, 756–757 reduction kinetics of, 760–761 separation of, PUREX process, 2732 speciation of, 3111t–3112t, 3124–3125 Neptunium (VII) absorption spectra of, 764 coordination complexes of, 746t–747t, 749–750 preparation of, 749–750 properties of, 749–750 detection of, NMR, 3033 fluoro complexes of, 734, 735t

I-76

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Neptunium (VII) (Contd.) hydrolytic behavior of, 770 hydroxide, synthesis of, 726–727 infrared spectra of, 764 isomer shift of, 793–794, 794f in solution, 1933 speciation of, 3111t–3112t, 3124–3125 Neptunium carbide entropy of, 2196, 2197t formation enthalpy of, 2195–2196, 2197t high-temperature properties of, 2198, 2198f, 2199t Neptunium carbonates, structural chemistry of, 2426–2427, 2427t Neptunium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Neptunium dioxide crystal structure of, 2287–2288, 2287f enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 in gas-phase, 2148–2149, 2148t heat capacity of, 2138–2141, 2139f, 2142t, 2272–2273, 2273f magnetic properties of, 2236–2237, 2237f, 2282–2288 magnetic susceptibility of, 2283 neptunium hexafluoride from, 732–733 neutron scattering of, 2284–2286, 2285f–2286f phase diagram of, 724–725, 725f RXS of, 2288 scattering experiments of, 2236–2237, 2237f stability of, 725–726 structure of, 2394 synthesis of, 725 Neptunium disulfide preparation of, 739 properties of, 739–740 Neptunium hexafluoride chemical behavior of, 733 crystal structure of, 731t energy level analysis of, 2083–2085, 2083t, 2085f lattice parameters of, 731t, 732 magnetic susceptibility of, 2243 physical properties of, 733 preparation of, 732–734 structural chemistry of, 2419, 2421, 2421t studies of, 1938 thermodynamic properties of, 2160–2161, 2160t, 2162t–2164t Neptunium hydrides entropy of, 2188, 2189t formation enthalpy of, 2187–2188, 2187t, 2189t, 2190f

high-temperature properties of, 2188–2190, 2190t structure of, 2403–2404 Neptunium monophosphide, 743 Neptunium monoxide dissociative energy of, 2149–2150, 2150f in gas-phase, 2148–2149, 2148t structure of, 2394 Neptunium nitride, 742–743 preparation of, 742–743 properties of, 743 Neptunium oxides structure of, 2394 thermodynamic properties of, 2136, 2136t Neptunium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Neptunium pentafluoride, structural chemistry of, 2416, 2419, 2420t crystal structure of, 731t preparation of, 731–732 Neptunium pentahalides, structural chemistry of, 2416, 2419, 2420t Neptunium pentaoxide, synthesis of, 726 Neptunium pentasulfide preparation of, 740 properties of, 740 Neptunium phosphates, structural chemistry of, 2430–2433, 2431t–2432t Neptunium pnictides, structure of, 2409–2414, 2410t–2411t Neptunium series (4n þ 1), 24f actinium–225 in, 20, 24f in nature, 27 thorium–229 from, 53 Neptunium sesquioxide, formation enthalpy of, 2143–2146, 2144t, 2145f Neptunium sulfates, structural chemistry of, 2433–2436, 2434t Neptunium tetrabromide, preparation of, 737 Neptunium tetrachloride identification of, 737 magnetic properties of, 2258t, 2260–2261 oxychloride preparation from, 738 preparation of, 736 properties of, 736–737 Neptunium tetrafluoride absorption spectra of, 2068, 2070f crystal structure of, 731t preparation of, 730–731 thermodynamic properties of, 2165–2169, 2166t Neptunium tetrahalides, structural chemistry of, 2416, 2418t Neptunium tribromide, preparation of, 737–738 Neptunium trichloride oxychloride preparation from, 738 preparation of, 737

Subject Index

I-77

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Neptunium trifluoride crystal structure of, 731t preparation of, 730 Neptunium trihalides, structural chemistry of, 2416, 2417t Neptunium triiodide, preparation of, 738 Neptunium trisulfide preparation of, 740 properties of, 740 Neptunium–235 stability of, 702 synthesis of, 702–703 Neptunium–236 stability of, 702 synthesis of, 702–703 Neptunium–237 absorption cross section of, 2233 from americium-241, 1828 detection of AMS, 3062–3063 γS, 3302 ICPMS, 3327–3328 limits to, 3071t MBAS, 3043 MBES, 3028 NAA, 3055–3057, 3056t, 3058f NMR, 3033 PCNAA, 3307 αS, 3294–3295 TIMS, 3314–3315 determination of, 705, 706f, 783–785 with ICPMS, 789, 790f DIDPA extraction of, 1276 environmental hazards of, 1807 half-life of, 700, 703 mo¨ssbauer spectroscopy of, 793 natural occurrence of, 704, 782–783, 1756 from neutron irradiation, 1756–1757 nuclear properties of, 3277t plutonium–236 and 238 from, 703, 817, 1758 from plutonium-241, 705, 706f, 783–785 protactinium-233 from, 171 significance of, 700 SIMS of, 788–789 synthesis of, 701–703 toxicity of, 1820 Neptunium–238 half-life of, 702 nuclear properties of, 3277t Neptunium–239 detection of, INAA, 3304–3305 determination of, 784 half-life of, 702 natural occurrence of, 704, 1756 nuclear properties of, 3277t SIMS of, 788–789 synthesis of, 702

from uranium–238, 702, 704 from uranium–239, 255 Neptunocene properties of, 1946–1948 structure of, 2486, 2488t Neptunyl (V) disproportionation of, 759 speciation of, 3111t–3112t, 3121–3122, 3133–3134 stability constants of, 2571, 2572f Neptunyl (VI), speciation of, 3111t–3112t, 3122–3123 Neptunyl ion aqueous solution absorption spectra of, 2080, 2081f charge-transfer transition of, 2089 complexes of porphyrins and phthalocyanines, 2464t, 2465–2466, 2466f–2467f structure of, 2400–2402 complexes with, 1923 crown ether complex of, 2449t, 2450 in DDP, 2706 formates of, 2257 hydration number of, 2531, 2533t hydrolytic behavior of, 2553 ligands for, 3422–3423 magnetic properties of, 2240–2247, 2255t in mammalian tissues bone, 3404 circulation clearance of, 3368–3369, 3368f–3375f, 3377, 3384–3386 initial distribution, 3342t–3344t, 3355–3356 transferrin binding to, 3364 reduction of, 2591 stability constants of, 2576, 2576f study of, 1931, 1933 Nernst analysis of berkelium (IV) and (III), 3108 of neptunium (IV) and (III), 3108 Nernst equation, for aqueous actinide elements, 3097–3098 Nernst plot for aqueous actinide elements, 3099, 3099f of neptunium, 3099, 3099f, 3108 Network structures, factors in, 579 Neutralized cladding removal waste (NCRW), TRUEX process for, 2740 Neutron activation analysis (NAA) for berkelium, 1484 californium-252 for, 1828 for environmental actinides, 3055–3057, 3056t, 3058f fundamentals of, 3302–3303 INNA, 3303–3305 for neptunium, 785–786, 789 RNNA, 3305–3307

I-78

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Neutron activation analysis (NAA) (Contd.) for trace analysis, 3302–3307 for uranium, 635–636 Neutron capture in actinide elements, 1828 berkelium, 1444 curium curium–244, 1400 production of, 1400 einsteinium from, 1582 plutonium isotope formation, 825–826, 825f plutonium–239 formation with, 823–824 Neutron crystallography, for electronic structure, 1770 Neutron diffraction for coordination geometry study, 602–603 description of, 2383 for hydration study, 2528 sources for, 2383 for structural chemistry, 2383–2384 types of, 2383–2384 X-ray diffraction v., 2383 Neutron emissions from actinide elements, 1827–1828 actinium for, 43 californium–252 for, 1505–1507, 1506t californium–254 for, 1505, 1506t curium–248 for, 1505, 1506t Neutron irradiation for actinide and transactinide element production, 1756–1761, 1761t actinium from, 1756 of americium, 1268 of californium–252, 1507 neptunium from, 1757 in nuclear power, 1826–1827 of plutonium, 1757 protactinium from, 1756 for SNF transmutation, 1811–1812 of uranium, 3–4, 1756–1757 Neutron scattering for actinide element study, 14 advantages of, 2232–2233 disadvantages of, 2233–2234 history of, 2232 magnetic dipole moment and, 2232 of neptunium dioxide, 2284–2286, 2285f–2286f RXS v., sample size, 2237–2238 of uranium dioxide, 2274, 2285–2286, 2286f tetrachloride, 2248, 2250f x-ray scattering v., sample size, 2233–2234 Neutron spectroscopy (NS), for environmental actinides, 3026t, 3029

Neutrons in actinide synthesis, 3–4, 8–9 thermonuclear device production of, 9 NFL. See Non-Fermi liquid Nickel, plutonium melting point and, 897 Ningyoite, uranium in, 259t–269t, 275 Niobates, of uranium, uranium (IV), 277–280 Niobium foil, berkelium adsorption on, 1451 Niobium, protactinium purification from, 178–186 ion exchange, 180–181, 180f precipitation and crystallization, 178–186 solvent extraction and extraction chromatography, 181–186, 183f NIR-VIS. See Near-infrared and visible spectroscopy Nitrate solution, radiolysis of plutonium in, 1144–1145 Nitrates of actinide elements, 1796 of actinyl complexes, 1927, 1928t, 1929f complexes of, 2581 of curium, 1413t–1415t, 1422 of neptunium, equilibrium constants for, 773t of plutonium, 1167–1168 of protactinium (V), 212–213, 214t in pyrochemical methods, 2704 structural chemistry of, 2428–2430, 2429f of thorium, 106–108, 107f extraction of, 107–108 properties of, 106–107 structure of, 106, 107f synthesis of, 106 ternary, 108 Nitric acid actinide stripping with, 1280 berkelium, extraction in, 1448–1449 curium extraction in, 1407 separation in, 1409, 1434 dubnium, extraction in, 1703–1704 mendelevium extraction with, 1633 neptunium absorption spectra in, 764 extraction from, 706–708, 708f nobelium extraction with, 1640 plutonium processing in, 836 anion-exchange chromatography, 848–849 PUREX process, 841 reduction and oxidation reactions, 1139–1140 seaborgium, study in, 1710–1711 TRPO actinide extraction in, 2752–2753 uranates (V) and (IV) dissolution in, 381–382 uranium compound dissolution in, 632

Subject Index

I-79

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 metal reactions with, 328 oxide reactions with, 370–371 Nitride oxides, of actinides, 1989–1991 Nitride-nitride process, 2723–2725 actinide nitride recovery, 2724–2725 dissolution step, 2724 historical development of, 2723–2724 Nitrides of actinides, 1987–1989 of americium, 1317–1319 of neptunium, 742–743 of plutonium, 1017–1021, 3212–3213 phase diagram, 1017, 1017f preparation of, 1018 properties of, 1019, 1021t reactions of, 3222–3223 structure of, 1019, 1020t thermodynamic properties of, 2200–2203 enthalpy of formation, 2197t, 2200–2201, 2201f entropy, 2197t, 2201–2202 high-temperature properties, 2199t, 2202 of thorium, 97–99, 98t, 99f, 1989 halide reaction with, 98–99 lattice constant of, 99 preparation of, 97–98 structure of, 98–99 of uranium, 407–411, 408t–409t, 411f, 1988–1989, 3215 bromides, 497, 500 chlorides, 500 fluorides, 489–490 iodides, 499–500 phases, 407, 410, 411f preparation of, 410 properties of, 408t–409t stability of, 410 structure of, 410–411 Nitrilotriacetate (NTA) plutonium complex with, 1176–1177, 1178t, 1181 separation with, 2640–2641 Nitrogen americium ligands of, 1363 plutonium hydrides reaction with, 3217–3218 uranium metal reactions with, 327–328, 327t Nitrohalides, thermodynamic properties of, 2182–2185, 2187t NMR. See Nuclear magnetic resonance Nobelium, 1636–1641 atomic properties, 1634t, 1639 chemical properties of, 1640–1641, 1646t in curium complex, 1413t–1415t, 1422 discovery of, 5t, 13 dubnium v., 1703–1706 half-life of, 1637, 1638t isotopes, 1637, 1638t

lanthanide elements v., 2 metallic state of, 1639 oxidation states of, 2525–2526 in aqueous solution, 1774–1776, 1775t preparation and purification, 1638–1639 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f solution chemistry, 1639–1641 synthesis of, 13 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t Nobelium–253, x-ray emission of, 1634t, 1639 Nobelium–255 cation-exchange and coprecipitation experiments, 1639–1640 production of, 1637–1639 Nobelium–257, from rutherfordium–261, 1698 Nobelium–259, half-life of, 1637 Noble metals in intermetallic compounds of uranium, 325–326 reductive extraction of, 2717–2719 Nonaqueous separation methods overview of, 853 for plutonium, 853–857 combination processes, 856–857 halide volatility processes, 855 pyrochemical, 853–854 RTILs, 854 supercritical fluid extraction, 855–856 Non-Fermi liquid (NFL) description of, 2348 models for, 2349–2350 quantum critical point and, 2348–2350 Non-Kramers ion description of, 2228 uranium (IV), 2254 NRA. See Nuclear reaction analysis NS. See Neutron spectroscopy NTA. See Nitrilotriacetate Nuclear criticality, hazard of, 3255–3256 Nuclear energy. See also Thermoelectric generator actinide elements for, 1826–1827 californium–252 for, 1507 curium for, 1398–1400 decontamination after, 826, 828–830 environment and, 3013 fuels for, 826 plutonium for, 4, 813 carbides, 744 metals and intermetallic compounds, 862 nitrides, 1019, 1021t

I-80

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Nuclear energy (Contd.) oxides, 1023–1025 plutonium–239, 815, 820 uranium oxides with, 1070–1071 thorium for, 53 uranium for, 255 plutonium oxides with, 1070–1071 Nuclear fission. See also Nuclear energy of uranium discovery of, 255 uranium–235, 256 Nuclear ‘incineration,’ of SNF, 1811–1812 Nuclear magnetic moments, of californium, 1872 Nuclear magnetic resonance (NMR) for environmental actinides, 3033, 3034t for hydration study, 2528 for ligand exchange reactions, 607–608 intramolecular, 617, 617f organic and inorganic, 614–615 for magnetic susceptibility measurements, 2226 of neptunium, 766 of organometallic actinide compounds, 1800–1803 for structure study, 589 of thorium hydrides, 64 of uranium dioxide, 2280 of uranyl (V), 3121–3122 Nuclear properties of actinium, 20–26, 21f–26f, 22t–23t of americium, 1265–1267 of berkelium, 1445–1447 of curium, 1398–1400, 1399t of einsteinium, 1580–1583, 1581t of neptunium, 700–702 of plutonium, 815–822 of protactinium, 164–170 of superactinide elements, 1735–1737 alpha emission, 1735 of thorium, 53–55, 54t–55t of uranium, 255–257 Nuclear reaction analysis (NRA), for environmental actinides, 3059t, 3061 Nuclear spent fuel. See Spent nuclear fuel Nuclear spins, of californium, 1872 Nuclear systematics, development of, 10 Nuclear waste. See also Radioactive waste actinide chemistry for, 3 californium for, 1538 curium–244 in, 1759 disposal of, 1811–1813 in environment, 3013 hydride-dehydride or -oxidation process for, 996, 996f immobilization of brannerite for, 280

pyrochlore for, 278–279, 279f zirconolite for, 277–278 neptunium hydrated oxides and disposition of, 726 plutonium in iron and, 1138–1139 metal and intermetallic compounds, 862 oxides for, 1023–1024 phosphates for, 1170–1171 polymerization of, 1150 precipitation from, 2634 protactinium clean-up in, 189 scope of concern of, 3202 uranium predictions in, 270 Nuclear weapons. See also Thermonuclear device actinide chemistry for, 3 aging of, 979–980 environment and, 3013 hydride-dehydride or -oxidation process for, 996, 996f neptunium–237 in, 703 plutonium in, 813, 1757–1758 metal and intermetallic compounds, 862 testing of, 1805–1806 n-Octyl(phenyl)-N,N-diisobutyl-carbamoyl methylphosphine oxide (CMPO) actinide extraction with, 1769, 2738–2752 curium separation with, 1409, 1434 degradation, cleanup, and reusability of, 2747–2748 development of, 2652, 2655 extractant comparison with, 2763–2764, 2763t for extraction chromatography, 2748–2749 magnetically assisted chemical separation with, 2750–2752 neptunium extraction with, 707–708, 713 overview of, 2738 separation with, 2652 in SLM separation, 2749–2750, 2749f transuranium element recovery with, 1407–1408 in TRUEX process, 2739 in TRU•Spec, 3284 Oklo, Gabon pitchblende at, 1804–1805, 3016 plutonium–239 formation at, 824 uraninite at, 274 uranium deposits at, 271–272 Olefins, organoactinide complexes hydrogenation, 2996–2997 polymerization, 2997–2999 OLGA. See On-Line Gas Analyzer Oligonucleotides, uranyl ion for synthesis of, 631

Subject Index

I-81

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 One-atom-at-a-time chemistry challenges of, 1661–1662 chemical procedures of, 1662–1666 gas-phase chemistry, 1663–1665 overview of, 1662–1663 solution chemistry, 1665–1666 for element identification, 10 for mendelevium identification, 13 production methods and facilities required for, 1662, 1662t transactinide element study with, 1661–1666 for transactinides, 3 One-electron band model beyond, 2326 for actinide metals, 2324–2325 DFT with, 2326–2328 On-Line Gas Analyzer (OLGA) for bohrium study, 1711 for isothermal chromatographic systems, 1664, 1705 for rutherfordium study, 1693 for seaborgium study, 1707–1708, 1709f Optical properties of liquid plutonium, 963 of uranium dioxide, 2276–2278, 2277f Optical spectroscopy. See also Absorption spectra of actinide elements, 2013–2103 charge-transfer transitions and actinyl structures, 2085–2089 crystal-field interaction, 2036–2056 divalent, 2077–2079 free-ion interactions, 2020–2036 lanthanides v., 2016, 2017f penta- and hexavalent, 2079–2085, 2080t tetravalent, 2064–2076 trivalent, 2056–2064 of californium, californium (III), 2091, 2092f of fluorides, 2069–2070, 2069f–2070f free-ion interactions for, 2020–2036 of lanthanide elements, actinides v., 2016, 2017f of neptunium, 763–766 of organometallic actinide compounds, 1800 overview of, 2014 of protactinocene, 1951 of uranium, uranium (III), 2091, 2092f 4f Orbital free-ion parameters of, 2038, 2038t 5f orbital v., 1901, 2016, 2017f, 2062–2064, 2063f, 2353–2354 SIM of, 2343–2344 Wigner-Seitz radius of, 2310–2312, 2311f 5d Orbital electronic structures of, 1672–1673, 1672t

relativistic destabilization of, 1666, 1667f Wigner-Seitz radius of, 2310–2312, 2311f 5f Orbital in actinide metals, bonding, 2319 in actinides, 1–2, 10–11, 1770–1771, 1894–1895, 1896f, 1896t bonding of, 1898 contraction of, 1901 metallic state, 1787–1789 organometallic compounds, 1800–1803 role of, 1917–1918, 1918f superconductivity, 1789–1790 in americium, 1299–1301 in back-bonding, 576 in berkelium, 1445, 1456–1458, 1461, 1472–1473 in californium, 1526–1527, 1546, 1562–1563 in curium, stability of, 1402 in einsteinium, 1578–1579, 1586–1588 electronic excitations of, 2049–2050 electronic structure of, 2019–2020 free-ion energy levels of, 2014–2016, 2015f free-ion parameters of, 2038–2039, 2038t general observations of, 2329–2333 Hill plot, 2331–2333, 2332f low-symmetry structures, 2330–2331, 2331t narrow bands, 2329–2330, 2329f ground states of, 2042 hydrolytic behavior of, 3100 luminescence decay of, 2101–2102, 2101f lifetimes of, 2099–2100, 2099t, 2100f magnetic properties from, 719–720, 2353, 2356 metallic state and phenomena of, 2307–2373 basic properties, 2313–2328 cohesion properties, 2368–2371 general observations, 2328–2333 magnetism, 2353–2368 overview of, 2309–2313 strong correlations, 2341–2350 strongly hybridized, 2333–2339 superconductivity, 2350–2353 weak correlations, 2339–2341 4f orbital v., 1901, 2016, 2017f, 2062–2064, 2063f, 2353–2354 6d orbital v., 1901 in plutonium, 814, 921–925 in bonding, 1192, 1193f δ-phase, 925 ions, 1113–1114 α-phase, 924 in plutonium dioxide, 1196–1199, 1197f, 1200f in plutonium hexafluoride, 1194–1196, 1195f

I-82

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 5f Orbital (Contd.) in plutonocene, 1199–1203, 1201f–1202f qualitative representations of, 1193, 1194f relativistic effects on, 1898 SIM of, 2343–2344 strongly hybridized, 2333–2339 Fermi surface measurements, 2334 photoemission measurement background, 2334–2336 strong correlations, 2341–2350 UIr3 PES, 2336–2339, 2337f weak correlations, 2339–2341 in transactinide elements, 1654, 1659 unpaired electrons in, 1909–1910 in uranium bonding, 577 uranyl, 1915–1916 Wigner-Seitz radius of, 2310–2312, 2311f 6d Orbital as acceptor orbitals, 1901 in actinides, role of, 1917–1918, 1918f in cyclopentadienyl complexes, trivalent, 2803 electronic structures of, 1672–1673, 1672t ionization potentials of, 1673–1675, 1673t, 1674f 5f orbital v., 1901 relativistic destabilization of, 1666, 1667f in transactinide elements, 1659 7p Orbital filling of, 1722t, 1723, 1728 transactide contraction of, 3 in transactinide elements, 1659 7s Orbital filling of, 1722t, 1729 relativistic stabilization of, 1666, 1667f–1668f transactide contraction of, 3 8s Orbital filling of, 1722t, 1729 in transactinide elements, 1659 9p Orbital bonding of, 1732 filling of, 1733 9s Orbital bonding of, 1732 filling of, 1732–1733 f Orbital in actinide and lanthanide elements, 1894–1895, 1896f, 1896t angular momentum, 2041 crystal formation with, 2047–2048 energy levels and stability of, 2014–2016, 2015f free-ion interactions of, 2024, 2025t–2026t HF calculations of, 2032, 2034f, 2035 ionicity of bonding in, 2556, 2557f relativistic effects on, 1898 spin-orbit coupling on, 1949–1950

Orbital energies, of actinides v. lanthanides, 1898, 1899f 5g Orbital, filling of, 1722t, 1731 6f Orbital, filling of, 1722t, 1731 7d Orbital, filling of, 1732 8p Orbital, filling of, 1722t, 1730–1731 6p Orbital, in actinides, role of, 1917–1918, 1918f Orbital interaction diagram for actinocenes, 1945, 1946f for plutonium dioxide, 1197f, 1200f hexafluoride, 1195f for plutonocene, 1201f for uranyl (VI) ion, 577, 577f 4d Orbital, relativistic destabilization of, 1666, 1667f 5s Orbital, relativistic stabilization of, 1666, 1667f 6s Orbital, relativistic stabilization of, 1666, 1667f–1668f Ore thorium processing and separation from, 56–59 from monazite, 56–58 problems with, 58 from uraninite or uranothorianite, 58 uranium processing and separation from, 302–317 complexities of, 302–303 methods of, 302 pre-concentration, 303–304 recovery from leach solutions, 309–317 roasting or calcination, 304 Organic acids, EXAFS analyses in, 3137–3140 model systems, 3138–3139 natural systems, 3139–3140 Organic phases, for solvent extraction, 840–841 Organoactinide chemistry, 2799–2894 bimetallic complexes, 2889–2893 bond distance, 2893 bridging ligands, 2889 cyclopentadienyl complexes, 2890 metal-metal interaction, 2891–2892, 2893f metathesis reactions, 2889 overview of, 2889 phosphine groups, 2890 phospholyl ligand, 2890–2892, 2892f carbon-based ancillary ligands, 2800–2867 alkyl ligands, 2866–2867 allyl, pentadienyl and related ligands, 2865–2866 cyclooctatetraenyl complexes, 2851–2858 cyclopentadienyl complexes, 2800–2851 other carbocyclic ligands, 2858–2865

Subject Index

I-83

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 heteroatom-based ancillary ligands, 2876–2889 bis(trimethylsilyl)amide, 2876–2879 other, 2888–2889 pyrazolylborate, 2880–2886 tris(amidoamine), 2886–2888 heteroatom-containing ancillary ligands, 2868–2876 dicarbollide ligands, 2868–2869 other nitrogen-containing ligands, 2873–2876 phospholyl ligands, 2869–2871 pyrrole-based ligands, 2871–2873, 2873f–2874f neutral carbon-based donor ligands, 2893–2894 Organoactinide complexes. See also Organometallic compounds alkyne dimerization with, 2930–2947 promotion of, 2938–2947, 2940f–2941f terminal, 2930–2935 terminal ansa-, 2935–2937 alkyne hydroamination, 2981–2990 kinetic studies of, 2986–2990 neutral organoactinide complex promotion, 2981–2986 alkyne oligomerization, 2923–2930 amine, silane reactions, 2978–2981 azide and hydrazine reduction, 2994–2996 catalytic processes promoted by, 2911–3006 constrained-geometry hydroamination, 2990–2994 heterogeneous, 2999–3006 active site assessment, 3000–3002 alkane activation, 3002–3006 arene hydrogenation, 2999–3000 olefin hydrogenation, 2996–2997 olefin hydrosilylation, 2953–2978 of alkenes, 2969–2974 promotion for alkynes, 2974–2978 promotion for terminal alkynes, 2964–2969 of terminal alkynes, 2953–2964 olefin polymerization, 2997–2999 reactivity of, 2912–2923 activation modes, 2912–2913 alkyne and silane stoichiometric reactions of, 2916–2918, 2917f [(Et2N)3U][BPh4], 2922–2933 stoichiometric reactions of, 2913–2916, 2914f–2915f synthesis of ansa- complexes, 2918–2920, 2920f synthesis of high-valent organouranium complexes, 2920–2922, 2921f terminal alkyne cross dimerization, 2947–2952, 2948f–2949f

Organoimido complexes with bis(trimethylsilyl)amide, 2877–2879 with cyclopentadienyl, 2833–2835 with pentamethyl-cyclopentadienyl, 2916 Organometallic chemistry history of, 1942–1943 of plutonium, 1182–1191 pi-bonded ligands, 1188–1191 sigma-bonded ligands, 1182–1187 of uranium, 630–631 Organometallic compounds of actinide elements, 1800–1803, 1942–1967 actinocenes, 1943–1952 cyclopentadienyl complexes, 1952–1959 miscellaneous, 1965–1967 six- and seven-membered ring complexes, 1959–1962 uranium (III) complexes, 1962–1965 of berkelium, 1464t–1465t, 1471 of californium, 1541 in gas phase, 1560 of curium, 1413t–1415t, 1423–1424 of einsteinium, 1611 history of, 2467–2468 of lanthanides, 2468 of neptunium, 750–752 cyclooctatetraene, 751–752 cyclopentadienyl, 750–751 other, 752 overview of, 1800–1801 structural chemistry of, 2467–2497 cyclooctatetraene, 2485–2487, 2488t, 2489f cyclopentadienyl, 2468–2485 other, 2487–2491, 2490t–2491t, 2492f–2493f of uranium, magnetic properties of, 2252–2254 Organophosphorus esters, fermium complexes with, 1629 Organophosphorus ligands carboxylates v., 2585t–2586t, 2588 complexes of, 2585t–2586t, 2587–2590 Organophosporus extractants for americium, 1271–1284 carbamoylmethylenephosphine oxide, 1278–1284 DBBP, 1274 DIDPA, 1276 HDEHP, 1275–1276 TBP, 1271–1274 TRPO, 1274–1275 for berkelium, 1479 for curium, 1407 extraction properties of, 1283 for separation, 2651–2652, 2680–2682 Organothorium complexes active sites of, 3000–3002

I-84

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Organothorium complexes (Contd.) examples of, 116 study of, 117 Organouranium complexes azide and hydrazine catalytic reduction by, 2994–2996 high-valent synthesis of, 2920–2922, 2921f Orthophosphates of berkelium, 1470–1471 impurities in, 2058–2059 Orthosilicates, of uranium, 261t uranium (IV), 275–276 Oscillator strengths, of uranium chlorides, 447–448 halides, 442–443 Osmium, in hassium studies, 1712–1715, 1714f–1715f Outer sphere complexation, 2563–2566, 2566f, 2567t confusion over, 2564 conversion of, 2564–2565 description of, 2564 stability constant, 2565, 2566f thermodynamic data, 2566, 2567f Oxalates of actinide elements, 1796 of americium, 1322, 1323t of californium, 1546 of curium, 1413t–1415t, 1419, 1421–1422 of plutonium, 1173–1175 precipitation with, 836–837, 837 precipitation with, 2633–2634 structural chemistry of, 2441t–2443t, 2445–2446, 2445f of thorium, 114 as ligands, 131–132, 132t of uranium, 603–605, 604t Oxalic acid actinide stripping with, 1280 protactinium (V), 219 Oxidation of americium americium (II), 1337 americium (III), 1333–1335, 1333f americium (IV), 1334 of berkelium, 1460–1461, 1485 berkelium (III), 1448 of californium, 1526, 1546–1547 for cyclopentadienyl complexes, pentavalent, 2847 of neptunium neptunium (V), 762 neptunium (VI), 761–762 potential, 755 photochemical, of polydeoxynucleotides, 630–631 of plutonium by actinide ions, 1133–1137, 1134t–1135t

in air, 974, 975f of alloys, 975f, 976, 977t in aqueous solution, 1117–1146 metal and intermetallic compounds of, 3226f, 3227–3235, 3227t, 3229t moisture-enhanced, 974–976 by nonactinide ions, 1137–1143 preparation and stability of, 1125–1133 pyrophoricity, 975f, 976–977, 978f self-sustained, 3233–3235 of uranium carbonate leaching, 307–308 dioxide solid solutions, 394 processing, 305 self-sustained, 3245–3246 uranium (III), 598 by uranium hexafluoride, 562 Oxidation states of actinide cations, 2525–2527, 2525f of actinide elements, 1, 1774–1784 complex-ion formation, 1782–1784 hydrolysis and polymerization, 1778–1782 ion types, 1777–1778, 1777t, 1779f, 1780t ions in aqueous solutions, 1774–1776, 1775t of actinocenes, 1946–1948 of actinyl, 1928 of americium, 1324–1338, 2526 autoreduction, 1330–1331 disproportionation, 1331–1332 electrode potentials and thermodynamic properties, 1328–1330, 1329t hydration and coordination numbers, 1327, 1328f preparation of, 1325–1327 radiolysis, 1337–1338 redox kinetics, 1333–1337 of berkelium, 1472–1473 of californium, 1528, 1545, 1548, 1562, 2526 coordination number and bond distance with, 3093 of curium, 1416, 2526 of darmstadtium, 1720 determination of, 2725–2726 of dubnium, 1703–1704 of einsteinium, 1578, 2526 of element 112, 1720, 1724t of element 114, 1724t, 1727 of element 115, 1724t, 1727–1728 of element 116, 1724t, 1728 of element 117, 1724t, 1728 of element 118, 1724t, 1729 extraction for, 3287 of fermium, 2526 ionic radii and, 2558 of meitnerium, 1720 of mendelevium, 2526

Subject Index

I-85

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 of neptunium, 710, 710f, 724, 752–763, 2526–2527 control of, 759–763, 760t examples of, 752–753 redox potentials of, 753–755 stability of, 752 of nobelium, 2525–2526 of plutonium, 814, 1123–1125, 1124f–1125f, 1126t–1130t, 2525–2527, 2525f adjustment of, 849 equilibria, 1123–1125, 1124f–1125f, 1126t–1130t in separation of, 831–835 sorbed, 3175–3176 of protactinium, 161, 209, 2526 of roentgenium, 1720 of thorium, 117, 2526 of transactinide elements, stability of, 1673–1675, 1673t, 1674f–1675f of uranium, 257, 276–277, 328, 590, 1914–1915, 2526 in uraninite, 274–275 of uranyl, 1928 Oxide slagging, for plutonium reprocessing, 2709–2710 Oxide-metal processes, 2717–2721 actinide and rare earth separation, 2719, 2720t, 2721f actinide electrorecovery, 2719–2721 actinide recovery from HLLW, 2717 reductive extraction actinide and rare earth element, 2719 noble metals, 2717–2719 Oxide-oxide process, as pyrochemical method, 2704 Oxides of actinides, 1790, 1791t–1795t, 1796–1798 matrix-isolated, 1970–1976 of actinyl ions, 1932–1933, 1932t of americium, 1303, 1305t–1312t, 1313–1314 americium dioxide, 1303, 1313 coordination of, 1357–1358, 1358f phase relationships and thermodynamic data, 1303 of berkelium, 1464t–1465t, 1466–1467 of californium, 1530t–1531t, 1534–1538 behavior of, 1537–1538 complex, 1538 preparation of, 1534–1535 sesquioxide, 1535–1537, 1535f of curium, 1413t–1415t, 1419–1420 description of, 2388 of einsteinium, 1595–1599 of hassium, 1712–1715, 1714f–1715f magnetic properties of, 5f1 compounds, 2244, 2245t of neptunium, 724–730

dioxide, 725–726 hydrated, 726 pentaoxide, 726 phase diagram of, 724, 725f ternary, 728–730 of plutonium, 1023–1049, 3206–3212 applications of, 1023–1025 chemical properties, 1048–1049 container material compatibility, 1049 dioxide, 1031–1034 hazards of, 3202, 3257–3258, 3258t interface of, 976–977, 978f melting behavior, 1045 monoxide, 1028–1029 oxygen diffusion, 1044–1045 phase diagram, 1025, 1026f, 1039–1041, 1040f, 3206–3208, 3207f, 3211–3212, 3211f phase equilibria, 1025–1026, 1026f preparation of, 1028–1036, 3206–3207 reaction rates of, 3219–3222 safe storage, 3260–3262, 3261f sesquioxide, 1029–1031 solid-state structures, 1027t, 1036–1044, 1038f–1040f, 1042f–1043f ternary and quarternary, 1065–1069, 1066t–1067t ternary with actinides, 1070–1077 ternary with lanthanide oxides, 1069–1070 thermodynamic properties, 1047–1048, 1047t vaporization behavior, 1045–1047, 1046f of protactinium, 195–197 binary, 195, 196t polynary, 195–197, 197t of seaborgium, 1707, 1709 structural chemistry of, 2388–2399 actinium, 2390 americium, 2394–2396, 2396t berkelium, 2397–2398, 2398t californium, 2398–2399, 2398t curium, 2396–2397, 2396t einsteinium, 2399, 2399t history of, 2389 protactinium, 2391 thorium, 2390 uranium, 2391–2394, 2393f thermodynamic properties of, 2135–2157 with alkali metal ions, 2150–2153 with alkaline earth ions, 2153–2157 binary, 2135–2136, 2136t dioxides, 2136–2143 in gas phase, 2147–2150, 2148t, 2150f monoxides, 2147 sesquioxides, 2143–2147 ternary and quaternary oxides/oxysalts, 2157–2159t

I-86

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Oxides (Contd.) of thorium, 70, 75–76 as catalysts, 70, 76 properties of, 70, 75, 75t research of, 70 unit cell constants for, 2389, 2389t of uranium, 259t, 339–398, 3214–3215. See also Uranium oxides alkali and alkaline-earth metals, 371–383, 372t–378t binary, 339–371 bromides, 497, 527–528, 571–574 chlorides, 524–525 fluorides, 489–490, 564–567 geometric parameters of, 1973, 1974t halides, 456 hazards of, 3202 history of, 253–254 iodides, 499 safe storage, 3262 Oxide-water reaction, of plutonium, 3209–3210, 3209t Oxine, in thorium compounds, 115 Oxobromides, of uranium, 528 Oxochlorides, of uranium, 525–526 Oxoplutonates alkali metals, preparation of, 1056–1057 alkaline earth metals, preparation of, 1057–1059 solid state structures of, 1059–1064, 1060t–1061t double perovskites, 1062–1063, 1063f heptavalent, 1064 hexavalent, 1063–1064, 1064f perovskites, 1059–1062, 1062f Oxybromides, of berkelium, 1470 Oxychlorides of berkelium, 1470 of bohrium, 1711–1712, 1712f of californium, 1532 of neptunium, 738 of seaborgium, 1706–1707 of uranium, 494 Oxyfluorides, of neptunium, 734–736 preparation of, 734–736 properties of, 734, 736t Oxygen americium ligands of, 1361–1362 plutonium hydrides reaction with, 3216–3217 metal reaction with, 3225–3238 oxide generation of, 3250 in plutonium catalyzed corrosion, 3237 in uranium aqua ions, 592–593 carbonate leaching, 307–308 corrosion by, 3242–3245, 3243f, 3244t metal reactions with, 327–328, 327t

Oxygen diffusion in plutonium oxide, 1044–1045 of UO2, 367 Oxygen potential, of uranium oxides, 360–364, 361f–363f solid solutions, 394–398, 395t Oxyhalides of actinyl ions, 1939–1942, 1940t structures of, 1939–1941, 1940t, 1941f–1942f of californium, 1529–1534, 1530t–1531t, 1532f of dubnium, 1706 of neptunium, 738 of plutonium, 1100–1102 overview of, 1100 preparation and properties of, 1101–1102 solid-state structures, 1102, 1103f structural chemistry of, 2421–2424, 2422t, 2424t–2426t hexavalent, 2423, 2426t pentavalent, 2423, 2425t tetravalent, 2421, 2423, 2424t trivalent, 2421, 2422t thermodynamic properties of, 2182–2187, 2183t–2184t, 2186t–2187t Oxyhydroxides thermodynamic properties of, 2193–2195, 2194t of uranium, 259t–260t, 287 Oxyiodides of berkelium, 1470 of neptunium, 738 Oxyselenides, of neptunium, 741 Oxysulfates of berkelium, 1470 of californium, 1541 Oxysulfides of berkelium, 1470 of neptunium, 740 Oxytellurides, of neptunium, 741–742 PAA. See Phenylarsonic acid Pacemaker, plutonium–238 powered, 817, 1828–1829 Palladium, californium alloy with, 1518 PAM. See Periodic Anderson model Paramagnetic susceptibility measurements, for electronic structure, 1770 PARC process. See Partitioning Conundrum Key process Parsonsite natural occurrence of, 297 structure of, 295–296, 296f Particle-induced gamma emission spectroscopy (PIGE), for environmental actinides, 3059t, 3061

Subject Index

I-87

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Partition chromatography for actinide elements extraction, 1769 for actinium purification, 31–32 for SNF, 2728 Partitioning Conundrum Key process (PARC process), for americium extraction, 1272f, 1273 Passivated Ion-implanted Planar Silicon (PIPS) detectors, for seaborgium study, 1708 Paul Scherrer Institute (PSI) element 112 study at, 1721 rutherfordium production at, 1698 Pauli exclusion principle in actinide metals, 2320 description of, 2316–2317 Fermi-Dirac with, 2323 Pauli Hamiltonian, for electronic structure calculation, 1906 PCNAA. See Preconcentration neutron activation analysis PCS. See Photon correlation spectroscopy Peierls mechanism, for crystal structure, 2331 Pen˜a Blanca, Chichuhua District, Mexico, uranium deposits at, 272–273 Penning trap, for gas-phase ion chemistry, 1735 Pentadienyl ligands, 2865–2866 Pentahalides structural chemistry of, 2416, 2419, 2419f, 2420t thermodynamic properties of, 2160t, 2161–2165 gaseous, 2164–2165, 2164t solid, 2160t, 2161–2164 Pentahapto complexes, structural chemistry of, 2489, 2490t–2491t, 2492f Pentalene, 2862–2864 bond lengths in, 2864 derivation of, 2862 use of, 2863 Pentamethyl-cyclopentadienyl complexes, stoichiometric reactions of, 2913–2916, 2914f–2915f with alkynes and silanes, 2916–2918, 2917f PERALS, for soil sample measurement, 3066, 3067f Perchlorates of actinide elements, 1796 of plutonium, 1173 of thorium, 101, 102t–103t preparation of, 101 of uranium, 494, 570–571 Perchloric acid media, reduction in, americium (V), 1336 Percolation leaching, of uranium ore, 306 Periodic Anderson model (PAM), SIM v., 2344

Periodic potential, of metallic state, 2307–2308 Perovskites, solid state structures of, 1059–1062, 1060t–1061t, 1062f Peroxides of plutonium, 1175–1176 precipitation with, 836–838, 837–838 processing with, 1143 of protactinium, 208 gravimetric methods with, 229–230 of thorium, 76–77 formation of, 76–77 properties of, 77 of uranium, 259t, 288–289 Peroxydisulfate, oxidation by americium (III), 1333–1335, 1333f americium (IV), 1334 Perrhenates, of thorium, 113 PES. See Photoemission spectroscopy PFP. See Plutonium finishing plant Phase diagram of actinide elements, pressure v., 2368–2369, 2369f of actinide metals, 2312–2313, 2312f, 2384, 2384f of actinide sesquioxides, 1535, 1535f of berkelium oxide, 1466 of curium, plutonium alloys, 1412 of neptunium hydrides, 722, 723f oxides, 724, 725f of plutonium, 879, 882f–883f alloys, 925–929, 926f aluminum alloy, 894, 895f–896f borides, 997, 997f carbides, 1003–1004, 1003f determination of, 892 gallium alloy, 894, 894f–896f history of, 891–892 hydrides, 990, 991f–992f, 3204–3205, 3205f indium alloy, 896, 896f iron alloy, 897, 898f nitrides, 1017, 1017f oxides, 1025, 1026f, 1039–1041, 1040f, 1071–1073, 1073f, 3206–3208, 3207f, 3211–3212, 3212f silicides, 1009, 1011f thallium alloy, 896, 896f trichloride, 1099–1100 of uranium borides, 398, 400f carbides, 399, 403f hydrides, 331, 331f nitrides, 410, 411f oxides, 352–353, 352f, 354f, 1071–1073, 1073f selenides, 418, 419f

I-88

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Phase diagram (Contd.) sulfides, 413, 413f tellurides, 418, 419f uranium hexafluoride, 563, 563f Phase relations of plutonium hydrides and deuterides, 990–992, 991f–992f of uranium oxides, 351–357, 352f UO2.00-UO2.25, 353–354, 354f UO2.25-UO2.667, 354f, 355–356, 358t UO2.667-UO3, 356–357, 358t uranium-uranium dioxide region, 351–353, 352f Phase stability of californium, 1545 of plutonium, 877–890 allotropes of, 877–883, 980 atomic volumes, 886, 887t α and β stabilizers, 897 crystal structure data, 882, 886f δ field expansion, 892–897 density of, 886, 888t eutectic-forming elements, 897 interstitial compounds, 898 microcracking, 890 microsegregation in δ-phase alloys, 899, 916–917 oxides, 1025–1026 phase diagram, 925–929, 926f phase transformations in δ-phase alloys, 917–921, 918f–920f thermodynamic properties of, 890, 891f, 891t transformations, 886–890, 888f–889f vacancy clusters and, 984 valence electrons and, 927 Phase transformations of americium, 1297–1301, 1301f dioxide, 2292 of plutonium, 891–921 α- and β-phase stabilizers, 897 in δ-phase alloys, 917–921, 918f–920f eutectic-forming elements, 897 expand δ-phase alloys, 892–897 interstitial compounds, 898 microsegregation in δ-phase alloys, 899, 916–917 other elements, 898–899 for separation, 2648–2649 of uranium, 344, 347 1-Phenyl–3-methyl–4-benzoylpyrazolone (PMBP) neptunium extraction with, 705–706, 707f protactinium extraction with, 184 synergistic separation with, 2661–2662 3-Phenyl–4-bezoyl–5-isoxazolone, neptunium (IV) extraction with, 706

Phenylarsonates, of protactinium, gravimetric methods with, 229–230 Phenylarsonic acid (PAA), protactinium precipitation by, 179 Phonon energy, relaxation of, 2095–2100 actinides v. lanthanides, 2096 multi-, 2096–2097 Phonon spectrum, of plutonium, 964–967, 965f–966f Phosphates of actinide elements, 1783, 1796 of americium, 1305t–1312t, 1319–1321, 1355 complexes of, 2583 of curium, 1413t–1415t, 1422 of neptunium, 744–745 equilibrium constants for, 775t of plutonium, 1170–1172 precipitation with, 2633–2634 of protactinium (V), 217–218 sorption studies of, 3169–3171 uranium, 3169–3171 uranyl, 3171 structural chemistry of, 2430–2433, 2431t–2432t, 2433f of thorium, 109–110 arsenates v., 113 as ligands, 129 solubility and, 128 structure of, 109–110 study and use of, 109 synthesis of, 109–110 ternary, 110 vanadates v., 110 of uranium, 263t–265t autunite structures, 294–295 chain structures, 295–296 groups of, 294 natural occurrence of, 293 phosphuranylite structures, 295 synthetic, 296–297 uranium (IV), 275 uranium (VI), 297 uranophane structures, 295 in uranyl crown ether complex, 2455–2456 Phosphides of americium, 1318 complexes of, with cyclopentadienyl, 2832–2833 of neptunium, 743 of plutonium, 1021–1022 preparation of, 1021–1022 properties of, 1022 of protactinium, 204, 206t thermodynamic properties of, 2197t, 2203–2204 of thorium, 98t, 99–100 synthesis of, 99–100 of uranium, 411–412

Subject Index

I-89

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Phosphine imide complex, with cyclopentadienyl, 2825 Phosphinic acids, as trivalent actinide and lanthanide separating agent, 1408, 2657, 2665, 2684, 2753 Phosphinidene complexes, with cyclopentadienyl, 2833, 2834f–2835f, 2835 Phospholipids, in actinide fixation, 1817 Phospholyl ligands, 2869–2871 in bimetallic complexes, 2890–2892, 2892f cyclopentadienyl ligands v., 2869 dimeric trivalent compound, 2871, 2872f mixed-ring complexes, 2870–2871 mono-ring complexes, 2870 production of, 2869–2870 structure of, 2869, 2870f Phosphonic acids, as trivalent actinide and lanthanide separating agent, 2651, 2652, 2655, 2753 Phosphorescence, fluorescence v., 625 Phosphorimetry applications of, 3309 fundamentals of, 3309 of uranium, 636 Phosphorylide complex, with cyclopentadienyl, 2826, 2828f Phosphuranylite structures, of uranium phosphates and arsenates, 295 PHOTA. See Photoactivation PHOTN. See Photoneutron logging Photoactivation (PHOTA), for environmental actinides, 3034t, 3043 Photochemical oxidation of neptunium, 762 of polydeoxynucleotides, 630–631 Photochemistry experimental basis for, 627 history of, 626 overview of, 624–625 in Purex process, 712 of uranyl (VI), 624–630 Photoelectron spectroscopy of americium, 1296–1297 of californium, 1515–1516 of einsteinium oxide, 1605 of organometallic actinide compounds, 1800 of thorium hydrides, 64 of uranocene, 2854, 2855f Photoemission spectroscopy (PES) background of, 2334–2336 example of, 2339–2340, 2340f Photon correlation spectroscopy (PCS), for environmental actinides, 3034t, 3035–3036 Photoneutron logging (PHOTN), for environmental actinides, 3044t, 3046

Photothermal spectroscopy, of plutonium, ions, 1114 Phthalocyanine complexes, structural chemistry of, 2463–2467, 2464t, 2466f–2467f Physical concentration methods types of, 303 of uranium ore processing, 302 Pi-bonded ligands, of plutonium, 1188–1191 cyclooctatetraene complexes, 1188–1189 cyclopentadienyl complexes, 1189–1191 PIPS. See Passivated Ion-implanted Planar Silicon detectors Pitchblende. See also Uraninite actinide species in, 3014–3016 complexity of, 302–303 natural occurrence of, 1804–1805 plutonium in, 822 uranium in, 253 PIXE. See Proton-induced X-ray emission spectroscopy Plasma actinide clearance from, 3367–3387 dioxo ions, 3379–3387 rates of, 3367–3369, 3368f–3375f tetravalent and pentavalent, 3376–3379 trivalent, 3370–3376 actinide distribution in, 3357t–3358t, 3359–3361 albumin and globulins, 3362–3363 carbonate and bicarbonate, 3361 citric and other alpha-hydroxy dicarboxylic acids, 3360–3361 with erythrocytes, 3366–3367 transferrin, 3363–3364 transferrin binding, 3364–3366 description of, 3358 electrolytes concentrations in, 3356–3357, 3357t fluid volumes and protein and iron concentration in, 3357, 3358t neptunyl ion in, 3384–3386 plutonyl ion in, 3386–3387 uranyl ion in complexes, 3381–3382, 3382t complexes in bladder urine, 3383–3384 complexes in proximal renal tubular fluid, 3382–3383 Plasma protein, uranyl bonding to, 3380–3381 Plutonium allotropes of, 1, 877–890, 880f, 881t, 1787 α phase, 879–882, 882f–884f, 884t, 2309–2310, 2310f behavior of, 879, 880f, 881t β phase, 882, 882f–883f, 885t δ phase, 882–883, 882f–883f, 886f, 892–897, 899, 916–917, 2329–2330, 2329f

I-90

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Plutonium (Contd.) δ0 phase, 882f–883f, 883 discovery of, 877–879 e phase, 882f–883f, 883 γ phase, 882, 882f–883f transformation of, 879, 882f ζ phase, 882f–883f, 883, 890, 891f americium separation from, 1269–1270 in aqueous solution, 1110–1182 complex ions, 1156–1182 hydrolytic stability, 1146–1156 overview of, 1110–1111 oxidation and reduction reactions, 1117–1146 spectroscopic properties, 1113–1117 stoichiometry and structure of ions, 1111–1113 atomic properties of, 857–862 core-level spectra, 861 ionization potentials, 859 Mo¨ssbauer spectra, 861–862 optical emission spectra, 857–859, 858f, 860t x-ray spectra, 859–861 in biological systems acute toxicity of, 1820–1821 in bone, 1817 health hazard of, 1814 ingestion and inhalation of, 1818–1820 in liver, 1815–1816 long-term effects of, 1821–1822 in organs, 1815 removal of, 1822–1825 transferrin bonding of, 1814–1815 complexes of cyclopentadienyl, 2803 tris-cyclopentadienyl, 2470–2476, 2472t–2473t compounds of, 987–1108 antimonides, 1022–1023 arsenides, 1022 borides, 996–1003 bromides, 1092–1100 carbides, 1003–1009 carbonates, 1159–1166, 1160t–1161t carboxylates, 1176–1181, 1178t chalcogenides, 1023–1077 chlorides, 1092–1100 deuterides, 989–996 fluorides, 1077–1092 halides, 1077–1108, 1180t, 1181 history of, 987–988 hydrides, 989–996 iodates, 1172–1173 iodides, 1092–1100 nitrates, 1167–1168 nitrides, 1017–1021 oxalate, 1173–1175

oxides, 1023–1049 oxyhalides, 1100–1102 perchlorates, 1173 peroxide, 1175–1176 phosphates, 1170–1172 phosphides, 1021–1022 pnictides, 1016–1023 reaction kinetics of, 3215–3223 safety and handling of, 988 selenides, 1049–1056 silicides, 1009–1016 sulfates, 1168–1170 sulfides, 1049–1056 tellurides, 1049–1056 corrosion of catalyzed, 3236–3237 dry, 3227–3228 hydrogen- and hydride-catlyzed, 977–979 kinetic behavior, 3225–3227 metal and intermetallic compounds of, 973–979, 3223–3238, 3226f, 3227t, 3229t salt-catalyzed, 3238 thermal ignition, 3232–3235 unalloyed, 3231–3232 by water vapor, 3228–3230 crystal structure data for, 879, 881t curium v., 935 discovery of, 4, 5t, 8 extraction of neptunium v., 709 Purex process for, 710–712, 710f THOREX process, 2745 with TTA, 1701, 3282 half-life of, 815 handling of, 3201 hazards of, 3200 corrosion, 3204 HF calculations of, 1857–1858, 1857f HFIR target preparation of, 1401 history of, 4, 8, 814–815 ionization potentials of, 859, 1874t isotopes of, 4, 8–10, 12, 815–817, 816t decay of, 1143–1146 formation of, 821, 825–826, 825f from nuclear power reactors, 826, 827t–828t, 828 separation of, 821–822, 828–831 laser spectroscopy of, 1873 liquid, 960–963 melting point of, 960–962 properties of, 962–963 magnetic properties of, 2229–2230, 2230t, 2240–2263, 2355–2357 intermetallic compounds, 2361 man-made, 1805–1807 nuclear fuel processing and storage, 1806–1807, 1807t–1808t

Subject Index

I-91

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 nuclear weapons testing, 1805–1806 satellite disintegration, 1806 metal and intermetallic compounds of, 862–987 aging and self-irradiation damage, 979–987 alloys and phase transformations, 891–921 applications of, 862 corrosion kinetics of, 3223–3238 crystal structure data for, 899, 900t–915t electronic structure, theory, and modeling, 921–935 hazards of, 3256–3257 history of, 862 hydrogen reaction with, 3223–3225, 3224f mechanical properties, 968–973 metal preparation, 863–864 nature of, 863 oxidation and corrosion, 973–979, 3226f, 3227–3235, 3227t, 3229t oxygen, water, and air reaction with, 3225–3238 phase stability, 877–890 physical and thermodynamic properties of, 935–968 pyrochemical preparation and refining, 865–877 safe storage, 3260–3262, 3261f special case of, 2345–2347 structure of, 2386, 2387f natural occurrence of, 822–824, 1756, 1804, 3016 in marine organisms, 1809 states of, 3086 neutron irradiation of, 1757 nuclear properties of, 815–822 oxidation states of, 814, 2525–2527, 2525f in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t sorbed, 3175–3176 oxide-water reaction of, 3209–3210, 3209t production of, 814–815, 1757–1758, 2629 bismuth phosphate process, 2730 REDOX process, 2730–2731 TLA process, 2731–2732 pyrochemical methods for molten chlorides, 2698–2699, 2699f molten fluorides, 2701 processing for, 2702 quadrupole moments of, 1884, 1884f radial functions of, 895, 1897f radiolytic reactions of, 3246–3248 reaction with steel, 3238 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f, 2525, 2525f for RTGs, 43 in RTILs, 2689

rutherfordium extraction with, 1697–1699 separation and purification of, 826–857 in aqueous alkaline solutions, 852 aqueous-based, 830–831 DDP, 2705–2706 ion-exchange processes for, 845–852 from irradiated nuclear fuel, 828–830 non aqueous processes, 853–857 oxalates in, 1173–1174 precipitation and crystallization, 831–839 solvent extraction processes, 839–845 solution chemistry of, 1108–1203 aqueous, 1110–1182 electronic structure and bonding, 1191–1203 history of, 1108–1110 nonaqueous and organometallic, 1182–1191 storage of, 3201 studies on, 11 sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f superconductivity of, 1789 synthesis of, 4, 8–9 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f Plutonium (I) emission spectrum of, 857–859, 858f, 860t isotope shifts of, 1852, 1853f Plutonium (II) emission spectrum of, 857–859, 858f, 860t free-ion parameters of, 2038–2039, 2038t isotope shifts of, 1852, 1853f Plutonium (III) chlorides of, magnetic data, 2229–2230, 2230t compounds of carbonate of, 1159 carboxylates, 1177–1180, 1178t fluoride, 838 oxalate, 836–837, 1174 phosphates, 1171 silicates, 1065, 1068 sulfates of, 1168–1169 coordination numbers of, 1112 distribution coefficients of, 842, 842t free-ion parameters of, 2038–2039, 2038t hydrolytic behavior of, 1147–1149, 1148t, 2546, 2548t magnetic properties of, 2262–2263 oxidation state equilibrium of, 1123–1125, 1124f–1125f, 1126t–1130t

I-92

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Plutonium (III) (Contd.) preparation and stability of, 1125, 1131 oxoplutonates of, alkaline earth metals, 1058 precipitation with fluoride, 838 oxalate, 836–837 reduction potentials of, 2715, 2716f reduction to metal, 870–872, 873f speciation of, 3113t, 3117–3118 structure of, 593 Plutonium (IV) absorption spectrum of, 849 adsorption of, B. sphaericus, 3182–3183 anion-exchange chromatography for, 848–849, 848f in biological systems, 1819 compounds of carbonate of, 1162–1163 carboxylates, 1177–1180, 1178t hydroxide, 838 iodates, 1172–1173 nitrates of, 1167–1168 oxalate, 837, 1174–1175 peroxide, 837–838, 1175–1176 perrhenates, 1068 phosphates, 1171–1172 sulfates of, 1169–1170 vanadates, 1069 coordination numbers of, 1112 detection of, limits to, 3071t disproportionation of, 1119–1122 distribution coefficients of, 842, 842t, 848, 848f extraction of, DHDECMP, 2737–2738 free-ion parameters of, 2038–2039, 2038t hydrolytic behavior of, 1148t, 1149–1150 ligands for, 3417–3420, 3420f magnetic properties of, 2261–2262 magnetic susceptibilities, 2261–2262 in mammalian tissues bone, 3403 bone binding, 3407–3409 circulation clearance of, 3368–3369, 3368f–3375f, 3378 glycoproteins, 3410–3411, 3411t initial distribution, 3341t–3344t, 3346t, 3352–3353 liver, 3398–3400 transferrin binding to, 3364, 3365 natural occurrence of in hydrosphere, 1807–1810 sorption and mobility, 1810 oligomerized, 3210–3211 oxidation state equilibrium of, 1123–1125, 1124f–1125f, 1126t–1130t preparation and stability of, 1131–1132

oxoplutonates of alkali metals, 1056 alkaline earth metals, 1058 crystallographic data of, 1060t–1061t polymerization of, 1150–1154, 1151f, 1153f applications of, 1150 characterization of, 1152–1153 history of, 1151–1152 precipitation with hydroxide, 838 oxalate, 837 peroxide, 837–838 reduction of, 1139–1140 rutherfordium extraction with, 1697–1698 separation of HDEHP for, 2651, 2651f PUREX process, 2732 from SNF, 2646 solvating extractant system for, 2654–2655 speciation of, 3108–3109, 3113t, 3136 Plutonium (V) adsorption, B. sphaericus, 3182–3183 compounds of carbonate of, 1163–1165 carboxylates, 1178t, 1180–1181 nitrates of, 1168 oxalate, 1175 peroxide, 1175–1176 phosphates, 1172 coordination numbers of, 1112 disproportionation of, 1122–1123 hydrolytic behavior of, 1154–1155 in hydrosphere, 1807–1810 magnetic properties of, 2257–2261 oxidation state equilibrium of, 1123–1125, 1124f–1125f, 1126t–1130t preparation and stability of, 1132 oxoplutonates of alkali metals, 1056 alkaline earth metals, 1058 crystallographic data of, 1060t–1061t with pyrochemical processes, 2698–2699, 2699f reduction of, 1143 Plutonium (VI) adsorption, B. sphaericus, 3182–3183 compounds of carbonate of, 1165–1166 carboxylates, 1178t, 1180–1181 iodates, 1173 nitrates of, 1167–1168 peroxide, 1175–1176 phosphates, 1172 distribution coefficients of, 842, 842t hydrolytic behavior of, 1155–1156 magnetic properties of, 2247–2257

Subject Index

I-93

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 manganite and hausmannite reactions with, 3176–3177 oxidation state equilibrium of, 1123–1125, 1124f–1125f, 1126t–1130t preparation and stability of, 1132 oxoplutonates of alkali metals, 1057 alkaline earth metals, 1058–1059 crystallographic data of, 1060t–1061t oxygen exchange with solvent water, 1133 with pyrochemical processes, 2698–2699, 2699f reduction of, 1138–1139, 1142–1143 alpha-induced, 1145–1146, 1146t kinetics, 760–761 separation of, PUREX process, 2732 speciation of, 3113t, 3126 Plutonium (VII) coordination numbers of, 1112–1113 hydrolytic behavior of, 1156 magnetic properties of, 2240–2247 oxidation state, preparation and stability of, 1132–1133 oxoplutonates of alkali metals, 1057 alkaline earth metals, 1059 crystallographic data of, 1060t–1061t speciation of, 3113t, 3126 Plutonium carbide entropy of, 2196, 2197t formation enthalpy of, 2195–2196, 2197t high-temperature properties of, 2198, 2198f, 2199t Plutonium carbonates, structural chemistry of, 2426–2427, 2427t, 2428f Plutonium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Plutonium diboride, 999t, 1000, 1000f Plutonium dicarbide chemical properties of, 1008 structure of, 1005t, 1006–1007, 1007f Plutonium dioxide covalency in, 1196–1199, 1197f, 1200f crystal structure of, 2289–2290 crystal-field splittings of, 2288–2289 electronic structure of, 1044, 1196–1199, 1197f, 1200f, 1976 gas pressure generation with, 3248–3251 in gas-phase, 2148t, 2149 handling of, 3201 hazards of, 3249 IPNS of, 2289, 2290f JT effect of, 2290 magnetic properties of, 2288–2290 magnetic susceptibility of, 2290, 2291f oxidation of plutonium metal, 973, 3229 physical properties of, 1032, 1032t

plutonium metal production from, 866 preparation of, 1031–1034 pellets, 1032–1033 single crystals, 1033–1034 spheres, 1033 reactions of, 3219–3222 stability of, 3200 storage of, 3201 structure of, 1027t, 1037, 1038f, 1041–1044, 1042f–1043f, 2395 thermodynamic properties of, 1047t, 1048, 3250 enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 heat capacity of, 2138–2141, 2139f, 2142t XPS of, 861 Plutonium disilicide, structure of, 1015, 1016f Plutonium dodecaboride, 999t, 1002, 1002f Plutonium finishing plant (PFP), TRUEX process at, 2740, 2741f Plutonium fluorides, 1077–1092 chemical properties of, 1092 precipitation with, 838 preparation of, 1077–1082 overview of, 1077–1078 plutonium hexafluoride, 1080–1082, 1081f plutonium pentafluoride, 1079–1080 plutonium tetrafluoride, 1078–1079 plutonium trifluoride, 1078 properties of, 1083–1092 radiation decomposition of, 1090–1092 solid-state structures of, 1082–1083, 1084t, 1085f plutonium hexafluoride, 1083, 1084t plutonium tetrafluoride, 1083, 1084t, 1085f plutonium trifluoride, 1082, 1084t Plutonium halides, 1077–1108 chlorides, bromides, and iodides, 1092–1100 preparation of, 1092–1095 properties of, 1098–1100 solid-state structures of, 1096–1097 fluorides, 1077–1092 preparation of, 1077–1082 properties of, 1083–1092 solid-state structures of, 1082–1083 oxyhalides of, 1100–1102 preparation and properties of, 1101–1102 solid-state structures of, 1102 stability of, 1077 ternary halogenoplutonates, 1102–1108 phase diagram of, 1104, 1108f preparation of, 1103–1104 Plutonium hectoboride, 999t, 1002 Plutonium hexaboride, 999t, 1001–1002, 1002f

I-94

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Plutonium hexafluoride absorption spectra of, 2084–2085.2086f chemical properties of, 1092 covalency in, 1193–1196 electronic structure of, 1194–1196, 1195f energy level analysis of, 2083–2085, 2083t, 2085f preparation of, 1080–1082, 1081f properties of, 1086–1090, 1087t radiation decomposition of, 1090–1092 structure of, 1083, 1084t, 2419, 2421, 2421t studies of, 1938 thermodynamic properties of, 2160–2161, 2160t, 2162t–2164t Plutonium hydrides air reaction with, 3218 electrical properties of, 3205 entropy of, 2188, 2189t formation enthalpy of, 2187–2188, 2187t, 2189t, 2190f high-temperature properties of, 2188–2190, 2190t hydrogen reaction with, 3215–3216 nitrogen reaction with, 3217–3218 oxygen reaction with, 3216–3217 phase diagram of, 990, 991f–992f, 3204–3205, 3205f reaction rates of, 3215 structure of, 2403–2404 thermodynamic properties of, 3205, 3206t water reaction with, 3219, 3229 Plutonium hydroxides, 3213 precipitation with, 838 Plutonium monocarbide chemical properties of, 1007–1008 structure of, 1004–1006, 1005t Plutonium monophosphide, 1021–1022 Plutonium monosilicide, structure of, 1014, 1015f Plutonium monoxide dissociative energy of, 2149–2150, 2150f in gas-phase, 2148t, 2149 physical properties of, 1028 preparation of, 1028–1029 structure of, 2394–2395 Plutonium nitride, 3212–3213 enthalpy of formation of, 2197t, 2200–2201 entropy of, 2197t, 2201–2202 high-temperature properties of, 2199t, 2202 reactions of, 3222–3223 Plutonium oxalate, precipitation with, 837 Plutonium oxides, 1023–1049, 3206–3212 applications of, 1023–1025 container material compatibility with, 1049 dioxide, 1031–1034 formation enthalpies of, 1971 hazards of, 3257–3258, 3258t

interface of, 976–977, 978f monoxide, 1028–1029 phase diagram of, 1025, 1026f, 1039–1041, 1040f, 1071–1073, 1073f, 3206–3208, 3207f, 3211–3212, 3211f phase equilibria, 1025–1026, 1026f plutonium (VIII), 1932–1933 preparation of, 1028–1036, 3206–3207 higher oxides, 1034–1036 plutonium dioxide, 1031–1034 plutonium monoxide, 1028–1029 plutonium sesquioxide, 1029–1031 properties of chemical, 1048–1049 melting behavior, 1045 oxygen diffusion, 1044–1045 thermodynamic properties, 1047–1048, 1047t vaporization behavior, 1045–1047, 1046f reaction rates of, 3219–3222 safe storage, 3260–3262, 3261f sesquioxide, 1029–1031 sesquioxide phase with, 3208 solid-state structures of, 1027t, 1036–1044, 1038f–1040f, 1042f–1043f stability of, 3207 structure of, 2394–2395 ternary with actinides, 1070–1077 with lanthanide oxides, 1069–1070 thermal decomposition of, 3211 thorium oxides with, 1070–1071 uranium oxides with, 1070–1077 applications of, 1070–1071 phase diagram of, 1071–1073, 1073f preparation of, 1073–1074 properties of, 1074–1077 Plutonium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Plutonium pentafluoride, preparation of, 1079–1080 Plutonium peroxide, precipitation with, 837–838 Plutonium phosphates, structural chemistry of, 2430–2433, 2431t–2432t Plutonium pnictides, structure of, 2409–2414, 2410t–2411t Plutonium sesquioxide formation enthalpy of, 2143–2146, 2144t, 2145f high-temperature properties of, 2139f, 2146–2147 layer formation, 3208 oxide phase with, 3208 phase relationships of, 3207 physical properties of, 1030 preparation of, 1029–1031 reactions of, 3219

Subject Index

I-95

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 structure of, 1027t, 1037–1038, 1038f–1039f, 2395 thermodynamic properties of, 1047–1048, 1047t Plutonium silicides, structural chemistry of, 2406t, 2408 Plutonium sulfates, structural chemistry of, 2433–2436, 2434t Plutonium tetraboride, 999t, 1000–1001, 1001f Plutonium tetrachloride preparation of, 1093–1094, 1094f stabilization of, 1184 Plutonium tetrafluoride plutonium metal from, 866 from plutonium with americium–241, 1270 preparation of, 1078–1079 properties of, 1085–1086, 1087t structure of, 1083, 1084t, 1085f thermodynamic properties of, 2165–2169, 2166t Plutonium tetrahalides, structural chemistry of, 2416, 2418t Plutonium tribromide organic-solvent soluble, 1182–1183 preparation of, 1095 properties of, 1087t, 1098–1100, 1099t solid-state structure of, 1084t, 1096–1097, 1097f–1098f structural chemistry of, 2416, 2417t Plutonium trichloride magnetic properties of, 2262 organic-solvent soluble, 1182–1183 preparation of, 1092–1093 properties of, 1087t, 1098–1100, 1099t solid-state structure of, 1084t, 1096, 1096f, 1098f Plutonium trifluoride organic-solvent soluble, 1182–1183 preparation of, 1078 properties of, 1083–1085, 1087t structure of, 1082, 1084t thermodynamic properties of, 2169, 2170t–2171t Plutonium trihalides, structural chemistry of, 2416, 2417t Plutonium triiodide organic-solvent soluble, 1182–1183 preparation of, 1095 solid-state structure of, 1084t, 1096–1097 Plutonium tritelluride, structure of, 1053, 1053f Plutonium, Uranium, Reduction, Extraction process. See PUREX process Plutonium-231, discovery of, 815 Plutonium-236 detection of, αS, 3295 from neptunium-237, 703 nuclear properties of, 3277t ultrapure preparation of, 822

Plutonium-237, ultrapure preparation of, 822 Plutonium-238 applications of, 817–819 curium-242 and -244 v., 1400 detection of limits to, 3071t RIMS, 3321 αS, 3295 discovery of, 814–815, 817 as energy production by-product, 1805 half-life of, 815, 817 as heat source, 703, 1758 Mo¨ssbauer spectroscopy of, 861 from neptunium–237, 703 from neptunium–238, 861 nuclear properties of, 3277t for power generation, 1827–1828 uranium–234 from, 257 Plutonium–239 absorption cross section of, 2233 americium–241 from, 1268, 1758 critical parameters of, 820–821, 821t curium from, 1758–1759 detection of AMS, 3062–3063, 3319 FTA, 3307 γS, 3302 ICPMS, 3327–3328 limits to, 3071t RIMS, 3321 αS, 3295 TIMS, 3314 discovery of, 815 environmental hazards of, 1807 half-life of, 820 heat capacity of, 945 importance of, 820 ionization potential of, 1875 IP of, 859 maximum allowed dose of, 1821 Mo¨ssbauer spectroscopy of, 861–862 natural occurrence of, 822–824, 823t, 1756 neutron capture formation of, 823–824 nuclear energy with, 815 nuclear properties of, 3277t for nuclear weapons, 1805 production of from neptunium–239, 861 in nuclear reactor, 1826 from uranium–239, 255, 1757 radioactivity of, 1765 security risk of, 1758 study with, 1765 toxicity of, 1820 transmutation products of, 984–985, 985f Plutonium–240 detection of AMS, 3319

I-96

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Plutonium–240 (Contd.) γS, 3302 ICPMS, 3328 limits to, 3071t RIMS, 3321 αS, 3295 TIMS, 3314 as energy production by-product, 1805 environmental hazards of, 1807 Fourier transform spectrum of, 858, 858f Mo¨ssbauer spectroscopy of, 862 nuclear properties of, 3277t Plutonium-241 as beta emitter, 825 detection of RIMS, 3321 TIMS, 3315 as energy production by-product, 1805 maximum allowed dose of, 1821 neptunium–237 from, 705, 706f, 783–785 nuclear properties of, 3277t Plutonium-242 americium-243 from, 1268 curium from, 1400 detection of ICPMS, 3328 RIMS, 3321 αS, 3295 TIMS, 3315 as energy production by-product, 1805 Fourier transform spectrum of, 858, 858f heat capacity of, 947, 947f nuclear properties of, 3277t study with, 1765 Plutonium-243, as beta emitter, 825 Plutonium-244 detection of, AMS, 3062–3063 Fourier transform spectrum of, 858, 858f natural occurrence of, 822, 824 nuclear properties of, 3277t spontaneous fission of, 824 study with, 1765 Plutonocene electronic structure of, 1199–1203, 1201f–1202f HOMO of, 1946 properties of, 1946–1948 Plutonyl (V) formation of, 3210 speciation of, 3113t, 3123–3124 Plutonyl (IV), hydrolytic behavior of, 2551–2552, 2551f–2552f Plutonyl (VI), speciation of, 3113t, 3123–3124, 3134 Plutonyl ion aqueous solution absorption spectra of, 2080, 2081f complexes of, 1922–1923

cation-cation, 2594 structure of, 2400–2402 extraction of, REDOX process, 2730–2731 highest composition of, 3210 hydrolytic behavior of, 2553 in mammalian tissues circulation clearance of, 3378, 3386–3387 erythrocytes association with, 3366–3367 initial distribution, 3342t, 3356 reduction of, 2591 study of, 1931–1932 PMBP. See 1-Phenyl–3-methyl–4benzoylpyrazolone Pnictides of americium, 1305t–1312t, 1317–1319 coordination of, 1358–1359 of berkelium, 1464t–1465t, 1470 preparation of, 1460 of californium, 1530t–1531t, 1538–1539 of curium, 1413t–1415t, 1421 of neptunium, 742–744 applications of, 742 of plutonium, 1016–1023 antimony system, 1022–1023 arsenic system, 1022 families of, 1016–1017 nitrogen system, 1017–1021 phosphorus system, 1021–1022 valency and electronic structure, 1023 of protactinium, 204–207 structural chemistry of, 2409–2414, 2410t–2411t thermodynamic properties of, 2200–2204 gaseous nitrides, 2202–2203 phosphides, arsenides, and antimonides, 2203–2204 solid nitrides, 2200–2202 of thorium, 97–101, 98t, 99f antimony, 98t, 100 arsenides, 98t, 100 bismuth, 98t, 100 nitrides, 97–99, 98t, 99f phosphides, 98t, 99–100 of uranium, 407–412, 408t–409t nitride, 407–411, 408t–409t, 411f others, 411–412 preparation of, 411–412 Polarizabililty, of transactinide elements, 3, 1675–1676 Polarography for californium, 1548 for neptunium, determination of, 791–792 for protactinium, 220, 227 for uranium, 3066 Polonium, discovery of, 245 Polonium–212, seaborgium study interference by, 1708

Subject Index

I-97

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Polyaminopolycarboxylic acids, as chelating agents, 3413–3414 Polymerization of actinide elements, 1778–1782 of plutonium (IV), 1150–1154, 1151f, 1153f, 1781, 1810 of protactinium (IV), 1780 of thorium (IV), 1778–1781 of uranium (IV), 1780–1781 Polypnictide, complexes of, with cyclopentadienyl, 2836 Porphyrin complexes, structural chemistry of, 2463–2467, 2464t, 2466f–2467f Potassium chloride, in electrorefining, 2714–2715 permanganate, for uranium carbonate leaching, 307–308 with thorium molybdates, 112 with thorium sulfates, 105 Potentiometric method for neptunium, 781–782 determination of, 790–791 for protactinium, 227 Powder diffraction techniques, for oxides, 2389 Powder neutron scattering, overview of, 2383–2384 Powder X-ray diffraction of cyclopentadienyl complexes, tetravalent, 2814–2815 overview of, 2382–2383 Power production. See Nuclear energy PPs. See Pseudopotentials Praseodymium, UO2 solid solutions with, oxygen potentials of, 395t, 396 Precipitation of americium, 1270–1271 of berkelium, 1449 crystallization v., 832–833 of curium, 1410 historical development of, 2627–2628 of plutonium, 831–839 conversion chemistry, 836–839 coprecipitation, 833–835 decontamination factors for, 832, 833t reactions for, 831, 832t in RTILs, 2690 for separation, 2633–2634 Preconcentration neutron activation analysis (PCNAA) application of, 3307 description of, 3303 Pressure leaching, of uranium ore, 306 Pressure-composition diagram, of uranium-hydrogen system, 330–331, 330f Propionates, structural chemistry of, 2439t–2440t

Protactinium, 161–232 actinium separation from, 38 analytical chemistry of, 223–231 determination in environment, 231 electrochemical methods, 227 radioactivation methods, 226 radiometric methods, 223–226 spectral and X-ray methods, 226–227 applications of, 188–189 ceramic capacitors, 189 color cathode ray tube, 188–189 dating methods, 189 nuclear waste clean-up, 189 X-ray detection, 188 atomic properties of, 189–191 emission spectrum, 190 ground state configuration, 190 Mo¨ssbauer effect, 190–191 X-ray atomic energy levels, 190, 190t complexes of, tetrakis-cyclopentadienyl, 2814–2815 d transition elements v., 2 dubnium v., 1704–1705 half-life of, 162–163 ionization potentials of, 1874t isotopes of, 161–162, 164–170, 165t metallic state of, 191–194 alloys of, 194 physical parameters of, 191–194, 193t preparation of, 191 structure of, 2385 natural occurrence of, 170–171, 1755 nonstoichiometric compounds of, 1797 nuclear properties of, 164–170 oxidation states of, 2526 in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t preparation of, 172–189 of 234 and 234m isotopes, 186–187 aqueous raffinate enrichment for, 175–176 carbonate precipitate enrichment for, 174–175 ethereal sludge enrichment for, 176–178, 177f industrial-scale enrichment for, 174 procurement of, 172–173 of protactinium–233, 187–188 raw material analysis for, 172, 173t purification of, 178–186 ion exchange, 180–181, 180f large-scale recovery of protactinium–231, 186 precipitation and crystallization, 178–179 solvent extraction and extraction chromatography, 181–186, 183f pyrochemical methods for molten chlorides, 2695

I-98

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Protactinium (Contd.) molten fluorides, 2701 processing for, 2702 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f simple and complex compounds of, 194–209 borohydride, 206t, 208 carbides, 195 cyclooctatetraene, 206t, 208 halides, 197–204, 201t hydrides, 194 miscellaneous, 207–209 oxides, 195–197, 196t–197t pnictides, 204–207 tropolone, 206t, 208 solution chemistry of, 209–223 oxidation states of, 209 protactinium (IV) aqueous chemistry, 222–223, 223f protactinium (V) complexes in aqueous solution, 218–219, 219t protactinium (V) complexes in mineral acids, 212–218, 214t–215t, 216f, 217t, 218f protactinium (V) hydrolysis, 209–212, 210f, 211t, 212f redox behavior in aqueous solution, 220–221 structure of, 191–194, 193t superconductivity of, 1789 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f toxic properties of, 188 from uranium–235, 42–44 Protactinium (III) electron configurations of, 2018–2019, 2018f free-ion parameters of, 2038–2039, 2038t Protactinium (IV) aqueous chemistry of, 222–223, 223f emission spectra of, 2067–2068, 2068f free-ion parameters of, 2038–2039, 2038t hydrolytic behavior of, 2550 initial distribution in mammalian tissues, 3342t, 3347t, 3353–3354 magnetic properties of, 2240–2247 polymerization of, 1780 spectroscopic properties of, 2065–2066, 2066t Protactinium (V) absorption spectra of, 212, 212f

complexes in aqueous solution of, 218–219, 219t complexes in mineral acids of, 212–218 fluoro complexes, 213–215 ionic species in hydrochloric acid, 213, 215t ionic species in nitric acid, 212–213, 214t miscellaneous with inorganic ligands, 217–218 sulfuric acid, 215–216, 217t, 218f detection of limits to, 3071t NMR, 3033 dubnium v., 1704 equilibrium constants of, 211, 211t hydrolytic behavior of, 209–212, 210f, 211t, 212f magnetic properties of, 2239–2240 in mammalian tissues circulation clearance of, 3368–3369, 3368f–3375f, 3378–3379 transferrin binding to, 3365 thermodynamics of, 211, 211t Protactinium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Protactinium dioxide Dirac-Hartree-Fock calculations on, 1917–1918 enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 in gas-phase, 2148, 2148t heat capacity of, 2138–2141, 2139f, 2142t structure of, 2391 Protactinium hydrides entropy of, 2188, 2189t formation enthalpy of, 2187–2188, 2187t, 2189t, 2190f high-temperature properties of, 2188–2190, 2190t structure of, 2402–2403 Protactinium monoxide dissociative energy of, 2149–2150, 2150f structure of, 2391 Protactinium oxides structure of, 2391 thermodynamic properties of, 2136, 2136t Protactinium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Protactinium pentachloride structural chemistry of, 2416, 2419, 2419f, 2420t thermodynamic properties of, 2160t, 2161, 2164–2165, 2164t Protactinium pentafluoride structural chemistry of, 2416, 2419, 2419f, 2420t

Subject Index

I-99

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 thermodynamic properties of, 2160t, 2161, 2164–2165, 2164t Protactinium pentahalides, structural chemistry of, 2416, 2419, 2419f, 2420t Protactinium phosphates, structural chemistry of, 2430–2433, 2431t–2432t Protactinium pnictides, structure of, 2409–2414, 2410t–2411t Protactinium sulfates, structural chemistry of, 2433–2436, 2434t Protactinium tetrachloride, magnetic susceptibility of, 2241 Protactinium tetraformate, magnetic susceptibility of, 2241 Protactinium tetrahalides, structural chemistry of, 2416, 2418t Protactinium trihalides, structural chemistry of, 2416, 2417t Protactinium–231, 164–167, 165t, 166f actinium–227 from, 20 alpha-spectrum of, 166, 167f dating with TIMS, 171 with uranium–235, thorium–230, and, 170–171 detection of γS, 3301 limits to, 3071t MBAS, 3043 MBES, 3028 NMR, 3033 αS, 3294 TIMS, 3314 discovery of, 162–163 emission spectrum of, 190 gamma-ray spectrum of, 166, 168f half-life of, 166, 170 importance of, 164 isotope dilution mass spectrometry for, 231 large-scale recovery of, 186 natural occurrence of, 170 from neutron irradiation, 1756 nuclear properties of, 3274t–3275t, 3290t, 3298t overview of, 161 procurement of, 167 protactinium–232 from, 256 radioactivation methods for, 226 radiometric methods for alpha-counting, 224 gamma rays, 225 toxicity of, 188 Protactinium–232 from protactinium–231, 256 uranium–232 from, 256 Protactinium–233, 165t, 167–169 adsorption behavior of, 176 detection of, TIMS, 3314

half-life of, 169 importance of, 164, 167–169 natural occurrence of, 171 neptunium–237 equilibrium with, 785 nuclear properties of, 3274t–3275t, 3298t overview of, 161 preparation of, 187–188 procurement of, 167–169, 169t radiometric methods for, 225–226 Protactinium–234, 170, 170f discovery of, 162 gamma-ray spectrum of, 170, 171f half-life of, 186 importance of, 164 nuclear properties of, 3274t–3275t, 3298t protactinium–234 v. protactinium–234m, 170, 170f preparation of, 186–187 radiometric methods for, 225 Protactinocene electronic transitions in, 1949–1951 properties of, 1946–1948 structure of, 1944, 1944t, 1945f Protasite, anion topology of, 282, 284f–285f Protonation routes, for cyclopentadienyl complexes, 2819 Proton-induced X-ray emission spectroscopy (PIXE) for environmental actinides, 3059t, 3060–3061 RBS with, 3069 PSD. See Pulse shape discrimination Pseudomonas fluorescens, neptunium (V) adsorption, 3182 Pseudopotentials (PPs), for electronic structure calculation, 1671 PSI. See Paul Scherrer Institute Pulse shape discrimination (PSD), neptunium–237 determination with, 785 PUREX process actinide extraction with, 1274–1276, 1285, 1408, 1769 for actinide production, 2732–2733 alternative to, 1273 americium extraction with, 1273 BUTEX and REDOX processes v., 842 flow sheet for, 843, 843f historical development of, 841, 2629, 2732 improvements to, 844, 2733 for neptunium extraction, 710–712, 710f, 2756–2757 acids for, 711 advanced, 711 controlling of, 712 overview of, 710–711 other operations of, 844

I-100

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 PUREX process (Contd.) plutonium separation with, 829–830, 841–844, 856–857 steps of, 841–842 redox agents for, 760 separation with, 2646 steps of, 2732–2733 Pyrazole adduct, of cyclopentadienyl complexes, 2830 Pyrazolylborate complexes, 2880–2886 chemistry of, 2880 cyclopentadienyl ligands v., 2880 fluxional, 2885–2886 formation of, 2880–2881 metathesis reactions, 2884–2885, 2884f neptunium derivatives, 2885 steric factors, 2885 tetravalent, 2883, 2885, 2886f trivalent, 2882 uranium (III), 2881, 2882f Pyrochemical methods actinide chemistry in, 2694 for americium, 1269–1270 DDP applications, efficiency, 2707–2708 electrorefining, 2712–2717 electro-transport, 2714–2715 IFR, 2712–2714 separation efficiencies, 2715–2717, 2718t melt refining under molten salts, 2709–2710 metal-metal processes, 2708–2709 molten chlorides in, 2694–2700 americium, 2699–2700 curium and transcurium, 2700 neptunium, 2697–2698 plutonium, 2698–2699, 2699f protactinium, 2695 thorium, 2694–2695 uranium, 2695–2696, 2697f molten fluorides in, 2700–2701 plutonium, 2701 protactinium, 2701 thorium, 2701 uranium, 2701 molten metal-salt extraction, 2710–2712 Argonne salt transport process, 2710–2712, 2712f other applications, 2712 molten oxy-anion salts, 2702–2704 molybdates, 2702–2703 nitrates, 2704 sulfates, 2704 tungstates, 2703–2704 molten-salt processing in, 2701–2702 nitride-nitride process, 2723–2725 actinide nitride recovery, 2724–2725 dissolution step, 2724 historical development of, 2723–2724 overview of, 853–854, 2691–2694

oxide-metal processes, 2717–2721 for plutonium metal production, 864–877 direct oxide reduction, 866–869, 868f–869f electrorefining, 870–872, 873f flow diagram for, 865, 865f fluorination and reduction, 866, 867f molten salt extraction, 869–870 need for, 865 pyroredox or anode recovery, 872–876 vacuum melting and casting, 870, 871f–872f zone-refining, 876–877 for plutonium separation, 854 processing requirements of, 2701 recovery from LWR fuels, 2721–2723 calcium reduction, 2722 lithium reduction, 2722–2723 for separation, 2691–2725 separation techniques for, 2704–2707 DDP basis, 2705–2707 oxide-oxide process, 2704 Pyrochlore californium oxides, 1538, 1540f description of, 278–279 natural occurrence of, 279 structure of, 278, 279f uranium (V) in, 279 Pyrophoricity, of plutonium, 3251 in air, 975f, 976–977, 978f Pyroredox, for plutonium metal production, 872–876 equipment for, 868f, 875 process for, 875–876 product from, 876 Pyrrole-based ligands, 2871–2873, 2873f–2874f QED effect. See Quantum electrodynamic effect Quantum critical point, NFL and, 2348–2350 Quantum electrodynamic effect (QED effect), on inner orbitals, 1669 Quantum mechanical calculations, of crystal field parameters, 2049 ‘Quasiparticles,’ description of, 2339 Quaternary amines, for actinide extraction, 1769 Quaternary ammonium salts, for americium extraction, 1284 Quenching mechanisms, of uranyl (VI), 629 RA. See Rhizopus arrhizus RAD. See Autoradiography Radial functions, of plutonium atom, 895, 1897f

Subject Index

I-101

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Radial integrals, of actinide elements, 1863 comparisons of, 1865–1866, 1867f Radioactinium. See Thorium–227 Radioactive decay, of plutonium, consequences, 980 Radioactive displacement principle, description of, 162 Radioactive waste. See also Nuclear waste immobilization of, neptunium phosphate, 744 protactinium isolation from, 179 Radioactive-detected resonance ionization spectroscopy (RADRIS), of americium, 1880–1881, 1881f, 1884 Radioactivity of actinides, 1, 1764–1765 of curium–244, 1759 discovery of, 254 of plutonium–239, 1765 Radioanalytical chemistry of americium, 1364 of berkelium, 1483–1484 Radiochemical Engineering Development Center (REDC), for transcurium element production, 9 Radiochemical neutron activation analysis (RNAA) applications of, 3305–3307 description of, 3303 INAA v., 3305–3306 MC-ICPMS v., 3329 Radiocolloid formation, by actinium, 41–42 Radioisotope Engineering Development Center (REDC), production at, 1760 Radioisotope heater units (RHU), plutonium for, 703 plutonium–238, 817 Radioisotope thermoelectric generator (RTG) actinium for, 42–43 plutonium for, 43, 703 plutonium–238, 817 Radiolysis of adsorbed water, 3221–3222 of americium, 1337–1338 of einsteinium, 1579 of plutonium, 1143–1146 reactions of, 3246–3248 of water at SNF, 289 Radiometric methods for neptunium, 783–786 activation analysis, 785–786 alpha- and gamma-ray spectrometry, 783–785 liquid scintillation counting method, 785 of protactinium, 223–226 protactinium–231, 224–225 protactinium–233, 225–226 protactinium–234, 225

for uranium, 635–636 Radiopolarography of einsteinium, 1606–1607 of fermium, 1630 of mendelevium, 1636 of nobelium, 1640–1641 Radiothorium. See Thorium–228 Radiotoxicity, measuring of, 3339–3340 Radiotracer techniques, for environmental samples, 3022 Radium discovery of, 254 recovery of, 172–173 Radium–226 actinium–227 from, 1756 nuclear properties of, 3298t Radium–228, actinium–228 from, 25, 28 Radon, in actinium isolation, 32 RADRIS. See Radioactive-detected resonance ionization spectroscopy Raman spectroscopy (RAMS) of berkelium, berkelium (III), 1455 of californium, 1544, 1554 for environmental actinides, 3035 XRF and IRS with, 3069 RAMS. See Raman spectroscopy Rare earth metals actinide separation from, 2706 actinium separation from, 30 atomic volumes of, 922–923, 923f neptunium v., 700 reduction potentials of, 2715, 2716f reductive extraction of, 2719 separation of, actinide elements, 2719, 2720t, 2721f uranium oxides with, 389 Rate constants of actinide complexation, 2606, 2606t of An-O bond breakage, 2598–2600, 2599t comparison of, 2601–2602, 2602t of electron exchange reactions, 2597 of ligand exchange reactions, 608, 609t, 611t–612t redox reactions, 622–623 Rats initial distribution in, 3341t–3342t tissue deposition kinetics in, 3387–3388 RBS. See Rutherford backscattering Reaction rates, of plutonium hydrides, 3215 Reagent classes, for separation, 2645–2646 Recoil nucleus, from plutonium decay, 980–981 Recoil Transfer Chamber (RTC) in rutherfordium study, 1701 for superactinide element study, 1734 RECPs. See Relativistic effective core potentials

I-102

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 REDC. See Radiochemical Engineering Development Center; Radioisotope Engineering Development Center Redox behavior of actinide complexes, 2596–2602 An-O bond breakage, 2598–2600, 2599t complexation effect, 2601–2602, 2602t disproportionation reactions, 2600–2601, 2600t electron exchange reactions, 2597–2598 of actinide elements, 1778, 1780t in water, 3096 of actinium, 37–38 of americium autoreduction, 1330–1331 disproportionation, 1331–1332 electrode potentials and thermodynamic properties, 1328–1330, 1329t hydration and coordination numbers, 1327, 1328f kinetics of, 1333–1337 radiolysis, 1337–1338 of berkelium, 1448, 1479–1482 of californium, 1546–1549, 1547t disproportionation reactions v., 2601 of humic and fulvic acids, 2591 of neptunium, 753–755, 793–794, 794f in acidic media, 753 in basic media, 754–755 in biological systems, 1814 coulometry for, 757–759, 758f sodium hydroxide and, 756 voltammetric behavior of, 755–757, 756t, 757f of plutonium actinide ions and, 1133–1137, 1134t–1135t ammonia, 1141–1142 autoradiolysis, 1143–1146 hydrazine, 1142 hydroxylamine, 1140–1141 ions, 1117–1119, 1118f, 1118t, 1120t iron, 1138–1139 nitric acid, 1139–1140 nonactinide ions and, 1137–1143 oxidation state equilibrium, 1123–1125 peroxide, 1143 plutonium (IV) disproportionation, 1119–1122 plutonium (V) disproportionation, 1122–1123 plutonium (VI) oxygen exchange with solvent water, 1133 preparation and stability of oxidation states, 1125–1133 of protactinium, 220–221

of thorium, 60–61, 117–118 of transactinide elements, 1685–1686, 1685f–1686f of uranium aqua ions, 590–591, 592f, 594t dioxouranium (VI), 594t, 596 hexafluoride, 562 rates and mechanisms of, 622–624, 623f reduced phases, 274–280 REDOX process for actinide production, 2730–2731 bismuth phosphate process v., 2731 historical development of, 2629, 2730 PUREX process v., 842 Redox reagents, for neptunium, 759–761, 760t Redox speciation acid americium (III), 3114t, 3115 berkelium (IV/III), 3109–3110, 3114t californium (III), 3110, 3114t, 3115 curium (III), 3110, 3114t of environmental samples, 3100–3124 monatomic An (III) and An (IV) ions, 3100–3118 neptunium (III), 3111t–3112t, 3116–3117 neptunium (IV), 3106–3108, 3111t–3112t neptunyl (V), 3111t–3112t, 3121–3122 neptunyl (VI), 3111t–3112t, 3122–3123 plutonium (III), 3113t, 3117–3118 plutonium (IV), 3108–3109, 3113t plutonyl (VI/V), 3113t, 3123–3124 thorium (IV), 3103–3105, 3103t triatomic An (V) and An (VI) ions, 3118–3124 uranium (III), 3101t–3102t, 3116 uranium (IV), 3105–3106 uranyl (VI), 3101t–3102t, 3118–3121 base carbonate solution systems, 3129–3137 hydroxide solution systems, 3124–3129 of neptunium (IV), 3111t–3112t, 3135–3136 neptunium (VII/VI), 3111t–3112t, 3124–3125 neptunyl (V), 3111t–3112t, 3133–3134 plutonium (IV), 3113t, 3136 plutonium (VII/VI), 3126 plutonyl (VI), 3113t, 3134 of tetravalent ions, 3134–3135 thorium (IV), 3129, 3136–3137 uranium (IV), 3101t–3102t, 3136 uranyl (VI), 3101t–3102t, 3126–3133 Reduced phase, of uranium, 274–280 Reduction of americium, 1330–1331 americium (V), 1335–1337 americium (VI), 1335

Subject Index

I-103

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 of calcium, plutonium production, 2722 of californium, 1548 potentials, 1546–1547, 1547t of cyclopentadienyl complexes, trivalent, 2801–2802 of einsteinium einsteinium (III), 1602, 1607 for metal production, 1590 of lithium, for electrorefining, 2722–2723 of mendelevium, 1635–1636 of neptunium hexafluoride, 733 neptunium (IV), 762 neptunium (V), 762 neptunium (IV) to neptunium (III), 745 potential, 755 by nobelium, 1640 of plutonium by actinide ions, 1133–1137, 1134t–1135t in aqueous solution, 1117–1146 by nonactinide ions, 1137–1143 of uranium, 319 hexafluoride, 562 UO2 solid solutions, 392, 393t by uranium (III), 598 Reduction potentials of actinide elements, 1778, 1779f in water, 3097–3098, 3098t of actinide ions, 2127–2132, 2130f–2131f of neptunium, 1778, 1779f, 2127–2131, 2130f–2131f, 2525, 2525f of plutonium, 1778, 1779f, 2127–2131, 2130f–2131f, 2525, 2525f plutonium (III), 2715, 2716f of uranium, 1778, 1779f, 2127–2131, 2130f–2131f, 2525, 2525f uranium (III), 2715, 2716f Relativistic approaches, for electronic structure calculations, 1902–1914 double groups, 1910–1914 excited electronic states, 1909–1910 Hartree-Fock and density functional approaches, 1902–1904 RECPs, 1907–1909 relativistic effects, 1904–1907 Relativistic effective core potentials (RECPs) alternatives to, 1908 development of, 1908 for electronic structure calculation, 1671, 1907–1909 for element 118, 1729 of uranyl, 1918–1920 Relativistic effects on actinide cyclopentadienyl complexes, 1955 of actinides v. lanthanides, 1898, 1899f on actinocenes, 1949–1952

protactinocenes, 1949–1951 thorocene and uranocene, 1951–1952 of atomic electronic shells, 1666–1669, 1667f–1669f on chemical properties of transactinide elements, 1666–1671 description of, 1666–1669 on electronic structures, 1898–1900 5f electrons, 1898, 1899f calculation inclusion of, 1900 subshell splitting, 1899–1900 QED effect, 1669 quantum-chemical methods for, 1669–1671 spin-orbit splitting, 1668–1669 of superactinide elements, 1733 Relativistic elimination of small components (RESC), for electronic structure calculation, 1908–1909 Relativistic general gradient approximation (RGGA), for DFT, 1671 Relativistic Hartree-Fock (HFR) calculations, of f electrons, 2032, 2034f, 2035 Remote control, for actinide element study, 12, 12f–13f REMPI. See Resonance-enhanced multiphoton ionization RESC. See Relativistic elimination of small components Resistance furnace, for electrorefining, 782, 784f Resistivity tensor, of uranium, 324, 324t Resonance ionization mass spectrometry (RIMS) of actinide elements, 1875–1879, 1877t, 1878f–1879f excitation schemes, 1876–1877, 1877t, 1878f experimental v. predictions, 1878–1879, 1879f of fermium, 1877 ionization energies, 1878 precision of, 1879 applications of, 3321–3320 of berkelium, 1452 for environmental actinides, 3044t, 3047, 3048f experimental setup for, 1876 fundamentals of, 3319–3320, 3320f for mass spectrometry, 3310 of neptunium, 789–790 overview of, 3319 of plutonium, 859 problems of, 3329 of thorium, 60 TIMS v., 3329 for trace analysis, 3319–3322 Resonance ionization spectrometry (RIS), for environmental actinides, 3044t, 3047

I-104

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Resonance-enhanced multiphoton ionization (REMPI), of uranium dioxide, 1973 Resonant photoemission, of PES, 2336 Resonant X-ray scattering (RXS) description of, 2234 of neptunium dioxide, 2288 neutron scattering v., sample size, 2237–2238 of uranium dioxide, 2281 Respirable release fraction (RRF) of plutonium, 3252–3255, 3254t dioxide, 3254t, 3255 variations in, 3253–3254 RGGA. See Relativistic general gradient approximation Rhizopus arrhizus (RA), for extraction, 2669 RHU. See Radioisotope heater units RIMS. See Resonance ionization mass spectrometry RIS. See Resonance ionization spectrometry RKKY interaction. See Ruderman-KittelKasuya-Yosida interaction RNAA. See Radiochemical neutron activation analysis Roasting functions of, 304 of uranium ore, 304 Rock salt formations, for SNF storage, 1813 Roentgenium chemical methods for, 1720–1721 chemical properties of, 1717–1721 discovery of, 7t, 1653–1654 electronic structures of, 1682–1684 half-life of, 1719 isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, 1720 in aqueous solution, 1774–1776, 1775t production of, 1719–1720 relativistic orbital energies for, 1669f solution chemistry of complexation of, 1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f Room temperature ionic liquids (RTILs) actinides in, 2685–2691 properties of, 2687 description of, 854, 2686–2687 historical development of, 2685–2686 neptunium chemistry in, 2689 plutonium chemistry in, 2689 separation with, 854 separation techniques with, 2689–2691 dissolution, 2690 electrodeposition, 2690–2691

LLE, 2691 precipitation, 2690 uranium chemistry in, 2687–2688, 2689f RRF. See Respirable release fraction RTC. See Recoil Transfer Chamber RTG. See Radioisotope thermoelectric generator RTILs. See Room temperature ionic liquids Rubidium, with thorium sulfates, 105 Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction 5f v. 4f moments in, 2354 magnetic anisotropy with, 2364–2365 Rutherford backscattering (RBS) for environmental actinides, 3059t, 3063–3064, 3064f PIXE with, 3069 Rutherfordine, schoepite and, 289–290 Rutherfordium berkelium–249 in production of, 1447 chemical properties of, 1666, 1690–1702, 1691t historical, 1690–1693 discovery of, 6t, 1653, 1653t electronic structures of, 1676–1682, 1677f–1678f, 1680t–1681t, 1682f half-life of, 1661 hydrolytic behavior of, 1701 ionic radii of, 1674f, 1675–1676, 1676t ionization potential of, 1674, 1674f isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, in aqueous solution, 1774–1776, 1775t production of, 1662 relativistic orbital energies for, 1669f solution chemistry of, 1695–1702 anionic species extraction, 1695–1696 cationic species extraction, 1700–1702, 1702f complexation of, 1688–1689 fluoride complexes, 1699–1700 hydrolysis, 1686–1687, 1687t neutral complex extraction, 1696–1699 redox potentials, 1685–1686, 1685f–1686f volatility of, 1664 Rutherfordium tetrabromide, study of, 1693 Rutherfordium tetrachloride historical, 1690 study of, 1693, 1694f Rutherfordium tetrahalides, study of, 1693, 1694f Rutherfordium–257, chemical properties of, 1666 Rutherfordium–260, history of, 1690 Rutherfordium–261 chemical studies of, 1692

Subject Index

I-105

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 extraction of, 1695–1696 half-life of, 1661 in seaborgium study, 1710 Rutherfordium–262, seaborgium–266 α−α correlation with, 1708 RXS. See Resonant X-ray scattering Sale´eite at Koongarra deposit, 273 natural occurrence of, 293 uranium in, 259t–269t Salicylates, structural chemistry of, 2439t–2440t Salt roasting, functions of, 304 Samarium, californium v., 1521–1522, 1545, 1548 Satellites, disintegration of, 1806 Sayrite, anion topology of, 283, 284f–285f SBHLW. See Sulfate-bearing high-level waste solutions Scalar-relativistic methods AREP for, 1907–1908 ECPs for, 1906–1907 for ground state calculations, 1900 for thorium carbonyl, 1985 Scanning electron microscopy (SEM), for environmental actinides, 3049t, 3050, 3051f SCF equations. See Self-consistent field equations Schmitterite, as uranyl tellurite, 298 Schoepite at Pen˜a Blanca, Chichuhua District, Mexico, 272–273 rutherfordine and, 289–290 at Shinkolobwe deposit, 273 uranium in, 259t–269t, 287, 289–290 Schro¨dinger equation for actinide metals, 2327 for multiple electrons, 2021–2022 Scintillation detection for berkelium, 1484 gamma-spectrometry and, 3297 for uranium, 635 Seaborgium chemical properties of, 1691t, 1706–1711 discovery of, 6t, 1653, 1653t, 1762 electronic structures of, 1676–1682, 1677f–1678f, 1680t–1681t, 1682f gas-phase chemistry of, 1707–1709 history of, 1706–1707 ionic radii of, 1674f, 1675–1676, 1676t ionization potential of, 1674, 1674f isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659

oxidation states of, in aqueous solution, 1774–1776, 1775t relativistic orbital energies for, 1669f solution chemistry of, 1709–1711 complexation of, 1688–1689 redox potentials, 1685–1686, 1685f–1686f Seaborgium–263, study of, 1706–1707 Seaborgium–265 decay products of, 1708–1709 discovery of, 1735 study of, 1707–1708 Seaborgium–266 decay products of, 1708–1709 discovery of, 1735 rutherfordium–262 α−α correlation with, 1708 study of, 1707–1708 Seawater, neptunium in, 782–783 Secondary electron multiplier (SEM), for TIMS, 3313 Secondary electron X-ray absorption spectroscopy (SEXAS), for environmental actinides, 3044t, 3046 Secondary ion mass spectroscopy (SIMS) for environmental actinides, 3059t, 3062, 3063f for mass spectrometry, 3310 Se´elite, uranophane structure in, 295 Selenates, of actinide elements, 1796 Selenides of americium, 1316–1317 of neptunium, 740–741 of plutonium, 1049–1056 preparation of, 1052 properties of, 1055–1056 solid-state structure, 1053–1055, 1053f–1054f thermodynamic properties of, 2203t, 2204–2205 of thorium, 75t, 96–97 of uranium, 414t–417t, 418–420, 420f phases of, 418, 419f preparation of, 418–420 properties of, 414t–417t, 420 Selenites of actinide elements, 1796 of uranium, 268t with alkaline metals, 298–299 natural occurrence of, 298 Selenocyanates, of actinide elements, 1796 Self-consistent field (SCF) equations, in HF calculations, 1902 Self-irradiation of einsteinium, 1588 diffraction studies and, 1594–1595 in waste isolation, 1605 of plutonium at ambient temperature, 982–984, 983f

I-106

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Self-irradiation (Contd.) δ-phase, 986 lattice damage, 981–984 at low temperature, 981–982, 982f, 982t metal and intermetallic compounds, 979–987 SEM. See Scanning electron microscopy Separation chemistry, 2622–2769 applications of, 2725–2767 actinide production processes at design and pilot stages, 2737–2760 actinide production processes with industrial experience, 2729–2736 analytical separations and hydrometallurgical processing, 2725–2727 extractant comparison, 2763–2764 hydrometallurgy, 2727–2729 methods under development, 2760–2763 separations around the world, 2764–2767 future of, 2768–2769 actinide burnup strategies, 2768–2769 actinide in environment, 2769 alkaline wastes in underground storage tanks, 2768 historical development of, 2627–2631 challenges of, 2630–2631 fission discovery, 2628 identification, 2630 plutonium production, 2629 precipitation/coprecipitation, 2627–2628 REDOX and PUREX processes, 2629 synthesis of, 2630, 2631t uranium isotope enrichment, 2628–2629 systems for, 2631–2725 from alkaline solutions, 2667–2668 aqueous biphasic systems, 2666–2667 ion exchange methods, 2634–2643 with natural agents, 2668–2669 precipitation/coprecipitation, 2633–2634 pyrochemical process, 2691–2725 requirements, 2631–2632 in RTILs, 2685–2691 SFE for, 2677–2685 solvent extraction methods, 2644–2663 thermodynamic features of, 2663–2666 trivalent actinide/lanthanide, 2669–2677 volatility-based, 2632–2633 for trace analysis, 3281–3288 coprecipitation, 3281–3282 extraction chromatography, 3284–3285 ion exchange, 3282–3283 liquid-liquid extraction, 3282 speciation separations, 3285–3288 Separation factors, for americium and europium separation, 2669–2670, 2670t Sesquicarbides, thermodynamic properties of, 2195–2198

Sesquioxides of plutonium, reactions of, 3219 structural chemistry of, 2389–2390 thermodynamic properties of, 2143–2147 enthalpy of formation, 2143–2146, 2144t, 2145f entropy, 2146, 2146f high-temperature properties, 2139f, 2146–2147 SEXAS. See Secondary electron X-ray absorption spectroscopy SF. See Spontaneous fission SFE. See Supercritical fluid extraction Sheet structures factors in, 579 in uranyl minerals, 281–282 crystal morphology prediction of, 286–287 curite, 283, 284f–285f fourmarierite, 282–283, 284f–285f molybdates, 299 protasite, 282, 284f–285f sayrite, 283, 284f–285f uranophane, 284f–285f, 286 vandendriesscheite, 283, 284f–285f weeksite, 292–293 wo¨lsendorfite, 284f–285f, 286 SHEs. See SuperHeavy Elements Shinkolobwe deposit lepersonnite at, 293 uranium deposits at, 273 Siderophores as chelating agents, 3414–3423 americium (III) ligands, 3420–3421 catecholate ligands, 3414–3416, 3415f hydroxypyridinonate ligands, 3415f, 3416–3417, 3417f–3418f neptunyl ion ligands, 3422–3423 plutonium (IV) ligands, 3417–3420, 3420f uranyl ion ligands, 3421, 3422f complexes of, 2590–2591 extraction with, 2669 Sieverts apparatus, for plutonium hydride stoichiometry, 989 Sigma-bonded ligands, of plutonium, 1182–1187 alkoxides, 1185–1186 alkyls, 1186 amides, 1184–1185 borohydrides, 1187 halides, 1182–1184 Silane amine reactions with, 2978–2981 ratio in alkyne complexes, 2956 stoichiometric reactions of, with pentamethyl-cyclopentadienyl and alkynes, 2916–2918, 2917f

Subject Index

I-107

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Silica gel for oxidation state speciation, 2726 study of, 3153–3154 thorium sorption by, 3152t, 3153–3154 uranium sorption by, 3152t, 3154–3155 Silica, in protactinium purification, 174 Silicates actinide ion adsorption in, 3152–3153, 3152t, 3153f thorium, 3152–3154, 3152t uranium, 3152t, 3154–3155 of americium, 1321 matrices, einsteinium in, 1601–1602, 1602f–1603f overview of, 3151 phases of, 3153–3154 sorption studies of, 3151–3158 of thorium, 113 of uranium, 260t–261t minerals of, 292–293 natural occurrence of, 292 structure of, 292 uranium (IV), 276–277 uranium determination in, 632 Silicides of americium, coordination of, 1359 of plutonium, 1009–1016 crystal structure, 1011–1015, 1012t, 1013f–1016f phase diagram, 1009, 1011f preparation, 1011 properties of, 1015–1016 structural chemistry of, 2405–2408, 2406t of thorium, 69–70, 71t–73t phase diagram for, 69, 74f quaternary, 70 structures of, 69 ternary, 69–70 of uranium, 405–407, 406f phases of, 405–406, 460f properties of, 401t–402t, 406 ternary, 406 Silicon, thermodynamic properties of actinide compounds with, 2206–2208, 2206t–2207t Silyl complex, 2888 SIMS. See Secondary ion mass spectroscopy; Surface ionization mass spectrometry Single double coupled cluster excitations (CCSDs) for element 113, 1723 for element 118, 1728–1729 for element 119, 1729 in HF calculations, 1902 for relativistic correlation effects, 1670 of uranium dioxide, 1973

Single impurity model (SIM) description of, 2342–2343 f electrons in, 2343–2344 failure of, 2344 of UBe13, 2344 Single-shell tank (SST), TRUEX process for, 2740–2741 SISAK. See Special Isotopes Studied by the AKUFE Skeletal fraction ionic radii v., 3349 in mammalian tissues, 3346–3349, 3348f Skeleton, as deposition site, 3344, 3347–3349, 3348f Sklodowskite at Koongarra deposit, 273 uranium in, 259t–269t Slater-Condon method, for actinide elements, 1863 SLM. See Supported liquid membranes Slope analysis, for solvating extractant system, 2654 Smoke-detectors, americium–241 in, 1267 SNAP. See Space Nuclear Auxiliary Power SNF. See Spent nuclear fuel Soddyite sodium uranates in, 287 uranyl silicates in, 293 Sodium in anhydrous uranium chloride complexes, 451–452 with thorium sulfates, 105 Sodium carbonate actinide stripping with, 1280 for uranium carbonate leaching, 307 Sodium chloride, roasting with, 304 Sodium hydroxide neptunium redox behavior and, 756 reduction in, americium (V), 1335–1336 Soft-donor complexants, for actinide/ lanthanide separation, 2670–2671, 2673, 2761 Soil samples actinide handling in, 3022 neptunium in, 783 neptunium–237, 3327–3328 plutonium–239 in, 3327–3328 sorption studies of, 3171–3177 manganese, 3176–3177 micro-XANES, 3174 micro-XAS, 3172–3173 overview, 3171 southwestern US, 3174 XANES, 3172–3173 XAS, 3171–3172 XRF, 3172–3173 Yucca Mountain site, 3175–3176 Solid phase, in solvent extraction, 840

I-108

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Solubility of actinium, 38–40, 39t of neptunium neptunium (V), 769–770 neptunium (VI), 770 of thorium, 122–128, 124t, 125t, 127f, 133 carbonates and, 127–128 colloid generation in, 126 in complexing media, 126–128 crystallization in, 126, 127f hydrolysis of, 122–123, 124t in non-complexing media, 122–126, 124t–125t, 127f phosphates and, 128 products of, 123, 125t, 126 Solubility products, of trihydroxides, 2191–2192, 2194t Solution chemistry of actinide elements, 1765, 2524–2607 bonding, 2556–2563 cation hydration, 2528–2544 cation hydrolysis, 2545–2556 cation-cation complexes, 2593–2596 complexation reaction kinetics, 2602–2606 complexes, 2577–2591 correlations, 2566–2577 inner v. outer sphere, 2563–2566 redox reaction kinetics, 2597–2602 ternary complexes, 2591–2593 ARCA for, 1665 for one-atom-at-a-time chemistry, 1665–1666 SISAK for, 1665–1666 of transactinide elements, 1685–1689, 1765 complexation, 1687–1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f Solvating extractant system, 2653–2660 carbamoylphosphonate reagents in, 2653 DHDECMP for, 2655, 2656t DIAMEX process for, 2657–2658 diglycolamides for, 2659–2660 malonamide extractants for, 2657–2659 overview of, 2646, 2647f slope analysis for, 2654 TBP in, 2653 TRUEX process, 2655–2657 uranium (IV) and plutonium (IV) in, 2654–2655 Solvation numbers, of actinide cations, 2532–2533 Solvent exchange, for uranium leach recovery, 311–313 alkylphosphoric, 312–313 amine, 312 ion exchange v., 311

Solvent extraction acids for, 839 for actinium and lanthanum separation, 18 of americium, 1271–1289 amide extractants, 1285–1286 amine extractants, 1284 from lanthanides, 1286–1289 organophosporus extractants, 1271–1284 of californium, 1509 of curium, 1407–1409, 1434 of fermium, 1629 of lawrencium, 1646–1647 of mendelevium, 1633 methods for, 2644–2663 acidic extractants, 2650–2652, 2651f aqueous phase, 2649, 2649f, 2651f, 2666–2667 greatest selectivity of, 2647 ion pair formation systems, 2660, 2661f overview of, 2644 phase modifiers, 2648–2649 reagent classes for, 2645–2646 requirements of, 2644 solvating, 2646, 2647f, 2653–2660 supercritical fluid extraction, 2677–2685 synergistic extractants, 2646–2647, 2661–2663 thermodynamic features, 2663–2666 TIOA for, 2648, 2648t water in, 2644–2645 of neptunium, 705–713, 706f–708f, 709t from high-level liquid wastes, 712–713 plutonium v., 709 Purex process, 710–712, 710f of nobelium, 1638–1640 organic phases for, 840–841 overview of, 839 for oxidation state extraction, 3287 of plutonium, 839–845 extraction chromatography, 844–845 ion-exchange processes, 845–852 PUREX process, 841–844 protactinium purification with, 181–186, 183f, 187–188 with SISAK, 1665–1666 solid phase in, 840 thorium carboxylates in, 113–114 for trace analysis, 3287 for uranium metal preparation, 319 Sonochemical technique, for neptunium electrolysis, 762 Sorption studies, of actinide elements, 1810–1811, 3140–3183 bacterial interactions, 3177–3183 carbonate incorporation, 3159–3164 iron-bearing mineral phases, 3164–3169 natural soil samples, 3171–3177 overview of, 3140, 3151

Subject Index

I-109

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 phosphates, 3169–3171 silicates, 3151–3158 Sound velocities, of plutonium, 942–943, 944t liquid, 962 Space exploration curium in, 1398–1400 fuel preparation for, 1032–1034 plutonium–238 in, 817, 1025, 1032, 1758, 1827 Space Nuclear Auxiliary Power (SNAP), plutonium–238 in, 817–818, 1827 Spallation-based neutron scattering, overview of, 2383 Spark source mass spectroscopy (SSMS) for environmental actinides, 3049t, 3055 for mass spectrometry, 3310 Special Isotopes Studied by the AKUFE (SISAK) overview of, 1665–1666 rutherfordium study with, 1695 extraction, 1701–1702, 1702f for superactinides, 1735 Speciation bacterial influence on, 3178 electron-photon, -electron, -ion techniques for, 3047–3055 AES, 3049t, 3051 COUL, 3049t, 3052 DPV and DPP, 3049t, 3052, 3053f EDS, 3049t, 3050–3051 EELS, 3049t, 3051–3052 EMPA, 3049t, 3050 ESMS, 3049t, 3052–3055, 3054f overview of, 3047, 3049t, 3050 SEM, 3049t, 3050, 3051f SSMS, 3049t, 3055 in environment, 3013–3073 background, 3013–3021 combining and comparing analytical techniques, 3065–3071 sampling, handling, treatment, and separation, 3021–3024 specifics of, 3024–3065 ion-photon, -electron, -neutron, -ion techniques for, 3058–3065 AMS, 3059t, 3062–3063 ERDA, 3059t, 3065 ICPMS, 3059t, 3061–3062 NRA, 3059t, 3061 overview of, 3058–3060, 3059t PIGE, 3059t, 3061 PIXE, 3059t, 3060–3061 RBS, 3059t, 3063–3064, 3064f SIMS, 3059t, 3062, 3063f VOL, 3059t, 3061 neutron-photon, -electron, -neutron, -ion techniques for, 3055–3057

DNAA, 3056t, 3057 NAA, 3055–3057, 3056t, 3058f overview of, 3055–3057, 3056t passive techniques for, 3025–3033 βS, 3026t, 3028–3029 GRAV, 3026t, 3029 γS, 3025–3028, 3026t, 3028f ISEs, 3026t, 3029 LSC, 3026t, 3031, 3032f MBES, 3026t, 3028 NS, 3026t, 3029 overview of, 3025, 3026t RAD, 3026t, 3031, 3032f αS, 3026t, 3029–3031, 3030f XS, 3025, 3026t photon-phonon, -electron, -neutron, -ion techniques for, 3043–3047 LAICPMS, 3044t, 3046–3047 LAMMA, 3044t, 3046 LIBS, 3044t, 3045 LIPAS, 3043–3045, 3044t, 3045f overview of, 3043 PHOTN, 3044t, 3046 RIMS, 3044t, 3047, 3048f RIS, 3044t, 3047 SEXAS, 3044t, 3046 TIMS, 3044t, 3046–3047 UPS, 3044t, 3045 XPS, 3044t, 3045–3046 photon-photon techniques for, 3033–3043 AAS, 3034t, 3036 COL, 3034t, 3035 IRS, 3033–3035, 3034t LAICPOES, 3034t, 3036–3037 MBAS, 3034t, 3043 NIR-VIS, 3034t, 3035 NMR, 3033, 3034t overview of, 3033, 3034t PCS, 3034t, 3035–3036 PHOTA, 3034t, 3043 RAMS, 3034t, 3035, 3036f TOM, 3034t, 3040–3043, 3042f TRLF, 3034t, 3037, 3038f UVS, 3034t, 3037 XANES, 3034t, 3039, 3040f XAS, 3034t, 3037–3039, 3040f XRF, 3034t, 3039, 3041f for trace analysis, 3285–3288 Speciation diagram, of thorium, 122f Spectral emissivity, of liquid plutonium, 963 Spectrophotometry of berkelium, 1455, 1484 of neptunium, 782, 786–787 for protactinium, 227–228 light absorption in mineral acids solutions, 227–228 reactions with organic reagents, 228 for protactinium (IV), 222

I-110

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Spectrophotometry (Contd.) for thorium, 133 of uranium, 636 Spectroscopy actinide chemistry and, 1837 empirical analysis of, 1841, 1851–1852 experimental, 1838–1841 historical, 1839–1840 interest in, 1838 new properties, 1872–1873 numerical approach to, 1838–1839 radial parameters, 1862–1863 theoretical term structure, 1860–1862 of americium, 1364–1370 luminescence, 1368–1369 solution absorption, 1364–1368 vibrational, 1369–1370 x-ray absorption, 1370 of californium, 1827 effective-operator Hamiltonian for, 2026–2027 of einsteinium, 1827–1873 electronic structure determination with, 1858 experimental, 1838–1841 AVLIS, 1840 FTS, 1840 laser, of actinide elements, 1873–1875, 1874t, 1880–1884 of protactinium (IV), 2065–2066, 2066t of uranium hexafluoride, 1938 uranium (IV), 2066–2067, 2066t Spent nuclear fuel (SNF) alkaline processing scheme for, 852 americium in, 1268 DDP for, 2707–2708 disposal of, 1811–1813 immobilization, 1812–1813 transmutation, 1811–1812 electrodeposition for, 717 electrorefining for, 2712–2717 environmental aspects of, 1806–1807, 1807t extraction from, 1811 halide volatility processes for, 855 heavy isotope minimization in, 721 IFR reprocessing of, 2713–2714 impurities in, 274 ‘light glass’ v., 1273 neptunium recovery from, 732 neptunium–237 in, 702, 782–784 plutonium in, 813–814 iron and, 1138–1139 polymerization of, 1150 separation of, 828–830, 2646 plutonium oxides for, 1023–1024 problem of, 2728–2729 radiolysis of water at, 289

reprocessing of, 703–704, 856 studtite in, 289 uranium in, 270, 274 separation of, 2646 Spin functions for actinyl ions, 1932 transformation of, 1913 Spin-correlated crystal field potential, crystalfield splittings and, 2054 Spin-orbit coupling in actinide elements, 1899–1900, 1899f in actinide nitrides, 1988 corrections to, 2036 effect on f orbital, 1949–1951, 1950f electron repulsion v., 1928–1929 in electronic structure calculation, 1900, 1906 electrostatic interactions with, 2029 Hamiltonian for, 2028 with LS coupling, 2024–2026 of neptunium, 764–765 in uranium (V), 2246 Spin-orbit integrals, of actinide elements, divalent and 5þ valent, 2076 Spin-orbit splitting, as relativistic effect, 1668–1669 Spontaneous fission (SF) ARCA and measurement of, 1665 of bohrium, 1711 of californium, 1505 californium–252, 1766 of curium, 1432–1433 detection for transactinide identification, 1659 of dubnium, 1703, 1705 of element 112, 1719 of fermium–256, 1632–1633 of hassium, 1714 of plutonium–244, 824 of seaborgium, 1708 Spriggite, lead and uranium in, 288 SSMS. See Spark source mass spectroscopy SST. See Single-shell tank Stability constants of actinide cations, 2558–2559 correlations, 2567–2577 trivalent, 2562, 2563t of actinide complexes with inorganic ligands, 2578, 2579t with inorganic oxo ligands, 2581–2582, 2582t of actinide elements, 1780t, 2527 in mammalian tissues, 3346, 3347t of actinium, 40, 41t of americium, 1354 americium (III) fluoride, 1354–1355 of berkelium (III), 1475–1476, 1477t–1478t of curium (III), 1425, 1426t–1428t

Subject Index

I-111

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 of EDTA complexes, 2257f, 2556 of einsteinium, 1605, 1606t of glycolate and acetate uranium complexes, 590 of inner and outer sphere complexation, 2565, 2566f ionic radii and, 2574, 2575f of neptunium neptunium (V), 781–782 neptunyl (V), 2571, 2572f neptunyl ion, 2576, 2576f of sulfate complexes, 2581–2582, 2852t of uranium hydroxide complexes, 598, 600f inorganic complexes, 600–602, 601t organic ligand complexes, 603–605, 604t Steel, plutonium reaction with, 3238 Steric effects in actinide complex bonding, 2560 in organoactinide complexes, 2912 Stoichiometry of californium oxides, 1534 pnictides, 1538–1539 of organoactinide complexes, 2913–2916, 2914f–2915f of plutonium hydrides and deuterides, 990–992, 991f–992f ions, 1111–1113 oxalates, 1173–1174 structure and, 579 of uranium hydroxides, 598, 599t inorganic complexes, 600–602, 601t organic ligand complexes, 603–605, 604t ternary complexes, 605–606, 606t Stoner criteria, magnetic ordering with, 2354 Storage hazard assessment, 3248–3259 case studies, 3256–3259 chemical property uncertainty, 3255 metal incidents, 3256–3257 nuclear criticality, 3255–3256 nuclear material release and dispersal, 3252–3255 oxide incidents, 3257–3258 potential hazards, 3248–3256 residue incidents, 3258–3259 thermal hazards, 3251–3252 hazard mitigation, 3259–3262 atmosphere for, 3259–3260 conditions for, 3260–3262 of metals and oxides, 3260–3262 plutonium, 3260–3262, 3261f uranium, 3262 of plutonium, 3199–3266 alloys, 3213

hydrides, 3204–3206 metals, 3223–3238 other compounds, 3212–3213 oxides, 3206–3212 reaction kinetics, 3215–3223 scope of concerns, 3201–3202 radiolytic reactions, 3246–3248 of SNF, 1812–1811 of uranium, 3199–3266 compounds, 3213–3215 scope of concerns, 3201–3202 Strong correlations, of 5f orbitals, 2341–2350 heavy fermions, 2341–2344 non-Fermi liquid and quantum critical point, 2348–2350 plutonium systems, 2345–2347 Strontium, in aragonite, uranium v., 3162–3163 Structural chemistry of actinide chemistry, 2380–2495 complications of, 2380–2381 of coordination compounds, 2436–2467 with carboxylic acids, 2437–2448 overview of, 2436–2437 of metals and inorganic compounds, 2384–2436 actinide metals, 2384–2384 actinyl compounds, 2399–2402 arsenates, 2430–2433 borides, 2405–2408, 2406t borohydrides, 2404–2405, 2405f carbides, 2405–2408, 2406t carbonates, 2426–2427, 2427t, 2428f chalcogenides, 2409–2414, 2412t–2413t, 2414f halides, 2414–2421, 2417t–2418t, 2419f, 2420t–2421t hydrides, 2402–2404 nitrates, 2428–2430, 2429f oxides, 2388–2399 oxyhalides, 2421–2424, 2422t, 2424t–2426t phosphates, 2430–2433, 2431t–2432t, 2433f pnictides, 2409–2414, 2410t–2411t silicides, 2405–2408, 2406t sulfates, 2433–2436, 2434t, 2435f of organoactinide compounds, 2467–2491 cyclooctatetraene, 2485–2487, 2488t, 2489f cyclopentadienyl, 2468–2485 other, 2487–2491, 2490t–2491t, 2492f–2493f techniques for, 2381–2384 neutron diffraction, 2383–2384 x-ray diffraction, 2381–2383 technology for, 2380

I-112

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Structure of acetates, 2439t–2440t, 2440–2445 of actinide carbide oxides, 1977, 1977t of actinide complexes, cation-cation, 2595, 2596f of actinide cyclopentadienyl complexes, 1953, 1953f of actinide elements, 2369f, 2370–2371, 2371f of actinide metals, 2384–2388 actinium, 2385 americium, 2386–2387 berkelium, 2388 californium, 2388 curium, 2387–2388 einsteinium, 2388 neptunium, 2385–2386 overview, 2384–2385, 2384f plutonium, 2386, 2387f protactinium, 2385 thorium, 2385 uranium, 2385 of actinium, 34–35 of actinocenes, 1943–1944, 1944t, 1945f of actinyl compounds, 2399–2402 oxyhalides, 1939–1941, 1940t, 1941f–1942f of alkyl ligands, 2867, 2868f of americium, 1299–1300 chalcogenides, 1358–1359 halides, 1356–1357, 1358f oxides, 1357–1358, 1358f oxoanionic ligands, 1359–1360, 1360f pnictides, 1358–1359 silicides, 1359 of americyl complexes, 2400–2402 of arsenates, 2430–2433 of berkelium chalcogenides, 1470 halides, 1469 metallic state, 1458–1459 pnictides, 1470 sesquioxide, 1466–1467 of bijvoetite, 290 of borides, 2405–2408, 2406t of californium metal, 1519–1522, 1520t sesquioxide, 1536 zirconium-oxide, 1538 of calixarenes complexes, 2456–2463 of carbides, 2405–2408, 2406t of carbonates, 2426–2427, 2427t, 2428f of carboxylates, 2437–2448, 2438f, 2439t–2443t, 2443f–2447f of chalcogenides, 2409–2414, 2412t–2413t, 2414f of coffinite, 586, 587f

coordination geometry and, 579 of crown ether complexes, 2448–2456 of curite, 283, 284f–285f of curium chalcogenides, 1420–1421 dioxide, 1419 halides, 1418 metallic state, 1410–1411 sesquioxide, 1419 sesquiselenide, 1420 sesquisulfide, 1420 of cyclooctatetraene complexes, 2485–2487, 2488t, 2489f of cyclopentadienyl complexes, 2468–2485 bis, 2476–2482, 2478f, 2479t–2480t, 2481f–2483f hexavalent, 2847, 2849f mono, 2482–2485, 2484t, 2485f–2487f tetrakis, 2469, 2469t, 2470f tetravalent, 2815–2816, 2815–2817, 2816f, 2816t, 2818f tris, 2470–2476, 2472t–2473t, 2474f–2475f, 2477f trivalent, 2802 description of, uranium complexes, 579 of dihalides, 2415–2416 of einsteinium, sesquioxide, 1598–1599, 1599f, 2399, 2399t of ekanite, 113 of formates, 2437–2440, 2439t–2440t of fourmarierite, 282–283, 284f–285f of halides, 2414–2421, 2417t–2418t, 2419f, 2420t–2421t hexagonal bipyramidal coordination of uranyl (V), 588–589 of uranyl (VI), 580–581, 580f, 582f–583f of hexahalides, 2419, 2421, 2421t of hydrides, 2402–2404 americium, 2403 berkelium, 2404 curium, 2404 neptunium, 2403–2404 plutonium, 2403–2404 protactinium, 2402–2403 thorium, 2402 uranium, 2403 isostructural, uranium (IV) compounds, 586–588, 587f LAXS and EXAFS for, 589 of malonates, 2441t–2443t, 2447 of neptunium dioxide, 725–726 halides, 731t hexafluoride, 731t, 733 metallic state, 719 neptunium (VI) ternary oxides, 730 neptunium (VII) ternary oxides, 729–730

Subject Index

I-113

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 selenides, 741 sulfides, 740 of neptunyl complexes, 2400–2402 of nitrates, 2428–2430, 2429f of oxalates, 2441t–2443t, 2445–2446, 2445f of oxides, 2388–2399 actinium, 2390 americium, 2394–2396, 2396t berkelium, 2397–2398, 2398t californium, 2398–2399, 2398t curium, 2396–2397, 2396t einsteinium, 2399, 2399t history of, 2389 protactinium, 2391 thorium, 2390 uranium, 2391–2394, 2393f of oxyhalides, 2421–2424, 2422t, 2423, 2424t–2426t of parsonsite, 295–296, 296f pentagonal bipyramidal of uranyl (V), 589 of uranyl (VI), 580, 581f–582f of pentahalides, 2416, 2419, 2419f, 2420t peroxide complexes, of uranyl (VI), 583–584, 584f of phosphates, 2430–2433, 2431t–2432t, 2433f of plutonium antimonides, 1023, 1024f borides, 998–1002, 999t, 1000f–1002f carbides, 1004–1007, 1005t, 1006f–1007f chalcogenides, 1053–1055, 1053f–1054f fluorides, 1082–1083, 1084t, 1085f hydrides and deuterides, 992–994, 993f, 993t ions, 1111–1113 nitrides, 1019, 1020t oxides, 1027t, 1036–1044, 1038f–1040f, 1042f–1043f oxoplutonates, 1059–1064, 1060t–1061t oxyhalides, 1102, 1103f plutonium (III), 593 silicides, 1011–1015, 1012t, 1013f–1016f tribromide, 1084t, 1096–1097, 1097f–1098f trichloride, 1084t, 1096, 1096f, 1098f triiodide, 1084t, 1096–1097 of plutonyl complexes, 2400–2402 of pnictides, 2409–2414, 2410t–2411t of protactinium, 191–194, 193t hydrides, 194 of protasite, 282, 284f–285f of pyrochlore, 278, 279f of sayrite, 283, 284f–285f of sesquioxides, 2389–2390 of silicides, 2405–2408, 2406t six-coordination, of uranyl (VI), 582, 583f of studtite, 583, 584f

of sulfates, 2433–2436, 2434t, 2435f of tetrahalides, 2416, 2418t of tetravalent halides, 456, 482 of thorium, 61 chromates, 112 coordination compounds, 115 halides, 78–84, 79f, 81f, 83f, 90–91 hydrides, 64 molybdates, 111–112 nitrides, 98–99 phosphates, 109–110 phosphides, 99–100 selenides, 97 sulfates, 104–105, 104f sulfides, 96 tellurides, 96–97 thorium (IV), 118 vanadates, 110, 111f of thornasite, 113 of trihalides, 2416, 2417t of tris(amidoamine) complexes, 2887–2888, 2888f of uranium anhydrous chloride complexes, 451 aqueous complexes, 597 borides, 398, 399f carbides, 400, 404f carbonates, 290 dioxide dichloride, 569 dioxide monobromide, 527–528 dioxouranium (VI), 596, 596f hexachloride, 567, 568f hexafluoride, 560–561 hexavalent oxide fluoride complexes, 566–567 hydrides, 329–330, 329t metal, 320–321, 321f nitrides, 410–411 oxide difluoride, 566 oxides, 343–351, 345t–346t oxochloro complexes, 494, 570 pentachloride, 522–523 pentafluoride, 519, 519f perchlorates and related compounds, 571 silicates, 292 silicides, 401t–402t, 406 sulfides, 413, 414t–417t, 418f tellurides, 418, 420f tetrafluoride, 486 tetraiodide, 498, 498f transition metal oxides, 388–389 trichloride, 447, 447f trichloride hydrates, 448–449 trifluoride, 445 triiodide, 455 UNiAlHy, 338 uranium (III) compounds, 584–585, 585f uranium (IV) minerals, 282, 284f–285f

I-114

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Structure (Contd.) of uranophane, 284f–285f, 286 of uranyl (VI), 580–584, 580f–584f of uranyl complexes, 2400–2402 of vandendriesscheite, 283, 284f–285f of wo¨lsendorfite, 284f–285f, 286 of wyartite, 290 Studtite structure of, 583, 584f uranyl peroxides in, 288–289 Sublimation enthalpy of actinide elements, 2119t–2120t, 2122–2123, 2122f adsorption enthalpy and, 1663 Subshells, of actinide elements, 1 Sulfate-bearing high-level waste solutions (SBHLW), TRUEX process for, 2743–2745 Sulfates of actinide elements, 1796 of actinyl complexes, 1926–1927, 1928t of americium, 1305t–1312t, 1319–1321 of californium, 1549, 1550t–1553t complexes of, 2581–2582, 2852t of curium, 1413t–1415t, 1422 of neptunium, 745 equilibrium constants for, 774t of plutonium, 1168–1170 of protactinium (V), 215–216, 217t, 218f in pyrochemical methods, 2704 structural chemistry of, 2433–2436, 2434t, 2435f of thorium, 101–106, 102t–103t, 104f with alkali metals, 104–105 as ligand, 104–105 preparation of, 101–104 structure of, 104–105, 104f of uranium, 291–292 Sulfides of americium, 1316–1317 of neptunium, 739–740 neptunium disulfide, 739–740 neptunium pentasulfide, 740 neptunium trisulfide, 740 of plutonium, 1049–1056 preparation of, 1052 properties of, 1055–1056 solid-state structure, 1053–1055, 1053f–1054f thermodynamic properties of, 2203t, 2204, 2204f of thorium, 75t, 95–96, 1976 of uranium, 413, 413f, 414t–417t phases of, 413, 413f preparation of, 413 properties of, 413, 414t–417t structure of, 413, 414t–417t, 418f

Sulfites, of actinide elements, 1796 Sulfur, americium ligands of, 1363 Sulfuric acid solution for thorium separation, 56–58, 57f–59f uranates (V) and (IV) dissolution in, 381–382 uranium compound dissolution in, 632 for uranium leaching, 305 uranium oxide reactions with, 370–371 Superactinide elements, chemical properties of, 1722t, 1731–1734 Superconductivity of actinide elements, 1789–1790, 2239 of actinide metals, 2350–2353 breakthrough of, 2352–2353 conventional, 2350–2351 unconventional, 2351 of americium, 1299, 1789 of californium, 1527 description of, 2350 magnetic properties v., 2238–2239 of plutonium, 967–968, 1789 of protactinium, 161, 192, 193t, 1789 quantization of, 2317–2318 of thorium, 1789 hydride, 64 sulfides, 96 of UBe13, 2351 of UPt3, 2351 of uranium, 1789 of URu2Si2, 2352 Supercritical fluid extraction (SFE) actinide ion sources for, 2683–2684 of actinides, 2677–2685 applications of, 2684–2685 analytical, 2685 industrial, 2684–2685 experimental setup and procedures, 2678–2680, 2679f historical development of, 2677–2678 ion properties in, 2680–2682 β-diketones, 2680 modifiers for, 2682 organophosphorus compounds, 2680–2682 synergistic mixtures, 2682 overview of, 855–856 for plutonium separation, 856 pressure and temperature on, 2683 rational for, 2678 SuperHeavy Elements (SHEs) electronic structure and chemical property predictions, 1722–1734 experimental studies of, 1734–1739 chemical methods, 1734–1735 production reactions, 1737–1739 requirements for, 1734

Subject Index

I-115

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 half-lives and nuclear properties of, 1735–1737 natural occurrence of, 1661 overview of, 1653 Superposition model, of crystal field, 2051 Supported liquid membranes (SLM) CMPO in, 2749–2750, 2749f DMDBTDMA in, 2659 Surface ionization mass spectrometry (SIMS), of neptunium, 788–789 Surface tension, of liquid plutonium, 963 Sylvania process, for thorium, 61 Synchrotron description of, 2234, 2382 for environmental samples, 3086–3087, 3095–3140 acid redox speciation, 3100–3124 base redox speciation, 3124–3137 organic acids, 3137–3140 overview, 3095–3100 for magnetic studies, 2234 polarization of, 3088–3089 for sorption studies, 3140–3183 bacterial interactions, 3177–3183 carbonate incorporation, 3159–3164 iron-bearing mineral phases, 3164–3169 natural soil samples, 3171–3177 overview, 3140, 3151 phosphates, 3169–3171 silicates, 3151–3158 for XAS, 3087 for XRD, 2382 Synergistic extractants, 2661–2663 overview of, 2646–2647 in SFE, 2682 TAA. See Trifluoroacetylacetone TALSPEAK process for actinide/lanthanide separation, 2671–2673, 2672f, 2760 americium (III) extraction in, 1286, 1289 TAM. See Terephthalamide Tantalates of thorium, 113 of uranium (IV), 277–280 Tantalum californium and containers of, 1526 in curium metal production, 1411–1412 dubnium v., 1704–1706 protactinium purification from, 178–186 ion exchange, 180–181, 180f precipitation and crystallization, 178–186 solvent extraction and extraction chromatography, 181–186, 183f TBB. See t-Butylbenzene TBP. See Tri(n-butyl)phosphate TC. See Thermochromatographic column

TD-DFT. See Time-dependent density functional theory Technological problems, actinide chemistry for, 3 TEHP. See Tri–2-ethylhexyl phosphate Tellurates, of actinide elements, 1796 Tellurides of americium, 1316–1317 of curium, 1421 of neptunium, 741–742 of plutonium, 1049–1056 preparation of, 1052 properties of, 1055–1056 solid-state structure, 1053–1055, 1053f–1054f thermodynamic properties of, 2203t, 2204–2205 of thorium, 75t, 96–97 of uranium, 414t–417t, 418–420, 420f phases of, 418, 419f preparation of, 418–420 properties of, 414t–417t, 418, 420, 420f Tellurites of actinide elements, 1796 of uranium, 268t, 298–299 Tellurium alloys with neptunium, 742 uranium oxides with, preparative methods of, 383–389, 384t–387t TEM. See Transmission electron microscope Temperature-independent paramagnetism (TIP) of 5f1 oxides, 2244 of 5f6 compounds, 2263–2264 description of, 2226 of uranium (IV), 2248 of uranyl and uranium hexafluoride, 2239–2240 Terbium californium v., 1545 einsteinium v., 1613 nobelium v., 1640 Terephthalamide (TAM), for plutonium removal, 1824 Term structure, theoretical, 1860–1862 Terminal alkyne complexes cross dimerization of, 2947–2952, 2948f–2949f dimerization of, 2930–2935 ansa-organothorium complex, 2935–2937 external amines in, 2943–2944 hydroamination and, 2944–2945 kinetic studies of, 2936–2937, 2937f, 2940–2941, 2942f promotion of, 2938–2947, 2940f–2941f hydroamination of, 2981–2990 kinetic studies, 2986–2990 rates of, 2985

I-116

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Terminal alkyne complexes (Contd.) regioselectivities, 2984 scope and mechanistic studies, 2981–2986 thermodynamics of, 2982–2984 hydrosilylation of active species formation, 2957–2961 alkyne:silane ratio, 2956 bridged complex promotion, 2964–2969 cationic complex promotion, 2974–2978 kinetic studies, 2957, 2965–2966 mechanism, 2961–2963 neutral organoactinide promotion, 2953–2964 with primary silanes, 2966–2969 scope at room temperature, 2953–2954 scope of catalysis at high temperature, 2954–2955 thermodynamics, 2963–2966 oligomerization of, 2925–2926, 2928f, 2934f regioselective, 2945–2947 thermodynamic properties of, 2933–2935 tert-BHz. See Tert-butylhydrazine Tertiary amine for actinide extraction, 1769 for americium extraction, 1284 Tetraallylthorium, alkane activation by, 3002–3006, 3004t Tetrabenzylthorium, properties of, 116 Tetrafluorides complexes of, 2578 structural chemistry of, 2416, 2418t Tetrahalides structural chemistry of, 2416, 2418t thermodynamic properties of, 2165–2169 gaseous, 2169 solid, 2165–2168 Tetrahydrofuran (THF) for cyclopentadienyl complexes, trivalent, 2800–2802, 2805 with uranium trichloride, 452 Tetrakis-cyclopentadienyl complexes of actinides, 2814–2815 structural chemistry of, 2469, 2469t, 2470f N,N,N0 ,N0 -Tetrakis(2-pyridylmethyl) ethylenediamine (TPEN) americium (III) complexation with, 1354 americium (III) extraction with, 2675 N,N,N0 ,N0 -Tetraoctyl–3-oxapentane–1,5diamide (TODGA), actinide extraction with, 2658 TEVA columns for californium separation, 1508, 1511–1512 for einsteinium separation, 1585 for fermium separation, 1624 overview of, 3283 Thallium, in plutonium alloy, 896, 896f

2-Thenoyltrifluoroacetone (TTA) actinide complexes with, 1783–1784 for actinide extraction, 2532, 2650, 3287 in synergistic systems, 2661–2663, 2662f thermodynamic features of, 2663–2664 actinium extraction with, 28–29, 29f, 31–32 berkelium extraction with, 1448–1449, 1476 complexes of, californium, 1554 hafnium extraction with, 1701 lawrencium extraction with, 1643, 1645 for neptunium extraction, 705 for oxidation state speciation, 2726 plutonium extraction with, 1701, 3282 protactinium extraction with, 184 in spectrophotometric methods, 184 rutherfordium extraction with, 1695, 1700–1701 SFE separation with, 2680 thorium extraction with, 1701 in uranyl crown ether complex, 2455, 2455f zirconium extraction with, 1701 Thermal conductivity, of plutonium, 957 oxides with uranium oxides, 1076–1077 Thermal expansion, of plutonium, 937–942 coefficients, 937, 938t curve, 879, 880f, 939f oxides with uranium oxides, 1075–1076 Thermal hazards, of uranium and plutonium, 3251–3252 catalyzed corrosion, 3251–3252 ignition point, 3251 thermal excursions, 3252 Thermal ignition of plutonium, 3232–3235, 3233f of uranium, 3245–3246 Thermal ionization mass spectroscopy (TIMS) advantages of, 3329 AMS v., 3329 applications of, 3313–3315 for dating with protactinium–231, 171, 231 for environmental actinides, 3044t, 3046–3047 fundamentals of, 3311–3313, 3312f for mass spectrometry, 3310 MC-ICPMS v., 3326–3327 overview of, 3311 RIMS v., 3329 αS v., 3329 sensitivity of, 3315 for trace analysis, 3311–3315 for uranium analysis, 637–638 Thermal-neutron irradiation, thorium–232 after, 167, 169t Thermochromatographic column (TC), for thermochromatographic studies, 1664

Subject Index

I-117

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Thermochromatographic study of berkelium, 1451 of californium, 1523, 1524f of dubnium, 1664, 1703 of einsteinium, 1592, 1611–1612 of element 112, 1721 of fermium, 1625, 1628 for gas-phase chemistry, 1663 of hassium, 1714–1715, 1715f improved, 1664 of mendelevium, 1633–1634 of rutherfordium, 1664, 1692–1693 Thermodynamic properties of actinide complexes, cation-cation, 2595–2596, 2596t of actinide compounds, 2113–2213 with alkali metal ions, 2150–2153 with alkaline earth ions, 2153–2157 antimonides, 2197t, 2203–2204 arsenides, 2197t, 2203–2204 carbides, 2195–2198 chalcogenides, 2203t, 2204–2205 complex halides, 2179–2182, 2183t–2184t, 2185f di- and monohalides, 2178–2179, 2180t–2181t, 2181f dioxides, 2136–2143 in gas phase, 2147–2150, 2148t, 2150f group IIA elements, 2205, 2206t–2207t group IIIA elements, 2205–2206, 2206t–2207t, 2208f group IVA elements, 2206–2208, 2206t–2207t hexahalides, 2159–2161 hydrides, 2187–2190 monoxides, 2147 nitrides, 2200–2203 oxides, 2135–2136 oxyhalides, 2182–2187, 2183t–2184t, 2186t–2187t pentahalides, 2161–2165 phosphides, 2197t, 2203–2204 pnictides, 2200–2204 selenides, 2203t, 2204–2205 sesquioxides, 2143–2147 sulfides, 2203t, 2204, 2204f tellurides, 2203t, 2204–2205 ternary and quaternary oxides/oxysalts, 2157–2159t tetrahalides, 2165–2169 transition elements, 2208–2211 trihalides, 2169–2178 in water, 3096–3100, 3098t, 3099f of actinide elements in condensed phase, 2115–2118, 2119t–2120t, 2121f in gas phase, 2118–2123, 2119t–2120t

of actinide ions in aqueous solutions, 2123–2133, 2128t hydration, 2538–2544, 2540t–2541t, 2542f, 2543t, 2544f in molten salts, 2133–2135 of alkyne complexes hydrosilylation of, 2963–2966 oligomerization of, 2627f, 2926–2929, 2933–2935 of americium oxidation states, 1328–1330 oxides, 1303 of berkelium, 1482–1483, 1483t berkelium (III), 1476 of californium, 1555–1557, 1556t of cyclopentadienyl complexes, tetravalent, 2821, 2822t–2823t, 2840–2841, 2840t of einsteinium, 1603, 1605–1606 metallic state, 1592–1593 of electron exchange reactions, 2597 of element 114, 1727 of fermium, 1629 heavy fermions, 2342–2343, 2343f of hydration actinide ions, 2538–2544, 2540t–2541t, 2542f, 2543t, 2544f calculation of, 2539 lanthanide ions, 2542–2544, 2544t of inner and outer sphere complexation, 2566, 2567f of neptunium halides, 736t, 739 hydrides, 722–723 metallic state, 718–719 neptunium (IV), 769 oxides, hydrates, and hydroxides, 728, 728t of plutonium, 935–968 carbides, 1008–1009, 1008t densities and lattice parameters, 935–937 diffusion, 958–960 dioxide, 3250 elastic constants and sound velocities, 942–943 electrical resistivity, thermal conductivity, thermal diffusivity, and thermoelectric power, 954–958 halides, 1087t heat capacity, 943–949 hydrides, 3205, 3206t ions, 1111, 1111t magnetic behavior, 949–954 new tools and new measurements, 964–968 oxides, 1047–1048, 1047t phase transformations, 890, 891f, 891t pnictides, 1019, 1021t redox reactions, 1120t

I-118

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Thermodynamic properties (Contd.) surface tension, viscosity, and vapor pressure, 960–963 thermal expansion, 937–942 of protactinium (V), 211, 211t of solvent extraction reactions, 2663–2666 americium/europium separation, 2665–2666, 2667t in Cyanex 301, 2665 extraction equilibrium change, 2663 interaction strength, 2664–2665 TRPO for, 2666 TTA in, 2663–2664 of sulfate complexes, 2582, 2852t of terminal alkyne complexes, oligomerization of, 2627f, 2926–2929, 2933–2935 of thorium (IV), 118–119, 119t of uranium, 270, 597 dioxouranium (V), 595 fluoro complexes, 520 hexafluoride, 561 hydrides, 332–333, 332t metallic state, 321, 322t mixed halides, 499 oxide and nitride bromides, 497 oxides, 351–357, 352f, 360–364, 361f–363f tetrafluoride, 485–486 uranium oxide difluoride, 565 Thermodynamics of alkyne complexes, hydroamination of, 2982–2984 of bonding, 2556–2557, 2558t of terminal alkyne complexes, hydroamination of, 2982–2984 Thermoelectric generator actinium in, 19, 42–43 plutonium in, 43 Thermoelectric power of curium, 1398–1400 of plutonium, 957–958, 958t Thermonuclear device fermium from, 1623–1624 history of, 9 neutron production of, 9 THF. See Tetrahydrofuran Thiobacillus ferrooxidans, for uranium ore leaching, 306 Thiocyanate of actinide elements, 1796 for americium purification, 1291 of californium, 1550t–1553t, 1554 complexes of, 2580, 2581t for curium separation, 1409 of neptunium, equilibrium constants for, 773t of uranium, 602, 603t

Thiolate complexes, of cyclopentadienyl, 2836–2837 THOREX process, 115 for actinide production, 2733–2736 campaigns of, 2735 extractants for, 2736 historical development of, 2733–2734 plutonium recovery, 2745 solvent extraction cycles of, 2735 thorium, uranium, and plutonium separation in, 2736 uranium–238 in, 2735–2736 Thoria. See Thorium dioxide Thorian uraninite, thorium from, 55 Thorianite, thorium from, 55 Thorite natural occurrence of, 275–276 thorium from, 52, 55 Thorium actinium separation from, 38 adsorption of, silicates, 3152–3154, 3152t atomic spectroscopy of, 59–60 biosorption of, 2669 in californium metal production, 1517 californium separation with, 1513 complexes of ansa-organoactinide, 2935–2937 on bentonite, 3157–3158 cyclopentadienyl, 2803, 2804f mono-cyclopentadienyl, 2482–2485, 2484t, 2486f–2487f on montmorillonite, 3156–3157 pentamethyl-cyclopentadienyl, 2913, 2914f, 2916–2917, 2917f porphyrins and phthalocyanines, 2464t, 2465–2466, 2466f–2467f tetrakis-cyclopentadienyl, 2814–2815 tris-cyclopentadienyl, 2470–2481, 2472t–2473t, 2478f, 2479t–2480t, 2481f–2482f compounds of, 64–117 acetates, 114 acetylacetonates, 115 arsenates, 113 borates, 113 borides, 66–70, 71t–73t, 74f carbides, 66–70, 71t–73t, 74f carbonates, 108–109 carboxylates and related salts, 113–114 chalcogenides, 75t, 95–97 chromates, 112 complex anions, 101–114, 102t–103t coordination, 114–115 cyclopentadienyl anion in, 116 formates, 114 germanates, 113 halides, 78–94 hydrides, 64–66, 66t

Subject Index

I-119

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 hydroxides, 70, 75–77, 75t molybdates, 111–112 nitrates, 106–108, 107f organothorium, 116–117 other oxometallates, 113 oxalates, 114 oxides, 70, 75–77, 75t, 1070, 1971 perchlorates, 101, 102t–103t peroxides, 70, 75–77, 75t perrhenates, 113 phosphates, 109–110 pnictides, 97–101, 98t, 99f selenides, 75t, 96–97 silicates, 113 silicides, 66–70, 71t–73t, 74f sulfates, 101–106, 102t–103t, 104f sulfides, 75t, 95–96 tantalates, 113 tellurides, 75t, 96–97 titanates, 113 tungstates, 113 vanadates, 110, 111f d transition elements v., 2 electronic structure of, 1869, 1870t extraction with TTA, 1701 history of, 3, 52–53, 254 ionization potentials of, 59–60, 1874t isotopes of, 53–55, 54t–55t mass spectrometric methods for, 231 metallic state of, 60–63 alloys of, 63 chemical reactivity, 63 magnetic susceptibility of, 61–63 physical properties of, 61, 62t preparation of, 60–61 structure of, 2385 natural occurrence of, 55–56, 56t, 1755, 1804 nuclear properties of, 53–55, 54t–55t ore processing and separation of, 56–59 from monazite, 56–58 problems with, 58 from uraninite or uranothorianite, 58 oxidation states of, 2526 in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t pyrochemical methods for molten chlorides, 2694–2695 molten fluorides, 2701 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f rutherfordium extraction with, 1697–1699 solution chemistry of, 117–134 analytical chemistry of, 133–134 complexation, 129–133, 130t hydrolysis behavior, 119–120, 121t, 122f redox properties, 117–118 solubility, 122–128, 124t, 125t, 127f

thorium (IV) structure, 118 thorium (IV) thermodynamics, 118–119, 119t superconductivity of, 1789 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f UO2 solid solutions with oxygen potentials of, 394, 395t properties of, 390, 391t–392t uranium separation from, 2734–2735 Thorium (III) ground state of, 2240–2241 magnetic properties of, 2240–2247 Thorium (IV) calculations on, 1991–1992 carboxylates, EXAFS investigations of, 3137–3140, 3147t–3150t coordination numbers, analysis of, 586–588 detection of limits to, 3071t NMR, 3033 RBS, 3063–3064, 3064f VOL, 3061 hydration of, 2530–2531 hydrolytic behavior of, 2547–2551, 2549t magnetic properties of, 2239–2240 in mammalian tissues circulation clearance of, 3368–3369, 3368f–3375f, 3376 erythrocytes association with, 3366–3367 glycoproteins, 3410–3411, 3411t initial distribution, 3342t–3343t, 3350–3351 transferrin binding to, 3364–3365 polymerization of, 1778–1781 separation of, SFE for, 2682 speciation of, 3103–3105, 3103t, 3129, 3136–3137 structure of, 118 thermodynamics of, 118–119, 119t Thorium (II), electron configurations of, 2018–2019, 2018f Thorium borides, structural chemistry of, 2406t, 2407–2408 Thorium carbide entropy of, 2196, 2197t formation enthalpy of, 2195–2196, 2197t high-temperature properties of, 2198, 2198f, 2199t

I-120

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Thorium carbide oxide electronic structure of, 1982, 1983f energy curve for, 1981, 1982f formation of, 1980 interesting compounds of, 1982–1984, 1984t uranium v., 1980–1981 Thorium carbonates, structural chemistry of, 2426–2427, 2427t Thorium carbonyl, 1985–1987, 1987f energy levels of, 1986, 1987f ground state of, 1986, 1988f scalar-relativistic methods for, 1985–1986 Thorium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Thorium dicarbide, structural chemistry of, 2406t, 2408 Thorium dihydride, structure of, 2402 Thorium diiodide, structure of, 2415 Thorium dioxide bent structure of, 1976 as catalyst, 76 Dirac-Hartree-Fock calculations on, 1917–1918 double salt of, 77 enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 EPR of, 2265 in gas-phase, 2147–2148, 2148t heat capacity of, 2138–2141, 2139f, 2142t, 2272–2273, 2273f infrared spectroscopy of, 1971 production of, 75–76 properties of, 70, 75 structure of, 2390 Thorium extraction process. See THOREX process Thorium hydrides entropy of, 2188, 2189t formation enthalpy of, 2187–2188, 2187t, 2189t, 2190f high-temperature properties of, 2188–2190, 2190t structure of, 2402 Thorium hydroxide, 76 Thorium monoxide dissociative energy of, 2149–2150, 2150f in gas-phase, 2148, 2148t structure of, 2390 Thorium nitrates, structural chemistry of, 2428–2430, 2429f Thorium nitride enthalpy of formation of, 2197t, 2200–2201 entropy of, 2197t, 2201–2202 high-temperature properties of, 2199t, 2202 Thorium oxides, structure of, 2390 Thorium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t

Thorium peroxide, 76–77 Thorium phosphates, structural chemistry of, 2430–2433, 2431t–2432t Thorium pnictides, structure of, 2409–2414, 2410t–2411t Thorium series (4n), 23f actinium–228 in, 20, 23f thorium–228 in, 53–55, 54t–55t Thorium silicides, structural chemistry of, 2406t, 2408 Thorium sulfates, structural chemistry of, 2433–2436, 2434t Thorium tetrabromide polynary, 93–94, 94f–95f properties of, 78t, 81f, 82 synthesis of, 81–82 Thorium tetrachloride polynary, 93 properties of, 78t, 80–81, 81f synthesis of, 80 Thorium tetrafluoride phases of, 84–86, 85f, 86t polynary, 92–93, 92f properties of, 78t, 79–80, 79f synthesis of, 78–79 Thorium tetrahalides, structural chemistry of, 2416, 2418t Thorium tetraiodide polynary, 94 properties of, 78t, 83–84, 83f structure of, 83f, 84 synthesis of, 82–83 Thorium trihalides, structural chemistry of, 2416, 2417t Thorium–227 from actinium–227, 20 detection of RNAA, 3306–3307 αS, 3029 nuclear properties of, 3274t–3275t, 3298t synthesis of, 53 Thorium–228 detection of PERALS, 3066, 3067f αS, 3293–3294 nuclear properties of, 3274t–3275t, 3290t, 3298t purification of, gram quantities of, 32–33 synthesis of, 53, 54t Thorium–229 actinium–225 from, 28 detection of AMS, 3062–3063, 3318 NMR, 3033 nuclear properties of, 3274t–3275t, 3290t synthesis of, 53

Subject Index

I-121

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Thorium–230 dating with protactinium–231, and, 170–171 detection of AMS, 3062–3063, 3318–3319 ICPMS, 3327 limits to, 3071t NAA, 3055–3057, 3056t, 3058f PERALS, 3066, 3067f RIMS, 3322 αS, 3293–3294 TIMS, 3314 extraction of, 175–176 nuclear properties of, 3274t–3275t, 3290t, 3298t protactinium–231 from, 1756 synthesis of, 53 Thorium–231 protactinium–231 from, 164, 166f separation of, 163 synthesis of, 53 Thorium–232 actinium–228 from, 24 detection of γS, 3027–3028, 3028f, 3300–3302, 3301f ICPMS, 3327 INAA, 3304–3305 limits to, 3071t MBAS, 3043 MBES, 3028 NAA, 3055–3057, 3056t, 3058f PERALS, 3066, 3067f RIMS, 3322 RNAA, 3306–3307 αS, 3293–3294 TIMS, 3314 natural occurrence of, 3273, 3276 for nuclear energy, 53 nuclear properties of, 3274t–3275t, 3290t from ores, 53 protactinium–233 from, 187–188 after thermal-neutron irradiation, 167, 169t uranium–232 from, 256 uranium–233 separation from, 256 Thorium–233, nuclear properties of, 3274t–3275t Thorium–234 nuclear properties of, 3274t–3275t with protactinium–234, 186–187 synthesis of, 53 Thorium-uranium fuel cycle overview of, 2733–2734 uranium–233 for, 2734 Thornasite, structural data for, 113 Thorocene electronic transitions in, 1951–1952 HOMO of, 1946 preparation of, 116

properties of, 116, 1946–1948 structure of, 1943–1944, 1944t, 1945f, 2486, 2488t Thorocene, cerocene v., 1947 Time-dependent density functional theory (TD-DFT), for excited-state energies, 1910 Time-resolved laser fluorescence (TRLF) of curium (III), 2534 for environmental actinides, 3034t, 3037, 3038f water molecules in hydration sphere with, 2536–2537, 2537f TIMS. See Thermal ionization mass spectroscopy Tin protactinium separation from, 179 thermodynamic properties of actinide compounds with, 2206–2208, 2206t–2207t with thorium sulfates, 105 uranium compounds with, 407 TIOA. See Triisooctylamine TIP. See Temperature-independent paramagnetism Tissue deposition kinetics, 3387–3395 in mice, 3388–3395, 3389f–3392f, 3394t in rats, 3387–3388 Titanates of thorium, 113 of uranium, uranium (IV), 277–280 Titanite, thorium in, 56t Titanium, protactinium separation from, 179 TLA. See Trilaurylamine TLA process, for actinide production, 2731–2732 TnOA. See Tri-n-octylamine TOA. See Trioctylamine TODGA. See N,N,N0 ,N0 -Tetraoctyl–3oxapentane–1,5-diamide TOM. See X-ray tomography TOPO. See Tri-n-octylphosphine oxide Torbernite at Oklo, Gabon, 271–272 uranium in, 259t–269t Toxicity of actinide elements, 1765 of plutonium chemical v. radio, 1820 toxicity–239, 1820 of protactinium, 188 of transuranium elements, 12 Toxicology, of actinide elements, 1818–1825 ingestion and inhalation, 1818–1820 plutonium acute toxicity, 1820–1821 plutonium long-term effects, 1821–1822 removal of, 1822–1825

I-122

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 TPEN. See N,N,N0 ,N0 -Tetrakis (2-pyridylmethyl)ethylenediamine TPPO. See Triphenylphosphine oxide TPTZ. See Tripyridyltriazene Trace analysis, 3273–3330 atomic spectrometric techniques, 3307–3309 fluorometry, 3308 phosphorimetry, 3309 chemical procedures, 3278–3288 chemical separation, 3281–3288 sample decomposition, 3278–3281 mass spectrometric techniques, 3309–3328 accelerator, 3315–3319 inductively coupled plasma, 3322–3328 resonant ionization, 3319–3322 thermal ionization, 3311–3315 nuclear techniques, 3288–3307 alpha spectrometry, 3289–3296 FTA applications, 3307 gamma spectrometry, 3296–3302 neutron activation analysis, 3302–3307 Tracer methods for actinide element study, 11, 1765–1766 with actinium–228, 24–25 for berkelium study, 1444 for californium study, 1501, 1549, 1561–1562 for nobelium study, 1639–1640 for transfermium element study, 1622 for uranium, 256 TRAMEX process, for actinide/lanthanide separation, 2758–2759, 2759f Transactinide chemistry history of, 2 one-atom-at-a-time, 3 Transactinide elements, 1652–1739, 1753–1830 atomic properties of, 1672–1676 electronic structures of, 1672–1673, 1672t ionic radii and polarizability, 1674f, 1675–1676, 1676t oxidation state stabilities and IPs, 1673–1675, 1673t, 1674f–1675f Berkeley v. Dubna claims to, 1659–1660 biological behavior, 1813–1818 bioremediation, 1817–1818 in body fluids, 1814–1815 bone uptake, 1817 general considerations, 1813–1814 liver uptake, 1815–1816 chemical properties of bohrium, 1711–1712 dubnium, 1703–1706 hassium, 1712–1715 measured v. predicted, 1715–1717 measurements, 1690–1721, 1691t

meitnerium through element 112, 1717–1721 predictions, 1672–1689 rutherfordium, 1690–1702 seaborgium, 1706–1711 electronic structures of, 1770–1773, 1894–1897, 1896f–1897f, 1896t–1897t general considerations, 1770 periodic table position, 1773, 1774f spectroscopic studies, 1770–1771 structure, 1771–1773, 1772t, 1773f elements beyond 112, 1722–1739 electronic structure and chemical property predictions, 1722–1734 elements 113–115, 1723–1728 elements 116–118, 1728–1729 elements 119–121, 1729–1731 experimental studies of, 1734–1739 superactinide elements, 1731–1734 environmental aspects of, 1803–1813 in hydrosphere, 1807–1810 man-made, 1805–1807 of natural origin, 1804–1805 nuclear waste disposal, 1811–1813 overview of, 1803 sorption and mobility, 1810–1811 experimental techniques for, 1764–1769 column partition chromatography, 1769 hazards, 1764–1765 ion-exchange chromatography, 1767–1768, 1768f liquid-liquid extraction, 1768–1769 long-lived nuclides, 1765–1766 tracer techniques, 1766 ultramicrochemical manipulation, 1767 gas-phase compounds of, 1676–1685 electronic structures, 1676–1684, 1677f–1678f, 1680t–1681t, 1682f volatility predictions, 1684–1685 ground state configuration of, 1895, 1897t identification of, 1659 metallic state, 1784–1790 crystal structure, 1785–1787, 1786t electronic structures, 1788–1789, 1789f polymorphic transformation, 1787 preparation, 1784–1785 properties of, 1786t superconductivity, 1789–1790 nuclear properties of, 1655t–1656t, 1661 one-atom-at-a-time chemistry, 1661–1666 challenges, 1661–1662 chemical procedures, 1662–1666 production methods and facilities required, 1662, 1662t f orbital in, 1894–1895, 1896f, 1896t overview of, 2–3, 2f oxidation states of, 1762–1763, 1774–1784 complex-ion formation, 1782–1784

Subject Index

I-123

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 hydrolysis and polymerization, 1778–1782 ion types, 1777–1778, 1777t, 1779f, 1780t ions in aqueous solution, 1774–1776, 1775t periodic table with, 1654, 1654f practical applications, 1825–1829 medical and other, 1828–1829 neutron sources, 1827–1828 nuclear power, 1826–1827 relativistic effects on chemical properties, 1666–1671 atomic electronic shells, 1666–1669 quantum-chemical methods, 1669–1671 solid compounds, 1790–1803 binary, 1790, 1791t–1795t crystal structure and ionic radii, 1798, 1799t introductory remarks, 1790 organoactinide, 1800–1803 other, 1796 oxides and nonstoichiometric systems, 1796–1798 solution chemistry of, 1685–1689 complexation, 1687–1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f sources of, 1755–1763 atomic weights, 1763 heavy-ion bombardment, 1761–1763 natural, 1755–1756 neutron irradiation, 1756–1761 toxicology, 1818–1825 ingestion and inhalation, 1818–1820 plutonium acute toxicity, 1820–1821 plutonium long-term effects, 1821–1822 removal of, 1822–1825 Transactinide elements, practical applications, portable power sources, 1827 Transcalifornium elements, californium–252 for, 1505 Transcurium elements berkelium separation from, 1449 californium separation from, 1511 einsteinium separation from, 1584–1585 production of, 9 pyrochemical methods for, molten chlorides, 2700 Transfermium elements isolation and characterization of, 9–10 overview of, 1621–1622 oxidation states of, 1762–1763 synthesis of, 12–13 Transfermium Working Group (TWG), transactinide element claims and, 1660–1661 Transferrin actinide binding by, 3364–3366

actinide distribution with, 3363–3364 foreign metal ion binding to, 3364, 3365f function of, 3363–3364 plutonium bonding to, 1814–1815, 1817 structure of, 3363 uranium (IV) bonding to, 631 Transition metals atomic volumes of, 922–923, 923f characteristics of actinide compounds, 2333–2334 thermodynamic properties of, 2208–2211 enthalpies of formation, 2206t, 2208–2210, 2210f heat capacity and entropy, 2206t, 2210–2211 high-temperature properties, 2207t, 2208f, 2211 in uranium intermetallic compounds, 325 uranium oxides with, 383–389, 384t–387t crystal structures of, 388–389 preparative methods of, 383, 388 properties of, 384t–387t Wigner-Seitz radius of, 2310–2312, 2311f Transmission electron microscope (TEM) for actinide element detection, 11 for electronic structure, 1770 of Koongarra deposit, 273 for plutonium study, 964 of radiogenic helium, 986 Transmutation products, of plutonium–239, 984–985, 985f of SNF, 1811–1812 Transplutonium elements availability of, 1501 californium separation of, 1511 cohesion properties of, 2370–2371 fermium separation of, 1625 high-flux nuclear reactors for, production, 9 isolation and characterization of, 9 lanthanides v., 1578 metals of, 1590 Transuranium elements list of, 5t–7t periodic table and, 10 production of, 1759–1760, 1759f–1760f recovery of, 1407–1408 released into atmosphere, 1807, 1808t synthesis of, 4 toxicity of, 12 Transuranium extraction. See TRUEX process Tri–2-ethylhexyl phosphate (TEHP), for THOREX process, 2736 Trialkyl-phosphates, extraction with, 2666 Trialkyl-phosphinates, extraction with, 2666 Trialkyl-phosphine oxides (TRPO) actinide extraction with, 2752–2753 flow sheet for, 2753, 2754f

I-124

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Trialkyl-phosphine oxides (TRPO) (Contd.) in nitric acid, 2752–2753 overview of, 2752 studies of, 2753 suitability of, 2753, 2754t americium extraction with, 1274–1275 extractant comparison with, 2763–2764, 2763t extraction with, 2666 neptunium extraction with, 713 Trialkyl-phosphonates, extraction with, 2666 Tribromides, structural chemistry of, 2416, 2417t Trichlorides, structural chemistry of, 2416, 2417t Trifluorides complexes of, 2578 structural chemistry of, 2416, 2417t Trifluoroacetylacetone (TAA), SFE separation with, 2680 Trihalides structural chemistry of, 2416, 2417t thermodynamic properties of, 2169–2178 gaseous, 2177–2178 solid, 2169–2177 Trihydroxides, thermodynamic properties of, 2190–2192 enthalpy of formation, 2190–2191, 2191t entropy, 2191, 2191t solubility products, 2191–2192, 2194t Triiodides, structural chemistry of, 2416, 2417t Triisooctylamine (TIOA) dubnium extraction with, 1704–1705 rutherfordium extraction with, 1695 separation with, 2648, 2648t Trilaurylamine (TLA), in TLA process, 2731–2732 Tri-n-octylamine (TnOA) actinium extraction with, 30 neptunium extraction with, 709, 783, 784f in chelate chromatography, 715 nobelium extraction with, 1640 Tri-n-octylphosphine oxide (TOPO) californium extraction with, 1512 neptunium extraction with, 705–706, 707f, 795 protactinium extraction with, 175, 184 separation with, 2661, 2681 Trioctylamine (TOA), protactinium extraction with, 185 Trioctylphosphine oxide actinium extraction with, 29–30 curium separation with, 1433–1434 mendelevium extraction with, 1635 Triphenylarsine oxide, protactinium extraction with, 184

Triphenylphosphine oxide (TPPO), protactinium extraction with, 184 Tri(n-butyl)phosphate (TBP) for actinide extraction, 1769 actinium extraction with, 29, 31–32 americium extraction with, 1271–1274 berkelium extraction with, 1449 complexes with, californium, 1554 curium extraction with, curium–244, 1401 neptunium extraction with, 707, 710, 712–713, 795 for plutonium extraction, 841–844 in PUREX process, 2732–2733 rutherfordium extraction with, 1695–1699 separation with, 2646, 2647f, 2650, 2680–2682 in synergistic systems, 2661–2663, 2662f in solvating extraction system, 2653 for THOREX process, 2736, 2748–2749 thorium extraction with, 57 nitrate, 107 for uranium extraction, 314–315, 315f uranium (VI), 3282 Tripyridyltriazene (TPTZ), americum extraction with, 1286–1287, 2673–2675, 2674t Tris(carbonato) complex, uranyl (VI), 3131–3132 Tris(amidoamine) complexes, 2886–2888 electronic structure of, 2888 formation of, 2886–2887 overview of, 2886–2887 reduction of, 2887 structure of, 2887–2888, 2888f Tris-cyclopentadienyl complexes of actinides, 2800–2801, 2801t structural chemistry of, 2470–2476, 2472t–2473t, 2474f–2475f, 2477f of uranium and neodymium, 2259, 2259t Trivalent Actinide Lanthanide Separation by Phophorus reagent Extraction from Aqueous Komplexes. See TALSPEAK process TRLF. See Time-resolved laser fluorescence Tropolones, of actinide elements, 1783–1784 TRPO. See Trialkyl-phosphine oxides TRUEX process for actinide extraction, 1275, 1281–1283, 1282t, 1769, 2739 for americium extraction, 1286 development of, 2652, 2655 DΦDBuCMPO in, 1283, 2739 flow sheet at BARC, 2746f of chloride wastes, 2742f at JNC, 2744f in PFP, 2741f

Subject Index

I-125

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 HLW and simulants demonstrations, 2740–2745 for neptunium extraction, 713 numerical simulation code for, 2743 solvent in actinide stripping from, 2746–2747 degradation, cleanup, and reusability of, 2747–2748 for extraction chromatography, 2748–2749 magnetically assisted chemical separation, 2750–2752 in SLM separation, 2749–2750, 2749f UNEX process, 2739–2740 TRU•Spec CMPO in, 3284 for separation, 3284–3285 TTA. See 2-Thenoyltrifluoroacetone Tuliokite, 109 Tumor radiotherapy, actinium for, 43–44 Tungstates of americium, 1321 in pyrochemical methods, 2703–2704 of thorium, 113 of uranium, 267t–268t, 301 Tungsten in curium metal production, 1411–1412 seaborgium v., 1706–1707 TWG. See Transfermium Working Group UBe13 properties of, 2342–2343, 2343f SIM for, 2344 superconductivity of, 2351 UIr3 de Haas-van Alphen frequencies of, 2334, 2335f DOS of, 2338, 2338f Fermi surface measurements in, 2334 PES of, 2336–2339, 2337f UKAEA. See United Kingdom Atomic Energy Authority Ulrichtite, uranophane structure in, 295 Ultracentrifugation, for actinide speciation, 3069 Ultramicrochemical manipulation, of actinide elements, 1767 Ultramicrochemical methods, for actinide element study, 11 Ultrasonic nebulizers, for ICPMS, 3323 Ultraviolet photoelectron spectroscopy (UPS) for environmental actinides, 3044t, 3045 neptunium characterization with, 795 Ultraviolet spectroscopy (UVS) for environmental actinides, 3034t, 3037 overview of, 2014

Umohoite iriginite transformation of, 299, 300f uranium molybdates in, 299 UNiAlHy, 338–339 UNILAC. See Universal Linear Accelerator United Kingdom Atomic Energy Authority (UKAEA), protactinium from, 163–164, 173, 173t Universal Linear Accelerator (UNILAC), for seaborgium study, 1707–1709 Ununbium. See Element 112 UPS. See Ultraviolet photoelectron spectroscopy Uraninite composition of, 274 impurities in, 274–275 at Koongarra deposit, 273 at Oklo, Gabon, 271–272 oxidation states in, 274–275 at Pen˜a Blanca, Chichuhua District, Mexico, 272–273 thorium in, 58 uranium in, 259t, 274–275 Uranium, 253–639 actinium separation from, 30 adsorption of phosphates, 3169–3171 silicates, 3152t, 3154–3155 allotropes of α-phase, 320–326, 328–339, 344 β-phase, 321–323, 325–326, 328–339, 344, 347 γ-phase, 321–323, 347 analytical chemistry of, 631–639 chemical techniques for, 631–635 nuclear techniques for, 635–636 spectrometric techniques for, 636–639 in aragonite, strontium v., 3162–3163 bioassay of, αS, 3293 biochemistry of, 630–631 in biological systems in bone, 1817 health hazard of, 1814 in liver, 1815–1816 in organs, 1815 biosorption of, 2669 chemical bonding of, 575–578 U (III) and U (IV), 575–576 UF5 and UF6 compounds, 576–577 uranyl (V) and uranyl (VI) compounds, 577–578, 577f complexes of ansa-organoactinide, 2919–2920, 2920f cycloheptatrienyl, 2253–2254 cyclopentadienyl, 1953–1954 pentamethyl-cyclopentadienyl, 2913–2917, 2915f tetrakis-cyclopentadienyl, 2814–2815

I-126

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Uranium (Contd.) tris-cyclopentadienyl, 2470–2482, 2472t–2473t, 2474f–2475f, 2477f, 2478f, 2479t–2480t, 2483f, 2804–2806, 2805f, 2807f compounds of, 328–575 antimonides, 411–412 arsenates, 265t–266t, 293–297 arsenides, 411–412 azide, 602, 603t bismuthides, 411–412 borides, 398–399, 399f, 401t–402t bromides, 453–454, 494–497, 526–528 calcite, 3160 calcites, 289–291 carbides, 399–405, 401t–402t, 403f–404f carbonates, 261t–263t, 289–291 chalcogenides, 412–420, 414t–417t chlorides, 446–448, 490–493, 522–526, 567 corrosion kinetics of, 3239–3246 dioxide dichloride, 567–570 dolomite, 3160 fluorides, 444–446, 484–489, 518–521, 557–564 germanium, 407 halides, 420–575 Hill plot for, 2331–2333, 2332f history of, 328 hydrides, 328–339 hydroxides, 259t iodides, 454–455, 497–499, 574 lead, 407 molybdates, 266t, 275, 299–301 niobates, 277–280 nitride bromides, 497, 500 nitride chlorides, 500 nitride fluorides, 489–490 nitride iodides, 499–500 nonstoichiometric, 1797 orthosilicates, 261t, 275–276 oxide bromides, 497, 527–528, 571–574 oxide chlorides, 524–525 oxide fluorides, 489–490, 564–567 oxide halides, 456 oxide iodides, 499 oxides, 253–254, 259t, 339–398, 1070–1077 oxobromides, 528 oxochlorides, 525–526 oxychlorides, 494 oxyhydroxides, 259t–260t, 287 perchlorates, 494, 570–571 peroxides, 259t, 288–289 phosphates, 263t–265t, 275, 293–297 phosphides, 411–412 pnictides, 407–412, 408t–409t selenides, 414t–417t, 418–420, 420f

selenites, 268t, 298–299 silicates, 260t–261t, 276–277, 292–293 silicides, 405–407, 406f sulfates, 291–292 sulfides, 413, 413f, 414t–417t tantalates, 277–280 tellurides, 414t–417t, 418–420, 420f tellurites, 268t, 298–299 thiocyanate, 602, 603t tin, 407 titanates, 277–280 tungstates, 267t–268t, 301 vanadates, 266t–267t, 297–298 on zeolites, 301–302 d transition elements v., 2 decay of, 21f enrichment of, 557, 632 extraction of, 175, 270–271, 632–633 DDP, 2705–2706 Purex process for, 710–712, 710f free atom and ion properties, 318 Gibbs formation energy of hydrated ion, 2539, 2540t hazards of, 3200 heat capacity of, 2119t–2120t, 2121f history of, 3–4, 8, 253–255 discovery of, 253–254 fission of, 255 properties of, 254–255 uses of, 254 hydrogen reaction with, 3239–3242, 3240f, 3241t ionization potentials of, 1874t isotope enrichment of, 2628–2629 isotopes of, 4, 8–10, 255–257, 256t, 258t natural, 255–256, 256t, 258t nuclear properties of, 259t–269t synthetic, 256–257, 258t ligand substitution reactions, 606–624 intramolecular mechanisms of, 611t–612t, 617–618, 617f–619f isotopic exchange, 621–622 mechanisms of, 608–610 in non-aqueous system rates and mechanisms, 618–619, 620t organic and inorganic rates and mechanisms of, 611t–612t, 614–617 overview of, 606–607 oxygen exchange in uranyl (VI) and uranyl (V) complexes, 619–621 rates and mechanisms of, 607–608, 609t, 611t–612t redox rate and mechanisms, 622–624, 623f water exchange in uranyl (VI) and uranium (IV) complexes, 611t–612t, 614 water exchange rates and mechanisms, 610–614, 613f–614f

Subject Index

I-127

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 magnetic properties of, 2354–2357 intermetallic compounds, 2357–2360 metallic state of, 318–328 band structure, 2318, 2318f chemical properties of, 327–328, 327t corrosion kinetics of, 3239–3246 crystal structure of, 320–321, 321f electrical properties, 324, 324f, 324t general properties of, 321–323, 322t hydrogen solubility in, 330f, 331–332 intermetallic compounds and alloys, 325–326, 325t magnetic susceptibility, 323–324 physical properties of, 320–321, 321f preparation of, 318–324, 320f safe storage, 3262 structure of, 2385 from uranium tetrachloride, 491 metal-metal bonding, 1993–1994, 1995f MO levels of, molecules, 1969–1970, 1970f natural occurrence of, 170, 255, 257–302, 1755, 1804 mineralogy, 257, 259t–269t, 270–273 oxidation states of, 257 phases of, 280–302 reduced phases, 274–280 sorption of, 257 neptunium–237 production from, 701 nuclear properties of, 255–257 of uranium isotopes, 259t–269t occurrence in nature of, 162 ore processing and separation, 302–317 complexities of, 302–303 high-purity product refinement, 314–317, 315f–316f, 317t methods of, 302 pre-concentration, 303–304 recovery from leach solutions, 309–317 roasting or calcination, 304 organometallic chemistry of, 630–631 oxidation of, self-sustained, 3245–3246 oxidation states of, 257, 276–277, 328, 1914–1915, 2526 in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t plutonium and δ-phase plutonium influence of, 985 oxidation and reduction, 1136–1137 from plutonium decay, 985, 985f production of REDOX process, 2730–2731 TLA process, 2731–2732 protactinium separation from, 180, 180f, 183 pyrochemical methods for molten chlorides, 2695–2696, 2697f molten fluorides, 2701 processing for, 2702

quadrupole moments of, 1884, 1884f redox speciation for, 3100–3103, 3101t–3102t reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f, 2525, 2525f in RTILs, 2687–2688, 2689f solution chemistry of, 590–630 aqueous uranium complexes, 597–606 ligand substitution reaction mechanisms, 606–624 uranium aqua ions, 590–597 uranyl (VI) fluorescence properties and photochemistry, 624–630 structure and coordination chemistry of, 579–590 compounds of organic ligands, 589–590, 591f overview of, 579 uranium (III) compounds, 584–585, 585f uranium (IV) compounds, 585–588, 586f–588f uranyl (V) compounds, 588–589 uranyl (VI) compounds, 580–584, 580f–584f sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f superconductivity of, 1789 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t thorium separation from, 2734–2735 uranium hydride reactions with, 3246 Uranium (III) absorption spectra of, 2091, 2092f aqua ion of, 593, 594t biochemistry of, 630 bromides of bromo complexes, 454 uranium tribromide, 453 uranium tribromide hexahydrate, 453–454 chlorides of anhydrous chloro complexes, 450–452 magnetic data, 2229–2230, 2230t uranium trichloride, 446–448 uranium trichloride complexes with neutral donor ligands, 452 uranium trichloride hydrates and hydrated chloro complexes, 448–450 compounds of, 575–576 structures and coordination geometry of, 584–585, 585f crystal-field splittings of, 2057–2058, 2057f energy level structure, 2058, 2058f fluorides of, 421–456 uranium trifluoride, 444–445

I-128

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Uranium (III) (Contd.) uranium trifluoride monohydrate and fluoro complexes, 445–446 halides of, 421–456 absorption spectra of, 442, 443f complexes with, 601 electronic structure of, 422 history of, 421–422 magnetic properties of, 443–444, 2257–2259, 2258t oscillator strengths, 442–443 properties of, 422, 423t–441t stability of, 422 synthesis of, 422 iodides of complexes with neutral donor ligands, 455 uranium triiodide, 454–455 laser spectroscopic studies on, 2064 magnetic properties of, 2257–2261 magnetic susceptibility of, 2260, 2260t N-based ligand complexes of, 1962–1965, 1963f–1964f organometallic chemistry of, 630 oxide halides of, 456 preparation of, 456 structure of, 456 with pyrochemical processes, 2696, 2697f reduction potentials of, 2715, 2716f speciation of, 3101t–3102t, 3116 Uranium (IV) aqua ion of, 593–595, 594t biochemistry of, 630 bromides of, 494–497 oxide and nitride, 497, 500 ternary and polynary compounds, 495–497 uranium tetrabromide, 494–495 chlorides of, 490–493 complex chlorides, 492–493 nitride, 500 oxychloride and oxochloro complexes, 494 uranium tetrachloride, 490–492 compounds of, 575–576 molybdates of, 275 niobates, 277–280 orthosilicates of, 275–276 oxides, 372t–378t, 380–382 phosphates of, 275 silicates of, 276–277 structure and coordination geometry of, 585–588, 586f–588f tantalates, 277–280 titanates, 277–280 coordination numbers analysis of, 586–588 curium (IV) v., 585–586

crystal-field splittings of, 2247–2248 detection of ISEs, 3029 TRLF, 3037 XAS, 3039 DNA footprinting with, 630–631 electron configurations of, 2018–2019, 2018f extraction of, DHDECMP, 2737–2738 fluorides of, 484–490 complex fluorides, 487–489, 2255t, 2256 oxide and nitride, 489–490 uranium tetrafluoride, 484–486 uranium tetrafluoride hydrates, 486–487 halides of absorption spectra of, 482–483, 483f band structure of, 483 complexes with, 601 crystal-field strength of, 482–483 history of, 456 magnetic properties of, 483 mixed, 499–500 nitrogen-containing, 500 physical properties of, 456, 457t–481t stability of, 456 structure of, 456, 482 hydration of, 2531 hydrolytic behavior of, 585–586, 2550–2551 iodides of, 497–499 iodo complexes, 498–499 oxide and nitride, 499–500 uranium tetraiodide, 497–498 in living organisms, 631 magnetic properties of, 2247–2257, 2255t in mammalian tissues circulation clearance of, 3376–3377 initial distribution, 3342t, 3346t, 3351 organometallic chemistry of, 630 phases of, 280–302 bonding, 280–281 polymerization of, 1780–1781 with pyrochemical processes, 2696, 2697f reduction by, americium (V), 1337 separation of SNF, 2646 solvating extractant system for, 2654–2655 speciation of, 3101t–3102t, 3105–3106, 3136 spectroscopic properties of, 2066–2067, 2066t water exchange in complexes of, 611t–612t, 614 in wyartite, 290 Uranium (V) bromides of, 526–528 oxides, 527–528 ternary and polynary, 526–527

Subject Index

I-129

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 ternary and polynary oxide and oxobromo, 528 uranium pentabromide, 526 chlorides of, 522–526 complex chloride compounds, 523–524 oxide, 524–525 oxochloride, 525–526 uranium pentachloride, 522–523 fluorides of, 518–521 complex fluoro compounds, 520–521 oxide fluorides and complexes, 521 uranium pentafluoride, 518–520 halides of, 501–529 absorption spectra, 501 bonding in, 576–577 complexes with, 601 physical properties of, 501, 502t–517t stability of, 501 magnetic properties of, 2240–2247, 2247t oxides, 372t–378t, 380–382 in pyrochlore and zirconolite, 279 in wyartite, 290 Uranium (VI) americium (V) interaction with, 1356 bacterial reduction of, 297 bromides of, 571–574 uranium oxobromo complexes, 572–574 uranyl bromide, 571–572 uranyl hydroxide bromide and bromide hydrates, 572 chlorides, 567 oxochloro complexes, 570 perchlorates and related compounds, 570–571 uranium dioxide dichloride, 567–569 uranium hexachloride, 567 uranyl chloride hydrates and hydroxide chlorides, 569–570 detection of ISEs, 3029 limits to, 3071t NMR, 3033 RAMS, 3035 RBS, 3063–3064, 3064f distribution coefficients of, 842, 842t extraction of, 3066 americium (III) v., 1284 TBP, 3282 ferrihydrate adsorption of, 3166–3167 fluorides of, 557–564 complex fluorides, 563–564 hexavalent oxide fluoride complexes, 566–567 uranium hexafluoride, 557–563 uranium oxide difluoride, 565–566 uranium oxide tetrafluoride, 564–565 halides of, 529–575 absorption spectra of, 529, 557

applications of, 529 bonding in, 576–577 complexes with, 601 ground state of, 557 mixed halogeno-complexes, 574–575 iodides of, 574 magnetic properties of, 2239–2240 oxides, 371–380, 372t–378t phosphates of, 297 polarography for, 791–792 with pyrochemical processes, 2696, 2697f separation of HDEHP for, 2651, 2651f PUREX process, 2732 SFE for, 2682 sulfuric acid dissolution of, 305 Uranium aqua ions, 590–597 applications of, 593 dioxouranium (V), 594t, 595 dioxouranium (VI), 594t, 596, 596f oxidation states of, 590 oxygen atoms in, 592–593 redox behavior of, 590–591, 592f, 594t tetrapositive uranium, 593–595 tripositive uranium, 593 Uranium arsenide, magnetic properties of, 2234–2235, 2235f Uranium azide, 602, 603t Uranium bis-cycloheptatrienyl, ionic configuration of, 2246 Uranium borides, structural chemistry of, 2406t, 2407 Uranium borohydride structure of, 2404–2405, 2405f uranium (IV), 337 Uranium bromides, 453–454 bromo complexes, 454 oxide and nitride, 497, 500 physical properties of, 497, 500 preparation of, 497, 500 ternary and polynary, 528 ternary and polynary compounds, 495–497, 526–527 bonding in, 496–497 oxide and oxobromo compounds, 528 physical properties of, 496, 526–527 preparation of, 495–496, 526 uranium dioxide monobromide, 527–528 preparation of, 527 properties of, 527–528 uranium oxide tribromide, 527 uranium oxobromo complexes, 572–574 physical properties of, 573 preparation of, 572 reactions of, 573–574 uranium pentabromide, 526 uranium tetrabromide, 494–495 absorption spectra of, 495

I-130

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Uranium bromides (Contd.) physical properties of, 495 preparation of, 494–495 uranium tribromide, 453 preparation of, 453 properties of, 453 uranium tribromide hexahydrate, 453–454 uranyl bromide, 571–572 physical properties of, 571–572 preparation of, 571 uranyl hydroxide bromide and bromide hydrates, 572 Uranium carbide entropy of, 2196, 2197t formation enthalpy of, 2195–2196, 2197t high-temperature properties of, 2198, 2198f, 2199t Uranium carbide oxides binding energy of, 1980 electronic structure of, 1977–1978, 1977t, 1982, 1983f ground state configuration of, 1978–1979, 1979f interesting compounds of, 1982–1984, 1984t isolation of, 1978 Uranium carbonates, structural chemistry of, 2426–2427, 2427t Uranium carbonyl, 1984–1985 Uranium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t, 2414f Uranium chlorides anhydrous complexes, 450–452 physical properties of, 451 preparation of, 450–451 sodium in, 451–452 structure of, 451 complexes, 492–493, 523–524 isolation of, 523 ligands of, 492–493 magnetic properties of, 493 oxochloro, 494, 570 oxychloride, 494 physical properties of, 492–493, 524 preparation of, 492–493, 523–524 nitride, 500 oxide, 524–525 oxochloride, 525–526 absorption spectra of, 526 preparation of, 525–526 perchlorates and related compounds, 570–571 physical properties of, 571 preparation of, 570–571 uranium dioxide dichloride, 567–569 hydrates, 569–570 hydroxide chlorides, 569–570 physical properties of, 568–569 preparation of, 567–568

reactions of, 568–569 uranium hexachloride, 567 properties of, 567 synthesis of, 567 uranium pentachloride, 522–523 preparation of, 522 properties of, 522–523 uranium perchlorates, 494 uranium tetrachloride, 490–492 application of, 490–491 magnetic properties of, 491–492 physical properties of, 490–491 preparation of, 490 uranium trichloride, 446–448, 447f absorption spectra of, 447 magnetic properties of, 448 with neutral donor ligands, 452 physical properties of, 446–447 preparation of, 446 structure of, 447, 447f uranium trichloride hydrates, 448–450 absorption spectra of, 449–450 structure of, 448–449 synthesis of, 448–450 Uranium complexes, aqueous, 597–606 donor-acceptor interactions of, 597 hydrolytic behavior of, 597–600, 599t inorganic ligand complexes, 601–602, 601t organic ligand complexes, 603–605, 604t structure of, 597 ternary uranium complexes, 605–606 uranium (III), uranium (IV), uranyl (V), and uranyl (VI) complexes, 598, 601t, 604t between uranyl (V) and other cations, 606 Uranium deposits classification of, 270–273 groups of, 270 locations of, 271 exploration of, 3065 at Koongarra deposit, 273 at Oklo, Gabon, 271–272 at Pena Blanca, Chichuhua District, Mexico, 272–273 at Shinkolobwe deposit, 273 Uranium dicarbide, structural chemistry of, 2406t, 2408 Uranium dioxide bond lengths of, 1973, 1975t complex formation with, 606, 1921–1925, 1922f, 1923t, 1924f crystal structures of, 344, 345t–346t crystal-field ground state of, 2274 splittings, 2278–2279 theory for, 2278, 2279f diffusion of, 367–368 dissolution in hydrogen peroxide, 371 gas pressure generation with, 3251

Subject Index

I-131

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 in gas-phase, 2148, 2148t ground state of, 1972–1973 infrared spectroscopy of, 1971 magnetic properties of, 2272–2282 magnetic scattering of, 2281, 2282f magnetic structure of, 2273–2276, 2274f, 2276f magnetic susceptibility of, 2272–2273 magnon dispersion curves of, 2280–2281, 2280f neutron scattering of, 2285–2286, 2286f NMR of, 2280 optical properties of, 2276–2278, 2277f oxidation to U3O8, 369–370 phase relations of, 351–353, 352f preparative methods of, 339–340 RXS of, 2281 solid solutions with, 389–398 lattice parameter change, 390, 391t–392t magnetic properties, 389–390 in oxidizing atmospheres, 394 oxygen potentials, 394–398, 395t preparation of, 389–390 in reducing atmospheres, 392, 393t regions of, 390–394 structure of, 2391–2392 thermodynamic properties of enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 heat capacity of, 357–359, 359f, 2138–2141, 2139f, 2142t, 2272–2273, 2273f vaporization of, 364–367, 366f Uranium dioxide dichloride, 567–569 physical properties of, 568–569 preparation of, 567–568 reactions of, 568–569 Uranium dioxide monobromide, 527–528 preparation of, 527 properties of, 527–528 Uranium disulfide, structure of, 2412t–2413t, 2414, 2414f Uranium fluorides fluoro complexes, 445–446, 487–489, 520–521, 520t, 563–564, 564t applications of, 563 disproportionation of, 520–521 melting behavior of, 487, 488t phase diagram of, 487, 489f physical properties of, 487–488, 521 preparation of, 446, 487, 520, 520t, 563–564 hexavalent oxide fluoride complexes, 566–567 physical properties of, 566–567 preparation of, 566 oxides and nitrides of, 489–490

pentavalent oxide fluorides and complexes, 521 absorption spectra of, 521 preparation of, 521 polynuclear, 579 uranium hexafluoride, 557–563 application of, 557, 561–562 phase diagram of, 563, 563f physical properties of, 560–561 preparation of, 557–560, 558f, 560f uranium oxide difluoride, 565–566 physical properties of, 565 preparation of, 565 uranium hexafluoride conversion of, 565–566 uranium oxide tetrafluoride, 564–565 physical properties of, 565 preparation of, 564–565 uranium pentafluoride, 518–520 characterization of, 519–520 preparation of, 518 properties of, 518–519, 519f reduction of, 518 uranium tetrafluoride, 484–486 applications of, 484 physical properties of, 485–486 preparation of, 484–485 uranium hexafluoride preparation from, 485 uranium tetrafluoride hydrates, 486–487 physical properties of, 486–487 preparation of, 486 uranium trifluoride, 444–445 physical properties of, 445 preparation of, 444–445 structure of, 445 uranium trifluoride monohydrate, 445–446 preparation of, 445 Uranium halides, 420–575 applications of, 420 chemistry of, 421 hexavalent and complex, 529–575 absorption spectra of, 529, 557 applications of, 529 ground state of, 557 mixed halgeno-complexes, 574–575 oxide bromides and oxobromo complexes, 571–574 properties of, 529, 530t–556t uranium compounds with iodine, 574 uranium dioxide dichloride and related compounds, 567–570 uranium hexachloride, 567 uranium hexafluoride and complex fluorides, 557–564 uranium oxide fluorides and complex oxide fluorides, 564–567 uranium oxochloro complexes, 570

I-132

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Uranium halides (Contd.) uranium perchlorates and compounds, 570–571 intermediate, 528–529 characterization of, 529 equilibrium of, 528 preparation of, 528–529 oxidation states in, 420–421 pentavalent and complex, 501–529 absorption spectra of, 501 physical properties of, 501, 502t–517t stability of, 501 ternary and polynary oxide bromides and oxobromo compounds, 528 uranium oxide bromides, 527–528 uranium oxide chlorides, 524–525 uranium oxochloride, 525–526 uranium pentabromide and complex bromides, 526–527 uranium pentachloride and complex chlorides, 522–524 uranium pentafluoride and complex fluorides, 518–521 tervalent and complex, 421–456 absorption spectra of, 442, 443f anhydrous uranium chloro complexes, 450–452 electronic structure of, 422 history of, 421–422 magnetic properties of, 443–444 oscillator strengths, 442–443 oxide halides, 456 properties of, 422, 423t–441t stability of, 422 synthesis of, 422 uranium tribromide and bromo complexes, 453–454 uranium trichloride and chloro complexes, 446–452 uranium trichloride hydrates and hydrated chloro complexes, 448–450 uranium trifluoride and fluoro complexes, 444–445 uranium trifluoride monohydrate and fluoro complexes, 445–446 uranium triiodide and iodo complexes, 454–455 tetravalent and complex, 456–500 absorption spectra of, 482–483, 483f band structure of, 483 crystal-field strength of, 482–483 history of, 456 magnetic properties of, 483 mixed halides and halogeno compounds, 499–500 nitrogen-containing, 500 physical properties of, 456, 457t–481t stability of, 456

structure of, 456, 482 uranium oxide dibromide and nitride bromides, 497 uranium oxide diiodide and nitride iodide, 499 uranium oxide fluorides and nitride fluorides, 489–490 uranium oxychloride oxochloro complexes, 494 uranium perchlorates, 494 uranium tetrabromide and complex bromides, 494–497 uranium tetrachloride and complex chlorides, 490–493 uranium tetrafluoride and fluoro complexes, 484–489 uranium tetraiodide and complex iodides, 497–499 Uranium hexachloride, 567 magnetic susceptibility of, 2245–2246 properties of, 567, 568f structural chemistry of, 2419, 2421, 2421t synthesis of, 567 thermodynamic properties of, 2160–2161, 2160t, 2162t–2164t Uranium hexafluoride, 557–563, 1933–1939 application of, 557, 561–562 bond lengths of, 1935–1937, 1937t compounds of, 576–577 distillation of, 315–317, 316f, 317t energy levels of, 1934–1935, 1934f, 1936t enthalpy of formation of, 2159, 2160t magnetic properties of, 2239–2240 phase diagram of, 563, 563f physical properties of, 560–561 preparation of, 557–560, 558f, 560f structural chemistry of, 2419, 2421, 2421t studies of, 1935, 1938 thermodynamic properties of, 2159–2161, 2160t, 2162t–2164t TIP and, 2239–2240 uranium oxide difluoride conversion to, 565–566 uranium tetrafluoride preparation of, 485 vibrational frequencies of, 1935–1937, 1937t Uranium hydride, uranium reactions with, 3246 Uranium hydrides, 3213–3214 entropy of, 2188, 2189t formation enthalpy of, 2187–2188, 2187t, 2189t, 2190f high-temperature properties of, 2188–2190, 2190t structure of, 2403 Uranium iodides, 454–455, 497–500, 574 complexes, 498–499 with neutral donor ligands, 455

Subject Index

I-133

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 preparation of, 498 properties of, 498–499 oxide and nitride, 499–500 uranium tetraiodide, 497–498 physical properties of, 498, 498f preparation of, 497–498 uranium triiodide, 454–455 physical properties of, 455 preparation of, 454–455 Uranium monoxide dissociative energy of, 2149–2150, 2150f in gas-phase, 2148, 2148t Uranium nitride, 3215 enthalpy of formation of, 2197t, 2200–2201, 2201f entropy of, 2197t, 2201–2202 high-temperature properties of, 2199t, 2202 Uranium ores actinium from, 27 plutonium in, 822 protactinium from, 172–178 Uranium oxide difluoride, 565–566 physical properties of, 565 preparation of, 565 uranium hexafluoride conversion of, 565–566 Uranium oxide tetrafluoride, 564–565 physical properties of, 565 preparation of, 564–565 Uranium oxide tribromide, 527 Uranium oxides, 3214–3215 alkali and alkaline-earth metals, 371–383 non-stoichiometry, 382–383 uranates (VI), 371–380 uranates (V) and (IV), 381–382 binary, 339–371 chemical properties of, 369–371, 370t crystal structures of, 343–351, 345t–346t diffusion, 367–368 electrical conductivity of, 368–369 oxygen potential, 360–364, 361f–363f phase relations of, 351–357, 352f physical properties of, 345t–346t preparative methods of, 339–343, 341f reactions of, 370, 370t single crystal preparation, 343 thermodynamic properties, 360–364, 361f–363f UO2 heat capacity, 357–359, 359f UO2 vaporization, 364–367, 366f from fuel fire, 3255 geometric parameters of, 1973, 1974t–1975t infrared spectroscopy of, 1971 plutonium oxides with, 1070–1077 applications of, 1070–1071 phase diagram of, 1071–1073, 1073f preparation of, 1073–1074 properties of, 1074–1077

safe storage, 3262 structure of, 2391–2394, 2393f thermodynamic properties of, 2135, 2136t transition metals, 383–389, 384t–387t crystal structures of, 388–389 preparative methods of, 383, 388 properties of, 384t–387t U2O5 phase relations of, 354f, 355 preparative methods of, 340–341 U3O7 crystal structure of, 347–349 phase relations of, 354f, 355 preparative methods of, 340 U3O8 crystal structure of, 349–350, 349f electrical conductivity of, 368–369 preparative methods of, 341 UO2 oxidation to, 369–370 UO3 reduction to, 369–370 U4O9 crystal structures of, 344, 345t–346t, 347, 348f phase relations of, 353–354, 354f U4O9, preparative methods of, 340 U8O19, phase relations of, 354f, 355 UO, preparative methods of, 339 UO2 solid solutions, 371–383 lattice parameter change, 390, 391t–392t magnetic properties, 389–390 in oxidizing atmospheres, 394 oxygen potentials, 394–398, 395t preparation of, 389–390 regions of, 390–394 UO3 crystal structure of, 350–351 hydrates, preparative methods of, 342–343 preparative methods of, 341–342, 341f reduction to U3O8, 369–370 Uranium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Uranium pentabromide, 526 thermodynamic properties of, 2160t, 2161, 2164–2165, 2164t Uranium pentachloride, 522–523 preparation of, 522 properties of, 522–523 structural chemistry of, 2419, 2419f, 2420t thermodynamic properties of, 2160t, 2161, 2164–2165, 2164t Uranium pentafluoride, 518–520 characterization of, 519–520 compounds of, 576–577 preparation of, 518 properties of, 518–519, 519f reduction of, 518

I-134

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Uranium pentafluoride (Contd.) structural chemistry of, 2416, 2419, 2419f, 2420t thermodynamic properties of, 2160t, 2161, 2164–2165, 2164t Uranium pentahalides, structural chemistry of, 2416, 2419, 2420t Uranium perchlorate, 570–571 physical properties of, 571 preparation of, 570–571 Uranium phosphates, structural chemistry of, 2430–2433, 2431t–2432t, 2433f Uranium pnictides, structure of, 2409–2414, 2410t–2411t Uranium selenolate, from cyclopentadienyl complexes, 2807–2808 Uranium sesquioxide, formation enthalpy of, 2143–2146, 2144t, 2145f Uranium silicides, structural chemistry of, 2406t, 2408 Uranium sulfates magnetic susceptibilities of, 2252 structural chemistry of, 2433–2436, 2434t, 2435f Uranium tetrabromide, 494–495 absorption spectra of, 495 physical properties of, 495 preparation of, 494–495 Uranium tetrachloride, 490–492 application of, 490–491 magnetic properties of, 491–492 covalency of, 2249–2251 crystal-field splittings of, 2249 magnetic susceptibility, 2248, 2249f physical properties of, 490–491 preparation of, 490 reduction of, 319 thermodynamic properties of, 2165–2169, 2166t Uranium tetrafluoride, 484–486 absorption spectra of, 2068, 2069f applications of, 484 coordination chemistry of, 600 hydrates, 486–487 physical properties of, 486–487 preparation of, 486 physical properties of, 485–486 preparation of, 484–485 reduction of, 319 thermodynamic properties of, 2165–2169, 2166t uranium hexafluoride preparation from, 485 Uranium tetrahalides, structural chemistry of, 2416, 2418t Uranium tetraiodide, 497–498 physical properties of, 498, 498f preparation of, 497–498 thermodynamic properties of, 2166t, 2168

Uranium thiocyanate, 602, 603t Uranium thiolate, from cyclopentadienyl complexes, 2807–2808 Uranium tribromide, 453–454 hexahydrate, 453–454 physical properties of, 453–454 preparation of, 453 magnetic susceptibility of, 2257–2258, 2258t physical properties of, 453 preparation of, 453 Uranium trichloride, 446–448 absorption spectra of, 447 hydrates and hydrated complexes, 448–450 absorption spectra of, 449–450 structure of, 448–449 synthesis of, 448–450 magnetic properties of, 448 magnetic susceptibility of, 2257–2258, 2258t with neutral donor ligands, 452 physical properties of, 446–447 preparation of, 446 structural chemistry of, 447, 447f, 2416, 2417t thermodynamic properties of, 2170t, 2173t, 2176–2178 Uranium trifluoride magnetic susceptibility of, 2257, 2258t monohydrate, 445–446 preparation of, 445 physical properties of, 445 preparation of, 444–445 structure of, 445 thermodynamic properties of, 2169, 2170t–2171t, 2176–2178 Uranium trihalides, structural chemistry of, 2416, 2417t Uranium trihydride magnetic properties of, 2257, 2362 structure of, 2403 Uranium triiodide, magnetic susceptibility of, 2257–2258, 2258t Uranium trioxide in gas-phase, 2148, 2148t structure of, 2393–2394, 2393f Uranium tris-cyclopentadienyl, magnetic susceptibility of, 2259, 2259t Uranium X1 (UX1). See Thorium–234 Uranium X2 (UX2). See Protactinium–234 Uranium Y (UY). See Thorium–231 Uranium–232 isolation of, 256 nuclear properties of, 3274t–3275t, 3290t synthesis of, 256 Uranium–233 detection of AMS, 3062–3063, 3318 NMR, 3033 extraction of, 176

Subject Index

I-135

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 nuclear energy with, 255 nuclear properties of, 3274t–3275t, 3290t as probe for isotopic exchange study, 621 production of, 256–257 protactinium–233 in, 161, 167–169 from thorium–232, 53 for thorium-uranium fuel cycle, 2734 Uranium–234 detection of AMS, 3318 γS, 3300 ICPMS, 3327 limits to, 3071t PERALS, 3066, 3067f RIMS, 3321–3322 αS, 3293 TIMS, 3313–3314 nuclear properties of, 3274t–3275t, 3290t occurrence in nature, 255, 256t, 257 separation of, 257 Uranium–235 absorption cross section of, 2233 dating with protactinium–231, and, 170–171 detection of FTA, 3307 γS, 3300–3302, 3301f INAA, 3303–3304 limits to, 3071t NAA, 3055–3057, 3056t, 3058f NMR, 3033 RIMS, 3321–3322 RNAA, 3306 αS, 3293 TIMS, 3313–3314 discovery of, 255 laser spectroscopy of, 1873 natural occurrence of, 3273, 3276 neptunium–237 from, 1757 nuclear energy with, 255, 826, 1826–1827 products of, 826, 827t–828t, 828 nuclear properties of, 3274t–3275t, 3290t occurrence in nature, 26–27, 255–256, 256t, 823–824, 1804–1805 plutonium–239 regeneration of, 824 products of, 1756 security risk of, 1758 Uranium–236 detection of AMS, 3062–3063, 3318 αS, 3293 nuclear properties of, 3274t–3275t, 3290t Uranium–238 detection of γS, 3027–3028, 3028f, 3300–3302, 3301f ICPMS, 3327 INAA, 3304–3305 limits to, 3071t MBAS, 3043

MBES, 3028 NAA, 3055–3057, 3056t, 3058f PERALS, 3066, 3067f RIMS, 3321–3322 αS, 3029, 3293 TIMS, 3313–3315 natural occurrence of, 3273, 3276 neptunium–237 from, 1757 neptunium–239 from, 702, 704 nuclear energy with, 255 nuclear properties of, 3274t–3275t, 3290t occurrence in nature, 255, 256t, 1804–1805 plutonium–238 from, 815 in THOREX process, 2735–2736 Uranium–239 discovery of, 255 nuclear properties of, 3274t–3275t Uranium-actinium series (4n þ 3), 21f, 166f actinium–227 in, 20, 21f protactinium–231 in, 164–166, 166f thorium–227 from, 53 thorium–231 from, 53 uranium–235 in, 256 UPt3, superconductivity of, 2351 Uranocene covalency in, 2854, 2855f crystal-field parameters of, 2253 cyclooctatetraenyl complexes derivatives of, 2851–2853, 2852f electronic transitions in, 1951–1952, 1952t magnetic susceptibility of, 2252–2253 structure of, 1943–1944, 1944t, 1945f, 2486, 2488t synthesis of, history of, 1894, 2485–2486 uranium bis-cycloheptatrienyl v., 2246 Uranophane anion topology of, 284f–285f, 286 natural occurrence of, 292 at Pen˜a Blanca, Chichuhua District, Mexico, 272–273 at Shinkolobwe deposit, 273 structures, of uranium phosphates and arsenates, 295 uranium in, 259t–269t Uranopilite at Oklo, Gabon, 271–272 uranium in, 259t–269t Uranospathite, refinement of, 295 Uranothorianite, thorium from, 55, 58 Uranotungstite, uranyl tungstates in, 301 Uranyl (V) bonding of, 577–578 structure and coordination chemistry of, 588–589 Uranyl (VI) bonding of, 577–578, 577f bond-valence of, 3093–3094, 3094f

I-136

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Uranyl (VI) (Contd.) carboxylates, EXAFS investigations of, 3137–3140, 3141t–3150t coordination geometry of, 3132 fluorescence properties and photochemistry of, 624–630 fluorescence v. phosphorescence, 627 of ion, 629–630 quenching mechanisms, 629 speciation of, 3101t–3102t, 3118–3121, 3126–3133 structure and coordination chemistry of, 580–584, 580f–584f tris(carbonato) complex of, 3131–3132 water exchange in complexes of, 611t–612t, 614 Uranyl bromide, 571–572 physical properties of, 571–572 preparation of, 571 study of, 1933 Uranyl chloride. See Uranium dioxide dichloride Uranyl fluoride. See Uranium oxide difluoride Uranyl hydroxide bromide, 572 Uranyl ion, 1914–1920 5f covalency in, 1915–1916 adsorption of iron-bearing mineral phases, 3167 phosphates, 3171 calculated properties of, 1918–1920, 1919t–1920t charge-transfer of, 2085–2089, 2087f, 2088f chitosan adsorption of, 2669 complexes of on bentonite, 3157–3158 bidentate ligands, 1926–1928, 1928t, 1929f calixarene, 2456, 2457t–2458t, 2459–2463, 2459f cation-cation, 2594 crown ether, 2449–2451, 2449t, 2450f, 2452t–2453t, 2453–2456, 2454f–2455f hydroxide, 1925–1926, 1926t, 1927f on montmorillonite, 3155–3156 porphyrins and phthalocyanines, 2463–2467, 2464t, 2466f–2467f structure of, 2400–2402 with water, 1921–1925, 1922f, 1923t, 1924f compounds of in aragonite, 3160–3161, 3161t in calcite, 3160–3161, 3161t Dirac-Hartree-Fock calculations on, 1917–1918 electronic structure of, 1971–1972 calculation of, 1915 excited states of, 1930 extraction of, REDOX process, 2730–2731

highest occupied orbitals in, 1916–1917, 1917f history of, 2399–2400 hydration number of, 2531–2532, 2533t hydrolytic behavior of, 2553–2556, 2554f–2555f, 2554t–2555t iron-bearing mineral phases coprecipitation, 3168–3169 HFO interaction with, 3166 trapped, 3168 ligands for, 3421, 3422f linear geometry of, 1917 magnetic properties of, 2239–2240 in mammalian tissues bone, 3403 bone binding, 3407 circulation clearance of, 3368–3369, 3368f–3375f, 3376–3377, 3379–3384 erythrocytes association with, 3366–3367 initial distribution, 3342t–3346t, 3354–3355 transferrin binding to, 3365 solvation of, 2532–2533 thermodynamic properties of, 2544 TIP and, 2239–2240 vibrational frequencies of, 1920 water reaction with, 3239 Uranyl perchlorate. See Uranium perchlorate Uranyl polyhedra bonding in, 280–281 geometries of, 281–282, 284f–286f Urine electrolytes concentrations in, 3356–3357, 3357t uranyl complexes in, 3383–3384 URu2Si2, superconductivity of, 2352 U/TEVA•Spec DAAP in, 3284 for separation, 3284–3285 UVS. See Ultraviolet spectroscopy UX1. See Thorium–234 UX2. See Protactinium–234 UY. See Thorium–231 Vacancy clusters, phase stability and, 984 Vacuum melting and casting, for plutonium metal production, 870, 871f–872f Vadose zone, actinide elements in, 1809–1810 Valence electrons, phase stability and, 927 Valence spinor energies, of uranyl, 1918, 1918f Vanadates of thorium, 110, 111f phosphates v., 110 structure of, 110, 111f of uranium, 266t–267t, 297–298 in uranium ion exchange extraction, 311 Vanadium, uranium ore removal of, 304

Subject Index

I-137

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Vandendriesscheite anion topology of, 283, 284f–285f at Shinkolobwe deposit, 273 uranium in, 259t–269t Vapor pressure of berkelium, 1459 of californium, metal, 1523, 1524f of liquid plutonium, 963 of plutonium hexafluoride, 1086 tetrafluoride, 1085–1086 of protactinium, 192, 193t halides, 200 of uranium dioxide, 365–366, 366f Vaporization of californium metal, 1523–1524, 1524f oxides, 1537 of einsteinium, 1603 production of, 1609 of fermium, metal, 1628 of plutonium oxides, 1045–1047, 1046f with uranium oxides, 1074 of plutonium, tribromide, 1100 of UO2, 364–367, 366f VDPA. See Vinylidene–1,1-diphosphonic acid Vermiculite, uranyl-loaded, 3156 Vibrational frequencies of actinide carbide oxides, 1977, 1977t of actinide nitride oxides, 1990, 1990t of actinide nitrides, 1988, 1989f of actinyl complexes, 1923, 1924f of plutonium hexafluoride, 1086–1088, 1090t ions, 1116–1117 of uranium oxides, 1973, 1974t uranium dioxide, 1972 uranium hexafluoride, 1935–1938, 1937t uranyl, 1920, 1972, 2087 Vibrational spectroscopy of americium, 1369–1370 of matrix-isolated actinide molecules, 1968 of organometallic actinide compounds, 1800 of plutonium, ions, 1114–1117 Vickers microhardness, of plutonium, 970, 970f Vinylidene–1,1-diphosphonic acid (VDPA), actinide stripping with, 1280–1281 Viscosity, of liquid plutonium, 962–963 Void swelling, of plutonium, 981, 987 VOL. See Volumetry Volatility of dubnium, 1703 of elements 116–118, 1728

of rutherfordium, 1692 of transactinide element gas-phase compounds, 1684–1685, 1715 Volatility-based separation methods, 2632–2633 Voltammetry for californium, 1548 method for, 756 for neptunium, 755–757, 756t, 757f determination of, 791–792 for plutonium, 1119 for thorium, 133 Volumetric techniques, for uranium, 633–634 Volumetry (VOL), for environmental actinides, 3059t, 3061 Vyacheslavite, uranium in, 259t–269t, 275 Water actinide elements in electrochemical equilibria, 3096 standard reduction potentials, 3097, 3098t americium (II) oxidation by, 1337 in coordination chemistry, 3096 einsteinium cocrystallization and, 1608 plutonium reaction with, 3213 hydrides, 3219 metal, 3225–3238 oxides, 3219–3222 radiolytic decomposition of adsorbed, 3221 radionuclide pollution in, 3095 uranium corrosion by, 3242–3245, 3243f, 3244t in uranium dioxide complex, 1921–1925, 1922f, 1923t, 1924f exchange in, 1923–1925, 1924f uranyl ion reaction with, 3239 Water samples actinide handling in, 3022 treatment of, 3022–3023 Weapon-grade uranium description of, 1755 production of, 1757–1758 scope of concern of, 3202 Weeksite, structure of, 292–293 Wigner-Eckart theorem, for free-ion interactions, 2027–2028 Wigner-Seitz radius, of metallic state, 2310–2312, 2311f Wo¨lsendorfite anion topology of, 284f–285f, 286 from clarkeite, 288 Wyartite, structure of, 290 Wybourne’s formalism, for crystal-field interactions, 2039–2040

I-138

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 XANES. See X-ray absorption near-edge structure spectroscopy XAS. See X-ray absorption spectroscopy Xenotime, thorium in, 56t XMCD. See X-ray magnetic circular dichroism XPS. See X-ray photoelectron spectroscopy X-ray absorption fine structure (XAFS) for actinide-oxygen bond distances, 2530–2531 of actinyl ions, 2532 of berkelium, 1474 for hydration study, 2528 neptunium (V) speciation with, 795 X-ray absorption near-edge structure spectroscopy (XANES) of berkelium, 1474 for environmental actinides, 3034t, 3039, 3040f of neptunium (IV), 3107–3108 of plutonium (IV), 3108–3109 of plutonyl (V), 3210 polarization for, 3088–3089 for redox potential determination, 754, 754f of solid samples, sorption studies of, 3172–3173 of uranium silicate phosphate, 3170 uranium (V), 279 for valence measurement, 3087, 3089f–3091f of XAS, 3087, 3088f XPS with, 3069 X-ray absorption spectroscopy (XAS) for actinides, 14, 1770, 3086–3184 future direction, 3183–3184 sorption studies, 3140–3183 terrestrial aquatic environment, 3095–3140 for americium, 1296, 1370 for bacterial sorption, 3177–3178, 3179t–3180t of berkelium (IV/III), 3110 bond-valence sums for, 3093–3094 for environmental actinides, 3034t, 3037–3039, 3040f future direction for, 3183–3184 issues with, 3094–3095 for plutonium, 859–861 of protactinium, 226–227 of solid samples, sorption studies of, 3171–3172 synchrotron for, 3087 for thorium ligand study, 131 of uranium, in calcite, 3163–3164 XANES and EXAFS of, 3087, 3088f

X-ray atomic energy levels, of protactinium, 190, 190t X-ray crystallography. See also X-ray diffraction for actinide element detection, 11 of actinyl complexes, 1921 of berkelium, 1462, 1464t–1465t of californium, metal, 1519, 1520t of curium, 1413t–1415t for electronic structure, 1770 of plutonium borides, 999t carbides, 1005t, 1010t chalcogenides, 1050t–1051t fluorides, 1084t oxides, 1025, 1027t oxoplutonates, 1060t–1061t pnictides, 1020t silicides, 1012t ternary oxides, 1066t–1067t of protactinium, chloro and bromo complexes, 204, 205t of thorium borides, carbides, and silicides, 69, 71t–73t chalcogenides, 70, 75t complex anions, 101, 102t–103t halides, 78, 78t, 87t–89t hydrides, 65, 66t pnictides, 97–99, 98t of uranium intermetallic compounds and alloys, 325 trichloride hydrates, 448–450, 450 X-ray detection, protactinium for, 188 X-ray diffraction (XRD). See also Powder X-ray diffraction for actinide study, 1767 of berkelium, 1445, 1469 of californium, 1522 for coordination geometry study, 602–603 description of, 2381–2382 for hydration study, 2528 improvements to, 3093 IRS and, 3065 methods for, 2382 of neptunium dioxide, 725 trichloride, 737 neutron diffraction v., 2383 of plutonium oxide-water reaction, 3209–3210 for structural chemistry, 2381–2383 of thorium hydrides, 64 perchlorate, 101 X-ray emission spectroscopy, of californium, 1516–1517

Subject Index

I-139

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 X-ray fluorescence (XRF) americium–241 for, 1828 for environmental actinides, 3034t, 3039, 3041f future direction for, 3183–3184 of neptunium, 788 RAMS and IRS with, 3069 of solid samples, sorption studies of, 3172–3173 of uranium, 636–637 X-ray magnetic circular dichroism (XMCD) advantages/disadvantages of, 2236 development of, 2236 for magnetic studies, 2236 X-ray measurement, for transactinide identification, 1659, 1662 X-ray photoelectron spectroscopy (XPS) AES v., 3051 for electronic structure, 1770 for environmental actinides, 3044t, 3045 neptunium characterization with, 795 of plutonium, 861 oxides, 3208 of transplutonium oxides, 1516–1517 of uraninite, 274 XANES with, 3069 X-ray scattering of actinyl complexes, 1921 neutron scattering v., sample size, 2233–2234 of uranyl (VI), 3128–3129 X-ray spectroscopy (XS), for environmental actinides, 3025, 3026t X-ray tomography (TOM), for environmental actinides, 3034t, 3040–3043, 3042f X-ray tubes, for XRD, 2382 XRD. See X-ray diffraction XRF. See X-ray fluorescence XS. See X-ray spectroscopy ‘Yellow cake,’ refinement of, 314–317, 315f–316f, 317t Ytterbium in einsteinium alloy, 1592 einsteinium v., 1578–1579 Yucca Mountain site, sorption studies of soil samples, 3175–3176

Zeeman interaction, in magnetic properties, 2225–2226 Zeolites, uranium compounds on, 301–302 Zero-phonon lines (ZPL) in curium excitation spectra, 2061f, 2062 in protactinium excitation spectra, 2067–2068, 2068f of uranyl, 2087, 2088f ζ-Phase, of plutonium, 882f–883f, 883, 890, 891f density of, 936t strength of, 968f, 970 thermoelectric power, 957–958, 958t Zippeite, uranium sulfates in, 291–292 Zircon, thorium in, 56t Zirconium californium compound with, 1538 carbamoylmethylenephosphine oxide extraction of, 1280 extraction with TTA, 1701 protactinium purification from, 178–186 ion exchange, 180–181, 180f precipitation and crystallization, 178–179 solvent extraction and extraction chromatography, 181–186, 183f rutherfordium v., 1692–1693, 1694f, 1702 extraction of, 1697–1700 uranium dioxide solid solutions with oxygen potentials, 394, 395t properties of, 390, 391t–392t Zirconolite geochemical studies of, 278 natural occurrence of, 277–278 properties of, 278 uranium (V) in, 279 Zone melting, for uranium metal preparation, 319 Zone-refining, for plutonium metal production, 876–877 americium removal in, 877 equipment for, 877, 878f overview of, 876 process of, 876–877 ZORA method for actinide cyclopentadienyl complexes, 1958 for actinyl oxyhalides, 1941–1942 for electronic structure calculation, 1907 ZPL. See Zero-phonon lines

AUTHOR INDEX Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440. Page numbers suffixed by t and f refer to Tables and Figures respectively.

Aaberg, M., 1921 Aaliti, A., 2877 Aarkrog, A., 704, 783, 3280 Aarts, J., 2333 Aas, W., 589, 606, 608, 611, 612, 614, 617, 618, 1426, 2593 Aase, S. B., 861, 1295 Aba, A., 180 Abaouz, A., 88, 91 Abazli, H., 511, 730, 735, 739, 745, 746, 748, 792, 2443, 2595 Abbott, D. T., 3017 Abdel Gawad, A. S., 176, 182, 184, 185 Abdel-Rahman, A., 181 Abdelras, A. A., 1513 Abdul-Hadi, A., 180 Abdullin, F. S., 1653, 1654, 1707, 1719, 1736, 1738 Abdullin, F. Sh., 14, 1398, 1400 Abe, J., 1010 Abe, M., 188, 226, 1292 Abelson, P. H., 4, 5, 699, 700, 717 Aberg, M., 545, 570, 596, 598, 600, 2532, 2533, 2555, 2556, 2583, 3101, 3119, 3128 Abernathy, D., 2237 Abeyta, C. L., 3031 Abney, K., 1173 Abney, K. D., 97, 117, 398, 475, 495, 861, 998, 1112, 1166, 2642, 2749, 2827, 2868, 2869, 3109, 3210 Aboukais, A., 76 Abou-Kais, A., 76 Abragam, A., 2226, 2228 Abraham, A., 3029 Abraham, B. M., 329, 332, 333, 1018, 1052, 1092, 1094, 1095, 1100, 1101, 2167 Abraham, D. P., 719, 721 Abraham, F., 298, 301 Abraham, J., 115 Abraham, M. M., 1368, 1472, 1602, 2042, 2047, 2053, 2058, 2059, 2061, 2062, 2075, 2226, 2238, 2259, 2261, 2262, 2263, 2265, 2266, 2268, 2269, 2272, 2292 Abrahams, E., 923, 964, 2344, 2347, 2355 Abrahams, S. C., 1360 Abram, U., 597

Abramina, E. V., 760 Abramov, A. A., 37 Abramowitz, S., 1968, 1971 Abrams, R., 3424 Abramychev, S. M., 1398 Abrao, A., 410 Abriata, J. P., 355, 356 Abrikosov, I. A., 928, 2355 Abu–Dari, K., 3416, 3419 Abuzwida, M. A., 3052, 3053 Ache, H. J., 227 Achenbach, W., 1881 Acker, F., 67, 71 Ackerman, D., 14 Ackerman, J. P., 2710, 2714, 2715, 2719, 2720 Ackermann, D., 1653, 1713, 1717 Ackermann, R. J., 60, 61, 63, 70, 75, 321, 322, 351, 352, 353, 355, 356, 362, 364, 365, 718, 724, 890, 891, 945, 949, 963, 1030, 1045, 1046, 1048, 1297, 1298, 1403, 1409, 1410, 1417, 2114, 2115, 2116, 2120, 2147, 2148, 2149, 2380, 2391 Acquista, N., 1968, 1971 Adachi, H., 99, 576, 577, 1935, 1936, 2165 Adachi, T., 355, 383 Adair, H. L., 1302 Adair, M. L., 1410, 1412, 1413 Adam, M., 2472, 2817 Adam, R., 2472, 2805 Adams, D. M., 93 Adams, F., 169, 170, 171 Adams, J., 1582, 1593, 1612 Adams, J. B., 949, 950 Adams, J. L., 185, 186, 815, 1447, 1684, 1693, 1699, 1705, 1711, 1716, 1718 Adams, J. M., 2642 Adams, M. D., 950, 1080, 1086 Adams, R. E., 406 Adams, S. R., 3017 Adamson, M. G., 1036, 1047, 1075, 2195 Adar, S., 1509 Addison, C. C., 370, 378 Addleman, R. S., 2679, 2681, 2682, 2683 Aderhold, C., 1323, 1455, 1515, 2254, 2264, 2472, 2826 Adi, M. B., 115

I-141

I-142

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Adler, P. H., 920, 927, 933 Adloff, J. P., 20, 25, 31, 988, 1663 Adnet, J. M., 1143, 1355 Adolphson, D. G., 83 Adrian, G., 792 Adrian, H. W. W., 2439 Adriano, D. C., 3288 Adrianov, M. A., 900, 902, 904, 906, 907, 908, 910, 911, 912, 913, 914 Aebersold, H. U., 1732 Aeppli, G., 2238, 2351 Aerts, P. J. C., 1905 Afonas’eva, T. V., 726, 745, 747, 748, 767, 768, 1175, 2434, 2436, 2442 Afonichkin, V. K., 2703, 2704 Afzal, D., 2472 Agakhanov, A. A., 261 Agapie, T., 2888 Agarande, M., 3062 Agarwal, H., 115 Agarwal, P., 407, 2239, 2359 Agarwal, R., 1635, 1642, 1643, 1645, 1646 Agarwal, R. K., 115 Agarwal, Y. K., 1738 Agnew, S. F., 1268 Agreiter, J., 1968 Agron, P. A., 528 Agruss, M. S., 163, 173, 174, 175 Aguilar, R., 3279, 3280, 3282, 3314 Ahilan, K., 407, 2239, 2359 Ahlheim, U., 2352 Ahlrichs, R., 1908, 1909 Ahmad, I., 26, 167, 168, 1447, 1504, 1516, 1582, 1736 Ahmad, M. F., 114 Ahmed, F. R., 2443 Ahmed, M., 2982, 3060 Ahonen, L., 3066 Ahrland, S., 209, 772, 774, 1555, 1687, 2565, 2578, 2579, 2580, 2582, 2585, 2587, 2589, 2600, 2607, 3346, 3347, 3360, 3361, 3386 Ahuja, R., 719, 720, 1300, 1301, 2371 Aikhler, V., 1664, 1703 Aisen, P., 3364, 3366, 3375, 3397, 3399 Aissi, C. F., 76 Aitken, C., 2916 Aitken, E. A., 387, 393, 395, 396, 1045, 1075 Aizenberg, I., 1625, 1633 Aizenberg, I. B., 2037, 2051, 2052 Aizenberg, M. I., 1541, 1612 Akabori, M., 718, 719, 1018, 1421, 2185, 2186, 2187, 2724, 2725 Akatsu, E., 1431 Akatsu, J., 716, 837, 1049, 1294, 1512, 2653 Akber, R. A., 42 Akella, J., 61, 1299, 1300, 1403, 1410, 1411, 1412, 2370

Akhachinskii, V. V., 906, 912 Akhachinskij, V. V., 67, 68, 69, 74, 100, 325, 326, 398, 400, 401, 402, 405, 406, 407, 2114, 2197, 2205, 2206, 2207, 2208, 2209 Akhtar, M. N., 2441 Akiba, K., 2759, 2760, 2762 Akie, H., 2693 Akimoto, I., 1019 Akimoto, Y., 1028, 1303, 1312, 1317, 2395, 2411 Akin, G. A., 490 Akiyama, K., 1445, 1484, 1696, 1718, 1735 Akopov, G. A., 788, 3034, 3039 Aksel’rud, L. G., 69, 72 Aksenova, N. M., 30 Al Mahamid, I., 1178, 1180, 3087, 3108, 3113, 3118 Al Rifai, S., 1352 Aladova, E. E., 3282 Alami Talbi, M., 102, 110 Alario-Franco, M. A., 113 Albering, J. H., 70, 73, 100, 2431 Alberman, K. B., 377, 393 Albers, R. C., 1788, 3089, 3103, 3108 Albinsson, Y., 119, 120, 121, 122, 123, 124, 129, 130, 3024, 3152 Albiol, T., 1019 Albrecht, A., 3014 Albrecht, E. D., 915, 1003, 1004, 1005, 1006 Albrecht-Schmitt, T., 1312, 1360 Albrecht-Schmitt, T. E., 253, 298, 299, 412, 555, 1173, 1531, 2256 Albridge, R. G., 164 Albright, D., 813, 814, 825, 1756, 1758, 1805 Alcock, C. B., 402, 421 Alcock, K., 342, 357, 358, 3171 Alcock, N. W., 108, 542, 549, 571, 583, 588, 1173, 1921, 2434, 2439, 2440, 2441, 2476, 2483, 2484, 2485, 2532, 2843, 2887, 3138 Al-Daher, A. G. M., 115 Aldred, A. T., 719, 721, 739, 742, 744, 745, 1304, 2238, 2261, 2262, 2362 Aldridge, T. L., 3346 Aldstadt, J. H., 3323 Alei, M., 1126 Aleklett, K., 1737, 1738 Aleksandrov, B. M., 1513 Aleksandruk, V. M., 787, 788, 1405, 1433, 2532, 3034 Alekseev, V. A., 179 Alekseeva, D. P., 756, 1175 Alekseeva, T. E., 1725 Alenchikova, I. F., 1101, 1102, 1106, 1107, 1108, 2426 Ale´onard, K. B., 281 Alessandrini, V. A., 2274 Alexander, C., 1760, 3223, 3224, 3225

Author Index

I-143

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Alexander, C. A., 364, 365, 393, 1021, 1045 Alexander, C. W., 1505, 1506, 1507 Alexander, E. C., Jr., 824 Alexander, I. C., 98 Alexander, W. R., 3070 Alexandratos, S., 1585 Alexandratos, S. D., 716, 852, 1293, 2642, 2643, 3283 Alexer, I. C., 98 Alexopoulos, C. M., 2432 Al-Far, R. H., 2443 Alfassi, Z. B., 3056, 3057 Alford, M. J., 2864 Alhassanieh, O., 180 Ali, M., 2153 Ali, S., 1352 Ali, S. A., 1428, 1552 Alibegoff, G., 431 Aling, P., 355 Al-Jowder, O., 545 Al-Kazzaz, A. M. S., 206, 207 Al-Kazzaz, Z. M. S., 82, 745, 746 Allain, M., 92 Allard, B., 1117, 1146, 1158, 1354, 1803, 1804, 1806, 1807, 1808, 1810, 2546, 2591 Allard, B. I., 132 Allard, G., 67 Allard, T., 3152, 3155, 3168 Allbutt, M., 1050, 1051, 1052 Allegre, C. J., 231, 3314 Allemspach, P., 428, 436, 440, 444, 451 Allen, A. L., 484 Allen, A. O., 3221 Allen, F. H., 2444 Allen, G. C., 340, 344, 350, 375, 376, 504, 1035, 1972, 3171 Allen, J. W., 100, 861, 1521 Allen, O. W., 314 Allen, P., 849, 1167, 3025, 3089, 3095, 3102, 3103, 3104, 3106, 3107, 3109, 3110, 3111, 3113, 3114, 3115, 3117, 3118, 3119, 3122, 3130, 3131, 3135, 3138, 3140, 3141, 3142, 3145, 3146, 3147, 3148, 3149, 3150, 3152, 3154, 3155, 3156, 3158, 3160, 3165, 3166, 3167, 3171 Allen, P. B., 63 Allen, P. G., 118, 270, 277, 287, 289, 301, 579, 585, 589, 602, 795, 849, 932, 967, 1112, 1166, 1167, 1327, 1338, 1363, 1368, 1369, 1370, 1921, 1923, 1926, 1947, 2530, 2531, 2532, 2568, 2576, 2580, 2583, 2812, 3369, 3385, 3388, 3390, 3391, 3394, 3417, 3423 Allen, R. E., 2044 Allen, R. P., 968 Allen, S., 593, 2256 Allen, S. J., 2275

Allen, T. H., 973, 974, 975, 976, 989, 990, 1026, 1027, 1035, 1040, 1041, 1042, 1798, 2136, 2141, 3109, 3177, 3202, 3205, 3206, 3208, 3209, 3210, 3211, 3214, 3216, 3217, 3218, 3219, 3220, 3221, 3222, 3223, 3224, 3225, 3227, 3228, 3229, 3230, 3231, 3232, 3235, 3236, 3237, 3243, 3244, 3245, 3247, 3249, 3250, 3251, 3252, 3253, 3256, 3257, 3259, 3260 Allison, M., 29 Alloy, H. P., 226 Allpress, J. G., 373, 374, 375, 376, 380, 549, 550, 555 Almasova, E. V., 1479 Almeida, M., 1304 Almond, P. M., 298, 299, 412, 1173, 2256 Al-Niaimi, N. S., 772, 773, 774 Alnot, M., 3046 Alonso, C. T., 6 Alonso, J. R., 6 Alonso, U., 3069 Alstad, J., 1665, 1666, 1695, 1702, 1717, 1735, 2662 Altarelli, M., 2236 Altmaier, M., 3103, 3104, 3129 Altman, P. L., 3357, 3358 Altzizaglau, T., 1293 Alvarado, J. A., 3327 Alvarado, J. S., 3280, 3327 Alvarez, L. W., 3316 Aly, H. F., 181, 184, 1449, 1476, 1477, 1478, 1513, 1551, 1585, 1606, 2662 Alzitzoglou, T., 1665 Amalraj, R. V., 2633 Amano, H., 3171 Amano, O., 855, 856 Amano, R., 1323, 1324, 1541 Amanowicz, M., 719, 720 Amato, L., 2756 Amayri, S., 3131, 3381, 3382 Ambartzumian, R. V., 3319 Amberger, H. D., 1952 Amberger, H.-D., 505, 2226, 2253, 2254 Amble, E., 1681 Amekraz, B., 120, 3054 Amelinckx, S., 343 American Society for Testing and Materials, 634, 3279, 3280, 3282, 3283, 3285, 3291, 3292, 3295, 3296, 3302, 3308, 3309, 3327, 3328 Ames, F., 789, 1296, 1403, 1875, 1876, 1877, 3044, 3047, 3048, 3320, 3321 Ames, R. L., 1141 Ami, N., 1049 Amirthalingam, V., 2393 Amis, E. S., 2532 Amme, M., 289

I-144

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Ammentorp-Schmidt, F., 207 Amonenko, V. M., 364 Amoretti, G., 2278, 2279, 2280, 2283, 2284, 2285, 2286, 2287, 2288, 2294 Amrhein, C., 270, 3166, 3174 Anan’ev, A. V., 793, 1352 Ananeva, L. A., 458 Anczkiewicz, R., 3047 Anderegg, G., 1177, 1178 Anderko, K., 325, 405, 408, 409 Anders, E., 636, 3306 Andersen, J. C., 1028, 1030 Andersen, O. K., 1459 Andersen, R. A., 116, 452, 1956, 1957, 1958, 2246, 2247, 2256, 2260, 2471, 2472, 2473, 2475, 2476, 2477, 2478, 2479, 2480, 2481, 2561, 2802, 2803, 2805, 2806, 2807, 2808, 2809, 2810, 2812, 2813, 2829, 2830, 2833, 2834, 2837, 2845, 2846, 2866, 2867, 2876, 2877, 2879, 2881, 2916, 2922, 2923 Anderson, A., 580, 582 Anderson, C. D., 963 Anderson, C. J., 2688, 2690 Anderson, D. M., 2912 Anderson, H. H., 841 Anderson, H. J., 343 Anderson, J. E., 2464 Anderson, J. S., 83, 344, 373, 374, 375, 377, 382, 383, 390, 393, 549, 550, 555, 1796, 3214 Anderson, J. W., 862, 870 Anderson, K. D., 2407 Anderson, M. R., 107 Anderson, O. K., 1300 Anderson, R. F., 3056 Anderson, R. W., 484 Andersson, C., 2757 Andersson, D. A., 1044 Andersson, J. E., 223 Andersson, K., 1909 Andersson, P. H., 2347 Andersson, P. S., 3288 Andersson, S. O., 2757 Andraka, B., 719, 720 Andrassy, M., 1662, 1709 Andre´, C., 2591 Andre, G., 402, 407 Andreetii, G. D., 2816 Andreetti, G. D., 103, 110, 2471, 2472 Andreev, A. M., 164 Andreev, A. V., 334, 335, 339, 2359, 2360 Andreev, V. I., 1326, 1329, 1331, 1416, 1429, 2584 Andreev, V. J., 1545, 1559, 2129, 2131 Andreichikov, B., 1398, 1421 Andreichikov, B. M., 1398, 1433 Andreichuk, N. N., 1144, 1145, 1146, 1338, 2531, 3101, 3106, 3111, 3113

Andres, H. P., 428, 440 Andres, K., 2360 Andresen, A. F., 66, 351 Andrew, J. F., 957, 1004 Andrew, K. L., 1730, 1731 Andrews, A. B., 2343, 2344, 2345 Andrews, H., 855 Andrews, H. C., 30, 32 Andrews, J. E., 1114, 1148, 1155, 1160, 1163, 2583 Andrews, L., 405, 576, 1918, 1919, 1969, 1971, 1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 2185, 2894 Andreyev, A. N., 6, 14, 1653, 1701 Andrieux, L., 398 Andruchow, W. J., 115 Angel, A., 225 Angelo, J. A., Jr., 817 Angelucci, O., 76 Angus, W., 3340, 3349, 3350, 3398, 3399 Anisimov, V. I., 929, 953 Ankudinov, A. L., 1112, 1991, 3087, 3089, 3108, 3113, 3117, 3118, 3123 Anonymous, 163, 2629, 2632, 2668, 2669, 2712, 2713, 2714, 2715, 2717, 2730, 2732 Anousis, I., 302, 3039 ANS, 1269 Ansara, I., 67, 68, 69, 74, 100, 325, 326, 398, 400, 401, 402, 405, 406, 407, 2114, 2197, 2205, 2206, 2207, 2208, 2209 Anselin, F., 1018, 1022 Ansell, H. G., 103, 113 Ansermet, S., 260, 285, 288 Ansoborlo, E., 3052, 3382, 3423 Anson, C. E., 545 Antalic, S., 14, 1653, 1713, 1717 Anthony, A. M., 353, 360 Antill, J. E., 319 Antonelli, D., 817 Antonini, G. M., 3163 Antonio, M. R., 291, 584, 730, 754, 764, 861, 1112, 1113, 1356, 1370, 1474, 1480, 1481, 1778, 1933, 2127, 2263, 2402, 2526, 2527, 2528, 2531, 2532, 2584, 3039, 3086, 3087, 3089, 3099, 3100, 3106, 3107, 3108, 3110, 3111, 3112, 3114, 3116, 3117, 3122, 3125, 3163, 3170, 3179, 3181 Antonoff, G. N., 163 Antsyshkina, A. S., 2439 Anwander, R., 2918 Anyun, Z., 1141 Aoi, M., 855, 856 Aoki, D., 412, 2352 Ao-Ling, G., 2912

Author Index

I-145

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Aoshima, A., 2760 Aoyagi, H., 758 Aoyagi, M., 1452, 1515 Aoyagi, N., 625 Apelblatt, A., 2132 Apeloig, Y., 2957 Apostolidis, C., 28, 43, 44, 102, 108, 223, 1143, 1168, 1409, 1410, 2250, 2255, 2469, 2470, 2471, 2472, 2474, 2475, 2476, 2477, 2478, 2479, 2484, 2486, 2488, 2752, 2808, 2814, 2815, 2816, 2819, 2827, 2829, 2852, 2882, 2885 Appel, H., 729, 792 Appelman, E. H., 728, 1064, 2527 Appleman, D. E., 259, 266, 282 Apps, M. J., 3057 Apraksin, I. A., 108 Apyagi, H., 753, 790, 791 Arai, T., 845 Arai, Y., 396, 717, 743, 1018, 1019, 1022, 2140, 2142, 2157, 2199, 2201, 2202, 2693, 2698, 2715, 2716, 2724 Arajs, S., 322 Aramburu, I., 78, 82 Arapaki, H., 222, 225 Arapaki-Strapelias, H., 185, 209, 215, 222 Arblaster, J. W., 34, 35 Arbman, E., 164 Arbode, Ph., 3068 Arbore, Ph., 3062 Archer, M. D., 3097 Archibong, E. F., 1018, 1976, 1989, 1994, 2149 Arden, I. W., 225 Arden, J. W., 3311 Ardisson, C., 170 Ardisson, G., 170, 1688, 1700, 1718, 3024 Ardois, C., 289 Arduini, A., 2655 Arduini, A. L., 2819 Arendt, J., 560 Arfken, G., 1913 Arimura, T., 2560, 2590 Arisaka, M., 1409 Arita, K., 78 Arita, Y., 2208, 2211 Ariyaratne, K. A. N. S., 2479, 2484 Arkhipov, V. A., 2140 Arkhipova, N. F., 1725 Arko, A. J., 412, 921, 964, 1056, 2307, 2334, 2335, 2336, 2338, 2339, 2341, 2343, 2344, 2345, 2346, 2347, 2350 Arliguie, T., 1960, 1962, 2246, 2479, 2480, 2488, 2491, 2837, 2841, 2856, 2857, 2861, 2862, 2891, 2892 Armagan, N., 2451 Armbruster, P., 6, 14, 164, 1653, 1660, 1701, 1713, 1735, 1737, 1738 Armbruster, T., 260, 285, 288

Armijo, V. M., 3312, 3314 Armstrong, D. E., 1291 Arnaudet, L., 2472, 2820 Arnaud-Neu, F., 2655 Arney, D. S. J., 1958, 2479, 2832, 2833, 2835, 2845, 2847, 2848, 2849, 2914, 2916, 2921 Arnold, E. D., 2734 Arnold, G. P., 67, 69, 71, 98, 2407, 2408, 2411 Arnold, J. S., 3353, 3403, 3404, 3405, 3406, 3407 Arnold, P. L., 1966, 1967, 2859, 2861, 2888 Arnold, T., 3029, 3152, 3165, 3166, 3167 Arnold, Z., 334, 335 Arnoux, M., 24, 31 Arons, R. R., 719, 720 Aronson, S., 97, 100, 353, 360, 368, 369, 390, 394, 397 Arora, K., 115 Arredondo, V. M., 2984, 2986, 2990 Arrott, A., 2273, 2275 Arsalane, S., 102, 110, 1172, 2431 Arslanov, K. A., 3014 Arthur, E. D., 1811 Artisyuk, V., 1398 Artlett, R. J., 1938 Artna-Cohen, A., 166 Artyukhin, P. I., 1117, 1118, 1128 Arutyunyan, E. G., 102, 105, 2434, 2439 Asai, M., 1266, 1267, 1445, 1450, 1484, 1696, 1699, 1700, 1710, 1718, 1735 Asakara, T., 1294, 1295 Asakura, T., 711, 1272, 1273, 2757 Asami, N., 366 Asano, H., 407 Asano, M., 68 Asano, Y., 2633 Asanuma, N., 852 Asao, N., 2953, 2969 Asaro, F., 1582 Asch, L., 719, 720 Asfari, Z., 2456, 2457, 2458, 2459 Ashby, E. C., 2760 Ashcroft, N. E., 2308 Ashley, K. R., 2642 Ashurov, Z. K., 2441 Aslan, A. N., 69, 72 Aslan, H., 2472, 2817, 2818 Asling, C. W., 3341, 3342, 3344, 3353 Asling, G. W., 3387 Asmerom, Y., 3313 Aso, N., 2239, 2347, 2352 Asprey, L. B., 79, 191, 193, 201, 202, 203, 222, 457, 463, 502, 506, 507, 519, 520, 529, 530, 536, 732, 734, 763, 765, 841, 1049, 1082, 1084, 1095, 1097, 1107, 1117, 1118, 1265, 1291, 1295, 1297, 1302, 1312, 1314, 1315, 1319, 1322, 1323,

I-146

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 1325, 1326, 1329, 1331, 1333, 1356, 1357, 1358, 1360, 1365, 1366, 1367, 1404, 1415, 1416, 1417, 1418, 1419, 1429, 1458, 1467, 1475, 1513, 1515, 1519, 1520, 1529, 1604, 1935, 1968, 2077, 2165, 2232, 2350, 2388, 2395, 2397, 2415, 2416, 2417, 2418, 2420, 2426, 2427 Assefa, Z., 1453, 1467, 1531, 1532, 1554, 1601, 1602, 1603 Assinder, D. J., 3017, 3295, 3296 Astafurova, L. N., 1170, 2434 Astheimer, L., 220 Aston, F. W., 3309 Astro¨m, B., 1636 Aten, A. H. W., Jr., 1547 Atencio, D., 260, 264, 293 Atherton, D. A., 3370, 3373 Atherton, D. R., 1507, 1579, 3343, 3349, 3350, 3351, 3353, 3355, 3356, 3358, 3360, 3362, 3364, 3365, 3366, 3370, 3375, 3377, 3378, 3379, 3381, 3382, 3385, 3396, 3398, 3399, 3403, 3404, 3405, 3414, 3415, 3416, 3420 Atherton, N. J., 190, 226 Atlas, L. M., 1031 Atoji, M., 537, 2426 Attenkofer, K., 3178 Atterling, H., 1636 Attrep, M., Jr., 3279, 3280, 3282, 3314 Atwood, J. L., 116, 2240, 2452, 2472, 2473, 2480, 2484, 2803, 2804, 2812, 2815, 2816, 2829, 2844, 2845, 2912, 2924 Au, C. T., 76 Aubert, P., 1433 Aubin, L., 1629 Auchapt, P., 2731 Audi, G., 815, 817, 1446 Auerman, L. N., 221, 1113, 1473, 1515, 1547, 1548, 1607, 1629, 1636, 2525 Auerswald, K., 3017 Auge, R. G., 869 Augoustinik, A. I., 195 Augustson, J. H., 2662 Aukrust, E., 360 Aupais, J., 134, 785, 1405, 1432, 1433 Aur, S., 3107 Aurov, N. A., 431, 437, 450, 451, 454 Auskern, A. B., 97 Austin, A. E., 1006, 1007 Autschbach, J., 1666 Auzel, F., 483, 486, 491, 2039, 2067 Avdeef, A., 116, 1188, 1943, 1944, 2486, 2488, 2852 Avens, L. R., 439, 454, 455, 737, 752, 1182, 1183, 1184, 1185, 1186, 1190, 2484, 2487, 2488, 2802, 2813, 2832, 2858, 2867, 2876

Averbach, B. B., 828 Averill, B. A., 3117 Averill, F. W., 1682 Avignant, D., 85, 86, 87, 88, 90, 91, 457, 458, 468, 1108 Avisimova, N. Yu., 2439 Avivi, E., 905 Avogadro, A., 373, 1803 Avril, R., 1863, 1873, 1874, 1875 Awad, A. M., 2580 Awasthi, S. K., 728, 729, 1058, 1059, 1060, 1061 Awasthi, S. P., 2580 Awwad, N., 3409 Awwal, M. A., 2736 Axe, J. D., 203, 2065, 2114, 2241, 2243 Axelrod, D., 3401, 3424 Axelrod, D. J., 3341, 3348, 3356, 3387, 3405 Axler, K. M., 1109 Ayache, C., 719, 720 Aymonino, P. J., 110 Ayoub, E. J., 184 Ayres, J. A., 3246 Ayres, L., 3345, 3354, 3355, 3371, 3378, 3384 Aziz, A., 41, 1352, 1426, 1431 Baaden, M., 2685 Baba, N., 3318 Babad, H., 2760 Babaev, A. S., 787, 788, 1405, 1433, 3034 Babain, V. A., 856, 2682, 2684, 2685, 2739 Babauer, A. S., 2532 Babcock, B. R., 866, 869, 870 Babelot, J. F., 366, 367 Babikov, L. G., 2715 Babrova, V. N., 1320 Babu, C. S., 3113 Babu, R., 1076, 2205, 2206 Babu, Y., 1175 Baca, J., 2655 Bach, M. E., 268 Bachelet, M., 179 Bacher, W., 421, 423, 424, 425, 441, 446, 447, 457, 458, 460, 461, 462, 463, 464, 465, 466, 467, 469, 481, 484, 485, 486, 487, 489, 501, 502, 505, 506, 507, 517, 518, 520, 528, 530, 533, 534, 535, 536, 537, 538, 556, 557, 560, 561, 562, 563, 566 Backe, A., 1840, 1877, 1884 Backe, H., 33, 1879, 1880, 1881, 1882, 1883, 1884 Backer, W., 1352 Baclet, N., 886, 887, 930, 932, 933, 954, 956 Bacmann, J. J., 367 Bacmann, M., 386 Bacon, G. E., 2232 Bacon, W. E., 101 Badaev, Yu. V., 112

Author Index

I-147

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Bader, S. D., 323, 324, 1894, 2315, 2355 Badheka, L. P., 1282, 1285, 1294, 2657, 2658, 2659, 2738, 2743, 2744, 2745, 2749, 2757 Bae, C., 1723, 1728 Baechler, S., 3042, 3043 Baenziger, N. C., 70, 339, 399, 407 Baer, Y., 421, 2360 Baerends, E. J., 1200, 1201, 1202, 1203, 1666, 1667, 1668, 1907, 1910, 1916, 1943, 1944, 1947, 1948, 1951, 1972, 2089, 2253 Baernighausen, H., 509 Baes, C. E., 3158 Baes, C. F., 119, 120, 121, 1148, 1149, 1155, 1686, 1687, 1701, 1718, 1778 Baes, C. F., Jr., 119, 120, 121, 123, 124, 313, 598, 599, 2133, 2134, 2135, 2192, 2548, 2549, 2550, 2553, 2700, 2701 Baetsle´, L. H., 20, 30, 31, 32, 33, 35, 42, 43, 2728 Baeyens, B., 3152, 3156, 3157 Bagawde, S. V., 772, 773, 774, 1168 Baglan, N., 109, 126, 128, 129 Bagliano, G., 3061 Baglin, C. M., 817, 1626, 1633, 1639, 1644 Bagnall, K. W., 19, 81, 82, 94, 108, 115, 116, 179, 188, 201, 203, 204, 205, 206, 207, 208, 213, 215, 216, 221, 222, 224, 421, 473, 487, 494, 497, 498, 499, 510, 522, 524, 543, 565, 726, 727, 734, 735, 736, 738, 739, 745, 746, 748, 1077, 1184, 1190, 1191, 1312, 1315, 1323, 1398, 1417, 2424, 2426, 2434, 2435, 2469, 2472, 2475, 2476, 2483, 2484, 2485, 2817, 2826, 2843, 2880, 2883, 2885, 3250 Baiardo, J. P., 942 Baibuz, V. F., 2114, 2148, 2149, 2185 Baı¨chi, M., 351, 352, 365 Baidron, M., 195 Bailey, D. M., 78, 82 Bailey, E., 3102, 3120, 3121, 3142, 3143 Bailey, M. R., 3424 Bailey, S. M., 34 Bailly, T., 2591, 3419, 3421, 3423 Baily, H., 1071, 1073, 1074, 1075 Baily, W. E., 1045, 1075 Baines, C., 2351 Bair, W. J., 3340, 3352, 3386, 3424 Baird, C. P., 626, 629 Bairiot, H., 1071 Baisden, P. A., 1114, 1148, 1155, 1160, 1163, 1352, 1605, 1629, 1633, 1636, 1664, 1684, 1693, 1694, 1706, 1716, 2525, 2526, 2529, 2583, 2589 Baisden, T. A., 1629, 1633 Bajgur, C. S., 2919

Bajic, S., 3036 Bajo, S., 1806, 3024, 3029, 3030, 3283, 3293, 3296 Bajt, S., 270, 3039, 3172 Bakac, A., 595, 619, 620, 630 Bakakin, V. V., 458 Bakel, A. J., 279, 861 Baker, E. C., 2471, 2472, 2819, 2820 Baker, F., 1333 Baker, F. B., 606, 1129, 1131, 1139, 2594, 2599 Baker, J. D., 1278, 2653 Baker, M. McD., 3242 Baker, R. D., 319, 866 Baker, T. A., 1966, 1967, 2245, 2859, 2861 Bakiev, S. A., 1507 Bakker, E., 298 Bakker, K., 2139, 2142 Baklanova, P. F., 1164 Balakayeva, T. A., 108, 109, 110 Balakrishnan, P. V., 1175 Balarama Krishna, M. V., 708, 712, 713, 1294, 2743, 2745, 2757, 2759 Balashov, N. V., 1398 Balasubramanian, K., 1898, 1900, 1973, 1974 Balasubramanian, R., 1074 Balatsky, A. V., 2347 Balcazar Pinal, J. L., 93 Baldridge, K. K., 1908 Baldwin, C., 3409 Baldwin, C. E., 864, 875 Baldwin, D., 3036 Baldwin, N. L., 67, 2407 Baldwin, W. H., 747, 1323, 1324, 1361, 2439, 2527, 3125 Balescu, S., 3016 Ball, J. R., 2642 Ball, R. G., 2883 Ballatori, N., 3396, 3397 Ballentine, C. J., 639, 3327 Ballestra, S., 704, 783 Ballhausen, C. J., 376, 377, 378, 382, 501, 513, 526, 528, 2243 Ballou, J. E., 3340, 3352, 3386, 3424 Ballou, N. E., 180, 187 Ballou, R., 2359 Balo, P. A., 1505, 1828 Balta, E. Ya., 2439 Baltensperger, U., 1704, 3030, 3031 Baluka, M., 731, 732, 2420 Balzani, V., 629 Bamberger, C., 1312, 2701 Bamberger, C. E., 744, 1171, 2430, 2431, 2432 Ban, Z., 69, 70, 73 Banar, J. C., 3133 Banaszak, J. E., 1813, 1818, 2668, 3181 Band, W. D., 1033 Bandoli, G., 548, 2439, 2440, 2441 Banerjea, A., 2364

I-148

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Banerji, A., 713 Banfield, J. F., 3179, 3180, 3181 Banic, G. M., 821 Banick, C. J., 1398 Banik, G., 70 Banks, C. V., 111 Banks, R., 731, 732, 745, 2420 Banks, R. H., 208, 1187, 1188, 1951, 2261, 2405, 2852 Bannerji, A., 1281, 1282, 1294, 2668, 2738, 2743, 2744, 2745, 2747, 2748, 2749, 2757, 2759 Bannister, M. J., 352, 353, 357, 358 Bannyh, V. I., 3067 Bansal, B. M., 191, 193, 1416 Bansal, B. M. L., 2585 Ba´nyai, I., 596, 608, 609, 612, 613, 614, 1166 Bao, B., 1285 Bao, B.-R., 1285 Baptiste, Ph. J., 396 Baracco, L., 2443 Barackic, L., 87, 92 Baraduc, L., 459 Barak, J., 335 Baran, E. J., 110 Barandiara´n, Z., 442, 1895, 1896, 1897, 1908, 1930, 2037 Baranger, A. M., 2847, 2933, 2986 Baraniak, L., 3029, 3102, 3138, 3140, 3141, 3142, 3145, 3147, 3148, 3149, 3150 Baranov, A. A., 164, 166, 1479, 1480, 1481, 1483, 2126 Baranov, A. Yu., 1466 Baranov, S. M., 711, 712, 760, 761, 1142, 1143, 2757 Barash, Y. B., 335 Barbanel, Y. A., 1365, 1369 Barbanel, Yu. A., 1404, 1405 Barbano, P. G., 1284 Barbe, B., 904 Barber, D. W., 1426, 2673 Barber, R. C., 13, 1660 Barbieri, G. A., 112 Barboso, S., 2655 Barci, V., 1688, 1700, 1718 Barci-Funel, G., 3024 Barclay, G. A., 2430 Bard, A. J., 371, 3126 Bardeen, J., 62, 2350, 2351 Bardelle, P., 1018 Bardin, N., 608, 609, 2533, 2603, 3102, 3112 Barefield II, J. E., 1088, 1090, 2085 Barendregt, F., 164, 186 Bargar, J. R., 3165, 3167, 3168, 3170 Barin, I., 2160 Baring, A. M., 1527 Barinova, A. V., 268, 298 Barkatt, A., 39

Barker, M. G., 98 Barketov, E. S., 1553 Barlow, S., 593, 2256 Barmore, W. L., 971, 972 Barnanov, A. A., 1545 Barnard, R., 439, 445, 449, 452, 455, 585, 593 Barnes, A. C., 2603 Barnes, C. E., 2688, 2691, 3127, 3139, 3307 Barnes, E., 319 Barnes, R. F., 1455, 1474, 1509, 1543, 1582, 1604 Barnett, G. A., 224 Barnett, M. K., 224, 225 Barnett, T. B., 3384 Barney, G. S., 1127, 1140, 1294, 2749 Barnhart, D. M., 2400, 2484, 2486 Ba¨rnighausen, H., 1534 Baron, P., 1285, 2756, 2761, 2762 Barone, V., 1938 Barr, D. W., 704 Barr, M. E., 849, 2749, 3035, 3036 Barraclough, C. G., 373, 383 Barrans, R. E., Jr., 2676 Barre, M., 104, 105 Barrero Moreno, J., 3062 Barrero Moreno, J. M., 789 Barrett, C. S., 320 Barrett, N. T., 3163 Barrett, S. A., 2153 Barros, M. T., 2852 Barry, J. A., 197 Barry, J. P., 2916 Barsukova, K. V., 1448, 1449 Bart, G., 3055 Bartashevich, M. I., 334, 335, 339 Barth, H., 822, 1705, 3014, 3296 Barthe, M. F., 289 Barthelemy, P., 1327 Barthelet, K., 126 Bartlett, N., 542 Bartlett, R. J., 1194, 1902 Bartoli, F. J., 2044 Barton, C. J., 459, 1104 Barton, P. G., 1816 Bartos, B., 32 Bartram, S., 65 Bartram, S. F., 376, 378, 387, 389, 393, 395 Bartsch, R. A., 2749 Bartscher, W., 65, 66, 334, 335, 396, 722, 723, 724, 977, 989, 990, 992, 993, 994, 995, 2403, 2404 Bashlykov, S. N., 906, 912 Basile, L. J., 1369, 1923, 1931, 2655, 2739, 3035 Baskaran, M., 3016, 3288 Baskerville, C., 76, 80, 105 Baskes, M. I., 928

Author Index

I-149

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Baskin, Y., 76, 99, 113, 412, 2432, 2441 Basnakova, G., 297, 717 Basov, D. N., 100 Basset, J. M., 3002, 3003 Bassindale, A. R., 2985 Bassner, S. L., 1983 Bastein, P., 542 Bastin, G., 164 Bastin-Scoffier, G., 26 Baston, G. M. N., 854 Bastug, T., 1671, 1676, 1680, 1681, 1682, 1683, 1684, 1689, 1705, 1706, 1712, 1716 Basu, P., 1447 Bates, J. K., 270, 272, 273, 274, 275, 292, 1806, 3017, 3052, 3171, 3302 Bates, J. L., 352, 369, 1303, 1312 Bathelier, A., 1275 Bathellier, A., 2731 Bathmann, U., 231 Batista, E. R., 1936, 1937, 1938, 1941 Batley, G. E., 521 Batlle, J. V., 3016, 3023 Batscher, W., 2143, 2188, 2189 Battioni, J. P., 3117 Battiston, G. A., 2441 Battles, J. E., 373, 1046, 1074, 2692, 2695, 2696, 2698, 2723 Baturin, N. A., 747, 748, 749, 1181, 2434, 2436, 2439, 2442, 2531, 2595 Bauche, J., 860, 1847 Bauche-Arnoult, C., 1847 Baud, G., 377 Baudin, C., 2484 Baudin, G., 1285, 2756 Baudry, D., 2484, 2488, 2490, 2491, 2843, 2856, 2859, 2866, 2869, 2870, 2877, 2889, 2890 Bauer, A., 3114 Bauer, A. A., 325, 408, 410 Bauer, C. B., 2666 Bauer, D. P., 2851 Bauer, E. D., 100, 968, 2353 Bauer, R. S., 1521 Baugh, D. W., 493, 494 Baum, R.-R., 1882, 1884 Baumann, J., 2351 Baumbach, H. L., 988, 1079 Baumga¨rtner, F., 117, 208, 382, 730, 751, 763, 766, 1093, 1190, 1323, 1324, 1363, 1423, 1800, 2240, 2244, 2254, 2470, 2472, 2732, 2801, 2803, 2809, 2814, 2815 Bauminger, E. R., 862 Bauri, A. K., 713, 1281, 1294, 2743, 2745, 2747, 2748, 2759 Bauschlicher, C. W., Jr., 1969 Bawson, J. K., 3171 Baxter, D. W., 3341

Baxter, M. S., 705, 706, 783, 3017, 3031, 3032, 3056, 3059, 3062, 3072, 3106 Bayat, I., 1352, 1552 Baybarz, R. D., 34, 35, 38, 118, 191, 1268, 1292, 1303, 1312, 1313, 1314, 1315, 1320, 1323, 1325, 1328, 1329, 1352, 1358, 1360, 1365, 1400, 1401, 1402, 1403, 1410, 1412, 1413, 1415, 1418, 1423, 1424, 1446, 1449, 1450, 1454, 1457, 1458, 1459, 1460, 1463, 1464, 1466, 1467, 1473, 1474, 1475, 1478, 1479, 1480, 1481, 1482, 1509, 1510, 1513, 1515, 1519, 1520, 1522, 1526, 1528, 1529, 1530, 1532, 1533, 1534, 1536, 1541, 1546, 1547, 1548, 1551, 1552, 1555, 1557, 1584, 1585, 1590, 1591, 1592, 1593, 1596, 1597, 1598, 1599, 1604, 1607, 1629, 2077, 2232, 2264, 2388, 2389, 2397, 2398, 2399, 2415, 2416, 2417, 2418, 2434, 2436, 2542, 2641, 2671, 2758 Bayliss, P., 278 Bayoglu, A. S., 367, 1044, 1045 Bazan, C., 412 Bazhanov, V. I., 2177 Bazin, D., 932, 933 Beach, L., 1507 Beall, G. W., 1605 Beals, R. J., 303, 391, 393, 395 Beamer, J. L., 1507 Bean, A., 1174, 1360 Bean, A. C., 555, 1173, 1312, 1360 Bearden, J. A., 60, 190, 859, 1296, 1370 Beasley, M. L., 1312, 1313, 1421 Beasley, T., 3063 Beasley, T. M., 3280 Beattie, I. R., 1968 Beaucaire, C., 3152, 3155, 3168 Beauchamp, J. L., 2924, 2934 Beaudry, B. J., 412 Beaumont, A. J., 837, 870, 1100 Beauvais, R. A., 852 Beauvy, M., 724, 997, 998 Becerril-Vilchis, A., 3023 Bechara, R., 76 Bechthold, H.-C., 2452 Beck, H. P., 75, 78, 84, 89, 93, 94, 96, 413, 414, 415, 479, 2413 Beck, K. M., 291, 3160, 3161, 3164 Beck, M. T., 590, 605, 2564 Beck, O. F., 206, 208 Becke, A. D., 1671, 1903, 1904 Becker, E. W., 557 Becker, J. D., 2347 Becker, J. S., 3069, 3310, 3311 Becker, S., 1735, 3062 Beckmann, W., 20 Becquerel, A. H., 2433

I-150

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Becquerel, H., 254 Becraft, K. A., 1178, 1180 Beddoes, R. L., 2440 Bedell, K. S., 2344 Bedere, S., 892 Bednarcyk, J., 725 Bednarczyk, E., 343, 1033, 1034 Beeckman, W., 2490 Beene, J. R., 1880, 1882 Beer, P. D., 2457 Beetham, C., 162 Beetham, S. A., 864, 2147, 2723 Beets, A. L., 1507 Begemann, F., 3306 Begg, B. D., 279, 280, 861, 932, 1041, 1043, 1112, 1154, 1155, 1166, 1798, 3109, 3210 Begun, G. M., 744, 757, 781, 1116, 1133, 1148, 1155, 1315, 1356, 1369, 1455, 1465, 1470, 1471, 2430, 2431, 2432, 2583, 2594, 3035 Behera, B. R., 1447 Beheshti, A., 2883 Behesti, A., 115, 116 Behets, M., 2044 Behrens, E., 2734 Behrens, U., 2875 Beintema, C. D., 370 Beirakhov, A. G., 2441, 2442 Beitscher, S., 973 Beitz, J., 1129 Beitz, J. V., 1352, 1354, 1368, 1369, 1423, 1454, 1455, 1474, 1475, 1544, 1605, 2013, 2030, 2032, 2042, 2047, 2062, 2064, 2075, 2085, 2090, 2091, 2093, 2094, 2095, 2096, 2098, 2099, 2101, 2103, 2265, 2534, 2536, 2562, 2563, 2572, 2589, 2590, 2675, 2691, 3034, 3037, 3043, 3044 Beja, A. M., 2439 Bekk, K., 1873 Belbeoch, B., 347, 353 Belbeoch, P. B., 2392 Belenkll, B. G., 1507 Belford, R. L., 629 Belkalem, B., 2464, 2465, 2466 Bell, J. R., 2701 Bell, J. T., 380, 619, 1132, 1366, 2080, 2580 Bell, M. J., 1270, 2702 Bell, W. A., 821 Bellamy, R. G., 303 Belle, J., 339, 340, 360, 367, 370 Beller, M., 2982 Bellido, L. F., 3022 Belling, T., 1906 Belloni, L., 2657 Belnet, F., 2649 Belomestnykh, V. I., 566, 2452

Belov, A. N., 2147 Belov, K. P., 2359 Belov, V. Z., 1628, 1634, 1645, 1663, 1664, 1690, 1703 Belova, L. N., 259 Belozerov, A. V., 1654, 1719, 1720, 1738 Belt, V. F., 3327 Belyaev, Y. I., 724, 726, 727, 770 Belyaev, Yu. I., 2136 Belyaeva, Z. D., 1821 Belyakova, Z. V., 108 Belyatskii, A. F., 31 Belyayev, Y. A., 3372, 3387 Bemis, C. E., 1504, 1516, 1583, 1590 Bemis, C. E., Jr., 1452, 1626, 1627, 1637, 1638, 1639, 1644, 1659, 1880, 1882 Bemis, G., 3156 Ben Osman, Z., 1845 Ben Salem, A., 96, 415 Be´nard, P., 103, 109, 110, 2431, 2432 Be´nard-Rocherulle´, P., 472, 477, 2432 Bencheikh-Latmani, R., 3165, 3168 Bendall, P. J., 470, 471 Bender, C. A., 1873 Bender, K. P., 841, 843 Bender, M., 1736 Benedict, G. E., 2704, 2730 Benedict, U., 100, 192, 409, 421, 725, 739, 740, 741, 742, 743, 1030, 1070, 1071, 1073, 1299, 1300, 1304, 1312, 1313, 1315, 1316, 1317, 1318, 1411, 1412, 1415, 1421, 1458, 1459, 1462, 1520, 1521, 1522, 1789, 2315, 2370, 2371, 2384, 2386, 2387, 2407, 2411 Benedict, V., 194 Benedik, L., 3057 Benerjee, S., 3307 Benerji, R., 1280 Benes, P., 1766 Benesovsky, F., 69, 72 Benetollo, F., 548, 2439, 2440, 2441, 2442, 2443, 2472, 2473, 2475, 2483, 2484, 2491, 2817, 2818, 2831 Benford, G., 2728 Benhamou, A., 3220 Benjamin, B. M., 116, 2815 Benjamin, T. M., 231 Benke, R. R., 3027 Benker, D. E., 1408, 1451, 1509, 1584, 2633 Benn, R., 2837, 2841 Benner, G., 78, 79 Bennet, D. A., 2583 Bennett, B. I., 962 Bennett, D. A., 1114, 1148, 1155, 1160, 1163, 1447, 1635, 1642, 1643, 1645, 1646, 1662, 1703, 1704 Bennett, D. R., 1811 Bennett, G. A., 2710

Author Index

I-151

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Bennett, R. L., 2889 Benning, M. M., 2451, 2452, 2453 Benninger, l. K., 3160 Benny, J. A., 186, 199 Benoit, G., 3016 Benson, D. A., 366 Bensted, J. P. M., 3396 Bentz, P. O., 2966 Benz, R., 69, 71, 97, 98, 99, 100, 465, 466, 1094, 1098, 1104, 1105, 1106, 1107, 1108, 1109, 2411, 2709, 2713 Benzoubir, S., 3062 Ber, N. H., 42, 43 Beraud, J. P., 3220 Berberich, H., 2984 Bercaw, J. E., 2924 Berdinova, N. M., 3067 Berdonosov, S. S., 1636 Bereznikova, I. A., 372, 373, 374, 375, 376, 393 Berg, J. M., 270, 301, 849, 851, 1139, 1141, 1161, 1167, 2687, 3109, 3171 Berger, H., 1507 Berger, M., 423, 445, 2257, 2258 Berger, P., 1049, 1329 Berger, R., 740, 742, 1085, 1086, 1480, 1481 Bergman, A. G., 80, 86, 87, 90, 91 Bergman, G. A., 2114, 2148, 2149, 2185 Bergman, R. G., 2847, 2880, 2933, 2986 Bergsma, J., 66 Bergstresser, K. S., 1131 Berkhout, F., 1756, 1758, 1805 Berlanga, C., 724 Berlepsch, P., 260, 285, 288 Berlincourt, T. G., 324 Berliner, R. W., 3384 Berlureau, T., 2360 Berman, L. E., 2281, 2282 Berman, R. M., 390, 391 Bermudez, J., 2442 Bernard, G., 3037, 3046 Bernard, H., 1018, 1019, 1071, 1073, 1074, 1075 Bernard, J., 3023, 3067 Bernard, J. E., 928 Bernard, L., 81 Bernard, S. R., 3346, 3351, 3372, 3375, 3376 Bernardinelli, R. J., 257 Bernardo, P. D., 778, 779, 3142, 3143 Berndt, A. F., 907, 912, 915 Berndt, U., 384, 389, 391, 393, 395, 423, 445, 1065, 1066, 1303, 1312, 1313 Berne, A., 1364 Bernhard, D., 626 Bernhard, G., 1923, 2583, 3044, 3069, 3102, 3106, 3107, 3111, 3112, 3122, 3131, 3139, 3140, 3142, 3143, 3144, 3145, 3147, 3148, 3149, 3150, 3152, 3154,

3155, 3160, 3161, 3165, 3166, 3167, 3179, 3181, 3182, 3381, 3382 Bernhardt, H. A., 521 Bernhoeft, N., 2234, 2239, 2285, 2286, 2287, 2292, 2352 Bernkopf, M. F., 1340, 2592 Bernstein, E. R., 337, 2226, 2251, 2261, 2404 Bernstein, H., 927 Bernstein, J. L., 1360 Berreth, J. R., 167, 169, 188, 195, 230 Berry, D. H., 2966 Berry, J. A., 485, 518, 520, 731, 732, 3050, 3057, 3060, 3062, 3064 Berry, J. P., 3052 Berry, J. W., 869, 1297 Berryhill, S. R., 2487, 2488, 2489, 2851, 2852 Bersillon, O., 817 Berstein, A. D., 817 Bersuder, L., 859 Bertagnolli, H., 3087 Bertaut, F., 67, 71, 113 Bertha, E. I., 1354 Berthault, P., 2458 Berthet, J. C., 576, 582, 583, 2246, 2473, 2480, 2484, 2488, 2806, 2808, 2812, 2818, 2819, 2822, 2824, 2830, 2847, 2856, 2857, 2858, 2866, 2912, 2922, 2923, 2938, 2940, 2943, 2944, 2950, 2975, 2976, 2979, 3101, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118 Berthold, H. J., 407, 410, 435, 452 Berthon, C., 1168, 2657 Berthon, L., 1285, 2657, 2658 Berthoud, T., 1114 Bertino, J. P., 319 Bertozzi, G., 2633 Bertrand, J., 265 Bertrand, P. A., 1160, 1166, 2726, 3287 Bertsch, P. M., 270, 861, 3039, 3095, 3172, 3174, 3175, 3176, 3177, 3288 Berzelius, J. J., 52, 60, 61, 63, 79, 95, 108 Berznikova, N. A., 373, 375, 376 Besancon, P., 1055 Bescraft, K. A., 3025 Beshouri, S. M., 1956, 2256, 2477, 2480, 2482, 2483, 2803, 2806, 2807, 2812, 2813, 2829, 2830 Besmann, T. M., 361, 1047, 2141, 2143, 2145, 2151 Besse, J. P., 377 Bessnova, A. A., 726, 748, 770, 1170, 1175, 1181, 1321 Besson, J., 331 Bessonov, A. A., 1931, 2434, 2442, 2531, 2532, 2595, 3111, 3112, 3113, 3122, 3123 Betchel, T. B., 2696 Bethe, H., 1911 Bettella, F., 2585

I-152

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Betti, M., 789, 3068, 3070 Bettinelli, M., 2100 Bettonville, S., 2489, 2490, 2816, 2817, 2818, 2822, 2827 Betts, J., 942, 944, 945, 948, 949, 950 Betts, J. B., 2315, 2347, 2355 Betty, M., 3032 Betz, T., 729, 1061, 1064 Beuchle, G., 3066 Beuthe, H., 226 Beutler, E., 3358, 3364, 3397, 3398, 3399 Bevan, D. J. M., 345, 347, 354 Beveridge, T. J., 3179 Bevilacqua, A. M., 855 Bevz, A. S., 545, 546 Beyerlein, R. A., 64, 66 Bezjak, A., 2439, 2444 Beznosikova, A. V., 907, 909, 911, 912 Bhandari, A. M., 206, 208 Bhanushali, R. D., 1271 Bharadwaj, P. K., 540, 566, 2441 Bharadwaj, S. R., 2153 Bhat, I. S., 782, 786 Bhatki, K. S., 25, 31 Bhattacharyya, M. H., 3345, 3354, 3355, 3371, 3378, 3384, 3413 Bhattacharyya, P. K., 1555 Bhide, M. K., 1175 Bhilare, N. G., 3035 Bibler, N. E., 1419, 1422, 1433 Bichel, M., 1293 Bickel, M., 729, 730, 792, 1293, 2240, 2244, 2245, 2261, 3024, 3059, 3060 Bidoglio, G., 769, 774, 1159, 1314, 1328, 1329, 1330, 1338, 1339, 1341, 1354, 1355, 1803, 2538, 2546, 2582, 3037 Bidoglio, G. R., 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2129, 2137, 2143, 2144, 2154, 2155, 2159, 2165, 2171, 2173, 2174, 2175, 2182, 2186, 2187, 2194 Bidwell, R. M., 862, 897 Biel, T. J., 329 Biennewies, M., 492 Bier, D., 1828 Bierlein, T. K., 961 Bierman, S. R., 1268 Bigelow, J., 1401 Bigelow, J. E., 1271, 1275, 1402, 1445, 1448, 1449, 1450, 1509, 1510, 1584, 1585, 2636 Biggers, R. E., 1132 Biggs, F., 1516 Bigot, S., 131 Bihan, T. L., 739 Bilewicz, A., 32, 1695, 1699 Billard, I., 596, 627, 628, 629, 3102, 3119, 3121 Billard, L., 1606 Billiau, F., 2855

Billich, H., 1423, 2801, 2817 Billinge, S. J. L., 97 Billups, W. E., 2864 Biltz, W., 63, 100, 413 Bilyk, A., 2457 Bingmei, T., 2591 Binka, J., 1278, 2653 Binnemans, K., 2014, 2016, 2044, 2047, 2048, 2058, 2093 Binnewies, M., 93 Biradar, N. S., 115 Biran, C., 2979 Birch, D. S. J., 629 Birch, W. D., 295 Birkel, I., 1521, 1522, 2370 Birkenheuer, U., 1906 Birks, F. T., 226 Birky, B. K., 1506 Birrer, P., 2351 Bischoff, H., 3052 Bish, D. L., 3176 Bishop, H. E., 3050, 3060, 3062, 3064 Biskis, B. O., 3421, 3424 Bismondo, A., 777, 778, 782, 2440, 2568, 2585, 2586, 2589, 3102, 3142, 3143, 3145 Bisset, W., 2633 Bitea, C., 3045 Bittel, J. T., 368 Bittner, H., 66 Bivins, R., 2027, 2040 Biwer, B. M., 3163, 3171 Bixby, G. E., 1028, 1035, 2140, 3207, 3208, 3210, 3212, 3213, 3219 Bixon, M., 722, 723, 724 Bjerrum, J., 597 Bjerrum, N., 2563 Bjorklund, C. W., 870, 1028, 1029, 1030, 1045, 1048, 1093, 1104, 1171, 2431, 2432, 2709, 2713 Bjørnholm, S., 24, 31, 164, 170, 187, 1880 Bjørnstad, H. E., 3026, 3028, 3031, 3032, 3066 Bkouche-Waksman, I., 2441 Blachot, J., 817 Black, L., 97 Blackburn, P. E., 353, 354, 355, 360, 373, 1074 Bladeau, J.-P., 577, 627 Blain, G., 109, 128, 129, 3115 Blaise, A., 207, 409, 412, 416, 719, 720, 740, 741, 742, 743, 998, 1003, 1023, 1411, 2251, 2264, 2267, 2268, 2278, 2279, 2283, 2284, 2285, 2288, 2315 Blaise, J., 59, 857, 858, 859, 860, 1453, 1513, 1514, 1516, 1544, 1588, 1589, 1604, 1836, 1839, 1840, 1841, 1843, 1844, 1845, 1846, 1847, 1848, 1849, 1850, 1863, 1864, 1865, 1871, 1872, 1873, 1874, 1875, 1876, 1882, 2018

Author Index

I-153

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Blake, C. A., 312, 313 Blake, P. C., 116, 1776, 2240, 2473, 2480, 2803, 2804, 2812, 2816, 2829, 2845, 2912 Blakey, R. C., 377, 393 Blanc, P., 1285, 1329 Blancard, P., 1874, 1875 Blanco, R. E., 2734 Blank, H., 347, 353, 892, 894, 897, 900, 901, 927, 954, 956, 957, 958, 962, 963, 972, 974, 976, 977, 1019, 1030, 1071, 1790, 2392 Blank, H. R., 905, 906, 907, 911, 988 Blanke, B. C., 20 Blankenship, F., 2701 Blanpain, P., 1071 Blaser, P., 3014 Blasse, G., 377 Blaton, N., 267, 268, 541 Blatov, V. A., 536 Blau, M. S., 876, 877, 878, 943, 945, 947, 948, 949, 964 Blaudeau, J. P., 1112, 1113, 1192, 1199, 1778, 1893, 1897, 1909, 1928, 1930, 1932, 1933, 1991, 2037, 2127, 2527, 2528, 2531, 2532, 3087, 3106, 3107, 3108, 3111, 3112, 3113, 3116, 3118, 3122, 3125, 3170 Blaudeau, J.-Ph., 3039 Blauden, J.-P., 764 Blaylock, M. J., 2668 Bleaney, B., 1199, 1931, 2226, 2228, 2561, 3352, 3410, 3424 Bleany, B., 1823 Bleise, A., 3173 Bleuet, P., 861 Blobaum, J. M., 967 Blobaum, K. J. M., 967 Bloch, F., 2316 Bloch, L., 817 Block, J., 3239 Bloembergen, N., 2038 Blokhima, V. K., 571 Blokhin, N. B., 763, 765, 1336, 1337, 2531 Blokhin, V. I., 773 Blom, R., 1958 Blomquist, J. A., 3343 Blomqvist, R., 3066 Blo¨nningen, Th., 1880, 1882 Bloom, I., 2924 Bloom, W., 3352, 3424 Bloomquist, C. A., 1509, 1513, 1585 Bloomquist, C. A. A., 1284, 1293, 1449, 1629, 1633, 1635 Blosch, L. L., 2256, 2477, 2480, 2812, 2813, 2829, 2830 Bluestein, B. A., 1095 Blum, P., 67, 71, 398

Blum, P. L., 351, 352, 353, 402 Blum, Y., 2979 Blum, Y. D., 2979 Blume, M., 2234, 2273, 2288 Blumenthal, B., 319 Blumenthal, R. N., 396 Blunck, H., 98 Bo, C., 1927, 3143, 3145 Boardman, C., 856 Boaretto, R., 2887 Boatner, L. A., 113, 1171, 1368, 1472, 1602, 2042, 2047, 2053, 2058, 2059, 2061, 2062, 2075, 2157, 2159, 2226, 2238, 2259, 2261, 2262, 2263, 2265, 2266, 2268, 2269, 2272, 2292 Boatz, J. A., 1908 Bober, M., 366 Bocci, F., 3070 Bochmann, M., 162, 3130, 3131, 3132 Bochvar, A. A., 892, 894, 900, 901, 902, 903, 904, 907, 908, 910, 913, 915 Bock, E., 106 Bock, R., 106 Bockris, J. O’M., 2531, 2538 Bodak, O. I., 69, 72 Bode, B. M., 2966 Bode´, D. D., 1297, 1474, 1475, 1476, 1584, 1585 Bode, J. E., 254 Boden, R., 133, 1449 Bodheka, L. P., 1280 Bodu, R., 824 Boehlert, C., 863 Boehlert, C. J., 964 Boehme, C., 3102, 3119, 3121 Boehme, D. R., 417, 418 Boehmer, V., 2655 Boeme, C., 596 Boerio, J., 372 Boerrigter, P. M., 1200, 1201, 1202, 1203, 1916, 1943, 1944, 1947, 1948, 1951, 2089, 2253 Boettger, M., 1707 Boeuf, A., 65, 66, 334, 335, 994, 995, 1019, 2283, 2292, 2358 Boeyens, J. C. A., 551 Bogacz, A., 469, 475 Bogatskii, A. V., 108 Bogdanivic, B., 116 Bogdanov, F. A., 1169 Bogdanovic, B., 2865 Boge, M., 740, 998 Boggis, S. J., 3021 Boggs, J. E., 77 Bogomolov, S. L., 14, 1654, 1719, 1720, 1735, 1736, 1738 Bogranov, D. D., 164 Bohe, A. E., 855

I-154

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Bohet, J., 34, 35, 191, 193, 1403, 1410, 1412, 1413, 2123, 2160, 2411, 2695 Bohlander, R., 751 Bohmer, V., 2655 Bohrer, R., 477, 496, 515, 554 Bohres, E. W., 114, 206, 208, 470, 2241 Bois, C., 547 Boisset, M. C., 3165, 3166, 3167 Boisson, C., 2246, 2484, 2488, 2812, 2818, 2847, 2856, 2857, 2858, 2869, 2922, 2938 Boivineau, J. C., 347, 353, 1070, 1073, 1074 Boivineau, M., 955, 962 Bojanowski, R., 3026, 3029 Bok, L. D. C., 115 Bokelund, H., 405, 1008, 1409, 1410, 2752, 2753 Bokolo, K., 618 Boldt, A. L., 1275 Bole, A., 86, 91 Bolender, J., 2267 Boll, R. A., 31 Bollen, G., 1735 Bollhofer, A., 231 Bologna, J. P., 227 Bolotnikova, M. G., 1821 Bolton, H., Jr., 1179 Boltwood, B. B., 162 Bolvin, H., 1113, 1156, 1933, 3112, 3125 Bombardi, A., 2236 Bombieri, G., 548, 554, 2426, 2427, 2439, 2440, 2441, 2442, 2443, 2446, 2447, 2449, 2451, 2452, 2468, 2471, 2472, 2473, 2475, 2479, 2483, 2484, 2487, 2491, 2817, 2818, 2831, 2843 Bommer, H., 491 Bomse, M., 1312, 1315, 2580 Bonani, G., 3056 Bonanno, J. B., 2827 Bonazzi, P., 261, 301 Boncella, J. M., 1958 Bond, A. H., 1955, 2452, 2453, 2454, 2584, 2650, 2665, 2666 Bond, E. M., 1283, 2656 Bond, G. C., 1898 Bond, L. A., 3280, 3295, 3296, 3311, 3314 Bond, W. D., 1049, 1402, 2672 Bondarenko, P. V., 1507 Bondietti, E. A., 2591, 3287 Bondybey, V. E., 1968 Bones, R. J., 353, 360, 362, 364 Bonn, J., 3044, 3047, 3048, 3320, 3321 Bonnell, P. H., 1018, 1019 Bonnelle, C., 227, 859, 1095 Bonnelle, J. P., 76 Bonner, N. A., 704, 822 Bonnet, M., 215, 409, 412, 2358 Bonnisseau, D., 740, 998

Bonthrone, K. M., 297 Boocock, G., 1814, 1816, 3360, 3362, 3364, 3365, 3366, 3375, 3376, 3378, 3398 Booij, A. S., 2153, 2154, 2169, 2177, 2185, 2186, 2187 Boom, R., 2209 Booth, A. H., 186 Booth, C. H., 277, 932, 967, 2588, 3173, 3176, 3177, 3179, 3182 Booth, E., 225 Boraopkova, M. N., 424 Borchardt, P., 42, 43 Bordallo, H. N., 338, 339 Bordarier, Y., 1863 Bordunov, A. V., 2449 Boreham, D., 1093 Bore`ne, J., 266 Borg, J., 164 Borggreen, J., 164, 170 Boring, A. M., 921, 922, 924, 954, 1300, 1908, 2082, 2313, 2329, 2330 Boring, M., 1194, 1916, 1938 Borisenkov, V. I., 1504 Borisov, M. S., 1352 Borisov, S. K., 458, 487 Borisov, S. V., 458, 487 Borkowski, M., 840, 1352, 2580, 2649, 2656 Borlera, M. L., 102, 109, 2431, 2432 Born, H.-J., 164 Born, M., 2574 Born, W., 3306 Boro, C., 964, 965, 2342 Boroujerdi, A., 394, 395 Borovoi, A. A., 3095 Borsese, A., 100, 2411 Borylo, A., 3014, 3017 Borzone, G., 100, 2411 Boss, M. R., 988 Bostick, B. C., 3172 Bostick, W. D., 3409 Botbol, J., 187 Botoshansky, M., 2834, 2835, 2984 Bott, S. G., 439, 454, 455, 1182, 1183, 1184, 2452, 2802, 2827, 2876 Botta, F., 1033 Bo¨ttcher, F., 89, 94, 95 Botto, I. L., 110 Bouby, M., 3024, 3103, 3104, 3129 Boucher, E., 92 Boucher, R., 817 Boucher, R. R., 1012, 1015, 1304, 2407 Boucherle, J. X., 2358 Bouchet, J. M., 943, 970 Boudarot, F., 2237, 2286 Boudreaux, E. A., 2231 Bouexiere, D., 97 Bougon, R., 334, 503, 507, 533, 535, 536, 537, 561, 566, 567

Author Index

I-155

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Bouhlassa, S., 1324, 1352 Bouillet, M. N., 719, 720 Bouisset, P., 3062 Bouissie`res, G., 37, 38, 162, 164, 167, 176, 178, 179, 184, 187, 191, 195, 200, 201, 207, 209, 210, 211, 215, 216, 218, 220, 221, 222, 225, 227, 229, 230, 1077, 1079, 1080, 1101, 1302, 1468, 1529, 1548, 1602, 1611, 1629, 2552 Boukhalfa, H., 421, 1110, 1178, 1179 Boulet, P., 97, 402, 407, 967, 968, 1009, 1012, 1015, 1016, 1033, 1034, 1784, 1790, 2239, 2289, 2290, 2352, 2353, 2372, 2407 Bourcier, W. L., 292 Bourdarot, F., 744 Bourderie, L., 1551 Bourdon, B., 231, 3314 Bouree, F., 402, 407 Bourges, J., 1049, 1603, 2672 Bourges, J. Y., 1324, 1329, 1341, 1356, 1365, 1366 Bourion, F., 80, 81 Bourion, R., 80 Bourne, G. H., 3401, 3405 Boussie, T. R., 2488, 2852, 2856 Boust, D., 3022 Boutique, J.-P., 420, 423, 425, 435, 437, 457, 470, 473, 474, 478, 502, 509, 514, 515, 516, 538, 544, 551 Bouzigues, H., 824 Bovey, L., 858, 860, 1116 Bovin, A. V., 817 Bowden, Z. A., 2278 Bowen, R. B., 620 Bowen, S. M., 1431 Bowen, V. T., 3282, 3287, 3295 Bower, K., 225 Bowers, D. L., 2096, 2536, 3034, 3037, 3043, 3044, 3059, 3060 Bowersox, D. F., 717, 865, 866, 867, 868, 870, 873, 874, 875, 904, 905, 913, 914, 2709, 2711, 2713, 3224 Bowmaker, G. A., 1671 Bowman, A. L., 67, 71, 98, 2407, 2408, 2411 Bowman, B. M., 3353, 3402 Bowman, F. E., 961 Bowman, M. G., 30, 34, 35, 2385 Boxall, C., 1138 Boyanov, M. I., 3180, 3182 Boyce, J. B., 3240 Boyce, W. T., 1433 Boyd, C. M., 634 Boyd, H. A., 3057 Boyd, P. W. D., 1671 Boyd, T. E., 1292 Boyer, J., 1268 Boyi, W., 2452, 2456

Brabers, M. J., 32, 33, 113 Brachet, G., 1304 Brachmann, A., 3138, 3150 Brack, M., 1883 Bradbury, M. H., 192, 2148, 3152, 3156, 3157 Bradley, A. E., 854, 2690 Bradley, A. J., 3159 Bradley, C. R., 275 Bradley, D. C., 115, 1186 Bradley, D. G., 93 Bradley, J. P., 275 Bradley, M. J., 404, 1131, 1132, 1144, 1146 Bradshaw, J. S., 2449 Brady, E. D., 861, 1112, 1166, 3109, 3210 Brady, J. D., 1631, 1633, 1635, 1636, 1858 Brady, P. V., 3179 Braicovich, L., 1196, 1198, 2080, 2085, 2086, 2561 Braithwaite, A., 3165, 3167 Braithwaite, D., 407, 1300, 2239, 2352, 2359 Brambilla, G., 2704 Bramlet, H. L., 2426, 2427 Bramson, J. P., 3278, 3327, 3328 Brand, G. E., 2708, 2709 Brand, J. R., 2538 Brandau, B. L., 224 Brandau, E., 1352, 1551 Brandau, W., 3416, 3420 Brandel, V., 103, 109, 110, 128, 275, 472, 477, 1171, 1172, 2431, 2432 Brandenburg, N. P., 2434 Brandi, G., 1802, 2819 Brandsta¨tter, F., 266, 281 Brandt, L., 772, 774 Brandt, O. G., 2274, 2275 Brandt, R., 822, 3014, 3296 Branica, M., 584, 601, 3130 Brannon, J. C., 291, 3159, 3163 Bransta¨tter, F., 268 Brard, L., 2913, 2918, 2924, 2933, 2984, 2986 Brater, D. C., 485, 559 Bratsch, S. G., 38, 118, 1352, 1685, 1686, 2539, 2540, 2541, 2542, 2543, 2544, 3096, 3098, 3109, 3126 Brauer, G., 69, 72, 474, 513, 537, 2408 Brauer, R. D., 2678, 2680, 2682, 2683, 2684, 2689 Brault, J. W., 1840, 1845, 1846 Braun, E., 62 Braun, R., 377 Braun, T. P., 89, 95 Bray, J. E., 2261 Bray, K. L., 2049 Bray, L. A., 1049, 1268, 1290, 1291 Brcic, B. S., 506, 508 Bre´bion, S., 133 Brechbiel, M. W., 43, 44 Bredig, M. A., 357

I-156

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Bredl, C. D., 2333, 2352 Breeze, E. W., 415, 416, 417, 2413 Breit, G., 1898 Breit, G. N., 3140 Breitenstein, B. D., 3413 Breitung, W., 368 Breivik, H., 1666, 1695, 1702, 1717, 1735 Brendel, C., 94 Brendel, W., 94 Brendler, V., 2583, 3037, 3044, 3046, 3069, 3102, 3131, 3138, 3140, 3141, 3142, 3145, 3147, 3149, 3150, 3160, 3161, 3381, 3382 Brendt, U., 445 Brennan, J., 2488 Brennan, J. G., 1200, 1202, 1949, 1956, 1960, 2256, 2471, 2472, 2473, 2475, 2476, 2478, 2479, 2480, 2481, 2561, 2802, 2803, 2805, 2806, 2807, 2808, 2809, 2833, 2834, 2837, 2854, 2856, 2879, 2916, 2922 Brenner, I. B., 638, 3328 Brenner, V., 1921, 1922 Brese, N. E., 98 Bressat, R., 114 Brett, N. H., 415, 416, 417, 1058, 1059, 1060, 1062, 1065, 1066, 1067, 1070, 1071, 2413 Brewer, K., 2739, 2741 Brewer, K. N., 1282 Brewer, L., 33, 67, 95, 96, 413, 738, 860, 927, 962, 1034, 1093, 1452, 1515, 1586, 1643, 1854, 1855, 1858, 1859, 1872, 2015, 2018, 2020, 2024, 2076, 2078, 2118, 2209, 2407 Briand, J.-P., 164 Brianese, N., 2472, 2473, 2484, 2820, 2825, 2841 Bricker, C. E., 634 Brickwedde, F. G., 2159, 2161 Bridgeman, A. J., 3102 Bridger, N. J., 1018, 1019, 1020, 2238 Bridges, N. J., 421, 1110, 2380 Bridgewater, B. M., 2827 Bridgman, P. W., 61 Briesmeister, R. A., 1088 Briggs, G. G., 61, 78 Briggs, R. B., 487, 2632 Briggs-Piccoli, P. M., 97 Brighli, M., 2590 Brillard, L., 181, 211, 1352, 1428, 1476, 1477, 1551, 1554, 1629, 1688, 1700, 1718 Brintzinger, H., 61 Brisach, F., 2655 Brisi, C., 373, 375, 377, 393 Brisianes, G., 405 Brison, J. P., 2352 Bristow, Q., 3027 Brit, D. W., 343

Brito, H. F., 1454, 2042, 2062, 2071, 2075 Britt, H. C., 1447, 1477 Brittain, R. D., 2179 Britton, H. T. S., 112 Brixner, L., 376, 377, 378 Brixner, L. H., 2407 Broach, R. W., 2479, 2481, 2839 Brochu, R., 102, 110, 374, 377, 378, 380, 382, 393, 414, 1172, 2413, 2431 Brock, C. P., 1959, 1993, 2480, 2837, 2892, 2893 Brock, J., 851 Brodsky, M. B., 101, 324, 957, 1297, 1319, 2238, 2264, 2283, 2292, 2315, 2341, 2346, 2350, 2698 Brody, B. B., 1092, 1094, 1100, 1101, 2167 Brody, S., 3357, 3369 Broecker, W. S., 3056 Broholm, C., 2351 Broli, M., 353, 355, 360, 362, 396, 397 Bromely, L., 738 Bromley, L., 1093 Bromley, L. A., 95, 96, 413 Bronisz, L. E., 996 Bronner, F., 3357 Bronson, M. C., 996 Brook, A. G., 2985 Brookes, N. B., 1196, 1198, 2080, 2085, 2086, 2561 Brookhart, S. K., 2924 Brookins, D. G., 271 Brooks, A. L., 3396 Brooks, M. S., 191 Brooks, M. S. S., 207, 719, 720, 1527, 2150, 2248, 2276, 2289, 2291, 2353, 2354, 2359, 2464 Brooks, R., 1080, 1086 Brooks, S. C., 3180 Bros, J. P., 469, 475 Brosn, G. M., 2839 Brossman, G., 900, 901 Brown, A., 69, 72 Brown, C., 1071 Brown, C. F., 287 Brown, C. M., 929 Brown, D., 78, 81, 82, 86, 93, 94, 115, 162, 164, 166, 178, 179, 182, 183, 184, 186, 191, 194, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 213, 215, 216, 220, 221, 222, 224, 227, 379, 421, 423, 425, 435, 436, 439, 440, 441, 446, 451, 453, 455, 466, 469, 471, 472, 473, 474, 475, 476, 477, 478, 479, 480, 481, 482, 484, 485, 487, 490, 491, 492, 494, 495, 496, 497, 498, 499, 500, 501, 502, 504, 505, 507, 509, 510, 512, 513, 514, 515, 516, 518, 520, 522, 523, 524, 525, 526, 527, 528, 533, 534, 535, 543, 544, 547,

Author Index

I-157

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 552, 553, 554, 555, 556, 557, 566, 567, 569, 570, 571, 572, 573, 574, 575, 734, 736, 737, 738, 739, 745, 746, 748, 1077, 1084, 1095, 1097, 1100, 1184, 1188, 1190, 1191, 1312, 1398, 1411, 1417, 1459, 1527, 1529, 1562, 1593, 1599, 1681, 1798, 1931, 1951, 2065, 2080, 2085, 2086, 2087, 2123, 2160, 2161, 2164, 2195, 2276, 2413, 2415, 2416, 2418, 2419, 2420, 2421, 2422, 2423, 2424, 2425, 2426, 2428, 2434, 2435, 2472, 2475, 2476, 2483, 2484, 2485, 2580, 2695, 2817, 2843, 2851, 2852 Brown, D. R., 578 Brown, E. D., 76, 109 Brown, F., 1018, 3212, 3217, 3218, 3222 Brown, F. B., 1908, 1909 Brown, F. W., 3046 Brown, G. E., 270, 276, 277, 286, 795, 3094, 3102, 3127, 3139, 3152, 3155, 3158 Brown, G. E., Jr., 1810, 2531, 3111, 3122, 3163, 3165, 3169 Brown, G. H., 101 Brown, G. M., 521, 2479, 2481 Brown, G. S., 3282 Brown, H., 1187 Brown, H. C., 337 Brown, H. S., 732 Brown, I. D., 3093 Brown, J., 1810 Brown, J. D., 2076 Brown, K. B., 312, 313 Brown, K. L., 1963 Brown, N. R., 270, 297, 1295, 3017, 3302 Brown, P. J., 1023, 1055, 2249, 2250 Brown, P. L., 119, 120, 121, 123, 124, 126, 2575 Brown, R. D., 1981 Brown, W., 731, 732 Brown, W. G., 996 Brown, W. R., 2432 Browne, C. I., 5, 227, 1577, 1622 Browne, E., 20 Browning, P., 357, 367 Brozell, S. R., 577, 627, 1192, 1199, 1897, 1909, 1928, 1930, 2037 Bruce, F. R., 2734 Bruce, M. I., 2889 Bru¨chle, W., 182, 185, 186, 1447, 1629, 1635, 1643, 1646, 1647, 1662, 1664, 1679, 1684, 1685, 1687, 1696, 1698, 1699, 1700, 1704, 1705, 1708, 1709, 1710, 1711, 1712, 1713, 1714, 1716, 1718, 1735, 1738, 2575 Bru¨ck, E., 62 Bruck, M. A., 2472, 2919 Brucklacher, D., 2393 Brueck, E., 70, 73

Bruenger, F. W., 1823, 3340, 3343, 3350, 3353, 3355, 3359, 3360, 3361, 3362, 3364, 3365, 3366, 3370, 3373, 3374, 3375, 3376, 3377, 3378, 3379, 3381, 3382, 3385, 3388, 3396, 3398, 3399, 3403, 3404, 3405, 3413, 3414, 3415, 3416, 3420 Bruger, J. B., 1513, 1516 Bruggeman, A., 845 Brugger, J., 260, 267, 285, 288, 292 Bru¨gger, M., 1738 Bruguier, F., 861 Brumme, G. D., 366 Brun, C., 452 Brun, T. O., 64, 66 Brundage, R. T., 763, 766, 1369, 2095 Brunelli, M., 1802, 2420, 2819, 2865 Brunn, H., 77 Bruno, J., 117, 121, 124, 125, 127, 128, 130, 131, 293, 768, 1805, 1927, 2583, 3064, 3143, 3145, 3160 Bruno, J. W., 2470, 2479, 2801, 2840, 2841, 2918, 2934 Brunton, G. D., 84, 86, 87, 88, 89, 90, 91, 92, 424, 458, 459, 460, 461, 462, 463, 464, 465, 487, 2416 Brusentsev, F. A., 539, 542 Bru¨ser, W., 116 Brusset, H., 539, 541 Bryan, G. H., 466, 1018 Bryne, A. R., 786 Bryner, J. S., 101 Brynestad, J., 396 Bryukher, E., 31 Bublitz, D., 133, 3138, 3149 Bublyaev, R. A., 546 Bubner, M., 2568, 3102, 3135, 3138, 3140, 3141, 3142, 3145, 3147, 3149, 3150 Buchanan, J. M., 1168 Buchanan, R. F., 848 Buchardt, O., 630 Bucher, B., 1055 Bucher, E., 96, 2351 Bucher, J. J., 118, 277, 287, 289, 579, 585, 589, 602, 795, 1112, 1166, 1327, 1338, 1363, 1370, 1921, 1923, 1947, 2530, 2531, 2532, 2568, 2576, 2580, 2583, 2588, 2812, 3087, 3089, 3090, 3095, 3101, 3102, 3103, 3104, 3106, 3107, 3110, 3111, 3113, 3114, 3115, 3117, 3118, 3119, 3122, 3130, 3131, 3135, 3138, 3140, 3141, 3142, 3145, 3146, 3147, 3149, 3150, 3152, 3154, 3155, 3156, 3160, 3165, 3166, 3167, 3170, 3179, 3181, 3182, 3344, 3369, 3385, 3388, 3390, 3391, 3394, 3417, 3423 Buchholtz ten Brink, M., 275 Buchholz, B. A., 1295, 2750, 2751

I-158

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Buchkremer-Hermanns, H., 89, 94 Buchmeiser, M. R., 851 Buck, E. C., 253, 270, 271, 273, 274, 275, 279, 280, 289, 291, 292, 297, 1806, 3017, 3051, 3052, 3302 Buckau, G., 1352, 1354, 2591, 3022, 3043, 3057 Budantseva, N. A., 745, 747, 749, 1127, 1170, 1175, 1312, 1321, 1931, 2434, 2436, 2595, 3043 Buden, D., 817 Budentseva, N. A., 1312, 1320 Budnikov, P. P., 395 Buergstein, M. R., 2984 Buesseler, K. O., 3046 Bugl, J., 410 Buhrer, C. F., 412 Buijs, K., 34, 35, 191, 194, 1271, 1304, 1402, 1403, 1410, 1412, 1413, 1432, 1433 Bujadoux, K., 2930 Bukhina, T. I., 2668 Bukhsh, M. N., 213, 217, 229 Bukhtiyarova, T. N., 129, 773 Bukina, T. I., 1408 Buklanov, G. V., 14, 776, 822, 1036, 1352, 1398, 1400, 1624, 1629, 1632, 1633, 1635, 1636, 1653, 1654, 1663, 1684, 1690, 1707, 1719, 1720, 1735, 1736, 1738, 1932 Bulbulian, S., 3057 Buldakov, L. A., 3352, 3424 Bulkin, V. I., 986, 1302 Bullock, J. I., 439, 445, 449, 452, 455, 544, 585, 593, 1169 Bulman, J. B., 63 Bulman, R. A., 1813, 1815, 1817, 1819, 1820, 1821, 3340 Bulot, E., 2484, 2488, 2490, 2491, 2856, 2859, 2866 Bundschuh, T., 120, 125, 126, 3045 Bundt, M., 3014 Bunker, B. A., 3180, 3182 Bunker, M. E., 227 Bunnell, L. R., 404 Bunney, L. R., 180, 187 Bunzl, K., 3017 Bu¨nzli, J.-C. G., 2532 Bu¨ppelmann, L., 1145, 1146 Burch, W. D., 1352 Burdese, A., 102, 109, 2431, 2432 Burdick, G. W., 2020 Burford, M. D., 2683 Burg, J. P., 3047 Burgada, R., 2591, 3413, 3419, 3421, 3423 Burger, L. L., 841, 843, 2626, 2650, 2704 Burgess, J., 1778, 2603 Burggraft, B., 3349, 3350, 3398, 3399 Burghard, H. P. G., 208, 1188, 1951, 2852

Burghart, F. J., 2284 Burgus, W. H., 166, 167, 169, 188, 195, 230 Burk, W., 497 Burkart, W., 3173 Burkhart, M. J., 775, 1127, 1181, 2594 Burlakov, V. V., 2927 Burlando, G. A., 393 Burlet, P., 409, 412, 719, 720, 739, 740, 744, 1055, 2236, 2237, 2275, 2286 Burmistenko, Yu. N., 3046 Burnaeva`, A. A., 1422, 2431 Burnett, J., 1417 Burnett, J. L., 33, 38, 118, 1312, 1328, 1329, 1330, 1423, 1424, 1446, 1454, 1460, 1479, 1480, 1481, 1482, 1526, 1529, 1546, 1547, 1548, 1555, 1557, 1592, 1604, 1607, 1669, 1725, 1727, 2122, 2124, 2163, 2542 Burnett, W. C., 3020, 3282, 3285 Burney, G. A., 705, 714, 786, 787, 817, 1290, 1291, 1312, 1323, 1412, 1422, 3281 Burns, C. J., 421, 739, 1110, 1182, 1185, 1186, 1901, 1955, 1958, 1965, 2380, 2400, 2472, 2479, 2480, 2484, 2487, 2488, 2490, 2491, 2799, 2803, 2813, 2815, 2831, 2832, 2833, 2835, 2845, 2846, 2847, 2848, 2849, 2850, 2853, 2858, 2867, 2868, 2879, 2911, 2914, 2916, 2919, 2921, 2922, 2995, 2996 Burns, J., 2182, 2186 Burns, J. B., 1532 Burns, J. H., 116, 462, 488, 502, 747, 1084, 1093, 1096, 1295, 1312, 1315, 1317, 1320, 1323, 1324, 1357, 1358, 1359, 1360, 1361, 1362, 1415, 1416, 1417, 1423, 1431, 1455, 1464, 1465, 1468, 1471, 1528, 1530, 1531, 1532, 1533, 1541, 1544, 1599, 1953, 2163, 2400, 2401, 2402, 2417, 2422, 2427, 2434, 2436, 2439, 2444, 2451, 2452, 2469, 2470, 2472, 2489, 2490, 2527, 2801, 2814, 2815, 3125 Burns, M. P., 892, 942 Burns, P. A., 3017, 3302 Burns, P. C., 103, 113, 257, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 270, 271, 272, 280, 281, 282, 283, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 299, 300, 301, 580, 582, 583, 584, 730, 2193, 2402, 2429, 2430, 2431, 2432, 2433, 2434, 2435, 3093, 3094, 3118, 3155, 3160, 3170, 3178 Burns, R. C., 1084, 1101, 2426 Burns, W. G., 39 Burr, A. F., 60, 190, 859, 1370 Burraghs, P., 1681 Burrel, A. K., 605

Author Index

I-159

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Burrell, A. K., 2464, 2465 Burriel, R., 2208, 2211 Burris, J. L., 97 Burris, L., 2693, 2708, 2709, 2710, 2712, 2713 Burrows, H. D., 130, 131, 627, 629 Bursten, B., 764, 1113 Bursten, B. E., 203, 405, 575, 1112, 1191, 1192, 1196, 1200, 1363, 1670, 1671, 1676, 1726, 1727, 1728, 1729, 1778, 1893, 1894, 1895, 1896, 1900, 1901, 1902, 1903, 1908, 1915, 1916, 1917, 1922, 1925, 1926, 1932, 1933, 1934, 1939, 1943, 1944, 1945, 1946, 1948, 1949, 1950, 1951, 1952, 1953, 1954, 1955, 1956, 1957, 1958, 1959, 1960, 1961, 1962, 1966, 1969, 1971, 1973, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1991, 1993, 1994, 2127, 2246, 2400, 2527, 2528, 2531, 2532, 2561, 2803, 2815, 2853, 2861, 2863, 2918, 3039, 3087, 3106, 3107, 3108, 3111, 3112, 3113, 3116, 3118, 3122, 3125, 3170 Burwell, C. C., 862, 897 Burwell, R. L., Jr., 2999, 3002, 3003 Buryak, E. M., 335 Burzo, E., 67 Busch, G., 412 Busch, J., 113 Busch, R. D., 3409 Buscher, C. T., 851, 3101, 3152, 3155, 3156 Buschow, K. H. J., 65, 66, 69, 70, 71, 72, 73, 2356 Bushuev, N. N., 112 Bussac, J., 824 Buster, D. S., 3343, 3351, 3365, 3396, 3405 Butcher, R. J., 2484, 2486, 2487, 2813, 2844, 2845 Butler, E. N., 984 Butler, I. B., 3047 Butler, I. S., 3171 Butler, J. E., 2243 Butler, R. N., 2530 Butt, J. B., 3003 Butterfield, D., 35 Butterfield, M. T., 1056, 2347 Buxton, S. R., 619 Buyers, W. J. L., 399, 1055, 2360 Buykx, W. J., 353 Bychkov, A. V., 854, 2692, 2693, 2695, 2696, 2697, 2698, 2700, 2702, 2704, 2705, 2706, 2707, 2708 Bykhovskii, D. N., 176 Bykov, V. N., 364, 402 Byrne, A. R., 3056, 3057, 3058, 3307 Byrne, J. P., 3036 Byrne, J. T., 1104

Byrne, N. E., 2864 Byrne, T. E., 1505 Cabell, M. J., 27, 30, 31 Cabrini, A., 123 Cacceci, M. S., 782 Cacciamani, G., 927 Caceci, M., 768, 1352, 2664 Caceci, M. S., 2546, 2551, 2572, 2586 Caceres, D., 2441 Cacheris, W. P., 132 Caciuffo, R., 65, 66, 334, 335, 994, 995, 1019, 2278, 2279, 2285, 2286, 2287, 2292 Caciuffo, R. C., 2280, 2283, 2284, 2285, 2294 Caffee, M. W., 3300 Cagarda, P., 14, 1653, 1713, 1717 Cahill, C. L., 259, 262, 282, 289, 290 Cai, J. X., 76 Cai, S., 1635, 1642, 1643, 1645, 1646 Caignol, E., 468 Caillat, R., 329, 421, 487, 557 Caille´, A., 444 Caillet, P., 544 Cain, A., 1335 Caira, M. R., 472, 477, 512 Caird, J. A., 1453, 1454, 1455, 1515, 1544 Calais, D., 958, 959, 960 Calas, G., 270, 276, 277, 3152, 3155, 3163, 3168 Caldeira, K., 2728 Calder, C. A., 942, 943, 944, 946 Calderazzo, F., 2469, 2819 Caldhorda, M. J., 2912 Calestani, G., 103, 110, 204, 207, 2411 Caletka, R., 176, 1640, 1645, 1663, 1690 Caley, E. R., 253 Calhorda, M. J., 2885 Caligara, F., 2696, 2697 Calle, C., 2633 Calmet, D., 3062 Calvert, S. E., 225 Calvin, M., 115, 2264 Camarcat, M., 191 Campana, C. F., 555, 1173 Campbell, A. B., 2133, 2193 Campbell, D. O., 215, 1290, 1451, 1509, 1585, 2640 Campbell, D. T., 2452 Campbell, G. C., 2490, 2859, 2860 Campbell, G. M., 1008, 1116, 2698 Campbell, T. J., 259, 260, 262, 263, 266, 267, 269 Campello, M. P., 2881, 2883, 2885, 2886 Camus, P., 1453, 1846, 1871 Candela, G. A., 2272 Caneiro, A., 355, 356 Canneri, G., 109

I-160

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Cannon, J. F., 67, 2407 Cantle, J., 638, 3328 Cantrell, K. J., 287, 1159, 1160, 3173, 3176, 3177 Cantu, A. A., 1908 Cao, R., 2062 Cao, X., 791 Cao, Z., 1285 Capdevila, H., 1117, 1150, 1160, 1161, 1162, 1164 Capocchi, J. D. T., 61 Capone, F., 1029, 1036, 1045, 1047, 1971, 2149, 3212 Cappis, J. H., 789, 3014, 3314 Caputi, R. W., 1075 Carassiti, V., 629 Carbajo, J. J., 357, 1048, 1071, 1074, 1075, 1076, 1077 Carbol, P., 3032, 3070 Carey, A. E., 3287, 3295 Carey, G. H., 2587 Cariati, F., 2440 Cariou, J., 1882 Carleson, B. G. F., 2698 Carleson, T. E., 2679, 2681, 2683, 2684 Carlier, R., 220, 221 Carlile, C. J., 2250 Carlin, R. T., 2691 Carlos-Marquez, R., 1143 Carls, E. L., 1081 Carlson, E. H., 492 Carlson, L. R., 859, 1873, 1874, 1875, 1877 Carlson, O. N., 61 Carlson, R. S., 332 Carlson, T. A., 33, 1296, 1452, 1453, 1516, 1626, 1627, 1640, 1669, 1682, 1725, 1727 Carlton, T. S., 86, 91 Carmona, E., 1956, 2473, 2803, 2806, 2807 Carmona-Guzman, E., 2866 Carnall, W. T., 350, 373, 380, 382, 421, 422, 425, 482, 483, 486, 501, 502, 503, 504, 505, 509, 521, 529, 549, 561, 729, 745, 763, 766, 857, 858, 859, 988, 1088, 1109, 1110, 1112, 1113, 1194, 1296, 1312, 1314, 1324, 1325, 1326, 1327, 1338, 1340, 1365, 1404, 1406, 1410, 1430, 1453, 1454, 1455, 1465, 1471, 1473, 1474, 1475, 1513, 1515, 1533, 1543, 1544, 1545, 1557, 1604, 1847, 1866, 1896, 2014, 2015, 2016, 2018, 2020, 2030, 2031, 2032, 2033, 2034, 2035, 2036, 2037, 2038, 2039, 2041, 2042, 2044, 2047, 2048, 2050, 2053, 2054, 2056, 2057, 2058, 2060, 2062, 2063, 2064, 2065, 2068, 2069, 2070, 2071, 2072, 2073, 2075, 2077, 2078, 2080, 2082, 2084, 2085, 2086, 2089,

2090, 2091, 2092, 2093, 2094, 2095, 2096, 2097, 2099, 2103, 2226, 2251, 2259, 2265, 2530, 2601, 2696, 2697, 2699 Carniglia, S. C., 1085, 1312 Carpenter, J. D., 2924 Carpenter, S. A., 3025 Carpio, R. A., 2686 Carr, E. M., 398 Carra, P., 2236 Carrano, C. J., 1824, 3349, 3359, 3364, 3365, 3376, 3378 Carre, D., 1055 Carrera, A. G., 2655 Carrera, M. A. G., 2655 Carrere, J. P., 219 Carritt, J., 3341, 3342, 3348, 3353, 3356, 3386 Carroll, D. F., 1058 Carroll, R. L., 2652 Carroll, S. A., 3064, 3160 Carroll, S. L., 3180 Carrott, M. J., 2679, 2681, 2682, 2683 Carsell, O. J., 186 Carstens, D. H. W., 1968, 1971 Carswell, D. J., 187 Carter, F. L., 66, 1515 Carter, J. A., 3312 Carter, M. L., 279, 280, 291, 2157, 2159 Carter, R. E., 368 Carter, W. J., 2038 Cartula, M. J., 980, 981, 983, 984, 986 Carugo, O., 2577 Caruso, J., 3323 Carvalho, A., 2881, 2882 Carvalho, F. M. S., 260, 293 Carvalho, F. P., 1507 Casa, D., 2288 Casalta, S., 2143 Casarci, M., 1280, 1282, 2738, 2743 Casarin, M., 1953, 1957 Casas, I., 121, 124, 1805 Case, A. C., 3386 Case, G. N., 1640, 2561, 2585 Casellato, U., 115, 2437, 2438, 2440, 2441, 2472, 2473, 2484, 2820, 2825, 2841 Casensky, B., 2655 Casey, A. T., 215, 218, 219, 227 Casida, K. C., 1910 Casida, M. E., 1910 Cassol, A., 767, 770, 776, 777, 778, 779, 781, 782, 1178, 1180, 1181, 2441, 2550, 2554, 2584, 2585, 2586 Cassol, G., 2586, 2589 Castellani, C. B., 2441, 2577 Castellato, U., 1926 Castillo, M. K., 3057 Casto, C. C., 632

Author Index

I-161

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Castro, J. R., 1507 Castro-Rodrigues, I., 1965 Catalano, J. G., 113, 286, 1810, 2157, 2159 Cater, E. D., 1968, 1971 Catlow, C. R. A., 367, 368, 369, 1045 Caton, R. H., 64, 66 Catsch, A., 3413 Caturla, M. J., 863 Cauchetier, P., 1177, 1178, 1179, 1180, 1181, 2575 Cauchois, Y., 190, 227, 859 Caude, M., 2685 Caulder, D. L., 277, 2588, 3179, 3182 Caurant, D., 1962, 2246, 2847, 2858, 2862 Cauwels, P., 3042, 3043 Cavalli, E., 2100 Cavellec, R., 1369, 2042, 2062, 3037 Cavendish, J. H., 61, 78 Cavigliasso, G., 3102 Caville, C., 545 Cavin, O. B., 67 Cawan, T. E., 986 Cazaussus, A., 208, 209, 2432, 2433 C&E News, 1754 CEA, 1812, 1829 Cebulska-Wasilewska, A., 1507 Cecille, L., 2633, 2767 Cefola, M., 988 Cejka, J., 264, 281, 289 Celon, E., 2443 Cendrowski-Guillaume, S. M., 2479, 2488, 2857, 2858, 2871, 2889 Cercignani, C., 366, 367 Cernik, R. J., 2238 Cerny, E. A., 1179 Cesari, M., 2471, 2472, 2490, 2491, 2493, 2859 Cesbron, F., 262, 266, 268, 272, 292 Chace, M. J., 3405 Chachaty, C., 1168, 2563, 2580 Chackraburtty, D. M., 371, 1004, 1005, 1007, 1058, 1059, 1060, 1061, 1065, 1170, 2407, 2434, 2441, 2442, 2445, 2446 Chadha, A., 2434 Chadwick, R. B., 1447, 1662, 1703, 1704 Chai, Y., 2864 Chaigneau, M., 83 Chaikhorskii, A. A., 726, 727, 763, 764, 766, 770, 793 Chaiko, D. J., 292 Chakhmouradian, A. R., 113 Chakoumakos, B. C., 278 Chakrabarti, C. L., 3036 Chakravorti, M. C., 540, 566, 588, 2434, 2441 Chakravortty, V., 182, 1283, 1512 Chakroya, E. T., 3067 Chalk, A. J., 2966 Chalk River, 3340 Chamber, C. A., 3259

Chamberlain, D. B., 279, 861, 1282, 2655, 2738, 2739, 2740 Chamberlin, R. M., 117, 2827, 2868 Champagnon, B., 277 Champarnaud-Mesjard, J.-C., 281, 468 Chan, S. K., 2238, 2263, 2279 Chan, T. H., 2953 Chander, K., 1174, 1352 Chandler, J. M., 80 Chandra, P., 2352 Chandrasekharaiah, M. S., 352, 355, 356, 365, 369, 2195 Chang, A., 1943, 1944, 1947, 1949, 1951, 1959 Chang, A. H. H., 1943, 1946, 1947, 1948, 1949, 1951, 1952, 1973, 2253, 2853, 2864 Chang, A. T., 355, 356, 364 Chang, C., 1907 Chang, C. C., 2801, 2851 Chang, C. T., 2270, 2801, 2851 Chang, C. T. P, 1543 Chang, H.-P., 176, 188 Chang, Q., 1973 Chang, Y., 2693, 2713 Chang, Y. A., 927 Chao, G. Y., 103, 113 Chaplot, S. L., 942 Chapman, A. T., 343 Chappell, L. L., 43 Charbonnel, M. C., 1168, 1262, 1270, 1285, 2532, 2657 Chardon, J., 2431 Charistos, D., 302, 3039 Charlet, L., 3152, 3153, 3154, 3165, 3166, 3167 Charlop, A. W., 1635, 1642, 1643, 1645, 1646 Charnock, J. M., 588, 589, 595, 1927, 1928, 2441, 2583, 3132, 3165, 3167, 3169 Charpin, P., 102, 106, 345, 380, 468, 469, 503, 505, 533, 534, 535, 561, 1928, 2439, 2449, 2450, 2452, 2453, 2464, 2465, 2466, 2472, 2484, 2490, 2491, 2801, 2820, 2859, 2866, 3101, 3105, 3120, 3138, 3141 Charron, N., 3054 Chartier, D., 1355 Chartier, F., 1433 Charushnikova, I. A., 747, 748, 2434, 2439, 2442, 2595 Charushnikova, N. N., 746, 748 Charvillat, J. P., 204, 377, 739, 740, 741, 742, 743, 1020, 1022, 1304, 1312, 1316, 1317, 1318, 1319, 1403, 1411, 1412, 1414, 1415, 1420, 1421, 2411, 2413 Charvolin, T., 719, 720 Chasanov, M. G., 356, 357, 366, 378, 903, 1076, 1971, 1972, 2148, 2715 Chasman, R. R., 1736 Chassard-Bouchaud, C., 3050, 3062, 3063 Chassigneux, B., 109

I-162

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Chasteler, R. M., 1447, 1629, 1635, 1642, 1643, 1645, 1646, 1662, 1703, 1704, 2575 Chatalet, J., 421, 520, 529 Chatani, K., 783 Chateigner, D., 3152, 3156, 3157 Chatelet, J., 1874, 1875 Chatt, A., 769, 774 Chatt, J., 93 Chatterjee, A., 1447, 2530 Chattillon, C., 340, 351, 352, 353, 354, 355, 356, 363, 365 Chattin, F. R., 1451, 1509, 1584, 2633 Chattopadhyay, S., 2745 Chaudhuri, N. K., 772, 2578 Chauvenet, E., 61, 76, 78, 79, 80, 81, 82, 93, 108 Chauvin, G., 2712, 2713 Chavastelon, R., 105, 106 Chavrillat, J. P., 740, 741 Chayawattanangkur, K., 25 Chebotarev, K., 2426 Chebotarev, N. I., 900, 902, 904, 906, 907, 908, 910, 911, 912, 913, 914 Chebotarev, N. T., 892, 894, 900, 901, 902, 903, 904, 905, 907, 908, 909, 910, 911, 912, 913, 915, 939, 941, 984, 1106, 1107 Cheda, J. A. R., 106 Cheetham, A. K., 377, 383, 994, 1082 Cheinyavskaya, N. B., 1320 Chellew, N. R., 2692, 2708 Chelnokov, L. P., 1690 Chelnokov, M. L., 1654, 1719, 1720, 1735, 1738 Chemla, M., 1605 Chen, B., 108 Chen, C. T., 861 Chen, F., 270 Chen, J., 1287, 1288, 1352, 2562, 2665, 2762 Chen, J. H., 638, 3311, 3312, 3313 Chen, J. W., 2352, 2357 Chen, L., 2679, 2682, 2684 Chen, M. H., 1452, 1515 Chen, Q., 2888 Chen, S., 2752 Chen, S. L., 927 Chen, T., 189 Chen, X. Y., 2068, 2089 Chen, Y., 795, 1287 Chen Yingqiang, 231 Chen, Y.-X., 2938 Chen, Z., 266 Cheng, H., 171, 231, 3313 Cheng, L., 291, 3163, 3164 Chepigin, V. I., 164, 1654, 1719, 1720, 1735, 1738 Chepovoy, V. I., 1479 Chereau, P., 1044, 1048, 1070, 1074, 2145 Cherer, U. W., 182 Cherne, F. J., 928

Chernenkov, Yu. P., 546 Cherniak, D. J., 3170 Chernorukov, N. G., 113 Cherns, D., 123, 126 Chernyayev, I. I., 109, 566, 585, 593 Chernyi, A. V., 907, 909, 911, 912 Cherpanov, V. I., 2052 Chervet, J., 303 Chetham-Strode, A., 2635 Chetham-Strode, A., Jr., 181 Chetverikov, A. P., 1484 Chevalier, B., 70, 73, 2360 Chevalier, P.-Y., 351, 352, 2202 Chevalier, R., 79, 86, 87, 90, 92, 459 Chevallier, J., 331 Chevallier, P., 164 Chevari, S., 3366 Chevary, J. A., 1904 Chevreton, M., 2439, 2440 Chevrier, G., 102, 106, 2464 Cheynet, B., 351, 352, 2202 Cheynet, M. C., 3052 Chiadli, A., 3024 Chiang, M.-H., 861, 3108, 3178 Chiang, T. C., 964, 965, 967, 2342 Chiappini, R., 133, 3382 Chiapusio, J., 1055 Chiarixia, R., 1585 Chiarizia, R., 633, 716, 773, 840, 1280, 1281, 1282, 1293, 1294, 1508, 1511, 2642, 2643, 2649, 2652, 2655, 2660, 2661, 2727, 2743, 2747, 2748, 2750, 3283, 3284, 3285, 3286, 3295 Chibante, L. P. F., 2864 Chieh, C., 580, 582 Chien, S., 420, 3358 Chierice, G. O., 2580 Chikalla, T. D., 404, 724, 725, 726, 997, 998, 1025, 1030, 1045, 1303, 1312, 1313, 1323, 1358, 1419, 1420, 1464, 1466, 2143, 2147, 2389, 2395, 2396, 2397, 2398 Childs, W. J., 1088, 1194, 1846, 1873, 2080, 2084, 2086 Chilsholm-Brause, C. J., 3035, 3036 Chilton, D. R., 342, 357, 358, 3171 Chilton, J. M., 213, 256 Chinea-Cano, E., 3173 Chintalwar, G. J., 2668 Chiotti, P., 63, 67, 68, 69, 70, 74, 78, 80, 81, 82, 97, 100, 325, 326, 332, 398, 399, 400, 401, 402, 405, 406, 407, 408, 409, 2114, 2197, 2205, 2206, 2207, 2208, 2209, 2385, 2710 Chipaux, R., 997, 998, 1003 Chipera, S. J., 3095, 3175, 3176, 3177 Chipperfield, A. R., 3350, 3351, 3408, 3410, 3411

Author Index

I-163

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Chirkst, D. E., 424, 428, 429, 430, 431, 436, 437, 440, 450, 451, 454, 473, 475, 476, 495, 510, 511 Chisholm-Brause, C., 3101, 3111, 3122, 3152, 3155, 3156, 3165, 3169, 3171 Chisholm-Brause, C. J., 270, 301, 795, 2531 Chistyakov, V. M., 724, 726, 1331, 1334, 1336, 1479, 1481, 1484, 2706, 2707, 2708 Chitnis, R. R., 712, 713, 1281, 1282, 2743, 2745, 2747, 2750, 2757 Chitrakar, R., 1292 Chmelev, A., 1398 Chmutova, M. K., 705, 1283, 1450, 1479, 1509, 1554, 1585, 2651, 2656, 2661, 2666, 2677, 2738, 2739 Chmutova, M. S., 1271, 1284 Choca, M., 471, 512, 513 Chodos, S. L., 476 Choi, I.-K., 380, 2153 Choi, K.-S., 97 Choi, Y. J., 1676, 1679, 1680, 1681, 1682, 1723, 1727 Cholewa, M., 3069 Chollet, H., 2682, 2685 Chongli, S., 2251, 2753 Chopin, T., 109, 1172 Choporov, D., 1085, 1086 Choporov, D. Y., 736, 737, 1312 Choppin, G., 746, 748, 1275, 1284, 1287, 1288, 1291, 1327, 1352, 1354 Choppin, G. R., 5, 131, 132, 405, 705, 771, 772, 775, 778, 781, 782, 988, 1110, 1111, 1112, 1132, 1138, 1143, 1155, 1159, 1160, 1164, 1166, 1179, 1181, 1405, 1407, 1408, 1409, 1424, 1426, 1427, 1434, 1477, 1479, 1508, 1509, 1549, 1550, 1551, 1554, 1555, 1557, 1577, 1585, 1624, 1628, 1629, 1630, 1632, 1635, 1760, 1761, 1764, 1803, 1809, 1811, 2096, 2097, 2098, 2386, 2387, 2400, 2443, 2524, 2525, 2529, 2530, 2534, 2537, 2546, 2547, 2548, 2551, 2552, 2553, 2558, 2561, 2562, 2563, 2564, 2565, 2566, 2571, 2572, 2574, 2577, 2578, 2579, 2580, 2582, 2583, 2584, 2585, 2587, 2589, 2591, 2592, 2594, 2595, 2596, 2602, 2603, 2604, 2605, 2606, 2626, 2627, 2628, 2632, 2635, 2636, 2638, 2639, 2640, 2650, 2664, 2673, 2677, 2688, 2690, 2691, 2726, 3024, 3035, 3287 Chourou, S., 541, 542 Chow, L. S., 2723 Chrastil, J., 2683 Chrisment, J., 2649 Chrisney, J., 857 Christ, C. L., 583, 2486 Christe, K. O., 1978

Christensen, D. C., 717, 865, 866, 867, 868, 869, 870, 873, 874, 875 Christensen, E. L., 1048, 1093 Christensen, E. l., 837 Christensen, H., 3221 Christensen, J. N., 639, 3327 Christiansen, P. A., 1671, 1898, 1907, 1908, 1918, 1920 Christman, R. F., 3150 Christoph, G. G., 1058, 1059, 1060, 1062 Chu, C. Y., 2449 Chu, S. Y., 1626, 1633, 1639, 1644 Chu, S. Y. F., 817 Chu, Y. Y., 1407, 1408, 1409, 1635, 1642, 1643, 1645, 1646 Chuburkov, Y. T., 1640, 1645, 1663, 1690, 1692, 1693 Chuburkov, Yu. T., 1402, 1422, 1423 Chudinov, E. G., 1085, 1086, 1312, 1449, 1479, 1483, 1554, 1605 Chudinov, E. T., 736, 737 Chudinov, N., 1583 Chudnovskaya, G. P., 1365, 1369 Chukanov, N. V., 268, 298 Chuklanova, E. B., 2439 Chumaevskii, N. A., 2439, 2442 Chumikov, G. N., 3017, 3067 Chuney, M., 602 Chung, B. W., 967 Chung, T., 2479 Church, B. W., 3017 Church, H. W., 3252, 3253, 3255 Churney, K. L., 34 Chuveleva, E. A., 1291, 1449, 1512 Chuvilin, D. Y., 989, 996 Chydenius, J. J., 60, 75, 76, 79, 80, 109 Ciliberto, E., 1956, 1957 Cilindro, L. G., 1352 Cinader, G., 336, 994, 995, 2238, 2261, 2262, 2362, 3206 Cingi, M. B., 2440 Cirafici, S., 2204 Cı´sarova´, I., 2427, 2655 Cisneros, M. R., 849, 1139, 1161, 1167 Citra, A., 1969 Citrin, P. H., 3087 Ciurapinski, A., 3173 Civici, N., 3034, 3039 Claassen, A., 3029 Claassen, H. H., 2083 Clacher, A. P., 790, 3063, 3317, 3318 Claraz, M., 3052 Clark, A. H., 280 Clark, C. R., 862, 892 Clark, D. L., 289, 439, 454, 455, 580, 595, 602, 620, 621, 745, 749, 763, 766, 813, 861, 932, 988, 1041, 1043, 1110, 1112, 1116, 1117, 1154, 1155, 1156, 1159, 1162,

I-164

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 1163, 1164, 1165, 1166, 1181, 1182, 1183, 1184, 1314, 1340, 1341, 1359, 1798, 1925, 1926, 1927, 1928, 1931, 2427, 2428, 2429, 2450, 2451, 2484, 2486, 2487, 2488, 2553, 2558, 2583, 2592, 2607, 2802, 2813, 2814, 2844, 2845, 2846, 2858, 2876, 3035, 3087, 3108, 3109, 3112, 3113, 3115, 3118, 3123, 3125, 3126, 3127, 3128, 3130, 3131, 3133, 3134, 3136, 3160, 3167, 3210 Clark, G. A., 1281, 2747 Clark, G. L., 115 Clark, G. W., 343, 1033, 2266 Clark, H. K., 821 Clark, H. M., 186 Clark, J. P., 116 Clark, J. R., 583, 2486 Clark, R. B., 1021 Clark, R. J., 83, 84, 2415 Clark, S. B., 852, 1167, 3280, 3292, 3296, 3306 Clarke, R. H., 1818, 1819, 1820 Clarke, R. W., 19 Clarke, W. J., 3386 Clarkson, T. W., 3359, 3362 Claudel, B., 114, 2438, 2439, 2440, 2443 Clausen, K. N., 357, 389, 399 Clavague´ra-Sarrio, C., 1921, 1922, 1932, 1969, 1988 Clayton, C. R., 3046, 3069, 3179 Clayton, E. D., 988, 1268 Clayton, H., 2208 Clayton, J. C., 390, 394, 397 Cleaves, H. E., 352 Clegg, A. W., 2351 Clegg, J. W., 303, 307, 308, 309, 311 Cleland, W. E., 3117 Clemente, D. A., 548, 2440, 2441 Clemons, G. K., 3343, 3358, 3390, 3391 Cle`ve, P. T., 76, 77, 101, 105, 108, 109, 110 Cleveland, J. M., 466, 814, 837, 850, 988, 1007, 1018, 1110, 1117, 1138, 1140, 1167, 1168, 1169, 1172, 1173, 1174, 1175, 1177, 1178, 1180, 2131, 2579, 2582, 2634, 2650, 2730, 3208, 3212, 3222, 3247 Clifford, A. A., 2681, 2683, 2684 Clifton, C. L., 371 Clifton, J. R., 469, 491 Cline, D., 80 Clinton, J., 66 Clinton, S. D., 256 Clinton, S. O., 256 Cloke, F. G. N., 117, 1943, 1960, 1964, 2240, 2473, 2816, 2854, 2856, 2863, 2912 Close, E. R., 3359, 3361, 3368, 3373, 3387, 3388, 3400

CNIC, Commission on Nomenclature of Inorganic Chemistry of IUPAC, 1653, 1660, 1661 Cobble, J. W., 2538 Cobble, R. W., 2132 Coble, R. L., 343, 369 Cobos, J., 3070 Coburn, S., 2237, 2286 Cochran, J. K., 3022, 3307 Cochran, T. H., 3353, 3396, 3399 Cockcroft, J. K., 89, 94 Cocuaud, N., 1269 Coda, A., 3167 Codding, J. W., 167, 169, 188, 195, 230 Cody, J. A., 97, 420 Coffinberry, A. S., 892, 903, 905, 906, 907, 908, 909, 910, 911, 912, 913 Coffou, E., 102, 103, 110, 2431 Cogliati, G., 1022 Cohen, A., 1547 Cohen, D., 483, 726, 727, 731, 753, 759, 862, 1114, 1116, 1131, 1132, 1297, 1312, 1325, 1326, 1337, 1416, 1424, 1430, 1455, 1465, 1469, 1470, 1473, 1474, 1479, 1530, 1531, 1533, 1604, 1774, 2077, 2292, 2417, 2422, 2527, 2531, 2599, 2601, 3099, 3125 Cohen, D. M., 2394 Cohen, I., 390, 391 Cohen, J. B., 344 Cohen, K. P., 1269 Cohen, L. H., 1547 Cohen, M., 828 Cohen, N., 133, 3345, 3349, 3354, 3355, 3371, 3374, 3378, 3384, 3396 Cohn, K. C., 2919 Cohn, S. H., 3406 Cohran, S. G., 3266 Colani, A., 104 Colarieti-Tosti, M., 2248, 2289, 2291 Cole, S. C., 3159 Colella, M., 113, 271, 280, 291, 2157, 2159 Coleman, C. F., 312, 313, 841, 1477, 1549, 1550, 1554, 1606, 2565, 2731 Coleman, C. J., 1433 Coleman, G. H., 3281 Coleman, J. S., 465, 466, 1291, 1312, 1314, 1325, 1326, 1328, 1329, 1331, 1332, 1410, 1430, 2601 Coleman, P., 2352 Colen, W., 3101 Coles, S., 1943, 1956, 2473, 2803, 2806, 2807, 2854, 2856 Coles, S. J., 117, 2240 Colin-Blumenfeld, M., 129 Colineau, E., 719, 720, 967, 968, 1009, 1012, 1015, 1016, 1784, 1790, 2239, 2352, 2372, 2407

Author Index

I-165

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Colinet, C., 928, 2208 Colineu, E., 2353 Collard, J. M., 740, 1023 Colle, C., 3023, 3067 Colle, J. Y., 1029, 1036, 1047, 2149, 3212 Colle, Y., 1029, 1045, 1971 Collin, J., 2883 Collins, D. A., 164, 173, 177, 180, 227 Collins, E. D., 1271, 1275, 1402, 1448, 1449, 1451, 1509, 1510, 1584, 1585, 2636 Collins, M., 526 Collins, S. P., 2234, 2238 Collison, D., 588, 589, 595, 1927, 1928, 2440, 2441, 2442, 2447, 2448, 2583, 3132 Collman, J. P., 2924 Collongues, R., 113 Colmenares, C. A., 996, 3201, 3206, 3207, 3214, 3223, 3224, 3225, 3227, 3229, 3243, 3244 Colombet, P., 1054 Colsen, L., 1403, 1410, 1412, 1413 Colson, L., 34, 35, 191 Colvin, E. W., 2953 Colvin, R. V., 322 Comar, C. L., 3393 Combes, J. M., 795, 2531, 3111, 3122, 3165, 3169 Comeau, D. C., 1908, 1909 Comodi, P., 3170 Compton, V., 319 Comstock, A. A., 949, 960 Comstock, A. C., 949 Comstock, A. L., 2315, 2355 Conant, J. W., 333 Conaway, J. G., 3027 Conca, J. L., 3175, 3409 Conceicao, J., 2864 Condamines, C., 1285 Condamines, N., 1285 Condemns, N., 2657 Condit, R. H., 2195, 3258, 3259 Condon, E. U., 1862, 2089 Condon, J. B., 332, 3242 Condorelli, G., 116 Condren, O. M., 3016, 3023, 3296 Cone, R. L., 2044, 2047, 2053, 2072, 2073, 2100, 2101, 2103 Conner, C., 1282, 2655, 2738, 2739, 2740 Conner, W. V., 1312 Connes, J., 1840 Connes, P., 1840 Connick, R. E., 988, 1121, 1122, 1126, 1175, 1915 Connor, W. V., 1271, 1312, 1325, 1326 Conradi, E., 477, 496, 515, 554 Conradson, S., 984, 1359, 1370, 2263, 3039, 3040

Conradson, S. D., 127, 128, 130, 131, 270, 580, 595, 620, 621, 849, 861, 932, 933, 1041, 1043, 1112, 1116, 1117, 1154, 1155, 1156, 1162, 1164, 1166, 1167, 1168, 1798, 1923, 1925, 1926, 1927, 1928, 1991, 2427, 2428, 2531, 2583, 2607, 3035, 3039, 3087, 3101, 3108, 3109, 3111, 3112, 3113, 3115, 3117, 3118, 3122, 3123, 3125, 3126, 3127, 3128, 3133, 3134, 3136, 3137, 3152, 3155, 3156, 3163, 3165, 3169, 3171, 3210 Conradson, S. G., 3035, 3036 Constantinescu, O., 181, 211, 1688, 1700, 1718 Contamin, P., 367, 368 Conte, P., 219 Conticello, V. P., 2913, 2918, 2924, 2933, 2984, 2986 Conway, J. B., 2202 Conway, J. G., 442, 457, 1099, 1365, 1423, 1452, 1453, 1455, 1473, 1474, 1513, 1516, 1544, 1586, 1602, 1836, 1839, 1840, 1845, 1846, 1847, 1848, 1849, 1850, 1864, 1865, 1871, 1872, 1873, 1874, 1875, 1877, 1878, 1885, 2038, 2065, 2067, 2074, 2077, 2262, 2265, 2272 Coobs, J. H., 1033 Coogler, A. L., 817 Cook, R. E., 3165, 3168 Cooke, F., 1683 Cooke, N., 3354 Cooke, R., 1138 Cooper, B. R., 1023, 2275, 2364 Cooper, E. L., 3067, 3288 Cooper, J. H., 1449 Cooper, J. R., 3364, 3375 Cooper, J. W., 2699 Cooper, L. N., 62, 2350, 2351 Cooper, L. W., 3295, 3296, 3311, 3314 Cooper, M. A., 259, 262, 268, 287, 289, 290, 298, 2426 Cooper, M. B., 3017, 3302 Cooper, N. G., 814, 863 Cooper, U. R., 2732 Cooper, V. R., 835, 2730 Cooper, W. C., 280 Coops, M. S., 864, 869, 875, 1288, 1291, 1631, 1633, 1635, 1636, 1858, 2636 Cope, R. G., 892, 909, 912 Copeland, J. C., 1530, 1531, 1532, 1533, 1536, 2398 Copland, G. M., 2035 Copp, D. H., 3405 Copple, J. M., 2655, 2738, 2739 Coqblin, B., 1461 Corbel, C., 289 Corbett, B. L., 1445, 1448, 1509, 1510 Corbett, J. D., 83, 84, 2415

I-166

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Corbin, R. A., 1268 Cordaro, J. V., 791 Cordero- Montalvo, C. D., 2038, 2078 Cordfunke, E. H. P., 255, 339, 341, 350, 355, 356, 357, 358, 372, 373, 374, 375, 376, 378, 383, 514, 525, 543, 551, 552, 569, 1048, 1076, 2114, 2115, 2139, 2140, 2142, 2144, 2150, 2151, 2153, 2154, 2157, 2158, 2159, 2160, 2161, 2165, 2176, 2177, 2185, 2187, 2192, 2193, 2206, 2207, 2208, 2209, 2211 Cordier, P. Y., 2584, 2657, 2674, 2761 Cordier, S., 435, 471 Corey, A. S., 294 Corey, J. Y., 2965 Corington, A., 366 Coriou, H., 329, 2712, 2713 Corish, J., 1653, 1654 Corliss, C. H., 59, 60, 857, 1841, 1843 Cornehl, H. H., 1971 Cornet, J. A., 943, 958, 970 Cornog, R., 3316 Corsini, A., 115 Cort, B., 333, 457, 486, 882, 939, 949, 967, 989, 995, 2283, 2289, 2290 Cory, M. G., 1943, 1946, 1949 Cossy, C., 2603, 3110 Costa, D. A., 1185, 2687, 2688, 2689, 2690 Costa, N. L., 164, 166 Costa, P., 957 Costanzo, D. A., 1132 Coste, A., 1874, 1875 Costes, R. M., 535, 2449, 2452 Cotiguola, J. M., 63 Cotton, F. A., 162, 470, 1895, 2490, 2491, 2493, 2628, 2800, 2859, 2860, 3130, 3131, 3132, 3346 Coudurier, G., 76 Couffin, F., 726, 753, 2129 Coughlin, J. U., 270, 3165, 3168 Coulson, C. A., 1915 Coulter, L. V., 2538 Coupez, B., 1927 Courbion, G., 92 Courson, O., 2756 Cousseins, J. C., 85, 86, 87, 88, 90, 91, 92, 457, 458, 459, 468, 1108 Cousson, A., 79, 86, 87, 90, 92, 113, 459, 460, 511, 730, 745, 746, 748, 792, 2443, 2595 Cousson, H., 730, 792 Cousson, J., 745 Coutures, J.-P., 77 Covan, R. G., 2749 Coveney, R. M. J., 3159 Covert, A. S., 973 Cowan, G. A., 824, 1127 Cowan, H. D., 1117, 1118, 1121, 1126, 1131, 1132, 1144, 1146, 2601

Cowan, R. A., 1908 Cowan, R. D., 1730, 1731, 1845, 1862, 1863, 1865, 2023, 2039, 2076 Cowan, R. G., 1294 Cowley, R. A., 2233, 2274, 2276, 2277, 2281 Cowper, M. M., 3050, 3060, 3062, 3064 Cox, D. E., 2273, 2283 Cox, J. D., 62, 322, 2115, 2117, 2120, 2135, 2136, 2137 Cox, L., 2347 Cox, L. E., 333, 334, 335, 795, 861, 932, 989, 995 Cox, M., 840 Crabtree, G. W., 412, 2308 Crabtree, R. H., 2966 Cracknell, A. P., 2274 Craft, R. C., 817 Cragg, P. J., 2452 Craig, I., 1327, 1338, 1370, 2530, 2576, 2580, 3103, 3104, 3110, 3113, 3114, 3115, 3118 Crain, J. P., 1294 Crain, J. S., 3285, 3323, 3326, 3327 Cramer, E. M., 892, 910, 913, 914, 915, 937, 938, 939, 958, 959 Cramer, J., 822, 823, 3314 Cramer, J. J., 274 Cramer, R. E., 1957, 2472, 2473, 2475, 2479, 2484, 2561, 2825, 2826, 2919 Crandall, J. L., 1267 Crane, W. W. T., 164 Cranshaw, T. E., 53 Cranston, J. A., 20, 163, 201 Crasemann, B., 1452, 1515 Craw, J. S., 1926, 1928, 1929, 1931 Crawford, M.-J., 588 Crea, J., 620 Creaser, I., 2584 Cremers, D. A., 3045 Cremers, T. L., 103, 112, 996 Cresswell, R. G., 790, 3063 Crick, D. W., 2642 Crick, E. W., 3283 Cripps, F. H., 225, 226 Crisler, L. R., 1190, 2801, 2807 Criss, C. M., 2132 Cristallini, O., 186, 219 Criswell, D. R., 2728 Crittin, M., 3042, 3043 Croatto, U., 777, 2441 Crocker, A. G., 880, 882 Crocker, H. W., 1049 Croff, A. G., 827 Croft, W. L., 190 Cromer, D. T., 457, 464, 465, 901, 903, 906, 907, 909, 910, 911, 912, 914, 915, 1012, 1013, 1728, 2076, 2407, 2408, 2426, 2427, 2431, 2434, 2480, 2481, 2482, 2837

Author Index

I-167

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Cron, M. M., 352 Cronkite, E. P., 3358, 3367 Crookes, W., 186 Crosby, G. A., 2082, 2241 Crossley, M. J., 3117 Crosswhite, H., 857, 858, 859, 1455, 1474, 1475, 1515, 1544, 1847, 1862, 1866, 1896, 2014, 2015, 2016, 2018, 2029, 2030, 2032, 2035, 2036, 2039, 2042, 2056, 2057, 2077, 2078, 2090, 2091, 2093, 2095, 2096, 2259 Crosswhite, H. M., 421, 422, 501, 505, 509, 521, 857, 858, 859, 1453, 1454, 1455, 1515, 1544, 1847, 1862, 1863, 1866, 1868, 1896, 2014, 2015, 2016, 2018, 2020, 2029, 2030, 2032, 2035, 2036, 2038, 2039, 2056, 2057, 2063, 2077, 2091, 2093, 2259 Croudace, I., 3279, 3285 Croudace, I. W., 3328 Crough, E. C., 389, 391, 392, 396 Crouse, D. J., 312, 1049 Crouthamel, C. E., 169, 170, 171 Crowley, J., 3342, 3354, 3423, 3424 Crowley, J. F., 3341, 3348, 3356, 3387 Croxton, E. C., 399, 400 Crozier, E. D., 962 Csencsits, R., 3165, 3168 Csovcsics, C., 3399 Cui, D., 768 Cuifolini, M. A., 2864 Cuillerdier, C., 773, 1285, 1286, 2563, 2580, 2657, 2673, 2756 Culig, H., 3378, 3379 Cullity, B., 405 Culp, F. B., 638, 3327 Cumming, J. B., 3300, 3301 Cummings, B., 1364 Cummings, D. G., 3060 Cummins, C. C., 1966, 1967, 2245, 2488, 2491, 2859, 2861, 2888 Cuneo, D. R., 77, 487 Cuney, M., 2431 Cunnane, J. C., 292, 1172 Cunningham, B. B., 5, 179, 191, 193, 194, 226, 815, 834, 934, 988, 1085, 1093, 1098, 1101, 1265, 1295, 1297, 1312, 1313, 1409, 1410, 1411, 1412, 1413, 1414, 1417, 1418, 1420, 1444, 1445, 1463, 1464, 1466, 1468, 1470, 1472, 1473, 1480, 1481, 1517, 1519, 1520, 1530, 1531, 1532, 1533, 1536, 1542, 1543, 1547, 1590, 1595, 1596, 1604, 1635, 1674, 1728, 2129, 2264, 2267, 2268, 2386, 2387, 2395, 2396, 2397, 2398, 2417, 2422, 2589, 2638, 2639 Cunningham, G. C., 364, 365 Cunningham, J. E., 406

Cunningham, S. S., 2717 Curcio, M. J., 42, 43, 44 Curie, M., 3, 19, 172, 254, 1397 Curie, P., 3, 19, 162, 254 Curl, R. F., 2864 Curran, G., 3025 Currat, R., 81 Currie, L. A., 3288 Curti, E., 3152, 3156, 3157 Curtis, D., 822, 823 Curtis, D. B., 822, 823, 3014, 3279, 3314 Curtis, M. H., 996 Curtis, M. L., 172, 178, 224, 225 Curtiss, C. F., 962 Curtiss, L. A., 1991, 3113, 3118 Curtze, O., 1880, 1881, 1882, 1883 Cusick, M. J., 1292 Cuthbert, F. L., 55, 58, 2694 Cuthbertson, E. M., 3405 Cwiok, S., 1736 Cymbaluk, T. H., 2484, 2844, 2865 Cyr, M. J., 2464 Czaynik, A., 414 Czerwinski, K., 1138 Czerwinski, K. R., 182, 185, 1160, 1165, 1166, 1445, 1447, 1653, 1664, 1684, 1693, 1694, 1695, 1696, 1697, 1698, 1699, 1701, 1704, 1705, 1706, 1716, 1718, 3025, 3138, 3140, 3142, 3150 Czopnik, A., 2413 Czuchlewski, S., 2347 da Conceicao Vieira, M., 1993 Da Graca, M., 627 da Veiga, L. A., 2439 Daane, A. H., 329, 332, 399, 412 Dabeka, R. V., 84 Dabos, S., 409, 725, 743, 746, 748, 1459, 1520, 1521, 2315, 2370, 2443, 2595 Dabos-Seignon, S., 742, 776, 777, 778, 779, 781, 2315, 2371, 2559, 2565, 2570, 2574, 2585 D’Acapito, F., 389 Dacheux, N., 103, 109, 110, 126, 128, 134, 275, 472, 477, 785, 1171, 1172, 1405, 1432, 1433, 2431, 2432 Dadachova, K., 43 Daehn, R., 3152, 3155, 3156, 3157 Dahlberg, R. C., 2733 Dahlgaard, H., 3017, 3023 Dahlinger, M., 1880, 1882 Dahlke, O., 100 Dahlman, R. C., 2591 Dai, D., 1671 Dai, S., 2087, 2088, 2688, 2691, 3127, 3139 Dai, X., 964 Dakternieks, D. R., 2664

I-168

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Dal Negro, A., 3159 D’Alessandro, G., 123, 773 D’Alessio, J. A., 1186 Dalichaouch, Y., 2352 Dalla Cort, A., 597 Dallera, C., 1196, 1198, 2080, 2085, 2086, 2561 Dalley, N. K., 2429 Dallinger, R. F., 1952, 2253 Dallinger, R. P., 372 Dalmas de Re´otier, P., 2236 Dalmasso, J., 25, 3024 Dalton, J. T., 1006, 1009, 2407, 2408 Dam, J. R., 1147, 2554 Damien, A., 403 Damien, D., 99, 204, 207, 739, 740, 741, 742, 743, 1017, 1020, 1022, 1050, 1051, 1052, 1053, 1054, 1304, 1312, 1316, 1317, 1318, 1335, 1359, 1412, 1414, 1415, 1416, 1420, 1421, 1460, 1465, 1470, 2409, 2411, 2413, 2414 Damien, D. A., 1411, 1414, 1415, 1421, 1460, 1465, 1470, 1531, 1538, 1539, 1540, 1542, 1543, 2414 Damien, N., 740, 741, 2413 Damiens, A., 68 Damir, D., 336 Dams, R., 169, 170, 171 Danan, J., 67 Dancausse, J. P., 2315, 2371, 2407 Danebrock, M. E., 66, 67, 71, 2407 Danesi, P. R., 123, 773, 2738, 2750, 3173 Danford, M. D., 1323, 1324, 1361, 1362 Dang, H. S., 3057 Daniels, W. R., 1738 Danielson, P. M., 365 Danilin, A. S., 364, 365 Danis, J. A., 1181, 2452, 2453, 2454, 2455, 2456 Danon, J., 33 Danpure, C. J., 1816, 3398 d’Ans, J., 109 Dantus, M., 97 Danuschenkova, M. A., 1129, 1130 Dao, N. Q., 477, 539, 541, 542, 547, 2441 Daoudi, A., 402, 407, 414 Darby, J. B., Jr., 90, 398, 1787, 2238 D’Arcy, K. A., 2642 Dardenne, K., 763, 766, 3040, 3138, 3149, 3158 Darken, L. S., 926, 927 Darling, T. W., 942 Darnell, A. J., 70 Darovskikh, A. N., 1363 Darr, J. A., 2678 Dartyge, J. M., 208, 2432 Das, D., 2153 Das, D. K., 67

Das, M. P., 1626, 1627 Dash, A. K., 2830, 2866, 2918, 2922, 2923, 2927, 2935, 2938, 2940, 2943, 2944, 2953, 2955, 2958, 2961, 2965, 2969, 2971, 2975, 2976, 2979 Dash, K. C., 182 Dash, S., 2157, 2158, 2209 Date, M., 100 Datta, S. K., 1447 Dauben, C. H., 67, 1312, 1313, 1315, 1357, 1358, 1645, 2386, 2395, 2396, 2407, 2417, 2422 Daudey, J.-P., 1918, 1919, 1931 Dauelsberg, H.-J., 44 Daughney, C. J., 3182, 3183 Dautheribes, J., 789 Dauvois, V., 352 David, F., 34, 37, 38, 118, 119, 167, 221, 1296, 1302, 1330, 1460, 1480, 1481, 1482, 1483, 1523, 1526, 1529, 1547, 1548, 1549, 1555, 1557, 1598, 1602, 1605, 1606, 1607, 1611, 1613, 1628, 1629, 1630, 1635, 1636, 1639, 1640, 1641, 1644, 1645, 1799, 2123, 2124, 2125, 2126, 2127, 2129, 2526, 2529, 2530, 2531, 2538, 2539, 2543, 2553, 2575, 3101, 3104, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118 David, F. H., 1991 David, S. J., 813, 1088 Davidov, A. V., 1471 Davidov, D., 2360 Davidov, Y. P., 1127 Davidovich, R. L., 541, 542 Davidsohn, J., 82, 90, 93, 105, 109 Davidson, N. R., 722, 730, 731, 736, 737, 738, 740, 1018, 1052, 1092, 1094, 1095, 1100, 1101, 2167 Davies, D., 164, 170, 1077, 1078, 1079, 1080, 1085, 1086, 1099 Davies, G., 3140, 3150 Davies, W., 633, 634 Davis, D. G., 1507 Davis, D. W., 3172 Davis, I. A., 43 Davis, J. A., 3165, 3166, 3167, 3170, 3176 Davis, J. H., Jr., 2691 Davis, T. A., 3182, 3183 Davis, T. L., 3065 Davis, T. W., 3221 Davis, W., Jr., 563 Davis, W. M., 2245 Davy, H., 2692 Davydov, A. V., 161, 167, 178, 181, 184, 185, 187, 188, 195, 207, 209, 218, 219, 229, 1323, 1423, 1625, 1633 Dawihl, W., 109 Dawson, H. M., 101, 104

Author Index

I-169

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Dawson, J. K., 342, 357, 358, 425, 431, 458, 469, 474, 484, 485, 491, 495, 1077, 1078, 1079, 1084, 1099 Day, C. S., 2476, 2479, 2482, 2484, 2809, 2811, 2832, 2841, 2843, 2916, 2919, 2924, 2997 Day, D. E., 277 Day, J. P., 496, 574, 790, 3063, 3317, 3318 Day, P. N., 2966 Day, R. A., 279, 280 Day, R. A., Jr., 115 Day, R. S., 849, 851 Day, V. W., 116, 117, 1957, 1958, 2464, 2467, 2476, 2479, 2480, 2482, 2484, 2491, 2809, 2810, 2811, 2832, 2835, 2837, 2839, 2840, 2841, 2842, 2843, 2844, 2880, 2881, 2912, 2913, 2916, 2918, 2919, 2920, 2924, 2934, 2939, 2997 Dayton, R. W., 1030 De Alleluia, I. B., 395, 1065, 1066 de Almeida Santos, R. H., 90 de Bersuder, L., 859 de Boer, E., 203 De Boer, F. R., 70, 73, 2209, 2358 de Boer, J. H., 61 de Boisbaudran, L., 77 de Bruyne, R., 113 De Carvalho, R. G., 1427, 2582 De Carvalho, R. H., 1549, 1550, 1555, 1557 de Coninck, R., 368 De Franco, M., 1048, 2145 De Grazio, R. P., 1104 de Haas, W. J., 62 De Jong, W. A., 578, 1906, 1918, 1919, 1920, 1935, 1936 De Kock, C. W., 1094, 1095, 1099, 2167, 2851 De Kock, R. L., 1916, 2089 de Leon, J. M., 1991, 3087, 3089, 3108, 3113, 3117, 3118, 3123 De Long, L. E., 338, 339 de Maayer, P., 113 De Meester, R., 2752 de Novion, C. H., 742, 743, 774, 1017, 1022, 1052, 1054, 1304, 1312, 1316, 1317, 1318, 1412, 1415, 1421, 2409, 2413, 2414 de Novion, E. H., 204, 207 de Pablo, J., 1805, 1927, 3143, 3145 De Paoli, G., 198, 452, 2419, 2420, 2449, 2452, 2479, 2483, 2484, 2826, 2843 De Paz, M. L., 2443 De Plano, A., 1803 De Rango, C., 2449, 2452 De Rege, F. M., 2868 De Regge, P., 20, 27, 31, 38, 133 De Ridder, D. J. A., 2472, 2475, 2486, 2488, 2819 de Sousa, A. S., 2577, 2590

De Trey, P., 63 De Troyer, A., 30, 32, 33 de Villardi, G. C., 2449 de Villiers, J. P. R., 3159 de Visser, A., 2351 De Vries, T., 634 De Waele, R., 2688, 2690 de Wet, J. F., 472, 477, 512, 543 De Winter, F., 818 De Witt, R., 718, 719 de Wolff, P. W., 342 Deakin, L., 2256 Deakin, M. R., 2690 Deal, K. A., 43 Deal, R. A., 167, 169, 188, 195, 230 Dean, D. J., 944, 949, 950 Dean, G., 391, 1048, 1070, 1073, 1074, 2145 Dean, J. A., 632, 633, 635, 636, 637, 3278, 3280 Dean, O. C., 61, 80 Deane, A. M., 494, 1184 Deaton, R. L., 1045 Debbabi, M., 389, 391, 393, 395, 1065, 1066, 1312, 1313 Debets, P. C., 342, 346, 357, 358, 543, 545, 2394, 2426 Debierne, A., 19, 20 Decaillon, J. G., 3034, 3037 Decambox, P., 1368, 1405, 1433, 2096, 2536, 3034, 3037 Decker, W. R., 62 Declercq, G., 2489, 2490, 2492 Declercq, J. P., 2802, 2844 Declerq, J.-P., 264, 265, 267 Dedov, V. B., 1271, 1352, 1512 Dedov, V. D., 1402, 1422, 1423, 1427 Dee, S., 3279, 3285 Deely, K. M., 267, 268, 270, 287, 291, 583 Deer, W. A., 3169 Deere, T. P., 1283, 2656 Deferne, J., 265 D’Ege, R., 198, 201 Degetto, S., 2443, 2446, 2447, 3030, 3280 Degiorgi, L., 100 Degischer, G., 771, 1352, 1477, 1551, 2585 Degueldre, C., 1812, 3013, 3016, 3026, 3037, 3039, 3062, 3066, 3069, 3070 Deissenberger, R., 60, 789, 1296, 1403, 1452, 1875, 1877 Dejean, A., 2449, 2450, 3101, 3105, 3120, 3138, 3141 Dejonghe, P., 30, 32, 33 Del Cul, G. D., 2087, 2088 Del Mar Conejo, M., 1956 del Mar Conejo, M., 2803, 2806, 2807 Del Pra, A., 2441, 2442, 2443, 2483, 2484, 2826, 2843 deLabachellerie, M., 1873 Delaeter, J. R., 164

I-170

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Delamoye, P., 81, 95, 469, 482, 491, 1663, 2066, 2067, 2248, 2250 Delapalme, A., 409, 412, 1023, 1055, 2250, 2358, 2471, 2472 Delaplane, R., 475, 495 Delavaux-Nicot, B., 2806 Delavente, F., 2657 Delegard, C., 852, 1167 Delegard, C. H., 1117, 1118 Deleon, A., 314 Delepine, M., 61, 63, 64, 80, 97 Delev, D., 3327 Deliens, M., 259, 260, 261, 262, 263, 264, 265, 268, 283, 288, 293, 294 Delin, A., 2347 Dell, R. B., 1507, 3349, 3350 Dell, R. M., 342, 357, 1018, 1019, 1020, 1050, 1051, 1052, 2238, 3215 Della Mea, G., 3064, 3065 Della Ventura, G., 261, 301 Delle Site, A., 1352 Delliehausen, C., 407 Delmau, L., 1160, 1161, 1162, 2655 Deloffre, P., 891, 917, 958 Delong, L. E., 96 Delorme, N., 1114 Delouis, H., 1840 Delpuech, J.-J., 618, 2649 Delsa, J. L., 2815 DeLucas, L. S., 1045 deLumley, M. A., 189 Demartin, F., 261, 264 Demers, P., 53 Demers, Y., 1873 Demeshkin, V. A., 2118 Demichelis, R., 1416, 1430 Demildt, A., 20, 31, 38 Demildt, A. C., 30, 32, 33 deMiranda, C. F., 162, 166, 176, 181, 182, 184, 209, 213, 215, 217, 218, 220, 221, 222, 227, 229 Dempf, D., 207, 2851 Dempster, A. J., 20, 55, 163, 256 Demtschuk, J., 2969, 2974 Demyanova, T. A., 3034 Dem’yanova, T. A., 787, 788, 1405, 1433, 2532 Den Auwer, C., 861, 932, 1041, 1043, 1112, 1154, 1155, 1166, 1168, 1262, 1270, 1321, 1923, 2532 den Auwer, C., 2858, 3101, 3109, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118, 3210 Den Haan, K. H., 2924 den Heuvel, Van Chuba, P. J., 1507, 1518 Denayer, M., 368 Denecke, M., 3040 Denecke, M. A., 118, 133, 586, 589, 1147, 1150, 1152, 1153, 1154, 1991, 2531,

2568, 2576, 3089, 3101, 3102, 3103, 3104, 3105, 3106, 3114, 3126, 3127, 3128, 3129, 3131, 3135, 3138, 3140, 3141, 3142, 3145, 3146, 3147, 3148, 3149, 3150, 3152, 3154, 3155, 3156, 3158, 3165, 3166, 3167 Denes, G., 468 Deng, D. L., 2831 Denig, R., 164 Denisov, A. F., 30, 3025 Denming, K., 1267 Denning, R. G., 546, 578, 1113, 1114, 1192, 1196, 1198, 1199, 1930, 1931, 2079, 2080, 2085, 2086, 2087, 2239, 2561 Denninger, U., 2924, 2986 Dennis, L. M., 76 Dennis, L. W., 2261 Denniss, I. S., 711, 760, 761, 2757 Denotkina, R. G., 1161, 1171, 1172 deNovion, C. H., 99, 195, 391 Dent, A. J., 301, 3103, 3152, 3154, 3155 DePaoli, G., 2801 Depaus, R., 637 dePinke, A. G., 164, 166 Deportes, J., 65, 66 Deramaix, P., 1071 Deren, P., 422, 435, 443 Derevyanko, E. P., 1554 Dergunov, E. P., 80, 86, 87, 90, 91 Deriagin, A. V., 2359 Dernier, P., 2360 Deron, S., 822, 3061 d’Errico, F., 1507 Dervin, J., 109, 131 Deryagin, A. V., 339, 2360 Desai, P. D., 2115 Desai, V. P., 382, 730, 763, 766, 2244 Deschamps, J. R., 2382, 2383, 2384 Deschaux, M., 627, 629 Desclaux, J. P., 1598, 1605, 1606, 1607, 1613, 1626, 1627, 1643, 1667, 1668, 1669, 1670, 1673, 1675, 1692, 1725, 1873 Desclaux, J.-P., 1898, 1899 Deshayes, L., 2449, 2450, 2452 Deshingkar, D. S., 1282, 2743, 2745 Desideri, D., 3030, 3280 deSilviera, E. F., 164, 166 De´sire´, B., 1425, 1476, 1477, 1550, 1551, 1554 Deslandes, B., 932, 933 Desmoulin, J. P., 533, 534, 535 Desmoulin, R., 503 Despres, J., 892, 905, 906, 907 Desreux, J. F., 2655, 2815 Desrosiers, P. J., 2849 Destriau, M., 332 Desyatnik, V. N., 86, 93 Detlefs, C., 2287, 2292 Detourmine´, R. J., 402

Author Index

I-171

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Detweiler, D. K., 3396 Deutsch, E., 2602 Deutsch, W. J., 287 Devalette, M., 77 Devillers, C., 824, 1981 Devlin, D., 2752 Devreese, J., 368 Dewald, H. D., 3108 Dewberry, R. A., 1433 Dewey, H. J., 1088, 1090, 2085, 2400, 2687, 2688, 2689 DeWitt, R., 891 Deworm, J. P., 33 Dexter, D. L., 2095, 2102 D’Eye, R. W. M., 75, 80, 82, 83, 96, 424, 458, 484, 485, 2413, 2424 D’Eye, R. W. N., 1084 Dhami, P. S., 712, 713, 1281, 1282, 1294, 2668, 2669, 2743, 2744, 2745, 2747, 2749, 2750, 2757, 2759 Dhar, S. K., 407 Dharwadkar, S. R., 355, 356, 369, 2153, 2195 Dhers, J., 195, 196, 216 Dhumwad, R. K., 1282, 2743, 2744, 2745 D’Huysser, A., 76 Di Bella, S., 576, 1953, 1956, 1957, 1958 Di Bernardo, P., 1178, 1181, 2441, 2568, 2584, 2585, 2586, 2589, 3102, 3143, 3145 Di Cola, D., 2283, 2284, 2285 di Cresswell, R. G., 3317, 3318 Di Napoli, V., 2585, 2586 Di Paoli, G., 200, 201 Di Salvo, F. J., 98 Di Sipio, L., 546, 547, 553, 554 Di Tada, M. L., 3063 Diaconescu, P. L., 1966, 1967, 2488, 2491, 2859, 2861, 2888 Diakonov, I. I., 2191, 2192 Diakov, A. A., 1432, 1433 Diamond, G. L., 1821 Diamond, H., 5, 633, 1152, 1279, 1280, 1281, 1293, 1294, 1466, 1508, 1511, 1517, 1544, 1577, 1588, 1622, 1626, 2642, 2652, 2653, 2655, 2660, 2661, 2727, 2738, 2739, 2742, 2760, 2768, 3283, 3284, 3285, 3286, 3295 Diamond, R. M., 1916, 2538, 2562, 2580 Diamond, R. M. K., 2635, 2670 Dianoux, A.-J., 423, 445, 503, 505, 506, 2243, 2246 Dias, A. M., 2236 Dias, R. M. A., 2442 Diatokova, R. A., 1547, 1548 Dick, B. G., 2052 Dickens, M. H., 357 Dickens, P. G., 385, 388, 2390, 2394 Didier, B., 3165, 3166, 3167 Diebler, H., 2602

Diego, F., 371 Diehl, H., 111 Diehl, H. G., 393, 395 Dieke, G. H., 1896, 2015, 2036, 2038, 2078 Diella, V., 264 Diener, M. D., 2864 Dietrich, M., 64, 97 Dietrich, T. B., 301 Dietz, M. L., 633, 1293, 1294, 1508, 1511, 2652, 2660, 2661, 2691, 2727, 3283, 3284, 3286, 3295 Dietz, N. L., 270, 297, 3017, 3302 Dietze, H.-J., 3062, 3069, 3310, 3311 Diguisto, R., 620 Dilley, N. R., 100 Dimmock, J. O., 1913 Diness, A. M., 77 Ding, M., 861, 1041, 1043, 1112, 1154, 1155, 1166, 3109, 3210 Ding, Z., 3126 Dion, C., 298, 301 Diprete, C. C., 1401 Diprete, D. P., 1401 Dirac, P. A. M., 1898, 1904 Diri, M. I., 2315, 2355, 2368, 2369 Dittmer, D. S., 3357, 3358 Dittner, P. E., 1504, 1516, 1583, 1590, 2561, 2585 Dittner, P. F., 1452, 1626, 1627, 1637, 1638, 1639, 1640, 1644, 1659 Dittrich, S., 776 Ditts, R. V., 634 Divis, M., 2359 Dixon, D. A., 1906, 1918, 1919, 1920 Dixon, N. E., 3117 Dixon, P., 822, 823, 3279, 3314 Dixon, S. N., 166, 178, 182, 183 Djogic, R., 584, 601, 3130 Dmitriev, S. N., 786, 822, 1720 Dobretsov, V. N., 2140 Dobrowolski, J., 1066, 1068 Dobry, A., 123 Dock, C. H., 81 Dockum, J. G., 1579, 3343, 3349 Dockum, N., 3349, 3398, 3399 Docrat, T. I., 588, 595, 1927, 1928, 2583, 3132 Dod, R. L., 191, 193, 194, 201 Dode´, M., 353, 354, 355, 356, 360, 362, 363 Dodge, C. J., 2591, 3022, 3046, 3069, 3146, 3179, 3181 Dodge, R. P., 201, 2419, 2420, 2424 Dodgen, H. W., 857 DOE, 817, 3255, 3258, 3260, 3261, 3262, 3263 Doern, D. C., 3167 Does, A. V., 226 Dognon, J.-P., 1921, 1922 Dohnalkova, A., 274, 3179, 3181 Doi, K., 2392, 2418

I-172

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Dojiri, S., 837 Dok, L. D., 1629, 1635 Dolechek, R. L., 193 Dolejsek, V., 226 Dolezal, J., 3278 Dolg, M., 34, 1646, 1670, 1671, 1676, 1679, 1682, 1683, 1689, 1898, 1907, 1908, 1918, 1920, 1937, 1943, 1944, 1947, 1948, 1949, 1951, 1952, 1959, 1960, 2148 Dolidze, M. S., 1449 D’Olieslager, W., 2603, 2605, 2606, 2688, 2690 Dolling, G., 2233, 2274, 2276, 2277, 2281 Domanov, V. P., 1036, 1628, 1634, 1664, 1690, 1703, 1932 Domingos, A., 2880, 2881, 2882, 2883, 2884, 2885, 2886 Dominik, J., 3016, 3022 Domke, M., 2359 Donato, A., 2633 Dong, C. Z., 1670, 1672, 1673, 1674, 1675, 1840, 1877, 1884 Dong, W., 791 Dong, Z., 3065 Doni, A., 428, 436, 440, 444, 451 Donnet, L., 1355 Donohoe, R. J., 851, 1116, 1117, 1156, 1925, 1926, 2464, 2607, 3126, 3127, 3128, 3171 Donohue, D., 3173 Donohue, D. L., 3321 Donohue, J., 321 Donohue, R. J., 580, 595, 620, 621 Donzelli, S., 264 Dooley, G. J., 68 Doppler, U., 1880, 1882 Dorain, P. B., 2243 Dordevic, S. V., 100 Doretti, L., 2843 Dorhaut, P. K., 3210 Dorhout, P. K., 52, 97, 398, 861, 998, 1041, 1043, 1112, 1154, 1155, 1166, 3109 Dorion, P., 2843 Dormeval, M., 886, 887, 930, 932, 954, 956 Dormond, A., 2464, 2465, 2466, 2825, 2877, 2889, 2890 Dornberger, E., 102, 108, 117, 423, 445, 448, 1168, 1323, 1324, 1423, 2240, 2254, 2255, 2260, 2264, 2441, 2470, 2472, 2486, 2488, 2489, 2801, 2808, 2809, 2815, 2817, 2826 Dornho¨fer, H., 1738 Dosch, R. G., 1292 Doubek, N., 3061 Dougan, A. D., 1639, 1641 Dougan, R., 1636 Dougan, R. J., 1639, 1641, 1647 Dougherty, J. H., 3424

Dougherty, T. F., 3343, 3424 Douglas, M., 1906 Douglas, R. M., 275, 465, 466, 474 Douglass, M. R., 2984 Douglass, R. M., 1004, 1007, 1104, 1105, 1106, 1107, 1109, 1171, 2432, 2433 Doukhan, R., 932, 933 Dounce, A. L., 3351, 3355, 3359, 3360, 3362, 3380, 3381, 3382 Douville, E., 3022 Dow, J. A., 2655, 2738, 2739 Dowdy, E. D., 2984 Downer, M. C., 2078 Downes, A. B., 3016, 3023 Downs, A. J., 530, 1968 Doxater, M. M., 3034, 3037 Doxtader, M. M., 2096, 2536 Doye, S., 2982 Doyle, J. H., 958, 959 Dozol, J. F., 2655 Dozol, J.-F., 2655 Dra´bek, M., 2427 Draganic, I. G., 3221 Draganic, Z. D., 3221 Drago, R. S., 2576, 2577 Dragoo, A. L., 53, 67 Drake, J., 789, 3314 Drake, V. A., 2732, 2757 Dran, J. C., 3064, 3160 Draney, E. C., 942, 943, 944, 946 Drchal, V., 929, 953, 2355 Drehman, A. J., 2351 Dreissig, W., 2452 Dreitzler, R. M., 2327 Dresel, P. E., 3027 Dresler, E. N., 1431 Dressler, C. E., 1662, 1684, 1711, 1712, 1716 Dressler, P., 760 Dressler, R., 1447, 1662, 1664, 1679, 1684, 1685, 1699, 1707, 1708, 1709, 1713, 1714, 1716 Dretzke, A., 33, 1882, 1883 Dretzke, G., 1840, 1877, 1884 Drew, M. G. B., 1262, 1270, 1285, 2457, 2584, 2657, 2659, 2674, 2761 Drew Tait, C., 291 Dreyer, R., 776, 1352 Dreze, C., 1873 Driessen-Ho¨lscher, B., 2982 Drifford, M., 2243 Driggs, F. D., 2712 Dringman, M. R., 1028, 1029, 1030, 3207 Driscoll, W. J., 1275, 2650, 2672 Drobot, D. V., 81 Drobyshevskii, I. V., 1312, 1315, 1327, 2421 Drobyshevskii, Y. V., 731, 732, 734, 736 Droissart, A., 30, 31, 32, 33, 35, 42, 43

Author Index

I-173

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Dronskowski, R., 88, 94 Drot, R., 3046, 3171 Drowart, J., 322, 364, 365, 2114, 2203, 2204 Drozcho, E., 3063 Drozdova, V. M., 516 Drozdzynski, J., 253, 421, 422, 425, 426, 427, 428, 429, 430, 431, 432, 433, 434, 435, 436, 437, 438, 439, 440, 442, 443, 444, 445, 446, 447, 448, 449, 450, 451, 453, 454, 482, 483, 493, 2064, 2066, 2103, 2230, 2259, 2260 Drozhko, E. G., 1821 Droznik, R. R., 1412, 1413, 1519, 1520, 1521 Druckenbrodt, W. G., 839, 852 Druin, V. A., 164, 1629, 1641 Drulis, H., 334, 335, 338, 339 Drummond, D. K., 2924 Drummond, J. L., 1004, 1007, 1008, 1031, 1032, 1034 Drummond, M. L., 1969, 1979 D’Silva, A., 3036 du Jassonneix, B., 66 Du Mond, J. W. M., 859 Du Plessis, P. D. V., 2280, 2294 du Preez, A. C., 1168 du Preez, J. G. H., 94, 202, 204, 439, 472, 477, 482, 492, 496, 498, 499, 510, 522, 524, 543, 574, 2880 Dubeck, L. W., 63 Dubeck, M., 116 Dubinchuk, V. T., 268, 298 Duboin, A., 75, 78, 94, 95 Dubos, S., 1300 Dubrovskaya, G. N., 96 Duchamp, D. J., 462 Duchi, G., 269 Duckett, S. B., 2966 Ducroux, R., 396 Dudney, N. J., 369 Dudwadkar, N. L., 2750 Dueber, R. E., 385, 388 Duesler, E. N., 2573 Duff, M. C., 270, 274, 861, 3095, 3165, 3166, 3168, 3174, 3175, 3176, 3177, 3178, 3179, 3181 Duffey, D., 1507 Duffield, J., 3364, 3365, 3377, 3379, 3397, 3399 Duffield, J. R., 131, 132, 3340, 3398, 3410, 3422, 3424 Dufour, C., 192, 194, 725, 743, 1300, 1313, 1411, 1458, 1459, 1462, 1520, 1521, 1522, 2315, 2370 Dufour, J. P., 1738 Dufour, S., 1304 Dugne, O., 340, 351, 352, 353, 354, 355, 356, 363

Dugue, C. P., 3288 Duke, M. J. M., 3057 Dukes, E. K., 763, 764 Du¨llman, C. E., 1662, 1664, 1684, 1685, 1711, 1712, 1713, 1714, 1716, 1721, 1732 Du¨llmann, C. E., 1507 Du¨llmann, Ch. E., 1447 Dumas, B., 3016 Dumazet-Bonnamour, I., 2458, 2463 Dumont, G., 30, 32 Dunbar, R. B., 3159 Duncalf, D. J., 2912 Duncan, H. J., 3106 Dunlap, B. D., 719, 721, 739, 742, 743, 744, 745, 861, 862, 1297, 1304, 1317, 1319, 1542, 1543, 2230, 2269, 2271, 2283, 2292, 2308, 2361 Dunlop, J. W. C., 2457 Dunlop, W. H., 3266 Dunn, M., 3022, 3181 Dunn, S. L., 726 Dunogues, J., 2953 Dunster, J., 1818, 1819, 1820 Dupleissis, J., 183, 184, 768, 1605, 2529, 2530, 2538, 2539, 3024 Dupuis, M., 1908 Dupuis, T., 76, 109, 114 Dupuy, M., 958, 959, 960 Durakiewicz, T., 1056, 2347 Duran, T. B., 1268 Durand, P., 1907 Durbin, P., 3413, 3414, 3417, 3418, 3421 Durbin, P. N., 3419, 3421 Durbin, P. W., 1813, 1817, 1819, 1823, 1824, 1825, 2591, 3339, 3340, 3341, 3343, 3344, 3346, 3348, 3349, 3353, 3355, 3358, 3359, 3361, 3364, 3366, 3368, 3369, 3371, 3372, 3373, 3374, 3375, 3378, 3379, 3382, 3385, 3387, 3388, 3389, 3390, 3391, 3392, 3393, 3394, 3395, 3396, 3400, 3401, 3403, 3405, 3406, 3407, 3409, 3413, 3414, 3415, 3416, 3417, 3418, 3419, 3420, 3421, 3423, 3424 Duriez, C., 724 Durif, A., 113 Duro, L., 1805 Durrett, D. G., 376, 377, 378, 382, 501, 513, 526, 528, 2243 Dusausoy, Y., 602, 2431 Dushenkov, S., 2668 Dushin, R. B., 1365, 1369 Du¨sing, W., 97 Duttera, M. R., 2479, 2480, 2810, 2835, 2919 Duval, C., 76, 109, 114 Duval, P. B., 2845, 2846 Duverneix, T., 724

I-174

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Duyckaerts, E., 1352 Duyckaerts, G., 31, 116, 117, 725, 728, 729, 1177, 1178, 1413, 1414, 1419, 1607, 2396, 2397, 2413, 2695, 2696, 2697, 2698, 2699, 2700, 2815, 2819, 2844, 2851 Dvoryantseva, G. G., 105 Dworschak, H., 2767 Dworzak, W. R., 996 Dwyer, O. E., 854, 2710 Dyachkova, R. A., 1515, 1629 D’yachkova, R. A., 180, 184, 188, 209, 214, 218, 219, 224, 226, 1473 Dyall, K. G., 578, 1196, 1198, 1728, 1906, 1917, 1918, 1919, 1933, 1939, 1940, 1942, 1976 Dye, D. H., 412 Dygert, H. P., 3354 Dyke, J. M., 1897, 1938, 1972, 1973, 1974, 1975 Dyrssen, D., 2669, 2670 Dyve, J. E., 1666, 1695, 1702, 1717, 1735 Dzekun, E., 2739 Dzhelepov, B. S., 26 Dzielawa, J. A., 2691 Dzimitrowickz, D. J., 123, 126 Dzyubenko, V. I., 1416, 1430 Eakins, I. D., 28, 31 Earnshaw, A., 162, 998, 2388, 2390, 2400, 2407 Easey, J. F., 81, 82, 194, 201, 202, 203, 204, 473, 494, 497, 734, 736, 738, 2195, 2424, 2425, 2426 Easley, W., 2016, 2062, 2063, 2064, 2075, 2077, 2079, 2231, 2265, 2266 Easley, W. C., 2263 Eastman, D. E., 64 Eastman, E. D., 95, 96, 413, 452 Eastman, M. P., 382, 506, 2241, 2243, 2244, 2246 Eastman, P., 501, 503, 504, 520 Ebbe, S. N., 3417, 3419, 3421 Ebbinghaus, B., 113, 2157, 2159, 2195 Ebbinghaus, B. B., 1036, 1047 Ebbsjo¨, I., 63 Eberhardt, C., 1840, 1877, 1884 Eberhardt, K., 33, 60, 859, 1296, 1403, 1452, 1513, 1588, 1590, 1662, 1664, 1666, 1685, 1687, 1695, 1702, 1710, 1713, 1714, 1716, 1717, 1718, 1735, 1840, 1875, 1877, 1879, 1880, 1881, 1882, 1883, 1884, 3047, 3321 Eberle, S. H., 776, 777, 779, 780, 781, 782, 1178, 1180, 1323, 1352, 1428, 1431, 1552, 2585 Eberspracher, T. A., 2880, 2881 Ebert, W. L., 276, 292, 3171 Ebihara, M., 636, 1267

Ebihara, W. M., 3306 Ebner, A. D., 1292, 2752 Eby, R. E., 3312 Eccles, H., 589, 2441, 2442, 2447, 2448 Economou, T., 1398, 1421, 1433 Edelman, F., 2883 Edelman, F. T., 575 Edelman, M. A., 116, 1954, 1955, 2240, 2473, 2479, 2480, 2484, 2803, 2816, 2830, 2844, 2912 Edelmann, F., 1957, 2472, 2825, 2826, 2852, 2875, 2919 Edelmann, F. T., 2469, 2912, 2918, 2923 Edelson, M. C., 637 Edelstein, N., 731, 732, 733, 734, 751, 1188, 1312, 1315, 1327, 1330, 1338, 1363, 1370, 1411, 1469, 1525, 1526, 1529, 1542, 1543, 1549, 1555, 1557, 1602, 1606, 1628, 1629, 1635, 1640, 1644, 1645, 1753, 1790, 2016, 2020, 2050, 2061, 2062, 2063, 2064, 2065, 2066, 2067, 2068, 2074, 2075, 2077, 2079, 2080, 2083, 2084, 2096, 2123, 2143, 2144, 2227, 2230, 2231, 2233, 2240, 2243, 2244, 2245, 2246, 2247, 2248, 2249, 2251, 2253, 2256, 2261, 2262, 2263, 2264, 2265, 2266, 2269, 2270, 2272, 2276, 2292, 2293, 2420, 2426, 2486, 2488, 2803, 2809, 2810, 2812, 2819, 2851, 2853, 3037 Edelstein, N. M., 1, 34, 37, 94, 116, 118, 162, 203, 204, 208, 209, 287, 289, 382, 422, 425, 428, 429, 430, 436, 440, 442, 447, 450, 451, 453, 466, 469, 472, 476, 479, 482, 491, 492, 496, 498, 499, 501, 512, 515, 524, 527, 579, 585, 589, 602, 795, 1112, 1113, 1166, 1187, 1398, 1403, 1419, 1776, 1921, 1923, 1946, 1947, 1954, 1955, 2020, 2042, 2047, 2054, 2058, 2059, 2060, 2062, 2064, 2075, 2079, 2096, 2225, 2240, 2251, 2262, 2265, 2266, 2269, 2397, 2404, 2405, 2473, 2530, 2531, 2532, 2558, 2561, 2568, 2576, 2580, 2583, 3095, 3101, 3102, 3103, 3104, 3106, 3107, 3110, 3111, 3113, 3114, 3115, 3117, 3118, 3119, 3122, 3130, 3131, 3135, 3138, 3140, 3141, 3142, 3145, 3146, 3147, 3149, 3150, 3152, 3154, 3155, 3156, 3160, 3165, 3166, 3167, 3369, 3385, 3388, 3390, 3391, 3394, 3417, 3423 Edghill, R., 273 Edgington, D. N., 390 Eding, H. J., 398 Editors, 1076 Edmiston, M. J., 588, 595, 1927, 1928, 2583, 3132 Edmonds, H. N., 231, 3314

Author Index

I-175

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Edmunds, T., 3265 Edmunds, T. A., 3266 Edwards, G. R., 958, 959, 960, 961 Edwards, J., 435, 737, 738, 1084, 2422, 2843, 2880 Edwards, P. G., 116, 2867, 2923 Edwards, R. K., 352, 353, 365, 1074 Edwards, R. L., 171, 231, 638, 3311, 3312, 3313, 3314 Effenberger, H., 266, 281, 3159, 3163 Efimova, N. S., 791, 3049, 3052 Efremov, Y. V., 1292, 1504 Efremov, Yu. V., 1448, 1449 Efremova, A., 111 Efremova, K. M., 372, 373, 374, 375, 383 Efurd, D. W., 704, 789, 3133, 3288, 3312, 3314 Egami, T., 3107 Egan, J. J., 854 Eggerman, W. G., 1190, 2801, 2807 Eggins, S. M., 3326 Egorov, O., 3285 Egunov, V. P., 1422 Ehemann, M., 67 Ehman, W. D., 3291, 3299, 3303 Ehrfeld, U., 557 Ehrfeld, W., 557 Ehrhardt, J. J., 3171 Ehrhart, J. J., 3046 Ehrhart, P., 981, 983 Ehrlich, P., 1532 Ehrmann, W., 114 Eichberger, K., 501, 515, 527, 2080, 2227, 2243, 2244 Eichelsberger, J. F., 30, 32, 962 Eichhorn, B. W., 1181, 2452, 2453, 2454, 2455, 2456 Eichler, B., 1447, 1451, 1468, 1507, 1523, 1524, 1593, 1612, 1628, 1643, 1662, 1664, 1679, 1683, 1684, 1685, 1693, 1698, 1699, 1706, 1707, 1708, 1709, 1711, 1712, 1713, 1714, 1716, 1721, 1732 Eichler, E., 1664, 1684, 1693, 1694, 1706, 1716 Eichler, R., 1447, 1507, 1593, 1612, 1662, 1664, 1684, 1685, 1708, 1709, 1711, 1712, 1713, 1714, 1716, 1721 Eichler, S. B., 1593 Eick, H. A., 421, 718, 997, 998, 999, 1000, 1001, 1002, 1312, 1321, 1534, 1798, 2407 Eicke, H. F., 3296 Eigen, M., 2564, 2602 Eigenbrot, C. W., 2919 Eigenbrot, C. W., Jr., 2471, 2472, 2474, 2478, 2479, 2830, 2832 Eikenberg, J., 3024, 3029, 3030, 3283, 3293, 3296 Eikenberger, J., 3070 Einspahr, H., 321

Einstein, A., 1577 Eisen, M., 1182 Eisen, M. S., 2479, 2799, 2830, 2834, 2835, 2866, 2911, 2913, 2914, 2918, 2922, 2923, 2925, 2927, 2930, 2932, 2933, 2935, 2936, 2938, 2940, 2943, 2944, 2950, 2953, 2955, 2958, 2961, 2965, 2969, 2971, 2972, 2975, 2976, 2979, 2984, 2987, 2999, 3002, 3003 Eisenberg, D. C., 1188, 1189, 2855, 2856 Eisenberg, R., 2979 Eisenberger, P., 3087 Eisenstein, J. C., 765, 1915, 2080, 2227, 2239, 2241, 2243 Eisenstein, O., 1957 Ekberg, C., 119, 120, 121, 122, 123, 124 Ekberg, S., 1927, 1928, 1968, 2165 Ekberg, S. A., 289, 595, 602, 763, 766, 1116, 1117, 1164, 1166, 1359, 2583, 3130, 3131, 3133, 3134, 3160, 3167 Ekeroth, E., 371 Ekstrom, A., 521, 615 El- Ansary, A. L., 3035 El Bouadili, A., 2825, 2877 El Ghozzi, M., 87, 90 El Manouni, 3419, 3421 Elbert, S. T., 1908 Elder, R. C., 3107, 3108 El-Dessouky, M. M., 180 Elesin, A. A., 1352, 1405, 1427, 1428, 1433, 1512, 1585, 2652 Elfakir, A., 110 El-Ghozzi, M., 88, 91 Eliav, E., 33, 1643, 1659, 1669, 1670, 1672, 1673, 1675, 1723, 1724, 1726, 1729, 1730, 1731 Eliet, V., 3037 Eliseev, A. A., 114, 417, 2439, 2444 Eliseev, S. S., 525 Eliseeva, O. P., 188 El-Issa, B. D., 1959 El-Khatib, S., 942, 944, 945, 948 Ellender, M., 1179, 2591, 3354, 3415, 3416, 3419, 3420, 3421 Ellens, A., 442 Eller, M. J., 3089 Eller, P. G., 103, 112, 501, 502, 503, 504, 506, 519, 520, 528, 732, 733, 734, 1049, 1058, 1059, 1060, 1062, 1082, 1397, 1398, 2153, 2161, 2420, 2451, 2452, 2531, 3035, 3036, 3101, 3111, 3122, 3152, 3155, 3156, 3163, 3165, 3169 Ellern, A., 588 Ellert, G. V., 416, 417, 575 Elless, M. P., 3172 Ellinger, F. H., 329, 879, 882, 883, 885, 887, 892, 894, 895, 896, 898, 900, 901, 902, 903, 904, 905, 906, 907, 908, 909, 910,

I-176

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 911, 912, 913, 914, 915, 933, 936, 938, 984, 993, 994, 1003, 1004, 1005, 1006, 1009, 1011, 1012, 1014, 1015, 1020, 1027, 1028, 1029, 1030, 1045, 1048, 1070, 1112, 1164, 1295, 1297, 1302, 1312, 1357, 1359, 1360, 1419, 1463, 2386, 2395, 2397, 2403, 2407, 2418, 2427, 3213, 3238 Elliot, R. P., 408, 409 Elliott, R. M., 1078, 1079 Elliott, R. O., 719, 720, 879, 883, 892, 896, 897, 913, 932, 936, 938, 939, 941, 947, 948, 949, 955, 957, 981 Ellis, A. M., 1972 Ellis, D. E., 1194, 1682, 1916, 1933, 1938, 1966, 2561 Ellis, J., 119, 120, 121, 123, 124, 126, 2575 Ellis, P. J., 3117 Ellis, W., 2281, 2282 Ellis, Y. A., 170 Ellison, A. J. G., 276, 3052 Ellison, R. D., 488 Elmanouni, D., 2591 Elmlinger, A., 172, 178, 224, 225 El-Rawi, H., 2605 El-Reefy, S. A., 184 Elschenbroich, Ch., 2924 Elsegood, M. R. J., 2452 Elson, R. E., 80, 162, 172, 175, 181, 201, 209, 219, 220, 509, 2389, 2391, 2419, 2420, 2424 Elson, R. F., 191, 192, 193, 194, 195, 196, 198, 201, 206, 207, 229 El-Sweify, F. H., 181 Ely, N., 2472, 2819, 2820 El-Yacoubi, A., 102, 110 Elyahyaoui, A., 3024 El-Yamani, I. S., 186 Elzinga, E. J., 3170 Embury, J. D., 964 Emelyanov, A. M., 576, 1994 Emel’yanov, N. M., 93 Emerson, H. S., 1809 Emerson, S., 3159 Emery, J., 2074 Emiliani, C., 170 Emmanuel-Zavizziano, H., 174, 191 Enarsson, A., 2584, 2674, 2761 Enderby, J. E., 2603 Endoh, Y., 2239, 2352 Eng, P., 861, 3089, 3095, 3175, 3176, 3177 Engel, E., 1671 Engel, G., 113 Engel, T. K., 1048 Engeler, M. P., 2832, 2974 Engelhardt, J. J., 34 Engelhardt, U., 1283, 2472, 2656, 2826 Engelmann, Ch., 782, 786, 3056, 3057

Engerer, H., 389, 391, 393, 395, 1065, 1066, 1069, 1312, 1313 Engkvist, I., 129, 130, 3024 England, A. F., 2832 Engle, P. M., 28, 32 Engleman, R. J., 1844, 1863 Engleman, R., Jr., 1840, 1843, 1844, 1845, 1846 Engler, M. J., 1507 Engles, M., 63 English, A. C., 53 English, J. J., 1049 Engmann, R., 342 Enin, E. A., 1416, 1430 Ennaciri, A., 113 Enokida, Y., 712, 795, 2594, 2678, 2679, 2681, 2684, 2738 Enriquez, A. E., 1069 Ensley, B. D., 2668 Ensor, D. D., 502, 503, 519, 528, 1287, 1352, 1354, 1446, 1449, 1455, 1456, 1468, 1469, 1474, 1485, 1529, 1533, 1543, 1545, 1579, 1596, 1600, 1601, 2420, 2560, 2562, 2563, 2564, 2565, 2566, 2572, 2590, 2663, 2675, 2677, 2761 Ephritikhine, M., 576, 582, 583, 1182, 1960, 1962, 2246, 2254, 2472, 2473, 2479, 2480, 2484, 2488, 2490, 2491, 2801, 2805, 2806, 2807, 2808, 2812, 2818, 2819, 2820, 2822, 2824, 2830, 2837, 2841, 2843, 2847, 2856, 2857, 2858, 2859, 2861, 2862, 2866, 2869, 2870, 2871, 2872, 2889, 2891, 2892, 2912, 2922, 2923, 2938, 2940, 2943, 2944, 2950, 2975, 2976, 2979, 3101, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118 Erann, B., 194 Erbacher, O., 24, 25 Erdman, B., 445 Erdman, N., 1403 Erdmann, B., 194, 907, 908, 910, 911, 1304, 1412, 1413 Erdmann, N., 60, 859, 1296, 1452, 1513, 1524, 1588, 1590, 1840, 1875, 1876, 1877, 3032, 3047, 3321 Erdo¨s, P., 421, 444, 448, 1055, 1784, 1785, 2276, 2283, 2288 Erdtmann, G., 3274, 3277 Erdtmann, G. L., 188 Eremin, M. V., 2049, 2053 Erez, G., 936, 943, 944 Erez, J., 3159 Erfurth, H., 375, 376, 378, 382, 384, 385, 388, 389, 391, 392 Erickson, M. D., 3280, 3323, 3327 Ericsson, O., 190 Eriksen, T. E., 768

Author Index

I-177

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Eriksson, O., 63, 191, 924, 925, 928, 934, 935, 1300, 1301, 1894, 2248, 2289, 2291, 2313, 2318, 2330, 2347, 2348, 2355, 2359, 2364, 2370, 2384 Erilov, P. E., 1082 Erin, E. A., 1326, 1329, 1331, 1416, 1429, 1448, 1449, 1466, 1476, 1479, 1480, 1481, 1483, 1484, 1512, 1545, 1549, 1559, 2126, 2584 Erin, I. A., 2129, 2131 Erker, G., 2837, 2841 Erleksova, E. V., 3350, 3353 Erlinger, C., 2649, 2657 Ermakov, V. A., 1331, 1333, 1334, 1335, 1336, 1337, 1352, 1402, 1422, 1423, 1550, 1553 Ermakovl, V. A., 1629 Ermeneux, F. S., 2100 Ermler, W. C., 1671, 1898, 1907, 1908, 1918, 1920, 1943, 1946, 1949, 1951, 1952, 2864 Ermolaev, N. P., 2575 Ernst, R. D., 116, 750, 2469, 2476, 2484, 2491, 2843, 2865 Ernst, R. E., 2844 Ernst, S., 2532, 2533 Erre, L., 2440 Errington, W., 2440 Errington, W. B., 1963 Ertel, T. S., 3087 Erten, H. N., 131, 132 Ervanne, H., 3066 Esch, U., 399 Eshaya, A. M., 854 Esimantovskiy, V. M., 2739 Eskola, K., 6, 1639, 1641, 1660, 1662, 1692 Eskola, P., 6, 1639, 1641, 1660 Esmark, H. M. T., 52 Espenson, J. H., 595, 606, 619, 620, 630, 2602 Esperas, S., 108, 549, 571, 1173, 1921, 2532 Espinosa, G., 1432 Espinosa-Faller, F. J., 861, 932, 1041, 1043, 1112, 1154, 1155, 1166, 3109, 3210 Espinoza, J., 2749 Essen, L. N., 129, 132, 2585 Esser, V., 3052 Essington, E., 3017 Essling, A. M., 3284 Esterowitz, L., 2044 Esteruelas, M. A., 2953 E´tard, A., 61, 63, 67, 68, 78, 80, 81, 82, 95 Etourneau, J., 67, 70, 71, 73, 2360 Etter, D. E., 487, 903 Ettmayer, P., 67, 70 Etz, E. S., 634 Etzenhouser, R. D., 2452 Eubanks, I. D., 1411, 1412 Evans, C. V., 231, 635, 3300, 3301

Evans, D. F., 2226 Evans, D. S., 98 Evans, H. M., 3341, 3342, 3353 Evans, H. T., 265, 266 Evans, H. T., Jr., 583, 2434, 2486, 3118 Evans, J. E., 166, 1586, 1839, 1850, 1885 Evans, J. H., 2116 Evans, J. S. O., 942 Evans, K. E., 1507 Evans, S., 1681 Evans, S. K., 1045 Evans, W. E., 34 Evans, W. H., 2114 Evans, W. J., 1956, 1967, 2473, 2476, 2477, 2804, 2805, 2816, 2857, 2924 Everett, N. B., 3358 Evers, C. B. H., 66, 67, 71, 2407 Evers, E. C., 485 Everson, L., 2655, 2738, 2739 Evstaf’eva, O. N., 105 Ewart, F. T., 786, 787, 3043, 3044 Ewing, R. C., 55, 103, 113, 257, 259, 260, 262, 269, 270, 271, 272, 273, 274, 275, 277, 278, 280, 281, 283, 287, 288, 289, 290, 292, 293, 294, 298, 2157, 2159, 2193, 2426, 3093, 3094, 3118, 3155, 3160 Eyal, Y., 278 Eyman, L. D., 2591 Eymard, S., 2655 Eyring, H., 367 Eyring, L., 1029, 1037, 1039, 1044, 1303, 1312, 1313, 1323, 1358, 1419, 1420, 1466, 1535, 1536, 1538, 1596, 1598, 1599, 1613, 2143, 2169, 2309, 2381, 2390, 2391, 2392, 2395, 2396, 2397, 2398, 2399, 3207, 3208, 3209, 3211, 3212 Ezhov, Yu. S., 2177 Faber, J., 2275 Faber, J., Jr., 353, 357, 2274, 2275, 2276 Fabryka-Martin, J., 822, 823, 3279, 3280, 3282, 3314 Facchini, A., 2657, 2675, 2756 Faegri, J., 34 Faegri, K., 1670, 1682, 1683, 1723, 1727, 1728, 1905 Faestermann, T., 3016, 3063 Fagan, P. J., 116, 117, 2479, 2481, 2482, 2809, 2810, 2811, 2827, 2832, 2837, 2838, 2839, 2841, 2842, 2913, 2916, 2919, 2924, 2997 Fahey, J. A., 724, 725, 726, 740, 1414, 1420, 1421, 1457, 1458, 1459, 1460, 1463, 1464, 1465, 1466, 1467, 1470, 1471, 1528, 1530, 1534, 1536, 1541, 2178, 2180, 2388, 2389, 2397, 2398, 2399, 3124

I-178

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Faiers, M. E., 918, 919 Faile, S. P., 343 Fair, C. K., 2479, 2841 Fairbanks, V. F., 3358, 3364, 3397, 3398, 3399 Faircloth, R. L., 724, 1030, 1045, 1046, 1048, 2148, 2149 Fairman, W. B., 1293 Fairman, W. D., 184, 3284 Fajans, K., 162, 163, 170, 187, 254 Falan, T., 265 Falanga, A., 932, 933 Faleschini, S., 2843 Falgueres, C., 189 Faller, J. W., 2943 Fallon, S. J., 3047 Falster, A. U., 269, 277 Fan, S., 2752 Fang, A., 1953, 1958 Fang, D., 1312, 1319 Fang, K., 191 Fangding, W., 1141 Fangha¨nel, T., 120, 125, 126, 223, 421, 423, 425, 435, 439, 440, 441, 457, 458, 469, 473, 474, 477, 478, 480, 481, 497, 502, 503, 509, 513, 514, 515, 516, 517, 536, 538, 543, 544, 545, 551, 552, 556, 593, 594, 595, 596, 597, 598, 599, 601, 602, 603, 1113, 1147, 1148, 1149, 1150, 1152, 1153, 1154, 1156, 1158, 1160, 1161, 1165, 1166, 1181, 1425, 1426, 1427, 1933, 2115, 2117, 2120, 2126, 2127, 2128, 2132, 2136, 2137, 2138, 2142, 2144, 2151, 2152, 2153, 2154, 2155, 2157, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2170, 2171, 2174, 2175, 2176, 2179, 2181, 2182, 2186, 2187, 2190, 2191, 2192, 2193, 2194, 2195, 2197, 2200, 2203, 2204, 2206, 2538, 2546, 2554, 2587, 2592, 3045, 3102, 3112, 3114, 3125, 3140, 3143, 3144 Fankuchen, I., 2399 Fannin, A. A. J., 2686 Fano, U., 2336 Faraglia, G., 2843 Farah, K., 176, 185 Farber, D. L., 964, 965, 2342 Farbu, L., 2662 Fardy, J. J., 1168, 1448, 1449, 1479, 1480 Fargeas, M., 1316, 1416, 1418 Farges, F., 270, 276, 277, 3094, 3152, 3153, 3154 Farina, F., 2471, 2472 Faris, J. P., 848 Farkas, I., 596, 597, 608, 609, 612, 613, 614, 2587, 3101, 3102, 3103, 3104, 3105, 3126, 3127, 3128, 3138, 3149 Farkas, M. S., 1069, 1070

Farkes, I., 133 Farley, N. R. S., 3108 Farnham, J. E., 3403, 3404 Farnsworth, P. B., 67, 2407 Farr, D., 1043, 3210, 3211 Farr, J. D., 30, 34, 35, 2385 Farrant, D., 1071 Farrar, L. G., 1449 Farrell, M. S., 2735 Farrow, L. C., 3024, 3364, 3379 Fassett, J. D., 3320 Fauble, L. G., 34 Faucher, M., 2049 Faucher, M. D., 482, 2050, 2054, 2066 Faucherre, J., 109, 131 Fauge´re, J.-L., 1269 Faure, P., 932, 933 Fauske, H. K., 3234, 3255 Fauth, D. J., 3282, 3285, 3293, 3295, 3296 Fauve-Chauvet, A., 43 Fava, J., 77 Favarger, P. Y., 3062 Favas, M. C., 1174, 2441 Fawcett, J., 536, 539 Fayet, J. C., 2074 Fazekas, Z., 626, 627, 2681 Fearey, B. L., 1874, 1875, 1877, 3322 Feary, B. L., 3047 Feder, H. M., 2715 Federico, A., 637 Fedorets, V. I., 817 Fedorov, L. A., 709 Fedorov, P. I., 104 Fedorov, P. P., 104 Fedorov, Y. S., 2757 Fedorov, Yu. S., 711, 761 Fedoseev, A. M., 747, 749, 1170, 1312, 1319, 1320, 1321, 1425, 1429, 1430, 1433, 2427, 2434, 2436, 2583, 2595 Fedoseev, A. M. R., 2434, 2436 Fedoseev, E. V., 1423, 1471, 1541, 1612, 1625, 1633 Fedoseev, M., 3043 Fedoseev, M. S., 745 Fedoseev, N. A., 747, 749 Fedosseey, A. M., 1931 Fedotov, S. N., 791, 3049, 3052 Feher, I., 1432 Feher, M., 1972 Fein, J. B., 3178, 3180, 3182, 3183 Feinauser, D., 1513, 1552 Feldman, C., 1049 Feldmann, R., 1879, 1884 Felermonov, V. T., 1553 Felker, L. K., 1152, 1408, 1585, 1623, 1624, 2633 Fellows, R. L., 1424, 1446, 1453, 1455, 1465, 1468, 1470, 1474, 1485, 1530, 1533,

Author Index

I-179

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 1534, 1543, 1545, 1579, 1596, 1599, 1600, 1601, 2077, 2417 Felmy, A. R., 125, 127, 128, 130, 131, 1149, 1160, 1162, 1319, 1341, 2192, 2547, 2549, 2587, 2592, 3039, 3134, 3135, 3136, 3137 Fender, B. E. F., 346, 351, 377, 383, 470, 471, 994, 1082, 2153, 2393 Fendorf, S., 3172, 3180 Fendrick, C. A., 2913, 2918, 2924 Fendrick, C. M., 117, 2840, 2841, 2918, 2919, 2920 Feneuille, S., 1862 Feng, X., 292 Fenter, P., 291, 3163, 3164, 3183 Fenton, B. R., 273 Feola, J. M., 1507 Ferey, G., 87, 90 Ferguson, D. E., 1401, 1448, 2734 Ferguson, I. F., 344, 393 Ferguson, T. L., 1288, 2762 Fermi, 3, 4 Fermi, E., 1622 Fern, M., 3029, 3030 Fern, M. J., 3283, 3293, 3296 Fernandes, L., 105 Fernandez-Valverde, S., 3057 Fernando, Q., 2652 Ferran, M. D., 1093 Ferraro, J. B., 471, 512, 513 Ferraro, J. R., 93, 106, 107, 840, 1923, 1931, 2574, 2592, 2649, 3035 Ferrarro, J. R., 1369 Ferreira, L. G., 928 Ferretti, R. J., 3037 Ferri, D., 371, 596, 1921, 2532, 2533, 2583, 3101, 3119 Ferris, L. M., 404, 1270, 1513, 1548, 2701, 2702, 2734 Ferro, R., 53, 67, 98, 99, 100, 927, 2411, 2413 Fertig, W. A., 62, 96 Fetter, S., 3173 Fiander, D., 1735 Fidelis, J., 188 Fiedler, K., 550, 570 Fields, M., 372, 373, 374, 2690 Fields, P. R., 5, 1312, 1324, 1325, 1365, 1404, 1455, 1474, 1509, 1513, 1543, 1577, 1604, 1622, 1636, 2038, 2078, 2090 Fien, M., 3362 Fierz, Th., 3070 Fietzke, J., 231 Fieuw, G., 33 Fife, J. L., 398, 998 Fife, K. W., 1093 Fifield, L. K., 790, 1806, 3063, 3317, 3318 Figgins, P. E., 167, 172, 173, 175, 179, 215, 226, 257

Filby, R. H., 3024, 3280, 3284, 3285, 3292, 3296, 3306, 3307 Filimonov, V. T., 1352, 1512 Filin, B. M., 1302 Filin, V. M., 793, 986 Filippidis, A., 302, 3039 Filipponi, A., 3087 Filippov, E. A., 705 Filippov, E. M., 1507 Filipy, R. E., 3282 Filliben, J. J., 1364 Fillmore, C. L., 377 Filzmoser, M., 1055 Finazzi, M., 2236 Finch, C. B., 113, 1033, 1453, 1472, 1602, 2261, 2263, 2265, 2266, 2268, 2272, 2292 Finch, P. J., 1811 Finch, R. J., 257, 259, 260, 262, 270, 271, 272, 273, 277, 279, 281, 283, 287, 288, 289, 290, 292, 293, 294, 298, 299, 725, 861, 2193, 2426 Finch, W. C., 2999 Finch, W. I., 272, 297 Findlay, M. W., 3022 Findley, J. R., 375 Fine, M. A., 319 Fink, J. K., 357, 359, 1046, 1048, 1074, 1076, 2139, 2140, 2142 Fink, R. M., 3424 Fink, S. D., 1401 Finke, R. G., 2811, 2828, 2924 Finkel, M. P., 3387, 3388, 3421, 3424 Finkle, R. D., 3356, 3378, 3395, 3423, 3424 Finn, P. A., 270, 273, 274, 1806 Finn, R. D., 44 Finnemore, D. K., 62 Finnie, K. S., 280, 291 Finnigan, D. L., 3288, 3314 Fiolhais, C., 1904 Firestone, R. B., 24, 817, 1626, 1633, 1639, 1644, 3274, 3277, 3290, 3298 Firosova, L. A., 1291 Firsova, L. A., 1449, 1512 Fischer, D., 2817, 2818 Fischer, D. F., 1076, 2719, 2720, 3219, 3233, 3234 Fischer, E., 351, 352, 2202 Fischer, E. A., 280, 291 Fischer, E. O., 116, 208, 630, 751, 1093, 1190, 1323, 1324, 1363, 1423, 1800, 2801, 2803, 2814, 2815, 2859 Fischer, G., 231 Fischer, H., 2801 Fischer, J., 1080, 1082, 1083, 1090, 1092 Fischer, P., 69, 425, 428, 429, 436, 439, 440, 444, 447, 448, 451, 455, 479, 2257, 2258, 2352

I-180

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Fischer, R., 1172 Fischer, R. D., 207, 1190, 1191, 1199, 1801, 1894, 1943, 2017, 2253, 2430, 2431, 2472, 2473, 2475, 2491, 2817, 2819, 2824, 2831, 2851 Fischer, W., 80, 81, 82 Fiset, E. O., 1661 Fisher, E. S, 942 Fisher, E. S., 323, 324, 1894, 2315, 2355 Fisher, H., 3341, 3348, 3356, 3387 Fisher, M. L., 3117 Fisher, R. A., 945, 948, 949, 950, 2315, 2347, 2355 Fisher, R. D., 3033 Fisher, R. W., 75, 107, 336, 3246 Fisk, Z., 406, 1003, 2312, 2333, 2343, 2351, 2360 Fitch, A. N., 470, 471 Fitoussi, R., 1286, 2673 Fitzmaurice, J. C., 410, 412, 420 Fitzpatrick, J. R., 1268, 1283, 2749 Fjellvag, H., 66 Flach, R., 63 Flagella, P. N., 357, 2202 Flagg, J. F., 3351, 3355, 3380, 3381 Flahaut, J., 414, 1054, 2413 Flament, J.-P., 1909 Flamm, B. F., 864, 989, 996 Flanagan, S., 2864 Flanary, J. R., 2732 Flanders, D. J., 2440, 2476, 2483, 2484, 2485, 2843 Flegenheimer, J., 186, 213, 217, 219, 229 Fleisher, D., 2668 Fleishman, D., 3305 Fleming, D. L., 2195 Fleming, I., 2953 Fleming, W. H., 823 Flengas, F., 2695 Flengas, S., 2695, 2696 Flerov, G. N., 6, 1660 Fletcher, H. G., 81 Fletcher, J. M., 213, 218, 1011 Fletcher, S., 436, 453, 738, 1084, 1095, 1097, 1312, 2416 Flett, D. S., 840 Flippen-Anderson, J. L., 2382, 2383, 2384 Flitsiyan, E. S., 1507 Floquet, J., 2239 Floreani, D. A., 2686 Florin, A. E., 732, 1080, 1081, 1083, 1084, 1086, 1088, 1090, 1091, 2421, 2426 Florjan, D., 1507 Flotow, H. E., 64, 65, 66, 328, 329, 331, 332, 333, 334, 372, 376, 378, 382, 723, 724, 989, 990, 991, 992, 994, 1029, 1030, 1047, 1048, 2114, 2146, 2156, 2157, 2158, 2160, 2161, 2176, 2188, 2189,

2190, 2262, 3204, 3205, 3206, 3214, 3225, 3241 Flouquet, J., 407, 2352, 2359 Flu¨hler, H., 3014 Fluss, M. J., 863, 980, 981, 983, 984, 986 Flynn, T. M., 264, 265, 266, 281, 294, 296 Fochler, M., 1419, 1422 Foe¨x, M., 77 Fogg, P. G. T., 393 Folcher, G., 101, 2251, 2449, 2450, 2452, 2464, 2465, 2466, 2472, 2603, 2820, 2843, 2855, 3101, 3105, 3120, 3138, 3141 Folden, C. M., III, 1662, 1666, 1695, 1701, 1702, 1712, 1713, 1717, 1735, 1737 Folder, H., 164 Foldy, L. L., 1906 Foley, D. D., 303, 307, 308, 309, 311 Folger, H., 6, 14, 164, 1432, 1433, 1653, 1701, 1713, 1737 Foltyn, E., 718, 719 Foltyn, E. M., 939, 949, 1109 Fomin, V. V., 1095, 1100, 1101, 1102, 1106, 1107, 1108, 2426 Fontana, B. I., 452 Fontanesi, J., 1507, 1518 Fonteneau, G., 425, 446, 468 Fontes, A. S., Jr., 1036, 1047, 2195 Foord, E. E., 259, 262, 263, 264, 265, 266, 267, 268, 269, 275, 277 Foote, F., 321 Forbes, R. L., 1028, 1030 Forchioni, A., 2563, 2580 Ford, J. O., 1008 Foreman, B. M., 29, 184, 1111 Foreman, B. M., Jr., 2662 Foreman, H., 3407, 3408, 3413 Foreman, M. R. St. J., 2674 Forker, L., 3424 Forker, L. L., 3424 Førland, T., 360 Formosinho, S. J., 627 Foropoulos, J., 504, 505 Foropoulus, J., 737 Forrest, J. H., 187 Forrestal, K. J., 2804, 2805 Forrester, J. D., 78, 82, 83, 2418 Forsellini, E., 548, 554, 2426, 2427, 2441, 2442, 2443 Forsling, W., 1636 Fo¨rster, T., 2102 Forsyth, C. M., 2965 Fortner, J. A., 279, 861, 3017, 3051, 3052, 3302 Foster, K. W., 32, 34, 2122 Foster, L. S., 65 Foti, S., 180, 187 Foti, S. C., 3287 Fouche´, K. F., 84, 2565

Author Index

I-181

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Fourest, B., 52, 109, 126, 128, 129, 1605, 2529, 2530, 2538, 2539, 3022, 3101, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118 Fourmigue, M., 2488, 2857 Fourne`s, L., 2360 Fournier, J., 34, 65, 66, 207, 323, 334, 335, 347, 353, 357, 416 Fournier, J. M., 719, 720, 739, 740, 742, 886, 887, 930, 932, 933, 949, 954, 956, 994, 995, 998, 1003, 1019, 1023, 1055, 1411, 1461, 2122, 2123, 2238, 2264, 2267, 2268, 2278, 2279, 2283, 2284, 2285, 2288, 2292, 2315, 2353, 2355, 2358, 2362 Fournier, J.-M., 1754 Fowle, D. A., 3180, 3182 Fowler, M. M., 1738 Fowler, R. D., 191, 193, 904, 908, 913, 988, 2350 Fowler, S. W., 1507, 3017, 3031, 3032 Fowler, W. A., 3014 Fowles, G. W. A., 94 Fox, A. C., 1071 Fox, R. V., 856, 2684 Foxx, C. L., 866 Foyentin, M., 2065, 2066 Fozard, P. R., 3050, 3060, 3062, 3064 Fradin, F. Y., 1022, 2350 Fragala`, I., 116, 576, 1953, 1956, 1957, 1958 Frahm, R., 2236 Frampton, O. D., 76 Franchini, R. C., 869 Francis, A. J., 1110, 2591, 3022, 3046, 3069, 3146, 3179, 3181 Francis, C. W., 1819 Francis, K. E., 1080, 1086 Francis, M., 193 Francis, R. J., 2256 Franck, J. C., 217, 218 Francois, M., 2432 Francois, N., 2674 Frank, A., 83 Frank, N., 231 Frank, R. K., 42, 43 Frank, W., 2479, 2834, 2913, 2933, 2987 Franse, J. J. M., 2238, 2351, 2358, 2407 Frantseva, K. E., 516 Franz, W., 2333 Fratiello, A., 118, 2530, 2533 Frau´sto da Silva, J. J. R., 2587 Fray, D. J., 372, 373, 374 Frazer, B. C., 2273, 2283 Frazer, M. J., 115 Frechet, J. M. J., 851 Fred, M., 33, 190, 226, 857, 858, 860, 1088, 1194, 1295, 1836, 1839, 1842, 1845, 1846, 1847, 1852, 1871, 1873, 2016, 2080, 2083, 2084, 2085, 2086

Fred, M. S., 857, 858, 859, 1626, 2018 Fredo, S., 719, 720 Fredrickson, D. R., 357, 372, 378 Fredrickson, J. K., 274, 3178, 3179, 3180, 3181 Freedberg, N. A., 817 Freedman, M. S., 1626, 1627, 1634, 1639, 1644 Freedman, P. A., 3313 Freeman, A. J., 60, 398, 900, 901, 1265, 1461, 1598, 1605, 1606, 1607, 1613, 2238 Freeman, G. E., 1815 Freeman, H. C., 3117 Freeman, J. H., 1093 Freeman, R. D., 69, 72, 78, 2407 Freestone, N. P., 421, 441, 457, 484, 487, 507, 520, 521, 557, 563, 566 Frei, V., 616 Freiling, E. C., 3287 Freinling, E. C., 225 Freire, F. L., Jr., 3065 Freiser, H., 2675, 2676 Frejacques, C., 824 Fremont-Lamouranne, R., 1316, 1416, 1418 Frenkel, V. Y., 1330, 1331, 1355 Frenkel, V. Y. A., 1547 Frenkel, V. Ya., 1416, 1430, 1433, 1480, 1481 Frenzel, E., 3022 Freundlich, A., 1312 Freundlich, W., 103, 110, 111, 113, 728, 729, 1057, 1065, 1066, 1067, 1068, 1069, 1106, 1107, 1312, 1321, 2431 Friant, P., 3117 Frick, B., 100 Fricke, B., 213, 576, 1524, 1626, 1627, 1643, 1654, 1669, 1670, 1671, 1672, 1673, 1674, 1675, 1676, 1677, 1678, 1679, 1680, 1681, 1682, 1683, 1684, 1685, 1686, 1689, 1691, 1692, 1693, 1706, 1707, 1712, 1716, 1722, 1724, 1726, 1727, 1729, 1730, 1731, 1732, 1733, 1734, 1874, 1880, 1881, 1882, 1883, 1884 Friddle, R. J., 879, 882, 962, 964 Fridkin, A. M., 1476, 1479 Fried, A. R., 2587 Fried, S., 5, 35, 36, 163, 191, 192, 193, 194, 195, 196, 198, 200, 201, 206, 207, 220, 222, 227, 229, 722, 730, 731, 734, 736, 737, 738, 740, 742, 743, 988, 1079, 1176, 1312, 1317, 1325, 1419, 1455, 1465, 1469, 1470, 1513, 1515, 1530, 1531, 1533, 1543, 1544, 1547, 1557, 1577, 2176, 2389, 2390, 2391, 2397, 2407, 2408, 2411, 2413, 2417, 2418, 2422, 2431 Fried, S. M., 737, 1048, 1577, 1622 Friedel, J., 2310 Friedlander, G., 3292, 3299, 3303 Friedman, Am. M., 1636

I-182

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Friedman, H. A., 423, 424, 444, 446, 459, 461, 463, 1132, 1454, 1473, 1547, 1548, 1604 Friedrich, H. B., 1968, 1971 Friedt, J. M., 192, 2283 Friend, J. P., 3254, 3255 Friese, J. I., 607, 612 Frings, P., 2351, 2358 Frink, C., 1738 Frit, B., 281, 467, 509 Fritsch, P., 3352, 3359, 3368, 3377, 3413 Fritsche, S., 33, 1840, 1877, 1884 Fritzsche, S., 1670, 1672, 1673, 1674, 1675, 1676, 1680 Frlec, B., 506, 508 Froese-Fisher, S., 1670 Fro¨hlich, K., 793 Froidevaux, P., 2532, 3014 Frolov, A. A., 606, 763, 765, 1144, 1145, 1146, 1337, 1338, 2594, 2595 Frolov, K. M., 1120, 1128, 1140 Frolova, I. M., 1145, 1146 Frolova, L. M., 1484 Fromage, F., 109, 131 Fromager, E., 620, 622, 623, 1925 Fronaeus, S., 209 Fronczek, F. R., 2491, 2868 Frondel, C., 55, 264, 265 Frost, H. M., 3401, 3405 Fruchart, D., 65, 66, 69, 71, 72 Fryer, B. J., 584, 730, 2402 Fryxell, R., 3341, 3342, 3348, 3353, 3356, 3386 Fryxell, R. E., 352, 353, 376, 378 Fu, G. C., 2980 Fu, K., 1507 Fu, P.-F., 2924 Fu, Y., 786 Fuchs, C., 1033, 1034 Fuchs, L. H., 261, 276, 356, 586, 587 Fuchs, M. S. K., 1921, 1923 Fuchs-Rohr, M. S. K., 1906 Fu¨chtenbusch, F., 410 Fudge, A. J., 188, 225, 226 Fu¨eg, B., 3066, 3067 Fuess, H., 994, 1082 Fuest, M., 822, 3296 Fuger, J., 1, 69, 73, 80, 81, 82, 116, 118, 119, 121, 125, 128, 129, 379, 421, 423, 425, 431, 435, 436, 437, 439, 440, 441, 451, 457, 458, 469, 470, 471, 473, 474, 475, 476, 477, 478, 480, 481, 486, 497, 502, 503, 504, 505, 509, 510, 511, 513, 514, 515, 516, 517, 536, 538, 539, 541, 543, 544, 545, 546, 551, 552, 553, 556, 593, 594, 595, 596, 597, 598, 599, 601, 602, 603, 718, 719, 720, 722, 725, 726, 727, 728, 729, 735, 739, 744, 745, 753, 754, 767, 769, 771, 881, 888, 891, 989, 1008, 1019, 1021, 1045, 1047, 1048, 1061,

1063, 1085, 1086, 1087, 1093, 1098, 1100, 1101, 1110, 1111, 1117, 1118, 1131, 1147, 1148, 1149, 1150, 1155, 1157, 1158, 1159, 1160, 1161, 1162, 1165, 1166, 1167, 1169, 1170, 1171, 1180, 1181, 1303, 1312, 1313, 1328, 1329, 1341, 1352, 1403, 1409, 1410, 1413, 1414, 1417, 1419, 1420, 1424, 1457, 1460, 1464, 1465, 1468, 1469, 1471, 1478, 1479, 1482, 1483, 1525, 1533, 1537, 1543, 1551, 1555, 1562, 1598, 1753, 2113, 2114, 2115, 2117, 2120, 2123, 2124, 2125, 2126, 2127, 2128, 2132, 2133, 2136, 2137, 2138, 2140, 2142, 2143, 2144, 2145, 2150, 2151, 2152, 2153, 2154, 2155, 2156, 2157, 2159, 2160, 2161, 2163, 2164, 2165, 2167, 2168, 2169, 2170, 2171, 2172, 2173, 2174, 2175, 2176, 2179, 2181, 2182, 2186, 2187, 2190, 2191, 2192, 2193, 2194, 2195, 2197, 2199, 2200, 2201, 2203, 2204, 2205, 2206, 2267, 2270, 2389, 2396, 2397, 2413, 2538, 2539, 2546, 2554, 2576, 2578, 2579, 2580, 2582, 2583, 2589, 2695, 2696, 2697, 2698, 2815, 2822, 2851, 2912, 3206, 3213, 3214, 3215, 3347, 3380, 3382 Fugiwara, T., 1276 Fuhrman, N., 61, 1028, 1030 Fuhse, O., 106 Fuji, K., 382, 509, 524, 2244, 2245 Fujii, E. Y., 1398 Fujii, T., 1153 Fujikawa, N., 189 Fujinaga, T., 758 Fujine, S., 711, 712, 760, 766, 787, 1272, 1273, 1294, 1295, 2757 Fujino, O., 3067 Fujino, T., 253, 280, 355, 360, 361, 362, 364, 368, 369, 373, 375, 377, 378, 380, 382, 383, 387, 389, 390, 391, 392, 393, 395, 396, 397, 398, 533, 534, 1025, 1026, 1056, 1057, 1109, 2154, 2244 Fujioka, Y., 189 Fujita, D., 1602, 2272 Fujita, D. K., 1411, 1460, 1472, 1473, 1517, 1525, 1533, 1543, 1595, 1596, 1604, 2077, 2267, 2269, 2270, 2417, 2422 Fujita, Y., 338 Fujiwara, K., 120, 121, 1153, 2575 Fujiwara, T., 2753, 2755, 2760 Fukai, R., 3014, 3017 Fukasawa, T., 760, 762, 766, 787, 1272, 1477 Fukuda, K., 396, 397, 398, 2411 Fukuhara, T., 407 Fukumoto, K., 1292

Author Index

I-183

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Fukusawa, T., 40 Fukushima, E., 2077, 2232, 2415 Fukushima, S., 390, 391 Fukutomi, H., 607, 608, 609, 616, 617, 618, 620, 622 Fulde, P., 1646, 1943, 1944, 1947, 1948, 1949, 1951, 1952, 1959, 2347 Fuller, C. C., 3170 Fuller, J., 2691 Fuller, R. K., 3305 Fulton, R. B., 1134, 2597, 2598, 2599 Fulton, R. W., 1319, 1341, 2547, 2592 Fultz, B., 929, 965, 966, 967 Fun, H.-K., 2452, 2453, 2455 Funahashi, S., 339 Funasaka, H., 2743 Funk, H., 1296, 1403, 1877 Funke, H., 1923, 3106, 3107, 3111, 3112, 3122, 3139 Fuoss, R. M., 609 Fure, K., 1666, 1735 Furman, F. J., 392, 396 Furman, N. H., 634 Furman, S. C., 377 Furrer, A., 425, 428, 436, 439, 440, 444, 447, 448, 451, 455, 2257, 2258 Furton, K. G., 2679, 2682, 2684 Fusselman, S. F., 1270 Fusselman, S. P., 717, 2134, 2135, 2695, 2696, 2697, 2698, 2700, 2715, 2719, 2721 Fux, P., 2590 Gabala, A. E., 2819 Gabelnick, S. D., 1971, 1972, 2148 Gabes, W., 544 Gabeskiriya, V. Ya., 1484 Gabrielli, M., 2457 Gabuda, S. P., 458 Gacon, J. C., 2054, 2059, 2060, 2062 Gadd, K. F., 115, 493, 494 Gade, L. H., 1993 Gadolin, J., 1397 Gaebell, H.-C., 450 Gaffney, J. S., 3288 Gagarinskii, Yu. V., 458 Ga¨ggeler, G., 1704 Ga¨ggeler, H., 182, 185, 1447, 3030, 3031 Ga¨ggeler, H. W., 1447, 1451, 1468, 1593, 1612, 1643, 1662, 1663, 1664, 1665, 1679, 1684, 1685, 1693, 1694, 1698, 1699, 1700, 1704, 1705, 1706, 1707, 1708, 1709, 1710, 1711, 1712, 1713, 1714, 1716, 1718, 1721, 1732, 1738, 1806 Ga¨ggeler, M., 1628 Gagliardi, L., 576, 589, 595, 596, 1897, 1907, 1921, 1922, 1923, 1927, 1928, 1929, 1938, 1972, 1973, 1974, 1975, 1979,

1989, 1990, 1993, 1994, 1995, 2528, 3102, 3113, 3123 Gagne, J. M., 1873 Gagne´, M. R., 2912, 2913, 2918, 2924, 2933, 2984, 2986 Gagnon, J. E., 584, 730, 2402 Gaillard, J. F., 3181 Gaines, R. V., 259, 262, 263, 264, 265, 266, 267, 268, 269, 275 Gajdosova, D., 3046 Gajek, Z., 421, 422, 425, 426, 428, 432, 440, 442, 443, 447, 449, 450, 453, 469, 2138, 2249, 2278 Gal, J., 719, 720, 862, 2361 Galasso, F. S., 1059 Galateanu, I., 218, 219 Gal’chenko, G. L., 2114, 2148, 2149, 2168, 2185 Gale, N. H., 3311 Gale, R. J., 3100 Gale, W. F., 322 Galesic, N., 102, 103, 110, 2431 Galkin, B. Y., 2757 Galkin, B. Ya., 711, 761 Galkin, N. P., 303, 458 Gallagher, C. J., 164 Gallagher, F. X., 340, 342, 345, 346, 348, 355 Galle, P., 3050, 3062, 3063 Galleani d’Agliano, E., 1461 Gallegos, G. F., 932, 967 Galloy, J. J., 2392 Gallup, C. D., 3313 Galvao, A., 2885, 2886 Galva˜o, J. A., 2912 Galy, J., 268, 385 Galzigna, L., 548 Gambarotta, S., 117, 1966, 2260, 2871, 2872, 2873, 2874 Gamble, J. L., 3357 Gammage, R. B., 1432 Gamp, E., 469, 482, 492, 2065, 2066, 2248, 2249, 2251, 2261 Gan, Z., 164 Ganchoff, J. G., 184 Gandreau, B., 537, 566, 567 Ganguly, C., 3236 Ganguly, J., 116 Ganguly, L., 2815 Ganivet, M., 1118, 1119 Gankina, E. S., 1507 Gann, X., 2656 Gannett, C. M., 1447, 1635, 1642, 1643, 1645, 1646, 1662, 1703, 1704 Gans, W., 100 Gansow, O. A., 44 Gantz, D. E., 67, 77 Gantzel, P., 67, 1965 Gantzel, P. K., 2407

I-184

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Ganyushin, D. I., 1906 Ganz, M., 822, 3014, 3296 Gao, J., 1910 Gao, L., 76, 77 Gao, Y., 92 Garbar, A. V., 2859 Garcia Alonso, J., 3068 Garcia Alonso, J. I., 789, 3062 Garcia, D., 482, 2049, 2054, 2066 Garcia, E., 398, 998 Garcia, J. F., 3364, 3378, 3387 Garcia, K., 3022 Garcia-Carrera, A., 2655 Garcia-Hernandez, M., 1918, 1919, 1920, 1931, 1935, 1937, 1938 Gardner, C. J., 530 Gardner, E. R., 1027, 1030, 1031, 2389, 2395 Gardner, H., 936 Gardner, H. R., 944, 968, 969, 970, 971 Gardner, M., 319 Garg, S. P., 352 Garmestani, K., 44 Garner, C. S., 704, 822, 1078, 1092, 1095 Garnier, J. E., 396 Garnov, A. Y., 1336, 2531, 2532, 2568, 3102, 3111, 3112, 3113, 3122, 3123, 3143, 3145 Garrett, A. B., 399, 400 Garrido, F., 289, 340, 345, 348 Garstone, J., 892, 913 Gartner, M., 1684, 1707, 1708, 1709, 1716 Garuel, A., 2352 Garwan, M. A., 3014, 3063, 3317, 3318 Garza, P. A., 2660 Gasche, T., 191 Gasco, C., 3017, 3023 Gascon, J. L., 1432, 1433 Gaskill, E. A., 316, 317 Gaskin, P. W., 1179, 3415, 3416, 3420 Gasnier, P., 2685 Gaspar, P., 2881, 2882 Gasparinetti, B., 105 Gasparini, G. M., 1280, 1282, 2738, 2743 Gasparro, J., 1688, 1700, 1718, 3024 Gasperien, M., 730, 745, 792 Gasperin, M., 87, 92, 113, 460, 2443 Gasser, M., 3409 Gassner, F., 1287, 2674, 2761 Gasvoda, B., 3361 Gata, S., 1267 Gateau, C., 598 Gatehouse, B. M., 269 Gates, B. C., 2999 Gates, J. E., 1018, 1019 Gatez, J. M., 1177, 1178 Gatrone, R. C., 1279, 1281, 2642, 2652, 2738, 2747, 3283

Gatti, R. C., 5, 1178, 1180, 3025, 3302 Gaudiello, J., 2827 Gaudreau, B., 468, 537, 566, 567 Gaughan, G., 2811, 2828 Gaulin, B. D., 2281, 2282 Gault, R. A., 262, 289, 290 Ga¨umann, T., 1085, 1086 Gaumet, V., 88, 91 Gaune-Escard, M., 469, 475, 2185, 2186, 2187 Gaunt, A. J., 2584 Gauss, J., 1902 Gautam, M. M., 2750 Gauthier, R., 3034, 3035 Gauthier-Lafaye, F., 3172 Gautier-Soyer, M., 277 Gauvin, F. G., 2916 Gavrilov, K. A., 6, 1509 Gavrilov, V., 1398, 1421 Gavrilov, V. D., 1398, 1433 Gavron, A., 1477 Gay, R. L., 717, 2695, 2696, 2697, 2698, 2715, 2719 Gaylord, R., 1653 Gazeau, D., 2649, 2657 Geary, N. R., 707 Geary, W. J., 636 Gebala, A., 2819, 2820 Gebala, A. E., 1802, 2472 Gebauer, A., 605, 2464 Gebert, E., 261, 276, 372, 373, 586, 587, 719, 1057, 1060, 1061, 1312, 1313 Geckeis, H., 3024, 3069, 3070 Gedeonov, L. I., 1352 Geerlings, M. W., Jr., 44 Geerlings, M. W., Sr., 28, 44 Geertsen, V., 2682, 2685 Geeson, D. A., 3243, 3244 Geggus, G., 792 Gehmecker, H., 794 Geibel, C., 719, 720, 2347, 2352 Geibert, W., 44 Geichman, J. R., 505, 506, 535 Geigert, W., 231 Geipel, G., 108, 626, 1113, 1156, 1923, 1933, 2583, 3037, 3044, 3046, 3069, 3102, 3106, 3107, 3111, 3112, 3122, 3125, 3131, 3138, 3140, 3142, 3143, 3144, 3145, 3150, 3152, 3154, 3155, 3160, 3161, 3165, 3166, 3167, 3179, 3180, 3182, 3381, 3382 Geise, J., 170 Geiss, J., 170 Geist, A., 2756 Gelbrich, T., 259, 287 Gelis, A. V., 3043 Gellatly, B. J., 439, 445, 449, 452, 455, 472, 477, 482, 512, 543, 593

Author Index

I-185

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Gelman, A. D., 726, 728, 729, 745, 746, 747, 749, 750, 753, 763, 767, 768, 771, 773, 1059, 1110, 1113, 1116, 1117, 1118, 1123, 1128, 1133, 1156, 1163, 1172, 1175, 1325, 1327, 1352, 1367, 1368, 2527, 2575, 3124 Gendre, R., 1080 Genet, C. R., 1172 Genet, M., 103, 109, 110, 128, 220, 221, 275, 469, 472, 477, 482, 491, 492, 1172, 2066, 2248, 2249, 2251, 2431, 2432, 3024 Gens, R., 431, 451, 735, 739, 1061, 1063, 1312, 1469, 1483 Gens, T. A., 855 Gensini, M., 741 Gensini, M. M., 719, 720, 721 Gentil, L. A., 110 Geoffrey, G. L., 1983 George, A. M., 369 George, D. R., 305, 308 George, R. S., 465, 466 Georgopoulos, P., 3100, 3101, 3103, 3118 Gerard, V., 367 Gerasimov, A. S., 1398 Gerber, G. B., 3424 Gerdanian, P., 353, 354, 355, 356, 360, 362, 363, 364, 1048, 2145 Gerding, H., 544 Gerding, T. J., 272, 731, 732, 733, 2084 Gerdol, R., 3280 Gerds, A. F., 393, 399, 410, 2407 Gergel, M. V., 175, 704, 3016 Gergel, N. V., 822, 824 Gering, E., 2315, 2371, 2407 Gerke, H., 98 Gerlach, C. P., 2832, 2974 Gerloch, M., 2054 Germain, G., 260, 263, 283, 2489, 2490, 2492 Germain, M., 1275 Germain, P., 782 German, G., 2802, 2844 Gerontopulos, P. T., 1284 Gerratt, J., 93 Gersdorf, R., 2238 Gershanovich, A. Y., 86, 88, 89, 93 Gerstenkorn, S., 858, 860, 1847 Gerstmann, U., 3016, 3063 Gerwald, L., 409 Gerward, L., 100, 2407 Gerz, R. R., 728, 1064 Gesing, T. M., 69, 71, 405 Gesland, J. Y., 422 Gestin, J.-F., 43 Gevantman, L. H., 1123 Gevorgyan, V., 2969 Gewehr, R., 80, 81, 82 Gey, W., 64

Ghafar, M., 180 Ghermain, N.-E., 602 Ghermani, N. E., 2431 Ghiasvand, A. R., 2681, 2684 Ghijen, J., 2336 Ghiorso, A., 5, 6, 13, 53, 164, 815, 821, 1265, 1397, 1418, 1444, 1499, 1502, 1577, 1622, 1630, 1632, 1637, 1638, 1639, 1640, 1641, 1642, 1643, 1645, 1653, 1660, 1661, 1662, 1692, 1738, 1762, 2129 Ghiorso, W., 1653 Ghods, A., 3017 Ghods-Esphahani, A., 3308 Ghormley, J. A., 3221 Ghosh Mazumdar, A. S., 1175 Ghotra, J. S., 93 Giacchetti, A., 59, 1843, 1844 Giacometti, G., 2865 Giacomini, J. J., 3253, 3254 Giaechetti, A., 190, 226 Giammar, D. E., 287 Giannola, S. J., 3403, 3405 Giannozzi, P., 2276 Giaon, A., 24, 31 Giaquinta, D. M., 3152, 3157, 3158 Giarda, K., 1196, 1198, 2080, 2085, 2086, 2561 Giardello, M. A., 2913, 2918, 2924, 2933, 2934, 2984, 2986 Giardinas, G., 1654, 1719, 1720, 1735 Gibb, T. R. P., Jr., 329, 330, 331 Gibbs, D., 2234, 2281, 2282, 2288 Gibbs, F. E., 916, 960 Gibby, H., 3220 Gibby, R. L., 2147 Gibifiski, T., 414 Gibinski, T., 2413 Gibney, R. B., 744, 945, 954, 956, 957 Gibson, G., 106, 370 Gibson, J. K., 719, 720, 721, 1302, 1316, 1362, 1363, 1364, 1412, 1415, 1416, 1417, 1424, 1455, 1456, 1457, 1463, 1464, 1528, 1531, 1540, 1541, 1560, 1561, 1592, 1593, 1603, 1609, 1610, 1611, 1612, 1627, 1628, 1634, 1639, 1644, 2118, 2121, 2122, 2150, 2165, 2188, 2189, 2404 Gibson, M. L., 482 Gibson, R., 225 Gibson, R. R., 2633, 2634 Giere´, R., 277, 278, 279 Gieren, A., 2464 Giese, H., 77 Giesel, F., 19, 20, 47 Giessen, B. C., 719, 720, 897, 932 Giester, G., 265, 295 Giffaut, E., 1160, 1161, 1162, 1164, 1314, 1341, 2583

I-186

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Giglio, J. J., 3060 Gikal, B. N., 14, 1653, 1654, 1707, 1719, 1720, 1735, 1736 Gilbert, B., 116, 117, 1607, 2687, 2689, 2815, 2819, 2851 Gilbert, E. S., 1821 Gilbert, T. M., 2487, 2488, 2856, 2857 Gilbertson, R. D., 2660 Gili, M., 2633 Gilissen, R., 1033 Gilje, J. W., 1957, 2472, 2473, 2475, 2479, 2484, 2561, 2825, 2826, 2919 Gill, H., 3173, 3176, 3177 Gillan, M. J., 367 Gilles, P. W., 95, 96, 364, 413, 738, 1093 Gillespie, K. M., 2984 Gillespie, R. D., 2999, 3002 Gillier-Pandraut, H., 539 Gillow, J. B., 3022, 3179, 3181 Gilman, H., 2800, 2866 Gilman, W. S., 1048 Gilpatrick, L., 2701 Gilpatrick, L. O., 390 Ginderow, D., 261, 262, 268 Gindler, G. E., 632, 633, 3281 Gindler, J. E., 3340 Ginell, W. S., 854 Gingerich, K. A., 98, 99, 100, 398, 1987, 1994, 2198, 2202, 2411 Ginibre, A., 1844, 1863, 1873 Ginter, T., 1695, 1702, 1717, 1735, 1737 Ginter, T. N., 1662, 1664, 1685, 1701, 1712, 1713, 1714, 1716, 1717 Giordano, A., 1045 Giordano, T. H., 3140, 3150 Giorgi, A. L., 30, 34, 35, 68, 333, 2385 Giorgio, G., 114 Girard, E., 861 Girardi, F., 2633, 2767 Giraud, J. P., 2731 Girdhar, H. L., 350, 356 Girerd, J. J., 2254 Girgis, C., 182 Girgis, K., 53, 67 Girichev, G. V., 1680, 1681, 2169 Giricheva, N. I., 1680, 1681, 2169 Girolami, G. S., 2464, 2465 Gitlitz, M. H., 115 Gittus, J. H., 303 Giusta, A. D., 3167 Givon, H., 1509 Givon, M., 1284, 1325, 1328, 1329, 1331, 1365 Gladney, E. S., 3057 Glamm, A., 319 Glanz, J. P., 1699, 1700, 1710, 1718 Glaser, C., 76 Glaser, F. S., 66 Glaser, F. W., 2407

Gla¨ser, H., 372, 377, 378, 382 Glaser, J., 596, 607, 610, 1166, 1921, 2532, 2533, 2583, 3101, 3119 Glaser, R., 2979 Glasgow, D. C., 1505 Glassner, A., 2706, 2709 Glatz, J. P., 713, 1008, 1409, 1410, 1684, 1708, 1709, 1716, 2135, 2657, 2675, 2752, 2753, 2756 Glaus, F., 1662, 1664, 1685, 1713, 1714, 1716 Glauzunov, M. P., 793 Glavic, P., 86, 91 Glazyrin, S. A., 1126 Gleba, D., 2668 Glebov, V. A., 1670, 1672, 1692, 1693, 3111, 3122 Gleichman, J. R., 506 Gleisberg, B., 1433, 1434, 1629, 1635 Gleiser, M., 2115 Gleisner, A., 719, 720 Glenn, R. D., 3346 Glover, K. M., 166, 224 Glover, S. E., 3024, 3280, 3284, 3285, 3292, 3296, 3306, 3307 Glueckauf, E., 1915 Glukhov, I. A., 525 Glushko, V. P., 1047, 1048, 2114, 2148, 2149, 2185 Gmelin, 19, 28, 30, 36, 38, 40, 42, 43, 52, 55, 56, 57, 58, 59, 60, 61, 63, 67, 69, 70, 75, 101, 105, 114, 115, 117, 133, 162, 178, 255, 264, 265, 275, 303, 318, 325, 328, 407, 417, 420, 1265, 1267, 1290, 1296, 1398, 1400, 1402, 1406, 1433, 1764, 1771, 1790 Gnandi, K., 297 Gober, M. G., 1704 Gober, M. K., 182, 185, 1447, 1704, 1705 Goble, A. G., 164, 173, 176, 179, 182, 213 Gobomolov, S. L., 1654, 1719, 1736 Gobrecht, J., 1447 Goby, G., 1352, 1428, 1551, 1606, 1629 Godbole, A. G., 790, 1275, 3061 Goddard, D. T., 297 Godelitsas, A., 302, 3039 Godfrey, J., 638, 3328 Godfrey, P. D., 1981 Godfrin, J., 2633 Godlewski, T., 20 Godwal, B. K., 2370 Goeddel, W. V., 2733 Goedken, M. P., 2563 Goedkoop, J. A., 66 Goeppert Mayer, M., 1858 Goetz, A., 3310, 3311, 3312, 3313 Goeuriot, P., 861 Goffart, J., 116, 117, 470, 552, 553, 737, 1352, 1413, 1419, 1543, 2143, 2144, 2267,

Author Index

I-187

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 2270, 2396, 2418, 2489, 2490, 2802, 2815, 2816, 2817, 2818, 2819, 2822, 2827, 2844, 2851, 2912 Gofman, J. W., 164, 256 Gog, T., 2288 Gogolev, A. V., 1110 Gohdes, J. W., 289, 602, 1166, 2583, 3130, 3131, 3160, 3167 Go˜hring, O., 162, 170, 187 Goibuchi, T., 762 Gojnierac, A., 182 Goldacker, H., 2732 Goldberg, A., 886, 888, 890, 939, 940 Golden, A. J., 224 Golden, J., 164, 173, 176, 179, 213 Goldenberg, J. A., 1033 Gol’din, L. L., 20, 24 Goldman, J. E., 2273, 2275 Goldman, S., 1483, 1555 Goldschmidt, V. M., 2391 Goldschmidt, Z. B., 1862, 2015, 2016 Goldstein, S. J., 171 Goldstone, J. A., 333, 334, 335, 882, 939, 949, 989, 995 Goldstone, P. D., 1477 Golhen, S., 2256 Gollnow, H., 190, 226 Golovnin, I., 1071 Golovnya, V. A., 105, 106, 109 Goltz, D. M., 3036 Golub, A. M., 84 Golutvina, M. M., 184 Gomathy Amma, B., 3308 Gomez Marin, E., 956 Gomm, P. J., 28, 31 Gompper, K., 2633, 2756 Goncharov, V., 1973 Gonella, C., 352 Gong, J. K., 3406 Gong, W., 265 Gonis, A., 927, 3095 Gonthier-Vassal, A., 2250 Gonzales, E. R., 3057 Goodall, P. S., 3060 Goode, J. H., 188 Goodenough, J. B., 1059 Goodman, C. C., 1626, 1627, 1637, 1638 Goodman, C. D., 1639, 1659 Goodman, G., 2251 Goodman, G. L., 763, 766, 1090, 1454, 2016, 2030, 2038, 2044, 2080, 2083, 2085, 2267, 2283, 2289 Goodman, L. S., 1088, 1194, 1588, 1626, 1846, 1873, 2080, 2084, 2086 Googin, J. M., 319 Gopalakrishnan, V., 712, 713, 1281, 1282, 1294, 2668, 2669, 2743, 2744, 2745, 2747, 2749, 2750, 2757, 2759

Gopalan, A., 2633 Gopinathan, C., 215, 218 Gorban, Yu. A., 364 Gorbenko-Germanov, D. S., 1312, 1319, 1320, 1326 Gorbunov, L. V., 86, 93 Gorbunov, S. I., 984 Gorbunov, V. F., 793 Gorbunova, Yu. E., 2439, 2441, 2442, 2452 Gorby, Y. A., 3172, 3178, 3179 Gordeev, Y. N., 1505, 1829 Gorden, A. E. V., 1813, 1824, 1825, 2464, 3413, 3414, 3417, 3418, 3419, 3420, 3421 Gordienko, A. B., 1906 Gordon, C. M., 2690 Gordon, G., 592, 606, 609, 619, 622, 1133, 2607 Gordon, J., 356, 357, 2272 Gordon, J. C., 2484, 2486, 2813, 2814 Gordon, J. E., 63, 945, 947, 949, 2315, 2350 Gordon, M. S., 1908, 2966 Gordon, P., 2358 Gordon, P. L., 861, 932, 1041, 1043, 1112, 1154, 1155, 1166, 2464, 3109, 3210 Gordon, S., 768, 769, 770, 1325, 1326, 1337, 1416, 1424, 1430, 1774, 1776, 2077, 2526, 2531, 2553 Gore, S. J. M., 786 Gorlin, P. A., 2464 Go¨rller-Walrand, C., 2014, 2016, 2044, 2047, 2048, 2058, 2093, 3101 Gorman, T., 854 Gorman-Lewis, D., 3178 Gorokhov, L. N., 576, 1994, 2179, 2195 Gorshkov, N. G., 539 Gorshkov, N. I., 856 Gorshkov, V. A., 1654, 1719, 1720, 1735, 1738 Gorski, B., 1629, 1635 Gorum, A. E., 1022, 1050, 1052 Goryacheva, E. G., 30 Gosset, D., 289 Goto, S., 1450, 1484, 1696, 1718, 1735 Goto, T., 334, 335 Gotoh, K., 382 Gotoo, K., 340, 344, 347, 354 Gottfriedsen, J., 575, 2469 Goubitz, K., 514 Gouder, T., 97, 861, 863, 995, 1023, 1034, 1056, 2347, 2359, 3045, 3051 Goudiakas, J., 2153 Gould, T., 3264, 3265 Gould, T. H., 3266 Gould, T. H., Jr., 3265 Goulon, J., 2236, 3117 Goulon-Ginet, C., 3117 Gourevich, I., 2830, 2918, 2935, 2965, 2969, 2971 Gourier, D., 1962, 2246, 2847, 2858, 2862

I-188

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Gourishankar, K. V., 2723 Gourisse, D., 1333 Gourmelon, P., 3413 Goutaudier, C., 2100 Gove, N. B., 1267 Govindarajan, S., 2442 Gowing, H. S., 3364, 3375 Goyal, N., 2668 Grachev, A. F., 854 Gracheva, N. V., 416, 419 Gracheva, O. I., 788 Graczyk, D., 3284 Gradoz, P., 2491, 2869, 2870, 2871, 2872 Graf, P., 2386 Graf, W. L., 988 Graffe´, P., 1880, 1882 Graham, J., 75, 96, 2413 Graham, R. L., 1452 Gramaccioli, C. M., 261, 264 Gramoteeva, N. I., 2822 Grandjean, D., 414, 2413 Grant, G. R., 2736 Grant, I. P., 1669, 1670, 1675, 1726, 1728, 1905 Grant, P. M., 2589 Grantham, L. F., 717, 1270, 2134, 2135, 2695, 2696, 2697, 2698, 2699, 2700, 2719, 2720 Grantz, M., 1684, 1707 Grape, W., 505 Grate, J. W., 3285 Gratz, E., 2353 Graue, G., 163, 172, 174, 178 Grauel, A., 2352 Graus Odenheimer, B., 1352 Grauschopf, T., 1906 Gravereau, P., 2360 Graw, D., 207 Gray, A. L., 133, 3324 Gray, C. W., 630 Gray, G. E., 2687, 2691 Gray, H. B., 577, 609 Gray, L., 3264, 3265 Gray, P. R., 27, 704, 3276 Gray, S. A., 1179, 2591, 3354, 3413, 3415, 3416, 3419, 3420, 3421 Gray, W., 633, 634 Grayand, P. R., 171, 184 Graziani, R., 548, 2426, 2427, 2439, 2440, 2441, 2443, 2472, 2473, 2484, 2820, 2825, 2841 Grazotto, R., 554 Grdenic, D., 2439, 2444 Greathouse, J. A., 3156 Greaves, C., 346, 351, 377, 383, 2393 Greaves, G. N., 3163 Grebenkin, K. F., 989, 996 Grebenshchikova, V. I., 1320 Grebmeier, J. M., 3295, 3296, 3311, 3314

Greegor, R. B., 278, 3162, 3163 Greek, B. F., 314 Green, C., 2728 Green, D., 3353, 3403, 3405 Green, D. W., 1018, 1029, 1046, 1971, 1976, 1988, 2148, 2149, 2203 Green, J. C., 116, 1196, 1198, 1200, 1202, 1949, 1962, 1964, 2080, 2085, 2086, 2561, 2827, 2854, 2863, 2877 Green, J. L., 1003, 1417, 1530, 1532, 1536, 1543, 1557, 2398 Green, L. W., 3322 Green, M. L. H., 1962 Greenberg, D., 3424 Greenberg, D. M., 3405 Greenberg, E., 478, 497 Greenblatt, M., 77 Greene, T. M., 1968 Greenland, P. T., 1873 Greenwood, N. N., 13, 162, 998, 1660, 2388, 2390, 2400, 2407 Greenwood, R. C., 3243, 3244 Gregersen, M. I., 3358 Gre´goire, D. C., 3036 Gre´goire-Kappenstein, A. C., 3111 Gregor’eva, S. I., 1449 Gregorich, K., 182, 185, 186 Gregorich, K. E., 815, 1445, 1447, 1582, 1629, 1635, 1642, 1643, 1645, 1646, 1647, 1653, 1662, 1664, 1666, 1679, 1684, 1685, 1687, 1690, 1693, 1694, 1695, 1696, 1697, 1698, 1699, 1701, 1702, 1703, 1704, 1705, 1706, 1708, 1709, 1710, 1711, 1712, 1713, 1714, 1716, 1717, 1718, 1735, 1737, 1738, 2575 Gregory, J. N., 375 Gregory, N. W., 454, 456, 500 Greiner, J. D., 61, 2315 Greiner, W., 1670, 1731, 1733 Greis, O., 114, 206 Gremm, O., 2734 Grenn, J. C., 117 Grenthe, I., 118, 119, 120, 121, 124, 125, 127, 128, 130, 131, 211, 253, 270, 371, 421, 423, 425, 435, 439, 440, 441, 457, 458, 469, 473, 474, 477, 478, 480, 481, 497, 502, 503, 509, 513, 514, 515, 516, 517, 536, 538, 543, 544, 545, 551, 552, 556, 565, 577, 578, 580, 581, 586, 589, 590, 591, 593, 594, 595, 596, 597, 598, 599, 601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 616, 617, 618, 619, 620, 621, 622, 623, 625, 626, 753, 775, 1113, 1146, 1147, 1148, 1149, 1150, 1155, 1156, 1158, 1159, 1160, 1161, 1165, 1166, 1171, 1181, 1341, 1352, 1427, 1909, 1918, 1919, 1921, 1922, 1923, 1924, 1925, 1926, 1927,

Author Index

I-189

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 1928, 1933, 1991, 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2132, 2133, 2136, 2137, 2138, 2142, 2144, 2150, 2151, 2152, 2153, 2154, 2155, 2156, 2157, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2169, 2170, 2171, 2173, 2174, 2175, 2176, 2179, 2181, 2182, 2185, 2186, 2187, 2190, 2191, 2192, 2193, 2194, 2195, 2197, 2200, 2203, 2204, 2205, 2206, 2531, 2532, 2533, 2538, 2546, 2554, 2563, 2576, 2578, 2579, 2582, 2583, 2585, 2587, 2592, 2593, 3037, 3101, 3102, 3103, 3104, 3105, 3106, 3112, 3119, 3120, 3121, 3125, 3126, 3127, 3128, 3132, 3140, 3143, 3144, 3214, 3215, 3347, 3380, 3382 Greulich, N., 1738 Grev, D. M., 2439, 2440, 2568 Grewe, N., 2342 Grey, I. E., 113, 269, 345, 347, 354 Grieneisen, A., 2731 Grieveson, P., 402 Griffin, C. D., 2039 Griffin, D. C., 1730, 1731 Griffin, G. C., 1908 Griffin, H. E., 1284 Griffin, N. J., 324 Griffin, P. M., 857, 858, 860, 1847 Griffin, R. G., 1817 Griffin, R. M., 1009 Griffin, S. T., 2691 Griffioen, R. D., 1632 Griffith, C. B., 328 Griffith, W. L., 319 Griffiths, A. J., 504 Griffiths, G. C., 375, 376 Griffiths, T. R., 372, 373, 374 Grigorescu-Sabau, C. S., 1352 Grigor’ev, A. I., 2434 Grigor’ev, M. S., 745, 746, 747, 748, 749, 793, 1113, 1156, 1170, 1181, 1931, 2434, 2436, 2439, 2442, 2527, 2531, 2595, 3043 Grigoriev, A. Y., 2237 Grigoriev, M., 1262, 1270, 1312, 1321 Grigorov, G., 1507 Grillon, G., 3352, 3359, 3368, 3377, 3398, 3399 Grime, G. W., 297 Grimes, W. R., 423, 444, 459, 463, 487 Grimmett, D. L., 717, 1270, 2134, 2135, 2695, 2696, 2697, 2698, 2699, 2700, 2715, 2719, 2721 Grimsditch, M., 277 Grimvall, G., 2140 Grison, E., 904, 908, 913, 988 Gritmon, T. F., 2563 Gritschenko, I. A., 41

Gritzner, N., 522 Griveau, J. C., 967, 968, 1009, 1012, 1015, 1016, 2353, 2407 Grobenski, Z., 113 Groeschel, F., 3055 Grogan, H. A., 1821 Groh, H. J., 1427 Grojtheim, K., 2692 Grønvold, F., 340, 345, 347, 348, 351, 352, 353, 354, 355, 356, 357, 359, 362, 2114, 2203, 2204, 2389 Gropen, O., 580, 596, 1156, 1670, 1728, 1905, 1909, 1918, 1919, 1921, 1922, 1923, 1925, 1926, 1931, 1932, 1933, 1991, 2532, 3102, 3126, 3127 Grosche, F. M., 407, 2239, 2359 Gross, E. B., 294 Gross, E. K. U., 1910, 2327 Gross, G. M., 402, 407 Gross, J., 2568 Gross, P., 2160, 2208 Grosse, A., 163, 172, 173, 174, 175, 178, 179, 181, 198, 200, 226, 229 Grosse, A. V., 1728 Grossi, G., 1282, 2633, 2743 Grossman, L. N., 323, 393 Grossmann, H., 105 Grossmann, U. J., 1910 Grosvenor, D. E., 1081 Grove, G. R., 27, 30, 32, 904, 905, 908, 914, 1033 Grube, B. J., 3398, 3399 Gru¨bel, G., 2234, 2237 Gruber, J. B., 469, 491, 765, 2261 Grudpan, K., 225 Gruehn, R., 113, 550, 570 Gruen, D. M., 8, 292, 335, 342, 469, 490, 491, 492, 501, 510, 524, 724, 737, 763, 764, 1034, 1088, 1090, 1094, 1095, 1099, 1109, 1313, 1754, 1968, 1971, 2081, 2133, 2167, 2257, 2696, 2697, 2699 Gruener, B., 2655 Grumbine, S. K., 2484, 2487, 2844, 2845 Grundy, B. R., 170 Gruner, R., 3398 Gruning, C., 859 Gru¨ning, C., 33, 1452, 1876, 1877 Gru¨ning, P., 1840, 1877, 1884 Grunzweig-Genossar, J., 329, 333, 336 Gruttner, C., 2655 Gryntakis, E. M., 106 Grytdal, S. P., 3292 Gschneidner, K. A., 936, 939, 941 Gschneidner, K. A., Jr., 896, 897, 926, 927, 2309 Gu, D., 3057 Gu, J., 164 Gu, X., 266

I-190

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Gu, Z. Y., 3300 Guang-Di, Y., 2453 Guastini, C., 2472 Gubanov, V. A., 1692, 1933 Guczi, J., 3023 Gudaitis, M. N., 93 Gu¨del, H. U., 428, 429, 436, 440, 442, 444, 451 Gudi, N. M., 772, 773, 774 Guegueniat, P., 782 Gueguin, M. M., 527 Guelachvili, G., 1840, 1845 Guelton, M., 76 Gue´neau, C., 351, 352 Gue´neau, Le Ny, J., 365 Guenther, D., 3047 Gueremy, P., 3016 Guerin, G., 862 Gue´rin, L., 1269 Guerra, F., 3030, 3280 Guertin, R. P., 63 Guery, C., 92 Guery, J., 92 Guesdon, A., 2431, 2432 Guest, R. J., 633, 3282 Guesten, H., 227 Gueta-Neyroud, T., 2913, 2930, 2940 Gueugnon, J. F., 2292 Guey, A., 1507 Guggenberger, L. J., 78, 83, 84, 2415 Guibal, E., 3152, 3154 Guibe´, L., 81 Guichard, C., 1177, 1178, 1179, 1180, 1181, 2575 Guidotti, R. A., 83 Guilard, R., 2464, 2465, 2466, 3117 Guilbaud, P., 596, 2560, 2590, 3101 Guillaume, B., 781, 1324, 1329, 1341, 1356, 1365, 1366, 2594, 2595 Guillaume, J. C., 2594, 2596 Guillaumont, B., 1356 Guillaumont, R., 34, 37, 40, 82, 109, 117, 128, 129, 162, 176, 181, 183, 184, 185, 198, 199, 200, 207, 209, 211, 212, 215, 216, 217, 218, 219, 221, 222, 223, 225, 227, 421, 423, 425, 435, 439, 440, 441, 457, 458, 469, 473, 474, 477, 478, 480, 481, 497, 502, 503, 509, 513, 514, 515, 516, 517, 536, 538, 543, 544, 545, 551, 552, 556, 593, 594, 595, 596, 597, 598, 599, 601, 602, 603, 763, 765, 768, 988, 1147, 1148, 1149, 1150, 1158, 1160, 1161, 1165, 1166, 1181, 1330, 1352, 1417, 1418, 1425, 1428, 1460, 1476, 1477, 1481, 1482, 1523, 1526, 1529, 1549, 1550, 1551, 1554, 1555, 1557, 1606, 1628, 1629, 1635, 1640, 1644, 1645, 1663, 2115, 2117, 2120, 2123, 2126, 2127, 2128, 2132, 2136, 2137, 2138,

2142, 2144, 2151, 2152, 2153, 2154, 2155, 2157, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2170, 2171, 2174, 2175, 2176, 2179, 2181, 2182, 2186, 2187, 2190, 2191, 2192, 2193, 2194, 2195, 2197, 2200, 2203, 2204, 2206, 2532, 2538, 2546, 2550, 2552, 2554, 2578, 2676, 2858, 3022, 3024 Guillot, J.-M., 2657 Guillot, L., 3026, 3027, 3028 Guillot, P., 185, 215 Guilmette, R. A., 1821, 1825, 3345, 3349, 3354, 3360, 3364, 3371, 3374, 3385, 3396, 3409, 3413, 3420 Guinand, S., 123 Guinet, P., 351, 352, 353 Guittet, M.-J., 277 Gukasov, A., 2411 Gula, M. J., 1293, 2642, 2643, 3283 Gulbekian, G. G., 14, 1654, 1719, 1720, 1735, 1736, 1738 Gu¨ldner, R., 1073, 1095, 1100, 1101 Gulev, B. F., 746, 748, 749, 2527 Gulino, A., 1956, 1957 Gulinsky, J., 2966 Gulyaev, B. F., 1113, 1156 Gulyas, E., 114 Guminski, C., 1302, 1548, 1607 Gumperz, A., 80, 104 Gundlich, C., 82 Gun’ko, Y., 2912 Gun’ko, Y. K., 2469 Gunnick, R., 3302 Gunnoe, T. B., 2880 Gunten, H. R. V., 1738 Gu¨nther, D., 3323 Gunther, H., 1660 Gu¨nther, R., 1662, 1679, 1684, 1687, 1698, 1708, 1709, 1710, 1716, 1718 Gunther, W. H., 1088, 1089 Guo, G., 786 Guo, J., 164, 191 Guo, L., 3062 Guo, T., 2864 Guo, Y., 164 Guo, Z. T., 3300 Gupta, A. R., 41 Gupta, N. M., 110 Gupta, S. K., 2198 Gurd, F. R. N., 3362 Gureev, E. S., 1271, 1275, 1352 Gurevich, A. M., 583, 601 Gurman, S. J., 3108 Gurry, R. W., 926, 927 Gurvich, L. V., 2114, 2148, 2149, 2161, 2185 Gusev, N. I., 2531, 2532 Gusev, Yu. K., 549, 555, 556

Author Index

I-191

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Guseva, L. I., 1271, 1284, 1402, 1409, 1449, 1450, 1479, 1509, 1512, 1584, 1606, 1633, 1636, 2636, 2637, 2651 Gustafsson, G., 1661 Gu¨sten, H., 629 Gutberlet, T., 2452 Guthrei, R. I. L., 962, 963 Gutina, E. A., 2140 Gu¨tlich, P., 793 Gutmacher, G. R., 2636 Gutmacher, R., 860 Gutmacher, R. G., 857, 858, 860, 1288, 1291, 1423, 1452, 1453, 1455, 1473, 1474, 1475, 1476, 1513, 1516, 1586, 1839, 1845, 1847, 1848, 1850, 1864, 1871, 1872, 1885, 3045 Gutman, R., 2633 Gutowska, M., 113 Gutowski, K. E., 421, 1110, 2380 Guy, W. G., 187 Guymont, M., 76 Guzei, I., 2849 Guziewicz, E., 1056, 2347 Guzman, F. M., 181, 211 Guzman-Barron, E. S., 3361, 3378, 3380, 3381 Guzzi, G., 637 Gvozdev, B. A., 1402, 1422, 1423, 1629, 1636 Gwinner, G., 33 Gwozdz, E., 1509 Gwozdz, R., 188 Gygax, F. N., 2351 Gyoffry, B. L., 1669 Gysemans, M., 845 Gysling, H., 750 Haaland, A., 1958, 2169 Haar, C. M., 2924 Haas, E., 1071 Haas, H., 1735 Haas, M. K., 3067, 3288 Haba, H., 1445, 1450, 1484, 1696, 1718, 1735 Habash, J., 102, 104, 105, 2434, 2435 Habenschuss, A., 448, 2529, 3110 Haber, L., 110, 112 Haberberger, F., 1665, 1695 Habfast, K., 3310, 3311, 3312, 3313 Habs, D., 1880, 1881, 1882, 1883, 1884 Hackel, L. A., 1873 Hackett, M. A., 2278 Hadari, Z., 64, 336, 338, 722, 723, 724, 862, 994, 995, 3206 Haddad, S. F., 2443 Haeffner, E., 2732 Haegele, R., 551 Haessler, M., 204, 207 Hafey, F., 184 Hafez, M. B., 1352, 3024

Hafez, N., 3024 Haffner, H., 792, 3398, 3399 Hafid, A., 2877, 2890 Hafner, W., 2859 Haga, Y., 412, 2239, 2256, 2257, 2280 Hagan, L., 1513, 1633, 1639, 1646 Hagan, P. G., 1175, 1176 Hagberg, D., 596 Hagee, G. R., 166 Hagemann, F., 19, 27, 28, 30, 32, 35, 36, 37, 53, 1092, 1094, 1095, 1100, 1101, 2167, 2390, 2413, 2417, 2431 Hagemark, K., 353, 355, 360, 362, 396, 397 Hagenberg, W., 207 Hagenbruch, R., 1323 Hagenmuller, P., 70, 73, 77, 110 Hagerty, D. C., 1009, 1011 Haggin, J., 2982 Hagiwara, K., 2851 Hagrman, D. T., 357, 359 Ha¨gstrom, I., 184, 2674, 2767 Hagstro¨m, S., 60 Hahn, F. F., 3354 Hahn, O., 3, 4, 20, 24, 25, 163, 164, 169, 170, 172, 187, 254, 255 Hahn, R. L., 164, 781, 1116, 1148, 1155, 1356, 1636, 1639, 1659, 2526, 2594, 2595 Haigh, J. M., 2439 Hain, M., 1881 Haines, H. R., 904, 905, 1010 Haines, J. W., 3403, 3405 Hains, C. F., Jr., 2472 Haire, G., 2396 Haire, R. G., 33, 79, 192, 717, 719, 720, 721, 740, 744, 861, 863, 923, 989, 992, 994, 995, 1019, 1025, 1028, 1029, 1030, 1033, 1037, 1039, 1041, 1043, 1044, 1112, 1151, 1152, 1154, 1155, 1166, 1299, 1300, 1302, 1312, 1313, 1315, 1316, 1317, 1359, 1369, 1398, 1411, 1412, 1413, 1414, 1415, 1416, 1417, 1418, 1419, 1420, 1421, 1423, 1424, 1446, 1453, 1455, 1456, 1457, 1458, 1459, 1460, 1462, 1463, 1464, 1465, 1466, 1467, 1468, 1469, 1470, 1471, 1472, 1474, 1479, 1481, 1482, 1483, 1485, 1499, 1507, 1513, 1515, 1517, 1518, 1519, 1520, 1521, 1522, 1523, 1524, 1525, 1527, 1528, 1529, 1530, 1531, 1532, 1533, 1534, 1535, 1536, 1537, 1538, 1539, 1540, 1541, 1542, 1543, 1545, 1547, 1548, 1554, 1555, 1559, 1560, 1561, 1562, 1577, 1578, 1579, 1587, 1590, 1591, 1592, 1593, 1594, 1595, 1596, 1597, 1598, 1599, 1600, 1601, 1602, 1603, 1605, 1609, 1610, 1611, 1612, 1613, 1627, 1628, 1634, 1639, 1644, 1754, 1785, 1787,

I-192

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 1789, 1840, 1877, 1884, 2070, 2077, 2116, 2118, 2121, 2122, 2123, 2124, 2127, 2129, 2131, 2143, 2149, 2150, 2153, 2154, 2155, 2165, 2174, 2182, 2186, 2188, 2189, 2238, 2264, 2267, 2268, 2269, 2270, 2271, 2272, 2315, 2350, 2355, 2368, 2369, 2370, 2371, 2381, 2388, 2389, 2390, 2391, 2392, 2398, 2399, 2404, 2411, 2413, 2414, 2417, 2418, 2422, 2430, 2431, 2432, 3109, 3207, 3210, 3211 Haired, R. G., 2723, 2724 Haı¨ssinsky, M., 37, 162, 178, 179, 187, 191, 209, 216, 220, 221, 222, 225, 227 Hai-Tung, W., 2912 Hajela, S., 2924 Haka, H., 1267 Hakanen, M., 189 Hake, R. R., 2357 Hakem, N. L., 1178, 1180 Hakimi, R., 1825, 3409, 3413, 3420 Hakkila, E. A., 958, 959, 960, 961 Hakonson, T. E., 1803 Halachmy, M., 391 Halada, G. P., 3046, 3069, 3179 Halasyamani, P. S., 593, 2256 Halaszovich, S., 2633 Hale, W. H., 1290, 1291, 2387, 2388 Hale, W. H., Jr., 1419, 1420, 2397 Halet, J.-F., 435 Haley, M. M., 2864 Hall, A. K., 2457 Hall, C. M., 639, 3327 Hall, D., 2429 Hall, D. A., 546 Hall, F. M., 213, 217, 229 Hall, G. R., 1320, 1332, 1366 Hall, H. L., 1266, 1267, 1445, 1447, 1629, 1635, 1642, 1643, 1645, 1646, 1662, 1703, 1704, 2575 Hall, H. T., 67 Hall, J. P., 2191 Hall, L., 738 Hall, N. F., 106, 107 Hall, R. A. O., 2315 Hall, R. M., 1507 Hall, R. O., 945, 947, 949 Hall, R. O. A., 718, 955, 957, 981, 982, 1022, 1299, 2115, 2205 Hall, S. W., 2832 Hall, T. L., 78, 82, 2418, 2421, 2423 Halla, F., 104 Haller, P., 3030, 3031 Halliday, A. N., 639, 3327 Halow, I., 34 Halperin, J., 774, 2581, 2582 Halstead, G. W., 501, 503, 504, 506, 520, 2471, 2472, 2491, 2819, 2820, 2868

Ham, A. W., 3359, 3362, 3396, 3401, 3402, 3405 Ham, G. J., 3361 Hamaguchi, Y., 347, 2418 Hamaker, J. W., 77 Hamblett, I., 854 Hambly, A. N., 373, 374, 375, 549, 550, 555 Hamer, A. N., 170 Hamermesh, M., 1913 Hamill, D., 2165 Hamilton, J. G., 3341, 3342, 3348, 3354, 3356, 3387, 3395, 3401, 3405, 3413, 3423, 3424 Hamilton, J. H., 164 Hamilton, T., 1653 Hamilton, T. M., 1445, 1664, 1684, 1693, 1694, 1695, 1697, 1698, 1699, 1706, 1716 Hamilton, W. C., 337, 2404 Hammel, E. F., 853, 877 Hammer, J. H., 962 Hammond, R. P., 862, 897 Hamnett, A., 1681 Han, J., 1973 Han, Y., 1918, 1919, 1920 Han, Y. K., 1671, 1676, 1679, 1680, 1681, 1682, 1723, 1727, 1728, 1729, 2161 Hanchar, J. M., 282, 293, 638, 3094, 3327 Hancock, C., 67 Hancock, G. J., 42 Hancock, R. D., 2571, 2572, 2577, 2590 Handa, M., 391, 1004, 2723, 2724 Handler, M. R., 3326 Handler, P., 425, 509, 523, 2245 Handley, T. H., 164, 169 Handwerk, J. H., 76, 113, 303, 391, 393, 395, 1022 Handy, N. C., 596, 1907, 1921, 1922, 1923, 2528, 3102, 3113, 3123 Hanfland, C., 44 Hanlon, L. L., 3409 Hannah, S., 2464 Hannink, N. J., 182, 185, 1447, 1512, 1653, 1695, 1696, 1697, 1698, 1699, 1704, 1705 Hannon, J. P., 2234 Hannum, W. H., 2693, 2713 Hanrahan, R. J., 863 Hanscheid, H., 1828 Hansen, J. E., 1862, 2029 Hansen, M., 325, 405, 408, 409 Hansen, N. J. S., 164, 170 Hanson, B. D., 289 Hanson, P., 636 Hanson, S. L., 269, 277 Hanson, W. C., 1803 Hanusa, T. P., 2924 Hanuza, J., 429, 430, 431, 444, 450, 2260 Haoh, R. L., 1644 Hara, M., 1326, 1352

Author Index

I-193

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Hara, R., 2888 Harada, M., 616, 626, 627, 852, 2633, 2681 Harada, Y., 76, 113 Harari, A., 113 Harbottle, G., 231, 635, 3300, 3301 Harbour, R. M., 705, 714, 786, 787, 1290, 1291, 1449, 3281 Harbur, D. R., 892, 917, 918, 919, 920, 925, 930, 931, 933, 935, 960, 962, 963, 2355 Hardacre, C., 854 Hardcastle, K. I., 2924 Harder, B., 1186 Harding, J. H., 367, 368 Harding, S. R., 2205 Hardman, K., 66 Hardman-Rhyne, K., 66 Hardt, P., 116, 2865 Harduin, J. C., 3024 Hardy, A., 110 Hardy, C. J., 213, 218 Hardy, F., 2352 Hargittai, M., 2177 Harguindey, E., 1895, 1897, 1908 Harland, C. E., 846 Harman, W. D., 2880 Harmon, C. A., 2851, 2852 Harmon, C. D., 2690 Harmon, H. D., 1477, 1606, 2565, 2580 Harmon, K. M., 707, 837, 863, 2704, 2708, 2709 Harnett, O., 261 Harper, E. A., 1006, 2407, 2408, 3214 Harper, L. W., 3239 Harper, P. E., 2426, 2427 Harrington, C. D., 303, 315, 317, 319, 559, 560 Harrington, J. D., 2684 Harrington, S., 942, 944, 945, 948 Harris, H. B., 80 Harris, J., 6, 1660, 1662, 1692 Harris, L. A., 86, 87, 90, 91, 113, 342, 357 Harris, R., 3179 Harris, W. R., 1824, 3349, 3359, 3364, 3365, 3376, 3378 Harrison, J. D., 3424 Harrison, J. D. L., 1058, 1059, 1060, 1062, 1065, 1066, 1067, 1070 Harrison, R. J., 1906, 1918, 1919, 1920 Harrison, W. A., 933, 2308 Harrod, J. F., 2916, 2965, 2966, 2974, 2979 Harrowfield, J. M., 2456, 2457, 2458, 2461 Harrowfield, J. M. B., 1174 Hart, B. T., 3057 Hart, F. A., 93, 452 Hart, H. E., 3413 Hart, K. P., 278 Hart, R. C., 2271 Hartley, J., 986 Hartman, D. H., 2691

Hartman, M. J., 3027 Hartmann, O., 2284 Hartmann, W., 164 Hartree, D. R., 2020, 2022 Harvey, A. R., 739, 742, 744, 745 Harvey, B. G., 5, 164, 186, 187, 988, 1049, 1508, 1577, 1624, 1628, 1629, 1630, 1632, 1635, 1660, 2635, 2638, 2639 Harvey, B. R., 782, 3021, 3022 Harvey, J. A., 53 Harvey, M. R., 912, 958, 959, 960 Hasan, A., 3409 Hasbrouk, M. E., 892, 942 Hascall, T., 2849 Haschke, F. M., 64, 65 Haschke, J., 975 Haschke, J. M., 328, 331, 332, 333, 334, 337, 723, 724, 863, 864, 973, 974, 975, 976, 977, 978, 979, 989, 990, 991, 992, 994, 995, 1025, 1026, 1027, 1028, 1029, 1030, 1035, 1039, 1040, 1041, 1042, 1145, 1303, 1534, 1798, 2114, 2136, 2141, 2147, 2188, 2189, 2190, 2389, 2395, 2403, 2404, 3109, 3177, 3199, 3200, 3201, 3202, 3204, 3205, 3206, 3207, 3208, 3209, 3210, 3211, 3212, 3213, 3214, 3215, 3216, 3217, 3218, 3219, 3220, 3221, 3222, 3223, 3224, 3225, 3227, 3228, 3229, 3230, 3231, 3232, 3233, 3234, 3235, 3236, 3237, 3238, 3239, 3240, 3241, 3242, 3243, 3244, 3245, 3246, 3247, 3249, 3250, 3251, 3252, 3253, 3254, 3255, 3256, 3257, 3258, 3259, 3260, 3262 Hasegawa, K., 718 Hasegawa, Y., 40, 2568, 2625 Haselwimmer, R. K. W., 407, 2239, 2359 Hash, M. C., 279, 861 Hashitani, H., 383 Hasilkar, S. P., 1174 Haskel, A., 2834, 2835, 2913, 2925, 2927, 2930, 2932, 2935, 2936, 2940, 2958, 2984, 2987 Hass, P. A., 1033 Hassaballa, H., 2452 Hasse, K. D., 1681 Hastings, J. B., 2234 Hasty, R. A., 77 Haswell, C. M., 2868, 2869 Haswell, S. J., 3281 Hata, K., 1266, 1267 Hataku, S., 1272, 1273 Hatcher, C., 279 Hathway, J. L., 2449 Hatsukawa, Y., 1266, 1267 Hatter, J. E., 854, 2690 Hattori, H., 76 Haubach, W. J., 173

I-194

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Hauback, B. C., 66, 338, 339 Haubenreich, P. N., 487, 2632 Hauck, J., 208, 372, 373, 375, 378, 2241, 2439 Haufler, R. E., 2864 Haug, H., 395, 1069, 1422, 2431 Haug, H. O., 1402, 1409, 1415, 1418, 1419, 1464, 1467, 2396, 2397, 2418 Haug, H. W., 1529, 1530 Hauge, R. H., 2165, 2864 Haung, K., 1515 Hauser, O., 104 Hauser, W., 763, 766, 1425, 1426, 3070 Hauske, H., 35, 36, 38, 1100, 1101, 1312, 1357, 1418, 2441 Hausman, E., 172, 174, 182 Havel, J., 2585, 3046 Havela, L., 97, 338, 339, 861, 921, 929, 953, 964, 1023, 1056, 2307, 2347, 2351, 2353, 2355, 2356, 2357, 2358, 2359, 2360, 2361, 2363, 2366, 2368 Haven, F., 3355 Havrilla, G. L., 3041, 3069 Haw, J. F., 2490, 2859, 2860 Hawes, L. L., 937, 938, 939 Hawk, P. B., 3362 Hawkes, S. A., 2473, 2816 Hawkins, D. T., 2115 Hawkins, H. T., 2452, 2456 Hawkins, N. J., 1080, 1086, 1088 Hawkinson, D. E., 180 Hawthorne, F. C., 259, 261, 262, 268, 272, 283, 286, 287, 289, 290, 298, 2193, 2426, 3093, 3094, 3118, 3155, 3160 Hay, B. P., 2660 Hay, P. J., 576, 580, 589, 596, 620, 621, 1192, 1193, 1194, 1196, 1198, 1199, 1287, 1777, 1893, 1908, 1916, 1918, 1920, 1921, 1922, 1923, 1924, 1925, 1926, 1927, 1931, 1932, 1934, 1935, 1936, 1937, 1938, 1940, 1941, 1958, 1959, 1965, 1966, 2165, 2260, 2528, 2872, 2874, 2891, 3102, 3111, 3112, 3113, 3121, 3122, 3123, 3126, 3128 Hay, S., 892 Hayashi, H., 2185, 2186 Hayden, L. A., 267, 268, 289, 291, 580, 582, 583, 2434, 2435 Hayek, E., 82, 83 Hayes, G. R., 2688 Hayes, R. G., 750, 1188, 1946, 2253, 2469, 2853 Hayes, S. L., 862, 892, 2199, 2202 Hayes, W., 357, 389, 2278 Hayes, W. N., 1530, 1533, 1543, 2077, 2416 Hayman, C., 2160, 2208 Hays, D. S., 2980 Hayward, B. R., 319 Hayward, J., 457, 486

Hazemann, J. L., 389 He, J., 2979 He, L., 792 He, M.-Y., 2999 He, P., 29 He, X., 2752, 2753 He, X. M., 2752, 2753 Head, E. L., 1028, 1029, 1030, 1045, 1048 Head-Gordon, M., 1902 Heal, H. G., 988, 1049 Heald, S. M., 291, 1810, 3160, 3161, 3164 Healy, J. W., 3424 Healy, M. J. F., 854 Healy, T. V., 1554 Heathman, S., 97, 192, 719, 720, 739, 742, 923, 1300, 1462, 1522, 1578, 1594, 1754, 1785, 1787, 1789, 2315, 2355, 2368, 2369, 2370, 2371, 2407 Heatley, F., 115, 116, 2442, 2448, 2880, 2883 Heaton, L., 2283, 2407 Heaven, M. C., 1973 Heavy, L. R., 3364, 3378, 3387 Hebert, G. M., 461 Hebrant, M., 2649, 2657 Hecht, F., 109, 114, 3029 Hecht, H. G., 382, 469, 491, 502, 503, 504, 505, 1194, 2082, 2241, 2243, 2244, 2246 Heckel, M. C., 2584 Hecker, S. S., 813, 814, 863, 889, 890, 892, 893, 895, 896, 917, 918, 919, 920, 921, 924, 925, 930, 931, 933, 935, 936, 943, 945, 957, 960, 961, 962, 968, 970, 971, 972, 973, 974, 979, 980, 983, 985, 2310, 2355, 2371, 3213, 3250 Heckers, U., 410 Heckley, P. R., 204 Heckly, J., 541 Heckmann, G., 2480, 2836 Heckmann, K., 2633 Hedberg, M., 3173 Hedden, D., 2924, 2999 Hedger, H. J., 1006, 2407, 2408 Hedrick, J. B., 1804 Heeg, M. J., 3107 Heeres, A., 2924 Heeres, H. J., 2924 Heerman, L., 2688, 2690 Heffner, R. J., 2351 Hefter, G., 2577, 2579 Hegarty, J., 763, 766, 2095 Hegedus, L. S., 2924 Heger, G., 380, 1928 Heiberger, J. J., 2715 Heid, K. R., 3346 Heidt, L. J., 595 Heier, K. S., 3014 Heimbach, P., 116, 2865

Author Index

I-195

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Hein, R. A., 352, 357, 2350 Heindl, F., 96 Heinecke, J. W., 3358 Heineman, W. R., 3107, 3108 Heinemann, C., 1971, 1990 Heinemann, D., 1671 Heining, C., 1923 Heinrich, G., 227 Heinrich, Z., 716 Heiple, C. R., 1018 Heirnaut, J. P., 2388 Heise, K.-H., 2568, 3102, 3135, 3138, 3140, 3141, 3142, 3145, 3147, 3149, 3150, 3182 Helean, K., 113, 270, 287 Helean, K. B., 2157, 2159, 2193 Helfferich, F., 2625 Helfrich, R., 2352 Helgaker, T., 1905 Hellberg, K.-H., 421, 485, 557 Helliwell, M., 578, 589, 2400, 2401, 2441, 2442, 2448, 2584 Hellmann, H., 745, 2434, 2436 Hellmann, K., 1882, 1884 Hellwege, H. E., 744, 1369, 1455, 1470, 1471, 2430, 2431, 2432 Helm, L., 609, 614, 3110 Helminski, E. L., 1267 Hem, J. D., 3097, 3164 Hemmi, G., 2464, 2465 Hemming, S., 3056 Henche, G., 550, 570 Henderson, A. L., 932, 967 Henderson, D. J., 1284, 1293, 1449, 1509, 1513, 1585, 1629 Henderson, R. A., 1445, 1447, 1629, 1635, 1642, 1643, 1645, 1646, 1647, 1662, 1703, 1704, 1705, 2575 Hendricks, M., 1695, 1699 Hendricks, M. B., 815 Hendricks, M. E., 203, 425, 431, 435, 439, 469, 474, 1472, 2229, 2230, 2241, 2257, 2258, 2259, 2261, 2262, 2264, 2267, 2268, 2695 Hendrix, G. S., 1003, 1004, 1005, 1006 Henge-Napoli, M. H., 3052, 3413, 3419, 3423 Henkie, Z., 100, 412, 2411 Henling, L. M., 2924 Hennelly, E. J., 1267 Hennig, C., 389, 589, 596, 602, 612, 616, 621, 2582, 3102, 3106, 3107, 3111, 3112, 3114, 3119, 3121, 3122, 3139, 3140, 3147, 3148, 3149, 3152, 3155, 3156, 3165, 3166, 3167, 3169, 3179, 3180, 3181, 3182 Henrich, E., 382, 730, 763, 766, 2244 Henrickson, A. V., 837 Henrion, P. N., 732, 734

Henry, J. Y., 2409 Henry, R. F., 2452, 2453, 2454 Henry, W. E., 335, 2350 Hensley, D. C., 1626, 1627, 1637, 1638, 1639, 1644, 1659 Hentz, F. C., 123 Hepiegne, P., 2890 Heppert, J. A., 2670 Hequet, C., 1285 Herak, M. J., 182 Herak, R., 356, 2393 Herbst, J. F., 1461 Herbst, R. J., 1004 Herbst, R. S., 1282, 2739, 2741 Herbst, S., 2739 Hercules, D. M., 3046 Herczeg, J. W., 1811 Hergt, J. M., 3326 Hering, J. G., 287 Herlach, D., 1447 Herlert, A., 1735 Herlinger, A. W., 2652 Herman, J. S., 129, 130, 131, 132 Hermann, G., 182, 209, 215, 224, 1447 Hermann, J. A., 490, 837, 1271, 1291 Hermann, W. A., 3003 Hermanowicz, K., 430, 444, 450, 2260 Hermansson, K., 118 Herment, M., 25 Herniman, P. D., 1332, 1366 Herpin, P., 109 Herrero, J. A., 2441, 2442 Herrero, P., 2439, 2440 Herrick, C. C., 103, 112, 886, 888 Herring, G. M., 3403, 3404, 3407, 3410 Herrman, W. A., 2918 Herrmann, G., 25, 60, 164, 789, 794, 859, 1296, 1403, 1452, 1513, 1662, 1665, 1695, 1703, 1704, 1738, 1875, 1876, 1877, 2591, 3044, 3047, 3048, 3320, 3321 Herrmann, H., 413 Herschel, W., 253 Hertogen, J., 636, 3306 Hertz, M. R., 172, 173, 175 Hery, Y., 195, 204, 207, 2411, 2413 Herzberg, G., 1911, 1913, 1914 Herzog, H., 2728 Hesek, D., 2457 Hess, B. A., 1670, 1672, 1673, 1675, 1682, 1898, 1906 Hess, N. J., 127, 128, 130, 131, 270, 595, 861, 932, 1041, 1043, 1112, 1154, 1155, 1160, 1162, 1164, 1166, 1179, 1359, 1927, 1928, 3039, 3087, 3108, 3109, 3113, 3118, 3133, 3134, 3135, 3136, 3137, 3163, 3171, 3210 Hess, R., 932, 1041, 1155, 3109, 3210

I-196

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Hess, R. F., 97, 861, 1041, 1043, 1112, 1154, 1155, 1166 Hess, W. P., 291, 3160, 3161, 3164 Hessberger, F. P., 6, 14, 164, 1582, 1653, 1660, 1701, 1713, 1717, 1737, 1738 Hessler, J. P., 763, 766, 1423, 1453, 1454, 1455, 1515, 1544, 1545, 2094, 2095, 2096, 2098, 2099, 2534, 3034, 3037 Heuer, T., 428, 429, 436, 440, 451 Heully, J.-L., 1683, 1909, 1918, 1919, 1931, 1932 Heumann, K. G., 164 Hewat, A. W., 469, 475 Hey, E., 2480 Heydemann, A., 27, 170 Hickmann, U., 1738 Hicks, H. G., 180 Hidaka, H., 271, 824, 3046 Hiebl, K., 67, 71 Hien, H. G., 407 Hiernaut, J. P., 357, 1029, 1036, 1045, 1047, 1971, 2140, 2149, 3212 Hiernaut, T., 3070 Hies, M., 1879, 1880, 1881, 1882, 1883, 1884 Hiess, A., 2236, 2239, 2352 Hietanen, S., 120, 121, 123, 124, 2548, 2549, 2550 Higa, K., 631 Higa, K. T., 2472, 2826 Higashi, K., 768 Higashi, T., 2719, 2720 Higgens, G. H., 1622 Higgins, C. E., 1323, 1324, 1361 Higgins, G. H., 5, 1577 Higgins, L. R., 484 Higgy, R. H., 3014 Hightower, J. R., Jr., 2700, 2701 Hijikata, T., 717, 1270, 2134, 2135, 2695, 2696, 2697, 2698, 2700, 2717, 2719, 2720 Hildebrand, N., 1738 Hildenbrand, D., 70, 82, 420, 1937, 1938 Hildenbrand, D. L., 731, 734, 2114, 2149, 2161, 2169, 2179 Hill, C., 598, 2584, 2674, 2676, 2761, 2762 Hill, D., 2752 Hill, D. C., 303, 391, 393, 395 Hill, D. J., 1811 Hill, F. B., 854 Hill, F. C., 257, 281, 282, 288 Hill, H., 719 Hill, H. H., 35, 68, 191, 193, 960, 962, 1302, 1330, 1403, 1411, 1459, 1527, 1593, 2332, 2350 Hill, J., 200, 204, 527, 737, 2418 Hill, J. P., 2288 Hill, M. W., 164, 180, 182 Hill, N. A., 67, 303 Hill, N. J., 711, 761, 2757

Hill, O. F., 835, 2730 Hill, R., 133 Hill, R. N., 828 Hill, S. J., 3280 Hillary, J. J., 164, 173, 177, 180 Hillberg, M., 2284 Hillebrand, W. F., 2391 Hillebrandt, W., 3016, 3063 Hilliard, J. E., 828 Hilliard, R. J., 3244, 3245, 3246 Hillier, I. H., 1926, 1928, 1929, 1931 Hillman, A. R., 3108 Hills, J. W., 2679, 2681 Hilscher, G., 2362 Himes, R. C., 415, 2413 Himmel, H.-J., 1968 Hinatsu, Y., 382, 387, 389, 390, 391, 392, 2244, 2252 Hinchey, R. J., 2538 Hincks, E. P., 53 Hincks, J. A., 1033 Hindman, J. C., 220, 222, 227, 606, 727, 748, 753, 759, 768, 781, 988, 1088, 1181, 1194, 1333, 1356, 2080, 2084, 2086, 2527, 2582, 2594, 2599, 2601, 3099 Hines, M. A., 615 Hingmann, R., 6 Hinman, C. A., 369 Hinrichs, W., 1190 Hinton, J. F., 2532 Hinton, T. G., 3296 Hipple, W. G., 2452, 2453, 2454 Hirao, K., 1898, 1905, 1906, 1909, 1918, 1919, 1920 Hirashima, K., 395 Hirata, M., 1049, 1676, 1680, 1696, 1718, 1735 Hirata, S., 1906 Hirayama, F., 2102 Hirose, K., 3023 Hirose, T., 1266, 1267 Hirose, Y., 2811 Hirota, M., 410 Hirsch, A., 5, 1577, 1622 Hirsch, G. M., 3387, 3388 Hisamatsu, S., 1822 Hiskey, J. B., 1288, 2762 Hitachi Metals Ltd., 188 Hitchcock, P. B., 116, 117, 1776, 1964, 2240, 2473, 2479, 2480, 2484, 2491, 2803, 2816, 2830, 2844, 2863, 2875, 2886, 2887, 2912 Hitt, J., 2479 Hitterman, R. L., 102, 106, 320, 2429 Hitti, B., 2351 Hiyama, T., 2969 Hjelm, A., 2364 Hlousek, J., 264, 281

Author Index

I-197

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Ho, C. H., 3167 Ho, C. I., 322 Ho, C. Y., 1593 Ho, C.-K., 188 Hoard, J. L., 530, 560, 2421 Hobart, D., 1324, 1325, 1326, 1328, 1329, 1341, 1356, 1365, 1366, 1369 Hobart, D. E., 745, 749, 757, 988, 1110, 1116, 1123, 1125, 1131, 1132, 1145, 1148, 1151, 1152, 1155, 1159, 1162, 1163, 1164, 1165, 1166, 1444, 1445, 1455, 1465, 1470, 1471, 1474, 1479, 1481, 1547, 1558, 1559, 1636, 1805, 1925, 1926, 1927, 2129, 2131, 2531, 2553, 2558, 2583, 2592, 2594, 3036, 3111, 3122, 3130, 3165, 3169 Hobbs, D. T., 1401 Hoberg, J. O., 2924, 2933 Hoch, M., 392, 396 Hochanadel, C. J., 3221 Hocheid, B., 892, 905, 906, 907 Hochheimer, H. D., 97 Hocks, L., 116, 2815 Hodge, H. C., 3340, 3354, 3355, 3386, 3413, 3421, 3423 Hodge, H. J., 2159, 2161 Hodge, M., 421 Hodge, N., 370, 1077 Hodges, A. E., 2188 Hodges, A. E., III, 990, 991, 992, 994, 995, 1028, 1035, 2404, 3204, 3205, 3206, 3207, 3208, 3210, 3212, 3213, 3215, 3216, 3219 Hodgeson, T., 639 Hodgson, A., 1179, 2591, 3354, 3413, 3415, 3416, 3419, 3420, 3421 Hodgson, B., 854 Hodgson, K. O., 116, 1188, 1943, 1944, 2473, 2486, 2488, 2816, 2852, 2853 Hoehner, M., 605, 2464 Hoehner, M. C., 2464 Hoekstra, H., 341, 342, 346, 350, 356, 357, 358, 372, 375, 378, 380, 393, 1312, 1313, 3171 Hoekstra, H. R., 340, 342, 343, 345, 346, 348, 350, 355, 356, 357, 358, 371, 372, 373, 374, 376, 378, 380, 382, 383, 384, 385, 386, 387, 388, 389, 392, 719, 1057, 1060, 1061, 1466, 1517, 2156, 2157, 2392, 2393, 2394, 3214 Hoektra, P., 3065 Hoel, P., 1285, 2657, 2756 Hoelgye, Z., 716 Hoff, H. A., 1022 Hoff, J., 3313 Hoff, J. A., 231, 3314 Hoff, P., 3282 Hoff, R., 1660

Hoff, R. W., 1398, 1623 Hoffert, F., 1273 Hoffert, M. I., 2728 Hoffman, D., 1114, 1148, 1155, 1160, 1163, 3043 Hoffman, D. C., 182, 185, 186, 227, 815, 821, 824, 988, 1114, 1168, 1182, 1398, 1400, 1445, 1447, 1512, 1582, 1629, 1632, 1635, 1642, 1643, 1645, 1646, 1647, 1652, 1653, 1660, 1661, 1662, 1663, 1664, 1665, 1666, 1670, 1671, 1679, 1684, 1685, 1690, 1693, 1694, 1695, 1696, 1697, 1698, 1699, 1701, 1702, 1703, 1704, 1705, 1706, 1708, 1709, 1711, 1712, 1713, 1714, 1716, 1717, 1718, 1728, 1735, 1737, 1738, 1760, 1804, 2575, 2583, 2591, 2669, 3016, 3022, 3276, 3419 Hoffman, G., 200, 747, 749 Hoffman, J. J., 1008 Hoffman, P., 740 Hoffman, S., 6, 7, 164 Hoffmann, A., 77 Hoffmann, C. G., 97 Hoffmann, G., 1034, 1172, 2164, 2407, 2427, 2430, 2431 Hoffmann, P., 788 Hoffmann, R., 113, 378, 1917, 1954, 1957, 1958, 2400, 2841 Hoffmann, R.-D., 69, 70, 72, 73 Hofmann, P., 1957, 1958, 2841 Hofmann, S., 1582, 1653, 1654, 1660, 1701, 1713, 1717, 1719, 1720, 1735, 1737, 1738 Ho¨gfeldt, E., 129, 597 Hohenberg, P., 1903, 2327 Hohorst, F. A., 32 Hoisington, D., 457, 486 Hojo, T., 631 Ho¨k-Bernstro¨m, B., 2592 Holah, D. G., 115, 202, 204, 436, 453, 738, 1084, 1095, 1097, 1312, 2416 Holah, D. H., 204 Holbrey, J. D., 2686, 2691 Holc, J., 597 Holcomb, H. P., 1416, 1430 Holden, A. N., 321 Holden, N. E., 27, 164, 255, 256, 1398 Holden, R. B., 61, 319 Holden, T., 2360 Holden, T. M., 1055 Ho¨lgye, Z., 1324 Holland, M. K., 791 Holland, R. F., 485, 518 Hollander, F. J., 2847, 2986 Hollander, J. M., 164, 1452 Holland-Moritz, E., 2238, 2279, 2354 Holleck, H., 1009, 1019

I-198

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Holley, C. E., 744, 1004, 1008, 1028, 2114, 2195, 2196, 2197, 2198, 2199, 2200 Holley, C. E., Jr., 744, 1004, 1028, 1029, 1030, 1045, 1048, 1463 Holliger, P., 271, 824, 3172 Holloway, J. H., 186, 197, 199, 379, 421, 441, 457, 484, 485, 487, 507, 518, 520, 521, 536, 539, 543, 557, 563, 566, 731, 732, 734 Holm, E., 704, 783, 3014, 3017, 3026, 3029, 3056, 3057, 3296 Holm, L. W., 1636 Holmberg, R. W., 120, 121, 2548, 2549 Holmes, J. A., 319 Holmes, N. R., 350 Holmes, R. G. G., 856, 2684 Holt, K., 3409 Holt, M., 965, 967 Holthausen, M. C., 1903 Holtkamp, H., 101 Holtz, M. D., 1452 Holtzman, R. B., 226 Holzapfel, W. B., 2315, 2370 Homma, S., 857 Honan, G. J., 620 Honeyman, B. D., 3016 Hong, G., 1671, 1907, 1959, 1960 Hong, H., 965, 967 Hong, S., 2984 Hongye, L., 1267 Ho¨nigschmid, O., 61 Honkimaki, V., 3042, 3043 Hooper, E. W., 1093 Hoover, M. D., 3354 Hopkins, H. H., Jr., 164, 1093 Hopkins, T. A., 2687 Hopkins, T. E., 423 Hoppe, R., 77, 450, 729, 1061, 1064 Hoppe, W., 2464 Hor, P. H., 77 Horen, D. J., 25 Horn, I., 3047 Horner, D. E., 1049 Horovitz, M. W., 3359, 3361, 3368, 3373, 3387, 3388, 3400 Horrocks, W. D., Jr., 1327 Horsley, J. A., 1916 Horwitz, E., 1278, 1279, 1280, 1281, 1283, 1284, 1292, 1293, 1294 Horwitz, E. P., 633, 707, 713, 716, 1152, 1408, 1431, 1449, 1508, 1509, 1511, 1513, 1585, 1629, 1633, 1635, 2626, 2642, 2643, 2652, 2653, 2655, 2656, 2660, 2661, 2666, 2667, 2671, 2727, 2738, 2739, 2740, 2741, 2742, 2746, 2747, 2748, 2750, 2760, 2768, 3282, 3283, 3284, 3285, 3286, 3295 Horwitz, P., 1281, 1282

Horyn, R., 2409 Hoshi, H., 845, 2759, 2760, 2762 Hoshi, M., 109, 395, 1163, 1312, 1321, 1431 Hoshino, K., 855, 856 Hoshino, Y., 338 Hoskins, P. W. O., 287 Hosseini, M. W., 2457 Host, V., 2655 Hotchkiss, P. J., 2432 Hotoku, S., 711, 712, 760, 2757 Hough, A., 982, 1058 Houk, R. S., 3324 Houk, Z., 2669 Houpert, P., 3423 Hovey, J. K., 119, 2132, 2133 Howard, B., 3355, 3366 Howard, C. J., 502, 503 Howard, G., 2676 Howard, W. M., 1884 Howatson, J., 2439, 2440, 2568 Howell, R. H., 986 Howells, G., 3353, 3403, 3405 Howells, G. R., 2731, 3403 Howes, K. R., 595, 619, 620 Howie, R. A., 3169 Howland, J. J., Jr., 2264 Howlett, B., 398 Hoyau, S., 1921, 1922 Hoyle, F., 3014 Hrashman, D. R., 2234 Hristidu, Y., 630, 2814 Hromyk, E., 3349, 3398, 3399 Hrynkiewicz, A., 13 Hrynkiewicz, A. Z., 1660 Hseu, C. S., 2801, 2851 Hsi, C. K. D., 3166, 3167 Hsini, S., 468 Hsu, F., 2360 Hsu, M., 1695 Hu, A., 1906 Hu, J., 116, 2473, 2479, 2480, 2484, 2816, 2830, 2844, 2875, 2912 Hu, T., 2665 Hu, T. D., 1363 Huang, C. Y., 2315 Huang, J., 1368, 1454, 1544, 2042, 2044, 2047, 2053, 2062, 2068, 2072, 2073, 2075, 2089, 2153, 2157, 2265 Huang, J. W., 2668 Huang, K., 1452, 2068, 2089 Huang, K.-N., 1515 Huary, P. G., 2070 Hubbard, R. P., 1845, 1846 Hubbard, W. N., 80, 81, 421, 436, 437, 470, 471, 473, 475, 476, 486, 502, 504, 505, 510, 511, 539, 541, 546, 553, 1086, 1098, 1101, 2114, 2128, 2157, 2160,

Author Index

I-199

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 2161, 2163, 2165, 2167, 2168, 2169, 2172, 2181, 2182, 2186 Hu¨bener, S., 1447, 1451, 1523, 1524, 1592, 1593, 1628, 1634, 1643, 1662, 1679, 1684, 1693, 1706, 1707, 1708, 1709, 1711, 1712, 1716, 1720, 2123 Huber, E. J., Jr., 1028, 1029, 1030, 1045, 1048 Huber, G., 33, 60, 859, 1452, 1513, 1588, 1590, 1840, 1875, 1876, 1877, 3047, 3321 Huber, J. G., 62, 63, 333 Huberman, B. A., 3240 Hubert, H., 1285, 2756, 2761 Hubert, S., 81, 120, 126, 422, 430, 431, 450, 451, 469, 482, 492, 1352, 1368, 1369, 1428, 1476, 1477, 1551, 1554, 1606, 1629, 2042, 2054, 2059, 2060, 2062, 2063, 2064, 2065, 2066, 2067, 2074, 2096, 2230, 2248, 2249, 2259, 2263, 2265, 3037, 3054, 3101, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118 Hubin, R., 109, 113 Huchton, K. M., 851 Huddle, R. A. U., 3244 Hudgens, C. R., 487, 903 Hudson, E. A., 287, 289, 301, 602, 861, 1166, 2583, 2812, 3087, 3089, 3090, 3101, 3108, 3113, 3118, 3130, 3131, 3140, 3141, 3145, 3146, 3148, 3150, 3152, 3154, 3155, 3156, 3158, 3160, 3167, 3170 Hudson, M. I., 1285 Hudson, M. J., 1262, 1270, 1285, 1287, 2584, 2657, 2659, 2674, 2675, 2756, 2761 Hudswell, F., 1186 Huebener, S., 1628, 1634 Huet, N., 2674 Huff, E. A., 3059, 3060 Huffman, A. A., 487 Huffman, A. C., 3065 Huffman, J. C., 1185, 2490, 2814, 2832, 2867, 2868, 2879, 2916 Hu¨fken, T., 70 Hufnagl, J., 2351 Hu¨fner, S., 2015, 2036, 2043, 2044, 2045 Hugen, Z., 1278, 2653 Hughes, A. E., 39 Hughes, C. R., 3165, 3167 Hughes, D. G., 892, 909, 912 Hughes, K.-A., 259, 262, 281, 288, 290, 2429 Hughes, T. G., 2731 Hughes-Kubatko, K.-A., 270, 287, 2193 Hugus, Z. Z., Jr., 1915 Huheey, J. E., 2575 Huhmann, J. L., 2965 Huie, R. E., 371 Huizenga, J. R., 5, 1577 Huizengo, J. R., 1622

Hulet, E. K., 6, 1288, 1291, 1297, 1398, 1423, 1453, 1473, 1474, 1475, 1476, 1509, 1513, 1516, 1530, 1533, 1543, 1584, 1585, 1586, 1605, 1623, 1629, 1631, 1633, 1635, 1636, 1639, 1641, 1647, 1692, 1695, 1696, 1707, 1719, 1848, 1849, 1850, 1858, 2416, 2525, 2526, 2529, 2636, 2670, 3346, 3347 Hull, G., 319 Hulliger, F., 100, 412, 2359, 2407, 2411 Hult, E. A., 1666, 1695, 1702, 1717, 1735 Hult, E. K., 2077 Hultgren, A., 2732 Hultgren, R., 2115 Hults, W. L., 929 Hulubel, H., 227 Hummel, P., 577 Hummel, W., 590 Hund, F., 395 Hung, C. C., 3024 Hung, S.-T., 472 Hungate, F. P., 3341 Hu¨niger, M., 97 Hunt, B. A., 2767 Hunt, D. C., 988 Hunt, E. B., 67, 71, 2408 Hunt, F., 2679 Hunt, L. D., 1639, 1644, 1659 Hunt, P. D., 352, 365, 367 Hunt, R. D., 1971, 1972, 1976, 1977, 1978, 1983, 1988, 1989, 2894 Huntelaar, M. E., 2154, 2185, 2186, 2187 Hunter, D. B., 270, 274, 861, 3039, 3095, 3165, 3168, 3172, 3174, 3175, 3176, 3177, 3179, 3181 Hunter, W. E., 2480, 2812, 2829, 2924 Huntley, D. J., 225 Huntoon, R. T., 1427 Huntzicker, J. J., 353, 357, 359 Huray, P. G., 1411, 1418, 1421, 1423, 1460, 1472, 1525, 1542, 1543, 1602, 1603, 2238, 2264, 2267, 2268, 2269, 2270, 2271, 2272, 2356 Hure´, J., 2712 Hurley, F. H., 2685 Hursh, J. B., 3340, 3366, 3383, 3424 Hurst, G. S., 3319 Hurst, H. J., 1107 Hurst, R., 1078, 1079, 1080, 1086 Hursthouse, A. S., 3056, 3059, 3072, 3106 Hursthouse, A. S. A., 705, 706, 783 Hursthouse, M., 1943, 1956, 2473, 2803, 2806, 2807, 2854, 2856 Hursthouse, M. B., 117, 2240 Hurtgen, C., 738, 1100, 1303, 1312, 1313, 2389, 2396 Hussey, C. L., 2686 Hussonnois, H., 1629

I-200

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Hussonnois, M., 181, 211, 1352, 1425, 1428, 1476, 1477, 1550, 1551, 1554, 1606, 1629, 1688, 1690, 1700, 1718, 2067 Hutchings, M. T., 357, 389, 2278, 2279, 2283, 2284, 2285, 2389 Hutchings, T. E., 1196, 1198, 2080, 2085, 2086, 2561 Hutchinson, J. M. R., 783 Hutchison, C. A., 425, 509, 523, 2083 Hutchison, C. A., Jr., 2241, 2243, 2245, 2272 Hutchison, J. E., 2660 Hutson, G. V., 2690 Hutter, J. C., 1282, 2655, 2738, 2739, 2740 Hutton, R. C., 3062 Huxley, A., 407, 2236, 2239, 2352, 2359 Huyghe, M., 103, 112 Huys, D., 31, 32 Huzinaga, S., 1908 Hwang, I.-C., 535 Hwerk, J. H., 76, 113 Hyde, E. K., 25, 55, 107, 164, 167, 181, 182, 187, 224, 817, 822, 1095, 1101, 1267, 1304, 1499, 1503, 1577, 1580, 1584, 1660, 1703, 1756, 1761, 3281 Hyde, K. R., 1011 Hyder, M. L., 1480, 1481, 1484, 1549 Hyeon, J.-Y., 575, 2469 Hyland, G. J., 357, 359, 1077, 2140 Hyman, H. H., 317, 506, 508, 2632 Hynes, R., 2979 IAEA, 303, 314, 345, 367, 398, 822, 1025, 1031, 1045, 1047, 1048, 1071, 2114, 2115, 2123, 2145, 2195, 2197, 2200, 3199, 3201, 3202, 3246, 3260 Iandelli, A., 411, 2411 Ibberson, R. M., 340, 345, 348 Ibers, J. A., 97, 420 Ibrahim, S. A., 133 Ice, G. E., 2234 Ichikawa, M., 1019 Ichikawa, S., 1445, 1450, 1484, 1696, 1718, 1735 Ichikawa, Y., 1266, 1267 ICRP, 1822, 1823, 3340, 3344, 3352, 3355, 3358, 3404, 3405, 3424 Iddings, G. M., 164 Idira, M., 2371 Idiri, M., 97, 192, 1754, 1787, 1789, 2370 Ifill, R. O., 280 Igarashi, S., 789, 790, 3059, 3062, 3068, 3072 Igarashi, Y., 789, 790, 3059, 3062, 3068, 3072 Iglesias, A., 3162 Igo, D. H., 3108 Iguchi, T., 338 Ihara, E., 2924 Ihara, N., 2568

Ihde, A. J., 19 Iida, T., 962, 963 Iizuka, M., 717, 2698 Ijdo, D., 2153, 2185, 2186, 2187 Ikawa, M., 167 Ikeda, H., 713 Ikeda, N., 789, 790, 3017, 3059, 3062, 3068, 3072 Ikeda, S., 627 Ikeda, T., 762, 766, 787 Ikeda, Y., 608, 609, 617, 618, 620, 852, 2633, 2681, 2738 Ikezoe, H., 164 Ikushima, K., 2280 Ildefonse, P., 272, 292, 3152, 3155, 3168 Ilger, J. D., 3024 Iliev, S., 14, 1653, 1654, 1707, 1719, 1736, 1738 Iliff, J. E., 61, 78 Ilin, E. G., 82 Il’inskaya, T. A., 727 Illemassene, M., 2042, 2062, 2096 Illgner, Ch., 1880, 1882, 1884 Illies, A. J., 412 Il’menkova, L. I., 214 Ilmsta¨dter, V., 3034, 3035 Ilyatov, K. V., 793 Ilyin, L. A., 1821 Ilyushch, V. I., 1582 Imai, H., 621 Immirzi, A., 2443, 2446, 2447, 2449, 2452 Imoto, S., 382, 389, 509, 524, 1019, 2244, 2245, 2252 Imre, L., 106 Inaba, H., 347, 353, 354, 356 Inada, Y., 412 Infante, I., 1939, 1980 Ingamells, C. O., 632 Inghram, M. G., 1577 Ingletto, G., 546, 547, 553, 554 Ingold, F., 1033 Ingri, J., 3288 Inn, K. G. W., 783, 1364, 3020 Inokuti, M., 2102 Inoue, T., 717, 864, 1270, 2134, 2135, 2147, 2693, 2695, 2696, 2697, 2698, 2699, 2700, 2715, 2716, 2717, 2719, 2721, 2723, 2724 Inoue, Y., 180, 209, 217, 224, 706, 776, 777, 778, 781, 782, 2559, 2578, 2585, 2726, 3287 Inova, G. V., 1524 Insley, H., 84, 86, 87, 88, 89, 90, 424, 459, 460, 461, 462, 463, 464, 465 International Critical Tables, 119 Ioannou, A. G., 596, 1907, 1921, 1922, 1923, 2528, 3102, 3113, 3123 Ionov, S., 2676

Author Index

I-201

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Ionova, G., 117, 213, 221, 1417, 1418, 2126, 2676, 3101, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118 Ionova, G. V., 719, 720, 792, 1300, 1430, 1463, 1516, 1549, 1612, 1683, 1685, 1686, 1706, 1716, 1933 Iorga, E. V., 3111, 3122 Iosilevsji, I. L., 2139, 2148 Ioussov, A., 1427 Ippolitova, E. A., 372, 373, 374, 375, 376, 377, 383, 384, 385, 393 Irani, R. R., 2652 Irgum, K., 851 Iridi, M., 923, 1522, 1578, 1594, 1789, 2370 Irish, D. E., 580, 582, 2430 Irmler, M., 1465, 1471 Irvine, W. M., 1981 Isaacs, E. D., 2234 Iseki, M., 993, 994, 1018 Ishida, K. J., 225 Ishida, V., 188 Ishida, Y. E., 173 Ishigame, M., 343 Ishii, T., 345, 347, 355, 369 Ishii, Y., 338, 2411 Ishikawa, N., 533, 534 Ishikawa, S., 1898, 1905, 1981 Ishikawa, Y., 1643, 1659, 1669, 1670, 1672, 1673, 1675, 1723, 1724, 1726, 1729, 1730, 1731 Ishimori, T., 1509, 1554, 1584, 2672 Ismail, N., 1918, 1919, 1921, 1931, 1972, 1973, 1974 Isnard, O., 65, 66, 69, 71, 72 Iso, S., 856, 2680, 2681, 2682, 2683, 2684 Isobe, H., 273, 3046, 3171 Isom, G. M., 864, 989 Issa, Y. M., 3035 Itagaki, H., 769, 2553, 3022 Itaki, T., 352 Itie´, J. P., 1411, 1458, 1459, 1462, 2407 Itı´e´, J. P., 1300 Itkis, M. G., 14, 1654, 1719, 1720, 1735, 1736, 1738 Itkis, M. G. K., 1654, 1736 Ito, T., 631 Ito, Y., 2211, 2691 Itoh, A., 1018, 1421, 2723, 2724, 2725 Ivanenko, Z. I., 2037, 2051, 2052 Ivanov, K. E., 3051 Ivanov, O. I., 1484 Ivanov, O. V., 14, 1654, 1719 Ivanov, R. B., 26 Ivanov, S. B., 539, 541, 542 Ivanov, V. B., 2693, 2704 Ivanov, V. E., 364 Ivanov, V. K., 357, 1048, 1071, 1074, 1075, 1076, 1077

Ivanov, V. M., 3035 Ivanov, Y. E., 1049 Ivanova, L. A., 179, 185, 198, 199, 200, 230, 1471 Ivanova, O. M., 82, 105, 108, 114, 2439, 2444 Ivanova, S. A., 705, 709, 788 Ivanovich, M., 635, 3016, 3291, 3293, 3294, 3300 Ivanovich, N. A., 1352 Ivanovskii, L., 2695 Iveson, P. B., 1262, 1270, 1285, 2584, 2657, 2659, 2674, 2761 Iwai, T., 717, 2695, 2698, 2715, 2716, 2724 Iwasa, N., 1654, 1719 Iwasaki, M., 460, 461, 462, 463, 467, 533, 534, 1696, 1718, 1735 Iwasawa, Y., 2999 Iwasieczko, W., 338, 339 Iwatschenko-Borho, M., 3022 Iyer, P. N., 195, 1169, 2434 Iyer, R. H., 708, 712, 713, 1282, 1294, 2743, 2745, 2749, 2750, 2757, 2759 Iyer, V. S., 1033 Izatt, R. M., 2449 Izmalkov, A. N., 1422 J. B. Darby, J., 900, 901 Jaakkola, T., 3066 Jablonski, A., 377 Jabot, P., 2712, 2713 Jackson, E. F., 1069 Jackson, J. M., 260, 281, 292 Jackson, K. A., 1904 Jackson, N., 164, 173, 180, 224 Jackson, R. A., 367, 368 Jackson, S. E., 3323 Jacob, C. W., 2385 Jacob, E., 421, 423, 424, 425, 441, 446, 447, 457, 458, 460, 461, 462, 463, 464, 465, 466, 467, 469, 481, 484, 485, 486, 487, 489, 501, 502, 503, 504, 505, 506, 507, 517, 518, 520, 528, 530, 533, 534, 535, 536, 537, 538, 556, 557, 560, 561, 562, 563, 566 Jacob, I., 66, 338 Jacob, T., 1670, 1671, 1672, 1673, 1674, 1675, 1683 Jacobi, E., 187 Jacoboni, C., 92 Jacobs, H., 410, 2633 Jacobs, T. H., 69, 71, 72 Jacobson, A. J., 2153 Jacobson, E. L., 69, 72, 78, 2407 Jacobson, L. O., 3356, 3378, 3395, 3423, 3424 Jacobson, R. A., 78, 83, 84, 2415 Jacoby, R., 108

I-202

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Jacox, M. E., 1968, 1972 Jacquemin, J., 982 Jadhav, A. V., 1174 Jaffe, L., 2114 Jaffe´, R., 2679, 2682, 2684 Ja¨ger, E., 1643, 1662, 1664, 1685, 1687, 1698, 1699, 1700, 1709, 1710, 1713, 1714, 1716, 1718 Jahn, W., 1190 Jain, A. K., 2728 Jain, G. C., 3236 Jain, H. C., 1174 Jainxin, T., 2591 Jaiswal, D. D., 3056, 3057 Jakes, D., 272, 372, 373, 374, 375, 2156 Jakovac, Z., 209 Jakubowski, N., 638, 3325 Jalilehvand, F., 118, 586, 1991, 2531, 2576, 3101, 3102, 3103, 3104, 3105, 3106, 3126, 3127, 3128 Jamerson, J. D., 2819, 2826, 2836 James, A. C., 1823 James, R. A., 1265, 1397, 1418 James, R. W., 2234 James, W. J., 61 Jammet, G., 3061 Jamorski, C., 1910 Jampolskii, V. I., 1681 Jan, S., 3060 Janakova, L., 1507 Janczak, J., 449, 450, 2464 Janecky, D. R., 3133 Janeczek, J., 259, 271, 274, 275 Jangida, B. L., 58 Janiak, C., 1957 Janik, R., 6, 14, 1653, 1713, 1737 Jankunaite, D., 3016 Jannasch, P., 76 Jansen, G., 1906 Jansen, G. J., 2704 Jansen, S. A., 3140, 3150 Janssens, M.-J., 636, 3306 Jarabek, R. J., 3409 Jarboe, D. M., 3250, 3253, 3259 Jardine, C. N., 117, 2863 Jardine, L. J., 988 Jarrell, M. A., 2343, 2344, 2345 Jarry, R. L., 563 Jarvinen, G. D., 849, 863, 913, 1287, 1407, 1408, 2633, 2634, 2676, 2677, 2749, 2761, 3163 Jarvis, K. E., 3324 Jarvis, N. V., 2571, 2577, 2590 Jarzynski, C., 1653 Jaulmes, S., 103, 109, 110, 112, 2432 Jaussaud, C., 211 Javorsky, C. A., 99, 100 Javorsky, P., 968, 2353

Jayadevan, N. C., 1004, 1005, 1007, 1058, 1059, 1060, 1065, 1170, 2407, 2434, 2441, 2442, 2445, 2446 Jayadevan, N. G., 371 Jayasooriya, U. A., 545 Jean, F. M., 2680, 2682, 2683, 2684 Jeandey, C., 719, 720 Jeannin, Y., 2441, 2446 Jeannin, Y. P., 13, 1660 Jee, W. S., 1507, 3349, 3350, 3398, 3399, 3402, 3403, 3405 Jee, W. S. S., 3340, 3343, 3349, 3350, 3353, 3396, 3398, 3399, 3401, 3402, 3403, 3404, 3405, 3407, 3424 Jefferies, N. L., 3050, 3057 Jefferies, T. E., 3047 Jeffery, A. J., 1022, 2115, 2205 Jeffiries, C. D., 2065 Jeffrey, A. J., 2315 Jeffries, C. D., 203, 2241 Jeitschko, W., 66, 67, 69, 70, 71, 72, 73, 100, 399, 405, 2407, 2431 Jelenic, I., 2439, 2444 Jellinek, F., 415, 416, 417, 419 Jelly, J. V., 53 Jemine, X., 737, 2418, 2822, 2912 Jena, S., 1447 Jenkins, H. D. B., 1468 Jenkins, I. L., 178, 181, 1093, 1174, 1175, 1290, 2625 Jenkins, J., 2147, 2208 Jenkins, J. A., 864, 2723 Jenne, E. A., 3165 Jensen, A. S., 1883 Jensen, F., 1903 Jensen, J. H., 1908 Jensen, K. A., 271 Jensen, M. P., 607, 612, 763, 766, 840, 1352, 1354, 1955, 2524, 2558, 2562, 2563, 2570, 2572, 2583, 2584, 2585, 2586, 2589, 2590, 2641, 2649, 2665, 2675, 2691, 2727, 3035, 3138, 3149, 3178 Jensen, W. B., 1897 Jeong, J. H., 2473, 2475, 2826 Jeppesen, C., 630 Jerden, J. L., 297 Jere, G. V., 77 Jerome, S. M., 3302 Jeske, C., 2918 Jeske, G., 2924 Jessop, B. H., 1432 Jetha, A., xvi Jette, E. R., 2386 Jeung, N., 3341, 3343, 3344, 3353, 3358, 3390, 3391, 3396, 3403, 3405, 3406, 3413, 3414, 3415, 3416, 3417, 3418, 3419, 3420, 3421 Jevet, J. C., 2413

Author Index

I-203

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Jezowska-Trzebiatowska, B., 2532, 2533 Jha, M. C., 78, 80, 82 Jha, S. K., 782, 786 Ji, M., 2681 Ji, Y. Q., 715 Jia, G., 3280 Jia, J., 2938, 2998, 2999 Jia, L., 2845, 2846 Jianchen, W., 2753 Jiang, D. L., 3102, 3143, 3145 Jiang, F. S., 133 Jiang, H., 2684 Jiang, J., 589, 2441, 2568, 3142, 3143 Jiang, P. I., 2738 Jiao, R., 785, 1274, 1287, 1288, 1352, 1407, 1412, 2562, 2665, 2676, 2752, 2753, 2762 Jie, L., 2452, 2456 Jie, S., 2912 Jimin, Q., 1267 Jin, J., 1973 Jin, J. N., 108 Jin, K. U., 1692, 1693 Jin, L., 2532 Jin, X., 786 Jin, Z., 108 Jingxin, H., 1141 Jing-Zhi, Z., 2453 Jin-Ming, S., 2453 Joannon, S., 3326 Joao, A., 130, 131 Jochem, O., 398 Jocher, W. G., 395, 396 Joel, J., 955 Joergensen, C. K., 1104, 3171 Johanson, L. I., 1521 Johanson, W. R., 412 Johansson, B., 63, 191, 928, 1044, 1297, 1299, 1300, 1301, 1459, 1460, 1515, 1517, 1527, 1626, 1634, 1639, 2276, 2330, 2353, 2354, 2355, 2359, 2364, 2370, 2371, 2464 Johansson, G., 102, 106, 118, 123, 595, 2531, 2549, 3101, 3103, 3105, 3106 Johansson, H., 2757 Johansson, L., 2564, 3056, 3057 Johansson, M., 1666, 1695, 1702, 1717, 1735 John, K. D., 1958, 2479, 2480 John, W., 859 Johner, H. U., 3042, 3043 Johns, I. B., 329, 332, 336, 989, 991, 1077, 3246 Johnson, B., 2150 Johnson, C. E., 2151 Johnson, D. A., 521, 615, 2539, 2542 Johnson, E., 1524, 1670, 1672, 1673, 1674, 1675, 1676, 1685, 1686, 1691, 1692, 1874 Johnson, E. R., 1821

Johnson, G. D., 2760 Johnson, G. K., 357, 358, 2159, 2165, 2193, 2722, 2723 Johnson, G. L., 77 Johnson, I., 903, 2151, 2711, 2714, 2715 Johnson, J. D., 3150 Johnson, J. S., 123, 770 Johnson, K. A., 901, 906, 907, 908, 911, 912, 915, 936, 958, 959, 1009, 1011, 1012, 1014, 1028, 1302, 2407, 3253, 3254 Johnson, K. D. B., 393 Johnson, K. H., 1916 Johnson, K. R., 109 Johnson, K. W., 957 Johnson, K. W. R., 837, 915, 1077, 1093, 1095, 1100, 1104, 2709, 2713 Johnson, L. A., 3413 Johnson, M. A., 1873 Johnson, O., 75, 107, 329, 332, 336, 421, 509, 3246 Johnson, Q., 80, 201, 329, 1299, 1300, 2419, 2420, 2424 Johnson, Q. C., 914, 1126 Johnson, S. A., 859, 1873, 1874, 1875, 1877 Johnson, S. G., 1874, 1875, 1877, 3047, 3060 Johnson, T. A., 2717 Johnson, T. R., 2712, 2714, 2715, 2719, 2720, 2722, 2723 Johnston, A., 3014 Johnston, D. A., 2226 Johnston, D. C., 67, 71, 96 Johnston, D. R., 471, 476, 482, 496, 2066 Johnston, M. A., 2473 Johnston, M. E., 3387 Johnstone, J. K., 1292 Jolie, J., 3042, 3043 Jollivet, P., 277 Jolly, L., 933 Jonah, C., 1129, 2760 Jonah, C. D., 2760, 3178 Jones, A. D., 1407, 1408, 1549, 2582 Jones, C., 588, 595, 1927, 1928, 2583, 3132 Jones, C. W., 3343, 3396, 3405, 3414, 3415, 3416, 3420 Jones, D. A., 2561 Jones, D. G., 3028 Jones, D. W., 67, 71 Jones, E. R., 749, 2695 Jones, E. R., Jr., 203, 425, 431, 435, 439, 469, 751, 1188, 1472, 1946, 2229, 2230, 2241, 2253, 2256, 2257, 2258, 2259, 2260, 2261, 2262, 2264, 2267, 2268, 2486, 2488, 2851, 2853 Jones, E. S., 3414, 3415, 3416, 3420 Jones, K. W., 3069 Jones, L. H., 350, 380, 502, 519, 529, 530, 1114, 1180, 1312, 1325, 1326, 1361,

I-204

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 1369, 1410, 1430, 1923, 1968, 2165, 2601 Jones, L. L., 1322 Jones, L. V., 30, 32, 487, 962, 1033 Jones, M. E., 1312 Jones, M. J., 3165, 3169 Jones, M. M., 1078, 1287, 2633, 2634, 2676 Jones, P. J., 94, 178, 179, 182, 183, 194, 195, 201, 203, 204, 205, 206, 207, 213, 215, 216, 221, 222, 498, 499, 2418, 2424, 2425, 2434, 2435, 2695 Jones, R. P., 2044, 2047, 2053, 2072, 2073 Jones, W. M., 356, 357, 2272 Jonson, B., 1735 Jonsson, M., 371 Jordan, K. C., 20 Jorga, E. V., 2533 Jørgensen, C. K., 1674, 1733, 1894, 1916, 1932, 2020, 2051, 2052, 2054, 2067, 2080, 2085, 2089 Jorgensen, J. D., 64, 66 Joron, J. L., 231, 3305, 3314 Joseph, R. A., 396 Joshi, A. R., 752, 3052 Joshi, J. K., 1033, 1177, 1178 Joshi-Tope, G. A., 3179 Jost, D., 182, 185, 1447, 1451, 1698, 1699, 1700, 1704, 1705, 1710, 1718, 3030, 3031 Jost, D. T., 1447, 1643, 1662, 1664, 1679, 1684, 1685, 1693, 1694, 1698, 1699, 1705, 1706, 1707, 1708, 1709, 1711, 1712, 1713, 1714, 1716, 1721 Jostons, A., 3265 Joubert, J. C., 113 Joubert, L., 1966, 2177 Joubert, P., 537, 566, 567 Jouniaux, B., 1077, 1079, 1080, 1101, 1529, 1602, 1611, 3312 Jovanovic, B., 2393 Jove`, J., 391, 459, 730, 735, 739, 740, 741, 742, 745, 746, 792, 1105, 1106, 1107, 1312, 1316, 1317, 1359, 2413, 2426, 2427, 2443 Jowsey, J., 3404, 3407, 3410 Joyce, J. J., 921, 964, 1056, 2307, 2343, 2344, 2345, 2347 Joyce, S. A., 1035, 3220 Ju, Y. H., 2691 Judd, B. R., 190, 1847, 1862, 1863, 2015, 2016, 2020, 2023, 2024, 2026, 2027, 2029, 2030, 2035, 2036, 2050, 2054, 2055, 2056, 2075, 2090, 2228, 2241, 2265 Judge, A. I., 379 Judson, B. F., 863 Juenke, E. F., 387, 393, 395 Julian, S. R., 407, 2239, 2359 Jullien, R., 1461

Jung, B., 162, 428, 429, 436, 440, 451 Jung, P., 981, 983 Jung, W., 3397, 3399 Jung, W.-G., 2209 Jung, W.-S., 466, 489, 616 Junk, P. C., 2452 Junker, K., 1447 Junkison, A. R., 1050, 1052 Junsheng, G., 1267 Jurado Vargas, M., 133 Jurgensen, K. A., 1268 Jurriaanse, A., 1449 Jursich, G., 1368, 1454, 1455, 2014, 2016, 2020, 2031, 2037, 2041, 2047, 2054, 2056, 2068, 2071, 2072, 2073, 2075, 2094, 2096 Jursich, G. M., 1454 Jusuf, S., 1918, 1919 Juza, R., 89, 98, 466, 473, 476, 479, 489, 497, 500 Kabachenko, A. P., 164, 1654, 1719, 1720, 1735, 1738 Kabachnik, M. I., 1283, 2738 Kabanova, O. L., 1129, 1130 Kacher, C., 1653 Kacher, C. D., 1445, 1664, 1684, 1693, 1694, 1695, 1696, 1697, 1698, 1699, 1705, 1706, 1716 Kachner, G. C., 972, 973 Kackenmaster, H. P., 490 Kaczorowski, D., 2352 Kadam, R. M., 1175 Kading, H., 163, 172, 174, 178 Kadish, K. M., 2464 Kadkhodan, B. D. M., 185 Kadkhodayan, B., 182, 1445, 1447, 1653, 1664, 1684, 1693, 1694, 1695, 1699, 1704, 1705, 1706, 1716 Kadkhodayan, B. A., 1695, 1696, 1697, 1698, 1699 Kadoya, H., 407 Kadyrzhanov, K. K., 3027, 3033, 3061 Kaffnell, N., 164 Kaffrell, N., 1665 Kahn, A., 103, 110, 113 Kahn, L. R., 1908 Kahn, M., 38, 1104, 1108 Kahn, O., 2256 Kahn, R., 2250 Kahn, S., 180 Kahn-Harari, A., 113 Kai, Y., 2924 Kaifu, N., 1981 Kailas, S., 1447 Kaindl, G., 2237, 2359 Kaji, D., 1450

Author Index

I-205

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Kalashnikov, N. A., 3221 Kalashnikov, V. M., 1145 Kalbusch, J., 2381 Kaldor, U., 33, 1643, 1659, 1669, 1670, 1672, 1673, 1675, 1682, 1723, 1724, 1726, 1729, 1730, 1731 Kaledin, L. A., 1973 Kalevich, E. S., 1422 Kalibabchuk, V. A., 84 Kalina, D. G., 117, 1278, 1280, 1281, 1431, 2240, 2470, 2653, 2655, 2656, 2666, 2667, 2671, 2738, 2739, 2768, 2801 Kalinichenko, B. S., 1512, 3221 Kalinina, S. V., 1302 Kalkowski, G., 2359 Kalpana, G., 63, 100 Kalsi, P. K., 791, 3052, 3053 Kaltsoyannis, N., 203, 204, 289, 577, 578, 602, 1166, 1198, 1200, 1893, 1896, 1898, 1901, 1939, 1943, 1947, 1948, 1949, 1951, 1954, 1955, 1956, 1958, 1962, 1963, 1964, 1967, 2561, 2583, 2888, 3130, 3131, 3152, 3154, 3155, 3160, 3167 Kalvius, G. M., 192, 719, 720, 792, 861, 862, 1297, 1317, 1319, 2283, 2284, 2292, 2361 Kamachev, V. A., 856 Kamagashira, N., 343 Kamara´d, J., 334, 335 Kamaratseva, N. I., 355 Kamashida, M., 1272 Kamat, R. V., 1033 Kameda, O., 343 Kamegashira, N., 364, 2405 Kamenskaya, A. M., 1636 Kamenskaya, A. N., 28, 38, 61, 188, 220, 221, 443, 1547, 1548, 1606, 1607, 1608, 1624, 1629, 1636, 2525, 2526 Kaminski, M., 1295 Kaminski, M. D., 2751, 2752 Kamiyama, T., 407 Kampf, J. W., 2591 Kampmann, G., 3397, 3399, 3400 Kan, M., 2457 Kanamaru, M., 389 Kanamori, H., 1981 Kanatzidis, M. G., 97 Kandan, R., 1076 Kandil, A. T., 184, 3035 Kanehisa, N., 2924 Kaneko, H., 1292 Kaneko, T., 1445, 1450, 1696, 1718, 1735 Kanellakopoulos, B., 102, 108, 117, 208, 382, 421, 423, 445, 448, 727, 729, 730, 751, 763, 766, 767, 769, 792, 1093, 1168, 1190, 1304, 1318, 1319, 1322, 1323, 1324, 1363, 1403, 1411, 1421, 1423,

2017, 2238, 2240, 2241, 2244, 2245, 2249, 2250, 2251, 2253, 2254, 2255, 2257, 2258, 2260, 2261, 2264, 2267, 2268, 2315, 2441, 2469, 2470, 2471, 2472, 2474, 2475, 2476, 2477, 2478, 2479, 2484, 2486, 2488, 2489, 2551, 2553, 2575, 2801, 2803, 2808, 2809, 2814, 2815, 2816, 2817, 2819, 2826, 2827, 2829, 2851, 2852, 2882, 2885, 3037 Kanetsova, G. N., 424 Kani, Y., 855, 856 Kanishcheva, A. S., 2441, 2452 Kannan, R., 2668, 2669 Kannan, S., 2452, 2453, 2455 Kanno, M., 473 Kansalaya, B., 63 Kansi, K., 1272, 1273 Kant, A., 336, 841, 3246 Kao, C. C., 2288 Kapashukov, I. I., 1317 Kaplan, D. I., 3288 Kaplan, G. E., 61, 85, 90 Kaplan, L., 63, 70, 1279, 1280, 1281, 1431, 2653, 2655, 2656, 2666, 2667, 2671, 2738, 2739, 2768 Kapon, M., 2830, 2834, 2835, 2918, 2923, 2935, 2944, 2950, 2965, 2969, 2971, 2984 Kapoor, S. C., 1282, 2745 Kappel, M. J., 1815, 3416, 3420 Kappel, M. S., 3414, 3415, 3416, 3420 Kappelmann, F. A., 1275, 1286, 2651 Kappler, J. P., 2236 Kapshuhof, I. I., 1931 Kapshukov, I. I., 108, 545, 546, 724, 726, 735, 739, 747, 749, 1164, 1312, 1315, 1319, 1466, 2129, 2131, 2427, 2442, 2527, 2595 Kapulnik, Y., 2668 Karabasch, A. G., 63, 80 Karabulut, M., 277 Karalova, Z. I., 709 Karalova, Z. K., 29, 30, 42, 185, 709, 1283, 1408, 1448, 1509, 1512, 1554, 1585, 2668 Karandashev, V. K., 2657 Karaoglou, A., 3424 Karasev, V. I., 1505, 1829 Karasev, V. T., 787 Karaseva, V. A., 1352 Karbowiak, M., 421, 422, 425, 426, 427, 428, 429, 430, 431, 432, 433, 434, 435, 440, 442, 443, 444, 445, 447, 448, 449, 450, 451, 453, 482, 483, 2042, 2062, 2064, 2066, 2103, 2230, 2259, 2260 Karchevski, A. I., 335 Karelin, A. I., 791, 3052

I-206

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Karelin, E. A., 1412, 1413 Karelin, Y. A., 1505, 1654, 1829 Karelin, Ye. A., 14 Karell, E. J., 2723 Karim, D. P., 3100, 3101, 3103, 3118 Karkhana, M. D., 2195 Karkhanavala, M. D., 355, 356, 369 Karle, I., 1092, 1094, 1100, 1101, 2167 Karlstro¨m, G., 596 Karmanova, V. Yu., 787 Karmazin, L., 598, 2452, 2584 Karnland, O., 3152 Karol, P. J., 1653 Karow, H. U., 366 Karpacheva, S. M., 1271, 1352 Karpova, V. M., 3352, 3424 Karraker, D. G., 115, 203, 425, 431, 435, 439, 469, 501, 750, 751, 752, 793, 1182, 1188, 1189, 1323, 1324, 1363, 1472, 1542, 1543, 1946, 2081, 2229, 2230, 2241, 2253, 2257, 2258, 2259, 2261, 2262, 2264, 2267, 2268, 2269, 2271, 2292, 2486, 2488, 2595, 2695, 2801, 2802, 2803, 2809, 2815, 2819, 2828, 2843, 2851, 2853, 2855, 2856 Karstens, H., 63 Kartasheva, N. A., 108, 709 Kasar, U. M., 104, 752, 3052 Kascheyev, N. F., 175 Kaseta, F. W., 2039 Kasha, M., 1144 Kasimov, F. D., 1512 Kasimova, V. A., 1512 Kasper, J. S., 67, 71, 997, 1002 Kaspersen, F. M., 28 Kassierer, E. F., 2664 Kassner, M. E., 892, 894, 1003, 1004, 1009, 1011, 1017 Kast, T., 2683 Kasten, P. R., 2733 Kasting, G. B., 2670 Kasuya, T., 100, 719, 720 Kasztura, L., 1670, 1672, 1692 Kaszuba, J. P., 1341, 3106, 3133 Katakis, D., 606, 609 Katargin, N. V., 1633, 1636 Katayama, Y., 3328 Kately, J. A., 2205 Kathren, R. L., 3282, 3307 Kato, T., 2140, 2147 Kato, Y., 622, 727, 762, 767, 770, 775, 1327, 1368, 1405, 1424, 1430, 1434, 2095, 2096, 2098, 2099, 2426, 2534, 2724, 3045, 3099 Katser, S. B., 2439, 2442 Katsnelson, M. I., 2355 Katsura, M., 338, 410, 2411 Katz, J. H., 3364

Katz, J. J., xv, xvi, 1, 19, 162, 255, 317, 318, 328, 339, 340, 342, 356, 370, 374, 378, 383, 392, 421, 558, 622, 724, 815, 855, 902, 903, 904, 907, 912, 913, 988, 1034, 1077, 1086, 1092, 1094, 1095, 1100, 1101, 1312, 1313, 1321, 1398, 1403, 1417, 1549, 1624, 1628, 1629, 1635, 1660, 1753, 1754, 1901, 1928, 2114, 2160, 2167, 2632, 3206, 3207, 3208, 3212, 3340, 3347, 3348, 3353, 3354 Katz, S., 533 Katzin, L. I., 53, 63, 70, 75, 98, 106, 107, 108, 114, 161, 166, 172, 174, 175, 182, 187, 188, 255, 256, 988, 1915 Kauffmann, O., 109 Kaufman, A., 171, 335, 405 Kaufman, L., 927, 928 Kaufman, M. J., 2148 Kaufman, V., 1843, 1845, 2038, 2080 Kaul, A., 3424 Kaul, F. A. R., 3003 Kautsky, H., 3296 Kavitov, P. N., 1398 Kawada, K., 369, 1266, 1267 Kawade, K., 1484 Kawai, T., 2134, 2135, 2700 Kawamura, F., 762, 855, 856, 1272 Kawamura, H., 789, 790, 3059, 3062, 3068, 3072 Kawamura, K., 93 Kawasaki, O., 382 Kawasuji, I., 40, 1477 Kawata, T., 1282, 1408, 2743 Kay, A. E., 900, 901, 902, 949, 952, 988 Kay, P., 391, 396 Kaya, A., 637 Kayano, H., 338, 339 Kaye, J. H., 714, 1409, 1432, 1434 Kazachevskiy, I. V., 3017, 3067 Kazakevich, M. Z., 220, 221, 1402 Kazakova, G. M., 1448, 1449, 1480 Kazakova, S. S., 1352, 2652 Kazanjian, A. R., 3247 Kazanski, K. S., 1320 Kazantsev, G. N., 1422, 2699, 2700 Keally, T. J., 1800 Kearfott, K. J., 3027 Keding, L., 265 Keenan, K., 520 Keenan, T. K., 87, 90, 457, 458, 1084, 1095, 1097, 1105, 1106, 1107, 1117, 1118, 1120, 1126, 1273, 1291, 1312, 1314, 1319, 1325, 1326, 1328, 1329, 1331, 1357, 1365, 1404, 1410, 1415, 1416, 1417, 1418, 1429, 1430, 1467, 1473, 1474, 2416, 2417, 2418, 2426, 2427, 2583, 2601, 3281 Keeney, D. A., 1695, 1699

Author Index

I-207

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Keeney-Kennicutt, W. L., 3175, 3176 Keiderling, T. A., 337, 2226, 2251, 2404 Keijzers, C. P., 203 Keil, R., 133, 3034, 3035, 3049 Keim, W., 116, 2865 Keimer, B., 2288 Keirim-Markus, I. B., 1821 Keiser, D. D., 719, 721 Keiser, D. L. J., 862, 892 Keitsch, M. R., 2969, 2974 Keller, C., 19, 20, 35, 41, 86, 88, 91, 113, 162, 181, 185, 194, 195, 197, 208, 373, 375, 376, 377, 378, 379, 380, 382, 383, 384, 385, 386, 387, 389, 390, 391, 392, 393, 394, 395, 396, 467, 487, 721, 727, 728, 729, 730, 733, 734, 759, 763, 766, 793, 814, 907, 908, 910, 911, 988, 1056, 1057, 1058, 1059, 1060, 1061, 1064, 1065, 1066, 1067, 1068, 1105, 1106, 1265, 1303, 1304, 1312, 1313, 1314, 1319, 1322, 1323, 1326, 1341, 1352, 1353, 1358, 1398, 1403, 1412, 1413, 1422, 1428, 1431, 1445, 1509, 1513, 1549, 1552, 1553, 2238, 2244, 2261, 2389, 2431, 2432, 2433, 2568, 3214, 3215 Keller, D. L., 1011, 1015, 1018, 1019, 1022, 1045, 1048, 1049 Keller, E. L., 428, 436, 440, 444, 451, 560 Keller, J., 6 Keller, L., 428, 429, 436, 440, 451 Keller, N., 2449, 2450, 2451, 2452, 2458, 2462, 3343, 3351, 3356, 3358 Keller, O. J., Jr., 2561, 2585 Keller, O. L., 1423 Keller, O. L., Jr., 181, 1454, 1592, 1639, 1640, 1659, 1660, 1669, 1670, 1672, 1673, 1674, 1675, 1676, 1682, 1685, 1689, 1691, 1692, 1703, 1723, 1724, 1725, 1727, 1760, 2127 Keller, R. A., 1840, 1845, 1846 Keller, W. H., 61, 78 Kelley, J. M., 3280 Kelley, K. K., 357, 2115 Kelley, T. M., 965, 966, 967 Kelley, W. E., 320 Kelly, C. E., 818 Kelly, D., 1035, 1043, 3210, 3211, 3220 Kelly, D. P., 1033 Kelly, J. M., 3295, 3296, 3311, 3314 Kelly, J. W., 2421 Kelly, M. I., 77 Kelly, P. J., 2276 Kelly, P. R., 269 Kelly, R. E., 1297 Kelly, S. D., 291, 3163, 3164, 3165, 3168, 3179, 3180, 3181, 3182 Kelmy, M., 109

Kember, N. F., 3403 Keming, F., 1267 Kemme, J. E., 862, 897 Kemmerich, M., 900, 901 Kemmler, S., 376, 377 Kemmler-Sack, S., 375, 376, 377, 378, 382, 384, 385, 386, 388, 389, 391, 392, 393, 469, 508, 521, 2425 Kemner, K. M., 291, 3163, 3164, 3165, 3168, 3179, 3180, 3181, 3182 Kemp, T. J., 542, 626, 629, 2439, 2440, 3138 Kemper, C. P., 68, 71 Kempter, C. P., 936, 939, 941, 2407 Kenna, B. T., 1292 Kenneally, J. M., 14, 1654, 1719, 1736, 1738 Kennedy, D. J., 1453, 1516 Kennedy, D. W., 274, 3178, 3179, 3180, 3181 Kennedy, J. H., 634 Kennedy, J. W., 5, 8, 814, 815, 902, 903, 904, 907, 912, 913, 3292, 3299, 3303 Kennel, S. J., 43 Kennelly, W. J., 116, 2476, 2484, 2491, 2843 Kent, R. A., 963, 1008, 1046, 1085, 1116 Keogh, D. D., 2607 Keogh, D. W., 861, 932, 1041, 1043, 1112, 1116, 1117, 1154, 1155, 1156, 1162, 1166, 1925, 1926, 2401, 2427, 2428, 2429, 2450, 2451, 2464, 2465, 2466, 2583, 3109, 3126, 3127, 3128, 3136, 3210 Keogh, W. D., 580, 595, 620, 621 Kepert, C. J., 2571 Kepert, D. L., 494, 586, 588, 1174, 2441 Kerbelov, L. M., 3027 Kerdcharoen, T., 1906 Kerkar, A. S., 2153 Kermanova, N. V., 1127 Kern, D. M. H., 621 Kern, J., 3042, 3043 Kern, S., 457, 486, 2248, 2250, 2278, 2283, 2289, 2290 Kernavanois, N., 2236 Kerrigan, W. J., 1398 Kerrisk, J. F., 957 Kersting, A. B., 3288, 3314 Kertes, A. S., 58, 2625, 2664 Keskar, M., 69, 104, 105, 2434 Keski-Rahkonen, O., 1466, 1515, 1605 Kessie, R. W., 1082 Kester, F., 67 Ketels, J., 1550, 1554 Kettle, P.-R., 1447 Kettle, S. F. A., 201 Kevan, S. D., 2336, 2339 Keys, J. D., 164 Khaekber, S., 3067 Khajekber, S., 3017 Khalifa, S. M., 2662 Khalili, F. I., 2564, 2565, 2566

I-208

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Khalkhin, V. A., 1352 Khalkin, C., 28, 43 Khalkin, V. A., 28, 43, 776 Khalturin, G. V., 769, 1352, 3352, 3424 Khan, A. S., 95 Khan Malek, C., 81, 469, 492, 2248, 2249 Khan, S. A., 2565, 2566 Khanaev, E. I., 458, 1079 Khandekar, R. R., 1170 Kharitonov, A. V., 2657 Kharitonov, O. V., 1291, 1449, 1512 Kharitonov, Y. P., 822 Kharitonov, Y. Y., 763, 765 Kharitonov, Yu. Ya., 108, 109, 575 Khater, A. E., 3014 Khedekar, N. B., 1174 Kheshgi, H. S., 2728 Khizhnyak, P. L., 1408, 1547 Khlebnikov, V. P., 184, 209, 214, 218, 219 Khodadad, P., 414, 415, 2413 Khodakovsky, I. L., 129, 771, 1328, 2114, 2546, 2580 Khodeev, Y. S., 576, 1994 Khodeev, Yu. S., 2179 Khokhlov, A. D., 1302 Khokhrin, V. M., 3025 Khokhryakov, V. F., 1821, 3282 Khopkar, P. K., 1284, 1426, 1427, 1449, 1553, 2579, 2661, 2662, 2759 Khosrawan-Sazedj, F., 264 Khrustova, L. G., 2703, 2704 Khubchandani, P. G., 2431 Kiarshima, A., 2099, 2100 Kiat, J. M., 2250 Kido, H., 77 Kieffer, R., 67 Kiehn, R. M., 862, 897 Kiener, C., 2603 Kierkegaard, P., 1170, 2434 Kihara, S., 706, 708, 753, 758, 790, 791 Kihara, S. A, 1407 Kihara, T., 712, 766, 787 Kikuchi, M., 219 Kikuchi, T., 857, 1019 Kilimann, U., 2469 Kilius, L. R., 3014, 3063, 3317, 3318 Killeen, P. G., 3027 Killion, M. E., 839 Kim, B. I., 1935, 1936 Kim, B.-I., 576 Kim, C., 789, 790 Kim, Ch. K., 3017, 3059, 3062, 3068, 3072 Kim, G., 3282 Kim, J., 2756 Kim, J. B., 181 Kim, J. I., 106, 119, 120, 121, 122, 125, 126, 127, 130, 133, 727, 763, 766, 767, 769, 787, 988, 1114, 1138, 1145, 1146, 1147,

1150, 1154, 1160, 1165, 1166, 1172, 1312, 1314, 1319, 1332, 1338, 1340, 1341, 1352, 1354, 1365, 1366, 1367, 1405, 1406, 1425, 1426, 1427, 1428, 1433, 1782, 1805, 2536, 2546, 2549, 2550, 2551, 2553, 2575, 2591, 2592, 3022, 3024, 3037, 3038, 3043, 3044, 3045, 3057, 3066, 3103, 3104, 3129, 3138, 3149, 3276 Kim, J. K., 1507 Kim, J. L., 3043 Kim, K. C., 367, 1088, 1116, 2161 Kim, W. H., 2602 Kimmel, G., 2407 Kimura, E., 394 Kimura, K., 167 Kimura, M., 1935, 1937 Kimura, S., 1272, 1273 Kimura, T., 699, 706, 708, 715, 716, 727, 767, 770, 775, 783, 1049, 1112, 1294, 1327, 1368, 1405, 1407, 1409, 1424, 1430, 1434, 1512, 2095, 2096, 2097, 2098, 2099, 2100, 2426, 2530, 2534, 2587, 2653, 3043, 3045 Kimura, Y., 407 Kinard, W. F., 1433, 1477, 2580, 2589 Kinard, W. K., 1352 Kincaid, B. M., 3087 Kindler, B., 14, 1653, 1654, 1713, 1717, 1719, 1720, 1738 Kindo, K., 407 King, E., 955, 957, 983 King, E. G., 376 King, E. L., 109 King, G. F., 3117 King, L. A., 2686 King, L. J., 1271, 1275, 1402, 1445, 1448, 1449, 1509, 1510, 1584, 1585, 2636 King, S. J., 790, 3063, 3317, 3318 King, W., 2912, 2924, 2979 King, W. A., 2912, 2934 Kingsley, A. J., 2887 Kingston, H. M., 3281 Kinkead, S. A., 732, 734, 1049, 1082 Kinman, W. S., 265, 295 Kinoshita, K., 717, 1270, 2134, 2135, 2594, 2695, 2696, 2697, 2698, 2700, 2715, 2717, 2719, 2720, 2721 Kinser, H. B., 1509 Kinsley, L. P. J., 3326 Kinsley, S. A., 1943 Kinsman, P. R., 280, 291, 366, 367 Kipatsi, H., 1117, 2546 Kiplinger, J. K., 2850 Kiplinger, J. L., 1958, 2472, 2479, 2480, 2484 Kirbach, U., 1687, 1699, 1700, 1709, 1710, 1718

Author Index

I-209

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Kirbach, U. W., 1447, 1662, 1664, 1666, 1684, 1685, 1695, 1701, 1702, 1711, 1712, 1713, 1714, 1716, 1717, 1735 Kirby, H. W., 18, 19, 20, 23, 25, 26, 27, 28, 32, 33, 35, 38, 40, 41, 42, 43, 161, 162, 163, 166, 167, 170, 172, 174, 178, 179, 180, 182, 187, 195, 213, 215, 226, 230, 2556, 3281, 3347, 3354 Kirchner, H. P., 2432 Kirchner, J. A., 319 Kirin, I. S., 1323 Kiriyama, T., 58 Kirk, B. L., 1507 Kirk, P. L., 988, 1079 Kirkpatrick, J. R., 3239 Kirschbaum, B. B., 3380 Kirslis, S. S., 521 Kiselev, G. V., 1398 Kishi, T., 2743 Kisieleski, W., 3353, 3356, 3362, 3366, 3370, 3378, 3386, 3395, 3407, 3423, 3424 Kisliuk, P., 2067 Kiss, Z., 2077, 2078 Kissane, R. J., 732, 734 Kist, A. A., 1507 Kitamura, A., 120, 121, 2575 Kitano, Y., 3160 Kitatsuji, Y., 706, 708, 753, 790, 791, 1407 Kitazawa, H., 719, 720 Kitazawa, T., 727 Kittel, C., 948, 2308 Kitten, J., 3095, 3175, 3177 Kiukkola, K., 353, 360, 362 Kiyoura, R., 353, 360 Kiziyarov, G. P., 259 Kjaerheim, G., 352 Kjarmo, H. E., 962 Kjarsgaard, B. A., 3027 Kjems, J. K., 357, 2351 Klaasse, J. C. P., 2407 Klaehne, E., 1191 Klaft, I., 1880 Kla¨hne, E., 2472, 2475, 2817 Klapo¨tke, T. M., 117, 118 Klaproth, M. H., 253, 254 Klaus, M., 716 Klauss, H. H., 2284 Klein-Haneveld, A. J., 415, 416, 417, 419 Kleinschmidt, J., 3341, 3342, 3348, 3353, 3356, 3386 Kleinschmidt, P. D., 34, 192, 195, 731, 734, 1077, 1080, 1411, 1459, 1523, 1527, 1562, 1592, 1593, 2115, 2116, 2117, 2120, 2122, 2123, 2148, 2164, 2208, 2209, 2210 Kleinschmidt, R., 3341, 3342, 3348, 3353, 3356, 3386 Klemic, G. A., 3027

Klemm, J., 164 Klemperer, W., 2148 Klenze, R., 223, 730, 763, 766, 787, 1352, 1354, 1405, 1406, 1425, 1426, 1427, 1428, 1433, 2249, 2251, 2260, 2261, 2536, 2591, 3037, 3038, 3043, 3044, 3045, 3057 Kleppa, O. J., 2209 Klett, A., 3029 Kleykamp, H., 393, 740, 1019 Klı´ma, J., 372, 373, 374 Klimov, S. I., 1636 Kline, R. J., 1120, 1123, 1126, 1134, 1145 Klinkenberg, P. F. A., 60, 1842, 1843 Klobukowski, M., 1908 Klopp, P., 1876 Kluge, E., 180 Kluge, H., 1296 Kluge, H.-J., 789, 1403, 1735, 1875, 1876, 1877, 3044, 3047, 3048, 3320, 3321 Kluttz, R., 2488 Kluttz, R. Z., 2852 Klyuchnikov, V. M., 108 Kmetko, E. A., 921, 922, 926, 960, 962, 1300, 1789, 2312, 2384 Knacke, O., 80, 81, 83, 100, 2160 Knapp, F. F., 1507 Knapp, G. S., 3100, 3101, 3103, 3118 Knapp, J. A., 64 Knappe, P., 1906 Knauer, J. B., 1401, 1448, 1449, 1450, 1479, 1505, 1509, 1510, 1584, 1585, 1828 Knauer, J. B., Jr., 1445, 1449 Knauss, K. G., 3129 Knebel, G., 2352 Knecht, H., 410, 435, 452 Knetsch, E. A., 2351 Knie, K., 3016, 3063 Knief, R. A., 821 Knight, D. A., 3342, 3353 Knight, E. E., 2969 Knight, P. D., 2984 Knighton, J. B., 864, 869, 875, 908, 1513, 2711 Knobeloch, D., 225 Knobeloch, G. W., 704, 3312, 3314 Knoch, W., 908 Kno¨chel, A., 2452 Knoesel, F., 2875 Knoghton, J. B., 1297 Knopp, R., 120, 125, 126, 1150, 2588, 3045, 3179 Kno¨sel, F., 2472 Knott, H. W., 1022 Knowles, K. J., 2392 Knudsen, F. P., 377 Knyazeva, N. A., 575 Ko, R., 234 Kobashi, A., 2578, 2726, 3024

I-210

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Kobayashi, F., 1019, 2185, 2186, 2723, 2724, 2725 Kobayashi, K., 703 Kobayashi, S., 2157, 2158 Kobayashi, T., 2464 Kobayashi, Y., 716, 837 Kobus, J., 1454 Koch, C. W., 77 Koch, F., 344 Koch, G., 814, 859, 1070, 1071, 1073, 1110, 1284, 2732 Koch, L., 44, 195, 378, 713, 1056, 1057, 1060, 1061, 1064, 1312, 1313, 2752, 2753, 3062, 3068 Koch, R., 3065 Koch, W., 1903 Koch, W. F., 634 Kochen, R. L., 1292, 2752 Kochergin, S. M., 1352 Kochetkova, N. E., 1283, 2677, 2738 Kock, L., 729, 730 Kockelmann, W., 410 Koczy, F. F., 170 Koeberl, C., 3305 Koehler, S., 789 Koehler, W. C., 342, 1463 Koehly, G., 1049, 1273, 1324, 1329, 1341, 1365, 1366, 2672 Koelling, D. D., 60, 1194, 1461, 1938, 2308, 2334, 2335, 2336, 2338, 2339, 2353 Koenst, J. W., 1292 Kofuji, H., 709, 784, 789, 3327 Kohara, T., 2352 Kohgi, M., 407 Kohl, P. A., 2687, 2691 Kohl, R., 2163, 2422 Ko¨hler, E., 116 Kohler, S., 859, 1296, 1452 Ko¨hler, S., 60, 1403, 1452, 1513, 1588, 1590, 1875, 1877, 3047, 3321 Kohlmann, H., 75, 96, 413, 414, 415, 2413 Kohlschu¨tter, V., 63 Kohn, W., 1671, 1903, 2327 Kohno, N., 784 Koike, T., 1696, 1718, 1735 Koike, Y., 28, 29, 40, 2239 Koiro, O. E., 1283, 2656, 2738 Kojic-Prodic, B., 102, 103, 110 Kojima, Y., 1266, 1267, 1445, 1484 Kojouharova, J., 14, 1653, 1713, 1717 Kokaji, K., 631 Kok-Scheele, A., 2177 Kolar, D., 597 Kolarich, R. T., 209, 214, 215, 217, 218, 2578 Kolarik, V., 1507 Kolarik, Z., 760, 840, 1280, 1287, 2649, 2657, 2674, 2675, 2738, 2756, 2761 Kolarik, Z. J., 707, 713

Kolb, A., 106, 107 Kolb, D., 1671 Kolb, J. R., 1802, 2819 Kolb, R. J., 2817 Kolb, T., 1884 Kolbe, W., 2077, 2261, 2263, 2266, 2272, 2292, 2561 Kolberg, D., 2289, 2290 Kolesnikov, V. P., 1422, 2699, 2700 Kolesov, I. V., 6 Kolesov, V. P., 2114, 2148, 2149, 2185 Kolin, V. V., 1365, 1369, 1404, 1405 Kolitsch, U., 259, 265, 295 Kolitsch, W., 413, 509, 510, 512, 522, 2420 Kolodney, M., 973, 2692 Kolomiets, A. V., 338, 339 Koltunov, G. V., 1143 Koltunov, V. S., 711, 712, 760, 761, 1120, 1126, 1127, 1128, 1129, 1130, 1140, 1141, 1142, 1143, 1175, 2757 Koma, Y., 1281, 1282, 1286, 2743, 2747, 2760, 2761 Komamura, M., 709, 784, 789, 3327 Komarov, S. A., 2177 Komarov, V. E., 2703, 2704 Komatsubara, T., 407, 2239, 2347, 2352 Komissarov, A. V., 1973 Komkov, Y. A., 1059, 1113, 1118, 1133, 1156, 2527, 3124 Komkov, Yu. A., 753 Komura, K., 170, 709, 783, 784, 789, 3327 Komura, S., 2418 Kondo, Y., 1276, 2753, 2755, 2760 Konev, V. N., 900, 902, 904, 906, 907, 908, 910, 911, 912, 913, 914 Konig, E., 730, 763, 766, 2244 Ko¨nig, E., 382 Konig, M., 1735 Konings, R. J. M., 121, 125, 128, 421, 423, 425, 435, 440, 441, 457, 458, 469, 473, 474, 477, 478, 480, 481, 497, 502, 503, 509, 513, 514, 515, 516, 517, 536, 538, 543, 544, 545, 551, 552, 556, 593, 594, 595, 596, 597, 598, 599, 601, 602, 603, 1048, 1076, 1155, 1166, 1171, 1341, 1402, 1411, 1417, 1419, 1941, 2113, 2114, 2115, 2117, 2118, 2120, 2123, 2126, 2127, 2128, 2132, 2133, 2135, 2136, 2137, 2138, 2139, 2140, 2142, 2143, 2144, 2146, 2147, 2148, 2150, 2151, 2152, 2154, 2155, 2156, 2157, 2158, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2169, 2170, 2171, 2173, 2174, 2175, 2176, 2177, 2178, 2180, 2181, 2182, 2186, 2187, 2191, 2192, 2193, 2194, 2195, 2200, 2204, 2205, 2206, 2207, 2209, 2538, 2579, 2582, 3214, 3215, 3347, 3380, 3382

Author Index

I-211

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Koningsberger, D. C., 3087 Konishi, K., 170 Konkina, L. F., 1178, 1352 Ko¨nnecke, Th., 1426 Konobeevsky, S. T., 892, 894, 900, 901, 902, 903, 904, 905, 907, 908, 909, 910, 913, 914, 915 Konoshita, K., 2211 Konovalova, N. A., 221, 1607, 1624, 1629, 1636, 2525 Konrad, T., 66, 67, 71, 399, 2407 Kooi, J., 1109, 1449, 1547, 2696, 2697, 2699 Kopajtic, Z., 3068 Kopf, J., 2472 Ko¨pf, J., 2817 Kopmann, W., 2284 Koppel, I., 101 Koppel, M. J., 1824 Koppenaal, D. W., 3278, 3327, 3328 Koppenol, W. H., 14 Kopytov, V. V., 1326, 1329, 1331, 1416, 1429, 1430, 1448, 1449, 1466, 1479, 1480, 1481, 1512, 1545, 1549, 1559, 2129, 2131, 2584 Korba, V. M., 474 Korbitz, F. W., 68 Korchuganov, B., 1398, 1421 Korchuganov, B. N., 1398, 1433 Koreishi, H., 2560, 2590 Korkisch, J., 1450, 2625 Korman, S., 3413 Kormilitsyn, M. V., 854 Kormilitzin, M. V., 2705, 2706, 2707, 2708 Kornberg, H. A., 3413 Kornetka, Z. W., 2966 Kornilov, A. S., 1337, 1338 Korobkov, I., 117, 1966, 2260, 2871, 2872, 2873, 2874 Korotin, M. A., 929, 953 Korotkin, Y. S., 31, 1664, 1690, 1703 Korotkin, Yu. S., 1425 Korpusov, G. V., 1449 Korshinek, G., 3016, 3063 Korshunov, B. G., 81 Korshunov, I. A., 1422, 2431 Korst, W. L., 64, 2402 Kortright, F. L., 76 Korzhavyi, P. A., 1044 Koseki, S., 1908 Kosenkov, V. M., 2118 Koshti, N., 2633 Koshurnikova, N. A., 1821 Kosiewicz, S. T., 995 Koster, G. F., 1863, 1913, 2028, 2029, 2040 Ko¨stimeier, S., 1943, 1946, 1949 Kostka, A. G., 2527 Kostorz, G. E., 2232 Kosulin, N. S., 939, 941, 1299, 2118

Kosyakov, V. N., 791, 1275, 1312, 1322, 1323, 1326, 1329, 1330, 1331, 1335, 1416, 1429, 1448, 1449, 1476, 1479, 1480, 1481, 1483, 1545, 1549, 1559, 1583, 2126, 2129, 2131, 2584, 2672, 3024 Kosynkin, V. D., 30, 373, 393 Kot, W., 2240, 2261 Kot, W. K., 204, 209, 1188, 1189, 1776, 1954, 1955, 2020, 2065, 2067, 2068, 2083, 2227, 2240, 2251, 2262, 2265, 2269, 2473, 2803, 2855, 2856 Kotani, A., 861 Kotlar, A., 353, 354, 355, 356, 360 Kotliar, G., 923, 964, 2344, 2347, 2355 Kotlin, V. P., 1365, 1369, 1404, 1405 Kottenhahn, G., 395 Kotzian, M., 1943, 1946, 1949 Koulke‘s-Pujo, A. M., 101 Kouzaki, M., 407 Kovacevic, S., 208, 2432 Kovacs, A., 1664, 1684, 1693, 1694, 1706, 1716, 1941, 2164, 2165, 2169, 2170, 2171, 2173, 2174, 2175, 2176, 2177 Kovacs, J., 182, 185, 1447, 1704, 1705 Koval, V. T., 84 Kovalchuk, E. L., 133 Kovalev, I. T., 364, 365 Kovantseva, S. N., 1512 Kovba, L. M., 111, 113, 345, 346, 355, 366, 372, 373, 374, 375, 376, 377, 384, 385, 393, 2434 Kovtun, G. P., 364 Koyama, T., 857, 2719, 2720, 2743, 2761 Kozai, N., 294 Kozak, R. W., 44 Kozelisky, A. E., 714 Kozhina, I. I., 436, 437, 454, 471, 475, 495 Kozimor, S. A., 1956, 1967, 2473, 2476, 2477 Kozina, L. E., 114 Kozlov, A. G., 2507 Kozlowski, J. F., 1968, 1971 Kra¨henbu¨hl, U., 3066, 3067 Krainov, E. V., 1484 Kramer, G. F., 1298 Kramer, G. M., 618 Kramer, K., 813, 814, 825 Kra¨mer, K., 428, 429, 434, 435, 436, 440, 442, 444, 450, 451, 453 Kramer, S. D., 1880, 1882 Kramers, H. A., 2044 Krameyer, Ch., 1882, 1884 Kramida, A. E., 1863 Krasnova, O. G., 2169 Krasnoyarskaya, A. A., 376, 377 Krasser, W., 470 Kratz, J. V., 33, 60, 182, 185, 186, 213, 859, 1447, 1452, 1513, 1588, 1590, 1629, 1635, 1643, 1646, 1647, 1662, 1663,

I-212

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 1665, 1666, 1671, 1679, 1684, 1686, 1687, 1688, 1690, 1695, 1696, 1698, 1699, 1700, 1701, 1702, 1704, 1705, 1707, 1708, 1709, 1710, 1711, 1716, 1717, 1718, 1721, 1735, 1738, 1840, 1875, 1876, 1877, 2575, 3047, 3069, 3321 Kraus, H., 206, 208 Kraus, K. A., 31, 120, 121, 152, 180, 182, 769, 770, 1123, 1147, 1150, 1151, 2548, 2549, 2554, 2580 Krause, M. N., 1605 Krause, M. O., 1466, 1515 Krause, W., 266, 281 Krauss, D., 1695, 1700 Kravchenko, E. A., 82 Krebs, B., 94, 1681 Kreek, S. A., 1445, 1653, 1664, 1684, 1693, 1694, 1695, 1696, 1697, 1698, 1699, 1705, 1706, 1716 Kreiner, H. J., 3022 Kreissl, M., 1828 Krejzler, J., 2580 Kremer, R. K., 89, 94 Kremers, H. E., 18, 37 Kremliakova, N. Y., 1325, 1326, 1327 Kremliakova, N. Yu., 1407, 1408, 1409, 1410 Kreslov, V. V., 3352, 3424 Kressin, I. K., 86, 88, 91, 632, 635, 3292 Krestov, G. A., 1452, 1481, 1482, 2114 Kreuger, C. L., 1270 Krikorian, N. H., 67, 68, 71, 2407, 2408 Krikorian, O., 2157, 2159, 2195 Krikorian, O. H., 1009, 1011, 1036, 1047 Krill, G., 2236 Krimmel, A., 2352 Krinitsyn, A. P., 788, 3034, 3039 Krisch, M., 964, 965, 2342 Krishna, R., 1902 Krishnan, K., 1169, 1170, 2434 Krishnan, S., 963 Krishnasamy, V., 2633 Krivokhatskii, A. S., 1352, 1513 Krivovichev, S. V., 103, 113, 260, 266, 268, 285, 287, 288, 290, 299, 300, 301, 2430 Krivy´, I., 372, 373, 374, 375 Krizhanskii, L. M., 793 Kroemer, H., 948 Kroenert, U., 3320, 3321 Kroft, A. J., 3039 Krogh, J. W., 1973 Krohn, B. J., 1088 Krohn, C., 2692 Krol, D. M., 372, 375 Krolikiewicz, H., 1507 Kroll, H., 3413 Kroll, N. M., 1906 Kronenberg, A., 1699, 1700, 1710, 1718

Kroner, M., 2865 Kro¨ner, M., 116 Kro¨nert, U., 3044, 3047, 3048, 3320, 3321 Kropf, A. J., 279, 861 Krot, N. N., 726, 728, 729, 745, 746, 747, 748, 749, 750, 753, 763, 764, 767, 768, 770, 771, 773, 793, 1059, 1110, 1113, 1116, 1118, 1127, 1133, 1156, 1175, 1181, 1322, 1323, 1325, 1326, 1327, 1329, 1336, 1338, 1352, 1367, 1368, 1405, 1416, 1429, 1430, 1433, 2434, 2436, 2439, 2442, 2507, 2527, 2531, 2532, 2575, 2583, 2595, 3043, 3111, 3112, 3113, 3122, 3123, 3124 Krsul, J. R., 2717 Krueger, C. L., 717, 2134, 2135, 2695, 2696, 2697, 2698, 2699, 2700, 2715, 2719, 2721 Kruger, E., 3398, 3399 Kruger, O. L., 414, 415, 1004, 1019, 1020, 1021, 1022, 1048, 1050, 1052, 2411, 2413 Kru¨ger, S., 1906, 1918, 1919, 1920, 1925, 1931, 1935, 1937, 1938 Krugich, A. A., 364 Krumpelt, M., 2715 Krupa, C., 203 Krupa, J. C., 81, 95, 203, 204, 209, 221, 469, 482, 491, 763, 765, 1170, 1427, 2016, 2020, 2037, 2065, 2066, 2074, 2096, 2138, 2248, 2250, 2278, 2434, 2676 Krupa, J. P., 422, 443 Krupka, K. M., 287, 3178, 3179 Krupka, M. C., 68, 2407 Kruppa, A. T., 1736 Kruse, F. H., 201, 202, 222, 463, 465, 466, 488, 1095, 1097, 1105, 1106, 1107, 1312, 1315, 1357, 1415, 1416, 1417, 1418, 2417, 2427, 2583 Kru¨ss, G., 80, 95, 96, 101, 104 Kryscio, R. J., 1507 Kryukov, E. B., 2442 Kryukova, A. I., 1422, 2431 Ku, H. C., 67, 71 Ku, T. L., 171, 3129, 3294 Kubaschewski, O., 321, 421, 425, 435, 469, 478, 486, 497, 502, 516, 2114, 2185, 2208 Kubatko, K.-A., 584, 730, 2402 Kube, G., 33, 1882, 1883 Kube, W., 1840, 1877, 1884 Kubiak, R., 2464 Kubica, B., 30, 1687, 1710, 1718 Kubik, P., 1447 Kubo, K., 68 Kubo, V., 2533 Kubota, M., 713, 1276, 1292, 2723, 2753, 2755, 2760

Author Index

I-213

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Kuca, L., 1278, 2653 Ku¨chle, W., 34, 1908, 1918, 1920, 1937, 2148 Ku¨chler, 132 Kuchumova, A. N., 109, 110 Kuczewski, B., 3069 Kudo, A., 3017 Kudo, H., 182, 1450, 1696, 1718, 1735 Kudritskaya, L. N., 121, 125 Kudryashov, V. L., 510, 511 Kudryavtsev, A. N., 727 Kuehn, F., 479 Kugel, R., 1088, 1194, 2080, 2084, 2086 Kugler, E., 1735 Ku¨hl, H., 105 Ku¨hn, F., 89, 93 Kuhs, W. F., 65, 66, 334, 335, 2283 Kuiser, H. B., 2758 Kukasiak, A., 1661 Kuki, T., 99 Kulakov, V. M., 164, 166 Kulazhko, V. G., 3221 Kulda, J., 2280, 2294 Kulikov, E. V., 40 Kulikov, I. A., 1035, 1127, 1140, 1144 Kulkarni, A. V., 3052, 3053 Kulkarni, D. K., 206, 208 Kulkarni, M. J., 2668 Kulkarni, S. G., 2202 Kulkarni, V. H., 115 Kullberg, L., 2565, 2578, 2579, 2582, 2585, 2589 Kullen, B. J., 1081 Kullgren, B., 1819, 1823, 2591, 3343, 3358, 3366, 3369, 3373, 3375, 3379, 3382, 3385, 3388, 3389, 3390, 3391, 3392, 3393, 3394, 3395, 3413, 3416, 3417, 3418, 3419, 3421, 3423 Kulmala, S., 189 Kulyako, Y., 2684 Kulyako, Y. M., 856, 1355, 1512 Kulyako, Yu. M., 1422, 1480, 1481 Kulyukhin, S. A., 38, 61, 220, 221, 1547, 1606, 1607, 1608, 1609, 1624, 1629, 2700 Kumagai, K., 63 Kumagai, M., 845, 2738, 2749 Kumagi, M., 1294, 1295 Kumar, A., 845 Kumar, N., 84, 339, 470, 493, 496, 568, 571, 572, 574 Kumar, P. C., 3061 Kumar, R., 2684 Kumar, S. R., 180 Kumok, V. N., 40, 109 Kung, K. S., 3175 Kunitomi, N., 2418 Kunnaraguru, K., 2669

Kunz, H., 1879, 1880, 1882, 1883, 1884 Kunz, P., 33, 859, 1452, 1876, 1877 Kunz, P. J., 1840, 1877, 1884 Kunze, K. R., 2165 Kunzl, V., 226 Kuo, J. M., 3323 Kuo, Sh. Y., 3065 Kuperman, A. Y., 791 Kuperman, A. Ya., 3049, 3052 Kupfer, M. J., 2652 Kuppers, G., 188 Kupreev, V. N., 1681 Kurata, M., 864, 2147, 2715, 2717, 2719, 2720, 2723 Kurbatov, N. N., 93 Kurihara, L. K., 2451, 2452, 2453 Kurioshita, K., 2738 Kurnakova, A. G., 185 Kuroda, K., 631 Kuroda, P. K., 133, 824, 3276 Kuroda, R., 58 Kurodo, R., 188 Kuroki, Y., 706 Kurosaki, K., 2157, 2158, 2202 Kushakovsky, V. I., 395 Kushto, G. P., 576, 1976, 1988, 1989, 1990 Kusnetsov, V. G., 542 Kusumakumari, M., 1422 Kusumoto, T., 2969 Kuswik- Rabiega, G., 3413 Kutaitsev, V. I., 892, 894, 900, 901, 902, 903, 904, 906, 907, 908, 910, 911, 912, 913, 914, 915 Kutner, V. B., 1653, 1654, 1719 Kutty, K. V. G., 396 Kuvik, V., 3061 Kuwabara, J., 3295, 3296 Kuyckaerts, G., 1352 Kuz’micheva, E. U., 345, 346, 355, 366 Kuzmina, M. A., 176 Kuznetsov, B. N., 2999 Kuznetsov, N. T., 2177 Kuznetsov, R. A., 1829 Kuznetsov, V. G., 539, 541, 542, 552, 575 Kuznetsov, V. I., 1267 Kuznetsov, V. S., 1448 Kuznetsov, V. Yu., 3014 Kuznetsova, N. N., 259 Kuznietz, M., 329, 333, 336, 2200 Kuzovkina, E. V., 1449 Kveseth, N. J., 347, 354, 357, 359 Kwei, G., 967 Kwon, O., 555, 1173 Kwon, Y., 719, 720 Kyffin, T. W., 1048, 1152 Kyi, R.-T., 203 Kyker, G. R., 3362

I-214

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 La Bille, C. W., 3354 La Bonville, P., 1369 La Breque, J. J., 3027 La Chapelle, T. J., 5, 717, 727, 738, 3281, 3287 La Gamma de Bastioni, A. M., 187 La Ginestra, A., 2431 La Manna, G., 1989 La Mar, G. N., 2851 La Mar, L. E., 1291 La Placa, S. J., 337, 2404 La Rosa, J., 3017 La Rosa, J. J., 1293, 3284 La Verne, J. A., 3222 Laakkonen, L. J., 1917 Labeau, M., 113 Labonne-Wall, N., 1354, 2591 LaBonville, P., 1923, 1931 Labozin, V. P., 1848 Labroche, D., 340, 351, 352, 353, 354, 355, 356, 363 Labzowsky, L. N., 1669 Lackner, K. S., 2728 Lacombe, P., 324 Lacquement, J., 2135, 2622, 2699, 2700 Ladd, M. F. C., 1169 Ladygiene, R., 3016 Laerdahl, J. K., 34 Lafferty, J. M., 66 Lafuma, J., 3342, 3356 Lagarde, G., 126, 128 Lagergren, C. R., 3313, 3315 Lagerman, B., 119, 120, 121, 124, 128, 2582, 2593 Lagowski, J. J., 38, 118, 1352, 1686, 2539, 2540, 2541, 2542, 2543 Lagrange, J., 2590 Lagrange, P., 2590 Lahalle, M. P., 763, 765, 2278 Lai, L. T., 42, 43 Laidler, J., 2693, 2712, 2722, 2723 Laidler, J. B., 726, 727, 735, 736, 739, 1312, 1315, 2430, 3250 Laidler, K. J., 2557 Laine, R. M., 2979 Laintz, K. E., 2677, 2678, 2682, 2684, 2689 Lakner, J. F., 331 Lal, D., 3300 Lal, K. B., 2633 Laligant, Y., 87, 90 Lallement, R., 937, 939, 957, 981, 982, 2288, 2289 Lally, A. E., 633, 3278, 3281, 3282, 3294 Lam, D. J., 90, 338, 719, 721, 739, 740, 741, 742, 743, 744, 745, 763, 766, 1020, 1022, 1304, 1312, 1317, 1318, 1319, 1466, 1517, 1787, 2238, 2261, 2262, 2263, 2279, 2283, 2362, 2407, 2411, 2413 Lam, I. L., 1661

Lamar, L. E., 1045 Lamartine, R., 2458, 2463 Lambert, B., 2190, 2191, 2655 Lambert, D., 1874, 1875 Lambert, J. L., 67, 77 Lambert, S. E., 2357 Lambertin, D., 2135, 2699, 2700 Lambertson, W. H., 372 Lamble, G. M., 291, 3131, 3160, 3161, 3164 Lamble, K. J., 3280 Lambregts, M. J., 2717 La¨mmermann, H., 1099, 2262 Lamothe, M., 3016 Lan, T. H., 3359, 3362 Lance, M., 102, 106, 1960, 1962, 2246, 2449, 2450, 2451, 2452, 2458, 2462, 2464, 2465, 2466, 2472, 2473, 2479, 2480, 2484, 2488, 2490, 2491, 2801, 2805, 2806, 2807, 2808, 2812, 2818, 2819, 2820, 2830, 2837, 2841, 2847, 2856, 2857, 2858, 2859, 2861, 2862, 2866, 2869, 2870, 2871, 2872, 2889, 2891, 2892, 2922, 2938 Lancsarics, G., 1432 Land, C. C., 895, 900, 901, 905, 906, 907, 908, 911, 912, 914, 915, 984, 1009, 1011, 1012, 1014, 2407 Landa, E. R., 3172, 3178 Landau, A., 1659, 1670, 1675, 1726, 1729, 1730, 1731 Landau, B. S., 463 Landau, L., 2339 Lander, G. H., 320, 321, 322, 323, 324, 353, 357, 409, 412, 457, 486, 719, 721, 739, 742, 743, 744, 745, 861, 863, 949, 952, 953, 967, 968, 1022, 1023, 1055, 1056, 1112, 1166, 1419, 1784, 1787, 1789, 1790, 1894, 2225, 2233, 2234, 2236, 2237, 2238, 2239, 2248, 2249, 2250, 2262, 2264, 2274, 2275, 2276, 2278, 2279, 2280, 2281, 2282, 2283, 2284, 2285, 2286, 2287, 2289, 2290, 2292, 2293, 2294, 2315, 2352, 2353, 2354, 2355, 2368, 2369, 2371, 2372, 2397, 2407, 2464, 3109, 3210 Landers, J. S., 2686 Landesman, C., 3398, 3399 Landgraf, G. W., 1191, 2817 Landgraf, S., 2979 Landresse, G., 2698 Landrum, J. H., 1398, 1629, 1633, 1636, 1639, 1641, 1692, 1695, 1696, 2525, 2526 Lane, E. S., 2686 Lane, L. J., 1803 Lane, M. R., 185, 186, 815, 1445, 1447, 1582, 1653, 1664, 1684, 1693, 1694, 1695, 1699, 1706, 1711, 1716 Lang, R. G., 1842

Author Index

I-215

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Lang, R. J., 60 Lang, S. M., 377 Lange, R. C., 166 Lange, R. G., 43, 817, 818 Langer, S., 67 Langford, C. H., 609 Langham, W., 3341, 3342, 3348, 3353, 3356, 3386 Langmuir, D., 129, 130, 131, 132, 3159, 3166, 3167 Langridge, S., 2234, 2237, 2352 Lankford, T. K., 43 LANL, 1808 Lanz, H., 3342, 3354, 3423 Lanz, R., 1022 Lanza, G., 576, 1956, 1958 Lanzirotti, A., 291 Lapin, V. G., 1398 Lapitskaya, T. S., 1170, 2434 Lapitskii, A. V., 184, 218, 219 Lappert, M. F., 116, 1776, 1954, 1955, 2240, 2473, 2479, 2480, 2484, 2803, 2804, 2812, 2816, 2829, 2830, 2844, 2845, 2875, 2912, 2980 Laraia, M., 1071 Larina, V. N., 2822 Larionov, A. L., 2052 Larkworthy, L. F., 439, 445, 449, 452, 455, 585, 593 Laroche, A., 2712, 2713 Larroque, J., 719, 720, 997, 998 Larsen, A., 2732 Larsen, R. P., 3345, 3354, 3355, 3371, 3378, 3384 Larsh, A. E., 6, 1641, 1642 Larson, A. C., 86, 92, 457, 502, 503, 519, 528, 901, 903, 906, 909, 910, 911, 912, 914, 938, 1012, 1013, 1058, 1059, 1060, 1062, 2407, 2408, 2420 Larson, D. T., 976, 1028, 1035, 1303, 2147, 2389, 2395, 3208, 3229, 3230 Larson, E. A., 332, 3242 Larson, E. M., 103, 112 Larson, R. G., 166, 172, 174, 182 Larsson, S. E., 1661 Laruelle, P., 1055 Lasarev, Y. A., 6 Lasher, E. P., 3358 Lashley, J., 929, 949, 950 Lashley, J. C., 876, 877, 878, 942, 943, 944, 945, 947, 948, 949, 950, 952, 953, 964, 965, 966, 967, 2315, 2347, 2355 Laskorin, B. N., 705 Lassen, G., 1840, 1877, 1884 Lassen, J., 33, 859, 1452, 1876, 1877 Lassmann, M., 1828 Laszak, I., 2691 Laszlo, D., 3413

Lataillade, F., 904 Lataillade, G., 1819 Latham, A. G., 3294 Latimer, R. M., 6, 1449, 1476, 1477, 1478, 1551, 1585, 1606, 1641, 1642 Latimer, T. W., 1004 Latimer, W. M., 2114, 2192, 2538 Latour, J.-M., 1963, 1965 Latrous, H., 1479, 1605, 3114 Latta, R. E., 352, 353, 365 Lau, K. F., 64 Lau, K. H., 82, 420, 731, 734, 1937, 1938, 2179 Laube, A., 3066 Laubeneau, P., 208 Laubereau, P., 751, 1093, 1190, 1800, 2801, 2803, 2809, 2814, 2815 Laubereau, P. G., 116, 1323, 1324, 1363, 1416, 1423, 1455, 1465, 1471, 1531, 1541, 1544, 2470, 2472, 2489 Laubschat, C., 2359 Laubscher, A. E., 84, 2565 Laud, K. R., 109 Laue, C., 14, 185, 186, 1447, 1699, 1705, 1718 Laue, C. A., 815, 1447, 1582, 1654, 1662, 1684, 1693, 1711, 1712, 1716 Laug, D. V., 2717 Laugier, J., 402 Laugt, M., 110, 2431 Lauher, J. W., 1954 Lauke, H., 2866, 2918 Launay, F., 1845 Launay, J., 193 Launay, S., 103, 109, 110, 112, 2432 Laundy, D., 2238 Laurelle, P., 113 Laurens, W., 164 Laursen, I., 2044 Lauterbach, C., 1918, 1919, 1920, 1931, 1935, 1937, 1938 Lauth, P., 1840, 1877, 1884 Lauth, W., 33, 1879, 1880, 1881, 1882, 1883, 1884 Laval, J. P., 88, 91, 467 Lavallee, C., 1120, 1134, 2602 Lavallee, D. K., 2602 Lavallette, C., 2656 Lavanchy, V. M., 1447, 1662, 1684, 1711, 1712, 1716 Laveissie`re, J., 503 Lavrentev, A. Y., 1654, 1719, 1720, 1735 Lavrinovich, E. A., 709, 1408, 1512, 2668 Lavut, E. G., 346 Law, J., 1282, 2739, 2741 Lawaldt, D., 1312, 1319, 1320, 1321, 2430, 2431 Lawrence, B., 3356, 3378, 3395, 3423, 3424 Lawrence, F. D., 1804 Lawrence, F. O., 824, 3016, 3022, 3276

I-216

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Lawrence, J. J., 186, 187, 2702 Lawrence, J. N. P., 1821 Lawroski, S., 2730 Lawson, A. C., 333, 334, 335, 882, 939, 941, 942, 944, 948, 949, 952, 953, 962, 965, 966, 967, 984, 989, 995, 1419, 2233, 2264, 2293, 2370, 2397 Lawson, A. W., 958 Laxminarayanan, T. S., 1169 Laxson, R. R., 1505, 1829 Lay, K. W., 368 Laycock, D., 539, 734 Lazarev, L. N., 988 Lazarev, Y. A., 1504, 1653, 1707, 1719 Lazarevic, M., 314 Lazkhina, G. S., 176 Le Bail, A., 87, 90 Le Behan, T., 1754 Le Berquier, F., 859 Le Berre, F., 92 Le Bihan, T., 192, 406, 719, 720, 923, 1300, 1522, 1578, 1594, 1787, 1789, 2315, 2355, 2368, 2369, 2370, 2371, 2407, 2408 Le Blanc, J. C., 2133 Le Borgne, T., 2254, 2488, 2856 Le Cloarec, M.-F., 206, 208, 217, 218, 2432, 2433 Le Cloirec, P., 3152, 3154 Le Coustumer, P., 128 Leˆ, D. K., 3413 Le Doux, R. A., 566 Le Du, J. F., 109, 128, 1168, 1688, 1700, 1718, 3101, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118 Le Flem, G., 77, 110, 113 Le Fur, Y., 281 Le Garrec, B., 1873 Le Guen, B., 3413 Le Mare´chal, J.-F., 2472, 2473, 2479, 2801, 2806, 2808, 2819, 2843, 2856, 2857 Le Marois, G., 1286, 2673 Le Marouille, J. Y., 413, 414, 415, 514, 516, 528, 551, 2413, 2414, 2425 Le Naour, C., 181, 211, 1671, 1686, 1688, 1700, 1701, 1705, 1711, 1718 Le Roux, S. D., 2439 Le Vanda, C., 116, 2488, 2852, 2855, 2856 Le Vert, F. E., 1267 Lea, D. W., 3159 Lea, K., 2229, 2241 Leal, J. P., 2821, 2840, 2885, 2912 Leal, L. C., 1507 Leal, P., 2150 Leang, C. F., 164, 166 Leary, H. J., 1968, 1971 Leary, J. A., 357, 862, 863, 864, 870, 904, 905, 913, 914, 963, 1003, 1004, 1007, 1008,

1077, 1093, 1095, 1098, 1100, 1103, 1104, 1108, 1116, 1175, 1270, 2698, 2699, 2706, 2709, 2711, 2712, 2713, 3223, 3253, 3254 Leask, M., 356, 2229, 2241 Leavitt, R. P., 2044, 2045, 2048, 2058 Lebanov, Y. V., 1932 Lebeau, P., 68, 403 Lebech, B., 2237, 2286 Lebedev, A. M., 3051 Lebedev, I. A., 180, 1271, 1283, 1284, 1323, 1325, 1326, 1329, 1330, 1331, 1352, 1355, 1365, 1402, 1405, 1409, 1416, 1422, 1423, 1427, 1428, 1430, 1433, 1434, 1450, 1451, 1479, 1480, 1481, 1483, 1509, 1512, 1513, 1584, 1606, 1633, 1636, 2126, 2651 Lebedev, I. G., 900, 902, 904, 906, 907, 908, 910, 911, 912, 913, 914 Lebedev, L. A., 2127 Lebedev, V. A., 2715 Lebedev, V. M., 1427 Lebedev, V. Y., 1684, 1708, 1709, 1716, 1720 Lebedeva, L. S., 1412, 1413 Leber, A., 61 Leboeuf, R. C., 3358 Lebrun, M., 2756 Lechelle, J., 861 Lechelt, J. A., 2760 Leciejewicz, J., 69, 73, 2439, 2440, 3138 Leciewicz, L., 414 Lecocq-Robert, A., 353, 354 Lecoin, M., 27 Lecomte, M., 1049, 1285 Lecouteux, N., 3061 Ledbetter, H., 942, 943, 944, 945, 946, 948, 949, 964, 2315 Lederer, C. M., 164, 1267, 1398 Lederer, M., 209 Ledergerber, G., 1033 Ledergerber, T., 1883 Lee, A. J., 718 Lee, C., 1903 Lee, D., 1447, 1450, 1582, 1629, 1635, 1643, 1646, 1647, 1652, 2575 Lee, D. M., 182, 185, 186, 815, 1445, 1447, 1635, 1642, 1643, 1645, 1646, 1652, 1653, 1662, 1663, 1664, 1665, 1666, 1684, 1685, 1690, 1693, 1694, 1695, 1696, 1697, 1698, 1699, 1701, 1702, 1703, 1704, 1705, 1706, 1709, 1711, 1712, 1713, 1714, 1716, 1717, 1718, 1735, 1737 Lee, D.-C., 639, 3327 Lee, H., 2849 Lee, H. M., 369 Lee, J., 949

Author Index

I-217

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Lee, J. A., 191, 892, 913, 939, 945, 947, 949, 955, 957, 981, 982, 983, 1022, 1299 Lee, M.-R., 103, 112 Lee Nurmia, M. J., 185 Lee, P. A., 3087, 3100 Lee, R. E., 118, 2530, 2533 Lee, S.-C., 783, 2678, 2684 Lee, Sh. C., 3302 Lee, S.-Y., 3172 Lee, T. J., 1728 Lee, T. Y., 2816 Lee, T.-Y., 2471, 2472 Lee, Y. S., 1671, 1676, 1679, 1680, 1681, 1682, 1723, 1727, 1728, 1729, 1907 Leedev, I. A., 1547 Lefebvre, F., 3002, 3003 Lefe`bvre, J., 123 Lefevre, J., 1285, 2756 Lefort, M., 13, 1660 Lefrancois, L., 2649, 2657 Leger, J. M., 1303, 1535, 2389 Leggett, R. W., 3380, 3404, 3405 Legin, A. V., 3029 Legin, E. K., 750 Legoux, Y., 37, 129, 200, 201, 1077, 1079, 1080, 1101, 1302, 1316, 1416, 1418, 1468, 1529, 1593, 1602, 1611 Legre, J., 1874, 1875 Legros, J.-P., 2441, 2446 Lehmann, M., 3364, 3365, 3376, 3378, 3379 Lehmann, T., 1172, 2430, 2431 Leibowitz, L., 357, 1046, 1076 Leicester, H. M., 19, 20, 52 Leider, H. R., 329 Leigh, H. D., 2389 Leikena, E. V., 539 Leikina, E. V., 726, 763, 766, 770 Leininger, T., 1909, 1918, 1919, 1931, 1932 Leino, M., 6, 14, 1653, 1660, 1713, 1717, 1737, 1738 Leipoldt, J. G., 115 Leitienne, P., 1507 Leitnaker, J. M., 1018, 1019 Leitner, L., 389, 1069 Lejay, P., 2352 Lejeune, R., 31 Lelievre-Berna, E., 2236 Le´manski, R., 421, 444, 448, 1055, 1784, 1785, 2238 Lemberg, V. K., 3352, 3424 Lemire, R., 3206, 3213 Lemire, R. J., 121, 125, 128, 421, 423, 425, 435, 440, 441, 457, 458, 469, 473, 474, 477, 478, 480, 481, 497, 502, 503, 509, 513, 514, 515, 516, 517, 536, 538, 543, 544, 545, 551, 552, 556, 593, 594, 595, 596, 597, 598, 599, 601, 602, 603, 718, 719, 722, 726, 727, 728, 739, 744, 745, 767,

769, 771, 881, 888, 891, 989, 1008, 1019, 1021, 1045, 1047, 1048, 1085, 1086, 1087, 1098, 1100, 1101, 1110, 1111, 1117, 1118, 1131, 1147, 1148, 1149, 1150, 1155, 1157, 1158, 1162, 1166, 1167, 1169, 1170, 1171, 1180, 1181, 1341, 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2132, 2133, 2136, 2137, 2140, 2142, 2144, 2145, 2150, 2151, 2152, 2154, 2155, 2156, 2157, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2169, 2170, 2171, 2173, 2174, 2175, 2181, 2182, 2186, 2187, 2193, 2194, 2195, 2197, 2199, 2200, 2201, 2204, 2205, 2206, 2538, 2576, 2578, 2579, 2582, 2583, 3214, 3215, 3347, 3380, 3382 Lemmertz, P., 1738 Lemons, J. F., 1080, 1081, 1083, 1084, 1086, 1088, 1090, 1091, 1126, 2421, 2426 Lengeler, B., 932, 933 Lenhart, J. J., 3165, 3167 Lennox, A., 3354 Lenz, H. C., Jr., 3424 Leo´n Vintro´, L., 3016, 3023, 3296 Leonard, K. S., 1809 Leonard, R. A., 1281, 1282, 2655, 2738, 2739, 2740 Leong, J., 2473, 2816 Leonidov, V. Y., 373, 376 Leonov, M. R., 2822, 2859 Leppin, M., 3065 Leres, R., 1653 Leroux, Y., 2591, 3419, 3421 Lescop, C., 2480, 2837, 2841 Lesinsky, J., 82 Leslie, B. W., 272, 293 Less, N. L., 3242 Lesser, R., 953, 958, 971, 973, 974 Lester, G. R., 1915 Lesuer, D. R., 1297 Letokhov, V. S., 3319 Leung, A. F., 501, 509, 523, 763, 764, 2081, 2082, 2083, 2089, 2245 Leurs, L., 732, 734 Leutner, H., 376, 377 Leuze, R. E., 256, 841, 1402, 1629, 2672 Levakov, B. I., 1352 Levdik, T. I., 3352, 3424 Leventhal, J. S., 3172 Leverd, P. C., 2457, 2458, 2463, 2472, 2480, 2488, 2807, 2819, 2822, 2837, 2857 Levet, J. C., 2413, 2422, 2424, 2425 Levet, J.-C., 402, 407, 414, 416, 417, 420, 423, 425, 435, 437, 440, 456, 457, 470, 473, 474, 478, 479, 499, 502, 509, 514, 515, 516, 525, 527, 528, 538, 544, 551 Levin, L. I., 2052 Levine, C. A., 704, 822, 823, 3276

I-218

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Levine, I. N., 1911 Levine, S., 2114 Levitin, R. Z., 2359 Levitz, N. M., 1081 Levy, G. C., 2565, 2566 Levy, H. A., 488 Levy, J. H., 435, 439, 453, 455, 474, 478, 498, 515, 530, 536, 560, 2417, 2418, 2420, 2421, 2426 Lewan, M. D., 3137 Lewin, R., 854 Lewis, B. M., 357, 358, 2193 Lewis, H. D., 957 Lewis, J. E., 393 Lewis, J. S., 2728 Lewis, L. A., 3227, 3228, 3232 Lewis, M. A., 861 Lewis, R. H., 226 Lewis, R. S., 824 Lewis, W. B., 382, 529, 530, 2076, 2082, 2241, 2243, 2244, 2246 Leyba, J. D., 1445, 1447, 1662, 1703, 1704, 1705 Lhenaff, R., 3016 Li, B., 3055 Li, J., 405, 578, 1200, 1363, 1893, 1943, 1944, 1945, 1946, 1948, 1949, 1950, 1951, 1960, 1961, 1962, 1969, 1973, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 2246, 2861, 2863 Li, J. Y., 715 Li, K., 791 Li, L., 1671, 1905, 1907, 1960, 2912, 2938 Li, R., 3033 Li, S., 77, 2371 Li, S. T., 2042, 2047, 2053, 2059, 2061 Li, S. X., 2717 Li, S.-C., 80, 81 Li, S.-M. W., 3178, 3179 Li, Y., 259, 282, 287, 762, 2984, 3099 Li, Y.-P., 103, 113, 262, 268, 283, 287, 289, 290 Li, Yu., 3033 Li, Z., 164, 191, 2966, 2974 Lian, J., 113, 2157, 2159 Liang, B., 405, 1976 Liang, B. Y., 1977, 1978, 1980, 1981, 1983, 1984 Liang, J., 2752, 2753 Liansheng, W., 1280, 2738 Liberge, R., 2633 Liberman, D., 1728, 2076 Liberman, S., 1874, 1875 Libotte, H., 1300, 1522, 2370 Libowitz, G. G., 328, 329, 330, 331, 332, 2188 Lichte, F. E., 269, 277 Lidster, P., 94, 208, 471, 472, 498, 2065, 2276 Lidstro¨m, E., 2285, 2286, 2287, 2352

Liebman, J. F., 1578, 1611 Lieke, W., 2333 Lien, H., 3026, 3028, 3031, 3032, 3066 Lierse, C., 727, 769, 1145, 1146, 3016, 3063 Lieser, K. H., 133, 180, 788, 3034, 3035, 3095 Liezers, M., 638, 787, 3043, 3044, 3328 Light, M. E., 259, 287 Lightfoot, H. D., 2728 Ligot, M., 2695, 2696 Lijima, K., 1681 Lijun, S., 1267 Likhner, D., 3366 Liley, P. E., 322 Lilijenzin, J. O., 1117 Liljenzin, G., 184 Liljenzin, J., 2525, 2546, 2547, 2592, 2767 Liljenzin, J.-O., 209, 218, 220, 1285, 1286, 1687, 1761, 1764, 1803, 1811, 2584, 2627, 2657, 2659, 2672, 2674, 2675, 2756, 2757, 2761, 2767 Lilley, E. M., 1297, 1299 Lilley, P. E., 3117 Lilliendahl, W. C., 2712 Lilly, P. E., 1593 Lim, C., 3113 Lim, I., 1724, 1729 Lima, F. W., 182 Liminga, R., 103, 110, 1360 Lin Chao, 231 Lin, G. D., 76 Lin, J. C., 3056 Lin, K. C., 1968, 1985, 2894 Lin, L., 2924 Lin, M. R., 1181, 2452, 2453, 2454, 2455 Lin, S. T., 335 Lin, Y., 2678, 2680, 2681, 2682, 2683, 2684, 2689, 2924 Lin, Z., 795, 1364, 2479, 2480, 2913, 2924, 2997 Lin, Z. R., 2837 Linauskas, S. H., 3050 Lincoln, S. F., 607, 620, 1174 Lindau, I., 1521 Lindaum, A., 2370 Lindbaum, A., 192, 923, 1300, 1522, 1578, 1594, 1754, 1787, 1789, 2315, 2355, 2368, 2369, 2370, 2371 Lindberg, M. J., 287 Lindecker, C., 103, 109, 110, 2432 Lindemer, T. B., 361, 389, 396, 1047, 2141, 2143, 2145, 2151 Lindenbaum, A., 1823 Lindenmeier, C. W., 3278, 3327, 3328 Lindgerg, A., 189 Lindgren, I., 1461 Lindh, R., 1909 Lindhorst, P. S., 3409 Lindner, M., 3014

Author Index

I-219

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Lindner, R., 905, 906, 907, 911, 988, 1790 Lindquist-Reis, P., 118 Lindqvist-Reis, P., 3158 Lindsay, J. D., 191, 193 Lindsay, J. D. G., 2350 Lindsay, J. W., 3219 Lindsey, J. D. G., 1302 Lindstrom, R. E., 2686 Linevsky, 2148 Linford, P. F., 944, 949 Linford, P. F. T., 949, 950 Lingane, J. J., 634 Link, P., 1300 Lipis, L. V., 1099, 1100, 1101, 1102, 1106, 1107, 1108, 2426 Lipkind, H., 65, 75, 78, 80, 81, 83, 95, 100, 107 Lipp, A., 67 Lippard, S. J., 337, 2404 Lippelt, E., 2351 Lipponen, M., 130, 131 Lipschutz, M. E., 638, 3327 Lipsztein, J., 3355, 3366 Lipsztein, J. L., 3345, 3356, 3366, 3371, 3375, 3382 Liptai, R. G., 879, 882, 962, 964 Lis, T., 426, 427, 438, 448, 454 Lischka, H., 1908, 1909 Lisco, H., 3424 Listopadov, A. A., 1049 Listowsky, I., 3364, 3366, 3397, 3399 Litfin, K., 1300, 1522, 2370 Litherland, A. E., 3014, 3063, 3316, 3317, 3318 Litteral, E., 357 Litterst, F. J., 2283, 2284 Litterst, J., 719, 720 Little, K. C., 840 Littleby, A. K., 3050, 3057 Littler, D. J., 823 Littrell, K. C., 840, 2649 Litvina, M. N., 1325, 1331 Litz, L. M., 399, 400, 404 Litzen, U., 1843 Liu, B., 2752 Liu, C., 76, 274, 1910, 3179, 3181 Liu, Ch. Yu., 3065 Liu, D.-S., 2875 Liu, G., 3413 Liu, G. K., 483, 486, 1113, 1368, 1454, 1455, 1544, 1605, 2013, 2014, 2016, 2020, 2030, 2031, 2036, 2037, 2041, 2042, 2044, 2047, 2048, 2049, 2053, 2054, 2056, 2059, 2061, 2062, 2064, 2068, 2069, 2070, 2071, 2072, 2073, 2075, 2089, 2095, 2099, 2101, 2103, 2265 Liu, H., 164, 3323 Liu, H. Q., 2979 Liu Husheng, 186 Liu, J. L., 715

Liu, J. Z., 2865 Liu, M. Z., 108 Liu, Q., 2589, 2664 Liu, T. S., 3300 Liu, W., 1671, 1682, 1683, 1727, 1905, 1910, 1943, 1944, 1947, 1948, 1952 Liu, X., 108, 2980 Liu, Y., 76, 3170 Liu, Y. D., 76 Liu, Y. H., 2464 Liu, Y.-F., 1449, 1450, 1451 Livens, F., 3013 Livens, F. R., 588, 589, 595, 705, 706, 783, 790, 1927, 1928, 2440, 2441, 2442, 2447, 2448, 2583, 3056, 3059, 3063, 3072, 3106, 3132, 3165, 3167, 3169 Livet, J., 2563, 2580, 2657 Livina, M. N., 1331 Livingston, H. D., 3022, 3282, 3295 Livingston, R. R., 3221, 3259 Lizin, A. A., 2431 Llewellyn, P. M., 2243, 2561 Lloyd, E., 3401 Lloyd, J. R., 717 Lloyd, L. T., 964 Lloyd, M. H., 1033, 1151, 1152, 1312, 1313, 1421 Lloyd, R. D., 1507, 1579, 1823, 3340, 3343, 3349, 3350, 3353, 3396, 3401, 3405, 3413, 3414, 3415, 3416, 3420, 3424 Lo, E., 1862, 2029 Lo Sasso, T., 3345, 3371, 3396 Loasby, R. G., 892, 909, 912, 944, 949, 952 Lobanov, M. V., 77 Lobanov, Y. V., 6, 14, 1036, 1653, 1654, 1707, 1719, 1736, 1738 Lobanov, Yu. V., 1398, 1400 Lobikov, E. A., 1848 Locock, A., 3170, 3178 Locock, A. J., 263, 264, 265, 266, 281, 294, 295, 296, 2431, 2432, 2433 Loeb, W. F., 3357, 3358 Loewenschuss, A., 2540, 2541, 2543, 2544 Lofgren, N., 738 Lofgren, N. A., 413 Lofgren, N. L., 95, 96, 1093 Loge, G. W., 3322 Logunov, M. V., 856 Logvis’, A. I., 748 Loh, E., 2020 Lo¨hle, J., 1318 Lohr, H. R., 333, 486, 502, 1312, 1313 Lohr, L. L., Jr., 1916, 1943, 1948 Lohr, W., 3424 Loidl, A., 2352 Loiseleur, H., 2438, 2439 Lokan, K. H., 3302 Lokshin, N. V., 3014

I-220

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Lombard, L., 405 Lommel, B., 1653, 1713, 1717 Long, E. A., 356, 357, 2272 Long, G., 1080, 1086, 2701 Long, J. T., 854 Long, K. A., 366, 367 Longerich, H. P., 3323 Longfield, M. J., 2287, 2292, 2352 Longheed, R. W., 1653 Longstaffe, F. J., 3164 Lonnel, B., 14 Lonzarich, G. G., 407, 2239, 2359 Loong, C.-K., 2042, 2047, 2053, 2059, 2061, 2248, 2250, 2278, 2283, 2289 Loopstra, B. O., 341, 346, 349, 350, 351, 356, 357, 358, 372, 373, 374, 375, 376, 383, 392, 514, 2392, 2394, 2434 Lopez, M., 629 Lord, W. B. H., 904, 908, 913, 988 Lorenz, R., 195, 2407, 2408 Lorenz, V., 2469, 2912 Lorenzelli, R., 367, 391, 392, 742, 743, 744, 774, 1008, 1044, 1045, 2407 Loriers, J., 96, 1303, 1535, 2389 Loser, R. W., 3259 Losev, V. Yu., 2441 Lott, U., 396 Lotts, A. L., 2733 Louer, D., 102, 103, 109, 110, 472, 477, 1172, 2431, 2432 Louer, M., 102, 110, 472, 477, 1172, 2431, 2432 Lougheed, R., 1453, 1473, 1474 Lougheed, R. M., 1849 Lougheed, R. W., 6, 14, 1398, 1453, 1474, 1475, 1476, 1516, 1530, 1533, 1543, 1586, 1629, 1631, 1633, 1635, 1636, 1639, 1641, 1647, 1654, 1692, 1695, 1696, 1707, 1719, 1736, 1738, 1839, 1850, 1858, 1864, 1871, 1872, 1885, 2077, 2416, 2525, 2526 Louie, J., 955 Louie, S. G., 2336 Louis, M., 422 Louis, R. A., 82 Loukah, M., 76 Loussouarn, A., 43 Louwrier, K. P., 988, 1033 Love, L. O., 821 Love, S. F., 3024, 3284, 3296, 3307 Loveland, W., 1653, 1737, 1738 Loveland, W. D., 815, 1108, 1499, 1501, 1577, 1580, 1586, 1613, 2630 Lovell, K. V., 854 Lovesey, S. W., 2234 Lovett, M. B., 2527, 2553, 3021, 3022, 3023, 3287, 3295 Lovley, D. R., 3172, 3178 Lowe, J. T., 1290, 1291

Loye, O., 113 Lu, B., 3055 Lu, C. C., 1452, 1640 Lu, F., 3046, 3069 Lu, F. L., 3179 Lu, H., 3062 Lu, M. T., 2633, 2634 Lu, N., 1155 Lu, W. C., 367 Lubedev, V. Y., 1684 Luc, P., 1846, 1882 Lucas, C., 3037 Lucas, F., 103, 112 Lucas, J., 372, 374, 376, 377, 378, 380, 382, 393, 425, 446, 468, 575, 2422 Lucas, R. L., 990, 991, 992, 994, 1028, 1035, 2404, 3204, 3205, 3206, 3207, 3208, 3210, 3212, 3213, 3219 Lucchini, J. F., 289 Luce, A., 2633 Luck, W. A. P., 3117 Luckey, T. D., 3359, 3362 Ludwig, R., 1352 Lue, C. J., 1973 Luengo, C. A., 63 Luger, P., 2452 Lugli, G., 1802, 2420, 2471, 2472, 2490, 2491, 2493, 2819, 2859, 2865 Lugovskaya, E. S., 112 Lui, Z.-K., 928 Lujanas, V., 3016 Lujaniene, G., 3016 Luk, C. K., 3364 Lukashenko, S. N., 3017, 3067 Lukaszewicz, K., 2411 Luke, H., 1534 Luke, W. D., 2487, 2488, 2489, 2852, 2855, 2856 Lukens, H. R., 3305 Lukens, W. W., 289, 602, 1166, 2256, 2259, 2583, 3130, 3131, 3160, 3167 Lukens, W. W., Jr., 2477, 2480, 2812, 2813, 2829, 2830 Lukinykh, A. N., 2431 Lukoyanov, A. V., 929, 953 Luk’yanenko, N. G., 108 Luk’yanov, A. S., 907, 909, 911, 912 Lukyanova, L. A., 458, 1079 Lumetta, G. J., 1278, 1282, 1294, 1397, 2660, 2737, 2740, 2748 Lumpkin, G. R., 113, 271, 273, 277, 278, 280, 291, 2157, 2159, 3051 Lumpov, A. A., 856 Luna, R. E., 3252, 3253, 3255 Lundgren, G., 102, 103, 104, 112, 586, 2434 Lundqvist, R., 222, 223, 1629, 1633, 2529, 2550 Lundqvist, R. D., 1605 Lundqvist, R. F., 1629, 1633, 1636

Author Index

I-221

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Lundqvist, R. F. D., 2525, 2526 Lung, M., 2734 Lunzer, F., 2979 Luo, C., 1449, 1450, 1451 Luo, H., 100 Luo, K., 266 Luo, S. D., 171 Luo, S. G., 715 Luo, X., 639, 3327 Lupinetti, A. J., 398, 861, 998, 1112, 1166, 3109, 3210 Luttinger, J. M., 2334 Lutzenkirchen, K., 596, 627, 628, 629, 3102, 3119, 3121 Lux, F., 204, 205, 206, 207, 208, 501, 515, 527, 1323, 1324, 2080, 2227, 2243, 2244 Lychev, A. A., 539, 549, 555, 556, 1361 Lyle, S. J., 41, 187, 1352, 1426, 1431 Lynch, R. W., 1292 Lynch, V., 605, 2401, 2464, 2465, 2466 Lynn, J., 967 Lynn, J. E., 1880 Lyon, A., 1653 Lyon, W. G., 376, 382 Lyon, W. L., 863, 1045, 1075, 1270, 2710 Lyon, W. S., 164, 169 Lyons, P. C., 3046 Lytle, F., 3087, 3088, 3162, 3163 Lytle, F. E., 3320 Lytle, F. W., 278 Lyttle, M. H., 2852 Lyubchanskiy, E. R., 3352, 3424 Lyzwa, R., 444 Ma, D., 42, 43 Maas, E. T., Jr., 618 Maata, E. A., 117, 2827, 2832, 2837, 2838, 2841, 2842, 2913, 2924, 2997 Mac Cordick, J., 452 Mac Donald, M. A., 1962 Mac Lachlan, D., 3117 Mac Lean, L. M., 3266 Mac Lellen, J. A., 3278, 3327, 3328 Mac Leod, A. C., 353 Mac Wood, G. E., 440, 441, 477, 480, 499 Macak, P., 620, 622, 623, 1925 Macalik, L., 444 Macaskie, L. E., 297, 717 Macdonald, J. E., 389 Macfarlane, A., 3266 Macfarlane, R. D., 1632 Machiels, A., 725 Machuron-Mandard, X., 1049, 3253, 3254, 3262 Macias, E. S., 3292, 3299, 3303 Mack, B., 3029 Mackey, D. J., 2067

Madariaga, G., 78, 82 Maddock, A. G., 162, 164, 173, 176, 177, 178, 179, 180, 182, 184, 187, 198, 201, 208, 209, 213, 215, 217, 218, 219, 220, 224, 227, 229, 230, 988, 1049 Madic, C., 117, 576, 608, 609, 762, 1049, 1116, 1148, 1155, 1168, 1262, 1270, 1285, 1287, 1356, 1369, 1417, 1418, 2426, 2427, 2532, 2533, 2583, 2584, 2594, 2596, 2603, 2622, 2649, 2657, 2658, 2659, 2672, 2674, 2675, 2676, 2756, 2761, 2762, 2858, 3101, 3102, 3110, 3111, 3112, 3113, 3114, 3115, 3116, 3117, 3118, 3253, 3254, 3262 Madic, S., 1923 Maeda, A., 390, 391, 2201 Maeda, K., 753, 790, 791 Maeda, M., 712, 760, 766, 787 Maeland, A. J., 66, 2188 Maershin, A. A., 854 Magana, J. W., 958, 959, 2195 Magette, M., 735, 739 Maghrawy, H. B., 184 Magill, J., 366, 367 Magini, M., 118, 123, 2531, 3103, 3105 Magirius, S., 1314, 1338, 1340 Maglic, K., 356 Magnusson, L. B., 5, 717, 727, 3281, 3287 Magon, L., 767, 770, 776, 777, 778, 779, 781, 782, 1178, 1180, 1181, 2441, 2550, 2554, 2585, 2586, 2589 Magyar, B., 3068 Mahajan, G. R., 1285, 1352, 2657, 2658 Mahalingham, A., 63 Mahamid, I. A., 861 Mahata, K., 1447 Mahe, P., 103, 110 Mahlum, D. D., 1817, 3386 Mahon, C., 1507, 1518 Mahony, T. D., 1507 Maier, D., 1303, 1312 Maier, H. J., 1882, 1883 Maier, J. L., 1697, 2650, 2672 Maier, R., 2469, 2470, 2472, 2475, 2814, 2819, 2882, 2885 Mailen, J. C., 1049, 1270, 1513, 1548, 2702 Maillard, C., 1143 Maillard, J.-P., 1840 Maillet, C. P., 195 Maino, F., 1318, 1319, 1403, 1411, 1421 Mair, M. A., 633, 3282 Maiti, T. C., 714 Maitlis, P. M., 2966 Majer, V., 1766 Majumdar, D., 1973, 1974 Majumder, S., 1906 Mak, T. C. W., 472, 2869 Makarenkov, V. I., 1321

I-222

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Makarov, E. F., 793 Makarova, T. P., 41, 1352, 1476, 1479, 2557 Makhyoun, M. A., 1959 Makishima, A., 3285 Maksimova, A. M., 1352 Malcic, S. S., 2427 Maldivi, P., 1963, 1965, 1966, 2177 Malek, A., 2916 Malek, C. K., 469, 482, 491, 2065 Maletka, K., 475, 476, 478, 479, 495 Maletta, H., 2352 Malhotra, R. K., 3061 Malik, F. B., 1452, 1640 Malik, S. K., 66, 339 Malikov, D. A., 1422, 1448, 1449, 1479 Malinovsky, M., 2692 Malkemus, D., 31 Malkin, B. Z., 2037, 2051, 2052 Mallett, M. W., 328, 331, 399, 410, 2407 Malli, G. L., 1898 Malm, J. G., 163, 174, 182, 200, 502, 503, 504, 505, 533, 534, 535, 537, 731, 732, 733, 734, 1048, 1049, 1080, 1081, 1082, 1086, 1088, 1090, 1092, 1194, 2080, 2084, 2086, 2161, 2176, 2419, 2420, 2421 Malmbeck, R., 1666, 1735, 2135, 2756 Malmqvist, P., 1897, 1909, 1910, 1972, 1973, 1974, 1975 Malta, O., 483, 486, 491 Malta, O. L., 2039 Maly, J., 37, 1302, 1480, 1547, 1607, 1629, 1635, 1637, 1639, 2129 Malyshev, N. A., 31 Malyshev, O. N., 164, 1654, 1719, 1720, 1735, 1738 Malysheva, L. P., 1513 Mamantov, G., 1547 Manabe, O., 2560, 2590 Manceau, A., 3152, 3153, 3154, 3156, 3157, 3165, 3166, 3167 Manchanda, V. K., 182, 184, 706, 1284, 1285, 1294, 1352, 2657, 2658, 2659, 2736 Mandleberg, C. J., 1077, 1078, 1079, 1080, 1085, 1086, 1099 Mandolini, L., 597 Manes, L., 421, 994, 995, 1019, 1286, 1297, 2283, 2292, 2336 Manescu, I., 859 Manfrinetti, P., 407 Mang, M., 794 Mangaonkar, S. S., 110 Mangini, A., 231, 3046, 3164 Manheimer, W., 2728 Manier, M., 220, 221 Mankins, J. C., 2728 Manley, M. E., 929 Mann, B. E., 2966

Mann, D. K., 3327 Mann, J. B., 1296, 1356, 1516, 1604, 1643, 1670, 1674, 1699, 1728, 1729, 1731, 1732, 1733, 2030, 2032, 2042, 2076, 2091, 2095 Mann, R., 14, 1653, 1713, 1717 Manning, G. S., 2591 Manning, T. J., 2574 Manning, W. M., 5, 902, 903, 904, 907, 912, 913, 988, 1577, 1622, 1754, 2114 Mannix, D., 2237, 2285, 2286, 2287, 2352 Mannove, F., 2767 Manohar, H., 2442 Manohar, S. B., 182, 184 Manriquez, J. H., 2916, 2919, 2924, 2997 Manriquez, J. M., 116, 117, 2479, 2481, 2482, 2809, 2811, 2827, 2832, 2837, 2838, 2839, 2841, 2842, 2913, 2924, 2997 Mansard, B., 1071, 1073, 1074, 1075 Manske, W. J., 76 Manson, S. T., 1453, 1516 Mansouri, I., 457 Mansuetto, M. F., 420 Mansuy, D., 3117 Mantione, K., 3022, 3181 Manuelli, C., 105 Mao, X., 786 Mapara, P. M., 1275 Maple, M. B., 62, 63, 100, 861, 2352, 2357 Maples, C., 26 Maquart, Ch., 3040 Mar, A., 2256 Marabelli, F., 1055 Marakov, E. S., 402 Maraman, W. J., 832, 837, 866, 870, 988, 1048, 1093, 1175, 2706, 2709, 2712, 2713 Marangoni, G., 2443, 2446, 2447 Marasinghe, G. K., 277 Marc¸alo, J., 1971, 1993, 2150, 2883, 2884, 2885, 2912 Marcantonatos, M. D., 627, 629 March, N. H., 1994 Marchenko, V. I., 711, 761, 1126, 1140 Marchidan, D. I., 360, 362 Marciniec, B., 2966 Marckwald, W., 20 Marcon, J. P., 378, 414, 739, 740, 741, 1050, 1051, 1052, 1054, 1070, 1074, 1312, 1316, 2413 Marconi, W., 2490, 2491, 2493, 2859, 2865 Marcu, G., 1352 Marcus, R. B., 333 Marcus, Y., 58, 771, 1284, 1312, 1313, 1315, 1325, 1328, 1329, 1331, 1338, 1365, 1509, 2540, 2541, 2543, 2544, 2580, 2625, 2637, 2666

Author Index

I-223

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Marden, J. W., 61, 80 Mardon, P. G., 718, 719, 892, 904, 905, 909, 913, 1009, 2116 Marei, S. A., 1411, 1418, 2267, 2268 Marezio, M., 1067 Margerum, D. W., 2605 Margherita, S., 123 Margolies, D. S., 920, 933 Margorian, M. N., 3282 Margrave, J. L., 2165 Margraves, J. L., 2864 Marhol, M., 847 Maria, L., 2881 Marian, C. M., 1900 Mariani, R. D., 2717 Marie, S. A., 184 Marin, J. F., 367, 368 Marinenko, G., 634 Marinsky, J. A., 484, 2591 Mark, H., 1452, 1515 Markin, T. L., 353, 360, 362, 364, 389, 391, 392, 396, 1027, 1030, 1031, 1070, 1071, 1123, 1184, 1320, 1322, 2389, 2395 Markos, M., 3179, 3181 Markowicz, A., 3173 Markowski, P. J., 100 Marks, A. P., 2577 Marks, T. J., 116, 117, 576, 750, 1801, 1802, 1894, 1942, 1956, 1957, 1958, 1959, 1993, 2240, 2464, 2467, 2468, 2469, 2470, 2471, 2472, 2473, 2476, 2479, 2480, 2481, 2482, 2484, 2491, 2801, 2809, 2810, 2811, 2815, 2817, 2819, 2821, 2822, 2824, 2827, 2832, 2835, 2837, 2838, 2839, 2840, 2841, 2842, 2843, 2844, 2866, 2892, 2893, 2912, 2913, 2914, 2916, 2918, 2919, 2920, 2924, 2933, 2934, 2938, 2939, 2965, 2972, 2979, 2984, 2986, 2990, 2997, 2998, 2999, 3002, 3003 Marlein, J., 33 Marler, D. O., 470 Marley, N. A., 3288 Maron, L., 580, 596, 1156, 1907, 1909, 1918, 1919, 1921, 1922, 1923, 1925, 1926, 1931, 1932, 1957, 2532, 3102, 3126, 3127 Maroni, V. A., 2096, 2536, 3034, 3037 Marov, I. N., 218, 219 Marples, J. A. C., 39, 191, 193, 230, 353, 725, 892, 909, 913, 915, 939, 981, 982, 1058, 2385, 2411 Marquardt, C., 2591 Marquardt, C. M., 133, 223, 763, 766, 3138, 3149 Marquardt, Ch., 3069 Marquardt, R., 1421

Marquart, R., 747, 749, 1034, 1312, 1319, 1320, 1321, 1359, 2407, 2408, 2427, 2430, 2431 Marques, N., 2821, 2840, 2880, 2881, 2882, 2883, 2884, 2885 Marquet-Ellis, H., 423, 445, 503, 505, 2251, 2855 Marquez, L. N., 287 Marquez, N., 2912 Marrocchelli, A., 2633 Marrot, J., 2254 Marrus, R., 190, 1847 Marschner, C., 2979 Marsden, C., 1918, 1919, 1921, 1922, 1931, 1932, 1933, 1969, 1972, 1973, 1974, 1975, 1988 Marsh, D. L., 1829 Marsh, S. F., 849, 851, 1167, 1926, 3109 Marshall, E. M., 2149 Marshall, J. H., 3401, 3404, 3407 Marshall, R. H., 384, 385, 386, 387, 388 Marsicano, F., 2577 Marteau, M., 726, 753, 773, 2129 Martell, A., 121, 124, 132, 510, 597, 602, 604, 606 Martell, A. E., 771, 1178, 2557, 2558, 2559, 2568, 2571, 2575, 2576, 2577, 2579, 2581, 2582, 2587, 2633, 2634, 3346, 3347, 3353, 3361, 3382 Martella, L. L., 1278, 2653, 2737 Marten, R., 3014 Martens, G., 3117 Martensson, N., 1297 Marthino Simo˜es, J. A., 2924, 2934 Marti, K., 824 Martin, A., 1008 Martin, A. E., 352, 353, 378, 391, 2715 Martin, D. B., 903 Martin, D. G., 1075 Martin- Daguet, V., 2685 Martin, F. S., 424 Martin, G. R., 187 Martin, J. M., 2400 Martin, K. A., 1280, 2738, 2742 Martin, L. J., 3017 Martin, M. Z., 1505 Martin, P., 42, 389, 861, 3014 Martin, R., 1507, 1518, 1879, 1882, 1884 Martin, R. C., 1505, 1828, 1829 Martin, R. L., 580, 589, 596, 620, 621, 1192, 1193, 1194, 1196, 1198, 1199, 1777, 1908, 1916, 1918, 1920, 1921, 1922, 1923, 1924, 1925, 1926, 1927, 1931, 1932, 1935, 1936, 1937, 1938, 1940, 1941, 1965, 2528, 3102, 3111, 3112, 3113, 3121, 3122, 3123, 3126, 3128 Martin Sanchez, A., 133 Martin Sa´nchez, A., 3017, 3022

I-224

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Martin, W. C., 1513, 1633, 1639, 1646 Martinez, B., 939, 941, 942, 962, 965, 966, 967, 984, 3247, 3257, 3259 Martinez, B. T., 2749 Martinez, D. A., 3263 Martinez, H. E., 3031 Martinez, J. L., 2360 Martinez, M. A., 861 Martinez, R., 932 Martinez, R. J., 882, 967, 3247, 3257, 3259 Martinez-Cruz, L. A., 2407, 2408 Martin-Gil, J., 2439 Martinho Simo˜es, J. A., 2912 Martinot, L., 118, 119, 421, 423, 445, 487, 492, 717, 718, 725, 728, 729, 753, 754, 1328, 1424, 1482, 2127, 2133, 2134, 2135, 2694, 2695, 2696, 2697, 2698, 2699, 2700, 2701, 2704 Martin-Rovet, D., 101, 728, 1064 Martinsen, K.-G., 2169 Martinsen, M., 78, 80, 81, 82, 96, 100 Marty, B., 824 Marty, N., 184, 187 Marty, P., 2682, 2685 Martynova, N. S. Z., 516 Martz, J., 975 Martz, J. C., 945, 957, 973, 974, 976, 977, 978, 979, 980, 983, 984, 985, 987, 1035, 3200, 3201, 3218, 3225, 3227, 3228, 3230, 3232, 3233, 3234, 3235, 3236, 3237, 3238, 3245, 3247, 3250, 3251, 3252, 3253, 3254, 3256, 3257, 3258, 3260 Marusin, E. P., 69, 72 Maruyama, T., 1450, 1696, 1718, 1735 Maruyama, Y., 1507 Marvhenko, V. I., 2757 Marvin, H. H., 2030, 2036 Marx, G., 3052 Mary, T. A., 942 Marzano, C., 319, 2712 Marzotto, A., 548, 554 Masaki, N., 377, 387, 389, 409, 2392, 2411 Masaki, N. M., 727, 749, 750, 792, 793, 2280, 3043 Masci, B., 2456, 2457, 2458, 2459, 2460, 2461, 2558 Mashirev, V. P., 989, 996 Mashirov, L. G., 539, 548, 549, 555, 556, 571, 1116, 1361, 2533, 2594, 3111, 3122 Masino, A. P., 2819 Maslen, E. N., 2530 Maslennikov, A., 2553 Maslennikov, A. G., 1480, 1548, 1636, 3052, 3053 Maslov, O. D., 786, 822, 1624, 1632, 1663, 1690 Mason, B., 259, 262, 263, 264, 265, 266, 267, 268, 269, 275

Mason, C., 1138 Mason, D. M., 76 Mason, G. W., 27, 115, 171, 172, 175, 184, 219, 704, 822, 824, 1275, 1278, 1280, 1448, 1490, 1697, 2650, 2653, 2672, 2768, 3016, 3276 Mason, J. T., 78, 80, 82 Mason, M. J., 125, 127, 128, 130, 131, 2587 Mason, N. J., 3136, 3137 Mason, T., 170, 187 Mason, T. E., 399 Mass, E. T., 565 Massalski, T. B., 926, 932, 949, 950 Masschaele, B., 3042, 3043 Masse, R., 1819, 3398, 3399 Masson, J. P., 503, 561 Masson, M., 1285 Massud, S., 3035 Mastal, E. F., 43, 817, 818 Mastauskas, A., 3016 Masters, B. J., 621, 622, 1133, 2580, 2599 Masuda, A., 231 Mateau, M., 773 Matei-Tanasescu, S., 360, 362 Ma´tel, L., 3017 Materlik, G., 2236 Materna, Th., 3042, 3043 Matheis, D. P., 417, 418 Matheson, M. S., 2760 Mathew, K. A., 40, 41 Mathews, C. K., 355 Mathey, F., 2491, 2869, 2870 Mathieson, W. A., 2732 Mathieu, G. G., 3129 Mathieu-Sicaud, A., 123 Mathur, B. K., 540, 566, 2441 Mathur, J. N., 705, 708, 712, 713, 775, 1269, 1274, 1275, 1278, 1280, 1281, 1282, 1294, 1426, 1427, 1449, 1553, 2579, 2622, 2626, 2653, 2661, 2662, 2664, 2666, 2667, 2668, 2669, 2738, 2739, 2743, 2744, 2745, 2747, 2748, 2749, 2750, 2753, 2754, 2757, 2759 Mathur, P. K., 180 Matiasovsky, K., 2692 Matignon, C., 61, 63, 64, 80, 97 Matioli, P. A., 260, 293 Matisons, J. G., 2883 Matkovic, B., 102, 103, 110, 2431 Matlack, G. M., 1592, 1593 Matlock, D. K., 939, 940 Matonic, J. H., 593, 1069, 1112, 1138, 1149, 1166, 1179, 1327, 1328, 1824, 1991, 1992, 2530, 2590 Matsika, S., 577, 627, 763, 764, 1192, 1199, 1897, 1901, 1909, 1928, 1930, 1931, 1932, 2037, 2079, 2561, 2594 Matson, L. K., 415, 2413

Author Index

I-225

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Matsuda, H. T., 2748 Matsuda, T., 2157, 2158, 3067 Matsuda, Y., 2657 Matsui, T., 347, 353, 360, 369, 394, 396, 766, 787, 1019, 1025, 1026, 2202, 2208, 2211, 2715 Matsumura, M., 2693, 2717 Matsunaga, N., 1908 Matsunaga, T., 3023, 3171 Matsuoka, H., 410 Matsuoka, O., 1905 Matsutsin, A. A., 458 Matsuzuru, H., 837 Mattenberger, K., 739, 1023, 1055, 1056, 1318, 2234, 2236, 2362 Mattern, D., 3046 Matthens, W. C. M., 2209 Matthews, C. K., 396 Matthews, J. M., 102, 110 Matthews, J. R., 1071, 1970 Matthews, R., 3065 Matthews, R. B., 1004 Matthias, B. T., 34, 191, 193, 1302, 2350 Mattie, J. F., 3067, 3288 Matton, S., 785, 3352, 3359, 3368, 3377 Mattraw, H. C., 1086, 1088 Matuzenko, M. Y., 727, 770, 793 Matveev, A., 1906, 1918, 1919, 1920, 1931, 1935, 1937, 1938 Matz, W., 1923, 3106, 3107, 3111, 3112, 3122, 3179, 3181 Matzke, H., 1004, 1019, 1044, 1071, 2281, 2282, 3065, 3070 Matzke, H. J., 1537 Matzke, Hj., 367, 368, 3214, 3239, 3251, 3265 Matzner, R. A., 301 Mauchien, P., 1114, 1368, 1405, 1433, 2096, 2536, 3034 Mauel, M. E., 2728 Mauerhofer, E., 1479, 3101, 3102, 3111, 3112, 3113, 3114 Mauermann, H., 2918 Maulden, J. J., 187 Maunder, G., 1947 Maung, R., 2452 Maurette, M., 1805 Maxim, P., 64 Maximov, V., 398 Maxwell, S. C., III, 2660, 2661, 2727 Maxwell, S. L., 1409, 1433, 3282, 3283, 3285, 3286, 3293, 3295, 3296, 3311, 3315 Maxwell, S. L., III, 714, 1508, 1511 May, A. N., 53 May, C. A., 1874, 1875, 1877 May, C. W., 1507 May, I., 711, 712, 760, 761, 2584, 2757 May, S., 782, 786, 3056, 3057 Maya, L., 769, 774, 775, 3035, 3154

Mayankutty, P. C., 58 Mayer, H., 262 Mayer, K., 1143 Mayer, M., 1906 Mayer, P., 588 Mayerle, J. J., 337, 2404 Maynard, C. W., 2734 Maynard, E. A., 3354, 3386 Maynard, R. B., 2472, 2473, 2479, 2484, 2561, 2825, 2826 Maynau, D., 1932, 1969, 1988 Mayne, K., 192 Mays, C. W., 1507, 3343, 3349, 3350, 3396, 3401, 3405, 3414, 3415, 3416, 3420, 3424 Mayton, R., 2691 Mazeina, L., 113, 2157, 2159 Mazer, J. J., 276 Mazoyer, R., 724 Mazumdar, A. S. G., 1127, 1175 Mazumdar, C., 2237 Mazur, Y. F., 1512 Mazurak, M., 431 Mazus, M. D., 69, 72 Mazzanti, M., 598, 1963, 1965, 2452, 2584 Mazzei, A., 1802, 2420, 2819, 2865 Mazzi, F., 269, 278 Mazzi, U., 2585 Mazzocchin, G. A., 2585, 2589 McAlister, D. R., 2649, 2652 McAlister, S. P., 962 McBeth, R. L., 107, 292, 490, 492, 501, 510, 524, 737, 1109, 2081, 2696, 2697, 2699 McBride, J. P., 1033 McCart, B., 2262 McCartney, E. R., 2389 McCaskie, L. E., 1818 McClellan, R. O., 3396 McClure, D. S., 2077, 2078 McClure, S. M., 2864 McCollum, W. A., 70 McColm, I. J., 67, 71 McCormac, J. J., 225, 226 McCoy, J. D., 164 McCreary, W. J., 863 McCubbin, D., 1809 McCue, M. C., 106, 119, 2126, 2132, 2538, 2539 McCulloch, M. T., 3047, 3326 McCullough, L. G., 2877 McDeavitt, S., 863 McDeavitt, S. M., 719, 721 McDermott, M. J., 537, 2426 McDevitt, M. R., 42, 43, 44 McDonald, B. J., 997, 998, 1000, 1001, 1004, 1007, 1008 McDonald, F. E., 2984 McDonald, G. J. F., 3014

I-226

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 McDonald, R., 2880, 2881 McDonald, R. A., 70, 339, 399, 407 McDonald, R. O., 309 McDonough, W. F., 3047 McDougal, J. R., 1049 McDowell, B. L., 1432 McDowell, J. D., 1296 McDowell, J. F., 33 McDowell, R. S., 502, 519, 529, 530, 1935, 1968, 2165 McDowell, W. J., 107, 1271, 1477, 1509, 1549, 1554, 1585, 1606, 1640, 2127, 2561, 2565, 2580, 2585 McDuffee, W. T., 2735 McEachern, R. J., 348 McElfresh, M. W., 2352 McElroy, D. L., 1299 McEwen, D. J., 634 McEwen, K. A., 2360 McFarland, S. S., 1507, 3343, 3349, 3405 McGarvey, B. R., 2251, 2252 McGill, R. M., 484 McGillivray, G. W., 3243, 3244 McGlashan, M. L., 1630 McGlinn, P., 278 McGlynn, S. P., 1915, 2239 McGrath, C. A., 185, 186, 815, 1447, 1582, 1684, 1693, 1699, 1705, 1716, 1718 McGuire, S. C., 1445, 1448, 1509, 1510 McHarris, W., 1582, 1632 McInroy, J. F., 3057 McIsaac, L. D., 1277, 1278, 2653 McIsaak, L. D., 225 McKay, H. A. C., 164, 171, 173, 177, 180, 227, 772, 773, 774, 841, 1123, 1554, 1915, 2732 McKay, K., 705, 706, 783, 3056, 3059, 3072 McKay, L. R., 3396 McKee, S. D., 2749 McKerley, B. J., 865, 866, 867, 868, 870, 873, 874, 875 McKibbon, J. M., 3265 McKinley, J. P., 3156 McKinley, L. C., 1033 McKown, H. S., 3321 McLaughlin, D. E., 2351 McLaughlin, R., 469, 2016, 2064, 2077, 2079, 2265, 2272 McLean, J. A., 3069, 3323 McLeod, C. W., 3323 McLeod, K. C., 634 McMahan, M. A., 1653 McMillan, E., 699, 700, 717 McMillan, E. M., 4, 5 McMillan, J. M., 787 McMillan, J. W., 3043, 3044, 3050, 3060, 3062, 3064 McMillan, P. F., 1054

McMillan, T. S., 521 McNally, J. R., Jr., 857, 858, 860, 1847 McNamara, B. K., 289 McNeese, J. A., 875 McNeese, L. E., 2701, 2702 McNeese, W. D., 862, 988 McNeilly, C. E., 997, 998, 1025, 1030, 1045, 1303, 1312, 2147 McOrist, G. D., 3305 McPheeters, C. C., 2712, 2722, 2723 McQuaid, J. H., 1707 McQueeney, R. J., 929, 945, 947, 948, 949, 950, 952, 953, 965, 966, 967, 2315, 2347, 2355 McTaggart, F. K., 75, 96, 2413 McVay, T. N., 84, 86, 87, 88, 89, 90, 424, 460, 461, 462, 463, 464, 465 McVey, W. H., 1175 McWhan, D. B., 1295, 1297, 2234, 2235, 2239, 2386, 2395 Mcwhan, D. B., 2234 Mcwherter, J. L., 1804 Meaden, G. T., 955, 957 Meadon, G. T., 957 Meary, M. F., 1507 Meas, Y., 3023 Mech, A., 422, 425, 426, 427, 442, 447, 448, 482, 2064, 2066, 2103 Mech, J. F., 5, 27, 171, 184, 704, 822, 824, 1577, 1622, 3016, 3276 Mecklenburg, S. L., 851 Medenbach, O., 262 Medfod’eva, M. P., 1352 Medina, E., 818 Medinsky, M. A., 3360, 3364, 3385 Medved, T. Y., 1283, 2738 Medvedev, V. A., 62, 129, 322, 771, 1328, 2114, 2115, 2117, 2120, 2135, 2136, 2137, 2148, 2149, 2185, 2546, 2580 Medvedovskii, V. I., 1117, 1118, 1128 Meece, D. E., 3160 Meerovici, B., 329, 333, 336 Meerschaut, A., 96, 415 Mefodeva, M. P., 726, 728, 729, 745, 746, 747, 749, 750, 753, 763, 767, 768, 771, 793, 1113, 1118, 1133, 1156, 2442, 2527, 3124 Meggers, W. F., 33, 1842 Meguro, Y., 706, 708, 1407, 2678, 2679, 2680, 2681, 2682, 2683, 2684 Mehlhorn, R. J., 1452, 1453, 1839, 1850, 1885, 2263 Mehner, A., 2352 Mehrbach, A. E., 609, 614 Mehta, K. K., 2736 Meier, M., 3047 Meier, R., 2237 Meijer, A., 2531, 3175 Meijerink, A., 2020

Author Index

I-227

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Meinke, W. W., 164, 182, 184, 187 Meinrath, G., 1312, 1319, 1340, 1341, 1365, 2592 Meisel, D., 2760 Meisel, G., 1873 Meisel, K., 63, 98, 100 Meisel, R. L., 1028, 1029, 1030, 3207 Meisen, U., 100 Meisner, G. P., 67, 71 Meisser, N., 260, 267, 285, 288, 292 Meissner, W., 62 Meites, L., 632 Meitner, L., 3, 4, 20, 163, 164, 169, 172, 255 Melchior, S., 729 Meldner, H., 1661 Meli, M. A., 3030, 3280 Melkaya, R. F., 735, 739, 744, 747, 1315, 2595 Mellor, J. W., 101, 253, 255 Meltzer, R. S., 2101, 2103 Melzer, D., 1190 Melzer, G., 107 Menager, M.-Th., 3064 Menchikova, T. S., 900, 902, 904, 906, 907, 908, 910, 911, 912, 913, 914 Mendel, M., 1666, 1695, 1702, 1717, 1735 Mendeleev, D., 161, 162, 254 Mendelsohn, L. B., 1516 Mendelson, A., 319 Mendelssohn, K., 939, 949, 981, 983 Mendik, M., 1055 Menis, O., 634 Menovsky, A., 2351, 2358, 2359, 2407, 2411 Menshikh, Z. S., 1821 Menshikova, T. S., 892, 894, 900, 901, 902, 903, 904, 907, 908, 910, 913, 915 Mentink, S. A. M., 399 Mentzen, B., 114, 2438, 2439, 2440, 2443 Mentzen, B. F., 2438, 2439 Menzel, E. R., 765 Menzel, H.-G., 3424 Menzer, W., 376, 382, 523 Menzies, C., 367 Me´ot-Reymond, S., 949, 954, 2355 Merbach, A. E., 2603, 3110 Mercing, E., 1352 Merciny, E., 1177, 1178 Merckle, A., 107 Mercurio, D., 509 Mereiter, K., 261, 262, 266, 267, 281, 2426, 2427, 3159, 3163 Merenga, H., 1905 Meresse, Y., 719, 720, 1300, 1522, 2370 Merigou, C., 109, 1172 Merini, J., 1416, 1418 Merinis, J., 200, 201, 1077, 1079, 1080, 1101, 1468, 1529, 1593, 1602, 1611 Merkusheva, S. A., 109 Merli, L., 727, 2136, 2190, 2191

Merlino, S., 268, 298 Mermin, N. D., 2308 Merrifield, R. E., 2330 Merrill, E. T., 2730 Merrill, J. J., 859 Merrill, R. D., 996 Merritt, R. C., 303, 304, 307, 308, 309, 311, 312, 313, 314 Merroun, M., 3179, 3180, 3182 Mertig, I., 63 Mertis, K., 2866 Mertz, C., 292, 3039 Merwerter, J. L., 3016, 3022 Merz, E., 2736 Merz, K. M., 2432 Merz, M. D., 890, 936, 937, 962, 968, 969, 970 Meschede, D., 2333 Mesmer, R. E., 119, 120, 121, 598, 599, 1148, 1149, 1155, 1686, 1687, 1701, 1718, 1778, 2192, 2549, 2550, 2553 Mesmer, R. F., 3158 Metabanzoulou, J.-P., 2532 Metag, V., 1880, 1881, 1884 Metcalf, D. H., 2087, 2088 Metcalf, R. G., 3384 Metin, J., 468 Metivier, H., 1148, 1806, 1813, 1819, 1820, 1822, 1824, 3352, 3364, 3377, 3398, 3399, 3413, 3423, 3424 Metoki, N., 2239 Metropolis, R. B. N., 2027, 2040 Metsentsev, A. N., 14 Metta, D. N., 3016 Metz, M. V., 2938, 2984 Metzger, F. J., 111 Metzger, R. L., 1432 Meunier, G., 268, 385 Meunier-Piret, J., 2489, 2490, 2492, 2802, 2844 Meusemann, H., 332 Mewherter, J. L., 824, 3276 Mewhinney, J. A., 3396 Meyer, D., 2469, 2470, 2814, 2882 Meyer, G., 425, 428, 429, 431, 434, 435, 436, 440, 444, 447, 450, 451, 453, 456, 469, 471, 989, 1315, 1465, 1471 Meyer, J., 3361 Meyer, K., 1432, 1965, 2245, 2888 Meyer, M. K., 862, 892 Meyer, N. J., 119, 120, 121, 123, 124, 2548, 2549 Meyer, R. A., 367 Meyer, R. I., 1640 Meyer, R. J., 63, 80, 104, 108 Meyer, W., 473, 476, 479, 497, 500 Meyers, B., 3265 Meyers, W. D., 1882 Meyerson, G. A., 61 Meyrowitz, R., 292, 363, 367

I-228

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Mezentsev, A. N., 1653, 1654, 1707, 1719, 1736, 1738 Mezhov, E. A., 711, 712, 760, 761, 1143, 2757 M’Halla, J., 3115 Mhatre, B. G., 110 Miard, F., 892 Micera, G., 2440 Michael, K. M., 1282, 2745 Michard, P., 3152, 3154 Michel, D., 113 Michel, G., 1840 Michel, H., 3024 Michel, J., 535 Michel, M. C., 824 Micskei, K., 1166 Middlesworth, L. V., 3405 Miedema, A. R., 66, 927, 2209 Miederer, M., 42, 43 Miejer, A., 3111, 3122, 3165, 3169 Miekeley, N., 132 Miernik, D., 428, 429, 450, 451, 493 Mietelski, J. W., 3017 Mighell, A. D., 459, 460, 461, 463 Miglio, J. J., 1507 Migliori, A., 942, 944, 945, 947, 948, 949, 950, 964, 965, 966, 967, 2315, 2347, 2355 Mignanelli, M. A., 391 Mignano, J., 1507 Miguel, M., 627 Miguirditchian, M., 2562 Miguta, A. K., 280 Mihalios, D., 3003 Mikesell, B. I., 3323, 3326, 3327 Mikhailichenko, A. I., 30 Mikhailov, V. A., 175, 184, 219, 2575 Mikhailov, V. M., 1331, 1416, 1430, 1433 Mikhailov, Yu. N., 539, 541, 542, 552, 575, 2439, 2441, 2442, 2452 Mikhailova, M. A., 26 Mikhailova, N. A., 791, 1126, 3052 Mikhalko, V., 3101, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118 Mikhee, N. B., 1607, 1608, 1609 Mikheev, N. B., 28, 38, 61, 220, 221, 1113, 1117, 1368, 1402, 1403, 1424, 1463, 1473, 1515, 1547, 1548, 1606, 1607, 1608, 1612, 1624, 1629, 1630, 1636, 1776, 2129, 2133, 2525, 2526, 2700 Mikheev, V. L., 1582 Mikheeva, M. N., 788 Mikou, A., 88, 91, 467 Mikulaj, V., 3017 Mikulski, J., 1636, 2526 Milam, S. N., 2464, 2465 Milanov, M., 776, 1352 Milek, A., 1629, 1635 Miles, F. T., 854 Miles, G. L., 184, 187, 219, 230

Miles, J. H., 843 Milic, N. A., 123 Milic, N. B., 2549 Milicic-Tang, A., 95 Millay, M. A., 3046 Miller, C. M., 1874, 1875, 1877, 3322 Miller, D., 367 Miller, D. A., 942, 944, 948 Miller, D. C., 892, 909, 912 Miller, G. G., 2677 Miller, J. F., 64 Miller, J. H., 1829 Miller, J. M., 3292, 3299, 3303 Miller, J. T., 2851 Miller, K. M., 3025, 3027 Miller, L. F., 1505 Miller, M. B., 1582 Miller, M. J., 2852 Miller, M. L., 257, 259, 270, 272, 280, 281, 283 Miller, M. M., 2832 Miller, N. H., 274, 289 Miller, R. A., 224, 225 Miller, R. L., 2868, 2869 Miller, S., 1821 Miller, S. A., 264 Miller, S. C., 3340, 3353, 3402, 3413 Miller, S. L., 1681 Miller, W., 1509 Miller, W. E., 2692, 2693, 2695, 2696, 2698, 2713, 2714, 2715, 2723 Millie´, P., 1921, 1922 Milligan, W. O., 1312, 1313, 1421 Mills, D., 2234 Mills, J. L., 2676 Mills, K. C., 413 Mills, T. R., 1270 Milman, V., 2265, 2293 Milner, G. W. C., 226 Milovanova, A. S., 1337 Milstead, J., 1636 Milton, J. A., 3328 Milyukova, M. S., 1271, 1284, 1325, 1326, 1329, 1331, 1365, 1431, 1448, 1449, 1450, 1479, 1509, 1584, 1606, 2651 Mimura, H., 2762 Minaeva, N. A., 2442 Minakawa, N., 339 Minato, K., 1317, 2724 Mincher, B. J., 708, 709, 856, 1431, 2684, 2738 Mindiola, D. J., 1966, 1967, 2245, 2859, 2861, 2888 Mineev, V., 2352 Mineo, H., 1272, 1273 Miner, F. J., 1104, 1144, 1175, 1176 Miner, W. N., 398, 408, 409, 892, 894, 895, 896, 898, 900, 901, 902, 903, 904, 905, 906, 907, 908, 909, 910, 911, 912, 913,

Author Index

I-229

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 914, 933, 936, 937, 938, 939, 953, 984, 988, 3213, 3238 Ming, W., 2452, 2453, 2456 Minnich, M. G., 3323 Minor, D., 1067 Mintz, E. A., 116, 117, 2470, 2801, 2822, 2824, 2844, 2918, 2919, 2920 Mintz, M. H., 335, 722, 723, 724, 3239 Miquel, Y., 576 Miraglia, S., 65, 66 Miranda, C. F., 198, 225, 227 Mironov, V. S., 1113, 1133, 1156, 1933 Miroslavov, A. E., 856 Mirvaliev, R., 2675 Mirzadeh, S., 31, 43, 1507 Misaelides, P., 302, 3039 Misciatelli, P., 106 Misdolea, C., 367 Mishima, J., 3200, 3252 Mishin, V. Y., 750, 1323 Mishin, V. Ya., 2800 Mishler, L. W., 357 Mishra, R., 2153 Mishra, S., 1283 Misiak, R., 1662, 1687, 1709, 1710, 1718 Misra, B., 2738, 2739 Missana, T., 3069, 3070 Mistry, K. B., 1819 Mistryukov, V. E., 2439 Mitchell, A. J., 1152, 3036 Mitchell, A. W., 740, 741, 742, 743, 1003, 1009, 1020, 1022, 1304, 1312, 1317, 1318, 1319, 2407, 2411, 2413 Mitchell, J. N., 916, 960, 964 Mitchell, J. P., 2924 Mitchell, M. L., 1369, 3035 Mitchell, P. I., 3016, 3017, 3023, 3296 Mitchell, R. H., 113 Mitchell, R. S., 294 Mitius, A., 69, 72, 2408 Mitsch, P., 2392 Mitsubishi Materials Corporation, 179 Mitsugashira, T., 30, 37, 40, 703, 1477 Mitsuji, T., 209, 217, 220, 221, 222 Mittal, R., 942 Miushkacheva, G. S., 3352, 3424 Miyakawa, T., 2095 Miyake, C., 382, 389, 390, 391, 396, 397, 421, 509, 524, 2244, 2245, 2252, 2657 Miyake, K., 412, 2347 Miyake, M., 410 Miyashiro, H., 2693, 2717, 2719, 2720 Mize, J. P., 227 Mizoe, N., 2966 Mizumoto, M., 2723 Moattar, F., 1352 Mochizuki, Y., 1897, 1938, 1992 Mockel, S., 268, 298

Modolo, G., 1288, 1289, 1294, 1295, 2676, 2749, 2756, 2762 Mody, T. D., 605, 2464 Moedritzer, K., 2652 Moeller, R. D., 901 Moeller, T., 18, 37, 1402, 1643 Moens, A., 2381 Moens, L., 638, 3325 Mogck, O., 2655 Mogilevskii, A. N., 1480, 1481 Mohammad, B., 3060 Mohammed, A. K., 132 Mohammed, T. J., 2687 Mohan, M. S., 3024 Mohanly, S. R., 182 Mohapatra, P. K., 706, 1284, 1294, 1352, 2658, 2659 Mohar, M., 1684, 1693, 1706, 1716 Mohar, M. F., 1664, 1684, 1693, 1694, 1695, 1706, 1716 Mohs, T. R., 2591 Moine, B., 81 Moise, C., 2825, 2877, 2889, 2890 Moiseev, S. D., 30 Moissan, H., 61, 63, 67, 68, 78, 80, 81, 82, 95, 96, 100 Moisy, P., 3111 Moisy, Ph., 762 Molander, G. A., 2918, 2924, 2933, 2969, 2974, 2982, 2984 Moline, S. W., 1448, 1490 Molinet, R., 44, 1143, 2752 Molinie, P., 1054 Moll, H., 118, 133, 490, 580, 581, 586, 589, 591, 596, 602, 605, 612, 616, 621, 626, 1113, 1156, 1921, 1922, 1923, 1925, 1926, 1933, 1991, 2531, 2532, 2576, 2582, 2592, 3101, 3102, 3103, 3104, 3105, 3106, 3112, 3120, 3121, 3125, 3126, 3127, 3128, 3129, 3132, 3138, 3140, 3143, 3144, 3149, 3150, 3152, 3154, 3155, 3165, 3166, 3167 Møller, C., 1902 Mo¨ller, P., 1661, 1884 Mollet, H. F., 2263 Molnar, J., 2177 Molochnikova, N. P., 179, 182, 184, 187, 207, 219, 229, 230, 1408, 2667 Molodkin, A. K., 102, 105, 106, 108, 109, 110, 114, 2434, 2439, 2444 Molokanova, L. G., 786 Moloy, K. G., 116, 2479, 2842, 2844 Molzahn, D., 822, 3296 Moment, R. L., 942, 943, 946, 949, 964, 2315 Moncorge, R., 2100 Mondange, H., 113 Mondelaers, W., 3042, 3043 Money, R. K., 30, 34, 35, 2385

I-230

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Mongeot, H., 2655 Moniz, P., 851 Monroy-Guzman, F., 181 Monsecour, M., 20, 27, 31, 38 Montag, T., 1135, 2599 Montag, T. A., 1335 Montagnoli, M., 3170 Montaser, A., 3069, 3323 Montegue, B., 3423 Montenero, A., 103, 110, 546, 547, 553, 554 Montgomery, H., 63, 2315, 2350 Montgomery, J. A., 1908 Montgomery, R., 3055 Monthoux, P., 407, 2239, 2359 Montignie, E., 97, 417 Montoloy, F., 468, 469, 506 Montorsi, M., 393 Montroy Gutman, F., 1688, 1700, 1718 Moodenbaugh, A. R., 62, 96 Moody, C. A., 3285, 3296 Moody, D. C., 452, 2449, 2450, 2452, 2472, 2480, 2801, 2807, 2832, 2891 Moody, E. W., 849 Moody, G. J., 3029 Moody, J., 1654, 1736 Moody, J. C., 1179, 2591, 3354, 3413, 3415, 3416, 3419, 3420, 3421 Moody, J. W., 415, 2413 Moody, K. J., 14, 1450, 1647, 1653, 1654, 1707, 1719, 1736, 1738 Moon, H. C., 121, 123, 124, 125, 126, 127, 2550 Moon, K. A., 595 Mooney, R. C. L., 80, 1028, 2418 Mooney, R. W., 110 Moore, C. E., 1672 Moore, D. A., 127, 128, 131, 1160, 1162, 1179, 2546, 2547, 2549, 3134, 3135, 3136 Moore, D. P., 984, 2347 Moore, F. H., 1174, 1175 Moore, F. L., 182, 184, 185, 187, 225, 226, 1284, 1292, 1409, 1448, 1449, 1509, 2648, 2660 Moore, F. S., 185 Moore, G. E., 180, 357, 1323, 1324, 2580 Moore, J. G., 188, 2735 Moore, J. R., 1542, 1543, 2270, 2271 Moore, K. T., 967 Moore, L. J., 3320 Moore, R. B., 1735 Moore, R. C., 3409 Moore, R. E., 459 Moore, R. H., 1270, 2710 Moore, R. L., 227 Moore, R. M., Jr., 2488, 2856 Moore, R. W., 29 Moorthy, A. R., 3307 Moos, H. W., 2086, 2095, 2096

Morales, L., 1056, 3222 Morales, L. A., 861, 932, 967, 968, 973, 975, 976, 984, 1026, 1027, 1035, 1040, 1041, 1042, 1043, 1112, 1154, 1155, 1166, 1784, 1790, 1798, 2136, 2141, 2239, 2347, 2352, 2353, 2372, 3109, 3177, 3202, 3206, 3208, 3209, 3210, 3211, 3214, 3220, 3221, 3222, 3223, 3224, 3225, 3227, 3229, 3231, 3232, 3235, 3236, 3243, 3244, 3245, 3249, 3250, 3253, 3259 Moran, S. M., 3314 Moravec, J., 372, 373, 374, 375 Moreau, C., 355 Moreau, L., 43 Morel, J. M., 2657, 2658 Moreland, P. E., 3069 Morelli, J. J., 3046 Morello, M., 3023, 3067 Moren, S. B., 231 Moreno, N. O., 406 Moretti, E. S., 1179, 3345, 3354, 3355, 3371, 3378, 3384 Morfeld, P., 274 Morgan, A., 3342, 3353 Morgan, A. N., 870, 871, 1077, 1093, 1095, 1175, 2712, 3031 Morgan, A. N., III, 1185, 1186 Morgan, A. R., 164 Morgan, J., 162, 3306 Morgan, J. R., 879, 883, 890, 891, 920, 933, 936, 962, 970 Morgan, J. W., 636 Morgan, L. G., 2704 Morgan, L. O., 5, 1265 Morgan, W. W., 2736 Morgenstern, A., 223, 1143, 1172, 2550, 3022 Mo¨ri, A., 3070 Mori, A. L., 1957, 2472, 2484, 2825, 2826 Mori, R., 2675 Morii, Y., 2411 Morikawa, K., 2675 Morimoto, K., 712, 762 Morimoto, T., 395 Morin, J., 324 Morin, M., 3342, 3356 Morin, N., 824 Morinaga, H., 164 Morini, O. J., 1316 Morisseau, J. C., 1356, 2594, 2596 Morita, K., 1654, 1719 Morita, K. N, 1654, 1719, 1720, 1735 Morita, S., 3017 Morita, Y., 713, 1276, 1292, 2753, 2755, 2760 Morita, Z., 962, 963 Moriyama, H., 120, 121, 703, 768, 1153, 1270, 2135, 2211, 2575 Moriyama, J., 394

Author Index

I-231

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Moriyama, N., 837 Moriyasu, M., 627 Morosin, B., 2043, 2439, 2440, 2568 Morovic, T., 1682 Morozko, S. A., 3035 Morozova, Z. E., 179 Morrell, D. G., 2253 Morrey, J. R., 1294, 2748 Morris, A., 1972 Morris, D. E., 270, 291, 301, 580, 595, 620, 621, 851, 1151, 1156, 1455, 1465, 1471, 1474, 1479, 1481, 1925, 1926, 1958, 2400, 2472, 2479, 2480, 2484, 2607, 2845, 2846, 2850, 3035, 3036, 3101, 3126, 3127, 3128, 3131, 3132, 3152, 3155, 3156, 3160, 3161, 3164, 3170, 3171, 3174 Morris, D. F. C., 163 Morris, J., 1035, 2283, 3220 Morris, K., 790, 3063 Morris, W. F., 2195 Morrison, C. A., 2044, 2045, 2048, 2058 Morrison, J. C., 2035 Morrov, Y., 3063 Morrow, R. J., 1513, 1516 Morrow, W. G., 3340 Morse, J. W., 1138, 1753, 1809, 2400, 2553, 2726, 3024, 3175, 3176 Morss, L. R., xv, xvii, 1, 18, 33, 80, 106, 117, 119, 339, 380, 425, 431, 447, 451, 469, 471, 622, 728, 730, 731, 732, 733, 734, 735, 739, 989, 1061, 1063, 1064, 1092, 1109, 1303, 1312, 1313, 1315, 1328, 1330, 1352, 1354, 1413, 1419, 1446, 1454, 1460, 1464, 1465, 1468, 1469, 1471, 1473, 1474, 1475, 1479, 1482, 1483, 1526, 1537, 1543, 1547, 1555, 1557, 1605, 1606, 1624, 1629, 1753, 1776, 1790, 1874, 1901, 1928, 2065, 2082, 2113, 2122, 2124, 2125, 2126, 2132, 2136, 2137, 2143, 2144, 2147, 2153, 2154, 2161, 2178, 2180, 2182, 2190, 2191, 2230, 2233, 2264, 2267, 2270, 2293, 2396, 2397, 2419, 2420, 2526, 2538, 2539, 2542, 2560, 2562, 2563, 2572, 2590, 2675, 2821, 2840, 2934, 3096, 3101, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118, 3206, 3212, 3340, 3347, 3348, 3353, 3354 Mortera, S. L., 2457 Morterat, J. P., 405 Mortimer, G. E., 3326 Mortimer, M., 2115, 2205 Mortimer, M. J., 192, 945, 947, 949, 982, 1022, 1299, 2315 Mortl, K. P., 2256 Morton, C., 2984 Mortreux, A., 2930

Mosdzelewski, K., 35, 41, 1323, 1352, 1431 Moseley, J. D., 3258 Moseley, P. T., 78, 82, 106, 205, 738, 2413, 2418, 2421, 2423 Moser, J., 719, 720 Moser, J. B., 414, 415, 1019, 1020, 1021, 1022, 1050, 1052, 2411, 2413 Moser, W. S., 2692, 2712, 2722 Moskalev, P. N., 1323, 1363 Moskalev, Y. I., 3352, 3424 Moskovtchenko, J. F., 1507 Moskowitz, D., 66, 2407 Moskowitz, J. W., 1916 Moskvichev, E. P., 113 Moskvin, A. I., 129, 132, 218, 219, 504, 584, 602, 763, 764, 765, 769, 770, 771, 1161, 1171, 1172, 1177, 1178, 1179, 1180, 1338, 1352, 2585, 3347 Moskvin, L. N., 26 Mosley, W. C., 1312, 1313, 1414, 1419, 1420, 1422, 2396, 2397 Moss, F. A., 1402 Moss, J. H., 3061 Moss, M. A., 69, 72 Mosselmans, J. F., 3102, 3120, 3121, 3132, 3142, 3143, 3165, 3169 Mosselmans, J. F. W., 588, 593, 595, 1927, 1928, 2256, 2583 Mossman, D. J., 3172 Motegi, K., 1909 Motekaitis, R. J., 2557, 2558, 2559, 2568, 2571, 2575, 2576, 2579, 2581, 2582 Motoyama, G., 407 Motta, E. E., 2692, 2708 Mou, W., 164 Mouchel, D., 1293 Moukhamet-Galeev, A., 606, 611, 612, 2593 Moulin, C., 120, 1114, 1138, 1368, 1405, 1433, 2096, 2536, 2682, 2685, 3034, 3037, 3054 Moulin, J. P., 1356, 2594, 2596 Moulin, V., 120, 1138, 1354, 2591, 3022, 3034, 3037, 3054, 3064, 3382 Moulton, G. H., 1077, 1114 Moulton, R., 3126 Moulton, W. G., 455 Moune, O. K., 482, 2050, 2054, 2066 Moune-Minn, O. K., 2044 Mount, M. E., 3017 Mountford, P., 1962 Mountfort, S. A., 3050, 3060, 3062, 3064 Mousty, F., 2633, 2767 Moutte, A., 40 Moyes, L. N., 3165, 3167, 3169 Moze, O., 70, 73 Mozumi, Y., 391, 396 Mrad, O., 211 Mrazek, F. C., 378

I-232

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Mrosan, E., 63 Mucci, J. F., 1994 Mucke, A., 269 Mucker, K., 80 Mudge, L. K., 2704 Mudher, K. D. S., 1169, 1170, 2434, 2441, 2445, 2446 Mueller, M. H., 64, 66, 102, 106, 320, 372, 719, 721, 739, 742, 743, 744, 745, 882, 1022, 2283, 2407, 2429 Mueller, R., 1154, 3103, 3104, 3129 Mueller, U., 2420 Mueller, W., 161, 192, 193, 204, 207, 1023 Muenter, J., 2148 Muggenburg, B. A., 3413 Muherjee, S. K., 1271 Mu¨hleck, C., 1875, 1876 Mu¨hlenbernd, T., 2837, 2841 Muis, R. P., 2158, 2160, 2161, 2185, 2208, 2211 Mukaibo, T., 473 Mukaiyama, T., 2723, 2724 Mukoyama, T., 576, 577, 2165 Mulac, W., 1774, 1776 Mulac, W. A., 1325, 1326, 1337, 1416, 1424, 1430, 1774, 1776, 2077, 2526, 2531 Mulak, J., 470, 471, 491, 505, 740, 741, 745, 2252, 2278 Mulay, L. N., 2231 Mulford, R., 718 Mulford, R. N., 2085, 2161 Mulford, R. N. R., 97, 329, 722, 723, 724, 742, 743, 963, 1003, 1004, 1005, 1006, 1008, 1020, 1028, 1029, 1030, 1045, 1048, 1070, 1312, 1314, 1321, 1361, 1463, 2403, 2404, 2407, 2411 Mu¨ller, A., 76 Muller, A. B., 121, 125, 128, 421, 423, 425, 435, 440, 441, 457, 458, 469, 473, 474, 477, 478, 480, 481, 497, 502, 503, 509, 513, 514, 515, 516, 517, 536, 538, 543, 544, 545, 551, 552, 556, 593, 594, 595, 596, 597, 598, 599, 601, 603, 612, 1155, 1166, 1171, 1341, 2114, 2115, 2120, 2126, 2127, 2128, 2132, 2133, 2136, 2142, 2150, 2151, 2152, 2154, 2155, 2156, 2157, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2169, 2170, 2171, 2173, 2174, 2175, 2181, 2182, 2186, 2187, 2193, 2194, 2195, 2200, 2204, 2205, 2206, 2538, 2579, 2582, 3214, 3215, 3347, 3380, 3382 Mu¨ller, B. G., 78, 79 Mu¨ller, F., 80, 81, 100 Mu¨ller, G., 116, 2473, 2816, 2912 Muller, I., 863 Muller, M., 3057

Mu¨ller, M. H., 320, 321, 322 Muller, P. M., 301 Mu¨ller, R., 64, 3045, 3103, 3104, 3129 Mu¨ller, U., 413, 477, 496, 509, 510, 512, 515, 522, 554, 2419 Mu¨ller, W., 34, 35, 191, 343, 739, 740, 741, 742, 1271, 1286, 1293, 1297, 1298, 1299, 1304, 1312, 1316, 1317, 1318, 1319, 1323, 1328, 1402, 1403, 1410, 1411, 1412, 1413, 1414, 1415, 1417, 1420, 1421, 1424, 1450, 1584, 1629, 1785, 1790, 2123, 2160, 2264, 2267, 2268, 2315, 2384, 2386, 2387, 2411, 2413, 2695, 2699 Mu¨ller-Westerhoff, U., 630, 1802, 1894, 1943, 2252, 2485, 2851 Mullich, U., 1287, 2674, 2761 Mulliken, R. S., 1679 Mullins, L. J., 717, 837, 863, 864, 866, 869, 870, 871, 875, 1100, 1270, 2698, 2699, 2706, 2709, 2712, 2713 Mumme, I. A., 283 Mumme, W. G., 295 Munnemann, M., 1403 Munno, R., 269, 278 Munoz, M., 121, 124 Munslow, I. J., 2887 Mu¨nstermann, E., 83 Muntz, J. A., 3361, 3378, 3380, 3381 Mu¨nze, R., 2574 Munzenberg, G., 1653, 1654, 1660, 1701, 1713, 1717, 1719, 1720, 1735, 1737, 1738 Mu¨nzenberg, G., 6, 14, 164, 1621 Murad, E., 70, 2149 Muradymov, M. A., 856 Muradymov, M. Z., 2682, 2684 Murakami, T., 257, 270, 273, 277, 288, 290, 292, 294, 298, 299 Murakami, Y., 2288 Murakawa, M., 412 Murali, M. S., 705, 708, 712, 713, 1269, 1274, 1275, 1278, 1280, 1281, 1282, 1294, 2626, 2653, 2666, 2667, 2668, 2738, 2739, 2743, 2744, 2745, 2747, 2748, 2749, 2753, 2754, 2757, 2759 Muralidharan, K., 928 Muralidharan, S., 2676 Muraoka, S., 3023 Murasik, A., 414, 425, 439, 444, 447, 448, 455, 476, 479, 2257, 2258 Muratova, V. M., 3067 Murav’eva, I. A., 374, 376, 377 Murayama, Y., 1829 Murbach, E. W., 193, 2708, 2709 Murch, G. E., 367, 368, 1045 Murdoch, K., 422, 430

Author Index

I-233

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Murdoch, K. M., 2042, 2047, 2054, 2058, 2059, 2060, 2062, 2064, 2075, 2096, 2266 Murillo, C., 3130, 3131, 3132 Murillo, C. A., 162 Murmann, R. K., 2596 Muromura, T., 993, 994, 1018, 3218 Murphy, W. F., 321, 323, 1081 Murphy, W. M., 272, 293 Murray, A., 367, 368, 635, 3291, 3293, 3300 Murray, A. S., 3014 Murray, C. N., 1803, 3296 Murray, J. R., 75, 96, 2413 Murray, J. W., 3175 Murrell, M. T., 171, 189, 231, 3312, 3314, 3322 Murrillo, C., 2800 Murthy, M. S., 60 Murthy, P. R., 101 Murty, A. S. R., 115 Murzin, A. A., 856, 2682, 2684, 2685 Musante, Y., 1118, 1119 Muscatello, A. C., 839, 1278, 1280, 1431, 2605, 2606, 2653, 2655, 2656, 2666, 2667, 2671, 2738 Muse, L., 224 Musella, M., 357, 359, 1077 Musgrave, J., 822, 823, 3279, 3314 Musgrave, J. A., 270, 3171 Musgrave, L. E., 3234, 3235, 3260 Musigmann, C., 2655 Musikas, C., 43, 209, 220, 227, 726, 753, 773, 774, 1275, 1285, 1286, 1287, 1328, 1329, 1338, 1407, 1408, 1480, 1481, 1547, 1548, 2129, 2401, 2402, 2427, 2439, 2444, 2563, 2580, 2595, 2657, 2673, 2674, 2675, 2756, 2761, 2762, 3128 Musikas, G., 773 Mustre de Leon, J., 1112 Mutoh, H., 1049 Mutter, A., 286, 290 Muxart, R., 162, 164, 166, 167, 182, 184, 185, 195, 196, 197, 198, 199, 200, 207, 208, 209, 213, 215, 216, 217, 218, 219, 221, 222, 225, 227, 228, 229, 230, 2432, 2552 Mwenifumbo, C. J., 3027 Myasoedov, B. F., 29, 30, 161, 178, 179, 181, 182, 183, 184, 185, 187, 188, 195, 198, 199, 200, 207, 209, 219, 221, 224, 227, 228, 229, 230, 704, 705, 709, 782, 788, 856, 1110, 1117, 1271, 1283, 1284, 1323, 1325, 1326, 1327, 1329, 1330, 1331, 1355, 1365, 1368, 1402, 1405, 1407, 1408, 1409, 1410, 1416, 1422, 1423, 1430, 1431, 1433, 1434, 1448, 1449, 1450, 1451, 1471, 1479, 1480, 1481, 1484, 1509, 1512, 1513, 1546,

1547, 1548, 1554, 1584, 1585, 1606, 1625, 1633, 1636, 2651, 2656, 2661, 2666, 2667, 2668, 2673, 2684, 2738, 2739 Myasoedov, B. G., 1283 Myasoedov, B. V., 3282 Mydlarz, T., 416 Mydosh, J. A., 2351, 2352 Myers, R. J., 2231 Myers, W. A., 824, 3014 Myers, W. D., 1661, 1738 Mykoyama, T., 1935, 1936 Myrtsymova, L. A., 1398 Nabalek, C. R., 2134, 2135 Nabar, M. A., 110 Nabelek, C. R., 2700, 2715, 2719, 2721 NABIR, 1818 Nabivanets, B. I., 121, 125 Nace, R. L., 3129 Nachtrieb, N. H., 958 Nadeau, Kilius, L. R., 3318 Nadeau, M. J., 3014, 3063, 3317, 3318 Naegele, J. R., 795, 1286, 1297, 2336 Nagai, S., 1071 Nagaishi, R., 1430, 2095, 2098, 2099 Nagame, Y., 164, 1266, 1267, 1445, 1450, 1484, 1662, 1687, 1696, 1699, 1700, 1709, 1710, 1718, 1735 Nagao, S., 3023 Nagar, M. S., 708, 1281, 2747, 2748 Nagarajan, G., 1086 Nagarajan, K., 396, 1076, 2205, 2206 Nagasaki, S., 625, 795, 2594, 2738, 3024 Nagatoro, Y., 637 Nagels, P., 368 NAGRA, 3027, 3028 Nagy, B., 3172 Nagypa´ l, I., 590, 605 Na¨hler, A., 1665, 1666, 1695, 1699, 1700, 1702, 1710, 1717, 1718, 1735 Naik, R. C., 203 Nair, A. G. C., 2757 Nair, G. M., 1177, 1178, 1352, 3061 Nair, M. K. T., 1282, 2743, 2745 Nairn, J. S., 164, 173, 177, 180, 227 Naito, K., 340, 343, 344, 345, 347, 353, 354, 355, 356, 357, 360, 364, 369, 377, 378, 391, 393, 394, 396, 1025, 1026, 2405 Nakada, M., 727, 749, 750, 792, 793, 2256, 2257, 3043 Nakagawa, T., 410 Nakagawa, Y., 392 Nakahara, H., 1266, 1267, 1484, 1653, 1696, 1718, 1735 Nakahara, H. T., 164

I-234

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Nakai, H., 1965 Nakajima, A., 2668 Nakajima, K., 396, 2140, 2142, 2157, 2199, 2201, 2202, 2724 Nakajima, T., 1906, 1909 Nakama, S., 396, 398 Nakamatsu, H., 576, 577, 1935, 1936, 2165 Nakamoto, T., 727, 749, 750, 793, 2256, 2257 Nakamura, A., 360, 361, 362, 364, 1954, 1956, 1957, 1958, 2256, 2257, 2280, 2472, 2484, 2825, 2826, 2841 Nakamura, E., 3285 Nakamura, S., 407 Nakamura, T., 77, 760, 2657 Nakano, M., 1806 Nakano, Y., 1272, 1273, 2675 Nakashima, S., 3035 Nakashima, T., 120, 121 Nakatani, A., 382 Nakatani, M., 1352 Nakayama, S., 769, 2553, 3043, 3045 Nakayama, Y., 1073 Nakotte, H., 338, 339, 409, 412, 2289, 2290 Nalini, S., 1074 Nance, R. L., 865, 866, 867, 868, 870, 873, 874, 875, 3223 Nannicini, R., 2657, 2675, 2756 Nannie, C. A., 1297 Naramoto, H., 294 Narayanan, K., 76 Narayankutty, P., 1274 Naray-Szabo, L., 77 Nardel, R., 1293 Nardi, J. C., 2686 Narducci, A. A., 97, 420 Naresh, K., 3031 Narita, S., 776, 777, 778, 781, 782, 2585 Narten, A. H., 781, 2595, 3128 Narumi, K., 294 Nash, C. S., 1671, 1676, 1726, 1727, 1728, 1729, 1908, 1966, 1985 Nash, K., 1176 Nash, K. L., 607, 612, 615, 705, 988, 1168, 1269, 1274, 1275, 1280, 1281, 1286, 2558, 2560, 2562, 2570, 2572, 2579, 2582, 2585, 2586, 2588, 2589, 2590, 2597, 2603, 2604, 2605, 2606, 2622, 2626, 2641, 2649, 2650, 2652, 2655, 2656, 2663, 2664, 2666, 2667, 2691, 2726, 2727, 2739, 2742, 2747, 2758 Naslain, R., 67, 71 Nasluzov, V. A., 1906 Nassimbeni, L. R., 549, 2439 Nassini, H. E., 855 Nasu, S., 343, 2280 Natarajan, P. R., 1127, 1169, 1175, 1280, 1352, 2434, 2653, 2738, 2743, 2744 Natarajan, R., 1555

Natarajan, R. R., 1278 Natarajan, V., 1175 Nathan, O., 24 National Academy of Sciences, 1811 National Academy of Sciences Report, 3262 National Research Council, 1760 Natowitz, J. B., 1267 Natsume, H., 375 Naulin, C., 561 Naumann, D., 497 Navarro, A., 2438, 2439, 2443 Navaza, A., 380, 1928, 2439, 2449, 2450, 2452, 2453 Navaza, P., 3101, 3105, 3120, 3138, 3141 Nave, S., 2070 Nave, S. A., 1542 Nave, S. E., 1411, 1418, 1421, 1460, 1472, 1525, 1542, 1543, 1602, 1603, 2238, 2264, 2267, 2268, 2269, 2270, 2271, 2272, 2356 Nave, S. F., 1418, 1423 Navon, O., 3305 Navratil, J. D., 129, 771, 841, 843, 864, 875, 1079, 1277, 1278, 1292, 1328, 1398, 1403, 2114, 2426, 2427, 2546, 2580, 2626, 2650, 2653, 2662, 2692, 2712, 2722, 2727, 2737, 2752 Navrotsky, A., 113, 270, 287, 2157, 2159, 2193 Nawada, H. P., 355 Nazarenko, O. M., 26 Nazarewicz, W., 1736 Nazarov, P. P., 180 Nazarov, V. K., 772, 773 Nazarova, I. I., 1352, 1405, 1428, 1433 NBS Handbook, 3340 NCRP, 1819, 3396, 3413, 3422, 3424 Ndalamba, P., 768 NEA, 1759 Neal, T. J., 3280, 3327 Nebel, D., 132 Neck, V., 119, 120, 121, 122, 125, 126, 127, 130, 421, 423, 425, 435, 439, 440, 441, 457, 458, 469, 473, 474, 477, 478, 480, 481, 497, 502, 503, 509, 513, 514, 515, 516, 517, 536, 538, 543, 544, 545, 551, 552, 556, 593, 594, 595, 596, 597, 598, 599, 601, 602, 603, 727, 763, 766, 767, 769, 1147, 1148, 1149, 1150, 1154, 1158, 1160, 1161, 1165, 1166, 1181, 1782, 2115, 2117, 2120, 2126, 2127, 2128, 2132, 2136, 2137, 2138, 2142, 2144, 2151, 2152, 2153, 2154, 2155, 2157, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2170, 2171, 2174, 2175, 2176, 2179, 2181, 2182, 2186, 2187, 2190, 2191, 2192, 2193, 2194, 2195, 2197, 2200, 2203, 2204, 2206, 2538,

Author Index

I-235

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 2546, 2549, 2550, 2553, 2554, 2575, 2592, 3037, 3045, 3103, 3104, 3129 Neckel, A., 69, 72 Nectoux, F., 728, 729, 746, 748, 776, 777, 778, 779, 781, 782, 1057, 1181, 2431, 2432, 2443, 2559, 2565, 2570, 2572, 2574, 2585, 2586, 2594, 2595, 2596 Nectoux, P., 2443 Neeb, K.-H., 826, 828 Nefedov, V. S., 1670, 1672, 1692, 1693 Negi, R. S., 3061 Neher, C., 61 Neilson, G. W., 3117 Neirlich, M., 1960, 1962 Neish, A. C., 110, 114 Neitz, R. J., 2584 Nekhoroshkov, S. N., 1365, 1369 Nekrasova, V. V., 30, 161, 185 Nellis, W., 1319 Nellis, W. J., 2238, 2264, 2315, 2341, 2346 Nelms, S., 638, 3328 Nelson, B. K., 3159 Nelson, C. S., 2288 Nelson, D., 3017 Nelson, D. E., 1449, 3316 Nelson, D. M., 633, 1293, 1808, 2527, 2553, 3016, 3023, 3284, 3287, 3295 Nelson, D. R., 2660, 2661, 2727 Nelson, E. J., 967 Nelson, F., 30, 180, 769, 1150, 1151, 2580 Nelson, G. C., 859 Nelson, H. R., 399 Nelson, L. S., 3235, 3254 Nelson, M. R., 1508, 1511, 3283, 3286, 3295 Nelson, R. D., 889, 890, 961, 970 Nelson, R. S., 39 Nelson, T. O., 864, 989, 996, 3031 Nemcsok, D. S., 2164, 2165 Nemeto, S., 1408 Nemoto, S., 1282, 1286, 2743, 2761 Nenot, J. C., 1806, 1813, 1818, 1819, 1820, 1822, 1824, 3340, 3342, 3356, 3424 Nepomnyaskeru, V. Z., 1302 Nereson, N. G., 67, 71, 2407, 2408 Nervik, W. E., 19, 28, 29, 3281 Nesbitt, R. W., 3047, 3328 Nesper, R., 98, 100 Nestasi, M. J. C., 182 Nester, C. W., 1640 Nesterova, N. P., 1283, 2656, 2738 Nestor, C. W., 1669, 1682, 1725, 1727 Nestor, C. W. J., 33, 1296 Nestor, C. W., Jr., 1452, 1453, 1516, 1626, 1627, 1670, 1672, 1673, 1674, 1675, 1676, 1685, 1692 Neta, P., 371 Netherton, D. R., 3244 Neu, M., 1653, 3043

Neu, M. P., 289, 421, 593, 595, 602, 745, 749, 813, 861, 932, 988, 1041, 1043, 1069, 1110, 1112, 1114, 1116, 1117, 1138, 1148, 1149, 1154, 1155, 1156, 1159, 1162, 1163, 1164, 1165, 1166, 1178, 1179, 1314, 1327, 1328, 1340, 1341, 1359, 1370, 1445, 1664, 1684, 1693, 1694, 1695, 1706, 1716, 1824, 1925, 1926, 1927, 1928, 1991, 1992, 2530, 2553, 2558, 2583, 2590, 2592, 2669, 3035, 3087, 3106, 3108, 3109, 3112, 3113, 3115, 3118, 3123, 3125, 3130, 3131, 3133, 3134, 3160, 3167, 3210 Neubert, A., 70 Neuefeind, J., 596, 602, 1777, 1921, 2691 Neufeldt, S. J., 350, 373, 380, 382, 383, 729, 2077 Neuhaus, A., 372, 373 Neuilly, M., 824 Neuman, M. W., 3357, 3361, 3362, 3406, 3407 Neuman, W. F., 3351, 3355, 3357, 3361, 3362, 3376, 3406, 3407 Neumann, F., 66 Neumann, R., 264 Neu-Muller, M., 3397, 3399 Neurock, M., 1988, 1989, 1990 Neurock, M. J., 576 Neves, E. A., 2580 Nevitt, M. V., 90, 744, 1003, 1009, 1787 Newkome, G. R., 526 Newman, D. J., 2016, 2035, 2036, 2037, 2042, 2049, 2051, 2074, 2082, 2245 Newton, A. S., 63, 64, 65, 75, 78, 80, 81, 83, 95, 100, 107, 329, 332, 336, 841, 3246 Newton, D., 822, 3346, 3372, 3373 Newton, G. W. A., 854 Newton, T. W., 590, 606, 622, 760, 1117, 1118, 1120, 1123, 1124, 1125, 1126, 1127, 1129, 1130, 1131, 1132, 1133, 1134, 1135, 1136, 1137, 1138, 1139, 1140, 1142, 1144, 1145, 1146, 1151, 1152, 1159, 1162, 1181, 1332, 1333, 1334, 1778, 2131, 2583, 2594, 2597, 2598, 2599, 3036 Newville, M., 861, 3087, 3089, 3163, 3164, 3175, 3176, 3177 Newville, M. G., 291 Neyman, K. M., 1906 Neyroud, T. G., 2834, 2835, 2984 Ng, B., 2037, 2042, 2049, 2051 Ng, W. L., 70, 73 Ngian, F. H. M., 3065 Ngo-Munh, Th., 3024 Nguyen, A. D., 2054, 2059, 2060, 2062 Nguyen, K. A., 1908 Nguyen, S. N., 287 Nguyen-Nghi, H., 423, 445, 503, 505

I-236

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Nguyen-Trung, C., 121, 125, 128, 421, 423, 425, 435, 440, 441, 457, 458, 469, 473, 474, 477, 478, 480, 481, 497, 502, 503, 509, 513, 514, 515, 516, 517, 536, 538, 543, 544, 545, 551, 552, 556, 593, 594, 595, 596, 597, 598, 599, 601, 602, 603, 1155, 1166, 1171, 1341, 2114, 2115, 2120, 2126, 2127, 2128, 2132, 2133, 2136, 2142, 2150, 2151, 2152, 2154, 2155, 2156, 2157, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2169, 2170, 2171, 2173, 2174, 2175, 2181, 2182, 2186, 2187, 2193, 2194, 2195, 2200, 2204, 2205, 2206, 2538, 2554, 2555, 2579, 2582, 3214, 3215, 3347, 3380, 3382 Nichkov, I., 2715 Nichkov, I. F., 2715 Nicholl, A., 713 Nichols, J. A., 1918, 1919, 1920 Nichols, J. L., 903, 904 Nichols, M. C., 417, 418 Nicholson, C. A., 2732 Nicholson, G., 2457 Nicholson, M. D., 3017 Nickel, J. H., 932 Nicol, C., 1285, 2657, 2658 Nicolai, R., 3138, 3140, 3150, 3182 Nicolaou, G., 3062 Nicolet, M., 1033 Niedrach, C. W., 319 Niedzwiedz, W., 1507 Nief, F., 2491, 2869, 2870 Nief, G., 824 Nielsen, B., 31 Nielsen, H. S., 164, 170, 187 Nielsen, J. B., 117, 475, 495, 1082, 2827, 2868, 2869 Nielsen, O. B., 24, 164, 170, 187 Nielsen, P. E., 630 Nielson, C. W., 1863, 2028, 2029, 2040 Nier, A. O., 3309 Nierenberg, W. A., 190, 1847 Nierlich, M., 102, 106, 468, 469, 576, 582, 583, 1262, 1270, 2246, 2449, 2450, 2451, 2452, 2456, 2457, 2458, 2459, 2460, 2461, 2462, 2463, 2464, 2472, 2473, 2479, 2480, 2484, 2488, 2490, 2491, 2558, 2801, 2805, 2806, 2807, 2808, 2812, 2818, 2819, 2820, 2830, 2837, 2841, 2847, 2856, 2857, 2858, 2859, 2861, 2862, 2866, 2869, 2870, 2871, 2872, 2889, 2891, 2892, 2922, 2938 Niese, S., 1433, 1434, 3023 Niese, U., 755 Nieupoort, W. C., 578 Nieuwenhuys, G. J., 2342 Nieuwenhuyzen, M., 854, 2690

Nieuwpoort, W. C., 1905, 1935, 1936 Nieva, G., 62 Nifatov, A. P., 3352, 3424 Nigon, J. P., 1312, 1319, 1326, 1366, 2427 Nigond, L., 1285, 2657, 2756 Niinisto¨ , L., 580, 581 Niinisto¨, L., 2434 Niitsuma, N., 100 Nikaev, A. K., 1325, 1327, 1367, 1368 Nikahara, H., 1267 Nikalagevsky, V. B., 1352 Nikishova, L. K., 1127 Nikitenko, S. I., 762, 1126, 1138, 1175 Nikitin, E. A., 1398 Nikitina, G. P., 1049 Nikitina, S. A., 787, 3034 Nikitina, T. M., 3111, 3122 Niklasson, A. M. N., 2355 Nikoforov, A. S., 709 Nikolaev, A. V., 185, 1300 Nikolaev, N. S., 1101, 1102, 1107, 2426 Nikolaev, V. M., 1292, 1427, 1512, 1585 Nikolaevskii, V. B., 1325, 1327, 1329, 1338, 1352, 1367, 1368, 2527 Nikolotova, Z. A., 108 Nikolotova, Z. I., 705, 709 Nikol’skaya, T. L., 791, 3049, 3052 Nikonov, M., 3101, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118 Nikonov, M. V., 726, 770, 1110, 3043 Nikula, T. K., 44 Nilov, V., 164 Nilson, L. F., 61, 63, 80, 81, 82, 95, 101, 104 Nilsson, B., 1661 Nilsson, S. G., 1661 Ninov, V., 6, 14, 164, 1447, 1582, 1653, 1662, 1701, 1711, 1712, 1713, 1717, 1737 Nisbet, A., 3023 Nishanaka, I., 1267 Nishikawa, M., 366 Nishimura, Y., 3062 Nishina, Y., 167 Nishinaka, I., 164, 1266, 1267, 1484, 1696, 1718, 1735 Nishinaka, K., 1445 Nishio, G., 1019 Nishioka, T., 407 Nissen, D. A., 2698 Nissen, M. K., 225 NIST, 132, 597, 602, 639 Nitani, N., 727, 767, 770, 775, 2140, 2426 Nitsche, H., 589, 718, 719, 722, 726, 727, 728, 739, 744, 745, 767, 769, 771, 863, 881, 888, 891, 988, 989, 1008, 1019, 1021, 1045, 1047, 1048, 1085, 1086, 1087, 1098, 1100, 1101, 1110, 1111, 1114, 1117, 1118, 1131, 1147, 1148, 1149, 1150, 1155, 1157, 1158, 1160, 1162,

Author Index

I-237

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 1163, 1167, 1169, 1170, 1171, 1178, 1180, 1181, 1319, 1447, 1662, 1664, 1666, 1684, 1685, 1695, 1701, 1702, 1711, 1712, 1713, 1714, 1716, 1717, 1735, 1737, 1803, 1923, 1973, 1974, 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2133, 2136, 2137, 2140, 2142, 2144, 2145, 2151, 2152, 2154, 2155, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2170, 2171, 2173, 2174, 2175, 2182, 2186, 2187, 2193, 2194, 2195, 2197, 2199, 2200, 2201, 2204, 2206, 2538, 2568, 2576, 2578, 2582, 2583, 2588, 2592, 3025, 3029, 3037, 3039, 3043, 3044, 3046, 3069, 3095, 3102, 3106, 3107, 3111, 3112, 3122, 3131, 3135, 3138, 3140, 3141, 3142, 3145, 3146, 3147, 3148, 3149, 3150, 3152, 3154, 3155, 3160, 3161, 3165, 3166, 3167, 3173, 3176, 3177, 3179, 3181, 3182, 3183, 3206, 3213, 3302, 3347, 3381, 3382, 3416, 3420 Nitschke, J. M., 6, 1653 Nix, J. R., 1661 Nixon, J. Z., 851 NN, 1269, 1273 Noakes, D. R., 2284 Nobis, M., 2982 Nodono, M., 2924 Noe´, M., 1411, 1413, 1414, 1419, 1457, 1460, 1519, 1520, 1521, 1525, 1533, 1534, 1538, 1543, 1596, 1599, 1600, 2269, 2270, 2396, 2397, 2413, 2417 Noel, D., 2649 Noe¨l, H., 75, 96, 97, 402, 406, 407, 413, 414, 415, 416, 417, 420, 423, 425, 435, 437, 440, 456, 457, 470, 473, 474, 478, 479, 499, 502, 509, 514, 515, 516, 538, 544, 551, 2407, 2408, 2413, 2414, 2422, 2424 Noer, R. J., 63, 2315, 2350 Nogar, N. S., 1874, 1875, 1877 Nogueira, E. D., 2702 Nohira, T., 2691 Nolan, S. P., 2822, 2893, 2912, 2924, 2934, 2965 Noland, R. A., 319, 2712 Noller, B. N., 3057 Noltemeyer, M., 2875 Nomura, K., 1281, 1282, 2743, 2747, 2761 Nomura, Y., 343 Noon, M. E., 1176 Nordenskjo¨ld, A. E., 75 Nordine, P. C., 963 Nordling, C., 60 Nordstrom, A., 851 Nordstro¨m, L., 2248, 2289, 2291 Nore´n, B., 2579 Norling, B. K., 1053

Norman, J., 2548, 2549 Norman, M. R., 2353 Normile, P., 2371 Normile, P. S., 2237, 2286 Norreys, J. J., 69 Norris, D. I. R., 391, 396 Norris, J. O. W., 1931, 2080, 2085, 2086, 2087 Norseev, Y., 28, 43 No¨rtemann, F., 1906 Northrup, C. J. M., Jr., 330, 331 Northrup, D. R., 3065 Norton, J. R., 2924 Norvell, V. E., 1547 Norwood, W. D., 3413 Noskin, V. E., 3282, 3295 No¨th, H., 67 Nottorf, R., 64, 421 Nottorf, R. W., 63, 64, 65, 329, 332, 336, 3246 Novak, C. F., 127, 1341 Nova´k, M., 264, 281 Novakov, T., 1452 Novgorodov, A. F., 40, 822 Novichenko, V. L., 28, 38, 220 Novikov, A. P., 788, 1408, 1409, 2673 Novikov, G. I., 80, 81, 82, 1681 Novikov, Y. P., 704, 705, 782, 3282 Novikov, Yu. P., 184, 188 Novikova, G. I., 20, 24 Novion, D., 739, 740, 741, 742 Novo-Gradac, K. J., 1959, 1993 Novoselova, A. B., 424 Nowak, E. J., 1292 Nowicki, L., 340, 345, 348 Nowik, I., 719, 720, 721, 743 Nowikow, J., 214, 217 Nowotny, H., 67, 69, 71, 72 Noyce, J. R., 3293 Nozaki, Y., 44, 231 Nriagu, J. O., 297 Nugent, L. J., 33, 38, 118, 1328, 1329, 1330, 1363, 1423, 1424, 1446, 1452, 1454, 1460, 1479, 1480, 1481, 1482, 1523, 1526, 1529, 1546, 1547, 1548, 1555, 1557, 1592, 1604, 1606, 1607, 1630, 1636, 1641, 1643, 1647, 1859, 1872, 2122, 2124, 2542 Nugent, M., 291, 3131, 3160, 3161, 3164 Nuhn, H.-D., 3088 Numata, M., 1018, 1421 Nunez, L., 1295, 2655, 2738, 2739, 2750, 2751, 2752 Nunnemann, M., 60, 859, 1296, 1452, 1513, 1588, 1590, 1840, 1875, 1877, 3047, 3321 Nurmia, M., 6, 1447, 1629, 1635, 1638, 1639, 1640, 1641, 1643, 1645, 1646, 1647, 1653, 1660, 1662, 1692, 1705, 2575

I-238

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Nurmia, M. J., 182, 1445, 1447, 1635, 1642, 1643, 1645, 1646, 1662, 1664, 1684, 1693, 1694, 1695, 1696, 1697, 1698, 1699, 1703, 1704, 1705, 1706, 1716 Nurnberg, O., 2953 Nuttall, R. L., 34, 2114 Nuttall, W. J., 2234 Nyce, G. W., 1956, 2473, 2476, 2477, 2805, 2816, 2857 Nyle´n, T., 3032 Nyssen, G. A., 2605 Oates, W. A., 927 Oatts, T. J., 3327 Obata, T., 2275, 2279, 2294 Obbade, S., 298, 301 Oberkirch, W., 116, 2865 Oberli, F., 3047 Oberti, R., 261, 301 O’Boyle, D. R., 892, 894, 896, 898, 900, 901, 902, 903, 904, 905, 907, 908, 909, 910, 911, 912, 913, 914, 933, 3213, 3238 O’Brian, R. J., 3156 O’Brien, R. S., 3017 O’Brien, S. C., 2864 Occelli, F., 964, 965, 2342 Ochiai, A., 407 Ochiai, K., 637 Ochsenfeld, W., 2732 Ochsenkuehn Petropulu, M., 3070 Ockenden, D. W., 1151 Ockenden, H. M., 1004, 1007, 1008, 1018, 3212, 3217, 3218, 3222 O’Conner, J. D., 3305 Oddou, J. L., 719, 720 Odie, M. D., 324 Odintsova, N. K., 1848 Odoj, R., 1288, 1289, 1294, 1295, 2657, 2675, 2676, 2749, 2756, 2762 Odom, A. L., 2888, 3033 Odom, J. D., 452, 2801 O’Donnell, T. A., 198, 562, 1084, 1101, 2426 OECD/NEA Report, 310, 705, 793 Oesterreicher, H., 66 Oesthols, E., 3152, 3153, 3154 Oetting, F. H., 321, 322 Oetting, F. L., 61, 80, 81, 351, 352, 353, 362, 421, 436, 437, 470, 471, 473, 475, 476, 486, 502, 504, 505, 510, 511, 539, 541, 546, 553, 718, 890, 891, 945, 949, 950, 963, 1021, 1028, 1048, 1086, 1098, 1101, 1297, 1298, 1328, 1329, 1403, 1409, 1410, 1417, 1482, 2114, 2115, 2116, 2120, 2123, 2125, 2126, 2127, 2128, 2140, 2157, 2160, 2161, 2163, 2165, 2167, 2168, 2169, 2172, 2181,

2182, 2186, 2188, 2538, 2539, 3204, 3215, 3216 Ofelt, G. S., 2090, 2093 Ofer, S., 862 Ofte, D., 962, 963, 1033 Oganessian, Y. T., 6, 822, 1653, 1654, 1660, 1707, 1719, 1720, 1735, 1736, 1738 Oganessian, Yu. Ts., 14 Ogard, A. E., 357, 1004, 1007, 1048, 1077, 1093, 1095, 2140 Ogasawara, H., 861 Ogasawara, M., 2984 Ogawa, T., 719, 720, 721, 1018, 1019, 1317, 1421, 2185, 2186, 2201, 2693, 2723, 2724, 2725 Ogden, J., 3223, 3224, 3225 Ogden, J. S., 364, 365, 1021 Ogden, M. I., 2456, 2457, 2458, 2461 Ogle, P. R., 505, 506, 535 Ogliaro, F., 435 Ogorodnikov, B., 3016 Oguma, M., 390, 394, 396, 397 Ohara, C., 2743 O’Hare, D., 593, 2256 O’Hare, P. A. G., 357, 358, 372, 378, 2114, 2150, 2151, 2156, 2157, 2158, 2159, 2160, 2161, 2193 Ohde, H., 2679 Ohe, Y., 719, 720 Ohff, A., 2927 Ohishi, M., 1981 Ohmichi, T., 390, 391, 396, 743, 1022, 2201 Ohmori, T., 352 Ohnesorge, W. E., 115 Ohno, T., 2864 Ohnuki, T., 273, 294, 822, 1160, 3046 Ohse, R. W., 280, 291, 364, 366, 367, 1019, 1074, 1403, 1411, 2149, 2202 Ohta, T., 77 Ohtaki, H., 118, 2531, 3103, 3105 Ohtani, T., 1071 Ohtsuki, T., 164 Ohuchi, K., 1025, 1026, 1049, 1056, 1057 Ohwada, K., 372, 373, 375, 460, 461, 462, 463, 467, 520, 533, 534 Ohya, F., 356 Ohyama, T., 1266, 1267 Ohya-Nishiguchi, H., 382, 2245 Ohyoshi, A., 1352 Ohyoshi, E., 1352 Oi, N., 988 Oikawa, K., 407 Oishi, Y., 395 Ojima, H., 189 Ojima, I., 2966, 2974 Okajima, S., 1148, 1155, 1172, 3043, 3044 Okamoto, H., 1018, 1302, 1412, 1466, 2398

Author Index

I-239

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Okamoto, H. J., 1421 Okamoto, Y., 719, 743, 1992 Okatenko, P. V., 1821 Okazaki, M., 397 O’Kelley, G. D., 1636, 2526 Oken, D. E., 3380 Okladnikova, N. D., 1821 Olander, D. R., 366, 367 Oldham, R. D., 3345, 3354, 3355, 3371, 3378, 3384 Oldham, S. M., 1185 Olinger, H., 3397, 3399, 3400 Olivares, J. A., 3322 Oliver, G. D., 1507 Oliver, J., 1479, 1605, 3114 Oliver, J. H., 774, 2581, 2582 Oliver, J. R., 2735 Olivian, M., 2953 Olivier, S., 1806 Ollendorff, W., 1323 Ollier, N., 277 Olmi, F., 269 Olofson, J. M., 2924 Olofsson, V., 1803, 1804, 1806, 1807, 1808, 1810 Olonde, X., 2930 O’Loughlin, E. J., 3165, 3168 Olsen, C. E., 191, 193, 334, 335, 886, 888, 909, 949, 955, 957, 981, 2273, 2315, 2350, 2355 Olsen, J. S., 2407 Olsen, K., 1965 Olsen, L. G., 1282, 2741 Olsen, S. S., 2407 Olsen, T., 409 Olson, C. G., 1056 Olson, G. B., 920, 933 Olson, R. A., 293 Olson, W. M., 97, 742, 743, 976, 977, 1008, 1020, 1074, 1312, 1314, 1361, 2404, 2411 Omejec, L., 69, 70, 73 Omenetto, N., 3037 Omori, T., 219 Omtvedt, J. P., 1662, 1666, 1695, 1701, 1702, 1712, 1713, 1717, 1735, 1737 Omtvedt, L. A., 1666, 1695, 1702, 1717, 1735, 1737 Ondik, H. M., 459, 460, 461, 463 Ondrus, P., 262, 263, 2427 Onishi, K., 1282, 1408, 2743 Ono, R., 1431 Ono, S., 339, 1696, 1718, 1735 Onodera, Y., 2762 Onoe, J., 576, 577, 1194, 1935, 1936, 2165 Onosov, V. N., 119 Onoufriev, V., 1071

Onuki, Y., 406, 407, 412, 2239, 2256, 2257, 2280 Oomori, T. J., 3160 Oosawa, M., 225, 226 Opalovskii, A. A., 539, 542 Ophel, T. R., 3317, 3318 Oppeneer, P. M., 2359 Orchard, A. F., 1681 Ordejon, B., 1908 Ordonez-Regil, E., 3171 Orlandi, K., 3017 Orlandi, K. A., 3022 Orlandi, P., 269 Orlandini, K. A., 1293, 1808, 3280, 3287, 3288, 3295, 3296, 3311, 3314 Orleman, E. F., 621 Orlemann, E. F., 841 Orlinkova, O. L., 374, 375 Orlova, A. I., 2431 Orlova, A. S., 374 Orlova, I. M., 539, 565, 2441 Orlova, M. M., 1156 Orman, S., 3242 Orme, J. T., 918, 919 ORNL, 2700 Oro, L. A., 2953 Orr, P. B., 1449, 1450, 1451, 1509, 1510, 1584, 1585 Orr, R. D., 1409, 1432, 1434 Orrock, B. J., 2735 Ortego, J., 501, 523 Ortego, J. D., 522 Orth, D. A., 2735 Ortiz, E. M., 1141 Ortiz, J. V., 1959, 1965, 2480, 2481, 2482, 2837 Ortiz, M. J., 1973 Ortiz, T. P., 1268 Osawa, S., 189 Osborn, R., 389, 929, 2278, 2279, 2283, 2284, 2285 Osborne, D. W., 64, 66, 333, 372, 376, 378, 382, 486, 502, 1048, 2176, 2273, 2282 Osborne, M. M., 1132 Osborne-Lee, I. W., 1505, 1506, 1507 Oser, B. L., 3362 O’Shaughnessy, P. N., 2984 Oshima, K., 345, 347, 355, 369 Osicheva, N. P., 583, 601 Osipenko, A. G., 2705, 2706 Osipov, S. V., 1145, 1338 Ossola, F., 2472, 2473, 2484, 2820, 2825, 2841 Ost, C., 1132 Oster, F., 62 Osteryoung, R. A., 2687, 2691 ¨ sthols, E., 125, 127, 128, 129, 130, 131, 132 O Ostlund, N. S., 1903 Osugi, T., 2693 Otey, M. G., 566

I-240

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Othmer, U., 1880 Ott, H., 2237 Ott, H. R., 2312, 2333, 2343, 2351, 2360 Ott, M. A., 1152, 3036 Otten, E. W., 1875, 1876, 1880 Otten, E.-W., 3044, 3047, 3048, 3320, 3321 Otto, K., 329, 330, 331, 332 Otto, T., 1735 Ottolini, L., 261, 301 Otu, E. O., 2652 Ouadi, A., 43 Ouahab, L., 2256 Ouchi, K., 375, 391, 395, 396, 993, 994, 1018, 3218 Oughton, D. H., 3063 Ouillon, N., 109, 1172 Ouqour, A., 76 Oura, Y., 1266, 1267, 1445, 1484, 1662, 1696, 1709, 1718, 1735 Outebridge, W. F., 292 Ouvrard, L., 75, 81, 109 Ouweltjes, W., 551, 552, 2158, 2160, 2161, 2165, 2187 Ouzounian, G., 2591 Overhauser, A., 2052 Overman, R. F., 1448, 1449, 1471 Overman, R. T., 186 Oversby, V. M., 1145, 3109, 3210 Oweltjes, W., 514, 543 Owens, D. R., 103, 113 Oyamada, R., 93 Ozawa, M., 1281, 1282, 1408, 2743, 2747, 2761, 2762 Ozin, G. A., 1994 Pabalan, R. T., 301, 3156 Pabst, A., 269 Paccagnella, A., 3064 Pace, R. J., 3117 Pachauri, O. P., 2587 Paciolla, M. D., 3140, 3150 Padilla, D., 2752 Padiou, J., 414, 417, 2413 Paffett, M. T., 1035, 1043, 1044, 3210, 3211, 3220 Page, A. G., 2668 Page`s, M., 79, 86, 87, 90, 92, 111, 113, 391, 459, 460, 511, 728, 729, 730, 735, 739, 740, 741, 742, 743, 745, 746, 748, 776, 777, 778, 779, 781, 782, 792, 1057, 1065, 1066, 1067, 1068, 1069, 1105, 1106, 1107, 1181, 1312, 1321, 1335, 1359, 1360, 1416, 1430, 2315, 2370, 2413, 2443, 2559, 2565, 2570, 2572, 2574, 2585, 2586, 2594, 2595, 2596 Pagliosa, G., 713, 2756 Pagoaga, M. K., 259, 282

Pai, M. R., 110 Paine, R. T., 502, 519, 529, 530, 536, 1283, 1431, 1935, 1968, 2165, 2400, 2420, 2426, 2480, 2573, 2656, 2832, 2891 Painter, E., 3353, 3356, 3362, 3366, 3370, 3378, 3386, 3395, 3407, 3424 Paisner, J. A., 859, 1873, 1874, 1875, 1877, 1878 Paixa˜o, J. A., 409, 412, 2287, 2292, 2439 Palacios, M. L., 3171 Palacz, Z. A., 3313 Palade, D. M., 779 Palanivel, B., 63, 100 Palei, P. N., 185, 188, 218, 219, 228 Palenik, C. S., 271 Palenzona, A., 407, 2204 Paley, P. N., 184, 1129, 1130 Palfalvi, J., 1432 Palisaar, A.-P., 98 Palladino, N., 2865 Palmer, B. A., 1840, 1843, 1844, 1845, 1846, 1863 Palmer, C., 110, 112 Palmer, C. E. A., 287, 1114, 1148, 1155, 1160, 1163, 1340, 2583 Palmer, D., 421, 423, 425, 435, 439, 440, 441, 457, 458, 469, 473, 474, 477, 478, 480, 481, 497, 502, 503, 509, 513, 514, 515, 516, 517, 536, 538, 543, 544, 545, 551, 552, 556, 593, 594, 595, 596, 597, 598, 599, 601, 602, 603, 2115, 2117, 2120, 2126, 2127, 2128, 2132, 2136, 2137, 2138, 2142, 2144, 2151, 2152, 2153, 2154, 2155, 2157, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2170, 2171, 2174, 2175, 2176, 2179, 2181, 2182, 2186, 2187, 2190, 2191, 2192, 2193, 2194, 2195, 2197, 2200, 2203, 2204, 2206, 2538, 2546, 2554, 2555 Palmer, D. A., 1147, 1148, 1149, 1150, 1155, 1158, 1160, 1161, 1165, 1166, 1181 Palmer, P. D., 580, 595, 620, 621, 763, 766, 861, 1051, 1112, 1115, 1123, 1125, 1131, 1132, 1151, 1152, 1156, 1162, 1164, 1166, 1359, 1455, 1465, 1471, 1474, 1479, 1481, 1925, 1926, 1927, 1928, 2427, 2428, 2429, 2450, 2451, 2583, 2607, 3035, 3036, 3057, 3087, 3108, 3109, 3112, 3113, 3115, 3118, 3123, 3125, 3126, 3127, 3128, 3130, 3131, 3133, 3134, 3136, 3160, 3167, 3210 Palmer, P. P., 289, 602 Palmy, C., 63 Palsgard, E., 297 Pal’shin, E. S., 161, 178, 179, 181, 182, 183, 184, 185, 187, 188, 195, 198, 199, 200, 207, 209, 219, 224, 228, 229, 230

Author Index

I-241

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Palstra, T. T. M., 2351 Pan, C., 2864 Pan, Q., 191 Panak, P., 1428 Panak, P. J., 223, 2588, 3179, 3181, 3182, 3183 Panattoni, C., 2439, 2440 Panchanatheswaran, K., 2472, 2826 Panczer, G., 277 Pandey, A. K., 2659, 2750 Pandit, S. C., 540, 566, 2441 Pankratz, L. B., 2710 Panlener, R. J., 396 Pannetier, J., 467 Panov, A. V., 989, 996 Pansoy-Hjelvic, M. E., 851, 3022, 3181 Paolucci, G., 452, 548, 2468, 2471, 2473, 2487, 2491, 2819, 2824, 2831 Papadopulos, N. N., 3057 Papenguth, H. W., 3022, 3179, 3181 Papiernik, R., 509 Papina, T., 1806 Papirek, T., 1507 Pappalardo, R., 2051 Pappalardo, R. G., 1312, 1324, 1325 Paprocki, S. J., 1045, 1049 Paquet, F., 3352, 3364, 3377, 3398, 3399, 3413, 3423 Paratte, J. M., 3016 Pardue, W. M., 1011, 1015, 1018, 1019, 1021, 1022, 1045, 1048 Parida, S. C., 2209 Parissakis, G., 3070 Park, G. I., 2669 Park, H. S., 2669 Park, I.-L., 626, 627 Park, J. F., 3340, 3352, 3424 Park, K., 397 Park, Y.-Y., 2681 Parker, V. B., 34, 80, 81, 421, 436, 437, 470, 471, 473, 475, 476, 486, 502, 504, 505, 510, 511, 539, 541, 546, 553, 1086, 1098, 1101, 2114, 2128, 2157, 2160, 2161, 2163, 2165, 2167, 2168, 2169, 2172, 2181, 2182, 2186 Parkin, G., 2827, 2849 Parkin, I. P., 410, 412, 420 Parkman, R. H., 3165, 3167 Parks, G. A., 795, 2531, 3094, 3102, 3111, 3122, 3127, 3139, 3152, 3155, 3158, 3165, 3169 Parks, R. D., 63 Parks, S. I., 455 Parma, L., 3037 Parnell, J., 3172 Parpia, F. A., 1643, 1670 Parpiev, N. A., 2441 Parr, R. G., 1671, 1903 Parry, J., 1943, 1956, 2473

Parry, J. S., 117, 2240, 2803, 2806, 2807, 2854, 2856 Parry, S. F. S., 2710 Parry, S. J., 635, 636, 3303, 3306 Parshall, G. W., 2924 Parson, T. C., 2851 Parsonnet, V., 817, 1829 Parsons, B. I., 164, 186, 187 Parsons, R., 371 Parsons, T. C., 116, 1411, 1519, 1520, 1525, 1543, 1547, 1590, 1595, 1596, 1604, 2269, 2270, 2417, 2422, 2486, 2488 Parthasarathy, R., 180 Partington, J. R., 19, 367 Parus, J. L., 785 Pascal, J., 324 Pascal, J. L., 101 Pascal, P., 421 Pascard, R., 740, 1004, 1052, 1054, 2413 Paschoa, A. S., 3069 Pascual, J., 180, 187 Pasero, M., 268, 269, 298 Pashalidis, I., 1160, 1165, 1166 Pasilis, S. P., 2400 Pasquevich, D. M., 855 Passler, G., 33, 60, 859, 1296, 1403, 1452, 1513, 1588, 1590, 1840, 1875, 1876, 1877, 1884, 3047, 3321 Passo, C. J., 3283 Passow, H., 3359, 3362 Passynskii, A., 2531 Pastor, R. C., 78 Pasturel, A., 2208 Pastuschak, V. G., 711, 712, 761, 1143, 2757 Paszek, A., 1455, 1515, 1544 Paszek, A. P., 422, 453, 2039, 2057, 2259 Patat, S., 385, 388 Patchell, R. A., 1507 Patel, C. C., 101 Patel, S. K., 182 Patel, T., 466 Patelli, A., 3069 Pathak, P. N., 182, 184, 2736 Patil, K. C., 2442 Patil, S. K., 752, 772, 773, 774, 790, 1168, 1169, 1170, 1422, 2579, 3052, 3061 Patin, J. B., 1447, 1582, 1654, 1662, 1664, 1666, 1684, 1685, 1695, 1701, 1702, 1711, 1712, 1713, 1714, 1716, 1717, 1719, 1735, 1736, 1737, 1738 Patin, J. J., 14 Patnaik, D., 86, 91 Patrick, J. M., 1174, 2441 Patrusheva, E. N., 1449 Patrussi, E., 1070, 1071, 1072 Patschke, R., 97 Patton, F. S., 319 Pattoret, A., 322, 351, 352, 353, 362, 364, 365

I-242

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Pattrick, R. A. D., 3165, 3169 Patzschke, M., 1941 Paul, M. T., 767, 768, 777, 779, 780, 782 Paul, R., 390, 392 Paul, R. C., 105 Pauli, H. C., 1883 Pauling, L., 3093 Paulka, S., 42 Paulovic, J., 1909 Paulus, E. F., 2655 Paulus, W., 185, 186, 1447, 1662, 1679, 1684, 1687, 1698, 1699, 1705, 1708, 1709, 1710, 1716, 1718 Pauson, P., 2799 Pauson, P. L., 1800 Pautov, L. A., 261 Paviet, P., 1425, 1426, 1427 Paviet-Hartmann, P., 861, 1041, 1043, 1112, 1154, 1155, 1166, 3109, 3210 Pavlikov, V. N., 112 Pavlinov, L. V., 364 Pavlotskaya, F. I., 704, 782, 783 Pavlov, V. C., 364 Paw, J. C., 2472, 2473, 2561, 2825, 2826 Paxton, H. C., 821, 988 Payne, G. F., 746, 748, 1184, 1191, 1474, 2476, 2483, 2484, 2485, 2843 Payne, G. L., 1545 Payne, M., 2877 Payne, T. E., 273, 3165, 3166, 3167, 3176 Pazukhin, E. M., 1352 Peacock, R. D., 732, 733, 734, 2426 Pearce, J. H., 718, 719, 904, 905, 909 Pearce, M., 2591, 3419, 3421 Pearce, M. J., 3419, 3421 Pearce, N. J. G., 3047 Pearcy, E. C., 272, 293 Pearse, A. G. E., 3349 Pearson, W. B., 98 Pe´caut, J., 598, 1963, 1965, 2452, 2584 Pecher, C., 3401 Pecoraro, V. L., 1824, 2591, 3349, 3359, 3364, 3365, 3376 Peddicord, K. L., 988 Pedersen, J., 164, 170 Pedersen, K., 3069 Pederson, L. R., 2760 Pederson, M. R., 1904 Pedicord, K. L., 2199, 2202 Pedley, J. B., 2149 Pedregosa, J. C., 110 Pedretti, U., 2490, 2491, 2493, 2859, 2865 Pedrini, C., 81 Pedziwiatr, A. T., 67 Peek, J. M., 861 Peeters, O., 267, 268 Peetz, U., 395 Pei-Ju, Z., 2452, 2453, 2456

Peiris, M. A. R. K., 3308 Pekarek, V., 847 Pekov, I. V., 268, 298 Peleau, B., 3024 Pe´ligot, E., 254, 413, 421, 2592 Pelissier, M., 1683, 1907, 1909 Pell, M. A., 97, 420 Pellegrini, V., 42, 43 Pelletier, J.-F., 2930 Pelletier-Allard, N., 1862 Pellizzi, G., 546, 547, 553, 554 Pelsmaekers, J., 353, 354 Pemberton, J. E., 2400 Pe´neau, A., 81 Peneloux, A., 1663 Peng, Q. X., 108 Peng, S., 2140 Peng, Z., 2980 Peng-Nian, S., 2912 Pe´nicaud, M., 2371 Penkin, M. V., 1365, 1369 Penneman, R. A., 78, 86, 87, 88, 90, 91, 92, 103, 112, 201, 202, 222, 424, 446, 451, 452, 458, 459, 461, 465, 466, 488, 502, 504, 505, 506, 507, 519, 520, 734, 1044, 1058, 1059, 1060, 1062, 1105, 1106, 1107, 1114, 1265, 1271, 1273, 1291, 1296, 1312, 1314, 1319, 1322, 1323, 1325, 1326, 1328, 1329, 1331, 1333, 1365, 1366, 1367, 1369, 1397, 1398, 1401, 1402, 1410, 1417, 1418, 1429, 1430, 1468, 1674, 1699, 1728, 1729, 1732, 1733, 1760, 1923, 2415, 2420, 2427, 2449, 2450, 2451, 2452, 2471, 2472, 2601, 3163, 3281 Pennington, M., 2439 Pennington, W. T., 475, 495, 2827, 2868 Penny, D. J., 2390, 2394 Penrose, W., 3017 Penrose, W. R., 1808, 3022, 3287 Pense-Maskow, M., 1665, 1695 Pentreath, R. J., 782 Peny, Z., 263 Peper, S. M., 298 Peppard, D. F., 27, 107, 115, 171, 172, 175, 184, 219, 704, 822, 824, 1275, 1448, 1490, 1697, 2574, 2592, 2650, 2672, 3016, 3276 Pepper, M., 1192, 1196, 1670, 1671, 1894, 1895, 1900, 1902, 1903, 1908, 1909, 1915, 1916, 1917, 1934, 1971, 1976, 1994, 2400, 2561 Pepper, R. T., 378 Peralta, J. E., 1906, 1936, 1937, 1938 Perdew, J. P., 1903, 1904 Perego, G., 2420, 2471, 2472 Pereira, L. C. J., 1304 Perekhozheva, T. N., 1432, 1433

Author Index

I-243

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Perelygin, V. P., 1706 Peretrukhin, V. F., 756, 764, 1117, 1118, 1133, 1327, 1329, 1416, 1430, 1480, 1548, 1636, 2127, 2553, 3052, 3053 Peretz, M., 64, 336 Perevalov, S. A., 1512 Perey, M., 20, 27 Pereyra, R. A., 876, 877, 878, 916, 920, 921, 933, 936, 945, 947, 948, 949, 960, 964 Perez, I, Gimenez, J., 1805 Perez-Mato, J. M., 78, 82 Perezy Jorba, M., 113 Pe´rio, P., 329, 347, 348, 353, 355, 2392 Perkins, L. J., 2728 Perkins, M., 225 Perkins, W. T., 3047 Perlman, I., 5, 25, 817, 822, 1267, 1304, 1366, 1397, 1499, 1503, 1577, 1580, 1584, 1756, 1761, 2730 Perlman, J., 164 Perlman, M. L., 704, 822 Perlman, M. N., 194 Perminov, V. F., 1312, 1319 Perminov, V. P., 726, 748, 770, 1312, 1321, 1405, 1430, 1433, 2427, 2439, 2531, 2532, 3043, 3111, 3112, 3113, 3122, 3123 Permyakov, Yu. V., 793 Pernpointner, M., 1724, 1729 Pe´rodeaud, P., 352 Perrin, A., 544, 550, 551, 552, 555, 2556 Perrin, C., 435, 471 Perrin, D. D., 132, 597 Perrin, L., 1957 Perrin, R. E., 704, 789, 3014, 3312, 3314 Perrone, J., 128 Perry, G. Y., 817 Pershina, V., 185, 186, 213, 1447, 1516, 1524, 1549, 1652, 1662, 1664, 1668, 1670, 1671, 1672, 1673, 1674, 1675, 1676, 1677, 1678, 1679, 1680, 1681, 1682, 1683, 1684, 1685, 1686, 1687, 1688, 1689, 1691, 1693, 1698, 1700, 1701, 1704, 1705, 1706, 1707, 1708, 1709, 1711, 1712, 1713, 1714, 1716, 1718, 1894, 1933 Person, J. L., 535 Persson, B. R. R., 3296 Persson, G., 184, 2672, 2767 Persson, G. E., 1286 Persson, I., 118 Perutz, R. N., 2966 Peshkov, A. S., 1291 Petcher, D. J., 2423, 2425 Petcher, T. J., 201, 2420 Peter, E., 3364, 3365, 3376, 3379 Peterman, D. R., 1327, 2739 Peters, C., 2234

Peters, M. W., 2655 Peters, O. M., 541 Peters, R. G., 2491, 2850, 2922, 2995, 2996 Peters, T. B., 1401 Petersen, D. A., 3360, 3364, 3385 Petersen, J. L., 2919 Petersen, K., 2352 Petersilka, M., 1910 Peterson, D., 1737, 1738 Peterson, D. A., 316, 317 Peterson, D. E., 34, 892, 894, 911, 1003, 1004, 1009, 1011, 1017, 1523, 2115, 2116, 2117, 2120, 2149, 2208, 2209, 2210 Peterson, D. T., 29, 61, 64, 65, 66, 95 Peterson, E. J., 2677 Peterson, J., 1468 Peterson, J. R., 421, 502, 503, 519, 528, 757, 859, 953, 958, 971, 973, 974, 1077, 1084, 1093, 1096, 1133, 1295, 1312, 1315, 1324, 1325, 1326, 1328, 1329, 1341, 1357, 1358, 1365, 1366, 1397, 1403, 1410, 1411, 1412, 1414, 1415, 1417, 1419, 1420, 1421, 1424, 1444, 1445, 1446, 1451, 1452, 1455, 1456, 1457, 1458, 1459, 1460, 1462, 1463, 1464, 1465, 1466, 1467, 1468, 1469, 1470, 1473, 1474, 1477, 1479, 1480, 1481, 1482, 1483, 1485, 1513, 1515, 1519, 1520, 1521, 1522, 1524, 1525, 1527, 1528, 1529, 1530, 1531, 1532, 1533, 1534, 1538, 1539, 1540, 1542, 1543, 1544, 1545, 1547, 1548, 1555, 1558, 1559, 1562, 1579, 1588, 1590, 1593, 1595, 1596, 1598, 1599, 1600, 1601, 1604, 1605, 1606, 1612, 1840, 1875, 1877, 2017, 2077, 2124, 2127, 2129, 2131, 2153, 2154, 2155, 2163, 2174, 2182, 2186, 2238, 2269, 2270, 2271, 2272, 2315, 2370, 2388, 2389, 2397, 2398, 2411, 2413, 2414, 2416, 2417, 2420, 2422, 2490, 2565, 2580, 2688, 3047, 3321 Peterson, S., 27, 452, 572, 842 Peterson, S. W., 372, 373, 2431 Petiau, J., 3163 Petit, A., 1863, 1865, 1868, 1873 Petit, J. C., 3064, 3160 Petit, L., 1023, 1044, 2347, 3211 Petit, T., 389 Petley, B. W., 1653 Petrich, G., 2733 Petrov, K. I., 109, 114 Petrov, V. M., 1680, 1681 Petrova, V. N., 1680, 1681 Petryna, T., 1636, 2526 Petrynski, W., 338, 339 Petrzilova, H., 1278, 2653 Petteau, J. F., 2633

I-244

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Pettersson, H., 3017 Pettifor, D. G., 927 Pettke, T., 639, 3327 Petukhova, I. V., 1352 Peuser, P., 3044, 3047, 3048, 3320, 3321 Peycelon, H., 3305 Pezerat, H., 195, 196, 197, 216, 225, 230 Pfeil, P. C. L., 325 Pfiffelmann, J. P., 824 Pfitzer, F., 372, 373, 374, 375, 376, 377 Pfleiderer, C., 967, 2353 Pfrepper, G., 214, 217, 1695, 1700 Pfrepper, R., 1695, 1700 Phelps, C., 2684 Phelps, W. T., Jr., 3065 Philippot, J., 355 Phillipe, M., 1285 Phillips, A. G., 3234, 3255 Phillips, C. S. G., 1640 Phillips, D. H., 1908 Phillips, E. J. P., 3172, 3178 Phillips, G., 787, 3043, 3044 Phillips, G. M., 164, 173, 177, 180 Phillips, L., 5 Phillips, N. E., 2315 Phillips, T. L., 1507 Phipps, K. D., 1033, 1034, 2395 Phipps, T. E., 963, 1045, 1083, 1085, 1086 Piana, M. J., 3170 Pianarosa, P., 1873 Piboule, M., 3042, 3043 Picard, C., 353, 354, 362, 363 Picard, G., 2135, 2699, 2700 Piccard, A., 163 Picer, M., 3306 Pichot, E., 109 Pickard, C. J., 2265, 2293 Pickett, D. A., 189, 231, 3312, 3314 Pickett, G. R., 63, 2315, 2350 Picon, M., 414, 2413 Pidnet, J.-M., 1269 Piechowski, J., 3024 Piehler, D., 204, 2020, 2065, 2067, 2068, 2083, 2227 Piekarski, C., 274, 2392 Pierce, R. D., 2693, 2708, 2709, 2710, 2712, 2722, 2723 Pierce, W. E., 226 Pierloot, K., 1930 Piersma, B. J., 2686 Pietraszko, D., 2411 Pietrelli, L., 2633 Piguet, D., 1447, 1662, 1664, 1684, 1685, 1693, 1706, 1707, 1709, 1711, 1712, 1713, 1714, 1716, 1721 Pijunowski, S. W., 372, 373, 1045 Pikaev, A. K., 1117, 1118, 1338, 2127, 2527 Pilati, T., 261, 264

Pillai, K. T., 1033 Pillinger, W. L., 190, 793 Piltz, G., 510, 511 Pilv Vo, R., 1293 Pilz, N., 788 Pimpl, M., 3014 Pin, C., 3284, 3326 Pinard, J., 1874, 1875 Pingitore, N. E., Jr., 3162 Pinkerton, A. A., 2584 Pinkerton, A. B., 2642 Pinkston, D., 3200, 3252 Pinte, G., 782, 786, 3056, 3057 Pippin, C. G., 44, 615, 1473, 1474, 1475 Pires de Matos, A., 208, 1993, 2150, 2880, 2881, 2882, 2883, 2884, 2885, 2886, 2912 Pires de Matos, P., 1971 Piret, P., 259, 260, 261, 262, 263, 264, 265, 267, 282, 283, 288, 293 Piret-Meunier, J., 116, 260, 263, 264, 283 Pirie, J. D., 2275 Pirozkhov, S. V., 1428, 1449, 1483, 1554, 1605 Pirozov, S. V., 164, 166, 180, 1323, 1352 Pisaniello, D. L., 2584 Piskarev, P. E., 3024 Piskunov, E. M., 780, 1352, 1427, 3061 Pissarsjewski, L., 77 Pissot, A. M., 198, 225 Pitard, F., 632 Pitkanen, V., 3304 Pitman, D. T., 67 Pitner, W. R., 854, 2686, 2690 Pittman, E. D., 3137 Pitts, S. H., Jr., 3233, 3234 Pitzer, K. S., 753, 1683, 1689, 1727, 1728, 1898, 1900, 1907, 2538 Pitzer, R. M., 254, 577, 627, 763, 764, 1192, 1199, 1676, 1679, 1777, 1897, 1901, 1908, 1909, 1910, 1928, 1930, 1931, 1932, 1939, 1940, 1943, 1944, 1946, 1947, 1948, 1949, 1951, 1952, 1959, 1973, 2037, 2079, 2253, 2400, 2561, 2594, 2853, 2864 Pius, I. C., 1271 Pkhar, Z. Z., 1633, 1636 Plaisance, M. L., 215, 218 Plakhtii, V. P., 546 Plambeck, J. A., 2133, 2134 Planas-Bohne, F., 3354, 3397, 3398, 3399, 3400 Plancque, G., 3054 Plant, J., 270, 271 Plaschke, M., 3066 Platzner, I. T., 637, 3310, 3311, 3312, 3313 Plesek, J., 2655 Pleska, E., 739, 1055 Plesko, E. P., 293

Author Index

I-245

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Plesset, M. S., 1902 Plessy, L., 2731 Plettinger, H. A., 2439 Plews, M. J., 1190, 1191, 2472, 2475, 2817 Plissionier, M., 101 Ploehn, H. J., 1292, 2752 Plotko, V. M., 6 Pluchet, E., 220 Plu¨ddemann, W., 104 Plumer, M. L., 444 Plurien, P., 504, 505, 506, 507, 2243, 2246, 2449, 2452 Plutonium in the Environment, 3295 Plymale, A. E., 3180 Plyushcheva, N. A., 31 Poa, D. S., 2722, 2723 Poblet, J. M., 3143, 3145 Poblet, M. M., 1927 Pocev, S., 2531, 3101, 3105 Pochini, A., 2655 Poda, G. A., 1507 Podnebesnova, G. V., 539, 565 Podoinitsyn, S. V., 856 Podor, R., 109, 128, 602, 1172, 2431, 2432 Podorozhnyi, A. M., 1629, 2525 Podosek, F. A., 3159 Poettgen, R., 70, 73 Pohlki, F., 2982 Poinsot, R., 192 Poirot, I., 2261 Poliakoff, M., 2678 Polig, E., 3403 Pollard, F. H., 636 Pollard, P. M., 787, 3043, 3044 Polligkeit, W., 536 Pollmeier, P. G., 100 Pollock, E. N., 636 Polo, A., 2473 Polozhenskaya, L. P., 583, 601 Poluboyarinov, Y. V., 6 Polunina, G. P., 372, 373, 374, 375, 376, 384, 385 Polyakov, A. N., 14, 1398, 1400, 1653, 1654, 1707, 1719, 1736, 1738 Polyakova, M. Y., 986 Polynov, V. N., 822, 1398 Polyukhov, V. G., 1416, 1430 Polzer, W., 3017 Pomar, C., 3016, 3063 Pommer, A. M., 292 Pompe, S., 2568, 3102, 3135, 3138, 3140, 3141, 3142, 3145, 3147, 3149, 3150 Pomytkin, V. F., 1848 Ponader, C. W., 270, 276, 277 Poncet, J. L., 3117 Poncy, J. L., 3413, 3423 Ponomareva, O. G., 1126 Pons, F., 904

Poojary, M. D., 2442 Poole, D. M., 903, 904, 913 Poole, O. M., 892, 913 Poole, R. T., 520 Poon, S. J., 2351 Poon, Y. M., 501, 509, 523, 2016, 2036, 2081, 2082, 2083, 2245 Pope, M. T., 2584 Pope, R., 1071 Popeko, A. G., 6, 14, 164, 1653, 1654, 1701, 1713, 1717, 1719, 1720, 1735, 1737, 1738 Popik, M., 2177 Pople, J. A., 1902 Popov, D. K., 1178, 1352 Popov, M. M., 2168 Popov, S. G., 357, 1048, 1071, 1074, 1075, 1076, 1077 Popov, Y. S., 1504 Popov, Yu. S., 1446, 1447 Popovic, S., 103, 110 Poppensieker, K., 6, 1738 Popplewell, D. S., 1814, 1816, 3360, 3361, 3362, 3364, 3365, 3366, 3375, 3376, 3378, 3398 Porai-Koshits, M. A., 102, 105, 2434, 2439 Porcelli, D., 3288 Porcher, P., 113, 2044 Porchia, M., 2472, 2473, 2484, 2820, 2822, 2825, 2841, 2893, 2934 Porodnov, P. T., 2693, 2699, 2704, 2705 Porsch, D., 1071 Portal, A. J. C., 719, 721 Portanova, R., 767, 770, 776, 777, 778, 779, 781, 1178, 1180, 1181, 2550, 2554, 2584, 2585, 2586, 2589 Porter, C. E., 1508, 1511, 1585, 1623, 1624 Porter, F. T., 1626, 1627, 1634, 1639, 1644 Porter, J. A., 1312, 1422 Porter, M. J., 2256 Posey, J. C., 518 Poskanzer, A. M., 29, 184, 1111, 2662 Poskin, M., 32, 33 Pospelov, Yu. N., 3014 Post, B., 66, 2407 Postel, S., 3424 Potel, M., 75, 96, 97, 402, 407, 414, 415, 416, 417, 514, 516, 528, 2413, 2425 Potemkina, T. I., 745, 747, 749, 2434, 2436 Potter, P., 718, 719, 722, 726, 727, 728, 739, 744, 745, 767, 769, 771, 881, 888, 891, 989, 1008, 1019, 1021, 1045, 1047, 1048, 1085, 1086, 1087, 1098, 1100, 1101, 1110, 1111, 1117, 1118, 1131, 1147, 1148, 1149, 1150, 1155, 1157, 1158, 1162, 1167, 1169, 1170, 1171, 1180, 1181, 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2133, 2136, 2137,

I-246

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 2140, 2142, 2144, 2145, 2151, 2152, 2154, 2155, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2170, 2171, 2173, 2174, 2175, 2182, 2186, 2187, 2193, 2194, 2195, 2197, 2199, 2200, 2201, 2204, 2206, 2538, 2576, 2578, 2582, 2583, 3206, 3213, 3347 Potter, P. E., 367, 391, 997, 998, 1002, 1004, 1009, 1010, 1015 Potter, R. A., 1317, 1318 Potts, A. M., 3424 Poty, B., 3065 Potzel, U., 719, 720 Potzel, W., 719, 720, 2361 Poulet, H., 545 Poulsen, O., 1846, 1873 Poupard, D., 3312 Pourbaix, M., 3096 Povey, D. C., 1169 Povinec, P. P., 1806, 3017, 3031, 3032 Povondra, P., 3278 Powell, A. K., 545, 2442, 2447, 2448 Powell, D. H., 3110 Powell, E. W., 484, 560 Powell, F. W., 484 Powell, G. L., 3239 Powell, J. E., 63, 64, 65, 841 Powell, J. R., 854 Powell, R. E., 1898 Powell, R. F., 957 Powell, R. W., 322, 1593 Powell, T., 421 Power, P. P., 2980 Powietzka, B., 2255, 2808 Pozet, N., 1507 Pozharskii, B. G., 1099, 1100 Poznyakov, A. N., 1161, 1172 Pozo, C., 1285 Pozolotina, V. N., 3280 Prabhahara, R. B., 2205, 2206 Prabhu, D. R., 1285, 2657, 2658, 2736 Prasad, N. S. K., 2441 Prasad, R., 2157, 2158, 2209 Prater, W. K., 821 Pratopo, M. I., 768 Pratt, K. F., 1468 Prenger, C., 2752 Preobrazhenskaya, E. B., 3034 Prescott, A., 520 Prescott, C. H., 319 Presson, M. T., 1168, 1262, 1270, 2532 Preston, D. L. S., 1821 Preston, J. S., 1168 Preus, H., 2148 Preuss, H., 1676, 1679, 1908, 1918, 1920, 1937, 1943, 1944, 1947, 1949, 1951, 1959 Prewitt, C. T., 1463 Pribylova, G. A., 705, 2661

Price, C. E., 100 Price, D. L., 2232 Price, G. R., 3037 Priceman, S., 323 Prichard, W. C., 3223 Priest, N. D., 3173, 3317, 3318, 3403, 3405 Prigent, J., 372, 374, 376, 413, 551 Priibylova, G. A., 1283 Prikryl, J. D., 272, 301 Prince, E., 66 Prins, G., 373, 374, 375, 514, 525, 543, 544, 551, 552, 569, 2158, 2160, 2161, 2185 Prins, R., 3087 Pritchard, C. A., 3312, 3321 Pritchard, S. E., 1873 Pritchard, W. C., 1004, 1007, 3253, 3254 Privalov, T., 565, 577, 578, 595, 596, 606, 613, 619, 620, 622, 623, 1925, 2185, 2187, 2195 Probst, H., 83 Probst, T., 3057 Proceedings, 405, 420 Proctor, S. G., 1271, 1290 Prodic, B., 102, 108, 110, 2430, 2431, 2558 Prokryl, J. D., 272, 293 Propst, R. C., 1480, 1481, 1484 Propst, R. L., 1549 Prosser, C. L., 3353, 3356, 3362, 3366, 3370, 3378, 3386, 3395, 3407, 3424 Prosser, D. L., 1033 Proust, J., 792, 2443 Proux, O., 389 Provitina, O., 789 Provost, J., 2431, 2432 Prpic, I., 182 Pruett, D. J., 2688, 2690 Pruner, R. E., 3247, 3257, 3259 Prunier, C., 1269, 1285, 2756 Prusakov, V. N., 1312, 1315, 1327, 2421 Prussin, T. G., 3025 Pruvost, N. L., 821, 988 Pryce, M. H. L., 1915, 2080, 2227, 2239, 2241, 2243 Pryce, M. H. L. J., 765 Pryor, A. W., 2391 Przewloka, A., 1735 Przystawa, J. A., 2274 Ptackova, B. N., 1507 Puaux, J.-P., 2438, 2439 Pucci, R., 1994 Puchta, G. T., 3003 Pugh, E., 407, 2239, 2359 Pugh, R. A., 863 Pugh, W., 180 Puglisi, C. V., 3250, 3253, 3259 Puigdomenech, I., 211, 270, 590, 1146, 1158, 1159, 1314, 1328, 1329, 1330, 1338, 1339, 1341, 1354, 1355, 2114, 2115,

Author Index

I-247

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 2117, 2120, 2126, 2127, 2128, 2129, 2137, 2143, 2144, 2154, 2155, 2159, 2165, 2171, 2173, 2174, 2175, 2182, 2186, 2187, 2194, 2538, 2546, 2582, 2593 Pulcinelli, S. H., 90 Pullat, V. R., 3057 Pullen, F., 102, 110 Pulliam, B. V., 1840, 1847 Punyodom, W., 225 Purdue, W. M., 1049 Pursel, R., 2430 Purser, K. H., 3063, 3318 Purson, J. D., 1058, 1059, 1060, 1062, 3163 Purushotham, D. S. C., 182, 184 Purvis, G. D., 1902 Pushcharovsky, D. Y., 102, 109, 266, 268, 298 Pushlenkov, M. F., 1271 Pushparaja, 2669 Pustovalov, A. A., 817 Putnis, A., 286, 290 Puzzuoli, G., 1282, 2743 Pyle, G. L., 5, 1577, 1622 Pyper, N. C., 369, 1670, 1675, 1726, 1728 Pyykko¨, I., 576 Pyykko¨, P., 578, 792, 1666, 1669, 1670, 1675, 1723, 1726, 1729, 1873, 1894, 1898, 1899, 1913, 1916, 1917, 1933, 1939, 1940, 1941, 1942, 1943, 1948, 1969, 1976, 1978, 1993, 2400 Pyzhova, Z. I., 29, 30 Qian, C. T., 2831 Qin, Z., 1662, 1664, 1685, 1713, 1714, 1716 Qu, H., 3024, 3284, 3296 Quamme, G. A., 3357, 3381, 3383 Quarton, M., 103, 109, 110, 112, 2431, 2432 Quere, Y., 817 Quezel, J., 739 Quezel, S., 739 Quigley, M. S., 3024 Quijano-Rico, M., 3306 Quill, L. L., 700 Quimby, F. W., 3357, 3358 Quiney, H., 1670 Quiney, H. M., 1905 Quinn, B. M., 3126 Raab, W., 785 Raabe, O. G., 3254 Rabardel, L., 77 Rabbe, C., 2676 Rabe, P., 3117 Rabideau, S., 1088

Rabideau, S. W., 529, 530, 1111, 1117, 1118, 1119, 1120, 1121, 1123, 1126, 1128, 1129, 1131, 1132, 1133, 1134, 1135, 1144, 1145, 1146, 1149, 2580, 2599, 2601 Rabinovich, D., 117, 475, 495, 2827, 2868, 2869 Rabinovich, I. B., 2822 Rabinovitch, V. A., 1725 Rabinowitch, E., 255, 318, 328, 339, 340, 558, 629, 2160, 2167 Racah, G., 60, 1862, 1863, 1865, 1869, 2026, 2027 Radchenko, V., 1398, 1421 Radchenko, V. M., 1317, 1398, 1412, 1413, 1422, 1433, 1518, 1519, 1520, 1521, 1829 Ra¨de, D., 77 Rader, L. F., Jr., 3061 Radionova, G. N., 1448, 1449 Radkov, E., 3420 Radu, N., 2832 Radu, N. S., 2974 Radzewitz, H., 113, 1312, 1313 Radziemski, L. J., 2080 Radziemski, L. J., Jr., 1845, 1874, 1875, 1877 Rae, A. D., 546, 2429 Rae, H. K., 1080, 1086 Raekelboom, E., 298 Raetsky, V. M., 324 Rafaja, D., 338, 339 Rafalski, A. L., 958, 959, 960 Raff, J., 3179, 3181, 3182 Raffenetti, R. C., 1908 Raffy, J., 3016 Raftery, J., 2400 Ragan, V. M., 3159 Raghavachari, K., 1902 Raghavan, R., 772 Ragheb, M. M. H., 2734 Ragnarsdottir, K. V., 2191, 2192 Rahakrishna, P., 2392 Rahman, H. U., 2274, 2278, 2288 Rahman, Y. E., 1179 Rai, D., 125, 126, 127, 128, 130, 131, 728, 767, 768, 769, 1149, 1160, 1162, 1179, 1319, 1341, 2192, 2546, 2547, 2549, 2592, 3039, 3134, 3135, 3136, 3137, 3247 Rai, H. C., 86, 91 Raich, B., 319 Raimbault, L., 3305 Raimbault-Hartmann, H., 1735 Rainey, R. H., 188, 1151, 2735 Rainey, R. N., 2735 Rais, J., 1283, 2655 Raison, E. P., 1531, 1532 Raison, P., 2250 Raison, P. E., 1398, 1467

I-248

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Raj, D. D. A., 1074 Raj, P., 339 Raj, S. S., 2452, 2453, 2455 Rajagopalan, M., 63, 100 Rajagopalan, S., 396 Rajan, K. S., 2587 Raje, N., 180 Rajec, P., 3017 Rajendra, S., 1275 Rajnak, K., 203, 482, 491, 1099, 1588, 1590, 1845, 1852, 1862, 1868, 1878, 1879, 2016, 2029, 2030, 2032, 2038, 2042, 2044, 2049, 2055, 2056, 2065, 2066, 2074, 2090, 2091, 2093, 2095, 2251, 2261 Rakhmanov, Z., 1507 Rakovan, J., 3087, 3170 Ralph, J., 357 Ralston, L., 3354, 3378 Ralston, L. G., 3345, 3354, 3355, 3371, 3378, 3384 Rama Rao, G. A., 182, 184 Ramadan, A., 184 Ramakrishna, V. V., 182, 772, 773, 774, 1168, 1170, 2579 Ramamurthy, P., 101 Raman, V., 77 Ramaniah, M. V., 40, 41 Ramanujam, A., 712, 713, 1281, 1282, 1294, 2668, 2669, 2743, 2744, 2745, 2747, 2749, 2750, 2757, 2759 Ramaswami, D., 1082 Ramdoss, K., 3308 Rameback, H., 1432, 1434 Ramirez, A. P., 942, 944, 948 Rammelsberg, C., 75 Ramos, A. F., 3057 Ramos Alonso, V., 93 Ramos, M., 942, 944, 945, 948, 965, 966, 967, 984 Ramos-Gallardo, A., 2407, 2408 Ramounet, B., 3352, 3359, 3364, 3368, 3377, 3398, 3399 Ramsay, D. A., 1981 Ramsay, J. D. F., 3064, 3103, 3152, 3154, 3155 Ramsey, J. D. F., 301 Ramsey, K. B., 851 Ramsey, W. J., 910 Rana, R. S., 2016, 2030, 2038, 2044 Rananiah, M. V., 2579 Rance, P., 1145 Rand, M., 421, 423, 425, 435, 439, 440, 441, 457, 458, 469, 473, 474, 477, 478, 480, 481, 497, 502, 503, 509, 513, 514, 515, 516, 517, 536, 538, 543, 544, 545, 551, 552, 556, 593, 594, 595, 596, 597, 598, 599, 601, 602, 603, 3206, 3213 Rand, M. H., 53, 61, 67, 68, 69, 74, 100, 270, 321, 322, 325, 326, 351, 352, 353, 362,

364, 398, 400, 401, 402, 405, 406, 407, 425, 435, 469, 478, 486, 497, 502, 516, 718, 719, 722, 726, 727, 728, 739, 744, 745, 767, 769, 771, 881, 888, 890, 891, 945, 949, 963, 989, 1004, 1008, 1019, 1021, 1028, 1030, 1045, 1046, 1047, 1048, 1069, 1085, 1086, 1087, 1098, 1100, 1101, 1110, 1111, 1117, 1118, 1131, 1147, 1148, 1149, 1150, 1155, 1157, 1158, 1159, 1160, 1161, 1162, 1165, 1166, 1167, 1169, 1170, 1171, 1180, 1181, 1297, 1298, 1314, 1328, 1329, 1330, 1338, 1339, 1341, 1354, 1355, 1403, 1409, 1410, 1417, 2114, 2115, 2116, 2117, 2120, 2126, 2127, 2128, 2129, 2132, 2133, 2136, 2137, 2138, 2140, 2142, 2143, 2144, 2145, 2149, 2151, 2152, 2153, 2154, 2155, 2157, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2170, 2171, 2173, 2174, 2175, 2176, 2179, 2181, 2182, 2186, 2187, 2190, 2191, 2192, 2193, 2194, 2195, 2196, 2197, 2198, 2199, 2200, 2201, 2203, 2204, 2205, 2206, 2207, 2208, 2209, 2538, 2546, 2554, 2576, 2578, 2582, 2583, 3347 Randall, C. H., 198 Randles, S. R., 3244 Randrup, J., 1661 Rangaswamy, R., 3308 Rangelov, R., 3027 Rankin, D. T., 3265 Rannou, J. P., 2422 Rao, C. L., 40, 41, 42 Rao, C. R. V., 339 Rao, G. S., 1174 Rao, L., 1341, 1363, 1370, 2568, 3102, 3142, 3143, 3145 Rao, L. F., 772, 1155, 1164, 2553, 2558, 2561, 2571, 2574, 2578, 2589, 2594, 2595, 2602 Rao, M. K., 1282, 2743, 2744, 2745 Rao, P. M., 60, 1452, 1875, 1877 Rao, P. R. V., 396, 772, 773, 774, 840, 1076, 1168, 2649 Rao, R. S., 2370 Rao, V. K., 40, 41, 1352 Raphael, G., 2288, 2289 Rapin, M., 904, 955 Rapko, B. M., 1278, 1280, 1283, 2573, 2653, 2656, 2660, 2737, 2738 Rapp, G. R., 259, 260, 262, 263, 266, 267, 269 Rapp, K. E., 518 Raschella, D. L., 1424, 1524, 1527 Rasilainen, K., 273 Rasmussen, J. J., 1303, 1312 Rasmussen, M. J., 1093 Raspopin, S. P., 86, 93, 2715

Author Index

I-249

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Rastogi, R. C., 3017 Rastsvetaeva, R. K., 266 Rateau, G., 1819 Ratherton, D., 3396, 3401, 3405 Ratho, T., 466 Ratmanov, K. V., 1145, 1146 Ratsimandresy, Y., 3037 Rattray, W., 3025 Rau, W., 3397, 3399 Raub, E., 63 Rauchfuss, T. B., 2837 Rauchle, R. F., 64 Raudaschl-Sieber, G., 3003 Raue, D. J., 1081 Rauh, E. G., 60, 63, 70, 75, 322, 352, 364, 365, 724, 2147, 2148, 2380, 2391 Rauschfuss, T. B., 2480, 2481, 2482 Ravagnan, J., 3069 Ravat, B., 933 Raveau, B., 2431, 2432 Ravenek, W., 1907 Ravn, H. L., 1735 Rawson, R. A., 3358 Ray, A. K., 1018, 1976, 1989, 1994, 2149 Ray, C. S., 277 Raymond, C. C., 412 Raymond, D. P., 131, 132 Raymond, K., 2591 Raymond, K. N., 116, 1168, 1188, 1813, 1815, 1819, 1823, 1824, 1825, 1943, 1944, 2471, 2472, 2473, 2474, 2478, 2479, 2486, 2488, 2491, 2591, 2669, 2816, 2819, 2820, 2830, 2832, 2852, 2853, 2868, 2919, 3340, 3343, 3349, 3359, 3364, 3365, 3366, 3369, 3375, 3376, 3378, 3379, 3382, 3385, 3388, 3389, 3390, 3391, 3394, 3409, 3413, 3414, 3415, 3416, 3417, 3418, 3419, 3420, 3421, 3422, 3423 Raynor, G. V., 98 Raynor, J. B., 976 Razbitnoi, V. L., 1320 Razbitnoi, V. M., 1323, 1352, 1402, 1422, 1423 Reader, J., 857, 1513, 1633, 1639, 1646, 1841 Readey, D. W., 1031 Reas, W. H., 837 Reavis, J. G., 717, 1004, 1009, 1077, 1093, 1095, 1104, 2709, 2713 Rebel, H., 1873 Rebenko, A. N., 539, 542 Rebizant, J., 65, 66, 69, 73, 97, 102, 108, 192, 204, 207, 334, 335, 409, 412, 431, 451, 470, 552, 553, 719, 720, 722, 723, 724, 725, 739, 741, 744, 792, 861, 863, 967, 968, 994, 995, 1009, 1012, 1015, 1016, 1019, 1023, 1033, 1034, 1050, 1052, 1055, 1056, 1168, 1304, 1318, 1754, 1784, 1790, 2135, 2188, 2189, 2237,

2239, 2249, 2250, 2255, 2283, 2284, 2285, 2286, 2287, 2289, 2290, 2292, 2347, 2352, 2353, 2359, 2370, 2372, 2381, 2403, 2404, 2407, 2411, 2441, 2469, 2470, 2471, 2472, 2474, 2475, 2476, 2477, 2478, 2479, 2484, 2486, 2488, 2489, 2490, 2808, 2814, 2815, 2816, 2817, 2818, 2819, 2827, 2829, 2882 Recker, K., 372 Recrosio, A., 1022 Reddon, G., 3165, 3168 Reddy, A. K. D., 2538 Reddy, A. S., 182 Reddy, A. V. R., 182, 184 Reddy, J. F., 743, 1022 Reddy, S. K., 182 Redey, L., 2723 Redfern, C. M., 1200, 1202, 1949, 2561, 2854 Redhead, P. A., 60 Rediess, K., 505, 509, 510, 543 Redman, J. D., 1104 Ree, T., 367 Reed, D., 3039 Reed, D. T., 861, 1148, 1155, 1172, 1813, 1814, 1818, 1930, 1991, 2536, 2668, 3034, 3037, 3043, 3044, 3095, 3113, 3118, 3175, 3177, 3179, 3181, 3182 Reed, D. T. R., 2096 Reed, W. A., 2360, 3165, 3169 Reeder, R. J., 291, 3131, 3159, 3160, 3161, 3164, 3170 Reedy, G. T., 356, 366, 1018, 1029, 1971, 1972, 1976, 1988, 2148, 2149, 2203 Rees, T. F., 2650 Reese, L. W., 1270 Regalbuto, M. C., 2655, 2738, 2739 Regel, L. L., 749, 2442 Rehfield, C. E., 3343 Rehka¨mper, M., 639, 3327 Rehklau, D., 1875, 1876 Rehner, T., 82, 83 Rehr, J. J., 1112, 1991, 2858, 3087, 3089, 3090, 3103, 3108, 3113, 3117, 3118, 3123, 3170 Rehwoldt, M., 1190 Reich, T., 118, 289, 389, 580, 589, 596, 602, 612, 616, 621, 626, 795, 1112, 1113, 1156, 1166, 1921, 1923, 1933, 2531, 2532, 2568, 2576, 2580, 2582, 2583, 2812, 3046, 3089, 3101, 3102, 3106, 3107, 3111, 3112, 3113, 3117, 3118, 3119, 3121, 3122, 3125, 3126, 3127, 3128, 3129, 3130, 3131, 3132, 3135, 3138, 3139, 3140, 3141, 3142, 3143, 3144, 3145, 3146, 3147, 3148, 3149, 3150, 3152, 3154, 3155, 3156, 3160,

I-250

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 3161, 3165, 3166, 3167, 3179, 3180, 3181, 3182, 3381, 3382 Reichert, W. M., 2691 Reichl, J., 2966 Reichlin, R., 1300 Reichlin, R. L., 1403, 1410, 1411, 1412 Reich-Rohrwig, W., 3029 Reid, A. F., 116 Reid, M. F., 422, 483, 486, 1113, 2020, 2031, 2044, 2051, 2054, 2067, 2068, 2069, 2070, 2072, 2089, 2091, 2099 Reihl, B., 2336, 2338, 2359 Reilly, J. J., 338 Reilly, S. D., 861, 1112, 1148, 1155, 1166, 1178, 1179, 1824, 3035, 3106, 3109, 3113, 3115, 3123, 3133, 3134, 3210 Reilly, S. P., 1138, 1179 Reilly, S. R., 1116, 1117 Reimann, T., 1352 Reiners, C., 1828 Reinhard, P. G., 1736 Reinhardt, H., 2757 Reinhoudt, D. N., 597 Reis, A. H., Jr., 372, 373 Reisdorf, W., 6, 1660, 1738 Reisfeld, M. J., 763, 765, 1356, 1365, 1475, 1513, 1515, 1604, 2076, 2082, 2241 Reisfeld, R., 1894, 1916 Reishus, J. W., 1046 Reiss, G. J., 2479, 2834 Reissmann, U., 2852 Reitmeyer, R., 3165, 3167 Reitzik, M., 3357, 3381, 3383 Rekas, K., 1507 Rekas, M., 1352, 1431 Remaud, P., 43 Remy, M., 1963, 1965 Rendl, J., 1828 Renkin, J. M., 2815 Renshaw, J. C., 589, 2441 Rentschler, H. C., 61, 80 Repnow, R., 33, 1880, 1881, 1882, 1883, 1884 Reshetnikov, F. G., 1028 Reshetov, K. V., 373, 375 Reshitko, S., 14, 1653, 1713, 1717 Ressouche, E., 475, 476, 495, 719, 720, 2352 Reul, J., 34, 35, 191, 1271, 1297, 1402, 1403, 1410, 1412, 1413, 1417, 1424, 2696, 2700 Reul, R., 1403, 1411 Reusser, E., 279 Reuter, H., 407 Revel, R., 1168, 1262, 1270, 3101, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118 Revenko, Y. A., 856 Revy, D., 789 Rexer, J., 64 Reymond, F., 172 Reynolds, C. T., 205

Reynolds, D. A., 2760 Reynolds, F. L., 319 Reynolds, J. G., 2256, 2558, 2819 Reynolds, J. H., 824 Reynolds, L. T., 630, 1189, 1800, 1952, 2799, 2815 Reynolds, M. B., 485 Reynolds, R. W., 1472, 1602, 2266, 2268, 2272, 2292 Reynolds, S. A., 164, 169, 225, 226 Reznikova, V. E., 1095, 1100 Reznutskij, L. R., 2114, 2148, 2149, 2185 Rhee, D. S., 1352, 1354, 2591, 3022 Rheingold, A. L., 1965, 2849, 2974 Rhinehammer, T. B., 487 Rhodes, L. F., 1363, 1954, 1956, 1957 Rhodes, R., 2628, 2629, 2692 Rhyne, J. J., 66 Rhyne, L. D., 2851 Rhys, A., 2068, 2089 Ribas Bernat, J. G., 93 Ricard, L., 2491, 2869, 2870 Rice, R. W., 998 Rice, W. W., 1088, 1090 Richard, C. E. F., 737 Richards, D. A., 3313 Richards, E. W. T., 190, 226 Richards, R. B., 530, 2730 Richards, S. M., 1002 Richardson, A. E., 29 Richardson, F. S., 2051, 2067 Richardson, J. W., 719, 721, 939, 941, 942, 1419, 2397 Richardson, J. W., Jr., 457, 486, 882, 2233, 2264, 2293 Richardson, N. L., 3254 Richardson, N. V., 1681 Richardson, R. P., 2261 Richardson, S., 2584 Richman, I., 2067 Richmann, M. K., 861 Richter, J., 2469 Richter, K., 724, 726, 988, 2407 Richter, M., 2359 Rickard, C. E. F., 108, 115, 200, 201, 204, 205, 208, 527, 2418 Rickert, P. G., 1279, 1281, 2652, 2655, 2691, 2738, 2747, 2750 Ricketts, T. E., 2749, 3219, 3220, 3253, 3254, 3262 Ridgeliy, A., 226 Rieder, R., 1398, 1421, 1433, 3306 Riefenberg, D. H., 958, 959, 960 Riegel, J., 60, 789, 1296, 1403, 1452, 1875, 1876, 1877 Rieke, R. D., 2851 Rienstra-Kiracofe, J. C., 1973 Rieth, U., 1735

Author Index

I-251

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Rietschel, A., 64 Rietveld, H. M., 373, 375, 376, 392, 2381, 2383, 2397 Rietz, R. R., 208, 1187, 2404, 2405 Rigali, L., 1284 Rigali, M. J., 3172 Rigato, V., 3065, 3069 Riggle, K., 786 Riglet, C., 775, 789, 1161, 3099 Riglet, Ch., 753, 756 Rigny, P., 504, 505, 506, 560, 2243, 2246, 2251, 2449, 2450, 2603, 2855, 3101, 3105, 3120, 3138, 3141 Rigol, J., 1653, 1719 Riha, J., 1106 Rijkeboer, C., 2381 Riley, B., 1045 Riley, F. D., 1508, 1511, 1585 Riley, F. D., Jr., 1623, 1624 Riley, P. E., 3416, 3419 Rimke, H., 1875, 1876, 3044, 3047, 3048, 3320, 3321 Rimmer, B., 115 Rimsky, A., 102, 103, 109, 111, 112, 131, 587, 588, 2427 Rimsky, H., 103, 110 Rin, E. A., 1545 Rinaldi, P. L., 2565, 2566 Rinaldo, D., 2458 Rinehart, G. H., 817, 818, 819, 963, 1033, 1058, 1059, 1060, 1062 Rink, W. J., 3033 Rios, E. G., 2442 Rioseco, J., 3017 Riou, M., 27 Ripert, M., 389, 861 Riseberg, L. A., 2086, 2095, 2096 Riseborough, P. S., 2343, 2344, 2345 Ritchey, J. M., 2484, 2891 Ritchie, A. G., 3244 Ritger, P. L., 2451, 2452 Ritter, G. L., 1275 Ritter, J. A., 1292, 2752 Rittmann, B. E., 1813, 1814, 1818, 2668, 3179, 3181, 3182 Rivard, M. J., 1507, 1518, 1829 Rivera, G. M., 1670, 1672, 1673, 1674, 1675, 1685, 1874 Rivers, M., 3089, 3172, 3175, 3176, 3177, 3183 Rivers, M. L., 270, 861, 3039 Rivie`re, C., 576 Riviere, E., 2254 Rizkalla, E. N., 776, 777, 778, 779, 781, 2443, 2529, 2537, 2546, 2548, 2558, 2559, 2562, 2563, 2564, 2565, 2566, 2570, 2571, 2574, 2585, 2589 Rizvi, G. H., 772, 1281, 1282, 2745, 2747 Rizzo da Rocha, S. M., 410

Rizzoli, C., 763, 765 Roach, J., 822, 823, 3279, 3314 Robbins, D. A., 2208 Robbins, J. L., 871, 949, 950, 1021, 1956, 2806 Robbins, R. A., 856 Robel, W., 1323 Robert, F., 103, 112 Robert, F. J., 103, 110 Robert, J., 166 Roberts, A. C., 103, 113 Roberts, C. E., 119, 120, 121, 123, 124, 2548, 2549 Roberts, E., 3354 Roberts, Emma, xvi Roberts, F. P., 1011, 1268, 1290, 1291 Roberts, J. A., 939, 941, 942, 962, 984 Roberts, J. T., 484 Roberts, K. E., 1114, 3025, 3043 Roberts, L. E. J., 195, 196, 226, 340, 353, 354, 356, 360, 362, 390, 2391, 3214 Roberts, M. M., 588, 2434 Roberts, R. A., 1138, 2726 Roberts, S., 457, 486 Roberts, W. L., 259, 260, 262, 263, 266, 267, 269 Robertson, D. E., 3022 Robertson, J. L., 929 Robins, R. G., 343 Robinson, B., 3346 Robinson, B. A., 3106 Robinson, H. P., 1098, 1101 Robinson, H. R., 3253, 3254 Robinson, P. S., 1184 Robinson, R. A., 333, 2289, 2290 Robinson, T., 225 Robinson, V. J., 3022 Robison, T. W., 2633, 2634 Robouch, P., 753, 756, 1159, 1160, 1161, 1165, 1166, 3099 Robouch, P. B., 1159, 1314, 1328, 1329, 1330, 1338, 1339, 1341, 1354, 1355, 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2129, 2137, 2143, 2144, 2154, 2155, 2159, 2165, 2171, 2173, 2174, 2175, 2182, 2186, 2187, 2194, 2538, 2546, 2582 Roche, M. F., 164 Rochicoli, F., 3066 Rodchenko, P. Y., 1126 Rodden, C. J., 632 Roddy, J. W., 1303, 1304, 1312, 1314, 1317, 1318, 2404, 2411, 2413 Rodehu¨ser, L. R., 618 Roden, B., 62 Rodgers, A. L., 549, 2439 Rodgers, S. J., 3413, 3414, 3416, 3418, 3419, 3421 Rodier, N., 542, 547

I-252

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Rodinov Yu, F., 164, 166 Rodionov, V. F., 26 Rodionova, I. M., 185 Rodionova, L. M., 29, 30, 1448, 2668 Rodrigues de Aquino, A., 410 Rodriguez de Sastre, M. S., 355 Rodriguez, M., 1432, 1433 Rodriguez, R. J., 719, 721 Roe, S. M., 2440 Roehler, J., 3117 Roell, E., 63, 64 Roemer, K., 713 Roensch, F., 822, 823, 3279, 3314 Roensch, F. R., 789, 3133, 3279, 3280, 3282, 3314 Roentgen, W. C., 1654 Roepenack, H., 839, 852, 1070, 1071, 1073, 1074 Roesch, D. L., 903 Roesky, H. W., 2472, 2875 Roesky, P. W., 1943, 2924, 2984, 2986 Roessli, B., 2239, 2352 Rofer, C. K., 3263 Rofidal, P., 930, 932, 954 Rogalev, A., 2236 Rogers, F. J. G., 164, 166, 173, 180, 224 Rogers, J. J. W., 3014 Rogers, L. M., 2469 Rogers, N. E., 487 Rogers, R. D., 421, 580, 595, 620, 621, 854, 1110, 1156, 1925, 1926, 1956, 2380, 2451, 2452, 2453, 2454, 2469, 2589, 2590, 2607, 2666, 2675, 2686, 2691, 2803, 2806, 2807, 3126, 3127, 3128 Rogl, P., 67, 68, 69, 71, 406, 997, 998, 1002, 2362, 2407, 2408 Rogova, V. P., 259 Rogowski, J., 1665 Rogozina, E. M., 1178, 1352 Rohac, J., 1654, 1719, 1720, 1735 Rohr, D. L., 986 Rohr, L. J., 962 Rohr, W. G., 962, 963 Rojas, R., 2441, 2442 Rojas, R. M., 2439, 2440, 2441, 2443 Rojas-Herna´ndez, A., 3023 Rokop, D., 822, 823, 3279, 3314 Rokop, D. J., 3014, 3069, 3288, 3314 Roll, W., 55 Rolland, B. L., 1054 Rollefson, G. K., 104, 857 Roller, H., 377 Rollin, S., 2650 Ro¨llin, S., 3068 Rollins, A. N., 2452, 2453, 2454 Rolstad, E., 352 Romanov, A., 1821 Romanov, G. A., 2579

Romanov, S. A., 1821, 3282 Romanovski, V., 3419 Romanovski, V. V., 1168, 2591 Romanovskii, V. N., 856, 2682, 2684, 2739 Ro¨mer, J., 3066 Romer, K., 2756 Romero, A., 2407, 2408 Romero, J. A. C., 2982 Ron, A., 469, 491 Rona, E., 224, 621 Roncari, E., 2585 Ronchi, C., 347, 353, 357, 359, 1029, 1033, 1036, 1045, 1047, 1077, 1971, 2139, 2140, 2148, 2149, 2388, 2392, 3212 Ronchi, R., 2149 Rondinella, V., 3070 Ronen, Y., 1447 Ronesch, K., 3061 Roof, R. B., 457, 903, 906, 909, 910, 911, 912, 976, 977, 989, 1061, 1067, 1084, 1107, 1109, 1300, 2407, 2408 Roof, R. B., Jr., 1012, 1013, 1027 Rooney, D. M., 393 Rooney, D. W., 854, 2686, 2690 Rooney, T. A., 1968, 1971 Roos, B. O., 576, 589, 595, 596, 1897, 1909, 1910, 1927, 1928, 1929, 1972, 1973, 1974, 1975, 1979, 1989, 1990, 1994, 1995 Roozeboom, H. W. B., 101, 104 Rosan, A. M., 2943 Rosber, A., 1923 Ro¨sch, F., 776, 1352, 1479, 3101, 3102, 3111, 3112, 3113, 3114 Ro¨sch, N., 1906, 1918, 1919, 1920, 1921, 1923, 1925, 1931, 1935, 1937, 1938, 1943, 1946, 1948, 1949, 1951 Rose, R. L., 939, 940, 949, 950, 1297 Roselli, C., 3030 Rosen, A., 576, 1671, 1677, 1680, 1682, 1916, 1933 Rosen, M., 936, 943, 944 Rosen, R. K., 2246, 2247, 2473, 2805, 2809, 2810 Rosen, S., 1003, 1009 Rosenberg, R. J., 3304 Rosenblatt, G. M., 1653, 1654 Rosenblum, M., 1952 Rosenfeld, T., 817 Rosengren, A., 63, 1460, 1515, 1517, 1626, 1634, 1639 Rosenheim, A., 82, 90, 93, 105, 109 Rosenkevitch, N. A., 1547, 1548 Rosenthal, M. W., 487, 1179, 1823, 2632, 3387, 3388, 3413, 3424 Rosenzweig, A., 78, 86, 88, 90, 91, 92, 259, 261, 262, 263, 264, 265, 266, 267, 268, 269, 275, 451, 458, 461, 464, 465, 488,

Author Index

I-253

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 504, 505, 506, 507, 734, 1398, 1417, 1418, 1468, 2415 Rosethal, U., 2927 Roshalt, J. N., 170 Rosner, G., 784 Rosoff, B., 3413 Ross, J. W., 2283 Ross, M., 265, 2434 Ross, R., 2701 Ross, R. B., 1671, 1898, 1908, 1918, 1920 Ross, R. G., 1451, 1509, 1584 Rossat-Mignod, J., 719, 720, 739, 744, 1055, 2275, 2409 Rossbach, H., 1683 Rossberg, A., 589, 596, 602, 612, 616, 621, 2582, 3102, 3106, 3107, 3111, 3112, 3119, 3121, 3122, 3139, 3140, 3147, 3148, 3149, 3179, 3180, 3181, 3182 Rossel, C., 2352, 2357 Rosser, R., 3062 Rossetto, G., 452, 2472, 2473, 2484, 2801, 2820, 2825, 2841 Rossetto, R., 2819, 2824 Rossi, R., 2479 Rossini, F. D., 2114 Rossini, I., 596, 3102, 3119, 3121 Rossotti, F. J. C., 209 Rossotti, F. J. R., 589, 598 Rossotti, H., 209, 589, 598 Rotella, F. J., 457, 486 Rotenberg, M., 2027, 2040 Roth, R. S., 377, 1067 Roth, S., 1957, 2472, 2479, 2825, 2826, 2919 Roth, W., 1423, 2801 Roth, W. L., 344 Rothe, J., 1147, 1150, 1152, 1153, 1154, 3103, 3104, 3129, 3138, 3149, 3158 Rothe, R. E., 988 Rothschild, B. F., 106, 107 Rothstein, A., 3354, 3359, 3362 Rothwarf, F., 63 Rotmanov, K. V., 1144, 1145 Roudaut, E., 1019 Rough, F. A., 325, 408 Rough, F. H., 325 Roult, G., 467 Rouquette, H., 2655 Rourke, F. M., 824, 1804, 3016, 3022, 3276 Rouse, K. D., 2391 Rouski, C., 1738 Rousseau, D., 2916 Roussel, P., 575, 1962, 1963, 1964, 2887, 2888 Roux, C., 904, 955 Roux, J., 3065 Roux, M. T., 281 Rouxel, J., 96, 415 Rowe, M. W., 3276 Rowland, H. G., 3353, 3402

Rowland, R. E., 3403, 3404, 3407 Rowley, E. L., 988, 1049 Roy, J. J., 717, 1270, 2134, 2135, 2695, 2696, 2697, 2698, 2699, 2700, 2715, 2719, 2721 Roy, R., 77 Roy, S., 1447 Rozanov, I. A., 416, 419 Rozen, A. M., 108, 705, 709 Rozenberg, G., 3065 Rozenkevich, N. A., 1607, 1629, 1636 Rozov, S. P., 1113, 1133, 1156 Ruban, A. V., 928 Ruben, H., 2386, 2434, 2436 Ruben, H. W., 2405 Rubenstone, J. L., 3056 Rubini, P., 608, 609, 2533, 2603, 3102, 3112 Rubini, P. R., 618 Rubinstein-Auban, A., 539 Rubio Montero, M. P., 3017, 3022 Rubisov, V. N., 1169 Ruby, S. L., 1297, 2292 Ruch, W. C., 316, 317 Rucklidge, J. C., 3318 Rudenko, N. P., 184 Rudigier, H., 2333 Rudnick, R. L., 3047 Rudnitskaya, A. M., 3029 Ru¨dorff, W., 372, 373, 374, 375, 376, 377, 378, 382, 384, 385, 386, 388, 389, 391, 392, 393, 523 Rudowicz, C., 730 Rudzikas, Z., 1862 Ruedenauer, F., 3173 Ruehle, A. E., 303, 315, 317, 319, 559, 560 Ruf, M., 555 Ruff, O., 61 Rufinska, A., 2837, 2841 Rugel, G., 3016, 3063 Ruggiero, C. E., 1110, 1138, 1179, 1824, 2590 Ruh, R., 113 Ruikar, P. B., 182, 184, 708, 1281, 2747, 2748 Ruiz, J., 2966 Rulli, J. E., 353, 368, 369 Rumer, I. A., 28, 38, 220, 221, 1113, 1402, 1547, 1548, 1606, 1607, 1608, 1624, 1629, 1636, 2525, 2700 Rumer, I. A. R., 221 Rumyantseva, Z. G., 185 Runciman, W. A., 2067, 2274, 2278, 2288 Rundberg, R. S., 1152, 3036, 3175 Rundberg, V. L., 1132 Runde, W., 595, 704, 932, 1041, 1043, 1148, 1154, 1155, 1156, 1164, 1166, 1173, 1174, 1175, 1312, 1314, 1319, 1327, 1332, 1338, 1340, 1341, 1359, 1360, 1365, 1366, 1368, 1369, 1370, 1803, 1927, 1928, 3035, 3037, 3087, 3106,

I-254

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 3108, 3109, 3112, 3113, 3115, 3118, 3123, 3125, 3133, 3134, 3210 Runde, W. H., 861, 1112, 1116, 1117, 1166, 1181, 2452, 2453, 2454, 2455, 2456 Rundle, R. E., 63, 64, 65, 67, 70, 71, 329, 330, 334, 335, 339, 399, 407, 2232, 2402, 2403, 2408, 2411 Rundloef, H., 475, 478, 479, 495 Rundo, J., 3355, 3366 Runeberg, N., 1933, 1969 Runeberg, N. J., 578 Runnalls, O. J. C., 423, 444, 900, 901, 902, 903, 905, 908, 909, 1011, 1012, 1015, 1066, 1304, 2407 Rupert, G. N., 97 Rush, R. M., 770 Rushford, M. A., 1873 Russell, A. D., 3159 Russell, A. S., 162, 187, 226 Russell, D. R., 536, 539 Russell, E., 3353, 3356, 3362, 3366, 3370, 3378, 3386, 3395, 3407, 3424 Russell, L. E., 1004, 1008, 1058, 1059, 1060, 1062, 1065, 1066, 1067, 1070 Russell, M. L., 1262, 1270, 2761 Russo, M., 1947, 1958 Russo, R. E., 1114, 1148, 1155, 1160, 1163, 2583 Ruster, W., 1875, 1876, 3044, 3047, 3048, 3320, 3321 Rustichelli, F., 65, 66, 334, 335, 994, 995, 1019, 2283, 2292 Rutgers van der Loeff, M., 3046 Rutgers van der Loeff, M. M., 44 Rutherford, E., 3, 19, 20, 254 Ru¨thi, M., 3283 Rutledge, G. P., 563 Rutsch, M., 3139 Ruzic Toros, Z., 103, 110 Ruzicka, J., 3285 Ryabinin, M., 1398, 1421 Ryabinin, M. A., 1317, 1398, 1412, 1413, 1433 Ryabov, A. D., 3002 Ryabova, A. A., 1129, 1140, 1337 Ryan, A. D., 312 Ryan, J. L., 38, 118, 125, 126, 127, 130, 310, 312, 728, 767, 768, 769, 847, 848, 849, 1049, 1104, 1149, 1290, 1312, 1315, 1328, 1329, 1409, 1410, 1424, 1446, 1479, 1480, 1481, 1482, 1526, 1529, 1546, 1547, 1548, 1555, 1557, 2082, 2083, 2192, 2542, 2546, 2547, 2558, 2580, 3247 Ryan, R. R., 78, 86, 87, 88, 90, 91, 92, 259, 261, 451, 458, 461, 464, 465, 466, 488, 497, 501, 502, 504, 505, 506, 507, 508, 512, 513, 515, 516, 517, 519, 520, 521,

524, 526, 527, 528, 536, 734, 1398, 1417, 1418, 1468, 1959, 2415, 2420, 2426, 2452, 2471, 2472, 2480, 2481, 2482, 2484, 2487, 2488, 2573, 2677, 2801, 2807, 2832, 2837, 2856, 2857, 2891, 3163 Ryan, V. A., 209, 214, 215, 217, 218, 2578 Ryazanova, L. A., 3067 Ryba-Romanowski, W., 422 Rybka, R., 263 Rycerz, L., 476, 478, 2185, 2186, 2187 Rydberg, J., 209, 218, 220, 223, 718, 719, 722, 726, 727, 728, 739, 744, 745, 767, 769, 771, 881, 888, 891, 989, 1008, 1019, 1021, 1045, 1047, 1048, 1085, 1086, 1087, 1098, 1100, 1101, 1110, 1111, 1117, 1118, 1131, 1147, 1148, 1149, 1150, 1155, 1157, 1158, 1162, 1167, 1169, 1170, 1171, 1180, 1181, 1687, 1761, 1764, 1803, 1811, 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2133, 2136, 2137, 2140, 2142, 2144, 2145, 2151, 2152, 2154, 2155, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2170, 2171, 2173, 2174, 2175, 2182, 2186, 2187, 2193, 2194, 2195, 2197, 2199, 2200, 2201, 2204, 2206, 2525, 2538, 2546, 2547, 2576, 2578, 2582, 2583, 2592, 2627, 2628, 2757, 2767, 3206, 3213, 3347 Rykov, A. G., 606, 763, 765, 780, 1134, 1164, 1315, 1319, 1326, 1330, 1331, 1333, 1334, 1335, 1336, 1337, 1338, 1352, 1416, 1430, 1481, 1545, 1549, 2129, 2131, 2427, 2527, 2531, 2594, 2595, 3061, 3101, 3106, 3111, 3113 Rykov, V. A., 1516 Rykova, A. G., 1145 Ryu, J. S., 2984 Ryzhkov, M. V., 1692 Ryzhov, M. N., 1271, 1352, 1427 Ryzhova, L. V., 1431 Saadi, M., 298, 301 Saadioui, M., 2655 Saba, M. A., 3227, 3228, 3230 Saba, M. T., 2662 Sabat, M., 2473, 2479, 2893 Sabatier, R., 457 Sabattie, J.-M., 2449, 2450 Sabau, C. A., 3043, 3044 Sabau, C. S., 1352 Sabelnikov, A. V., 822 Sabharwal, K. N., 1294, 1295 Sabine, T. M., 2430 Sabol, W. W., 1086, 1088 Saboungi, M.-L., 277

Author Index

I-255

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Sacher, G., 3353, 3356, 3362, 3366, 3370, 3378, 3386, 3395, 3407, 3424 Sachs, A., 108 Sachs, S., 3140, 3150 Sackett, W. M., 163, 170, 226 Sackman, J. F., 977, 1035 Saddington, K., 2731 Sadigh, B., 2370 Sadikov, G. G., 541 Saed, A. G., 184 Saeki, M., 727, 749, 750, 792, 793, 3043 Saengkerdsub, S., 3127, 3139 Safronova, Z. V., 2657 Sagaidak, R. N., 1654, 1719, 1720, 1735, 1738 Saggio, G., 3003 Sagi, L., 1432 Saha, R., 396 Sahar, A., 2132 Sahm, C. C., 6 Sahoo, B., 86, 91, 466 Saibaba, M., 396 Saiger, G. L., 3358 Saiki, M., 182 Saiki, W., 338 Saillard, J.-Y., 435 Sainctavit, P., 2236 Saita, K., 392, 395 Saito, A., 1132, 2400, 2726, 3287 Saito, E., 2855 Saito, M., 1398 Saito, T., 727 Saito, Y., 353, 360, 362 Sakaguchi, T., 2668 Sakai, M., 13, 1660 Sakai, T., 225 Sakairi, M., 28, 29, 40, 41 Sakaki, S., 2966 Sakakibara, T., 100 Sakama, M., 1267, 1445, 1484, 1696, 1718, 1735 Sakamoto, M., 2418 Sakamoto, Y., 822, 1160 Sakamura, Y., 717, 1270, 2134, 2135, 2695, 2696, 2697, 2698, 2699, 2700, 2715, 2716, 2719, 2720, 2724 Sakanoue, M., 170, 188, 225, 226, 1323, 1324, 1541 Sakanque, M., 1352, 1354 Sakara, M., 1699, 1700, 1710, 1718 Sakata, M., 2693, 2717, 2719 Sakman, J. F., 976 Sakurai, H., 2153, 2157 Sakurai, S., 1049, 3066 Sakurai, T., 343 Salahub, D. R., 1910 Salamatin, L. I., 822, 1624, 1629, 1632, 1635 Salasky, M., 1432

Salazar, K. V., 452, 1959, 2449, 2450, 2472, 2480, 2484, 2801, 2807, 2832, 2891 Salazar, R. R., 2749 Salbu, B., 3016, 3021, 3023, 3026, 3028, 3031, 3032, 3063, 3066, 3173 Salem, S. I., 859 Sales, B. C., 1171 Sales Grande, M. R., 230 Sallach, R. A., 543 Saller, H. A., 325 Salmon, L., 2254 Salmon, P., 416, 742 Salsa, B. A., 1959 Saluja, P. P. S., 2133, 2531 Salutsky, M. L., 19, 33, 34, 38, 162, 172, 178, 224, 225 Salvatore, F., 371 Salvatore, M., 1285 Salvatores, M., 2756 Salvi, N., 2668, 2669 Salzer, A., 2924 Salzer, M., 86, 88, 91, 467, 487, 1106 Samadfam, M., 294 Samartzis, T., 94 Sameh, A. A., 1960 Samhoun, K., 34, 37, 1325, 1326, 1328, 1329, 1330, 1365, 1366, 1460, 1481, 1482, 1523, 1526, 1529, 1547, 1548, 1549, 1555, 1557, 1558, 1559, 1602, 1606, 1611, 1628, 1629, 1630, 1635, 1636, 1639, 1640, 1641, 1644, 1645, 2123, 2129, 2131, 2526 Samilov, P. S., 164, 166 Samochocka, K., 1352 Sampath, S., 2434 Sampson, K. E., 3062 Sampson, T. E., 996 Samsel, E. G., 2930 Samson, S., 373 Samsonov, G. V., 323 Samsonov, M. D., 856, 2678, 2684 Samter, V., 82, 90, 93, 105, 109 San Pietro, A., 3341, 3342, 3348, 3353, 3356, 3386 Sanada, Y., 3171 Sanchez, A. L., 3175 Sanchez, C., 3409 Sanchez Cabeza, J. A., 3016, 3017, 3023 Sanchez, J. P., 409, 412, 719, 720, 744, 792, 2236 Sanchez, S., 2135, 2699, 2700 Sanchez-Castro, C., 2344 Sanchis, H., 1071 Sandell, E. B., 632 Sandenaw, T. A., 744, 886, 888, 939, 945, 949, 954, 955, 956, 957, 963, 1048, 2315, 2355 Sanders, C. J., 2887

I-256

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Sanders, C. L., 3352, 3424 Sanders, D., 854 Sanderson, S. W., 106 Sandino, A., 293, 2583 Sandino, M. C. A., 270 Sandratskii, L. M., 2367 Sandstro¨m, M., 118, 123, 586, 1991, 2531, 2576, 3101, 3102, 3103, 3104, 3105, 3106, 3126, 3127, 3128 Sanger, A. R., 2980 Sani, A. R., 28 Sankaran, K., 1988 Sano, T., 1019 Sano, Y., 2743 Santhamma, M. T., 77 Santini, C., 3002 Santini, P., 421, 444, 448, 1055, 1784, 1785, 2238, 2280, 2286, 2287, 2288, 2292, 2294 Santoro, A., 340, 345, 346, 348, 1067, 3214 Santos, G. P., 3057 Santos, I., 2880, 2881, 2882, 2883, 2884, 2885, 2886 Santos, I. G., 597 Santos, M., 2150 Santschi, P. H., 1806, 3016, 3022, 3024 Saprykin, A. S., 1326, 1416, 1429 Sara, K. H., 496 Sargent, F. P., 2736 Sari, C., 69, 73, 396, 719, 720, 721, 724, 726, 1030, 1070, 1071, 1073, 1299, 2143, 2384, 2386, 2387 Sarkisov, E. S., 1458 Saro, S., 6, 14, 164, 1653, 1654, 1701, 1713, 1717, 1719, 1720, 1735, 1737, 1738 Sarp, H., 265, 266 Sarrao, J. L., 967, 968, 1784, 1790, 2239, 2347, 2352, 2353, 2372 Sarsfield, M. J., 578, 589, 2400, 2401, 2441 Sarup, R., 2038, 2039, 2078 Sasahira, A., 855, 856 Sasajima, N., 2208, 2211 Sasaki, K., 2275, 2279, 2294 Sasaki, N., 68 Sasaki, T., 856, 2679, 2680, 2681, 2682, 2683, 2684 Sasaki, Y., 1286, 2658, 2659 Sasao, N., 822 Sasashara, A., 2693, 2717 Sasayama, T., 1018 Sassani, D. C., 2132 Sastre, A. M., 845, 2655 Sastry, M. D., 1175 Sata, T., 77, 353, 360 Sathe, R. M., 109 Sathyamoorthy, A., 339 Sa¨tmark, B., 2756 Sato, A., 40, 1477

Sato, H., 407 Sato, N., 396, 397, 398, 407, 2239, 2347, 2352 Sato, T., 215, 227, 273, 1019, 1518, 3171 Satoh, K., 407 Satoh, T., 63 Satonnay, G., 289 Satpathy, K. C., 86, 91 Satpathy, M., 1447 Sattelberger, A. P., 439, 454, 455, 752, 1182, 1183, 1184, 1185, 1186, 1190, 1959, 1965, 2480, 2481, 2482, 2487, 2488, 2490, 2802, 2832, 2837, 2856, 2857, 2858, 2867, 2868, 2876, 2879, 2891, 2916 Sattelberger, P., 789, 1875, 1876, 1877, 3044, 3047, 3048, 3320, 3321 Satten, R. A., 471, 476, 482, 496, 2066, 2067, 2226 Satterthwaite, C. B., 64, 65, 66 Saue, T., 34, 1670, 1728, 1905, 1918, 1919, 1931 Sauer, M. C., Jr., 2760 Sauer, N. N., 2400, 2484 Saunders, B. G., 859 Sauro, L. J., 1284, 1509, 1513, 1585 Sautereau, H., 2438, 2439, 2443 Savage, A. W., 474 Savage, D. J., 633, 1048, 1152, 3282 Savage, H., 1048 Savard, G., 1735 Savilova, O. A., 711, 761, 2757 Savochkin, Y. P., 2699, 2705 Savoskina, G. P., 1271, 1513 Savrasov, S. Y., 923, 964, 2344, 2347, 2355 Sawa, M., 410 Sawa, T., 845 Sawai, H., 631 Sawant, L. R., 791, 3052, 3053 Sawant, R. M., 772, 2578 Sawatzky, G., 2236 Sawodny, W., 505, 509, 510, 543 Sawwin, S. B., 188 Sawyer, D. L., 67, 2407 Sawyer, J. O., 373, 375 Saxena, S. S., 407, 2239, 2359 Sayers, D. E., 3088 Saylor, H., 560 Sayre, W. G., 2530 Sbrignadello, G., 2441 Scaife, D. E., 83, 84, 2418, 2424 Scapolan, S., 631 Scargell, D., 178, 181 Scargill, D., 213, 218 Scarrow, R. C., 3416, 3419 Scavnicar, S., 102, 108, 113, 2430, 2558 Scha¨del, M., 14, 182, 185, 186, 1447, 1523, 1593, 1628, 1629, 1635, 1643, 1646, 1647, 1662, 1664, 1665, 1679, 1684,

Author Index

I-257

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 1685, 1686, 1687, 1690, 1696, 1698, 1699, 1700, 1704, 1705, 1708, 1709, 1710, 1711, 1712, 1713, 1714, 1716, 1718, 1721, 1735, 1738, 2575 Schaef, H. F., 287 Schaefer, J. B., 776, 777, 781, 2585 Schaeffer, D. R., 1049 Scha˜fer, H., 2333 Scha¨fer, H., 93, 492 Scha¨fer, T., 3070 Schafer, W., 719, 720 Schaffer, R., 3341, 3342, 3348, 3353, 3356, 3386 Schake, A. R., 1185, 1186, 2484, 2487, 2488, 2813, 2858 Schake, B. S., 2749 Schamhart, D. H., 3385 Schaner, B. E., 353, 354, 368, 369, 391 Schank, C., 2352 Schatz, G., 1873 Schauer, V., 372 Schausten, B., 185, 186, 1447, 1662, 1664, 1685, 1687, 1698, 1699, 1700, 1705, 1709, 1710, 1713, 1714, 1716, 1718 Schautz, F., 1959 Schaverien, C. J., 2924 Schawlaw, A. L., 1681 Schecker, J. A., 814, 863 Schedin, U., 2554 Scheele, R. D., 2704 Scheerer, F., 789, 1296, 1403, 1875, 1876, 1877 Scheetz, B. E., 293, 2452, 2456 Scheibaum, F. J., 3024 Scheidegger, A. M., 3152, 3155, 3156, 3157 Scheider, V., 1132 Scheinberg, D. A., 42, 43, 44 Scheitlin, F. M., 1049 Schell, N., 3106, 3107, 3111, 3112, 3122 Schenk, A., 2351 Schenk, H. J., 208, 470, 2241 Schenkel, R., 1299, 1411 Scheppler, C., 2135 Scherbakov, V. A., 575 Scherer, O. J., 2480, 2836 Scherer, U. W., 185, 1447, 1629, 1635, 1643, 1646, 1647, 1704, 1705, 2575 Scherer, V., 199, 201, 1323, 1419, 1422, 2417 Scherff, H. L., 182, 195, 209, 215, 224, 2407, 2408 Scherrer, A., 1881 Schertz, L. D., 117, 2840, 2913, 2918, 2919, 2920, 2924 Scheuer, U., 932, 933 Schiaffino, L., 597 Schickel, R., 1008 Schiferl, D., 1300 Schild, D., 133 Schilling, J., 76, 82, 93 Schimbarev, Y. V., 1829

Schimek, G. L., 475, 495, 2827, 2868 Schimmack, W., 3017 Schimmelpfenning, B., 565, 580, 589, 596, 610, 620, 622, 623, 1156, 1907, 1909, 1918, 1919, 1921, 1922, 1923, 1924, 1925, 1926, 1931, 1932, 2185, 2187, 2195, 2532, 2576, 3102, 3120, 3126, 3127, 3128 Schimpf, E., 182, 185, 1447, 1662, 1664, 1685, 1699, 1700, 1704, 1705, 1709, 1710, 1713, 1714, 1716, 1718 Schindler, M., 286, 290 Schioeberg, D., 3117 Schiraldi, D. A., 2811 Schirber, J. E., 2334, 2335, 2339 Schlea, C. S., 1427 Schlechter, M., 1033, 2395 Schlehman, G. J., 1031 Schleid, T., 80, 425, 431, 435, 447, 456, 469, 471, 1315 Schlemper, E. O., 268 Schlenker, P., 3416, 3420 Schlesinger, H. I., 337, 1187 Schlesinger, M. E., 2728 Schlosser, F., 1925 Schlosser, G., 2734 Schlyter, K., 445 Schmeide, K., 3140, 3150 Schmeider, H., 2733 Schmick, H. E., 1299 Schmid, B., 444, 455, 2257, 2258 Schmid, K., 2819 Schmid, W. F., 110 Schmidbaur, H., 2472 Schmidt, C., 2655 Schmidt, C. T., 3344, 3353, 3369, 3373, 3388, 3389, 3391, 3392, 3393, 3394, 3395, 3396, 3405, 3406 Schmidt, F. A., 61 Schmidt, H., 1073 Schmidt, H. G., 64, 113 Schmidt, K. H., 6, 768, 769, 770, 1473, 1474, 1475, 1660, 1738, 1774, 1776, 1882, 2077, 2531, 2553 Schmidt, K. M., 1325, 1326, 1337, 1416, 1424, 1430 Schmidt, K. N., 2526 Schmidt, M., 1908, 3102, 3138, 3140, 3141, 3145, 3147, 3149 Schmidt, R., 1507 Schmidtke, H. H., 2051 Schmieder, H., 423, 445, 448 Schmieder, M., 2732 Schmitt, P., 2457 Schmitz, F., 391 Schmitz-Dumont, O., 410 Schmutz, H., 1105, 1106, 1312 Schnabel, B., 64

I-258

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Schnabel, P., 389 Schnabel, P. G., 357 Schnabel, R. C., 1185, 2491, 2831, 2835, 2849, 2919 Schnap, B., 3341, 3342, 3348, 3353, 3356, 3386 Schneider, 1507 Schneider, A., 399 Schneider, H., 421, 485, 557, 3003 Schneider, J. H. R., 6, 1738 Schneider, J. K., 1477, 1550, 2563 Schneider, O., 413 Schneider, R. A., 707 Schneider, V. W., 839, 852, 1070, 1071, 1073, 1074 Schneider, W. D., 2359 Schneider, W. F., 1966 Schneider, W. F. W., 6, 1738 Schneiders, H., 410 Schnell, N., 1923 Schnizlein, J. G., 3219, 3233, 3234 Schober, H., 942 Schock, L. E., 2473, 2912, 2918, 2924 Schock, R. N., 1299, 1300 Schoebrechts, J. P., 431, 451, 735, 739, 1312, 1469, 1483, 2182, 2687, 2689 Schoen, J., 1284 Schoenes, J., 100, 2276, 2277, 2289, 2290 Schoenfeld, F. W., 3213, 3238 Schoenmackers, R., 1477 Schofield, P., 3121, 3142 Schofield, P. F., 3102, 3120, 3143 Scholder, R., 77, 372, 375, 376, 377, 378, 382 Scholten, J., 3046 Schomaker, V., 1935, 1937 Schonfeld, F. W., 880, 892, 894, 896, 898, 900, 901, 902, 903, 904, 905, 907, 908, 909, 910, 911, 912, 913, 914, 933, 936, 937, 938, 939, 953 Schoonover, J. R., 97, 3041, 3069 Scho¨pe, H., 1879, 1880, 1882, 1884 Schopfer, C. J., 3307 Schott, H. J., 6, 14, 1653, 1654, 1662, 1664, 1685, 1701, 1713, 1714, 1716, 1719, 1720, 1737, 1738 Schotterer, U., 1806 Schrader, R. J., 490 Schram, R. P. C., 2139, 2142 Schramke, J. A., 1149, 2192 Schrauder, M., 3305 Schreck, H., 41, 1322, 1323, 1428, 1431, 1513, 1552 Schreckenbach, G., 580, 589, 596, 620, 621, 1192, 1193, 1194, 1198, 1199, 1777, 1921, 1922, 1923, 1924, 1925, 1926, 1927, 1931, 1932, 1935, 1936, 1938, 1940, 2528, 3102, 3111, 3112, 3113, 3121, 3122, 3123, 3126, 3128

Schreiber, C. L., 471, 476, 482, 496, 2066, 2067, 2226 Schreiber, D. S., 64 Schreiber, S. B., 726, 1141 Schreier, E., 2284 Schreiner, F., 1161, 1165, 1166, 1170 Schrepp, W., 787, 1114 Schretzmann, K., 366 Schrieffer, J. R., 62, 2350, 2351 Schroeder, N. C., 2633, 2634, 2642, 2676 Schubert, J., 1823, 3387, 3388, 3413 Schuler, Ch., 3016, 3022 Schuler, F., 3399 Schuler, F. W., 63 Schu¨ler, H., 190, 226 Schull, C. G., 64 Schulte, L. D., 2749 Schultz, A. J., 2479, 2481, 2839, 2841 Schultz, H., 981, 983 Schultz, M., 1956, 2803, 2806, 2807, 3020 Schultze, J., 2836 Schulz, A., 117, 118 Schulz, W. W., 188, 841, 843, 1265, 1267, 1270, 1277, 1278, 1280, 1281, 1282, 1283, 1290, 1291, 1292, 1298, 1328, 1329, 1342, 1398, 1403, 1408, 2626, 2650, 2652, 2653, 2655, 2730, 2739, 2740, 2741, 2742, 2746 Schulze, J., 2480 Schulze, R. K., 964, 967 Schuman, R. P., 167, 169, 187, 188, 195, 209, 214, 215, 217, 218, 230, 2578 Schumann, D., 40, 1624, 1632, 1662, 1679, 1684, 1687, 1698, 1699, 1700, 1708, 1709, 1710, 1716, 1718 Schumann, H., 1957, 2918, 2924, 2969, 2974 Schumm, R. H., 34, 2114, 2165 Schuppler, U., 3354, 3398 Schurhammer, R., 2685 Schu¨ssler-Langeheine, C., 2237 Schuster, M., 89, 93, 94 Schuster, R. E., 118, 2530, 2533 Schuster, W., 1321, 1359, 2407, 2408 Schu¨tz, G., 2236 Schu¨tze, Th., 1884 Schwab, M., 1300, 1403, 1410, 1411, 1412 Schwalbe, L., 1300 Schwalm, D., 33 Schwamb, K., 1840, 1877, 1884 Schwamb, P., 33, 1879, 1880, 1881, 1882, 1883, 1884 Schwarcz, H. P., 189 Schwartz, A. J., 863, 964, 965, 967, 980, 981, 983, 984, 986, 987, 2342 Schwartz, C. M., 377, 378 Schwartz, D. F., 319 Schwartz, J. L., 3362 Schwartz, L. L., 621, 622, 2599

Author Index

I-259

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Schwartz, S., 3037 Schwarz, H., 77, 1971, 1990 Schwarz, R., 77 Schwarz, W. H. E., 1666, 1667, 1668, 1669, 1671, 1898 Schwarzenbach, G., 597 Schweiger, J. S., 180 Schweikhard, L., 1735 Schweiss, P., 2250, 2471, 2472 Schwerdtfeger, P., 1646, 1666, 1667, 1668, 1669, 1670, 1671, 1672, 1673, 1675, 1676, 1682, 1683, 1689, 1691, 1723, 1724, 1725, 1727, 1729, 1898 Schwetz, K., 67 Schwickert, G., 1880 Schwikowski, M., 1806 Schwing-Weill, M.-J., 2655 Schwochau, K., 114, 206, 208, 220, 470, 2241 Schwochau, V., 220 Schwotzer, W., 470, 2490, 2491, 2493, 2859, 2860 Scibona, G., 123, 773 Science and Technology Review, 3265 Scofield, J. H., 1453, 1516 Scoppa, P., 1803, 1809 Scott, B. C., 2835 Scott, B. L., 117, 593, 967, 1069, 1112, 1116, 1117, 1149, 1156, 1162, 1166, 1173, 1174, 1181, 1312, 1327, 1328, 1360, 1784, 1790, 1958, 1991, 1992, 2239, 2352, 2372, 2400, 2401, 2427, 2428, 2429, 2450, 2451, 2452, 2453, 2454, 2455, 2456, 2464, 2465, 2466, 2472, 2479, 2480, 2484, 2491, 2530, 2583, 2590, 2813, 2827, 2844, 2845, 2846, 2850, 2868, 2869, 2919, 2922, 2996, 3035, 3113, 3115, 3123, 3136 Scott, F. A., 2704 Scott, G. L., 2831, 2849 Scott, K. G., 3341, 3342, 3348, 3354, 3356, 3387, 3413, 3423, 3424 Scott, M. J., 2655 Scott, P., 575, 1901, 1962, 1963, 1964, 2473, 2491, 2816, 2886, 2887, 2888, 2984 Scott, R. B., 2159, 2161 Scott, R. D., 3062 Scott, T. E., 61 Scotti, A., 366, 367 Scuseria, G. E., 1906, 1936, 1937, 1938, 2864 Seaborg, G. T., xv, xvi, xvii, 3, 4, 5, 6, 8, 10, 18, 19, 25, 53, 162, 164, 184, 255, 256, 622, 704, 732, 814, 815, 817, 821, 822, 823, 834, 835, 902, 903, 904, 907, 912, 913, 988, 1108, 1265, 1267, 1304, 1312, 1321, 1323, 1324, 1397, 1398, 1400, 1403, 1418, 1444, 1449, 1450, 1451, 1480, 1481, 1499, 1501, 1503, 1508, 1549, 1577, 1580, 1584, 1585, 1586,

1613, 1621, 1622, 1624, 1628, 1629, 1630, 1632, 1635, 1637, 1639, 1642, 1643, 1644, 1645, 1646, 1653, 1660, 1661, 1664, 1684, 1689, 1691, 1693, 1694, 1695, 1696, 1697, 1698, 1699, 1706, 1716, 1723, 1724, 1731, 1734, 1738, 1754, 1756, 1761, 1901, 1916, 1928, 2114, 2538, 2562, 2580, 2625, 2629, 2630, 2635, 2638, 2639, 2670, 2730, 3206, 3207, 3208, 3212, 3276, 3340, 3347, 3348, 3353, 3354 Sear, H., 3358 Searcy, A. W., 69, 72, 78, 2407 Sears, D. R., 87, 92 Sears, G. W., 963, 1045, 1083, 1085, 1086 Seayad, A. M., 2982 Secaur, C. A., 2491 Sechovsky´, V., 339, 2351, 2353, 2356, 2357, 2358, 2360, 2361, 2363, 2366, 2368, 2411 Secoy, C. H., 390 Seddon, E. A., 2877 Seddon, K. R., 854, 2686, 2690 Sedgwick, D., 3354 Sedla´kova´, L., 373, 374, 375 Sedlet, J., 19, 38, 42, 162, 172, 181, 182, 2655, 2738, 2739 Sedykh, I. M., 1707, 1719 Seed, J. R., 1144 Seeger, R., 1902 Seemann, I., 375, 376, 377 Segnit, E. R., 295 Segovia, N., 3057 Segre`, E., 5, 8, 166, 699, 700, 815 Seibert, A., 1662, 1687, 1698, 1709, 1710, 1718, 3069 Seibert, H. C., 3424 Seidel, A., 3398, 3399 Seidel, B., 2352 Seidel, B. S., 763, 766 Seidel, D., 605, 2401, 2464, 2465, 2466 Seidel, S., 1975 Seifert, R. L., 963, 1083, 1085, 1086 Seiffert, H., 728, 1057, 1061 Seijo, L., 442, 1895, 1896, 1897, 1908, 1909, 1930, 2037 Seip, H. M., 1935, 1937 Seitz, F., 2310, 2966 Seitz, T., 63, 70 Sejkora, J., 262, 264, 281 Seki, R., 3017 Sekine, R., 576, 577, 1935, 1936, 2165 Sekine, T., 28, 29, 40, 41, 1352, 2568, 2580, 2585, 2591, 2625, 2649, 2669, 2670 Selbin, J., 116, 376, 377, 378, 382, 501, 508, 513, 516, 517, 521, 522, 523, 526, 528, 2243, 2815 Sel’chenkov, L. I., 847

I-260

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Selenska-Pobell, S., 3179, 3180, 3181, 3182 Seleznev, A. G., 984, 1299, 1317, 1412, 1413, 1518, 1519, 1520, 1521, 2118 Seleznev, B. L., 3029 Selig, H., 533, 731 Selin, T. J., 2969 Sella, A., 1947 Selle, J. E., 903, 1049 Sellers, G. A., 3046 Sellers, P. A., 191, 192, 193, 194, 195, 196, 198, 201, 206, 207, 229, 2389, 2391 Sellers, P. O., 172, 175, 219 Sellman, P. G., 75, 96, 2413 Selucky, P., 2655 Selvakumar, K., 2982 Semenov, E. N., 791, 3052 Semenov, G. A., 2147 Semochkin, V. M., 180 Se´mon, L., 596, 3102, 3119, 3121 Sen Gupta, P. K., 268 Sen, W. G., 1624, 1632 Sena, F., 3068 Senentz, G., 2633 Senftle, F. E., 1507 Seng, W. T., 1509 Senin, M. D., 2168 Sepp, W.-D., 1671, 1677, 1680, 1706, 1716 Seppelt, K., 535, 542, 1975 Seraglia, R., 2491, 2831 Seranno, J. G., 715 Serebrennikov, V. V., 109 Sereni, J. G., 62, 63 Seret, A., 719, 720 Serezhkin, V. N., 536, 2441 Serezhkina, L. B., 536, 2441 Serfeyeva, E. I., 1328 Sergeev, A. V., 2441 Sergeev, G. M., 1352, 1405, 1428, 1433 Sergent, M., 435, 471 Sergeyava, E. I., 129, 771, 2114, 2546, 2580 Serghini, A., 102, 110 Serik, V. F., 731, 732, 734, 736, 1082, 1312, 1315, 1327, 2421 Se´riot, J., 332 Serizawa, H., 396, 397, 398, 1317, 2140, 2142, 2411 Serne, R. J., 3173, 3176, 3177 Serp, J., 2135 Serrano, J., 3043, 3045 Sersbryakov, V. N., 3221 Sessler, J. L., 605, 2401, 2463, 2464, 2465, 2466 Seta, K., 347 Seth, M., 1646, 1666, 1668, 1669, 1670, 1671, 1675, 1676, 1682, 1683, 1689, 1691, 1723, 1724, 1725, 1726, 1727, 1729 Settai, R., 407 Settle, J. L., 2719, 2720 Sevast’yanov, V. G., 416, 2177

Sevast’yanova, E. P., 769 Sevast’yanova, Yl. P., 3352, 3424 Seven, M. J., 3413 Severing, A., 333, 334, 335, 2283, 2284, 2285 Sevestre, Y., 3025 Seward, N. K., 1662, 1701, 1712, 1713, 1717 Sewtz, M., 33, 1879, 1880, 1881, 1882, 1883, 1884 Sewtz, M. H., 1840, 1877, 1884 Seyam, A. M., 116, 117, 1802, 1956, 1957, 2473, 2815, 2819, 2827, 2832, 2837, 2838, 2841, 2842, 2847, 2912, 2913, 2924, 2997 Seyferth, D., 1188, 1802, 1943, 2252 Sganga, J. K., 1507 Shabana, E. I., 186 Shabana, R., 176, 181, 182, 184, 185 Shabestari, L., 1507, 3349, 3350, 3396 Shabestari, L. R., 3396, 3405 Shacklett, R. L., 859 Shadrin, A., 2684, 2685 Shadrin, A. U., 2739 Shadrin, A. Y., 856, 2682, 2684 Shafiev, A. I., 1292, 1448, 1449 Shah, A. H., 1449, 2663 Shahani, C. I., 40, 41 Shahani, C. J., 40, 41 Shalaevskii, M. R., 1628, 1634, 1640, 1645, 1663, 1664, 1690, 1703 Shalek, P. D., 95, 407, 412 Shalimoff, G., 2233, 2240, 2261, 2264, 2270, 2293 Shalimoff, G. V., 1419, 1543, 1776, 1954, 1955, 2143, 2144, 2230, 2240, 2264, 2265, 2397, 2473, 2803 Shalimov, V. V., 1512, 1585 Shalinets, A. B., 1352, 1353, 2546, 2588, 2590 Sham, L. J., 1903, 2327 Shamir, J., 471, 512, 513 Shamsipur, M., 2681, 2684 Shanbhag, P. M., 2400 Shand, M. A., 2440 Shankar, J., 215, 218, 2431 Shanker Das, M., 109 Shannon, R. D., 18, 34, 55, 1296, 1463, 1528, 1675, 1676, 2126, 2557, 2558, 2563, 2572, 2916, 3106, 3115, 3123, 3124, 3127, 3347, 3348, 3353, 3360, 3365, 3379 Shanton, H. E., 1588 Shapkin, G. N., 1363 Shapovalov, M. P., 1120, 1128, 1129, 1142 Shapovalov, V. P., 817 Sharan, M. K., 1447 Sharma, A. K., 3031 Sharma, H. D., 1169, 2585 Sharma, R. C., 791, 3057 Sharovarov, G., 3024 Sharp, C., 3413

Author Index

I-261

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Sharp, D. W. A., 520 Sharp, P. R., 2699 Sharpe, L. R., 3107 Shashikala, K., 339 Shashukov, E. A., 1127 Shatalov, V. V., 989, 996 Shatinskii, V. M., 166 Shaughnessy, D. A., 14, 815, 1447, 1582, 1654, 1662, 1684, 1693, 1711, 1712, 1716, 1719, 1736, 1738, 3173, 3176, 3177 Shaughnessy, D. K., 185, 186, 1699, 1705, 1718 Shaver, K., 172, 178, 224, 225 Shavitt, I., 1903, 1908, 1909 Shaw, J. L., 1009 Shchegolev, V. A., 1664, 1690, 1703 Shchelokov, R. N., 539, 565, 566, 2441, 2442 Shcherbakov, V. A., 2533, 2579, 3111, 3122 Shcherbakova, L. L., 575, 2533 Shchukarev, S. A., 82, 516 Shea, T., 1071 Sheaffer, M. K., 3017 Shea-Mccarthy, G., 3095, 3175, 3177 Shebell, P., 3027 Sheen, P. D., 2457 Sheff, S., 2691 Sheft, I., 317, 421, 742, 743, 855, 1077, 1086, 1095, 1100, 1101, 1417, 2407, 2408, 2411 Sheikin, I., 407, 2239, 2359 Sheindlin, M., 357, 359, 1077 Sheldon, R. I., 920, 939, 949, 963 Sheline, R. K., 24, 31, 1968, 1985, 2894 Shelton, R. N., 96 Shen, C., 1285 Shen, G. T., 3159 Shen, J., 263 Shen, Q., 2924 Shen, T. H., 932, 967 Shen, Y., 2049 Shen, Y. F., 76 Sheng, Z., 3057 Shenoy, G. K., 862, 1297, 1304, 1317, 1319, 2292 Shepard, R., 1908, 1909 Shepelev, Y. F., 1361 Shepelev, Yu. F., 539 Shepel’kov, S. V., 113 Sherby, O. D., 958 Sherif, F. G., 2580 Sherman, M. P., 3212, 3213, 3220, 3221, 3222, 3249 Sherrill, H. J., 508, 516, 517, 521, 526, 528, 2243 Sherry, E., 346, 2394 Shestakov, B. I., 31, 41, 2557 Shestakova, I. A., 31, 38, 39, 40, 41, 2557 Shesterikov, N. N., 1169

Shetty, S. Y., 109 Shevchenko, V. B., 175, 184, 1161, 1171, 1172 Shewmon, P. G., 960 Shiba, K., 394 Shibata, M., 1267, 1445, 1484 Shibata, S., 1681 Shibusawa, T., 631 Shick, A. B., 929, 953, 2355 Shigekawa, M., 1696, 1718, 1735 Shigeta, K., 3067 Shiina, R., 2347 Shikama, M., 407 Shikany, S. D., 3258, 3259 Shiknikova, N. S., 1821 Shilin, I. V., 772, 773 Shilnikova, N. S., 1821 Shiloh, M., 771, 1312, 1338, 1365 Shilov, A. E., 3002 Shilov, V. N., 1338 Shilov, V. P., 626, 753, 770, 988, 1113, 1117, 1118, 1127, 1129, 1133, 1156, 1325, 1327, 1329, 1336, 1352, 1367, 1368, 1416, 1429, 2127, 2527, 2583, 3043, 3098, 3124, 3125, 3126 Shimazu, M., 631 Shimbarev, E. V., 1317, 1422, 1466 Shimizu, H., 356 Shimojima, H., 215, 216, 224 Shimokawa, J., 1019 Shin, J. H., 2849 Shin, Y., 3127, 3139 Shin, Y. S., 2688 Shinde, V. M., 3035 Shinkai, S., 2560, 2590 Shinn, J. H., 3017 Shinn, W. A., 373, 378, 391, 1046, 1074, 1088, 1090, 1091 Shinohara, A., 1696, 1718, 1735 Shinohara, N., 784, 1625 Shinohara, S. N., 2637 Shinomoto, R., 482, 2251 Shinozuka, K., 631 Shiokawa, T., 219 Shiokawa, Y., 37, 718 Shiozawa, K., 2724 Shirahashi, K., 1276, 2753, 2755, 2760 Shirai, O., 717, 753, 790, 791, 2695, 2698, 2715, 2716, 2724 Shiraishi, K., 789, 790, 3059, 3062, 3068, 3072 Shirane, G., 2273 Shirasu, Y., 1317 Shiratori, T., 394, 396, 397, 398 Shirley, V. A., 3274, 3277, 3290, 3298 Shirley, V. S., 24, 164, 817, 1267, 1398, 1626, 1633, 1639, 1644 Shirokova, I. B., 1321 Shirokovsky, I. V., 14, 1398, 1400, 1504, 1653, 1654, 1707, 1719, 1736, 1738

I-262

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Shishalov, O. V., 2699, 2705 Shishkin, S. V., 822 Shishkina, O. V., 2441 Shishkina, T. V., 822 Shivanyuk, A., 2655 Shkinev, V. M., 1408, 2667 Shleien, B., 1506 Shlyk, L., 415, 2413 Shmakov, A. A., 960 Shmulyian, S., 33, 1659, 1669, 1675, 1724, 1731 Shock, E. L., 2132 Shoesmith, D. W., 289, 371 Shoji, Y., 1696, 1718, 1735 Shor, A. M., 1906, 1921, 1923 Shore, B. W., 1588, 1590, 1878, 1879 Shorikov, A. O., 929, 953 Short, D. W., 958, 959 Short, I. G., 2087 Short, J. F., 164, 173, 180, 224 Shortley, G. H., 1862, 2089 Shoun, R. R., 107, 1271, 1312, 1509, 1554, 1585 Shoup, S., 1312 Shpunt, L. B., 1049 Shreve, J. D., 3252, 3253, 3255 Shrivastava, A., 1447 Shtrikman, S., 936, 943, 944 Shuanggui, Y., 1267 Shuh, D. K., 118, 277, 287, 289, 579, 585, 589, 602, 795, 967, 1112, 1166, 1327, 1338, 1363, 1370, 1825, 1921, 1923, 1947, 2530, 2531, 2532, 2568, 2576, 2580, 2583, 2588, 2812, 3095, 3101, 3102, 3103, 3104, 3106, 3107, 3110, 3111, 3113, 3114, 3115, 3117, 3118, 3119, 3122, 3130, 3131, 3135, 3138, 3140, 3141, 3142, 3145, 3146, 3147, 3149, 3150, 3152, 3154, 3155, 3156, 3160, 3165, 3166, 3167, 3173, 3176, 3177, 3179, 3182, 3369, 3385, 3388, 3390, 3391, 3394, 3417, 3420, 3423 Shuhong, W., 1267 Shuifa, S., 1267 Shukla, J. P., 845, 2750 Shuler, W. E., 763, 764 Shull, C. G., 334, 335, 2232, 2402 Shull, R. D., 927 Shults, W. D., 1480, 1481 Shumakov, V. D., 939, 941 Shunk, F. A., 325, 405, 407, 408, 409, 411 Shupe, W. M., 3223 Shushakov, V. D., 1299, 1412, 1413, 1518, 1519, 1520, 1521, 2118 Shutov, A. V., 1654, 1719, 1720, 1738 Shvareva, T. Y., 1173 Shvetsov, I. K., 1271, 1352, 1479, 1583, 3221

Siba, O. V., 545, 546 Sibieude, F., 77 Sibrina, G. F., 113 Sichere, M.-C., 272, 292 Siddall, T. H., 1276, 1277, 1278, 2532 Siddall, T. H., III, 2238, 2736 Siddall, T. H., Jr., 2653 Siddham, S., 76 Siddons, D. P., 2234 Sidhu, R. S., 3282 Sidorenko, G. V., 750, 2800 Sidorova, I. V., 2195 Siebens, A. A., 3357 Siegal, M., 1312, 1315, 1469 Siegal, S., 1530, 1531, 1533 Siegel, E., 3413 Siegel, M. D., 3409 Siegel, S., 88, 89, 93, 340, 341, 342, 343, 345, 346, 348, 350, 355, 356, 357, 358, 372, 375, 378, 380, 384, 389, 393, 471, 533, 1465, 1469, 1470, 2392, 2393, 2394, 2417, 2422, 3171, 3214 Siek, S., 69, 73 Siekierski, S., 188, 1666, 2580 Siemann, R., 2275, 2364 Sienel, G. R., 1191, 2817 Sienko, M. J., 423, 445, 2257, 2258 Sienko, R. J., 67, 71 Sievers, R., 89, 98, 473, 500 Sieverts, A., 63, 64 Sigmon, G., 584, 730, 2402 Sigurdson, E., 2866 Sikirica, M., 69, 73 Sikka, S. K., 2370 Sikkeland, T., 5, 6, 1502, 1637, 1638, 1639, 1640, 1641, 1642, 1643, 1645, 1653, 1662, 2129 Silberstein, A., 471, 472, 512, 513 Silbi, H., 3026, 3069 Silbley, T. H., 3175 Sillen, L. G., 2549, 3346, 3347 Sille´n, L. G., 103, 112, 120, 121, 123, 124, 132, 373, 510, 597, 602 Silva, A. J. G. C., 264 Silva, M., 2880, 2883, 2885 Silva, M. R., 2439 Silva, R., 1662, 1692, 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2129, 2137, 2143, 2144, 2154, 2155, 2159, 2165, 2171, 2173, 2174, 2175, 2182, 2186, 2187, 2190, 2192, 2194 Silva, R. J., 287, 863, 988, 1110, 1114, 1148, 1155, 1159, 1160, 1162, 1163, 1182, 1313, 1314, 1328, 1329, 1330, 1338, 1339, 1340, 1341, 1354, 1355, 1585, 1621, 1626, 1627, 1635, 1637, 1638, 1639, 1640, 1641, 1642, 1643, 1644, 1645, 1646, 1659, 1662, 1803, 2538,

Author Index

I-263

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 2546, 2582, 2583, 2592, 2639, 2640, 3043, 3095, 3140, 3142, 3145, 3150 Silver, G., 851 Silver, G. L., 1121, 1122, 1123 Silverman, L., 543 Silverwood, P. R., 2440 Silvestre, J. P., 113, 208, 1065, 1067, 1068, 1312 Silvestre, J. P. F., 477 Simakin, G. A., 1164, 1326, 1329, 1331, 1416, 1429, 1480, 1481, 1483, 1545, 2126, 2584 Simanov, Yu. P., 372, 373, 374, 375, 376, 377, 383, 384, 385, 393 Sime, R. L., 162, 169 Simionovici, A., 861 Simmons, B., 3358 Simmons, E. L., 3356, 3378, 3395, 3423, 3424 Simmons, W. B., 269, 277 Simms, H. E., 854 Simnad, M. T., 958 Simoes, J. A. M., 2885 Simoes, M. L. S., 2587 Simon, A., 89, 94, 95 Simon, D. J., 1735 Simon, G. P., 846, 851 Simon, J., 42, 43 Simon, N., 2655 Simoni, E., 422, 430, 431, 450, 451, 482, 1168, 1369, 1923, 2042, 2062, 2230, 2259, 3037, 3046, 3118, 3171 Simonsen, S. H., 2429 Simper, A. M., 1907, 1921, 1922, 1923, 2528, 3102, 3113, 3123 Simpson, C. Q., 2490 Simpson, F. B., 166, 230 Simpson, J. J., 189 Simpson, K. A., 348 Simpson, M. E., 3341, 3342, 3353 Simpson, O. C., 963, 1045, 1083, 1085, 1086 Simpson, P. R., 270, 271 Simpson, S., 2877 Simpson, S. J., 1962 Sims, H. E., 864, 2147, 2723, 3022 Sims, T. M., 1445, 1448, 1509, 1510 Sinaga, S., 339 Sinclair, D. J., 3047 Sinclair, W. K., 1821 Singer, J., 472, 1109 Singer, N., 115 Singer, T. P., 3361 Singh, D. J., 1904 Singh Mudher, K. D., 69, 104, 105, 371 Singh, N. P., 133, 3069 Singh, R. K., 845 Singh, R. N., 343 Singh, S., 105 Singh, Z., 2157, 2158, 2209 Singjanusong, P., 225

Singleton, J., 945, 947, 948, 949, 950, 2315, 2347, 2355 Sinha, A. K., 297 Sinha, D. N., 76, 106 Sinha, P. K., 2633 Sinha, S. P., 2688 Sinitsyna, G. S., 31, 41, 2557 Sinkler, W., 719, 721 Sipahimalani, A. R., 1281 Sipahimalani, A. T., 2747, 2748 Siregar, C., 2559 Sironen, R. J., 1018, 1275 Sishta, C., 2934 Sitran, S., 2440 Sivaraman, N., 2684 Sizoo, G. J., 164, 187 Sjoblom, R., 1325, 1326, 1337, 1416, 1424, 1430, 1774, 2077 Sjoblom, R. K., 1453, 1454, 1455, 1474, 1509, 1543, 1544, 1582, 1604, 1774, 1776, 2526 Sjodahl, L. H., 352, 357, 368 Sjoeblom, K. L., 3017 Ska´la, P., 262 Ska´la, R., 2427 Skalberg, M., 24, 1432, 1434, 1665, 2674, 2761 Skalski, J., 1735 Skanthakumar, S., 270, 287, 596, 602, 1370, 1420, 1777, 1921, 2233, 2263, 2267, 2268, 2691, 3178 Skarnemark, G., 24, 1665, 1666, 1695, 1702, 1717, 1735, 2767 Skavdahl, R. E., 997, 998, 1025, 1028, 1029, 1030, 1045 Skelton, B. W., 2457, 2571 Skiba, O. V., 546, 854, 1422, 2431, 2692, 2693, 2695, 2696, 2697, 2698, 2699, 2700, 2702, 2704, 2705, 2706, 2707, 2708, 2715 Skinner, C. W., 259, 262, 263, 264, 265, 266, 267, 268, 269, 275 Skinner, D. L., 3061 Skiokawa, Y., 1548 Skipperud, L., 3063 Skobelev, N. F., 1512 Skobelev, N. K., 1267, 1367 Skoblo, A. I., 575 Skold, K., 2232 Skoog, S. J., 2880 Skorik, N. A., 109 Skorovarov, D. I., 705 Skotnikova, E. G., 105 Skriver, H. L., 63, 928, 1300, 1459, 1527, 2150, 2276, 2359, 2370 Skwarzec, B., 3014, 3017 Skylaris, C.-K., 596, 1907, 1921, 1922, 1923, 1938, 2528, 3102, 3113, 3123 Slaback, L. A., Jr., 1506 Slade, R. C., 2054

I-264

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Slain, H., 319 Slater, J. C., 1860, 1861, 1862, 1863, 1865, 1910, 1939, 2020, 2027, 2029, 2058, 2076, 2324, 2325, 2326 Slater, J. L., 1968, 1985, 2894 Slater, J. M., 3029 Sleight, A. W., 376, 942 Slivnik, J., 86, 91, 506, 508 Sliwa, A., 335 Sljukic, M., 102, 103, 110, 2431 Slovokhotov, Y. L., 3087 Slovyanskikh, V. K., 416, 417, 419 Slowikowski, B., 3024, 3059, 3060 Slukic, M., 103, 110 Smalley, R. E., 2864 Smallwood, A., 3305 Smart, N. G., 856, 2678, 2680, 2681, 2682, 2683, 2684, 2685 Smentek, L., 1454 Smetana, Z., 2411 Smets, E., 343 Smiley, S. H., 485, 559 Smirin, L. N., 3017, 3067 Smirnov, E. A., 960 Smirnov, I. V., 856, 2682, 2684, 2685, 2739 Smirnov, M. V., 2695 Smirnov, N. L., 727, 2136 Smirnov, V. K., 2179 Smirnov, Yu. A., 791, 3049, 3052 Smirnova, E. A., 907, 909, 911, 912, 1513 Smirnova, I. V., 753, 1113, 1118, 1156, 3124 Smirnova, T. V., 747, 749, 750 Smirnova, V. I., 2527 Smit-Groen, V. S., 2153 Smith, A., 982 Smith, A. J., 102, 104, 105, 164, 184, 195, 201, 215, 220, 221, 222, 227, 2420, 2423, 2425, 2434, 2435, 2441 Smith, A. M., 1968 Smith, B., 225, 270, 271 Smith, B. F., 1287, 1512, 2633, 2634, 2676, 2677, 2761 Smith, C., 357 Smith, C. A., 849, 1139, 1161, 1167, 1926, 2864, 3109 Smith, C. L., 3409 Smith, C. M., 3204, 3215, 3216 Smith, C. S., 877 Smith, D., 3302 Smith, D. A., 3107 Smith, D. C., 739, 1958, 2479, 2847, 2848, 2849, 2921 Smith, D. H., 3321 Smith, D. K., 261, 292, 3288, 3314 Smith, D. M., 1166 Smith, D. W., 1935, 1937 Smith, E. A., 505, 506, 535

Smith, E. F., 80 Smith, F. J., 1270, 2702 Smith, G., 224 Smith, G. M., 1957, 1958, 2479, 2837, 2839, 2841, 2918, 2924, 2934 Smith, G. S., 80, 201, 509, 914, 1300, 1403, 1410, 1411, 1412, 2419, 2420, 2424 Smith, H., 1818, 1819, 1820 Smith, H. K., 66 Smith, H. L., 5, 227, 1577, 1622 Smith, H. W., 3395 Smith, J. A., 1427 Smith, J. F., 61, 2315 Smith, J. K., 1915, 2239 Smith, J. L., 161, 192, 193, 333, 334, 335, 921, 922, 923, 924, 926, 929, 945, 947, 948, 949, 950, 954, 955, 995, 1003, 1299, 1300, 1527, 1789, 2236, 2312, 2313, 2315, 2329, 2333, 2343, 2347, 2350, 2351, 2355, 2384, 2723 Smith, J. M., 3343, 3353, 3355, 3360, 3366, 3370, 3375, 3381, 3382, 3402, 3403, 3404, 3405 Smith, J. N., 231, 3314 Smith, K., 66 Smith, K. A., 2488, 2852, 2856 Smith, K. L., 271, 280, 291 Smith, L. L., 1294, 3280, 3285, 3323, 3327 Smith, P. H., 2573 Smith, P. K., 2149, 2387, 2388 Smith, R. A., 1011, 1018, 1019, 1022 Smith, R. C., 863, 3230 Smith, R. D., 2677, 2678 Smith, R. M., 604, 606, 771, 1178, 2557, 2558, 2559, 2568, 2571, 2575, 2576, 2579, 2581, 2582, 2634, 3347, 3353, 3361, 3382 Smith, R. R., 226 Smith, T., 2275 Smith, T. D., 2593 Smith, V. H., 1823, 3341, 3413, 3422 Smith, W., 2916 Smith, W. H., 1178, 1179, 1185, 2487, 2488, 2491, 2687, 2688, 2689, 2690, 2831, 2849, 2858, 2868, 2879, 2919 Smith, W. L., 1813, 3340, 3413, 3414 Smithells, C. J., 63, 75 Smithers, R. H., 2953 Smoes, S., 322, 364, 365 Smolan’czuk, R., 1717, 1735, 1736, 1737 Smolders, A., 1033 Smolin, Y. I., 1361 Smolin, Yu. I., 539 Smolnikov, A. A., 133 Smyth, J. R., 3031 Snellgrove, T. R., 546, 2087 Snijders, J. G., 1200, 1201, 1202, 1203, 1666, 1667, 1668, 1907, 1910, 1916, 1943,

Author Index

I-265

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 1944, 1947, 1948, 1951, 1972, 2089, 2253 Snow, A. I., 399 Snyder, R. H., 3356, 3378, 3395, 3423, 3424 Snyder, R. L., 417, 418 Sobczyk, M., 422, 425, 435, 442, 447 Sobelman, I. I., 2028, 2029 Sobiczewski, A., 1661, 1735 Sobolev, Y. B., 1335 Sobolov, Y. P., 1330, 1331 Soddy, F., 3, 20, 162, 163, 201, 254 Soderholm, L., 291, 457, 486, 584, 596, 602, 730, 731, 732, 734, 754, 764, 861, 1112, 1113, 1152, 1356, 1370, 1398, 1420, 1474, 1480, 1481, 1777, 1778, 1921, 1933, 2127, 2161, 2230, 2233, 2263, 2264, 2267, 2268, 2402, 2419, 2420, 2526, 2527, 2528, 2531, 2532, 2584, 2691, 3039, 3086, 3087, 3089, 3099, 3100, 3106, 3107, 3108, 3110, 3111, 3112, 3114, 3116, 3122, 3125, 3152, 3157, 3158, 3163, 3170, 3178, 3179, 3181 Soderland, J. M., 1300 Soderland, P., 1300, 1301 So¨derlind, P., 191, 1894, 2330, 2370 Sofield, C. D., 1947 Sofronova, R. M., 373, 375, 393 Soga, T., 460, 461, 462, 463, 467 Sokai, H., 231 Sokhina, L. P., 1169 Sokina, L. P., 1126 Sokol, E. A., 1720 Sokolnikov, M., 1821 Sokolov, E. I., 1315 Sokolov, V. B., 1082, 1312, 1315, 1327, 2421 Sokolova, E., 261 Sokolovskii, S. A., 709 Sokolvskii, Y. S., 854 Sokotov, V. B., 731, 732, 734, 736 Solar, J. P., 208, 1188, 1951, 2852, 2856 Solar, J. R., 116 Solarz, R. W., 859, 1873, 1874, 1875, 1877, 1878 Solatie, D., 3032, 3070 Sole, K. C., 1288, 2762 Solente, P., 939, 981 Soliman, M. H., 3035 Sollman, T., 76, 109 Solnstsev, V. M., 724, 726 Solntseva, L. F., 583, 601 Solodukhin, V. P., 3017, 3067 Solovkin, A. S., 1169 Solov’yova, G. V., 2822 Solt, G., 2283, 2288 Somerville, L. P., 1653 Somogyi, A., 861

Son, S.-K., 1676, 1679, 1680, 1681, 1682, 1723, 1728 Song, B., 1910 Song, C., 713, 2752, 2753, 2754 Song, C. L., 2753 Song, I., 3087, 3089, 3108 Songkasiri, W., 1814, 3179, 3182 Sonnenberg, D. C., 2934 Sonnenberg, J. L., 1916, 1922, 1925, 1926 Sonnenberg, L. B., 3150 Sonnenberger, D. C., 1957, 1958, 2124, 2479, 2821, 2822, 2824, 2827, 2837, 2839, 2840 Sontag, W., 3404, 3405, 3406 Sood, D. D., 1033, 1170, 2202, 2578 Sopchyshyn, F. C., 3322 Sorantin, H., 833 Sorby, M. H., 66 Sorrell, D. A., 2699 Sorsa, A., 3304 Sostero, S., 542, 2439 Sotobayashi, T., 182 Soto-Guerrero, J., 3046 Soubeyroux, J. L., 65, 66, 69, 71, 72 Souka, N., 176, 182, 184, 185 Souley, B., 2458 Soulie, E., 520, 2082, 2245, 2251 Souron, J. P., 110 Sousanpour, W., 39 Souter, P. F., 576, 1988, 1989, 1990, 2185 Southon, J., 3300 Soverna, S., 1662, 1664, 1685, 1713, 1714, 1716, 1732 Sowby, F. D., 3403 Soya, S., 608, 609 Spaar, M. T., 1542, 1543, 2270 Spadini, L., 3165, 3166, 3167 Spahiu, K., 718, 719, 722, 726, 727, 728, 739, 744, 745, 767, 768, 769, 771, 881, 888, 891, 989, 1008, 1019, 1021, 1045, 1047, 1048, 1085, 1086, 1087, 1098, 1100, 1101, 1110, 1111, 1117, 1118, 1131, 1147, 1148, 1149, 1150, 1155, 1157, 1158, 1162, 1167, 1169, 1170, 1171, 1180, 1181, 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2133, 2136, 2137, 2140, 2142, 2144, 2145, 2151, 2152, 2154, 2155, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2170, 2171, 2173, 2174, 2175, 2182, 2186, 2187, 2193, 2194, 2195, 2197, 2199, 2200, 2201, 2204, 2206, 2538, 2576, 2578, 2582, 2583, 3206, 3213, 3347 Spangberg, D., 118 Spear, K. E., 1000, 1018, 1019 Specht, H. J., 1880, 1881, 1884 Spedding, F. H., 61, 329, 332, 336, 448, 841, 2529, 3110, 3246

I-266

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Speer, J. A., 275 Spence, R., 2583 Spence, R. W., 5, 1577 Spencer, A. J., 297 Spencer, C. M., 2966 Spencer, H., 3413 Spencer, R. W., 1622 Spencer, S., 596, 1907, 1921, 1922, 1923, 2528, 3102, 3113, 3123 Speva´ckova, V., 176 Spiegelmann, F., 1909 Spiegl, A., 2851 Spiegl, C. J., 3354 Spiers, F. W., 3401 Spinks, J. W. T., 1144 Spirelet, J. C., 725 Spiridonov, V. P., 1681 Spirlet, C., 207 Spirlet, J. C., 34, 35, 69, 73, 161, 191, 192, 193, 204, 343, 412, 718, 719, 720, 739, 742, 743, 744, 792, 1017, 1019, 1023, 1050, 1052, 1055, 1286, 1297, 1299, 1300, 1304, 1328, 1403, 1410, 1411, 1412, 1413, 1458, 1785, 1787, 2115, 2205, 2249, 2267, 2268, 2283, 2315, 2370, 2381, 2411, 2695, 2699 Spirlet, M. R., 102, 108, 431, 451, 470, 552, 553, 737, 1168, 2255, 2418, 2441, 2471, 2472, 2474, 2475, 2476, 2477, 2478, 2479, 2484, 2489, 2490, 2655, 2808, 2815, 2816, 2817, 2818, 2827, 2829 Spirlet, T. E., 725 Spiro, T. G., 1952, 2253 Spiryakov, V. I., 735, 739, 744, 747, 2431 Spiryakov, V. O., 2595 Spitsyn, V. I., 180, 184, 188, 209, 214, 218, 219, 224, 226, 345, 346, 366, 372, 373, 374, 375, 383, 719, 720, 753, 1113, 1118, 1156, 1325, 1326, 1327, 1329, 1338, 1367, 1368, 1416, 1429, 1430, 1433, 1463, 1473, 1515, 1547, 1548, 1549, 1607, 1612, 1629, 1636, 1933, 2525, 2526, 2527, 3124 Spjuth, L., 1285, 2584, 2659, 2674 Spoetl, C., 3163, 3164 Spoor, N. L., 3366, 3383, 3424 Sposito, G., 3152 Spo¨tl, C., 291 Spotswood, T. M., 620 Sprague, J., 3354 Spriet, B., 876, 890, 963 Sprilet, J. C., 719, 720 Springer, F. H., 1427 Spurny, J., 2633 Spu¨th, L., 2761 Squires, G. L., 2232 Sreenivasan, N. L., 3052 Srein, V., 264, 281

Srinivasan, B., 2655, 2738, 2739 Srinivasan, N. L., 1033 Srinivasan, P., 2669 Srinivasan, R., 2695 Srinivasan, T. G., 2684, 3052 Sriram, S., 1294, 2658, 2659 Srirama Murti, P., 355 Srivastava, R. C., 2980 Sriyotha, U., 389, 1069 St. John, D. S., 25 Staatz, M. H., 292 Stabin, M., 43 Stackelberg, M. V., 66 Stacy, R. G., 2633 Stadlbauer, E., 396, 1352 Stadler, S., 1314, 1340, 1365, 1366, 1367, 2546 Stafford, R. G., 988 Stafsudd, O. M., 763, 764, 2089 Stahl, D., 1028 Stakebake, J. L., 973, 974, 976, 977, 978, 1035, 3199, 3201, 3207, 3208, 3211, 3212, 3213, 3215, 3216, 3217, 3218, 3220, 3221, 3222, 3223, 3225, 3227, 3228, 3229, 3230, 3231, 3232, 3233, 3234, 3235, 3242, 3249, 3251, 3253, 3254, 3257, 3259, 3260 Stalinski, B., 335, 338, 339 Stalinski, S. P, 338 Stalnaker, N., 2633, 2634 Stambaugh, C. K., 901 Stan, M., 928 Standifer, E. M., 1319, 2592 Standifer, R. L., 855 Stanik, I. E., 214 Stannard, J. N., 3340, 3424 Stanner, J. W., 227 Stanton, H. E., 1626 Stapfer, G., 818 Stapleton, H. J., 203, 2065, 2241, 2262 Star, I., 1352 Starchenko, V., 856, 2684, 2685 Starikova, Z. A., 2442 Staritzky, E., 472, 474, 1109, 1168, 1312, 1319, 1322, 1326, 2427, 2429, 2431, 2432, 2434 Stark, P., 2633 Starks, D. F., 1188, 2486, 2488, 2851 Starks, D. V., 116 Starodub, G. Y., 822 Staroski, R. C., 2642 Stary, I., 1352, 1629 Stary, J., 1352, 1477, 1509, 1550, 1551, 1552, 2575, 2580, 2650 Starynowicz, P., 438, 454 Stather, J. W., 1179, 3340, 3354, 3415, 3416, 3420, 3424 Staudhammer, K. P., 876, 877, 878 Staufer, M., 1906 Stauffert, P., 1957, 1958, 2841

Author Index

I-267

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Staun Olsen, J., 100 Staundenmann, J. L., 96 Staunton, G. M., 485, 518 Stavsetra, L., 1666, 1695, 1702, 1717, 1735, 1737 Staz, H., 1913 Stchouzkoy, T., 195, 196, 197, 216, 218, 225, 229, 230 Steadman, R., 67, 71 Steahly, F. L., 63 Stech, D. J., 2686 Stecher, H. A., 2840 Stecher, P., 69, 72 Steeb, S., 2392, 2393 Steed, J. W., 2452 Steel, A., 3163 Steemers, T., 1033 Steers, E. B. M., 1116 Steglich, F., 719, 720, 2333, 2342, 2347, 2352 Steidl, D. V., 1080, 1082, 1083, 1090, 1092 Steiglitz, L., 2801 Stein, L., 32, 180, 201, 207, 2418, 2420, 2425, 2695 Stein, P., 1952, 2253 Steinberger, U., 2360 Steindler, M. A., 2655, 2739 Steindler, M. J., 731, 732, 733, 1080, 1082, 1083, 1088, 1089, 1090, 1092, 1281, 2084 Steiner, J. J., 407 Steiner, M. J., 2239, 2359 Steinfink, H., 1023, 1053 Steinhaus, D. W., 1845 Steinhof, A., 1881, 1884 Steinle, E., 1426 Steinru¨cke, E., 116, 2865 Stemmler, A. J., 2591 Stenger, L., 1312, 1315, 1469 Stepanov, A. V., 41, 787, 788, 1352, 1353, 1405, 1433, 1476, 1477, 1478, 1550, 1551, 2532, 2546, 2557, 2563, 3034 Stepanov, D. A., 787 Stepanova, E. S., 2583 Stephanou, S. E., 1271, 1322, 1323, 1333, 1366, 1402, 1410 Stephen, J., 190 Stephens, D. R., 1297, 1299, 3255 Stephens, F. M., Jr., 309 Stephens, F. S., 1582 Stephens, W. R., 719 Stephens-Newsham, L. G., 3057 Stepushkina, V. V., 1449, 2637 Sterling, J. T., 352 Stern, C. L., 2479, 2913, 2924, 2933, 2938, 2984, 2986, 2990, 2997, 2998, 2999 Stern, D., 2912, 2924 Stern, E. A., 3088 Sternal, R. S., 1959, 1993, 2479, 2892, 2893

Sterne, P. A., 986, 3095 Sterner, S. M., 127, 128, 130, 131, 2549, 3136, 3137 Sterns, M., 389 Stetzer, O., 1588, 1590, 1840, 1877 Steunenberg, R. K., 869, 908, 950, 1080, 1086, 1088, 1090, 1091, 1513, 2693, 2708, 2709, 2710, 2711, 2712, 2713 Stevens, C. M., 1577, 3069 Stevens, K. W. H., 2036, 2039 Stevens, M. F., 920, 921, 943, 968, 970, 971 Stevens, W., 3343, 3350, 3353, 3355, 3359, 3360, 3361, 3362, 3364, 3365, 3366, 3370, 3373, 3374, 3375, 3376, 3377, 3378, 3379, 3381, 3382, 3385, 3388, 3398, 3399, 3403, 3404, 3414, 3415, 3416, 3420 Stevenson, C. E., 2692 Stevenson, F. J., 3150 Stevenson, J. N., 1084, 1093, 1096, 1397, 1403, 1410, 1411, 1412, 1415, 1417, 1420, 1421, 1457, 1460, 1464, 1465, 1468, 1470, 1480, 1520, 1530, 1532, 2315, 2416, 2417 Stevenson, P. C., 19, 28, 29, 180, 3281 Stevenson, R. J., 3409 Stevenson, R. L., 2730 Stevenson, S. N., 1530, 1533 Steward, L. M., 3220 Stewart, D. C., 1114, 1404 Stewart, D. F., 562 Stewart, G. R., 192, 333, 334, 335, 719, 720, 947, 948, 949, 967, 968, 1784, 1790, 2239, 2312, 2315, 2333, 2350, 2352, 2353, 2372 Stewart, H. B., 2733 Stewart, J. L., 2247, 2256, 2260, 2876, 2879 Stewart, J. M., 259, 282 Stewart, K, 3255 Stewart, K., 3253, 3254 Stewart, M. A. A., 1184, 1312, 1315 Stewart, W. E., 2532 Stieglitz, L., 1423 Stiffler, G. L., 996 Still, E. T., 3355, 3366 Stirling, C., 639, 3327 Stirling, W. G., 2234, 2237, 2286 Stites, J. G., Jr., 34 Stoewe, K., 417, 418, 420 Stoffels, J. J., 3313, 3315 Stohl, F. V., 261, 292 Stokeley, J. R. J., 1323, 1324, 1361 Stokely, J. R., 747, 1473, 1474, 1479, 1480, 1481, 1547, 1548, 2527, 3125 Stokinger, H. E., 3354 Stoll, H., 34, 1676, 1679, 1898, 1908, 1918, 1920, 1937, 1943, 1944, 1947, 1949, 1951, 1959, 2148

I-268

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Stoll, W., 1132 Stollenwerk, A., 2251, 2260 Stollenwerk, A. H., 730, 763, 766, 2260, 2261 Stoller, S. M., 530, 2730 Stolzenberg, H., 1735 Stone, B. D., 34 Stone, F. G. A., 2889 Stone, H. H., 390 Stone, J. A., 190, 203, 425, 431, 435, 439, 469, 749, 750, 751, 752, 793, 1188, 1189, 1472, 1946, 2229, 2230, 2241, 2253, 2256, 2257, 2258, 2259, 2260, 2261, 2262, 2264, 2267, 2268, 2486, 2488, 2595, 2695, 2801, 2803, 2815, 2819, 2843, 2851, 2853, 2855, 2856 Stone, R. E., 1631, 1633, 1635, 1636, 1858 Stone, R. S., 3339, 3413 Stoneham, A. M., 39 Storey, A. E., 1169 Storhok, V. W., 1011, 1018, 1019, 1022 Storms, E. K., 68, 365, 366, 744, 1004, 1008, 1018, 1019, 1028, 2114, 2195, 2196, 2197, 2198, 2199, 2200 Storvick, T. S., 717, 1270, 2134, 2135, 2695, 2696, 2697, 2698, 2699, 2700, 2715, 2719, 2720, 2721 Stoughton, R. W., 63, 115, 175, 188, 256 Stout, B., 2443 Stout, B. E., 778, 781, 782, 1181, 2386, 2387, 2572, 2586, 2594, 2596 Stout, M. G., 964, 972, 973 Stover, B. J., 3340, 3343, 3350, 3351, 3353, 3356, 3358, 3359, 3360, 3361, 3362, 3364, 3365, 3366, 3375, 3376, 3377, 3378, 3379, 3385, 3388, 3396, 3398, 3399, 3405, 3424 Stover, J. C. N., 3343 Sto¨we, K., 1054, 2413 Stoyer, M. A., 14, 1654, 1719, 1736, 1738 Stoyer, N. J., 14, 1114, 1182, 1654, 1664, 1684, 1693, 1694, 1695, 1706, 1716, 1719, 1736, 1738 Strachan, D. M., 2760 Stradling, G. N., 1179, 2591, 3354, 3361, 3413, 3415, 3416, 3419, 3420, 3421 Straka, M., 578, 1933, 1939, 1940, 1941, 1942, 1976 Strand, P., 3063 Strasser, A., 1028 Strassmann, F., 4, 164, 169, 255 Stratton, R., 1071 Stratton, R. W., 1033 Straub, T., 2479, 2834, 2835, 2913, 2925, 2927, 2930, 2932, 2935, 2936, 2940, 2958, 2984, 2987 Straub, T. R. G., 2913, 2933, 2987 Straumanis, M. E., 61 Strazik, W. F., 2564, 2565

Strebin, R. S., 1409, 1432, 1434 Strec¸k, W., 422, 430, 431, 451 Street, J., 2635, 2670 Street, K., 2538, 2562, 2580 Street, K. J., 1585 Street, K., Jr., 5, 1508, 1916, 2635 Street, R. S., 344, 389, 391, 392, 1027, 1030, 1031, 1070, 1071, 2389, 2395 Strehlow, R. A., 1104 Streicher, B., 1654, 1719, 1720, 1738 Streitweiser, A., 208, 630, 1188, 1189, 1894, 1943, 1948, 1951, 2252, 2253, 2488, 2851, 2852, 2855, 2856 Streitweiser, A., Jr., 68, 116, 1188, 1802, 1943, 1951, 1952, 2485, 2486, 2488, 2851, 2852, 2856 Strek, W., 450, 2230, 2259 Strellis, D. A., 185, 186, 815, 1447, 1582, 1662, 1684, 1693, 1699, 1701, 1705, 1711, 1712, 1713, 1716, 1717, 1718 Strelow, F. W., 3061 Streubing, V. O., 1302 Strickert, R. G., 2546, 2547, 3247 Stricos, D. P., 225 Strietelmeier, B. A., 3022, 3175, 3181 Striganov, A. R., 1847, 1848 Stringer, C. B., 189 Stringham, W. S., 172 Strittmatter, R. J., 575, 1191, 1363, 1952, 1954, 1955, 1956, 1957, 1958, 1962, 1966, 2803, 2918 Strnad, J., 2633 Strnad, V., 1507 Strobel, C., 78, 84 Strohal, P., 3306 Strohecker, J. W., 490 Stromatt, R. W., 791 Stromberg, H. D., 1297, 1299 Stromsnes, H., 1918, 1919 Strong, J. C., 3354 Stronski, I., 191, 1352, 1431 Strotzer, E. F., 63, 96, 100, 413 Stroupe, J. D., 530, 560, 2421 Strouse, C. E., 2077, 2232, 2415 Strovick, T. S., 2134, 2135 Strub, E., 185, 186, 1447, 1687, 1699, 1700, 1705, 1710, 1718 Struchkov, Y. T., 746, 747, 748, 749, 2434, 2595, 2859 Struchkov, Yu. T., 2439, 2442 Struchkova, M. I., 105 Struebing, V. O., 892, 896, 897, 901, 905, 906, 932, 936, 1302 Strumane, R., 343 Struminska, D., 3014, 3017 Strunz, H., 269 Struss, A. W., 83 Strutinsky, V. M., 1661, 1880

Author Index

I-269

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Struxness, E. G., 3346, 3351, 3372, 3375, 3376 Stryer, L., 631 Stuart, A. L., 2256, 2477, 2480, 2812, 2813, 2829, 2830 Stuart, W. I., 283, 997, 998, 1000, 1001 Stubbert, B. D., 2990 Studd, B. F., 115 Studier, M. H., 5, 53, 164, 172, 175, 219, 704, 1577, 1622, 3016 Studier, N. H., 822, 824 Stuit, D., 3024, 3284, 3296 Stuit, D. B., 3282, 3285, 3296, 3307 Stults, S. D., 2473, 2561, 2802, 2805, 2806 Stump, N., 1467 Stump, N. A., 1453, 1467 Stumpe, R., 787, 1114, 3043 Stumpf, T., 2587, 3114 Stumpp, E., 376, 377, 378, 382, 505, 510, 511, 524 Stunault, A., 2234 Stupin, V. A., 2118 Sturchio, N. C., 291, 3163, 3164, 3183 Sturgeon, G. D., 506, 507, 1107 Stuttard, G. P., 385, 388 Su, S. J., 1908 Suarez Del Rey, J. A., 1432, 1433 Subbanna, C. S., 2202 Subbotin, V. G., 14, 989, 996, 1653, 1654, 1707, 1719, 1736, 1738 Subotic, K., 14, 1653, 1654, 1719, 1736, 1738 Subrahmanyam, V. B., 164 Subramanian, M. A., 942 Subramanian, M. S., 1174 Suckling, C. W., 504 Sudakov, L. V., 724, 726, 1317, 1466 Sudarikov, B. N., 303 Sudnick, D. R., 1327 Sudo, T., 2953, 2969 Sudowe, R., 815, 1662, 1664, 1666, 1685, 1695, 1701, 1702, 1712, 1713, 1714, 1716, 1717, 1735, 1737 Sueki, K., 164, 1266, 1267, 1696, 1718, 1735 Sueyoshi, T., 397 Suganuma, H., 1409 Sugar, J., 33, 60, 859, 1452, 1513, 1590, 1633, 1639, 1646, 1845, 1874, 1875, 1877, 1878, 1879 Suger, J., 2038 Sugimoto, M., 2966 Sugisaki, M., 395, 397 Sugiyama, K., 406, 407 Suglobov, D. N., 548, 549, 555, 556, 571, 575, 750, 1116, 1361, 2594, 2800, 3111, 3122 Suglobova, I. G., 86, 88, 89, 93, 424, 428, 429, 430, 431, 436, 437, 440, 450, 454, 470, 471, 473, 475, 476, 495, 510, 511, 571

Sugo, Y., 2658, 2659 Sukhov, A. M., 14, 1653, 1654, 1707, 1719, 1736, 1738 Suksi, J., 273 Sulcek, Z., 3278 Sullenger, D. B., 1033, 1034, 2395 Sullivan, J., 3206, 3213 Sullivan, J. C., 606, 607, 612, 615, 704, 718, 719, 722, 726, 727, 728, 739, 744, 745, 748, 759, 764, 767, 768, 769, 770, 771, 781, 822, 824, 881, 888, 891, 989, 1008, 1019, 1021, 1045, 1047, 1048, 1085, 1086, 1087, 1098, 1100, 1101, 1110, 1111, 1113, 1117, 1118, 1129, 1131, 1147, 1148, 1149, 1150, 1155, 1157, 1158, 1159, 1160, 1162, 1164, 1166, 1167, 1169, 1170, 1171, 1176, 1180, 1181, 1325, 1326, 1335, 1337, 1356, 1368, 1369, 1416, 1424, 1430, 1473, 1474, 1475, 1774, 1776, 1778, 1923, 1931, 1933, 2077, 2094, 2096, 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2131, 2133, 2136, 2137, 2140, 2142, 2144, 2145, 2151, 2152, 2154, 2155, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2170, 2171, 2173, 2174, 2175, 2182, 2186, 2187, 2193, 2194, 2195, 2197, 2199, 2200, 2201, 2204, 2206, 2527, 2531, 2538, 2553, 2558, 2562, 2563, 2571, 2576, 2578, 2582, 2583, 2589, 2594, 2595, 2596, 2597, 2599, 2601, 2602, 2603, 2604, 2605, 2606, 2760, 3016, 3035, 3087, 3112, 3125, 3170, 3347 Sullivan, M. F., 1507 Summerer, K., 1738 Summerson, W. H., 3362 Sumner, S. A., 3354 Sun, J., 2831 Sun, Y., 2100, 2880, 2881 Sundaram, S., 1086 Sundararajan, K., 1988 Sundaresan, M., 58, 2580 Sunder, S., 274, 289, 371 Sundman, B., 351, 352 Suner, A., 187 Sung-Ching-Yang, G. Y., 164 Sung-Yu, N. K., 2801, 2851 Suortti, P., 2381, 2382, 2383 Surac, J. G., 184 Suraeva, N. I., 1516, 1683 Suranji, T. M., 123, 2549 Surbeck, H., 133 Suresh, G., 2666, 2667, 2739 Surls, J. P., 1291, 2636 Surls, J. P., Jr., 1509 Suryanarayana, S., 1033 Sus, F., 785

I-270

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Suski, W., 333, 414, 416, 719, 720, 743, 2238, 2413 Suskin, M. A., 2016, 2035 Suslick, K. S., 2464, 2465 Suslova, K. G., 1821, 3282 Susuki, H., 2934 Sutcliffe, P., 949 Sutcliffe, P. W., 939 Sutter, C., 2234, 2237 Sutter, J. P., 2256 Sutterlin, U., 3398 Suttle, J. F., 490 Sutton, A. L., Jr., 389, 396 Sutton, J., 2532 Sutton, S., 473 Sutton, S. R., 270, 291, 861, 3039, 3087, 3089, 3095, 3163, 3164, 3172, 3175, 3176, 3177, 3183 Suvorov, A. V., 82 Suzuki, A., 589, 595, 613, 712, 713, 795, 1921, 1923, 1991, 2538, 2594, 2738, 3102, 3105, 3111, 3112, 3113, 3122, 3123 Suzuki, H., 1957, 1958, 1981, 2479, 2837, 2839 Suzuki, K., 622, 718 Suzuki, M., 1398, 2681, 2684 Suzuki, S., 30, 40, 180, 209, 217, 224, 784, 1477, 1548, 2659 Suzuki, T., 100, 182, 428, 436, 440, 444, 451, 719, 720, 1625 Suzuki, Y., 717, 718, 743, 1004, 1018, 2153, 2157, 2201, 2695, 2698, 2715, 2716, 2724, 2725, 3179, 3180, 3181 Svane, A., 1023, 1044, 2347, 3211 Svantesson, I., 2767 Svantesson, J., 184 Svantesson, S., 1286, 2672 Svec, F., 851 Sveen, A., 347, 354, 357, 359 Svergensky, D. A., 2132 Sveshnikova, L. B., 2452 Sviridov, A. F., 1484 Svirikhin, A. I., 1654, 1719, 1720, 1738 Swain, K. K., 180 Swallow, A. G., 115 Swaney, L. R., 506 Swang, O., 2169 Swanson, B. I., 732, 733, 734 Swanson, J. L., 126, 127, 130, 728, 767, 769, 843, 941, 1109, 1282, 2740 Swanton, S. W., 301, 3103, 3152, 3154, 3155 Swaramakrishnan, C. K., 1058, 1059, 1060 Swatloski, R. P., 2691 Sweedler, A. R., 63 Swepston, P. N., 2866, 2918, 2924 Swiatecki, W. J., 1653, 1661, 1738 Swift, D. J., 3017 Swift, M. N., 3353, 3356, 3362, 3366, 3370, 3378, 3386, 3395, 3407, 3424

Swift, T. J., 2530 Swihart, G. H., 268 Sykora, R. E., 1173, 1531 Sylva, R. N., 119, 120, 121, 123, 124, 126, 2575 Sylvester, P., 3326 Sylwester, E., 1684, 1693, 1706, 1716 Sylwester, E. R., 185, 186, 301, 815, 932, 967, 1445, 1447, 1582, 1662, 1664, 1684, 1693, 1694, 1695, 1699, 1705, 1706, 1709, 1716, 1718, 3152, 3154, 3155, 3158 Symons, M. C. R., 2530 Szabo, A., 1903 Szabo´, G., 3023 Szabo´, Z., 580, 581, 589, 590, 591, 596, 597, 602, 604, 605, 607, 608, 609, 610, 612, 614, 616, 617, 618, 621, 625, 1156, 1923, 1924, 2576, 2578, 2579, 2582, 2587, 2592, 2593, 3101, 3102, 3103, 3104, 3105, 3120, 3121, 3126, 3127, 3128, 3129, 3132, 3144 Szalay, A., 3166 Szalay, P. G., 1908, 1909 Szczepaniak, W., 425, 439, 444, 447, 448, 455, 469, 475, 476, 478, 479, 495, 2257, 2258 Sze, K. H., 1962 Szeglowski, Z., 30 Szempruch, R., 3253, 3254 Szilard, B., 76 Szklarz, E. G., 68 Szostak, F., 3050 Szotek, Z., 1023, 1044, 2347, 3211 Szwarc, R., 352, 357, 365 Szymanski, J. T., 103, 113 Szymanski, Z., 1661 Szytula, A., 69, 70, 73 Tabata, K., 77 Tabuteau, A., 87, 92, 391, 460, 511, 728, 730, 792, 1067, 1068, 1312, 1321, 1359, 1360, 2431, 2432 Tacev, T., 1507 Tachibana, T., 352 Tachimori, S., 1049, 1283, 1286, 1363, 1370, 1554, 2658, 2659, 2675, 2738, 2760 Tada, M. L., 3317, 3318 Tagawa, H., 280, 306, 355, 368, 369, 373, 377, 378, 380, 383, 391, 392, 393, 395, 396, 409, 490, 1317, 1318, 2199, 2411 Tagirov, B. R., 2191, 2192 Tagliaferri, A., 1196, 1198, 2080, 2085, 2086, 2561 Taguchi, M., 366 Tague, T. J., 1977, 1978, 1983 Tague, T. J., Jr., 2894 Tahvildar-Zadeh, A., 2343, 2344, 2345 Tai, D., 1507

Author Index

I-271

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Taibi, K., 3066 Taillade, J. M., 133 Tailland, C., 932, 933 Taira, H., 631 Taire, B., 1530, 1531, 1533 Tait, C. D., 270, 289, 291, 580, 595, 602, 620, 621, 704, 763, 766, 851, 861, 932, 1041, 1043, 1112, 1116, 1117, 1154, 1155, 1156, 1162, 1164, 1166, 1359, 1370, 1925, 1926, 1927, 1928, 1931, 2427, 2428, 2429, 2450, 2451, 2464, 2583, 2607, 3035, 3087, 3108, 3109, 3112, 3113, 3115, 3118, 3123, 3125, 3126, 3127, 3128, 3130, 3131, 3133, 3134, 3136, 3160, 3161, 3164, 3167, 3170, 3171, 3175, 3210 Tajik, M., 452 Takagi, E., 226 Takagi, J., 215, 216, 224 Takagi, S., 100 Takahashi, K., 164, 1056, 1057, 2154, 3043, 3045 Takahashi, M., 727, 760 Takahashi, N., 717, 2134, 2135, 2695, 2696, 2697, 2698, 2699, 2700, 2719 Takahashi, S., 356 Takahashi, Y., 354, 795, 3024 Takaku, A., 3059, 3062, 3068, 3072 Takaku, Y., 789, 790, 3017, 3062 Takanashi, M., 2743 Takano, H., 2693 Takano, M., 1018, 1421, 2724 Takano, Y., 294 Takashima, Y., 1294, 1295, 2749 Takats, J., 2819, 2821, 2826, 2836, 2840, 2880, 2881, 2883, 2885, 2912 Takayama, H., 789, 790, 3059, 3062, 3068, 3072 Takayanagi, S., 407 Takeda, M., 727 Takegahara, K., 100 Takeishi, H., 706, 708, 1407, 1424, 2680, 2681, 2683, 3043, 3045 Takemura, H., 2457, 2460 Takeshita, K., 2675 Takeuchi, H., 382, 2245 Takeuchi, K., 576, 577, 1935, 1936, 2165 Takeuchi, M., 2738 Takeuchi, R., 2953, 2966 Takeuchi, T., 407 Takizawa, Y., 1822 Takizuka, T., 2723 Talbert, W., 1665 Talbot, R. J., 822, 3342, 3346, 3353, 3372, 3373 Tallant, D. R., 1292 Tallent, O., 2701 Talley, C. E., 412

Talmont, X., 2731 Tamaura, Y., 1292 Tamborini, G., 3062 Tame, J. R. H., 630 Tamhina, B., 182 Tamm, K., 2602 Tan, B., 795 Tan, F., 266 Tan Fuwen, 231 Tan, J.-h., 1018 Tan, T.-Z., 1285 Tan, X.-F., 1285 Tanabe, K., 76 Tanaka, H., 394, 2695, 2698 Tanaka, K., 116, 2865 Tanaka, O., 1019 Tanaka, S., 339, 625, 769, 795, 2553, 2738, 3022, 3024 Tanaka, X., 2762 Tanaka, Y., 76, 1281, 1282, 1286, 2743, 2747, 2761 Tanamas, R., 384, 385, 386, 393, 1303, 1312 Tananaev, I. G., 161, 709, 770, 1110, 1113, 1133, 1156, 1312, 1314, 1340, 1341 Tandon, J. P., 2587 Tandon, L., 3222 Tanet, G., 769, 774 Tang, C. C., 2238 Tang, W. J., 2982 Tani, B., 272, 343, 357, 358, 1465, 1469, 1470, 2417, 2422 Taniguchi, K., 389 Tanikawa, M., 164 Tanke, R. S., 2966 Tannenbaum, A., 3340, 3380, 3423 Tannenbaum, I. R., 1080, 1081, 1083, 1084, 1086, 1088, 1090, 1091, 2421, 2426 Tanner, J. P., 1423 Tanner, P., 482, 2054, 2066 Tanner, P. A., 472, 477 Tanner, S. P., 1352, 1427, 1454 Tanner, S. R., 1592 Tanon, A., 892, 905, 906, 907 Tanouchi, N., 2953 Tao, Z., 3062 Taoudi, A., 88, 91 Tapuchi, S., 719, 720 Tarafder, M. T. H., 93 Taranov, A. P., 727, 2136 Tarrant, J. R., 1423, 1454, 1592, 1636, 1639, 1640, 1644, 1659, 2127, 2526, 2561, 2585 Tashev, M. T., 2441 Tasker, I., 2193 Tasker, I. R., 357, 358 Tatarinov, A. N., 14, 1654 Tate, R. E., 490, 876, 880, 937, 939, 958, 959, 960, 961

I-272

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Tateno, J., 368, 369, 373, 378, 383, 396 Tatewaki, H., 1897, 1938, 1992 Tatsumi, K., 378, 1917, 1954, 1956, 1957, 1958, 2400, 2472, 2484, 2825, 2826, 2841 Taube, H., 592, 619, 622, 1133, 2607 Taube, M., 988 Taut, S., 1447, 1451, 1524, 1593, 1628, 1662, 1684, 1699, 1708, 1709, 1711, 1712, 1716 Tawn, E. J., 1821 Taylor, A. D., 2278, 2279, 2283, 2284, 2285 Taylor, A. J., 342, 357 Taylor, B. F., 2966 Taylor, C. D., 2035 Taylor, D. M., 988, 1179, 1816, 1823, 3024, 3340, 3350, 3351, 3352, 3354, 3359, 3360, 3361, 3362, 3364, 3365, 3368, 3371, 3372, 3373, 3374, 3375, 3376, 3377, 3378, 3379, 3385, 3387, 3388, 3396, 3398, 3399, 3403, 3408, 3410, 3411, 3413, 3414, 3415, 3416, 3420, 3422, 3424 Taylor, G. N., 1507, 1823, 3340, 3343, 3349, 3350, 3353, 3355, 3360, 3366, 3370, 3375, 3381, 3382, 3396, 3398, 3399, 3401, 3403, 3404, 3405, 3414, 3415, 3416, 3420, 3424 Taylor, J. C., 78, 86, 102, 106, 264, 283, 342, 357, 358, 423, 425, 435, 439, 445, 453, 455, 469, 473, 474, 475, 478, 495, 498, 502, 503, 511, 515, 529, 530, 536, 543, 544, 560, 567, 568, 569, 573, 594, 944, 949, 950, 1107, 2394, 2414, 2415, 2417, 2418, 2420, 2421, 2423, 2424, 2426, 2429, 2430 Taylor, J. M., 1009 Taylor, K. M., 1028, 1030 Taylor, M., 55, 103 Taylor, N. J., 2430 Taylor, P., 348 Taylor, R., 3279, 3285 Taylor, R. G., 2480, 2812, 2829, 2845 Taylor, R. I., 2273 Taylor, R. J., 711, 712, 760, 761, 1138, 2440, 2757 Taylor, R. N., 3328 Taylor, S. H., 3171 Taylor, S. R., 26, 170 Tazzoli, V., 3167 Tchikawa, S., 1267 Teague, S. V., 3254 Teale, P., 1810 Teaney, P. E., 1049 Teetsov, A., 275 Teherani, D. K., 3057 Teichteil, C., 1909, 1918, 1919, 1931, 1932 Teillac, J., 27, 184, 187

Teillas, J., 164 Teixidor, F., 2655 Tellers, D. M., 2880 Tellgren, R., 475, 478, 479, 495 Telnoy, V. I., 2822 Telouk, P., 3326 Temmerman, W. M., 1023, 1044, 2347, 3211 Temmoev, A. H., 133 Tempest, A. C., 2843 Tempest, P. A., 344, 348, 1035 Temple, R. B., 2735 Templeton, C. C., 106, 107 Templeton, D. H., 67, 71, 78, 82, 83, 106, 116, 208, 423, 542, 580, 1187, 1312, 1313, 1315, 1357, 1358, 1645, 2251, 2256, 2288, 2386, 2395, 2396, 2404, 2405, 2407, 2417, 2418, 2422, 2429, 2434, 2436, 2487, 2488, 2489, 2558, 2853, 2856, 2877, 3088, 3089 Templeton, L. K., 542, 580, 2288, 2404, 2405, 2488, 2853, 3088, 3089 Ten Brink, B. O., 164 Tennery, V. J., 1317, 1318 Teo, B.-K., 3087, 3088, 3091, 3093, 3100, 3117, 3164 Tepp, H. G., 316, 317 Ter Akopian, T. A., 164 Ter Haar, G. L., 116 ter Meer, N., 200, 1312, 1319, 1322, 1323, 1361, 2164, 2427, 2439, 2442 Terada, K., 1028, 1029, 1030, 3207, 3219 Terminello, L. J., 863, 3089, 3101, 3141, 3152, 3156 Teschke, F., 3306 Teshigawara, M., 339 Testa, C., 3030, 3280 Tetenbaum, M., 352, 364, 365, 367, 1029, 1030, 1047, 2146, 2262 Teterin, A. Y., 861 Teterin, A. Yu., 3051 Teterin, E. G., 458, 1079, 1169 Teterin, Y. A., 861, 3142, 3145, 3150 Teterin, Yu. A., 3051 Tetzlaff, R. N., 817 Teuben, J. H., 2924 Teufel, C., 107 Tevebaugh, R., 80 Thakur, A. K., 114 Thakur, L., 114 Thakur, N. V., 1275 Thalheimer, W., 164 Thalmeier, P., 2347 Thamer, B. J., 862, 897 Tharp, A. G., 69, 72, 78, 2407 Thayamballi, P., 1023, 2364 Thein, M., 783 Theisen, R., 1070, 1071, 1072 Theng-Da Tchang, 193

Author Index

I-273

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Theobald, W., 1880, 1881, 1882, 1883, 1884 Thern, G. G., 185, 187 The´venin, T., 730, 740, 741, 742, 792, 1017, 1022, 1052, 1054, 2409, 2413, 2414, 2426, 2427 Thewalt, U., 505, 510 Thewlis, J., 2385 Theyssier, M., 3034, 3064 Theyyunni, T. K., 712, 1282, 2743, 2745, 2757 Thi, Q., 1732 Thibault, Y., 293 Thibaut, E., 420, 423, 425, 435, 437, 457, 470, 473, 474, 478, 502, 509, 514, 515, 516, 538, 544, 551 Thied, R. C., 854, 2686, 2690 Thiel, W., 89, 93, 94 Thiele, K.-H., 116 Thieme, M., 3142, 3145, 3150 Thies, S., 2352 Thies, W. G., 3398 Thiriet, C., 2143 Thiyagarajan, P., 840, 1152, 2649, 2652 Thode, H. G., 823 Thole, B. T., 2236 Thoma, D. J., 929 Thoma, R. E., 84, 85, 86, 87, 88, 89, 90, 91, 424, 446, 459, 460, 461, 462, 463, 464, 465, 487, 489, 1468, 2416 Thomas, A. C., 128, 785 Thomas, C. A., 988 Thomas, D. M. C., 3254, 3255 Thomas, J. D. R., 3029 Thomas, J. K., 2199, 2202 Thomas, J. L., 750, 2469 Thomas, M., 3017, 3027 Thomas, O., 2657 Thomas, R. A. P., 1818 Thomas, W., 988, 3020 Thomason, H. P., 787, 3043, 3044 Thomassen, L., 2391 Thome´, L., 340, 348 Thomke, K., 76 Thompson, G. H., 817, 1397, 1402, 2653, 2727 Thompson, H. A., 3094, 3102, 3127, 3139, 3152, 3155, 3158 Thompson, J. D., 406, 967, 968, 1784, 1790, 2239, 2352, 2353, 2372 Thompson, J. L., 1152, 3036, 3288, 3314 Thompson, K. R., 1968, 1971 Thompson, L., 1966, 2260, 2872, 2874 Thompson, M. A., 974, 3219 Thompson, M. C., 770, 1397, 1411, 1412, 2387, 2388 Thompson, R. C., 172, 174, 182, 215, 226, 768, 769, 775, 1814, 2553, 3340, 3386, 3424 Thompson, S. G., 5, 835, 1444, 1480, 1481, 1508, 1577, 1622, 1624, 1628, 1629,

1630, 1632, 1635, 1661, 2629, 2635, 2638, 2639, 2730 Thomson, B. M., 3409 Thomson, J., 170, 225, 3031 Thomson Rizer, C. L., 3046 Thonstad, J., 2692 Thoret, J., 111, 112, 113 Tho¨rle, P., 33, 1588, 1590, 1662, 1664, 1685, 1687, 1698, 1699, 1700, 1709, 1710, 1713, 1714, 1716, 1718, 1840, 1877, 1879, 1882, 1884 Thorn, R. J., 364, 365, 724, 2148 Thouvenot, P., 1368, 1369, 2062, 2063, 2096, 2263, 2265 Thronley, F. R., 3163 Thuemmler, F., 1070, 1071, 1072 Thue´ry, P., 1262, 1270, 2254, 2449, 2451, 2452, 2456, 2457, 2458, 2459, 2460, 2461, 2462, 2488, 2558 Thulasidas, S. K., 2668 Thuma, B., 6 Tian, G., 2665 Tian, G. X., 1363 Tian, S., 116, 1776, 2240, 2473, 2803, 2816, 2875, 2912, 2984, 2986, 2990 Tibbs, P. A., 1507 Tichy´, J., 347, 354, 357, 359 Ticker, T. C., 1670, 1672, 1673, 1674, 1675, 1676, 1685, 1692 Tiedemann, B. E. F., 1825, 3420 Tiemann, M., 1828 Tiffany-Jones, L., 44 Tikhomir, G. S., 1512 Tikhomirov, V. V., 1484 Tikhomirova, G. S., 1449, 1633, 1636, 2636, 2637 Tikhonov, M. F., 1120, 1128, 1140, 1302 Tikhonov, M. R., 3111, 3122 Tikhonova, A. E., 788, 3034, 3039 Tikkanen, W. R., 2919 Till, C., 2693, 2713 Tilley, T. D., 2832, 2965, 2974 Timerbaev, A., 3024 Timma, D. L., 27 Timofeev, G. A., 744, 1134, 1326, 1329, 1331, 1333, 1334, 1335, 1336, 1416, 1429, 1430, 1446, 1447, 1479, 1480, 1481, 1483, 1484, 1545, 1547, 1559, 2126, 2129, 2131, 2584, 3061 Timofeeva, L. F., 893, 894, 895, 896, 986 Timokhin, S., 1679, 1684, 1708, 1709, 1716 Timokhin, S. N., 1451, 1593, 1625, 1629, 1633, 1635, 1662, 1664, 1684, 1685, 1692, 1693, 1695, 1700, 1706, 1708, 1709, 1713, 1714, 1716, 1720 Ting, G., 176, 188 Ting, K. C., 2668 Tinker, N., 2442

I-274

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Tinker, N. D., 2887 Tinkham, M., 2043 Tinkle, M., 457, 486 Tipton, C. R., Jr., 1030 Tischler, M. L., 3179, 3181 Tishchenko, A. F., 112 Tissue, B. M., 2047, 3322 Titov, V. V., 1082 Tits, J., 2591 Tiwari, R. N., 76, 106 Tjeng, L. H., 861 To, M., 2208, 2211 Tobin, J. G., 967 Tobler, L., 1447, 1662, 1684, 1711, 1712, 1716, 1732 Tobo´n, R., 2315, 2350 Tobo´u, R., 63 Tobschall, H. J., 297 Tochiyama, O., 706, 776, 777, 778, 781, 782, 2099, 2100, 2559, 2578, 2585, 2726, 3287 Todd, P., 1507 Todd, T. A., 1282, 2739, 2741 Toepke, I. L., 64 Toevs, J. W., 996 Toews, K., 2681, 2684 Tofield, B. C., 2153 Togashi, A., 1282, 1408, 2743 Toivonen, H., 1913 Toivonen, J., 580, 581, 2434 Tokarskaya, Z. B., 1821 Tokman, M., 1669 Tokura, Y., 2288 Tolazzi, M., 2584 To¨lg, S., 1881 Tolley, W. B., 1093 Tolmachev, Y. M., 727 Tolmachyov, S. Y., 786 Tolson, D., 3358 Tom, S., 164, 186, 187 Tomas, A. M., 226 Tomat, A., 2586, 2589 Tomat, G., 767, 770, 776, 777, 778, 781, 782, 2441, 2550, 2584, 2585, 2586, 2589 Tomczuk, Z., 2714, 2715 Tomilin, S. V., 735, 739, 747, 749, 1164, 1319, 2129, 2131, 2427, 2431, 2442, 2527, 2595 Tomioka, O., 2678, 2679, 2681, 2684 Tomioka, Y., 2288 Tomiyasu, H., 607, 608, 609, 616, 617, 618, 620, 622, 626, 627, 712, 762, 852, 2633, 2681 Tomkins, F. S., 33, 190, 226, 1295, 1836, 1839, 1842, 1846, 1847, 1871 Tomkowicz, Z., 69, 70, 73 Toms, D. I., 198, 201 Toms, D. J., 164, 173, 176, 179, 213, 224

Tondello, E., 116, 546, 547, 553, 554, 770, 2554 Tondon, V. K., 1058, 1059, 1060, 1061 Tondre, C., 2649, 2657 Tong, J. P. K., 580, 582 Toogood, G. E., 2430 Toops, E. C., 25 Topic, M., 102, 103, 110, 2431 Topp, N. E., 1541, 1591 Topp, S. V., 1813 Toraishi, T., 597, 625, 2587 Torikachvili, M. S., 2352, 2357 Toropchenova, G. A., 175 Torres, R. A., 1114, 1148, 1155, 1160, 1163, 1354, 2583 Torri, G., 2633 Torstenfelt, B., 1803, 1804, 1806, 1807, 1808, 1810 Torstenfelt, N. B., 1152 Toscano, P. J., 2999 Toshiba Denshi Eng KK, 189 Totemeier, T. C., 322, 327 Toth, I., 1166 Toth, K. S., 164 Toth, L., 2688, 2701 Toth, L. M., 1132, 1152, 2087, 2088 Tougait, O., 75, 97, 416, 417, 2413 Tournois, B., 2655 Toussaint, C. J., 373 Toussaint, J., 2633 Toussaint, J. C., 34, 35, 194, 1271, 1304, 1402, 1403, 1410, 1412, 1413 Toussaint, N., 195, 2407, 2408 Tousset, J., 29 Touzelin, B., 353, 391, 392 Towndrow, C. G., 3354 Townes, C. H., 1681 Toyoshima, A., 1445, 1484, 1696, 1718, 1735 Trabalka, J. R., 3287 Tracy, B. L., 3017 Traeger, J., 1507 Traill, R. J., 2434 Trakhlyaev, P. S., 1352 Trammell, G. T., 2234 Tran Kim, H., 1352 Trapeznikov, A. P., 3280 Trauger, D. B., 53, 2733 Trautmann, N., 25, 33, 60, 164, 789, 794, 859, 1296, 1403, 1432, 1433, 1451, 1452, 1513, 1588, 1590, 1662, 1664, 1665, 1666, 1679, 1684, 1685, 1687, 1695, 1699, 1702, 1705, 1708, 1709, 1710, 1713, 1714, 1716, 1717, 1718, 1735, 1738, 1836, 1840, 1875, 1876, 1877, 1879, 1880, 1881, 1882, 1883, 1884, 2018, 2591, 3044, 3047, 3048, 3069, 3320, 3321

Author Index

I-275

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Traverso, O., 542, 2439, 2585, 2586, 2589, 2801 Travis, J. C., 3320 Travnikov, S. S., 1323, 1423, 1471, 1541, 1612, 1625, 1633 Treiber, A., 116, 2814 Treiber, W., 727, 769 Trela, W. J., 967 Tremaine, P. R., 2132, 2133 Tresvyatsky, S. G., 395 Tret’yakov, E. F., 20, 24 Tretyakova, S. P., 6 Treuil, M., 3305 Trevorrow, L., 731, 732, 733, 1082, 1088, 1090, 1091, 1106 Triay, I. R., 861, 1152, 2531, 3036, 3095, 3106, 3111, 3122, 3165, 3169, 3175, 3176, 3177 Trice, V. G., 2692, 2708 Trifonov, I. I., 86, 93 Tripathi, S. N., 2195 Tripathi, V., 2352 Trivedi, A., 3050 Trnka, T. M., 2827 Troc, R., 323, 333, 347, 353, 357, 412, 414, 415, 1055, 2238, 2362, 2413 Trochimczuk, A. Q., 2642, 3283 Trochimczuk, A. W., 2642 Trofimenko, S., 2880, 2883 Trofimov, A. S., 164 Trofimov, T. I., 856, 1422, 1480, 1481, 2678, 2684 Troiani, F., 2633 Tromp, R. L., 167, 187 Trond, S. S., 505, 506 Troost, L., 67, 75, 81, 109, 2408 Trost, B. M., 2982 Trottier, D., 459 Troxel, J. E., 69 Trubert, D., 181, 211, 1671, 1686, 1688, 1700, 1701, 1705, 1711, 1718 Trucks, G. W., 1902 Truitt, A. L., 1322 Trujillo, E. A., 737 Trujillo, V. L., 3263 Trukhlyaev, P. S., 1271, 1352, 1402, 1422, 1423, 1427, 1512 Trunov, V. K., 111, 112, 113, 536, 2434 Trunova, V. I., 372, 374 Truswell, A. E., 458, 484, 485, 1077, 1078, 1079, 1084 Trzebiatowski, W., 335, 377, 470, 471, 491 Trzeciak, M. J., 328, 331 Tsagas, N. F., 3057 Tsai, H. C., 366 Tsai, J.-S., 1507 Tsai, K. R., 76 Tsai, Y.-C., 2888

Tsaletka, R., 1690 Tsang, C. F., 1661 Tsang, T., 2243 Tsapkin, V. V., 575 Tsaryov, S. A., 175 Tschachtli, T., 3066, 3067 Tschinke, V., 1907 Tse, D. S., 2979 Tselichshev, I. V., 2706, 2707, 2708 Tsezos, M., 2669 Tshigunov, A. N., 345, 346, 355, 366 Tsirlin, V. A., 31 Tsivadze, A. Y., 763, 764 Tsivadze, A. Yu., 565 Tso, C., 206, 208 Tso, T. C., 191, 379 Tsoucaris, G., 2449, 2450 Tsoupko-Sitnikov, V., 28, 43 Tsuda, T., 2691 Tsuji, T., 347, 356, 1025, 1026, 2140 Tsujii, M., 1292 Tsukada, K., 164, 1266, 1267, 1445, 1450, 1484, 1696, 1699, 1700, 1710, 1718, 1735 Tsukatani, T., 3328 Tsumura, A., 709, 784, 789, 3327, 3328 Tsupko-Sitnikov, V. V., 28, 43 Tsushima, S., 589, 595, 613, 1921, 1923, 1991, 1992, 2538, 3102, 3105, 3111, 3112, 3113, 3122, 3123, 3128, 3131, 3132 Tsutsui, M., 750, 1802, 2472, 2819, 2820 Tsutsui, S., 792, 2280, 3043 Tsuyoshi, A., 2759, 2760, 2762 Tsvetkov, V. I., 1821 Tsyganov, Y. S., 1447, 1653, 1654, 1662, 1684, 1707, 1711, 1712, 1716, 1719, 1736, 1738 Tsyganov, Yu. S., 1398, 1400 Tsyganov, Yu. Ts., 14 Tsykanov, V. A., 854 Tuan, N. A., 3171 Tuck, D. G., 84, 470, 493, 496, 568, 571, 572, 574 Tucker, C. W., Jr., 2385 Tucker, P. A., 903, 1033 Tucker, P. M., 348 Tucker, T. C., 1452, 1640 Tucker, W., 75, 107 Tuli, J. K., 817 Tuller, H. L., 368, 369 Tul’skii, M. N., 731, 732, 734, 736 Tunayar, A., 2655 Turanov, A. N., 2657 Turchi, E. A., 927 Turchi, P. E. A., 928, 932, 967 Turcotte, R. P., 724, 725, 726, 1464, 1466, 1530, 1536, 1537, 2143, 2389, 2398

I-276

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Tu¨rler, A., 185, 1445, 1447, 1451, 1468, 1593, 1653, 1662, 1664, 1679, 1684, 1685, 1693, 1694, 1695, 1696, 1697, 1698, 1699, 1700, 1701, 1704, 1705, 1706, 1707, 1708, 1709, 1710, 1711, 1712, 1713, 1714, 1716, 1717, 1718, 1720, 1721, 1732 Turler, E. A., 182 Turnbull, A. G., 83, 2424 Turner, G. A., 3359, 3360, 3361, 3364, 3368, 3372, 3373, 3374, 3375, 3376, 3378, 3388 Turner, H. W., 2877 Turos, A., 340, 348, 3065, 3214, 3239, 3251 Turowski, P. N., 3413, 3414, 3418, 3419, 3421 Turteltaub, K. W., 3316 Tutov, A. G., 546 Tverdokhlebov, S. V., 3029 Tverdokhlebov, V. N., 105, 106 Twiss, P., 3327 Tyler, J. W., 340, 344, 348 Tynan, D. E., 314 U. S. Department of Energy, 43 U. S. Geological Survey, 1755 U. S. Nuclear Regulatory Commission, 32 Uchida, Y., 3102, 3131, 3132 Uchiyama, G., 711, 712, 760, 1272, 1273, 1294, 1295, 2757 UCRL, 1312 Udovenko, A. A., 541 Udupa, S. R., 2668, 2669 Ueda, K., 2560, 2590 Ueda, R., 391, 396 Ueki, T., 106, 2429 Ueno, E., 3067 Ueno, F., 89, 95 Ueno, K., 109, 709, 783, 784, 789, 1163, 1312, 1321, 1431 Ugajin, M., 360, 362, 394, 1010 Ugozzoli, F., 2655 Uhelea, I., 13 Uhl, E., 67, 71 Uhlir, L. C., 3414, 3416, 3419 Ukon, I., 407 Ulanov, S. A., 793 Ulehla, I., 1660 Ulikov, I. A., 1337 Ulin, K., 1507 Ullmaier, H., 981, 983 Ullman, W., 3206, 3213 Ullman, W. J., 718, 719, 722, 726, 727, 728, 739, 744, 745, 767, 769, 771, 881, 888, 891, 989, 1008, 1019, 1021, 1045, 1047, 1048, 1085, 1086, 1087, 1098, 1100, 1101, 1110, 1111, 1117, 1118, 1131, 1147, 1148, 1149, 1150, 1155, 1157,

1158, 1161, 1162, 1165, 1166, 1167, 1169, 1170, 1171, 1180, 1181, 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2133, 2136, 2137, 2140, 2142, 2144, 2145, 2151, 2152, 2154, 2155, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2170, 2171, 2173, 2174, 2175, 2182, 2186, 2187, 2193, 2194, 2195, 2197, 2199, 2200, 2201, 2204, 2206, 2538, 2576, 2578, 2582, 2583, 3347 Ulrich, H. J., 3026, 3069 Ulstrup, J., 1450 Umashankar, V., 3308 Umehara, I., 407 Umetani, S., 3067 Une, K., 390, 394, 396, 397 Ungaretti, L., 3159 United Nations, 303 United States Environmental Protection Agency, 3280 Uno, M., 338, 2157, 2158, 2202 Uno, S., 856, 2680, 2681, 2683, 2684 Unrein, P. J., 772, 1352, 1426, 1477, 1550, 2561, 2574, 2579 UNSCEAR, 1805 Unterwurzacher, M., 3164 Uozumi, K., 2134, 2135, 2700, 2719, 2721 Upali, A., 545 Urbain, G., 115 Urban, F. J., 789, 1296, 1403, 1875, 1877 Urban, G., 132 Urban, V., 2652 Urbaniak, W., 2966 Uribe, F. S., 971, 972 Usami, T., 864, 2147, 2723 Ushakov, S. V., 113, 2157, 2159 Usov, O. A., 546 Ustinov, O. A., 2702 Ustinov, V. A., 2140 Usuda, S., 784, 1049, 1625, 2637, 3066 Utamura, M., 760 Utkin, A. N., 1680, 1681 Utkina, O. N., 984 Utyonkov, V. K., 14, 1398, 1400, 1504, 1653, 1654, 1707, 1719, 1736, 1738 Uusitalo, J., 14, 1653, 1713, 1717 Uvarova, Y. A., 261 Uylings, P. H. M., 1843 Vaden, D., 2717 Vaezi- Nasr, F., 183 Vagunda, V., 1507 Vahle, A., 1447, 1451, 1662, 1664, 1684, 1685, 1708, 1709, 1711, 1712, 1713, 1714, 1716 Vaidya, V. N., 1033, 1271 Vaidyanathan, S., 1127, 1175, 3052, 3053 Vaillant, L., 2674

Author Index

I-277

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Vakarin, S. V., 2703, 2704 Vakatov, D. V., 1719 Vakhrushin, YuA., 113 Valdez, Y., 2749 Valdivieso, F., 861 Valenzuela, R. W., 1369 Valeriani, G., 1282, 2743 Valigi, M., 2431 Valkiers, S., 405 Valkonen, J., 580, 581, 2434 Vallet, V., 577, 578, 580, 581, 589, 590, 591, 595, 596, 606, 607, 610, 612, 613, 616, 617, 619, 625, 1156, 1909, 1918, 1919, 1921, 1922, 1923, 1924, 1925, 1926, 1931, 1932, 1969, 1988, 2532, 2576, 2578, 2579, 3102, 3120, 3126, 3127, 3128, 3144 Valli, K., 25, 164 Valocchi, A. J., 3106 Valone, S. M., 928 Valot, C., 930, 932, 933, 954 van Alphen, P. V., 62 van Arkel, A. E., 61, 62 Van Axeel Castelli, V., 597 Van Britsom, G., 3024, 3059, 3060 Van den Bossche, G., 470, 552, 553, 2472, 2476, 2489, 2815 Van Der Hout, R., 28 Van Der Laan, G., 2236 van der Loeff, M. M. R., 231 Van Der Sluys, W. G., 739, 1185, 1186, 1965, 2490, 2867, 2868 Van Deurzen, C. H. H., 1845, 2038, 2065, 2074 van Egmond, A. B., 372, 374, 375, 378, 383 van Geel, J., 44, 3265 van Genderen, A., 2146, 2185, 2186, 2187 Van Ghemen, M., 199, 201, 2417 van Gisbergen, S. J. A., 1910 Van Houten, R., 65 Van Impe, J., 484, 485 Van Konynenburg, R. A., 3258, 3259 van Lenthe, E., 1907 van Lierde, W., 343, 353, 354 Van Mal, H. H., 66 Van Meersche, M., 2489, 2490, 2492, 2802, 2844 Van Middlesworth, L., 3356 van Miltenburg, J. C., 2146 Van Nagel, J. R., 1507 Van Pelt, C., 1155, 1327, 1368, 1369 van Pieterson, L., 2020 van Rensen, E., 80, 81 Van Rossum, J. P., 3385 van Springel, K., 541 Van Tets, A., 2439 Van Tuyle, G. J., 1811 Van Vlaanderen, P., 514, 525, 2153, 2185, 2186

Van Vleck, J. H., 2225 van Voorst, G., 374, 375, 378, 383 van Vucht, J. H. N., 66 Van Wagenen, G., 3344 Van Wezenbeek, E. M., 1666, 1667, 1668, 1972 Van Winkle, Q., 152, 166, 172, 174, 182 van Woesik, R., 3047 van Wu¨llen, C., 1671, 1682, 1683, 1727, 1907 Vance, D. E., 3291, 3299, 3303, 3327 Vance, E. R., 279, 280, 291, 2067, 2157, 2159 Vance, J. E., 255, 303 Vandegrift, G. F., 1281, 1282, 1295, 2655, 2738, 2739, 2740, 2750, 2751 Vander Sluis, K. L., 33, 1363, 1423, 1452, 1533, 1534, 1543, 1643, 1872 Vandergriff, R. D., 1508, 1511, 1585, 1623, 1624 Vanderhooft, J. C., 2865 Vaniman, D. T., 861, 3095, 3175, 3176, 3177 Vannagell, J. R., 1507 Varelogiannis, G., 2347 Varga, L. P., 763, 765, 1356, 1365, 1475, 1513, 1515, 1604, 2076, 2082 Varga, S., 1671, 1676, 1680, 1681, 1682, 1683, 1684, 1712, 1716 Varga, T., 2633 Variali, G., 2431 Varlashkin, P. G., 757, 1133, 1547, 1559, 2129, 2131 Varnell, L., 164 Vasaikar, A. P., 110 Vasilega, N. D., 112 Vasil’ev, V. P., 2114, 2148, 2149, 2185 Vasil’ev, V. Y., 763, 765, 1144, 1145, 1146, 1317, 1337, 1338, 2531, 3101, 3106, 3111, 3113 Vasil’ev, V. Ya., 108, 1412, 1413, 1416, 1422, 1430, 1448, 1449, 1466, 1479, 1484 Vasilkova, I. V., 516 Vasko, V. M., 1720 Vasseur, C., 1304 Vasudev, D., 2668 Vasudeva Rao, P. R., 355, 1283, 1422, 2205, 2206, 2684 Vaufrey, F., 2657 Vaughan, D. A., 2407 Vaughan, D. J., 3165, 3167, 3169 Vaughan, J., 3352, 3403, 3404, 3407, 3410, 3424 Vaughan, R. W., 64 Vaughen, V. C. A., 256 Vaughn, G. A., 718, 719, 891 Vaughn, J., 1823 Vaughn, R. B., 849, 1139, 1161, 1167 Vaughn, R. L., 2686 Vaugoyeau, H., 351, 352, 353, 405

I-278

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Vavilov, S. K., 2693, 2699, 2704, 2705, 2706, 2707, 2708, 2715 Vazquez, J., 1927, 3143, 3145 Vdovenko, V. M., 86, 93, 436, 437, 454, 470, 471, 473, 475, 476, 495, 548, 549, 571, 575, 1116, 2579 Vdovichev, V. S., 30 Veal, B. W., 763, 766, 1466, 1517 Vecernik, J., 755 Ve´drine, A., 86, 87, 92, 457, 458, 459 Vedrine, J. C., 76 Veeck, A. C., 3419 Veeraraghavan, R., 182, 184 Vegas, A., 2407, 2408 Veirs, D. K., 704, 849, 851, 861, 932, 1041, 1043, 1112, 1139, 1154, 1155, 1161, 1166, 1167, 1926, 3109, 3210 Veirs, K., 1035, 3220 Veleckis, E., 272 Veleshko, I. E., 28, 38, 1606, 1607, 1608 Venanzi, L. M., 496, 574 Vendl, A., 70 Vendryes, G., 824 Venkataraman, C., 2288 Venkateswarlu, K. S., 215, 218 Vennart, J., 3353 Ventelon, L., 2480, 2837 Venugopal, B., 3359, 3362 Venugopal, V., 69, 105, 2157, 2158, 2202, 2209, 2434 Ver Sluis, K. L., 33 Vera Tome´, F., 133 Verbist, J. J., 420, 423, 425, 435, 437, 457, 470, 473, 474, 478, 502, 509, 514, 515, 516, 538, 544, 551 Vereshchaguin, Yu. I., 1479 Verges, J., 1453, 1516, 1544, 1840, 1845, 1846, 1847, 1848, 1849, 1871 Verma, R. D., 105 Vermeulen, D., 6, 1705, 1738 Verneuil, A., 76, 77, 104 Vernois, J., 188, 207, 209, 215, 219 Vernooijs, P., 1972 Verry, M., 1819, 3398, 3399 Vertse, T., 1736 Veselsky, J. C., 3037, 3308 Veselsky, M., 1654, 1719 Veslovsky´, F., 262, 263 Vesnovskii, S., 822 Vesnovskii, S. P., 822, 1398 Vettier, C., 2234, 2285, 2286, 2287, 2352 Vezzu, G., 3029, 3030, 3283, 3293, 3296 Viala, F., 1873 Viani, B. E., 3101, 3152, 3156 Vicens, J., 2456, 2457, 2458, 2459, 2460, 2461 Vidali, M., 115, 1926, 2437, 2438 Vidanskii, L. M., 346 Viers, D. K., 2864

Vigato, A., 1926 Vigato, P. A., 115, 2437, 2438 Vigil, F., 967 Vigil, F. A., 882, 2289, 2290 Vigner, D., 102, 106, 380, 1928, 2820 Vigner, J., 1960, 1962, 2246, 2801, 2805, 2806, 2807, 2808, 2818, 2819, 2847, 2856, 2857, 2858, 2859, 2861, 2862, 2866, 2869, 2870, 2871, 2872, 2889, 2922, 2938 Vigner, J.-D., 2439, 2449, 2450, 2451, 2452, 2458, 2462, 2464, 2465, 2466, 2472, 2473, 2479, 2480, 2484, 2488, 2490, 2491 Viklund, C., 851 Vilaithong, T., 1507 Vilcsek, E., 3306 Vilcu, R., 367 Villa, A. C., 2472 Villa, I. M., 3047 Villain, F., 2449, 2453 Villella, P. M., 704, 932, 1041, 1043, 1154, 1155, 3109, 3210 Villiers, C., 2472, 2801, 2805, 2806, 2808, 2820, 2824 Vinas, C., 2655 Vincent, H., 113 Vincent, M. A., 1926, 1928, 1929, 1931 Vincent, T., 3152, 3154 Vinokurov, S. E., 2684 Vinto, L. L., 3017, 3023 Virelizier, H., 2657, 2658, 3054 Virk, H. S., 3031 Virlet, J., 2603 Visscher, L., 34, 578, 1728, 1905, 1939, 1980 Vissen, J., 3029 Vissequx, M., 2890 Visser, A. E., 2686, 2691 Visser, O., 1905 Viste, A., 343, 357, 358 Viswanathan, H. S., 3106 Viswanathan, K., 261 Viswanathan, K. S., 1988 Viswanathan, R., 96, 1074 Visyashcheva, G. I., 749, 1164, 2129, 2131, 2427, 2442 Visyasheva, G. I., 1312, 1319 Vita, O. A., 357 Vitart, X., 1285, 2657, 2756 Vitorge, P., 718, 719, 722, 726, 727, 728, 739, 744, 745, 753, 756, 767, 769, 771, 775, 881, 888, 891, 989, 1008, 1019, 1021, 1045, 1047, 1048, 1085, 1086, 1087, 1098, 1100, 1101, 1110, 1111, 1117, 1118, 1131, 1147, 1148, 1149, 1150, 1155, 1157, 1158, 1159, 1160, 1161, 1162, 1164, 1165, 1166, 1167, 1169,

Author Index

I-279

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 1170, 1171, 1180, 1181, 1314, 1341, 1354, 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2133, 2136, 2137, 2140, 2142, 2144, 2145, 2151, 2152, 2154, 2155, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2170, 2171, 2173, 2174, 2175, 2182, 2186, 2187, 2193, 2194, 2195, 2197, 2199, 2200, 2201, 2204, 2206, 2538, 2576, 2578, 2582, 2583, 2673, 3099, 3136, 3206, 3213, 3347 Vitos, L., 1044 Vitti, C., 262 Vityutnev, V. M., 1448, 1449, 1479, 1484, 1512, 1549 Vivian, A. E., 605, 2401, 2464, 2465, 2466 Vjachin, V. N., 1398 Vladimirova, M. V., 1035, 1144, 1145, 1337 Vlasov, M. M., 3024 Vlasov, Yu. G., 3029 Vobecky, M., 1512, 1624, 1632 Vochten, R., 262, 267, 268, 294, 541 Vodovatov, V. A., 539, 1116, 2594 Voegli, R., 2828 Voegtlin, C., 3340, 3354, 3413, 3421, 3423 Voelz, G., 1818, 1819, 1820 Voelz, G. L., 1820, 1821, 3199, 3252 Vogel, Ch., 1643 Vogel, G. J., 1081 Vogel, J. S., 3316 Vogel, M., 1735 Vogel, R. C., 950, 1080, 1086, 2632, 2710 Vogel, S. C., 965, 966, 967 Vogl, K., 3017, 3027 Vogler, S., 3046 Vogt, E., 1653 Vogt, O., 100, 409, 412, 718, 739, 744, 1023, 1052, 1055, 1056, 1318, 2234, 2236, 2362 Vogt, S., 3173 Vogt, T., 942 Vohra, Y. K., 61, 2370 Voight, A. F., 29 Voinov, A. A., 14, 1654, 1719, 1736, 1738 Voinova, L. M., 2432 Voitekhova, E. A., 373, 375 Vokhmin, V., 118, 119, 1991, 2126, 2531, 3101, 3104, 3110, 3111, 3113, 3114, 3115, 3116, 3117, 3118 Vokhmyakov, A. N., 93 Volchok, H. L., 3282, 3295 Volck, C., 95, 110 Volden, H., 2169 Volden, H. V., 1958 Volesky, B., 2669 Volf, V., 1179, 3361, 3404, 3413, 3415, 3416, 3419, 3420, 3421, 3422 Voliotis, S., 102, 109, 131, 587, 588, 2427 Volk, T., 2728

Volkov, V. A., 424, 430, 431, 437, 450, 454, 470, 471, 473 Volkov, V. V., 1402, 1422, 1423 Volkov, Y. F., 735, 739, 744, 747, 749, 1164, 1312, 1315, 1319, 2527, 2595 Volkov, Yu. F., 108, 109, 1422, 2129, 2131, 2427, 2431, 2442 Volkova, E. A., 20, 24 Volkovich, V. A., 372, 373, 374 Volkoy, Y. F., 1931 Vollath, D., 2392 Volleque, P. G., 1821 Vollmer, S. H., 2479, 2482, 2809, 2811, 2832, 2841, 2916, 2919, 2924, 2997 Voloshin, A. V., 102, 109 Volz, W. B., 1475, 1513, 1515 Von Ammon, R., 2817 von Bolton, W., 61, 63, 80, 115 von Erichsen, L., 332 von Goldbeck, O., 53, 67 von Gunten, H. R., 1449, 1450, 1451 von Hippel, F. N., 3173 von Schnering, H. G., 98, 100 von Wartenberg, H., 61, 63, 80 von Wedelstaedt, E., 3413 von Welsbach, C. A., 52 Vorobei, M. P., 545, 546 Vorob’ev, A. F., 2114, 2148, 2149, 2185 Vorob’eva, V. V., 1352, 1553 Voronov, N. M., 364, 365, 373, 375, 393 Voshage, H., 3306 Vosko, S. H., 1643, 1904 Vostokin, G. K., 1654, 1719, 1720, 1738 Vostrotin, V. V., 1821 Vozhdaeva, E. E., 525 Vrtis, R. N., 2802, 2876 Vu, D., 98 Vukcevic, L., 3051 Vyalikh, D. V., 2237 Vyas, B. N., 1819 Vyatkin, V. E., 1127 Vyatkina, I. I., 1330 Vysokoostrovskaya, N. B., 1145 Waber, J. T., 398, 408, 409, 973, 976, 977, 1626, 1627, 1669, 1670, 1682, 1689, 1728, 1731, 1732, 1733, 3200, 3213, 3259 Wacher, W. A., 117 Wachter, P., 420, 1055, 1056 Wachter, W. A., 116, 117, 2240, 2464, 2467, 2471, 2472, 2801, 2815 Wachter, Z., 3045 Wachtmann, K. H., 69, 72 Wacker, L., 1806 Wada, H., 2652 Wada, N., 407

I-280

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Wada, Y., 712, 762 Waddill, G. D., 277 Wade, K. L., 2676 Wade, U., 1178, 1180 Wade, W. Z., 958, 959, 960, 2118, 2121 Wadier, J. F., 391, 396, 1044 Wadsley, A. D., 113 Wadt, W. R., 576, 578, 1194, 1195, 1196, 1908, 1916, 1917, 2084, 2165, 2400 Waerenborgh, J. C., 719, 720 Wagener, W., 2284 Waggener, W. C., 763 Wagman, D. D., 34, 62, 322, 2114, 2115, 2117, 2120, 2135, 2136, 2137, 2165 Wagner, F., 1582 Wagner, F., Jr., 1453, 1454, 1455, 1513, 1515, 1533, 1543, 1544 Wagner, F. W., 1455, 1515 Wagner, J. J., 1845, 1846 Wagner, M. J., 1294, 2748 Wagner, R. P., 1090 Wagner, W., 466, 472, 476, 479, 482, 496, 499, 2236 Wahl, A. C., 4, 5, 8, 814, 815, 834, 902, 903, 904, 907, 912, 913 Wahlberg, J., 3061 Wahlgren, U., 565, 577, 578, 580, 581, 589, 590, 591, 595, 596, 606, 608, 609, 610, 612, 613, 616, 617, 619, 620, 622, 623, 1113, 1156, 1907, 1909, 1918, 1919, 1921, 1922, 1923, 1924, 1925, 1926, 1931, 1932, 1933, 2185, 2187, 2195, 2532, 2576, 2578, 2579, 3101, 3102, 3103, 3104, 3105, 3112, 3120, 3125, 3126, 3127, 3128, 3144 Wai, C. M., 2677, 2678, 2679, 2680, 2681, 2682, 2683, 2684, 2689 Wailes, P. C., 116 Wain, A. G., 178, 181, 772, 773, 774, 1290 Wait, E., 342, 346, 357, 358, 390, 2394 Wait, Z., 3171 Waite, T. D., 273, 3165, 3166, 3167, 3176 Wakamatsu, S., 1049 Wakerley, M. W., 494 Wakita, H., 3106 Walch, P. F., 1916, 2561 Waldek, A., 33, 859, 1452, 1513, 1588, 1590, 1840, 1875, 1876, 1877, 3047, 3321 Waldek, W., 1687, 1710, 1718 Walden, J. C., 958, 959 Walder, A. J., 638, 639, 3310, 3311, 3312, 3313 Waldhart, J., 70 Waldron, M. B., 892, 904, 905, 913 Waldron, W. B., 900, 901, 902, 988 Walen, R. J., 164 Walenta, K., 261, 262, 263, 265, 267, 288, 293, 294

Walewski, M., 2441 Walker, A., 350, 373, 380, 382, 729, 2077 Walker, A. J., 356 Walker, C. R., 357 Walker, C. T., 69, 73, 719, 720, 725, 2274, 2275 Walker, D. I., 2434 Walker, F. W., 164 Walker, I. R., 407, 2239, 2359 Walker, L. A., 521 Walker, R., 2253, 2488, 2852, 2853 Walker, R. L., 3312 Walker, S., 593 Walker, S. M., 2256 Walker, W., 1756, 1758, 1805 Wall, D. E., 2552, 2584 Wall, I., 377 Wall, M., 964, 965, 967, 2342 Wall, M. A., 863, 967, 980, 981, 983, 984, 986, 987 Wall, N., 1352 Wallace, M. W., 3159 Wallace, P. L., 910, 912 Wallace, T. C., 67, 71, 2407, 2408 Wallace, W. E., 66, 67 Wallenius, M., 3062 Waller, B. E., 2681, 2682, 2683, 2684 Walling, M. T., Jr., 2732 Wallmann, J. C., 5, 1085, 1295, 1297, 1409, 1410, 1412, 1413, 1414, 1417, 1419, 1420, 2386, 2387, 2395, 2396, 2397 Wallmeroth, K., 3320, 3321 Wallner, C., 3016, 3063 Wallroth, K. A., 110 Wallwork, A. L., 711, 760, 761, 1926, 1928, 1929, 1931, 2757 Walsh, K. A., 1077, 1093, 1095, 1104 Walsh, P. J., 2847, 2933, 2986 Walstedt, R. E., 2280 Walter, A. J., 178, 179, 195, 196, 226, 340, 353, 354, 360, 362, 726, 2391 Walter, D., 116, 2865 Walter, H. J., 231 Walter, K. H., 195, 378, 729, 730, 1060, 1061, 1064, 1065, 1066, 1067, 1312, 1313, 1422, 2431, 2432, 2433 Walter, M., 3165, 3167 Walters, R. L., 1803 Walters, R. T., 1088 Walther, C., 223, 1147, 1150, 1152, 1153, 1154, 1735, 3020, 3036, 3045, 3066 Walther, H., 787, 1114 Walton, A., 170 Walton, J. R., 5, 1637 Walton, J. T., 1653 Walton, R. A., 94 Walton, R. I., 593, 2256 Wan, A., 265 Wan, H. L., 76

Author Index

I-281

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Waner, M. J., 97 Wang, A., 108 Wang, F., 1905, 1907 Wang, H. K., 2852 Wang, H.-Y., 108 Wang, J., 133, 727, 2830, 2866, 2918, 2923, 2935, 2944, 2950, 2965, 2969, 2971 Wang, J. Q., 2913, 2918, 2927, 2930, 2935, 2938, 2940, 2943, 2953, 2955, 2958, 2961, 2965, 2969, 2971 Wang, J. X., 2866, 2922, 2940, 2943, 2975, 2976, 2979 Wang, L. M., 2157, 2159 Wang, M., 3055 Wang, Q., 577, 627, 1192, 1199, 1897, 1909, 1928, 1930, 1939, 1940, 2037 Wang, R., 1023 Wang, R. T., 2602 Wang, R.-J., 472 Wang, S., 2752 Wang, U.-S., 1285 Wang, W., 108 Wang, W. D., 630, 2979 Wang, X., 1975, 2676, 2762 Wang, X. Z., 70, 73 Wang, Y., 1285, 1903, 3052 Wang, Z., 2587 Wangersky, P. J., 170 Wani, B. N., 110 Wa¨nke, H., 1398, 1421, 1433, 3306 Wanklyn, B. M., 113 Wanner, H., 121, 125, 128, 421, 423, 425, 435, 440, 441, 457, 458, 469, 473, 474, 477, 478, 480, 481, 497, 502, 503, 509, 513, 514, 515, 516, 517, 536, 538, 543, 544, 545, 551, 552, 556, 593, 594, 595, 596, 597, 598, 599, 601, 602, 603, 718, 719, 722, 726, 727, 728, 739, 744, 745, 767, 769, 771, 1155, 1159, 1166, 1171, 1314, 1328, 1329, 1330, 1338, 1339, 1341, 1354, 1355, 2114, 2115, 2117, 2120, 2126, 2127, 2128, 2129, 2132, 2133, 2136, 2137, 2140, 2142, 2143, 2144, 2145, 2150, 2151, 2152, 2154, 2155, 2156, 2157, 2159, 2160, 2161, 2163, 2164, 2165, 2168, 2169, 2170, 2171, 2173, 2174, 2175, 2181, 2182, 2186, 2187, 2193, 2194, 2195, 2197, 2199, 2200, 2201, 2204, 2205, 2206, 2538, 2546, 2576, 2578, 2579, 2582, 2583, 3152, 3206, 3213, 3214, 3215, 3347, 3380, 3382 Wantong, M., 1267 Wanwilairat, S., 1507 Wapstra, A. H., 13, 164, 815, 817, 1267, 1446, 1660 Waqar, F., 3060 Ward, B. J., 918, 919

Ward, J., 1403, 1411 Ward, J. W., 34, 192, 195, 328, 333, 334, 335, 722, 723, 724, 795, 989, 990, 994, 995, 1298, 1330, 1403, 1411, 1459, 1523, 1527, 1555, 1562, 1592, 1593, 2115, 2116, 2117, 2120, 2122, 2123, 2148, 2188, 2189, 2208, 2209, 2210, 2403, 2404, 3204, 3205, 3213, 3214, 3239, 3240, 3241, 3242 Ward, R., 376 Ward, W. C., 3031 Warden, J., 1516 Wardman, P., 371 Ware, M. J., 93 Warf, J., 80 Warf, J. C., 107, 329, 332, 336, 423, 444, 632, 841, 3246 Warneke, T., 3328 Warner, A. J., 3346, 3372, 3373 Warner, B. P., 1185, 1186, 1958, 2491, 2850, 2922, 2995, 2996 Warner, H., 881, 888, 891, 989, 1008, 1019, 1021, 1045, 1047, 1048, 1085, 1086, 1087, 1098, 1100, 1101, 1110, 1111, 1117, 1118, 1131, 1147, 1148, 1149, 1150, 1155, 1157, 1158, 1162, 1167, 1169, 1170, 1171, 1180, 1181 Warner, J. C., 255, 303, 318, 319 Warner, J. K., 269, 278 Warren, B. E., 2385 Warren, I. H., 100 Warren, K. D., 2253, 2261 Warren, R. F., 2880 Warwick, P., 3279, 3285 Warwick, P. E., 3328 Wasserburg, G. J., 638, 3288, 3311, 3312, 3313 Wasserburg, G. T., 3014 Wasserman, H. J., 2472, 2480, 2801, 2807, 2832, 2891 Wasserman, N., 33, 1296 Wasserman, S. R., 754, 3087, 3095, 3099, 3100, 3107, 3108, 3119, 3152, 3157, 3158 Wastin, F., 69, 73, 97, 719, 720, 861, 863, 967, 968, 1009, 1012, 1015, 1016, 1023, 1033, 1034, 1050, 1052, 1056, 1112, 1166, 1304, 1784, 1790, 2239, 2289, 2290, 2347, 2352, 2353, 2372, 2407, 3109, 3210 Wastin, F. J., 2237, 2286 Watanabe, H., 390, 391, 1019 Watanabe, K., 392, 395 Watanabe, M., 1272, 1273, 1286, 2675, 2761 Watanabe, N., 412 Watanabe, T., 407 Watanabe, Y., 1695, 1699, 1905, 3062 Waterman, M. J., 1174, 1175

I-282

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Waters, T. N., 546, 2429 Watkin, J. G., 439, 454, 455, 1182, 1183, 1184, 1186, 2400, 2484, 2486, 2487, 2813, 2814, 2844, 2845 Watling, R. J., 3327 Watrous, R. M., 172, 175 Watson, G. M., 2281, 2282 Watson, J. N., 279, 280 Watson, K. J., 2530 Watson, P., 2289, 2290 Watson, P. L., 2924, 3002 Watson, R. E., 1461 Watson, S. B., 2735 Watt, G. W., 115, 493, 494 Wattal, P. K., 712, 713, 1281, 1282, 2743, 2745, 2747, 2757 Watts, J. D., 1902 Watts, O., 2827 Watts, R., 3353 Waugh, A. B., 198, 478, 498, 502, 503, 511, 530, 2394, 2418 Wauters-Stoop, D., 267 Wawryk, R., 100 Waychunas, G. A., 3163, 3165, 3166, 3167, 3173, 3176, 3177 Wayland, B. B., 2576 Wayman, R., xvi Weakley, T. J. R., 2660 Weaver, B., 1271, 1275, 1286, 1312, 1448, 1449, 1479, 1480, 1629, 2626, 2651, 2758 Weaver, B. S., 1509 Weaver, C. F., 423, 444, 461 Weaver, E. E., 732, 733, 1086, 2421 Weaver, J. H., 64, 2864 Webb, G. W., 34 Webb, S. M., 3181 Weber, A., 182, 185, 1447, 1704, 1705 Weber, E. T., 997, 998 Weber, J., 1477 Weber, J. K. R., 963 Weber, L. W., 2238, 2261, 2262, 2362 Weber, M. J., 1545 Weber, S., 2655, 2738, 2739 Weber, W. J., 863, 3163 Weber, W. P., 2969 Wede, U., 777, 779, 780, 782 Wedekind, E., 398 Wedermeyer, H., 339, 340 Wedler, M., 2875 Weeks, A. D., 363, 367 Weeks, M. E., 19, 20, 52 Weeks, S., 3036 Weger, H. T., 1172 Weghorn, S. J., 605, 2463, 2464, 2466 Wei, C.-T., 3405 Wei, L., 3062 Wei, S. H., 928

Wei, Y., 2749 Wei, Y. Z., 845, 1294, 1295 Weifan, Y., 1267 Weigel, F., 35, 36, 38, 162, 199, 200, 201, 383, 395, 559, 593, 745, 747, 749, 1034, 1069, 1078, 1095, 1100, 1101, 1172, 1312, 1319, 1321, 1322, 1323, 1357, 1359, 1361, 1418, 1421, 1422, 2163, 2164, 2393, 2407, 2408, 2417, 2422, 2427, 2430, 2431, 2434, 2436, 2439, 2441, 2442, 3206, 3207, 3208, 3212 Weigl, M., 2756 Weiland, E., 3152 Weill, F. L., 1824 Weinheim, M. K., 1584, 1606 Weinland, R. F., 105 Weinstock, B., 732, 733, 1080, 1081, 1086, 1088, 1090, 1935, 1937, 2083, 2241, 2243, 2421 Weisman, S. J., 194 Weiss, A. R., 319 Weiss, B., 1688, 1700, 1718 Weiss, R. J., 942 Weissbluth, M., 2020, 2021, 2022, 2023, 2027, 2040 Weitl, F. L., 3378, 3413, 3414, 3415, 3416, 3418, 3419, 3420, 3421 Weitzel, H., 391 Weitzenmiller, F., 900, 901 Welch, G. A., 1004, 1007, 1008, 1018, 1031, 1032, 1034, 1151, 1174, 3212, 3217, 3218, 3222 Welch, R. B., 1738 Weldrick, G., 375 Weller, M. T., 259, 287, 2390, 2394 Wellington, G. M., 3162 Wells, A. F., 569, 579, 600, 1007, 1059, 1083, 3208, 3214, 3215 Wells, H. L., 90 Welp, U., 2267 Weltner, J. W., 1968, 1985 Weltner, W. J., 2894 Welton, T., 2686 Wen, Z., 791 Wenck, P., 3117 Wenclawiak, B. W., 2679, 2681 Wendeler, H., 789, 1875, 1877 Wendlandt, W. W., 107 Wendt, H., 616 Wendt, K, 60 Wendt, K., 1452, 1875, 1876, 1877 Weng, W. Z., 76 Wenji, W., 2452, 2456 Wensch, G. W., 909 Werkema, E. L., 2845, 2846 Werner, A., 2563 Werner, B., 2480, 2836 Werner, E. J., 2655

Author Index

I-283

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Werner, G. D., 1108, 1109, 1111 Werner, G. K., 1363, 1423, 1454, 1533, 1534, 1543, 1592, 1604 Werner, G.-D., 1172, 1312, 1319, 1320, 1321, 2430, 2431 Werner, H., 2953 Werner, L. B., 5, 815, 834, 934, 1366, 1397 Wernli, B., 3068 Wersin, P., 3152 Wes Efurd, D., 1155 Weschke, E., 2237 Wessels, G. F. S., 115 West, M., 457, 486 West, M. H., 1093 West, R., 2969 Wester, D. W., 745, 1160, 1164, 1169, 1170, 1294, 1454, 2094, 2095, 2096, 2748 Westgaard, L., 170, 187 Westlake, D. G., 64 Westland, A. D., 93 Weston, R., 1071 Westphal, B. R., 2717 Westrum, E. F., 2273, 2282 Westrum, E. F., Jr., 106, 340, 345, 348, 350, 353, 354, 355, 356, 357, 359, 378, 478, 486, 497, 502, 988, 1015, 1018, 1028, 1030, 1034, 1052, 1079, 1098, 1100, 2114, 2156, 2169, 2176, 2203, 2204, 2208, 2211 Westrum, E. F., Jr ., 1085, 1101 Weulersse, J. M., 537, 566, 567 Wharf, R. M., 2677 Wharton, J. H., 526 Wheeler, R. B., 1432 Wheeler, R. G., 1913 Wheeler, V. I., 342, 357 Wheeler, V. J., 106, 1019 Wheelwright, E. J., 1268, 1290, 1291 Whicker, F. W., 3296 Whisenhunt, D. W., 2591, 3419 Whisenhunt, D. W., Jr., 2669 White, A. H., 1174, 2441, 2457, 2461, 2571 White, D., 3416, 3419 White, D. J., 1168, 2591, 3419 White, D. L., 3413, 3414, 3416, 3417, 3418, 3419, 3421 White, G. D., 87, 90 White, G. M., 115 White, H. E., 1872 White, J., 415, 416, 417 White, J. C., 313 White, J. F., 368 White, M. R., 3387, 3388 White, R. W., 68, 191, 193, 1302, 2350 White, T. J., 278 White, W. B., 293 Whitehead, N. E., 3026, 3029 Whitehorn, J. P., 3244

Whitehouse, C. A., 1821 Whiteley, M. W., 1927, 1928, 2583, 3132 Whiting, M. C., 1952 Whitley, M. W., 588, 595 Whitman, C. I., 61, 319 Whittacker, B., 2123, 2160 Whittaker, B., 94, 186, 191, 198, 199, 200, 201, 203, 206, 207, 208, 466, 471, 472, 476, 479, 482, 496, 498, 499, 501, 512, 515, 524, 527, 731, 732, 745, 746, 2065, 2276, 2413, 2419, 2420 Whyte, D. D., 909 Wiblin, W. A., 225, 226 Wichmann, U., 396 Wick, G. C., 164 Wick, O. J., 814, 891, 957, 958, 988, 991, 1007, 1032, 1070, 1073, 1138, 1173, 1175, 2730 Wicke, E., 329, 330, 331, 332 Wickleder, M. S., 52 Wickman, H. H., 2265 Wicks, G. W., 3265 Widmark, P.-O., 1979 Wiedenheft, C. J., 1045 Wiehl, N., 1666, 1695, 1702, 1717, 1735 Wielstra, Y., 2924 Wiener, M., 3398, 3399 Wier, T. P. J., 2685 Wierczinski, B., 1663, 1666, 1695, 1699, 1702, 1717, 1735 Wierzbicki, A., 2691 Wierzbicki, J. G., 1507, 1518, 1829 Wiesinger, G., 2362 Wietzke, R., 1963, 1965 Wiewandt, T. A., 722, 723, 724, 2404 Wigel, F., 1312, 1319, 1320, 1321 Wiggens, J. T., 1584 Wiggins, J. T., 1509 Wiggins, P. E., 1507 Wiggins, P. F., 1507 Wigley, D. A., 981, 983 Wigley, T. M. L., 2728 Wigner, 1911 Wigner, E., 2326 Wigner, E. P., 2310 Wijbenga, G., 2208, 2211 Wijesundera, W. P., 1643 Wijkstra, J., 1449 Wilcox, P. E., 3362 Wilcox, W. W., 942, 943, 944, 946 Wild, J. F., 14, 1297, 1398, 1530, 1533, 1543, 1629, 1633, 1636, 1639, 1641, 1647, 1653, 1654, 1692, 1695, 1696, 1707, 1719, 1736, 1738, 2077, 2416, 2525, 2526, 2670 Wilhelm, H. A., 61, 63, 67, 319, 399 Wilhelm, W., 2236 Wilhelmy, J. B., 1447, 1477

I-284

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Wilk, P. A., 815, 1447, 1582, 1662, 1666, 1684, 1693, 1695, 1701, 1702, 1711, 1712, 1713, 1716, 1717, 1735, 1737 Wilke, G., 116, 2865 Wilkerson, M. P., 2400 Wilkes, J. S., 2686 Wilkins, R., 2603 Wilkins, R. G., 164, 184, 215, 220, 221, 222, 227, 606, 609, 613, 2564 Wilkinso, D. H., 1660 Wilkinson, D. H., 13, 1660 Wilkinson, G., 162, 630, 1189, 1800, 1952, 2628, 2799, 2800, 2815, 2866, 3130, 3131, 3132, 3346 Wilkinson, M. K., 334, 335, 2232 Wilkinson, W. D., 255, 313, 317, 318, 321, 323, 325, 327, 403, 903, 3245 Wilks, M. J., 3017, 3302 Will, G., 719, 720 Willets, A., 596, 1907, 1921, 1922, 1923, 1938 Willett, R. D., 102, 110 Willetts, A., 2528, 3102, 3113, 3123 Williams, A., 334, 335 Williams, C., 754, 1088, 1194, 1473, 1474, 1475, 2080, 2084, 2086, 2263, 3087, 3099, 3100, 3107, 3108 Williams, C. T., 277, 278 Williams, C. W., 380, 483, 486, 731, 732, 734, 764, 861, 1061, 1063, 1112, 1113, 1312, 1313, 1356, 1370, 1419, 1420, 1454, 1455, 1465, 1471, 1474, 1480, 1481, 1544, 1605, 1778, 1933, 2014, 2016, 2020, 2031, 2037, 2041, 2044, 2047, 2054, 2056, 2064, 2068, 2069, 2070, 2071, 2072, 2073, 2075, 2082, 2085, 2096, 2099, 2127, 2153, 2161, 2190, 2233, 2264, 2267, 2268, 2293, 2397, 2419, 2420, 2526, 2527, 2528, 2531, 2532, 2584, 3039, 3087, 3106, 3107, 3108, 3110, 3111, 3112, 3114, 3116, 3122, 3125, 3170, 3179, 3181 Williams, D. R., 131, 132 Williams, E. H., 620 Williams, G., 2457 Williams, G. A., 3017, 3302 Williams, J., 1070 Williams, J. H., 2250 Williams, J. L., 1507, 2686, 3343, 3349, 3350, 3396, 3398, 3399, 3405 Williams, J. M., 2283, 2479, 2481, 2839, 2841 Williams, K. R., 1479, 1554, 2603, 2604, 2605 Williams, M. H., 3341, 3387, 3403, 3405 Williams, P., 101, 104 Williams, R. J. P., 1640 Williams, R. W., 231, 3312, 3314 Williams, S. J., 786 Williamson, G. K., 892, 913 Williamson, M., 3403, 3404, 3407, 3410

Willis, B. T. M., 340, 344, 345, 347, 348, 354, 2273, 2392, 3163 Willis, D. L., 3355, 3366 Willis, J. M., 90 Willis, J. O., 995, 2333, 2351 Willis, M., 2132 Willit, J. L., 2692, 2695, 2696, 2698, 2723 Wills, B. T. M., 2391 Wills, J., 2248, 2289, 2291 Wills, J. H., 3380 Wills, J. M., 190, 924, 925, 928, 934, 935, 1300, 1301, 1894, 2313, 2318, 2330, 2347, 2348, 2355, 2370, 2384 Wilmarth, P., 1653, 1738 Wilmarth, W. R., 421, 1469, 1533, 1544, 2174, 2271 Wilson, A., 70 Wilson, A. S., 63, 64, 65, 339, 399, 407 Wilson, D. W., 98, 99, 100, 2411 Wilson, G. C., 3318 Wilson, G. L., 2160 Wilson, H. D., 1509 Wilson, I., 2591, 3419, 3421 Wilson, L. J., 2864 Wilson, M., 190, 199, 1852 Wilson, M. J., 1507 Wilson, P. W., 425, 435, 439, 453, 455, 469, 473, 474, 495, 515, 530, 536, 543, 544, 560, 562, 567, 568, 569, 573, 594, 2417, 2418, 2420, 2421, 2424, 2426 Wilson, R. E., 1825, 3173, 3176, 3177, 3420 Wilson, S., 1669 Wilson, S. R., 2464 Wilson, T. A., 2385 Wilson, W. B., 393 Wilson, W. W., 561 Wimmer, H., 1352, 1354, 1405, 1406, 1433, 2536, 2591, 3037, 3038, 3043 Winand, J. M., 1304 Winchester, R. S., 832, 837 Windley, B. F., 270, 271 Windus, T. L., 1908 Winfield, J. M., 520 Wing, R. O., 3258 Wingchen, H., 80, 81, 82 Wingefors, S., 1286, 2672 Winick, H., 3088 Winkelmann, I., 3017, 3027 Winkler, B., 2265, 2293 Winkler, C., 61, 63, 64 Winkler, J. R., 577 Winkler, R., 784 Winninck, J., 2687, 2691 Winocur, J., 190, 1847 Winslow, G. H., 345, 351 Winter, H., 63 Winter, N. W., 1908, 1909, 1910, 1930 Winter, P. W., 369

Author Index

I-285

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Winter, R., 3398 Winterfeld, J., 2924 Wipff, G., 596, 1927, 2560, 2590, 2685, 3101, 3102, 3119, 3121 Wirth, B. D., 863, 980, 981, 983, 984, 986 Wirth, F., 104 Wirth, G., 204, 205, 1662, 1664, 1679, 1684, 1685, 1687, 1708, 1709, 1710, 1713, 1714, 1716, 1718, 1738 Wirth, P., 1179, 3415, 3416, 3420 Wirth, R., 3364, 3365, 3377, 3379, 3398, 3399, 3404, 3422 Wise, H. S., 190, 226 Wiseman, P. J., 123, 126 Wishnevsky, V., 200, 1095, 1100, 1101, 1312, 1357, 1418, 2164, 2422 Wisniewski, P., 412, 2411 Wisnubroto, D. S., 713, 2738 Wisnyi, L. G., 372, 373 Wison, L. C., 1507 Wiswall, R. J., Jr., 854 Withers, H. R., 1507 Witte, A. M., 70 Witteman, W. G., 2407, 2408 Wittenberg, L. J., 487, 718, 719, 891, 904, 914, 962, 963 Wittig, J., 1300 Wittmann, F. D., 1312, 1321, 1359, 2407, 2408 Wittmann, M., 98, 100 Wlodzimirska, B., 32 Wlotzka, F., 3306 Wocadlo, S., 2442, 2447, 2448 Wogman, N. A., 3297 Wo¨hler, L., 104 Wo¨hler, P., 104 Wohlleben, D., 62 Woiterski, A., 1906 Wojakowski, A., 195, 204, 414, 416, 739, 740, 741, 742, 743, 1020, 1022, 1304, 1312, 1316, 1317, 1318, 1412, 1415, 1421, 2411, 2413 Wojakowski, W., 740, 742, 1414 Wolcott, N. M., 2350 Wold, S., 3062 Wolf, A. S., 518 Wolf, G., 64 Wolf, M., 1312, 1357, 2167, 2422 Wolf, M. J., 107, 181, 182, 187, 1092, 1094, 1095, 1100, 1101 Wolf, R., 636, 3306 Wolf, S. F., 253, 273, 637, 638, 3017, 3273, 3294, 3296, 3299, 3301, 3302, 3308, 3324, 3326, 3327, 3328 Wolf, T., 2118, 2121 Wolf, W., 2229, 2241 Wolf, W. P., 356 Wolfberg, K., 3031 Wolfe, B. E., 367

Wolfer, W. G., 863, 980, 981, 983, 984, 985, 986, 987 Wollan, E. O., 64, 2402 Wolmersha¨user, G., 2480 Wolmersha¨user, G., 2836 Wolson, R. D., 2714, 2715 Wolzak, G., 164 Wong, C. H., 2816 Wong, C.-H., 2471, 2472 Wong, E., 471, 476, 482, 496, 2243 Wong, E. Y., 763, 764, 2066, 2067, 2089, 2226 Wong, J., 964, 965, 967, 2342 Wong, K., 3031 Wong, K. M., 2351, 3282 Wong, N. L., 3357, 3381, 3383 Wong, P. J., 988, 1159, 2650 Woo, S. I., 2669 Wood, C. P., 1670 Wood, D. H., 910, 914, 915, 3258, 3259 Wood, J. H., 333, 334, 335, 1908, 1916, 1938 Wood, P., 348 Wood, R., 3413 Woodall, M. J., 385, 388 Woodhead, J. D., 3326 Woodhead, J. L., 188, 225, 226, 1093 Woodley, R. E., 396, 404, 3220 Woodrow, A. B., 636, 3306 Woodruff, L., 3356 Woodruff, S. B., 1916 Woods, A. B. D., 2274, 2277 Woods, M., 1129, 1160, 1166, 1335 Woods, M. J., 3302 Woods, R. J., 1144 Woods, S. A., 3302 Woodward, L. A., 93 Woodward, R. B., 1952 Woodwark, D. R., 546, 2087 Woody, R. J., 305, 308 Woolard, D. C., 108 Woollatt, R., 35 Wooten, J. K., Jr., 2027, 2040 Worden, E. F., 859, 1452, 1453, 1513, 1516, 1544, 1586, 1836, 1839, 1840, 1845, 1846, 1847, 1848, 1849, 1850, 1864, 1865, 1871, 1872, 1873, 1874, 1875, 1877, 1878, 1882, 1885 Worden, E. F. J., 2018 Worl, L. A., 2752 World Energy Council, 1755 Wort, D. J. H., 1873 Wortman, D. E., 2044 Wouthuysen, S. A., 1906 Wrenn, M. E., 133, 3069, 3340, 3345, 3349, 3355, 3366, 3371, 3374, 3396, 3405, 3424 Wriedt, H. A., 1017, 1019, 1025, 1026, 1029, 1045, 1046, 1047, 1048, 3206, 3207, 3211, 3212

I-286

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Wright, A., 2283 Wright, A. F., 994, 1082 Wright, H. W., 164, 169 Wright, J. C., 2047 Wright, J. M., 841 Wrighton, M. S., 2966 Wrobel, G., 76 Wrobleski, D. A., 1959, 2480, 2481, 2482, 2832, 2837, 2891 Wroblewska, J., 1066, 1068 Wrona, B. J., 1021, 1022 Wronkiewicz, D. J., 270, 272, 273 Wronski, T. J., 3402, 3403, 3405 Wruck, D. A., 1114, 1340 Wu, C., 44 Wu, E. J., 97 Wu, H., 2682 Wu, J., 3055 Wu, K., 42, 43 Wu, P., 791 Wu, S.-C., 188 Wu, Y., 76, 77, 715 Wu, Y-D., 2980 Wu, Z., 2980 Wulff, M., 2262 Wyart, J.-F., 857, 858, 859, 860, 1513, 1514, 1516, 1588, 1589, 1604, 1836, 1840, 1841, 1843, 1844, 1845, 1846, 1847, 1848, 1849, 1850, 1863, 1864, 1865, 1868, 1873, 1876, 1882, 2038 Wyatt, E. I., 164, 169 Wybourne, B. G., 1365, 1454, 1455, 1513, 1862, 1896, 2015, 2016, 2020, 2024, 2025, 2027, 2029, 2030, 2036, 2039, 2040, 2042, 2049, 2055, 2056, 2074, 2228, 2230 Wycech, S., 1661 Wyckoff, R. W. G., 1084 Wydler, A., 1653 Wygmans, D. G., 1282, 2655, 2738, 2739, 2740 Wylie, A. W., 83, 84, 2424 Wymer, R. G., 842, 1033 Wynne, K. J., 998 Wyrick, S. B., 1433 Wyrouboff, G., 76, 77, 104 Wyse, E. J., 3278, 3327, 3328 Xeu, J., 2669 Xi, R. H., 3052 Xia Kailan, 186 Xia, Y. X., 131, 132, 2587 Xianye, Z., 1141 Xiao, Z., 2864 Xiaofa, G., 265 Xie, Y., 2665 Xie, Y. N., 1363 Xie, Z., 2869

Xin, R. X., 2753 Xing-Fu, L., 2912 Xiong, G., 2999 Xi-Zhang, F., 2912 Xu, D. Q., 108 Xu, H., 3052 Xu, H. G., 1706 Xu, J., 29, 1168, 1287, 1363, 1813, 1819, 1823, 1824, 1825, 2591, 2665, 3343, 3366, 3369, 3375, 3379, 3382, 3385, 3388, 3389, 3390, 3391, 3394, 3409, 3413, 3416, 3417, 3418, 3419, 3420, 3421, 3423 Xu, J. D., 2591, 3413, 3414, 3417, 3418, 3419, 3420, 3421, 3422 Xu, N., 3165, 3166, 3167, 3176 Xu, R. Q., 964, 965, 2342 Xu, S., 791 Xu, S. C., 108 Xu, W., 1534 Xue, Z., 2980 Xuexian, Y., 1278, 2653 Ya, N. Q., 1704 Yaar, I., 719, 720 Yabushita, S., 1909, 1910 Yacoubi, N., 1303, 1535, 2389 Yadav, R. B., 355, 396 Yaeger, J. S., 3285, 3327 Yaes, R. J., 1507 Yaffe, L., 106 Yagnik, S. K., 3055 Yahata, T., 993, 994, 1018 Yaita, T., 1363, 1370, 1554 Yakovlev, C. N., 1134 Yakovlev, G. N., 180, 1164, 1271, 1275, 1292, 1312, 1319, 1320, 1322, 1323, 1326, 1330, 1331, 1333, 1334, 1335, 1352, 1402, 1422, 1423, 1427, 1428, 1448, 1449, 1553, 2652 Yakovlev, N. G., 791, 1448, 1449, 3024 Yakshin, V. V., 705 Yakub, E., 2139, 2148 Yakuschev, A., 1468, 1679, 1684, 1708, 1709, 1716 Yakushev, A. B., 1447, 1624, 1632, 1662, 1664, 1684, 1685, 1695, 1700, 1706, 1707, 1708, 1709, 1713, 1714, 1716, 1720, 1721 Yamada, C., 1981 Yamada, K., 396, 397, 398, 2202 Yamada, M., 397 Yamagami, S., 473 Yamagishi, I., 1276, 1292, 2753, 2755, 2760 Yamagishi, S., 2723, 2724 Yamaguchi, A., 394 Yamaguchi, H., 822

Author Index

I-287

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Yamaguchi, I., 2753, 2755, 2760 Yamaguchi, K., 2153, 2157 Yamaguchi, L., 1276 Yamaguchi, T., 822, 1160 Yamakuchi, Y., 189 Yamamato, S., 294 Yamamoto, E., 412 Yamamoto, H., 1266, 1267 Yamamoto, I., 2678, 2679, 2681, 2684 Yamamoto, M., 709, 783, 784, 789, 790, 1354, 3059, 3062, 3068, 3072, 3295, 3296, 3327, 3328 Yamamoto, T., 338, 339, 703 Yamamoto, Y., 2953, 2969 Yamamura, T., 626, 627, 2681 Yamana, H., 30, 37, 120, 121, 703, 1153, 1270, 2135, 2575 Yamanaka, S., 338, 2157, 2158, 2202 Yamanouchi, S., 352 Yamasaki, S., 709, 784, 789, 3327 Yamashita, T., 375, 391, 392, 393, 727, 749, 750, 793, 1025, 1026, 1049, 1056, 1057, 1812, 2140, 2693 Yamauchi, S., 64, 65, 328, 331, 332, 333, 334, 723, 724, 989, 990, 991, 992, 994, 2114, 2188, 2189, 2190, 3204, 3205, 3206, 3214, 3225, 3241 Yamaura, M., 2748 Yamawaki, M., 338, 339, 769, 2153, 2157, 2553, 2738, 3022 Yamazaki, T., 861 Yamini, Y., 2681, 2684 Yamnova, N. A., 102, 109 Yan, C., 2869 Yanai, T., 1906 Yanase, A., 100 Yanase, N., 3171 Yanch, J. C., 1507 Yan-De, H., 2453 Yang, B. J., 1695 Yang, C. Y., 1916 Yang, D., 785, 2364 Yang, H. S., 231 Yang, K. N., 2357 Yang, Q., 2869 Yang, T., 589, 595, 613, 1991, 1992, 3105 Yang, W., 164, 191, 1903 Yang, X., 76, 2479, 2938, 2997, 2998, 2999 Yanir, E., 115, 1325, 1328, 1329, 1331 Yano, K., 2202 Yanovskii, A. I., 746, 747, 748, 749, 2434, 2439, 2442, 2595 Yao, J., 2677 Yao, K., 2577 Yaouanc, A., 2236 Yaozhong, C., 2591 Yap, G. P. A., 117, 1966, 2260, 2871, 2872, 2873, 2874

Yarbro, O. O., 2735 Yarbro, S. L., 726, 1141 Yarembash, E. L., 417 Yarkevich, A. N., 2657 Yartys, V. A., 66, 338, 339 Yasaki, T., 167 Yashita, S., 1653, 1738 Yasuda, H., 2924 Yasuda, K., 3066 Yasuda, R., 294 Yasue, H., 2966 Yasumoto, M., 2153, 2157 Yatzimirskij, K. B., 2114, 2148, 2149, 2185 Ye, X., 76 Yeager, J. P., 1294 Yee, N., 3180, 3182, 3183 Yeh, C.-C., 3285 Yeh, S., 731, 732, 2420 Yen, K.-F., 80, 81 Yen, T.-M., 2471, 2472 Yen, W. M., 763, 766, 2095, 2102, 2103 Yeremin, A. V., 6, 14, 164, 1653, 1654, 1701, 1713, 1717, 1719, 1720, 1737, 1738 Yeremin, A. Y., 1654, 1719 Yeremin, V., 14 Yerin, E. A., 2672 Yerkess, J., 67, 71 Yermakov, Y. I., 2999 Yesn, T. M., 2816 Yi, W., 639, 3327 Yi, Z., 265 Ying-Ting, X., 2912 Yoder, G. L., 357, 1048, 1071, 1074, 1075, 1076, 1077 Yokovlev, G. N., 1312, 1319 Yokoyama, A., 1696, 1718, 1735 Yokoyama, T., 3285 Yokoyama, Y., 189, 627 Yonco, R. M., 903, 2715 Yoneda, J., 1507 Yong, P., 297, 717 Yong-Hui, Y., 2453 Yongru, Z., 3062 Yonker, C. R., 2677, 2678 Yoshida, H., 2723 Yoshida, N., 68, 2851 Yoshida, S., 93 Yoshida, Y., 753, 790, 791 Yoshida, Z., 699, 706, 708, 727, 753, 758, 762, 767, 770, 775, 790, 791, 856, 1049, 1405, 1407, 1409, 1424, 1434, 2095, 2096, 2098, 2099, 2100, 2426, 2534, 2678, 2679, 2680, 2681, 2682, 2683, 2684, 3045, 3099 Yoshihara, K., 473 Yoshihara, S., 395 Yoshihiro, M., 856 Yoshikawa, S., 1625

I-288

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Yoshiki, N., 2693, 2717 Yosida, Z., 1430 Yosikama, H., 2637 Youmans, W. B., 3357 Young, A. P., 377, 378 Young, B., 1507 Young, B. L., 1268 Young, D. A., 3307 Young, E. J., 363, 367 Young, G. A., 303 Young, J. P., 502, 503, 519, 528, 1315, 1446, 1453, 1455, 1456, 1458, 1462, 1465, 1468, 1469, 1470, 1471, 1474, 1485, 1529, 1530, 1533, 1534, 1543, 1545, 1547, 1579, 1596, 1598, 1599, 1600, 1601, 1880, 1882, 2077, 2417, 2420, 2422, 3321 Young, R. C., 62, 81, 82 Youngdahl, K. A., 2979 Youngs, T. G. A., 2674 !yres, J. A., 336 Ysauoka, H., 2280 Ythier, C., 25 Yu, M., 108 Yu, X., 164 Yu, Z., 77 Yuan, S., 77, 164, 189, 191 Yuan, V. W., 967 Yuchs, S. E., 3152, 3157, 3158 Yudin, G. L., 1516 Yu-fu, Y., 3026, 3028, 3031, 3032, 3066 Yu-Guo, F., 2453 Yui, M., 1160, 1162, 3134, 3135, 3136 Yuile, C. L., 3351, 3354, 3355, 3424 Yuita, K., 709, 784, 789, 3327 Yukawa, M., 3062 Yun, S. W., 407 Yungman, V. S., 2114, 2148, 2149, 2161, 2185 Yunlu, K., 2472, 2817, 2818, 2824 Yushkevich, Y. V., 822 Yusov, A. B., 626, 988, 1327, 1336, 1355, 1368, 1405, 1425, 1429, 1430, 1433, 2096, 2583, 3124, 3126 Yussonnua, M., 1664, 1703 Yustein, J. T., 1988, 1989 Yuxing, Y., 1278, 2653 Yvon, J., 824 Zabinsky, S. I., 3089 Zablocka-Malicka, M., 475, 495 Zachara, J. M., 274, 1810, 3156, 3178, 3179, 3180, 3181 Zachariasen, W. H., 34, 35, 36, 69, 71, 75, 79, 80, 87, 90, 91, 95, 96, 97, 98, 191, 192, 193, 194, 195, 196, 198, 201, 206, 207, 229, 329, 350, 372, 373, 379, 380, 405, 413, 414, 423, 439, 447, 455, 459, 460,

461, 462, 463, 488, 502, 503, 529, 539, 543, 567, 718, 719, 740, 879, 882, 885, 886, 887, 906, 907, 915, 936, 938, 988, 1006, 1012, 1015, 1019, 1028, 1044, 1082, 1083, 1084, 1096, 1097, 1102, 1105, 1109, 1112, 1164, 1295, 1297, 1303, 1312, 1315, 1317, 1325, 1357, 1358, 1359, 1360, 1403, 1415, 1419, 1420, 1458, 1463, 1519, 1754, 1786, 2315, 2386, 2388, 2389, 2390, 2391, 2394, 2395, 2396, 2397, 2402, 2403, 2407, 2411, 2411.2413, 2413, 2417, 2418, 2420, 2421, 2422, 2426, 2427, 2431, 2439 Zacharova, F. A., 2527 Zachwieja, U., 410 Zadeii, J. M., 133 Zadneporovskii, G. M., 458, 487 Zadov, A. E., 268, 298 Zadvorkin, S. M., 334, 335 Zagrai, V. D., 847 Zagrebaev, V. I., 14, 1654, 1719, 1736, 1738 Zahn, R., 1880, 1881, 1882, 1883 Zahradnik, P., 3173 Zahrt, J. D., 1058, 1059, 1060, 1062 Zaiguo, G., 1267 Zainel, H. A., 2156 Zaitsev, A. A., 1330, 1331, 1335, 1352, 1405, 1428, 1433, 1553, 2652 Zaitsev, B., 2739 Zaitsev, B. N., 2739 Zaitsev, L. M., 108, 771, 1123, 1163, 1172, 1352 Zaitseva, L. L., 113, 1095, 1100, 1101, 1102, 1106, 1107, 1108, 2426 Zaitseva, N. G., 28, 43, 822 Zaitseva, V. P., 504, 1175 Zak, O., 3375 Zakharov, L. N., 1965, 2859 Zakharov, V. A., 2999 Zakharova, F. A., 749, 753, 1113, 1118, 1133, 1156, 3124 Zakhvataev, B. B., 1663, 1690 Zalduegui, J. F. S., 3284 Zalikin, G. A., 3352, 3424 Zalkin, A., 67, 71, 78, 82, 83, 106, 116, 208, 423, 580, 1187, 1188, 1943, 1944, 1960, 2251, 2256, 2404, 2405, 2418, 2429, 2434, 2436, 2471, 2472, 2473, 2476, 2478, 2479, 2480, 2481, 2482, 2483, 2486, 2487, 2488, 2489, 2558, 2561, 2802, 2805, 2806, 2808, 2812, 2833, 2834, 2837, 2852, 2856, 2867, 2877, 2879, 2923 Zaloudik, J., 1507 Zalubas, R., 59, 60, 1843, 1844 Zambonini, F., 111 Zamir, D., 64, 994, 995, 3206

Author Index

I-289

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Zamorani, E., 1033 Zamzow, D., 3036 Zanazzi, P. F., 3170 Zanella, P., 116, 452, 2472, 2473, 2479, 2484, 2801, 2820, 2825, 2826, 2841, 2843 Zanella, R., 2819, 2824 Zaniel, H., 2208, 2211 Zannoni, E., 2100 Zanonato, P., 2568, 2584, 3102, 3142, 3143, 3145 Zanotti, G., 2479 Zantuti, F., 705 Zaritskaya, T. S., 1398 Zarki, R., 3024 Zarli, B., 2439, 2440 Zasorin, E. Z., 1681 Zauner, S., 185, 186, 1447, 1662, 1687, 1698, 1699, 1700, 1705, 1709, 1710, 1718, 1879, 1884 Zavalsky, Yu. P., 184 Zavizziano, H., 174 Zawodzinski, T. A. J., 2687 Zazzetta, A., 2490, 2491, 2493, 2859 Zdanowicz, E., 100 Zech, P., 1507 Zeelie, B., 482, 492, 496, 498, 574 Zeh, P., 3057 Zehnder, A., 1447 Zekany, L., 1166 Zeldes, H., 2266 Zelenkov, A. G., 164, 166 Zelentov, S. S., 726 Zelinski, A., 191 Zeller, R., 2236 Zeltman, A. H., 529, 530 Zemann, H., 3159, 3163 Zemb, T., 2649, 2657 Zemlyanukhin, V. I., 1271 Zemskov, B. G., 793 Zenkova, R. A., 1320 Zeoeda, E., 3308 Zerner, M., 1943, 1946, 1949 Zeyen, C. M. E., 81 Zhang, D., 2923 Zhang, F., 927 Zhang, H., 116, 2240, 2473, 2480, 2484, 2803, 2804, 2812, 2816, 2829, 2844, 2845, 2912 Zhang, H. B., 76 Zhang, J., 265, 2452, 2665 Zhang, L., 3117 Zhang, P., 2665, 2753 Zhang, Q., 231 Zhang, W., 3062 Zhang, X., 164, 186, 791 Zhang, X. F., 2831 Zhang, Y., 266 Zhang, Y. X., 861

Zhang, Y.-J., 2442, 2447, 2448 Zhang, Z., 254, 271, 280, 291, 577, 627, 1192, 1199, 1777, 1897, 1909, 1910, 1928, 1930, 2037, 2400 Zhangji, L., 2591 Zhangru, C., 265 Zhao, D., 298 Zhao, H. T., 3409 Zhao, J., 786 Zhao, J. G., 1908, 1909 Zhao, K., 1943, 1946, 1949, 1951, 1952, 2864 Zhao, P. H., 2591 Zhao, X., 3014, 3063 Zhao, X. L., 3063, 3317, 3318 Zhao, Y., 795, 1933, 3057 Zhao, Z., 76 Zharova, T. P., 760 Zharskii, I. M., 1681 Zheng, D., 2924 Zheng, H. S. Z., 2752 Zheng, P. J., 2831 Zhernosekov, K., 1479, 3101, 3102, 3111, 3112, 3113, 3114 Zhong, C., 2453 Zhong, J., 795 Zhorin, V. V., 2042, 2047, 2048, 2049, 2053, 2059, 2061 Zhou, G.-F., 1285 Zhou, J. S., 1059 Zhou, M., 1918, 1919, 1969, 1972, 1973, 1974, 1980, 1981, 1982, 1983, 1985, 1986, 1987, 1988 Zhou, M. F., 1977, 1978, 1979, 1980, 1982, 1983, 1984, 1985, 1990 Zhou, M. L., 108 Zhou, S., 928 Zhu, D.-H., 3420 Zhu, J., 1285, 2966, 2974 Zhu, S., 2681 Zhu, W. J., 77 Zhu, X.-H., 2965 Zhu, Y., 29, 713, 785, 1274, 1287, 1288, 1352, 1363, 1407, 1412, 2562, 2665, 2676, 2752, 2753, 2754, 2762 Zhuchko, V. E., 1707 Zhuikov, B. L., 1628, 1634, 1670, 1672, 1692, 1693 Zhuk, M. I., 113 Zhuravelova, A. K., 3352, 3424 Zhuravleva, G. I., 711, 761, 1128, 1129, 1130, 1140, 1141, 1142, 2757 Ziegler, M., 3420 Ziegler, S., 1881 Ziegler, T., 1907 Zielen, A. J., 606, 748, 781, 1181, 1356, 2527, 2583, 2594, 2599, 3125 Zielinski, P., 1713, 1714, 1737, 1738

I-290

Author Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Zielinski, P. M., 1662, 1664, 1666, 1685, 1695, 1701, 1702, 1712, 1713, 1714, 1716, 1717, 1735 Zigmunt, A., 338, 339 Zijp, W. L., 164, 187 Zikovsky, L., 130, 131 Zilberman, B., 1145 Zilberman, B. Y., 2757 Zilberman, B. Ya., 711, 761 Ziller, J. W., 1956, 1967, 2473, 2476, 2477, 2804, 2805, 2816, 2857 Ziman, J. M., 2308 Zimmer, E., 120, 121, 2736 Zimmer, K., 1735 Zimmerman, H. P., 185, 1447 Zimmerman, J. B., 633, 3282 Zimmermann, H., 116, 2865 Zimmermann, H. P., 182, 1704, 1705 Zimmermann, J. I. C., 254 Zimmermann, M. V., 2288 Zinder, B., 3030, 3031 Zingaro, R. A., 3024 Zingeno, R. A., 313 Zipkin, J., 817, 1626, 1633, 1639, 1644 Zirkle, R. E., 3340 Ziv, D. M., 20, 24, 38, 39, 40 Ziv, V. S., 179 Zivadinovich, M. S., 2430 Ziyad, M., 102, 110, 1172, 2431 Zlokazova, E. I., 1432, 1433 Zmbov, K. F., 70 Zocco, T. G., 882, 892, 916, 917, 918, 919, 920, 925, 930, 931, 933, 935, 960, 962, 964, 980, 984, 986, 987, 2355 Zocher, R. W., 1046 Zogal, O. J., 338 Zolnierek, A., 2283 Zolnierek, Z., 469, 491, 505, 2249, 2283, 2288

Zolotulcha, S. I., 175 Zongwei, L., 1699, 1700, 1710, 1718 Zonnevijlle, F., 2584 Zons, F. W., 111 Zorz, N., 2657, 2658 Zouiri, M., 2431 Zozulin, A. J., 452, 2472, 2801, 2807, 2891 Zschack, P., 965, 967 Zubarev, V. G., 1322, 1323 Zubavichus, Y. V., 3087 Zuev, Y. N., 989, 996 Zukas, E. G., 920, 921, 933, 936 Zumbusch, M., 96, 98, 2411 Zumsteg, I., 3029, 3030, 3283 Zumsteg, M., 3283, 3293, 3296 Zunger, A., 928 Zunic, T. B., 113 Zur Nedden, P., 1352 Zuraeva, I. T., 1683 Zussman, J., 3169 Zvara, I., 1451, 1468, 1524, 1593, 1625, 1628, 1633, 1634, 1640, 1645, 1660, 1663, 1664, 1684, 1690, 1692, 1693, 1695, 1700, 1703, 1705, 1706, 1720, 2123 Zvarova, T. S., 1663, 1664, 1690, 1703 Zwanenburg, G. J., 203 Zwick, B. D., 289, 439, 454, 455, 602, 752, 849, 1166, 1167, 1182, 1183, 1184, 1185, 1186, 1190, 2484, 2486, 2583, 2802, 2813, 2814, 2867, 2876, 3109, 3130, 3131, 3160, 3167 Zwicknagl, G., 2347 Zwirner, S., 719, 720 Zych, E., 422, 427, 428, 429, 435, 436, 437, 438, 440, 444, 449, 451, 453, 454 Zygmunt, A., 338 Zygmunt, S. A., 1991, 3113, 3118

THE CHEMISTRY OF THE

ACTINIDE AND TRANSACTINIDE ELEMENTS

Joseph J. Katz

Glenn T. Seaborg

This work is dedicated to Joseph J. Katz and Glenn T. Seaborg, authors of the first and second editions of The Chemistry of the Actinide Elements and leaders in the field of actinide chemistry.

THE CHEMISTRY OF THE

ACTINIDE AND TRANSACTINIDE ELEMENTS THIRD EDITION

Volume 1 EDITED BY Lester R. Morss Argonne National Laboratory, Argonne, Illinois, USA

Norman M. Edelstein Lawrence Berkeley National Laboratory, Berkeley, California, USA

Jean Fuger University of Lie`ge, Lie`ge, Belgium

Honorary Editor Joseph J. Katz Argonne National Laboratory

Library of Congress Control Number: 2008922620

ISBN-10 1-4020-3555-1 (HB) ISBN-10 1-4020-3598-5 (e-book) ISBN-13 978-1-4020-3555-5 (HB) ISBN-13 978-1-4020-3598-2 (e-book)

Published by Springer, P.O. Box 17, 3300 AA Dordrecht, The Netherlands.

www.springer.com

Printed on acid-free paper

All Rights Reserved First published in 2006 Reprinted 2006 Reprinted with corrections in 2008 # 2006 and 2008 Springer Science + Business Media B.V. No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work.

CONTENTS Volume 1 ix xv

Contributors Preface 1. Introduction Joseph J. Katz, Lester R. Morss, Norman M. Edelstein, and Jean Fuger 2. Actinium H. W. Kirby and L. R. Morss 3. Thorium Mathias S. Wickleder, Blandine Fourest, and Peter K. Dorhout 4. Protactinium Boris F. Myasoedov, H. W. Kirby, and Ivan G. Tananaev 5. Uranium Ingmar Grenthe, Janusz Droz˙dz˙yn´ski, Takeo Fujino, Edgar C. Buck, Thomas E. Albrecht-Schmitt, and Stephen F. Wolf Subject Index (Volume 1) Author Index (Volume 1)

1

18 52 161 253

I-1 I-31

Volume 2 ix xv

Contributors Preface 6. Neptunium Zenko Yoshida, Stephen G. Johnson, Takaumi Kimura, and John R. Krsul 7. Plutonium David L. Clark, Siegfried S. Hecker, Gordon D. Jarvinen, and Mary P. Neu 8. Americium Wolfgang H. Runde and Wallace W. Schulz Subject Index (Volume 2) Author Index (Volume 2)

699

813

1265

I-1 I-27 v

vi

Contents

Volume 3 Contributors Preface

ix xv

9. Curium 1397 Gregg J. Lumetta, Major C. Thompson, Robert A. Penneman, and P. Gary Eller 10. Berkelium 1444 David E. Hobart and Joseph R. Peterson 11. Californium 1499 Richard G. Haire 12. Einsteinium 1577 Richard G. Haire 13. Fermium, Mendelevium, Nobelium, and Lawrencium 1621 Robert J. Silva 14. Transactinide Elements and Future Elements 1652 Darleane C. Hoffman, Diana M. Lee, and Valeria Pershina 15. Summary and Comparison of Properties of the Actinide and Transactinide Elements 1753 Norman M. Edelstein, Jean Fuger, Joseph J. Katz, and Lester R. Morss 16. Spectra and Electronic Structures of Free Actinide Atoms and Ions 1836 Earl F. Worden, Jean Blaise, Mark Fred, Norbert Trautmann, and Jean-Franc¸ois Wyart 17. Theoretical Studies of the Electronic Structure of Compounds of the Actinide Elements 1893 Nikolas Kaltsoyannis, P. Jeffrey Hay, Jun Li, Jean-Philippe Blaudeau, and Bruce E. Bursten 18. Optical Spectra and Electronic Structure 2013 Guokui Liu and James V. Beitz Subject Index (Volume 3) Author Index (Volume 3)

I-1 I-39

Volume 4 Contributors Preface 19. Thermodynamic Properties of Actinides and Actinide Compounds Rudy J. M. Konings, Lester R. Morss, and Jean Fuger 20. Magnetic Properties Norman M. Edelstein and Gerard H. Lander

ix xv 2113 2225

Contents

vii

21. 5f-Electron Phenomena in the Metallic State A. J. Arko, John J. Joyce, and Ladia Havela 22. Actinide Structural Chemistry Keith E. Gutowski, Nicholas J. Bridges, and Robin D. Rogers 23. Actinides in Solution: Complexation and Kinetics Gregory R. Choppin and Mark P. Jensen 24. Actinide Separation Science and Technology Kenneth L. Nash, Charles Madic, Jagdish N. Mathur, and Je´roˆme Lacquement

2307

Subject Index (Volume 4) Author Index (Volume 4)

I-1 I-35

2380 2524 2622

Volume 5 Contributors Preface 25. Organoactinide Chemistry: Synthesis and Characterization Carol J. Burns and Moris S. Eisen 26. Homogeneous and Heterogeneous Catalytic Processes Promoted by Organoactinides Carol J. Burns and Moris S. Eisen 27. Identification and Speciation of Actinides in the Environment Claude Degueldre 28. X-ray Absorption Spectroscopy of the Actinides Mark R. Antonio and Lynda Soderholm 29. Handling, Storage, and Disposition of Plutonium and Uranium John M. Haschke and Jerry L. Stakebake 30. Trace Analysis of Actinides in Geological, Environmental, and Biological Matrices Stephen F. Wolf 31. Actinides in Animals and Man Patricia W. Durbin

ix xv 2799

2911 3013 3086 3199

3273 3339

Appendix I Nuclear Spins and Moments of the Actinides Irshad Ahmad

3441

Appendix II Nuclear Properties of Actinide and Transactinide Nuclides Irshad Ahmad

3442

Cumulative Subject Index (Volumes 1, 2, 3, 4 and 5) Cumulative Author Index (Volumes 1, 2, 3, 4 and 5)

I-1 I-141

CONTRIBUTORS Irshad Ahmad Argonne National Laboratory, USA Thomas E. Albrecht-Schmitt Auburn University, Alabama, USA Mark R. Antonio Argonne National Laboratory, USA A. J. Arko Los Alamos National Laboratory, USA (retired) James V. Beitz Argonne National Laboratory, USA (retired) Jean Blaise Laboratoire Aime´ Cotton, Orsay, France Jean-Philippe Blaudeau High Performance Technologies, Inc., Wright-Patterson Air Force Base, Ohio, USA Nicholas J. Bridges The University of Alabama, USA Edgar C. Buck Pacific Northwest National Laboratory, Richland, Washington, USA Carol J. Burns Los Alamos National Laboratory, USA Bruce E. Bursten The University of Tennessee, USA Gregory R. Choppin Florida State University, USA David L. Clark Los Alamos National Laboratory, USA

ix

x

Contributors

Claude Degueldre Paul Scherrer Institute, Switzerland Peter K. Dorhout Colorado State University, USA Janusz Droz˙dz˙yn´ski University of Wroclaw, Poland Patricia W. Durbin Lawrence Berkeley National Laboratory, USA Norman M. Edelstein Lawrence Berkeley National Laboratory, USA Moris S. Eisen Technion -Israel Institute of Technology, Israel P. Gary Eller Los Alamos National Laboratory, USA (retired) Mark Fred Argonne National Laboratory, USA (deceased) Blandine Fourest Institut de Physique Nucle´aire, Orsay, France Jean Fuger University of Lie`ge, Belgium Takeo Fujino Tohoku University, Japan (retired) Ingmar Grenthe Royal Institute of Technology, Stockholm, Sweden Keith E. Gutowski The University of Alabama, USA Richard G. Haire Oak Ridge National Laboratory, USA John M. Haschke Actinide Science Consulting, Harwood, TX, USA

Contributors Ladia Havela Charles University, Czech Republic P. Jeffrey Hay Los Alamos National Laboratory, USA Siegfried S. Hecker Los Alamos National Laboratory, USA David E. Hobart Los Alamos National Laboratory, USA Darleane C. Hoffman Lawrence Berkeley National Laboratory, USA Gordon D. Jarvinen Los Alamos National Laboratory, USA Mark P. Jensen Argonne National Laboratory, USA Stephen G. Johnson Idaho National Laboratory, USA John J. Joyce Los Alamos National Laboratory, USA Nikolas Kaltsoyannis University College London, UK Joseph J. Katz Argonne National Laboratory, USA (retired) Takaumi Kimura Japan Atomic Energy Agency, Japan Harold W. Kirby (deceased) Mound Laboratory, Miamisburg, Ohio, USA Rudy J. M. Konings European Commission, Joint Research Centre Institute for Transuranium Elements, Karlsruhe, Germany John R. Krsul Argonne National Laboratory, USA (retired)

xi

xii

Contributors

Je´roˆme Lacquement CEA-Valrho, Marcoule, France Gerard H. Lander European Commission, Joint Research Centre Institute for Transuranium Elements, Karlsruhe, Germany Diana M. Lee Lawrence Berkeley National Laboratory, USA Jun Li Pacific Northwest National Laboratory, Richland, Washington, USA Guokui Liu Argonne National Laboratory, USA Gregg J. Lumetta Pacific Northwest National Laboratory, Richland, Washington, USA Charles Madic CEA-Saclay, Gif-sur-Yvette, France Jagdish N. Mathur Bhabha Atomic Research Centre, Mumbai, India Lester R. Morss Argonne National Laboratory (retired) and U.S. Department of Energy, Washington DC, USA Boris F. Myasoedov Russian Academy of Sciences, Moscow, Russia Kenneth L. Nash Washington State University, USA Mary P. Neu Los Alamos National Laboratory, USA Robert A. Penneman Los Alamos National Laboratory, USA (retired) Valeria Pershina Gesellschaft fu¨r Schwerionenforschung, Darmstadt, Germany

Contributors Joseph R. Peterson The University of Tennessee, USA and Oak Ridge National Laboratory, USA (retired) Robin D. Rogers The University of Alabama, USA Wolfgang Runde Los Alamos National Laboratory, USA Wallace W. Schulz Albuquerque, New Mexico, USA Robert J. Silva Lawrence Livermore National Laboratory, USA (retired) Lynda Soderholm Argonne National Laboratory, USA Jerry L. Stakebake Boulder, Colorado, USA Ivan G. Tananaev Russian Academy of Sciences, Moscow, Russia Major C. Thompson Savannah River National Laboratory, USA (retired) Norbert Trautmann Universita¨t Mainz, Germany Mathias S. Wickleder Carl von Ossietzky Universita¨t, Oldenburg, Germany Stephen F. Wolf Indiana State University, Terre Haute, Indiana, USA Earl F. Worden, Jr. Lawrence Livermore National Laboratory, USA (retired) Jean-Franc¸ois Wyart Laboratoire Aime´ Cotton, Orsay, France Zenko Yoshida Japan Atomic Energy Agency, Japan

xiii

PREFACE The first edition of this work (The Chemistry of the Actinide Elements by J. J. Katz and G. T. Seaborg) was published in 1957, nearly a half century ago. Although the chemical properties of thorium and uranium had been studied for over a century, and those of actinium and protactinium for over fifty years, all of the chemical properties of neptunium and heavier elements as well as a great deal of uranium chemistry had been discovered since 1940. In fact, the concept that these elements were members of an “actinide” series was first enunciated in 1944. In this book of 500 pages the chemical properties of the first transuranium elements (neptunium, plutonium, and americium) were described in great detail but the last two actinide elements (nobelium and lawrencium) remained to be discovered. It is not an exaggeration to say that The Chemistry of the Actinide Elements expounded a relatively new branch of chemistry. The second edition was published in 1986, by which time all of the actinide elements had been synthesized and chemically characterized, at least to some extent. At this time the chemistry of the actinide elements had reached maturity. The second edition filled two volumes, with a chapter for each of the elements (the elements beyond einsteinium were combined in one chapter) and systematic treatment of various aspects of the chemical and electronic properties of the actinide elements, ions, and compounds due to the filling of the 5f subshell. Six transactinide elements had been synthesized by 1986 but their experimentally determined chemical properties occupied only 1.5 pages of text in the second edition. This edition was initiated by the editors of the second edition (J. J. Katz, G. T. Seaborg, and L. R. Morss) in 1997. They realized that the study of the chemical properties of the actinide elements had advanced to produce distinct subdisciplines of actinide chemistry, for example actinide coordination chemistry, actinide X-ray absorption spectroscopy, itinerancy in actinide intermetallics, organoactinide chemistry, and actinide environmental chemistry. These fields had sufficiently matured so that scientists could make more substantial contributions to predicting and controlling the fate of actinides in the laboratory, in technology, and in the environment. We now understand and are able to predict with some degree of confidence the chemical bonding and reactivity of actinides in actinide materials, in actual environmental matrices and in proposed nuclear waste repositories. Most of the unique properties of the actinides are caused by their accessible and partly filled 5f orbitals. In addition to advances with the actinides, there have been research groups at nuclear research centers in several countries that have dedicated themselves to carry out significant and systematic experimental studies on the transactinide elements for several decades. For these reasons the editors initiated the writing of a third edition, with the xv

xvi

Preface

enlarged title The Chemistry of the Actinide and Transactinide Elements that is both broader and deeper than the second edition. The third edition follows the plan enunciated by the authors of the first edition: “This book is intended to provide a comprehensive and uniform treatment of the chemistry of the actinide [and transactinide] elements for both the nuclear technologist and the inorganic and physical chemist.” To fulfill this plan consistent with the maturity of the field, the third edition is organized in three parts. The first group of chapters follows the format of the first and second editions by beginning with chapters on individual elements or groups of elements that describe and interpret their chemical properties. A chapter on the chemical properties of the transactinide elements is included. The second group, chapters 15-26, summarizes and correlates physical and chemical properties that are in general unique to the actinide elements, because most of these elements contain partially-filled shells of 5f electrons whether present as isolated atoms or ions, as metals, as compounds, or as ions in solution. The third group of chapters (chapters 27-31) focuses on specialized topics that encompass contemporary fields related to actinide species in the environment, in the human body, and in storage or wastes. There are also two appendices that tabulate important nuclear properties of all actinide and transactinide isotopes. Each chapter has been written to provide sufficient background for the substantial parts of the readership that are not specialists in actinide science, nuclear-science-related areas (nuclear physics, health physics, nuclear engineering), spectroscopy, or solid-state science (metallurgy, solid state physics). The editors hope that this work educates and informs those readers who are scientists and engineers that are unfamiliar with the field and wish to learn how to deal with actinides in their research or technology. The editors are deeply indebted to the contributors of each chapter, all of whom agreed enthusiastically to write their chapters and all of whom did so as a labor of love as well as a long-term professional responsibility. We take special pleasure in thanking Dr. Emma Roberts, Senior Publishing Editor of Springer, who provided the resources to turn more than thirty manuscripts into this attractive and useful professional series of volumes. We also thank Roger Wayman and Aaliya Jetha of Springer and all the other professional staff at Springer and SPI Publisher Services who brought this work to completion. The editors dedicate this work to Joseph J. Katz and Glenn T. Seaborg, the first authors of the first edition and second editions of The Chemistry of the Actinide Elements. They provided inspiration for the generations of scientists who followed them and they set high standards in their research. Dr. Katz guided and motivated the editors and authors of the third edition to produce a work that followed the model of the first and second editions and provided leadership as this edition was unfolding. Because of his insights and leadership as an inorganic, physical, and actinide chemist, we have asked Dr. Katz to be

Preface

xvii

listed on the title page as honorary editor, and he has agreed to accept this role. The editors also dedicate this work to the memory of Professor Seaborg, the codiscover of plutonium and many other actinide and transactinide elements, and pioneer in actinide chemistry. We note with sadness that he participated in planning this edition but passed away before any of the chapters had been written. We believe that he would have been pleased to see how productive has been the research of the authors and many other actinide and transactinide scientists who follow his leadership. All of us who have participated in the writing, editing, and publishing The Chemistry of the Actinide and Transactinide Elements express our hope that this new edition will make a substantive contribution to research in actinide and transactinide science, and that it will be an appropriate source of factual information on these elements for teachers, researchers, and students and for those who have the responsibility for utilizing the actinide elements to serve humankind and to control and mitigate their environmental hazards. Lester R. Morss Norman M. Edelstein Jean Fuger

CHAPTER TWENTY ONE

5f‐ELECTRON PHENOMENA IN THE METALLIC STATE A. J. Arko, John J. Joyce, and Ladia Havela

21.1 21.2 21.3 21.4 21.5 21.6

21.7 21.8

Strong correlations 2341 Conventional and unconventional superconductivity 2350 21.9 Magnetism in actinides 2353 21.10 Cohesion properties – influence of high pressure 2368 21.11 Concluding remarks 2372 Abbreviations 2372 References 2373

Introduction 2307 Overview of actinide metals 2309 Basic properties of metals (freeelectron model) 2313 General observations of 5f bands in actinides 2329 Strongly hybridized 5f bands 2333 Weak correlations – landau fermi liquid 2339

21.1 INTRODUCTION

In this chapter, the properties of actinides in the metallic state will be reviewed with an emphasis on those properties which are unique or predominantly found in the metallic solid state. Such properties include magnetism, superconductivity, enhanced mass, spin and charge‐density waves, as well as quantum critical points. An introduction to fundamental condensed matter principles is included to focus the discussion on the properties in the metallic state. Systematics of the actinide 5f electronic structure will be presented for elements, alloys, metallic, and semi‐metallic compounds so as to elucidate the unique characteristics that arise from the properties of actinides and 5f electrons in a periodic potential. There are two defining characteristics to materials in the metallic state: first, the material exhibits a periodic potential which controls much of the electronic structure, and second, there is a finite density of electronic states at the chemical potential which influences, among other properties, the thermodynamic and 2307

2308

5f‐electron phenomena in the metallic state

transport characteristics. For the early actinide metals, these two characteristics are often manifested as narrow bands containing a substantial 5f electron component. Complexity in material properties often arises when competing or overlapping energy scales are available. In the metallic state, with a continuum of electron energy levels available, there is the possibility for interaction of charge with spin and lattice degrees of freedom. Because the actinides have an open 5f electron shell which, in the metallic state, often straddles the boundary between localized and itinerant character, the interplay between spin, charge, and lattice degrees of freedom leads to varied and interesting properties. In order to better understand the controlling role of the 5f electrons in the metallic state, one should look beyond the elements and beyond standard temperature and pressure. To elucidate the fundamental properties of 5f electrons in the metallic state, we consider the actinide elements at low temperature and high pressure. An additional dimension to the understanding of the 5f metals can be attained by considering the actinide elements in a metallic host matrix, e.g. alloys and compounds. Atoms in a closely spaced periodic environment (crystalline condensed matter) experience an overlapping of outer electron shells with neighboring atoms. If the outer shells are open, then these electrons are shared between neighboring atoms and can travel from atom to atom through the periodic array. This sharing of electrons, a form of bonding, becomes the glue that holds the atoms together. In the crudest sense, this is the metallic state. Here attention is given to those atoms (materials) whose outer shell comprises an unfilled 5f shell, namely, actinide materials. A thorough treatment of the subject covers volumes (Kittel, 1963, 1971; Ziman, 1972; Ashcroft and Mermin, 1976; Harrison, 1980, 1999), so the overview presented here is cursory. The intent is primarily to cover those aspects of the metallic state that differentiate 5f electron systems from simpler metals containing only s, p, or d electrons, since many properties of 5f systems appear anomalous by comparison. In the atomic and molecular configurations of f‐electron materials, the highly directional nature of the f‐orbitals plays a central role in the unique properties of the lanthanides and actinides. In the metallic state, however, it is widely accepted that it is the very limited radial extent of the 5f wave functions relative to the s, p, or d wave functions of the valence band that is at the heart of the exotic phenomena (consequently the 5f electrons are nearly localized), though the understanding of the actinides and their compounds is still incomplete. These metals and their compounds are among the most complex in the periodic table, displaying some of the most unusual behaviors relative to non‐f systems, such as very low melting temperatures, large anisotropic thermal expansion coefficients, very low‐symmetry crystal structures, many solid‐to‐solid phase transitions, exotic magnetic states, incommensurate charge‐density waves, etc. Some insights can be gained by using the 4f series as a guide, but the comparison is limited since the radial extent of the 4f electrons is even smaller than that of the 5f electrons.

Overview of actinide metals

2309

A comprehensive picture of actinides in the metallic state is slowly emerging. Many of the very unusual properties appear to be a direct consequence of the formation of extremely narrow 5f bands in which the electrons are not completely free. Rather, their motion is affected by the presence of neighboring 5f electrons. This differs from the lanthanide metals whose 4f electrons tend to be localized in atomic states except perhaps for Ce and Yb (Gschneidner and Eyring, 1993). In recent years, there have been many advances in the theoretical capability to calculate the electronic structure of materials that form narrow bands. In particular, extensions to density functional theory (DFT) now allow the inclusion of some of the electron–electron interactions that previously were the exclusive domain of many‐body physics. Yet even this approach often proves insufficient. The problem of narrow bands or localization of electrons in an unfilled shell is strongly related to magnetic properties as well. However, there is a fundamental difference between band magnetism and localized magnetism. Although the electronic and magnetic properties of a material are related, the pervasiveness and sheer volume of unusual magnetic behavior observed in the 5f series suggest that they be treated separately.

21.2.

OVERVIEW OF ACTINIDE METALS

The anomalous nature of the electronic properties of the 5f series of metals is apparent when considering the electrical resistivity, atomic volume (or equivalently the Wigner–Seitz radius), and a composite crystallographic phase diagram of the actinide metals through Cm. These physical properties are shown in Figs. 21.1–21.3. While these data have been presented on numerous occasions, they remain most illuminating, clearly showing a transition from itinerant (participating in bonding) behavior of the 5f electrons in the light actinides to localized (limited to an atomic site) behavior beyond Pu. It is the transition region that is least understood and where much of the anomalous behavior is centered. Fig. 21.1 shows the electrical resistivity, r, as a function of temperature for the actinides through Cm (the last element obtained in sufficient bulk to allow such measurements). One immediately sees that the overall resistivity increases dramatically up to a‐Pu (the low‐temperature stable phase of Pu) and then begins to drop for Am. The a‐Pu value of 150 mOhm cm (mO cm) is much higher than that of Cu (as a material with conventional metallic properties) where the room temperature value is of the order of 1 mO cm. The resistivity is intimately tied to the electronic structure of the material and several models ranging in complexity detail the relationship between resistivity and electronic structure. Within the free‐electron model, r is related to the relaxation time t of electrons

5f‐electron phenomena in the metallic state

2310

Fig. 21.1 Electrical resistivity as a function of temperature between 0 and 300 K for the actinides metals Th through Cm (after Hecker, 2001).

and mean free path defined as l ¼ vFt, where vF is the velocity of electrons at the Fermi surface, called Fermi velocity, by the relationship r ¼ m =Ne2 t 

ð21:1Þ

where m is the effective mass of electrons of charge e whose density is N. Clearly the mean free path of conduction electrons in 5f metals is very short and t is the time between two scattering events compared to normal metals. It is shortest for a‐Pu and begins to increase again with Am. Indeed, for a‐Pu the mean free path of the conduction electrons is no more than the interatomic spacing. One can hardly call these free electrons. Additionally, the a‐Pu resistivity increases with decreasing temperature, an effect contrary to normal metals like Cu, while it appears relatively normal for Th through U. Such a negative temperature dependence is often associated with magnetic scattering of electrons (thus decreasing their mean free path) although experimental evidence indicates a lack of magnetism in Pu metal. The Wigner–Seitz radius (Wigner and Seitz, 1933), or the equilibrium atomic volume of an atom in a metallic lattice, is likewise instructive, especially when compared to the volumes occupied by atoms in metals with an open 5d or 4f shell. Fig. 21.2 compares the Wigner–Seitz radius of the lanthanides and actinides with those of the 5d transition metals. It was shown by Friedel (1969) that the atomic volume should display a parabolic dependence with increasing atomic number Z as one fills an open shell of electrons involved in bonding

Overview of actinide metals

2311

Fig. 21.2 The Wigner–Seitz radius (RWS) for the lanthanides, actinides and the 5d transition metal series. The transition metals show a parabolic dependence with bonding d‐orbitals in accordance with the predictions of Friedel. The lanthanides display a nominally constant volume with non‐bonding 4f states. The actinides show mixed character with Th through a‐Pu on the bonding Friedel curve while Am–Cf look lanthanide‐like with a non‐bonding f‐character (courtesy of Los Alamos Science).

and conduction (i.e. the 5d electrons in Fig. 21.2). This is attributed to an increasing nuclear charge with its increasing Coulomb attraction, which is not completely screened by outer electrons shared by their neighbors, thus resulting in a volume contraction. But then, as the shell fills, the screening is again effective and the atom relaxes. If, on the other hand, the outer electrons are instead localized as is the case of the 4f electrons in lanthanides, then the nuclear charge for each value of Z is effectively screened by the localized electrons, and the atomic volume remains unaffected as Z increases. This is clearly evident for the lanthanides in Fig. 21.2, except for Eu and Yb, exhibiting valency irregularities (the metals are divalent, not trivalent as the other lanthanides). The atomic volumes of early actinides appear to follow a parabolic curve up to the metal Np, suggesting 5f participation in bonding, but then begin to strongly deviate, behaving more like the

2312

5f‐electron phenomena in the metallic state

Fig. 21.3 The binary phase diagram for the actinides Am through Cm showing the reduction in melting point and increase in complexity of the crystal structure and phases as the series moves from bonding (Ac–U) through localized (Am, Cm) with Pu having the lowest symmetry a‐phase as well as the lowest melting point and six solid state allotropes (after Smith and Kmetko, 1983).

localized 4f electrons beyond Pu (i.e. the atomic volumes remain relatively constant with increasing Z ). It is as if there were two distinct 5f series: the first ending with Np and the second beginning with Am. In the intermediate region, the various phases of Pu are found, and also much of the correlated electron behavior of interest in this chapter. The abrupt ending of the parabolic dependence of the equilibrium volumes of the actinides between plutonium and americium differentiates them from the lanthanides and the transition metals. But in addition, the transition metals and actinides also differ in their low‐temperature crystal structures. The transition metals form close‐packed, high‐symmetry structures, such as hexagonal close‐ packed (hcp), face‐centered cubic (fcc), and body‐centered cubic (bcc), whereas the light actinides form at low temperatures low‐symmetry, open‐packed structures. For instance, protactinium forms a body‐centered tetragonal (bct) structure, and uranium and neptunium form orthorhombic structures with two and eight atoms per cell, respectively. These data suggest that anomalous behavior already starts in the light actinides where many compounds of the light actinides display strongly correlated electron behavior (Ott and Fisk, 1987; Stewart, 2001). The crystal structures, along with alloying information, are summed up in the composite phase diagram of Fig. 21.3 (Smith and Kmetko, 1983).

Basic properties of metals ( free‐electron model)

2313

This phase diagram is composed of a series of binary phase diagrams of adjacent actinide metals from Ac to Cm plotted side by side (the x‐axis between any two adjacent metals varies from 0 to 100% of the content of the heavier metal). The shaded areas having no crystal structure label represent areas of uncertainty. In the early part of the series (between Ac and Th) structures are obtained somewhat similar to transition metals while beyond Am, typical structures of the rare earth metals are found. Indeed, it appears that beyond Am the anticipated ‘second rare earth series’ is obtained. In the region of Np and Pu, however, striking deviations from normal behavior are observed. The most obvious is the large drop in the melting temperature, reaching a value as low as 600 C near Np and Pu. Equally anomalous in this region, however, are the large number of allotropes, or solid‐state crystalline phases. In fact, the actinides have the largest number of allotropes of any series in the periodic table. Also in this region one obtains the highest number of bonding f‐electrons. Many of these relevant parameters to actinide metals are captured in Table 21.1. Note the appearance of magnetism in the second rare earth series above Am, as well as the absence of many‐body ordering phenomena in Pu and Np and the superconductivity in the light actinides (Am would nominally be magnetic if not for a fortuitous J ¼ 0 ground state allowing for superconductivity). The occurrence of interesting electronic properties increases enormously as one changes from the pure actinide elements to actinide alloys and compounds. Figs. 21.1–21.3 are entirely consistent with each other. The metallic radii are smallest at the crossover to localization, and as shown in Fig. 21.2, the low‐ temperature phases of the heavier actinides (beginning with americium) form dhcp structures. As in most metals, it is the bcc phase that forms prior to melting. However, the temperature range over which this phase is formed in the actinides is very small compared to transition metals and appears to be another signature of narrow bands, as described below (Wills and Eriksson, 2000). A detailed description of the properties for Pu metal is presented in Chapter 7. Here the emphasis is on overall 5f electronic properties and their differences from simpler metals. To recognize these differences, a short discussion of free electron and condensed‐matter behavior is presented. The papers by Boring and Smith (2000), and Wills and Eriksson (2000) serve as more detailed references and the main sources for this material.

21.3 BASIC PROPERTIES OF METALS (FREE‐ELECTRON MODEL)

21.3.1

Formation of energy bands in simple metals

In general, most materials (metal or non‐metal), when condensed in the solid state, form a crystalline array of repeating unit cells. Indeed, it is this repetition in space that allows for the mathematical determination of the electron wave

plutonium

neptunium

uranium

protactinium

actinium thorium

Element

912  3

1408  2

1845  20

2023  10

1323  50

Melting pointa,b (K)

349.0  3.0

465.1  3.0

b, monocl.

a, monocl.

g, bcc

b, tetrag.

a, orthorh.

g, bcc

a, bc tetrag. b, bcc or fcc a, orthorh. b, tetrag.

570  10 533  8

fcc a, fcc b, bcc

418  20 602  6 5.315(5) 5.0842 4.11 (1450K) 3.929

2.854 5.656(5) (995K) 1049–1408 3.524(2) (1078K) below 553 6.663 (293K) 553–849 4.897 (586K) 849–912 3.518 (873K) below 397.6 6.183 (294 K) 397.6–487.9 9.284 (463K)

below 1443 1443–1845 below 941 941–1049

below 1633 1633–2023 3.241

˚) co (A

10.463

4.822

4.723

7.859

10.963

3.388

4.887

5.87 4.955 10.759(5) 10.759(5)

Enthalpy of Lattice constants a,c sublimationa,b at 298.15 K Lattice Temperature ˚) ˚) (kJ mol–1) symmetrya–c range (K)a–c ao (A bo (A

93.13

17.71

101.79 19.85

18.08

19.38

20.48

18.06

19.04 18.11

15.37

10.01 11.724

X‐ray density (g cm–3) b (deg) (calc)

34

16

2

4

8

2

4 30

2

4 4 2

Z (atoms per unit cell)a,c

Table 21.1 Properties of actinide metals.

1.571

1.523

1.53

1.511

1.503

1.548

1.542 1.548

1.643

1.878 1.798 1.80

43(2)

118

104(2)

118(2)

59.0(9)

Metallic radius Bulk CN 12 modulus a,c,e ˚ (A) (GPa)f

17(1)

14

10

6.6

4

5.5

5.3

5.5

3.8

2.7

.93

Low T specific heat w0 coeff. (10–4emu/ meff 2 g g (mJ/mol K ) mol)h,i (mB)j

0.68 SC

1.4 SC

1.37 SC

Ordering temp. (K)l

einsteinium

11.040

11.069(7)

11.34(1)d

11.25

4.44

10.162

13.24 15.1 15.1 8.84

13.5 12.7 14.79

13.67 13.69

16.51

4 4 4 4

4 4 4

4 4

2

2

4

15.92 16.03

8

17.15

1.767 1.691 1.69 2.03

1.743 1.782 1.704

1.730 1.730

1.592

1.640

1.640

1.588

50

25

33

30

29.9

2

64(3)

6.8

5.2

5.1

5.1

5.2

11.3?

9.7

8.5

51 FM

34 AF

8.07k 52 AFk

0.79 SC

b

Values from Chapters 2–12. Values taken from Chapter 19. c Values taken from Chapter 22, at 298.15 K, except as noted. d From Stevenson and Peterson (1979). e See also Zachariasen (1973). f Th (Benedict and Holzapfel, 1993); Pa, U, and Am (Lindbaum et al., 2003); Np (Dabos et al., 1987); a‐Pu (Dabos‐Seignon et al., 1993); d‐Pu, from measurements on a single crystal of Pu with 3.3 atomic% Al (Ledbetter and Moment, 1976); Cm, Bk, and Cf (Benedict, 1987). g Th (Gordon et al., 1966); Pa (Spirlet et al., 1987); U (Bader et al., 1975); Np (Mortimer, 1979); a‐Pu and d‐Pu0.955Al0.05 (Lashley et al., 2003); Am (Smith et al., 1979). h Temperature‐independent susceptibility w0. i Most of these elements show a slight temperature dependence, possibly due to impurities. Data taken from Nellis and Brodsky (1974) except Th (Greiner and Smith, 1971); Pu (Olsen et al., 1992). j Effective magnetic moment in units of Bohr magnetons (mB). Different samples show rather different values. Representative values given. Data taken from Chapter 20 except as noted. k This Cm value is from Kanellakopulos et al. (1975). l Superconducting (SC), antiferromagnetic (AF), ferromagnetic(FM). Data for ordering temperatures of the transamericium actinides are from Chapter 20 except as noted.

a

1173  30 1133 130  10

310  10

384  10

196  10

1323  50

1619  50

1449  5

283.8  1.5

californium

berkelium

curium

americium

913  2

487.9–593.1 3.159 5.768 (508K) d, fcc 593.1–736.0 4.637 (593K) d0 , bc tetrag. 736.0–755.7 3.34 (738K) e, bcc 755.7–913.0 3.6361 (763K) a, dhcp below 1042 3.47 b, fcc 1042–1350 4.89 g, bcc? 1350–1449 unknown a, dhcp below 1568 3.500(3)d b, fcc 1568–1619 5.065 a, dhcp below 3.416(3) 1250 b, fcc 1250–1323 4.997(4) a, dhcp below 973 3.384(3) b, fcc

973–1173 4.78(1) fcc 5.75(1)

g, orthorh.

2316

5f‐electron phenomena in the metallic state

functions to within a phase factor. These cyclic wave functions are called Bloch states after Felix Bloch, who first introduced them (Bloch, 1928). The simplest elements, with a single outer electron, such as lithium or sodium, typically form cubic crystal structures at room temperature. The outer electrons from their atomic valence shells become conduction electrons traveling almost freely through the lattice. That is, these valence electrons occupy one‐electron Bloch states, and they are therefore responsible for bonding in the solid. A logical progression can be followed for band formation starting from the isolated atom, to molecules and finally, band formation and the formation of Bloch states in a metal. In the isolated atom, the electrons exist in a potential well with well‐defined energy levels or states. The levels representing the outermost, or valence states, are responsible for bonding. Considering first the case of only two isolated atoms (i.e. molecular case), when two atoms are brought together, their outer electron wave functions (orbitals) overlap, and the valence electrons feel a strong electrostatic pull from both nuclei (typically depicted as a double‐well electrostatic potential). The atomic orbitals combine to form molecular orbitals that may bind the two atoms into a diatomic molecule. The single atomic energy level splits into two allowed states: one lower in energy, or bonding, and the other higher in energy, or antibonding. The energy difference between these two levels is proportional to the amount of overlap of the two‐ electron atomic orbitals, and the molecular orbitals (wave functions) corresponding to the bonding and antibonding energy levels are the sum and difference, respectively, of the atomic orbitals. If one generalizes to the case of N atoms brought close together to form a perfect crystal, the single valence electron now sees the periodic electrostatic potential due to all N atoms (where N is a number of order 1023). The wave function (Bloch state) is now a combination of overlapping wave functions from all the atoms and extends over the entire volume occupied by those atoms. As in the molecular case, that wave function can be a bonding state or an antibonding state. The original atomic valence levels generalize to a band of very closely spaced energy levels, half of them bonding and half of them antibonding, and the width of the energy band is approximately equal to the energy splitting between the bonding and antibonding energy levels in the diatomic molecule. This broad band forms whether the crystal is an insulator, a metal, or a semiconductor, the metal being the case where the uppermost band is not completely occupied by the available electrons. Because in a macroscopic sample the number of energy levels in the energy band is large (approximately 1023, corresponding to the number of valence electrons in the crystal) and the spacing between these energy levels is small, the electron energies may be considered to be a continuous variable. The number of electron energy levels per unit energy is then described in terms of a density of states (DOS) that varies with energy. Because each electron must have a slightly different energy (the Pauli exclusion principle), electrons fill up

Basic properties of metals ( free‐electron model)

2317

the energy levels one by one, in the order of increasing energy (in accordance with the Fermi–Dirac statistics). This concept will be detailed below. 21.3.2

Brillouin zones

A Bloch state, or the three‐dimensional extended wave function of a valence electron in a solid, may be represented in one dimension by the valence electron wave function appearing at every atomic site along a line of atoms, but its amplitude is modulated by the plane wave eik·r where k is the momentum of the allowed state and r is the position vector. As mentioned before, this general form for a Bloch state in a solid emerges from the requirement of translational invariance. That is, the electron wave function in a given unit cell must obey the Bloch condition uk ðr þ T n Þ ¼ uk ðrÞ;

ð21:2Þ

where Tn is a set of vectors connecting equivalent points of the repeating unit cells of the solid and uk is the one‐electron potential. The wave function must therefore be of the form Ck ðrÞ ¼ eik r uk ðrÞ;

ð21:3Þ

where a plane wave with wave vector k modulates the atomic wave function in a solid. The wave vector k, or the corresponding crystal momentum p ¼ hk, is the quantum number characterizing that Bloch state, and the allowed magnitudes and directions of k reflect the periodic structure of the lattice. Indeed, the momentum vectors k are related to the vectors of the unit cell in an inverse fashion. For example, if Tn is the vector in a unit cell in real space (e.g. along the [100] direction) which connects equivalent points, then the corresponding crystal momentum vector is 2p/Tn which connects equivalent points in momentum space (i.e. a reciprocal lattice vector). The most basic periodic crystal unit is not necessarily the unit cell. Often a unit cell can be further reduced to a primitive cell, or a Bravais lattice, which defines the most basic repetitive unit. One can then derive a set of real space vectors that define a Bravais lattice. The inverse of these vectors defines the most basic repetitive unit in momentum space – the Brillouin zone. Energy bands are defined within this three‐dimensional reciprocal, or momentum space having axes of kx, ky, and kz. For a simple cubic unit cell, both the primitive cell in real space and its associated Brillouin zone are likewise simple cubic. Allowed energy band states, of course, can have a continuously varying set of momentum states, with the reciprocal lattice vectors being only a special set of crystal momenta defining the Brillouin zone boundaries along various high‐symmetry directions. Within a solid, the periodic, crystalline symmetries replace the more common localized potentials of atoms and molecules. Also, the crystal momentum quantum numbers replace the usual orbital angular‐momentum components. Within this framework, the metallic,

2318

5f‐electron phenomena in the metallic state

condensed matter properties of magnetism, superconductivity, enhanced mass, spin, and charge‐density waves are quantified. 21.3.3

Complex and hybridized bands

The electronic structure gets more complicated in metals containing more than one type of valence electrons. A typical band structure for uranium metal (Wills and Eriksson, 2000) is shown in Fig. 21.4. Here the multiple overlapping bands are created when the conduction electrons in a solid originate from various s, p, d, and f valence orbitals of an atom. In general, the width of each band increases as the interatomic distance decreases and the overlap of the wave functions increases. Also, the s and p bands are always wider (span a wider energy range) than the d band, which in turn is always wider than the f band, reflecting the larger radial extent of the non‐f wave functions. The overlapping bands in Fig. 21.4 portray a case where at a given value of k (a position vector in momentum space) one has wave functions of more than one orbital symmetry (angular momentum) but having nearly the same energy. This implies that the Bloch functions with a given quantum number (wave vector) k could be represented as a linear combinations of states originating from the s, p, d, and f atomic orbitals. In other words, the Bloch states could be ‘hybridized’ states containing many angular‐momentum components, in contrast to atomic

Fig. 21.4 An electronic structure calculation for a‐U metal including energy bands and the density of states. The DFT predictions for the energy bands E(k) are plotted along several different directions in the unit cell of the reciprocal lattice. The labels on the k‐axis denote different high‐symmetry points in reciprocal space: G ¼ (000), Y ¼ (100), T ¼ (111). The narrow bands close to the Fermi level are dominated by the 5f levels. Some of the bands cross the Fermi level making a‐uranium a metal. The shaded area for the density of states curve represents the 5f orbital contribution (courtesy of Los Alamos Science).

Basic properties of metals ( free‐electron model)

2319

orbitals that contain only one angular‐momentum component. The angular‐ momentum mixture for a given band can vary from point to point in momentum space. Near k‐values where several bands are nearly degenerate one obtains a strong admixture, while for regions in k‐space where bands do not cross each other, the orbital symmetry of a band may contain only a single component. The dashed line in Fig. 21.4 is the Fermi energy (EF) and separates the occupied from unoccupied energy levels. The 5f states dominate the bonding primarily because there are three 5f electrons per atom and only one d‐electron per atom occupying the Bloch states and participating in bonding. The narrow 5f band is referred to as the dominant band. Because narrow bands correspond to small overlaps of wave functions, these 5f band electrons may be easily pushed toward localization by various effects, in which case they do not contribute to bonding. Compared with the band widths of non‐f metals, the actinide 5f bands are narrow and reflect the limited wave function overlap between f‐orbitals on adjacent sites. The narrowness of the 5f bands and the proximity to the Fermi energy make the 5f bands central to understanding the actinide metallic state. 21.3.4

Density of states

A very useful concept to consider is the concept of the density of allowed energy states per unit energy interval. Recall that the allowed states in a band are not actually continuous, but are very closely spaced. Since each band of allowed states may contain two electrons from each atom (spin up and spin down), one can see that bands that disperse rapidly with energy will have fewer allowed states per unit energy interval than slowly dispersing or ‘flat’ bands. The right frame of Fig. 21.4 shows the DOSs resulting from the multiband structure on the left panel of Fig. 21.4. Note that the 5f states outnumber all the others at the Fermi energy EF (see below for description). If an energy sub‐band is filled (two electrons of opposite spin occupy all its energy levels), there will be no electron density at EF and the solid is an insulator. If a band is only partially filled, the solid is a metal. 21.3.5

The Fermi energy and effective mass

Electrons, being spin‐½ particles, obey Fermi statistics with the occupation of states occurring in order of increasing energy. The mathematical expression for Fermi–Dirac statistics is f ¼ 1=½expfðE  EF Þ=kB Tg þ 1 :

ð21:4Þ

where kB is the Boltzmann factor. The probability, f, for occupation of states at T ¼ 0 is unity up to the Fermi energy, EF, and zero above this energy. EF is defined as the highest occupied energy state in a metal after all the electrons in a crystal (or in a box in the case of true free electrons) have been accounted for at

2320

5f‐electron phenomena in the metallic state

T ¼ 0. As the atomic levels are filled up and the band states (i.e. the valence states involved in bonding) become occupied, the energy or momentum of a band electron from a particular atom is not precisely known. One only knows that it occupies one of the near continuum of allowed energies in a band and that the lowest states in a band must be occupied first. In many elements (e.g. the alkali metals), the atom has only one electron to contribute to the uppermost or valence band. In that case, the uppermost band is unfilled (half filled for the alkali metals). More importantly, in the case of complex systems as shown in Fig. 21.4, the complexities introduced by the crystal structure and the subsequent hybridization result in an overlapping of valence bands, such that some states from a higher band actually lie below a lower one. This is clearly shown in Fig. 21.4 where the s–d bands cross the f‐bands. In this case, the upper band begins to be filled before the lower one is fully occupied, so that, when all the electrons are exhausted, neither band is filled, and empty states exist just above EF. The highest occupied energy (at T ¼ 0 K) is EF and the material is a metal because the electrons occupying the highest energy state have many empty allowed states in their vicinity into which they can scatter in order to travel throughout the crystal. By contrast, in the case of insulators where the uppermost band is fully occupied and there is an energy gap before the next band that is unoccupied, the Pauli exclusion principle prevents the occupation of states that already contain two electrons. Thus the electrons are not free to change states and move throughout the crystal unless they obtain sufficient energy to access an empty state beyond the energy gap between filled and empty states. At finite temperature T, some electrons within kBT below EF can occupy empty states within kBT above EF. This is shown in Fig. 21.5 where the Fermi– Dirac distribution function has been convoluted with a model DOS. The probability of occupation of states below EF is unity except within a few kBT of EF where some electrons can scatter into empty states within a few kBT above EF. Fig. 21.5 shows that electrons with binding energies higher than (EF – kBT ) contribute to the bonding, and only the narrow stripe just above EF is responsible for the metallic behavior. Most of the properties of a metal (excluding magnetism) are determined by the band states within a few kBT of EF. The sudden drop in occupation is referred to as the Fermi edge. One immediately begins to see that densities of states whose width is of the order of kBT will be dramatically affected by temperature. Of course, in complex systems electrons from more than one band and angular momentum are allowed to scatter into empty states. The substantive effects of the Fermi function are generally considered to occur within 2.2kBT of the Fermi level. These values represent the 90% (below EF) and 10% (above EF) occupancy values for electron states at a finite temperature T. Within the free‐electron model (i.e. free‐electron gas in a box) the energy is measured from the bottom of the free‐electron band parabola. The electron energy dispersion is

Basic properties of metals ( free‐electron model)

2321

Fig. 21.5 The solid line is the density of states for a free‐electron gas plotted as a function of one‐electron energy. At T ¼ 0, electrons occupy all the states up to the Fermi energy EF. The dashed curve shows the density of filled states at a finite temperature T. Only electrons within kBT of the Fermi level can be thermally excited from states below the Fermi energy (region B) to states above that level (region A) (courtesy of Los Alamos Science).

E ¼ ðpÞ2 =2m ; 

ð21:5Þ

where p is the momentum and m is effective mass of the electron. The uppermost filled level is at the Fermi energy and is given by EF ¼ (pF)2/2m , where pF is the momentum of this uppermost level. Here EF essentially corresponds to the bandwidth of the occupied states. If one then takes a repetitive box (i.e. a crystal lattice) one fulfills the requirement of periodicity, so that a free‐electron parabola exists in each box – or Brillouin zone. The parabola from each Brillouin zone may extend through many other adjacent zones so that the resulting band (reduced or folded back into the first zone by virtue of periodicity) can be very complex. Nonetheless, in the case of alkali metals and other simple metals the bandwidth definition of the Fermi energy is still often used. The crystal momentum is zero at the center of the reciprocal lattice where k ¼ 0. In a complex band system such as shown in Fig. 21.4, this definition loses some of its meaning. Nonetheless, if one adheres to this definition, one may define the Fermi temperature, TF ¼ EF/kB, as well as the Fermi velocity, vF ¼ [2EF/m ]1/2. The use of m* rather than mo is appropriate in the formula because even the periodic crystal potential has some effect on the effective mass. Indeed many of

2322

5f‐electron phenomena in the metallic state

the properties of the free‐electron model can be transferred to real material systems by substituting m for mo. The effective mass is essentially a measure of the interactions (correlations) that slow down (sometimes even speed up) the electron motion. Because of electron–electron interactions vF can be smaller for a given p, sometimes much smaller, than predicted by free‐electron theory. It is as if the electron were much heavier than a free electron. Formally, m ¼
h=ðd2 EðkÞ=dk2 Þ;

ð21:6Þ

where E(k) is a band that crosses the Fermi level and the derivative is evaluated at the Fermi level. It is easy to see that a very slowly dispersing or nearly flat band (this is obviously no longer a free‐electron parabola) will have a much larger m than a rapidly varying band such as is found for s‐ and p‐electrons where the wave function overlap is large. Correlations can be viewed as effectively resulting in a flattening of the bands at the Fermi edge. 21.3.6

Fermi surface

If one draws the energy band states in three dimensions defined by the crystal momentum
hk (in Fig. 21.4 they are shown in one dimension along a major symmetry axis) and connects all the points where each band crosses EF, then these points trace out a surface in momentum space (or k‐space) known as the Fermi surface. In the free‐electron model, each state on the Fermi surface corresponds to an electron having a constant absolute value of Fermi momentum jpFj with kinetic energy given by the free particle formula above. In the case of a free‐electron parabolic band, the Fermi surface is essentially a sphere, provided that the Fermi momentum pF exists within the first Brillouin zone. If it extends into the next zone, one may still simply reconstruct the Fermi surface from a lattice of overlapping spheres. Again, in complex systems where several bands of differing angular momentum and bandwidth cross the Fermi energy, the topology of the Fermi surface can become extremely complex, one cannot use the simple bandwith definition of the Fermi energy, and pF must be defined for each band. The topology of the Fermi surface can be experimentally determined by means of de Haas–van Alphen (dHvA) oscillations. While a complete description of this effect is far beyond the scope of this chapter, qualitatively this is a measurement of the oscillatory diamagnetic susceptibility. For metal single crystals at low temperatures in the presence of a changing magnetic field, B, the diamagnetic susceptibility is influenced by B because the presence of B imposes an additional quantum condition on the free‐electron orbits. The energy states of the electrons in the allowed orbits are called Landau levels, and these change with changing B. Without going into detail, the changing Landau levels (as B is varied) induce oscillations in the susceptibility, the frequency of

Basic properties of metals ( free‐electron model)

2323

which (proportional to 1/B) is directly related to the cross‐sectional area of the Fermi surface in momentum space. By measuring the oscillations for differing directions of B, one can reconstruct the topology of the Fermi surface. Furthermore, by measuring the amplitude of the oscillations as a function of temperature, it is possible to determine the m of the orbiting electrons. 21.3.7

Electronic heat capacity

For a gas of free particles heated from absolute zero to a temperature T, classical statistical mechanics would predict that, on the average, the kinetic energy of each particle would increase by an amount kBT. But because of the Pauli exclusion principle, the electrons obey Fermi–Dirac statistics and only those conduction electrons occupying states within kBT of the Fermi level EF can be heated (by phonon scattering) because only they can access states not occupied by other electrons (see Fig. 21.5). The number of electrons that participate in properties such as electrical conduction and electronic heat capacity decreases to a fraction T/TF of the total number of conduction electrons in the metal. At room temperature, T/TF is about 1/200 in most metals. Thus, replacing the classical Maxwell–Boltzmann statistics with the Fermi– Dirac quantum statistics implied by the exclusion principle has a profound impact on the electronic properties of metals. The factor T/TF shows up explicitly in the low‐temperature specific heat of a metal. In general, the specific heat is the sum of a lattice‐vibration term (proportional to T 3) and an electronic term gT, which is due to the thermal excitation of the electrons. The classical coefficient of the electronic term is g ¼ NkB (where N is the number of conduction electrons) but because of the exclusion principle, it becomes g ¼ 2NkB T=TF ;

ð21:7Þ

and only electrons near the Fermi energy can be excited. Thus, in simple metals obeying the free‐electron model, g is inversely proportional to TF, or equivalently, EF, and therefore proportional to m (see above), or to the density of electronic states at the Fermi level, N(EF). The prefactor 2 represents two possible spin directions. A common unit of g is (mJ mol1 K2) and the value is about 1 for a typical free‐electron metal like Cu. In strongly correlated actinide materials, values as large as 1000 have been observed. Here electrons behave more like strongly interacting particles of a liquid, e.g. more like a Fermi liquid. Because of interactions, m increases and shows an increase in the value of g over that predicted by the free‐electron model. Thus, low‐temperature specific heat measurements reveal the strength of the electron–electron correlations in a metal and therefore provide a major tool for identifying unusual metals.

2324

5f‐electron phenomena in the metallic state 21.3.8

Electrical resistivity

For free electrons the resistivity r is given by equation (21.1). In a perfect crystal, electrical resistance would be zero near the classical T ¼ 0 limit because the non‐interacting conduction electrons, acting as waves, would move through the perfect lattice unimpeded. Above T ¼ 0, the thermal excitations of lattice vibrations (phonons) affect the lattice periodicity and thus scatter the Bloch waves which depend on periodicity. Near T ¼ 0, in the absence of strong electron–electron (e–e) interactions and impurities, r(T ) increases as T 5, while at higher temperatures r(T ) ¼ AT, where A is a constant. In general, anything that destroys the perfect translational invariance of the crystal lattice will scatter electrons. This is reflected in the mean free path of electrons, l, the distance traveled by electrons between scattering events (see equation (21.1)). Foreign atoms, lattice vacancies, more complicated defects such as stacking faults, and finally, magnetic moments in an array without the full symmetry of the lattice can scatter electrons since they destroy the periodicity. Many of these imperfections are temperature‐independent and lead to a finite limiting resistance as T ¼ 0 is approached, called the residual resistance or r0. Hence, this limit is used as a measure of the quality of metal samples, for which the lowest r0 signifies the most perfect sample. It has been shown that correlated electron materials (and actinide metals in particular, see Fig. 21.1) often have anomalously high r(T ) and r0 despite very small or zero magnetic moments at low temperatures. For systems with a high N(EF), strong electron–electron scattering gives rise to a term aT 2, where the prefactor a reflects the e–e correlations so that a/g2 is approximately constant for various materials.

21.3.9

One‐electron band model

It has been shown that even a free‐electron model for a periodic system yields a relatively complex band structure. The periodic potential actually introduces gaps at the Brillouin zone boundaries, and, depending on pF relative to the zone boundaries, the Fermi surface can be very complicated. To obtain the band structure in materials with several valence electrons having more than one type of angular momentum requires substantial calculations. However, the problem of dealing with 1023 electrons can be reduced to a one‐electron problem by assuming that an electron sees only an averaged potential between the ions and the remaining electrons, and that this periodic electrostatic potential can be modeled in a self‐consistent fashion. Slater first proposed calculating the electronic states, the energy bands in Fig. 21.4, of solids by the same self‐consistent method that had been applied so successfully to describe the electronic states of atoms and molecules (Slater, 1937). In this method, one treats electrons as independent particles and calculates the average Coulomb forces on a single electron. The equation for the one‐electron states is essentially the time‐independent Schro¨dinger equation,

Basic properties of metals ( free‐electron model) ðT þ Veff Þci ðrÞ ¼ Ei ci ðrÞ

2325 ð21:8Þ

where T is a kinetic energy operator (e.g. –
h ▽ /2m in a non‐relativistic approximation and ▽ is the derivative with respect to position, Veff is the average effective potential, and Ei are the eigenstates. The other electrons and all the ions in the solid are the source of these Coulomb forces on one electron and give rise to the Veff. This calculation, repeated for all the electrons in the unit cell, leads to a charge distribution  nðrÞ ¼ Sjci ðrÞ2 ð21:9Þ 2

2

from which a new electrostatic potential seen by the electrons can be obtained as a solution of the Poisson equation. Using the new electrostatic potential, one then repeats the calculations for each electron until the charge density (distribution of electrons) and the crystal potential (forces on the electrons) have converged to self‐consistent values. Slater’s approach led to all the modern electronic band structure calculations commonly labeled one‐electron methods. These one‐electron band‐structure methods are adaptations of the familiar Hartree–Fock methods that work so well for atoms and molecules. They were put on a more rigorous footing through Kohn’s development of DFT. Unlike the genuine Hartree–Fock method, the non‐local part of electron–electron interaction is treated less formally, but it includes the long‐range screening, unimportant for simple molecules but prominent in the electron gas. Once a metal is formed, its conduction electrons (approximately 1023 per cubic centimeter) can act collectively, in a correlated manner, giving rise to what is called quasiparticle behavior (not determined by averaged electrostatic forces) and to collective phenomena such as superconductivity and magnetism. These phenomena are outside the scope of the independent electron model, which cannot accommodate all the electron–electron interactions found in the actinide series. Many‐body interactions do not readily lend themselves to reduction to an average potential. Nevertheless, great strides have been made toward including correlations into the one‐electron picture. In particular, DFT described below can incorporate the concept of exchange as well as Coulomb correlation. These electron correlations are described in the next section. 21.3.10

Electron–electron correlations

Electrons in a crystal are simultaneously attracted to the ions and repelled from each other via Coulomb repulsion. To minimize the total energy of the system, the electrons must minimize the electron–electron repulsion while maximizing the electron–ion attraction, and the way to minimize the Coulomb repulsion is for them to stay as far from each other as possible. In calculations on the helium atom it was found that: first, the two He electrons are indistinguishable – that is, electron 1 can be in orbital A or B, and so can electron 2; second, the electrons have to obey the Pauli exclusion principle, which means

2326

5f‐electron phenomena in the metallic state

that the total wave function for the two electrons has to be antisymmetric, and that antisymmetry implies that the Hamiltonian must contain an exchange term. This exchange term determines the probability that two electrons of the same spin can exist near each other. It is what separates the Hartree–Fock calculations of many‐electron atoms from the original Hartree calculations of those atoms. When the exchange term was included in the calculation of an electron gas, it was found that around each electron, there is a ‘hole’, or depression in the probability of finding another electron close by. Indeed, this probability was found to be one‐half the value it would have without the exchange term. This exchange hole demonstrates that the electron motion of the two electrons is correlated with each other, in the sense that electrons with the same spin cannot get close to each other. In the 1930’s, Wigner performed similar calculations for electrons of opposite spins, which led to a ‘correlation’ hole (very similar to the exchange hole) for the probability of finding an electron of opposite spin near a given electron (Wigner, 1934). The picture of an exchange hole and a correlation hole around each electron is a great visual image of electron correlations in solids. Modern one‐electron calculations include these correlations in an average way because these terms can be calculated from the average electron density around a given electron. The cost in energy of putting two electrons on the same site is referred to as the Coulomb correlation energy. Several theories will be considered in this chapter that include interactions beyond the one‐electron method, these approaches are termed correlated‐ electron theory. Likewise, any solid (metal, insulator, and so on) that exhibits behavior not explained by either the free‐electron model or the one‐electron band model is considered a correlated‐electron system. If the properties of a solid deviate strongly from the predictions of free‐electron or band models (e.g. heavy fermions), that solid is called a strongly correlated system. While many actinide metals and compounds fall within this group, still many others can be described as weakly correlated systems that are quite tractable within the one‐electron approach. 21.3.11

Density functional theory

This section concludes with a brief description of DFT, a one‐electron band structure approach which includes both exchange and correlation, and which has been very successful in describing weakly correlated systems. Two common variants are used: the local density approximation (LDA), which expresses the exchange and correlation potential, Exc(n(r)), as a function of local electron density, while the generalized gradient approximation (GGA) includes, in addition to these terms, the gradient of n(r) as well. Formally, as in the Slater approach, the starting point for DFT calculations is the time‐independent Schro¨dinger equation (similar to equation (21.8) above).

Basic properties of metals ( free‐electron model)

2327

One would, in principle, calculate the ground‐state (lowest‐energy configuration) total electronic energy from Hcðr1 ; r2 ; . . . rn Þ ¼ Ecðr1 ; r2 ; . . . rn Þ ;

ð21:10Þ

where H is the Hamiltonian containing the kinetic energy and all the interactions of the system (i.e. electron–electron correlation and exchange and electron–nuclei interactions) and r1,r2,. . . rn are the n position vectors. However, in the most generalized form c(r1,r2,. . . rn) is now a many‐electron wave function of the n‐electron system, and E is the total electron energy of the entire system in the ground state. The input parameters in equation (21.10) are the atomic numbers of the atoms and the geometry of the crystal (the lattice constant, the crystal structure, and the atomic positions). From the solution of this equation, one should, in principle, be able to calculate the equilibrium crystal structure, the cohesive energy, as well as the band structure. Unfortunately, there is no practical way to solve equation (21.10) for a solid. To get around this problem, Hohenberg and Kohn (1964), Kohn and Sham (1965), and Dreitzler and Gross (1990) pointed out that the total energy of a solid (or atom) may be expressed uniquely as a functional of the electron density (equation (21.9) (i.e. E ¼ E[n(r)] just as Exc above). This function can be minimized in order to determine the ground‐state energy. Therefore, instead of working with a many‐electron wave function, c(r1,r2,. . . rn), one can express the ground‐state energy in terms of the electron density at a single point (as in equation (21.9)), where that density is due to all the electrons in the solid. In addition, Hohenberg and Kohn (1964), Kohn and Sham (1965), and Dreitzler and Gross (1990) demonstrated that, instead of calculating the electron density from the many‐electron wave function, one may work with the solutions to an effective one‐electron problem (equation (21.8)). The method uses the form of the total‐energy functional to identify an effective potential Veff (r) as described above for one‐electron states, and then to solve for the one‐ electron states to produce a density equal to the many‐electron density. To account for the relativistic effects in actinides, it is necessary to replace the non‐relativistic Schro¨dinger‐like one‐electron equation (equation (21.8)) by the relativistic Dirac equation. By finding the correct form for the effective potential, the electron density in equation (21.9) will be the same as that required by DFT. The one‐electron problem defined by equation (21.8) has the same form as the equations solved by band theorists before DFT was invented, and the eigenvalues of those equations as a function of crystal momentum are precisely the energy bands. The contribution of DFT is to provide a rigorous prescription for determining the new effective potential and for calculating the total ground‐state energy, E[n(r)]. The total energy functional within DFT is given by E½nðrÞ ¼ T½nðrÞ þ EH ½nðrÞ þ Exc ½nðrÞ þ EeN ½nðrÞ þ ENN;

ð21:11Þ

2328

5f‐electron phenomena in the metallic state

where T is the effective kinetic energy of the one‐electron states obtained from equation (21.9), EH is the usual classical Hartree interaction between an electron and a charge cloud, EeN is the interaction between an electron and nuclei, and ENN is the inter‐nuclear Coulomb interaction. The important term is Exc, which is the one part of equation (21.11) that goes beyond the classical Hartree term obtained from the expression ð ð21:12Þ Exc ½nðrÞ ¼ nðrÞexc ðnðrÞÞdr: This term represents the difference between the true energy of the eigenstates and the one‐electron eigenstates. The operator of exchange-correlation exc[n(r)] represents the sum of the exchange term ex(r) plus the correlation term ec(r). The new (and presumably more correct) effective potential can now be obtained from the relationship Veff ðrÞ ¼ d=dnðrÞ½EH ðnðrÞÞ þ Exc ðnðrÞÞ þ EeN ðnðrÞÞ :

ð21:13Þ

With this new potential, the problem again reduces to a one‐electron problem by substituting this potential into equation (21.8). From these definitions, it is clear that the effective potential in which the electron moves has contributions from the electron’s interaction with the nuclei and the other electrons in the solid both by the classical Hartree term and by the quantum mechanical exchange and correlation terms. Because all electron–electron interactions that go beyond the classical Hartree term are found in Exc[n(r)], it is crucial to have a good approximation for this term. Unfortunately, there is no exact form of this term for a real solid. However, if one assumes the functional to be local, a numerical form may be obtained from many‐body calculations (quantum Monte Carlo or perturbation series expansion), and very good values may be obtained for the ground‐state energy for different values of the electron density. If the electron density of a real system varies smoothly in space, one expects that a form of Exc taken from a uniform electron gas should be applicable to the real system as well. This approximation is none other than the LDA. The good agreement, for many solids, on cohesive energy, equilibrium volume, and structural properties between this approximate theoretical approach and experimental values suggests that the LDA form of Exc works even if the electron density varies rapidly in space. Thus, the total ground‐state energy can be obtained by solving an effective one‐electron equation. This tremendous simplification of replacing interacting electrons with effective one‐electron states will work only if one can find the correct, effective one‐electron potential. Good approximations can be obtained for ex(r) and ec(r) as determined by comparisons between the thus calculated band structures and experimental band structures measured by optical properties and photoelectron spectroscopy (PES).

General observations of 5f bands in actinides 21.4

2329

GENERAL OBSERVATIONS OF 5f BANDS IN ACTINIDES

21.4.1

Narrow 5f bands

It is correct to say that the short radial extent of the 5f wave function yields only a small overlap between electrons from neighboring atoms and that this in turn results in very narrow 5f bands. Nevertheless, if the atomic spacing were sufficiently small, the overlap would be significant, as it is for 5f metals up to a‐Pu. Why then does one not get a continuation of the actinide contraction (see Fig. 21.2) if the 5f electrons are involved in bonding? Boring and Smith (2000) in their review argue that it is the presence of non‐f bands at EF (i.e. the 6p, 7s and to some extent the 6d bands), which contributes a repulsive force to the interatomic bonding forces (i.e. the s, p, d electrons with their larger radial extent, begin to repel each other at much larger distances). This is shown in Fig. 21.6 where the atomic‐sphere approximation is used to calculate the contributions to bonding from individual bands for Pu (for

Fig. 21.6 The force per atom as a function of interatomic spacing. DFT predictions for the bonding curves of d‐Pu in the fcc structure are plotted vs the interatomic spacing x ¼ ln(a/a0). Included are the curve for the total cohesive energy per atom, and the individual contributions from the s, p, d, and f states. The f band is narrow at this larger volume (courtesy of Los Alamos Science).

2330

5f‐electron phenomena in the metallic state

simplicity, in the fcc phase) as a function of interatomic spacing. For any single band, the calculated equilibrium spacing is that at which the interatomic forces on the atom are zero – i.e. where the calculated curve crosses the horizontal zero line. From Fig. 21.6, one can see that if plutonium had only an f‐band contribution, its equilibrium lattice constant would be smaller than that found. The f‐band would be wider, and Pu would stabilize in a high‐symmetry crystal structure. In reality, the contribution from the s–p band (a repulsive term at true equilibrium) helps to stabilize plutonium at a larger volume; the f‐band is narrow at that larger volume, and the narrowness leads to the low‐symmetry crystal structure. This argument is universal for multiband metals. In the transition metals, the s–p band is repulsive at equilibrium and leads to slightly larger volumes than would be the case if these metals had only d bands. For metals above Pu the repulsive force of the s–p bands is sufficient to prevent additional lattice contraction. The additional f‐electron is no longer involved in bonding and it becomes energetically favorable for the entire f‐subshell to localize. Another factor to the total energy balance is the correlation energy of electrons localized in atomic 5f states. The system gains the 5f bonding energy by the 5f delocalization, but as the electrons in atomic states can be better correlated than in band states, part of the correlation energy is lost. In actinide compounds the whole range of narrow band behavior is observed, from transition‐metal‐like to localized. The existence of non‐actinide atoms in compounds immediately yields a larger An–An separation so that a greater tendency toward localization is expected even in uranium compounds. This is in fact the case. 21.4.2

Low‐symmetry structures from 5f bands

Fig. 21.3 shows a large number of low‐symmetry crystal structures among the actinide metals. Actinide compounds, especially the more strongly correlated materials, show the same tendencies. It has long been assumed (at least for the pure metals) that it is the directional nature of the 5f bonds which leads to the low‐symmetry structures. In recent years, the charge density for several actinides using the full‐potential DFT method has been calculated. For elemental actinides up to Pu, no dominant directional 5f bonds have been found and, most importantly, no charge buildup between atoms (So¨derlind et al., 1995). What, then, is the driving force for the numerous transitions and low‐symmetry allotropic phases? A general reason can be seen in the narrow 5f bands themselves. There exists a high density of 5f states at or near EF so that a lowering of the electronic energy can occur through a Peierls‐like distortion (Merrifield, 1966). The original Peierls distortion model was demonstrated in a one‐ dimensional lattice. It was shown that a row of perfectly spaced atoms can lower the total energy by forming pairs (or dimers). The lower symmetry causes the otherwise degenerate electronic energy levels to split, some becoming lower

General observations of 5f bands in actinides

2331

Table 21.2 Typical energies of the various interactions characterizing the localized picture of magnetism for ions with 3d, 5f or 4f unfilled shells. Interaction

3d (meV)

5f (meV)

4f (meV)

coulomb (U) spin–orbit (DS–O) crystal field (CF) exchange bandwidth (W)

1000–10000 10–100 1000 100 4000–10 000

1000–10000 300 100 10 700–5000

1000–10000 100 10 1 Np > Pu > Am. Whereas uranyl salts are highly common, formation of AmO2þ 2 requires the use of strong oxidizing agents such as peroxodisulfate. The An¼O bond length in hexavalent actinyl compounds generally ranges between ˚ . In all cases, the bond is very strong, while in uranyl, it appears 1.7 and 2.0 A that the bond order may be even greater than two as evidenced by the short bond length (Greenwood and Earnshaw, 2001). The linearity of the uranyl and other hexavalent actinyl ions (Np, Pu, Am) has been the subject of many theoretical inquiries that sought to elucidate the relative contributions of orbitals from the actinide and oxygen atoms. Wadt (1981) noted that the difference in the gas‐phase geometries of isoelectronic UO2þ 2 and ThO2 is due to the relative ordering of the 5f and 6d levels. In uranium, the 5f orbitals are lower in energy, thus favoring a linear geometry upon interaction with oxygen 2p orbitals. In thorium, however, the 6d orbitals are lower, resulting in a bent geometry. Furthermore, Tatsumi and Hoffmann (1980) and Pyykko¨ et al. (1989) have added that 6p interactions with oxygen are significant in uranium; this repulsive interaction activates the 5f orbitals of uranium in a coorperative manner through a ‘pushing from below’ mechanism, leading to short, linear oxo bonds. A review of the electronic structure of several actinide‐containing molecules is available from Pepper and Bursten (1991). It is estimated that 98% of all crystal structures have O¼U¼O angles in the range 174–180 (Sarsfield et al., 2004). Despite the prevalence of the linear dioxo cation, nonlinear uranyl species have been observed. For example, the structure of UO2[(SiMe3N)CPh(NSiMe3)]2THF contains a uranyl unit with a O¼U¼O angle of 169.7(2) (Sarsfield and Helliwell, 2004). While this bend is a dramatic example of nonlinearity, more common deviations are observed in the structures of UO2(O‐2,6‐iPr2C6H3)2(pyr)2 (Barnhart et al., 1995a) and [UO2(OCH (iPr)2)2]4 (Wilkerson et al., 2000); the O¼U¼O angles in these examples are 173.4(2) and 172.6(2) , respectively.

Metals and inorganic compounds

2401

Accurate determination of the uranium–oxygen bond length of uranyl in its compounds by X‐ray diffraction have traditionally been difficult due to the large difference in scattering power (proportional to the number of electrons) between the two atoms. However, advances in neutron diffraction techniques and their wider availability have eliminated this problem. The nuclear cross sections of uranium and oxygen are comparable, thus allowing accurate atomic placement using neutrons. In general for hexavalent actinyl ions, several factors have been identified that can lead to variations in the U¼O bond length. The most significant is the bonding of ligands in the equatorial plane, perpendicular to the O¼An¼O axis. Actinyls readily form complexes with halides, such as F– and Cl–, oxygen  3 donors such as OH ; SO2 4 ; NO3 ; PO4 , and carboxylates, as well as neutral donors, such as H2O or pyridine. Coordination numbers between four and six from monodentate and bidentate ligands are common in the equatorial plane and generate octahedral, pentagonal bipyramidal, and hexagonal bipyramidal geometries. In uranyl, the formal charge on uranium is 2þ, although other evidence suggests that it may be closer to 3þ (the formal charge is different from oxidation state); thus, depending on the extent of orbital overlap from equatorial ligands, the electron density withdrawn from the axial oxygen atoms greatly affects the M¼O bond lengths (Sarsfield and Helliwell, 2004). Another factor is the local environment provided by the rest of structure, sometimes resulting in U¼O bond lengths that vary within the same compound. For example, in the compound UO{OB(C6F5)3}[(SiMe3N)CPh(NSiMe3)], the interaction of one oxo ligand (Lewis base) with the borane (Lewis acid) results in an ˚ ) compared to the uncoordinated one (1.770(3) elongated U¼O bond (1.898(3) A ˚ ) (Sarsfield and Helliwell, 2004). Finally, reduction of the actinide oxidation A state from 6þ to 5þ results in a lengthening, and hence weakening, of the oxo bond. Additional information on actinyl structures and structural changes with correlations to vibrational spectra has been compiled by Hoeskstra (1982). Actinide elements in the pentavalent oxidation state form a less common type of actinyl represented by the formula AnOþ 2 . This species is known for U, Np, þ Pu, and Am. Like AnO2þ , the AnO ion is linear and symmetric, although the 2 2 low charge on AnOþ prevents the formation of very stable complexes. These 2 compounds are very susceptible to disproportionation into An(IV) and An(VI). The most notable pentavalent actinyl is NpOþ 2 ; it has recently been observed to form an inclusion complex with the porphyrin, hexaphyrin(1.0.1.0.0.0). Here, the environment around the linear cation results in two different Np¼O bond ˚ . These distances are unusually short for lengths: 1.762(1) and 1.826(1) A ˚ is common in simple inorganic salts (Sessler the neptunyl ion where 1.85 A et al., 2001b). Differences in the An¼O bond length are also significantly influenced by the oxidation state of the metal; changing from a hexavalent to a pentavalent ˚ (Burns and Musikas, actinyl results in a bond length increase of about 0.14 A 1977). This change in the bond length implies a weakening of the bond and is

Actinide structural chemistry

2402

attributed to the additional non‐bonding electrons in each AnOþ 2 ion compared þ 2þ to the corresponding AnO2þ 2 ion. Both AnO2 and AnO2 exhibit the actinide contraction where incremental increases in the atomic number result in a ˚ (Zachariasen, 1954; Musikas lengthening of the An¼O bond by about 0.01 A and Burns, 1976). Self-assembled uranyl peroxide nanosphere clusters of 24, 28, and 32 polyhedra (some containing neptunyl) that crystallize from alkaline solution have been characterized (Burns et al., 2005). 22.3.4 (a)

Hydrides, borohydrides, borides, carbides, and silicides

Hydrides

A majority of the actinide hydrides attain either the AnH2  x or AnH3 composition through direct reaction of the metal in a H2 atmosphere. Structural information is available for hydrides of thorium through californium. The resulting actinide hydrides react readily with oxygen and all are pyrophoric. (i)

Thorium

Thorium dihydride was originally studied by Rundle et al. (1952) using neutron diffraction and was indexed as a body‐centered tetragonal (bct) lattice; it is also isomorphous with ZnH2. However, several weak maxima were observed in the X‐ray diffraction pattern that were presumably due to unidentified impurities. An X‐ray diffraction study by Korst (1962) examined sub‐stoichiometric samples of thorium hydride in the overall composition range ThH1.93 to ThH1.73. Samples richest in hydrogen (ThH1.93 and ThH1.88) gave diffraction patterns corresponding to the bct lattice of Rundle et al., while the other samples (ThH1.84, ThH1.79, and ThH1.73) contained bct lines as well as face‐centered cubic lines in their diffraction patterns. As a result, Korst reindexed all samples as face‐centered tetragonal, for which the preferred setting is body‐centered tetragonal. The higher thorium hydride, Th4H15, was studied by X‐ray diffraction and assigned a bcc lattice based on a H/Th ratio of 3.62 (representing the lower limit due to impurities) (Zachariasen, 1953). The structure of Th4H15 was also confirmed by Korst (1962) with a H/Th ratio as high as 3.73. (ii)

Protactinium

X‐ray diffraction studies of the complicated Pa–H system revealed the existence of four protactinium hydride phases during the hydriding process as a function of temperature and pressure. Phase I is present in mixtures with Phase II (>500 K) or Phase IV ( Cl > Br > I due to increasing size of the anion. In addition, coordination number for a given ligand (i.e., F) typically increases as the oxidation state of the metal decreases due to size effects as in UF6 (CN ¼ 6) and UF3 (CN ¼ 11). This variability in size results in a large number of potential polyhedral types, significantly more diverse than those observed in transition metal halides. Further comprehensive structural reviews on actinide and lanthanide halides (Brown, 1968) as well as actinide fluorides (Penneman et al., 1973) are available elsewhere. Important structural types and tables of known structures will be described herein. In addition to size effects based on ligand type and metal oxidation state, clear trends are often also observed due to the actinide contraction. As one moves from left to right across the actinide series, the cation becomes smaller, resulting in an increasing occurrence of actinide halide polyhedra of lower coordination number. When polymorphism is observed for a given element, the high‐temperature polymorph is typically the one of lower coordination number due to the generation of a more open lattice structure. Polymorphism is more common in the lower oxidation states due to larger size of the cation and enhanced ionic bonding (Taylor, 1976). Dihalides are known for only a few of the actinides due to the instability of the An2þ oxidation state. Thorium diiodide was first prepared by the reaction of ThI4 with Th metal at elevated temperatures and characterized in an X‐ray powder pattern by Clark and Corbett (1963). A subsequent single‐crystal X‐ray diffraction study by Guggenberger and Jacobson (1968) confirmed the prediction by Clark and Corbett that the compound is not a true Th(II) salt, but rather contains Th(IV) with two supernumerary electrons. Thus, ThI2 should be formulated as Th4þ(I–)2(e–)2. The structure contains four two‐ dimensionally infinite layers that alternate between trigonal prismatic and trigonal antiprismatic layers. Americium dichloride, dibromide, and diiodide, each of which was prepared by reacting americium metal with the appropriate mercuric halide, have also been indexed using X‐ray diffraction. The chloride and bromide belong to orthorhombic and tetragonal crystal systems, respectively (Baybarz, 1973b). The diiodide, AmI2, has a monoclinic structure (Baybarz et al., 1972b). Some

2416

Actinide structural chemistry

dihalides of californium(II) have also been characterized; CfBr2 (Peterson and Baybarz, 1972) and CfI2 (Hulet et al., 1976) are tetragonal and hexagonal, respectively. The actinide trihalides are the most structurally complete series of all the actinide halides and they form a series of compounds showing strong similarities to the lanthanide trihalides. The trifluorides (through curium) exhibit a nine‐ coordinate LaF3‐type structure; however, berkelium trifluoride is dimorphic with its low‐temperature modification being the eight‐coordinate YF3‐type (Brown, 1973). The same type of change occurs in californium trifluoride above 600 C (Stevenson and Peterson, 1973). An analogous structural change occurs in the lanthanide trifluorides between promethium and samarium (Thoma and Brunton, 1966). These structural observations have been related to the actinide contraction in a paper by Brown et al. (1968a). The actinide trichlorides follow a similar trend. At californium, there is a structural change as a consequence of the actinide contraction. The earlier actinides possess the nine‐coordinate UCl3 structure type. Californium trichloride is dimorphic and exhibits both a nine‐coordinate UCl3 modification, and an eight‐coordinate PuBr3‐type modification. The structural change observed in the trichlorides occurs earlier in the tribromides; Ac through a‐NpBr3 are nine‐ coordinate UCl3 types, while b‐NpBr3 through BkBr3 are eight‐coordinate PuBr3 types. The triiodides are quite different altogether. The triiodides from protactinium through americium (a‐modification) are PuBr3‐type structures, while the compounds from americium (b‐modification) through californium are six‐coordinate BiI3‐type structures (Brown, 1973). The trichlorides, tribromides, and triiodides are also moisture-sensitive materials and easily form hydrated compounds. The trihalides of the actinides are listed in Table 22.10. The actinide tetrafluorides (Th–Cf) have been the most extensively characterized class of tetrahalides due to their isostructural nature (all are monoclinic); each eight‐coordinate actinide is surrounded by a square antiprism of fluorine ligands (Keenan and Asprey, 1969). Structural details of the remaining tetrahalides are far less available (Table 22.11). The tetrachlorides (Th through Np) are also isostructural and have tetragonal crystal lattices. In ThCl4, thorium is eight‐coordinate and the ligands are arranged in a dodecahedron around the actinide. Both b‐ThBr4 and PaBr4 are isostructural with the tetrachlorides. Few structural details are available for a‐ThBr4, UBr4, and NpBr4 other than them being orthorhombic, monoclinic, and monoclinic, respectively. Of the tetraiodides, structural data are only available for ThI4 and UI4. The former has an eight‐coordinate distorted square antiprismatic geometry, while the latter is six‐coordinate octahedral (Brown, 1973). The pentahalides are quite uncommon; the only actinide for which all four pentahalides are known is protactinium, and none are known past neptunium (only NpF5 is known). These compounds are extremely moisture sensitive and the hydrolysis of some is further complicated by disproportionation. PaF5 and

hexagonal – – hexagonal hexagonal – hexagonal hexagonal – hexagonal orthorhombic trigonal – orthorhombic trigonal – – a, b

– –

f

f

–

e

e

d

–

c

a

–

a

a

– –

hexagonal – – hexagonal hexagonal – hexagonal hexagonal – hexagonal hexagonal – – hexagonal orthorhombic tetragonal hexagonal m

m

l

l

– –

k

d, j

–

d, g

g, i

–

g

g, h

– –

b, g

References hexagonal – – hexagonal hexagonal (a) orthorhombic (b) orthorhombic orthorhombic – orthorhombic monoclinic rhombohedral orthorhombic monoclinic rhombohedral monoclinic –

Symmetry

Bromide

–

o

i

i

i, n

i

i

d, i

–

d, g

g

g

g

g

– –

b, g

References

– – orthorhombic orthorhombic orthorhombic – orthorhombic orthorhombic hexagonal hexagonal hexagonal – – hexagonal – – –

Symmetry

Iodide

– – –

s

– –

n

d, r

d

g, r

g

–

g

g, q

p

– –

References

a Zachariasen (1949b); b Fried et al. (1950); c Templeton and Dauben (1953); d Asprey et al. (1965); e Peterson and Cunningham (1968a); f Stevenson and Peterson (1973); g Zachariasen (1948b); h Taylor and Wilson (1974a); i Burns et al. (1975); j Peterson and Burns (1973); k Peterson and Cunningham (1968b); l Burns et al. (1973); m Fujita et al. (1969); n Cohen et al. (1968); o Fellows et al. (1975); p Scherer et al. (1967); q Levy et al. (1975); r Haire et al. (1983); s Fried et al. (1968).

Es

Cf

Cm Bk

Pu Am

Ac Th Pa U Np

Symmetry

Symmetry

References

Chloride

Flouride

Table 22.10 Actinide trihalides (AnX3) and their crystal symmetries.

monoclinic – monoclinic monoclinic monoclinic monoclinic monoclinic monoclinic monoclinic monoclinic a, e

a, b, g

a, b, f

a, b

a, b

a, b

a, b, d, e

a, b, c

–

a, b

tetragonal – tetragonal tetragonal tetragonal – – – – – – – – – –

l

h, k

–

i, j

h

References orthorhombic (a) tetragonal (b) tetragonal monoclinic monoclinic – – – – –

Symmetry

Bromide

– – – –

p

o

i, n

m

m

References

monoclinic – – monoclinic – – – – – –

Symmetry

Iodide

– – – – – –

r

– –

q

References

g

a

Asprey and Haire (1973); b Keenan and Asprey (1969); c Stein (1964); d Kunitomi et al. (1964); e Haug and Baybarz (1975); f Asprey et al. (1957); Haug and Baybarz (1975); h Mooney (1949); i Brown and Jones (1967); j Brown et al. (1973); k Taylor and Wilson (1973a); l Spirlet et al. (1994); m Scaife (1966); n Brown and Jones (1966); o Taylor and Wilson (1974b); p Brown et al. (1970); q Zalkin et al. (1964); r Levy et al. (1980).

Pa U Np Pu Am Cm Bk Cf

Th

Symmetry

Symmetry

References

Chloride

Actinide tetrahalides (AnX4) and their crystal symmetries.

Fluoride

Table 22.11

Metals and inorganic compounds

2419

b‐UF5 are isostructural (Brown, 1973), while the powder data from NpF5 appears to be similar to that of a‐UF5 (Malm et al., 1993); each has tetragonal crystal symmetry. PaF5 and b‐UF5 are both seven‐coordinate with pentagonal bipyramidal geometry. The structure of a‐UF5, however, is six‐coordinate and octahedral. PaCl5 is also seven‐coordinate with infinite chains of edge‐fused pentagonal bipyramids (Fig. 22.6). Of the remaining pentahalides, a‐PaBr5 and UBr5 are isostructural, b‐PaBr5 and a‐UCl5 (cubic close‐packed) both form edge‐sharing dimers, b‐UCl5 dimers are based on hexagonal close‐packing of anions, and PaI5 is believed to be structurally similar to TaI5 (Brown et al. 1976; Mu¨ller, 1979). The pentahalides are listed in Table 22.12. Some intermediate compounds of the stoichiometries An2X9 and An4X17 have also been discovered, including Pa2F9, U2F9, U4F17, and Pu4F17. The former two compounds are isostructural with bcc symmetry. In the nine‐ coordinate U2F9, it is believed that its black color results from resonance between oxidation states four and five. The latter two compounds are structurally uncharacterized (Brown, 1973). Structural information for only four actinide hexahalides is available (Table 22.13). The hexafluorides of U, Np, and Pu are volatile solids obtained

Fig. 22.6 Crystal structure of PaCl5 (top) with an illustration of the infinite chains of edge‐ sharing pentagonal bipyramids (bottom) (Dodge et al., 1967).

o

h

a

tetragonal – – tetragonal (a) tetragonal (b) tetragonal f, g

d, e

b, c, d

– –

monoclinic – – monoclinic (a) triclinic (b) –

References

–

j

i

– –

h

monoclinic (a) monoclinic (b) triclinic (g) triclinic – –

Symmetry

Bromide References

– –

n

k

k, l

k

orthorhombic – – – – –

Symmetry

Iodide References – – – – –

o

Stein (1964); b Zachariasen (1948b); c Eller et al. (1979); d Zachariasen (1949g); e Ryan et al. (1976); f Malm et al. (1993); g Baluka et al. (1980); Dodge et al. (1967); i Smith et al. (1967); j Mueller and Kolitsch (1974); k Brown et al. (1969); l Brown et al. (1968b); m Brown (1979); n Levy et al. (1978); Brown et al. (1976).

Np

U

Pa

Symmetry

a

Symmetry

References

Chloride

Fluoride

Table 22.12 Actinide pentahalides (AnX5) and their crystal symmetries.

Metals and inorganic compounds

2421

Table 22.13 Actinide hexahalides (AnX6) and their crystal symmetries. Fluoride

U Np Pu a e

Chloride

Symmetry

References

Symmerty

References

orthorhombic orthorhombic orthorhombic

a, b

hexagonal – –

e, f, g

c d

– –

Levy et al. (1976); b Hoard and Stroupe (1958); c Malm et al. (1958); d Florin et al. (1956); Zachariasen (1948b); f Zachariasen (1948c); g Taylor and Wilson (1974c).

from AnF4 fluorination, and UCl6 is obtained from the reaction of AlCl3 with UF6. AmF6 has been claimed as the result of oxidation of AmF3 by KrF2 in anhydrous HF at 40–60 C, although no structural data is available (Drobyshevskii et al., 1980). All are powerful oxidizing agents and extremely sensitive to moisture; contact with water results in the formation of AnO2X2 and HX compounds. The hexafluoride of uranium is important in gaseous diffusion processes for the enrichment of uranium. The hexafluorides are isostructural compounds that form discrete octahedra, although in the case of UF6, neutron diffraction data suggests that there are significant deviations from the ideal parameters of Hoard and Stroupe due to strong U–U repulsions (Taylor et al., 1973). The hexachloride of uranium (the only other actinide hexahalide) contains a hexagonal crystal lattice with perfect octahedral geometry around uranium. It is isostructural with b‐WCl6 (Taylor, 1976). Actinide oxyhalides of the type An(VI)O2X2, An(V)O2X, An(IV)OX2, and An(III)OX are known although less thoroughly characterized than the halides themselves. In general, the higher oxidation state compounds are favored by the early actinides, while the lower oxidation states are favored by the later actinides. The trivalent actinide oxyfluorides are limited to AcOF, ThOF, PuOF, and CfOF. With the exception of PuOF, these oxyhalides have CaF2 fluorite‐ type structures with the oxygen and fluorine atoms randomly distributed in the anion sites. The PuOF lattice is a tetragonal modification of the fluorite structure, probably stabilized by excess fluoride (Brown, 1973). The remaining trivalent actinide oxychlorides, oxybromides, and oxyiodides (where structural data are available) are strictly of the tetragonal PbFCl structure type, thus making their characterization rather straightforward. In this arrangement, the metal atom has four oxygen neighbors and five halide neighbors. It is rather remarkable that compounds formed from both large and small cations ranging in size from Ac3þ to Es3þ and anions from Cl to I can all adopt this structure type. The known compounds are listed in Table 22.14. Tetravalent actinide oxyhalides are very limited in number; none are known beyond neptunium (Table 22.15). With the exception of ThOF2, all adopt the PaOCl2 structure type. This rather unusual structure consists of infinite

fcc fcc – – – tetragonal – fcc – fcc – –

d

–

c

–

a,p

– – –

b

tetragonal – – tetragonal tetragonal tetragonal tetragonal tetragonal tetragonal tetragonal tetragonal

References

k

j

i

h

g

a

f

e

– –

a

tetragonal – – tetragonal tetragonal tetragonal tetragonal tetragonal tetragonal tetragonal –

Symmetry

Bromide References

–

n

m

c

l

a

f

e

– –

a

– – – tetragonal tetragonal tetragonal tetragonal – tetragonal tetragonal –

Symmetry

Iodide

–

n

–

m

o

a

f

e

– – –

References

a Zachariasen (1949b); b Rannou and Lucas (1969); c Weigel and Kohl (1985); d Peterson and Burns (1968); e Levet and Noe¨l (1981); f Brown and Edwards (1972); g Templeton and Dauben (1953); h Peterson (1972); i Peterson and Cunningham (1967b); j Copeland and Cunningham (1969); k Fujita et al. (1969); l Weigel et al. (1979); m Cohen et al. (1968); n Fried et al. (1968); o Haire et al. (1983); p Zachariasen (1951).

Ac Th Pa U Np Pu Am Cm Bk Cf Es

Symmetry

a

Symmetry

References

Chloride

Fluoride

Table 22.14 Trivalent actinide oxyhalides (AnOX) and their crystal symmetries.

Metals and inorganic compounds

2423

polymeric chains along the c‐direction with cross‐linking in the ab plane. The protactinium environments are diverse and can be either seven‐, eight‐, or nine‐ coordinate with three‐ or four‐coordinate oxygen atoms. The LaF3 structure type of ThOF2 is orthorhombic but is largely structurally uncharacterized (Taylor, 1976). The pentavalent actinide oxyhalides can be of An(V)OX3, An(V)O2X, or An(V)2OX8 composition. In general, structural data are few, if available at all (Table 22.16). The most thoroughly characterized of these oxyhalides are the isostructural PaOBr3 and UOBr3 systems. The structure of the former compound is composed of endless double chains (with random terminations) with pentagonal bipyramidal polyhedra around the Pa atoms. Four out of every five pentagonal edges of the polyhedra are shared (Brown et al., 1975). Hexavalent actinide oxyhalides are typically of the form An(VI)O2X2 (actinyl) or An(VI)OX4. The actinyl fluorides, UO2F2, NpO2F2, PuO2F2, and AmO2F2, are isostructural and have the rhombohedral UO2F2 structure type. Here, the linear uranyl cation is surrounded equatorially by six fluorides, generating a ˚ is coordination number of 8 for uranium. The U–O bond distance of 1.74(2) A common for the uranyl cation. Neutron diffraction of UO2Cl2 reveals a linear uranyl cation surrounded equatorially by five atoms, four of which are chlorides and the fifth is an oxygen atom from a neighboring uranyl group. Uranyl bromide, UO2Br2, is also known structurally, but the last in the series, UO2I2, is as of yet unknown. Known compounds are listed in Table 22.17 (Taylor, 1976). Actinide halo‐complexes containing alkali, ammonium, or other cations will not be discussed here. The reader is referred elsewhere for comprehensive reviews of structural characterizations (Brown, 1973).

22.3.6

Carbonates, nitrates, phosphates, arsenates, and sulfates

In general, a limited number of anhydrous binary compounds of actinides and these ligands are reported in the literature. This is due to the greater stability of the hydrated compounds and higher order complexes. In most examples, the common structural feature is that the anions all provide oxygen atoms that surround the actinide cation. Coordination numbers for the metal atom in these compounds can be as high as eight to 12 for tetravalent thorium, but typically decrease across the series to between six and nine due to the actinide contraction. A coordination number of six is observed in a few uranyl structures. The high coordination numbers are predominantly due to the ability of these ligands to act in both monodentate and bidentate (symmetric and asymmetric) coordination modes. Bidentate coordination is most common because of the small ‘bite’ distance (O O distance) of the ligand.

orthorhombic – – – – – –

a

orthorhombic orthorhombic orthorhombic orthorhombic b

b, e, f

b, c, d

b

References – orthorhombic orthorhombic –

Symmetry

Bromide

–

f

c

–

References

orthorhombic orthorhombic orthorhombic –

Symmetry

Iodide

–

f

c

g

References

a D’Eye (1958); b Bagnall et al. (1968a); c Brown and Jones (1967); d Dodge et al. (1968); e Taylor and Wilson (1974d); f Levet and Noe¨l (1979); g Scaife et al. (1965).

Th Pa U Np

Symmetry

Symmetry

References

Chloride

Fluoride

Table 22.15 Tetravalent actinide oxyhalides (AnOX2) and their crystal symmetries.

h

a

monoclinic – – orthorhombic monoclinic – –

Symmetry

– –

g

f

– –

e

References PaO2I – – – – – –

Compound

Iodide

hexagonal – – – – – –

Symmetry

– – – – – –

h

References

Brown and Easey (1970); b Stein (1964); c Kemmler‐Sack (1969); d Bagnall et al. (1968b); e Brown et al. (1975); f Levet et al. (1977); g Brown (1973); Brown et al. (1967).

d

d

–

c

a

b

PaOBr3 – – UO2Br UOBr3 – –

orthorhombic bcc orthorhombic monoclinic – tetragonal rhombohedral

PaO2F Pa2OF8 Pa3O7F UO2F – NpO2F NpOF3 a

Compound

Symmetry

Compound

References

Bromide

Fluoride

Table 22.16 Pentavalent actinide oxyhalides and their crystal symmetries.

Actinide structural chemistry

2426

Table 22.17 Hexavalent actinide oxyhalides and their crystal symmetries. Fluoride

Chloride

Compound

Symmetry

References

Compound

Symmetry

References

UO2F2 UOF4 (a) UOF4 (b) NpO2F2 NpOF4 PuO2F2 PuOF4 AmO2F2

rhombohedral trigonal tetragonal rhombohedral trigonal rhombohedral trigonal rhombohedral

a, b

UO2Cl2 – – – – – – –

orthorhombic – – – – – – –

l, m

c, d e a, f g h, i j k

– – – – – – –

Zachariasen (1949b); b Atoji and McDermott (1970); c Paine et al. (1975); d Levy et al. (1977); Taylor and Wilson (1974e); f Bagnall et al. (1968b); g Peacock and Edelstein (1976); h Florin et al. (1956); i Alenchikova et al. (1958); j Burns and O’Donnell (1977); k Keenan (1968); l Debets (1968); m Taylor and Wilson (1973b). a e

(a)

Carbonates

Structures of actinide carbonates number very few in the literature and mostly contain the actinyl cation, thus restricting ligand bonding to the equatorial region. Carbonates typically bond in a bidentate fashion, but instances of monodentate bridging carbonate are also known. Actinide carbonates are sometimes geologically occurring minerals such as rutherfordine. Rutherfordine is the naturally occurring form of the mineral UO2CO3 and its structure has been investigated both as the natural mineral (Christ et al., 1955) and a synthetic compound (Cromer and Harper, 1955). The crystal structure of the natural mineral has reccently been refined (Finch et al., 1999). In both cases, UO2CO3 crystallizes as an orthorhombic lattice and there are six oxygen atoms bound in the equatorial plane. Two carbonate groups act in a symmetrical bidentate fashion, while the remaining two oxygens are from monodentate carbonate groups, resulting in hexagonal bipyramidal geometry. Other instances of uranyl carbonate compounds are listed in Table 22.18. While the hexagonal bipyramidal geometry is common in several uranyl carbonates, slight differences in the U¼O actinyl bond length are still observed; for example, 1.67(9), 1.79(1), and ˚ distances are observed in UO2CO3, (NH4)4UO2(CO3)3 (Graziani 1.80(1) A et al., 1972), and Tl4UO2(CO3)3 (Mereiter, 1986b), respectively. Simple carbonates of the transuranium actinyls ðAnO2þ 2 Þ are known for both neptunium and plutonium. NpO2CO3 (The´venin et al., 1986; Kato et al., 1998) and PuO2CO3 (Navratil and Bramlet, 1973) are both isostructural with the uranium analog and have orthorhombic lattices. The tetraammonium tricarbonate compounds of neptunyl and plutonyl, (NH4)4NpO2(CO3)3 and

Metals and inorganic compounds

2427

Table 22.18 Some actinide carbonates and their crystal symmetries. Carbonates

Symmetry

References

[C(NH2)3]6[Th(CO3)5] 4H2O Na6[Th(CO3)5] 12H2O UO2CO3 Sr2UO2(CO3)3 8H2O Na4UO2(CO3)3 K4UO2(CO3)3 Tl4UO2(CO3)3 (NH4)4UO2(CO3)3

monoclinic triclinic orthorhombic monoclinic hexagonal monoclinic monoclinic monoclinic

NpO2CO3 KNpO2CO3 Na3NpO2(CO3)2 nH2O Rb3NpO2(CO3)2 · nH2O K4NpO2(CO3)3 (NH4)4NpO2(CO3)3 [Na6Pu(CO3)5]2 Na2CO3 33H2O PuO2CO3 (K,NH4)PuO2CO3 (NH4)4PuO2(CO3)3 Am2(CO3)3 2H2O KAmO2CO3 CsAmO2CO3 RbAmO2CO3 NH4AmO2CO3 (NH4,Cs)4AmO2(CO3)3

orthorhombic hexagonal monoclinic orthorhombic monoclinic monoclinic monoclinic orthorhombic hexagonal monoclinic cubic hexagonal hexagonal hexagonal hexagonal monoclinic

Voliotis and Rimsky (1975a) Voliotis and Rimsky (1975b) Cromer and Harper (1955) Mereiter (1986a) Cı´sarˇova´ et al. (2001) Malcic (1958a) Mereiter (1986b) Graziani et al. (1972); Malcic (1958b) The´venin et al. (1986) Keenan and Kruse (1964) Volkov et al. (1981) Volkov et al. (1981) Musikas and Burns (1976) Marquart et al. (1983) Clark et al. (1998a) Navratil and Bramlet (1973) Ellinger and Zachariasen (1954) Marquart et al. (1983) Weigel and ter Meer (1967) Keenan and Kruse (1964) Keenan (1965) Ellinger and Zachariasen (1954) Nigon et al. (1954) Fedoseev and Perminov (1983)

(NH4)4PuO2(CO3)3, are also isostructural with the corresponding uranium compound and crystallize in monoclinic crystal systems. Only bidentate coordination of the carbonate ion is observed. Pentavalent actinyl ðAnOþ 2 Þ carbonate compounds containing americium have also been studied; the compounds KNpO2CO3, KPuO2CO3, and KAmO2CO3 (Ellinger and Zachariasen, 1954; Keenan and Kruse, 1964) are isostructural with hexagonal symmetry. Tetravalent thorium and plutonium carbonate compounds include Na6Th (CO3)5 · 12H2O (Voliotis and Rimsky, 1975b) and Na6[Pu(CO3)5]2 Na2CO3 · 33H2O (Clark et al., 1998a); the crystal structure of the latter is shown in Fig. 22.7. In both structures, the actinides are ten coordinate and all the carbonate groups are bidentate. The geometry of each has been described as a modified hexagonal bipyramid; two trans carbonate ligands occupy axial positions analogous to the trans oxo ligands in an actinyl ion, while the remaining carbonates occupy the equatorial sites, thus forming the hexagon. An example of a trivalent actinide carbonate can be seen in the structure of Am2(CO3)3 · 2H2O (Weigel and ter Meer, 1967).

Actinide structural chemistry

2428

Fig. 22.7 Coordination geometry of [Pu(CO3)5]6– anion (showing axial and equatorial carbonate ligands) in the crystal structure of [Na6Pu(CO3)5]2 · Na2CO3 · 33H2O (Clark et al., 1998a).

(b)

Nitrates

Structures of simple actinide nitrates containing only actinide/actinyl cations and nitrate anions are unknown. All known structures are hydrated, contain additional non‐actinide monovalent or divalent cations, or contain various donor ligands. Actinide nitrate compounds are limited mainly to Th(VI) and uranyl cations, although a few neptunium and plutonium structures exist. In the tetravalent thorium and plutonium compounds, the nitrate anions are typically bidentate, thus allowing for extraordinarily high coordination numbers ranging from eight to as high as 12. In actinyl compounds, the trans oxo ligands enforce equatorial nitrate coordination, thus causing both bidentate as well as monodentate coordination in the case of four equatorial nitrate ligands. Hexagonal bipyramidal geometry is common in this case. Examples of actinide nitrate compounds are available from the previous edition of this work or Brown (1973).

Metals and inorganic compounds

2429

Thorium(IV) nitrate pentahydrate has been investigated using both X‐ray and neutron diffraction (Taylor et al., 1966; Ueki et al., 1966). The structure as determined by neutron diffraction is shown in Fig. 22.8. Four bidentate nitrate groups and three of the five water molecules are coordinated to the metal center, resulting in a coordination number of 11. Water–water and water–nitrate hydrogen bonds are significant in terms of stabilizing the overall structure, with ˚ . The plutonium the latter being slightly longer than the former by about 0.2 A analog, Pu(CO3)4 · 5H2O, is isostructural with the thorium compound, both of which have orthorhombic symmetry (Staritzky, 1956). The dihydrate (Dalley et al., 1971), trihydrate (Hughes and Burns, 2003), and hexahydrate (Hall et al., 1965) of uranyl nitrate each exhibit eight‐coordinate uranium centers of hexagonal bipyramidal geometry. In each compound, both nitrates are bidentate and two waters are coordinated through oxygen. Once again, extensive hydrogen bonding is present between hydrogen atoms of water molecules and unbound oxygen atoms of the nitrate groups (Hall et al., 1965; Dalley et al., 1971). The U¼O bond lengths are shorter in the dihydrate ˚ ) than in the hexahydrate (1.85 and 1.87 A ˚ ), presumably (1.754(4) and 1.763(5) A due to the greater effects of hydrogen bonding in the latter.

Fig. 22.8 Coordination environment of thorium in the neutron diffraction crystal structure of Th(NO3)4 · 5H2O (Taylor et al., 1966).

2430

Actinide structural chemistry

Neptunyl nitrate hexahydrate, NpO2(NO3)2 · 6H2O, has orthorhombic symmetry and appears to be isostructural with the uranium analog. X‐ray powder data are also available for the compounds NpO2NO3 · H2O and Np (NO3)4 N2O5, but structural details are inconclusive (Laidler, 1966). The series of tetravalent thorium nitrates having the formula M(II)Th (NO3)6 · 8H2O [M(II) ¼ Mg, Mn, Co, Ni, Zn] are isomorphically related. Further studies of the Mg compound have shown that the coordination is best described by the formula [Mg(H2O)6] [Th(NO3)6] · 2H2O. All the nitrates bond in a bidentate fashion, leading to a coordination number of 12 for thorium (Sˇc´avnicˇar and Prodic´, 1965). In some cases, anhydrous nitrate compounds can be obtained such as RbUO2(NO3)3. All the nitrate groups are bidentate to the metal, thus resulting in hexagonal bipyramidal geometry around the uranium atom (Barclay et al., 1965). Also included in the anhydrous uranyl compounds are KUO2(NO3)3 (Krivovichev and Burns, 2004) and CsUO2(NO3)3 (Zivadinovic, 1967), as well as the tetranitrate Rb2[UO2(NO3)4] (Irish et al., 1985). (c)

Phosphates and arsenates

Phosphate and arsenate compounds containing the following actinides have been the subject of a series of extensive articles: uranium(VI) (Weigel and Hoffmann, 1976a), neptunium(VI) (Weigel and Hoffmann, 1976b), ammonium– americyl(VI)–phosphate (Weigel and Hoffmann, 1976c), plutonium(VI) (Fischer et al., 1981), americium(VI) (Lawaldt et al., 1982), thorium(IV), uranium(IV), and neptunium(IV) (Bamberger et al., 1984a), and plutonium(III) and plutonium(IV) (Bamberger et al., 1984b). Representative examples of actinide phosphates will be presented herein (Table 22.19). The structural chemistry of actinide phosphates and arsenates is important on a number of levels. Uranyl phosphates and arsenates in particular are found geologically in large numbers as naturally occurring minerals, which include autenite, tobernite, metazeunerite, and uranocircite. Additionally, the long‐ term stability of the rare‐earth phosphate mineral monazite has led to studies involving the immobilization of actinides in synthetic monazites for long‐term storage. Phosphate chemistry is also critically important for understanding the behavior of actinides in the environment as well as in separations schemes. Actinide phosphate compounds typically contain the orthophosphate  4 ðPO3 4 Þ, metaphosphate ðPO3 Þ, or pyrophosphate ðP2 O7 Þ anions; arsenate structures are typically limited to the former type. The tetrahedral PO3 4 ion lends itself to both monodentate and bidentate metal bonding, as illustrated in Fig. 22.9. The pyrophosphate anion contains two tetrahedral centers, each of which can be monodentate or bidentate. The various types of phosphate coordination modes in the solid state are exemplified in the structure of Th4(PO4)4P2O7. Each heavy thorium atom is bound to eight oxygen atoms 4 from five PO3 4 groups and one P2 O7 group. One of the former groups is bidentate and the remaining four are monodentate; the pyrophosphate

Table 22.19

Some actinide phosphates, by type, and their crystal symmetries.

Phosphate

Symmetry

orthophosphates (including double phosphates) AcPO4 0.5H2O hexagonal Th3(PO4)4 monoclinic U(UO2)(PO4)2 U3(PO4)4 (U2O)(PO4)2 (UO2)3(PO4)2(H2O)4 PuPO4 PuPO4 0.5H2O Pu(PO4)3 AmPO4 AmPO4 0.5 H2O CmPO4 (Li,Na,K,Rb,Cs)Th2(PO4)3 KTh2(PO4)3 NaTh2(PO4)3 Na2Th(PO4)2 (Ca,Sr,Cd,Ba,Pb)0.5Th2(PO4)3 CuTh2(PO4)3 TlTh2(PO4)3 PbTh(PO4)3 Pb3Th6(PO4)10 Pb7Th(PO4)6 (H,Li,Na)UO2PO4 4H2O H11(UO2)2(PO4)5 (Li,Na)U2(PO4)3 (Na,K,NH4)UO2PO4 3H2O (Mg,Ca,Sr,Ba)(UO2PO4)2 · nH2O (n ¼ 2–6.5, 8–12) a‐KU2(PO4)3 b‐(K,Rb)U2(PO4)3 a‐CaU(PO4)2 b‐CaU(PO4)2 Ca(UO2PO4)2 nH2O (n ¼ 0–2) Cu2UO2(PO4)2 (H,Li)NpO2PO4 4H2O a‐NaNp2(PO4)3 b‐(Na,K,Rb)Np2(PO4)3 (Na,K,NH4)NpO2PO4 3H2O Mg(NpO2PO4)2 9H2O (Ca,Sr,Ba)(NpO2PO4)2 6H2O (H,K,NH4)PuO2PO4 nH2O a‐NaPu2(PO4)3 b‐(Na,K,Rb)Pu2(PO4)3

triclinic monoclinic orthorhombic orthorhombic monoclinic hexagonal orthorhombic monoclinic hexagonal monoclinic monoclinic monoclinic monoclinic monoclinic monoclinic monoclinic monoclinic monoclinic monoclinic cubic tetragonal monoclinic monoclinic tetragonal tetragonal

(K,Rb,Cs,NH4,)AmO2PO4 nH2O NH4AmO2PO4 3H2O

tetragonal tetragonal

monoclinic rhombohedral orthorhombic monoclinic orthorhombic monoclinic tetragonal monoclinic rhombohedral tetragonal tetragonal tetragonal tetragonal monoclinic rhombohedral

References Fried et al. (1950) Shankar and Khubchandani (1957) Be´nard et al. (1994) Burdese and Borlera (1963) Albering and Jeitschko (1995) Locock and Burns (2002) Bjorklund (1957) Bjorklund (1957) Bamberger et al. (1984b) Keller and Walter (1965) Keller and Walter (1965) Weigel and Haug (1965) Matkovic´ et al. (1968a) Matkovic´ et al. (1968b) Matkovic´ and Sˇljukic´ (1965) Galesˇic´ et al. (1984) Guesdon et al. (1999) Loue¨r et al. (1995) Laugt (1973) Quarton et al. (1984) Quarton et al. (1984) Quarton et al. (1984) Weigel and Hoffmann (1976a) Staritzky and Cromer (1956) Matkovic´ et al. (1968a) Weigel and Hoffmann (1976a) Weigel and Hoffmann (1976a) Guesdon et al. (1999) Volkov et al. (2003) Dusausoy et al. (1996) La Ginestra et al. (1965) Weigel and Hoffmann (1976a) Guesdon et al. (2002) Weigel and Hoffmann (1976b) Nectoux and Tabuteau (1981) Volkov et al. (2003) Weigel and Hoffmann (1976b) Weigel and Hoffmann (1976b) Weigel and Hoffmann (1976b) Fischer et al. (1981) Burnaeva et al. (1992) Burnaeva et al. (1992); Volkov et al. (2003) Lawaldt et al. (1982) Weigel and Hoffmann (1976c)

2432

Actinide structural chemistry Table 22.19 (Contd.)

Phosphate

Symmetry

References

metaphosphates Th(PO3)4 Pa(PO3)4

orthorhombic orthorhombic

a‐U(PO3)4 b‐U(PO3)4 a‐Np(PO3)4 b‐Np(PO3)4 g‐Np(PO3)4 Pu(PO3)4

monoclinic orthorhombic tetragonal triclinic orthorhombic orthorhombic

Douglass (1962) Le Cloarec and Cazaussus (1978) Baskin (1967) Douglass (1962) Nectoux and Tabuteau (1981) Nectoux and Tabuteau (1981) Nectoux and Tabuteau (1981) Douglass (1962)

pyrophosphates a‐ThP2O7

cubic

b‐ThP2O7

orthorhombic

PaP2O7

cubic

(PaO)4(P2O7)3 a‐UP2O7 b‐UP2O7 NpP2O7 PuP2O7

monoclinic cubic orthorhombic cubic cubic

Bamberger et al. (1984a); Burdese and Borlera (1963) Bamberger et al. (1984a); Burdese and Borlera (1963) Le Cloarec and Cazaussus (1978) Le Cloarec et al. (1976) Kirchner et al. (1963) Douglass and Staritzky (1956) Keller and Walter (1965) Bjorklund (1957)

other Th4(PO4)4P2O7 KThU(PO4)3 Pa2O5 · P2O5 UXPO4 · 2H2O (X ¼ Cl, Br) U2(PO4)(P3O10) [(UO2)3(PO4)O (OH)(H2O)2](H2O) U(HPO4)2 · 4H2O

orthorhombic monoclinic orthorhombic tetragonal orthorhombic tetragonal

Be´nard et al. (1996) Guesdon et al. (1999) Le Cloarec et al. (1976) Be´nard‐Rocherulle´ et al. (1997) Podor et al. (2003) Burns et al. (2004)

N/A

Voinova (1998)

group donates two oxygen atoms, one from each tetrahedral center (Be´nard et al., 1996). Actinide pyrophosphates can adopt two different structural modifications: the orthorhombic b‐form and the cubic a‐form. Structural details of the former type are scarce, but the latter modification is known for structures including the actinides Th, Pa, U, Np, and Pu. These pyrophosphates are all isostructural and lattice parameters decrease with increasing atomic number. Six oxygen atoms are coordinated to the metal center in each instance (Le Cloarec and Cazaussus, 1978). The b‐UP2O7 modification has orthorhombic symmetry (Douglass and Staritzky, 1956). Simple metaphosphates of tetravalent Th, Pa, U, and Pu of the composition An(PO3)4 are all isostructural and have orthorhombic symmetry

Metals and inorganic compounds

2433

Fig. 22.9 The two crystallographically independent uranyl centers in the crystal structure of (UO2)3(PO4)2(H2O)4. Hydrogen atoms have been omitted from the three water molecules bound to the uranium on the right (Locock and Burns, 2002).

(Douglass, 1962; Le Cloarec and Cazaussus, 1978). Structural details for the simple arsenates of AmAsO4 and PuAsO4 (monoclinic symmetry) are available elsewhere (Keller and Walter, 1965). (d)

Sulfates

Actinide sulfates enjoy a unique place in the history of nuclear chemistry; it was A. H. Becquerel who, in 1896, discovered radioactivity in the uranyl double sulfate K2UO2(SO4)2 · 2H2O. He simply noticed that in the absence of sunlight (actually, in the total darkness of laboratory drawer), the salt will darken a photographic plate and so must spontaneously emit its own type of radiation (Becquerel, 1896). Additionally, sulfates have traditionally played an important role in the mining of uranium ores. Uranium is leached from crushed ores using sulfuric acid, resulting in soluble ionic species such as UO2 ðSO4 Þ4 3 . Despite its prevalence in actinide chemistry, structural characterizations of actinide sulfates are relatively few (Table 22.20). Actinide sulfate compounds are usually found in hydrated form where as few as one to as many as ten water molecules are present in the structural formula.

Table 22.20 Some actinide sulfates and their crystal symmetries. Sulfate

Symmetry

References

Th(SO4)2 Th(SO4)2 8H2O Th(OH)2SO4 (NH4)2Th(SO4)3 K4Th(SO4)4 2H2O H3PaO(SO4)3 U(OH)2SO4 U6O4(OH)4(SO4)6 a‐UO2SO4 b‐UO2SO4 Cs2(UO2)2(SO4)3 K2UO2(SO4)F2 2H2O (NH4)2UO2SO4 2H2O (K,Rb)4U(SO4)4 2H2O (NH4, K)2UO2(SO4)2 2H2O UO2SO4 2.5H2O UO2SO4 3H2O Na10[(UO2)(SO4)4](SO4)2 3H2O U(SO4)2 4H2O (NH4, Rb)U(SO4)2 4H2O H2(UO2)2(SO4)2 5H2O (NH4)2(UO2)2(SO4)3 5H2O CsU(SO4)2 5.5H2O a‐2UO2SO4 7H2O b‐2UO2SO4 7H2O U2(SO4)3 8H2O (Cs, Rb)2UO2(SO4)2 10H2O Cs2NpO2(SO4)2 Cs2(NpO2)2(SO4)3 (Cs, Rb)2NpO2(SO4)2 nH2O (n ¼ 0.5, 4, 10) (NpO2)2SO4 H2O (NpO2)2SO4 2H2O K2NpO2(SO4)2 2H2O Cs2Np(SO4)3 2H2O Cs3NpO2(SO4)2 2H2O (NH4)2NpO2SO4 2H2O NpO2SO4 2.5H2O Na10Np2(SO4)9 4H2O Pu(SO4)2 (NH4)2Pu(SO4)3 NaPu(SO4)2 H2O (K, Cs)2PuO2(SO4)2 2H2O (K, Rb)4Pu(SO4)4 2H2O

hexagonal monoclinic orthorhombic monoclinic triclinic hexagonal orthorhombic tetragonal monoclinic monoclinic tetragonal monoclinic monoclinic monoclinic monoclinic monoclinic orthorhombic monoclinic orthorhombic monoclinic orthorhombic orthorhombic orthorhombic orthorhombic monoclinic orthorhombic orthorhombic monoclinic tetragonal orthorhombic

Mudher et al. (1999) Habash and Smith (1983) Lundgren (1950) Mudher et al. (1999) Arutyunyan et al. (1966a) Bagnall et al. (1965) Lundgren (1952) Lundgren (1953) Kovba et al. (1965) Brandenburg and Loopstra (1978) Ross and Evans (1960) Alcock et al. (1980a) Niinisto et al. (1978) Mudher et al. (1988) Weigel and Hellmann (1986) Weigel and Hellmann (1986) Traill (1952) Burns and Hayden (2002) Kierkegaard (1956) Chadha et al. (1980) Traill (1952) Staritzky et al. (1956) Chadha et al. (1980) Zalkin et al. (1978b) Brandenburg and Loopstra (1973) Chadha et al. (1980) Weigel and Hellmann (1986) Fedosseev et al. (1999) Fedosseev et al. (1999) Weigel and Hellmann (1986)

orthorhombic monoclinic monoclinic monoclinic triclinic monoclinic monoclinic orthorhombic hexagonal monoclinic hexagonal monoclinic monoclinic

PuO2SO4 2.5H2O a‐Pu(SO4)2 4H2O b‐Pu(SO4)2 4H2O NH4Pu(SO4)2 4H2O Am2(SO4)3 8H2O

monoclinic orthorhombic orthorhombic monoclinic monoclinic

Grigor’ev et al. (1993a) Budantseva et al. (1988) Weigel and Hellmann (1986) Charushnikova et al. (2000a) Grigor’ev et al. (1991a) Fedosseev et al. (1999) Weigel and Hellmann (1986) Charushnikova et al. (2000b) Mudher et al. (1999) Mudher et al. (1999) Iyer and Natarajan (1989) Weigel and Hellmann (1986) Mudher et al. (1988); Mudher and Krishnan (2000) Weigel and Hellmann (1986) Jayadevan et al. (1982) Jayadevan et al. (1982) Iyer and Natarajan (1990) Burns and Baybarz (1972)

Metals and inorganic compounds

2435

Water molecules can be directly bonded to the metal or take on a non‐bonding role in the lattice. In the case of thorium(IV) sulfates, the number of water molecules in the lattice is variable by controlling the temperature of crystallization. The octahydrate is crystallized from neutral aqueous solution at 20–25 C, lower hydrates are obtained by drying at 100–110 C, and the anhydrous form is formed at 400 C. In the octahydrate, the coordination sphere around thorium is occupied by four oxygen atoms from two chelating sulfate groups and the oxygen atoms of six water molecules, resulting in bicapped square antiprismatic geometry. These polyhedra are linked by hydrogen bonding (Habash and Smith, 1983). Protactinium sulfates are rare, probably due to the difficulties in handling this element. One example is H3PaO(SO4)3 which has hexagonal symmetry, but decomposes to amorphous H3PaO(SO4)3 at 375 C (Bagnall et al., 1965). Uranyl sulfate structures, however, are more common because they constitute a widespread class of minerals. For example, in the cluster compound Na10[(UO2) (SO4)4](SO4)2 · 3H2O, the [(UO2)(SO4)4]6 anion (Fig. 22.10) is composed of a uranyl pentagonal bipyramid that shares an edge with one sulfate tetrahedron and vertices of three tetrahedra (Burns and Hayden, 2002). Polymorphism is displayed in 2UO2SO4 · 7H2O; the a and b forms are similar, but differ in the

Fig. 22.10 The uranyl sulfate cluster in the crystal structure of Na10[(UO2)(SO4)4] (SO4)2 · 3H2O (Burns and Hayden, 2002).

2436

Actinide structural chemistry

way in which their chains are repeated and the orientation of their polyhedra (Zalkin et al., 1978b). Examples of neptunium and plutonium sulfate structures are also available. The compound (NpO2)2SO4 · H2O is a rare example of cation–cation interactions. Each linear NpOþ 2 unit is coordinated equatorially by three oxygen atoms from three sulfate groups as well as two oxygen atoms from two neighboring neptunyl groups, resulting in pentagonal bipyramidal polyhedra (Grigor’ev et al., 1993a). Higher hydrated forms are also known, depending on the conditions of preparation (Budantseva et al., 1988). The hexavalent actinide compounds of the composition AnO2SO4 · 2.5H2O (An ¼ U, Np, Pu) are isostructural with monoclinic symmetry. Two structural modifications are known for Pu(SO4)2 · 4H2O (a and b), both of which are monoclinic; the latter modification has a lattice constant (a‐axis) nearly twice as large as the former (Weigel and Hellmann, 1986). The compound Am2(SO4)3 · 8H2O, a rare americium sulfate, was studied using single‐crystal X‐ray diffraction. Each trivalent americium atom is coordinated by four oxygen atoms from four sulfate groups and by four water molecules; the resulting polyhedron is intermediate between an antiprism and a dodecahedron. Extensive hydrogen bonding links the polyhedra and the structure is isomorphous with the neodymium analog (Burns and Baybarz, 1972).

22.4 COORDINATION COMPOUNDS

Structural studies of coordination compounds of actinides in the solid state are quite numerous and diverse. Crystallographic information generated from X‐ray and neutron diffraction techniques regarding the structural details of such compounds is too extensive to be comprehensively discussed herein. Thus, the following section comprising actinide coordination compounds will focus on two major areas: (1) structures containing carboxylic acid‐derived acyclic ligands and (2) structures containing macrocyclic ligands including crown ethers, calixarenes, and porphyrins/phthalocyanines. Organoactinide compounds will be treated separately. Actinide complexes with acyclic ligands are by no means limited to those involving carboxylic acids; a large number of crystal structures are available for those containing amides, phosphine oxides, and carbonyls, just to name a few. Due to the great diversity in this area, carboxylic acids were chosen owing to their extensive employment as actinide extraction ligands, ion‐exchange media, and as agents in other practical applications. Their ability to act in both monodentate and bidentate modes and yield complexes of high coordination number has resulted in a plethora of structural characterizations, which will be illustrated in Section 22.4.1.

Coordination compounds

2437

Macrocyclic ligands, including crown ethers, calixarenes, and porphyrins/ phthalocyanines, have received a lot of attention due to their cyclic arrangement of donor atoms (including oxygen, nitrogen, and sulfur) for coordination to both lanthanide and actinide cations. The ability to vary the ring size of the macrocycle, as well as to alter the identity of the donor atoms (to tune hard/soft properties), has resulted in the generation of a large number of crystal structures that exhibit tremendous diversity, particularly with regard to the role of counter‐ions for the generation of inclusion versus exclusion complexes. Examples of structurally characterized actinide/macrocycle complexes will be presented in Section 22.4.2. Organoactinide structures involving cyclopentadienyl ligands, their derivatives, and related ligands, on account of their distinction from both acyclic and macrocyclic actinide complexes, will be the focus of Section 22.5. In addition, the chemistry of organoactinide complexes, including both synthesis and characterization, is the focus of Chapter 25. 22.4.1

Complexes with carboxylic acids

Carboxylic acids typically form stable coordination complexes with the large actinide ions via monodentate or bidentate donation through the carboxylate oxygen atoms, yielding complexes of high coordination number. Representative carboxylate ligands include monocarboxylate species such as formates, acetates, glycolates, and salicylates, dicarboxylate species such as oxalates and malonates, and pyridine or benzene derivatives containing three or more carboxylate functionalities. Several coordination modes are possible in carboxylic acid complexes with actinides, the major types of which are represented in Fig. 22.11 (for monocarboxylic acids). Carboxylic acid ligands can engage in both monodentate and bidentate coordination modes, as well as provide more than one bonding site per molecule. These features make carboxylic acids highly versatile ligands as evidenced in the high number of structural characterizations that have been made (Tables 22.21–22.23). Structural characteristics of representative examples will be described. While a large number of carboxylic acid ligands exhibit the potential to chelate actinide cations, crystal structures have been most commonly determined of formates, acetates, oxalates, and malonates. This is due to the small O O ‘bite’ distances and the overall relative compactness of the molecules, resulting in easy packing in the crystal lattice. Large or bulky chains attached to the (mono‐ or di‐) carboxylate functionality tend to make crystallization and subsequent structural characterization difficult (Casellato et al., 1978). Formates are the simplest type of carboxylic acid, where the the R1 group is a hydrogen atom. Actinide formates are typically prepared in solution using formic acid or a formate salt. Uranium(VI) diformate monohydrate crystallizes in the orthorhombic space group with the uranyl ion coordinated equatorially by five oxygen atoms, resulting in pentagonal bipyramidal geometry around the

2438

Actinide structural chemistry

Fig. 22.11 Summary of possible monocarboxylic acid bonding modes. R1 can be a hydrocarbon radical or a proton (Casellato et al., 1978).

uranium atom. The equatorial coordination is assigned to one oxygen atom from bound water and four oxygen atoms from the formate ligands, with these nodes forming infinite formate–uranium–formate chains, further stabilized by hydrogen bonding through bound water (Mentzen et al., 1977). The monoclinic NaUO2(HCOO)3 · H2O lattice contains an interesting combination of structural motifs with two distinct types of formate bonding (Fig. 22.12). First, the uranyl motif contains equatorial pentagonal coordination through five formate oxygen atoms. The two uranyl oxygen atoms reside axially, resulting in a pentagonal bipyramid about uranium. The second motif has hexa‐coordination around Naþ using two oxygen atoms from water and four from formate ligands. Each uranium polyhedron is formed from three types of formate ligands. First, one type of formate bridges adjacent uranium centers, resulting in infinite formate–uranium–formate chains. Second, two infinite chains are bridged by a second type of formate, resulting in a uranium polyhedra ‘layer’. Third, layers of sodium polyhedra and uranium polyhedra are bridged by a third type of formate ligand, resulting in an ..ABABA.. layering scheme (Claudel et al., 1976, Mentzen, 1977). Formate complexes with Th(IV) have also have been structurally investigated. For example, Th(HCOO)4 · 3H2O contains a central thorium atom with coordination number of ten, formally described as [Th(HCOO)4 · 2H2O]H2O. Each thorium is coordinated to eight oxygen atoms of eight separate bridging formate

Table 22.21 Monocarboxylic acid compounds with actinides, by type. Structure formate Am(HCOO)3 Th(HCOO)4 An(HCOO)4, [An ¼ Th(IV), Pa(IV), U(IV), Np(IV)] Th(HCOO)4 2/3H2O Th(HCOO)4 3H2O UO2(HCOO)(OH) H2O UO2(HCOO)2 H2O NaUO2(HCOO)3 H2O (NH4)2UO2(HCOO)4 SrUO2(HCOO)4 (1 þ x)H2O (NH4)NpO2(CHOO)2 acetate Th(CH3COO)4 (CN3H6)2[Th(CH3COO)6] [UO2(CH3COO)2Ph3PO]2 UO2(CH3COO)2(Ph3PO)2 UO2(CH3COO)2Ph3PO [UO2(CH3COO)2Ph3AsO]2 UO2(CH3COO)2(Ph3AsO)2 Na[(UO2)2(m‐OH)2(CH3COO)2(OH)] UO2(CH3COO)2 2H2O NaUO2(CH3COO)3 (C6H15N4O2)[UO2(CH3COO)3] CH3COOH H2O U(CH3COO)4 (NpO2)2(CH3COO)2(H2O) C2H3N NaNpO2(CH3COO)3 BaNpO2(CH3COO)3 2H2O NaPuO2(CH3COO)3 NaAmO2(CH3COO)3

References Weigel and ter Meer (1967) Chevreton et al. (1968) Hauck (1976) Chevreton et al. (1968) Chevreton et al. (1968); Arutyunyan et al. (1966b) Le Roux et al. (1979) Mentzen et al. (1977) Claudel et al. (1976); Mentzen (1977) Mentzen et al. (1978a) Mentzen et al. (1978b) Grigor’ev et al. (1994) Eliseev et al. (1967) Arutyunyan et al. (1966c) Panattoni et al. (1969) Graziani et al. (1967) Graziani et al. (1967) Bandoli et al. (1968) Bandoli et al. (1968) Avisimova et al. (2001) Howatson et al. (1975) Zachariasen and Plettinger (1959); Navaza et al. (1991) Silva et al. (1999) Jelenic´ et al. (1964) Charushnikova et al. (1995) Zachariasen (1954) Burns and Musikas (1977) Zachariasen (1954) Zachariasen (1954)

propionate MUO2(CH3CH2COO)3, (M ¼ Cs, Rb, Tl, NH4) Ca[UO2(C2H5COO)3]2 6H2O

Benetollo et al. (1995)

glycolate UO2(CH2OHCOO)2 U(CH2OHCOO)4 2H2O NpO2(CH2OHCOO) H2O

Mentzen and Sautereau (1980) Alcock et al. (1980b) Grigor’ev et al. (1995)

salicylate [UO2(NO3)(C7H4O3)(DMAP)]2 [H3O][UO2(C7H5O3)3] 5H2O Am(C7H5O3)3 H2O

Nassimbeni et al. (1976) Alcock et al. (1989) Burns and Baldwin (1977)

Burkov et al. (1997)

2440

Actinide structural chemistry Table 22.21 (Contd.)

Structure

References

benzoate Na[UO2(C6H5COO)3] (C6H5COOH) H2O

Benetollo et al. (1995)

pyridine‐2‐carboxylate (monopicolinate) [(UO2)3(C5H4NCOO)2(NO3)2(H2O)2] 2H2O

Silverwood et al. (1998)

pyridine‐3‐carboxylate UO2(C5H4NCOO)2(H2O)2

Alcock et al. (1996a)

2,6‐dihydroxybenzoate [UO2(C6H3(OH)2COO)2(H2O)2] 8H2O

Cariati et al. (1983)

amino acid UO2(CO2CH2NH3)4 (NO3)2 (glycine) UO2(g‐aminobutanoic acid)3(NO3)2 H2O

Alcock et al. (1985) Bismondo et al. (1985)

anthranilate (1), pyrazinate (2 ) (H3O)[UO2(C6H4NH2COO)3]H2O (1) [UO2(C4H3N2COO)2(H2O)] 2H2O (2)

Alcock et al. (1996b) Alcock et al. (1996b)

ligands, resulting in a distorted Archimedic antiprism. The remaining two coordination sites are occupied by oxygen atoms from two water molecules located in the square faces of the antiprism (Chevreton et al., 1968). Acetate ligands are carboxylates where R1 is a methyl group, making them compact for packing in a crystal. The uranyl acetate dihydrate lattice contains a uranyl cation equatorially coordinated to an oxygen from a water molecule, two oxygen atoms from a chelating acetate ligand, and two oxygen atoms from two bridging acetate ligands, resulting in a distorted pentagonal bipyramidal geometry around the uranium center. The bridging acetates link the uranium centers together to form propagating chains, and adjacent chains are associated with one another through a lattice water molecule; this water participates in hydrogen bonding to the bound water of one chain and two acetate ligands of the neighboring chain (Howatson et al., 1975). Acetate complexes with uranyl incorporating phosphine oxides have also been structurally characterized and are significant with regards to separations processes. Certain types of phosphine oxides exhibit functional extractive abilities for actinides such as uranium and plutonium, making them invaluable for remediating acidic media and waste streams. The compound UO2(CH3 COO)2(Ph3PO)2 and the related arsine oxide analog UO2(CH3COO)2 (Ph3AsO)2 were found to be isomorphous by single‐crystal X‐ray diffraction (Graziani et al., 1967; Bandoli et al., 1968). The related compounds [UO2(CH3 COO)2(Ph3PO)]2 (Panattoni et al., 1969) and [UO2(CH3COO)2(Ph3AsO)]2 (Bandoli et al., 1968) have also been isolated. The former structure consists of two seven‐coordinate uranium centers. Each uranium has two axial uranyl

Table 22.22 Dicarboxylic acid compounds with actinides, by type. Structure oxydiacetate [Th(SO4)(CO2CH2OCH2CO2)(H2O)2] H2O Th(CO2CH2OCH2CO2)2(H2O)4 6H2O Na2[Th(CO2CH2OCH2CO2)3] 2NaNO3 [UO2(CO2CH2OCH2CO2)]n [C2H5NH2(CH2)2NH2C2H5] [UO2(CO2CH2OCH2CO2)2] [(CH3)2NH(CH2)2NH(CH3)2] [UO2(CO2CH2OCH2CO2)2] (C6H13N4)2[(UO2)2(CO2CH2OCH2CO2)2 (m‐OH)2] 2H2O Na2[UO2(CO2CH2OCH2CO2)2] 2H2O iminodiacetate [UO2(CO2CH2NH2CH2CO2)]n UO2(CO2CH2NH2CH2CO2)2 (C4H12N2)[(UO2)2(CO2CH2NHCH2CO2)2 (m‐OH)2] 8H2O

References Graziani et al. (1983) Benetollo et al. (1984) Benetollo et al. (1984) Bombieri et al. (1972, 1974a) Jiang et al. (2002) Jiang et al. (2002) Jiang et al. (2002) Bombieri et al. (1973) Battiston et al. (1979) Bombieri et al. (1974b) Jiang et al. (2002)

glutarate UO2(CO2(CH2)3CO2)Li(CO2(CH2)3COOH) 4H2O

Benetollo et al. (1979)

succinate UO2(CO2(CH2)2CO2) DMSO UO2(CO2(CH2)2CO2) H2O

Shchelokov et al. (1985) Bombieri et al. (1979)

oxalate Ac2(C2O4)3 10H2O K4Th(C2O4)4 4H2O UO2(C2O4) 3H2O Na3UO2(C2O4)F3 6H2O M3[UO2(C2O4)2]F 2H2O (M ¼ Na, Rb, Cs) M3UO2(C2O4)F3 2H2O (M ¼ K, Rb, Cs) K2UO2(C2O4)F2 K2(UO2)2(C2O4)F4 K4UO2(C2O4)2F2 K3[UO2(C2O4)2]F 3H2O K2(UO2)2(C2O4)3 4H2O K4U(C2O4)4 4H2O K6[(UO2)2(C2O4)5] 10H2O Cs2UO2(C2O4)(SeO4) Cs4[UO2(C2O4)2(SO4)] 2.7H2O Ba2[U(C2O4)4(H2O)] 7H2O (NH4)2[UO2(C2O4)(SeO4)] 1.5H2O (NH4)2[UO2(O2)(C2O4)(H2O)] 2H2O (NH4)3[UO2(NH2O)(C2O4)2] H2O (NH4)3[UO2(C2O4)2]F H2O (NH4)2UO2(C2O4)2 (NH4)4UO2(C2O4)3 (NH4)2(UO2)2(C2O4)3

Weigel and Hauske (1977) Akhtar and Smith (1969) Jayadevan and Chackraburtty (1972) Dao et al. (1984) Dao et al. (1984) Dao et al. (1984) Chakravorti et al. (1978) Chakravorti et al. (1978) Chakravorti et al. (1978) Dao et al. (1984) Jayadevan et al. (1975) Favas et al. (1983) Legros and Jeannin (1976) Mikhailov et al. (2000a) Mikhailov et al. (2000b) Spirlet et al. (1986, 1987a) Mikhailov et al. (1996) Baskin and Prasad (1964) Shchelokov et al. (1984) Dao et al. (1984) Alcock (1973a) Alcock (1973b) Alcock (1973c)

Table 22.22 (Contd.) Structure

References

(NH4)2(CH6N3)4[(UO2)2(C2O4)5] 2H2O (N2H5)2UO2(C2O4)2(H2O) (N2H5)6[(UO2)2(C2O4)5] 2H2O Tl2UO2(C2O4)2 2H2O (NpO2)2C2O4 6H2O NpO2(C2O4) 3H2O Np(C2O4)2 6H2O H2Np2(C2O4)3(C2O4)2 9H2O NaNpO2(C2O4) 3H2O K6(NpO2)2(C2O4)5 nH2O (n ¼ 2–4) Cs2NpO2(C2O4)2 2H2O Cs2(NpO2)2(C2O4)3 (NH4)NpO2(C2O4) 8/3H2O [Co(NH3)6][NpO2(C2O4)2] nH2O (n ¼ 3, 4) PuO2(C2O4) 3H2O Pu2(C2O4)3 10H2O Am2(C2O4)3 10H2O

Chumaevskii et al. (1998) Poojary and Patil (1987) Govindarajan et al. (1986) Jayadevan et al. (1973) Grigor’ev et al. (1996) Mefod’eva et al. (1981) Grigor’ev et al. (1997) Charushnikova et al. (1998) Tomilin et al. (1984) Mefod’eva et al. (1981) Mefod’eva et al. (1981) Mefod’eva et al. (1981) Grigor’ev et al. (1991b) Grigor’ev et al. (1991c) Mefod’eva et al. (1981) Chackraburtty (1963) Weigel and ter Meer (1967)

malonate (C2H10N2)2[Th(CO2CH2CO2)4(H2O)] (C4H12N2)2[Th(CO2CH2CO2)4] H2O Li2UO2(CO2CH2CO2)2 nH2O (n ¼ 1, 3) Na2UO2(CO2CH2CO2)2 nH2O (n ¼ 0, 2) K2UO2(CO2CH2CO2)2 H2O (NH4)2UO2(CO2CH2CO2)2 H2O [U(CO2CH2CO2)2(H2O)3]n MUO2(CO2CH2CO2)2 3H2O (M ¼ Ba, Sr) (NpO2)2(CO2CH2CO2) nH2O (n ¼ 3, 4)

Zhang et al. (2000) Zhang et al. (2000) Herrero et al. (1977) Herrero et al. (1977) Herrero et al. (1977) Rojas et al. (1979) Zhang et al. (2000) Bombieri et al. (1980) Grigor’ev et al. (1993b,c)

methylmalonate (C4H12N2)2[Th(CO2CH(CH3)CO2)4] 2H2O [{Co(NH3)6}{UO2(CO2CH(CH3)CO2) (CO2C(CH3)2CO2)}]2Cl2 6H2O (C4H12N2)[UO2(CO2CH(CH3)CO2)2(H2O)] 1.5H2O (C4H14N2)[UO2(CO2CH(CH3)CO2)2(H2O)] 2H2O

Zhang et al. (2002a) Zhang et al. (2002a)

dimethylmalonate (C2H10N2)2[Th(CO2C(CH3)2CO2)4] 5H2O (C10H26N2)[(UO2)2(CO2C(CH3)2CO2)3] (C2H10N2)[UO2(CO2C(CH3)2CO2)2(H2O)] H2O (C6H16N2)[(UO2)3(CO2C(CH3)2CO2)4(H2O)2] 3H2O (C7H20N2)[UO2(CO2C(CH3)2CO2)2] 3H2O [{Co(NH3)6}{UO2(CO2C(CH3)2CO2)2}Cl]2 7H2O

Zhang et al. (2000) Zhang et al. (2002b) Zhang et al. (2002b) Zhang et al. (2002b) Zhang et al. (1998) Zhang et al. (1998)

diethylmalonate (C4H12N2)[UO2(CO2C(C2H5)2CO2)2(H2O)] H2O (C10H26N2)[UO2(CO2C(C2H5)2CO2)2(H2O)] 2H2O (C10H26N2)[(UO2)3(CO2C(C2H5)2CO2)5] 2H2O

Zhang et al. (2002a) Zhang et al. (2002a) Zhang et al. (2002a)

Zhang et al. (2000) Zhang et al. (2002a)

Coordination compounds

2443

Table 22.22 (Contd.) Structure

References

pyridine‐2,6‐dicarboxylate (dipicolinate) Th[C5H3N(COO)2]2(H2O)4 {UO2[C5H3N(COO)2] H2O}n U[C5H3N(COO)2]2(H2O)3 3.5H2O (Ph4As)2UO2[C5H3N(COO)2]2 6H2O (Ph4As)2U[C5H3N(COO)2]3 3H2O (UO2)3[C5H3N(COO)(COOH)]2 [C5H3N(COO)2]2 2H2O UO2(C7H3NO5) 3H2O UO2[C5H3N(COO)2]2 (C5H4NCOOH) 6H2O

Bombieri et al. (1977) Cousson et al. (1991)

fumarate (1), maleate (2) UO2(C4H4O4)(H2O)2 (1) [UO2(C4H2O4)K(C4H3O4)] (2)

Bombieri et al. (1982) Bombieri et al. (1981)

Table 22.23

Degetto et al. (1978) Immirzi et al. (1975) Haddad et al. (1987) Marangoni et al. (1974) Baracco et al. (1974) Cousson et al. (1993)

Tetracarboxylic and hexacarboxylic acid compounds with actinides, by type.

Structure

References

1,2,4,5‐benzenetetracarboxylate (NH4)3[(NpO2)5(C10O8H2)2] 7H2O [Na3NpO2(C10O8H2)]2 11H2O UO2(C10O8H4) 2H2O

Cousson (1985) Nectoux et al. (1984) Cousson et al. (1986)

benzene hexacarboxylate Na4(NpO2)2(C12O12) 8H2O

Nectoux et al. (1984); Cousson et al. (1984)

Fig. 22.12 Crystal structure of anionic portion of NaUO2(HCOO)3 · H2O, with Naþ, H2O, and hydrogen atoms omitted (Claudel et al., 1976). The coordinates were obtained from the Cambridge Structural Database (refcode SURFOR).

2444

Actinide structural chemistry

oxygen atoms and pentagonal equatorial coordination provided by a chelating acetate group, two oxygen atoms from bridging acetate groups, and an oxygen atom from a triphenyl phosphine oxide moiety. It is isomorphous with the arsenic‐containing analog. An example of a pentavalent actinide complex is illustrated (Fig. 22.13) in the single‐crystal X‐ray diffraction structure of BaNpO2(CH3COO)3 2H2O. The anion contains a linear NpOþ 2 unit surrounded equitorially by three bidentate acetate groups, resulting in a hexagonal bipyramidal geometry around the neptunium center. The Ba2þ cation acts a crosslinker with shared coordination between six acetate oxygen atoms of three different neptunium polyhedra and the oxygen atoms of two lattice water molecules, resulting in a dodecahderal/ ˚, square antiprism polyhedron. Neptunyl Np–O bond distances are 1.85(2) A ˚ (Burns and Musiwhile Np–Oacetate distances range from 2.52(2) to 2.56(2) A kas, 1977). Tetravalent thorium forms an anhydrous complex with four acetate ligands, Th(CH3COO)4, that is structurally isomorphous (Eliseev et al., 1967) with the uranium(IV) analog (Jelenic´ et al., 1964). Each thorium center is ten‐coordinate;

Fig. 22.13 Crystal strucuture of BaNpO2(CH3COO)3 · 2H2O with hydrogen atoms omitted (Burns and Musikas, 1977). The coordinates were obtained from the Cambridge Structural Database (refcode BNPTAC ) (Allen, 2002).

Coordination compounds

2445

eight oxygen atoms are provided by eight acetate ligands that bridge between adjacent thorium centers and the remaining two coordination sites are occupied by two of these acetate ligands acting in a tridentate manner (i.e., both oxygen atoms close to the metal center). Dicarboxylate complexes with actinides are well studied, as evidenced by the large number of crystal structures present in the literature (Table 22.22). Crystallographic information for complexes with the simplest dicarboxylate, the oxalate ligand, is abundant, primarily due to its high affinity for actinides, the ability to form both four‐ and five‐membered rings, and its potential to chelate in a tetradentate manner. An example of the tetradentate ability of oxalate is illustrated in UO2(C2O4) · 3H2O. Each oxalate ligand, through its four oxygen donors, bridges two uranyl ions yielding five‐membered rings; additional coordination is provided by the oxygen of a water molecule, making each uranium center hepta‐coordinate and pentagonal bipyramidal. The remaining two water molecules, while not participants in direct uranium bonding, engage in hydrogen bonding to further stabilize the complex (Jayadevan and Chackraburtty, 1972). The crystal structure of monoclinic K2(UO2)2(C2O4)3 · 4H2O shows the association of three separate oxalate ligands with a single uranyl cation (Fig. 22.14). Each linear uranyl fragment has six oxygen atoms bound equatorially from three oxalate ligands, forming three five‐membered rings, with an average

Fig. 22.14 Crystal strucuture of anionic portion of K2(UO2)2(C2O4)3 · 4H2O with Kþ, H2O, and hydrogen atoms omitted (Jayadevan et al., 1975). The coordinates were obtained from the Cambridge Structural Database (refcode KUROXT ).

2446

Actinide structural chemistry

˚ . The geometry around each uranium atom is U–O bond distance of 2.45(4) A hexagonal bipyramidal, with the equatorial hexagon being slightly puckered. Each oxalate group takes on a tetradentate role while associated with two uranyl cations, yielding infinite polymeric anions in the crystal lattice; the Kþ cations are associated with eight oxygen atoms from the oxalate ligands and the ˚ (Jayadevan et al., 1975). lattice water molecules within a sphere of about 3.2 A Bridging oxalate coordination and the absence of uranium‐bound water is observed in K6[(UO2)2(C2O4)5] · 10H2O; each uranyl cation in the dinuclear hexavalent anion is five‐coordinate equatorially. Two oxalate ligands coordinate in a bidentate manner, forming two five‐membered rings, and one oxalate bridges symmetrically, donating one oxygen atom to each uranium center. The pentagonal bipyramidal polyhedron around uranium has an average equatorial ˚ (Legros and Jeannin, 1976). U–O bond distance of 2.38 A Pyridine‐2,6‐dicarboxylic acid (pdca) can be multidentate through oxygen only or heteronuclear oxygen/nitrogen donation, and can form monomeric or polymeric metal‐templated complexes. A repeating helical pattern is found in the single‐crystal X‐ray diffraction structure of [UO2{C5H3N(COO)2} H2O]n where pseudo‐planar pentagonal equatorial coordination around the linear uranyl ion is provided by two oxygens and one nitrogen from the pdca ligand, oxygen from a water molecule, and oxygen from a neighboring pdca ligand (Fig. 22.15). The bridging provided by the neighboring pdca ligand results in a polymeric structure that takes on a helical shape. In the crystal, all helices are of ˚ . Each helix is surrounded the same sense and possess a diameter of about 21 A

Fig. 22.15 Crystal strucuture of [UO2{C5H3N(COO)2} · H2O]n with hydrogen atoms omitted (Immirzi et al., 1975). The coordinates were obtained from the Cambridge Structural Database (refcode PYDCUO ).

Coordination compounds

2447

by six other helices that are associated with one another via hydrogen bonding between bound water and dangling C–O groups (Immirzi et al., 1975). Malonate ligands are dicarboxylates, structurally related to oxalates, where the caboxylate functionalities are joined by a methylene group. Several Th(IV) and U(VI) malonato complexes have been structurally characterized, once again taking advantage of the relatively compact nature of the malonate ligand for crystal packing. Malonate ligands have the ability to coordinate with actinides in bidentate, tridentate, and tetradentate modes, examples of which will be shown when available. The structure of the bispiperazinium complex, (C4H12N2)2[Th(CO2CH2 CO2)4] · H2O, contains an eight‐coordinate thorium atom with four 1,5‐bidentate malonate ligands, resulting in a monomeric anionic complex (Fig. 22.16). The geometry around the thorium is distorted square antiprismatic, with the ˚ . The lattice water Th–O bond distances ranging from 2.337(2) to 2.450(2) A molecule is uncoordinated. The compounds (C2H10N2)2[Th(CO2CH2CO2)4(H2O)], (C4H12N2)2[Th(CO2CH(CH3)CO2)4] · 2H2O, and (C2H10N2)2[Th (CO2C(CH3)2 CO2)4] · 5H2O have similar coordination around the thorium center with the exception that the former compound has a bound water, giving

Fig. 22.16 Crystal strucuture of anioic portion of (C4H12N2)2[Th(CO2CH2CO2)4] ·H2O with (C4H12N2)2þand H2O omitted (Zhang et al., 2000). The coordinates were obtained from the Cambridge Structural Database (refcode WONKUF).

Actinide structural chemistry

2448

the thorium a coordination number of nine and a mono‐capped distorted square antiprismatic geometry. The latter two structures contain methylmalonate and dimethylmalonate ligands, respectively (Zhang et al., 2000). The structure of [U(CO2CH2CO2)2(H2O)3]n, however, contains uranium with a coordination number of nine in a mono‐capped square antiprismatic geometry. The coordination sphere is achieved through two 1,5‐bidentate malonate ligands, each also bridging to an adjacent uranium through a carbonyl oxygen (thus the malonate ligands are tridentate) and oxygen atoms from three water molecules. The bridging character of the malonate ligands results in the formation of infinite chains. Chelating U–O bond distances are 2.315(4) and 2.434(4) ˚ , while the bridging U–O distance is 2.420(4) A ˚ (Zhang et al., 2000). A Two other types of malonate binding have also been observed using single‐ crystal X‐ray diffraction. The structure of (C6H16N2)[(UO2)3(CO2C(CH3)2 CO2)4(H2O)2] · 3H2O (involving dimethylmalonate), has two distinct uranium sites. The first site shows hexagonal bipyramidal geometry around a single uranium center from two axial uranyl oxygen atoms, two trans equatorial water molecules, and two equatorial 1,3‐bidentate malonate ligands. The second site shows two crystallographically equivalent uranium atoms, each also with hexagonal bipyramidal geometry. This geometry results from two axial uranyl oxygen atoms, a 1,3‐bidenate malonate ligand that bridges the uranium atom at the first site, and two malonate ligands in a m2‐1,3‐ and 1,5‐bidentate arrangement. The malonate that bridges the two uranium sites is coordinated in a bis(1,3‐bidentate) manner, making the ligand tetradenate and the overall structure infinite (Zhang et al., 2002b). Higher order carboxylate ligands (tetracarboxylate and hexacarboxylate) are shown in Table 22.23, the details of which will not be discussed here.

22.4.2 (a)

Complexes with macrocyclic ligands

Crown ethers

Traditional crown ethers are cyclic polyether molecules that interact with the actinide cations in one of two fashions: either through an inner‐sphere coordination mode, resulting in direct metal ion inclusion into the crown ether cavity, or through an outer‐sphere coordination mode involving hydrogen bonds with the uranyl cation where the metal–crown interaction results in sandwich or polymeric structures. Crown ether derivatives where oxygen has been replaced with nitrogen (azacrowns) or sulfur (thiacrowns) have also been studied, thus taking advantage of the softer character of these elements. The complexation characteristics of crown ethers depend on a variety of factors, including size of cavity (size‐fitting effect), nature of the heteroatoms present, as well as the type of counter ions, all of which are critical in obtaining inclusion versus exclusion complexes.

Coordination compounds

2449

For inclusion complexes, the diameter of the crown ether molecule, and thus the ability for an actinide cation to fit within the cavity, increases from 12‐crown‐4, to 15‐crown‐5, to 18‐crown‐6. Crown ethers are neutral molecules; crystal structures showing metal ion complexation that results in inclusion usually have one or more poorly coordinating anions present to balance the charge on the cation. The formation of crown ether inclusion complexes, as indicated by the few structures available in the literature, takes careful matching of solvent and counter‐ions to suitable macrocyclic cavity sizes (Bradshaw et al., 1996). Representative structures of actinide inclusion complexes are shown in Table 22.24. In UO2(18‐crown‐6)(CF3SO3)2, an inclusion complex between UO2þ and 2 18‐crown‐6, the trifluoromethanesulfonate anion is not directly bound to the complex, but rather effectively balances the overall charge (Deshayes et al., 1994a). The linear uranyl fragment is perpendicular with respect to the crown plane and the six crown ether oxygen atoms coordinate the uranium atom equatorially, resulting in an overall hexagonal bipyramidal geometry. The average ˚ . In the related structure (Fig. 22.17), equatorial U–O bond distance is 2.50(5) A UO2(dicyclohexyl‐18‐crown‐6)(CF3SO3)2, uranyl insertion into dicyclohexano‐ 18‐crown‐6 results in a similar 1:1 UO2:crown inclusion complex where the geometry about the uranium atom is a hexagonal bipyramid (Deshayes et al., 1994a). Here, the average equatorial U–O bond distance is slightly longer at ˚ , indicating that the dicyclohexane rings of the crown ether result in a 2.58(7) A less flexible coordination environment. The uranyl cation in the related inclusion complex UO2(18‐azacrown‐6) (CF3SO3)2 is bonded to all six nitrogen atoms of the crown in a hexagonal bipyramidal manner. The six nitrogen atoms in the azacrown ring are in a ˚ out of this plane. The puckered plane with the uranium atom lying 0.066(1) A ˚ , indicating the relative weakness of average U–N bond distance is 2.66(6) A

Table 22.24 Inclusion compounds of actinides and crown ethers. Structure

References

UO2(18‐crown‐6)(CF3SO3)2 UO2(18‐crown‐6)(ClO4)2

Deshayes et al. (1994a) Dejean et al. (1987); Folcher et al. (1979) Bombieri et al. (1978a) Moody et al. (1979) Deshayes et al. (1994a) Navaza et al. (1984) Dejean et al. (1987) de Villardi et al. (1978) Nierlich et al. (1994) Thue´ry et al. (1995a) Clark et al. (1998b)

[UCl3(18‐crown‐6)]2[UO2Cl3(OH)(H2O)] MeNO2 U(BH4)3(18‐crown‐6)3/4 UO2(dicyclohexyl‐18‐crown‐6)(CF3SO3)2 UO2(dicyclohexyl‐18‐crown‐6)(ClO4)2 [U(BH4)2(dicyclohexyl‐18‐crown‐6)]2[UCl5(BH4)] [UCl3(dicyclohexyl‐18‐crown‐6)]2[UCl6] UO2(18‐azacrown‐6)(CF3SO3)2 UO2(diaza‐18‐crown‐6)(CF3SO3) [NpO2(18‐crown‐6)](ClO4)

2450

Actinide structural chemistry

Fig. 22.17 Crystal strucuture of UO2(dicyclohexyl‐18‐crown‐6)(CF3SO3)2 with hydrogen atoms omitted (Deshayes et al., 1994a). The coordinates were obtained from the Cambridge Structural Database (refcode WIFTUA).

the U–N bond compared to the U–O bond in the above complexes (Nierlich et al., 1994). The compound [U(BH4)2dicyclohexyl‐18‐crown‐6]2[UCl5(BH4)] contains U(III) macrocyclic coordination along with the coexistence of U(IV) in the same crystal. In the cationic portion, the U(III)(BH4)þ2 moiety resides in the crown ether cavity and the two BH4 groups assume axial positions (B–U– B ¼ 173(5) ). All six equatorial oxygen atoms participate in bonding, resulting in hexagonal bipyramidal geometry around uranium. The anion, (UCl5BH4)2– contains uranium in the 4þ oxidation state in a pseudo‐octahedral environment (Dejean et al., 1987). Other crown ether inclusion complexes of uranium include U(BH4)3(18‐crown‐6)3/4, for which only marginal crystallographic data exist due to crystal disorder, making further structural characterization necessary (Moody et al., 1979). A rare example of a transuranium inclusion compound is [NpO2(18‐crown‐ 6)](ClO4). The NpOþ 2 cation resides within the crown ether cavity and the Np center is equatorially coordinated by the six coplanar oxygen atoms at an ˚ , yielding a hexagonal bipyramidal coordination average distance of 2.594(10) A polyhedron (Fig. 22.18). The average Np–O distances of the trans oxo ligands ˚ , unusually short for the NpOþ cation (Clark et al., 1998b). are 1.800(5) A 2 Despite the potential to favorably match crown ether cavities containing five and six donors to the UO2þ ion that prefers such equatorial coordination 2

Coordination compounds

2451

Fig. 22.18 Crystal strucuture of [NpO2(18‐crown‐6)](ClO4) with ClO 4 and hydrogen atoms omitted (Clark et al., 1998b). The coordinates were obtained from the Cambridge Structural Database (refcode NICFUA).

environments, the majority of actinide structures in the literature exhibit second sphere/outer sphere exclusion motifs (Thue´ry et al., 1995d). The result is the formation of ‘supermolecules’ usually involving complex hydrogen‐bonded networks. Hydrogen bonding between the crown ether oxygen atoms and water molecules coordinated to the metal is commonly observed (but not always) (Rogers et al., 1988). Table 22.25 summarizes representative second sphere/ outer sphere actinide‐crown ether exclusion complexes. An interesting example of mistaken identity was observed in the case of UO2(NO3)2(H2O)2 · (12‐crown‐4). An initial study by Armag˘an (1977) contended, based on crystallographic data, that the compound was of the inclusion type. However, all previous and subsequent attempts to place uranyl in the relatively small cavity of 12‐crown‐4 were unsuccessful. Due to anomalies within the reported results, a follow‐up study was done that established the structure as an exclusion complex; UO2(NO3)2 nodes are connected to 12‐crown‐4 molecules through a hydrogen‐bonded network enabled by the lattice water molecules (Ritger et al., 1983). One of the first examples of a hydrogen bonding‐stabilized exclusion complex is that of UO2(NO3)2(H2O)2 · 2H2O · (18‐crown‐6). Discrete UO2(NO3)2(H2O)2 units are separated by crown ether molecules and linked together by hydrogen bonding through intermediary water molecules. Each uranium atom is coordinated to the trans uranyl oxygen atoms, two water molecules, and two bidentate nitrate groups (Eller and Penneman, 1976).

Table 22.25 ethers.

Exclusion (second sphere/outer sphere) compounds of actinides and crown

Structure

References

9‐crown‐3, 12‐crown‐4 UI3(trithia‐9‐crown‐3)(MeCN)2 UO2(SO4)(H2O)2 · (12‐crown‐4)0.5 · H2O UO2(NO3)2(H2O)2 · (12‐crown‐4) [UO2Cl2(H2O)2(12‐crown‐4)] · (12‐crown‐4) [Li(12‐crown‐4)]2[UO2Cl4] [Li(12‐crown‐4)]2[UO2Br4] [Na(12‐crown‐4)2]2[UO2Cl4] · 2MeOH

Karmazin et al. (2002) Rogers et al. (1991) Ritger et al. (1983) Rogers et al. (1989) Danis et al. (2001) Danis et al. (2001) Rogers (1988)

15‐crown‐5 ThCl4(MeOH)2(OH2)2 · (15‐crown‐5) · MeCN UO2(NO3)2(H2O)2(15‐crown‐5) UO2Cl2(H2O)3(15‐crown‐5) (H5O2)[UO2(H2O)2Cl3] · (15‐crown‐5)2 [Na(15‐crown‐5)]2[UO2Cl4] [Na(15‐crown‐5)]2[UO2Br4] [(NH4)(15‐crown‐5)2]2(UO2Cl4) · 2MeCN [UO2(H2O)5][ClO4]2 · (15‐crown‐5)3 · MeCN UO2(SO4)(H2O)2 · (benzo‐15‐crown‐5)0.5 · 1.5H2O UO2(NO3)2(H2O)2(benzo‐15‐crown‐5) [UO2(TTA)2H2O]2(benzo‐15‐crown‐5) [Na(benzo‐15‐crown‐5)]2(UO2Cl4) UO2(NO3)2(H2O)2(benzo‐15‐crown‐5)2 UO2(H2O)3(CF3SO3)2 · (benzo‐15‐crown‐5)2 [(H5O2)(H9O4)(benzo‐15‐crown‐5)2][UO2Cl4] [(H5O2){(NO2)2benzo‐15‐crown‐5}2]2 [{UO2(NO3)2}2C2O4] [(NH4)(benzo‐15‐crown‐5)2]2[UCl6] · 4MeCN [UO2(NO3)2]2(m‐H2O)2(monoaza‐15‐crown‐5)2 18‐crown‐6 [ThCl(OH)(H2O)6]Cl4 · (18‐crown‐6) 2H2O [ThCl2(H2O)7]Cl2 · (18‐crown‐6) 2H2O ThCl4(EtOH)3(H2O) · (18‐crown‐6) H2O Th(NCS)4(H2O)(HOCH2CH2OH)2 (18‐crown‐6) Th(H2O)3(NO3)4 (18‐crown‐6) [(H3O)(dicyclohexyl‐18‐crown‐6)]2[Th(NO3)6] UO2(SO4)(H2O)3 (18‐crown‐6)0.5 [(H5O2)2(18‐crown‐6)][UO2Cl4] [UO2(CH3COO)(OH)(H2O)]2 (18‐crown‐6) UO2(CH3COO)2(H2O)2 · (H2O)2 (18‐crown‐6) UO2(NO3)2(H2O)2(18‐crown‐6) UO2(NO3)2(H2O)2 · 2H2O (18‐crown‐6) UO2(H2O)5(CF3SO3)2 (18‐crown‐6) [UO2(H2PO4)2(H2O)]2 (18‐crown‐6) · 5H2O UO2(H2PO4)2(H2O) (18‐crown‐6) · 3H2O [U(SCN)4(H2O)4][18‐crown‐6]1.5 · 3H2O · (C6H12O) UO2(NCS)2(H2O)3 (18‐crown‐6)1.5 MeCN

Rogers and Benning (1988a) Gutberlet et al. (1989) Hassaballa et al. (1988, 1998) Hassaballa et al. (1998) Danis et al. (2001) Danis et al. (2001) Rogers et al. (1987a) Rogers et al. (1987b) Rogers et al. (1991) Deshayes et al. (1993) Kannan et al. (2001) Moody and Ryan (1979) Deshayes et al. (1993) Thue´ry et al. (1995b) Rogers et al. (1991) Rogers et al. (1991) Rogers et al. (1987a) Cragg et al. (1988) Rogers and Bond (1992) Rogers (1989) Rogers et al. (1988) Rogers et al. (1998) Rogers et al. (1987c) Ming et al. (1988) Rogers et al. (1991) Rogers et al. (1991) Mikhailov et al. (1997) Mikhailov et al. (1997) Bombieri et al. (1978b) Eller and Penneman (1976) Deshayes et al. (1994b) Danis et al. (2000) Danis et al. (2000) Charpin et al. (1977) Rogers et al. (1998)

Coordination compounds

2453

Table 22.25 (Contd.) Structure

References

[(H3O)(18‐crown‐6)]2[{UO2(NO3)2}2C2O4] [UO2(H2O)5][ClO4]2 (18‐crown‐6)2 2MeCN H2O [NH4(18‐crown‐6)]2[UCl6] 2MeCN [NH4(18‐crown‐6)]2[UO2(NCS)4(H2O)] [K(18‐crown‐6)]2[UO2(NCS)4(H2O)] [K(18‐crown‐6)]2[UO2Cl4] [K(18‐crown‐6)]2[UO2Br4] [(UO2)2(OH)2(H2O)6](ClO4)2 [dicyclohexyl‐18‐crown‐6]3 MeCN UO2Cl4(dicyclohexyl‐18‐crown‐6 H3O)2 [UO2(TTA)2(m‐H2O)]2(H2O)2(dibenzo‐18‐crown‐6) [(NH4)(dibenzo‐18‐crown‐6)]2[(UO2Cl4) 2MeCN

Rogers et al. (1991) Rogers et al. (1987b) Rogers and Benning (1988b) Ming et al. (1987a) Ming et al. (1987b) Danis et al. (2001) Danis et al. (2001) Navaza et al. (1984) Guang‐Di et al. (1990) Kannan et al. (2001) Rogers et al. (1987a)

24‐crown‐8 [(H5O2)(dicyclohexyl‐24‐crown‐8)]2(UO2Cl4) MeOH [(H5O2)(dicyclohexyl‐24‐crown‐8)]2(UCl6) MeOH

Rogers and Benning (1991) Rogers and Benning (1991)

The crystal lattice of the compound [(H5O2){(NO2)2benzo‐15‐crown‐5}2]2 [{UO2(NO3)2}2C2O4] contains discrete cation and anion pairs. The anion consists of two UO2(NO3)2 groups (each nitrate is bidentate) bridged by a tetradentate oxalate group (forming two five‐membered rings); each uranium center is surrounded by a hexagonal bipyramidal polyhedron of ligands. A single H5 Oþ 2 ion resides between two 15‐crown‐5 molecules and is stabilized by hydrogen bonding to the ethereal oxygen atoms of the crown ether (Rogers et al., 1991). Inclusion of H3Oþ is observed in the structure of [(H3O)(18‐crown‐ 6)]2[{UO2(NO3)2}2C2O4]; the H3Oþ species resides in the cavity of the crown ether molecule, stabilized by hydrogen bonding (Fig. 22.19). This hydrogen bonding likely occurs with three crown ether oxygen atoms, giving the hydroni˚ out of the plane. The discrete um a pseudo‐pyramidal geometry, residing 0.4 A uranyl‐containing anion adopts the same conformation as the former molecule, with alternate cation–anion–cation stacking (Rogers et al., 1991). In UO2(SO4)(H2O)2 · (12‐crown‐4)0.5 · H2O, two trans uranyl oxygen atoms, two water molecules, and one oxygen each from three sulfate atoms coordinate each uranium atom, generating a pentagonal bipyramid. The sulfate anions bridge each uranium atom to two neighbors, thus forming polymeric double chains. Furthermore, the 18‐crown‐6 molecule and the uncoordinated water molecule form an organic layer that separates the layers of the uranium polymeric double chains; the layers are stabilized by a hydrogen‐bonding network (Rogers et al., 1991). A series of five alkali metal/crown ether/uranyl halide sandwich exclusion complexes have been structurally characterized and each displays square

2454

Actinide structural chemistry

Fig. 22.19 Crystal strucuture of [(H3O)(18‐crown‐6)]2[{UO2(NO3)2}2C2O4] with hydrogen atoms omitted (Rogers et al., 1991). The coordinates were obtained from the Cambridge Structural Database (refcode SODFUM ).

bipyramidal [UO2X4]2– anions sandwiched between two [A(crown ether)]þ cations (X ¼ Cl, Br and A ¼ Li, Na, K). Crown ethers of varying cavity size were investigated, including 18‐crown‐6, 15‐crown‐5, and 12‐crown‐4. The [K (18‐crown‐6)]2[UO2Cl4] and [K(18‐crown‐6)]2[UO2Br4] complexes display Type I bonding behavior where the Kþ cations form inclusion complexes with the crown ethers. Two uranium‐bound halides coordinate in a bridging manner to each Kþ ion and the anionic unit is tilted with respect to the plane of the crown ether toward the Kþ ions to varying degrees (56 for Cl and 63 for Br) (Danis et al., 2001). The [Na(15‐crown‐5)]2[UO2Cl4] has two crystallographically unique anionic units, one of which is Type I bonding, as described above, and the other Type II where only one uranium‐bound chloride interacts with each Naþ ion. Significant tilt of the anionic unit (31 ) also occurs. In the Type I bonding, the linear uranyl unit of the anion is aligned parallel to the crown ether plane. If the halide in the aforementioned complex is changed from Cl to Br, a structural shift occurs to Type III bonding. Here, each crown‐encapsulated Naþ ion is bridged by one uranyl bromide and one uranyl oxygen. The linear unbound Br–U–Br unit is aligned parallel to the crown ether plane. Finally, [Li(12‐crown‐4)]2 [UO2Cl4] and [Li(12‐crown‐4)]2[UO2Br4] both exhibit Type IV bonding and are both nearly isostructural. In both complexes, the bonding to each crown‐

Coordination compounds

2455

encapsulated Liþ is solely through the two uranyl oxygen atoms, resulting in a plane defined by uranium and its four halide atoms that separates the cationic units. The type of bonding exemplified in these structures can be described in terms of hard–soft acid–base theory; in the latter two complexes, the ‘hard’ Liþ ion prefers exclusive interaction with the ‘hard’ uranyl oxygen atoms (Danis et al., 2001). Exclusion crown ether complexes of uranyl incorporating ligands that are important in uranium chemistry are also known. For example, thenoyl (trifluoroacetone) (HTTA), a b‐diketone extractant that acts synergistically with crown ethers in extraction schemes, interacts directly with uranium in [UO2 (TTA)2H2O]2(benzo‐15‐crown‐5) and [UO2(TTA)2(m‐H2O)]2(H2O)2(dibenzo‐18‐crown‐6), where the crown ethers are second‐sphere and third‐sphere ligands, respectively (Fig. 22.20). In both complexes, each uranium attains pentagonal bipyramidal geometry, with equatorial coordination provided by two bidentate HTTA groups and a water molecule. In the former, the bound water hydrogen bonds to the crown ether, making it second sphere. In the latter, intermediate water molecules generate a hydrogen‐bonding network (Kannan et al., 2001). Various forms of phosphate also play significant roles in both processing and environmental aspects of uranium chemistry. The structure of [UO2(H2PO4)2 (H2O)]2 (18‐crown‐6) · 5H2O once again shows pentagonal bipyramidal geometry around uranium, as well as infinite, one‐dimensional [UO2(H2PO4)2(H2O)] chains that are hydrogen‐bonded to uncomplexed crown ether molecules

Fig. 22.20 Crystal strucuture of [UO2(TTA)2H2O]2(benzo‐15‐crown‐5) with hydrogen atoms omitted (Kannan et al., 2001). The coordinates were obtained from the Cambridge Structural Database (refcode RORXIF ).

Actinide structural chemistry

2456

through solvate lattice water molecules. Each of four H2PO 4 units is bound mZ1 to uranium. A similar situation is observed in the crystal structure of UO2(H2PO4)2(H2O) (18‐crown‐6) 3H2O (Danis et al., 2000). Although fewer in number, thorium exclusion‐type crown ether structures are also known. For example, the crystal structure of [(H3O)(dicyclohexano‐18‐ crown‐6)]2[Th(NO3)6] reveals the thorium atom resting at a center of symmetry and unbound to the crown ether donor atoms. The thorium is 12‐coordinate due to bidentate coordination of the six nitrate anions, thus giving it a nearly perfect icosahedral geometry. The Th–O bond distances in this anionic unit ˚ . Each H3Oþ cation rests in the cavity of the crown range from 2.551 to 2.587 A ether molecules, stabilized by three hydrogen bonds, as well as ion–dipole interactions (Ming et al., 1988). (b)

Calixarenes

The class of macrocyclic ligands known as calixarenes is structurally recognized by phenolic subunits joined in a cyclic fashion via methylene linkages; derivatives based on CH2–X–CH2 linkages are also commonly used, where X is O, NH, or S. Substitutions at the pendant phenol oxygen site are also possible. The latter types are of interest due to their less rigid character and larger number of potential donor sites. Calixarenes are highly diverse in terms of available ring sizes, making them excellent candidates for systematic analyses concerning their donor properties in binding to groups of metal ions, including lanthanides and actinides. Traditional calixarene chemistry allows for substitutions at either the lower or upper rim of the calixarene and the tuning of their physical properties. The lower rim of a calixarene comprises the cyclic arrangement of alcohol functionalities of the phenol unit. Typically, substitution is directed to the upper rim, leaving the lower rim unsubstituted, thus comprising the class of ‘phenolic calixarenes’. Due to the variety of ring sizes available, actinide complexes with calixarenes can be either inclusion or exclusion complexes with the coordination based on considerations such as ligand type, ring diameter, and metal ion radius. For a general overview of phenolic calixarene f‐element coordination chemistry, the reader is referred to a review from Thue´ry et al. (2001d); representative single‐crystal X‐ray diffraction structures from the literature will be reviewed herein, the likes of which are summarized in Table 22.26. The complexes formed between UO2þ 2 and triply deprotonated p‐tert‐butylhexahomotrioxacalix[3]arene, studied by Thue´ry et al. (1999a) show the lowest coordination number (five) observed for a uranyl complex (Fig. 22.21). In the presence of the deprotonating agents triethylamine and DABCO, two isomorphous inclusion‐type complexes are formed where the uranyl is located in the center of the lower rim of the calixarene. The uranyl cation is bound in the equatorial plane to the three deprotonated phenolic oxygen atoms with ˚ , yielding pseudo‐trigonal an average U–Oeq bond distance of 2.20(3) A

[{U(tert‐butylcalix[5]arene–5H)}2(m2‐oxo)]2 · 5pyr

calix[5]arenes [Hpyr]2[{U(tert‐butylcalix[5]arene–5H)}2(m2‐oxo)] · 4pyr

[HNEt3]2[UO2{bis(homo‐oxa)‐p‐tert‐butylcalix[4]arene–4H}] · 2H2O [Hpyr][(UO2)2(p‐methyloctahomotetraoxacalix[4]arene–4H)(OH)(H2O)] · 2.5pyr [(UO2)2(1‐acid‐3‐diethylamide substituted calix[4]arene–2H)2] · 10MeCN · 2MeOH [UO2(calix[4]arene–1H)2(DMF)3.7(DMSO)0.3] · [calix[4]arene(DMF)] · 1.5DMF [HNEt3]2[UO2(p‐tert‐butyltetrathiacalix[4]arene–4H)(DMF)] · 2DMF [HNEt3]2[UO2(p‐tert‐butyltetrathiacalix[4]arene–4H)(MeCN)] · 1.7DMSO [Hpyr]2[UO2(p‐methyl‐tetrahomodioxacalix[4]arene–4H)] · 3H2O [HNEt3]2[UO2(p‐phenyl‐tetrahomodioxacalix[4]arene–4H)] · 2CHCl3 [H3NnBu]2[UO2(p‐phenyl‐tetrahomodioxacalix[4]arene–4H)] · (H3NnBu) · (CH3COO) · 2H2O [UO2(p‐methyl‐N‐benzyl‐tetrahomodiazacalix[4]arene–2H)] · 2CHCl3 · MeCN

Leverd and Nierlich (2000) Leverd and Nierlich (2000)

Thue´ry et al. (2001a) Thue´ry et al. (2001a) Leverd and Nierlich (2000) Harrowfield et al. (1991a) Thue´ry et al. (2001b) Beer et al. (1998) Asfari et al. (2001) Asfari et al. (2001) Asfari et al. (2001) Masci et al. (2002b) Masci et al. (2002b) Masci et al. (2002b) Thue´ry et al. (2001c)

Masci et al. (2002a) Masci et al. (2002a) Masci et al. (2002a) Masci et al. (2002a) Masci et al. (2002a) Thue´ry et al. (1999a) Thue´ry et al. (1999a) Thue´ry et al. (2001a)

calix[3]arenes [HNEt3][UO2(p‐methylhexahomotrioxacalix[3]arene–3H)] [HNnPr3][UO2(p‐tert‐butylhexahomotrioxacalix[3]arene–3H)] · MeOH [H3NnBu][UO2(p‐tert‐butylhexahomotrioxacalix[3]arene–3H)] [H2NnBu2][UO2(p‐tert‐butylhexahomotrioxacalix[3]arene–3H)] · MeOH (C6H14N)[UO2(p‐tert‐butylhexahomotrioxacalix[3]arene–3H)] · 2MeOH · H2O [UO2(p‐tert‐butylhexahomotrioxacalix[3]arene–3H)(HNEt3)] · 3H2O [UO2(p‐tert‐butylhexahomotrioxacalix[3]arene–3H)(HDABCO)] · 3MeOH [UO2(NO3)2(p‐chloro‐N‐benzylhexahomotriazacalix[3]arene)] · pyr · CHCl3

calix[4]arenes [UO2(NO3)2(p‐methyl‐N‐benzyltetrahomodiazacalix[4]arene)] · 0.5MeOH · H2O [HNEt3]2[UO2(p‐tert‐butyltetrahomodioxacalix[4]arene–4H)] · CHCl3 · MeCN [{UCl(tert‐butylcalix[4]arene–4H)}3(m3‐oxo)] · 11.5pyr

References

Structure

Table 22.26 Representative actinide‐calix[n]arene compounds, by type.

Thue´ry and Nierlich (1997)

[HNEt3]2[UO2(p‐tert‐butylcalix[5]arene–4H)] · 2MeOH

Thue´ry et al. (1999b) Thue´ry et al. (1998) Thue´ry et al. (1998)

[U{(tert‐butylcalix[6]arene–4H)LaCl2(pyr)4}2] [UO2(p‐tert‐butylcalix[6]arene–4H)]2 · 2(HNEt3) · 2(H3O) · 6MeCN [HNEt3]2[UO2(p‐tert‐butyltetrahomodioxacalix[6]arene–4H)] · 3MeCN [Hpyr]3[Cs][(UO2Cl2)2(tert‐butylcalix[6]arene–4H)] · 7pyr [(UO2)2Li(OH)(p‐tert‐butylhexahomotrioxacalix[6]arene–6H)(pyr)][Li(H2O)3(pyr)] · (Hpyr) · H2O · 4.5pyr [UO2K( p‐tert‐butylhexahomotrioxacalix[6]arene–3H)(H2O)2]2 · 14pyr

calix[7]arenes [(UO2)6(p‐benzylcalix[7]arene–7H)2(O)2(HDABCO)6] · 3MeCN · CH3Cl · 5MeOH · 3H2O [HNEt3]2[UO2( p‐tert‐butylcalix[7]arene–4H)] · MeNO2 · MeOH [HNEt3]2[UO2( p‐tert‐butylcalix[7]arene–4H)] · MeCN · 2H2O

Harrowfield et al. (1991b) Thue´ry et al. (2001b) Thue´ry et al. (1995c) Thue´ry et al. (1995d) Thue´ry et al. (2001d) Thue´ry and Masci (2003) Thue´ry and Masci (2003) Thue´ry et al. (2001d) Leverd et al. (2000)

[HNEt3]2[(UO2)4(p‐tert‐butyloctahomotetraoxacalix[8]arene–8H)(OH)2(H2O)4] · 1.5NEt3 · 2.5H2O · MeOH [(HNEt3)2(OH)][(UO2)2(p‐tert‐butylcalix[8]arene–4H)(OH)] · 2NEt3 · 3H2O · 4MeCN [HNEt3]5[(UO2)2(p‐tert‐butylcalix[8]arene–4H)(OH)]2 · 3OH · 3MeCN [NMe4][(UO2)3(OH)(p‐tert‐butylcalix[8]arene–6H)(DMSO)2] [(UO2)4O4(p‐tert‐butyloctahomotetraoxacalix[8]arene)] · 10MeOH [(UO2)2(pyr)4(p‐tert‐butyloctahomotetraoxacalix[8]arene–4H)] · pyr

calix[9, 12]arenes [HNEt3]3[(UO2)2(p‐tert‐butylcalix[9]arene–5H)(CO3)] [HNEt3]2[{(UO2)2(NO3)(pyr)}2(tert‐butylcalix[12]arene–8H)] · 9pyr

calix[8]arenes [Th4(p‐tert‐butylcalix[8]arene–7H)(p‐tert‐butylcalix[8]arene–6H)(DMSO)4(OH)3(H2O)] · (DMSO) · 2H2O

Leverd and Nierlich (2000) Leverd et al. (2002) Thue´ry et al. (1996) Thue´ry et al. (2001b) Leverd et al. (1998) Thue´ry and Masci (2004) Thue´ry and Masci (2004)

calix[6]arenes [U(tert‐butylcalix[6]arene–3H)2] · (Hpyr)2Cl2 · 10pyr

References

Structure

Table 22.26 (Contd.)

Coordination compounds

2459

Fig. 22.21 Crystal strucuture of [UO2(p‐tert‐butylhexahomotrioxacalix[3]arene–3H ) (HDABCO)] · 3MeOH with MeOH, HDABCO, and hydrogen atoms omitted (Thue´ry et al., 1999a). The coordinates were obtained from the Cambridge Structural Database (refcode BINKOY ).

bipyramidal geometry around the uranium atom. The oxa‐linkages that connect the phenolic units do not take part in the bonding; thus, the five‐coordinate environment around uranium is the lowest ever observed. The overall conformation of the calixarene ligand is cone‐shaped, and the uranyl is slightly displaced from the plane formed by the three bonding phenolic oxygen atoms. This displacement is counter‐ion‐dependent, with triethylamine and DABCO ˚ displacements, respectively (Thue´ry et al., resulting in 0.186(4) and 0.248(3) A 1999a). The trigonal equatorial coordination environment around uranium in the two aforementioned complexes changes with alterations to the upper rim as well as the deprotonating agent. Maintaining the tert‐butyl substitution at the upper rim and changing the deprotonation agent to H2NBu preserves the trigonal equatorial coordination around uranium; however, in the presence of NPr3, a distorted tetragonal coordination is observed, with an ether oxygen also taking part in the bonding. Distorted tetragonal coordination is also observed with a methyl substitution and triethylamine. Higher degrees of equatorial coordination are also possible. A tert‐butyl substitution with 4‐methylpiperidine as

2460

Actinide structural chemistry

the deprotonating agent results in distorted pentagonal coordination aided by the participation of two ether oxygen atoms; an intermediate coordination environment (between tetragonal and pentagonal) occurs with HNBu2 (Masci et al., 2002a). Calix[4]arene‐based actinide complexes are plentiful in the literature, owing to the larger cavity size of the ligand and larger number of potential donor sites. Tetrahomodioxa‐ and tetrahomodiazacalix[4]arene uranyl structures typically show 1:1 complexes with different complexation modes. The complexation of UO2þ 2 with p‐tert‐butyltetrahomodioxacalix[4]arene in the presence of triethylamine yields an inclusion complex where the uranyl is bound equatorially in the plane of four deprotonated phenolic oxygen atoms, with the two calixarene ˚ from ether oxygen atoms taking on a non‐bonding role (3.832(4) and 3.820(4) A uranium). The geometry around uranium is square bipyramidal with an average ˚ (Thue´ry et al., 2001a). U–Oeq bond distance of 2.28(3) A The uranyl/p‐methyl‐N‐benzyltetrahomodiazacalix[4]arene complex, on the other hand, is of the exclusion type. Interestingly, the complex forms in the absence of base, resulting in a neutral 1:1 complex, where the uranyl is bound to two phenolic oxygens (zwitterionic form) of the calixarene and to two nitrate counter‐ions. The uranyl cation rests above the plane of the four phenolic ˚ , with the two bound U–Ophenol oxygen atoms at a distance of 1.543(8) A ˚ . The nitrate anions have different coordidistances at 2.234(9) and 2.269(8) A nation modes, one being mondentate and the other bidentate. The differences observed between the dioxa‐ and diaza‐complexes are presumably due to electrostatic repulsion between the uranyl and the ammonium groups of the diazacalixarene (Thue´ry et al., 2001a). A unique inclusion complex between p‐methyloctahomotetraoxacalix[4]arene and two uranyl cations has also been structurally characterized (Fig. 22.22). The doubly bridged dinuclear cation rests in the calixarene cavity with the bridging provided by a hydroxide and one oxygen atom from a water molecule. Pentagonal bipyramidal geometry around each uranium results from the two axial uranyl oxygen atoms, the two bridging oxygen atoms, two deprotonated phenolic oxygen atoms, and a single ether oxygen atom. The mean U–Ophenoxide ˚ , while the mean U–Oether distances are significantly bond distances are 2.25(2) A ˚ (Thue´ry et al., 2001b). longer at 2.67(2) A The reaction of UO2þ 2 with p‐tert‐butycalix[5]arene in the presence of triethylamine generates an inclusion complex. The uranyl is bound equatorially to the five phenolic oxygen atoms of the lower rim of the calixarene, generating an overall pentagonal bipyramidal geometry around the uranium atom. Interestingly, only four of the five phenolic sites are deprotonated, suggesting that uranyl ion has an acid‐enhancing effect. The U–Oeq bond distances vary greatly; ˚ , a fourth at 2.571(7) A ˚ , and the longest at 2.836(8) three in the range 2.25–2.30 A ˚ . The large variation in the range of U–Oeq bond lengths may be due to the A calixarene cavity being too large for ideal coordination of the uranyl ion. Finally, the calixarene itself takes on the common cone conformation and

Coordination compounds

2461

Fig. 22.22 Crystal strucuture of [Hpyr][(UO2)2(p‐methyloctahomotetraoxacalix[4]arene– 4H )(OH )(H2O)] · 2.5pyr with Hpyr, pyr, and hydrogen atoms omitted (Thue´ry et al., 2001b). The coordinates were obtained from the Cambridge Structural Database (refcode QOPMIR).

one of the protonated triethylamine molecules sits in the cavity of the cone, coordinated with an axial uranyl oxygen atom (Thue´ry and Nierlich, 1997). Single crystals of larger calix[n]arenes, where n ¼ 6, 7, 8, 9, or 12, complexed with actinides have also been isolated and their structures determined. While uranium–calixarene complexes are the most common in the literature, a novel Th(IV) structure with p‐tert‐butylcalix[8]arene has also been solved (DMSO solvate). The structure contains two different calixarene ligands, each with varying degrees of deprotonation (both seven and six protons), bound to four thorium atoms. While the structure itself is very complicated, it is obvious that the two calixarenes attain two different conformations, with one being in a ‘propeller’ conformation and the other a ‘crown’. The two calixarenes form four cone‐shaped cavities, the apices of which are defined by a plane of four phenolic oxygen atoms; each cavity is subsequently associated with a single thorium atom. Each thorium center is associated with five phenolic oxygen atoms, three of which are mondentate while the remaining two take on bridging interactions. DMSO and hydroxide molecules also contribute to the bonding (Harrowfield et al., 1991b). A related uranyl complex incorporating p‐tert‐butylcalix[8]arene is bimetallic and contains only a single calixarene ligand (Fig. 22.23). Here, each uranyl ion

2462

Actinide structural chemistry

Fig. 22.23 Crystal strucuture of [(HNEt3)2(OH)][(UO2)2(p‐tert‐butylcalix[8]arene–4H) (OH)] · 2NEt3 · 3H2O · 4MeCN with [(HNEt3)2(OH)]þ, NEt3, H2O, MeCN, and hydrogen atoms omitted (Thue´ry et al., 1995c). The coordinates were obtained from the Cambridge Structural Database (refcode ZAMJIG).

resides in the cavity of the calixarene, making it an inclusion complex, and each is bound equatorially to four phenolic oxygen atoms, two of which are deprotonated. The uranyl ions are also linked via a bridging hydroxide, thus making the overall geometry around each heptacoordinate uranium atom distorted pentagonal bipyramidal. The equatorial U–O bond lengths at the protonated ˚ , while the corresponding lengths at the deprosites are 2.619(9) and 2.476(9) A ˚ . Two protonated triethylamine moletonated sites are 2.218(9) and 2.20(1) A cules are also associated with the complex, each being hydrogen‐bonded to a separate axial uranyl oxygen atom. The overall conformation of the bound calixarene has been described as a ‘pleated loop’ (Thue´ry et al., 1995c). The largest calixarene complex of an actinide to date for which a single‐crystal X‐ray diffraction structure is known is that between tert‐butylcalix[12]arene and UO2þ 2 (Fig. 22.24). The resulting inclusion complex contains two uranyl bimetallic units; the uranyl ions in each unit are bridged by a tridentate nitrate ligand. Each bimetallic unit is bound to five phenolic oxygen sites, four of which are deprotonated. One uranyl in each unit is bound to three of the oxygen atoms, while the second is bound to the remaining two and a pyridine molecule (through nitrogen). The resulting geometry around each uranium atom is pentagonal bipyramidal. The four shorter U–Oeq bond lengths at each bimetallic

Coordination compounds

2463

Fig. 22.24 Crystal strucuture of [HNEt3]2[{(UO2)2(NO3)( pyr)}2(tert‐butylcalix[12] arene–8H)] · 9pyr with [HNEt3]þ, pyr(unbound ), and hydrogen atoms omitted (Leverd et al., 2000). The coordinates were obtained from the Cambridge Structural Database (refcode MALGEL).

˚ and correspond to the four deprotonated phenolic sites; the unit are about 2.2 A ˚ (Leverd et al., 2000). fifth longer bond length at the protonated site is 2.62(3) A (c)

Porphyrins/phthalocyanines

The macrocyclic ligands commonly referred to as porphyrins are ubiquitous in nature. They are structurally described as an arrangement of four pyrrole units linked together in a cyclic manner at the 2‐ and 5‐positions by methine bridges, forming an aromatic, 22‐p electron system. The iron‐containing porphyrin, commonly known as heme, comprises the primary binding site in hemoglobin that is responsible for dioxygen transport throughout the body. While traditional porphyrins contain only nitrogen‐donor atoms, pyrrole‐derived macrocycles have also been synthesized that contain pyrrole, furan, and thiophene subunits solely, or combinations thereof. In addition, extensive chemistries have been developed in the synthesis of expanded, contracted, and isomeric porphyrins, the details of which have been described elsewhere. Expanded porphyrins will hereafter be defined as containing at least 17 atoms in a conjugated manner and three pyrrole or pyrrole‐like subunits (Sessler and Weghorn, 1997). Porphyrins have been extensively studied as templates for metal ion coordination; the addition of base, such as triethylamine, for the deprotonation of nitrogen sites allows for tetradentate or higher coordination to the metal

Actinide structural chemistry

2464

centers, often times facilitating electronic transitions in the visible portion of the electromagnetic spectrum that give rise to a wide range of observable color changes. In addition, traditional nitrogen‐containing porphyrins give rise to unique coordination complexes with metals that prefer oxygen or sulfur atom donation (Girolami et al., 1994). Traditionally, oxygen and sulfur atoms, when incorporated into ligand support molecules, have been the atoms of choice for coordination to metal centers; thus, the use of pyrrole‐derived porphyrins provides a unique opportunity to study the binding to actinide ions in a non‐traditional manner (i.e. all nitrogen atoms) and the subsequent effect on electronic and structural (using X‐ray crystallography) motifs. Only a small number of porphyrin–actinide crystal structures have been reported in the literature, indicative of the inherent difficulty in synthesizing these kinds of complexes (as well as the precursors). These structures contain the expanded porphryins, characterized by a bigger core size to accommodate the actinide cations that are considerably larger in diameter than the more commonly used transition metals (Sessler et al., 2001a). Crystallographic studies of porphyrin‐ and polypyrrolic‐derived ligands with actinides have been limited to tetravalent, pentavalent, and hexavalent cations, including Th(IV), U(IV), Np(V), and U(VI). Table 22.27 lists representative structurally characterized actinide phthalocyanine/porphyrin complexes. The claimed ‘first’ structural determination of an actinide porphyrin complex was

Table 22.27 Phthalocyanine and porphyrin compounds of the actinides. Structure

References

phthalocyanines Th(phthalocyanine)2 U(phthalocyanine)2 U(diphthalocyanine)2I5/3 U(diphthalocyanine)2I2 UO2(superphthalocyanine)

Kobayashi (1978) Gieren and Hoppe (1971) Janczak and Kubiak (1999) Anczak et al. (2000) Day et al. (1975)

porphyrins Th(tetraphenylporphyrin)2 · C7H8 [Th(tetraphenylporphyrin)2][SbCl6] 2C7H8 · CH2Cl2 [Th(tetraphenylporphyrin)(OH)2]3 · 2H2O · 3C7H16 Th(octaethylporphyrin)2 Th(octaethylporphyrin)(acetylacetonate)2 U(tetraphenylporphyrin)Cl2(THF) UO2(pentaphyrin) UO2[hexaphyrin(1.0.1.0.0.0)] UO2(monooxasapphyrin) UO2(b‐methoxysapphyrin) UO2(grandephyrin) UO2(alaskaphyrin)(CHCl3)4 [HNEt3]NpO2[hexaphyrin(1.0.1.0.0.0)]

Girolami et al. (1988) Girolami et al. (1988) Kadish et al. (1988) Girolami et al. (1994) Dormond et al. (1986) Girolami et al. (1987) Burrell et al. (1991a) Sessler et al. (2001b) Sessler et al. (1998) Burrell et al. (1991b) Sessler et al. (2002) Sessler et al. (1992) Sessler et al. (2001b)

Coordination compounds

2465

for U(tpp)Cl2(THF) with U(IV) and doubly deprotonated tetraphenylporphyrin (tpp). X‐ray analysis indicates an exclusion complex, where the U(IV) rests ˚; above the plane of the porphyrin (defined by four nitrogen atoms) by 1.29 A the two chloride ions and a THF molecule are bound to the metal. The porphyrin itself is not rigorously planar, but rather ‘saucer‐shaped’ to promote bonding of the four nitrogens to uranium. Overall, the coordination geometry about uranium consists of what may be described as a 4:3 piano‐stool configuration, with the porphyrin comprising the base of the stool. The U–N bond ˚ , while the U–Cl and U–O bond distances are 2.63(1) and lengths are 2.41(1) A ˚ 2.50(1) A, respectively (Girolami et al., 1987). The structure of Th(octaethylporphyrin)(acetylacetonate)2, incidentally, was reported by Dormond et al. in 1986. The structure of UO2(pentaphyrin) contains an expanded pentadentate porphyrin that takes on a characteristic saddle‐shaped geometry with a uranyl ion located at the center. The uranyl ion is bound symmetrically through uranium to all five nitrogen atoms of the ligand, resulting in a nearly ideal, centrally coordinated pentagonal bipyramid, with U–N and U–O bond ˚ , respectively. Distortions from distances averaging 2.541(3) and 1.756(5) A planarity are due to the oversized diameter of the ligand cavity, thus yielding to the bonding requirements of the uranyl ion (Burrell et al., 1991a). þ The complexes of both UO2þ 2 and NpO2 with hexaphyrin(1.0.1.0.0.0) contain the ligand in its oxidized, aromatic form; the crystal structure of the latter is provided in Fig. 22.25. The linear uranyl ion is completely encapsulated within the porphyrin and is oriented perpendicularly to the plane of the six nitrogen atoms; each nitrogen participates in bonding to the uranium, resulting in a distorted hexagonal bipyramid due to non‐centered placement of uranium ˚ within the macrocycle cavity. The average U–N bond distance is 2.63(1) A (considerably longer than U–N distances observed in the former pentaphyrin ˚ (typical for the uranyl cation) structure) and U–O distances are 1.760(2) A (Sessler et al., 2001b). The analogous NpOþ 2 structure reveals less distortion in the ligand geometry as compared to the uranyl complex, presumably due to a better intrinsic ‘fit’ between the larger NpOþ 2 cation and the hexaaza ligand core. The geometry around the neptunium center, as in the uranium complex, is roughly a hexago˚ ] are nal bipyramid. The two Np–O bond distances [1.762(1) and 1.826(1) A ˚ in simple metal salts); the difference in length short for the NpOþ cation (1.85 A 2 of these bonds is presumably due to a short‐contact interaction between a triethylammonium cation nitrogen atom and a neptunyl oxygen atom. In ˚ , nearly 0.14 A ˚ longer than addition, Np–N bond distances average 2.77(2) A in the corresponding uranyl complex (Sessler et al., 2001b). Thorium–porphyrin compounds are also relatively common in the literature; for example, Th(IV) and octaethylporphyrin (oep) in the presence of acetylacetonate yield Th(oep)(acac)2. The geometry about the Th(IV) center in the crystal structure is described as a nearly ideal octa‐coordinated Archimedean antiprism

2466

Actinide structural chemistry

Fig. 22.25 Crystal strucuture of [HNEt3]NpO2[hexaphyrin(1.0.1.0.0.0)] with [HNEt3]þ and hydrogen atoms omitted (Sessler et al., 2001b). The coordinates were obtained from the Cambridge Structural Database (refcode QIVCON ).

provided by the four pyrrolic nitrogen atoms and the four oxygen atoms of the two acetylacetonato ligands. The Th(IV) ion is observed to rest closer to the acteylacetonato oxygen atoms than the nitrogen atoms of the porphyrin, making it an exclusion complex. The Th–N and Th–O bond distances average ˚ , respectively, and the geometry of the acetylacetonate ligand is 2.50 and 2.40 A consistent with known carboxylic acid complexes of related type (Dormond et al., 1986). The neutral Th(tetraphenylporphyrin)2 · C7H8 and its oxidized p‐radical cation in the form of [Th(tpp)2][SbCl6] are quite similar and have average Th–N ˚ , respectively. Both metal centers are bond distances of 2.55(1) and 2.52(2) A displaced from the mean plane formed by the pyrrolic nitrogen atoms with an ˚ for the neutral and 1.45 A ˚ for the average displacement distance of 1.47 A cation. The overall geometry around thorium in both the neutral and cationic species may be described as distorted square antiprismatic. Slight differences in the interplanar spacings and twists angles further distinguish the two (Girolami et al., 1988). Phthalocyanines are porphyrin‐like macrocycles (aza rather than methine bridge) and may be described as tetrabenzo‐tetraazaporphyrins that, unlike porphyrins, are typically prepared via a metal‐templated condensation using phthalonitrile and its derivatives (Sessler and Weghorn, 1997). The

Organoactinide compounds

2467

Fig. 22.26 Crystal strucuture of UO2(superphthalocyanine) with hydrogen atoms omitted (Day et al., 1975). The coordinates were obtained from the Cambridge Structural Database (refcode CIMINU10).

uranyl‐templated condensation reaction with o‐dicyanobenzene has yielded an expanded, cyclic five‐subunit complex with uranyl known as a ‘uranyl superphthalocyanine’ (Fig. 22.26). The crystal structure of the UO2(superphthalocyanine) complex reveals a linear uranyl ion pentacoordinated to the five nitrogen donors of the ligand, creating a near ideal compressed pentagonal bipyramid. The linear [179(1) ] uranyl fragment has an average U–O bond ˚ , consistent with other uranyl structures. The average distance of 1.744(8) A ˚ and is consistent with other seven‐coordinate U–N bond distance is 2.524(9) A uranyl/nitrogen complexes. A side‐profile of the complex reveals severe distortions from planarity, inherently due to steric strain within the ligand upon metal binding (Day et al., 1975).

22.5 ORGANOACTINIDE COMPOUNDS

Historically, organoactinide chemistry had its origins in the era of the Manhattan Project with unsuccessful attempts to synthesize volatile compounds such as tetraethyl uranium for isotopic enrichment in the gaseous diffusion operations. The synthesis of the unique sandwich compound, uranocene, in 1968, more than previous strides in actinide chemistry with cyclopentadienyl ligands, truly marked the beginning of the organoactinide era, evidenced by the exponential growth thereafter. The subsequent exploration

Actinide structural chemistry

2468

of organoactinide complexes has mainly focused on p‐electron interactions with the cyclopentadienyl and cyclooctatetraenyl ligands and their derivatives, resulting in complexes that take advantage of the potential for high coordination numbers as compared to d‐block elements. In addition to the p‐bonding ability of these ligands, coordinative saturation of the actinide center can be approached with a variety of other s‐ or p‐donating ligands (including halides, alkyls, and others), thus introducing a seemingly endless number of possibilities for studying coordination, ligand activation, or reactivity (Marks, 1982a). Organometallic complexes of lanthanide ions are largely ionic in nature, due to poor overlap between the 4f orbitals and ligand molecular orbitals. As a result, all the lanthanides favor the trivalent oxidation state and display similar chemical reactivity, with differences being primarily due to differences in ionic radii. The 5f electrons of the early actinides, however, are not completely shielded by the 6s and 6p electrons, resulting in a significant radial extension of the 5f orbitals that allows for overlap with ligand orbitals and a covalent bonding contribution. Despite this small covalent contribution, ionic character predominates; in fact, in the later actinides, contraction of the 5f orbitals due to increased nuclear charge results in less metal–ligand orbital overlap and in the predominance of the trivalent oxidation state (Bombieri et al., 1998). The interest surrounding organoactinide chemistry is based on the unique properties of actinide ions (e.g., larger size) that cause them to interact with ligands to produce chemistry that is wholly different from that observed with the d‐elements. The larger size of the actinide ions permits coordination numbers (as high as 12) and polyhedra that are unknown or highly unusual for d‐elements. This implies a greater control over coordinative unsaturation and a greater number of reactive species can be coordinated and maintained in spatially unusual orientations (Marks, 1982a). The tremendous growth of organoactinide chemistry since 1968 has resulted in the structural characterization of a wide range of complexes, far too many to be comprehensively presented in this section. The following sections present representative examples, primarily organized in a tabular form, that give the reader an idea of the classes of bonding, as well as the diversity and complexity of organoactinide structural chemistry with brief synopses of select complexes where appropriate. For a more comprehensive treatment of the chemistry and characterization of these compounds, the reader is referred to Chapter 25 of this work, or the annual lanthanide/actinide surveys that are listed in Table 22.28. 22.5.1

Cyclopentadienyl–actinide compounds

Organoactinide complexes of the cyclopentadienyl ligand (Z5‐C5H5 or Cp) commonly occur as An(Z5‐C5H5)4, An(Z5‐C5H5)3X, An(Z5‐C5H5)2X2, and An(Z5‐C5H5)X3 where X is a halogen atom, an alkyl, hydride, or alkoxy group, NCS, BH4, or other ligands with oxygen, nitrogen, or phosphorus donor sites of varying denticity. Typically, the aromatic nature of the Cp ring

Organoactinide compounds

2469

Table 22.28 Annual lanthanide and actinide organometallic surveys (1964–1998). Year

Reference

Year

References

1964–1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982

Hayes and Thomas (1971) Calderazzo (1973) Calderazzo (1974) Marks (1974) Marks (1975) Marks (1976) Marks (1977) Marks (1978) Marks (1979a) Marks (1980) Marks (1982b) Ernst and Marks (1987) Ernst (1990)

1983 1984–1986 1987–1990 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

Rogers and Rogers (1990) Rogers and Rogers (1991) Rogers and Rogers (1992a) Rogers and Rogers (1992b) Rogers and Rogers (1993) Kilimann and Edelmann (1995) Richter and Edelmann (1996) Gun’ko and Edelmann (1996) Edelmann and Gun’ko (1997) Edelmann and Lorenz (2000) Hyeon and Edelmann (2003a) Hyeon and Edelmann (2003b) Gottfriedsen and Edelmann (2005) Hyeon et al., (2005)

2000

Table 22.29 Representative tetrakis–cyclopentadienyl organoactinide complexes. Structure

References

Cp4An (An ¼ Th, U, Np) Cp4Th Cp4U

Kanellakopulos and Bagnall (1972) Maier et al. (1993) Burns (1974)

lends itself to a Z5 (pentahapto) bonding mode to the actinide metal via its p‐electrons. The following discussion will focus on structural motifs present in representative compounds of mono‐, bis‐, tris‐, and tetrakis‐cyclopentadienyl organoactinide complexes (Marks, 1979b). (a)

Tetrakis–cyclopentadienyl complexes

The Cp4An complexes, shown in Table 22.29, are very few in number and are prepared by heating AnCl4 with KCp. A single‐crystal X‐ray diffraction study of Cp4U revealed four identical Cp rings arranged in a tetrahedral fashion ˚ (Burns, around the uranium atom with an average U–C distance of 2.538 A 1974). The single‐crystal structure of Cp4Th is isostructural with the uranium ˚ (Maier et al., analog with a slightly longer average Th–C distance of 2.606 A 1993). The arrangement of Cp ligands around the thorium center is illustrated in Fig. 22.27. Furthermore, powder X‐ray diffraction techniques have confirmed the isostructural nature of the Th, U, and Np complexes (Kanellakopulos and Bagnall, 1972).

2470

Actinide structural chemistry

Fig. 22.27 Crystal strucuture of Cp4Th with hydrogen atoms omitted (Maier et al., 1993). The coordinates were obtained from the Cambridge Structural Database (refcode LANTEZ).

(b)

Tris‐cyclopentadienyl complexes

The tris‐cyclopentadienyl complexes of the actinides are known for Th, U, Pu, Am, Cm, Bk, and Cf, but not all have been structurally characterized. The uranium and thorium compounds can be prepared by different methods, including reduction of the tetravalent derivatives or photo‐induced b‐hydride elimination reactions of Cp3An–alkyl compounds (Bruno et al., 1982a). The thorium version is a unique example of thorium in the rare trivalent oxidation state and some structural data are available (Kanellakopulos et al., 1974). The uranium complex is a strong Lewis acid and readily favors the formation of adducts with a variety of Lewis bases (Marks, 1982a). Powder diffraction data are available for the Cm, Bk, and Cf compounds, evidence that the trivalent oxidation state is preferred for the heavier actinide elements (Cm, Bk, Cf ) (Laubereau and Burns, 1970a,b). The predominance of Cp3AnX compounds over Cp3An (where An is U or Th and X is an anion, Lewis base, or another Cp ring) in organoactinide chemistry depicts the degree to which the tetravalent oxidation state of the metal is preferred over the trivalent state in these complexes, or in cases where the trivalent oxidation state is maintained, the high Lewis acid character of the

Organoactinide compounds

2471

precursor (Bombieri et al., 1998). In all the Cp3AnX compounds, the Cp rings are bound in the traditional Z5 (pentahapto) mode to the actinide cation(s) and the complexes have irregular tetrahedral structure (although there are exceptions). Structural analysis has confirmed that this molecular arrangement exists for other complexes in which the X is varied, revealing not only the retention of the irregular tetrahedral structure, but also the aromatic nature of the Cp rings and the regularity of the An–C bond length. A series of tris‐cyclopentadienyl actinide complexes are tabularized in Table 22.30. The series of Cp3UX complexes, where X is a halide (F, Cl, Br, I), have been structurally characterized (Wong et al., 1965; Ryan et al., 1975; Spirlet et al., 1989; Rebizant et al., 1991). While each has the same distorted tetrahedral environment around the uranium center, none are isostructural, despite the chloride and bromide being geometrically equivalent (both monoclinic, P21/n). A neutron diffraction structure of the chloride is also available which shows disorder of the Cp rings as well as a crystallographic phase transition between 80 and 100 K (Delapalme et al., 1988). A structure of the iodide derivative is shown in Fig. 22.28. A large number of compounds exhibit s‐bonding at the fourth site, such as Cp3U(n‐C4H9), Cp3U(p‐CH2C6H4Me) (Perego et al., 1976), or Cp3U[MeC (CH2)2] (Halstead et al., 1975), with U—Cs bond distances of 2.426(23), ˚ , respectively. In the latter complex, while p‐bonding of 2.541(15), and 2.48(3) A the methylallyl group is possible, the structure clearly indicates s‐type interactions with the metal center. The result is a distorted tetrahedral geometry with approximate C3v symmetry. An interesting case exists with [Cp2Th(Z5:Z1‐ C5H4)]2, where the two Cp2Th centers are bridged by two Z5:Z1‐C5H4 ligands, each pentahapto to one thorium and monohapto (s‐bonded) to its neighbor (Baker et al., 1974). Another interesting situation arises in the pyrazolate complex, Cp3U (N2C3H3), where endo‐bidentate Z2‐coordination through both nitrogen atoms to the uranium center is observed; the U–N distances are 2.40 and 2.36 ˚ (Fig. 22.29). In this compound, the ionic nature of the U–N bond suggests A that the N–N bond is involved in a non‐directional association with the uranium atom; the resulting geometry may be described as a flattened tetrahedron with bonds joining the uranum atom with the center of the three Cp ligands and the midpoint of the N–N pyrazolate bond (Eigenbrot and Raymond, 1981). The reaction of Cp3U · THF with the potentially bidentate phosphine ligand, Me2P(CH2)2PMe2, yields the complex (Cp3U)2[Me2P(CH2)2PMe2] where the phosphine ligand adopts an unusual role (Zalkin et al., 1987a). Here, the phosphine acts as a bridging ligand between each Cp3U fragment rather that chelating in a bidentate mode through each phosphorus atom. In doing so, the steric repulsions are minimized and the coordination number of the uranium is reduced by one, resulting in an ‘economical arrangement’. The U–P bond dis˚ and the U–Cpcentroid distance is 2.52(1) A ˚ , both of which tance is 3.022(2) A

Table 22.30 Representative derivatives.

tris‐cyclopentadienyl

organoactinide

Structure

Non‐Cp Donors (# per center)

Cp Cp3Th Cp3An (An ¼ Cm, Bk, Cf)

– –

[(Cp3U)2(m‐H)][Na(THF)2] Cp3U(HBBN) Cp3U(BH4) Cp3UF Cp3UCl

H H(2) H(3) F Cl

(Cp3UClCp3)[Na(18‐crown‐6)(THF)2] Cp3UBr Cp3UI [Cp2Th(Z5:Z1‐C5H4)]2 Cp3U(CCH) Cp3U[CCPh] Cp3U(n‐C4H9) [Cp3U‐n‐C4H9][LiC14H28N2O4] Cp3U(p‐CH2C6H4Me) Cp3U[MeC(CH2)2] Cp3U(CHPMe2Ph) Cp3U(CHPMe3) Cp3U(CNC6H11)

Cl Br I C C C C C C C C C C

Cp2Cp*U(CH2Ph) Cp3U(NCR) (R ¼ nPr, iPr) Cp3UNPh2 Cp3U(NCS) Cp3UNC(Me)CHP(Me)(Ph)2 Cp3U(NPPh3) Cp3U(NCBH3)(NCMe) [Cp3U(NCMe)2]2[UO2Cl4] · (C4H6)2 [Cp3U(NCMe)2][CpThCl4(NCMe)] [Cp3U(NCMe)2][BPh4] Cp3U(NCS)(NCMe)

C N N N N N N(2) N(2) N(2); Cl(4), N N(2) N(2)

Cp3U(N2C3H3)

N(2)

[Ph4As][Cp3U(NCS)2] Cp3U(OR) (R ¼ C(CF3)2CCl3, Ph)

N(2) O

Cp3U(THF) Cp3U(OSiPh3) Cp3Np(OPh) (Cp3U)2(Me2P(CH2)2PMe2) Cp3U(SMe)

O O O P S

complexes

and

References Kanellakopulos et al. (1974) Laubereau and Burns (1970a,b) Le Mare´chal et al. (1989a) Zanella et al. (1987b) Zanella et al. (1988) Ryan et al. (1975) Wong et al. (1965); Delapalme et al. (1988) Le Mare´chal et al. (1989b) Spirlet et al. (1989) Rebizant et al. (1991) Baker et al. (1974) Atwood et al. (1976) Atwood et al. (1973) Perego et al. (1976) Arnaudet et al. (1986) Perego et al. (1976) Halstead et al. (1975) Cramer et al. (1981, 1983) Cramer et al. (1988a) Kanellakopulos and Aderhold (1973) Kiplinger et al. (2002a) Adam et al. (1993) Cramer et al. (1987a) Spirlet et al. (1993a) Cramer et al. (1984a) Cramer et al. (1988b) Adam et al. (1990) Bombieri et al. (1983a) Rebizant et al. (1987) Aslan et al. (1988) Aslan et al. (1988); Fischer et al. (1978) Eigenbrot and Raymond (1981) Bombieri et al. (1983b) Kno¨sel et al. (1987); Spirlet et al. (1990a) Wasserman et al. (1983) Porchia et al. (1989) De Ridder et al. (1996a) Zalkin et al. (1987a) Leverd et al. (1996)

Table 22.30 (Contd.)

Structure

Non‐Cp Donors (# per center)

References

Cp Cp3U[Z2‐MeC¼N(C6H11)] Cp3U[(Net2)C¼N(C6H3Me2–2,6)] Cp3U(NPh)(O)CCHPMe2Ph Cp3U(Z2‐OCCH)P(Me)(Ph)2

C, N C, N O, N C, O

Zanella et al. (1985) Zanella et al. (1987a) Cramer et al. (1987b) Cramer et al. (1982)

Cp* (Cp*)3ThH (Cp*)3UX (X ¼ F, Cl) (Cp*)3U(CO) (Cp*)3U(Z1‐N2)

H F; Cl C N

Evans et al. (2001) Evans et al. (2000) Evans et al. (2003a) Evans et al. (2003b)

MeCp, Me4Cp, PhCH2Cp (Me4Cp)3UCl (PhCH2Cp)3UCl (Me4Cp)3U(CO) (MeCp)3U(NH3) (MeCp)3U(NPh)

Cl Cl C N N

(MeCp)3U[N(CH2CH2)3CH] (MeCp)3U(C7H10N2) (MeCp)3U(OPPh3) [(MeCp)3U]2[m‐Z1,Z2‐PhNCO]

N N O O; C, N

(MeCp)3U(PMe3) (MeCp)3U[P(OCH2)3CEt] (MeCp)3U(C4H8S) [(MeCp)3U]2[m‐S] [(MeCp)3U]2[m‐Z1,Z2‐CS2]

P P S S S; C, S

Cloke et al. (1994) Leong et al. (1973) Parry et al. (1995) Rosen and Zalkin (1989) Brennan and Andersen (1985) Brennan et al. (1988a) Zalkin and Brennan (1987) Brennan et al. (1986b) Brennan and Andersen (1985) Brennan and Zalkin (1985) Brennan et al. (1988a) Zalkin and Brennan (1985) Brennan et al. (1986b) Brennan et al. (1986a)

Cp0 , Cp00 , Cptt, (SiMe3)2CHCp (Cp00 )3Th (Cptt)3Th (Cp0 )3U (Cp00 )3ThCl (Cptt)3ThCl (Cp00 )2(Cp*)ThCl [(SiMe3)2CHCp]3ThCl (Cp00 )3UCl (Cp0 )3UCH¼CH2 [Na(18‐crown‐6)][(Cp0 )3U‐N3‐U(Cp0 )3] [(Cp0 )3U]2[m‐O]

– – – Cl Cl Cl Cl Cl C N O

Blake et al. (1986a, 2001) Blake et al. (2001) Zalkin et al. (1988a) Blake et al. (1998) Blake et al. (1998) Blake et al. (1998) Blake et al. (1998) Blake et al. (1998) Schock et al. (1988) Berthet et al. (1991a) Berthet et al. (1991b)

* Semicolons used to differentiate coordination to different metal centers or different structures.

2474

Actinide structural chemistry

Fig. 22.28 Crystal strucuture of Cp3UI with hydrogen atoms omitted (Rebizant et al., 1991). The coordinates were obtained from the Cambridge Structural Database (refcode JIKGOZ).

Fig. 22.29 Crystal strucuture of Cp3U(N2C3H3) with hydrogen atoms omitted (Eigenbrot and Raymond, 1981). The coordinates were obtained from the Cambridge Structural Database (refcode CPYRZU).

Organoactinide compounds

2475

are comparable to the distances observed in the (MeCp)3U(PMe3) complex of ˚ , respectively (Brennan and Zalkin, 1985). 2.972(6) and 2.52(1) A Several novel tris‐cyclopentadienyl complexes have also been studied structurally. In the anionic portion of [Ph4As][Cp3U(NCS)2], the uranium center is surrounded by a trigonal planar arrangement of Cp ligands in the equatorial plane, and the thiocyanate ligands occupy axial positions with U–N bond ˚ (Bombieri et al., 1983a). The first example of the distances of 2.46 and 2.50 A opposite situation, a cationic organoactinide species, was observed in [Cp3U (NCMe)2]2[UO2Cl4] (C4H6)2, formed from the reaction of Cp3UCl in MeCN with gaseous butadiene and traces of O2 (Fig. 22.30). The cation contains uranium in the tetravalent oxidation state with trigonal bipyramidal geometry (D3h), while the anion has hexavalent uranium with approximate D2h symmetry (Bombieri et al., 1983b). Another cationic organoactinide species is evident in [Cp3U(NCMe)2][CpThCl4(NCMe)] with the familiar trigonal bipyramidal geometry. An interesting aspect of this structure is the simultaneous presence of tetravalent thorium in the anion with octahedral coordination (Rebizant et al., 1987). In the compound Cp3U(NPh)(O)CCHPMe2Ph, Z2 coordination of the oxygen and nitrogen atoms of the neutral ligand creates a four‐membered ring. The ˚ , respectively, indicating U–N and U–O bond lengths are 2.45(1) and 2.34(1) A the presence of single bonds which are typical for donor atoms carrying a partial negative charge. Due to the sterically crowded nature of the uranium center, the formation of this cis‐Cp3UXY‐type compound is quite rare; its highly crowded ˚ ), elongated U–CCp nature is evident in the small ligand bite distance (2.22(2) A ˚ vs 2.72 A ˚ for Cp3UBr), and compressed Cpcentroid–U– bonds (average 2.84(2) A Cpcentroid angles (Cramer et al., 1987b). A rare instance of a neptunium‐containing organometallic complex (with tetravalent neptunium) is Cp3Np(OPh). Considering the oxygen atom and the centers of the three Cp ligands as vertices, the structure has flattened tetrahedral geometry and near C3v symmetry (De Ridder et al., 1996a). The Np–O bond

Fig. 22.30 Crystal strucuture [Cp3U(NCMe)2]2[UO2Cl4] · (C4H6)2 with (C4H6) and hydrogen atoms omitted (Bombieri et al., 1983b). The coordinates were obtained from the Cambridge Structural Database (refcode BUJPOL).

2476

Actinide structural chemistry

˚ , considerably shorter than that in CpNpCl3(OPMePh2)2 distance is 2.136(7) A ˚ of 2.277(6) A (Bagnall et al., 1986). Cp3Np(OPh) is isostructural with its uranium analog Cp3U(OPh); the U–O bond distance is slightly shorter, howev˚ , and the flattened tetrahedral geometry is maintained (Spirlet er, at 2.119(7) A et al., 1990a). The structure of [(MeCp)3U]2[m‐S] shows sulfur occupying a bridging role ˚, between two (MeCp)3U moieties, with an average U–S distance of 2.60(1) A one of the shortest ever observed. The most interesting aspect of this structure is the bent U–S–U angle of 164.9(4) . These observed structural features are consistent with a class of bridging sulfur transition metal complexes with nearly linear M–S–M angles (159–180 ) and M–S bond lengths shorter than expected for a M–S single bond. This trend suggests that the bridging sulfur may act as a p‐donor or p‐acceptor towards the metal center; an alternative explanation, however, is an electrostatic one, where steric repulsion due to the bulky (MeCp)3U groups accounts for the observed structural features (Brennan et al., 1986b). The first example of end‐on binding of N2 has been observed in the structure of (Cp*)3U(Z1–N2). A solution of (Cp*)3U under N2 at 80 psi darkens with the precipitation of hexagonal crystals of the desired compound. Binding is reversible, with quantitative regeneration of (Cp*)3U upon lowering the pressure to 1 atm. The three Cp* ligands are bound pentahapto to the uranium center, with the remaining coordination site filled by N2, resulting in a trigonal pyramidal ˚ is geometry (Evans et al., 2003b). The U–N bond distance of 2.492(10) A ˚ U–CCO distance observed in (Cp*)3U(CO). comparable to the 2.485(9) A Here, the CO ligand is isoelectronic with N2 and also binds end‐on to the uranium center through carbon (Evans et al., 2003a). The isostructural nature of the two compounds is illustrated in Fig. 22.31. (c)

Bis‐cyclopentadienyl complexes

Like the tris‐compounds, the prevalance of Cp2(Th,U)X2 compounds over Cp2(Th,U)X compounds reveals the large preference for the tetravalent oxidation state in these complexes. However, the Cp2(Th,U)X2 are considerably unstable compared to transition metal and lanthanide analogs towards intermolecular ligand redistribution (Bombieri et al., 1998). For example, Cp2UCl2, produced by the reaction of TlCp and UCl4 in the presence of 1,2‐dimethoxyethane (DME), is actually a mixture of Cp3UCl and CpUCl3(DME) (Ernst et al., 1979). The pentamethylcyclopentadienyl ligand (Cp*) has been utilized in organoactinide chemistry to circumvent many of the problems encountered with the unstable Cp2(Th,U)X2 compounds. As compared to the unsubstituted analog (Cp), Cp* provides increased covalent character of the Cp–M bond, stronger p‐ donor ability, kinetic stabilization due to steric shielding of the metal, and increased thermal stability. In addition to inhibiting the formation of polymeric structures, the Cp* improves many solution chemistry properties, including

Organoactinide compounds

2477

Fig. 22.31 Crystal strucutures of (Cp*)3U(CO) (Evans et al., 2003a) and (Cp*)3U(
1‐N2) (Evans et al., 2003b) with hydrogen atoms omitted. The coordinates were obtained from the Cambridge Structural Database (refcodes IMUVAN and ENABUQ).

crystallizability, thus promoting its widespread use in organoactinide chemistry (Bombieri et al., 1998). The addition of methyl groups to the Cp rings promotes coordinative unsaturation of the actinide metal by preventing the binding of other sterically demanding ligands. In addition, the methyl groups stabilize the organoactinide complexes with respect to ligand redistribution reactions, a feature that dominates the solution chemistry of unsubstituted f‐element metallocenes. Ligand rearrangement prevents the cystallization of the Cp2UCl2 and (Cp*)(Cp)UCl2, as well as [(tBu)Cp]2UCl2 and (Cp0 )2UCl2 (Lukens et al., 1999). In contrast, the (Cp*)2UCl2 complex (Fig. 22.32) has normal, monomeric pseudotetrahedral ‘bent‐sandwich’ configuration and has no tendency to undergo ligand redistribution to form the unknown (Cp*)3UCl (Spirlet et al., 1992a). A large number of representative bis‐cyclopentadienyl actinide complexes are listed in Table 22.31, again illustrating the magnitude and diversity of organoactinide structural chemistry. The list is dominated by Cp* ligands (and other Cp derivative with bulky substituents), a tribute to its prevalence in organometallic chemistry and its usefulness in preventing ligand redistribution. The series of compounds Cp2ThX2(Me2P(CH2)2PMe2), where X ¼ Cl, Me, or CH2C6H5, have been synthesized and structurally characterized. The chloro derivative (Fig. 22.33) was synthesized from the reaction of sodium cyclopentadienide with ThCl4 (CH3)2PCH2CH2P(CH3)2 in THF at 203 K. The latter two derivatives were synthesized from the reaction of the chloro derivative with methyllithium and benzyllithium, respectively, at 228 K. In accordance with Keppert’s rules, the monodentate ligand with the shortest bond distance in each

2478

Actinide structural chemistry

Fig. 22.32 Crystal strucutures of (Cp*)2ThCl2 and (Cp*)2UCl2 with hydrogen atoms omitted (Spirlet et al., 1992a). The coordinates were obtained from the Cambridge Structural Database (refcodes VUJRAT and VUJPUL).

structure (the Th–Cpcentroid bond) occupies the site trans to the bidentate Me2P (CH2)2PMe2 ligand, thus making the bulky Cp ligands cis to one another. This is, in many ways, counter‐intuitive in that the bulky Cp ligands should prefer a trans configuration to each other to lessen steric hindrance. The average Th–P bond lengths in the above three compounds are 3.147(1), 3.121(1), and 3.19(3) ˚ , respectively (Zalkin et al., 1987b,c). A The compounds (Cp*)2UCl2(C3H4N2), (Cp*)2UCl(C3H3N2), and (Cp*)2U (C3H3N2)2 exhibit two bonding modes for the pyrazole/pyrazolate ligand. In the first compound, the pyrazole ligand acts as a neutral donor, with donation to the uranium center occurring through only a single nitrogen atom. In the latter two complexes, the pyrazole ligand is in the form of the pyrazolate anion and donates two nitrogen atoms per ligand to the uranium center. In the mono‐chloro complex, the geometry can be approximated as tetrahedral by considering the two Cp* centroids, the chloride, and the midpoint of the N–N bond as corners. The U–N nitrogen bond length trend is supported ˚ average) by the nature of the ligand: the longest U–N bonds (2.607(8) A occur for the neutral pyrazole ligand, while the anionic ligand yields the shortest U–N bonds. In the monopyrazolate complex, the two U–N ˚ , while the dipyrazolate distances are bond lengths are 2.351(5) and 2.349(5) A ˚ . Interestingly, in the latter case, 2.403(4), 2.360(5), 2.363(9), and 2.405(5) A the two ‘internal’ U–N bonds are shorter (greater crowding) than the two ‘external’ bonds. The pyrazolate U–N bond lengths are consistent ˚ ) (Eigenbrot and Raymond, with the Cp3U(N2C3H3) structure (1.36, 1.40 A 1982).

Table 22.31 Representative derivatives.

bis‐cyclopentadienyl

Structure Cp Cp2U(BH4)2 [{Cp2U(m‐Cl)}3(m3‐Cl)2][{CpUCl2}2 (m‐Cl)3] · 2(CH2Cl2) Cp2ThX2(Me2P(CH2)2PMe2) (X ¼ Me, Cl, CH2C6H5) [Cp2U(m‐CH)(CH2)P(Ph)2]2 · (C2H5)2O M‐[Cp2U(m‐S‐CH)(CH2)P(Ph)2]2 · C5H12 Cp2Th[(CH2)(CH2)PPh2]2

organoactinide

complexes

and

Non‐Cp donors (# per center)

References

H(6) Cl(4); Cl(5)

Zanella et al. (1977) Arliguie et al. (1994a)

C(2), P(2); Cl(2), P(2) C(3)

Zalkin et al. (1987b,c)

C(3) C(4)

Cp* [(Cp*)2Th(H)(m‐H)]2 [K(18‐crown‐6)][(Cp*)2U(Cl)H6 Re(PPh3)2] · 0.5(C6H6) (Cp*)2U(H)(Me2P(CH2)2PMe2) (Cp*)2MCl2 (M ¼ Th, U) [(Cp*)2U(m‐Cl)]3 [Li(TMED)][(Cp*)2UCl(NC6H5)] (Cp*)2Th(Cl)(HNC(Me)NC(Me)CHCN) (Cp*)2UCl(Z2‐(N,N0 )‐MeNN¼CPh2) (Cp*)2UCl2(C3H3N2)

H, P(2) Cl(2) Cl(2) Cl, N Cl, N(2) Cl, N(2) Cl, N(2)

(Cp*)2UCl2(C3H4N2)

Cl(2), N

(Cp*)2UCl2(HNPPh3) (Cp*)2UCl2(HNSPh2) (Cp*)2ThCl[O2C2(CH2CMe3)(PMe3)] [(Cp*)2ThCl{m‐CO(CH2CMe3)CO}]2 (Cp*)2ThCl[Z2‐COCH2CMe3] (Cp*)2ThBr2(THF) [(Cp*)2Th(Me)][B(C6F5)4] (Cp*)2Th[(CH2)2SiMe2] (Cp*)2Th(CH2SiMe3)2 (Cp*)2Th(CH2CMe3)2 (Cp*)2Th(Z4‐C4H6) [(Cp*)2Th(Me)(THF)2][BPh4] [(Cp*)2U(Me)(OTf )]2 (Cp*)2U(N‐2,4,6‐tBu3C6H2) (Cp*)2U(NC6H5)2 (Cp*)2U[NH(C6H3Me2–2,6)]2 (Cp*)2U(NCPh2)2 (Cp*)2U(NSPh2)2 (Cp*)2U(C3H3N2)2

Cl(2), N Cl(2), N Cl, O(2) Cl, O(2) Cl, C, O Br(2), O C C(2) C(2) C(2) C(4) C, O(2) C, O(2) N N(2) N(2) N(2) N(2) N(4)

[(Cp*)2Th(m‐O2C2Me2)]2

O(2)

H(3) H(3), Cl

Cramer et al. (1978, 1980) Cramer et al. (1980) Cramer et al. (1995a) Broach et al. (1979) Cendrowski‐Guillaume et al. (1994) Duttera et al. (1982) Spirlet et al. (1992a) Manriquez et al. (1979) Arney and Burns (1995) Sternal et al. (1987) Kiplinger et al. (2002b) Eigenbrot and Raymond (1982) Eigenbrot and Raymond (1982) Cramer et al. (1989) Cramer et al. (1995b) Moloy et al. (1983) Fagan et al. (1980) Fagan et al. (1980) Edelman et al. (1995) Yang et al. (1991) Bruno et al. (1982b) Bruno et al. (1983) Bruno et al. (1986) Smith et al. (1986) Lin et al. (1987) Kiplinger et al. (2002b) Arney and Burns (1995) Arney et al. (1992) Straub et al. (1996) Kiplinger et al. (2002c) Ariyaratne et al. (2002) Eigenbrot and Raymond (1982) Manriquez et al. (1978)

Table 22.31 (Contd.)

Structure Cp* (Cp*)2U(Z2‐(N,N’)‐MeNN¼ CPh2)(OTf ) [(Cp*)2U(OMe)]2(m‐PH) (Cp*)2Th(PPh2)2

Non‐Cp donors (# per center)

References

S(2) S(2) S(2)

Kiplinger et al. (2002b) Duttera et al. (1984) Wrobleski et al. (1986a) Lescop et al. (1999) Lin et al. (1988) Ventelon et al. (1999)

S(3) S(4)

Lescop et al. (1999) Wrobleski et al. (1986b)

N(2)

Brennan et al. (1988b)

Cp0 , Cp00 , Cptt, (tBu)2Cp (Cp00 )2UX2 (X ¼ BH4, Cl, OAr)

H(6); Cl(2); O(2)

(Cp00 )2UX2 (X ¼ BH4, Br, I) [(tBu)2Cp]2UX2 (X ¼ F, Cl) [(Cp00 )2UF(m‐F)]2 [(Cp00 )2U(m‐BF4)(m‐F)]2 (Cp00 )2MCl2 (M ¼ Th, U) (Cp00 )2U(m‐Cl)2Li(PMDETA) (Cp00 )2U(m‐Cl)2Li(THF)2 [PPh4][(Cp00 )2UCl2] [{(tBu)2Cp}2U]2(m‐Cl)2 [(Cp00 )2U(m‐X)]2 (X ¼ Cl, Br) (Cp00 )2UX2 (X ¼ Cl, Me) [(Cptt)2Th(Cl){CH(SiMe3)2}] (Cp00 )2UCl[CN(C6H3Me2)]2

H(6); Br(2); I(2) F(2); Cl(2) F(3) F(4) Cl(2) Cl(2) Cl(2) Cl(2) Cl(2) Cl(2); Br(2) Cl(2); C(2) Cl, C Cl, C(2)

(Cp00 )2UCl(NCSiMe3)2

Cl, N(2)

[(tBu)2Cp]2Th(m,Z3‐P3)Th(Cl) [(tBu)2Cp]2 (Cp00 )2UBr(CNtBu)2

Cl, P(3)

Hunter and Atwood (1984) Blake et al. (1995) Lukens et al. (1999) Lukens et al. (1999) Hitchcock et al. (1984) Blake et al. (1995) Blake et al. (1988a) Blake et al. (1988b) Blake et al. (1988a) Zalkin et al. (1988b) Blake et al. (1986b) Lukens et al. (1999) Edelman et al. (1995) Zalkin and Beshouri (1989a) Zalkin and Beshouri (1989b) Scherer et al. (1991)

[(Cp0 )2U(m‐O)]3 [(Cp00 )2U(m‐O)]2

O(2) O(2)

[(tBu)2Cp]2Th(m,Z3,Z3‐P6) Th[(tBu)2Cp]2 [(tBu)2Cp]2Th(m,Z2:1:2:1‐As6) Th[(tBu)2Cp]2

P(3)

Beshouri and Zalkin (1989) Berthet et al. (1993) Zalkin and Beshouri (1988) Scherer et al. (1991)

As(3)

Scherer et al. (1994)

(Cp*)2U(SMe)2 (Cp*)2Th[S(CH2)2Me]2 [Na(18‐crown‐6)][(Cp*)2 U(StBu)(S)] (Cp*)2U(StBu)(S2CStBu) (Cp*)2ThS5 MeCp [(MeCp)2U]2(m‐NR)2 (R ¼ Ph, SiMe3)

O, N(2) O, P P(2)

Br, C(2)

* Semicolons used to differentiate coordination to different metal centers or different structures.

Organoactinide compounds

2481

Fig. 22.33 Crystal strucuture of Cp2ThCl2(Me2P(CH2)2PMe2) with hydrogen atoms omitted (Zalkin et al., 1987b). The coordinates were obtained from the Cambridge Structural Database (refcode BIXVOT10).

The first example of an organoactinide polysulfide reveals the unique twist‐ boat conformation of a ThS5 ring, generated by the reaction of (Cp*)2ThCl2 with Li2S5. The crystal structure of (Cp*)2ThS5 (Fig. 22.34) is unique compared to transition metal analogs, such as Cp2TiS5, Cp2ZrS5, and Cp2HfS5, which strictly exhibit a MS5 chair conformation. This anomaly in conformation is likely due to the coordination of four ring sulfur atoms to the uranium center, rather than two. Two types of bonding are thought to occur: two Th–S bonds at ˚ are ionic in nature and two at 3.036(3) A ˚ are dative in nature 2.768(4) A (Wrobleski et al., 1986b). Many polynuclear bis‐organoactinide complexes with bridging hydride, halide, and oxo groups are known. For example, the single‐crystal neutron diffraction structure of the dimeric compound [(Cp*)2Th(H)(m‐H)]2, one of the first examples of an actinide hydride complex, contains both bridging and terminal hydrides. Two (Cp*)2Th(H) moieties, each containing a terminal hydride, are connected by two bridging hydrides; the terminal and bridging ˚ , respectively, with a Th–Th separation Th–H distances are 2.03(1) and 2.29(3) A ˚ (Broach et al., 1979). of 4.007(8) A The trimeric bridging halide complex, [(Cp*)2U(m‐Cl)]3, contains three (Cp*)2U units, each connected by a bridging chloride and pseudotetrahedral

2482

Actinide structural chemistry

Fig. 22.34 Crystal strucuture of (Cp*)2ThS5 with hydrogen atoms omitted (Wrobleski et al., 1986b). The coordinates were obtained from the Cambridge Structural Database (refcode DIJRET).

geometry around each uranium. The cyclic –U–Cl–U–Cl–U–Cl– moiety comprises a nearly planar six‐membered ring, with average U–Cl, U–C, and U–U ˚ , respectively (Manriquez et al., distances of 2.901(5), 2.76(3), and 5.669(2) A 1979). Finally, the bridging oxo complex, [(Cp00 )2U(m‐O)]2, contains two (Cp00 )2U units connected by two bridging oxo ligands and a geometry similar to the chloro complex (Fig. 22.35). The average U–O and U–C distances are ˚ , respectively. The average U–Cpcentroid distance is 2.496 2.213(8) and 2.77(4) A ˚ (Zalkin and Beshouri, 1988). For further examples of bridging complexes, the A reader is referred to Table 22.31. (d)

Mono‐cyclopentadienyl complexes

Mono‐cyclopentadienyl organoactinide complexes, while less common, are typically Lewis‐base adducts of the type CpAnX3Ln. These complexes are usually sterically and electronically unsaturated, making their synthesis and subsequent crystallization quite challenging. Representative complexes for which structural data are available are listed in Table 22.32. The structures of

Organoactinide compounds

2483

Fig. 22.35 Crystal strucuture of [(Cp00 )2U(m‐O)]2 with hydrogen atoms omitted (Zalkin and Beshouri, 1988). The coordinates were obtained from the Cambridge Structural Database (refcode GIFNIS).

CpUCl3(OPPh3)2 · THF (Bombieri et al., 1978c; Bagnall et al., 1984) and CpUCl3[OP(NMe2)3]2 (Bagnall et al., 1984) show an octahedral environment around the uranium centers with the neutral ligands occupying the cis coordination sites. In addition, the chlorine ligands are arranged in a mer fashion (as opposed to a fac arrangement) and the Cp ligands are trans to one of the neutral ligands. One of the few neptunium‐containing organoactinide complexes, CpNpCl3(OPMePh2)2, is analogous to the uranium structures described above (Fig. 22.36) (Bagnall et al., 1986). The compound [CpU(CH3COO)2]4O2 has four seven‐coordinate uranium centers, each with distorted pentagonal bipyramidal geometry. The pentagonal arrangement around a given uranium center is defined by five oxygen atoms from four different acetate ligands. Two bridging acetates are monodentate simultaneously with respect to two neighboring uranium atoms. The remaining two bridging acetate groups take on a more complex role, each joining two neighboring uranium centers, with one oxygen being mondentate toward one uranium and the other oxygen being bidentate toward both uranium atoms. The remaining coordination sites are occupied by bridging oxo ligands ( joining two pairs of uranium atoms), providing the apex of each pentagonal bipyramid,

2484

Actinide structural chemistry

Table 22.32 Representative mono‐cyclopentadienyl organoactinide complexes.

Structure

Non‐Cp donors (# per center)

Cp CpU(BH4)3 [CpTh2(O‐iPr)7]3 CpUCl(acac)2(OPPh3) CpUCl3(OPPh3)2 · THF

H(9) O(5) Cl, O(5) Cl(3), O(2)

CpUCl3[OP(NMe2)3]2 CpNpCl3(OPMePh2)2 CpU[(CH2)(CH2)PPh2]3 [Cp(CH3COO)5U2O]2 [CpU(CH3COO)2]4O2

Cl(3), O(2) Cl(3), O(2) C(6) O(6) O(6)

Baudry et al. (1989a) Barnhart et al. (1995b) Baudin et al. (1988) Bombieri et al. (1978c); Bagnall et al. (1984) Bagnall et al. (1984) Bagnall et al. (1986) Cramer et al. (1984b) Brianese et al. (1989) Rebizant et al. (1992)

H(9) Cl, N, O(3)

Ryan et al. (1989) Cramer et al. (1995b)

I(2), O(3) I(2), N(3) C(6) C(9) C, N, O(3); N, O(3)

Avens et al. (2000) Avens et al. (2000) Kiplinger et al. (2002a) Cymbaluk et al. (1983) Butcher et al. (1995)

N(2) N(2), O(2)

Avens et al. (2000) Berthet et al. (1995)

Cl(5) Cl(4), O(1) Cl(3), O(2)

Edelman et al. (1995) Edelman et al. (1987) Ernst et al. (1979)

Cp* [Na(THF)6][Cp*U(BH4)3]2 [Cp*(Cl)(HNSPh2)U(m3‐O) (m2‐O)U(Cl)(HNSPh2)]2 Cp*UI2(THF)3 Cp*UI2(pyr)3 Cp*U(CH2Ph)3 Cp*U(Z3‐2‐MeC3H4)3 Cp*[(Me3Si)2N]Th(m2‐OSO2CF3)3 Th[N(SiMe3)(SiMe2CH2)]Cp* Cp*U[N(SiMe3)2]2 [Cp*U(NEt2)2(THF)2]BPh4 Cp000 , MeCp [(Cp000 ThCl3)2NaCl(OEt2)]2 Cp000 UCl2(THF)(m‐Cl)2[Li(THF)2] (MeCp)UCl3(THF)2

References

* Semicolons used to differentiate coordination to different metal centers or different structures.

and each pentahapto Cp ligand occupies the remaining apex (Rebizant et al., 1992). A cyclic hexameric thorium organoactinide complex (Fig. 22.37) is evident in the structure of [CpTh2(O–iPr)7]3. Interestingly, the Cp ligands in this structure take on a bridging role between three [Th2(O–iPr)7] units, each pentahapto to its neighboring thorium atoms. Each thorium center has distorted octahedral geometry provided by a Cp ligand and five O–iPr groups, two of which are bound to a thorium atom and the remaining three bridge between two thorium atoms (Barnhart et al., 1995b). The two thorium atoms in the triflate‐bridged compound isolated by Butcher et al. (1995) have different coordination numbers (Fig. 22.38). Each thorium atom has one Cp* ligand bound in a pentahapto fashion and the two centers are

Organoactinide compounds

2485

Fig. 22.36 Crystal strucuture of CpNpCl3(PMePh2O)2 with hydrogen atoms omitted (Bagnall et al., 1986). The coordinates were obtained from the Cambridge Structural Database (refcode DIXCOC).

joined by three bridging triflate ligands. One thorium center is coordinated to a cyclometalated amide ligand in a bidenate manner through both nitrogen, and interestingly, carbon, resulting in a hexacoordinate thorium atom (Th–N¼ ˚ , Th–C¼2.43(5) A ˚ ). The remaining thorium center has a bis‐(tri2.26(4) A methylsilyl)amide ligand bound in a monodentate fashion only through the ˚ ), resulting in pentacoordinate thorium. nitrogen atom (Th–N¼2.24(3) A 22.5.2

Cyclooctatetraene–actinide compounds

A milestone in the field of organometallics that effectively marked the beginning of organoactinide chemistry was the synthesis (Streitweiser and Mu¨ller‐ Westerhoff, 1968) and subsequent structural characterization of uranocene. The pursuit of uranocene was a direct result of the idea that it would be analogous to ferrocene with the additional benefit of studying the contribution of f‐orbitals to the bonding. Like ferrocene, uranocene is a sandwich complex of D8h symmetry in which the uranium(IV) ion is positioned between two octahapto (Z8‐C8H8) cyclooctatetraene (COT) dianions. Although eclipsed in

2486

Actinide structural chemistry

Fig. 22.37 Crystal strucuture of [CpTh2(O‐iPr)7]3 with hydrogen atoms omitted (Barnhart et al., 1995b). The coordinates were obtained from the Cambridge Structural Database (refcode ZEJYES).

uranocene, the COT rings have the potential of being either eclipsed or staggered (Zalkin and Raymond, 1969; Avdeef et al., 1972). The thorium analog of uranocene, commonly referred to as thorocene, is isostructural, and both are extremely air‐sensitive (Avdeef et al., 1972). Both structures consist of the central metal atom participating in symmetrical p‐bonding to the COT ligands, related by a crystallographic inversion center. The average Th–C and U–C bond ˚ , respectively; the corresponding metal‐to‐ distances are 2.701(4) and 2.647(4) A ˚ . Spectroscopic studies with uranocene centroid distances are 2.004 and 1.924 A seem to indicate at least some p‐interactions between the molecular orbitals of the COT ligands and the 5f orbitals of the metal. Neptunocene, a transuranic metallocene, is isostructural with both thorocene ˚ (De Ridder and uranocene, with an average Np–C bond distance of 3.630(3) A et al., 1996b). Powder diffraction data are available for both (COT)2Pa and (COT)2Pu that indicate protactinocene is isostructural with the lower actinide analogs and plutonocene is isomorphous with the series (Karraker et al., 1970; Starks et al., 1974). Incorporation of the COT ligand is not limited to metallocenes. In fact, a host of other examples containing COT are listed in Table 22.33.

Organoactinide compounds

2487

Fig. 22.38 Crystal strucuture of Cp*[(Me3Si)2N]Th(m2‐OSO2CF3)3Th[N(SiMe3) (SiMe2CH2)]Cp* with hydrogen atoms omitted (Butcher et al., 1995). The coordinates were obtained from the Cambridge Structural Database (refcode ZANJIH).

A mixed cyclopentadiene/cyclooctatetraene complex is observed in the crystal structure of (COT)(Cp*)U(Me2bpy) (Schake et al., 1993). The binding of the COT and Cp* rings are Z8 and Z5, respectively, and the bipyridine adduct is bidentate through both nitrogen atoms. The resulting geometry around the uranium is a distorted tetrahedron with a Cp*–U–COT bond angle (from centroids of ligands) of 138.2 , comparable to what is observed in the thorium complexes, (COT)Cp*Th[CH(SiMe3)2] and (COT)Th(Cp*)(m‐Cl)2Mg(CH2tBu) (THF) 0.5PhMe (Gilbert et al., 1989). Butenouranocene, [C8H6(CH2)2]2U, contains a cyclooctatetraene derivative appended with a cyclobuteno ring (Fig. 22.39). The uranium ion is sandwiched between the two eclipsed rings, but centered on the cyclooctatetraene rings, with ˚ (Zalkin et al., an overall C2h symmetry. The average U–C distance of 2.64(2) A ˚ ) and similar structures. 1979) is comparable to uranocene (2.65 A 22.5.3

Other (indenyl, arene, etc.) compounds

Representative organoactinide complexes containing ligands not covered in previous sections are listed in Table 22.34 and include various indenyl, arene, and miscellaneous structures, including bridged Cp ligands. The indenyl ligand,  C 9 H 7 , is formally analogous to C5 H5 , yet is more sterically demanding (both substituted and unsubstituted) and can coordinate in pentahapto, trihapto, and monohapto modes (Bombieri et al., 1998).

Actinide structural chemistry

2488

Table 22.33 Representative cyclooctatetraenyl organoactinide complexes.

Structure

Non‐Cp donors (# per center)

(COT)2Th (COT)2U

– –

(Me4COT)2U

–

(Ph4COT)2U [C8H6(CH2)2]2U [C8H6(CH2)3]2U [C8H6(CH)4]U (COT)2An (An ¼ Pa, Np, Pu)

– – – – –

(COT)2Np K(COT)2An · (THF)2 (An ¼ Np, Pu) K(COT)2Pu · [CH3O(CH2)2]2O (COT)U(Z5‐C4Me4P)(BH4)(THF)

– – – H(3), O

[(COT)U(BH4)(m‐OEt)]2 (COT)U(BH4)2(OPPh3) (COT)(Cp*)Th(m‐Cl)2Mg(CH2tBu) (THF) · 0.5PhMe (COT)UCl2(pyr)2 (COT)ThCl2(THF)2 (COT)(Cp*)Th[CH(SiMe3)2] [(COT)U(mdt)]2 (COT)U(mdt)(pyr)2

H(3), O(2) H(6), O Cl(2)

(COT)Th[N(SiMe3)2]2 (COT)(Cp*)U(Me2bpy) (m‐Z8,Z8‐COT)U2(NC[tBu]Mes)6 [(COT)U]2[m‐Z4,Z4‐HN(CH2)3N(CH2)2 N(CH2)3NH] [(COT)Cp*U(THF)2]BPh4 [(COT)U(OiPr)(m‐OiPr)]2 (COT)U(MeCOCHCOMe)2 [Na(18‐crown‐6)(THF)2][(COT)U(StBu)3] [(COT)U(m‐SiPr)2]2 [Na(18‐crown‐6)(THF)][(COT)U(C4H4S4)2]

Cl(2), N(2) Cl(2), O(2) C C(2), S(4) C(2), N(2), S(2) N(2) N(2) N(3)

References Avdeef et al. (1972) Zalkin and Raymond (1969); Avdeef et al. (1972) Hodgson and Raymond (1973) Templeton et al. (1977) Zalkin et al. (1979) Zalkin et al. (1982) Zalkin et al. (1985) Karraker et al. (1970); Starks et al. (1974) De Ridder et al. (1996b) Karraker and Stone (1974) Karraker and Stone (1974) Cendrowski‐Guillaume et al. (2002) Arliguie et al. (1992) Baudry et al. (1990a) Gilbert et al. (1989) Boussie et al. (1990) Zalkin et al. (1980) Gilbert et al. (1989) Arliguie et al. (2003) Arliguie et al. (2003)

N(4)

Gilbert et al. (1988) Schake et al. (1993) Diaconescu and Cummins (2002) Le Borgne et al. (2000)

O(2) O(3) O(4) S(3) S(4) S(4)

Berthet et al. (1995) Arliguie et al. (1992) Boussie et al. (1990) Leverd et al. (1994) Leverd et al. (1994) Arliguie et al. (2000)

The p‐bonding of indenyl ligands to the Th(IV) center in (C9H7)4Th occurs in an Z3 manner, where the five‐membered rings of each indenyl ligand form the apices of a distorted tetrahedron. The indenyl bonding occurs through the three non‐bridging carbons of each five‐membered ring, giving thorium a

Organoactinide compounds

2489

Fig. 22.39 Crystal strucuture of [C8H6(CH2)2]2U with hydrogen atoms omitted (Zalkin et al., 1979). The coordinates were obtained from the Cambridge Structural Database (refcode CBOCTU).

coordination number of 12. The lengthening of the distance between thorium and the remaining two bridging carbons of the five‐membered ring is likely a consequence of localization of charge at these sites (Rebizant et al., 1986a,b). This is similar to what is observed in (C12H13)3ThCl (containing a trimethyl indenyl ligand) (Spirlet et al., 1982) and (C9H7)3UCl. In the latter case, the three ˚ , while the two shorter U–C bond distances range from 2.67(1) to 2.77(1) A ˚ , suggesting trihapto bonding. longer bonds are in the range of 2.79(1)–2.89(1) A However, the authors suggest the possibility of pentahapto bonding if one considers steric interferences from chloride and the six‐membered ring (Burns and Laubereau, 1971). The trihapto indenyl coordination mode is also reported in the bromide and iodide analogs of the uranium complex (Spirlet et al., 1987b; Rebizant et al., 1988). Pentahapto coordination of the indenyl ligand is apparent in the structures of several complexes, including (C9H7)3U (Meunier‐Piret et al., 1980a), (C9H7)2U (BH4)2 (Rebizant et al., 1989), and (C9H7)UBr3(THF)(OPPh3) (Meunier‐Piret et al., 1980b). In the tri‐indenyl uranium complex (Fig. 22.40), the U–Cindenyl bond distances to the five‐membered ring are very similar; for instance, these ˚, distances for one of the indenyl rings are 2.846, 2.802, 2.845, 2.833, and 2.804 A with no bridging/non‐bridging correlation. The first example of monhapto indenyl coordination is in the structure of (C15H19)3ThCl, where the hexamethyl indenyl ligand is s‐bonded through one carbon of each five‐membered ring to thorium (Spirlet et al., 1992b). Arene complexes of the actinides are very few (and limited to uranium); those for which structures are available show Z6 p‐bonding of the aromatic ring

Table 22.34

Representative other organoactinide complexes.

Structure

Other donors (# per center)

indenyl pentahapto (
5) (C9H7)3U

–

(C9H7)2U(BH4)2 (C9H7)UX3(THF)2 (X ¼ Cl, Br)

References

Meunier‐Piret et al. (1980a) Rebizant et al. (1989) Rebizant et al. (1983, 1985) Meunier‐Piret et al. (1980b)

(C9H7)UBr3(THF)(OPPh3)

H(6) Cl(3), O(2); Br(3), O(2) Br(3), O(2)

trihapto (
3) (C9H7)4Th

–

(C11H11)3ThCl (C12H13)3ThCl (C9H7)3UCl

Cl Cl Cl

(C12H13)3UCl

Cl

(C9H7)3UBr [(C9H7)UBr2(NCMe)4]2[UBr6] [{(C9H7)UBr(NCMe)4}2(m‐O)] [UBr6] (C9H7)3UI (C11H11)3ThCH3 (C9H7)3U(OCH2CF3)

Br Br(2), N(4) Br, N(4), O

Rebizant et al. (1986a,b) Spirlet et al. (1990b) Spirlet et al. (1982) Burns and Laubereau (1971) Meunier‐Piret and Van Meerssche (1984) Spirlet et al. (1987b) Beeckman et al. (1986) Beeckman et al. (1986)

I C O

Rebizant et al. 1988) Spirlet et al. (1993b) Spirlet et al. (1993c)

monohapto (s‐bonded ) (C15H19)3ThCl

Cl

Spirlet et al. (1992b)

arenes (C6Me6)U(BH4)3 [(C6Me6)UCl2]2(m‐Cl)3(AlCl4)

H(9) Cl(5)

[(C6Me6)UCl2(m‐Cl)3Cl2U (C6Me6)][AlCl4] (C6Me6)UCl2(m‐Cl)3UCl2 (m‐Cl)3Cl2U(C6Me6) (C6H6)U(AlCl4)3 (C6Me6)U(AlCl4)3

Cl(5)

Baudry et al. (1989b) Cotton and Schwotzer (1985) Campbell et al. (1986)

Cl(5); Cl(8)

Campbell et al. (1986)

Cl(6) Cl(6)

[U3(m3‐Cl)2(m2‐Cl)3(m1,Z2‐AlCl4)3 (Z6‐C6Me6)3][AlCl4] [U(O‐2,6‐iPr2C6H3)3]2

Cl(6)

Cesari et al. (1971) Cotton and Schwotzer (1987) Cotton et al. (1986)

O(3)

Van Der Sluys et al. (1988)

Summary

2491

Table 22.34 (Contd.) Other donors (# per center)

References

Cl(4) Cl(4)

Secaur et al. (1976) Schnabel et al. (1999)

Cl(2), N(2) Cl(2), N N(2) N(2)

Marks (1977) Paolucci et al. (1991) Peters et al. (1999) Schnabel et al. (1999)

other [U(C3H5)2(OiPr)2]2 [Li(THF)4]2[(C2B9H11)2UCl2] [U(BH4)(THF)5][U(BH4)3 (m‐Z7,Z7‐C7H7)U(BH4)3] [K(18‐crown‐6)][U(Z‐C7H7)2] K2(m‐Z6,Z6‐C10H8)[U(NC[tBu]Mes)3]2

type allyl dibarbollide cycloheptatrienyl

Brunelli et al. (1979) Fronczek et al. (1977) Arliguie et al. (1994b)

(Me4Fv)2FeThCl2

fulvalene

[(Z5‐C4Me4P)(m‐Z5‐C4Me4P)U(BH4)]2 (Z5‐C4Me4P)2U(BH4)2 (Z‐2,4‐Me2C5H5)U(BH4)3

phospholyl phospholyl dimethylpentadienyl

Structure ring‐bridged LiU2Cl5[CH2(C5H4)2]2(THF)2 [Me2Si(C5Me4)2]U(m‐Cl4) [Li(TMEDA)]2 [CH2(C5H4)2]UCl2(bipy) m‐[2,6‐CH2C5H3NCH2](Z5‐C5H4)2UCl2 (Cp*)(C5H4CH2)U(NAd)(NHAd) [{Me2Si(C5Me4)(C5H4)}U(m‐NPh)]2

cycloheptatrienyl napthalene

Arliguie et al. (1995) Diaconescu and Cummins (2002) Scott and Hitchcock (1995) Gradoz et al. (1994) Baudry et al. (1990b) Baudry et al. (1989a)

* Semicolons used to differentiate coordination to different metal centers or different structures.

(C6H6) to the metal center. For example, in the complexes (C6H6)U(AlCl4)3 (Cesari et al., 1971) and (C6Me6)U(AlCl4)3 (Cotton and Schwotzer, 1987), the hexahapto arene ligands are bound to the uranium centers along with three bidentate AlCl4 ligands (through chlorine), resulting in pentagonal bipyramidal structures (Fig. 22.41). In the case of [(C6Me6)UCl2]2(m‐Cl)3(AlCl4), as well as other U(III)–benzene complexes, the U–benzene (centroid) distances are considerably longer than in traditional anionic p‐ligands. This is a strong indication of the relatively weak bonds that form in these types of complexes with the neutral arene ligand (Cotton and Schwotzer, 1985).

22.6

SUMMARY

The actinide structures that have been presented herein represent a fraction of known f‐element compounds that have been studied by neutron and X‐ray diffraction techniques. However, this treatment is by no means exhaustive as it

2492

Actinide structural chemistry

Fig. 22.40 Crystal strucuture of (C9H7)3U with hydrogen atoms omitted (Meunier‐Piret et al., 1980a). The coordinates were obtained from the Cambridge Structural Database (refcode TRINUR).

would require several more chapters of comparable length. It should be apparent that the study and structural characterization of actinide compounds continues to play an important role in understanding the nature of this fascinating row of elements. While it is true that most simple and fundamental actinide compounds have been structurally characterized over the past 50 years, these studies are only the ‘tip of the iceberg’ in terms of what can and has yet to be discovered. Due to the complex nuclear wastes that exist at many sites, the intricacies of environmental actinide migration and interaction phenomena, the task‐specific nature of fuel processing schemes for the recovery of heavy elements, and a continued fundamental academic interest in these elements, advances in actinide chemistry will continue to be increasingly important into the foreseeable future. These advances must necessarily be accompanied by more complex structural analyses that will achieve a more thorough understanding of the chemical behavior of the actinides. The development of more advanced X‐ray and neutron diffraction instrumentation, along with the use of more exotic techniques such as extended X‐ray absorption fine‐structure (EXAFS) spectroscopy and even highly advanced ab initio quantum mechanics tools based on relativistic theory, will be

Summary

2493

Fig. 22.41 Crystal strucutures of (C6H6)U(AlCl4)3 (Cesari et al., 1971) and (C6Me6)U (AlCl4)3 (Cotton and Schwotzer, 1987) with hydrogen atoms omitted. The coordinates were obtained from the Cambridge Structural Database (refcodes BNZUAL and FODRUL).

paramount in moving forward. These techniques will continue to assist in the elucidation of the critical aspects of actinide electronic structure and bonding, such as the role of 5f electrons in covalent interactions, that are still widely studied and debated. Nonetheless, the actinides are a series of elements unlike any other that will continue to provide ample challenges for chemists worldwide and push the limits of existing technology, particularly in the area of structural determination.

2494

Actinide structural chemistry ABBREVIATIONS

Acac BBN bipy n Bu t Bu (tBu)Cp (tBu)2Cp COT Cp Cp* Cp0 Cp00 Cp000 Cptt CpCH2Ph DABCO DMAP DMF DMPE DMSO Et HTTA mdt Me Me2bpy Me4COT MeCp Me4Cp Me4Fv Mes NAd OAr OTf Ph Ph4COT PMDETA i Pr n Pr pyr

acetylacetonato ¼ 2,4‐pentanedionato 9‐borabicyclo(3.3.1)nonane 2,20 ‐bipyridyl butyl ¼ C4H9– tert‐butyl ¼ (CH3)3C–
5‐C5H4(tBu)
5‐C5H3(tBu)2–1,3
8‐C8H8
5‐C5H5
5‐C5(CH3)5
5‐C5H4[Si(CH3)3]
5‐C5H3[Si(CH3)3]2–1,3
5‐C5H2[Si(CH3)3]3–1,2,4
5‐C5H3[SitBu(CH3)2]2–1,3
5‐C5H4(CH2C6H5) 1,4‐diazabicyclo[2.2.2]octane dimethylaminopyridine dimethylformamide (Me)2P(CH2)2P(Me)2 dimethylsulfoxide ethyl ¼ C2H5– thenoyl trifluoroacetone 1,3‐dithiole‐4,5‐dithiolate methyl ¼ CH3– 4,40 ‐dimethyl‐2,20 ‐bipyridine
8‐C8H4(CH3)4
5‐C5H4(CH3)
5‐C5H(CH3)4 1,2,3,4‐tetramethylfulvalene 2,4,6‐C6H2(CH3)3 1‐adamantyl 2,5‐dimethylphenoxide OSO2CF3 phenyl ¼ C6H5–
8‐C8H4(C6H5)4 pentamethyldiethylenediamine ¼ (Me2NCH2CH2)2NMe iso‐propyl ¼ (CH3)2CH– n‐propyl ¼ C3H7– pyridine ¼ C5H5N; Hpyr ¼ C5H5NH

References (SiMe3)2CHCp THF TMED

2495

Z5‐C5H4[CH(SiMe3)2] tetrahydrofuran ¼ OC4H8 tetramethylethylenediamine

ACKNOWLEDGMENT

The authors thank Dr. Ann E. Visser for her early contributions to this chapter.

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Zachariasen, W. H. (1949c) Nat. Nucl. Ener. Ser., Manhattan Proj. Tech. Sect., Div. 4, Plutonium Proj. 14B, 1448–50. Zachariasen, W. H. (1949d) Acta Crystallogr., 2, 94–9. Zachariasen, W. H. (1949e) Acta Crystallogr., 2, 291–6. Zachariasen, W. H. (1949f) Acta Crystallogr., 2, 288–91. Zachariasen, W. H. (1949g) Acta Crystallogr., 2, 296–8. Zachariasen, W. H. (1951) Acta Crystallogr., 4, 231–6. Zachariasen, W. H. (1952a) Acta Crystallogr., 5, 660–4. Zachariasen, W. H. (1952b) Acta Crystallogr., 5, 664–7. Zachariasen, W. H. (1952c) Acta Crystallogr., 5, 17–19. Zachariasen, W. H. (1953) Acta Crystallogr., 6, 393–5. Zachariasen, W. H. (1954) Acta Crystallogr., 7, 795–9. Zachariasen, W. H. and Ellinger, F. H. (1955) Acta Crystallogr., 8, 431–3. Zachariasen, W. H. and Ellinger, F. H. (1957) J. Chem. Phys., 27, 811–12. Zachariasen, W. H. and Ellinger, F. H. (1959) Acta Crystallogr., 12, 175–6. Zachariasen, W. H. and Plettinger, H. A. (1959) Acta Crystallogr., 12, 526–30. Zachariasen, W. H. and Ellinger, F. H. (1963a) Acta Crystallogr., 16, 777–83. Zachariasen, W. H. and Ellinger, F. H. (1963b) Acta Crystallogr., 16, 369–75. Zachariasen, W. H. (1975) J. Inorg. Nucl. Chem., 37, 1441–2. Zalkin, A., Forrester, J. D., and Templeton, D. H. (1964) Inorg. Chem., 3, 639–44. Zalkin, A. and Raymond, K. N. (1969) J. Am. Chem. Soc., 91, 5667–8. Zalkin, A., Rietz, R. R., Templeton, D. H., and Edelstein, N. M. (1978a) Inorg. Chem., 17, 661–3. Zalkin, A., Ruben, H., and Templeton, D. H. (1978b) Inorg. Chem., 17, 3701–2. Zalkin, A., Templeton, D. H., Berryhill, S. R., and Luke, W. D. (1979) Inorg. Chem., 18, 2287–9. Zalkin, A., Templeton, D. H., Le Vanda, C., and Streitweiser, A. Jr (1980) Inorg. Chem., 19, 2560–3. Zalkin, A., Templeton, D. H., Luke, W. D., and Streitwieser, A. Jr (1982) Organometallics, 1, 618–22. Zalkin, A. and Brennan, J. G. (1985) Acta Crystallogr. C, 41, 1295–7. Zalkin, A., Templeton, D. H., Kluttz, R., and Streitwieser, A. Jr (1985) Acta Crystallogr. C, 41, 327–9. Zalkin, A. and Brennan, J. G. (1987) Acta Crystallogr. C, 43, 1919–22. Zalkin, A., Brennan, J. G., and Andersen, R. A. (1987a) Acta Crystallogr. C, 43, 1706–8. Zalkin, A., Brennan, J. G., and Andersen, R. A. (1987b) Acta Crystallogr. C, 43, 418–20. Zalkin, A., Brennan, J. G., and Andersen, R. A. (1987c) Acta Crystallogr. C, 43, 421–3. Zalkin, A. and Beshouri, S. M. (1988) Acta Crystallogr. C, 44, 1826–7. Zalkin, A., Brennan, J. G., and Andersen, R. A. (1988a) Acta Crystallogr. C, 44, 2104–6. Zalkin, A., Stuart, A. L., and Andersen, R. A. (1988b) Acta Crystallogr. C, 44, 2106–8. Zalkin, A. and Beshouri, S. M. (1989a) Acta Crystallogr. C, 45, 1080–2. Zalkin, A. and Beshouri, S. M. (1989b) Acta Crystallogr. C, 45, 1219–21. Zanella, P., De Paoli, G., Bombieri, G., Zanotti, G., and Rossi, R. (1977) J. Organomet. Chem., 142, C21–4. Zanella, P., Paolucci, G., Rossetto, G., Benetollo, F., Polo, A., Fischer, R. D., and Bombieri, G. (1985) J. Chem. Soc., Chem. Commun., 96–8.

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CHAPTER TWENTY THREE

ACTINIDES IN SOLUTION: COMPLEXATION AND KINETICS Gregory R. Choppin and Mark P. Jensen 23.1 23.2 23.3 23.4 23.5

23.6 23.7 23.8 23.9 23.10 23.11

Correlations 2567 Actinide complexes 2577 Ternary complexes 2591 Cation–cation complexes 2593 Kinetics of redox reactions 2597 Kinetics of complexation reactions 2602 23.12 Summary 2606 References 2608

Introduction 2524 Hydration of actinide cations 2528 Hydrolysis of actinide cations 2545 Bonding in actinide complexes 2556 Inner versus outer sphere complexation 2563

23.1 INTRODUCTION

The solution chemistry of the actinide elements has been explored in aqueous and organic solutions. While the relative stabilities of the actinide oxidation states and the types of complexes formed with the actinide cations in these states vary between solvents, the fundamental principles governing their redox reactions and their complexation strengths are the same regardless of the solvent. This chapter focuses on aqueous actinide chemistry, reflecting the wide variety of studies on actinide reactions in aqueous solutions. However, three factors that are important for actinides in non‐aqueous solvents should be noted. First, in non‐aqueous solvents, the formation of neutral cation–anion ion pairs is often dominant due to the lower (as compared to water) dielectric constants of the solvents. Second, non‐aqueous conditions also allow the formation of complexes between actinide cations and ligands containing soft Lewis base groups, such as sulfur. Third, non‐aqueous solvents are often useful for

2524

Introduction

2525

stabilizing redox‐sensitive actinide complexes, as oxidation states that are unstable in aqueous solution may be stable in non‐aqueous solutions (Mikheev et al., 1977; Hulet et al., 1979). Actinide cations can exist in a variety of oxidation states (2þ to 7þ) in aqueous solution, with trivalent, tetravalent, pentavalent, and hexavalent actinides being the most common. However, there is wide variability in the stability of a particular oxidation state across the actinide series and for some actinides several oxidation states can coexist in the same solution. This is most evident for plutonium as there are small differences in the redox potentials of Pu(III), Pu(IV), Pu(V), and Pu(VI) over a range of pH values (Fig. 23.1). The divalent oxidation state is the most stable form of nobelium in acidic aqueous solution. It is strongly stabilized, relative to the trivalent state, by the formation of a closed, 5f14 shell, as reflected in the large reduction potential of the No3þ aquo ion [E (No(III)/No(II)) ¼ þ1.45 V vs NHE] (see Chapter 19).

Fig. 23.1 Reduction potential diagrams for uranium, neptunium, and plutonium for 1 M HClO4, pH 8, and 1 M NaOH (Choppin et al., 2002). Values for 1 M HClO4 are formal potentials for that medium.

2526

Actinides in solution: complexation and kinetics

This is in direct contrast to nobelium’s lanthanide homolog, ytterbium, which is significantly more stable as E (Yb(III)/Yb(II)) ¼ –1.05 V vs NHE (Morss, 1985). The stability of No(II) suggests that isoelectronic Md(I) might be expected in aqueous solution. However, while Md(I) has been reported (Mikheev et al., 1980), its existence has not been confirmed (Hulet et al., 1979; Samhoun et al., 1979). Md(II) is moderately stable in acidic solution [E (Md(III)/ Md(II)) ¼ 0.15 V vs NHE], and can be produced through the reduction of Md(III) by Cr(II), Eu(II), or metallic zinc. Nobelium and mendelevium are the only actinides stable as divalent cations in aqueous solution but Am(II), Cm(II), and Cf(II) can be produced transiently in aqueous acidic solutions by pulse radiolysis (Gordon et al., 1978). Trivalent californium, einsteinium, and fermium also can be reduced to the divalent oxidation state by Sm(II) or Yb(II) in 85% ethanol/water. The trivalent oxidation state is the most stable form of actinium and the transplutonium actinide ions, americium to mendelevium and lawrencium, in aqueous solution. Pu(III) is readily produced by reduction, but it is slowly oxidized to Pu(IV) by the radiolysis products from the a‐decay if more than tracer amounts of 238Pu or 239Pu are present. Solutions of the long‐lived plutonium isotopes 242Pu and 244Pu in 1 M perchloric acid show little oxidation of Pu(III) after storage for weeks. Np(III) is less stable than Pu(III) but its oxidation to Np(IV) is very slow in the absence of oxygen. U(III) is a strong reducing agent, oxidizing in water. Trivalent thorium and protactinium are not stable in solution. All the actinides from thorium to californium form tetravalent species in aqueous solution. Th(IV) is the only oxidation state of thorium that is stable in solution. Pa(IV), U(IV), and Np(IV) are stable in the absence of oxygen. Low concentrations of Pu(IV) are stable in acidic aqueous solutions even in the presence of oxygen, but the similarity of the potentials of the Pu(IV)/Pu(V), Pu(V)/Pu(IV), and Pu(IV)/Pu(III) redox couples can make it difficult to prepare and maintain high concentrations of plutonium in a single oxidation state because of the resulting tendency of plutonium to undergo disproportionation reactions (see Section 23.10). Tetravalent americium, curium, berkelium, and californium are much less stable than the other An(IV) species, but they can be prepared in aqueous solution with strong oxidants in the presence of fluoride, phosphate, or polyoxometallate ligands, which form strong complexes with the tetravalent actinides. Bk(IV) is the most stable of the tetravalent transplutonium species with a Bk(IV)/Bk(III) reduction potential similar to that of Ce(IV) [E (Ce (IV)/Ce(III)) ¼ þ1.6 V vs NHE] (Antonio et al., 2002). The actinides from protactinium to americium can be prepared in the pentavalent oxidation state. Pa(V) and Np(V) are the most stable oxidation states of these elements in aqueous solution, though NpOþ 2 disproportionates to Np(IV) and Np(VI) at high neptunium concentrations and acidities (>8 M HNO3). UOþ 2 and PuO2þ are very susceptible to disproportionation, but become more stable as the uranium or plutonium concentration is decreased or the pH is increased.

Introduction

2527

PuOþ 2 becomes the predominant dissolved form of plutonium in natural waters (Nelson and Lovett, 1978). AmOþ 2 is a strong oxidant and is reduced to Am(III) by alpha radiolysis. The hexavalent oxidation state of the actinides, which is present as AnO2þ 2 ions in aqueous solution, is known for the actinides from uranium to americium. UO2þ 2 is the most stable form of uranium in solution and is the most stable of the actinyl(VI) cations. The stability of the actinyl(VI) cations decreases in the 2þ 2þ 2þ order UO2þ 2 >> PuO2 >NpO2 >AmO2 . Np(VI) can be reduced by cation exchange resin to Np(V) (Sullivan et al., 1955). The heptavalent actinides, Np(VII) and Pu(VII), are unstable in acidic solution. The reduction of Np(VII) and Pu(VII) to the hexavalent oxidation state is very slow in alkaline solutions (Spitsyn et al., 1968; Sullivan and Zielen, 1969), and is reversible in 1 M NaOH (Zielen and Cohen, 1970). The structure of the Np(VII) anion, NpO4 ðOHÞ3 2 , is the same in the solid state (Burns et al., 1973; Tomilin et al., 1981; Grigor’ev et al., 1986) and in solution (Appelman et al., 1988; Williams et al., 2001). The existence of Am(VII) (Krot et al., 1974; Shilov, 1976) is still a matter of controversy. Given the stabilities of the various oxidation states, as well as the limited availability and high specific activity of many of the actinide nuclides, there are comparatively few solution studies of the complexes of actinium, protactinium, and the transplutonium elements from berkelium to lawrencium. Quantitative information about the complexation of actinide ions in the less common oxidation states, An(II) and An(VII), also is very scarce. The lack of data on these species can often be filled by extrapolation from the behavior of other, better studied actinide cations. Stability constants provide a measure of the resistance of a metal–ligand complex to dissociation in solution, and are directly related to the Gibbs energy of complexation. It is often difficult to measure the chemical activities of actinide ions, ligands, and complexes, so concentrations are used commonly in place of activities for calculations of stability constants. Such concentration stability constants are valid for only a limited range of conditions due to their dependence on the ionic strength of the solution. The concentration stability constant, bnq, for the reaction of an actinide cation, An, with a ligand, L, according to the equation, nAn þ qL ! Ann Lq is bnq ¼ ½Ann Lq =½An n ½L q

ð23:1Þ

This notation is used throughout this chapter to identify stability constants, Gibbs energies (DGnq), enthalpies (DHnq), and entropies (DSnq) of complexation of n actinide cations by q ligands.

2528

Actinides in solution: complexation and kinetics 23.2 HYDRATION OF ACTINIDE CATIONS

The hydration of an actinide cation is a critical factor in the structural and chemical behavior of the complexes. Although f‐element salts generally have large lattice energies, many are fairly soluble in water, reflecting the strength of the interactions between the metal cations and water molecules. Once an actinide cation is dissolved in an aqueous solution, the formation of inner sphere complexes involves displacement of one or more water molecules by each ligand. In the reaction with simple ligands to form inner sphere complexes, the release of water molecules from the hydration spheres of the ligand and actinide ion to the bulk solvent contributes to the thermodynamic strength of the complexes formed by increasing the entropy, but some of this gain is offset by a positive enthalpy contribution. The size and structure of the hydration sphere of a metal ion have been probed by direct and indirect methods. Direct methods include X‐ray and neutron diffraction, X‐ray absorption fine structure (XAFS) measurements, luminescence decay, and nuclear magnetic resonance (NMR) relaxation measurements, while the indirect methods involve compressibility, NMR exchange, and optical absorption spectroscopy. Theoretical and computational studies are also becoming important in understanding the coordination geometry and coordination number (CN) of actinide ion hydrates (e.g. Spencer et al., 1999; Hay et al., 2000; Tsushima and Suzuki, 2000; Antonio et al., 2001).

23.2.1

Trivalent actinides

Much of the initial hydration data reported for trivalent actinide cations were derived by analogy to the experimental data for the trivalent lanthanide ions. In the lanthanide studies, the data is consistent with formation of an isostructural series with nine water molecules coordinated to the early members of the lanthanide series that transitions to an isostructural series containing eight water molecules over the middle members of the lanthanide series. This reflects the decrease in radius with increasing atomic number; i.e. the lanthanide (and actinide) contraction. The transition between CN ¼ 9 and 8 occurs between Pm(III) and Dy(III) for the Ln(III) series. The trivalent cations of both the An(III) and Ln(III) series have similar cationic radii, and a similar decrease in hydration number from nine to eight is observed for the trivalent actinide elements between Am(III) and Es(III) (Table 23.1), which span the same range of cationic radii as Pm(III)–Dy(III). Initial measurements of the hydration of the trivalent actinides involved electrophoretic and diffusion methods in which it is difficult to differentiate between the total hydration (all of the water molecules that feel the effect of a cation over several concentric hydration spheres) and first sphere or primary hydration (i.e. the water molecules directly coordinated to the cation).

Hydration of actinide cations

2529

Table 23.1 Hydration radii, Rb, hydration numbers, h, and primary sphere hydration, NH2 O , of trivalent actinide ions obtained by electrophoresis and diffusion measurements (Lundqvist et al., 1981; Fourest et al., 1984; David, 1986). An3þ

˚) Rb (A

h

NH2 O

Am Cm

4.60 4.69 4.55 4.9 4.64 4.92 4.95 4.88

13.6 14.4 13.0 16.4 13.8a 16.6 16.9 16.2

9.0 8.9 – 8.2 – 8.0 – –

Cf Es Fm Md a

Data obtained from diffusion measurements.

Fig. 23.2 Total hydration (h) and number of water molecules in the primary coordination sphereðNH2 O Þ of Ln3þ and An3þ cations (Rizkalla and Choppin, 1994).

Fourest et al. (1984) estimated the primary, inner sphere coordination numbers, NH2 O of the trivalent actinides by interpolation using the values of the lanthanide elements (Habenschuss and Spedding, 1979a, 1979b, 1980). The two sets of hydration numbers for Ln(III) and An(III) cations are presented in Fig. 23.2.

2530

Actinides in solution: complexation and kinetics

These values show that the primary hydration number, NH2 O , of the trivalent metal ions as a function of cationic radius for coordination number 8 is, in both cases, sigmoidal with smaller primary hydration for the smaller, heavier cations. By contrast the opposite trend is seen for the total hydration number, h, which is smaller for the lighter cations. This was attributed by Fourest’s group to the increase in the cationic charge density as the atomic number increases. It should be noted that the break in the properties of the two series also is observed in other physical data such as apparent molal volume, relative viscosity, heat of dilution, and electrical conductivity. The coordination geometry in the first hydration sphere has been obtained primarily from neutron diffraction measurements and is consistent with formation of nona‐coordinate lanthanides with a tricapped trigonal prismatic (TCTP) structure. X‐ray crystal structures of nona‐coordinate Ln(III) and Pu(III) triflates also show this geometry in the solid state (Chatterjee et al., 1988; Matonic et al., 2001). Similarly, the data for the heavier members of the series, with coordination number 8, are consistent with a square prismatic structure. The ions that are intermediate between these two extremes (Pm–Dy or Am–Es) show an equilibrium mixture of the structures for NH2 O ¼ 8 and NH2 O ¼ 9. Optical spectroscopy indirectly confirms that the solid state structures of the hydrated An(III) ions persist in solution as well (Carnall, 1989; Matonic et al., 2001), and fluorescence lifetime measurements of Cm(III) solutions give a direct primary hydration number of (9.2  0.5) (Kimura and Choppin, 1994). While it cannot give the coordination geometry, XAFS measurements are useful for determining the average actinide–oxygen bond distances of the first hydration sphere and NH2 O in liquid samples at concentrations much lower than those accessible by X‐ray or neutron diffraction. An–OH2 bond distances and coordination numbers have been determined by XAFS for all of the An(III) from U(III) to Cf(III) at concentrations of 0.520  103 M. The AnO bond distances are all consistent with octa‐ or nona‐coordination, and the average coordination number reported across the actinide series is (9  1). As is the case with the other oxidation states, some investigators report hydration numbers 10–20% higher than this, but this is within the generally accepted absolute uncertainty of XAFS‐based coordination number determinations and there are a number of factors that could explain systematic deviations from the true coordination number, as discussed by Allen et al. (2000). 23.2.2

Tetravalent actinides

Information relating to the hydration numbers of tetravalent actinide ions is somewhat limited. From NMR peak areas, an estimate of the primary hydration number of Th(IV) in an aqueous acetone solution of Th(ClO4)4 at 100 C indicated a hydration number of 9 (Butler and Symons, 1969; Fratiello et al., 1970a) whereas an indirect, NMR line width method gave NH2 O ¼ 10 (Swift and Sayre, 1966). However, the direct and accurate method of solution X‐ray

Hydration of actinide cations

2531

diffraction gave NH2 O ¼ (8:0  0:5) for acidic, 12 M Th(ClO4)4 and ThCl4 solutions (Johansson et al., 1991). Other reported values are: Th(IV) (10.8  0.5) and U(IV) (10  1) (Moll et al., 1999), Np(IV) (11.2  0.4) (Allen et al., 1997), Th(IV) 11.0, U(IV) 10.65, Np(IV) 10.2, and Pu(IV) 10.0 (David and Vokhmin, 2003). An entirely different method for the estimation of total hydration numbers from conductivity measurements has been proposed and developed by Gusev (1971, 1972, 1973). This method gave a value of h ¼ 20 for the total hydration number of Th(IV), which can be compared to the values of 22 obtained from compressibility measurements (Bockris and Saluja, 1972a,b) that are based on the lower compressibility of a solvate’s solvent molecules as a result of electroconstriction (Passynskii, 1938). Reviews of the available evidence pertaining to hydration numbers of U(IV) and Np(IV) have suggested that two forms of each of these aquo ions may exist, differing in geometry and possibly coordination number (Rykov et al., 1971; Sullivan et al., 1976). Radial distribution functions from X‐ray measurements on 2 M uranium(IV) perchlorate solutions indicate a primary hydration number of NH2 O ¼ (7:8  0:3) with no perchlorate in the primary coordination sphere (Pocev and Johansson, 1973). XAFS measurements of Np(IV) and Bk(IV) aquo cations gave NH2 O ¼ (9  1) and (7.9  0.5), respectively (Antonio et al., 2001, 2002). The An–O bond distances derived from XAFS for the An(IV) hydrates, which are more accurate than the coordination numbers, also are most consistent with a primary hydration number of 8. Changes in the optical absorption spectra of U(IV), Np(IV), and Pu(IV) also have been interpreted as consistent with NH2 O ¼ 8 (Rykov et al., 1973). 23.2.3

Pentavalent and hexavalent actinides

The hydration of pentavalent actinyl cations has been studied less than any of the other common oxidation states, but the findings are quite consistent from study to study. In the solid state, neptunyl(V) perchlorate has a total equatorial coordination number of 5. Four oxygens come from inner sphere water molecules and a fifth oxygen comes from the ‘‐yl’ oxygen of a neighboring NpOþ 2 ion (Grigor’ev et al., 1995), as discussed in Section 23.9. In solutions, where the AnOþ 2 concentration is usually quite small, cation–cation complexes (Section þ 23.9) of AnOþ 2 are not important, and fully hydrated AnO2 cations are þ expected. Optical absorption spectra of AnO2 in solution are consistent with a primary hydration number of 5, based on symmetry considerations and comparison with the spectra of solid state complexes of known structures (Garnov et al., 1996). XAFS measurements on solutions containing 1  103 to 2  102 M NpOþ 2 agree well with this, consistently giving a hydration number of 5 and Np–O equatorial bond distances that suggest the coordination of 5 water molecules (Combes et al., 1992; Allen et al., 1997; Antonio et al., 2001). Hydration numbers of the hexavalent actinyl cations have received more attention, particularly for UO2þ 2 . The Raman spectra of aqueous uranyl

2532

Actinides in solution: complexation and kinetics

solutions were interpreted to show the presence of six inner sphere water molecules in the plane perpendicular to the O¼U¼O axis (Sutton, 1952). However, similar hydration numbers have been obtained by methods that are influenced by the second hydration shell. For example, activity coefficient measurements suggest a hydration number of 7.4 relative to an assumed hydration number of zero for Cs(I) (Hinton and Amis, 1971). Similarly, a hydration number of 7 has been derived from conductivity measurements (Gusev, 1971, 1972, 1973). In the solid state, UO2(ClO4)2 · 7H2O contains discrete pentagonal bipyrami ˚ s, 1977), an dal UO2 ðH2 OÞ2þ 5 cations and ClO4 anions (Alcock and Espera indication that, like the actinyl(V) cations, penta hydration may be preferred by actinyl(VI) cations in solution. Garnov et al. (1996) also deduced a hydration 2þ number of 5 for AnO2þ 2 from absorption spectra of PuO2 . It seems likely that 2þ this is correct since XAFS measurements of AnO2 solutions also give average hydration numbers of ranging from 4.5 to 5.3 and An–O equatorial bond distances that are close matches for those of pentacoordinate UO2 ðH2 OÞ2þ 5 in UO2(ClO4)2 · 7H2O (Allen et al., 1997; Wahlgren et al., 1999; Antonio et al., 2001). In agreement with this, a study of uranyl(VI) perchlorate solutions by X‐ray diffraction concluded that the hydration number of UO2þ 2 could be either ˚ berg et al., 1983a ). 4 or 5 (A

23.2.4

Solvation and hydration in non‐aqueous media

Solvation numbers of actinide cations in non‐aqueous media have been measured for only a few systems. FTIR investigations of the homologous lanthanide solvates [Ln(NO3)3(DMSO)n] in anhydrous acetonitrile (Bu¨nzli et al., 1990) indicated a change in coordination number in the middle of the series near Eu(III) from nine to eight with increasing atomic number. NMR spectroscopy, stoichiometric, and XAFS measurements gave a solvation number of 2 for uranyl nitrate salts in tri(n‐butyl)phosphate (TBP) solutions. The total coordination number would include two for TBP coordination and four for the bidentate nitrate coordination (Siddall and Stewart, 1967; Den Auwer et al., 1997). A commonly used extractant ligand in actinide separation science is thenoyltrifluoroacetone, TTA. The luminescent lifetimes of the Cm(III) complex with TTA in various organic solvents was 130–140 ms which gives NH2 O ¼ (3:8  0:5). This indicates the formation of a Cm–TTA complex with a total CN ¼ 10 (Dem’yanova et al., 1986). Solvation of UO2þ 2 ions in water–acetone and water–dioxane mixtures were studied by ultrasound (Ernst and Jezowska‐Trzebiatowska, 1975a,b). The resulting hydration numbers are listed in Table 23.2. The data show a decrease in the hydration numbers with increasing dioxane concentration. This can be attributed to a partial replacement of waters of hydration by the organic

Hydration of actinide cations Table 23.2

2533

þ

Hydration numbers ofAnO22 ions in aqueous and mixed solvents.

Salt

Medium

Method

h

References

UO2SO4

water

ultrasound

10.3

UO2 (NO3)2

water

ultrasound

11.9

UO2SO4

dioxane–water (20%)

ultrasound

6.3

UO2 (NO3)2

dioxane–water (20%)

ultrasound

6.3

UO2SO4

dioxane–water (45%)

ultrasound

4.8

UO2 (NO3)2

dioxane–water (45%)

ultrasound

5.8

UO2 (ClO4)2 UO2 (NO3)2 UO2 (ClO4)2

acetone–water acetone–water acetone–water

PMR PMR PMR

4.0 2.0 6.0

UO2 (NO3)2

acetone–water

PMR

6.0

UO2Cl2

acetone–water

PMR

6.0

UO2 (ClO4)2 UO2 (ClO4)2 NpO2 (ClO4)2 NpO2 (ClO4)2

acetone–water acetone–water acetone–water acetone–water

PMR PMR PMR PMR

4.7–4.9 4.5–4.9 6.0 4.8

Ernst and Jezowska‐ Trzebiatowska (1975a,b) Ernst and Jezowska‐ Trzebiatowska (1975a,b) Ernst and Jezowska‐ Trzebiatowska (1975a,b) Ernst and Jezowska‐ Trzebiatowska (1975a,b) Ernst and Jezowska‐ Trzebiatowska (1975a,b) Ernst and Jezowska‐ Trzebiatowska (1975a,b) Fratiello et al. (1970b) Fratiello et al. (1970b) Shcherbakov and Shcherbakova (1976) Shcherbakov and Shcherbakova (1976) Shcherbakov and Shcherbakova (1976) Bardin et al. (1998) ˚ berg et al. (1983a) A Shcherbakov et al. (1974) Bardin et al. (1998)

solvent although inner sphere complexation by the anion would also reduce the hydration number. This result is in agreement with low‐temperature 1H‐NMR measurements for   both UO2X2 (X is ClO 4 , Cl , or NO3 ) (Fratiello et al., 1970b; Shcherbakov 2þ and Shcherbakova, 1976) and NpO2 (Shcherbakov et al., 1974) compounds (Table 23.2). For uranyl, the average number of bound waters was shown to increase with increasing molar ratio, ½H2 O =½UO2þ 2 , to a limiting value of six for ratios from 40 to 70 depending on the anion (Shcherbakov and Shcherbakova, 1976). The stronger the complexing ability of the anion, the higher the ratio required to reach maximum hydration. More recent high‐field NMR measure2þ ments of UO2þ 2 and NpO2 hydration report NH2 O ¼ 4.7– 4.9 for a range of 2þ ˚ ½H2 O =½AnO2 ratios (Aberg et al., 1983a; Bardin et al., 1998).

2534

Actinides in solution: complexation and kinetics 23.2.5

Measurements of N H2 O by TRLF technique

Beitz and Hessler (1980) reported the first study of aqueous Cm(III) photophysics, including measurement of the emission spectrum and lifetimes of aqueous of Cm3þ in H2O and D2O. Beitz (1994) reported a value of NH2 O ¼ 9 for the hydrated Cm3þ cation and smaller residual inner sphere hydration numbers for a number of Cm(III) complexes in a review of the theoretical and experimental aspects of such studies to 1994. Studies by time‐resolved laser fluorescence (TRLF) with Cm(III) have proven very valuable for understanding the hydration of trivalent actinides. Measurement of the Cm fluorescence decay constant, k(Cm), as a function of residual hydration in crystals of lanthanide complexes of known structure and hydration doped with Cm(III) resulted in equation (23.2) for calculation of the residual hydration numbers (Kimura and Choppin, 1994): NH2 O ¼ 0:65kðCmÞ  0:88

ð23:2Þ

where k(Cm) is expressed in ms1. This equation assumes no contribution from the ligand to the deexcitation of the luminescence excited state and that quenching of the excitation results only from interaction with the OH vibrators of the water in the first coordination sphere. The absolute uncertainty in the hydration numbers calculated from equation (23.2) is 0.5. Use of equation (23.2) gives a value for NH2 O of Cm3þ in water of (9.2  0.5). The residual hydration in the primary coordination sphere of Cm(III) in a number of aminopolycarboxylate complexes (Kimura and Choppin, 1994) is plotted in Fig. 23.3 and shows the variation of the measured hydration number, NH2 O , as a function of pH. These data indicate that the complexation is initiated around pH 2–4 and the hydration number remains constant until pH values of 10 and higher are reached. This constancy over the medium pH range is consistent with the formation of very strong 1:1 complexes. The two plateaus in the data for the NTA complex reflects the successive formation of 1:1 and 1:2 complexes for this smaller ligand. In Table 23.3, the calculated hydration numbers reported for the different complexes are listed for Am(III) and Nd(III) (Kimura and Kato, 1998) and Cm(III) and Eu(III) (Kimura et al., 1996). In these systems, the total coordination number (i.e. the sum of the average number of ligand donor groups and primary water molecules) was (9.3  0.4) for Cm(III), (10.7  0.5) for Am(III), (8.8  0.5) for Eu(III) and (9.9  0.5) for Nd(III) complexation. The TRLF technique has been used to characterize Cm(III) complexation in  natural waters by ligands such as OH, CO2 3 , NO3 and humic acids 3þ (Table 23.4). While the aqueous Cm ion has nine water molecules in the primary coordination sphere, NH2 O ¼ 8:5; 8:0; 7:0; 5:0, and 3.0 are expected for monohydroxide, dihydroxide, monocarbonate, dicarbonate, and tricarbonate complexes, respectively, from the assumptions that OH vibrators of coordinated water molecules act independently in the de‐excitation process and a carbonate ion coordinates with Cm(III) as a bidentate ligand. The NH2 O for each

Hydration of actinide cations

2535

Fig. 23.3 Dependence of the hydration number of Cm(III) complexes with polyaminopolycarboxylate ligands on pH. I ¼ 0.1 M NaClO4, [Cm] ¼ 7.3  106 M, [ligand] ¼ 8  106 M. H6ttha ¼ triethylenetetraaminehexaacetic acid, H5dtpa ¼ diethylenetriaminepentaacetic acid, H4edta ¼ ethylenediaminetetraacetic acid, H3hedta ¼ N‐(2‐hydroxyethyl) ethylenediaminetriacetic acid, H4dcta ¼ trans‐1,2‐diaminocyclohexane‐tetraacetic acid, H3nta ¼ nitriliotriacetic acid. Table 23.3 Inner sphere hydration numbers of Am(III), Cm(III), Nd(III) and Eu(III) complexes with aminopolycarboxylate ligands. NHa 2 O Ligand 3

nta (1:1) nta3 (1:2) hedta3 edta4 dcta4 dtpa5 ttha6 a

Am(III)

Cm(III)

Nd(III)

Eu(III)

6.5 – 5.1 4.8 – 3.1 1.6

6.3 1.7 4.2 3.7 3.8 1.7 0.6

5.6 – 4.5 4.0 4.5 2.6 0.7

4.5 – 3.2 2.7 2.5 1.0 1.2

Uncertainties are 0.5.

species calculated from the lifetime in Table 23.4 agrees with each expected value within the experimental uncertainty. The lifetimes measured for Cm(III) humate and fulvate complexes involves two components, which indicates the presence of two types of complexes. The first component gives an NH2 O of 8.2–8.4 and the second, 3.6–3.7.

Actinides in solution: complexation and kinetics

2536 Table 23.4 lifetimes.

Inner sphere hydration number of Cm(III) complexes from fluorescence Excitation (nm)

Emission (nm)

Lifetime (ms)

N H2 O (0.5)

396.7 375.4 381.3 396.5 383 375.4 337

593 593.8 – – 603–607 593.8 608

68 63 – – 107  3 72.5  1.3 240

8.7 9.4 – – 5.2 8.1 1.8

383 – 377.5–399.4

590(sh) 599(sh) 607.4

160  5 – 141

3.2 – 3.7

397.2

598.8

72  2

8.2

Cm(OH)2þ

399.2

603.5

80  10

7.3

Cm(CO3)þ

397.5

598.0

85  4

6.8

CmðCO3 Þ 2

398.9

605.9

105  5

5.3

CmðCO3 Þ3 3

399.9

607.6

215  6

2.1

Cm humate

398 – 374–398.5 –

601.0 – 600.3 –

72  5 (80%) 145 (20%) 70  5 (80%) 142 (20%)

8.2 – 3.6 –

Medium 0.1 M HClO4 1.0 M HClO4 16 M HNO3 0.1 M HClO4 3 M K2CO3 1 M NaCO3 0.1 M Na2CO3 Cm(OH)

2þ

Cm fulvate

References Beitz et al. (1988) Klenze et al. (1991) Beitz (1991) Kim et al. (1991) Decambox et al. (1989) Beitz (1991) Klenze et al. (1991) Wimmer et al. (1992) Wimmer et al. (1992) Wimmer et al. (1992) Wimmer et al. (1992) Wimmer et al. (1992) Wimmer et al. (1992) Wimmer et al. (1992)

All of the NH2 O values calculated using equation (23.2) from the fluorescence lifetimes in the literature are chemically reasonable. The determination of the hydration number from fluorescence lifetimes makes it possible to characterize Cm(III) species in aqueous solution at high sensitivity, providing valuable insight into the primary structure of ions in solution.

23.2.6

Hydration in concentrated solutions

Data from luminescence studies in more concentrated media must be evaluated carefully. An example of this is shown in Fig. 23.4 in which the measured hydration number for the trivalent europium ion increases as the perchloric acid concentration increases. This presumably reflects the fact that as the electrolyte concentration increases, the number of water molecules in the

Hydration of actinide cations

2537

Fig. 23.4 Variation of the number of water molecules in the primary hydration sphere of trivalent europium and curium ions as determined by TRLF.

secondary hydration sphere decreases and, consequently, there is a tightening of the bond between the trivalent europium and the hydrate waters in the inner sphere. This tightening allows for more efficient quenching of the fluorescence by the hydroxyl groups of the H2O. NMR studies (Choppin, 1997) have shown that inner sphere complexation by perchlorate ions does not occur below approximately 8–10 M. Obviously, this calculated increase in hydration number does not represent greater hydration nor does it represent an effect of complexation by perchlorate; rather, it is due to the tighter bonding. The data in Fig. 23.4 show that the hydration number of the Eu(III) remains relatively constant in hydrochloric acid up to approximately 6–8 M, after which it decreases. The same is true for the Cm(III) hydration number in HCl, which begins a decline at about 5 M HCl. This difference presumably reflects greater complexation of the actinide trivalent ion by the relatively soft anion Cl. In fact, this difference in complexation has been used for over 40 years to provide efficient separation of trivalent actinides from trivalent actinides in concentrated HCl solutions by passage through columns of cation exchange resin. Independent studies (Rizkalla and Choppin, 1994) have shown that complexation does occur with the chloride anions for both trivalent actinides and lanthanides in 1.0 M HCl. The constancy of the hydration number in Fig. 23.4 for both

2538

Actinides in solution: complexation and kinetics

cations to concentrations of ca. 4 M HCl indicates that up to this concentration, only outer sphere complexes are formed and, therefore, the primary hydration sphere is not affected. At higher concentrations, however, there is greater complexation by the soft donor Cl with the actinide, which has been interpreted as reflecting an enhanced covalent interaction of trivalent actinide ions relative to that of lanthanide ions of the same ionic radius (Diamond et al., 1954, see Section 23.4). By contrast, in Fig. 23.4 it is seen that the Cm(III) and Eu(III) behavior as a function of nitric acid concentration is very similar from dilute acid to 12 M. Nitrate ions begin to form inner sphere complexes at lower concentrations than chloride anions do, as reflected in the decreased hydration number even at relatively lower concentrations. However, the oxygens of the nitrate are hard donors and, therefore, there is no evidence of any covalent enhancement in its bonding as is seen with the chloride anions for the trivalent actinide cations relative to the lanthanide cations. 23.2.7

Thermodynamic properties

As Chapter 19 of this work is devoted to the thermodynamic properties of the actinides, their ions and compounds, this section focuses only on the hydration behavior of the actinides to minimize overlap. The values used for the calculations of the thermodynamic properties in this section are taken from literature references, which are sometimes different from those accepted in recent critical assessments of the thermodynamic properties of the actinides (Grenthe et al., 1992; Silva et al., 1995; Lemire et al., 2001; Guillaumont et al., 2003) or those in Chapter 19. The thermodynamic properties of the actinide ions in the oxidation states III–VI have been reviewed by Morss (1976), Fuger and Oetting (1976), Fuger (1982), and David (1986). Calorimetric measurements of the heats of formation of the trivalent cations are limited to the actinides up to californium that are available in macroscopic quantities and with isotopes of sufficiently low specific radioactivity. Entropies of Pu(III) (Hinchey and Cobble, 1970; Fuger and Oetting, 1976), Th(IV) (Morss and McCue, 1976), and the actinyl ions UO2þ 2 2þ (Coulter et al., 1940), NpOþ 2 and NpO2 (Brand and Cobble, 1970) also have been reported. Data on other actinide species have been estimated across the entire actinide series using various models. David et al. (1985) proposed a general expression for the calculation of the o absolute enthalpy of hydration, DHhyd , based on the semiempirical model of Bockris and Reddy (1970). The hydration enthalpy of a cation can be related to the crystallographic radius, R, the hydration number, NH2 O , and the ionic charge, þZ, by the equation: o DHhyd ¼ aZ 2 ðR þ 2RW Þ1 þ bZNH2 O ðR þ RW Þ2 gZNH2 O ðR þ RW Þ3

þ sZ 2 NH2 O ðR þ RW Þ4 þ NH2 O W þ Pð1ÞZ

ð23:3Þ

Hydration of actinide cations

2539

where W is the hydration energy of one water molecule and Rw is the radius of a ˚ . The numerical values of the coefficients (a, b, etc.) of water molecule, 1.38 A equation (23.3) were computed using hydration enthalpies (which included contributions from the hydration of halide anions) of 35 monovalent, divalent, trivalent, and tetravalent ions (David et al., 1985) assuming NH2 O ¼ 4 for monovalent, 6 for divalent, and 8 for trivalent and tetravalent cations. The estimated uncertainty between the experimental and calculated enthalpies is 0.4–0.5%. Bratsch and Lagowski (1985a,b, 1986) proposed an ionic model to calculate o o the thermodynamics of hydration DGohyd , DHhyd , and DShyd using standard thermochemical cycles. The model uses the values of the enthalpy of formation of the monoatomic gas ½DHfo ðMg Þ , the ionization potential for the oxidation state under consideration, and the crystal ionic radius of the metal ion. Since the ionization potentials for the actinide ions are not all available, the authors ‘back‐calculated’ an internally consistent set of ionization potentials from selected thermodynamic data (Bratsch and Lagowski, 1986). The general set of equations used are: zþ þ þ o o o o DHhyd ðMZþ Þ ¼ DHfo ðMZþ aq Þ  DHf ðMg Þ þ Z½DHf ðHg Þ þ DHhyd ðHaq Þ

ð23:4aÞ Zþ þ þ o o o o DShyd ðMZþ Þ ¼ S o ðMZþ aq Þ  S ðMg Þ þ Z½S ðHg Þ þ DShyd ðHaq Þ

ð23:4bÞ

Zþ þ þ o o o DGohyd ðMZþ Þ ¼ DGof ðMZþ aq Þ  DGf ðMg Þ þ Z½DGf ðHg Þ þ DGhyd ðHaq Þ

ð23:4cÞ The calculated Gibbs energies and enthalpies of hydration for the actinide ions are listed in Tables 23.5 and 23.6. The absolute entropies for the gaseous ions are calculated with the equation (Johnson, 1982): So ðMZþ g Þ ¼ 1:5R lnðat wt:Þ þ R lnð2J þ 1Þ þ 108:75

ð23:5Þ

The values of the entropies of the trivalent aquo actinide ions were obtained by interpolation from the dependence of the corrected (structural) entropy term, Sco (see Chapter 19, equation (19.6)), of the lanthanides on ionic radii (Fig. 23.5) These corrected entropy values are only dependent on the structure of the aquo ion (David et al., 1985). Justification of this approach is provided by the agreement of the calculated value of Sco of Pu(III) with that from experimental data (Fuger and Oetting, 1976). The entropies are listed in Table 23.7. Similarly, the entropies of the tetravalent actinides were obtained from pertinent data on Th(IV) (Morss and McCue, 1976) and Ce(IV) (Morss, 1976).

þ3

3832 4182 4136 4114 4115 4095 4110 4144 4186 4222 4256 4285 4379 4523 4347

Element

Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

– 6960 7128 7259 7357 7432 7598 7700 7622 7822 7990 8076 8219 8477 8452

þ4 – – – 1177 – – – – – – – – – – –

þ6

Gas phase DGf (kJ mol1) þ4 – 704 606 539 497 475 356 298 416 250 116 61 51 282 233

þ3 614 314 411 477 516 571 590 586 574 563 554 547 476 351 546

Aquo ion DGf (kJ mol1)

– – 1050 969 915 850 741 – – – – – – – –

þ5 – – – 953 796 757 587 – – – – – – – –

þ6 3093 3143 3194 3238 3278 3313 3347 3377 3407 3432 3457 3479 3502 3521 3540

þ3

– 5860 5930 5994 6050 6105 6150 6194 6234 6268 6302 6333 6364 6391 6415

þ4

DGhyd (kJmol–1)

– – – 1228 – – – – – – – – – – –

þ6

Table 23.5 Gibbs energies of formation and hydration of the gaseous and hydrated actinide ions. Data from Bratsch and Lagowski (1986) and Marcus and Loewenschuss (1986).

3885 4242 4197 4176 4177 4154 – 4165 – 4199 – 4241 – 4277 – 4308 4337 4432 4580 4402

Ac Th Pa U Np Pu

Es Fm Md No Lr

Cf

Bk

Cm

Am

þ3

Element – 7022 7194 7327 7425 7498 – 7664 – 7756 – 7682 – 7882 – 8048 8135 8279 8542 8518

þ4 – – – 1210 – – – – – – – – – – – – – – – –

þ6

Gas phase DHf (kJmol–1) þ4 – 766 664 595 553 534 – 414 – 364 – 480 – 314 – 182 127 13 223 175

þ3 633 327 411 423 528 587 (592) 608 (617) 608 (615) 597 (601) 587 (577) 584 580 510 382 581

Aquo ion DHf (kJmol–1)

– – 677 1032 978 915 – 805 – – – – – – – – – – – –

þ5 – – – (1019) 861 822 – 652 – – – – – – – – – – – –

þ6 3224 3275 3326 3371 3411 3447 – 3479 – 3513 – 3544 – 3570 – 3598 3623 3648 3668 3689

þ3

– 6063 6133 6197 6253 6307 – 6353 – 6395 – 6437 – 6471 – 6505 6437 6567 6594 6618

þ4

 DHhyd (kJmol–1)

– – – 1345 – – – – – – – – – – – – – – – –

þ6

Table 23.6 Standard enthalpies of formation of the gaseous and hydrated actinide ions. Data from Bratsch and Lagowski (1986) and Marcus and Loewenschuss (1986). Number in brackets denote experimental data.

2542

Actinides in solution: complexation and kinetics

Fig. 23.5 Variation of the corrected entropy, Soc , with the crystallographic radius of the trivalent lanthanides and actinides with CN ¼ 8. ( ) experimental data (□) extrapolated data.

▪

Differences in lanthanide and actinide hydration thermodynamics have been attributed by Bratsch and Lagowski (1986) to relativistic effects in the actinides which perturb the energies of the s, p, d, and f orbitals. The first and second ionization potentials of the 7s electrons of the actinides are higher than those of the 6s electrons of the lanthanides whereas the third ionization potentials are similar for both groups and the fourth ionization potential is lower for the actinides than the lanthanides. A small decrease in IP3 and IP4 for the f7 configuration in the actinides results in smoother variations in the relative stabilities of the adjacent oxidation states across the actinide series while the greater spatial extension of the 5f orbitals increases the actinides’ susceptibility to environmental effects (Johnson, 1982). Nugent et al. (1973a,b) proposed equation (23.6) as a basis for comparison of the actinide and lanthanide thermodynamics: PðMÞ ¼ DHfo ðMg Þ þ DEðMÞ  DHfo ðM3þ aq Þ

ð23:6Þ

where DE(M) is the promotion energy from the ground state electron configuration to the f qd1s2 configuration where q varies from 0 (La and Ac) to 14 (Lu and Lr). DE(M) is approximately zero or near zero for La, Ce, Gd,

þ3

176 192 195 196 195 192 177 195 199 201 201 201 199 195 178

Element

Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

– 177 192 195 196 196 192 178 195 199 201 202 201 199 195

þ4

296 280 281 >271 – – – – – – – –

– – –

þ5

Gas phase S (JK1 mol1)

– – – 280 273 277 278 – – – – – – – –

þ6

þ4 – 417 402 399 398 399 402 408 399 395 393 393 393 395 399

þ3 199 186 183 183 185 190 199 194 194 197 206 215 224 231 255 – – 21 26 21 21 21 25 30 22 – – – – –

þ5

Aquo ion S (JK1 mol1)

– – – 98 94 92 88 88 – – – – – – –

þ6 441 444 444 445 446 448 442 455 459 464 473 482 489 492 499

þ3

– 682 682 682 682 683 682 674 682 682 682 683 682 682 682

þ4

 DShyd (JK–1 mol–1)

323 323 324 AnOþ An4þ > AnO2þ 2 > An 2

This is consistent with most thermodynamic data and reflects the effective charges on the actinide atoms in the actinyl(V) and actinyl(VI) ions (Section 23.4). Hydroxide‐bridged polynuclear complexes have been observed for actinide cations and the tendency toward polymer formation (Fig. 23.7) is a function of the charge density of the actinide cation. In the case of Th4þ and U4þ, X‐ray measurements indicate the formation of clusters built of units with ˚ . The kinetics of polymerization– an An–An distance in range 3.95–4.00 A depolymerization becomes more complicated for Pu4þ. The slower rate of

Fig. 23.7 Structure of hydroxyl bridged actinide hydroxide polymers.

2546

Actinides in solution: complexation and kinetics

depolymerization compared with the rate of polymer formation is due to an equilibrium between hydroxo and oxo bridge formation with aging.

23.3.1

Trivalent actinides

With a few exceptions, quantitative hydrolysis measurements of the actinide ions are complicated since the actinide hydroxides are quite insoluble and sorb to surfaces. The increasing pH required for hydrolysis also can result in significant changes in the oxidation state equilibria (e.g. for plutonium). Of the common oxidation states, the trivalent actinides have been the most intensively studied species. Solubility experiments (Rai et al., 1983), solvent extraction (Caceci and Choppin, 1983a), spectroscopy (Stadler and Kim, 1988), and other techniques (Shalinets and Stepanov, 1972) have been used. The low solubility of An(OH)3 in neutral/basic solutions prevents use of conventional absorption spectroscopy. However, time‐resolved laser fluorescence spectroscopy allows measurements at the very low concentrations present in neutral/ alkaline solutions (Stadler and Kim, 1988). This laser spectroscopy technique was used to study the hydrolysis of Cm(III) at concentrations as low as 3  109 M. Values obtained for formation of the 1:1 and 1:2 species at 25 C in 0.10 M (NaClO4) solutions are: log b11 ¼ (6:67  0:18) log b12 ¼ (12:6  0:28) The laser fluorescence method has been used by Fangha¨nel and Kim (1994) to measure the values of log b11 and log b12 for Cm(III) over a range of ionic strengths from 0.011 to 6.15 M in NaCl solution at pH 8.6. An evaluation of An(III) hydrolysis has been made by Rai et al. (1983). Table 23.8 lists the log *bnq and log Ksp values for the hydrolytic reactions of Am(III) from this reference. In carbonate‐free environments, Am(OH)2þ and AmðOHÞþ 2 are the major species at pH 8.2, while, in carbonate‐rich waters, Am(CO3)þ and AmðCO3 Þ 2 may also be significant components (Fig. 23.8). Because of the strong sorption characteristics of the hydroxide species, Am(III) is frequently removed from solution onto colloids, sediments, and humic substances. Stadler and Kim (1988) and the OECD‐NEA (Silva et al., 1995, Guillaumont et al., 2003) have reviewed americium hydrolysis, while the hydrolysis of trivalent actinides has been reviewed by Fuger et al. (1992) and Rizkalla and Choppin (1994). Polynuclear hydroxides of the formula An2(OH)24þ have been reported for Np(III) (Allard et al., 1980) and Pu(III) (Allard and Rydberg, 1983) with values for log  b22 of ca. 15 (Np) and 16 (Pu). Values for the AnOH2þ hydrolysis formation constants for the trivalent actinide ions are listed in Table 23.9.

Hydrolysis of actinide cations

2547

Table 23.8 Hydrolysis constants for Am(III), I ¼ 0 M; T ¼ 22 C (Rai et al., 1983; Felmy et al., 1990). I. log *bnq values for formation of Am(OH)q3-q Am3þ þ H2 O ! AmðOHÞ2þ þ Hþ þ Am3þ þ 2 H2 O ! AmðOHÞþ 2 þ 2H Am3þ þ 3 H2 O ! AmðOHÞ3 þ 3Hþ

log log log

II. logKsp values for solid Am(OH)3 AmðOHÞ3ðamÞ ! Am3þ þ 3OH AmðOHÞ3ðcrÞ ! Am3þ þ 3OH

log Ksp ¼ 24:5 log Ksp ¼ 27:0



b11 8:2 b12 ¼ 17:1  b13 ¼ 28:6 

Fig. 23.8 Fraction of Am(III) species in water in equilibrium with atmospheric carbon dioxide as a function of pH (Choppin et al., 2002).

23.3.2

Tetravalent actinides

Study of the aqueous chemistry of tetravalent actinides can be difficult due to the very strong tendency of the cations to hydrolyze even in acidic solutions (pH

ca. 2). Moreover, An(IV) cations of elements from protactinium through americium can undergo redox reactions relatively easily if the pH is not very low or in the absence of a strong complexant, making it difficult to ensure that only the tetravalent oxidation state is present. Thorium is found in aqueous solution only in the 4þ oxidation state and is often used as a model for Np(IV) and Pu(IV) behavior. However, it has a smaller ionic charge density than these cations, due to its larger ionic radius, that results

2548

Actinides in solution: complexation and kinetics

Table 23.9 Hydrolysis constants of trivalent actinide ions; T ¼ 25 C (Rizkalla and Choppin, 1994). Species

Medium

Method a

log *bnq

Np(OH)2þ Pu(OH)2þ

0.3 M NaClO4 1.0 M NaClO4 0.2 M LiClO4, 23 C 1.0 M NaClO4 1.0 M NaClO4 0.7 M NaCl, 21 C 0.5 M(H,NH4)ClO4 0.1 M LiClO4, 23 C 0.1 M LiClO4, 23 C 0.1 M NaClO4 0.1 M NaClO4 0.1 M NaClO4 0.2 M NaClO4 0.1 M NaClO4 0.1 M NaClO4 0.1 M NaClO4 0.1 M NaClO4 0.1 M NaClO4 0.1 M LiClO4, 23 C 0.1 M LiClO4, 23 C 0.1 M LiClO4 0.1 M LiClO4, 23 C 0.1 M LiClO4, 23 C 0.1 M LiClO4, 23 C 0.1 M LiClO4, 23 C 0.1 M LiClO4, 23 C

pH pH ex sol ex ex ex ex ex sol sol sol ex sol sol sol sol sol ex ex ex ex ex ex ex ex

7.43  0.12 5.53 3.80  0.2 7.03  0.05 7.50  0.3 7.54  0.2 6.80  0.3 5.92 5.30  0.1 7.68 7.93 6.34  0.83 14.76 16.56 14.77 13.64  0.63 24.84 24.71 5.92  0.13 5.40  0.1 5.93 5.66 5.62 5.05 5.14 3.8  0.2

Am(OH)2þ

AmðOHÞþ 2

Am(OH)3 Cm(OH)2þ Bk(OH)2þ Cf(OH)2þ Es(OH)2þ Fm(OH)2þ a

pH, potentiometric titration; sol, solubility; ex, solvent extraction.

in significant differences in the extent of the hydrolytic reactions. The hydrolysis of Th4þ involves extensive formation of polynuclear complexes. In the earlier stages of the hydrolysis in perchlorate media, when the number of hydroxide ions per thorium atom in the complexes is 2, the hydrolytic reactions are fully reversible and equilibrium is quickly reached (Hietanen, 1954; Kraus and Holmberg, 1954; Baes et al., 1965). The first extensive measurements of the hydrolysis behavior were interpreted (Hietanen, 1954) as indicating the formation of an infinite series of ‘core þ links’ complexes, ThððOHÞ3 ThÞ4þn n . However, other measurements over large pH and Th(IV) concentration ranges 8þ could be satisfactorily fitted with three polymers, Th2 ðOHÞ6þ 2 ; Th4 ðOHÞ8 , 9þ þ 3þ and Th6 ðOHÞ15 , and two monomers, ThOH and ThðOHÞ2 (Kraus and Holmberg, 1954; Baes et al., 1965). In Table 23.10, the constants  bnq are listed for the reactions:

Hydrolysis of actinide cations nTh

4þ

þ qH2 O !

Thn ðOHÞ4nq q

2549 þ qHþ

Of the complexes mentioned, Th2 ðOHÞ6þ is significant in chloride media 2 (Hietanen and Sillen, 1968; Baes and Mesmer, 1976; Milic, 1981) as well 10þ 6þ as Th2 ðOHÞ5þ 3 and Th6 ðOHÞ14 . In nitrate media, the complexes Th2 ðOHÞ2 , 9þ Th6 ðOHÞ15 and Th3 ðOHÞ7þ 5 predominate (Milic and Suranji, 1982). Constants for the hydroxo complexes are somewhat smaller in chloride and nitrate than in perchlorate media (Table 23.10). For values n  2 (equation (23.7)), equilibrium is more slowly attained than for mononuclear complex formation, resulting in formation of larger polymers before precipitation takes place. Direct structural determinations by X‐ray diffraction on hydrolyzed thorium nitrate solutions confirmed the existence of ˚ the dimer Th2 ðOHÞ6þ 2 (Johansson, 1968). The Th–Th distance is 3.99 A, i.e. exactly the same as in the solid Th2(OH)2(NO3)6(H2O)8 that contains dimers joined by double hydroxo bridges. As the hydrolysis reaction proceeds, complexes of higher nuclearity become prominent although the Th–Th distance ˚ . The hydrolytic complexes formed stays almost the same, approximately 3.94 A in concentrated nitrate solutions also contain nitrate ions coordinated as bidentate ligands. As expected, the number of nitrate ions coordinated per thorium decreases as hydrolysis becomes more extensive. Diffraction measurements by Johansson (1968) on hydrolyzed solutions of thorium perchlorate and chloride ˚ , implying that the same type of hydroxo‐ give the same Th–Th distance 3.94 A bridged complexes are formed in these media. 0 Rai et al. (1997) have reported a value of log Ksp ¼ 45:5 for amorphous 0 Th(OH)4 while Neck and Kim (2001) have proposed for a value of log Ksp of 0 –(47.0  0.8) (Table 23.11). The values of log Ksp of Th(IV) are larger than for

Table 23.10

Hydrolysis constants, log  bnq, for Th(IV) in different media.

T n, q

0 C 1 M NaClO4a

25 C 1 M NaClO4b

95 C 1 M NaClO4a

25 C 3 M NaCl c

25 C 3 M NaNO3d

1, 1 1, 2 2, 2 2, 3 4, 8 6, 14 6, 15

4.31 8.46 5.59 – 22.80 – 43.81

4.23 7.69 4.61 – 19.16 – 37.02

2.25 4.51 2.59 – 10.44 – 20.61

– – 4.69 8.73 – 36.37 –

– – 5.19 – – – 42.3

a b c d

Molality scale, Baes et al. (1965). Kraus and Holmberg (1954). Data recalculated from Hietanen and Silen (1968). Th3(OH)57þ also suggested with log  b35 ¼ 14.23, by Milic and Suranji (1982).

2550

Actinides in solution: complexation and kinetics

Table 23.11 Hydroxide complexation constants for An(IV) cations, I ¼ 0 Kim, 2001).

o log KspðcrÞ o log KspðamÞ o log b11 log bo12 log bo13 log bo14 log bo24 log bo4;12 log bo6;15 a b

M

(Neck and

Th(IV)

U(IV)

Np(IV)

Pu(IV)

54.2  1.3 47.0  0.8 11.8  0.2 22.0  0.6 31.0  1.0 38.5  1.0 59.1a 141.3 176.0

60.86  0.36 54.5  1.0 13.6  0.2 26.9  1 37.3  1 46.0  1.4 – – 196b

63.7  1.8 56.7  0.4 14.5  0.2 28.3  0.3 39.2  1 47.7  1.1 – – –

64.0  1.2 58.5  0.7 14.6  0.2 28.6  0.3 39.7  0.4 48.1  0.9 – – –

Calculated for I ¼ 0 from data in Moon (1989). log b6,15 for I ¼ 3 M NaClO4 (Baes and Mesmer, 1976).

the other An(IV) ions, presumably due to inclusion of polynuclear species of Th(IV) in the concentration of the soluble fraction (Neck and Kim, 2001). Evidence is scarce and conflicting on the hydrolysis of Pa4þ. Values of log  b11 ¼ 0.14 and log  b12 ¼ 0.52 have been measured for the first two mononuclear complexes in a 3 M (Li,H)ClO4 medium, by means of a solvent extraction method (Guillaumont, 1968). This would lead to about 50% of the protactinium present as unhydrolyzed Pa4þ in 1 M perchloric acid; however, other extraction measurements indicate that PaðOHÞ2þ is the predominant 2 species in 1 M acid (Lundqvist, 1974). The mononuclear complexes are predominant only in extremely dilute solutions. Polymers become significant at protactinium concentrations as low as 105 M. Hydrolysis of U(IV) is of concern only in reducing solutions as UO2þ 2 is the form present in oxic waters. The hydrolysis of U(IV) increases with increasing ionic strength and increasing temperature. Polynuclear hydrolytic species form readily and are likely to be present except in strongly acidic solutions or at very low concentrations of U(IV). Hydrolysis constant values were reported for ð4þnÞþ a series of polynuclear Uðnþ1Þ ðOHÞ3n complexes in 3 M (H,Na)ClO4 by Hietanen (1956) using a ‘coreþlinks’ model of thread‐like chains of U(OH)2U links. However, this model has fallen out of favor and reevaluation of these experiments showed that only U(OH)3þ and one polynuclear species,  U6 ðOHÞ9þ 15 , were required to reproduce the data with log b11 ¼ 2.1 and  log b6,15 ¼ 16.9 (Baes and Mesmer, 1976) except at the highest q:n ratios. This suggests that dinuclear or tetranuclear hydroxide complexes are less important for U(IV) than for Th(IV), but that hexanuclear U6 ðOHÞ9þ 15 and higher oligomers of U(IV) with n > 6 and q/n > 2.5 do form in millimolar solutions of U(IV) when the pH exceeds 1.5.

Hydrolysis of actinide cations

2551

As can be seen in the data in Table 23.11, the hydrolysis of Np(IV) is quite similar to that of Pu(IV) but greater than that of Th(IV) and U(IV). The ease of oxidation of Np(IV) to NpOþ 2 in non‐reducing solutions results in Np(V) being the dominant neptunium species in oxic waters. Although there has been little research on hydrolytic polymers of Np(IV), it is very probable that the same polymers observed for Th(IV), U(IV), and Pu(IV) are formed by Np(IV). Similar to the situation for Np(IV), the hydrolysis of Pu(IV) is difficult to investigate. At pH  1.0, tetravalent plutonium experiences hydrolysis and also oxidizes to PuOþ 2 . Disproportionation reactions also occur in these acid solutions to form Pu(III) and PuO2þ 2 . Preparation and maintenance of a solution with only Pu(IV) present is a challenge in any investigation of Pu(IV) behavior. This is reflected in the inconsistent data in a number of publications on Pu(IV) hydrolysis. The tendency of hydrolyzed plutonium(IV) to form intrinsic colloids or to sorb on other colloids is also a complicating factor. It has been demonstrated that colloidal Pu(IV) can be present at pH ¼ 0 to 1 and total Pu(IV) concentrations smaller than 103 M (Kim and Kanellakopulos, 1989). Ultrafiltration removes such colloids if a sufficiently small filter size is used. However, without filtration, the solubility data used to calculate solubility product constants may be more than an order of magnitude too large due to the presence of colloids. Hydrolyzed plutonium species also have a strong tendency to sorb to surfaces. The surfaces of equipment used for plutonium experimentation must be treated to minimize sorption in solubility and extraction measurements (Caceci and Choppin, 1983b). Freshly precipitated Pu(OH)4 · xH2O, dehydrates over time with the hydroxo bridges between neighboring plutonium ions converting to an oxo bridged structure (Fig. 23.9). The resulting crystalline PuO2 has a value of o log KspðcrÞ ¼ 64 (Table 23.11), compared to the value of the amorphous o o hydrate of log KspðamÞ ¼ 58:5. The measured value of log KspðcrÞ (64.0) reflects the reduced solubility of the aged precipitate; but measured solubilities in solutions of pH  7 are those of the amorphous solid, independent of whether An(OH)4(am) or AnO2(cr) were used for the initial solid phase. This can be attributed to the bulk crystalline solid being covered by a surface layer of the amorphous species. The amorphous form dissolves readily in strong acid but dissolution of the aged PuO2 precipitate is very difficult due to the strength of

Fig. 23.9 Conversion of amorphous Pu(OH)4 into crystalline PuO2 by loss of H2O.

2552

Actinides in solution: complexation and kinetics

Fig. 23.10 Fraction of mononuclear plutonium(IV) hydrolysis products as a function of pH in 1 M NaClO4 solution (Choppin, 2003).

the Pu–O bonding. Generally, aged PuO2(cr) must be contacted with an acidic oxidizing solution which converts the Pu(IV) to the much more soluble PuO2þ 2 species. The variation of mononuclear Pu(IV) hydrolytic species with pH is shown in Fig. 23.10. At pH 1.0, there are almost equal concentrations of Pu4þ, Pu(OH)3þ, and PuðOHÞ2þ 2 , demonstrating strong hydrolysis of Pu(IV). The fraction of polynuclear species present increases as the plutonium and/or the pH concentration increases. The hydrolysis constants of Pu(IV) indicate an extremely low value for soluble plutonium in neutral solutions. However, the net plutonium solubility is much larger than predicted ( 106 M) by the constants in Table 23.11, as it is due to the relatively high concentration of PuOþ 2 ( 106 to 107 M) in redox equilibrium with the ultratrace concentrations of soluble Pu(IV). 23.3.3

Pentavalent actinides

The protactinium(V) ion is a much stronger acid than other pentavalent actinides with log  b11 ¼ 4.5 in 3.5 M (Li, H)ClO4 (Guillaumont, 1968). In both the tetravalent and pentavalent states, protactinium hydrolyzes much more readily than do the other actinides. A structure different from the other actinyl(V) ions, e.g. PaOðOHÞþ 2 , with a strongly covalent protactinium–oxo bond has been proposed (Guillaumont et al., 1968).

Hydrolysis of actinide cations

2553

þ The tendency of UOþ 2 and PuO2 to disproportionate and the strong oxidaþ tion properties of AmO2 have led to few hydrolytic studies of these cations. NpOþ 2 is relatively stable, however, and is the most studied actinyl(V) species. Pentavalent neptunium does not hydrolyze in solutions with pH less than 8. Sullivan et al. (1991), Itagaki et al. (1992), and Neck et al. (1992) have discussed neptunium hydrolysis in some detail. A value of log  b11 for NpOþ 2 (ca. 8.85 at I ¼ 0) was reported by Baes and Mesmer (1976) and Schmidt et al. (1980). The stability of NpOþ 2 has led to its use as a chemical analog for pentavalent plutonium since PuOþ 2 is environmentally important at low concentrations of plutonium (Nelson and Lovett, 1978). A study of the thermodynamics of NpOþ 2 hydrolysis (Sullivan et al., 1991) in a solution of I ¼ 1.0 M (CH3)4NCl at T ¼ 25 C gave the following values for the  ! reaction NpOþ NpO2 OH: 2 þ OH

log b11 ¼ (9:26  0:06) DH11 ¼ (22:10  0:04) kJ mol1 DS11 ¼ (16  5) J K1 mol1 This value for  b11 indicates that at pH 9.26, NpOþ 2 is 50% hydrolyzed. Sullivan et al. (1991) estimated that logb11 for PuOþ 2 would be ca. 4.5, which indicates that PuOþ 2 does not form a significant fraction of hydroxide species until pH 9. Of all the plutonium oxidation states, the pentavalent state has the least tendency to hydrolyze (Choppin, 1991) and is most stable in basic solution (Peretrukhin et al., 1994). Unlike the case of NpOþ 2 , the redox potential of Pu(V)/Pu(IV) and the strong hydrolysis of Pu(IV) limit the concentration of PuO2þ in marine waters. Plutonium redox and sorption have been reviewed by Morse and Choppin (1991) and plutonium hydrolysis by Clark et al. (1995). 23.3.4

Hexavalent actinides

The hydrolysis of the uranyl cation, UO2þ 2 , has been studied more intensely than that of any other actinide cation, partially because the lower level of radioactivity of natural uranium allows use of a wider variety of techniques than for shorter lived actinides. Also, the hydrolysis of U(VI) forms a wide variety of polynuclear hydrolytic species, resulting in a quite complex chemistry (Table 23.12 and Fig. 23.11). The hydrolysis of the cations of the actinyl(VI) species decreases in the order 2þ 2þ 2þ 2þ UO2þ 2 > NpO2 > PuO2 , with a larger difference between NpO2 and PuO2 (Table 23.13). The actinide radial contraction with atomic number would lead to the opposite trend. The pattern is different also from that for the actinide(IV) ions where the order of acidities is U4þ > Np4þ < Pu4þ. For these ions, the unexpected decrease between U4þ and Np4þ is followed by a marked reversal at Pu4þ.

Actinides in solution: complexation and kinetics

2554

In very dilute solutions, 106 M U(VI), the hydrolysis of UO2þ 2 first forms mononuclear UO2 ðOHÞ2q species, but above this concentration UO2þ 2 exists q mainly in polynuclear species. Within wide ranges of pH and CM (metal concentration), the predominant complex is the dimer (ðUO2 Þ2 ðOHÞ2þ 2 ). As the pH increases, the trimer ðUO2 Þ3 ðOHÞþ 5 becomes prominent (Fig. 23.12). In chloride solutions ðUO2 Þ3 ðOHÞ2þ 4 is also formed. In concentrated solutions of low pH, (UO2)2OH3þ may be present. Other complexes which have been proposed to 4 2þ þ form are ðUO2 Þ3 ðOHÞ 7 ; ðUO2 Þ3 ðOHÞ10 ; ðUO2 Þ4 ðOHÞ6 ; ðUO2 Þ4 ðOHÞ7 ,

Table 23.12 Hydrolysis constants at I ¼ 0 and 25 C for formation of (UO2)n(OH)q species. o

o

n, q

log  bnq (Palmer and Nguyen‐Trung, 1995)

log  bnq (Guillaumont et al., 2003)

1, 1 2, 2 3, 5 3, 7 3, 8 3, 10

5.42  0.04a 5.51  0.04 15.33  0.12 27.77  0.09 37.65  0.14 62.4  0.3

5.25  0.24 5.62  0.04 15.55  0.12 32.2  0.8  

a

For I ¼ 0.10 M (KNO3).

Fig. 23.11 Structures of dinuclear uranyl hydroxide and oxide complexes.

Table 23.13 Hydrolysis constants, log  bnq, of hexavalent actinides, NpO22þand PuO22þ, in NaClO4 solution; T ¼ 25 C. PuO22þ

NpO22þ

n, q

I¼1M (Cassol et al., 1972a)

I¼1M (Kraus and Dam, 1949)

I¼1M (Cassol et al., 1972b)

I¼3M (Schedin, 1975)

1, 1 2, 2 3, 5 4, 7

5.17 6.68 18.25 –

5.71 – – –

5.97 8.51 22.16 –

– 8.23 – 29.13

Hydrolysis of actinide cations

2555

Fig 23.12 Speciation diagram (n,q) for the formation of ðUO2 Þn ðOHÞð2nqÞ . ½UO2þ q 2 total ¼ 4:75  104 M; T ¼ 25  C, from the data of Palmer and Nguyen‐Trung (1995) extrapolated to I ¼ 1.0 M. Table 23.14 Hydrolysis constants for UO22þ at different ionic strengths; T ¼ 25 C. I (M)

log  b11

logb11

0a 0.05 0.1 0.4 0.7 1.0

5.88 6.02 6.09 6.20 6.07 6.20

8.12 7.00 7.70 7.56 7.71 7.82

a

Extrapolated values.

þ and ðUO2 Þ5 ðOHÞ2þ 8 . The variation of the hydrolysis constant of UO2(OH) as a function of ionic strength is shown in Table 23.14. The existence of the dimer ðUO2 Þ2 ðOHÞ2þ has been confirmed by direct 2 determination of the species present in hydrolyzed uranyl(VI) chloride solutions ˚ berg, 1970). Even in the concentrated solutions (CM ¼ 3 M) used in these (A diffraction studies, the dimer is an important species at the lower ligand numbers investigated.

2556

Actinides in solution: complexation and kinetics

˚ , which is The average U–U distance in this concentrated solution is 3.88 A ˚ close to the distance of 3.94 A found in the solids [(UO2)2(OH)2Cl2(H2O)4] and ˚ berg, 1969; Perrin, 1976). [(UO2)2(OH)2(NO3)2(H2O)3]H2O (A 23.4 BONDING IN ACTINIDE COMPLEXES

Actinide ions in all common solution oxidation states (2þ to 6þ) are hard Lewis acids, and actinide–ligand bonds are predominantly ionic, as expected from the electropositive nature of the actinides. This is manifested in kinetically labile, non‐directional bonds, and a marked preference for binding to ligands via hard Lewis base donor atoms like fluorine or oxygen. The thermodynamic bond strengths of actinide–ligand complexes are determined primarily by electrostatic attraction and steric constraints. The electrostatic attraction between an actinide cation and a ligand is proportional to the product of the effective charges of the metal and ligand divided by the actinide–ligand distance. The steric constraints may arise from the properties of the actinide cation (ion size and presence or absence of actinyl oxygen atoms) or of the ligand (number and spatial relationship of donor atoms, size of the chelate rings, and flexibility of ligand conformations). 23.4.1

Ionicity of f‐element bonding

As a consequence of the predominantly ionic nature of the metal–ligand bonding in actinide complexes, the strength of the complexes and the associated chemistry are determined primarily by the effective charge of the actinide cation and of the coordinating ligands. Similar to the lanthanide 4f orbitals, the actinide 5f orbitals are well shielded from environmental influences and have little influence on bonding energies of the outer 6d orbitals, which dominate the radii values. The orbital energies and the radii of actinide ions in a given oxidation state vary slowly and smoothly across the actinide series. As a result, the types of actinide complexes formed and the strength of those complexes, as reflected by the stability constants, are relatively uniform within an oxidation state in comparison to transition metal complexes where covalence and ligand field stabilization energies can cause significant variations (Fig. 23.13). An important exception to the regularities of complex formation within an actinide oxidation state is Pa(V), which is the only pentavalent actinide that does not form the linear transdioxo actinyl(V) moiety, and whose chemistry is closer to that of pentavalent niobium and tantalum (Kirby, 1959) than that of AnO2þ cations. 23.4.2

Thermodynamics of bonding

The predominantly ionic nature of actinide–ligand bonding also accounts for the enthalpies and entropies of actinide complexation. The formation of inner sphere 1:1 actinide–ligand complexes in aqueous solution is characterized

Bonding in actinide complexes

2557

Fig. 23.13 Variation of the stability constants of metal complexes with ethylenediaminetetraacetate (edta4–) with ion size for the trivalent actinide ( ), trivalent lanthanide (○), and divalent fourth row metal cations ( ). Stability constant data from Martell et al. (1998) and Makarova et al. (1972) for I ¼ 0.1 M, and T ¼ 25 C. Rcation from Shannon (1976) for CN ¼ 6.

▪

▴

by positive values of the formation entropies, DS11, and of the values of the formation enthalpies, DH11, that vary from moderately endothermic (positive and unfavorable) to moderately exothermic (negative and favorable) depending on the charge and coordination number of the ligand. For simple ligands, the entropic component of the Gibbs energy tends to be the more important in determining the magnitude of the Gibbs energy change (DG) upon complexation and, hence, of the equilibrium constant. In aqueous media, the entropy changes (DS) for formation of 1:1 lanthanide and actinide complexes arise primarily from the partial dehydration of the metal and ligand that is associated with the formation of an inner sphere complex. For a given ligand, the DS values tend to increase as the effective charge of the actinide ion increases, as expected for electrostatic bonding (Laidler, 1956). Also, since the complexation entropies are linked to dehydration of the metal and ligand, characteristic values of DS/n exist for a given actinide oxidation state and a particular class of ligands, as shown for actinide carboxylate complexation in Table 23.15 (n can be either the number of donor groups bound to the cation or the number water molecules displaced from the inner coordination sphere of the cation).

Actinides in solution: complexation and kinetics

2558

Table 23.15 Average entropy change per coordinated carboxylate group, n, for carboxylate, polycarboxylate, and aminopolycarboxylate ligands (standard deviation 10%). Cation

Average DS/n (JK1 mol1)

References

Th4þ UO22þ Am3þ Sm3þ NpOþ2 Ca2þ

96 73 62 59 27 25

Martell et al. (1998) Martell et al. (1998) Rizkalla et al. (1989) Choppin (1993) Jensen and Nash (2001) Choppin et al. (1992a)

23.4.3

Coordination numbers

Typical coordination numbers of transition metal ions, where d‐orbitals participate in the formation of directional covalent bonds, range from four to six, with well‐defined stereochemistry (tetrahedral, square planar, octahedral, etc.). In contrast, most actinide–ligand bonds are characterized by a very small degree of covalence, if any, and the coordination geometry of the complexes is not determined by the directionality of the bonding overlap of the actinide and ligand orbitals. Combined with the somewhat larger size of actinide cations relative to the 3d and 4d transition metal cations, this results, for actinide cations, in larger and variable coordination numbers, which are determined by the maximum number of ligands (including Lewis base solvent molecules) that can fit around the actinide. Increasing oxidation state decreases the ionic radii of the actinide ions (Shannon, 1976), thus favoring lower coordination numbers than are observed for actinides in the lower oxidation states. In water, or in other oxygenated solvents with similar steric demands, typical inner sphere coordination numbers of actinide ions range between seven and nine (including the ‐yl oxygen atoms of the actinyl cations) with coordinated solvent molecules filling space not occupied by other ligands. The size and shape of the ligands are very important in determining the exact coordination number of actinide cations. Coordination numbers as low as four or five, for example in U(NPh2)4 (Reynolds et al., 1977) or UO2(p‐tert‐butylhexahomotrioxacalix[3]arene)– (Masci et al., 2002), are observed for bulky ligands in low polarity media. In contrast, coordination numbers of 10 or 12 are not uncommon in solid state and solution‐phase complexes containing small, bidentate ligands, such as CO2 and NO 3 3 [e.g. ten‐coordinate 6 AnðCO3 Þ5 (Clark et al., 1995) and 12‐coordinate AnðNO3 Þ2 6 (Ryan, 1960; Sˇcavnicar and Prodic, 1965)]. The constraints imposed by the presence of the two oxo groups in the linear, 2þ pentavalent AnOþ 2 and hexavalent AnO2 cations provide an inherent, steric limitation on the number of ligand donor groups that can form bonds to the actinyl cations. The stability constants of the complexes of actinide cations in

Bonding in actinide complexes

2559

each of the common oxidation states with a series of carboxylate and aminocarboxylate ligands are presented as a function of the number of potential donor groups present in each ligand in Fig. 23.14. For the spherical An(III) and An(IV) cations, which lack the ‐yl oxygen atoms of the higher actinide oxidation states, the stability constants of the metal–ligand complexes increase regularly with the increased number of donor groups in the ligand. The size, spherical symmetry, and lack of strong, directional covalent bonding in these complexes allow An(III) and An(IV) cations to accommodate polydentate ligands that form multiple chelate rings. In contrast, the linear dioxo structure 2þ of AnOþ 2 and AnO2 cations constrains the interactions with ligands to the

Fig. 23.14 Effect of the steric constraints imposed by actinyl oxygen atoms of neptunyl(V) and uranyl(VI) on the stability constants of the carboxylate and aminocarboxylate ligands as compared to trivalent and tetravalent actinides. Data from Martell et al. (1998), Rizkalla et al. (1990a), and Tochiyama et al. (1994).

2560

Actinides in solution: complexation and kinetics

plane perpendicular to the actinyl oxygens (referred to as the equatorial plane hereafter). Generally, this limits the number of bound donor groups in a single ligand to three or four for the actinyl ions. As shown in Fig. 23.14, the 2þ thermodynamic stability of the complexes of AnOþ cations 2 and AnO2 increases regularly until three donor groups are present in a given ligand. The presence of additional (more than three) donor groups causes no significant increase in the stability constants of the actinyl complexes because the additional donors do not form bonds with the actinyl cation. Interesting exceptions to this general observation are the pentacoordinate calixarene‐based ligands (Shinkai et al., 1987; Guilbaud and Wipff, 1993a), which have the proper geometry to be strong and highly selective complexants for the actinyl(VI) ions. 23.4.4

Steric effects in actinyl bonding

The ‘‐yl’ oxygen atoms can interfere with the complexation of rigid ligands, even if the ligand contains three or fewer donor atoms, by restricting ligand donor atoms to bonding only in the equatorial plane of the actinyl ion. In rigid ligands this restriction can cause torsional strain within a bound ligand, or, if the ligand is too large to be contained in the equatorial plane, portions of the ligand and the actinyl oxygens may come into steric conflict. This was reported for the uranyl(VI) complexes of the relatively rigid ligand tetrahydrofuran‐2,3,4,5‐tetracarboxylic acid, for which the stability constant of the uranyl complex is two orders of magnitude smaller than expected from the stability constants of the complexes of the ligand with the sterically undemanding trivalent lanthanide cations or the uranyl complexes of similar, but more flexible, ligands (Morss et al., 2000). When steric constraints are not important, the strength of actinide–ligand interactions are primarily governed by electrostatic attraction. Increasing effective charge and decreasing ion size (i.e. increasing charge density) of either the actinide cation or the ligand favor stronger bonds, as discussed in Section 23.6. For a given oxidation state, the radii of actinide ions become progressively smaller with increasing atomic number, imparting a larger charge density to the actinide cation and, generally, making the complexes of the heavier actinides progressively more stable. Unfortunately, little data is available for elements heavier than curium, but the measured stability constants support such correlations. 23.4.5

Relative strength of complexation

For a given ligand, the strength of the actinide complexes usually increases in the order 3þ 4þ AnOþ AnO2þ 2 < An < 2 < An

when steric effects are not important. Obviously the order tracks neither the oxidation state nor the formal charge of the actinide cations. While the overall, formal charges of the actinyl(V) and actinyl(VI) cations are þ1 and þ2,

Bonding in actinide complexes

2561

respectively, the order of the stability constants implies that the effective charge (Zeff) felt by a ligand bound to the actinyl cations in the equatorial plane is considerably larger. This suggests that the ‐yl oxygen atoms of the actinyl(V) and actinyl(VI) cations retain a partial negative charge. Assuming completely electrostatic bonding (except for the actinyl oxygens) and that the effective charges of Ca2þ, Nd3þ, Am3þ, and Th4þ are equal to their formal charges, the effective charge felt by ligands bound to pentavalent and hexavalent actinyl cations were estimated empirically. For NpOþ 2 , Zeff was estimated as þ(2.2  0.1) (Choppin and Rao, 1984). For AnO2þ 2 ðAn ¼ U; Np; PuÞ, cations this approach estimated Zeff between þ3.0 and þ3.3, depending on the cation and the estimation procedure (Choppin and Unrein, 1976; Choppin, 1983; Choppin and Rao, 1984). In the series of AnO2þ 2 –fluoride complexes, the derived value of Zeff decreases with increasing atomic number. These experimental Zeff values agree with those from theoretical calculations (Walch and Ellis, 1976; Matsika and Pitzer, 2000), providing theoretical foundations for the observed order of actinide complex stabilities. The stability constants of a few carboxylate complexes of No2þ have been reported (McDowell et al., 1976). They are smaller than those of the actinyl(V) cations, and are similar to those observed for Ca2þ or Sr2þ. This suggests that the divalent actinides have the lowest effective charge and form the weakest complexes of any actinide oxidation state. 23.4.6

Covalent contribution to bonding

Although an ionic model adequately describes most actinide complexes in solution, measurable covalent bonding is present in the actinide–ligand bonds of some compounds. The most prevalent example of covalence in actinide bonding comes from actinide–ligand multiple bonds (Kaltsoyannis, 2000; Denning et al., ˚ ) O¼An¼O bonds in the linear dioxo 2002), particularly the short (ca. 1.7–1.8 A actinyl ions of the pentavalent and hexavalent light actinides, AnOþ 2 and AnO2þ ðAn ¼ U; Np; Pu; AmÞ. Other well‐characterized examples of acti2 nide–ligand bonds with some degree of covalence are found in actinide–organometallic complexes (Cramer et al., 1983; Brennan et al., 1987, 1989). More surprising examples come from computation (Pepper and Bursten, 1991) and experiments that suggest that a measurable covalent contribution is present even in An–F bonds, the actinide–ligand bonds expected to be the most strongly ionic. Bleaney et al. (1956) and Kolbe and Edelstein (1971) observed superhyperfine splitting, attributable to covalence, in the EPR of trivalent uranium and plutonium fluorides, which are present as cubic AnF5 8 in a fluorite host. In contrast, superhyperfine splitting was not observed for the equivalent compounds of the trivalent lanthanides doped in fluorite, implying that the An–F bonds have measurably greater covalent character than Ln–F bonds. However, the presence of some covalence in the actinide–ligand bonds does not diminish the overarching importance of ionic interactions in the formation of these bonds.

2562

Actinides in solution: complexation and kinetics

In solution, the best evidence for some degree of covalence in actinide–ligand bonds comes from the thermodynamic differences in the complexes of the trivalent lanthanides and the trivalent actinides with soft donor ligands (i.e. ligands containing N, S, or halide donors other than F–). The complexes formed by An3þ cations and Ln3þ cations with hard donor, oxygen‐based, ligands (carboxylates, organophosphates) are nearly indistinguishable for Ln3þ and An3þ ions with similar ionic radii (e.g. Am3þ and Pm3þ). However, as first observed by Diamond et al. (1954), An3þ cations form thermodynamically more stable complexes with soft donor ligands than the equivalent Ln3þ cations do. This deviation from predictions based solely on electrostatic bonding has been interpreted as indicating slightly greater covalence in the actinide–soft donor ligand bond. The stability constants of aqueous complexes of trivalent lanthanide and actinide cations with some representative hard and soft donor ligands, as well as ligands containing both hard and soft donor groups, are summarized in Table 23.16. 23.4.7

Soft ligand bonding

A greater degree of covalence in the bonds between an actinide ion and soft donor ligand should also be reflected in more exothermic complexation enthalpies, relative to the equivalent lanthanide complexes. Significant differences in the enthalpies of metal–nitrogen bonds were not observed in the aminocarboxylate complexes of americium, curium, and europium (Rizkalla et al., 1989). However, large differences in the complexation enthalpies of trivalent lanthanide and actinide cations consistent with enhanced covalence in actinide–soft donor bonds have been reported for ligands containing only soft donor atoms in both aqueous and organic solutions (Zhu et al., 1996; Jensen et al., 2000a; Miguirditchian, 2003). The preference of actinide ions for softer donor ligands is the common basis for successful chemical separations of the trivalent actinides from the trivalent lanthanides (Nash, 1993a). Although actinide–soft donor bonds are thermodynamically stronger than the corresponding lanthanide–soft donor bonds, neither series of f‐element cations forms particularly strong complexes with ligands containing only soft donors, as illustrated by the stability constants in Table 23.16. The likelihood of observing complexes between actinide ions and soft donor ligands is further reduced in aqueous solution by the high background concentration of the hard Lewis base H2O, 55 mol L1. Thus, forming actinide complexes with soft donor ligands in aqueous solution requires either high concentrations of the soft ligand, multiple soft donor sites within a single ligand, or the presence of both hard and soft donors within the same ligand. Soft donor binding in aqueous solution is also encouraged when the soft donor groups are relatively acidic, which allows the soft donor ligand to compete with hydrolysis reactions. As a result, actinide soft donor reactions are most easily observed in non‐aqueous solvents.

Inner versus outer sphere complexation

2563

Table 23.16 Stability constants of trivalent lanthanide and actinide cations of similar ionic radius with oxygen donor and nitrogen donor ligands in aqueous NaClO4, T ¼ 25 C. ˚ , Pm3þ ¼ 1.233 A ˚ , Sm3þ ¼ (Crystal radii according to Shannon (1976) Nd3þ ¼ 1.249 A ˚ for CN ¼ 8.) ˚ , Am3þ ¼ 1.230 A 1.219 A logb1q

Complex formed a

Nd

Hard donors M(ac)2þ 1.92 M(ox)þ M(ox)2

5.18 (Pm) 8.78 (Pm)

Sm 2.03 – –

Ligand donor atoms

I (M )

References

1.96

1 or 2 O

2

5.25 8.85

2O 4O

0.1 0.1

Grenthe (1964); Choppin and Schneider (1970) Stepanov (1971) Stepanov (1971)

Am

Both hard and soft donors M(edta)– 15.75 16.20

16.77

4 O, 2 N

0.5

M(dtpa)2–

5 O, 3 N

0.5

1N 2N 3N 6N 3N

–b –b –b 0.1 1c

Soft donors MN2þ 3 MðN3 Þþ 2 M(N3)3 M(tpen)3þ M(tptz)3þ

20.09

20.72

21.12

0.4 0.6 0.7

– – – 4.70 3.4

1.3 1.6 1.4 6.73 4.2

2.8

Gritmon et al. (1977); Rizkalla et al. (1989) Gritmon et al. (1977); Rizkalla et al. (1989) Musikas et al. (1983) Musikas et al. (1983) Musikas et al. (1983) Jensen et al. (2000a) Musikas (1984)

a ac, acetate; ox2, oxalate; edta4, ethylenediaminetetraacetate; dtpa5–, diethylenetriaminepentaacetate; tpen, N,N,N0 ,N0 ‐tetrakis(2‐pyridylmethyl)ethylenediamine; tptz, 2,4,6‐tri(2‐pyridyl)‐1,3,5‐ triazine. b Ionic strength not given. c 1 M KCl.

In summary, actinide–ligand bonding, though primarily ionic, should be considered as intermediate between the strongly ionic bonding observed in lanthanide complexes and the more covalent bonding found in transition metal complexes. The exact behavior of an actinide ion is determined by its oxidation state, the hard or soft characteristics of the ligand, and the position of an actinide element within the actinide series, with the actinides becoming more lanthanide‐like with increasing atomic number. 23.5 INNER VERSUS OUTER SPHERE COMPLEXATION

Although the concept of outer sphere complexation was introduced by Werner (1913) and the theory first given a mathematical base by Bjerrum (1926) progress in understanding the factors involved in the competition between inner and outer sphere complexation was slow.

2564

Actinides in solution: complexation and kinetics

The term ‘outer sphere complex’ refers to species in which the ligand does not enter the primary coordination sphere of the cation but remains separated by at least one solvent molecule. Such species are known also as ‘solvent separated’ ion pairs to distinguish them from inner sphere complexes in which the bonding involves direct contact between the cation and the ligand. Some ligands cannot displace the water and complexation terminates with the formation of the outer sphere species. Actinide cations have been found to form both inner and outer sphere complexes and for some ligands, both types of complexes may be present simultaneously. For labile complexes, it is often quite difficult to distinguish between inner and outer sphere complexes. Adding to this confusion is the fact that stability constants for such labile complexes determined by optical spectrometry are often lower than those of the same system determined by other means such as potentiometry, solvent extraction, etc. This has led some authors to identify the former as ‘inner sphere’ stability constants and the latter as ‘total’ stability constants. However, others have shown that this cannot be correct even if the optical spectra of the solvated cation and the outer sphere complex are the same (Beck, 1968; Johansson, 1971). Nevertheless, the characterization and knowledge of the formation constants of outer sphere complexes are important as such complexes play a significant role in the Eigen–Tamm mechanism for the formation of labile complexes (Eigen and Wilkins, 1965). The Eigen–Tamm mechanism assumes rapid formation of an outer sphere association complex (i.e. an ion pair) and the subsequent rate‐determining step in which the ligand displaces one or more water molecules, x x MðH2 OÞzþ ! MðH2 OÞzþ ! MðH2 OÞq1 Lzx þ H2 O q þL q - - -L

The conversion of the outer sphere complex to the inner sphere complex is the rate‐determining step and is dependent on the equilibrium concentration of the outer sphere complex. Consequently, calculations of rate constants by the Eigen model involve estimation of the stability constants of the outer sphere species. Actinide cations form labile, ionic complexes of both inner and outer sphere character and serve as useful probes to study the competition between inner and outer sphere complexation due to ligand properties. It has been proposed (Choppin and Strazik, 1965; Choppin and Ensor, 1977; Khalili et al., 1988) that the thermodynamic parameters of complexation can be used as a criterion for evaluation of inner versus outer sphere complexation. For outer sphere complexes, the primary hydration sphere is minimally perturbed. As a result, an exothermic enthalpy results from the cation–ligand interaction while the entropy change can be expected to be negative since the ordering of ionic charges is not accompanied by a compensatory disordering of the hydration sphere. By contrast, when inner sphere complexes are formed, the primary hydration sphere is sufficiently disrupted that this contribution to the entropy and enthalpy of complexation frequently exceeds that of the cation–ligand

Inner versus outer sphere complexation

2565

interaction and the result is an endothermic enthalpy and a positive entropy change. These considerations have led, for trivalent lanthanides and actinides in their 1:1 complexes (i.e., ML), to assignment of predominately outer sphere  character to the Cl, Br, I, ClO 3 , NO3 and sulfonate complexes and of inner   sphere character to the F , IO3 and SO2 4 complexes (Choppin, 1971). The experimental, total, stability constant, bexp is related to bos and bis by bexp ¼ bis þ bos where bis and bos are the stability constants for inner and outer sphere formation, respectively. The effect of cationic charge on the equilibrium between inner and outer sphere complexation by the halate and chloroacetate anions has been investigated (Rizkalla et al., 1990b; Choppin et al., 1992b). In the case of halate systems, the entropy change for the complexation with monochlorate (pKa(HClO3) ¼ –2.7) was considered to indicate 100% outer sphere character while that of the monoiodate (pKa(HIO3) ¼ 0.7) led to the assignment of a predominately inner sphere character. The data for the 1:1 europium bromate (pKa (HBrO3) ¼ –2.3) complex was interpreted to show a mixed nature with the outer sphere character more dominant. For thiocyanate complexes, stepwise stability constant patterns are reported for An(III) (Harmon et al., 1972a) and AnO2þ 2 (Ahrland and Kullberg, 1971a) to be K1 > K2 < K3, indicating predominant outer sphere nature of the 1:1 and 1:2 complexes which changes to inner sphere for the 1:3 system. For An(IV), the pattern (Laubscher and Fouche´, 1971) is K1 > K2 > K3 < K4, indicating that inner sphere complexation occurs only in the 1:4 species. A series of related ligands, acetate and chloroacetates (Ensor and Choppin, 1980), was studied by solvent extraction and calorimetry to ascertain the relationship of ligand pKa and inner versus outer sphere character. The relationship of experimental values of log b11 with the ligand pKa as well as the relationships of the calculated values of log bis and log bos is shown in Fig. 23.15. Acetate (ac–, pKa ¼ 4.8) formed inner sphere complexes and trichloroacetate (Cl3ac, pKa ¼ 0.5), outer sphere complexes. The inner sphere nature increased with pKa (Rinaldi et al., 1979) with estimates for inner character of 100% La(ac)2þ, 50% La(Clac)2þ, 22% La(Cl2ac)2þ, and 0% La(Cl3ac)2þ. These values agreed satisfactorily with calculations using a modified Born equation (Choppin and Strazik, 1965). For the uranyl(VI) system, similar calculations (Khalili et al., 1988) provided the following values for the percent inner sphere character: UO2(ac)þ, 100%; UO2(Clac)þ, 42%; UO2(Cl2ac)þ, 9%; UO2(Cl3ac)þ, 4%. The data are consistent with an increased tendency to outer sphere complexation for the same cation as the ligand pKa values decrease since the more acidic ligand is less competitive with hydration. Conversely, there is a stronger tendency to outer sphere complexation with increased charge on the metal cation, reflecting the increased hydration strength for higher cation charge. From acetate/haloacetate 1:1 complexation data with An3þ and AnO2þ 2 , it

2566

Actinides in solution: complexation and kinetics

Fig 23.15 Dependence of the experimentally measured total stability constant, bexp, and the calculated inner (bis) and outer (bos) sphere stability constants for Am(III) complexes on the acidity of Cl3–nHnCCO2H ligands.

was estimated that equal amounts of inner and outer sphere complexation would be observed for carboxylate ligands of pKa 2.83.0 (Khalili et al., 4þ 1988). For NpOþ cations, equal amounts of inner and outer sphere 2 and Th complexes would be present in 1:1 complexes with carboxylate ligands of pKa 1.1 and 4.2, respectively (Choppin and Rizkalla, 1994). The thermodynamic data of Eu(halate)2þ and Th(halate)3þ complexation are listed in Table 23.17. The entropy for the monochlorate (pKa HClO3 ¼ 2.7) was interpreted as indicating 100% outer sphere character with Eu(III) and a predominance of it with Th(IV). The values for the monoiodate (pKa HIO3 ¼ 0.7) complexes led to assignment of a predominately inner sphere character for both Eu(III) and Th(IV) (Choppin and Ensor, 1977). The data for the 1:1 europium complex with bromate (pKa HBrO3 ¼ 2.3) were interpreted as showing a mixed nature with more outer sphere character. Values of 70, 80, and 85% (10%) were estimated as the percent of outer sphere nature in the 3þ þ EuBrO2þ 3 ; UO2 BrO3 , and ThBrO3 complexes (Rinaldi et al., 1979; Ensor and Choppin, 1980; Khalili et al., 1988). This is consistent with increased outer sphere nature with larger effective charge of U in UO2þ 2 . This pattern is likely due to the increase in hydration strength as the cationic charge increases.

Correlations

2567

Table 23.17 Thermodynamic parameters for halate complexation. Complex

log b11

DG (kJ mol1)

DH (kJmol1)

DS (JK1 mol1)

% inner sphere

EuClO32þ EuBrO32þ EuIO32þ ThClO33þ ThBrO33þ ThIO33þ

0.04 0.59 1.14 0.14 0.63 2.49

0.25 3.39 6.53 0.78 3.61 14.24

6.3 2.5 11.0 2.4 2.5 6.5

20 3 59 11 20 70

0 ca. 30 100 0 ca. 15 100

23.6 CORRELATIONS

Actinide cations interact with hard Lewis bases through strongly ionic bonds whose thermodynamic strength is dependent of the charges of the actinide cations and of the ligands and on any steric constraints imposed by the actinide ion or ligand (see Section 23.4). In the absence of steric effects, the predominance of ionic bonding in actinide complexes and the regular decrease in the size of actinide ions within an oxidation state as the atomic number increases are the basis for the systematics of actinide–ligand complexation, which can be exploited for important predictive capabilities. The stoichiometries, structures, and stability constants of actinide–ligand complexes in solution can often be predicted from the chemistry of related ligands or of other metal ions, including those in other oxidation states. Such empirical correlations can provide fairly accurate estimates of the properties of actinide–ligand complexes, although no correlation is universally applicable to all ligands, actinide ions, or actinide oxidation states because of electronic effects (e.g. covalency) or steric constraints. Given the large number of potential ligands, the ability to use such correlations to predict the strength of the interaction between a metal ion and a ligand accurately is very useful. The difficulties in working with radioactive materials further increase the value of these correlations. The interactions of Hþ and Anzþ with ligands are governed primarily by the same physical forces, electrostatics. Consequently, ligand basicity is often a good predictor of the relative thermodynamic strength of the interactions of ligands with actinide cations. In practice, ligand basicity may be expressed either in the Brønsted sense as the affinity of a ligand for protons or, more generally, as the affinity of a ligand for Lewis acids (i.e. other metal cations). Since both the pKa and the logarithmic stability constant of a metal–ligand complex (MnLq), log bnq, are directly proportional to the Gibbs energy of reaction, DGprotonation ¼ 2:303RT pKa

ð23:9Þ

DGcomplexation ¼ 2:303RT log bnq

ð23:10Þ

2568

Actinides in solution: complexation and kinetics

the correlation of stability constants with ligand basicity falls in the general category of linear Gibbs energy correlations. The database of ligand pKa values is the most extensive set of data available for correlating and interpreting actinide–ligand bonding. The logarithm of the stability constant for actinide–ligand complexation is expected to be directly proportional to the basicity of the ligand, expressed as the pKa, within a series of ligands containing a single bonding functionality where variations in steric effects are negligible. Examples of this type of correlation for the formation of þ 1:1 UO2þ 2 :monocarboxylate complexes and of both 1:1 and 1:2 NpO2 :b‐ diketonate complexes are shown in Fig. 23.16. The monocarboxylic acids could behave as monodentate or bidentate ligands (Howatson et al., 1975; Denecke et al., 1998; Rao et al., 2002), while the b‐diketonate ligands form bidentate six‐membered chelate rings with the neptunyl(V) ion. The deviation of the UO2(O2CCHCl2)þ complex from the correlation likely arises from the formation of a mixture of inner and outer sphere dichloroacetate complexes (Section 23.5), while the other ligands form only inner sphere complexes with the uranyl(VI) cation.

Fig. 23.16 Linear Gibbs energy correlation of the stability constants of 1:1 uranyl(VI): monocarboxylate (○), and 1:1 ( ) and 1:2 (□) neptunyl(V):b‐diketonate complexes with the ligand basicity. Data from Martell et al. (1998), Gross and Keller (1972), and Sekine et al. (1973). (1) Dichloroacetate, (2) glycine, (3) chloroacetate, (4) 2‐furoate, (5) 2‐thenoate, (6) formate, (7) thioglycolate, (8) 3,5‐dihydroxybenzenecarboxylate, (9) phenylacetate, (10) acetate, (11) propionate, (12) hexafluoroacetylacetone, (13) 2‐furoyltrifluoroacetone, (14) trifluoroacetylacetone, (15) 2‐thenoyltrifluoroacetone, (16) difuroylmethane, (17) 2‐thenoylacetone, (18) 2‐furoylacetone, (19) acetyacetone, (20) benzoylacetone.

▪

Correlations

2569

Using the pKa to represent ligand basicity is straightforward for simple ligands, such as monocarboxylate and b‐diketonate ligands (Fig. 23.16), where all of a ligand’s donor atoms are available for coordination once the single ionizable proton is removed from the ligand. The correlation of actinide complexation constants to ligand basicity is more complicated when the ligand contains multiple basic sites or can form more than a single chelate ring. Summing the pKa values for each of a ligand’s donor groups yields a single parameter representing an effective, total basicity. These values, SpKa, usually correlate fairly well with the stability constants, log b11, of an actinide ion, as shown in Fig. 23.17. Such correlations between stability constants and SpKa values is the strongest within groups of related ligands, as similarity of the structural features of the complex is more likely. In some cases, all of the

Fig. 23.17 Linear Gibbs energy correlation between the stability constants and total ligand basicity for (a) uranyl(VI) and (b) thorium(IV) complexes. (1) Dichloroacetate, (2) chloroacetate, (3) sulfate, (4) nicotinate, (5) ascorbate, (6) acetate, (7) glycolate, (8) thiodiacetate, (9) adipate, (10) fluoride, (11) glutarate, (12) succinate, (13) lactate, (14) a‐hydroxyisobutyrate, (15) maleate, (16) phthalate, (17) malonate, (18) picolinate, (19) oxalate, (20) oxydiacetate, (21) acetylacetonate, (22) citrate, (23) oxinate, (24) tropolonate, (25) iminodiacetate, (26) N‐(2‐hydroxyethyl)iminodiacetate, (27) N‐ methyliminodiacetate, (28) nitriliotriacetate, (29) N‐(2‐hydroxyethyl)ethylenediamine‐N, N0 ,N0 ‐triacetate–hedta3–, (30) ethylenediaminetetraacetate–edta4–, (31) ethylenediamine‐ N,N0 ‐diacetate–edda2–, (32) hydroxide, (33) monoprotonated ethylenediaminetetraacetate– H(edta)3–, (34) sulfoxinate, (35) carbonate, (36) thenoyltrifluoroacetonate, (37) trans‐1, 2‐diaminocyclohexane‐N,N,N0 ,N0 ‐tetraacetate–dcta4–, (38) diethylenetriaminepentaacetate–dtpa5–, (39) tetra(2‐pyridylmethyl)ethylenediamine–tpen.

2570

Actinides in solution: complexation and kinetics

potential donor atoms represented by the individual pKa values do not bind the metal ion, either because of actinide‐ or ligand‐based steric considerations, or because the donor atoms are not well matched to actinide chemistry (e.g. sulfur donors in aqueous solution). For such complexes, the actual An–L stability constant is smaller than predicted. In other cases, the assumption of An–L bonds being primarily ionic may be invalid, or the presence of a ligand containing donor atoms that are Lewis bases without appreciable Brønsted basicity (e.g. ether oxygens), would result in an An–L stability constant that is greater than that predicted by the SpKa correlation. Deviations from the expected correlation between a measured stability constant and SpKa for a particular An–L pair can be a useful diagnostic for determining the denticity or coordination modes of ligands in actinide complexes (Jensen and Nash, 2001). The complexation of Np(V) by thiodiacetic acid (H2tda) in 0.5 M NaClO4 solution (Rizkalla et al., 1990a) is a good example of this approach. Thiodiacetic acid (Fig. 23.18), is a potentially tridentate ligand, capable of forming two five‐membered –S–C–C–O– chelate rings with metal ions of the proper size. However, the low affinity of actinide ions for ligands with sulfur donor atoms and the low effective charge of the neptunyl(V) cation, þ2.2, combine to keep the ligand from forming such chelate rings. Based on the SpKa (3.07 þ 4.00 ¼ 7.07), the correlation predicts a stability constant for NpO2(tda)– of logb11 ¼ 3.0. A favorable Np–S interaction yielding a tridentate complex with two –S–C–C–O– chelate rings would make the stability constant still larger. However, the reported stability constant is much smaller (log b11 ¼ 1.2), indicating that the complex is not tridentate. The magnitude of the stability constant does match those of NpOþ 2 complexes with monofunctional carboxylic acid ligands (log b11 ¼ 0.7–1.3), and is only slightly larger than

Fig. 23.18

Ligand structures.

Correlations

2571

the value predicted, log b11 ¼ 0.8, by considering NpOþ 2 complexation only at the most acidic site where pKa ¼ 3.07. The agreement of the experimental stability constant with that for a single ligand pKa leads to the conclusion that there is no significant Np–S interaction and that tda2 binds to NpOþ 2 only through a single carboxylate group. The lack of a Np–S bond also is consistent with the crystal structure of NaNd(tda)2, in which only Nd–O bonds are observed (Kepert et al., 1999). The uncertainty in the nature of the interactions of certain actinide ions with particular ligands can make it difficult to understand or predict actinide complexation chemistry based solely on the basicity of a ligand, as the size and charge of the proton are very different from those of the actinide ions in solution. Using the Gibbs energies of complexation for other metal ions instead of pKa values can overcome this limitation if the Lewis acids (metal ions) used for the correlations impose steric constraints, electrostatic fields, and degrees of covalency similar to those of the actinide ions under consideration. Since the lanthanide cations form metal–ligand bonds that are predominantly ionic and are of approximately the same size as actinide cations, they often are good models for actinide–ligand complexes. Hard transition metal cations, such as Fe3þ or Zn2þ (Hancock and Martell, 1989; Jarvis and Hancock, 1991), and alkaline earth cations, such as Ca2þ (Choppin et al., 1992a), also can be used, with care, in some actinide–ligand bonding correlations. Figs. 23.18 and 23.19 compare the stability constants of actinide–ligand complexes of actinide cations in each of the common solution oxidation states (3þ, 4þ, 5þ, and 6þ) with the stability constants of the complexes formed by the same ligands with the trivalent lanthanide cations Nd3þ or Sm3þ. The correlations are considerably 4þ better than for the stability constants of the UO2þ 2 –ligand or Th –ligand complexes with the SpKa values depicted in Fig. 23.17. However, as discussed in Section 23.4, the correlation fails when the assumption of similar steric constraints is incorrect for the complexes of actinyl ions with polydentate ligands containing more than three donor groups per ligand (Figs. 23.19a and 23.20a). In contrast, when the NpðVÞOþ 2 complexes are compared to the complexes of AnðVIÞO2þ cations, which are subject to similar steric constraints, 2 the stability constants of polydentate ligands track the correlation well (Fig. 23.19b). The stability constants of An(IV) cations, represented by Th4þ, and of An(III) cations, represented by Am3þ, track the Gibbs energies of trivalent lanthanide (Nd3þ or Sm3þ) complexation well (Fig. 23.20), indicating that any steric constraints imposed on the ligands by the trivalent and tetravalent actinide cations are similar to those of the lanthanide cations. However, one complex obviously deviates from the correlation. The stability constant of the Am (tpen)3þ complex (Ligand #39, tetra(2‐pyridylmethyl)ethylendiamine, Fig. 23.18) is two orders of magnitude larger than expected based on the stability constant of the Sm(tpen)3þ complex, even though the larger radius of Am3þ suggests that the stability constant should be smaller for Am(tpen)3þ.

2572

Actinides in solution: complexation and kinetics

Fig. 23.19 Correlation between the stability constants of neptunyl(V) complexes and the stability constants of the complexes of (a) the trivalent lanthanides Nd3þ ( ) and Sm3þ (□), 2þ and (b) the hexavalent actinides UO2þ 2 (●) and PuO2 (○). See Fig. 23.17 for the ligands’ numerical identities.

▪

˚ for coordination number 8, while for (The crystal radius of Am3þ is 1.230 A ˚ under the same conditions [Shannon, 1976].) All six of the Sm3þ it is 1.219 A potential nitrogen donor atoms in the tpen ligand appear to be coordinated to both Ln3þ and An3þ cations, with some coordinated water molecules remaining in the inner coordination sphere of the metal ions in aqueous solution (Jensen et al., 2000a). Based on the similar size and coordination environment of the two cations, steric constraints would be expected to play no role in this deviation of the Am3þLn3þ correlation. The greater stability of the Am3þ–tpen complex most likely arises from an enhanced degree of covalence in the An–N bonds as compared to the Ln–N bonds (Choppin, 1983). The size of the ligand chelate rings can also affect the stability of actinide– ligand complexes. Examining the Gibbs energy relationships for the complexes of two different ligands with numerous different metal ions can be instructive for understanding the interactions of actinide ions with ligands (Jensen and Nash, 2001). Five‐membered chelate rings are the most stable ring size for complexes of actinide‐sized cations (Hancock, 1992), and the strength of actinide–ligand interactions for chelating ligands usually decreases with ring size in the order 5 > 6  7 8 for all actinide oxidation states (Stout et al., 1989). If the

Correlations

2573

Fig. 23.20 Correlation between the stability constants of trivalent lanthanide complexes and the stability constants of the complexes of (a) a hexavalent actinide, (b) a trivalent actinide, and (c) a tetravalent actinide. See Fig. 23.17 for the ligands’ numerical identities.

donor groups are strongly basic, ligands that form seven‐membered rings can be quite stable. Presumably this is because the large size and non‐directional electrostatic bonding of the actinide cations can accommodate the larger chelate ring (Rapko et al., 1993). Complexes with eight‐membered chelate rings formed by inter‐ligand hydrogen bonding also are important species in non‐aqueous

2574

Actinides in solution: complexation and kinetics

media, most notably for phosphoric acid based extractants such as bis(2‐ethylhexyl)phosphoric acid (Ferraro and Peppard, 1963). The basis for the empirical correlations between the stability constants of the actinide ion complexes with the acid constants of ligands or the stability constants of other metal ions is the strongly ionic character of the bonding in these systems. Born (1920) calculated the solvation energy of an ion in solution (MZþ) from a model of a sphere of charge þZ and radius R in a system with a dielectric constant, D, by the equation DGsolvation ðMZþ Þ / Z 2 =DR

ð23:11Þ

Modifications to the Born equation (Mu¨nze, 1972) have formed a useful basis for estimating and comparing actinide–ligand complexation constants (Choppin, 1983; Rizkalla et al., 1990b), and may be useful for describing the entropies of complexation as well (Manning, 1996). For cations of the same charge (Z), the modified Born equation predicts a linear relationship between the logarithmic stability constant and 1/Rcation, the reciprocal of the cation radii. This relationship holds over a range of cationic radii for numerous metal–ligand complexes, as shown for trivalent lanthanides and for trivalent and tetravalent actinides in Fig. 23.21. In systems where an approximately linear relationship does not hold for f‐element complexes, such as citrate complexes (Fig. 23.21), significant steric effects or specific interactions (metal–solvent, ligand–solvent, complex–solvent, or ligand–ligand) are likely. However, it is not known if the order of magnitude deviation of the Fm(dcta) and Md(dcta) (dcta4 ¼ trans‐ 1,2‐diaminocyclohexane‐N,N,N0 ,N0 ‐tetraacetate, Fig. 23.18) complexes from the correlation with 1/Rcation in Fig. 23.21 arises from such chemical factors or from the higher uncertainties associated with stability constant measurements of complexes involving high specific activity radionuclides. The cationic charge used in the Born equation, Z, could be taken to be equal to the formal charge of An(III) and An(IV) cations, but it is less clear what the 2þ value of Z should be for AnOþ 2 and AnO2 species since the oxo ligands appear to retain a partial negative charge. As discussed in Section 23.4, electrostatic correlations based on the Born equation for actinyl–fluoride complexes, suggest that the effective cationic charge experienced by a ligand bound to NpOþ 2 is þ2.2, and for ligands bound to UO2þ is þ3.3 (Choppin and Unrein, 1976; 2 Choppin and Rao, 1984). Defining the ligand charge in the cases of neutral ligands, polydentate ligands, 2 or ligands containing both anionic functional groups (e.g., CO 2 or PO3 ) and neutral donor sites (e.g. –N¼ or –O–) is also difficult. Effective anionic charges have been estimated for some organic ligands by assuming that the Born equation is valid for ligand protonation (Choppin, 1983), which results in a linear relationship between SpKa and the effective anionic charge of a ligand,Zan, Zan ¼ 0:208 SpKa

Correlations

2575

Fig. 23.21 Dependence of the stability constants of actinide (solid symbols) and lanthanide (open symbols) complexes on cation size as dictated by a purely electrostatic bonding model: ( , □) 1:1 complexes of trivalent cations with citrate (cit3), ( , ~) 1:3 complexes of trivalent cations with a‐hydroxyisobutyrate (ahib), (●, ○) 1:1 complexes of trivalent cations with trans‐1,2‐diaminocyclohexane‐N,N,N0 ,N0 ‐tetraacetate (dcta4), ( ) 1:1 complexes of tetravalent actinide cations with ethylenediaminetetraacetate (edta4–). Stability constant data from ( ) Stary´ (1966) and Bru¨chle et al. (1988) at I ¼ 0.5 M; (~) Martell et al. (1998) at I ¼ 0.1 M; ( , □) Martell et al. (1998) at I ¼ 0.1 M (ionic strength correction applied to Pu3þ); ( ) Martell et al. (1998) with Pu value average of Cauchetier and Guichard (1973), Krot et al. (1962), and Mikhailov (1969) at I ¼ 0.5 M (ionic strength correction applied to Np4þ, and Pu4þ). Ionic radii from David (1986) for CN ¼ 8.

▪

▴

▴ ▪ ▾

▾

The Born approach has been useful in describing actinide–ligand complexation in solution, but there has been much discussion over the years about the proper form that an equation describing general electrostatic bonding interactions should take. This debate eventually waned due to the understanding that the general function, Zn/rm, is suitable (Huheey, 1976). The Brown–Sylva–Ellis equation, a semiempirical correlation using a complicated function of Z2/r2 coupled to a number of electronic corrections appears very successful for describing metal–ligand interactions for a wide range of metal ions, including the actinides (Brown et al., 1985). Other electrostatic models that incorporate corrections for inter‐ligand repulsion (Moriyama et al., 1999, 2002; Neck and

Actinides in solution: complexation and kinetics

2576

Kim, 2000) into the general Born framework have been able to reproduce the stability complexes for higher mononuclear complexes of the actinides (i.e. b1q with q > 1). Inter‐ligand interactions are not important for 1:1 Anzþ:L complexes and the metal–ligand interactions can be represented by the simplest form of the coulombic attraction between a metal ion and a monovalent L ligand with log b11 / Z/dM–L (dM–L ¼ the distance between the center of the metal ion and the ligand donor atom). Fig. 23.22 depicts this correlation for the 1:1 complexes of hydroxide and fluoride anions with neptunium in the trivalent, tetravalent, pentavalent, and hexavalent oxidation states, using estimates of the actinide– ligand bond distances derived from extended X‐ray absorption fine structure measurements of aqueous actinide complexes (Allen et al., 1997, 2000; Moll et al., 1999; Vallet et al., 2001) and effective charges of þ2.2 and þ3.2 for NpOþ 2 and NpO2þ 2 cations, respectively. The correlation also holds for more complicated inorganic and organic ligands. Correlations based on electrostatic considerations are important for understanding actinide–ligand bonding, but other correlations could also be used. Drago and Wayland (1965) used an empirical, four‐parameter equation, DH11 ¼ E A E B þ C A C B

ð23:12Þ

Fig. 23.22 Dependence of the stability constants of neptunium fluoride (●) and neptunium hydroxide ( ) on the effective ionic potential at I ¼ 0 M and 25 C. Data from Lemire et al. (2001) with the value for NpF2þ (○) estimated from the LnF2þ stability constants of Martell et al. (1998).

▪

Actinide complexes

2577

to describe the enthalpy of adduct formation between a Lewis acid (the EA and CA terms) and a Lewis base (the EB and CB terms). EA and EB are related to the tendency of an acid and base to form electrostatic bonds and CA and CB are related to their tendency to form covalent bonds. The equation was subsequently related to the molecular orbitals of the complexes formed (Marks and Drago, 1975). Hancock and Marsicano (1980) extended this approach to Gibbs energies of complexation using two additional parameters to include the steric constraints of the Lewis acid and base. Stability constants of aqueous Pu(IV) and U(VI) complexes with a number of ligands were estimated in this way (Hancock and Marsicano, 1980; Jarvis et al., 1992; Jarvis and Hancock, 1994). This parameterization also has been used to understand bonding in lanthanide–ligand systems (Choppin and Yao, 1988; Carugo and Castellani, 1992). For a given lanthanide ion, the stability constants with oxygen donor ligands, which form strongly ionic bonds, were found to be well correlated to EB, the ligand electrostatic parameter. In contrast, the stability constants of the complexes of the softer, nitrogen donor ligands were correlated with the ligand‐ based covalent parameter, CB. Ionization potentials and electronegativities have also been used in correlations with the Gibbs energies of complexation of other families of metal ions (Hefter, 1974; Hancock and Martell, 1996). The success of such correlations, whether based on linear Gibbs energy relationships of stability or protonation constants, on the Born solvation model, or on empirical parameterization is a reflection of the regularity of the solution chemistry of actinide cations and the strongly electrostatic nature of the bonding of their complexes.

23.7 ACTINIDE COMPLEXES

The complexes formed by actinide ions have been the focus of much research because of the importance of separating individual actinide elements from each other or from other elements in the nuclear fuel cycle, and of understanding the environmental chemistry of the actinide elements. A wide variety of experimental methods have been used to identify the stoichiometry or quantify the appropriate equilibrium constants of kinetically labile actinide complexes in solution. The accuracy of these studies depends strongly on the oxidation state purity of the actinide, which can be a problem for less stable oxidation states [e.g. U(III), U(V), Pu(V), Pu(VII), Am(IV), Am(V), or Am(VI)] and when multiple oxidation states can coexist in the same solution as is the case for neptunium and plutonium. The stoichiometry and strength of the actinide complexes with a given ligand are similar within a fairly narrow range for a particular oxidation state due to the predominantly ionic nature of the actinide–ligand bonds and the small differences in cationic radii. The consistent exception to this is Pa(V), which does not exist as an actinyl(V) cation.

2578

Actinides in solution: complexation and kinetics 23.7.1

Complexes with inorganic ligands

The reactions of actinide ions with halide and pseudohalide anions have been studied extensively. The complexes are, with the exception of the fluoro complexes, moderately weak in aqueous solution. As a consequence, measurements of the complexation constants often require high ligand concentrations (>1 M) and acidic media to allow sufficient amounts of the complexes to form and to avoid interference from hydrolysis reactions. This is most necessary for the tetravalent actinides which can undergo hydrolysis even when pH 1. Many of the halide complexes are sufficiently weak that outer sphere complexes are formed, particularly for the 1:1 (M:L) complexes. Aqueous fluoro complexes of the actinide ions are known for the trivalent through the hexavalent oxidation states. The fluoride ligand has a much higher affinity for actinide cations than the heavier halides and all actinide fluoro complexes are inner sphere complexes. The neutral fluoro complexes of trivalent and tetravalent actinides, AnF3 and AnF4, are insoluble in aqueous solution (pKsp ¼ 16.4 for PuF3 and 26.7 for PuF4 at I ¼ 0 M [Lemire et al., 2001]). In contrast, all of the aqueous actinyl(V) and actinyl(VI) fluoro complexes are soluble. Separation of actinyl species from actinides in the lower oxidation states by fluoride precipitation is an effective method for determining the oxidation state speciation of trace actinides (Kobashi and Choppin, 1988). Cationic complexes formed in the equilibria Anzþ þ qF ! AnFðzqÞþ q (Anzþ ¼ An(III), An(IV), An(V), and An(VI), and q < z) have been identified. 2þ Anionic complexes of AnOþ 2 and AnO2 have also been studied (Ahrland and Kullberg, 1971b; Inoue and Tochiyama, 1985), and pentagonal bipyramidal UO2 F3 5 forms at high fluoride concentrations (Vallet et al., 2002). Stability constants and thermodynamic parameters for the formation of the fluoro complexes of actinides in various oxidation states are summarized in Table 23.18. The stability constants of the 1:1 An:F complexes vary in the order 2þ 2þ UO2þ for hexavalent actinides [see Section 23.4, and 2 > NpO2 > PuO2 Choppin and Rao (1984)], Th4þ < U4þ > Np4þ  Pu4þ for tetravalent actinides, and Am3þ < Cm3þ < Bk3þ < Cf3þ for trivalent actinides (Chaudhuri et al., 1999). Stability constants for the fluoro complexes of the pentavalent actinides have been reported only for protactinium (Guillaumont, 1966; Kolarich et al., 1967) and neptunium (as assessed by Lemire et al., 2001). The reversal in the sequence of the stability constants from the order expected based on the cationic radii of the tetravalent actinides is small, and the expected order is observed for þ AnF2þ 2 and AnF3 . In each of these oxidation states, the stability of the actinide fluoro complexes is due to the highly favorable entropy contribution while the complexation enthalpies either oppose complex formation or are weakly favorable (Table 23.18). These DH and DS values reflect the importance of ion dehydration in the formation of inner sphere actinide complexes.

Actinide complexes

2579

Table 23.18 Stability constants, and Gibbs energies, enthalpies, and entropies of  ! AnO2 Fzq complexation for the reactions Anzþ þ qF ! AnFzq andAnOzþ q 2 þ qF q at 25 C. Number of F

DG DH DS log b1q (kJmol1) (kJmol1) (JK—1 mol–1) References

Am3þ, I ¼ 0.1 M 1a 2.49

14.2

28

140

1

2.59

14.8

23

126

2

4.75

27.1

24

170

8.17 14.57

46.6 83.1

2.4 3.3

149 120

Ahrland et al. (1990) Ahrland et al. (1990)

9.02 15.72 21.18

51.5 –89.7 120.9

5.6 3.5 0.5

154 136 119

Ahrland et al. (1990) Ahrland et al. (1990) Ahrland et al. (1990)

7.59

43.3

5.6

164

NpOþ2 , I ¼ 1 M 1 UO22þ, I ¼ 1 M 1

Nash and Cleveland (1984b)

1.3

7.4

–

Martell et al. (1998)

4.54

25.9

1.7

92.5

2

7.98

45.5

2.1

160

3

10.41

59.5

2.4

207

4

11.89

67.9

0.3

229

Ahrland and Kullberg (1971c) Ahrland and Kullberg (1971c) Ahrland and Kullberg (1971c) Ahrland and Kullberg (1971c) Vallet et al. (2002)

Th4þ, I ¼ 4 M 1 2 U4þ, I ¼ 4 M 1 2 3 Pu4þ, I ¼ 2 M 1

5 a b

0.60b





–

Choppin and Unrein (1976) Nash and Cleveland (1984a) Nash and Cleveland (1984a)

–

I ¼ 1.0 M.  ! K5 for the reaction UO2 F2 UO2 F3 4 þF 5 ; I ¼ 1:0

M; T

¼  5 C.

The actinide complexes of the heavier halides are much weaker than those of the fluoro complexes. They also are quite soluble. To the extent that equilibrium constants are available, the strength of the monohalogeno complexes decreases in the order Cl > Br > I (Grenthe et al., 1992) and they appear to be outer sphere under most circumstances (Section 23.2.6). Data on aqueous bromide complexation is scarce and the reducing power of iodide as well as the weakness of the complexes formed have limited studies of the iodide complexes to U(IV), Np(IV), and Pu(III) species (Vdovenko et al., 1963; Khopkar and Mathur, 1974; Patil et al., 1978). Stability constants for actinide complexation with chloride anions in aqueous solution are available for 1:1 and usually 1:2 species for trivalent (Ac, Pu–Es), tetravalent (Th–Pu), pentavalent (Np), and hexavalent

2580

Actinides in solution: complexation and kinetics

(U–Pu) actinides (Fuger et al., 1992). For actinyl(VI) cations the complexation enthalpies for formation of the monochloro and dichloro complexes are endothermic in 2 M HClO4 at 25 C (DH11 ¼ þ[9.2  0.5] and DH12 ¼ þ[18  1] 1 kJ mol1 for UO2þ for PuO2þ 2 and DH11 ¼ þ[14  2] kJmol 2 (Rabideau and Masters, 1961; Awasthi and Sundaresan, 1981)). The values of the corresponding complexation entropies range from þ26 to þ50 JK1 mol1. Anionic chloro complexes are often used for separations purposes. Reliable stability constants are not known for these species, but anion exchanging resins or solvent extraction reagents promote the formation of these inner sphere complexes. The trivalent actinides form anionic AnCl4 complexes in the resin or organic phase when the concentration of hydrochloric acid exceeds 8 M. Tetravalent uranium, neptunium, and plutonium form anionic chloro complexes with increasing ease, though anionic Th(IV) chloro complexes were reported as being only minor species in 12 M LiCl/0.1 M HCl (Kraus et al., 1956). The actinyl(VI) cations also form anionic chloro complexes that absorb on anion exchange resins. Both the tetravalent and hexavalent actinides absorb 2 as the doubly charged anionic complexes, AnCl2 6 and AnO2 Cl4 , in 12 M HCl,   while AnCl5 and AnO2 Cl3 are the likely species at lower chloride concentrations (Ryan, 1961; Allen et al., 1997). Although anionic complexes form in the resin phase, in non‐aqueous solvents (Marcus and Bomse, 1970) and in the solid state (Brown, 1972), anionic actinide chloro, bromo, and iodo complexes are not present in appreciable amounts in the aqueous phase, except at the highest halide concentrations (Marcus, 1966; Allen et al., 2000). The stability constants for formation of the 1:1 complexes at I ¼ 1.0 M are listed in Table 23.19.  The pseudohalides azide ðN 3 Þand nitrogen‐coordinated thiocyanate (NCS ) form complexes with actinide cations that are moderately stronger than the equivalent chloro complexes (Table 23.19). The greater stability of the An(III)  complexes with these softer ligands (i.e. Cl, N 3 , and NCS ) relative to that of the Ln(III) complexes has been the basis for group separations of the trivalent 5f elements from the 4f elements (Diamond et al., 1954; Sekine, 1965; Stary´, 1966; Musikas et al., 1983; Borkowski et al., 1994). Despite the greater strength of the pseudohalide complexes, spectroscopic measurements indicate that the 1:1 and, probably, the 1:2 An(III):SCN complexes are outer sphere complexes (Harmon et al., 1972b). Strong evidence for the aqueous anionic complexes, AnðSCNÞ 4;  2 AnO2 ðSCNÞ , and AnO ðN Þ and AnO ðN Þ also have been reported 2 3 3 2 3 4 3 (Ahrland, 1949; Sherif and Awad, 1961; Sekine, 1965; Kinard and Choppin, 1974; Chierice and Neves, 1983). 23.7.2

Complexes with inorganic oxo ligands

Actinides in the common oxidation states form complexes with inorganic oxo ligands. The complexes of the most common of these ligands, H2O and OH are discussed in Sections 23.2 and 23.3, while the complexes of the halate ligands are considered in Section 23.5.

Actinide complexes

2581

Table 23.19 Stability of 1:1 actinide chloride, azide, and thiocyanate complexes at I ¼ 1 M and 25 C (Martell et al., 1998). Anzþ

logb11 chloride

logb11 azide

logb11 thiocyanate

Ac3þ Pu3þ Am3þ Cm3þ Bk3þ Cf3þ Es3þ Th4þ U4þ Pu4þ NpOþ 2 UO2þ 2

0.10 0.10 0.1  0.18a  0.18a 0.18 0.40 0.14 0.35b 0.10c

– – 0.67 0.64 – 0.70 – – – – – 2.31d

0.05 0.46 0.43 0.44 0.49 0.53 0.56 1.08 1.49c – 0.32b 0.74

a b c d

I ¼ 0.5 M. I ¼ 2.0 M. T ¼ 20 C. I ¼ 0.1 M.

The stabilities of the actinide complexes with inorganic oxo anions vary in 2 2 3 the order NO 3 < SO4  CO3 < PO4 , as expected from the increasing charge and basicity of the ligands. The actinide nitrato complexes are important in the processing of nuclear reactor fuel, especially in separations where the neutral actinide nitrates can be extracted into organic solvents and the anionic, hexanitrato actinide(IV) complexes are used in anion exchange separations. The reported stability constants of the 1:1 An:NO 3 complexes are slightly larger than those of the analogous chloro complexes, and the anionic nitrato species form more readily than the corresponding chloro complexes. For the actinides, nitrate ions usually act as bidentate chelating ligands with two oxygen atoms from each nitrate coordinated to an actinide. Sulfate, carbonate, and phosphate complexes can be important in actinide processing, and, along with silicates, are important ligands in determining the environmental behavior of actinide cations. Normally, the stability constants of the complexes with these ligands increase in the usual sequence of 3þ 4þ AnOþ < AnO2þ 2 < An 2 < An . The trivalent actinides have been shown to form 1:1 and 1:2 An:SO2 4 complexes, while the trisulfato complexes also form for the tetravalent and hexavalent actinides. For the weakly complexing actinyl(V) cations, only NpO2 SO 4 has been reported (Halperin and Oliver, 1983). Stability constants for some actinide–sulfate complexes are summarized in Table 23.20. The thermodynamics of actinide–sulfate complexation are consistent with the formation of inner sphere

Actinides in solution: complexation and kinetics

2582

Table 23.20 Stability constants of actinide sulfate complexes at I ¼ 2 M and 25 C (De Carvalho and Choppin, 1967; Ahrland and Kullberg, 1971a; Halperin and Oliver, 1983; Nash and Cleveland, 1983; Martell et al., 1998) and carbonate complexes at I ¼ 0 M and 25 C (Grenthe et al., 1992; Silva et al., 1995; Lemire et al., 2001). Sulfate (I ¼ 2 M)

Carbonate (I ¼ 0 M)

Anzþ

logb11

logb12

logb11

Ac3þ Pu3þ Am3þ Th4þ U4þ Np4þ Pu4þ UO2þ NpO2þ PuO2þ UO22þ NpO22þ PuO22þ

1.36a 1.55 1.43 3.25 3.48 3.49 3.80

2.68a 2.12 1.85 5.53 5.82 6.06 6.6

a

0.19 1.81a

2.76a

7.8

logb12

logb13

12.3

15.2

4.96

6.53

9.68 9.3 11.6

16.94 16.5 14.5

7.4 5.50 5.1 21.60 19.37 17.7

I ¼ 1 M.

Table 23.21 Thermodynamic parameters for actinide sulfate complexation in 2 M perchlorate media at 25 C (Sullivan and Hindman, 1954; Zielen, 1959; Jones and Choppin, 1969; Ahrland and Kullberg, 1971a; Halperin and Oliver, 1983). Actinide ion

DG11 DH11 DS11 DG12 DH12 DS12 (kJmol–1) (kJmol1) (JK1 mol–1) (kJmol1) (kJmol1) (JK1 mol1)

Am3þ Cm3þ Cf3þ Th4þ Np4þ NpOþ 2 UO22þa

8.4 7.5 7.9 18.8 20.0 1.1 10.3

a

18.4 17.2 18.8 20.9 18.3 19 18.2

90 83 90 133 128 66 96

– – – 32.6 – – 15.7

– – – 40.4 – – 35.1

– – – 245 – – 171

I ¼ 1 M NaClO4.

complexes. The endothermic enthalpies of complexation vary little between actinides in different oxidation states and the strength of a particular actinide–sulfate complex relative to that of other actinide–sulfate species is determined mainly by the complexation entropies (Table 23.21). Sulfate complexes of uranyl(VI) can form polynuclear, ternary hydroxo‐sulfato complexes in weakly acidic solutions (Grenthe and Lagerman, 1993; Moll et al., 2000).

Actinide complexes

2583

Carbonate complexes of the actinides have been investigated often, as reviewed by Newton and Sullivan (1985) and Clark et al. (1995). Although the solubility of neutral AnO2(CO3) is low, the triscarbonato uranyl(VI) complex, UO2 ðCO3 Þ4 3 , is responsible for the relatively high concentration of uranium in 4 seawater (Spence, 1968). The complexes NpO2 ðCO3 Þ4 3 and PuO2 ðCO3 Þ3 are less important in the environment because the stability constants of the actinyl (VI) triscarbonato complexes decrease by four orders of magnitude from UO2þ 2 to PuO2þ 2 as the effective charge on the actinide decreases (Table 23.20). Similar to nitrate, the carbonate ligands are bidentate, binding in the equatorial plane of the actinyl cations, forming triscarbonato actinyl complexes with hexagonal bipyramidal geometry. Carbonate complexes also are among the few soluble complexes of uranyl(V), plutonyl(V), and americyl(V) that have been quantitatively studied (Bennet et al., 1992; Giffaut and Vitorge, 1993; Docrat et al., 1999). The stabilities of the triscarbonato actinyl(V) complexes are roughly 13 orders of magnitude smaller than the corresponding actinyl(VI) complexes (Lemire et al., 2001). Nevertheless, carbonate ligands stabilize actinyl(V) ions, especially in the solid state (Keenan and Kruse, 1964; Madic et al., 1983a). Few measured stability constants for AnðIVÞCO2 3 complexes have been reported, but those of the limiting solution species, AnðCO3 Þ6 5 (Clark et al., 1998), are large, exceeding 1035 M5. Well‐characterized polynuclear complexes of the actinyl(VI) cations with bridging and terminal carbonate 2 ˚ berg et al., 1983b; ligands have an AnO2þ stoichiometry of 3:6 (A 2 : CO3 Allen et al., 1995). Carbonate complexes of Np(VII) also have been proposed (Shilov et al., 1976). The actinide complexes of highly charged inorganic ligands, such as phosphates, arsenates, or silicates, can precipitate in a variety of different solid phases. Soluble, protonated complexes of these ligands, for example AnO2 ðHPO4 Þ22n , have lower stability constants than complexes of the fully n deprotonated ligands because of the reduced charge of the protonated ligand. The actinyl(V) and actinyl(VI) cations form soluble 1:1 complexes with PO3 4 that are strong enough to compete with carbonate complexation (Sandino and Bruno, 1992; Brendler et al., 1996; Morgenstern and Kim, 1996). Singly deprotonated orthosilicic acid, H3 SiO 4 , forms complexes with trivalent and hexavalent actinides in solutions that are weakly acidic to neutral (Yusov and Fedoseev, 2003 and references therein), and the stability constants of the orthosilicate complexes are proportional to the hydrolysis constants of the metal cations (Jensen and Choppin, 1998). Multicharged, complex inorganic oxides, such as polyphosphates, polymeric silicates, and polyoxometallates, with properties intermediate between those of simple ligands and of oxide or mineral surfaces also form complexes with actinide cations. Stability in acidic solution and the ability to create soluble, well‐defined structures with extensive redox activity make the actinide polyoxometallates interesting complexes (Yusov and Shilov, 1999). The rich chemistry of polyoxometallates results in the complexation and stabilization of

2584

Actinides in solution: complexation and kinetics

transplutonium actinides in oxidation states usually not stable in aqueous solutions, for example Am(IV), Cm(IV), and Cf(IV) (Kosyakov et al., 1977). 6 Many common polyoxometallate anions, such as SiW12 O4 40 ; P2 W18 O62 ; 8 14 Nb6 O19 , and NaP5 W30 O110 , form complexes with actinide cations, and both 1:1 and 1:2 complexes have been identified. The stability constants for the Th4þ complexes of SiW12 O4 40 are log b11 ¼ 11.3 and log b12 ¼ 17.8, and are characterized by large positive complexation entropies, DS11 ¼ 232 JK1 mol1 and DS12 ¼ 356 JK1 mol1 (Choppin and Wall, 2003). The binding sites on the surfaces of some polyoxometallate ligands can accommodate the steric requirements of the actinyl cations as well as the simple actinide cations (Gaunt et al., 2002). Certain polyoxometallates, like the Preyssler anion P5 W30 O15 110 , also can encapsulate actinide cations internally, forming inert, but soluble, compounds (Creaser et al., 1993; Antonio et al., 1998). 23.7.3

Complexes with organic ligands

The variety and strength of organic ligands that form complexes with actinide ions in aqueous solution are limited by the preference of the actinides for hard donor ligands and by the tendency of actinide cations toward hydrolysis. Consequently, ligands that bind actinide cations in aqueous solution usually contain some hard base, oxygen donor sites because the strength and basicity of organic ligands containing only softer donor groups, generally, are insufficient to suppress the precipitation of actinide hydroxides. In organic solvents, where actinide hydrolysis is not important, organic ligands with softer donors such as dithiophosphinic acids (Pinkerton et al., 1984; Jensen and Bond, 2002), thiacrown ethers (Karmazin et al., 2002), ethylenediamine (Cassol et al., 1990), or tripyrazine (Drew et al., 2000) form actinide complexes that are stable, although weaker than complexes of similar oxygen donor ligands. The most commonly studied actinide–organic ligand complexes involve ligands bearing carboxylic acid groups. Actinide complexes with simple monocarboxylate ligands (i.e. those that contain no other actinide‐binding groups) are not among the stronger actinide complexes (Table 23.22). Compared to common inorganic ligands, the actinide complexes of simple monocarboxylates are somewhat stronger than the equivalent SO2 4 complexes, but weaker than the OH or CO2 complexes. For acetic acid, the stability constants of the first 3 and second acetate complexes, b11 and b12, follow the expected order of effective cation charge and ionic radii for actinides in the different oxidation states. However, the 1:3 acetate complexes of the actinyl(VI) ions are stronger than expected from the stability constants of the An(III) and An(IV) complexes. The thermodynamics of actinide–monocarboxylate complexation are, like those of the simple inorganic ligands, entropy driven, with weakly positive or negative complexation enthalpies. Monocarboxylates with low pKa values (e.g. dichloroacetate [pKa ¼ 1.1] and trichloroacetate [pKa ¼ –0.5]), form outer sphere complexes with the actinides (Section 23.5).

Table 23.22 Stability constants of actinide carboxylate and phosphonate complexes in perchlorate media at 25 C.

Acetate (ac–) CH3CO2–

glycolate HOCH2CO2

oxalate (CO2)22

malonate CH2(CO2)22

I (M)

logb11

Pu3þ

2a

2.02

Am3þ Cm3þ Th4þ

0.5a 0.5a 1

NpO2þ

logb12

logb13

logb14

References

3.34

–

–

1.99 2.06 3.86

3.28 3.09 6.97

– – 8.94

– – 10.28d

2

0.87

–

–

–

UO22þ

1

2.42

4.41

6.40

NpO22þ

1a

2.31

4.23

6.0

Magon et al. (1968) Grenthe (1962) Grenthe (1963) Portanova et al. (1975) Rizkalla et al. (1990b) Ahrland and Kullberg (1971a) Portanova et al. (1970)

Am3þ Cm3þ Bk3þ

0.5a 0.5a 2

2.82 2.85 2.65

4.86 4.75 4.69

6.3 – –

– – –

Th4þ

1

4.11

7.45

10.1

12.0e

NpOþ2

2

1.43

1.90

–

–

UO22þ

1

2.35

3.97

5.17

–

NpO22þ

1a

2.37

3.95

5.00

–

PuO22þ

0.1

2.43

3.79

No2þ

0.5b

1.68

Am3þ Th4þ

1 1

4.63 8.23

Np4þ

1

NpOþ2

– –

–

–

–

–

8.35 16.77

11.15 22.77

– –

8.19

16.21

–

–

1

3.71

6.12

–

–

UO22þ

1a

5.99

10.64

11.0

–

Th4þ

1

7.47

12.79

16.3

–

NpOþ2

1

2.63

4.28

–

–

Grenthe (1962) Grenthe (1963) Choppin and Degischer (1972) Di Bernardo et al. (1978) Rizkalla et al. (1990b) Di Bernardo et al. (1976) Portanova et al. (1972) Eberle and Schaefer (1968) McDowell et al. (1976) Sekine (1964) Moskvin and Essen (1967) Bansal and Sharma (1964) Tochiyama et al. (1992) Havel (1969) Di Bernardo et al. (1977) Jensen and Nash (2001)

2586

Actinides in solution: complexation and kinetics Table 23.22 I (M)

succinate (CH2CO2)2 2

diglycolate O(CH2CO2)2 2

b c d e

logb12

logb13

logb14

References

9.48

–

–

Di Bernardo et al. (1977)

–

–

–

–

Di Bernardo et al. (1983) Stout et al. (1989) Bismondo et al. (1981)

UO2þ 2

1

5.42

Th4þ

1

6.44

NpOþ2

1c

1.51

UO2þ 2

1

3.85

–

–

–

Th4þ

1

8.15

14.8

18.2

–

NpOþ 2

1

3.79

–

–

–

UO2þ 2

1

5.11

–

–

NpO2þ 2

1a

5.16

–

–

–

PuO2þ 2

1a

4.97

–

–

–

2 0.1

8.50 7.57

16.05 14.17

Nash (1991a) Nash (1993b)

2 0.1

8.34 7.82

15.44 13.82

Nash (1991a) Nash (1993b)

0.1

5.34

8.31

Nash (1993b)

phosphonoacetate O2CCH2PO3H2 Th4þ UO2þ 2 methane‐1,1‐diphosphonate 4þ 2 CH2(PO3H)2 Th UO2þ 2 ethane‐1,2‐diphosphonate (CH2PO3H)2 UO2þ 2 2 a

logb11

(Contd.)

– 2.14

7.54

Di Bernardo et al. (1983) Jensen and Nash (2001) Di Bernardo et al. (1980) Cassol et al. (1973) Cassol et al. (1973)

20 C. 0.5 M NH4NO3, no temperature given. 23 C. log b15 ¼ 11.00. log b15 ¼ 13.4.

Multifunctional ligands such as polycarboxylates, hydroxycarboxylates, and aminocarboxylates tend to form stronger actinide complexes than simple monocarboxylates due to the formation of chelate rings through coordination of multiple functional groups. This occurs because the affinity of carboxylate (or phosphonate) groups for actinide ions, and their very favorable complexation entropies, provide an anchor for the complexation of amines, ether oxygens, or other less effective donor atoms within the same ligand. For instance, simple

Actinide complexes

2587

alcohols are not good ligands for actinides in aqueous solution. However, the stability constants of the 1:1 An:L complexes of a‐hydroxycarboxylates like glycolate (Table 23.22) and a‐hydroxyisobutyrate are stronger than that of acetate because of chelation via the a‐hydroxy group (Ahrland, 1986; Stumpf et al., 2002; Toraishi et al., 2002), even though the pKa values of the carboxylic group would indicate that they are less basic ligands. Multifunctional ligands also form polynuclear complexes by bridging actinide ions, though this behavior is not unique to actinide cations. In some cases, for example (UO2)2(edta), ðUOÞ2 ðcitrateÞ2 2 , or Th4(glycolate)n (n ¼ 8  1) (Kozlov and Krot, 1960; Rajan and Martell, 1965; Frau´sto da Silva and Simoes, 1968; Toraishi et al., 2002), the polynuclear complexes are well defined and soluble, making measurement of the formation constants of the polynuclear species possible. The likelihood of polynuclear complex formation is usually favored by increasing metal concentrations and decreasing ligand:metal ratios. As the size of the polynuclear complexes increase, their precipitation becomes more likely. Ethylenediaminetetraacetic acid (H4edta) and the related multifunctional polyaminocarboxylate ligands are strong, but not very selective, complexants for An(III) and An(IV) cations. Steric constraints make them much poorer ligands for actinyl(V) and actinyl(VI) cations as discussed in Section 23.6. This has led to the use of polyaminocarboxylates as masking agents for interfering An(III) or An(IV) cations in the chemical analysis of actinyl ions. When fully coordinated, the most commonly used polyaminocarboxylate ligands, hexadentate edta4 and dcta4, and octadentate dtpa5 only partially envelope actinide cations, leaving one or more coordination sites for water molecules (Carey and Martell, 1968; Fried and Martell, 1971; Kimura and Choppin, 1994), or for other small ligands (Pachauri and Tandon, 1975). The strongest polyaminocarboxylate ligands complex An(III) and An(IV) cations over a wide range of acidities (Fig. 23.23). In moderately acidic media (pH 1–3), protonated actinide–polyaminocarboxylate complexes, for example An(Hedta), form. As the pH is increased, fully deprotonated complexes, such as An(edta) form first, followed by the formation of ternary actinide–hydroxy‐polyaminocarboxylate complexes, such as An(OH)(edta)2, in basic solutions. Increasing the hydroxide concentration further will eventually displace the organic ligand, but for strong polyaminocarboxylate ligands like edta4 this occurs only in the most caustic solutions (>1 M NaOH) (Wang et al., 2003). Table 23.23 shows that the strength of actinide‐polyaminocarboxylate complexes is principally due to large, positive complexation entropies, in common with other inner sphere actinide complexes. However, in contrast to the actinide complexes of inorganic or carboxylate ligands, most actinide–polyaminocarboxylate complexes are strengthened by substantially exothermic complexation enthalpies, which are commonly observed in metal–amine complexation. Organophosphorus ligands with low water solubility are used widely in organic solvents for chemical separation or purification of the actinides by

2588

Actinides in solution: complexation and kinetics

Fig. 23.23 Speciation of Am(III) complexes of ethylenediaminetetraacetic acid (H4edta) and ethylenediaminetetra(methylenephosphonic) acid (H8edtmp) identified by the An:H:L stoichiometry as a function of pH for 1  10–6 M Am and 1.2  10 –4 M ligand at I ¼ 0.1 M and 25 C. Stability constants from Shalinets (1972a,b).

solvent extraction. Water‐soluble organophosphorus ligands based on phosphoric and phosphonic acids, ROPO3H2 and RPO3H2, are also important actinide complexants in nature (Panak et al., 2002a,b) and in chemical separations (see Chapter 24). Compared to carboxylic acids, the phosphonic acids usually form f‐element complexes with Gibbs energies of complexation that are larger than expected from the ligand basicity (Nash, 1993b), even when the ligands are partially protonated (e.g. RPO3H) as illustrated in Table 23.22. The methane‐1,1‐diphosphonic acids, RCH(PO3H2)2, analogs of malonic acid,

Actinide complexes

2589

Table 23.23 Thermodynamic parameters for actinide acetate and aminopolycarboxylate complexation at 25 C. DG11 DH11 DS11 I (M) (kJmol1) (kJmol1) (JK1 mol–1) References 11.2 11.7 22.0 13.8

6.8 6.0 11.3 10.5

60 57 112 82

Rizkalla et al. (1989) Choppin et al. (1985) Portanova et al. (1975) Ahrland and Kullberg (1971a)

Am3þ 0.5 Th4þ 1 NpO2þ 0.5 1 UO22þ 1

44.9 55.3 33.2 33.6 50.1

4.6 6.5 16.4 16.0 2.2

136 207 56 59 161

Rizkalla et al. (1989) Di Bernardo et al. (1983) Choppin et al. (1992a) Jensen and Nash (2001) Di Bernardo et al. (1980)

Pu3þ

0.1

103.1

17.7

287

Am3þ

0.1

103.7

19.5

282

Cm3þ Th4þ

0.5 0.5 0.1

95.7 96.2 132.5

23.9 29.3 12.1

241 225 404

Fuger and Cunningham (1965) Fuger and Cunningham (1965) Rizkalla et al. (1989) Choppin et al. (1985) Kinard et al. (1989)

dcta4

Am3þ Cm3þ

0.5 0.5

103.9 103.3

10.8 9.7

312 314

Rizkalla et al. (1989) Choppin et al. (1987)

dtpa5

Am3þ Th4þ

0.5 0.1

120.6 163.8

39.5 12

272 510

Rizkalla et al. (1989) Kinard et al. (1989)

ac–

Am3þ Cm3þ Th4þ UO22þ

ida2

edta4

2 2 1 1

CH2(CO2H)2, form quite strong complexes. Partially protonated complexes are believed to be a key factor in the strength of these diphosphonate complexes, stabilizing the 1:2 actinide:phosphonate complexes through inter‐ligand, intra‐ complex hydrogen bonding (Nash et al., 1995). The larger anionic charge of the fully deprotonated phosphonic acids, the presence of inter‐ligand hydrogen bonding, and the enhanced dehydration of the metal cations on complexation (Jensen et al., 2000b), contribute to the stability of actinide–diphosphonate complexes, as does the strength of the An–O¼P bond. Complexation of An(IV) cations by neutral, fully protonated methanediphosphonic acid, CH2(PO3H2)2, persist in 2 M nitric acid at ligand concentrations as low as 0.05 M (Nash, 1991b). Since monophosphonate and diphosphonate ligands form complexes with actinide ions more readily than the corresponding carboxylates, methylenephosphonic acid derivatives of H4edta might be expected to be extremely powerful complexants. However, replacing the four acetic acid groups of H4edta with

2590

Actinides in solution: complexation and kinetics

methylenephosphonic acid groups (H8edtmp) yields slightly weaker An(III) complexes (Fig. 23.23), although the stability constants indicate that a range of AnHnedtmpn5 complexes exist in 1 M NaOH for a concentration of 1  104 M edtmp (Shalinets, 1972b). Inter‐ligand hydrogen bonding between the amines and the phosphonates (Jensen et al., 2000b) and steric constraints (Shalinets, 1972c) apparently resist the formation of complexes in these aminomethylenephosphonates. Anionic carboxylate and organophosphorus‐based ligands are among the most studied organic actinide complexants in aqueous solution, but the actinide complexes of a variety of other organic ligands also have been studied. Stable actinide complexes form in weakly acidic aqueous solution (pH 3–6) with neutral ligands like tpen (Fig. 23.18), or polyamino(2‐hydroxyalkyl) ligands (Jarvis et al., 1992; Jarvis and Hancock, 1994; Jensen et al., 2000a). The pKa values of these neutral ligands are low enough that An(III), An(IV), or An(VI) cations can effectively compete with protons for the ligand binding sites in acidic solutions. However, the hydroxide concentration in nearly neutral solutions is sufficient to displace these neutral organic ligands and precipitate actinide hydroxides. Competition of protons for the actinide binding sites is not a hindrance to the binding of crown ether ligands (e.g. 15‐crown‐5 or 18‐crown‐6, Fig. 23.18). Yet without chelating by other complexing groups such as carboxylic acids incorporated into the crown ether, these ligands are weak actinide complexants in aqueous solution (Brighli et al., 1985), most likely forming outer sphere complexes (Guilbaud and Wipff, 1993b). In contrast, even the simplest phenol‐based calix[5]‐ and calix[6]‐arene macrocyclic ligands (Fig. 23.18) form  strong actinyl(VI) complexes (logb11 ¼ 19 for UO2þ 2 at 25 C, I ¼ 0.1 M) with a 2þ selectivity ratio for UO2 over divalent transition metal cations that exceeds 1010 (Shinkai et al., 1987). Naturally occurring ligands that efficiently bind metal cations are found throughout the biosphere. Hard transition metal cations are vital for many biological processes and there are many natural ligands that regulate their biochemistry. The actinides are also hard cations and the charge to radius ratio of the tetravalent actinides is similar to that of one of the most biologically important metal ions, Fe(III). Consequently, ligands that efficiently bind iron are expected to be efficient ligands for actinides. Desferrioxamine siderophores, a class of polyhydroxamic acid ligands used by microbes to scavenge and transport Fe(III), have proven to be equally efficient ligands for Pu(IV) (Jarvis and Hancock, 1991). X‐ray crystallography of the Pu(IV) complex of desferrioxamine E shows that the Pu is nine‐coordinated with three water molecules and six desferrioxamine oxygens in the inner coordination sphere (Neu et al., 2000). Interestingly, the ligand is only slightly deformed when it complexes ˚ difference in ionic radii (CN ¼ 6). Pu(IV) rather than Fe(III), despite the 0.08 A The complexing strength of naturally occurring hydroxamic and catechol (1,2‐dihydroxybenzene) groups that siderophores use to sequester Fe(III) have

Ternary complexes

2591

led to the design of catecholamide and hydroxypyridone ligands that strongly complex An(III) and An(IV) cations (Raymond, 1985). These ligands are highly selective for An(IV) over Fe(III) both in vitro (Romanovski et al., 1999; Zhao et al., 1999) and in vivo (Stradling et al., 1992; Xu et al., 1995), and are more efficient reagents for Pu decontamination than the polyaminocarboxylate, diethylenetriaminepentaacetate (dtpa5). Humic and fulvic acids are naturally occurring polyelectrolytes resulting from the decay of natural matter. Their composition varies with the local geology, hydrology, and biology, resulting in fulvic acids with molecular weights as low as 300 and humic acids with molecular weights in excess of 100 000 (Choppin and Allard, 1985). These materials contain alcoholic, phenolic, and carboxylic acid groups, which result in an affinity for metal ion complexation. Actinide ions may interact with these ligands either through binding in specific sites (Marinsky, 1976) or through a generalized ‘territorial’ binding where the cation is attracted by multiple functional groups within one area of the ligand (Manning, 1979). Different modeling approaches have been proposed to calculate the stability constants for metal ions bound by these ligands (Choppin and Labonne‐Wall, 1997). Stability constants of certain humic and fulvic acid complexes have been reported for the most common actinides (Choppin and Allard, 1985; Kim and Sekine, 1991; Moulin et al., 1992; Kim et al., 1993; Marquardt and Kim, 1998). In addition to complexation of actinide cations, humic and 2þ fulvic acids can also be redox active, reducing the hexavalent NpO2þ 2 and PuO2 (Dahlman et al., 1976; Choppin, 1988; Jainxin et al., 1993; Yaozhong et al., ´ and Choppin, 2000) and NpOþ 1993), and pentavalent PuOþ 2 (Andre 2 (Marquardt et al., 1996). Both their redox and complexation properties can lead to significant effects on actinide behavior in environmental systems.

23.8 TERNARY COMPLEXES

In aqueous solution, most actinide–ligand complexes could be considered ternary complexes, as they have three components, an actinide ion (component 1), one or more ligands (component 2) and some number of inner sphere water molecules (component 3). It is common, however, to consider such metal cation þ ligand anion þ coordinated water complexes as a binary metal–ligand complexes. Therefore, our discussion of ternary (or mixed) complexes is limited to three‐component complexes, such as AnXqYp or AnO2XqYp, where X and Y are different ligands but not H2O. Such ternary complexes may also have coordinated water molecules and varying degrees of protonation of the ligands. Bimetallic complexes, AnnMmXq also are considered ternary complexes, but solution studies on such bimetallic complexes of actinide cations are rare (Stemmler et al., 1996; Dodge and Francis, 1997). Despite the large literature on actinide–ligand complexation and the large number of possible complexes of

2592

Actinides in solution: complexation and kinetics

actinide ions in their various oxidation states, with two different ligands, the number of detailed experimental studies on ternary actinide complexation is limited. The combination of the low polarity and hydrophobicity of organic solvents often results in the formation of ternary complexes in these solvents. As a consequence, the best documented and most extensively studied actinide ternary complexes are those present in the organic phases of liquid–liquid (solvent) extraction systems, which are described in detail in Chapter 24. In organic solvents, the ternary actinide complexes often form with neutral organophilic ligands, required to provide solubility, and anions, required to balance the positive charge of the actinide cations, in the inner coordination sphere. However, complexes containing different anions and no neutral ligands are also well known in such solvents (Ferraro and Peppard, 1963). Ternary complexes of actinide salts have been important in actinide separations for more than a century, since the initial use of the extraction of UO2(NO3)2(Et2O)2 into diethylether to purify uranium (Pe´ligot, 1842). Industrial scale processing of the tetravalent and hexavalent actinides was built on this foundation, substituting methylisobutylketone, dibutylcarbitol (dibutoxydiethylene glycol), or tri(n‐butyl)phosphate (and similar organophosphate‐ based ligands) for diethylether. The tri(n‐butyl)phosphate (TBP) systems are particularly important since they have been adopted internationally for processing nuclear fuel in the PUREX process (Choppin et al., 2002). When actinides are extracted from nitric acid solutions into organic solutions containing TBP, the complexes AnO2(NO3)2(TBP)2 are formed in the organic phase for the hexavalent actinides, while the tetravalent actinides have the form An (NO3)4(TBP)p (p ¼ 2 or 3). The nitrate groups are directly coordinated to the central actinide cation as bidentate ligands. Given the propensity of the actinides to undergo hydrolysis reactions (Section 23.3), the single largest class of ternary complexes in aqueous solution are the mixed hydroxides, An(OH)qLp, which are readily encountered even in weakly acidic solutions for some species. This class of complexes was first reported almost 50 years ago (Ho¨k‐Bernstro¨m, 1956). The most extensively studied ternary actinide complexes remain the hydroxycarbonates, An(OH)q(CO3)p and AnO2(OH)q(CO3)p. The structural features and the formation constants 2þ of An3þ, An4þ, AnOþ hydroxycarbonates have been reported 2 , and AnO2 (Clark et al., 1995). The hydroxycarbonates of the pentavalent and hexavalent actinyl ions (Neck et al., 1997; Szabo´ et al., 2000) exhibit some solubility. In contrast, the neutral hydroxycarbonates, An(OH)(CO3), are the solubility‐ limiting species in near neutral aqueous solutions in equilibrium with atmospheric carbon dioxide when other ligands are absent (Bernkopf and Kim, 1984; Silva and Nitsche, 1984; Standifer and Nitsche, 1988; Felmy et al., 1990). Neutral 1:1:1 An(OH)(CO3) species do not exist in significant amounts in the solution phase (Felmy et al., 1990; Meinrath and Kim, 1991). Simple, mononuclear hydroxycarbonate complexes, as well as polynuclear species with average

Cation–cation complexes Th16 ðOHÞ20 ðCO3 Þ12þ 16

2593

Th8 ðOHÞ20 ðCO3 Þ8þ 2

stoichiometries of and have been reported at low metal concentrations (Grenthe and Lagerman, 1991). Ternary U(VI)–fluoride–carboxylate ligand complexes have been used for systematic studies of the rates and mechanisms of intermolecular and intramolecular exchange reactions. Multinuclear NMR and potentiometric investigations of the complexes revealed a variety of stoichiometries and structures that depend on the nature of the carboxylic acid (Smith, 1959; Szabo´ et al., 1997; Aas et al., 1998; Szabo´ and Grenthe, 2000; Szabo´, 2002). The presence of two types of ligands (X ¼ F, Y ¼ RCOO) and a variety of coordination geometries usually gave rise to a number of different ternary complexes that were simultaneously present in the solutions. In the presence of carbonate or glycolate ligands, the formation of dinuclear ternary complexes, ðUO2 Þ2 Fq ðglyÞ4qp p and ðUO2 Þ2 Fq ðCO3 Þ4q2p , was reported. Although a variety of species were p present in the solutions studied, the rate constants and the activation parameters for fluoride exchange were not strongly dependent on the identity of the carboxylate ligand, even for chelating ligands containing other coordinating groups (e.g. picolinic acid, glycine, and N‐(phosphonomethyl) glycine). Coordination of negatively charged carboxylate ligands (Yz) has little effect on the equilibrium constants for fluoride complexation by UO2 Y2qz in contrast to q fluoride complexation by UO2 ðH2 OÞ2þ (Aas et al., 1998). q The small amount of quantitative information regarding ternary complexes in aqueous solution limits attempts to model the chemical speciation of actinides in chemical systems when many different ligands are present. Nevertheless, the regularity of electrostatic bonding in actinide complexes (Section 23.4) makes estimation of the formation constants possible, allowing evaluation of the possible importance of a hypothesized species to determine if additional experimental work would be justified. The thermodynamic parameters for the formation of simple 1:1:1 An(X)(Y) ternary complexes often can be estimated from the parameters of the binary AnX and AnY complexes (Grenthe and Puigdomenech, 1997); however, the uncertainty in an estimated formation constant for these complexes can approach an order of magnitude. The most accurate estimated equilibrium constants for the formation of ternary complexes should include corrections for the appropriate change in the effective charge of the actinide caused by the complexation of the first ligand and for the decrease in the number of available coordination sites, which is an entropic (statistical) factor.

23.9

CATION–CATION COMPLEXES

Most studies of actinide complexation have involved interaction of actinide cations with neutral or anionic ligands as nearly all of the known complexes are with such ligands. However, the cationic, trans‐dioxoactinide(V) (i.e. actinyl(V)),

2594

Actinides in solution: complexation and kinetics

species form weak complexes with polyvalent metal cations in non‐complexing, 2þ acidic solutions, as first observed for the complexes of NpOþ 2 with UO2 þ (Sullivan et al., 1961). Cation–cation complexes of UO2 (Newton and Baker, þ 1962), PuOþ 2 (Newton and Burkhart, 1971), and AmO2 (Rykov and Frolov, 1975) with various cations have also been reported. Actinyl(V) cations are not the only dioxocation species that form cation–cation complexes. A complex of 2þ pentavalent cis‐dioxovanadium(V), VOþ 2 , with oxovanadium(IV), VO , also has been reported (Madic et al., 1983b).The formation of cation–cation complexes is not an inherent property of all actinyl ions. The presence of a pentavalent actinyl(V) cation is required to form cation–cation complexes. The actinyl(VI) cations, which have the same structure as the actinyl(V) cations, form cation–cation complexes only with an actinyl(V) cation. The nature of the species formed in cation–cation complexes has been a focus of investigation since their discovery. Three different models have been proposed. In one model, cation–cation complexes were treated as products of incomplete redox reactions accompanied by the formation of electron–hole pairs in the solvent (Rykov and Frolov, 1972a, 1974). However, this model postulated the formation of solvated electrons, which are not observed in the EPR spectrum of the Np(V)U(VI) complex (Madic et al., 1979). Another model proposed that the cation–cation complexes are polynuclear, ligand‐bridged complexes (Guillaume et al., 1982; Nagasaki et al., 1992) by analogy with oligomeric AnO2þ 2 hydroxides such as (UO2)2(OH)2. However, cation–cation complexes are stable in acidic solutions (2 M HClO4), and it is not apparent why water molecules or perchlorate anions would be effective bridging ligands for polynuclear species requiring participation of AnOþ 2 cations, as these cations generally form comparatively weak complexes with normal ligands. In the model most used, the cation–cation complexes are the result of bonding between AnOþ 2 cations either as inner sphere (Sullivan, 1962) or outer sphere complexes (Stout et al., 1993). Although the actinyl(V) cations possess a formal þ1 charge, the effective charge of the actinide atom is approximately þ2.2 (Choppin and Rao, 1984). This observation implies that each of the ‐yl oxygen atoms has a residual negative charge of ca. –0.6 that allows them to form moderately weak electrostatic bonds with other cations (Vodovatov et al., 1979). Relativistic spin–orbit configuration interaction calculations on NpOþ 2 resulted in a value for the residual negative charge of 0.48 on each of the neptunyl(V) oxygens while the calculated residual charge on the oxygen atoms of neptunyl(VI) was 0.17 (Matsika and Pitzer, 2000). If the residual negative charge on the oxygen atoms of actinyl(VI) cations is indeed so much smaller than it is for the actinyl(V) cations, the formation of cation–cation complexes by actinyl(V) ions but not by actinyl (VI) ions can be understood. However, a different explanation for the lack of actinyl(VI) cation–cation complexes is required if the empirical effective positive charges on the actinyl (VI) (ca. þ3.2) and actinyl(V) (ca. þ2.2) cations are more accurate reflections of the electron distribution in the actinyl cations than are these theoretically

Cation–cation complexes

2595

computed electron distributions. The effective positive charges measured for the pentavalent and hexavalent actinyl cations (Choppin and Rao, 1984) predict that the ‐yl oxygen atoms of actinyl cations carry approximately the same partial negative charge, –0.6, regardless of the oxidation state of the actinyl cation. Therefore, the attractive electrostatic force between the negatively charged ‐yl oxygen atoms and a given cation would be the same for both oxidation states. Under this model, the lack of actinyl(VI) cation–cation complexes must be attributed to the cancellation of the attractive electrostatic force between the cation and the ‐yl oxygen atoms by the larger repulsive force between the effective þ3.2 charge of the central hexavalent actinide atom and the positive charge of the other cation. Regardless of which mechanism is correct, the formally cationic actinyl(V) ions can assume the normal role of ligands, forming electrostatic bonds with other cations through the actinyl oxygen atoms, which carry a substantial, partial negative charge. The actual structures of cation–cation complexes in solution can be surmised from the combination of several different lines of structural evidence. The 3þ magnetic splitting of the Np Mo¨ssbauer spectra of NpOþ and NpOþ 2  Cr 2 3þ Rh adsorbed on cation exchange resin were interpreted as being consistent with axially symmetric NpOþ 2 (Karraker and Stone, 1977). Wide angle X‐ray þ scattering measurements of solutions containing either NpOþ 2  NpO2 or þ 2þ ˚ in the radial NpO2  UO2 cation–cation complexes show a peak at 4.2 A distribution function, which was assigned as the distance between nearest neighbor actinide atoms in the cation–cation complexes (Guillaume et al., þ 1983). Also, inner sphere NpOþ 2 NpO2 cation pairs have been observed in a number of crystalline neptunyl(V) complexes (Cousson et al., 1984; Tomilin et al., 1986; Grigor’ev et al., 1993a–c, 1995). In the solid state, two structural þ motifs for NpOþ 2  NpO2 complexes, the staggered and the ‘T‐shaped’ dimers (Fig. 23.24), with significantly different cation–cation distances, have been observed. The Np–Np distances of the T‐shaped dimers, like those observed ˚ (Grigor’ev et al., 1995), are excellent matches for in NpO2ClO4 · 4H2O, 4.20 A þ the X‐ray scattering results from aqueous solutions of NpOþ 2  NpO2 comþ plexes (Guillaume et al., 1983). Polymeric NpO2 cation–cation structures have not been observed in solution. Taken together, these experiments confirm the T‐shaped solution phase coordination geometry initially suggested by Sullivan (1962) and imply that these are inner sphere complexes. The stability constants for the formation of cation–cation complexes are invariably small. Typical constants reported for the equilibrium zþ ! AnOþ AnO2 Mðzþ1Þþ 2 þM

range from 0.1 to 16 M1 in aqueous solution, depending on the cations involved and the ionic strength. In organic media the equilibrium constants may be much larger (Rykov and Frolov, 1972b; Musikas, 1986). The enthalpies and entropies

2596

Actinides in solution: complexation and kinetics

þ Fig. 23.24 Inner sphere cation–cation interactions showing staggered NpOþ 2  NpO2 and 2þ T‐shaped NpOþ  UO complexes. 2 2

Table 23.24 Thermodynamic parameters of aqueous NpO2þ–cation complexes at 25 C. Data taken from Sullivan (1964), Murmann and Sullivan (1967), Madic et al. (1979), and Stout et al. (1993). Cation

DG (kJmol1)

DH (kJmol1)

DS (JK1 mol1)

Ionic strength (M)

Cr3þ Rh3þ NpO2þ 2 UO2þ 2 NpOþ 2

2.96 2.37 2.01 2.72 0.9

14 15 0 12 0

38 42 þ9 34 þ3

8.0 8.0 7 6.0 6.0

of complexation in aqueous solutions also are relatively small (Table 23.24). Such small or negative DH and DS values often indicate outer sphere complexation (Choppin, 1997). However, the reported DH and DS values also would be in agreement with the accumulated structural data and the formulation of the complexes as inner sphere, O¼An¼Oþ–Mzþ, complexes if the hydration sphere about the resulting complex is more ordered than the hydration spheres of the individual cations are (Stout et al., 1993). The redox reaction rates of AnOþ 2 ions are often influenced by complex formation with other cations present in the solution. Despite the small stability constants of these complexes ( NpO2 > AmO2 > PuO2 , with a stability constant of b ¼ 16 for the 2þ þ 2þ most stable complex, UOþ and 2  UO2 . The complexes NpO2  UO2 þ 2þ NpO2  NpO2 have about the same stability (Madic et al., 1979). Because 2þ the UOþ complex undergoes redox disproportionation at a much 2  UO2 slower rate than the simple UOþ 2 aquo ion, solutions of the relatively unstable uranium(V) are significantly stabilized in the presence of UO2þ 2 .

Kinetics of redox reactions

2597

23.10 KINETICS OF REDOX REACTIONS

The redox reactions of the lighter actinides, which often have several oxidation states of almost equal reduction potentials (e.g. plutonium, Fig. 23.1) are particularly challenging systems. The An(IV)–An(III) and the An(VI)–An(V) couples involve simple electron loss or gain (Newton, 1975; Sullivan and Nash, 1986). The An(VI)–An(IV) and An(V)–An(IV) redox half‐reactions include metal–oxygen bond formation or rupture, as well as electron gain or loss, because of the dioxo structure of the actinyl(V) and actinyl(VI) cations. The redox behavior of the actinides is complicated further by the possibility of disproportionation reactions at macro (but not at micro) concentrations.

23.10.1

Electron exchange reactions

Examples of reactions where the An–O bonds in the actinyl ions are not broken are processes such as ! Anð1Þ4þ þ Anð2ÞOþ Anð1Þ3þ þ Anð2ÞO2þ 2 2 where An(1) and An(2) denote actinide ions that retain their structures (e.g. An(1)zþ or Anð2ÞOzþ 2 ). A number of such reactions, involving uranium, neptunium, and plutonium as reductants and oxidants, have been carefully studied (Table 23.25) (Fulton and Newton, 1970). Though these reactions are fast, the rates vary within wide limits; for example, the oxidation of U3þ by UO2þ 2 or 3þ 2þ Np3þ by NpO2þ , respectively, are extremely fast while that of Np by UO 2 2 3þ 2þ or of Pu by NpO2 are much slower. The difference is not due to the fact that the latter reactions involve different actinides, since the oxidation of Pu3þ by PuO22þ is even slower than the Np3þ þ UO2þ and the Pu3þ þ NpO2þ 2 2 reaction rates. The rates of reaction are closely connected with the Gibbs energies, enthalpies, and entropies of activation (DG*, DH*, and DS*). These have been determined from the temperature dependence of the rate constants and are listed in * Table 23.25 for the formation of the activated complex [An(1)An(2)O5þ 2 ]   along with the equilibrium thermodynamic reaction values DG , DH , and DS for the redox reaction. The equilibrium values of the entropy changes, DS , are practically the same in all the reactions. This is because the hydration of the actinide ions in a particular oxidation state is fairly independent of the particular element involved. The values of DS are very negative, implying that the formation of strongly hydrated M4þ ions brings about a considerable net increase of order in the solutions. However, the values of DH , and, consequently, the values of DG , differ considerably between the various systems in such a way that the fastest reactions are also the most exothermic. The reactions rate constants, k, do not decrease monotonically as the reactions become less exothermic.

2598

Actinides in solution: complexation and kinetics

The activation parameters provide insight into the source of the large differ3þ ences in the reaction rates. The three reactions U3þ þ UO2þ þ NpO2þ 2 ; Np 2 , 2þ 3þ and Pu þ PuO2 are all first order in each of the reactants and independent of Hþ in the range of acidities measured (0.040.6 M, 0.010.1 M, and 0.11.0 M perchloric acid, respectively, at constant ionic strength) (Newton and Fulton, 1970). This implies that the reactions proceed via an activated complex [An(1) * 3þ An(2)O5þ þ NpO2þ 2 ] . The reaction Pu 2 , also progresses through formation of this activated complex. Since the rate depends upon the acidity, a parallel  reaction path via a hydrolyzed complex ½PuðOHÞNpO4þ 2 was proposed 2þ 3þ (Fulton and Newton, 1970). In the case of Np þ UO2 , the conditions are complicated by the presence of two parallel reactions following the initial reaction (Newton, 1970): þ 4þ Np3þ þ UOþ þ U4þ þ 2H2 O 2 þ 4H ! Np

and þ 2þ 4þ þ 2H2 O 2UOþ 2 þ 4H ! UO2 þ U

At high acidities, these reactions are fast, despite the need to break the U–O ‐yl bonds in UOþ 2 . As the reaction proceeds in 1.0 M acid, the concentration of uranyl(V) reaches a maximum, then decreases, while the concentration of uranium(IV) produced by the reaction of Np3þ with UOþ 2 steadily increases after a slow beginning. The activation parameters listed in Table 23.25 refer to the * activated complexes [An(1)An(2)O5þ 2 ] . The rates of the two fastest reactions are due to different causes. For U3þ þ UO2þ 2 , the rate is due to the less negative activation entropy while for * Np3þ þ NpO2þ 2 , it is due to the less endothermic enthalpy. The values of DH 2þ 2þ 3þ 3þ are not very different for U þ UO2 and Pu þ PuO2 , but the values of DS* are quite different. The faster rates of the mixed systems Np3þ þ UO2þ 2 and 3þ Pu3þ þ NpO2þ þ PuO2þ 2 compared to Pu 2 are due primarily to the favorable values of DH*. 23.10.2

Reactions of An–O bond breakage

Redox reactions in which An–O bonds are broken or formed are represented by þ þ ! Anð1ÞOþ Anð1Þ4þ þ Anð2ÞO2þ 2 þ 2H2 O 2 þ Anð2ÞO2 þ 4H

in Table 23.26. Analogous to the oxidation of An3þ (Table 23.25), the rates have a first‐order dependence on the concentrations of each of the actinide reactants. However, the rates of the An4þ oxidations also depend upon the Hþ concentrations with exponents that vary from –1 to –3. For some reactions, a non‐integral exponent is found, indicating alternative paths with different orders of dependence on the acidity. The apparent second‐order rate constants are generally much smaller than the rate constants of the An3þ oxidation reactions.

5.5  104 1.05  105 2.7  100 3.9  101 3.55  101

Reaction

U3þ þ UO22þ Np3þ þ NpO22þ Pu3þ þ PuO22þ Np3þ þ UO22þ Pu3þ þ NpO22þ 46.0 44.4 70.5 64.4 64.2

DG* (kJmol1) 18.1 4.2 20.2 10.9 14.6

DH* (kJmol1) 93 134 169 178 166

DS* (JK1 mol1) 67 95 6.3 8.6 15

DGo (kJmol1) 112 141 40 36 61

DHo (kJmol1)

151 159 151 151 153

DSo (JK1 mol–1)

b

3 1 1(–2) 2(–1) 2(–3) 3

na

DG* (kJmol1) 111 66.9 69.5 80.8 93 111

k (M1 s–1) 4  107 22 3.1 5  10–2 7.5  10–4 2  107 157 76.1 73.6 102.9 129 158

DH* (kJmol1) 152 31 14 74 125 159

DS* (JK1 mol–1)

51.4 54.0 32.6 38.5 17.2 24.3

DGo (kJmol1)

111 7.1 28.9 31.4 – 79.5

DHo (kJ1 mol1)

198 205 205 234 – 184

DSo (JK1 mol1)

Order of the hydrogen ion dependence; if more than one reaction path was observed, the order of the less important path is given in parentheses. T ¼ 30 C.

2 2 2 2 1 1

U4þ þ UO22þ U4þ þ NpO22þ U4þ þ PuO22þ Np4þ þ NpO22þ Np4þ þ PuO22þb Pu4þ þ PuO22þ

a

I (M)

Reaction

Table 23.26 Apparent second‐order rate constants, activation parameters, and thermodynamic equilibrium parameters for the reaction þ þ þ þ  Anð1Þ4þ þ Anð2ÞO2þ 2 þ 2H2 O ! Anð1ÞO2 þ Anð2ÞO2 þ 4H in perchlorate media with 1.0 M H at 25 C. Data from Masters and Schwartz (1961), Newton and Baker (1965), Sullivan et al. (1960), Hindman et al. (1954), Newton and Montag (1976), and Rabideau (1957).

k (M1 s1)

Table 23.25 Rate constants (M1 s1), activation parameters, and thermodynamic equilibrium parameters for the reaction 4þ  Anð1Þ3þ þ Anð2ÞO2þ þ Anð2ÞOþ 2 ! Anð1Þ 2 in 1.0 M HClO4 at 25 C from Fulton and Newton (1970).

Actinides in solution: complexation and kinetics

2600

The strong tendency for hydrolysis of An4þ sets a lower limit on the acidity of the solutions which can be investigated, ca. 0.1 M. Inverse acidity dependence is displayed by the reactions U4þ þ UO2þ 2 and Pu4þ þ PuO2þ 2 , which have similar slow rates and almost equal activation parameters, indicating they proceed along analogous paths. By contrast, U4þ þ NpO2þ and U4þ þ PuO2þ 2 2 , which also display inverse linear acidity dependence, are the fastest of these reactions with similar values for the activation parameters. The large increase in the rate is due to the much more favorable values of DH*. The values of DS* are less favorable, reducing somewhat the influence of the more favorable values of DH*. Generally, the slow rates of An4þ oxidation are due to very positive values of DH*. Positive values of DS* favor the process but are insufficient to compensate for the influence of DH*. Both the DH* and DS* values of An4þ oxidation differ significantly from those of An3þ oxidations (Table 23.25). These trends are even more marked in the thermodynamic equilibrium parameters in Tables 23.25 and 23.26 for the two types of reactions. The values of DSo are negative in An3þ oxidation reactions due to the formation of the strongly hydrated An4þ ions but they are positive for the oxidation reactions in the An4þ systems as this reaction is accompanied by release of water from the inner coordination sphere of the tetravalent cation. By contrast, the An3þ oxidations are exothermic, while the An4þ oxidations are endothermic. Thus, DHo opposes DS in both sets of reactions and the result is a mixture of values for the Gibbs energy changes of these oxidation reactions.

23.10.3

Redox disproportionation reactions

The disproportionation of actinyl(V) ions, AnOþ 2 , is the reverse of the An4þ þ AnO2þ oxidation–reduction reactions. In Table 23.27, the rates and 2 þ activation parameters of the disproportionation reactions of UOþ 2 ; NpO2 , and þ þ PuO2 are listed. These rates vary from UO2 reacting quite rapidly to NpOþ 2

Table 23.27 Apparent second order rate constant and activation parameters for the þ 4þ disproportionation reaction 2AnOþ þ AnO2þ 2 þ 4H ! An 2 þ 2H2 O in perchlorate media, [Hþ] ¼ 1.0 M at 25 C from Ahrland (1986).

UO2þ NpO2þ PuO2þ a

I (M)

na

k (M1 s–1)

DG* (kJmol1)

DH* (kJmol1)

DS* (JK1 mol1)

2 2 1

1 2 1

4  102 9  109 3.6  103

60 119 87

46 72 79

46 159 24

Acid dependence of the rate constant.

Kinetics of redox reactions

2601

reacting extremely slowly. The fast reaction rate of UOþ 2 is due to a low value of DH* while the slow rate of NpO2þ is due, to a large negative value of DS*. For both the redox and the disproportionation reactions, the lower the charge of the activated complex, the lower the DS* value. For the formation of AnOþ 2 ions, the more negative the exponent of the hydrogen dependence, the more positive the DS* value. For the disproportionation reactions, the more positive the exponent of the hydrogen dependence, the more negative the DS* value. All of the AnOþ 2 ions listed disproportionate at a faster rate in D2O (Rabideau, 1957; Hindman et al., 1959). Also, the reaction rates of MOþ 2 ions are often influenced by complex formation with cations present in the reaction. These cation–cation complexes are discussed in Section 23.9. Their formation results in a slower rate of oxidation of the AnOþ 2 species by a number of oxidizing agents. 23.10.4

Effect of complexation

All reactions discussed so far take place between hydrated metal ions in non‐ complexing perchlorate media. In the presence of complex formation with anions, the reaction rates usually increase significantly. This was noticed initially for chloride and sulfate solutions. For example, plutonium(IV) disproportionates about five times faster in hydrochloric acid than in perchloric acid of the same concentration (Rabideau and Cowan, 1955). A study of sulfate media containing Np(IV), Np(V), and Np(VI) revealed that the rate of formation of neptunium(V) depends upon the concentration of the complexes NpSO2þ 4 and NpO2SO4, while disproportion depends upon the concentration of HSO 4 (Sullivan et al., 1957). For both reactions, the rate laws are not simple. With increasing sulfate concentration, the rate of formation initially increases, reaches a maximum, then decreases. The maximum coincides with the maximum concentration of NpSO2þ 4 as the higher sulfate complexes have no catalytic effect. The rate of disproportionation, by contrast, is a monotonically increasing function of the concentration of HSO 4 . Table 23.28 lists the parameters for the reduction reactions of NpO2þ by complexing anions. 2 In the disproportionation of americium(V), analogous catalytic effects have been observed (Coleman et al., 1963). In perchloric acid, the reaction 3þ þ ! þ 2H2 O 3AmOþ 2AmO2þ 2 þ 4H 2 þ Am

occurs, with a rate dependence on the hydrogen ion between 2 and 3. At 76 C, and an acidity of 2 M, the rates in nitric, hydrochloric, and sulfuric acids are 4, 4.6, and 24 times as great as that in perchloric acid. Similar effects have also been found for several other systems. Comparison of the rate constants for the reaction of [(NH3)6Co]3þ and  3þ      [(NH3)5CoX]2þ (X ¼ N indicate 3 ; F ; Cl ; ac ; Br ; CN , or NCS ) with U that these reactions proceed by an inner sphere mechanism. The activation parameters for the analogous reaction of Np3þ with (NH3)5RuX3þ (X ¼ H2O

Actinides in solution: complexation and kinetics

2602

Table 23.28 Rate constant and activation parameters for the reduction of Np(VI). Data from Rao and Choppin (1984), Kim and Choppin (1988), and Choppin and Kim (1989). k1 (s1)

DH* (kJmol1)

DS* (JK1 mol–1)

Dicarboxylic acids (I ¼ 0.10 M NaCl) oxalic acid 1.1 33.7 malonic acid 2.2 34.2 methylmalonic acid 2.4 34.7 dimethylmalonic acid 3.0 35.2 succinic acid 3.0 34.0 maleic acid 3.0 35.9 phthalic acid 3.0 34.1 fumaric acid 3.0 23.1

1.30  103 2.70  103 1.06  104 3.10  105 1.50  104 1.00  104 5.20  105 1.80  105

90  7 70 10 88  9 43  13 66  9 87  12 38  8 37  23

7  21 64  25 16  29 183  33 103  42 43  42 209  25 209  84

Hydroxylic acids (I ¼ 1.0 M NaCl) kojic acid 4.6 25.0 tropolone 25.0

1.6 70.8

83  3 67  3

Reductant

pH

T ( C)

34  1 15  12

and NH3) (Espenson and Wang, 1970; Lavallee et al., 1973) supported this proposal, indicating formation of a seven‐coordinate Ru(III) intermediate.   Other bridging ligands such as SO2 4 ; ClO4 ; Cl , etc. have an accelerating effect on the reaction rate. This was attributed to a reduction in the cation– cation electrostatic repulsion through the formation of the intermediate An3þXxMzþ.

23.11 KINETICS OF COMPLEXATION REACTIONS

The complexation and dissociation of actinide cations with anions of simple structure are more rapid than the analogous rates of reaction of the d‐transition cations. These fast reaction rates are due to the strongly ionic nature of most actinide–ligand bonds, which results in a wide range of hydration and coordination numbers and symmetries. This structural versatility arises from the lack of strong crystal‐field effects in 5f electronic configurations as well as from the relatively large ionic radii of these cations as the coordination numbers and symmetries are determined by steric and electrostatic factors (see Sections 23.4 and 23.6). The complexation reactions usually proceed by the Eigen mechanism (Diebler and Eigen, 1959; Eigen and Tamm, 1962; Eigen, 1963). This mechanism involves two steps, the rapid formation of an outer sphere association complex (i.e. an ion pair) and the subsequent rate‐determining step in which the ligand displaces one or more water molecules. z ! z ! MðH2 OÞmþ MðH2 OÞmþ MðH2 OÞq1 LðmzÞ þ H2 O q þL q L

Kinetics of complexation reactions

2603

The actual ligand‐interchange step may be dissociative or associative in character. For multidentate ligands, the associative steps with replacement of two‐ coordinated water can be represented as

In the absence of any steric constraints, formation of the first M–L bond, generally, but not always, leads to rapid ring closure. As the chain distance separating the two donor atoms of the ligand increases, the rate (or probability) of ring closure decreases (Wilkins, 1974, Burgess, 1978). This is reflected in a decrease in logb11 and a deviation from linearity in plots of logb11 versus SpKa (see Section 23.6). In some systems it is uncertain whether this increase in donor separation is accompanied by a change from chelation to monodentation. Microscopic reversibility requires that complex dissociation reactions follow the formation pathway in reverse. Complex dissociation is typically investigated by addition of a competing metal ion or of a chelating agent that binds more strongly to the cation. Complex dissociation reactions are often catalyzed by Hþ in acidic solution. A variety of experimental techniques have been used to study actinide complexation kinetics. These include stopped‐flow spectrophotometry, pulse radiolysis, temperature‐jump, NMR, solvent extraction separation methods, and conventional spectrophotometry. According to the Eigen mechanism for complexation, the rate of solvent water exchange represents an upper limit to the rate of complex formation. Such rates are not available for the trivalent actinides but have been discussed for the chemically analogous lanthanides. Cossy et al. (1989) have reported that the second‐order rate constants for water exchange are directly proportional to the cation radii of trivalent lanthanides. The water exchange rates for Am(III)Cf(III) are estimated to range from 1  109 to 1  108 M1 s1 assuming a linear correlation with the lanthanides based on cation radius (Nash and Sullivan, 1998). Kiener et al. (1976) report that the water exchange rates for UO2þ 2 are complex. Exchange rates for tetravalent and for pentavalent actinide cations have neither been reported, nor can they be estimated reliably. Bardin et al. (1998) have reported NMR data that give a first order rate constant for 6 –1  water exchange by UO2þ 2 in d6‐acetone of 1  10 s at 25 C. The complexation kinetics of multidentate ligands are slower than for monodentate ligands due to the changes in ligand structural characteristics during the reactions. The aminopolycarboxylates have been used commonly in actinide separations, and, as a result, their kinetics of complexation with the An(III) cations have been studied in more depth than for any other An(III)–ligand system. Such studies usually involve metal exchange in which the An(III) cation displaces a trivalent lanthanide from complexation with an aminopolycarboxylate complex. For the reaction of An(III) with the Eu(III)–ethylenediaminetetraacetate complex (D’Olieslager et al., 1970; Williams and Choppin, 1974), the rate was shown to be described by the equation:

2604

Actinides in solution: complexation and kinetics Rate ¼ ðka ½EuðedtaÞ ½H ½An =½Eu þ kb ½EuðedtaÞ ½An Þ  ðkc ½AnðedtaÞ ½H þ kd ½AnðedtaÞ ½Eu Þ

ð23:14Þ

in which the ionic charges are omitted for simplicity. The specific rate constants ka and kc are associated with the hydrogen ion catalyzed forward and reverse terms, while kb and kd are specific rate constants for the respective acid‐independent terms. Below about pH 6 the hydrogen‐catalyzed paths dominate the reaction. In these paths, the metal complex is protonated in a series of proton additions, leading ultimately to the decomposition of the complex and hence to metal exchange. The alternate acid‐independent path in the exchange mechanism has been described by a metal ion‐catalyzed decomposition of the complex in which the ligand serves as a bridge between the entering and exiting metal ions. The exchange reactions can be represented as follows (Y ¼ edta4–). (A) Acid‐dependent mechanism

(B) Acid‐independent mechanism

The formation and dissociation reactions of other aminopolycarboxylate complexes of Ln and An cations follow these general mechanisms. The rates of metal ion exchange for the trivalent actinides (Am, Cm, Bk, Cf ) with Eu(edta) indicate a similar dependence on acidity and, in cases where an acetate buffer was used, an additional dependence on free acetate concentration (Choppin and Williams, 1973; Williams and Choppin, 1974). The rates of formation and dissociation of the Am(III) complex with dcta4– (trans‐1,2‐diaminocyclohexane‐N,N,N0 ,N0 ‐tetraacetate, Fig. 23.18) were determined using stopped‐flow spectrophotometry to study the formation reaction and conventional spectrophotometry for the decomposition reaction (Sullivan et al., 1978). The experimental results are consistent with the interpretation that a precursor between Am(III) and the ligand is formed. The rate‐determining step in the reaction was postulated to be the formation of a bond between Am(III) and an imino nitrogen of dcta4. The dissociation of the Am(dcta) complex was studied by the metal ion exchange technique using Cu2þ, as was reported in an analogous study of the

Kinetics of complexation reactions

2605

Ln(dcta) chelates (Nyssen and Margerum, 1970). No dependence on the copper concentration was observed, implying that any reaction rates measured were pertinent to either acid‐induced or spontaneous dissociation of the complex. The results agree with studies on the rate of dissociation of trivalent actinides with a variety of aminopolycarboxylate complexants studied by solvent extraction or ion exchange separation techniques at radiotracer concentrations of the metal ion (D’Olieslager et al., 1970; Choppin and Williams, 1973; El‐Rawi, 1974; Williams and Choppin, 1974; Muscatello et al., 1989). The rate‐ determining step for complex formation is an acid‐dependent intramolecular process that appears to be limited by the rate of formation of An(III) bonding to the amine nitrogen. The activation parameters for the reaction were reported to be Ea ¼ þ59.0 kJmol1 and DS* ¼ –19 JK1 mol1 (Sullivan et al., 1978). The rate of dissociation of trivalent actinide (Am, Cm, Bk, Cf ) complexes with the aminopolycarboxylate ligands hedta3 (N‐hydroxyethylethylenediaminetriacetate) and tmdta4 (trimethylenediaminetetraacetate) have been measured (El‐Rawi, 1974; Muscatello et al., 1989). As in the case for the edta complexes, the rate of the acid‐catalyzed dissociation decreases with increasing cation atomic number (Fig. 23.25), which is consistent with a simple electrostatic model for the interactions of both lanthanides and actinides. The dissociation rate of Am(dcta)– was observed to be more similar to that of the isoelectronic Eu(dcta) than to the dissociation rate of Nd(dcta), whose cationic radius (and, hence, electrostatic attraction for the ligand) is closest to that of Am3þ.

Fig. 23.25 Correlation of the rate constant of the acid dependent dissociation pathway, kD, of MY (Y ¼ edta4– or tmdta4–) and the reciprocal of the cation radius (CN ¼ 6).

2606

Actinides in solution: complexation and kinetics Table 23.29 Rate constants (M–1 s–1, 25 C) for the reaction kF

An3þ þ HY 3 Ð AnY  þ H þ : kD

dcta4

tmdta4

edta4

Metal ion

107 kF

104 kD

108 kF

kD

1010 kF

102 kD

Am Cm Bk Cf Eu

5.5  0.9 8.8  1.2 8.8  1.6 1.3  1.0 3.2  0.4

4.78  0.49 3.52  0.22 0.95  0.10 0.39  0.02 2.29  0.13

1.2 2.4 – – 0.34

4.4 2.8 – – 3.2

0.59 1.0 1.2 0.85 0.32

1.39 1.10 0.57 0.25 2.28

This result suggests a possible minor covalent contribution in the binding of Am(III) to the amine (Nash and Sullivan, 1998). The dissociation rate constants for the trivalent actinide complexes with tmdta4, as seen in Fig. 23.25, are about two orders of magnitude larger than for the corresponding An(edta) complexes. This is most probably due to the greater lability of the Am–N bonds in the six member N–Am–N ring of the tmdta complex when compared to the lability of the Am–N bonds in the five‐ membered N–Am–N ring of the edta chelate. In contrast to the tmdta complex, the acid‐dependent rate constant for the acid dissociation of the Am(dcta) complex is log kD ¼ 0.64, which is two orders of magnitude smaller than that for Am(edta) (Sullivan et al., 1978). This was attributed to the structural effect of the rigidity of the cyclohexyl ring. Table 23.29 lists the values for both the formation and dissociation rate constants for actinide(III) complexes of tmdta4, dcta4, and edta4 from Muscatello et al. (1989).

23.12 SUMMARY

Although the aqueous complexes of the actinide elements has been a topic of continual interest for over half a century, puzzles remain to be solved and opportunities abound because such complexes are central to understanding the environmental, biological, and separations chemistry of the actinides. Historically, most of this work has involved studies of complexation strength, and to a lesser extent, studies of the kinetics of reactions. Many different techniques have been used. Unfortunately, the utility of such thermodynamic and kinetic measurements diminishes the farther system conditions deviate from those used in the laboratory measurements. The presence of new kinetic pathways, unforeseen equilibria, or solid phases that were not encountered in the laboratory studies can dominate the aqueous speciation when the concentrations of

Summary

2607

the solution components or pH values are significantly different from the conditions that have been studied. For instance, the U–O bonds of the UO22þ cation are quite inert in acidic aqueous solutions with a half‐life for oxygen exchange of 4  104 h in 1 M perchloric acid (Gordon and Taube, 1961), but in 3.5 M tetramethylammonium hydroxide, the exchange is complete in minutes (Clark et al., 1999). As a result, other techniques for studying actinide complexes, such as NMR, fluorescence spectroscopy, and EXAFS have become increasingly important sources of extra‐thermodynamic information on dissolved actinide complexes in recent years. While the information available on the solution complexation of the actinide elements covers a range of actinide ions, oxidation states, and ligands, it can usually be understood by several straightforward principles. The actinide cations are hard Lewis acids that interact preferentially with ligands that are hard Lewis base donors, in aqueous solution, forming strongly electrostatic bonds. Thus, the complexes generally become more stable as the effective charge of the actinide cation or ligand increases and as the size of the actinide cation decreases, if metal‐ or ligand‐centered steric constraints are not important. This is best characterized for the An(III) and An(IV) oxidation states. However, the limited number of actinide cations that are stable in several of the oxidation states from 3þ to 6þ, and the short half‐lives of the trans‐californium elements limit the number of actinide species that can be studied by many techniques for use in systematic, empirical comparisons of the metal ion properties. The electrostatic model of actinide–ligand bonding can be very useful despite its simplicity. However, accurate, quantitative, and non‐empirical predictions of the strength and structure of actinide complexes are currently only possible for the simplest ligands because of ligand‐ and solvent‐centered effects. Many areas of actinide complexation chemistry remain relatively unexplored. Topics in actinide complexation which are only beginning to be defined include actinide complexation by neutral ligands in aqueous solutions, the formation of ternary complexes, and the behavior of actinide complexes in alkaline solutions. In addition, studies of ligands that are capable of stabilizing difficult to attain oxidation states; studies of ligands with well defined, pre‐organized actinide binding sites; and studies of actinide–selective soft donor ligands have the potential to create new perspectives in actinide chemistry.

ACKNOWLEDGMENTS

This chapter incorporates portions of Chapter 21, Solution Chemistry and Kinetics of Ionic Reactions by Sten Ahrland from The Chemistry of the Actinide Elements, second edition. Preparation of this chapter was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences at Argonne National Laboratory (Contract No. W‐31‐109‐ENG‐38) and at Florida State University.

2608

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Stary´, J. (1966) Talanta, 13, 421–37. Stemmler, A. J., Kampf, J. W., and Pecoraro, V. L. (1996) Angew. Chem. Int. Edn. Eng., 35, 2841–3. Stepanov, A. V. (1971) Russ. J. Inorg. Chem., 16, 1583–6. Stout, B. E., Caceci, M. S., Nectoux, F., and Page`s, M. (1989) Radiochim. Acta, 46, 181–4. Stout, B. E., Choppin, G. R., Nectoux, F., and Page`s, M. (1993) Radiochim. Acta, 61, 65–7. Stradling, G. N., Gray, S. A., Ellender, M., Moody, J. C., Hodgson, A., Pearce, M., Wilson, I., Burgada, R., Bailly, T., Leroux, Y. G. P., Elmanouni, D., Raymond, K. N., and Durbin, P. W. (1992) Int. J. Radiat. Biol., 62, 487–97. Stumpf, T., Fangha¨nel, T., and Grenthe, I. (2002) J. Chem. Soc., Dalton Trans., 3799–804. Sullivan, J. C. and Hindman, J. C. (1954) J. Am. Chem. Soc., 76, 5931–4. Sullivan, J. C., Cohen, D., and Hindman, J. C. (1955) J. Am. Chem. Soc., 77, 6203–4. Sullivan, J. C., Cohen, D., and Hindman, J. C. (1957) J. Am. Chem. Soc., 79, 4029–34. Sullivan, J. C., Zielen, A. J., and Hindman, J. C. (1960) J. Am. Chem. Soc., 82, 5288–92. Sullivan, J. C., Hindman, J. C., and Zielen, A. J. (1961) J. Am. Chem. Soc., 83, 3373–8. Sullivan, J. C. (1962) J. Am. Chem. Soc., 84, 4256–9. Sullivan, J. C. (1964) Inorg. Chem., 3, 315–19. Sullivan, J. C. and Zielen, A. J. (1969) Inorg. Nucl. Chem. Lett., 5, 927–31. Sullivan, J. C., Gordon, S., Cohen, D., Mulac, W. A., and Schmidt, K. H. (1976) J. Phys. Chem., 80, 1684–6. Sullivan, J. C., Nash, K. L., and Choppin, G. R. (1978) Inorg. Chem., 17, 3374–7. Sullivan, J. C. and Nash, K. L. (1986) in Inorganic and Bioinorganic Reaction Mechanisms, vol. 4 (ed. A. G. Sykes), Academic Press, London, pp. 185–213. Sullivan, J. C., Choppin, G. R., and Rao, L. F. (1991) Radiochim. Acta, 54, 17–20. Sutton, J. (1952) Nature, 169, 235–6. Swift, T. J. and Sayre, W. G. (1966) J. Chem. Phys., 44, 3567–74. Szabo´, Z., Aas, W., and Grenthe, I. (1997) Inorg. Chem., 36, 5369–75. Szabo´, Z. and Grenthe, I. (2000) Inorg. Chem., 39, 5036–43. Szabo´, Z., Moll, H., and Grenthe, I. (2000) J. Chem. Soc., Dalton Trans., 3158-61. Szabo´, Z. (2002) J. Chem. Soc., Dalton Trans., 4242–7 . Tochiyama, O., Inoue, Y., and Narita, S. (1992) Radiochim. Acta, 58/59, 129–36. Tochiyama, O., Siregar, C., and Inoue, Y. (1994) Radiochim. Acta, 66/67, 103–8. Tomilin, S. V., Volkov, Y. F., Kapshukov, I. I., and Rykov, A. G. (1981) Sov. Radiochem., 23, 570–4, 574–8, 695–9. Tomilin, S. V., Volkov, Y. F., Melkaya, R. F., Spiryakov, V. O., and Kapshukov, I. I. (1986) Sov. Radiochem., 28(3), 272–8. Toraishi, T., Farkas, I., Szabo´, Z., and Grenthe, I. (2002) J. Chem. Soc., Dalton Trans., 3805–12. Tsushima, S. and Suzuki, A. (2000) J. Mol. Struct. (THEOCHEM), 529, 21–5. Vallet, V., Wahlgren, U., Schimmelpfennig, B., Moll, H., and Szabo´, Z., Grenthe, I. (2001) Inorg. Chem., 40, 3516–25. Vallet, V., Wahlgren, U., Szabo´, Z., and Grenthe, I. (2002) Inorg. Chem., 41, 5626–33. Vdovenko, V. M., Romanov, G. A., and Shcherbakov, V. A. (1963) Sov. Radiochem., 5, 624–7.

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Vodovatov, V. A., Mashirov, L. G., and Suglobov, D. N. (1979) Sov. Radiochem., 21(6), 711–16. Wahlgren, U., Moll, H., Grenthe, I., Schimmelpfennig, B., Maron, L., Vallet, V., and Gropen, O. (1999) J. Phys. Chem. A, 103, 8257–64. Walch, P. F. and Ellis, D. E. (1976) J. Chem. Phys., 65, 2387–92. Wang, Z., Felmy, A. R., Xia, Y. X., and Mason, M. J. (2003) Radiochim. Acta, 91, 329–37. Werner, A. (1913) Neu Anschauungen auf dem Gebiet der anorganischen Chemie, 3rd edn, Vieweg Sohn, Braunschweig. Wilkins, R. (1974) The Study of Kinetics and Mechanisms of Reactions of Transition Metal Complexes, Allyn and Bacon, Boston. Williams, K. R. and Choppin, G. R. (1974) J. Inorg. Nucl. Chem., 36, 1849–53. Williams, C. W., Blaudeau, J.‐P., Sullivan, J. C., Antonio, M. R., Bursten, B. E., and Soderholm, L. (2001) J. Am. Chem. Soc., 123, 4346–7. Wimmer, H., Kim, J. I., and Klenze, R. (1992) Radiochim. Acta, 58/59, 165–71. Xu, J., Kullgren, B., Durbin, P. W., and Raymond, K. N. (1995) J. Med. Chem., 38, 2606–14. Yaozhong, C., Bingmei, T., and Zhangji, L. (1993) Radiochim. Acta, 62, 199–201. Yusov, A. B. and Shilov, V. P. (1999) Radiochemistry, 41, 1–23. Yusov, A. B. and Fedoseev, A. M. (2003) Russ. J. Coord. Chem., 29, 582–90. Zhao, P. H., Romanovski, V. V., Whisenhunt, D. W., Hoffman, D. C., Mohs, T. R., Xu, J. D., and Raymond, K. N. (1999) Solvent Extr. Ion Exch., 17, 1327–53. Zhu, Y., Chen, J., and Jiao, R. (1996) Solvent Extr. Ion Exch., 14, 61–8. Zielen, A. J. (1959) J. Am. Chem. Soc., 81, 5022–8. Zielen, A. J. and Cohen, D. (1970) J. Phys. Chem., 74, 394–405.

CHAPTER TWENTY FOUR

ACTINIDE SEPARATION SCIENCE AND TECHNOLOGY Kenneth L. Nash, Charles Madic, Jagdish N. Mathur, and Je´roˆme Lacquement 24.1 24.2 24.3 24.4

24.5

What does the future hold? Future directions in actinide separations 2768 References 2769

Introduction 2622 Historical development of actinide separations 2627 Fundamental features of actinide separation systems 2631 Applications of separations in actinide science and technology 2725

24.1 INTRODUCTION

Both the science and technology of the actinides as we know them today owe much to separation science. Conversely, the field of metal ion separations, solvent extraction, and ion exchange in particular, would not be as important as it is today were it not for the discovery and exploitation of the actinides. Indeed, the synthesis of the actinides and the elucidation of their chemical and physical features required continuous development and improvement of chemical separation techniques. Furthermore, the diverse applications of solvent extraction and ion exchange for metal ion separations as we know them today received significant impetus from Cold War tensions (and the production of metric tons of plutonium) and the development of nuclear power for peaceful uses. Solvent extraction, precipitation/coprecipitation, and ion exchange procedures have played a central role in the discovery and characterization of the 5f transition elements. Each of these separations techniques likewise has shaped progress in technological applications of actinides for electricity production and for nuclear weapons. Recent decades have seen the rise of pyroelectrometallurgical separations, wherein the long‐term future of actinide separations may lie. 2622

Introduction

2623

Efficient chemical separations are an essential feature of actinide science and technology because (1) aside from U and Th there are no primordial transuranic actinides and so no natural mineral deposits from which to isolate them and (2) the nuclear techniques employed to create actinides also induce fission in the heavy metal target atoms producing mixtures that can include up to one‐third of the periodic table. Whether for scientific purposes or technological applications, high degrees of purification of actinides from diverse solid solutions containing small amounts of the desired material in a complex solid matrix are required. This chapter addresses the details of these chemical separation processes and describes what the exercise of these separation processes has taught us about the chemistry of the actinides. Four specific separation tasks had to be accomplished to enable the discovery of the 5f elements and then to support creation of sufficient amounts of these elements to sustain their practical application: isolation of natural uranium from its mineral sources, isotope enrichment to increase the relative percentage of fissile 235U above that of natural uranium, separation of actinides from a diverse mixture of fission products, and separation of individual members of the series. The accomplishment of these tasks required innovative solutions to demanding problems. Setting aside the technologically essential process of isotope enrichment (not discussed in this chapter), separations of actinides can be considered at two scales: analytical‐scale separations conducted at low concentrations or with small amounts of the analyte, and large‐scale separations conducted on kilogram quantities of materials in large shielded facilities. Each of these carries unique opportunities and challenges. Analytical separations are best served by reagents that are both highly specific and very efficient (i.e. capable of quantitatively separating the target species in a single (or small number of ) contact(s)). Plant‐scale separations also perform best with highly specific reagents, but extremely high phase‐transfer efficiency typically is not preferred because materials must also be readily recovered from the separation matrix. Weak chemical separations processes can be overcome at plant scale by adding more repeat contacts (stages) of reagents. In a once through nuclear fuel cycle, there are no large‐scale separations subsequent to the preparation of the enriched uranium fuel. However, in the operation of a closed loop fuel cycle, it is necessary to separate the transuranium actinides individually or as a group from uranium and fission products. For the purpose of scientific discovery, it was (and is) necessary to isolate individual members of the series. The diverse redox chemistry of uranium, neptunium, and plutonium is the primary feature of processes for their isolation and purification. For the actinides beyond americium and in most applications for americium as well, the trivalent oxidation state predominates. The trivalent oxidation state is also prevalent in the lanthanides, which are produced in about one‐third of thermal neutron‐induced fission events in 235U and 239Pu. Most features of the chemistries of the trivalent transplutonium actinides and lanthanides are nearly identical.

2624

Actinide separation science and technology

Aside from the unique demands of trivalent actinide/lanthanide group separations, the discussions of separations systems below will consider features of lanthanide separations as representative of the behavior of trivalent actinides. The separation of individual trivalent actinides relies on the predominantly electrostatic bonding characteristics of the ions and on the steady reduction that is seen in the trivalent cation radii with increasing atomic number, a behavior paralleling that of the lanthanides. This small but (more‐or‐less) regular decrease in cationic radii provides an adequate driving force for ion exchange‐based separations of the individual members of the series, as will be described below. The actinides are as a group readily separated from most fission products, based on their unique chemistry as compared with the great diversity of species present. Typically, only Ru, Mo, Zr (under some circumstances), and the ubiquitous lanthanides represent a significant separations challenge. The isolation of individual trivalent transplutonium actinides from trivalent lanthanides can be readily achieved if the species to be separated are sufficiently differentiated based on cation radii. Specifically, the transplutonium elements can be readily separated from the light lanthanides, but with greater difficulty from those in the middle of the series. For an effective separation of the trivalent actinides from the lanthanides as a group or for ions having similar cation radii, it has proven essential to incorporate into the separation scheme donor atoms ‘softer’ than oxygen or fluoride. Poly‐aza ligands of complex geometries, chloride ions, thiocyanate ions, or species containing sulfur donor atoms have proven the most viable candidates. These soft‐donor reagents can appear in the separation schemes either as lipophilic extractant molecules or as water‐soluble complexing agents. Nearly 60 years of industrial scale implementation of aqueous processing schemes has produced both considerable insight into the ways and means of conducting these separations, and large waste disposal/environmental restoration challenges at the sites where such large‐scale processing has been conducted. The legacy of the massive volume of waste generated during these many years of aqueous processing to recover actinides from spent fuel has spurred efforts to develop radically different approaches. In particular, separations developed conceptually in the 1960s based on molten salts, molten metal, including electrochemical processing in these media, have received considerable attention in recent years for their potential as alternative large‐scale separations methods for spent fuel processing. Such methods tend to strongly favor reduced actinide species and radically different (though fundamentally simple) coordination chemistry for the actinide species in these media. Far less is known about the chemistry of actinides in supercritical fluids, room‐temperature ionic liquids, or other non‐conventional media, but any of these methods could play a central role in future nuclear fuel cycles. Processes based on volatility of certain actinide compounds have also received some attention and possess some interesting features. However, each of these concepts is far behind aqueous processing,

Introduction

2625

both because of the number of years of experience that have been accumulated for the aqueous option, and the unknowns always attendant to developing new science and technology. 24.1.1

Prior literature reviews/useful reference volumes

There are two categories of previous studies each serving a complementary role in describing actinide separation science: those providing ‘recipes’ for conducting separations of radioactive materials and those explaining the underlying principles. In the beginning, the chemical properties of the transuranium elements were a matter of informed speculation, so underlying principles were not known except by inference. Their discovery and the ultimate elucidation by Seaborg of the actinide hypothesis was a clear demonstration of the correctness (and utility) of Mendeleev’s periodic table. The chemical separation procedures that enabled actinide science as we know it today were based on belief in chemical periodicity. One remarkable aspect of actinide separation science is the enduring quality of many of the separations developed during the days of actinide discovery. This is a tribute to the talents and abilities of those early practitioners of actinide separation science. Perhaps the most useful (even today 40 or more years after their publication) detailed experimental separation procedures are those found in the National Academy of Science Series on radioanalytical chemistry. This series, published in the 1950s and 1960s, still constitutes a useful primary reference for formula separation schemes for the entire periodic table, including the actinides. Though individual bound volumes of these separation procedures are widely available, the series is long out of print. These volumes are however presently available online (http://lib‐www.lanl.gov/radiochemistry/elements.htm). Of course, the insights gained from these initial explorations have allowed the development of more general reference works and a better understanding of the chemical features of the processes. The classic reference book for aqueous separations chemistry (both ion exchange and solvent extraction) has long been Ion Exchange and Solvent Extraction of Metal Complexes by Marcus and Kertes (1969). In this book, the theory and practice of separation science is discussed in great detail. Solvent extraction chemistry has been reviewed by Sekine and Hasegawa (1977). In addition to concentrating on solvent extraction, this work differs from the Marcus and Kertes volume in that it has references to many more specific examples. Helfferich (1962) published a volume that is generally considered as the most authoritative discussion of the unique theoretical aspects of ion exchange‐based separations. Two ‘how‐to’ manuals have been published which describe in detail useful ion exchange separation procedures for the lanthanides and actinides (Korkisch, 1986a,b). Updates on the state of the art of f‐element separations have appeared in the literature at regular intervals. Jenkins (1979, 1984) reviewed ion exchange applications in the atomic energy industry. Symposium volumes entitled

2626

Actinide separation science and technology

Actinide Separations (Navratil and Schulz, 1980), Lanthanide/Actinide Separations (Choppin et al., 1985) and Separations of f Elements (Nash and Choppin, 1995) are collections of papers from several authors covering various aspects of lanthanide and actinide separations. Additional specialized reviews of specific topics have also appeared frequently. Most of these are considered below. The subject of lanthanide/trivalent actinide separations has been reviewed previously (Weaver, 1974; Nash, 1993a). Weaver’s review is an excellent source for a comprehensive discussion of solvent extraction separations of the lanthanides and trivalent actinides. Weaver discusses many of the historical aspects of lanthanide/actinide separations, and considers both the successes and failures in the separation of trivalent lanthanides and actinides. Nash’s review complements and updates the observations of Weaver, emphasizing the critical role played by soft‐donor ligands in the development of efficient processes for the selective separations of the trivalent 4f and 5f elements. Arguably, the most important reagent for actinide separations is tri(n-butyl) phosphate (TBP – structure a). This compound is the subject of a four‐volume handbook entitled The Science and Technology of Tributyl Phosphate (Schulz et al., 1990). Many chapters in this collection address important features of the application of TBP for nuclear fuel processing and actinide recovery. On the subject of large‐scale separations of actinides, the current state of the art in hydrometallurgical processing of actinides from spent fuel or radioactive wastes has been reviewed recently (Horwitz and Schulz, 1999; Mathur et al., 2001).

These reports describe and critically evaluate water‐based actinide partitioning research activities being conducted around the world. The diversity of activities being pursued worldwide is in some respects surprising. However, it does reflect the increasingly important nature of these separations. In truth, aqueous separations still dominate the actinide separations landscape. Contemporary research attempts to take a 21st century perspective on nuclear fuels processing, emphasizing the importance of closing the fuel cycle while minimizing the generation of wastes requiring geological disposal. 24.1.2

Scope of the chapter

The space available to this chapter simply does not allow for a comprehensive treatment of all aspects of the subject of actinide separations. Some selectivity will therefore be applied in the following discussion. All essential features of actinide separations will be discussed, but it will not be possible to include detailed step‐by‐step descriptions of all of the well‐known separation systems.

Historical development of actinide separations

2627

The reader will find such information among the several reviews noted above. Greater emphasis will be placed on the details of newer science and technologies, those currently being considered for advanced applications, and on those most appropriate methods to preserve long‐term options for nuclear fuels recycling in the 21st century. Because chemical separations have played such an important role in the discovery of the actinides, the chapter begins with a discussion of the early history of actinide separations. This discussion will be followed by some consideration of the fundamental chemistry of separation systems and of actinide behavior in phase transfer systems. The fundamental chemistry of actinides in aqueous solutions has been described in the previous chapter. It will therefore not be necessary to address the details of actinide behavior in solution in detail here. However, some aspects of the aqueous chemistry of actinides (redox, solvation, complexation) do play an important role in actinide separations, and so will receive an appropriate emphasis wherever needed in this chapter. The general features of phase transfer reactions will be discussed briefly, focusing on the differences between the classic solvent extraction, ion exchange, and precipitation methods. Unconventional techniques, those still at the developmental/exploration stage, including those related to the use of supercritical fluids (mainly CO2), molten metals/molten salts, and more exotic (and less extensively tested) techniques like those based on the use of room temperature ionic liquids (RTILs) or volatility will then be addressed. The issue of scale will be considered with coverage of analytical separations followed by a detailed description of the current state of the art in hydrometallurgical (industrial‐scale) separations for actinide recovery, recycle, and transmutation. The chapter concludes with some consideration of future directions.

24.2 HISTORICAL DEVELOPMENT OF ACTINIDE SEPARATIONS

Actinide separations had its beginnings with the discovery of radioactivity. Crookes and Becquerel found that the addition of carbonate to a solution containing uranium caused the formation of a precipitate that contained the beta, gamma radioactivity while the uranium remained in the solution phase. Rutherford and Soddy made a similar observation for thorium. Marie and Pierre Curie began a program to separate the components of pitchblende. In 1898, they announced the discovery of the new element polonium, ‘‘While carrying out these operations (separations by precipitation), more active products are obtained. Finally, we obtained a substance whose activity was 400 times larger than that of uranium. We therefore believe that the substance whose activity we have isolated from pitchblende is a hitherto unknown metal. If the existence of this metal can be affirmed, we suggest the name polonium’’ (Choppin et al., 2002). The separation method used by these pioneers was precipitation/coprecipitation, which remained the predominant

2628

Actinide separation science and technology

separation technique through the Manhattan Project of World War II. A historical perspective on the development of this science and technology through the end of World War II is available in The Making of the Atomic Bomb (Rhodes, 1986). Between 1934 and 1939, about 50 research papers claimed the discovery and reported studies of transuranium elements with Z ¼ 93, 94, 95, 96. In 1939, Hahn and Strassmann conducted very careful separations on neutron‐ irradiated uranium samples and proved that these ‘transuranium elements’ were, in fact, products of nuclear fission with atomic numbers below 60. This led to new experiments in 1940 in which neptunium (Z ¼ 93) and plutonium (Z ¼ 94) were synthesized and separated. These new elements were isolated using an oxidation–reduction cycle (with BrO 3 as the oxidizing agent) followed by precipitation of the reduced metal ions with crystalline LaF3, establishing a link with the 4f elements. Within the context of world politics in the 1930s and 1940s (and as it turned out the following decades), it was perhaps inevitable that the discovery of fission would be first valued for its potential military applications. Two approaches to the assembly of a critical mass were immediately recognized: isotope enrichment to increase the atom percentage of the fissile uranium isotope 235U and transmutation of 238U by neutron capture and b decay to produce 239Pu. The former option required a many theoretical plate isotope separation process wherein the stage‐wise efficiency is limited by the small difference in mass of the two principal isotopes. Plutonium production instead relies on neutron capture in a reactor fueled by uranium (the ratio of 239Pu production to fission of 238U after capture of a thermalized neutron is about 14 to 1 (Choppin and Rydberg, 1980) and chemical separation of different elements. Differences in the redox chemistries of uranium and plutonium facilitate their mutual separation. Neither isotope enrichment nor plutonium production were considered to have an advantage in the race to produce a critical mass for the first nuclear weapon in time to affect the outcome of the war, so both methods were pursued with equal vigor in the Manhattan Project. Two approaches to uranium isotope enrichment were proposed for full investigation and process development: electromagnetic isotope separation, proposed by E. O. Lawrence at Berkeley, and gaseous diffusion, championed by John Dunning at Columbia University (Rhodes, 1986). The latter was considered the more likely to succeed on an industrial scale because it was based on technology that was better established. It also offered the advantage of continuous operation, which was not deemed possible in the electromagnetic separation option. Electromagnetic isotope separation received equal consideration because of the greater per‐stage separation potential of the technique. Each method relied on the low‐temperature volatility of UF6 (Cotton and Wilkinson, 1988). As research continued on both approaches, groundbreaking occurred on the Clinch River in eastern Tennessee in 1942, leading to the establishment of the Clinton Engineering Works in Oak Ridge. The Gaseous Diffusion Plant (K‐25)

Historical development of actinide separations

2629

required the co‐siting of a dedicated coal‐fired power plant and occupied about 0.2 sq. km under a four‐stories‐high roof. The electromagnetic isotope separations plant (Y‐12) occupied half that space and required 13 tons of silver (borrowed from the U.S. Treasury) for the electromagnets. In the end, K‐25 provided feedstock of up to 50% enriched 235U to the Y‐12 plant for completion of the high enrichment needed for weapons production. These two plants working in tandem produced the 235U for the Hiroshima weapon (Rhodes, 1986). Industrial scale plutonium production was first accomplished at the Hanford site on the Columbia River near Richland, Washington (Anonymous, 1996). It began with commissioning of B reactor in September 1944 and continued through the lifetimes of eight single‐pass reactors, N reactor (the only dual‐ use Hanford reactor that produced both usable steam and Pu), and the fast flux test facility (FFTF) ending in the early 1980s. The isolation of plutonium from uranium and fission products was initially accomplished by precipitation with BiPO4. The process, pioneered by S. G. Thompson (Thompson and Seaborg, 1956, 1957; Seaborg and Thompson, 1960), involves coprecipitation of Pu(IV) by BiPO4 followed by oxidation to Pu(VI), which does not carry on BiPO4. The process was repeated several times and followed by a LaF3 precipitation to increase the purity of the product. This batch process is inherently inefficient and has the additional disadvantage of losing uranium to the waste stream. At the time, the loss of uranium to the waste stream was particularly damaging to process efficiency because of the limited amount of purified uranium that was available. However, precipitation/coprecipitation was the only viable technology that could be readily scaled up to production plant dimensions within the demanding time constraints of the Manhattan Project. In fact, the BiPO4 coprecipitation process was first demonstrated using microgram quantities of plutonium, hence the scale‐up was by a factor of 109. Because of the consistency and reproducibility of the chemistry involved, this scale‐up occurred without significant complications. After the war, additional separations of BiPO4 wastes were conducted to recover the rejected uranium for recycle to reactors. BiPO4 was eventually replaced at Hanford by solvent extraction processes based on the use of methyl(isobutyl)ketone (hexone, Structure b) for extraction of uranium and plutonium from slightly acidic Al(NO3)3 solutions (REDOX process) and later using TBP to selectively extract (and mutually separate) uranium and plutonium from nitric acid solutions (PUREX process). Great improvements in efficiency were achieved with each successive development, though the PUREX process produced a far smaller volume of secondary wastes than the REDOX process. Fifty years later, PUREX remains the principal method for processing of spent nuclear fuel.

2630

Actinide separation science and technology

In the spirit of scientific discovery and at several laboratories around the world, though primarily at Berkeley and under the supervision of Glenn Seaborg, research in the 1950s and 1960s continued to extend the actinide series from plutonium and americium towards the final element of the series (Z ¼ 103). The identification of new elements demands satisfaction of ‘‘...The basic criterion for the discovery of a new element is the experimentally verified proof that the atomic number of the new element is different from the atomic numbers of all previous elements. Establishment of the atomic number can be by chemical means, by identification of the characteristic X‐rays in the decay of the new species, or by establishment of genetic decay relationships through a‐particle decay chains in which the new element is identified by the observation of previously known decay products’’ (Seaborg and Loveland, 1990). To respond to the demand for predictable chemistry, it was essential that the separations process behave in a systematic fashion. As the postwar research on actinide syntheses progressed, it was quickly learned that the rich redox chemistry of the light actinides, which was central to most of the successful separations of the light members of the series, did not persist beyond americium. In aqueous solutions, the elements beyond americium behaved chemically more like the 4f analog lanthanides than the light members of the series, strongly preferring to remain in the trivalent oxidation state. Because synthesis of successive members of the series (beyond Cm) required the isolation and irradiation of a previous member of the series, the task of identifying the later members of the series was hindered not only by the ability to analyze for new species produced, but also by the rate at which target elements could be produced (and how quickly they decayed). The difficulty is demonstrated in Table 24.1 in which the nuclear reaction, target element, and product are noted. The process was further complicated by the increasingly short half‐lives of the elements produced, and the low efficiency of the reactions leading to their production. For the elements beyond einsteinium, only a few atoms at a time were created and detected. The procedures of one‐atom‐at‐a‐time chemistry have been described in some detail by Seaborg and Loveland (1990) and can be found in Chapters 13 and 14 of this work. The particle capture reactions that yielded new elements were also always accompanied by some fission. Yields for lanthanides in heavy element fission are high thus the dissolution of irradiated targets led to the creation of solutions that contained not only small amounts of the target transamericium elements but also significant concentrations of lanthanides. This complication impacted both the identification of new elements and the creation of appropriate target materials. Two challenging separation problems resulted from this circumstance: the need for mutual separation of the two groups (5f from 4f ), and of adjacent metal ions (in the 5f series) of identical charge and similar cationic radii. Because

Fundamental features of actinide separation systems

2631

Table 24.1 Summary of original actinide synthesis methods, means, and materials. Actinide

Target

Half‐lifea (Target)

Half‐lifea (Product)

239

Np Pu 241 Am 242 Cm 243 Bk 245 Cf 253 Es

238

238

238

U U 239 Pu 239 Pu 241 Am 242 Cm 238 U

4.47  109 yr 4.47  109 yr 24 100 yr 24 100 yr 432.7 yr 162.9 d 4.47  109 yr

2.35 d 87.74 yr 432.7 yr 162.7 d 4.5 h 43.6 min 20.47 d

255

Fm

238

4.47  109 yr

20.47 h

n

256

Md No 258 Lr

253 244

20.47 d 18.11 yr 351, 13.08 898, 2.645 yr

1.27 h 55 s 3.9 s –

4

254

a b

U

Es Cm 249–252 Cf –

Projectile

Method

n H n 4 He 4 He 4 He n

cyclotron cyclotron reactor cyclotron cyclotron cyclotron fusion explosion fusion explosion cyclotron HILACb HILACb –

2

He C

12

10,11

–

B

Appendix II. Heavy ion linear accelerator.

of the minute amounts of materials being used as targets and produced in irradiations, and the absence of multiple oxidation states, many standard separation procedures (e.g. precipitation/coprecipitation) were simply not useful. The emergence of polymeric ion exchange materials proved essential to accomplishing both of these separations. Though cation exchange resins bearing readily deprotonated sulfonic acid groups adsorbed the trivalent f‐elements strongly, even from moderately acidic solutions, these sorbents exhibited little inherent facility for accomplishing either separation, i.e. there was insufficient differentiation between cations of similar size. Lanthanides and trivalent actinides were absorbed by the resin under the same conditions and with most inorganic eluants exited the column together. The secret to attaining selectivity was proper choice of the eluting solution. Two distinctly different classes of eluting agents were applied to these separation problems, soft‐donor ligands, and hydroxycarboxylate complexants. Their use enabled the positive identification of the remaining members of the series thus confirming the basic correctness of the actinide hypothesis. Each of these separations methods is discussed in greater detail in Section 24.3.3.

24.3

FUNDAMENTAL FEATURES OF ACTINIDE SEPARATION SYSTEMS

To isolate an actinide ion from a complex mixture, some procedure must be devised to transport the target metal ion from its starting condition into a separate phase and then recover the target metal ion from that separate phase. For analytical‐scale separations, a highly efficient process that can be

2632

Actinide separation science and technology

accomplished in a single (or small number of) contact(s) between the phases is most desirable. For large‐scale separations, complex series of processes are typically combined to accomplish the separation. As a result, less efficient single‐stage chemical processes are acceptable (and in fact often preferred) for hydrometallurgical applications. Selectivity becomes a more important feature than extractant strength. The key features needed for large‐scale separations of nuclear materials are: (1) reversibility of phase transfer (mass transport) reactions with a shift in extraction conditions, (2) sufficient reliability to be readily adaptable to remote (i.e. no human contact) operations, (3) rapid chemical reaction and phase‐transfer kinetics, and (4) the ability to operate in a continuous rather than batch fashion. The first three features are absolutely essential; the fourth is highly desirable. Materials must also demonstrate physical and chemical stability in contact with strongly acidic aqueous solutions and in a high radiation environment. General features of selected separation techniques will be discussed in the following sections. 24.3.1

Volatility‐based separations methods

Choppin (2002) has provided an overview of the subject of separation processes based on the volatility of actinides and selected fission products. He suggests possible approaches to selective removal of Zr, Tc, and Ru fission products (or cladding material) through their volatile oxides (Tc, Ru) or chlorides (Zr). There are also reports on the potential use of volatile b‐diketone complexes of trivalent lanthanides for gas phase based separations. For example, tetra‐ and hexavalent actinide cations are known to form volatile compounds with FOD (6,6,7,7,8,8,8‐heptafluoro‐2,2‐dimethyl‐3,5‐octanedione, Structure c), which could form the basis for a separation of uranium and plutonium from americium (Anonymous, 1995). This same reagent will appear again in the discussion of actinide separations methods based on supercritical CO2 (Section 24.3.10). No separation system based on the volatility of either fission product oxides or b‐diketonate complexes has received extensive development at the process scale.

The most extensively researched system for volatility separations is based on the same volatile fluorides that are the basis of isotope separations. A separation based on the volatility of uranium and plutonium fluorides was demonstrated by Hyman et al. (1956) and investigated in greater detail at Oak Ridge National Laboratory for reprocessing as a part of the molten salt reactor project (Rosenthal et al., 1972). The overall effectiveness of the process is limited

Fundamental features of actinide separation systems

2633

principally by the simultaneous production of volatile fluorides of fission products Tc, Te, and I. The volatile fluorides can be separated by distillation, though the lower volatility of PuF4 (arising from the decomposition of PuF6) leads to Pu deposition problems. In principle, this approach should produce minimal volumes of wastes, though operations combining fluorine compounds and radioactive materials always present challenging materials handling and safety issues. The application of fluorinated compounds to volatility separations is mimicked in many separations that rely on supercritical CO2, as will be discussed in Section 24.3.10. 24.3.2

Precipitation/coprecipitation methods

In the laboratory, precipitation and coprecipitation processes are a regular and accepted feature of radioanalytical chemistry. Several applications of precipitation and coprecipitation techniques for conducting investigations of the redox speciation of actinides at radiotracer concentrations are discussed in Section 24.4.1a. For the cleanup of aqueous media containing low concentrations of actinides, ultrafiltration has also been employed to collect ultrafine actinide‐ containing solids (Cecille et al., 1987; Senentz and Liberge, 1998; Smith et al., 1998, 1999; Bisset et al., 2003). Though a number of precipitation processes have been advanced over the years to assist in selected actinide separation scenarios (Bertozzi et al., 1976; Mousty et al., 1977; Pietrelli et al., 1987; Spurny and Heckmann, 1987; Grossi et al., 1992a,b; Sinha et al., 1992; Strnad and Heckmann, 1992; Felker et al., 1995; Tomiyasu and Asano, 1995; Harada et al., 2001), precipitation is no longer practiced as the primary means of separations for large‐scale actinide production purposes. Because the actinides are acidic cations, they readily undergo hydrolysis and precipitate as hydroxides. If complexing agents are kept from the solution, actinide hydroxides can be readily precipitated in the trivalent (Ksp  10–20), tetravalent (Ksp  10–54), pentavalent (Ksp  10–10), and hexavalent (Ksp  10–25) oxidation states (Martell and Smith, 1998). Hydroxides are generally avoided at the production scale and are unreliable for radioanalytical purposes, but often prove quite convenient avenues to the purification of actinide ions at the milligram to gram level for research purposes. Their most notable feature is the ready reversibility of the precipitation through the addition of mineral acid solutions, thus hydroxide precipitation can be used to readily convert from (for example) chloride to nitrate salts. The cautionary note here is to avoid the formation of tetravalent plutonium hydroxide, which has an extremely low Ksp and is redissolved only with difficulty, and often not cleanly, particularly if the precipitate is aged. The presence of carbonate or strong complexing agents (e.g. aminopolycarboxylates) can seriously interfere with hydroxide precipitation processes. Other species that are readily precipitated are the phosphates of actinide ions in any oxidation state and under a wide range of conditions, and the fluorides

2634

Actinide separation science and technology

and the oxalates of trivalent and tetravalent actinide ions. The latter two reagents can be employed for oxidation state‐based separations, as the pentavalent or hexavalent actinide cations do not form insoluble species under most conditions with these anions while both the trivalent and tetravalent ions precipitate readily from acidic solutions. In the remanufacture of plutonium from nuclear weapons pits (fission core of a thermonuclear device), the selective precipitation of tetravalent plutonium as the peroxide was an essential feature of operations at the Rocky Flats Plant (Cleveland, 1970). The most technologically important coprecipitation process (no longer used in practice) is that based on bismuth phosphate, as noted above in Section 24.2 and again later in more detail in the discussion of process chemistry. For actinide oxidation state speciation in radioanalytical applications, the actinides themselves are present at concentrations too low to challenge solubility limits in a reliable fashion. The introduction of cations and anions that combine to form insoluble species that carry the actinides down are useful analytical or laboratory‐scale purification procedures. This is the case of lanthanum fluoride (LaF3) whose solubility product is reported as about 10–18.7 (Martell and Smith, 1998). This compound is readily precipitated from comparatively dilute acidic fluoride solutions. LaF3 (actually, most any lanthanide will serve) quantitatively carries trivalent and tetravalent actinide ions. Care must be exercised for quantitative LaF3 carrier precipitation to avoid excess HF, as the resultant formation of soluble metal fluoride complexes can interfere with the efficiency of precipitation. Partly as a result of the unique coordination geometry of the dioxo actinide (V) and (VI) cations, there are no reliable coprecipitation procedures for their analysis or macroscale separation, though there are a number of insoluble adsorbents that will remove these ions from solutions (though with limited selectivity). These adsorption reactions will be discussed in Section 24.4.1.

24.3.3

Ion exchange methods

The development of solid materials capable of capturing and reversibly releasing the metal ions back into the contacting solution, ion exchange materials, was a great step forward in separating elements with similar properties. The earliest non‐crystallization separation processes for individual trivalent lanthanide ions based on inorganic ion exchangers demonstrated separation factors for adjacent ions of 1.01–1.05, barely acceptable for chromatographic separations using large columns. For the production of actinides in microscopic amounts, such separation factors are simply too low to be useful. The selectivity limitations of inorganic ion exchange materials were only slightly improved with the development of polymeric organic ion exchange materials, though the latter offered superior reproducibility and resistance to dissolution. Radiation stability is an issue for either class of sorbents, but more problematic for the polymeric

Fundamental features of actinide separation systems

2635

materials. Clearly, more efficient procedures were required to cope with submicroscopic amounts of the new transplutonium elements being produced. The separation of trivalent actinides from lanthanides was first achieved by cation exchange from concentrated chloride media. Street and Seaborg (1950), Diamond et al. (1954), and later Choppin and Chetham‐Strode (1960) demonstrated that the behavior of lanthanides and actinides on cation exchange columns was identical below 6 M HCl, but diverged between 6 and 12 M (as shown in Fig. 24.1). Separation factors of about 10 were achieved at 12 M HCl. Separation efficiency was increased when the separation was carried out from salt solutions (dilute acid) or from alcohol–water mixtures of HCl. Diamond and coworkers proposed that the separation of promethium and americium at high concentrations of HCl was a manifestation of f‐orbital covalency to the bonding of Am3þ to Cl (which is not present in the Pm system). The origin of the effect is still a matter of discussion and debate, but it has become abundantly clear over the intervening decades that the most effective trivalent actinide and lanthanide separations are based on the contribution of ligand donor atoms softer (i.e. more polarizable) than oxygen. Separation efficiency was slightly greater when anion exchange was employed. Thompson et al. (1954) found actinide/lanthanide separation factors above 10 for anion exchange separation from 10 M LiCl aqueous solutions.

Fig. 24.1 Distribution of Pm(III) and Am(III) onto Dowex 50 cation exchange resin as a function of hydrochloric acid concentration (Diamond et al., 1954).

2636

Actinide separation science and technology

In this case, higher order (anionic) actinide chloride complexes are formed which preferentially associate with the resin. Introduction of 20% ethanol improved the separation factor, presumably through a modification of the hydration characteristics of the metal ions or their complexes. In this system, the actinides were eluted within a few column volumes while the lanthanides required much larger volumes. In another procedure using a Dowex 1 anion exchange resin column and eluting with 9.9 M LiCl (0.11 M HCl), Hulet et al. (1961) achieved an excellent separation of Ln–An. Surls and Choppin (1957) reported that similar results could be achieved in thiocyanate solution at significantly lower concentrations than is required for chloride (Fig. 24.2). This is a result of the increased interaction strength of the actinide with the ‘less‐soft’ nitrogen donor atom of SCN relative to the very soft Cl anion. The LiCl anion exchange process is still used for actinide/lanthanide separation at Oak Ridge National Laboratory for actinide production (King et al., 1981). The results of Guseva and Tikhomirova (1972) indicate a significant improvement in the group separation from 4% cross‐linked Dowex 50 using 10.5 M HCl

Fig. 24.2 Partitioning of trivalent actinides and lanthanides onto Dowex 1 anion exchange resin from 10 M lithium chloride (Hulet et al., 1961) and 2 M ammonium thiocyanate (Surls and Choppin, 1957) solutions ( , m, actinides, d, j, lanthanides).

▾

Fundamental features of actinide separation systems

2637

in 40% ethanol as the eluant as compared with 12.5 M HCl in water. Guseva et al. (1987a,b) subsequently demonstrated an efficient separation of trivalent actinides from all matrix elements (lanthanides and other fission products) with both cation and anion exchange from aqueous–ethanol solutions of sulfuric acid. Usuda and coworkers (Usuda, 1987, 1988; Usuda et al., 1987) have proposed a separation scheme for trivalent actinides using a three‐step ion exchange partition from light actinides and fission products. Though little fundamental solution chemistry research has been done to probe the impact of alcohol–water mixtures on actinide separations, the effects cited above clearly indicate an important role for the interactions between solvent and solute molecules in these systems. The separation of adjacent trivalent actinides represented an even more challenging task. The inherent selectivity of Dowex 50 cation exchange resin for adjacent lanthanide cations (in this case, behaving analogously with the trivalent actinides under all conditions) is demonstrated in Fig. 24.3. Separation factors for adjacent lanthanide cations average about 1.007. The coupling of water‐soluble chelating agents (also demonstrated in Fig. 24.3) with the ion

Fig. 24.3 Partitioning of trivalent lanthanide ions onto Dowex 50 cation exchange resin from various aqueous acid solutions. (Gd number is the distribution ratio of the element normalized relative to DGd ¼ 1.0, created from data in Marcus, 1983.)

Actinide separation science and technology

2638

exchange systems by Thompson and coworkers (Thompson et al., 1950, 1954; Choppin et al., 1956) was the enabling science that made the identification of the new transplutonium elements possible. The combination of a buffered solution of, in particular, a hydroxycarboxylic acid with a strong acid cation exchange resin like Dowex 50 made it possible to take advantage of the relative stability of the aqueous complexes of the actinide ions (which generally increase in proportion to those of the analogous lanthanide complexes across the series). This effect can be readily understood given a little consideration of the monophasic and biphasic equilibria involved in the process. Assuming that the water‐soluble metal complexes present in the eluant are not sorbed by the resin, the distribution of the metal ion onto the acidic resin phase is governed by the following equilibrium (taking a trivalent cation as the example): M3þ þ 3HðResinÞ ! MðResinÞ þ 3Hþ

ð24:1Þ

In the aqueous phase the metal complexation equilibria with a ligand HY can be written as: þ M3þ þ nHY ! MYð3nÞ þ nHþ ð24:2Þ n The distribution ratio (D) for the metal ion is the ratio of the amount of metal species in the resin phase, [M]R to that in the aqueous phase [M]a. Most commonly, these values are normalized to 1 ml of solution and 1 g of resin, respectively. þ

D ¼ ½M R =½M a ¼ ½MðResinÞ =ð½M3þ þ Sn1 ðMYð3nÞ ÞÞ n

ð24:3Þ

The distribution ratio is directly proportional to the resin’s affinity for the metal ion and inversely proportional to the degree of complex formation in the aqueous phase. In general, the separation factor (S), the ratio of distribution ratios, determines whether a separation of two species is successful or not. Written in terms of the respective one‐ and two‐phase complexation equilibria, the separation factor is:

0

M;M wherein Kex represents the equilibrium coefficient for the partitioning of the 0 cation onto the resin phase, and bM;M represents the complexation equilibrium i constants for species present in the eluant solution. In fact, multiple complexants can be used in the aqueous phase to enhance separations, in which case additional complexation equilibria can be used to predict separation performance. First attempts relied on citric acid (Structure d) as the eluant. As the synthesis of new actinides proceeded across the series, the product nuclides had progressively shorter half‐lives, and in passing the middle of the series, the actinide equivalent of a gadolinium break (differentiation of the stability constants of

Fundamental features of actinide separation systems

2639

adjacent actinide complexes, predominant at the beginning and end of the lanthanide series, disappeared in the middle of the series) reduced the effectiveness of citrate as an eluant. These combined features resulted in smaller separation factors between the newest nuclides and in their early exit from the column, hampering analysis and detection. Substitution of lactic acid for citric acid improved performance. The comparative elution positions of Am, Cm, Bk, Cf, Es, and Fm from Dowex 50 cation exchange resin when the eluting solution was 0.25 M ammonium citrate or 0.4 M ammonium lactate are shown in Table 24.2.

Ultimately, the demands of the chemistry and the radiochemistry required a ‘better’ eluant (i.e. one yielding more consistent (i.e. linear) trends of elution with decreasing radii while retaining rapid kinetics). To satisfy this demand, Choppin and Silva (1956) introduced a‐hydroxyisobutyric acid (Structure e), a‐HIBA, which also came to be known colloquially as the ‘BUTT’ eluant. This complexant differs from lactate in the substitution of a second methyl group for H at the alpha position. The a‐hydroxyisobutyric acid provides average separation factors for adjacent lanthanides or trivalent actinides of about 1.3–1.5 and very consistent elution positions even through the middle of the series where many reagents fail to give acceptable results. Parallel performance between trivalent lanthanides and actinides in cation exchange separations was a key factor in the identification of most of the transplutonium actinides. Fig. 24.4 shows the elution profile of trivalent actinides and lanthanides with ammonium a‐hydroxyisobutyrate and shows the consistency in separation factors for adjacent cations across the series. It should be noted that if the data were plotted in terms of cationic radii rather than atomic number, the lanthanide and actinide M0 results would overlap. Table 24.3 compares SM of adjacent actinides with lactic acid, a‐hydroxyisobutyrate, ethylenediamine‐N,N,N0 ,N0 ‐tetraacetic acid (EDTA) and further relates those data to the separation factors observed for Table 24.2 Elution of transplutonium elements from Dowex 50 cation exchange resin using ammonium carboxylate salts at 87 C, pH 3.0–4.5, 2 min/drop, 2 mm by 10–20 mm column (Thompson et al., 1950, 1954). Retention time (drop number) Carboxylic acid

Am

Cm

Bk

Cf

Es

Fm

0.25 M ammonium citrate 0.4 M ammonium lactate

94.0 58.5

80.8 49.0

56.0 33.0

38.3 22.0

32.5 18.0

26.7 13.6

2640

Actinide separation science and technology

Fig. 24.4 Elution profiles for trivalent lanthanide and actinide ions and separation factors (relative to Cm ¼ 1.0) for a‐hydroxyisobutyrate elution from Dowex 50 cation exchange resin (Choppin and Silva, 1956).

solvent extraction separations using bis(2‐ethylhexyl)phosphoric acid (HDEHP, Structure f), which will be considered further in Section 24.3.4a

Improvements in separations have been achieved with cation exchange systems of this type using very finely divided resin beds and high‐pressure elutions (Campbell, 1970). Kilogram amounts of americium and gram amounts of curium have been purified from each other by using nitrilotriacetic acid (NTA) and diethylenetriamine‐N,N,N0 ,N00 ,N00 ‐pentaacetic acid (DTPA, Structure g) as

Fundamental features of actinide separation systems

2641

Table 24.3 Separation factors for adjacent trivalent actinides with solvent extraction and cation exchange column using different reagents. Reagents Cation exchanger

Element

Solvent extration. HDEHP/HNO3

EDTA

Lactic acid

a‐HIBA

Am/Cm Am/Bk Bk/Cf Cf/Es Es/Fm Fm/Md

1.24 8.3 2.7 1.02 2.2 4.4

2.0 3.1 2.0 – – –

1.21 1.54 1.55 1.25 1.45 –

1.4 1.7 2.2 1.5 1.7 1.4

a‐HIBA ¼ a‐hydroxyisobutyric acid.

the eluants (Baybarz, 1970). The kinetics of the metal complexation/ion exchange equilibration on the Dowex 50 column with a‐hydroxyisobutyrate eluant was also found to be superior to that for the several other ligands that had been previously employed. For example, aminopolycarboxylic acid ligands like EDTA demonstrated comparable or even superior separation factors (to a‐hydroxyisobutyrate; see Fig. 24.3), but slower equilibration rates, which required longer residence times for the solutions on the column. The need for longer equilibration times on the column was a definite handicap in the search for short‐lived actinide species. Like TBP and PUREX, the BUTT column remains today one of the most effective ion exchange separation method for trivalent f‐elements from a mixture of like elements (Nash and Jensen, 2000). It should be noted that the intrinsic affinity of cation exchange resins increases for actinides in the order An(V) < An(III) < An(VI) < An(IV), in accord with the comparative electrostatic attraction of the cations for the anionic sulfonate functional groups of the resin. The differences are sufficiently large to allow the mutual separation of the ions in different oxidation states; however, all but the pentavalent oxidation state are bound too strongly for effective separation procedures to be routinely used. Where necessary and possible, sorption of strongly bound ions is generally reversed using oxidation state adjustment or chelating agents.

2642

Actinide separation science and technology

To avoid the elution difficulties of the cation exchange resins, ion exchange separations for the purification of the tetravalent and hexavalent actinides more frequently rely on anion exchange techniques. A variety of separation methods based on the use of tetraalkylammonium or methyl pyridinium polymeric resins have been developed. Introduction of the Reillex resins, based on methylpyridinium functional groups, is among the more significant recent advances in anion exchange separations for actinides (Abney et al., 1995). Perhaps the most important application of anion exchange resins is in the purification of plutonium. Pu(IV) is selectively sorbed onto Dowex 1 from 8 M HNO3, allowing the passage of other contaminants through the resin. Pu(IV), which is retained on the resin as the hexanitrato complex (PuðNO3 Þ2 6 ), is readily eluted using more dilute nitric acid. Anion exchange separations for An(IV) and An(VI) are facile because these cations readily form anionic complexes with simple inorganic – anions like NO 3 and Cl . However, higher order complexes are formed in the presence of the resin than are observed in the same solution in its absence. This is due to the superposition of the phase transfer equilibrium upon the typical aqueous phase complexation reactions, which tends to drive the process. In essence, anionic complexes are sorbed to the resin whether or not they are present in the aqueous solution phase contacting the resin. A new chelating ion exchange resin (Diphonix) that exhibits high affinity for actinide cations in all oxidation states from strongly acidic solutions has been developed jointly at Argonne National Laboratory and the University of Tennessee as a spinoff of the development of the transuranium extraction (TRUEX) solvent extraction process (Alexandratos et al., 1993; Chiarizia et al., 1993, 1994, 1996, 1997; Horwitz et al., 1993, 1994; Chiarizia and Horwitz, 1994, 2000; Trochimczuk et al., 1994). Diphonix resin combines a methylenediphosphonic acid chelating group with carboxylic and benzene sulfonic acid groups in a styrene–divinylbenzene matrix. This combination results in a chelating resin that exhibits good metal ion uptake kinetics (Chiarizia et al., 1994) and effectively sorbs actinide metal ions in all oxidation states from moderate to strong acid solutions and even in the presence of moderately strong complexants. The hexavalent and tetravalent species are so strongly retained by the resin even from 10 M HNO3 that they can only be removed upon elution with a moderately concentrated solution of a structurally related diphosphonate chelating agent (1‐hydroxyethane‐1,1‐diphosphonic acid, HEDPA; Structure h) or by applying a reducing agent. The distribution ratios for Am(III), U(VI), Pu(IV), Np(IV), and Th(IV) onto Diphonix as a function of [HNO3] are shown in Fig. 24.5. The acid dependence for Am(III) uptake indicates normal cation exchange behavior while that for Th(IV) and U(VI) has been interpreted in terms of coordination of these cations by the phosphoryl oxygens of the fully protonated methylenediphosphonate groups. The principal feature of the Diphonix resin is the strength of cation uptake rather than selectivity, though the resin demonstrates significant selectivity for Pu(IV) and U(VI) over Am(III) from concentrated nitric acid media. The principal advantage of this resin may

Fundamental features of actinide separation systems

2643

be in the separation of actinides from less‐strongly‐bound fission product and cations present as a result of matrix dissolution.

Fig. 24.5 Distribution of selected actinide ions onto Diphonix resin from nitric acid solutions (Chiarizia et al., 1997).

2644

Actinide separation science and technology 24.3.4

Solvent extraction methods

Successful solvent extraction processes depend on the selective transport of the target metal ion (or group of metal ions) from an aqueous solution containing contaminants into an immiscible organic solution. When the target metal ion is removed from that organic phase, it will have undergone some degree of purification, often characterized in terms of a ‘decontamination factor’ (Df). Additional purification processes may subsequently be engaged, depending on the Df required for the product. Strongly acidic, extensively hydrated metal ions like actinides and most of their complexes with typical mineral acid anions or other hydrophilic complexants have minimal intrinsic tendency to partition spontaneously from aqueous into non‐polar organic solutions. The driving force for phase transfer is provided by the introduction of a lipophilic complexant (extractant) into the organic phase. Usually, new complexes possessing a hydrophobic external ‘shell’ are formed at the oil–water interface and transferred to the non‐polar (or less polar) organic phase. Chemical reactions occurring in the aqueous phase, including oxidation–reduction, hydrolysis, and the formation of water‐soluble complexes, all affect the phase transfer equilibrium position as well. Of all separation techniques that have been applied for actinide separations, solvent extraction offers the greatest number of options and adjustable parameters to finetune performance. Further, it is perhaps the separations technique best adapted to the continuous operations, high throughput, and remote handling that are essential to the processing of nuclear fuels. Of course, this flexibility can also introduce complications, including rather long development time for the creation of a new solvent extraction‐based process. Historically, industrial scale aqueous processes have also produced waste streams noteworthy for both their complexity and volume. It is important at this stage to make the clear distinction between the chemistry of actinides in the organic media relevant to solvent extraction and the chemistry generally termed as organoactinide chemistry, which is covered in Chapters 25 and 26. In solvent extraction, metal ions in organic solutions never engage in bonding to carbon atoms, as they do in most true organometallic complexes. Direct bonding interactions between actinide ions and lipophilic complexants do play an important role in most solvent extraction systems, except for those based on molecules that organize in organic solutions to form reverse micelles. For the actinides in extraction processes, bonding is always to oxygen, nitrogen, or occasionally sulfur donor atoms in organic compounds or to chloride or thiocyanate anions, sometimes in combinations. In solvent extraction, some dissolved water molecules are always present in the organic phase. For actinide separations, these solutions will often also bear mineral acid molecules that have been extracted by the same lipophilic reagents that remove the actinides from the aqueous phase. In some systems, a specific interaction can occur between the metal cation and solvent molecules, but only

Fundamental features of actinide separation systems

2645

with compounds like methyl(isobutyl)ketone (MIBK) or (neat) tri(n‐butyl) phosphate (TBP) which are moderately strong Lewis bases and so capable of competing with adventitious water molecules in the organic phase of solvent extraction systems. It would be impossible to catalog all of the various reagents whose actinide extraction properties have been investigated in the space allocated for this overview. In the following discussion, the general characteristics of the classes of selected extraction systems are considered. The objective here is to illustrate the general features of the techniques. There are at least five different classes of solvent extraction systems that have been employed for actinide separations. The classes and representative biphasic extraction equilibria are: Liquid cation exchangers/chelating agents, ! MLn;org þ 3Hþ M3þ aq þ nHLorg aq

ð24:5Þ

Micellar extractants, ! MHn3 Ln;org þ 3Hþ M3þ aq aq þ ðHLÞn;org

ð24:6Þ

Solvating extractants,  ! MX3 Sn;org M3þ aq þ 3Xaq þ nSorg

ð24:7Þ

Ion pair forming extractants (or liquid anion exchangers), þ  !  MX4 Aorg M3þ aq þ 3Xaq þ A Xorg

ð24:8Þ

Synergistic extractants, ! ML3 Sn;org þ 3Hþ M3þ aq aq þ 3HLorg þ nSorg

ð24:9Þ

Species present in the aqueous and organic solutions are designated by the subscripts aq and org, respectively. In solvent extraction systems, the metal ion distribution ratio is a dimensionless quantity defined as D¼ [M]org/[M]aq. D is not a species‐specific term but rather defines the analytical concentrations of the metal ion in the aqueous and organic phases. The stoichiometric features of the equilibria outlined above are most relevant at low concentrations of the metal ions. Under conditions near the stoichiometric limits of concentrations, the phase transfer equilibria can be substantially more complex than these simple equilibria indicate. Each class of extraction system accomplishes the phase transfer by a slightly different chemical process. However, these systems share the following general characteristic: while the high dielectric constant of water readily supports the presence of charged ionic species as discrete molecules, the low polarity of organic solutions demands close contact between cations and anions. Most solutes in most organic solvents are expected to be discrete electroneutral entities. The liquid cation exchangers, chelating agents, and micellar extractants each exchange a number of monovalent cations (usually Hþ) equivalent to the

2646

Actinide separation science and technology

formal charge on the cation extracted to maintain electroneutrality in both phases. In these systems, transfer of the metal ion into the organic phase is favored by low acidity, implying that the metal ion can be stripped from the loaded organic solution into concentrated acid solutions (as Hþ competes with the metal ion for the extractant). Some acidic extractants have a tendency to self organize (aggregate), even in the absence of the extracted metal ion, to form dimers or higher order aggregates. Sulfonic acid extractants in particular behave in this manner, forming reverse micelles in the organic phase. Solvating extractant systems are technologically the most important for actinide purification. They accomplish phase transfer by solvating electroneutral metal complexes with mineral acid anions, hence the net phase transfer reaction includes the necessity to dehydrate and resolvate in the organic phase both the metal ion and a sufficient number of conjugate base anions of mineral acids to neutralize the cation charge. In solvating extraction systems, the phase transfer reaction is favored by high concentrations of the counter‐ion (preferably introduced as an acid solution to minimize the generation of secondary wastes) and stripped from the loaded organic solution by contact with dilute acid solutions, a change in oxidation state, or washing with a water‐soluble complexant. Primary among the solvating extractant systems that are technologically the most important actinide separations systems in operation today are those based on the solvating ability of TBP. More than 50 years of cumulative industrial scale experience exists on the PUREX process. This solvent extraction process accomplishes the selective removal of both plutonium [as Pu(IV)] and uranium [as U(VI)] from dissolved spent fuel solutions (3–6 M HNO3) as their electroneutral nitrate salts with minimal complication (Fig. 24.6). Most fission products and the trivalent and pentavalent actinides [Am(III), Cm(III), Np(V)] are rejected by TBP. Plutonium is selectively recovered from the extractant phase through its reduction to the trivalent oxidation state in which its extraction performance is comparable to that of Am(III). In PUREX processing, changes in neptunium oxidation state speciation causes partitioning of this element to undesirable locations within the process flow scheme. Until recent years, it has been most advantageous to try to maintain Np(V) in the aqueous phase so that it remains with the fission product raffinate. The emergence of full recycle fuel cycles for actinide transmutation in recent years has brought greater attention to the means of controlling Np speciation in PUREX‐style separations. The details of neptunium’s speciation complexity are discussed in Section 24.4.4f. Synergistic systems generally combine acidic extractants, usually and most effectively multidentate chelating agents, with solvating extractants, hence they share some features of both liquid cation exchangers and solvating extractant molecules. Ion pair‐forming extractants tend to be micellar in most organic solutions and to exchange simple anions for negatively charged metal coordination complexes. For actinide extraction by liquid anion exchangers, the

Fundamental features of actinide separation systems

2647

Fig. 24.6 Extraction of actinides into tri(n‐butyl )phosphate/dodecane as a function of nitric acid concentration.

anionic complex (e.g. AmCl 4 ) exists only in the organic phase in the presence of the lipophilic counter‐ion and is usually not an important species in the aqueous phase. These extractants are the soluble analogs of anion exchange resins and so exhibit relative actinide affinities in the order: An(IV) > An(VI) > An(III) > An(V). As a general (though not universal) rule, the greatest selectivity for metal ions having similar properties (like adjacent trivalent lanthanides or actinides) is seen in acidic extractant systems, particularly those involving the formation of multidentate complexes. Solvating extractant systems tend to exhibit their greatest selectivity only for metal ions differing in charge (for interactinide separations, this implies the presence of the metal ions in different oxidation states), but extract chemically similar species without much selectivity. Such behavior is also generally seen for micellar reagents, i.e. minimal selectivity is demonstrated for series of closely related metal ions. Synergistic systems achieve increased extraction strength, usually at the price of decreased selectivity (though there are some exceptions).

2648

Actinide separation science and technology

Table 24.4 Am and Eu extraction with 20% triisooctyl amine from 11.9 M LiCl/0.1 M HCl (Moore, 1961). Percent extracted Diluent

Am

Eu

Separation factor Am SEu

xylene toluene benzene mesitylene hexone 0 b,b ‐dichloroethyl ether o‐Dichlorobenzene nitrobenzene n‐Hexane CH2Cl2 CCl4 CHCl3

91.7 87.0 80.8 94.2 87.3 97.1 80.6 87.2 98.4 99.7 23.4 0.6

15.7 10.1 7.0 23.4 2.7 63.1 7.5 11.8 54.8 91.3 0.9 102 . Elements of the TALSPEAK (or reverse) still get periodic consideration in process chemistry of actinide recycle, as will be discussed in Section 24.4.4 g. French researchers have investigated the use of soft‐donor extractants and complexants to enhance actinide/lanthanide group separations (Musikas et al., 1980; Musikas, 1985; Vitorge, 1985). The relative stability constants for lanthanide and actinide azide complexes reported by Musikas et al. (1980) suggest that hydrazoic acid (HN3) could function as a useful reagent for this separation. This is confirmed in a later report on Am/Eu separation (Musikas, 1985) in which americium extraction is suppressed by complex formation with azide. The separation factors are similar to those reported by Sekine (1965) using SCN as the complexant in TBP extraction. As to the thermodynamic factors describing this system, Choppin and Barber (1989) find that, while the trivalent actinide–azide stability constants are somewhat larger than those of the trivalent lanthanides, the complexation enthalpies (calculated from the temperature coefficient of the stability constants) do not support the existence of a covalent bonding contribution. A soft‐donor extractant system, mixtures of o‐phenanthroline and nonanoic acid (Musikas, 1985), extracts americium in order of magnitude more strongly Am than europium from 0.1 M NaNO3 solutions at pH 4.5–5.1 ½SEu ¼ ð17:4  0:9Þ . To accomplish the separation at higher acidity, research has been conducted on the complexant/extractant 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine (TPTZ, Structure u), used in conjunction with carboxylate and sulfonate co‐extractants. The latter is necessary because of the hydrophilicity of the Am(NO3)3TPTZ complex. Replacement of nitrate by a‐bromocaprate (with decanol as diluent) gives group separation factors  10 with little apparent variation in the distribution ratios for the members of the groups (Am, Cm, or Eu, Nd, Tb, and Yb) (Table 24.8) in the pH range of 2–3. Substitution of dinonylnaphthalenesulfonic acid (HDNNS) for a‐bromocapric acid gives similar performance at 0.1 M acid.

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Actinide separation science and technology

Table 24.8 Extraction of selected trivalent actinides and lanthanides by 2,4,6‐tris (2‐pyridyl)‐1,3,5‐triazine (TPTZ)/1 M a‐bromocapric acid (ABCA)/decanol, and TPTZ/ HDNNS/t‐butylbenzene(TBB) nitric acid (Musikas, 1985). Metal

D(TPTZ/ABCA) pH 2.2

D(TPTZ/(TPTZ/HDNNS) [HNO3] ¼ 0.12 M

Am Cm Ce Nd Eu Gd Tb Yb

0.85 0.80 – 0.08 0.10 – 0.11 0.10

1.35 1.40 0.158 – 0.199 0.178 0.14 0.22

Structurally, TPTZ is perhaps not ideally suited as an extractant for this separation. Though there are a number of nitrogen donor atoms present in TPTZ, the planar nature of the ligand demands that no more than three nitrogen atoms be coordinated to a metal ion, leaving three additional potential donor atoms available for interactions (quite probably non‐productive interactions) with other solutes in the organic phase. Continued research on the design, synthesis, and characterization of polyaza extractants led ultimately to the development by Kolarik et al. (1999) of the bistriazinylpyridine (BTP) class of ligands (Structure v). Work continues on the adjustment of the structure and properties of these ligands (Ha¨gstrom et al., 1999; Hudson et al., 2003; Drew et al., 2004a, b).

In this ligand, pyridine rings have been substituted by triazines, in a geometry that favors at least tridentate coordination of the metal ion. Actinide/lanthanide

Fundamental features of actinide separation systems

2675

separation factors as high as 100 have been reported. This ligand is receiving considerable attention as a candidate for process‐scale lanthanide/actinide reagent (Madic et al., 2002). To date, 75 derivatives of this class of reagents have been prepared and have undergone some degree of characterization. Lipophilic co‐extractants (carboxylic or organophosphoric acids) and/or long‐chain alcohol diluents are often employed to minimize partitioning of the BTP extractant to the aqueous phase. Another polyaza ligand that has received some attention for its potential to accomplish actinide/lanthanide separation is the EDTA structural analog N,N, N0 ,N0 ‐tetra(methylpyridyl)ethylenediamine (TPEN, Structure w). Investigations of the structure of lanthanide complexes (Morss and Rogers, 1997) and the thermochemistry (Jensen et al., 2000) of the corresponding aqueous species confirm the existence of a hexadentate coordination mode and an apparent 100‐fold selectivity for actinides over lanthanides in aqueous solutions. Separation‐specific studies have been conducted by Takeshita and coworkers (Watanabe et al., 2002). These authors have reported separation factors greater than 70 in a synergistic extraction system analogous to that employed in the BTP system. As with all polyaza ligands, extractant partitioning to the aqueous phase is a complication in these systems.

In general, f‐elements are poorly extracted by simple sulfur donor extractants. Furthermore, extractant molecules that incorporate sulfur as a donor atom are often plagued by poor stability when contacted with acidic (particularly nitrate) aqueous solutions. Certain types of extractants are more vulnerable to such attack, as results presented by Musikas (1985) indicate. His reports of good actinide/lanthanide separation factors for solvent extraction by thio derivatives of HDEHP were later dismissed (Freiser, 1988) as being the result of hydrolysis of the extractant to produce the oxygenated derivative. Because the oxygenated analogs of thiophosphorus ligands extract trivalent lanthanide/actinide cations very strongly, even very low concentrations of these degradation products profoundly compromise the ability of the soft‐donor extractant to accomplish the separation. Thiophosphinic acids like Cyanex 301 are slightly more resistant to hydrolytic degradation than the dialkyldithiophosphates though the oxygenated products of their hydrolysis are as damaging to a successful lanthanide/actinide separation as HDEHP is in the thiophosphate system. This extractant when employed for separations of d‐transition metals (e.g. Cd2þ) is often used in a de‐aerated

2676

Actinide separation science and technology

environment to reduce the impact of degradation of the extractant on separation efficiency. Unfortunately, for separations of radioactive materials, the effect of radiolysis (and the oxygenated by‐products of water radiolysis) cannot be eliminated and degradation of the extractant will be problematic in process applications. Other derivatives of dialkyl dithiophosphinic acids have also been prepared and evaluated as potential actinide/lanthanide separation reagents. Results from Jarvinen et al. (1995) indicate moderate separation factors for americium from europium using dithiophosphinic acid extractants (R2PS2H) Cyanex 301, dicyclohexyldithiophosphinic acid, and diphenyldithiophosphinic acids. Wang et al. (2001) have synthesized several dialkylthiophosphinic acids where 2,4,4‐ trimethylpentyl group present in Cyanex 301 was replaced with n‐octyl, 1‐methylheptyl, 2‐ethylhexyl, heptyl, or hexyl groups. It has been observed that by using 0.5 M solution of the thiophosphinic acids, the pH for 50% extraction (pH1/2) of americium and europium from 1 M sodium nitrate is 2.58, 2.63, 2.67, 3.19, and 3.94, 3.99, 4.06, 4.52, respectively, for R ¼ n‐octyl, 1‐methylheptyl, 2‐ethylhexyl, or 2,4,4‐trimethylpentyl groups. The Am/Eu separation factors for the four extractants are 1  104. These authors suggest that di(2‐ethylhexyl)dithiophosphinic acid is the most promising of these extractants because of its lower pH1/2 and higher loading capacity of extraction of americium as compared to Cyanex 301 (Tian et al., 2001). More data on extractions Am at macro concentrations of the lanthanides, SEu mixer–settler or centrifugal contactor runs will be required to substantiate these studies. In an attempt to lower the pH1/2 of this class of extractants, Modolo and Odoj (1999) prepared bis( p‐chlorophenyl)dithiophosphinic acid. This extractant in a process solvent that includes tri(n‐butyl)phosphate or trioctylphosphine oxide as a co‐extractant is able to selectively extract trivalent actinides from lanthanides with separation factors acceptable for process applications. This extractant is receiving attention for possible process application, as will be discussed in Section 24.4.5b. M0 The higher SM between americium and europium has been suggested by Ionova et al. (2001) as being due to the strong coordination of M(III) to soft‐ donor sulfur atoms of Cyanex 301, covalent effect being significantly higher for Am–S as compared with Eu–S bonds. These authors have further shown that while using a mixture of Cyanex 301 and neutral O‐bearing co‐extractants, Am the extraction of M(III) and SEu can be correlated with the effective charge on Am O atom of the neutral organophosphorus extractant molecule. The SEu reported are 3200 for Cyanex 301 alone, 4700 for Cyanex 301 and TBP, 9100 for Cyanex 301 and tri‐tert-butyl phosphate, 16 000 for Cyanex 301 and tri‐ phenyl phosphate, 0.45 for Cyanex 301 and TOPO/CMPO, 95 for Cyanex 301 and N, N0 ‐dimethyl‐N,N0 ‐dibutyltetradecylmalonamide, and 17 000 for Cyanex 301 and N, N0 ‐di (ethyl‐2‐hexyl)dimethyl‐2,2‐butanamide. Other classes of sulfur donor extractants appear to be more resistant to hydrolysis, and have demonstrated some potentially useful selectivity for

Fundamental features of actinide separation systems

2677

Table 24.9 Distribution ratios and separation factors for americium/ europium extraction by 4‐benzoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3H‐ pyrazol‐3‐thione/toluene (0.0297 M)/0.1 M NaClO4 as a function of 4,7‐diphenyl‐1,10‐phenanthroline (synergist) from (Ensor et al., 1988). [DPPHEN]

DAm

SAm Eu

0.00269 0.00215 0.00144 0.00108 0.000718 0.000359

25.3 21.9 14.8 10.3 6.1 2.7

183 196 192 174 156 129

actinides over lanthanides. For example, the mixture of 0.3 M 4‐benzoyl‐2, 4‐dihydro‐5‐methyl‐2‐phenyl‐3H‐pyrazol‐3‐thione (BMPPT)/0.01 M TOPO/benzene extracts (from 0.1 M LiClO4, pH 3) americium preferentially over europium Am ðSEu ¼ 68Þ (Smith et al., 1987). The analogous system based on the oxygen‐ donor analog and TOPO (Chmutova and Kochetkova, 1970) gave stronger extraction but no significant separation of curium from europium. Further substitution of the soft‐donor synergist 4,7‐diphenyl‐1,10‐phenanthroline (DPPHEN, Structure x) for TOPO (Ensor et al., 1988), results in even greater Am selectivity for americium (SEu ¼ 190, pH 3.7, 0.03 M HBMPPT/0.0027 M DPPHEN). The extracted species is M(BMPPT)3(DPPHEN) (Table 24.9). This is the only known example of a system that contains soft‐donor atoms in both the primary extractant and in the synergist. Choppin et al. (1995) have reported on the separation of americium from europium using various combinations of thiothenoyltrifluoroacetone, tri(n‐butyl)phosphate, tributylphosphine sulfide, and N,N‐dimethyl‐N,N0 ‐dihexyl‐3‐oxapentanediamide as coextractant ligands in a synergistic extraction system. In this case, the soft‐donor ligands show little enhancement of Am/Eu separation factors.

24.3.10

Supercritical fluid extraction of actinides

The field of supercritical fluid extraction (SFE) of metal ions has been developed during the past decade. Among the first papers published, those by Wai and co‐ workers were the most important. In 1991, this group (Laintz et al., 1991)

2678

Actinide separation science and technology

published a paper describing the solubility of fluorinated metal dithiocarbamates in supercritical carbon dioxide (sc‐CO2) wherein they demonstrated that the solubility of the fluorinated dithiocarbamates were two to three orders of magnitude higher than those of the corresponding non‐fluorinated compounds. This technique was thus recognized as a promising new extraction method for metal ions from various sources. A year later, Wai and co‐workers published a second paper (Laintz et al., 1992) related to the SFE of metal ions from aqueous solutions and solid materials, and in 1993 they demonstrated the possibility of extracting lanthanide (Ln) and actinide (An) ions from solid materials with a fluorinated b‐diketone (Lin et al., 1993). The rationale for the use of SFE of metal ions as an alternative to conventional liquid–liquid extraction (LLE) was mainly to minimize the generation of the secondary organic waste often encountered in LLE processes. Carbon dioxide was chosen as the most appropriate supercritical fluid because: (i) the values of the critical point (Darr and Poliakoff, 1999) were appropriate for a SFE application: Pc ¼ 72.9 atm, T ¼ 304.2 K, rc ¼ 0.47 g mL–1; (ii) CO2 can be considered as a green solvent for the environment; (iii) (aside from asphyxiation hazards) CO2 is harmless to workers; (iv) CO2 is almost inert with respect to radiolysis; (v) CO2 is inexpensive. Moreover, the high diffusivity of sc‐CO2 means that rapid extraction of the metal ions from their sources can be expected. Since 1991, about 80 reports related to the SFE of metal ions have been published, most of them related to actinides. The most studied actinide ion is U(VI), with about 50 papers. This field was recently reviewed by Darr and Poliakoff (1999) and by Wai (2002). The sections to follow present the most important aspects of the SFE of actinide ions contained within various sources: (i) aqueous solutions, (ii) solid materials, (iii) pure actinide oxides. As most of the information available in the literature is related to U(VI), the examples discussed will predominantly concern this ion. (a)

Experimental setup and SFE procedures

Fig. 24.12 is a schematic of an experimental setup proposed by Tomioka et al. (2001a) for the SFE of metal ions from a metal oxide. A similar apparatus has been described by Wai and Laintz (1999). The carbon dioxide passes first through a vessel where it dissolves the contained ligand (solid or liquid). In the second vessel, the sc‐CO2 ligand solution then comes into contact with the actinide oxide to be extracted. Trofimov et al. (2001) recently showed that the use of ultrasound increases the solid dissolution rate. After extraction, the metal ion complex can be recovered by reducing both the pressure and temperature of the sc‐CO2 solution, leading to the precipitation of the metal ion complex and of the excess ligand. The CO2 can subsequently be recycled. To perform this reduction of pressure and temperature, the loaded sc‐CO2 solution passes through a capillary restrictor made of silica or stainless steel. Wai et al. (1998) noted some drawbacks to using this technique, such as clogging of the capillary

Fundamental features of actinide separation systems

2679

Fig. 24.12 Apparatus for the dissolution of uranium oxide powder with supercritical CO2 containing the HNO3–TBP complex (adapted from Tomioka et al., 2001a).

by the solutes, or breaking of the silica capillary in case of the use of sc‐CO2 modified with methanol. They therefore proposed an improved stripping method to eliminate these drawbacks by passing the loaded sc‐CO2 solution through an acidic aqueous solution while maintaining the pressure and temperature conditions of the SFE. Extraction of metal ions from aqueous solutions can be performed in such an apparatus with minor modifications. Several systems have been developed to measure the concentration of the metal ion extracted into the sc‐CO2. The most popular uses a UV–visible spectrophotometric cell to measure colored metal ion complexes, as in the case of U(VI) (Furton et al., 1995; Addleman et al., 1998; Sasaki et al., 1998). Recently, Wai and co‐workers (Carrott and Wai, 1998; Hunt et al., 1999) proposed sophisticated UV–visible measurement cells, with several light path lengths (38 mm, 733 mm, and 1cm) coupled with optical fibers, the spectra being measured with a charge–coupled device array UV–visible spectrophotometer. In the case of SFE of U(VI), the same research group also proposed the use of a Raman measurement cell (Addleman et al., 1998) or of a time‐resolved laser‐ induced fluorescence spectrometry cell (TRLIFS) (Addleman et al., 1998, 2000a,b; Addleman and Wai, 1999, 2000). The latter technique permits the measurement of U(VI) complexes under a wide range of concentrations.

Actinide separation science and technology

2680

The pressure and temperature conditions often chosen for SFE of metal ions are the following: pressure in the range 150–300 atm, temperature in the range 60–120 C. Frequently used conditions are 150 atm and 60 C. SFE of metal ions can be carried out in two modes: (1) Static mode: The actinide containing sample and the sc‐CO2 fluid are placed in contact and stirred until the actinide distribution equilibrium is obtained. The actinide‐loaded sc‐CO2 fluid is then removed from the extraction vessel. (2) Dynamic mode: The sc‐CO2 fluid containing the extractant is continuously fed to the extraction vessel and the actinide‐loaded sc‐CO2 fluid is then stripped online.

(b)

SFE properties of actinide ions

(i)

Ligands

Numerous ligands can be used for the SFE of actinide ions, most of which have also been used (or are structurally similar to reagents that have been used) in conventional solvent extraction. The most important ones are as follows. b‐Diketones A ligand of this type, 2,2‐dimethyl‐6,6,7,7,8,8,8‐heptafluoro‐3,5‐octanedione (FOD), was used by Wai and coworkers in the first article related to the SFE of actinide ions (Lin et al., 1993). It was shown that about 99% of 10 mg of uranyl ion contained within uranyl acetate solutions at pH 1.0 or deposited on cellulose‐based filter paper from a solution at pH 6.5, can be extracted under the following SFE conditions: 80 mg of FOD, sc‐CO2 containing 5% methanol, wet paper, 60 C; 150 atm. In another article, the same group (Lin et al., 1994) studied the SFE efficiency of several b‐diketones for Th(IV) and U(VI); the following ligands were studied: acetylacetone (AA), trifluoroacetylacetone (TAA), hexafluoroacetylacetone (HFA), thenoyltrifluoroacetone (TTA), and FOD. In the absence of methanol in the sc‐CO2 and all other SFE conditions being identical to those mentioned above, the extraction efficiency observed for U(VI) and Th(IV) were the following, respectively: 10 and 12% (AA), 15 and 22% (TAA), 40 and 69% (HFA), 51 and 80% (FOD), and 70 and 82% (TTA). The fluorinated b‐diketones are the most effective ligands and among them TTA seems to be the best. Note that Th(IV) is slightly more strongly extracted than U(VI) under these conditions. Neutral organophosphorous compounds Organophosphates and phosphine oxides were the most studied neutral organophosphorous compounds for SFE of actinide ions. Work has principally focused on the use of TBP for the extraction of uranyl nitrate (Lin et al., 1994, 1995; Iso et al., 1995, 2000; Meguro et al., 1996, 1997, 1998b, 2002;

Fundamental features of actinide separation systems

2681

Toews et al., 1996; Smart et al., 1997b; Carrott et al., 1998; Sasaki et al., 1998; Addleman et al., 2000a; Addleman and Wai, 2000, 2001; Enokida et al., 2000; Park et al., 2000; Tomioka et al., 2000, 2001a,b, 2002; Clifford et al., 2001; Shamsipur et al., 2001) This was certainly related to the observation of Toews et al. (1996) that of the three extractants TBP, tri‐n‐butylphosphine oxide (TBPO) and tri‐n‐octylphosphine oxide (TOPO), TBP was by far the most effective ligand for sc‐CO2 extraction and transport of uranyl nitrate. This is primarily a result of the greater solubility of TBP in sc‐CO2 relative to the phosphine oxides (Lin et al., 1995). Only a few reports concern the TBP‐ mediated SFE of other actinide ions: Th(IV) (Lin et al., 1995) and Pu(IV) (Iso et al., 2000). SFE of actinide ions (mostly U(VI) and Th(IV) by phosphine oxides has been the subject of a few reports (Lin et al., 1995; Toews et al., 1996; Wai et al., 1999; Addleman et al., 2000a; Shamsipur et al., 2001). It should be noted that most of the research on the extraction of actinide ions by neutral organophosphorous ligands has been done by Wai (U.S.), Yoshida (Japan) and their coworkers. Some of the results related to the extraction of uranyl nitrate by TBP are presented here; other results related to this system will be presented later in this section. The extracted complex in sc‐CO2 has the same stoichiometry [UO2(NO3)2(TBP)2] as is observed in conventional solvent extraction. The identity of the complex was established by Meguro et al. (1996) and confirmed by Wai et al. (1999) using the classical slope analysis method. This complex was characterized by UV–visible spectrophotometry (Addleman et al., 1998; Carrott et al., 1998; Sasaki et al., 1998), Raman spectrometry (Addleman et al., 1998), and TRLIFS (Addleman et al., 1998, 2000a,b; Addleman and Wai, 1999, 2000, 2001). TRLIFS was used in particular by Addleman and coworkers to determine the solubility of the U(VI) complex (Addleman et al., 2000a) and the DU(VI) values (Addleman and Wai, 2001), and for online measurement of the extracted U(VI) (Addleman et al., 2000b). The extraction kinetics of uranyl nitrate by TBP in sc‐CO2 are rapid (Wai et al., 1999) ( 45 min) if the U(VI) source consists of aqueous solutions. With solid samples (tissue paper, soil, sand, etc.), the extraction of U(VI) requires more time. An efficient model for interpreting the kinetic aspects of the SFE extraction of uranyl nitrate by TBP in sc‐CO2 in dynamic mode was recently proposed by Clifford et al. (2001). The value of DU(VI) is 2.0, for extraction by 0.3 mol L–1 TBP in sc‐CO2 at 60 C and 15 MPa from an aqueous solution of 3 mol L–1 HNO3 (Iso et al., 2000). Under the same experimental conditions, the distribution ratio for Pu(IV) was found to be 3.1 (Iso et al., 2000). Other thermodynamic aspects of the extraction of uranyl nitrate by TBP are considered below in the discussion of the influence of pressure and temperature on the SFE of metal ions. Uranyl nitrate can be effectively extracted from various sources, such as aqueous solutions, whether acidic or neutral, and solid waste (cellulosic paper, contaminated soil or sand, metallic waste). The solubility of UO2(NO3)2(TBP)2 in sc‐CO2 was found to be the highest of all the metallic complexes studied so far (Meguro et al., 1996):

Actinide separation science and technology

2682

0.43 mol L–1 at 40 C and 225 atm (Carrott et al., 1998). This moderate solubility warrants consideration of process development for spent nuclear fuel reprocessing. Only a few reports have considered the use of bidentate neutral organophosphorous extractants. This is certainly due to the low solubility of these ligands in sc‐CO2, as shown by Meguro et al. (1998a) for dihexyl (N,N,‐diethylcarbamoyl)methylphosphonate and for the octyl(phenyl)(N,N‐diisobutyl)carbamoylmethylphosphine oxide (OFCMPO). Synergistic mixtures In 1994, Lin et al. (1994) were the first to report the existence of synergistic phenomena for the SFE of U(VI) and Th(IV) ions. For example, with TTA and TBP extractants at 60 C and 150atm, SFE was carried out in dynamic mode on samples consisting of sand (200 mg) contaminated with 10 mg of U and 10 mg of Th with the following results (U and Th extracted, respectively): TTA (80 mmol) ¼ 72 and 74%; TBP (80 mmol) ¼ 15 and 10%; TTA þ TBP (40 mmol þ 40 mmol) ¼ 94 and 93%. A net synergistic effect was thus observed for the extraction of both actinide ions. Several papers related to SFE of actinide ions by diketones and neutral organophosphorous compound synergistic mixtures have been published since (Furton et al., 1995; Lin et al., 1998, 2001; Murzin et al., 1998; Addleman et al., 2000a, 2000b; Geertsen et al., 2000).

(ii)

Modifiers

The addition of a modifier can be an effective means of enhancing the extraction efficiency of sc‐CO2 extractant solutions. Methanol is the most widely used modifier. The use of methanol as an sc‐CO2 modifier was often reported when the ligands were b‐diketones and their synergistic mixtures, but modifiers are not ordinarily used in the case of TBP alone. The following example illustrates the efficiency of methanol as an sc‐CO2 modifier. Lin et al. (1994) studied the SFE of U(VI) and Th(IV) with the b‐diketones: AA, TAA, HFA, FOD, and TTA, with neat or 5% methanol‐modified sc‐CO2. The following experimental conditions were chosen: 60 C, 150 atm, cellulose‐based filter contaminated with 10mg of U and 10mg of Th, 80mmol of ligand, dynamic extraction. The actinide ion extraction yields obtained for neat and 5% methanol‐modified sc‐CO2, respectively, were as follows: AA (U ¼ 10 and 45%; Th ¼ 12 and 58%), TAA (U ¼ 15 and 98%; Th ¼ 22 and 95%), HFA (U ¼ 40 and 95%; Th ¼ 69 and 92%), FOD (U ¼ 51 and 98%; Th ¼ 80 and 97%), TTA (U ¼ 70 and 96%; Th ¼ 82 and 91%). The presence of methanol thus induces a net increase in uranium and thorium extraction efficiency, and this is certainly correlated to the increased polarity of the sc‐fluid due to the presence of the modifier. With SFE of solid samples, such as soil, sand or paper, it is also observed (Lin et al., 1993) that a small amount of water must be added to obtain satisfactory metal ion extraction efficiency.

Fundamental features of actinide separation systems (c)

2683

Influence of pressure and temperature on SFE of actinide ions

The SFE efficiency of actinide ion complexes can be tuned by modifying the pressure and temperature conditions as well. To illustrate these properties, consider the TBP SFE of U(VI) and Pu(IV) nitrates from aqueous nitric acid solutions, as studied by Yoshida and coworkers (Iso et al., 2000). At constant temperature and TBP concentration in sc‐CO2, an increase in pressure induces a decrease in DU(VI) and DPu(IV) correlated with the higher density of the sc‐fluid. A simple linear correlation between DU(VI) or DPu(IV) and r is observed in log–log plots: log D ¼ a log r þ b

ðIÞ

in which a is a proportionality constant related to the solvation characteristics of the metal complexes in sc‐CO2. The slopes a of the relationships were equal to –(2.7  0.5) for U(VI) and –(1.6  0.1) for Pu(IV). The differences in D as well as in the slope a between U(VI) and Pu(IV) make it possible to design a SFE scheme to separate uranium from plutonium. In the case of U(VI), for a temperature increase from 313 to 353 K and for a pressure of 40 MPa, DU(VI) decreases by a factor of about 2, as shown by Yoshida and coworkers (Meguro et al., 1997; Iso et al., 2000). Conversely, the same group (Iso et al., 2000) has shown that DPu(IV) increases with T, and the lower the pressure the greater the temperature effect. The increase in the pressure of sc‐CO2 that induces an increase in the density of the sc‐fluid has a large impact on the solubility of solutes. Chrastil (1982) demonstrated that the solubility S (g L–1) of an organic solute in a sc‐fluid is correlated with the density (g L–1) of the sc‐fluid by the following empirical relation ln S ¼ k ln r þ C

ðIIÞ

where the value of k is related to the solute–solvent interactions and that of C to the volatility of the solute. Since then, equation (II) has also been found to represent variations of the solubility of metal ion complexes in sc‐CO2. A review of the solubility of chelating agents and their metal complexes has been published by Smart et al. (1997a). This equation was also shown to be usable to represent the solubility of actinide ion extractants and their complexes (Meguro et al., 1998b). This is the case in particular for UO2(NO3)2(TBP)2 (Carrott et al., 1998; Addleman et al., 2000a) which, as noted above, is the metallic complex with the highest solubility in sc‐CO2. (d)

Sources of actinide ions for SFE

Several sources of actinide ions can be treated by SFE, including: (1) Aqueous solutions: Acetate‐buffered solution are often used when the extractants are b‐diketones (Lin et al., 1994), nitric acid, and nitric acid and alkali nitrate solutions (Lin et al., 1995; Meguro et al., 1996, 1997,

2684

Actinide separation science and technology

1998b; Smart et al., 1997b; Iso et al., 2000), uranium mine water (Lin et al., 1994). (2) Solid matrices (surrogates or genuine wastes): Cellulosic filter paper (Lin et al., 1993, 1994; Brauer et al., 1994; Shamsipur et al., 2001; Kumar et al., 2002), sand (Tomioka et al., 2002), soil (Fox et al., 1999), kaolin (Furton et al., 1995), glass wool (Furton et al., 1995), metals (Murzin et al., 1998; Shadrin et al., 1998), asbestos (Murzin et al., 1998), rubber (Murzin et al., 1998), plastics (polyethylene, polyester) (Furton et al., 1995), contaminated with solid actinide compounds, such as nitrates or oxides, (3) Actinide oxides: This case is particularly important in the light of the potential future applications, and is considered here in greater detail. Wai et al. (1997) filed a patent related to the SFE of metal ions directly from their oxides. They proposed as ligands numerous acidic compounds including b‐diketones, phosphinic acids, and carboxylic acids. Better performance was seen for fluorinated derivatives. In 2000, Tomioka and coworkers (Enokida et al., 2000; Tomioka et al., 2000) described the dissolution of gadolinium and neodymium ions from their sesquioxides M2O3 (M¼Gd and Nd) by the complex TBP–HNO3 dissolved in sc‐CO2. Wai and Waller (2000) also demonstrated the efficiency of the SFE extraction of uranium from UO3 by TTA or TTA þ TBP synergistic mixtures. Several papers related to the dissolution of uranium oxides (UO2, U3O8, and UO3) by the TBP–HNO3 complex have been published since then (Enokida et al., 2000; Samsonov et al., 2001; Tomioka et al., 2001a,b; Trofimov et al., 2001). The dissolution of UO2 was less rapid than those of the two other oxides, but it is possible to increase the dissolution rates of oxides if the HNO3/TBP molar ratio in sc‐CO2 is greater than 1. In a recent conference paper, Samsonov et al. (2002) reported the SFE of actinides from their oxides using TBP–HNO3; the studied oxides were: ThO2, UO2, U3O8, and UO3, NpO2, and PuO2. Under the experimental conditions [65 C, 250 atm, TBP– HNO3 reagent in sc‐CO2, thrice‐repeated alternation of static (10 min) and dynamic (15 min) extractions] it was shown that the extraction yields of U oxides were good (> 85% for the lowest value) while those of the oxides of Th, Np, and Pu were almost nil. (e)

Possible applications

(i)

Industrial processes

(1) Spent nuclear fuel reprocessing: Smart and Clifford (2001) from BNFL (UK) filed an international patent in 2001 in which they claimed that the reprocessing of spent nuclear fuel will be possible using the SFE method. The several steps of the conceptual process flow sheet are the following: (i) oxidize decladding of spent fuel under oxygen at 600 C, (ii) SFE of uranium by treatment of the oxidized fuel with a sc‐CO2 solution containing

Fundamental features of actinide separation systems

2685

an acidic ligand like a b‐diketone, (iii) separation of U from the other extracted ions in fractionation columns, and (iv) reduction of the volatile uranium complex by hydrogen to precipitate UO2. Probably the most interesting reagent for such application is TBP–HNO3 as noted by the teams of Wai and Yoshida. (2) Actinide waste decontamination: As noted above, the efficiency of SFE extraction of actinides from miscellaneous solid wastes has been demonstrated. An interesting case was the demonstration by Shadrin et al. (1998) of the efficiency of SFE for decontamination (U, Np, Pu, and Am) of ‘real‐world’ contaminated stainless steel. This could be a basis for further industrial developments. (ii)

Analytical applications

SF‐chromatography has been used to develop analytical methods. Examples include the work of Martin‐Daguet et al. (1997) and Geertsen et al. (2000) for the analysis of U(VI). (f)

Conclusions

SFE of actinide ions has been a very active research field since its inception a decade ago. Important nuclear applications may some day be developed, particularly in spent nuclear fuel reprocessing and nuclear waste decontamination. The observation by Wai et al. on dissolution of uranium oxides by sc‐CO2 solutions of HNO3–TBP solutions is noteworthy. The Wipff group is examining the system using the techniques of computational chemistry (Baaden et al., 2002; Schurhammer and Wipff, 2003). However, fundamental understanding of the basic chemistry of actinide interactions in supercritical media lags far behind practical demonstrations. Considerable basic research and development studies are still required, but it is safe to say that the interest in this field is likely to increase in the future.

24.3.11

Actinides in room‐temperature ionic liquids (RTILs)

Room temperature ionic liquids (RTILs) were discovered by Hurley and Wier (1951), who found that a mixture of AlCl3 and ethylpyridinium bromide (EPB) in a 2:1 molar ratio melted at 40 C and that this liquid is suitable for the electrodeposition of aluminum metal at room temperature. Research in this area has been pursued with two main objectives: the development of electrolytes for batteries, and the use of RTILs as ‘green’ liquids for the design of industrial processes for the synthesis of organic compounds. Though continuing research has established that this class of RTILs can indeed be quite toxic, these liquids are considered ‘green’ compared with traditional organic solvents used in the industry because they have no vapor pressure, hence no gaseous emissions, at

2686

Actinide separation science and technology

least from intact RTIL formulations. However, it should further be noted that many RTIL formulations are based on the use of hydrolytically unstable inorganic anions like PF 6 (reacts with water to produce HF). For more information on the properties of these materials, see reviews by Hussey (1983) and Welton (1999). The interest in using RTILs to develop separation processes for metals, for example liquid–liquid extraction with hydrophobic RTILs, is quite recent, as noted in a review by Visser et al. (2002). This subject became a hot topic in the late 1990s. The first paper dealing with an actinide in an RTIL, published in 1982 by De Waele et al. (1982), examined the electrochemical behavior of uranium(IV) in a Lewis acidic AlCl3 þ N(n‐butyl)pyridinium chloride (BPC) RTIL. Since that time, about 20 papers including patents for separation applications related to the chemistry of actinides within RTILs have been published, most of them (16) being related to uranium. In this short review, after a brief presentation of RTILs, the main chemical properties of actinides in RTILs will be described and the possible uses of RTILs for actinide separation presented. (a)

A brief description of RTILs

RTILs (Carpio et al., 1979; Hussey, 1983; Visser et al., 2002) are salts made of organic cations, such as: (i) N‐alkyl quaternary ammonium, R4Nþ, (ii) N‐alkyl pyridinium, (iii) N‐alkylisoquinolinium, (iv) 1‐N‐alkyl‐3‐methylimidazolium, (v) N‐alkyl quaternary phosphonium, R4Pþ, associated with various anions, e.g. halides (Cl–, Br–), haloaluminates (chloro or bromo), chlor     ocuprate ðCuCl 2 Þ, tetraalkylborides ðR4 B Þ; NO3 ; CF3 CO2 ; BF4 ; PF6 ; and     NðSO2 CF3 Þ2 . With the anions BF4 ; PF6 ; NðSO2 CF3 Þ2 , the RTILs are most often hydrophobic and can be used, for example, for the development of liquid– liquid extraction separation processes (Visser et al., 2002). Nevertheless, most of the work related to actinides concerns RTILs of AlCl3 and N‐alkylpyridinium or N‐alkylmethylimidazolium chlorides (called APC and AMIC, respectively). Both classes are highly sensitive to moisture. Recent work concerning the use of RTILs for nuclear fuel reprocessing is based on an RTIL made of N‐alkylmethylimidazolium nitrate (Thied et al., 1999). RTILs with nitrate anions were mentioned for the first time by Lane (1953). The physical properties, such as the density, viscosity, or electric conductivity of RTILs consisting of mixtures of AlCl3 and APC or AMIC have been the subject of numerous measurements (Carpio et al., 1979; Hussey, 1983; Fannin et al., 1984). The density of these melts exceeds 1 kg dm–3; although most of them are quite viscous, their conductivity is suitable for electrochemical applications. The chemistry of these melts is dominated by the Lewis chloro‐acidity. Depending on the molar ratio (Mr) of AlCl3 versus APC or AMIC, the chloro‐ acidity (which can be expressed as pCl with low and high pCl for basic and acidic melts, respectively) of the melts varies. For Mr ¼ 1, >1, and 400 C) works because UO2 and PuO2 conduct electricity and can be electrodeposited at a cathode like a metal. According to the formal potentials listed in Table 24.10, UO2 and PuO2 are reduced at more positive potentials than all the fission products, except for noble metals (Bychkov and Skiba, 1999; Bychkov et al., 2000). If plutonium recovery is not necessary, UO2Cl2 is electroreduced to UO2 at the pyrolytic carbon cathode, leaving plutonium and the majority of fission products in the melt. Recovery efficiency is 99.0–99.5% (Bychkov and Skiba, 1999). At the anode, chloride ions are oxidized to chlorine gas. Table 24.10 Formal electrode potentials of actinides and fission products (vs Cl2/Cl , molar fraction) in NaCl–2CsCl eutectic at 600 C (in volts) (Bychkov and Skiba, 1999). Sm(II)/Sm Eu(II)/Eu Ce(III)/Ce

–3.58 –3.39 –3.08

Pu(III)/Pu U(III)/U Zr(IV)/Zr Fe(II)/Fe U(IV)/U(III) Mo(III)/Mo Ag(I)/Ag

–2.83 –2.39 –2.17 –1.48 –1.45 –0.97 –0.932

U(VI)/UO2 Pd(II)/Pd Rh(III)/Rh Ru(III)/Ru (510 C) Np(V)/NpO2 Pu(IV)/Pu(III) Pu(VI)/PuO2

–0.65 –0.48 –0.44 –0.413 – –0.05 þ0.12

Actinide separation science and technology

2706

If both uranium and plutonium recovery is desired, electrolysis must be carried out while sparging the melt with an oxygen–chlorine gaseous mixture (Bychkov and Skiba, 1999). The cathodic products are quasi‐homogeneous (U, Pu)O2 with two‐phase composition: solid solution of PuO2 in UO2 crystals and solid solution of UO2 in PuO2 crystals. UO2 deposition rate is pre‐set by current density while PuO2 deposition rate is limited by the diffusion of plutonyl ions to the cathode (Bychkov et al., 2000). If it should be necessary to recover only PuO2, dissolution is performed in NaCl–KCl and plutonium oxide is precipitated by oxygen gas (Bychkov and Skiba, 1999). Behavior of minor actinides (Np, Am, and Cm). After the dissolution step, neptunium is present in the melt as NpOþ 2 . As a result, neptunium is electroreduced to NpO2 and is co‐deposited with uranium oxide (see Table 24.11). The behavior of americium and curium is not similar to that of neptunium; they remain as soluble species in the melt like other soluble fission products (alkaline elements, alkaline earth elements, and rare earth elements) (Kormilitzyn et al., 1999). Separation of americium and curium from the soluble fission products by carbonate precipitation has been proposed. Sodium carbonate is added to the spent melt (NaCl–2CsCl or NaCl–KCl) for fractional precipitation of americium and curium, probably as sesquioxides M2O3 (M ¼ Am and Cm). Similar results were obtained for both media in terms of the possible separation of minor actinides and rare‐earth elements (hereafter REE) (Kormilitzyn et al., 1999, Fig. 24.16). Unfortunately, americium precipitates between lanthanide(III) and lanthanide(II), which makes it difficult to separate Am from REE. Even if a small part of the americium sesquioxide could be recovered by filtration at high temperature, the remaining americium precipitates as mixed oxide with REE. If the separation of americium from REE is not necessary, the melt can be purified by adding phosphate to precipitate americium (and curium) and fission products. Fission products in the trivalent oxidation state precipitate as insoluble double phosphates Na3M(PO4)2, while many fission products in the divalent

Table 24.11 Gibbs energies of formation of selected oxides at 1700 K compiled by Mullins et al. (1960) from (Glassner, 1957) kJ (g atom O)–1 (Recalculated from values in kcal (g atom O)–1). La2O3 Ce2O3 Nd2O3 Y2O3 SrO

–452 –452 –444 –439 –422

Pu2O3 UO2 ZrO2 MgO NbO FeO MoO2

–402 –397 –385 –376 –268 –151 –134

InO Sb2O3 K2O TcO2 Rh2O Rb2O RuO2 TeO2

–105 –96 –84 –67 –8 –8 0 0

Fundamental features of actinide separation systems

2707

Fig. 24.16 Relative contents for Pu, Am, Ce, Eu in NaCl–2CsCl melt during fractional carbonate precipitation coming just after electrolysis step (Kormilitzyn et al., 1999).

oxidation state, including alkaline earth elements, also precipitate (Kormilitzyn et al., 1999). (h)

Applications, separation efficiency in the DDP

A chlorinator–electrolyzer has been designed that will accommodate a volume of 40 L. It can reprocess a loading of about 30 kg of material. All the internal surfaces that come into contact with the salt and gaseous phases (anode‐ crucible, cathode, gas tube) are crafted of pyrolitic graphite. After pyroelectrochemical treatment, the cathodic deposits are crushed, purified from salts by distillation, dried, and classified for vibropac fabrication of fuel rods (Bychkov and Skiba, 1999). Since the 1970s about 3 metric tons of UO2, 100 kg of PuO2, and 1600 kg of (U–Pu)O2 have been produced in molten alkali chlorides for BOR60, BN350, and BN600 reactors. From 1968 to 1973, 5.8 kg of spent UO2 coming from VK‐50 and BOR60 reactors were reprocessed while spent MOX fuel reprocessing began in the 1990s with 4.1 kg from BN350 (burn‐up 4.7%) and 3.5 kg from BOR60 (burn‐up 21–24%) (Bychkov and Skiba, 1999). For example, reprocessing of MOX fuel from BOR60 involved: (i) dissolution of the fuel in LiCl–4.53NaCl–4.88KCl–0.66CsCl; (ii) electrolysis to remove part of UO2 free from Pu; (iii) PuO2 precipitation; (iv) additional electrolysis for removing residual uranium as UO2, and (v) melt purification by phosphates. Mass balances give information on the behavior of actinides and fission products. It has been found that (Bychkov and Skiba, 1999; Bychkov et al., 2000): (i) Zr, Nb, Ru, Rh, Pd, and Ag were located in the first UO2 deposit; (ii) U/Pu separation factor in the first electrolysis is 120–140; (iii) most of the

2708

Actinide separation science and technology

Np is distributed between the two UO2 deposits; (iv) Am is present in UO2 deposits ( 3.5 wt%), in PuO2 precipitate ( 18 wt%) and in phosphates ( 73 wt%); (v) practically all the Cm is in phosphates though it has also been detected in the second UO2 deposit; (vi) representatives of REE (Ce and Eu) are concentrated in phosphates, and (vii) Cs, Rb, and partially Sr remain in melt. If a (U, Pu)O2 deposit is desired, it will be necessary to perform a preliminary electrolysis for the removal of Ru, noble metals and Zr, before carrying out the main electrolysis under a chlorine–oxygen atmosphere. In tests on simulated materials in NaCl–2CsCl, the separation factors observed were: 1000 for Cs, >100 for REE, 1 for Ru and Zr without preliminary electrolysis, and 10 with preliminary electrolysis (Kormilitzyn et al., 1999). DDP is currently used for oxide fuel reprocessing and for producing three oxides: UO2, PuO2, and (U–Pu)O2. The latter one is mainly dedicated to MOX fuel fabrication for BOR‐60 reactor. Research programs are now focused on conversion of weapon‐grade plutonium into MOX fuel, development of a process for complete recycle of Pu, Np, Am and Cm (Dry reprocessing, Oxide fuel, Vibro‐compact, Integral, Transmutation of Actinides, DOVITA program) (Bychkov and Skiba, 1999).

(i)

Metal–metal processes

(i)

Melt refining (or oxide slagging process)

Early pyrometallurgical processes which have been developed for minimizing the cost of recycling were rudimentary. One example is the melt refining process, which was proposed to reprocess the metallic uranium fuel alloy used in the core of the second experimental breeder reactor (EBR‐II) (Motta, 1956; Burris et al., 1964). The fuel was an enriched uranium alloy ( 52 wt% 235U) containing 5 wt % fissium (mixture of molybdenum, ruthenium, rhodium, palladium, zirconium, and niobium) with sodium used as a thermal bond (Burris et al., 1964; Steunenberg et al., 1970). Melt refining is also named oxide slagging or oxide drossing. Fission products were removed by combining volatilization and selective oxidation. After the mechanical removal of cladding and sodium bonds, the separation process consisted simply in melting the fuel at 1300–1400 C in a lime‐stabilized zirconia crucible. Volatile fission products that are condensable, such as iodine and cesium, were trapped on alumina–silica fibers while gaseous fission products (krypton, xenon) were stored to allow decay of 5.3 day 133Xe before being released into the atmosphere. Elements more electropositive than zirconium (see Table 24.11: alkali metals, alkaline earth, and rare earth elements) reacted with the zirconia to form an insoluble oxide slag. The other fission products (noble metals comprising the fissium) and the actinides remained with the uranium in the metallic form to be recycled. At this stage, the uranium recovery yield ranged from 90 to 95 wt% (Trice and Chellew, 1961; Burris et al., 1964).

Fundamental features of actinide separation systems

2709

The melt refining process leaves a residue or skull (mixture of oxides and unpoured metal) at the bottom of the crucible, which represented about 5–10% of the loading. An auxiliary process had been proposed to recover uranium from the skull. After preliminary oxidation of the skull under oxygen–argon mixture at 700 C, the resulting oxides were dissolved into a chloride flux. Contact with liquid zinc between 700 and 800 C allowed the removal of noble metals (Ru, Mo, Rh, Pd) and Ag. Uranium was then extracted from the chloride flux by using Mg–Zn alloy (magnesium being the reducing agent and zinc the alloying agent). Combining this process with the melt refining increased the uranium recovery yield to about 99.5 wt%. The fission product removals that had been achieved (rare earths: 90%, Ru: 80%, Mo: 90%, Pd: >99%, Zr: 75%, Ba, and Sr: >99%) were sufficient to maintain the desired concentrations of the fissium alloying elements in the EBR‐II fuel (Burris et al., 1964). The complementary process, named the skull reclamation process, has been studied only at the laboratory scale (Burris et al., 1964; Steunenberg et al., 1970). Oxide slagging was also investigated for plutonium reactor fuels, for example with the proposed LAMPRE fuel (Los Alamos Molten Plutonium Reactor Experiment, 10 wt% Fe–Pu alloy) (Mullins et al., 1960). Tests on synthetic spent plutonium fuel have been performed in magnesia and zirconia crucibles. But this approach was rapidly abandoned because of numerous drawbacks: high temperature, slow reaction rates, and the creation of a plutonium‐bearing residue. (j)

Melt refining under molten salts (or halide slagging processes)

In the halide slagging process, in particular chloride slagging, the active fission products were rapidly removed from the molten fuel as a result of chemical reactions occurring at the interface between two liquid phases. Moreover, the plutonium transfer was less than 1 wt%. The process consisted of contacting the molten fuel at 600–700 C with molten alkali chloride salts containing plutonium chloride or magnesium chloride as an oxidant. Used slags were PuCl3–NaCl, MgCl2–LiCl—KCl, or MgCl2–NaCl–KCl (Leary et al., 1958; Mullins et al., 1960). Gibbs energies of formation of selected halides are shown in Table 24.12. Results were in agreement with thermodynamic predictions: electropositive fission products (alkali and alkaline earth elements, rare earths) were oxidized and dissolved in the chloride slag. But, as in every melt refining process, the noble metal fission products were not removed from the spent fuel. Mullins et al. (1960) gave for MgCl2–NaCl–KCl at 700 C the percentage transferred into the salt phase for the following elements: Pu 0.92, Fe 0.04, Zr < 0.04, Mo < 0.15, Ru < 0.20, Ce 98, La 100, Mg 26. In these experiments, the MgCl2 exceeded by 10% the stoichiometric quantity needed to remove the rare earths. A similar process has been tested on (10–20 wt% plutonium)–uranium alloys with BaCl2–CaCl2 and MgCl2 as oxidant (Glassner, 1957). The effect of the slag

Actinide separation science and technology

2710

Table 24.12 Gibbs energies of formationa of selected chlorides at 775 K. Compiled by Ackerman (1991) from Pankratz (1984) kJ (g atom Cl)–1. CsCl KCl SrCl2 LiCl NaCl LaCl3 PrCl3 a b

–367.4 –362.8 –354.4 –345.2 –339.3 –293.7 –288.7

CeCl3 NdCl3 YCl3 AmCl3 CmCl3 PuCl3 NpCl3

–287.0 –284.1 –272.4 –268b –268b –261.1b –242.7b

UCl3 ZrCl4 CdCl2 FeCl2 MoCl2 TcCl3

–231.0 –195.0 –135.1 –122.3 –70.3 –46

Recalculated from values in kcal (g atom Cl)–1. Estimated values.

composition is minor. The criteria for slag selection must be melting point and high stability of halide components (alkali or alkaline earth elements). (k)

Molten metal‐salt extraction processes

By combining liquid metal (or alloy) solvent with molten salts and using oxidation–reduction reactions, it is possible to accomplish separations that could not be achievable by melt refining. The elements are distributed in the two‐phase solvent system and the distribution coefficients depend on the nature of the oxidizing and reducing agents and on the activities of the reacting species in solution. In general, chlorides are preferred because of their lower volatility, their compatibility with many containers, and favorable solubility relationships. Such separation techniques in various biphasic systems have been proposed in the past by several American laboratories: Brookhaven National Laboratory investigated Bi/MgCl2–NaCl–KCl to reprocess bismuth–uranium fuel (Bennett et al., 1964); the Hanford Works studied the actinide distribution in Al/AlCl3– KCl (Dwyer, 1956); the Ames Laboratory examined the same in Zn/LiCl–KCl (Moore and Lyon, 1959); Los Alamos National Laboratory tested Hg/RbCl– LiCl–FeCl2 for the reprocessing of LAMPRE fuel (Chiotti and Parry, 1962); Argonne National Laboratory proposed various applications in MgCl2‐based salt with Cu–Mg or Zn–Mg alloy. One of them is the Argonne salt transport process for the reprocessing of LMFBR fuels (Steunenberg et al., 1970).

(i)

Argonne salt transport process

The partitioning of element M between magnesium alloy and MgCl2‐based salt can be expressed by: MðalloyÞ þ 12nMgCl2 ðsaltÞ ! MCln ðsaltÞ þ 12nMg ðalloyÞ

ð24:39Þ

If Ka is the equilibrium constant, ai and gi respectively the activity and the activity coefficient of the reactants, the distribution ratio DM for a metal M

Fundamental features of actinide separation systems

2711

(ratio of mole fraction of MCln in salt to atom fraction of M in alloy) will be expressed by: log DM ¼ ðDG =2:3RTÞ þ ð12n log aMg þ log gM Þ  ð12n log aMgCl2 þ log gMCln Þ

ð24:40Þ

where DG ¼  RT ln Ka ¼ DGf ðMCln ; TÞ  12nDGf ðMgCl2 ; TÞ. The first term in brackets in equation (24.40) depends on temperature via the Gibbs energy of formation of MCln and MgCl2. The second term depends on temperature and composition of the alloy while the third depends on temperature and composition of salt. Importance of these terms on DM decreases from left to right when salt with MgCl2 is used as the oxidizing agent (Bowersox and Leary, 1960). The halides of the noble‐metal fission products and the metals used for cladding (like Fe), have a less negative Gibbs energy of formation (see Table 24.12) the first term dominates the distribution ratio and they should be easily separated from actinides by remaining in the alloy. For actinides and rare earth elements, the two following terms cannot be ignored. Johnson (1974) has explained their effect on distribution coefficients. Distribution ratios of actinides and rare earth elements between molten MgCl2 and Mg-alloy (Mg–Zn, Mg–Cu) have been measured over a wide range of magnesium content (Knighton and Steunenberg, 1965; Knighton, 1969). They are at a minimum when a Zn–Mg alloy is used (Mg content is about 10 wt%). A similar effect is not observed when Cu–Mg alloy is used. These two alloys have been proposed by Argonne National Laboratory to separate uranium and plutonium from fission products. Salt transport separation is based on the selective transfer of uranium and plutonium from a donor alloy to an acceptor alloy via a saline phase (see Fig. 24.17): Puðdonor alloyÞ þ 32MgCl2 ðsaltÞ ! PuCl3 ðsaltÞ þ 32Mg ðdonor alloyÞ ð24:41Þ PuCl3 ðsaltÞ þ 32Mgðacceptor alloyÞ ! Puðacceptor alloyÞ þ 32MgCl2 ðsaltÞ ð24:42Þ When uranium and plutonium are salt‐transported from the donor alloy to the acceptor alloy, noble fission product metals remain in the donor alloy and rare earth fission product are stabilized in the salt phase. Using 50 mol% MgCl2–30 mol% NaCl–20 mol% KCl and Mg–44 at% Cu alloy at 650 C, the separation factor for Ce from Pu is about 1000. Typical phase compositions for plutonium recovery and purification are: for the donor alloy, Cu–33wt% Mg; for the salt, 50 mol% MgCl2–30 mol% NaCl– 20 mol% KCl; for the acceptor alloy, Zn–5 wt% Mg. The solubility of the transported material in the donor alloy must be high enough to have a significant transfer rate. For example, the solubility of uranium at 600 C in Cu–33 wt% Mg alloy is very low (50 ppm) while it can reach 3.8 wt% in

Actinide separation science and technology

2712

Fig. 24.17 Scheme of salt transport process for plutonium (Steunenberg et al., 1970).

Cu–6.5 wt% Mg alloy (Steunenberg et al., 1970). Salt transport process has been developed at the laboratory scale, but no full scale application has yet been developed, though it was proposed in the mid‐1990s in a conceptual flow sheet for recovering actinides from LWR fuels (Pierce et al., 1993; Johnson et al., 1994) (see Section 24.3.12n). (ii)

Other applications of molten salt‐metal extraction

Development of this separation technique in molten fluorides has been carried out largely at Oak Ridge National Laboratory, in support of the molten salt breeder reactor (MSBR) concept for the reprocessing of fuel based on molten LiF–BeF2 solutions (see Section 24.3.12c). In chlorides, molten salt‐metal extraction has been proposed for enhanced recovery of actinides from spent salt generated during electrorefining of metallic fuel (see Section 24.3.12.l). It has also been developed as one process stage for actinide recovery from HLLW coming from PUREX (see Section 24.3.12m(i)). (l)

Electrorefining

Early work on electrorefining from molten salts was done to prepare either high‐ purity metallic uranium or plutonium separately. It began with investigations on uranium at small scale (Driggs and Lilliendahl, 1930; Marzano and Noland, 1953), at larger scale (Anonymous, 1951; Chauvin et al., 1962, 1964), then with plutonium. A significant application is the recovery and purification of plutonium developed at Los Alamos National Laboratory (Mullins et al., 1962) and used at Rocky Flats, Hanford and in various countries (Moser and Navratil, 1983). There has been little research and development related to the application of electrorefining techniques to the recovery and purification of spent fuels.

Fundamental features of actinide separation systems

2713

Investigations on irradiated uranium (Chauvin et al., 1964) and on Los Alamos Molten Plutonium Reactor Experiment (LAMPRE) fuel (Leary et al., 1958) have been carried out. Interest in electrorefining was revived with the proposed advanced fast reactor concept called the integral fast reactor (IFR) (Burris, 1986; Till and Chang, 1988; Chang, 1989; Hannum, 1997) whose primary feature was an integral fuel cycle in which the core and blanket materials after discharging are to be processed and refabricated in an onsite facility. The fuel cycle was based on electrorefining with a molten salt electrolyte (LiCl–KCl–UCl3/PuCl3) at 500 C in an inert atmosphere. An abundant literature has appeared on the chemistry and technology of IFR (see in particular Burris et al., 1987; Willit et al., 1992; Hannum, 1997; Anonymous, 2000). In the discussion below, the following features of this system will be presented: (i) a brief description of the main steps of the pyro‐process; (ii) the chemical basis for partitioning of actinides and fission products between metallic (solid or liquid) and salt phases; and (iii) the separation efficiencies obtained at laboratory scale and in the only engineering scale application (EBR‐II spent fuel treatment demonstration) completed to date. (i) Reprocessing in the IFR fuel cycle After discharging the spent core fuel (alloy of U, Pu, and Zr) in its stainless cladding, the fuel is chopped and placed in an anode basket. The anode basket containing the chopped fuel is put into an electrorefiner containing molten LiCl–KCl electrolyte and a liquid cadmium pool under inert atmosphere. CdCl2 is added in the electrolyte to oxidize electropositive fission‐product metals (alkali, alkaline earths, and a large fraction of the rare earth metals) to their chlorides (see Table 24.12). The amount of oxidizing agent to be added is adjusted to maintain 2 mol% actinide chlorides in the salt phase. The basket is made anodic and the following sequence occurs: (i) nearly pure uranium is electro‐transported to a solid mandrel cathode and (ii) transuranium elements and some uranium are transferred by electro‐transport to a liquid cadmium cathode. Noble metal fission products remain in an unoxidized form and are removed from the basket with the cladding hulls, although some portion falls into the cadmium pool at the bottom of the electrolyzer. Electropositive fission products remain in the salt and build‐up during the successive reprocessing batches and progressively modify the electrochemical and physical properties of the electrolyte. Periodic treatment is thus required to remove them and recycle the electrolyte. The molten metal‐salt extraction (using Li–Cd alloys) has been proposed for reduction and removal of transuranium elements (TRUs) from the electrolyte salt and for TRU reoxidation back into the salt to start the next electrorefining campaign. Moreover, the use of UCl3 as oxidant makes it possible to avoid the introduction of cadmium in the electrorefiner and thus the lower cadmium pool can be eliminated. This approach avoids the deposition of cadmium and

2714

Actinide separation science and technology

makes easier the removal of solids that accumulate at the bottom of the electrolyzer. Both types of cathode products are processed to distill off adhering salt and cadmium (in case a liquid cadmium cathode is used). Such a process produces three waste streams: fission product gases, metal waste stream that contains cladding hulls, and noble metal fission products, and salt waste stream (alkali, alkaline earth fission products). The treatment, the immobilization, and the disposal of these wastes are challenging, but their discussion is not within the scope of this chapter. These features have largely evolved during the laboratory‐ scale and engineering‐scale developments depending on the applications. The lone large‐scale feedback is the demonstration campaign on the treatment of spent metal fuel from the EBR‐II fast reactor commenced in 1996 at the Argonne‐West site in Idaho. Processes and results obtained are discussed in reference Anonymous (2000). (ii)

Chemical basis of electro‐transport in LiCl–KCl

Johnson (1988) and Ackerman and coworkers (Ackerman, 1991, Tomczuk et al., 1992; Ackerman and Johnson, 1993) have described the chemistry that controls the electro‐transport in LiCl–KCl electrolyte on solid or liquid cathode. The transfer of the element of interest (for example U or Pu) is done by electrolyzing (electrochemical oxidation) this element into the salt (electrolyte) at the anode and electrodepositing it as metal at the cathode. The element must be initially present in the electrolyte before starting electrolysis. Dissolution is facilitated by addition of a chemical oxidizing agent (i.e. a chemical agent whose the chloride is less stable than the chloride of the element one wishes to electro‐ transport). For uranium electro‐transport, the oxidizing agent can be CdCl2 (see Table 24.12). In the electrorefiner, the salt is well stirred and is in contact with both metal (electrode) phases. When a predetermined number of moles of metal (of given composition) are removed from the anode to the cathode, the compositions of both electrodes and the salt change until the salt is in equilibrium. For both elements M and M0 , the following equilibrium exists at each electrode: n1ðMCln2 Þ þ n2ðM0 Þalloy ! n1ðMÞalloy þn2ðM0 Cln1 Þsalt

ð24:43Þ

Equilibrium constant Ka can be expressed using mole fraction xi and activity coefficient gi of M and M0 in metal phase(s) and salt by: n2

Ka ðTÞ ¼ ½ðgMÞn1 ðgM0 Cln1 Þn2 =½ðgM0 Þ ðgMCln2 Þn1 n2

½ðxMÞn1 ðxM0 Cln1 Þn2 =½ðxM0 Þ ðxMCln2 Þn1

ð24:44Þ

where DG ðTÞ ¼  RT ln Ka ðTÞ ¼ n2 DGf ðMCln1 ; TÞ  n1 DGf ðM0 Cln2 ; TÞ. By writing donor alloy ¼ anode and acceptor alloy ¼ cathode (Johnson, 1988), the equations are similar to those written for salt transport description

Fundamental features of actinide separation systems

2715

(see Section 24.3.12.k). The metal (electrode) phases need not to be in equilibrium with each other in the classical sense which would mean that activity of each metal would be the same in all phases (Anonymous, 1951; Tomczuk et al., 1992; Ackerman and Johnson, 1993). Concentrations in the salt phase at equilibrium depend on activity coefficients in metal phases (solid or liquid) and salt. As the salt is diluted, the activity coefficients of MCln2 and M0 Cln1 are assumed to be constant. However, activity coefficients of M and M0 in metal phases can vary greatly when changing the metal phase and they can be greatly reduced by the formation of intermetallic compounds. For instance, the plutonium activity is reduced in cadmium by formation of PuCd6 (Johnson et al., 1965). A similar decrease for rare earth activity coefficients is observed with Cd (Johnson and Yonco, 1970). Uranium does not form intermetallic compounds with cadmium at the electrorefining temperature (500 C) (Martin et al., 1961). A reduction in the activity coefficient of an element (e.g. Pu) is equivalent to a reduction in the stability of the corresponding chloride. In presence of cadmium, plutonium behaves as its trichloride was about 3.3 kJ (equiv.)–1 more stable than uranium trichloride whereas it is 30.1 kJ (equiv.)–1more stable in absence of cadmium (Ackerman, 1991, see Table 24.12). This result also implies that the difference between the reduction potential of Pu(III)/Pu(0) and U(III)/U(0) is less negative at the liquid cadmium cathode than at the solid cathode. Sakamura et al. (1999) have summarized the reduction potential of actinide and rare earth elements in LiCl–KCl salt when the nature of the cathode change (see Fig. 24.18). These data are compiled from the literature (Martin et al., 1961; Lebedev et al., 1968, 1969; Krumpelt et al., 1974; Ackerman and Johnson, 1993; Kurata et al., 1996; Kinoshita et al., 1999). The removal of pure uranium on a solid mandrel electrode is possible because the reduction potential of U(III)/U(0) is far from those of the other actinides (see Fig. 24.18). The range of PuCl3/UCl3 ratios in the electrolyte within which pure uranium can be removed at a solid cathode has been determined by Tomczuk et al. (1992). At a liquid cadmium cathode, the reduction potentials of actinides are very similar and such a cathode should be suitable for recovery of all actinides together. However, the potentials are too close to those of rare earth elements to be suitable for an actinide/rare earth separation. The gap between actinides and rare earth elements is increased if bismuth is substituted for cadmium. This change could enable an actinide/RE separation (see Section 24.3.12 m(i)). The principal drawback of bismuth as an electrode material (compared to cadmium) is that it is not distillable and therefore difficult to purify. (iii)

Separation efficiencies in EBR‐II demonstration campaign (2000)

From 1996 to 1999, a hot demonstration was conducted in the Fuel Conditioning Facility at Idaho Falls where 100 spent driver assemblies (410 kg of highly enriched uranium alloyed with 10 wt% Zr, plus stainless steel cladding) and

2716

Actinide separation science and technology

Fig. 24.18 Reduction potential of actinide and rare earth elements at solid cathode, liquid cadmium cathode, and liquid bismuth cathode in LiCl–KCl eutectic salt at 500 C, xM in salt ¼ xM in Cd ¼ xM in Bi ¼ 0.001. (Figure created from information in Sakamura et al., 1999.)

25 spent blanket assemblies (1200 kg of depleted‐uranium with stainless steel cladding) from the Experimental Breeder Reactor‐II have been treated by the electro metallurgical technology (EMT) developed by Argonne National Laboratory. The metallic fuel was separated into three components: metallic uranium, a metallic waste form from the anode, and a highly radioactive salt mixture. The global process involved the following steps: (i) chopping the fuel elements; (ii) electrorefining; (iii) removing entrained salt (about 20 wt%) from uranium deposits and consolidating dendritic deposits in a cathode processor; (iv) casting into ingots the uranium metal from the cathode; (v) casting into ingots the metal residue from the anode; and (vi) mixing, heating, and pressing the salt electrolyte with zeolite to form a ceramic waste. The core of the process is the electrorefining step in LiCl–KCl melt at 500 C: the metallic fuel is selectively dissolved at the anode while nearly pure uranium metal is deposited at the cathode, leaving fission products, fuel cladding material, plutonium, and other transuranium elements partially at the anode and partially in the molten salt. In addition, the process neutralizes the reactive components (e.g. sodium‐bonds) of the fuel. The distribution of actinides

Fundamental features of actinide separation systems

2717

(U, Np, and Pu) and some fission products in each flux has been calculated from material balance given by Mariani and coworkers (Anonymous, 2000; Mariani et al., 2000) for spent driver fuel treatment (Table 24.13). Two electrorefiners have been designed and developed. The first, Mark‐IV, was used for driver elements and contained a cadmium pool. This pool was not used as cathode but acted as neutron absorber and corrosion‐resistant barrier. CdCl2 was added into the electrolyte to oxidize some of the U and other active metals before starting electrotransport. The anode assembly (four baskets) could hold about 8 kg of uranium. An overall anode batch size of 16 kg was achieved by using dual anode assemblies with a single cathode. Steel scrapers were placed near the cathode to control the growth of the uranium dendritic deposit and to allow the removal of the deposit through the cathode port. During the demonstration campaign, Mark‐IV was used to treat 12 driver assemblies at an average rate of 24 kg of uranium per month over a 3‐month period. The second electrorefiner, Mark‐V, cadmium free, was used for blanket elements (large quantities of depleted uranium). The throughput has been increased by using anode–cathode modules (ACMs) with a capacity of 37 kg per ACM. The overall anode batch size was about 150 kg when four ACMs are used. Each ACM would be able to produce about 87–100 kg of uranium per month. During the demonstration campaign, Mark‐V was used to treat 4.3 blanket assemblies at an average rate of 206 kg of U per month over one month. (m)

Oxide–metal processes

A pyrometallurgical partitioning technology for the recovery of uranium and transuranium elements from high-level liquid waste (HLLW) has been developed by the Japanese Central Research Institute of Electric Power Industry (CRIEPI) (Inoue et al., 1991), as described below. (i) Recovery of actinides from denitrated HLLW The process begins with a denitration step in which dehydration by heating converts all the elements in water to insoluble oxides (except for alkali metals which are removed by rinsing with water). The resulted oxides are chlorinated in molten LiCl–KCl eutectic melt. Kurata et al. (2000) argue that Cr, Fe, Zr, Mo, and Te are separated during the chlorination step. This is followed by a set of reductive extraction steps. (ii)

Reductive extraction of noble metals

The purpose of the first reductive extraction is to remove as much of the noble metals as possible while carrying less than 0.1% of each actinide into the reductive extraction product. Extraction step is performed by adding Cd–Li alloy. Laboratory‐scale tests show that the amounts of neptunium, plutonium,

b

a

87.8 0.3

3.6 0.8

100

0

1.3

100

11.6 0.3

Pu

2.4 91.9

U

To be converted to metal waste form. To be converted to ceramic waste form.

cladding hulls uranium ingot for interim storage dross from cathode processor remaining in electrorefiner saltb remaining in electrorefiner hold‐up, cadmium pool and plenum sections total output

a

100

1.4

88.0

0

8.5 2.1

Np

100

3.5

88.4

0

8.1 Zr4þ > Ce4þ > 2 > PuO2 > Pu 3þ Ru(NO) . Like the REDOX and BiPO4 processes, BUTEX rejected neptunium and the transplutonium actinides to the waste stream. Because of several limitations including the high viscosity and density of the extractant, and the formation of crystalline uranyl nitrate–Butex compounds, this process was discontinued as more efficient processes emerged.

(d)

TLA process

Trilaurylamine (TLA, Structure z) is a highly specific extractant for Pu(IV) while the extration of U(VI) is very low. Thus the TLA process was suggested for a second‐stage plutonium recovery process (Auchapt et al., 1968). A solution of 7–20% TLA in diethylbenzene has been used to extract Pu from 1.25–3 M HNO3. Plutonium was stripped with 3–4 M acetic acid (Coleman, 1964). From a solution formed as zircaloy‐clad fuel element is dissolved in nitric acid, plutonium extraction has been shown to be highly effective by using 10% TLA in

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Actinide separation science and technology

t‐butylbenzene (Haeffner et al., 1965; Hultgren, 1967). With certain modifications, the TLA process has generated a Df Pu of 1.75  107 from uranium and of 8  107 from b and g activities.

(e)

PUREX process

The PUREX (originally Plutonium Uranium Extraction but also found in the literature as Plutonium Uranium Recovery by Extraction or Plutonium Uranium Reduction Extraction) process used TBP dissolved in an inert aliphatic diluent as the extractant for uranium and plutonium from dissolver solution (Anonymous, 1951, 1955; McKay, 1956; Cooper and Walling, 1958; Mathieson and Nicholson, 1968; Koch et al., 1977). Normally a solution of 20–30% TBP in n‐dodecane, odorless kerosene, or another normal (or branched) paraffinic hydrocarbon (or mixture of hydrocarbons) is used as the diluent. This process was first developed at the Oak Ridge National Laboratory (Flanary, 1954). It has been employed at the industrial scale for nearly 50 years and remains the cornerstone of nuclear fuel reprocessing for both defense and power reactor fuels around the world. One of the major advantages of this process is that it selectively extracts Pu(NO3)4 and UO2(NO3)2 from dissolved spent nuclear fuels from solutions of moderate nitric acid concentrations (2–3 M), requires no addition of any salts, and is plagued by few co‐extracted impurities. Both Pu(IV) and Pu(VI) are readily extracted into the organic phase, whereas Pu(III) extraction is comparable to that of americium (see Fig. 24.6). In the hexavalent state, the order of distribution ratio is U(VI) > Np(VI) > Pu(VI). Neptunium, normally maintained in the pentavalent oxidation state in PUREX processing, is extracted even less than the trivalent actinides. Neptunium redox chemistry in nitric acid solutions generally causes some more extractable neptunium species to be present, hence there is often ‘leakage’ of neptunium into undesirable process streams in a PUREX plant (Drake, 1990), as will be discussed further in Section 24.4.4f. As the detailed description of the PUREX flow sheet is given elsewhere, only the practical steps involved with this process are listed here: (1) Feed preparation – fuel is decladded and dissolved, nitric acid concentration is adjusted to 2–3 M and plutonium valency is adjusted to 4þ, most commonly with H2O2 or HNO2. (2) Co‐decontamination cycle – U(VI) and Pu(IV) are co‐extracted into the TBP phase leaving behind the fission products, trivalent actinides, and Np(V) in the aqueous raffinate.

Applications of separations in actinide science and technology

2733

(3) Partition cycle – Pu(IV) is reduced to Pu(III) using ferrous sulfamate, U(IV), or hydroxylamine, resulting in Pu(III) being stripped into the aqueous phase while uranium remains in the TBP phase; U(VI) is subsequently stripped with very dilute nitric acid solution; final cleanup of remaining traces of U(VI) occurs during extractant reconditioning with Na2CO3. (4) A second uranium and plutonium extraction cycle follows step (3) for both the aqueous phases separately after feed adjustments to improve recovery. (5) Final purification of plutonium is done in modern PUREX plants using additional TBP solvent extraction steps. Historically, pure plutonium has been prepared using anion exchange chromatography, as follows: the feed is adjusted to 7.1 M HNO3 and the plutonium anionic species PuðNO3 Þ2 6 is adsorbed strongly onto the column; remaining contaminants like U, Zr– Nb, Ru, and Fe are not adsorbed; after adequate washings, plutonium is eluted from the anion exchange resin with 0.5 M nitric acid. The improved PUREX (IMPUREX) process operated at temperatures higher than 50 C suggests several advantages such as prevention of plutonium accumulation in the extractors, improvement in fission products and neptunium separations, etc. (Schmeider and Petrich, 1989) and is worth considering. All of the processes mentioned above, particularly PUREX, have been operated on a production scale. However, none of these processes can be used to separate and recover trivalent actinides or Np(V) neither from HLW solutions nor from various TRU containing waste solutions, which are often moderately concentrated nitric acid solutions (2–4 M). TBP can be employed to extract trivalent actinides (as was indicated in the work of Sekine, 1965, discussed in Section 24.3.4), but only with the reduction of acidity of the aqueous stream and addition of salting out agents. Diluting the HLW solutions, decreasing the acidity by denitration, or partial neutralization to obtain dilute acid salt solutions will increase the volumes of by‐product wastes and increase the difficulty of their disposal. If the so‐called minor actinides are to be transmuted, there clearly is a need for developing full‐fledged processes for recovery of these minor actinides from HLW and TRU wastes.

(f)

THOREX process

In the 1960s and 1970s, great interest developed in the thorium fuel cycle as a supplement to limited uranium reserves. The slightly harder neutron spectrum of heavy water and gas‐cooled/graphite‐moderated reactors make such reactors reasonable centerpieces of a uranium–thorium breeder reactor cycle, though it has been shown that thorium can be used practically in any type of existing reactor. For example, Stewart et al. (1971) have described a thorium–uranium breeder fuel cycle designed around the now‐decommissioned Fort St. Vrain gas‐ cooled reactor. Molten salt reactors have a similar favorable neutron spectrum

2734

Actinide separation science and technology

for this fuel cycle. These initiatives have been virtually brought to a halt for various reasons, except in India, where research has continued with its exploration of the thorium–uranium fuel cycle (Lung and Gremm, 1998). The initial 233U to operate this fuel cycle must be produced in a 235U‐fueled reactor, or with an initial 235U or 239Pu charge surrounded by a 232Th breeding blanket. Two fundamental limitations of the U–Th fuel cycle are the creation of 228 Th (t1/2 ¼ 1.912 years, 5.42 MeV a) and 232U (t1/2 ¼ 68.9 years, 5.32 MeV a) and their daughters as by‐products, and the creation of 233Pa (t1/2 ¼ 27 days, 0.3 MeV g, 0.6 MeV b) as parent of the desired 233U product. The build‐up of isotopic contaminants during successive irradiations of recycled 233U–Th fuels can greatly affect the handling procedures used in fuel‐element refabrication. Reactor‐fuel elements containing 233U may be fabricated semi‐remotely provided that complete fabrication can be accomplished in 2 weeks or less. If 233 U contains more than 200 ppm 232U, or if refabrication of fuel elements requires longer than 2 weeks, a shielded refabrication facility is necessary. Thorium fuels must be allowed to decay for 12 years if unshielded refabrication procedures are to be used (Arnold, 1962; Schlosser and Behrens, 1967). The fuel cycle has been advocated as non‐proliferating on the basis of the presence of 232 U isotope and the energetic g activity of its 208Tl and 212Bi daughters (Ragheb and Maynard, 1980). Another significant advantage of this fuel cycle is the reduced production of long‐lived transuranium actinides. Several approaches to fuel dissolution have been developed for this fuel cycle dependent in part on the reactor type used to breed 233U. The oxide fuel and the breeding blanket used for gas‐cooled reactor fuels are imbedded in a graphite matrix. In this cycle, the spent fuel is crushed and the carbon typically burned out prior to fuel reprocessing. Stainless steel cladding from water‐moderated reactors is easily dissolved with 4–6 M H2SO4 (Sulfex process) or 5 M HNO3–2M HCl (Darex process) in low‐carbon nickel alloy or titanium equipment, respectively. Uranium losses to the decladding solutions are readily recovered from the Darex decladding solutions in the acid THOREX extraction process. The ThO2–UO2 core can be dissolved in 13 M HNO3–0.04 M NaF–0.1 M Al(NO3)3. Uranium and thorium can be recovered from graphite‐based fuels by: (a) disintegration and leaching with 90% HNO3; (b) grinding and leaching with 70% HNO3; or (c) combustion followed by dissolution in fluoride‐catalyzed HNO3 (Blanco et al., 1962). Irradiated Al‐clad Th metal slugs are dissolved in HNO3 containing Hg2þ and F– as catalysts (Bruce, 1957). The separation of thorium from uranium is most typically accomplished using the same basic chemistry that drives the PUREX process, i.e. extraction of Th(IV) and U(VI) from nitric acid solutions into TBP solutions with aliphatic hydrocarbon diluents. The use of an acid‐deficient feed (0.15 M) induces high decontamination while injection of HNO3 at the fourth extraction stage provides high salting strength and insures quantitative uranium and thorium extraction. Because thorium is extracted by TBP less effectively than Pu(IV) or

Applications of separations in actinide science and technology

2735

U(VI), the introduction of Al(NO3)3 (Oliver, 1958) or Be(NO3)2 (Farrell et al., 1962) as salting out reagent has been demonstrated. In the acid THOREX process, three solvent extraction cycles are used. In the first cycle, uranium and thorium are extracted away from most fission products by 30% TBP from 5 M HNO3. Both are stripped into a dilute acid phase. In the second cycle, acid conditions are controlled for selective extraction of uranium while thorium remains in the aqueous raffinate. The extracted uranium is further purified by solvent extraction or ion exchange while the thorium is concentrated and stored for recycle. The processing of short‐cooled thorium metal results in the collection of a first cycle extraction column raffinate that contains 20–30% of the mass 233 as 233 Pa. Ultimate recovery of 233U requires storage of the raffinate for decay of 233 Pa. During a THOREX pilot plant short‐cooled scouting run, an estimated 27 g of 233Pa was collected and stored as extraction column raffinate. A one‐ cycle solvent extraction flow sheet was used to separate 233U from fission products and other contaminants contained in the raffinate. 233U was extracted into 6% TBP in Amsco 125–82 and subsequently stripped into dilute HNO3 (McDuffee and Yarbro, 1957, 1958). Five thorium processing campaigns were conducted at the Savannah River Plant. Two different flow sheets were used and a total of about 240 metric tons of thorium and 580 kg of uranium was processed. In the first two campaigns on thorium oxide, uranium was recovered with a dilute 3.5% TBP flow sheet and the thorium was sent to waste. 232U concentrations in these two campaigns were 40–50 ppm and 200 ppm. In the third campaign, thorium metal and thorium oxide were processed. ThO2 was processed in the final two THOREX campaigns. The three THOREX campaigns used 30% TBP to recover both uranium and thorium. Irradiation conditions were set to produce a concentration of 4–7 ppm 232U. Dissolving rates for thorium metal exceeded 4 metric tons per day and with thorium sent to waste, solvent extraction rates increased, and posed no limits. When Th oxide feed was used dissolving and THOREX solvent extraction rates were 1 metric ton per day. Satisfactory flow sheets were developed, losses were acceptable, and decontamination from fission products and Pa were adequate. Th–DBP precipitates did appear in the second Th cycle during the first THOREX campaign (Orth, 1978). Rainey and Moore (1962) demonstrated a laboratory‐scale THOREX separation in which good decontamination factors were obtained, and U and Th losses were less than 0.01 and 0.3%. Watson and Rainey (1979a,b) have demonstrated a THOREX computer code. When the fuel being irradiated contains appreciable amount of 238U, the plutonium thus formed requires that a combination of the THOREX and PUREX processes must be applied. The THOREX process is technologically less advanced and principally hindered by the much lower distribution coefficient of Th nitrate relative to uranium and plutonium. To drive thorium into the

2736

Actinide separation science and technology

TBP phase, a strong salting agent is required. Aluminum nitrate is replaced by nitric acid to reduce the amount of radioactive waste. However, high acid concentrations are counter‐effective in achieving high fission product decontamination. Therefore, several flow sheet variants with acid and acid‐deficient feed solutions, respectively, have been investigated (Merz and Zimmer, 1984). To achieve high decontamination factors, a dual cycle THOREX process was developed. This process uses an acid feed solution in the first cycle and an acid‐deficient feed in the second cycle. An immediate separation of thorium and uranium appears advisable in view of both fuel cycle strategy and process feasibility. To test the separation of thorium, uranium, and plutonium from each other, Grant et al. (1980) developed a modified THOREX solvent extraction flow sheet using 30% TBP. Not surprisingly, the inclusion of plutonium in the fuel cycle increases complexity. The first and second stages are used as a decontamination cycle to remove most of the fission products from the actinides. After intermediate concentration and adjustment of plutonium valency [to Pu(III)], the next three stages comprise the primary separation system and are used to recover Pu(III), Th, and 233U separately. Finally, several alternative extractants and even extractant types have also been suggested as a means of separating 233U from irradiated thorium. To overcome the comparatively weak extraction of Th by TBP, Siddall (1958, 1963b) suggests that diamyl(amyl)phosphonate (DAAP) should be considered as a replacement for TBP in Th processing. The separation factor between thorium and zirconium is at least ten times greater with DAAP than with TBP. A high degree of complexing of DAAP by thorium occurs even in dilute HNO3. This extractant is also less prone to third phase formation. The extraction behavior of 1 M solutions of tri‐2‐ethylhexyl phosphate (TEHP), di‐2‐ethylhexyl isobutyramide (D2EHIBA), and di‐n‐hexyl hexanamide (DHHA) in n‐dodecane towards U(VI), Th(IV), and Pa(V) in the presence of 220 g L–1 of thorium from nitric acid medium also has been studied (Pathak et al., 2000). Separation factors for U(VI) over Th(IV) consistently varied in the order: D2EHIBA > DHHA > TEHP > TBP under most conditions. The quantitative extraction of 233U from a synthetic mixture containing 233 U(10–5 M), 233Pa (10–11 M), and thorium (220 g L–1) at 1 M HNO3 using a 1 M solution of D2EHIBA in n‐dodecane is achieved in three stages. Detailed studies on the processing of irradiated thorium using an amine solvent at pilot plant scale have been reported (Awwal, 1971). In this process, the 233U and thorium are coextracted with 0.1 M methyldidecylamine from a feed solution of 5.8 g Th L–1 having 2.5  10–3 M H2SO4. The extracted thorium is selectively stripped with 1M H2SO4 and 233U is stripped with 0.5 M HNO3. The final product is purified by anion exchange. The decontamination factor from fission products for 233U and thorium are 3.2  104, 3.8  104, respectively, for the single cycle solvent extraction process. The separation factor of 233U from thorium is 2  104.

Applications of separations in actinide science and technology 24.4.4

2737

Actinide production processes at the design and pilot stages

During the last two decades, concerted and mission‐oriented research conducted around the world has identified a number of promising extractant systems for actinide separations using solvent extraction, extraction chromatography, supported liquid membrane, magnetically assisted chemical separations, or pyro‐reprocessing. The pyrometallurgical options have been discussed in Section 24.3.12. Plant‐scale demonstrations are yet to occur, partly because of materials/corrosion issues. Most aspects of separations in the IFR project have been demonstrated at the pilot scale. In the following discussion, the performance of the new extraction systems that have been developed for actinide partitioning will be compared. Many of the new extractant systems under development are based on bifunctional (or multifunctional) reagents, whose unique nature will become apparent in the discussion to follow. The chemical features of many of these systems have been considered above (see Section 24.3.4b). The emphasis in this section will be more on the status of process development. The reader is referred to the cited literature for detailed information on the chemistry of the extraction systems.

(a) Dihexyl‐N,N‐diethylcarbamoylmethylphosphonate (DHDECMP or CMP) Navratil and coworkers (Martella and Navratil, 1979; Navratil and Thompson, 1979) conducted a preliminary feasibility study for separation of actinides from synthetic acidified waste solutions likely to be produced during nuclear fuel fabrication and reprocessing. The initial solution contained large quantities of Na2CO3, Na3PO4, NaCl, Na2SO4, and the actinides, plutonium, americium, and uranium. A first contact with 30% TBP/n‐dodecane removed more than 99.99% of uranium and most of the plutonium. The aqueous raffinate was then contacted with 20–30% CMP/CCl4 which removed more than 99.91% of americium and all the residual plutonium and other actinides. Rapko and Lumetta (1994) have reported the extraction of U(VI), Pu(IV), Am (III), and important competing metal ions (e.g. Fe(III), Zr(IV), Bi(III)) from HNO3 solutions using a mixture of CMP (0.75 M) and TBP (1.05 M) in an aliphatic diluent [normal paraffinic hydrocarbon (NPH) or isoparaffinic hydrocarbon (ISOPAR)]. Above 2M HNO3, this organic phase splits into heavy and light fractions (third phase formation) even in the presence of 1 M TBP. Adjustment to about 2.0 M NaNO3 is indicated as necessary to prevent third phase formation. At about 2 M ðHNO3 ; NO 3 Þ in the absence of any aqueous complexing agent, a distribution ratio DAm of about 5 is reasonably good. Though 0.1 M HF has no effect on DAm, 0.05 M oxalic acid decreases DAm to about 1. Salting out with NaNO3 increased this value. DPu at radiotracer concentrations and DU at 0.05 M ( 12 g L1 total uranium) have been reported. DAm decreases in the presence of such moderate concentrations of uranium, presumably as a

2738

Actinide separation science and technology

result of the tying up of the free extractant by the macroscopic quantities of uranium present. Degradation products and acidic impurities in the CMP extractant can inhibit stripping of plutonium and uranium. The increased volume of wastes in all categories that would result from the introduction of a salting‐out reagent required to maintain extraction efficiency and phase compatibility is a significant drawback to the application of this class of reagents. (b) Octyl(phenyl)‐N,N‐di‐isobutylcarbamoylmethylphosphine oxide (OfDiBCMPO or CMPO) To overcome the comparative weakness of the CMP‐class extractants, structurally similar extractants containing the phosphine oxide functional group were prepared. Compounds with different substituents at the phosphoryl group and the amide nitrogen have been synthesized (Kalina et al., 1981a; Chmutova et al., 1983) and studied for extraction of transplutonium metal ions. Alterations have also been made at the bridge between the P¼O and C¼O groups (Rapko, 1995). Two detailed papers describe the synthesis and purification (Gatrone et al., 1987) and the spectral properties of the carbamoylmethylphosphine oxides (Gatrone and Rickert, 1987). The extraction behavior of mainly trivalent actinides, lanthanides, and a few other metal ions has been studied with all the reagents synthesized in this class. Actinide extraction properties and phase compatibility varied significantly with the nature of the alkyl substituents on the carbamoylmethylphosphine oxide core. Of the compounds investigated, OFCMPO was found to possess the best combination of properties for actinide extraction in a PUREX‐compatible diluent system. The CMPO‐type compounds have received the greatest attention of all potential actinide partitioning reagents developed over the past 20 years and as a result represent the best‐understood hydrometallurgical reagents for total actinide partitioning from wastes. Numerous investigations have attempted to demonstrate quantitative phase transfer of americium from HNO3 or HCl solutions by CMPO into diluents like diethylbenzene, CCl4, C2Cl4, and paraffinic hydrocarbons (Horwitz et al., 1981, 1983, 1986; Kalina et al., 1981a; Horwitz and Kalina, 1984). Extraction of Eu(III) from HNO3 or HCl with CMPO alone or a mixture of CMPO and TBP in mesitylene or n‐dodecane has been reported (Liansheng et al., 1990) as has the extraction of neptunium and plutonium (Kolarik and Horwitz, 1988; Mincher, 1989; Nagasaki et al., 1992) and Pm, U, Pu, Am, Zr, Ru, Fe, and Pd (Mathur et al., 1992b) from HNO3 into a mixture of CMPO and TBP in n‐dodecane. Basic studies of CMPO have reported its activity coefficients (Diamond et al., 1986), complexes formed with trivalent actinides and lanthanides (Mincher, 1992), electrochemistry of Ce(III) nitrate complex (Jiang et al., 1994), and numerical modeling to predict operations in the TRUEX process (Regalbuto et al., 1992; Vandegrift et al., 1993; Vandegrift and Regalbuto, 1995) and for co‐extraction of Tc(VII) with U(VI) (Takeuchi et al., 1995).

Applications of separations in actinide science and technology

2739

The now well‐known TRUEX process for the recovery of all the actinides from various types of highly acidic nuclear waste solutions is based on CMPO as the principal extractant. The TRUEX process solvent is 0.2–0.25 M CMPO þ 1.0–1.4 M TBP in paraffinic hydrocarbon (linear or branched, though the process has been demonstrated in chlorinated diluents as well) (Vandegrift et al., 1984; Horwitz et al., 1985; Schulz and Horwitz, 1988; Horwitz and Schulz, 1990; Mathur and Nash, 1998; Suresh et al., 2001). TBP hinders third‐phase formation, contributes to better acid dependencies for DAm, improves phase compatibility, and reduces hydrolytic and radiolytic degradation of CMPO. The basic actinide solvent extraction chemistry of TRUEX has been discussed in Sections 24.3.4b and 24.3.5. The ability to efficiently extract trivalent, tetravalent, and hexavalent actinides from solutions of moderate acid concentration and with good selectivity over most fission products (except lanthanides) is a key feature of this extractant. From an engineering perspective, the more‐ or‐less constant D values of Pu(IV), U(VI), and Am(III) between about 1 and 6 M HNO3 is important, as it allows efficient extraction of actinides from wastes or dissolved fuels with little or no need to adjust the acidity of the feed solution. This particular feature of TRUEX distinguishes this extraction system from other methods for TRU isolation. A sufficient volume of process‐relevant thermodynamic data on CMPO extraction chemistry has been developed to support the existence of a computational model, the generic TRUEX model (GTM) that can be used to predict system performance over a wide range of conditions (Regalbuto et al., 1992; Vandegrift et al., 1993; Vandegrift and Regalbuto, 1995). Russian chemists have independently developed a TRU extraction process based on a somewhat simpler (thus, less expensive) derivative of CMPO (diphenyl‐N,N‐di‐n‐butyl CMPO, DFDBuCMPO) employing a fluoroether diluent (Fluoropol‐732) (Myasoedov et al., 1993). This process behaves similarly to the TRUEX process in terms of its efficiency for actinide extraction, shows little tendency toward third‐phase formation, and avoids the interferences caused by degradation of TBP. It has been tested in centrifugal contactors and found to recover actinides with greater than 99.5% efficiency. The corrosive nature of aqueous effluents derived from degraded solvent (i.e. containing HF) is a potential drawback for this process. Continuing exploration of this extractant has suggested a universal solvent extraction (UNEX) process for the separation of cesium, strontium, and the actinides from nitric acid solutions and from actual acidic radioactive waste solutions (Law et al., 2001, 2002; Romanovskiy et al., 2001a,b, 2002; Herbst et al., 2002, 2003; Romanovskiy, 2002a,b; Todd et al., 2003). The composition of the UNEX solvent is 0.08 M chlorinated cobalt dicarbollide, 0.5 vol.% polyethylene glycol‐400 (PEG‐400) and 0.02 M DFDBuCMPO in a phenyltrifluoromethyl sulfone (FS‐13) diluent. Cobalt dicarbollide ½CoðB9 C2 H8 Cl3 Þ 2 is a lipophilic substitution‐inert Co(III) complex that exhibits significant affinity for Csþ. Using the Idaho National Engineering and Environmental Laboratory

2740

Actinide separation science and technology

(INEEL) tank waste, removal efficiencies of 99.4, 99.995, and 99.96% for 137Cs, 90 Sr, and the actinides, respectively, have been demonstrated. Possible limitations of the process include corrosive products of diluent degradation (e.g. HF), difficult back extraction due to the requirement of very low acidity for low DAm, and possibly complex solvent cleanup prior to recycle of the extractant (Horwitz and Schulz, 1999). (i)

TRUEX demonstrations with HLW and simulants

Decontamination of four types of actinide‐bearing wastes (or waste simulants) from the Hanford site, plutonium finishing plant (PFP), complexant concentrate (CC), neutralized cladding removal waste (NCRW), and single‐shell tank (SST) waste have been the subject of either bench‐scale experiments or pilot‐scale demonstrations using TRUEX with results as follows:
The removal of americium and plutonium from the plutonium finishing

plant (PFP) aqueous acidic waste [HNO3/Al(NO3)3 at 3 M total nitrate with 0.09 M HF, 0–0.2 M U, 10–5 to 10–4 M Pu, 10–6 to 10–5 M Am, less than 6  10–4 M Be, Cr, Ni, Zn, Pb] was accomplished using the TRUEX solvent (0.25 M CMPO, 0.75 M TBP in C2Cl4). The first two highly successful counter‐current runs with actual PFP waste employed a cross‐flow microfilter unit to remove finely divided solids and 4 cm diameter centrifugal contactor equipment for the solvent extraction of TRU elements. Duplicate runs were completed with 10 L of the clarified waste in about 40 min. The a‐activity of the aqueous raffinate was 1–2 nCi · g–1 and a TRU Df of 104 was obtained. A generic flow sheet of the TRUEX process for the removal of americium and plutonium from PFP waste is given in Fig. 24.20. A larger‐scale demonstration using a 20‐stage centrifugal contactor configuration achieved a‐decontamination factors up to 6.5  104 (Chamberlain et al., 1997).
The CC waste is alkaline and contains high concentrations of Naþ ; NO 3;  2 NO ; AlðOHÞ ; CO , organic complexants (EDTA, HEDTA, citric acid, 2 3 4 and their radiolytic and hydrolytic degradation products), and moderate concentrations of Csþ and Sr2þ. After acidification, bench‐scale batch extraction tests with synthetic and actual CC waste demonstrated that the Df TRU was on the order of 102 (Schulz and Horwitz, 1988). The TRU concentration in the effluent was 1 nCi g–1.
NCRW consists of solids (principally ZrO2 · xH2O) generated while treating Zircaloy‐clad fuels. It contains moderate amounts of TRU elements. A preliminary test with actual NCRW dissolved in HNO3 or HNO3–HF solutions using the TRUEX solvent was reported to result in satisfactory uptake of the actinides (Schulz and Horwitz, 1988). At the Pacific Northwest National Laboratory (PNNL), highly encouraging results have been reported for actinide removal by TRUEX treatment of NCRW sludge and of PFP sludge (Swanson, 1991a–c; Lumetta and Swanson, 1993a–c).

Applications of separations in actinide science and technology

Fig. 24.20 wastes.

2741

Generic flow sheet for TRUEX processing of plutonium finishing plant (PFP)


SST waste, a mixture of solid salt cake (e.g. water-soluble sodium salts),

solid sludge [primarily hydrated Fe(III) oxide], and a small volume of interstitial liquid containing TRU elements, can also be treated and TRU removed from the acidic solutions, as has been demonstrated using TRUEX on simulated dissolved sludge waste (Schulz and Horwitz, 1988). The most extensive pilot‐scale testing of the TRUEX process has been done at the Idaho National Engineering and Environmental Laboratory under the auspices of the Lockheed Martin Idaho Technologies Co. Several TRUEX demonstration runs have been made on sodium-bearing wastes (Law et al., 1998), a secondary acidic HLW. An optimized TRUEX flow sheet was tested in shielded hot cells at the Idaho Chemical Processing Plant (ICPP) Remote Analytical Laboratory using a 20‐stage bank of 2 cm centrifugal contactors. Stripping of actinides from the loaded process solvent was accomplished with 99.79% efficiency (99.84% for Am, 99.97% for Pu, 99.80% for U) using 1‐hydroxyethane‐1,1‐diphosphonic acid (HEDPA) as the stripping agent. A second demonstration using a dissolved zirconium calcine feed recovered 99.2% of Am (Law et al., 1998). In this case, the HEDPA stripping was less efficient due to problems created by precipitation of zirconium phosphate. The phosphate is believed to be present as an impurity in the HEDPA solution.

Actinide separation science and technology

2742

Literature reports indicate that such impurities are readily removed by recrystallization of HEDPA from glacial acetic acid (Nash and Horwitz, 1990). The radiolytic stability of this reagent has not been tested, but it is stable in acidic aqueous solutions. At the Los Alamos National Laboratory (LANL) substantial amounts of waste chloride salts containing moderate concentrations of Pu and Am are generated. These salts, dissolved in HCl, can serve as feed for the separation of actinides using high concentration of CMPO (0.5 M) in C2Cl4. If the feed contains large amounts of metal ion impurities that are appreciably extracted by CMPO [e.g. U(VI)], a preceding solvent extraction process employing TBP, TOPO, quaternary ammonium compounds, or some other process must be applied. The D values of Th(IV), U(VI), Np(IV), Pu(IV), and Am(III) at varying HCl concentrations in contact with 0.5 M CMPO in tetrachloroethylene have been reported previously (Horwitz et al., 1987). Initial counter‐current studies using TRUEX solvent indicated the need for moderate chloride ion concentration in the feed solution for satisfactory extraction of plutonium and americium (Schulz and Horwitz, 1988). Flow sheet for the generic TRUEX process for the removal of actinides from aqueous chloride solutions is given in Fig. 24.21.

Fig. 24.21

Generic flow sheet for TRUEX processing of chloride wastes.

Applications of separations in actinide science and technology

2743

In the European Community R&D program on the management and disposal of radioactive wastes, the Fuel Cycle Dept. ENEA, Rome, Italy, reported that the mixture of TBP and CMPO in chlorinated or aliphatic hydrocarbons achieves a very high Df for actinides. Batch and counter‐current extraction experiments were performed with MOX fabrication liquid wastes. Only batch studies were conducted with simulated solutions of aluminum MTR CANDU high‐level wastes of the EUREX reprocessing plant and with analytical wastes from control laboratories of a MOX fabrication plant. Very high Df values for actinides were obtained without requiring any salting agents and in the presence of many potentially complexing anions (Casarci et al., 1988, 1989). At Japan’s Power Reactor and Nuclear Fuel Development Corporation (PNC), batch and counter‐current runs with real high‐active raffinate from FBR spent fuel reprocessing have been carried out without adjusting acidity, using 0.2 M CMPO þ 1.2 M TBP in n‐dodecane. The mixer–settler employed in this study had 19 stages for extraction‐scrubbing and 16 stages for stripping. The rare earths were extracted along with actinides and some fraction of ruthenium. The Df for actinides was greater than 103. Oxalic acid was added in the feed and scrubbing solutions to improve ruthenium decontamination and effectively lower the D values of zirconium and molybdenum (Ozawa et al., 1992). In another communication from the same laboratory, Ozawa et al. (1998) suggested improvements in the TRUEX process flow sheet, specifically, increasing the acidity of the feed to about 5 M to improve Ru decontamination in the actinide fraction, and using salt‐free reagents like hydrazine oxalate, hydrazine carbonate, and tetramethylammonium hydroxide for stripping and cleanup steps to obtain a final raffinate that is a‐inactive and salt‐free. The improved TRUEX flow sheet utilized at PNC is given in Fig. 24.22. A numerical simulation code for the TRUEX process has been developed to determine the optimum operational conditions for the separation and recovery of TRU elements (Takanashi et al., 2000). With a view to minimize radioactive organic/inorganic waste released from TRUEX process, the electro‐redox technique and mediatory electrochemical oxidation using Ag(II)/Ag(I) or Co(III)/Co(II) couples have shown great promise (Ozawa et al., 2000). At the Bhabha Atomic Research Centre in India, basic data were generated for the extraction of actinides and a few fission and corrosion products using TRUEX solvent (0.2 M CMPO þ 1.2 M TBP in n‐dodecane) (Mathur et al., 1992b). Subsequent studies examined the extraction and separation of actinides from synthetic and actual high‐level aqueous raffinate waste (HAW), sulfate‐bearing high‐level waste solutions (SBHLW) at low acidity of about 0.3 M, non‐sulfate wastes originating from pressurized heavy water reactor (PHWR), and fast breeder reactor (FBR) both in about 3 M HNO3, and actual HLW solutions generated from the reprocessing of research reactor fuels at this center. In each study, the compositions of the synthetic waste solutions were reported (Deshingkar et al., 1993, 1994; Mathur et al., 1993a, 1995, 1996a; Gopalakrishnan et al., 1995). The results of batch studies on actual waste solutions are given below:

2744

Actinide separation science and technology

Fig. 24.22 Generic TRUEX flow sheet for actinide partitioning at JNC.

M CMPO þ 1.2 M TBP in n‐dodecane in 1:1 ratio. After two contacts, 99.8% of the a‐activity was found in the organic phase. The rare earths (Ce, Pm, Eu, etc.) followed americium, and ruthenium was partially extracted while cesium and strontium were not (Mathur et al., 1993a).
For extraction of HLW, the feed contains at least ten times higher concentration of uranium, fission and corrosion products than those in HAW. Therefore, one contact with 30% TBP/n‐dodecane was made to deplete the uranium content. After this, four contacts were made with 0.2 M CMPO þ 1.4 M TBP. The raffinate was found to contain 0.06% of the total a‐activity (Mathur et al., 1993a).


Unmodified HAW was contacted twice with fresh lots of 0.2

Applications of separations in actinide science and technology

2745


With SBHLW, two contacts were made with 30% TBP followed by

four contacts with 0.2 M CMPO þ 1.2 M TBP in n‐dodecane. Even at the low acidity of 0.3 M and 0.16 M SO2 4 , about 99.6% of the total a‐activity was removed from the HLW solutions (Gopalakrishnan et al., 1995). Mixer–settler experiments employing a six‐stage unit with synthetic SB‐ and PHWR‐HLW have been reported. After pretreatment with 30% TBP to reduce the concentrations of uranium, neptunium, and plutonium, the raffinate containing the remaining uranium, neptunium, and plutonium and the trivalent actinides and lanthanides (at total acidity of about 3 M) was the feed for a subsequent mixer–settler experiment using 0.2 M CMPO þ 1.2 M TBP in n‐dodecane. In all cases, the HLW raffinate leaving the extraction section showed a‐activity near background level. Final analysis indicated that nearly 99.7% of the rare earths are extracted along with the actinides and with about 30% of the ruthenium (Deshingkar et al., 1993, 1994; Chitnis et al., 1998b). The combined flow sheet using 30% TBP and the TRUEX solvent (Fig. 24.23) has been tested with actual HAW solutions generated from the reprocessing of research reactor fuels. In the first step, with 30% TBP U, Np, and Pu were recovered from HAW and then minor actinides left in the raffinate were extracted with the TRUEX solvent in the second step. Plutonium and neptunium extracted in TBP were stripped together using a mixture of H2O2 and ascorbic acid in 2 M HNO3 and later uranium was stripped from the TBP phase with dilute HNO3. Actinides extracted in TRUEX solvent were stripped together using a mixture of formic acid, hydrazine hydrate, and citric acid. The final raffinate analysis showed no alpha activity (Chitnis et al., 2000).

(ii)

Recovery of Pu from oxalate supernatant

The solutions resulting from Pu oxalate precipitation (oxalate supernatants) are among the final liquid waste streams in conventional PUREX processing. This waste typically contains 30 mg L–1of plutonium in 3 M HNO3 and about 0.1 M oxalic acid. TRUEX solvent has proven highly efficient for almost quantitative recovery of plutonium from such a solution in batch solvent extraction studies. Plutonium is stripped from the loaded CMPO phase by 0.5 M acetic acid or by a mixture of oxalic acid, calcium nitrate, and sodium nitrite (Mathur et al., 1994). Plutonium also could be recovered from such solutions utilizing the extraction chromatographic technique in which CMPO adsorbed on Chromosorb‐102 (CAC) was used for batch and column studies (Mathur et al., 1993b). When the oxalate supernatant contained large amounts of uranium (10–12 g L–1) along with plutonium, a TBP extraction step followed by TRUEX process solvent step has recovered uranium and plutonium almost quantitatively (Michael et al., 2000).

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Actinide separation science and technology

Fig. 24.23 Generic TRUEX flow sheet for actinide partitioning at BARC.

(iii)

Stripping of actinides from TRUEX solvent

Oxidation state‐specific stripping of actinides from loaded TRUEX solvent can be done in three steps: 0.04 M HNO3 to remove trivalent actinides, dilute HNO3–HF mixture (0.05M each), or dilute oxalic acid for selective stripping of tetravalent actinides, and 0.25 M Na2CO3 for uranium recovery (and simultaneous reconditioning of solvent for recycle). Horwitz and Schulz (1990)

Applications of separations in actinide science and technology

2747

recommend that a solution of either vinylidene‐1,1‐diphosphonic acid (VDPA) or HEDPA be used for stripping TRUs when they are directly to be vitrified. In similar fashion, coprecipitation of actinides, lanthanides, and a few other fission and corrosion products extracted into the TRUEX process solvent was achieved by using iron(III)ferricyanide as a carrier precipitant. The volume of the precipitate was very small and suitable for vitrification of TRUs (Rizvi and Mathur, 1997). In other reports (Chitnis et al., 1999a,b), a mixture of formic acid, hydrazine hydrate, and citric acid have shown promise for efficient stripping of Am and Pu from TRUEX solvent loaded with simulated HLW in both batch and counter‐current modes. Ozawa et al. (1998) report that hydrazine oxalate, hydrazine carbonate, and tetramethylammonium hydroxide for stripping of actinides from loaded TRUEX solvent and its cleanup will lead to a salt‐free effluent. (iv) Degradation, cleanup, and reusability of TRUEX solvent The hydrolytic and radiolytic degradation of CMPO has been studied in CCl4 and decahydronaphthalene (decalin) (Chiarizia and Horwitz, 1986), TCE, or a mixture of TBP and TCE (Nash et al., 1988b). Hydrolytic and radiolytic degradation of TRUEX process solvent (0.2 M CMPO þ 1.2 M TBP in n‐dodecane) has been investigated in the presence of 5 M HNO3 (Chiarizia and Horwitz, 1990) and under dynamic conditions in contact with 3 M HNO3 or synthetic PHWR‐HLW (Mathur et al., 1988). The G values (molecules/100 eV deposited) for the disappearance of CMPO in CMPO–TBP mixture are (1.2  0.3) in n‐dodecane, (4.5  0.3) in TCE, and (16.4  1.7) in CCl4 (Nash et al., 1989; Chiarizia and Horwitz, 1990), indicating that more reactive conditions are created upon radiolysis of chlorinated diluents. Hydrolysis generates only acidic compounds while radiolysis produces both acidic and neutral compounds. The degradation products reported are methyl(octyl)phenylphosphine oxide, octyl(phenyl)‐N‐monoisobutylcarbamoylmethyl phosphine oxide, dibutylphosphoric acid, octyl(phenyl)phosphinic acid, octyl(phenyl)phosphinyl acetic acid (Chiarizia and Horwitz, 1990), methyl(phenyl)‐N,N‐diisobutylcarbamoylmethylphosphinic acid, and phenyl(diisobutyl) carbamoylnitromethylphosphine oxide (Mathur et al., 1988). The presence of the acidic extractants as degradation products increases DAm under stripping conditions. Such impurities must be nearly completely removed from the used TRUEX solvent prior to recycle of the extractant. Table 24.16 gives the DAm with an irradiated CMPO mixture under static conditions in contact with 5 M HNO3 (Chiarizia and Horwitz, 1990) and under dynamic conditions in contact with 3 M HNO3 (Mathur et al., 1988). The D values at pH 2.0 are quite high and increase with absorbed dose. They also increase in the same fashion at 0.04 M HNO3, but up to a dose of 200 kGy ( 55 W h L–1 or 20 Mrad absorbed dose), D is less than 1, hence stripping with 0.04 M HNO3 should still be possible. Up to an absorbed dose of about 200 kGy, primary cleanup

Actinide separation science and technology

2748

Table 24.16 Partitioning of americium (DAm) between 0.2 M CMPO þ 1.2 n‐dodecane and HNO3 as a function of absorbed gamma dose.

M

TBP in

DAm Static condition 5.5 M HNO3 Chiarizia and Horwitz (1990)

Dynamic condition 3 M HNO3 Mathur et al. (1988)

Dose (kGy)

pH 2.0

0.04 M

Dose (kGy)

pH 2.0

0.04 M

0

70

130

200

280

0.011 0.87 0.91 1.33 1.42

0.13 0.72 0.61 0.59 0.58

0

50

110

210

260

0.016 0.55 2.77 16.4 32.7

– 0.23 0.38 0.81 1.21

DAm only after the wash with respective aqueous phase, no sodium carbonate or alumina treatment.

with 0.25 M Na2CO3 will remove most of the acidic impurities. Although the DAm at pH ¼ 2.0 may not match the reference condition, DAm at 0.04 M HNO3 suggests that continuous counter‐current stripping of americium will be efficient. However, at high radiation doses, a secondary cleanup with macroporous anion exchange resin (Chiarizia and Horwitz, 1990) or with basic alumina (Mathur et al., 1988) will restore TRUEX process solvent to near reference condition. (v)

CMPO for extraction chromatography separation of actinides

Extraction chromatography is fundamentally solvent extraction in which the extractant phase is ‘immobilized’ on a non‐reactive solid support. The technique is generally considered to be most applicable for analytical purposes due to the tendency of the immobilized extractant to ‘bleed’ from the solid as the aqueous effuent transits the column. However, process‐scale applications have been suggested. The feasibility of using TRU‐Resin™ (CMPO þ TBP adsorbed on Amberchrom‐CG‐71 from Eichrom Industries Inc., Darien, Illinois, USA) for separating TRU elements from actual neutralized decladding waste solution (resulting from the removal of zirconium cladding from irradiated fuel) from the Hanford Waste tank has been demonstrated (Lumetta et al., 1993). Actinides (U, Pu, Am) and lanthanides (Ce, Eu) were separated from nitric acid solutions using a column of 0.75 M CMPO in TBP adsorbed on XAD‐7. They were subsequently eluted from the column with HCl, oxalic acid, and nitric acid solutions (Yamaura and Matsuda, 1999). Highly encouraging results have been reported for the separation of americium, plutonium, and uranium from acidic waste solutions using several types of extraction chromatographic supports

Applications of separations in actinide science and technology

2749

impregnated with CMPO (Barney and Covan, 1992; Schulte et al., 1995a,b, 1996; Barr et al., 2001). Batch uptake studies have been carried out on the extraction chromatographic behavior of U(VI), Pu(IV), Am(III), and several fission and corrosion products from HNO3 media using CMPO adsorbed on Chromosorb‐102 (CAC) (Mathur et al., 1995). Very high D values of actinides and lanthanides as compared to other fission products were obtained. For example, a small CAC column (containing 9.5 g of CAC) was prepared and about 0.5 L of the uranium depleted actual HAW at an acidity of 1.7 M was passed through it. No a‐activity was detected in the effluent. An americium and RE fraction, plutonium fraction, and uranium fraction were subsequently eluted with 0.04 M HNO3, 0.01 M H2C2O4, and 0.25 M Na2CO3, respectively. Comparable results were obtained while using a similar column and a synthetic SBHLW (Gopalakrishnan et al., 1995). A novel silica‐based extraction chromatographic support has been prepared by immobilizing styrene–divinylbenzene copolymer in porous silica particles (SiO2‐P) (Wei et al., 2000). Separation experiments using a CMPO/SiO2–P resin packed column have given good separation of trivalent actinides and lanthanides from fission products like Cs, Sr, and Ru in simulated HLW solutions containing concentrated HNO3. Also, it has been shown that, using a column packed with freshly purified Cyanex‐301/SiO2–P, americium was completely adsorbed by the resin and only about 1–2% of the Ln(III) were adsorbed from a 1 M NaNO3 solution at pH 3.99 containing trace amounts of 241 Am, 153Gd, 152Eu (and 10–2 M Eu carrier), and 139Ce. Americium was then eluted in a pure form with 0.1 M HNO3. (vi) CMPO in supported liquid membrane separation of actinides Supported liquid membrane (SLM) is a technique wherein a microporous film (either as flat sheets or hollow tubes) is impregnated with an extractant and the transport of target metal ions is facilitated from the feed to the stripping solution. A simple schematic description of the SLM system is shown in Fig. 24.24. The salient features of the SLM processes are (1) extractant needed is in small quantities, (2) high feed/strip volume ratio, and (3) very simple

Fig. 24.24 Schematic description of a supported liquid membrane (SLM) system.

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Actinide separation science and technology

operation systems. Danesi et al. (1983) have used a solution of CMPO/DEB adsorbed onto a 48‐mm thick microporous polypropylene film to facilitate the transport of Am(III) from aqueous nitrate solutions to the strip section containing formic acid solution. The transport mechanism suggested consists of a diffusion process in the feed compartment through an aqueous diffusion film followed by a fast interfacial chemical reaction and finally diffusion through the membrane itself to the stripping compartment. The membrane permeability coefficient has been correlated with the diffusional parameters and to the chemical composition of the system. In another study from the same group (Danesi et al., 1985), an SLM consisting of a mixture of 0.25 M CMPO and 0.75 M TBP in decalin adsorbed on thin microporous polypropylene supports in flat‐sheet and hollow‐fiber configurations was used for the selective separation and concentration of actinides (Am, Pu, U, and Np) and lanthanides from synthetic acidic nuclear wastes. It has been shown that actinides can be efficiently removed at a level sufficient to characterize the resulting solution as a non‐TRU waste. An adjustment developed by Danesi et al. (1985) suggested an improvement in the efficiency of actinide removal from waste solutions. Incorporation of a double liquid membrane system, wherein a second SLM containing a primary amine that extracts only HNO3 from the strip solution, allows near complete removal of actinide and lanthanide metal ions from the feed solution (Chiarizia and Danesi, 1987). Ramanujam et al. (1999) have reported the transport of actinides from nitric acid and uranium‐lean simulated samples as well as the actual HLW using CMPO/n‐dodecane as a carrier and polytetrafluoroethylene as the support. The receiving phase was a mixture of citric acid, formic acid, and hydrazine hydrate. Very good transport of U(VI), Np(VI), Np(IV), Pu(IV), Am(III), and Ce (III) has been achieved. The TRUEX solvent (0.2 M CMPO þ 1.2 M TBP/n‐ dodecane) has also been used as a carrier for the transport of Am(III) from nitrate–nitric acid solutions using track‐etched polycarbonate plastic membranes (Pandey et al., 2001). For Am(III) transport, these membranes performed at a level comparable to that obtained using commercial membranes. (vii)

CMPO in magnetically assisted chemical separation of actinides

Pioneering work on the separation and recovery of actinides from waste solutions using magnetically assisted chemical separation (MACS) was performed at the Argonne National Laboratory by Nunez et al. (1995a,b). This process gives a selective and efficient separation by chemical sorption followed by magnetic recovery. Magnetic particles (ferrite, magnetite, etc.) are coated with extractants and added to the treatment tank containing dilute TRU waste. The solution can be stirred mechanically or by any other method. Finally, the particles are magnetically separated by imposing a magnetic field around the tank, pumping the solution through a magnetic filter, or introducing a magnet into the tank. Actinide ions can be stripped from the loaded particles with small

Applications of separations in actinide science and technology

2751

volumes of suitable stripping agents. This process of recovery of actinides (or any other metal ions) from the waste streams seems to be very simple, compact and, in the proper application, is likely to be cost‐effective. Like membrane‐ based separations, this approach does not involve large amounts of organic solvents and will not produce large volumes of secondary wastes. A conceptual diagram of the MACS process could be visualized as given in Fig. 24.25. Nunez et al. (1995a,b) have used TRUEX solvent (CMPO in TBP) as the active coating on the magnetic particles. The extraction of americium and plutonium from HNO3 solutions ranging in concentration from 2 to 8 M was found to decrease slowly with increasing acid concentration. The range of Kd values was between 400 and 3000 for americium and between 3900, and 46000 for plutonium. The uptake of the same nuclides was tested using synthetic dissolved sludge waste equivalent to the Hanford site waste. It was concluded that the MACS process could be applied to remediation problems at the Hanford site and other sites only if the waste streams contained low concentrations of TRU elements and lanthanides. Kaminiski and Nunez (2000) have further studied the separation of U(VI) from HNO3 and HCl solutions using extractants like CMPO, TBP, TOPO, and HDEHP employing the MACS technique. When magnetic particles were coated with TBP or a mixture of TOPO and HDEHP, partitioning of U(VI) was most efficient from dilute acid environments typical of contaminated ground water. From 2 to 8 M HNO3, the 1.0 M CMPO in TBP‐coated

Fig. 24.25 Schematic diagram of a magnetically assisted chemical separation system (MACS).

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Actinide separation science and technology

particles gave the highest Kd values for U(VI). From these collected observations, it seems likely that MACS has potential for separating actinides from different actinide‐bearing acidic waste solutions using various extractants coated on magnetic particles. Further studies are needed to demonstrate a full‐ scale operation. The same group has also shown a very high separation between Co and Ni while coating the magnetic particles with a mixture of 0.5 M Cyanex 272 and 0.5 M HDEHP (Kaminski and Nunez, 1999). The other uses of the MACS technique were in pre‐analysis separation and concentration of actinides in groundwater (Navratil, 2001), capture of 0.2–0.8 mm PuO2 particles from very dilute solutions (Worl et al., 2001), and removal of Pu and Am from pH 12 waste waters using magnetic polyamine–epichlorohydrin (Ebner et al., 1999). (c)

Trialkylphosphine oxide (TRPO)

Trialkylphosphine oxide, a mixture of seven alkyl phosphine oxides (Structure r), R being heptyl and octyl alone and a mixture of hexyl, heptyl, and octyl groups3, has been tested initially in China at the Institute for Nuclear Energy and Technology (Tsinghua University) (Zhu et al., 1983). Tests were continued in a collaborative effort with the European Institute for Transuranium Elements (Karsruhe, Germany) (Apostolidis et al., 1991; Zhu and Song, 1992; Glatz et al., 1993, 1995; Song et al., 1994, 1996; Song and Zhu, 1994; Zhu and Jiao, 1994) for the extraction of actinides, lanthanides, and other fission products from HNO3 and HLW solutions. The extraction equilibria for the actinide metal ions in their different valency states from nitrate solutions by TRPO can be represented as follows: M3þ aq þ3NO3 aq þ3TRPOorg ! MðNO3 Þ3 3TRPOorg

ð24:47Þ

M4þ aq þ4NO3 aq þ2TRPOorg ! MðNO3 Þ4 2TRPOorg

ð24:48Þ

MOþ 2 aq þNO3 aq þTRPOorg ! MO2 ðNO3 Þ TRPOorg

ð24:49Þ

MO2þ 2 aq þ2NO3 aq þ2TRPOorg ! MO2 ðNO3 Þ2 2TRPOorg

ð24:50Þ

From studies in HNO3 medium with 30% TRPO in n‐dodecane as the extractant (Zhu and Song, 1992), it was observed that DAm was less than 1 at 3 M and about 10 only at 1 M HNO3. To achieve an acceptable Df for Am, the acidity of HLW (typically 3–6 M) must be reduced to less than 1 M. Neptunium extraction is accomplished after electrolytic reduction to Np(IV) in HNO3 and in simulated HAW solutions. During all of the experiments with concentrated wastes initially 3 M HNO3, the waste was diluted ten times and the acidity 3

Zhu and Song (1992) report approximate composition of 10% hexyl, 50% heptyl and 40% octyl.

Applications of separations in actinide science and technology

2753

then adjusted between 0.7 and 1.0 M. Under such conditions, the recovery of U, Np, Pu, Am, and Cm from HAW using a seven‐stage mixer–settler was highly efficient (Zhu and Jiao, 1994). Centrifugal contactor runs (Glatz et al., 1993, 1995; Song et al., 1996) using a battery of 12 extractors with actual diluted HLW has given Df actinides between 103 and 105. The actinides have in all cases been stripped with 5 M HNO3 (Am, Cm, rare earths), 0.5 M oxalic acid (Np, Pu), and 5% Na2CO3 (U). Subsequent investigations applied the process to highly saline actual HLW from a Chinese reprocessing plant using 30% TRPO‐kerosene. The feed was diluted 2.7 times and the HNO3 concentration maintained at 1.08 M. This run using miniature centrifugal contactors gave a Df for total a and 99Tc activities of 588 and 125, respectively. It is claimed that after partitioning the HLW is a non‐a waste (Jianchen and Chongli, 2001). The study of g‐irradiation of a 30% TRPO solution in kerosene has shown that above a dose of 2  106 Gy phosphonic and phosphinic acids are produced as the radiolytic degradation products along with the formation of polymeric products in the molecular weight range of 500–900 g mol–1. The polymer forms strong complexes with plutonium from which the plutonium is not back‐extracted even after five contacts with 0.6 M oxalic acid. This leads to the retention of plutonium in the organic phase (Morita and Kubota, 1987, 1988; Morita et al., 1995; Zhang et al., 2001). Studies have been carried out with the commercially available TRPO (Cyanex‐923, Cytec, Canada Inc., a mixture of four alkyl phosphine oxides R3PO, R0 3PO, R2R0 PO and RR0 2PO where R ¼ hexyl and R0 ¼ octyl group) to evaluate the effect of phase modifier, TBP, on the extraction of actinides from HNO3 and synthetic PHWR‐HLW solutions (Murali and Mathur, 2001). A series of experiments carried out under various conditions indicated that a mixture of 30% TRPO/20% TBP in n‐dodecane, when contacted with PHWR‐HLW containing 18 g L–1 U at 1 M acidity and an organic to aqueous phase ratio of 5:1, gave highly encouraging results in batch studies. In these experiments, acidity was adjusted with ammonia (a 0.1 L solution of HLW required 0.02 L of liquid ammonia). The suitability of TRPO for the partitioning of actinides from HLW solutions has been summarized in Table 24.17. A generic flow sheet is shown in Fig. 24.26. A significant weakness of employing TRPO for actinide partitioning is its comparatively limited capacity and narrow range of nitric acid concentrations that will enable acceptable extraction of trivalent actinides. The dilution of HLW and adjustment of acidity increase waste volume that will create many problems when handling large volumes of HLW. (d)

Diisodecylphosphoric acid (DIDPA)

At the Japan Atomic Energy Research Institute, separation of metal ions from the HLW solutions has been classified into four groups: transuranium elements, Tc–platinum group metals, Sr–Cs, and other elements. For the separation of

Actinide separation science and technology

2754

Table 24.17 Suitability of TRPO for the partitioning of actinides from HLW. HLW, condition

Reagent composition

Inference

In 3.0 M acidity, as such

30% TRPO/n‐dodecane

third phase formation, cannot be used

Zhu and Song (1992) 10 times diluted, [Hþ] adjusted, 0.7–1.0 M

30% TRPO/n‐dodecane

extraction, reported satisfactory

Murali and Mathur (2001) [Hþ] ¼ 1.0 M

30% TRPO þ 20% TBP/n‐ dodecane, org:aq ¼ 5:1

up to six successive contacts, no reflux, reasonably high D

Murali and Mathur (2001) [Hþ] ¼ 1.0 M HLW, diluted in the ratio 1:2 with 1 M HNO3

30% TRPO þ 20% TBP/n‐ dodecane org:aq ¼ 2:1

up to six successive contacts, no reflux, reasonably high D

Fig. 24.26 Generic flow sheet for actinide partitioning using TRPO.

Applications of separations in actinide science and technology

2755

TRU elements, a mixture of 0.5 M DIDPA þ 0.1 M TBP in n‐dodecane has been proposed with the acidity of the HLW reduced to 0.5 M. Neptunium is reduced from Np(V) to Np(IV) using H2O2 and co‐extracted with Pu(IV). DIDPA being in the dimeric form (H2A2) in n‐dodecane, the species of the trivalent tetravalent, pentavalent and hexavalent actinides extracted in the organic phase are most likely the electroneutral complexes M(HA2)3, M(HA2)4, MO2(HA2), and MO2(HA2)2, respectively. Batch as well as counter‐current tests using a 16‐stage miniature mixer–settler with conditioned synthetic HLW have given very high extraction of actinides including neptunium (flow sheet in Fig. 24.27). During stripping, batch studies with DTPA as a stripping agent gave an Am/rare earths separation factor of greater than 10. After selectively stripping trivalent actinides with DTPA, rare earths could be quantitatively removed with 4 M HNO3. Neptunium and plutonium are stripped with 0.8 M oxalic acid (Morita and Kubota, 1987, 1988; Morita et al., 1995). In this process, reduction of acidity to about 0.5 M

Fig. 24.27 Generic flow sheet for actinide partitioning in the DIDPA process.

2756

Actinide separation science and technology

is accomplished using formic acid. At such low acidity, molybdenum and zirconium precipitate out, carrying about 93% of the plutonium. Filtration units are needed to get a clean HLW solution. (e)

N,N0 ‐Dimethyl‐N,N0 ‐dibutyltetradecylmalonamide (DMDBTDMA)

One drawback of using organophosphorus extractants is the solid residue that results upon their incineration at the end of their useful life. French researchers have championed the CHON (carbon, hydrogen, oxygen, nitrogen) principle of extractant design (avoiding the use of S or P containing reagents) to minimize the generation of wastes from extractant destruction. This approach to extractant design has generated a much interesting research on a diverse group of reagents. Among the numerous diamides synthesized and employed for extraction of actinides from nitric acid solutions (Musikas and Hubert, 1983; Musikas, 1987, 1991, 1995; Cuillerdier et al., 1991a,b, 1993; Nigond et al., 1994a,b; Baudin et al., 1995), N,N‐dimethyl‐N0 ,N0 ‐dibutyl‐2‐tetradecylmalonamide (DMDBTDMA) has shown the greatest promise. This diamide dissolves in n‐dodecane, does not give a third phase when in contact with 3–4 M HNO3, and a 1 M solution gives a DAm of about 10 at 3 M HNO3. In France, this extractant has been strongly promoted for the partitioning of actinides from HLW solutions (the DIAMEX process). Investigations of the extraction of uranium, plutonium, americium, and iron by DMDBTDMA at varying HNO3 concentrations from medium activity liquid waste has given encouraging results. However, some problems have been reported while using this process on tests with high‐activity liquid wastes (Baudin et al., 1995). A counter‐current centrifugal extractor experiment using a 16‐stage battery has been carried out to investigate the hydraulic and extraction behavior of the DIAMEX process using a synthetic HLW solution (Courson et al., 2000) and then finally used for the genuine HLW solution (Malmbeck et al., 2000). With six extraction stages, decontamination factors between 100 and 230 were obtained for lanthanides and above 300 for minor actinides. For back‐extraction, four stages were sufficient to recover more than 99.9% of both lanthanides and actinides. The kinetics of lanthanide/actinide extraction (Weigl et al., 2001) and both transient and steady‐state concentration profiles in DIAMEX counter‐current processing (Facchini et al., 2000) have also been studied. Detailed characterization of these materials and further development of the DIAMEX process continue under the auspices of the PARTNEW European Program (Madic et al., 2002). (f)

Neptunium partitioning during processing

In PUREX processing, consistent control of the flow of neptunium through the system is much more difficult than that of uranium, plutonium, or the trivalent actinides. Dissolution of spent reactor fuel by nitric acid under reflux conditions yields a solution containing principally Np(V) and Np(VI). Flow of neptunium in

Applications of separations in actinide science and technology

2757

PUREX depends on what initial oxidation state adjustments are made to the feed and what steps are taken subsequently to partition plutonium and uranium. Drake (1990) has summarized both the chemistry and process aspects of neptunium control in PUREX. The distribution of neptunium remains a topic of interest in actinide partitioning. At the Bhabha Atomic Research Centre, the recovery of neptunium from the HLW along with uranium was attempted using a 30% TBP extraction step. The sample was pretreated with 0.01 M K2Cr2O7 to oxidize both neptunium and plutonium to the hexavalent state. Both are subsequently co‐extracted with U (VI) into 30% TBP. The extraction behavior of neptunium was tested with three types of synthetic wastes and finally with an actual HLW solution. More than 90% of uranium, neptunium, and plutonium could be removed in a single contact. Stripping of neptunium was achieved using a mixture of 0.01 M ascorbic acid and 0.1 M H2O2 in 2 M HNO3 (Mathur et al., 1996b). The kinetics of Np(VI) extraction and stripping under the above conditions while taking synthetic PHWR‐HLW as the feed using the AKUFVE technique (Andersson et al., 1969; Johansson and Rydberg, 1969; Reinhardt and Rydberg, 1969; Rydberg, 1969) has demonstrated that the reaction kinetics are fast enough to avoid problems in mixer–settler contacts (Chitnis et al., 1998a). A counter‐current study using PHWR‐HLW has confirmed the entire process of neptunium extraction and stripping (Chitnis et al., 1998b). Recent work at the British Nuclear Fuels Limited (BNFL) has focused on the development of an advanced PUREX process. Control of neptunium partitioning in such a system can be accomplished through its interactions with hydroxamic acids. Taylor et al. (1998, 2001a,b) report that both formo‐ and acetohydroxamic acids selectively complex tetravalent actinides and rapidly reduce Np(VI) to Np(V). These characteristics could be used to separate neptunium from plutonium or uranium depending on the approach taken for neptunium extraction. Selected alkyl hydroxylamine species have also been evaluated as reductants for Np(VI) and Pu(IV). A similar approach to neptunium selectivity using reduction of Np(VI) by butyraldehydes has been suggested by Uchiyama et al. (1998). In the partitioning conundrum (PARC), process, the separation of neptunium from plutonium and uranium is proposed in steps prior to Pu/U partitioning in the first extraction cycle of PUREX. Np(VI) is rapidly reduced to Np(V) by n‐butyraldehyde. This reagent has no effect on the oxidation state of either Pu(IV) or U(VI). Flow sheet development demonstrated partial success in neptunium, technetium, and uranium partitioning. Further work is required to optimize the process. (g)

Trivalent actinide/lanthanide group separation

As noted in Section 24.3.9, separation of trivalent actinides as a group from the lanthanides has been a topic of great interest since the time of discovery of the transplutonium elements. However, setting aside waste volume minimization

2758

Actinide separation science and technology

considerations, this separation is most important as a problem for hydrometallurgical separations only if the actinides are to be transmuted. Neutron economy in transmutation requires the substantial removal of neutron‐absorbing lanthanides. In the PUREX process, as in most new processes being developed for actinide partitioning from HLW, the stripped fraction containing the trivalent actinides (Am and Cm) also contains the trivalent lanthanides. If all actinides are to be recycled as fuel (or targets for transmutation) in a current generation reactor, it is essential to separate americium and curium from trivalent lanthanides to avoid the strong absorption of thermalized neutrons by the lanthanides. Due to the similarities in chemical properties and behavior of Am(III) and Ln(III) reagents, extractants or complexing agents containing soft‐donor atoms such as N, S, Cl, etc. are required for reliable group separations (Nash, 1994). A number of techniques and reagents have been developed to achieve separation of trivalent actinides and lanthanides. Among these, a few important existing methods and those being newly developed will be discussed. (i)

TRAMEX process

Solution of concentrated LiCl at an acidity of 0.02 M HCl in contact with a tertiary amine solution in kerosene or diethyl benzene is the basis of the TRAMEX process for plant‐scale separation of trivalent actinides from fission‐product lanthanides (Baybarz et al., 1963). In this process, the feed solution is 11 M LiCl (0.02 M HCl) containing trivalent actinides and the fission products; the organic phase employed is 0.6 M Alamine 336 (a mixture of tertiary C6–C8 alkyl amines) in diethyl benzene. The scrubbing solution is 11 M LiCl (0.02 M HCl). Trivalent actinides are extracted into the organic phase, while the trivalent lanthanide fission products remain in the raffinate. The actinides are subsequently stripped from the organic phase with 5 M HCl. The TRAMEX process flow sheet is shown in Fig. 24.28. In a single extraction contact, trivalent actinides (Am, Cm, Bk, Cf, Es, and Fm) as a group have a separation factor of about 100 from the trivalent lanthanides (Ce, Nd, Eu, Tb, Ho, and Tm). The order of extraction for the actinides is reported to be Cf > Fm > Es > Bk > Am > Cm. Several tertiary amines also have been investigated for the extraction of americium and europium from 8 M LiCl/2 M AlCl3/0.02 M HCl using 0.5 M amine in diethyl benzene. The separation factor between americium and europium followed the order: triisoheptyl‐ (151.7) > triisooctyl‐ (124.5) trilauryl‐ (124.1) > Alamine 336 (108). The distribution ratios of americium and europium increased with a decrease in the carbon chain length of the amines. Although separation factor between americium and europium was lowest with Alamine 336, this extractant was preferred because of its easy availability and satisfactory extraction characteristics. In another study, extraction of trivalent Pu, Am, Cm, Cf, Eu, and Tm from 11.9 M LiCl at pH 2.0 was done with quaternary amines (Aliquat‐336 and

Applications of separations in actinide science and technology

2759

Fig. 24.28 Generic flow sheet for the TRAMEX process (adapted from King et al., 1981).

tetraheptyl ammonium chloride) and tertiary amines (triisooctyl amine, tri‐n‐ octyl amine, Alamine‐336 and trilauryl amine) in xylene (Khopkar and Mathur, 1981). The authors have obtained very low separation factors between trivalent actinides and lanthanides when quaternary amines were used whereas they are moderately high while using the tertiary amines. From the absorption spectra of americium and neodymium extracted by the above amines, it was established that the higher separation factors between actinides and lanthanides with tertiary amines are a result of the formation of octahedral hexachloro complexes as compared to the predominantly lower chloro‐complexes extracted by the quaternary amines. (ii)

Separation using LIX‐63

The extractant 5,8‐diethyl‐7‐hydroxydodecane‐6‐one oxime (LIX 63, Structure aa) gave a separation factor (DAm/DEu) of 2.9 in a batch extraction study (Hoshi et al., 2001). Using this extractant, separation of americium from lighter

2760

Actinide separation science and technology

lanthanides has been achieved using high‐speed counter‐current chromatography with a small‐coiled column. The coiled column was filled with polytetrafluoroethylene impregnated with a hexane solution of LIX 63. The mobile phase (0.1 M NaNO3/0.01 M morpholinoethane sulfonic acid) contained neodymium and europium (each 10–5 M) and radiotracer 241Am. The sample gave a very clear peak for lanthanides when the pH of the mobile phase was 5.60. 241Am was eluted at a pH of 4.60.The authors claim that separation of micro amounts of americium from macro amounts of lanthanides (Hoshi et al., 2001) is possible using this technique. Further work needs to be done to complete the evaluation of the method.

(iii)

TALSPEAK process

The chemistry of the TALSPEAK process has been discussed in detail in Section 24.3.9. Though not deployed as such for accomplishing lanthanide– trivalent actinide separations at process scale, the critical reagent in TALSPEAK, aminopolycarboxylic acids, have repeatedly been employed in the conceptual development of actinide–lanthanide hydrometallurgical separation processes. In the DIDPA and SETFICS processes (described in the next section), the separation of 4f and 5f elements is accomplished in a reverse‐ TALSPEAK stripping with 0.05 M DTPA (see Fig. 24.11). In the context of modern process design, the aminopolycarboxylates are acceptable reagents, as they are composed of only C, H, O, and N, and hence are fully incinerable. It should be noted, however, that this class of compounds are known to cause difficulties in storage, as hydrogen generation in waste tanks at Hanford has taught (Babad et al., 1991; Meisel et al., 1991; Pederson et al., 1992). 24.4.5

Methods under development

The considerable knowledge that has been developed during decades of fundamental studies of actinide separations supports a number of fresh approaches to important separations processes. It is expected that future efforts to minimize the volume of wastes derived from spent‐fuel processing will benefit from this scientific legacy as well. An example of the use of well‐understood science being applied in process development is the use of DTPA for La/An partitioning in the DIDPA extraction process for the TRU elements (Morita et al., 1995, 2002). In this case, the stripping of trivalent actinides from the loaded 0.5 M

Applications of separations in actinide science and technology

2761

DIDPA þ 0.1 M TBP solvent gave in a batch experiment (after adjustment to pH 3.6) a separation factor of americium from the lanthanides of 10. A report from JNC has suggested the separation of trivalent actinides and lanthanides applying DTPA in a TRUEX‐based process known as SETFICS (Solvent Extraction for Trivalent F‐elements Intragroup Separation in CMPO‐ Complexant System) (Koma et al., 1998, 1999; Ozawa et al., 1998). Using this process, a counter‐current experiment was done with an actual TRUEX product solution employing 0.05 M DTPA/4 M NaNO3 (pH 2.0) as the strippant. Americium and curium were successfully recovered using SETFICS. 144 Ce/241Am decontamination factor has been reported to be 72. Though 80% of the lanthanides were rejected from the Am–Cm fraction, samarium and europium were poorly separated from the actinide fraction (Koma et al., 1998).

(a)

Employing soft‐donor extractants

By comparison with oxygen donor extactants, soft‐donor extractant molecules offer greater potential for more efficient trivalent actinide–lanthanide group separations. For example, Ensor et al. (1988) reported Am/Eu separation factors of greater than 100 using the synergistic combination of 4‐benzoyl‐ 2,4‐dihydro‐5‐methyl‐2‐phenyl‐3H‐pyrazol‐3‐thione (BMPPT) and 4,7‐diphenyl‐1,10‐phenanthroline (DPPHEN). Independently, neither extractant is particularly effective for the extraction of americium or europium. Musikas and M0 Hubert (1983) reported a high SAm between americium and rare earths for their extraction from dilute nitric acid into an extractant mixture of TPTZ and dinonylnaphthalenesulfonic acid (HDNNS) in CCl4. It was further proposed that HDNNS could be replaced by a‐bromocapric acid in an aliphatic diluent. Work on solvent extraction procedures using TPTZ (and related complexants) continues (Cordier et al., 1998; Drew et al., 1998, 2000). To overcome the considerable aqueous solubility of TPTZ while conforming to the CHON principle, development of nitrogen‐containing extractant molecules continues. In a multinational effort funded by the European Commission’s research program on nuclear fuels reprocessing for the future (NEWPART), polyaza ligands, BTPs, have been characterized for selective extraction of trivalent actinides from 1.9 M HNO3/NH4NO3 solutions (Kolarik et al., 1999). The extracted complexes have the stoichiometry M(NO3)3 · HNO3 · 3BTP and the Am/Eu separation factors average 100–120. The extraction and separation efficiency is strongly dependent on the diluent. The n‐propyl derivative self‐associates (forming dimers and trimers) in a solution of branched alkanes with 2‐ethyl‐1‐hexanol present as a phase modifier. Counter‐current testing of the SANEX‐BTP process with real radioactive materials at the Atalante facility in France demonstrated that the n‐propyl derivative was susceptible to air oxidation with HNO2 catalysis. Branching in the hydrocarbon side chain improves stability.

2762 (b)

Actinide separation science and technology Employing Cyanex 301 and other dialkyldithiophosphinic acids

Though Musikas (1985) indicated potential for effective separation of trivalent actinides from lanthanides using thiophosphoric acid extractants, the instability of such extractants towards hydrolysis reduced their utility. However, dithiophosphinic acids, represented by the commercially available extractant Cyanex 301, are somewhat more stable (Sole et al., 1993). Basic features of these systems have been discussed in Sections 24.3.5 and 24.3.9. In a counter‐current fractional process having three extraction and two scrubbing stages, more than 99.99% of americium can be separated from a trace amount of europium with less than 0.1% extraction of the latter (Zhu, 1995; Zhu et al., 1996; Chen et al., 1997; Hill et al., 1998). In another study, a mixture of 0.5 M purified Cyanex 301 and 0.25 M TBP/ kerosene has been used in a counter‐current experiment to separate americium from lanthanides (Pr, Nd, and Eu) at concentrations of 0.1–0.6 M. A separation factor of around 200 between americium and the lanthanides has been obtained and the extraction can be performed at a pH of 2.7–2.8. This pH value is about 1 unit lower than that needed when Cyanex 301 is used alone. Americium was successfully (>99.998%) separated from macro amounts of lanthanides with only less than 0.04% lanthanides co‐extracted (Wang et al., 2001). The alternative to the SANEX‐BTP process that relies instead on dialkyldithiophosphinic acid extractants has been examined as the SANEX‐DTP or ALINA process. Initial investigations with a solvent composed of Cyanex 301 in combination with TBP or TOPO as phase modifiers proved inadequate in testing due to the instability of Cyanex 301 under representative conditions. Aromatic derivatives were synthesized in an effort to enable the separation from more acidic media and improve radiation stability. The bis( p‐chlorophenyl) dithiophosphinic acid (DClDPDTPA) synthesized by Modolo and Odoj (1999) accomplishes both of these objectives. The SANEX‐IV process currently under development relies on DClDPDTPA in combination with TOPO as phase modifier. This solvent is reported to extract trivalent actinides from 0.5 to 1.5 M nitric acid. Apart from the solvent extraction technique for the separation of trivalent actinides from the lanthanides employing Cyanex 301, other techniques like supported liquid membrane and column chromatography have also been utilized (Hoshi et al., 2000; Mimura et al., 2001). A selective and preferential transport of americium across a supported liquid membrane containing highly purified Cyanex 301 has been achieved in the product solution while most of europium remained in the feed solution (Hoshi et al., 2000). Also, micro‐ capsules enclosing Cyanex 301 were prepared by employing a biopolymer gel, alginic acid, as an immobilization matrix. The chromatographic separation of americium and europium was accomplished by gradient elution with 0.1 M (H, Na)NO3 (pH 2.0) for europium and 0.1 M HNO3 for americium while using the column packed with the above micro‐capsule (Mimura et al., 2001).

Applications of separations in actinide science and technology

2763

Although Cyanex 301 has not yet been used for the separation of americium and curium from the rare earths in the fraction stripped by 0.04 M HNO3 in the TRUEX process, this process appears to have great potential, though radiation stability and the nature of degradation products represent a concern. 24.4.6

Comparison of extractants being proposed for actinide partitioning

A comparison of the different extractants, their concentration, diluent, phase modifier, best conditions for extraction and stripping of americium is given in Table 24.18. Each system has both positive and negative features. Based on cost of the extractant, the DIDPA and TRPO are clearly superior. However, processes based on the TRPO and DIDPA extractants require, respectively, a ten‐fold dilution of the aqueous feed and/or denitration with formaldehyde impacting the volume of wastes generated. Only the DMDBTDMA extractant is completely incinerable. Furthermore, degradation products of DMDBTDMA do not interfere with stripping of americium, while those of CMP and CMPO can. However, the malonamide requires higher concentrations of HNO3 for efficient extraction of americium, has a comparatively steep nitric acid dependence on the extraction side, and a lower radiolytic stability than that of TBP. Phase modifiers (TBP) are required for both CMP and CMPO extraction systems to prevent third‐phase formation, but the TBP apparently increases the stability of the primary extractant. Extraction in the CMPO/TRUEX system is moderately independent of the concentration of HNO3, simplifying feed preparation. As a complement to PUREX, TRUEX has an advantage, as no adjustment of the aqueous raffinate from PUREX would be required to Table 24.18 Comparative features of partitioning of actinides (with data for Am(III)) with various extractants. Extractant concentration (M)

Diluent

HNO3 conc., for extraction (M)

HNO3 concentration for stripping (M) 2

DIDPA, 0.5

n‐dodecane þ 0.1 M TBP

0.5, denitration or dilution of HLW

4

CMPO, 0.2

n‐dodecane þ 1.2 M TBP

2–3, any HLW as such

0.04

TRPO, 30% (V/V)

n‐dodecane

0.7–1.0 M, HLW diluted 10 times

>4

TRPO, 30% (V/V)

n‐dodecane þ 20% TBP

1.0 M, no major dilution

>4

DMDBTDMA, 1.0

n‐dodecane

>2

87% fission) 242Pu targets has been achieved employing the TRUEX process. Other TRU wastes treated with TRUEX solvent at different laboratories in the U.S. are neutralized cladding removal waste (Pacific Northwest National Laboratory), plutonium finishing plant waste (Westinghouse Hanford Co.), and TRU wastes containing chloride salts (Los Alamos National Laboratory). Successful demonstration of a very high efficiency of recovery of TRU elements from the above‐mentioned types of wastes is a unique feature for CMPO as an extractant. Recently, new work has been initiated in the U.S. on the evaluation of possible future nuclear fuel cycles with the commencement of the Advanced Fuel Cycle Initiative. This program is progressing more‐or‐less in tandem with work on future reactor designs (Generation IV program). In addition, a considerable amount of work has been done in the U.S. investigating pyrometallurgical processing of spent nuclear fuels. Though much work remains to be done to fully enable pyroprocessing, there is no denying that this option has some attractive features and additional work to improve the process is justified. (b)

Japan

At the Japan Atomic Energy Research Institute, 0.5 M DIDPA þ 0.1 M TBP in n‐dodecane has been proposed for the separation of TRU elements from HLW solutions. To employ this acidic extractant for spent fuel reprocessing, the acidity must be reduced to 0.5 M to obtain an efficient recovery of actinides. Work has been done in batch and counter‐current tests using synthetic HLW. At Power Reactor and Nuclear Fuel Development Corporation, the TRUEX solvent, i.e. 0.2 M CMPO þ 1.2 M TBP in n‐dodecane, has been utilized for actinide partitioning in batch and counter‐current runs with a real high‐active raffinate from FBR spent fuel reprocessing. Pyroprocessing and supercritical fluids extraction are also under active consideration in Japan, as are alternatives to the DIAMEX process. (c)

Russia

At the Khlopin Radium Institute, St. Petersburg, efforts have been directed towards using a modified PUREX process to recover actinides such as neptunium

Actinide separation science and technology

2766

and the other actinides, possibly including the trivalent ions by using a neutral organophosphorus extractant like isoamyldialkylphosphine oxide. Scientists in this laboratory have developed a Russian TRUEX process, based on diphenyl‐N,N‐dibutyl CMPO which is less expensive and gives higher DAm values as compared to O(F)CMPO. It does not need TBP as the phase modifier but the diluent used is a fluoroether. Very high recoveries and separations of trivalent actinides have been achieved from waste solutions. A variation on this process has been incorporated by scientists in the U.S. at the Idaho National Engineering and Environmental Laboratory in the development of the UNEX process for radioactive waste processing. (d)

China

In China, the main emphasis has been on the extractant trialkylphosphine oxide (TRPO), which is easily synthesized and inexpensive. Actinide recovery and separation from HLW solutions carried out within international collaborations had to be done at acidity of 1 M and the HLW diluted considerably in this process. However, batch studies, mixer–settler, and centrifugal contactor runs have given highly encouraging results. (e)

France

French chemists have concentrated on the CHON (carbon, hydrogen, oxygen, and nitrogen) principle to design the new extractants of the class amides and diamides. After significant efforts in synthesizing various diamides with different combinations of substituents at R1, R2, and R3 (Structure n), the compound DMDBTDMA was prepared, which is soluble in aliphatic diluent like n‐dodecane and has respectable D values for trivalent actinides and lanthanides at 3–4 M HNO3. More recently, the tetradecyl backbone substituent has been replaced (in the baseline process) by an ethoxy hexyl (ether) group to improve phase compatibility characteristics. Batch studies, mixer–settler, and centrifugal contactor runs with synthetic as well as actual high‐active wastes have given satisfactory results for the recovery of actinides. A great deal of effort has been expended in France on new reagents and processes for minor actinide partitioning and lanthanide/actinide separations and on investigating phase compatibility issues in solvent extraction. Creativity and innovation highlight both the technology and R&D efforts in France on the closed‐loop nuclear fuel cycle. (f)

India

Scientists at Bhabha Atomic Research Centre have tested the TRUEX solvent for batch and mixer–settler runs using synthetic high‐active waste, stored sulfate bearing waste, and PHWR‐HLW. A uranium depletion step with 30% TBP/ n‐dodecane followed by TRUEX process has been suggested for highly efficient

Applications of separations in actinide science and technology

2767

separation and recovery of all the actinides. Batch studies with actual HAW and HLW of research reactor fuels and mixer–settler runs with actual HAW of research reactor fuels have been performed. The raffinate from the mixer–settler runs with synthetic as well as actual wastes had a‐activities at the background level. Also, work has been done with Cyanex 923 (a commercially available TRPO) and its mixture with TBP in n‐dodecane. The batch studies suggest that even with the combination of Cyanex 923 and TBP, the acidity has to be brought down to about 1 M but it may not be necessary to dilute the HLW to a great extent for achieving high separation efficiencies of the actinides. Preliminary studies have been carried out on the extraction of Am(III), U(VI), and Pu(IV) with DMDBTDMA from nitric acid and PHWR‐HLW solutions. (g)

Sweden

The research group at Chalmers University developed a three‐stage process called CTH (Chalmers Tekniska Hogskola) for separation and recovery of all the actinides from HLW solutions (Svantesson et al., 1979, 1980; Liljenzin et al., 1980). In the first step, acidity of HLW is adjusted to 6 M and uranium, neptunium, and plutonium are extracted with 1 M HDEHP/kerosene. This step also extracts most of the Fe, Zr, Nb, and Mo. In the second step, the acidity of the raffinate is considerably reduced by contacting with 50% TBP/ kerosene. Finally in the third step, americium, curium, and rare earths are extracted with 1 M HDEHP. From all the loaded organic phase, the actinides are stripped with suitable reagents. The entire process has been tried with synthetic waste using small‐scale mixer–settlers. Because of the problems associated with significant acidity adjustment in the entire process, this may not be cost‐effective on a plant scale. (h)

Other countries

In the UK, though British Nuclear Fuels Ltd. actively reprocesses commercial fuels to recover uranium and plutonium, little has been done in the field of actinide partitioning. It appears likely that if the United Kingdom ultimately decides to partition actinides, an appropriate process from the variety of options being developed elsewhere will most probably be adopted. Among the other countries, at the European Commission Joint Research Centre–Ispra Establishment, Italy, a process has been developed by first extracting uranium, neptunium, and plutonium with TBP or HDEHP, diluting the raffinate to a pH of 2 and extracting trivalent americium, curium, and rare earths with a mixture of 0.3 M HDEHP þ 0.2 M TBP in n‐dodecane (Cecille et al., 1980). This process has the same limitations mentioned above for the CTH process. Within Europe, wide international collaboration on actinide partitioning is supported by the European Commission in the frame of its successive Research Framework Programs.

Actinide separation science and technology

2768 24.5

WHAT DOES THE FUTURE HOLD? FUTURE DIRECTIONS IN ACTINIDE SEPARATIONS

Actinide separations for plutonium processing (in connection with either weapons production or as a part of a plutonium recycle program) and uranium recovery involve primarily solvent extraction processes operating on acidic aqueous solutions. As a consequence of 50 years of both research and process experience, this technology must be considered mature, and has proven to be reliable, though its application has generated complex wastes. Partly as a result of this maturity, but also due to changes in world politics, acid processing to recover plutonium is no longer the principal driving force for development in actinide separations. The challenges attendant to the present status of actinide separations are determined by renewed interest in closing the fuel cycle and by the need for waste cleanup and environment restoration for legacy materials. Current issues in actinide separations are defined by the physical and chemical state of actinides as they occur and the motivation for carrying out the separation. 24.5.1

Alkaline wastes in underground storage tanks

One legacy of 50 years of plutonium production for defense purposes is a large volume of mixed wastes (containing TRUs, long‐lived fission products, and non‐radioactive but chemically hazardous materials) (Horwitz et al., 1982). Their presence in underground waste tanks or storage bins represents a potential threat to the surrounding environment and so demands attention. These wastes take the form of sludges, solids, alkaline, or acidic solutions, and slurry phases in which actinides coexist with long‐lived fission products and non‐ radioactive constituents. In the face of this complexity, how can the volume of waste going to a repository be minimized? Two potentially important areas for development are: improving sludge washing procedures that can selectively remove actinides from the solids or sludges (solid–liquid separation), and separation procedures suitable for plant‐scale development which can operate in alkaline media. 24.5.2

Actinide burnup strategies

A ‘permanent’ remedy to the long‐term hazard of actinides is to ‘incinerate’ them in advanced reactors or accelerators and thus transform them into short‐ lived fission products. An added advantage of this approach is the potential for recovery of the energy value of the actinides. Clearly, transmutation also eliminates weapons proliferation concerns as well. Because lanthanides have high cross sections for neutron capture and thus interfere with the neutron physics of actinide burnup, robust Ln/An separation methods are demanded, in particular, processes resistant to radiolysis effects. Two areas of actinide separations research relevant to this problem are the continued development

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of fast reactor concept and pyrometallurgical separation process, and the development of new soft‐donor extractants and aqueous complexants for actinide/ lanthanide separations. Some of the less developed unconventional materials and techniques (RTILs and sc‐CO2, and volatility‐based methods in particular) may ultimately have an important role to play in solving this challenging problem.

24.5.3

Actinides and the environment

Minor concentrations of actinides are present in the terrestrial environment as a result of atmospheric weapons testing, the Chernobyl accident, and actinide production activities (including both planned and accidental releases). Accurate speciation techniques, environment decontamination methods, and in‐situ immobilization techniques are needed. Three generic areas for research, all of which involve some form of separation science, are pertinent to this subject: the development of reliable speciation techniques and thermodynamic models; solid‐solution separation methods for removal of actinides from soils, contaminated process equipment, etc.; and solution–mineral conversion techniques to fix residual actinides in‐situ and inhibit their entry into the hydrosphere/biosphere. In the earliest days of actinides separations, discovery and plutonium production dominated the landscape. Sixty years later as we approach the end of the age of fossil fuels, actinide separation could play a central role in the preservation and restoration of the planetary environment. The major change in emphasis does not mean the end of the need for actinide separations, it indicates a shift toward new horizons. Many opportunities exist for improvements in existing procedures or the development of new methods for actinide isolation.

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Taylor, R. J., May, I., and Hill, N. J. (2001a) in Solvent Extraction for the 21st Century, Proc. Int. Solvent Extraction Conf., ISEC’99 (eds. M. Cox, M. Hidalgo, and M. Valiente), Barcelona, Society of Chemical Industry, London, pp. 1339–43. Taylor, R. J., May, I., Denniss, I. S., Koltunov, V. S., Baranov, S. M., Marvhenko, V. I., Mezhov, E. A., Pastuschak, V. G., Zhuravleva, G. I., and Savilova, O. A. (2001b) in Solvent Extraction for the 21st Century, Proc. Int. Solvent Extraction Conf., ISEC’99 (eds. M. Cox, M. Hidalgo, and M. Valiente), Barcelona, Society of Chemical Industry, London, pp. 1381–5. Teixidor, F., Casensky, B., Dozol, J. F., Gruener, B., Mongeot, H., and Selucky, P. (2002) Selective Separation of M(1þ), M(2þ) and M(3þ) Radionuclides, Namely of Cs, Sr and Actinides, from Nuclear Waste by Means of Chelating Hydrophobic Cluster Anions, Report EUR 19956, Institut de Ciencia de Materials de Barcelona, European Commission. Thied, R. C., Seddon, K. R., Pitner, W. R., and Rooney, D. W. (1999) Patent WO99/ 41752. Thied, R. C., Hatter, J. E., Seddon, K. R., and Pitner, W. R. (2001) Patent WO01/13379 A1. Thompson, S. G., Cunningham, B. B., and Seaborg, G. T. (1950) J. Am. Chem. Soc., 72, 2798–801. Thompson, S. G., Harvey, B. G., Choppin, G. R., and Seaborg, G. T. (1954) J. Am. Chem. Soc., 76, 6229–36. Thompson, S. G. and Seaborg, G. T. (1956) First use of bismuth phosphate for separating plutonium from uranium and fission products, in Progress in Nuclear Energy – Series 3: Process Chemistry, sect. 3, vol. I (eds. F. R. Bruce, J. M. Fletcher, H. H. Hyman, and J. J. Katz), McGraw‐Hill, New York, pp. 163–71. Thompson, S. G. and Seaborg, G. T. (1957) Bismuth phosphate process for the separation of plutonium from aqueous solutions, Patent 2785951. Thulasidas, S. K., Kulkarni, M. J., Goyal, N., Murali, M. S., Mathur, J. N., Page, A. G., Chintalwar, G. J., and Banerji, A. (1999) Studies on the Uptake of U, Eu, Cs and Sr by Plant Sesurium portulacastrum for Bioremediation Using Analytical Spectroscopy, in Nuclear and Radiochemistry Symp. NUCAR‐99, Bhabha Atomic Research Centre. Tian, G., Zhu, Y., and Xu, J. (2001) Solvent Extr. Ion Exch., 19, 993–1015. Tian, G., Zhu, Y., Xu, J., Zhang, P., Hu, T., Xie, Y., and Zhang, J. (2003) Inorg. Chem., 42(3), 735–41. Till, C. and Chang, Y. (eds.) (1988) The Integral Fast Reactor, Advances in Nuclear Science and Technology, Plenum Publishing, New York. Todd, T. A., Law, J. D., Herbst, R. S., and Peterman, D. R. (2003) in American Institute of Chemical Engineers (Spring National Meeting), New Orleans, LA, March 30–April 3, 2003, pp. 2349–55. Toews, K. L., Smart, N. G., and Wai, C. M. (1996) Radiochim. Acta, 75, 179–84. Tomczuk, Z., Ackerman, J. P., Wolson, R. D., and Miller, W. E. (1992) J. Electrochem. Soc., 139(12), 3523–8. Tomioka, O., Enokida, Y., and Yamamoto, I. (2000) Prog. Nucl. Energy, 37(1–4), 417–22. Tomioka, O., Meguro, Y., Enokida, Y., Yamamoto, I., and Yoshida, Z. (2001a) J. Nucl. Sci. Technol., 38(12), 1097–102.

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Tomioka, O., Meguro, Y., Iso, S., Yoshida, Z., Enokida, Y., and Yamamoto, I. (2001b) J. Nucl. Sci. Technol., 38(6), 461–2. Tomioka, O., Meguro, Y., Iso, S., Yoshida, Z., Enokida, Y., and Yamamoto, I. (2002) in Proc. Int. Solvent Extraction Conf., ISEC 2002 (eds. K. C. Sole, P. M. Cole, J. S. Preston, and D. J. Robinson), Capetown, South Africa, Chris van Rensburg Publications, South African Institute of Mining and Metallurgy, Johannesburg, pp. 1143–7. Tomiyasu, H. and Asano, Y. (1995) Prog. Nucl. Energy, 29 (Suppl.), 227–34. Toth, L. and Gilpatrick, L. (1972) Report ORNL‐TM‐4056, Oak Ridge National Laboratory. Trice, V. G. and Chellew, N. R. (1961) Nucl. Sci. Eng., 9, 55–8. Trochimczuk, A. W., Horwitz, E. P., and Alexandratos, S. D. (1994) Sep. Sci. Technol., 29(4), 543–9. Trofimov, T. I., Samsonov, M. D., Lee, S. C., Smart, N. G., and Wai, C. M. (2001) J. Chem. Technol. Biotechnol., 76, 1223–6. Tsezos, M. and Volesky, B. (1981) Biotechnol. Bioeng., 23, 583–604. Tsezos, M. and Volesky, B. (1982) Biotechnol. Bioeng., 24, 385–401. Tsezos, M. (1983) Biotechnol. Bioeng., 25, 2025–40. Tsuda, T., Nohira, T., and Ito, Y. (2001) Electrochim. Acta, 46, 1891–7. Tsuda, T., Nohira, T., and Ito, Y. (2002) Electrochim. Acta, 47, 2817–22. Turanov, A. N., Karandashev, V. K., Kharitonov, A. V., Yarkevich, A. N., and Safronova, Z. V. (2000) Solvent Extr. Ion Exch., 18(6), 1109–34. Turanov, A. N., Karandashev, V. K., Kharitonov, A. V., Safronova, Z. V., and Yarkevich, A. N. (2002) Radiochemistry 44(1), 18–25. (Moscow, Russian Federation) (Translation of Radiokhimiya). Turanov, A. N., Karandashev, V. K., Yarkevich, A. N., and Safronova, Z. V. (2004) Solvent Extr. Ion Exch., 22(3), 391–413. Uchiyama, G., Asakura, T., Hotoku, S., and Fujine, S. (1998) Solvent Extr. Ion Exch., 16, 1191–213. Uozumi, K., Kinoshita, K., Inoue, T., Fusselman, S. P., Grimmett, D. L., Roy, J. J., Storvick, T. S., Krueger, C. L., and Nabelek, C. R. (2001) J. Nucl. Sci. Technol., 38(1), 36–44. Usami, T., Kurata, M., Inoue, T., Sims, H. E., Beetham, S. A., and Jenkins, J. A. (2002) J. Nucl. Mater., 300, 15–26. Ustinov, O. A. (1995) Physical-Chemical Validation of Spent U‐Pu Oxide Fuel Reprocessing by Recrystallization in Molten Molybdates, Abstracts of the Molten Salt in Nuclear Technologies Seminar, Dimitrovgrad, Russia. Usuda, S. (1987) J. Radioanal. Nucl. Chem., 111(2), 399–410. Usuda, S., Shinohara, S. N., and Yosikama, H. (1987) J. Radioanal. Nucl. Chem., 109, 353–61. Usuda, S. (1988) J. Radioanal. Nucl. Chem., 123, 619–31. Vandegrift, G. F., Leonard, R. A., Steindler, M. A., Horwitz, E. P., Basile, L. J., Diamond, H., Kalina, D. G. and Kaplan, L. (1984) Transuranic Decontamination of Nitric Acid Solutions by the TRUEX Solvent Extraction Process – Preliminary Development Studies, Report ANL‐84‐85, Argonne National Laboratory, Argonne, IL.

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CHAPTER TWENTY FIVE

ORGANOACTINIDE CHEMISTRY: SYNTHESIS AND CHARACTERIZATION Carol J. Burns and Moris S. Eisen 25.1 25.2 25.3 25.4

25.5 25.6

Bimetallic complexes 2889 Neutral carbon‐based donor ligands 2893 References 2894

Introduction 2799 Carbon‐based ancillary ligands 2800 Heteroatom‐containing p‐ancillary ligands 2868 Heteroatom‐based ancillary ligands 2876

25.1 INTRODUCTION

The advent of modern organometallic chemistry has often been cited as the report of the preparation of ferrocene, (Z5‐C5H5)2Fe, the first metallic complex containing a p‐complexed ligand (Pauson, 1951). It was not long after the report of this compound that comparable analogs of the lanthanides and actinides were reported (Reynolds and Wilkinson, 1956). Since that time, the organometallic chemistry of the actinides has lagged in comparable developments to the chemistry of the transition metals. Recent years, however, have witnessed a resurgence of interest in the non‐aqueous chemistry of the actinides, in part due to the availability of a much wider array of ancillary ligands capable of stabilizing new compounds and introducing new types of reactivity. Equally important in stimulating new interest has been the realization by numerous researchers that the organometallic chemistry of these elements provides types of chemical environments that effectively probe the metals’ ability to employ valence 6d and 5f orbitals in chemical bonding. Modern organoactinide chemistry is now characterized by the existence not only of actinide analogs to many classes of d‐transition metal complexes (particularly those of Groups 3 and 4), but increasingly common reports of compounds (and types of reactions) unique to the actinide series. Most developments in the non‐aqueous chemistry of the 2799

2800

Organoactinide chemistry: synthesis and characterization

actinides have involved the use of thorium and uranium, both due to their lower specific activity, and to the apparent chemical similarity these elements bear to Group 4 metals in organometallic transformations. Uranium has further demonstrated the ability to access a wide range of oxidation states (3þ to 6þ) in organic solvents, providing for greater flexibility in effecting chemical transformations. The earliest technological interest in organometallic actinide chemistry focused on its potential for application in isotope separation processes (Gilman, 1968). More recent reports continue to discuss the volatility of organoactinide compounds as a possible benefit in separation processes (gas chromatography, fractional sublimation) or in chemical vapor deposition processes (Mishin et al., 1986). At the same time, interest has emerged in the behavior of the actinide elements in stoichiometric and catalytic transformations, particularly in comparison to d‐transition metal analogs. The relatively large size and abundance of valence orbitals associated with the actinide metals can facilitate transformations of substrates at the metal center, or enable new types of reactions. These reactions will be discussed further in Chapter 26. This chapter will provide an overview of the preparation and properties of the major classes of actinide complexes; the material will be organized by major ancillary ligand type. Within a class of ligands, compounds will be discussed based upon assigned formal oxidation states. While earlier definitions of organometallic chemistry would restrict consideration to compounds exclusively containing metal–carbon s‐ or p‐bonds, for the purposes of this treatise we will briefly consider select classes of ancillary ligands based principally coordination of the metal center by elements of Group 15 or Group 16, particularly where these ligand sets serve to support novel molecular transformations at the metal center. 25.2

CARBON‐BASED ANCILLARY LIGANDS

25.2.1 (a)

Cyclopentadienyl ligands

Trivalent chemistry

The most common class of organoactinide complexes is that containing the cyclopentadienyl ligand ðC5 H
5 Þ, or one of its substituted derivatives. The use of variants of the cyclopentadienyl ligand has dominated the field of organometallic chemistry over the past 50 years, given their ability to stabilize a wide variety of oxidation states and coordination environments (Cotton et al., 1999). The cyclopentadienyl ligand itself dominated the early development of organoactinide chemistry. The coordination environment that likely has been reported for the largest number of the actinide elements is the homoleptic compound (Z5‐C5H5)3An (An ¼ actinide). This ligand set support most members of the actinide series from thorium to californium (Table 25.1). A number of synthetic routes have been reported to generate these species and their tetrahydrofuran (THF) adducts, including direct metathesis with alkali

Carbon‐based ancillary ligands Table 25.1

2801

Tris(cyclopentadienyl)actinide complexes.

Compound

Color

Melting point ( C)

References

(Z5‐C5H5)3Tha (Z5‐C5H5)3U (Z5‐C5H5)3Np (Z5‐C5H5)3Pu (Z5‐C5H5)3Am (Z5‐C5H5)3Cm (Z5‐C5H5)3Bk (Z5‐C5H5)3Cf

Green Brown Brown Green Flesh Colorless Amber Red

– >200 – 180 (dec.) 330 (dec.) – – –

Kanellakopolous et al. (1974a) Kanellakopolus et al. (1970) Karraker and Stone (1972) Baumga¨rtner et al. (1965) Baumga¨rtner et al. (1966) Laubereau and Burns (1970a) Laubereau and Burns (1970b) Laubereau and Burns (1970b)

a

Compound not fully characterized.

metal salts (Crisler and Eggerman, 1974; Kanellakopolus et al., 1974a, 1980; Moody and Odom, 1979; Wasserman et al., 1983), or transmetallation with Be (Z5‐C5H5)2 or Mg(Z5‐C5H5)2 (Fischer and Fischer, 1963; Baumga¨rtner et al., 1965, 1966, 1967, 1970; Laubereau and Burns, 1970a,b). In addition, the trivalent compounds may be obtained from chemical (Crisler and Eggerman, 1974) or photochemical (Kalina et al., 1977; Bruno et al., 1982) reduction of suitable tetravalent actinide precursors (Karraker and Stone, 1972; Chang et al., 1979; Zanella et al., 1980). Examples of these preparations are given in equations (25.1)–(25.5). UCl3  nTHF þ 3NaðC5 H5 Þ 2AnCl3 þ 3BeðC5 H5 Þ2

THF

70 C

ðZ5 -C5 H5 Þ3 UðTHFÞ þ 3NaCl ðZ5 -C5 H5 Þ3 An þ 3BeCl2 An ¼ Pu; Am; Cm; Bk; Cf

2PuCl3 þ 3MgðC5 H5 Þ2 ðZ5 - C5 H5 Þ3 U½ðCHðCH3 Þ2 

THF

hu;C6 H6

ðZ5 -C5 H5 Þ3 Pu þ 3MgCl2

ð25:1Þ ð25:2Þ

ð25:3Þ

ðZ5 -C5 H5 Þ3 U
H þ CH2 ¼ CHCH3

ðZ5 - C5 H5 Þ3 U
H þ ðZ5 -C5 H5 Þ3 U½CHðCH3 Þ2 
! ðZ5 -C5 H5 Þ3 U þ CH3 CH2 CH3 ð25:4Þ Cs2 PuCl6 þ MgðC5 H5 Þ2

THF

ðZ5 -C5 H5 Þ3 Pu þ unknown

ð25:5Þ

More recently, a study was conducted on reduction products of (Z5‐C5H5)3UCl with a variety of reducing agents (Le Marechal et al., 1989). It was found that the composition of the product was a function of the reducing agent [equations (25.6)–(25.8)].

2802

Organoactinide chemistry: synthesis and characterization THF

ðZ5 -C5 H5 Þ3 UCl þ Na=Hg

ðZ5 -C5 H5 Þ3 UðTHFÞ

ðZ5 -C5 H5 Þ3 UCl þ Na=Hg þ 18
crown
6

THF

ð25:6Þ

½ð18
crown
6ÞNa ½ðZ5 -C5 H5 Þ3 UCl ð25:7Þ

ðZ5 -C5 H5 Þ3 UCl þ NaH

½NaðTHFÞ2 f½ðZ5 -C5 H5 Þ3 U2 ðm-HÞg ð25:8Þ

Perhaps the most useful development in the synthetic chemistry of trivalent actinide complexes in recent years has been the development of the more soluble iodide starting materials (Karraker, 1987; Clark et al., 1989) AnI3L4 (An ¼ U, Np, Pu; L ¼ THF, pyridine, DMSO). These species, generated from actinide metals and halide sources in coordinating solvents, are readily soluble in organic solvents, and serve as convenient precursors to a variety of trivalent actinide species [equations (25.9)–(25.10)] (Zwick et al., 1992). An þ 3=2I2

L

AnI3 L4 L ¼ THF; pyridine; DMSO

PuI3 ðTHFÞ4 þ LiðC5 H5 Þ

THF

ðZ5 -C5 H5 Þ3 PuðTHFÞ þ 3LiI

ð25:9Þ

ð25:10Þ

The solubility of the parent tris(cyclopentadienyl)actinide complexes is limited in non‐polar media, presumably due to oligomerization through bridging cyclopentadienyl ligands. The molecular structures of these species have only been inferred by comparison of powder diffraction data with that obtained from known tris(cyclopentadienyl)lanthanide complexes. In response, a number of groups have explored the chemistry of substituted analogs of the cyclopentadienyl ligand for the light actinides (Th, U), including those with alkyl or silyl substituents, as well as the indenyl ligand. Tris(ligand) complexes have been reported and several examples have been structurally characterized. Tris(indenyl) complexes of thorium and uranium have been reported, and the complex (Z5‐C9H7)3U was structurally characterized (Goffart, 1979; Meunier‐Piret et al., 1980). Several other trivalent substituted cyclopentadienyl complexes have been prepared by reduction of tetravalent precursors (Brennan et al., 1986a; Zalkin et al., 1988a; Stults et al., 1990), as shown in equation (25.11).

Carbon‐based ancillary ligands

2803

The complexes [Z5‐(Me3Si)2C5H3]3U and (Z5‐C5Me4H)3U have also been prepared by reduction of tetravalent precursors (del Mar Conejo et al., 1999), although in the synthesis of [Z5‐(Me3Si)2C5H3]3U, ligand redistribution also takes place [equation (25.12)].

One of the more interesting members of the series of trivalent homoleptic cyclopentadienyl complexes is the well‐characterized thorium example, [Z5‐ (RMe2Si)2C5H3]3Th (R ¼ Me, tBu) (Blake et al., 1986a, 2001). This complex was prepared in a manner similar to that shown in equation (25.12), by reduction of the metallocene dichloride or the tris(cyclopentadienyl) chloride in toluene by Na–K alloy. The compound is isolated in good yield as a dark blue crystalline material, which has been structurally characterized (Fig. 25.1). As for most base‐free tris(cyclopentadienyl)actinide complexes, the compound crystallizes in a pseudo‐trigonal planar structure, with averaged ligand centroid–thorium–centroid angles near 120 , and averaged Th–Cring distances ˚ . A particular element of interest for this complex has been its of 2.80(2) A electronic structure. One of the most investigated aspects of actinide–cyclopentadienyl chemistry has been the nature of bonding between the metal and the ligand (Burns and Bursten, 1989). Most experimental studies of tris(cyclopentadienyl)actinide complexes, including 237Np Mo¨ssbauer studies of (Z5‐C5H5)3 Np (Karraker and Stone, 1972) and infrared and absorption spectroscopic studies of plutonium, americium, and curium analogs (Baumga¨rtner et al., 1965; Pappalardo et al., 1969; Nugent et al., 1971) suggest that while the bonding is somewhat more covalent than that in lanthanide analogs, the interaction between the metal and the cyclopentadienyl ring is still principally ionic. Theoretical treatments have suggested that the 6d orbitals are chiefly involved in interactions with ligand‐based orbitals. While the 5f orbital energy drops across the series, creating an energy match with ligand‐based orbitals, spatial overlap is poor, precluding strong metal–ligand bonding (Strittmatter and Bursten, 1991). Thorium lies early in the actinide series and the relatively high energy of the 5f orbitals (before the increasing effective nuclear charge across the series drops the energy of these orbitals) has lead to speculation that a Th(III) compound could in fact demonstrate a 6d1 ground state. In support of this, Kot et al. (1988) have reported the observation of an EPR spectrum with g values close to 2 at room temperature. Despite the common use of the permethylated cyclopentadienyl ligand ðC5 Me
5 Þ in actinide and lanthanide chemistry, it is only recently that a tris (cyclopentadienyl) actinide complex has been prepared with this ligand

2804

Organoactinide chemistry: synthesis and characterization

Fig. 25.1 Crystal structure of [
5‐(Me3Si)2C5H3]3Th (Blake et al., 1986a). (Reproduced by permission of The Royal Society of Chemistry.)

(Evans et al., 1997). It was previously anticipated that the large steric bulk associated with this ligand would preclude incorporation of three pentamethylcyclopentadienyl groups in the coordination sphere of an actinide, and in fact direct metathesis routes had not proven successful. The complex (Z5‐C5Me5)3U was instead initially prepared by reaction of a trivalent hydride complex with tetramethylfulvene [equation (25.13)].

Carbon‐based ancillary ligands

2805

Fig. 25.2 Crystal structure of (
5‐C5Me5)3U (Evans et al., 1997). (Reproduced with permission from John Wiley & Sons, Inc.)

Since that time, however, several other routes have been reported to generate the compound (Evans et al., 2002). The molecular structure is shown in ˚ ] is Fig. 25.2.The average U–Cring bond distance in this compound [2.858(3) A much larger than in other crystallographically characterized U(III) pentamethyl˚ ), suggesting a significant degree of steric cyclopentadienyl complexes (ca. 2.77 A crowding. The tris(cyclopentadienyl)actinide complexes display a rich coordination chemistry, and one which sheds light on the nature of metal orbital participation in chemical bonding. Actinide metals generally are acidic and coordinate Lewis bases. As previously discussed, many of the tris(cyclopentadienyl)actinide complexes can be isolated as THF adducts directly from reactions carried out in that solvent. In addition, these complexes will coordinate other simple N‐, O‐, or P‐ donor bases. In most instances the complexes form simple 1:1 adducts [equation (25.14)] (Brennan and Zalkin, 1985; Brennan et al., 1986b, 1988a; Zalkin and Brennan, 1987; Rosen and Zalkin, 1989; Adam et al., 1993), while in select cases complexes have been isolated where two metal centers are bridged by a bidentate base [equation (25.15)] (Zalkin et al., 1987b).

2806

Organoactinide chemistry: synthesis and characterization

Similarly, reaction of tris(cyclopentadienyl) complexes with anionic reagents has been shown to produce either anionic [equation (25.16)] or anion‐bridged bimetallic complexes [equation (25.17)] (Stults et al., 1989; Berthet et al., 1991a, 1992a): 2ðZ5 - ðSiMe3 ÞC5 H4 Þ3 U þ NaN3 þ 18-crown-6

½Nað18-crown-6Þ

½ðZ5 - ðSiMe3 ÞC5 H4 Þ3 U
N ¼ N ¼ N
UðZ5 - ðSiMe3 ÞC5 H4 Þ3 U ð25:16Þ 2ðZ5 - ðSiMe3 ÞC5 H4 Þ3 U þ NaH þ 18-crown-6

½Nað18-crown-6Þ

½ðZ - ðSiMe3 ÞC5 H4 Þ3 U
H
UðZ - ðSiMe3 ÞC5 H4 Þ3 U 5

5

ð25:17Þ Determination of the relative affinities of tris(cyclopentadienyl) complexes for various classes of ligands has been used to suggest the extent of metal‐to‐ligand p‐back‐donation. In order to compare the properties of actinides with lanthanides, ligand displacement series have been evaluated for the compounds (RC5H4)3M (M ¼ U, Ce) (Brennan et al., 1987). Both uranium and cerium complexes were found to have a preference for ‘softer’ phosphine donor ligands over ‘harder’ amine ligands, although in direct competition between the two metals, uranium always prefers the softer donors over cerium. Examination of the crystal structures of comparable uranium and cerium compounds reveals a slight shortening of the U–P bond (corrected for differences in metal radii); it has been suggested that this is a consequence of metal p‐back‐donation to phosphorus. Another indication of the ability of low‐valent early actinides to engage in p‐back‐donation may be found in the coordination of carbon monoxide to (RnC5H5–n)3U (Brennan et al., 1986c; Parry et al., 1995; del Mar Conejo et al., 1999). Both structural and spectroscopic studies indicate that a strong degree of metal‐to‐ligand back donation occurs. The molecular structure of (Z5‐C5Me4H)3U(CO) (Fig. 25.3) evidences a short U–CCO bond distance of ˚. 2.383(6) A

Carbon‐based ancillary ligands

2807

Fig. 25.3 Crystal structure of [
5‐C5Me4H]3U(CO) (del Mar Conejo et al., 1999). (Reprinted with permission from John Wiley & Sons, Inc.) Table 25.2 IR data of (
5‐RnC5H5–n)3U(CO) complexes. Compound

nCO (cm–1)

(Z5‐C5Me4H)3U(CO) (Z5‐Me3CC5H4)3U(CO) (Z5‐Me3SiC5H4)3U(CO) [Z5‐(Me3Si)2C5H3]3U(CO)

1880 1960 1976 1988

Comparison of the nCO stretching frequencies for a series of compounds with varying ligand substituents (Table 25.2) demonstrates that electron‐donating substituents on the ring contribute to increasing the electron density at the metal center, increasing metal‐to‐ligand back donation. There is little comparable data for the heavier actinides, although the above bonding arguments would suggest that as the 6d orbital energy drops across the series, metal–ligand interactions would be weaker. Consistent with this picture, it has been reported that plutonium forms less robust adducts. While the complex (Z5‐C5H5)3Pu(THF) can be isolated from solution, the THF is removed upon sublimation (Crisler and Eggerman, 1974); the analogous uranium compound remains intact upon sublimation (Wasserman et al., 1983). The early trivalent actinide cyclopentadienyl complexes are susceptible to one‐ and two‐electron oxidation reactions. As an example, reaction of the tris (cyclopentadienyl) complexes have been reported to yield the corresponding U(IV) thiolate or selenolate complexes [equation (25.18)] (Leverd et al., 1996).

2808

Organoactinide chemistry: synthesis and characterization Cp3 U þ R
E
E
R Cp3 U
ER 5 5 Cp ¼ ðZ -C5 H5 Þ; ðZ -C5 H4 MeÞ; ðZ5 -C5 H4 SiMe3 Þ; E ¼ S; R ¼ Me; Et; i Pr; t Bu; P; E ¼ Se; R ¼ Me

ð25:18Þ

Alkyl halides are similarly capable of oxidizing U(III) to generate equimolar mixtures of U(IV)–R and U(IV)–X as shown in equation (25.19) (Villiers and Ephritikhine, 1990). 2ðZ5 -C5 H5 Þ3 UðTHFÞ þ R
X

ðZ5 -C5 H5 Þ3 U
R þ ðZ5 -C5 H5 Þ3 U
X ð25:19Þ

In the presence of sodium amalgam to reduce the uranium halide formed, the reaction can be made to be quantitative for formation of the alkyl species. Reaction of (Z5‐C5H5)3U(THF) with dioxygen produces the bridged bimetallic complex [(Z5‐C5H5)3U]2(m‐O) (Spirlet et al., 1996). The analogous m‐ sulfido complex was produced by reaction of (Z5‐C5H5)3UCl with freshly prepared K2S. Chalcogen transfer reagents also oxidize tris(cyclopentadienyl) uranium complexes to yield bridged bimetallic species [equation (25.20)]; while most phosphine chalcogenides react readily, phosphine oxide does not oxidize U(III), but rather yields a base adduct (Brennan et al., 1986b). ðZ5 -C5 H4 MeÞ3 UðTHFÞ þ E ¼ PR3 ðZ5 -C5 H4 MeÞ3 U
E
UðZ5 -C5 H4 MeÞ3 E ¼ Se; Te; R ¼ Bu; E ¼ S; R ¼ Ph

ð25:20Þ

An analogous bridging oxo complex has been generated by the reaction of (Z5‐ C5H4SiMe3)3U with CO2 or N2O [equation (25.21)] (Berthet et al., 1991b). ðZ5 -C5 H4 SiMeÞ3 U þ CO2 or N2 O ðZ5 -C5 H4 SiMe3 Þ3 U
O
UðZ5 -C5 H4 SiMe3 Þ3

ð25:21Þ

This complex can also be prepared by the reaction of (Z5‐C5H4SiMe3)3U(OH) with (Z5‐C5H4SiMe3)3UH (Berthet et al., 1993); pyrolysis of the hydroxide complex generates instead the trinuclear complex [(Z5‐C5H4SiMe3)2U(m‐O)]3.

Carbon‐based ancillary ligands

2809

There are also a limited number of examples of two‐electron oxidation reactions of tris(cyclopentadienyl)uranium compounds. Reaction of (Z5‐C5H4Me)3U (THF) with organic azides (Brennan and Andersen, 1985) results in elimination of dinitrogen and formation of U(V) organoimido derivatives [equation (25.22)].

The related reaction with 1,3‐ or 1,4‐diazidobenzene gives rise to bimetallic pentavalent products [equation (25.23)] (Rosen et al., 1990).

The product generated from 1,4‐diazidobenzene supports electronic communication between the metal centers through an aromatic ligand conjugation‐based superexchange pathway; antiferromagnetic coupling is observed between the unpaired spins on the two metal centers (Fig. 25.4). The compound derived from 1,3‐diazidobenzene, however, cannot undergo similar conjugation, and the susceptibility data show no interaction between the metal centers. There exist relatively fewer examples of trivalent actinide complexes with two cyclopentadienyl rings. Compounds of the parent cyclopentadienyl ion are somewhat rare. Examples include the reported compounds (Z5‐C5H5)2ThCl (Kanellakopulos et al., 1974a) and (Z5‐C5H5)2BkCl (Laubereau, 1970), thought to exist as dimers. The compounds (Z5‐C5H4Me)2NpI(THF)3 and (Z5‐C5H4Me) NpI2(THF)3 were prepared by reactions of NpI3(THF)4 with Tl(C5H4Me) in tetrahydrofuran (Karraker, 1987). Given the propensity of sterically smaller ligands to redistribute and generate multiple species in solution, most complexes have been generated with more highly substituted cyclopentadienyl ligands, particularly (Z5‐C5Me5), [Z5‐(Me3Si)2C5H3], and [Z5‐(Me3C)2C5H3]. One of the most investigated of these complexes is the chloride‐bridged trimeric complex [(Z5‐C5Me5)2U(m‐Cl)]3 (Manriquez et al., 1979; Fagan et al., 1982). The complex can be prepared by a number of routes as shown in equations (25.24)–(25.26).

2810

Organoactinide chemistry: synthesis and characterization

Fig. 25.4 Magnetic susceptibility data for 1,4‐[(
5‐C5H4Me)3U](¼N‐C6H4‐N¼)[U (
5‐C5H4Me)3] (compound 1) and 1,3‐[(
5‐C5H4Me)3U](¼N‐C6H4‐N¼)[U(
5‐C5H4Me)3] (compound 2). (Reprinted with permission from Rosen et al. (1990). Copyright 1990 American Chemical Society.)

The reduction reaction shown in equation (25.24) has been extended to bis (alkyl) complexes to generate a stable mononuclear hydride complex stabilized by added ligand (Duttera et al., 1982), as depicted in equation (25.27).

The complex [(Z5‐C5Me5)2U(m‐Cl)]3 reacts with a variety of Lewis bases to generate monomeric adducts, and will undergo metathesis reactions (Fig. 25.5).

Carbon‐based ancillary ligands

2811

Fig. 25.5 Reactions of [(
5‐C5Me5)2U(m‐Cl)]3 (Fagan et al., 1982).

Alkyl complexes have been prepared by reaction with alkyllithium reagents, but are unstable at room temperature, except for R ¼ CH(SiMe3)2. One of the most interesting reactions is that of [(Z5‐C5Me5)2U(m‐Cl)]3 with unsaturated substrates such as diphenylacetylene. In an apparent disproportionation, the reaction products include the metallacycle complex resulting from coupling of two alkyne ligands, as well as an equivalent amount of (Z5‐C5Me5)2UCl2. Finke et al. (1981a,b) have examined the oxidation of the base adduct

2812

Organoactinide chemistry: synthesis and characterization

(Z5‐C5Me5)2UCl(THF) with alkyl halides. Kinetic evidence supports an atom‐ abstraction oxidative addition mechanism to the coordinatively unsaturated (Z5‐C5Me5)2UCl. The rate of reaction is 104–107 faster than any known isolable transition metal system reacting by atom abstraction. A cationic bis(pentamethylcyclopentadienyl)uranium(III) complex has been reported (Boisson et al., 1997). The complex [(Z5‐C5Me5)2U(THF)2][BPh4] is generated by protonation of the complex (Z5‐C5Me5)2U[N(SiMe3)2] with [NH4] [BPh4]. A number of U(III) complexes containing the [Z5‐1,3‐(Me3Si)2C5H3] ligand have been prepared (Blake et al., 1986b, 1987) by reduction of U(IV) precursors with Na–Hg or n‐BuLi in toluene or hexanes [equation (25.28)].

In the presence of a coordinating ligand (e.g. TMEDA), a uranate salt ([Z5‐ (Me3Si)2C5H3](m‐Cl)2U(L)) (L ¼ ligand) is isolated (Blake et al., 1988). An expanded synthesis of these and related [Z5‐1,3‐(Me3C)2C5H3] complexes has been reported involving reduction of tetravalent precursors by t‐BuLi in hexanes (Lukens et al., 1999b,c). A number of the dimeric complexes have been structurally characterized (Fig. 25.6) (Lukens et al., 1999a). The solution behavior of a number of members of the class [{Z5‐1,3‐R2C5H3}2U(m‐X)]2 (R ¼ Me3Si or Me3C) have been examined by variable temperature NMR (Lukens et al., 1999b). The complexes exist as dimers in solution at all temperatures examined. The dimers react with Lewis bases to yield monomeric mono‐ or bis‐ ligand adducts (Blake et al., 1987; Beshouri and Zalkin, 1989; Zalkin and Beshouri, 1989); these serve as reagents in subsequent metathesis reactions (Blake et al., 1987). The complexes [{Z5‐1,3‐R2C5H3}2U(m‐OH)]2 (R ¼ Me3Si or Me3C) have been prepared by reaction of one equivalent of water with [Z5‐1,3‐(Me3Si)2 C5H3]3U and [Z5‐1,3‐(Me3C)2C5H3]2UH, respectively (Lukens et al., 1996).

Carbon‐based ancillary ligands

2813

Fig. 25.6 Crystal structure of [{
5‐1,3‐(Me3Si)2C5H3}2U(m‐F)]2. (Reprinted with permission from Lukens et al. (1999a). Copyright 1999 American Chemical Society.)

Upon heating, these complexes have been observed to undergo an unusual ‘oxidative elimination’ to yield the corresponding m‐oxo complexes [equation (25.29)]. ½fZ5 -1;3-R2 C5 H3 g2 Uðm-OHÞ2

100 C
H2

½fZ5 -1;3-R2 C5 H3 g2 Ufm-OÞ2

ð25:29Þ

R ¼ Me3 Si or Me3 C The kinetics of this process have been examined, and the reaction is found to be intramolecular, probably involving a stepwise a‐elimination process. The reagent UI3(THF)4 has proven valuable in generating mono(cyclopentadienyl) uranium(III) complexes (Avens et al., 2000). Reaction of one equivalent of UI3(THF)4 with K(C5Me5) results in the formation of the complex (Z5‐C5Me5)UI2(THF)3. In the solid state this complex exhibits a pseudo‐ octahedral mer, trans geometry, with the cyclopentadienyl group occupying the axial position.

2814

Organoactinide chemistry: synthesis and characterization

In the presence of excess pyridine, this complex can be converted to the analogous pyridine adduct, (Z5‐C5Me5)UI2(py)3. (Z5‐C5Me5)UI2(THF)3 will react further with K(C5Me5) to generate the bis(ring) product, (Z5‐C5Me5)2UI (THF), or will react with two equivalents of K[N(SiMe3)2] to produce (Z5‐ C5Me5)U[N(SiMe3)2]2. The solid state structure of the bis(trimethylsilyl)amide derivative reveals close contacts between the uranium center and two of the ˚ ]. methyl carbons [2.80(2), 2.86(2) A 5 Oxidation of (Z ‐C5Me5)UI2(THF)3 with CS2 or ethylene sulfide produces a complex of the formula [(Z5‐C5Me5)UI2(THF)3]2(S). This species undergoes slow decomposition in solution to yield a polynuclear complex (Clark et al., 1995):

(b)

Tetravalent chemistry

The tetravalent oxidation state dominates the cyclopentadienyl chemistry of the early actinide elements. Tetrakis(cyclopentadienyl) complexes were among the earliest actinide complexes prepared, and the complexes (Z5‐C5H5)4An are known for Th (Fischer and Treiber, 1962), Pa (Baumga¨rtner et al., 1969), U (Fischer and Hristidu, 1962), and Np (Baumga¨rtner et al., 1968). Although only the uranium and thorium compounds have been structurally characterized (Burns, 1974; Maier et al., 1993), IR spectral and X‐ray powder data confirm

Carbon‐based ancillary ligands

2815

that all four complexes are isostructural. (Z5‐C5H5)4U is found to be psuedo‐ ˚ . This is somewhat tetrahedral, with a mean U–Cring bond distance of 2.81(2) A longer than average U–Cring distances for other U(IV) cyclopentadienyl complexes, reflecting the degree of steric crowding. The related tetrakis(indenyl) thorium compound has also been reported (Rebizant et al., 1986). The thorium atom is bonded to the carbons of the five‐membered ring portion of the indenyl ligand, although not in a Z5 fashion. The shortest Th–C bond distances [Th–C ˚ vs 3.09(3) A ˚ ] are to the three non‐bridging carbon atoms, average ¼ 2.83(3) A leading to the overall designation of the rings as trihapto.

The first reported organoactinide complex was (Z5‐C5H5)3UCl (Reynolds and Wilkinson, 1956), a member of the extensive class of complexes represented as Cp3AnX. The complex was first prepared by the reaction of uranium tetrachloride with sodium cyclopentadienide in tetrahydrofuran. Comparable routes have been used to prepare (Z5‐C5H5)3NpCl (Karraker and Stone, 1979), although this complex has also been prepared by reaction of NpCl4 with (C5H5)2Be (Fischer et al., 1966). Alternative routes have since been reported for the generation of (Z5‐C5H5)3UCl (Marks et al., 1976). Tris(indenyl)uranium and tris(indenyl)thorium complexes have been prepared by metathesis reactions with K(C9H7) in THF (Burns and Laubereau, 1971; Laubereau et al., 1971; Goffart et al., 1975, 1981; Goffart and Duyckaerts, 1978). Since the first report of cyclopentadienyl complexes, attempts have been made to assess the nature of the bonding in these complexes from their chemical reactivity. In contrast to complexes of lanthanides and Group 3 metals, (Z5‐ C5H5)3UCl does not react with FeCl2 to produce ferrocene, and it decomposes relatively slowly in water. Although this is taken as some indication of increased covalency in chemical bonding, these complexes are still believed to be more ionic than the majority of d‐transition metal cyclopentadienyl complexes (Burns and Bursten, 1989). The molecular structure of several Cp3AnX complexes have

2816

Organoactinide chemistry: synthesis and characterization

been determined, as well as several structures of closely related tris(indenyl) actinide halide complexes. Some comparative structural information is provided in Table 25.3, and a typical structure represented by (Z5‐C5H5)3UBr is presented in Fig. 25.7.

Table 25.3 Structural information for Cp3AnX complexes. Compound

M–C ˚) (average) (A

˚) M–X (A

References

(Z ‐C5H5)3UCl (Z5‐C5H5)3UBr (Z5‐C5H5)3UI (Z5‐C5H4CH2Ph)3UCl [Z5‐(Me3Si)2C5H3]3UCl (Z5‐C5Me4H)3UCl (Z5‐C5Me5)3UF (Z5‐C5Me5)3UCl [Z5‐(Me3Si)2C5H3]3ThCl [Z5‐(Me3Si)2C5H3]2(C5Me5)ThCl [Z5‐(Me2‐tBuSi)2C5H3]3ThCl {Z5‐[(Me3Si)2CH]C5H4}3ThCl (Z5‐C9H7)3UBr (Z5‐C9H7)3UI (Z5‐C9HMe6)3UCl (Z5‐C9H6Et)3ThCl

2.74 2.72(1) 2.73(3) 2.733(1) 2.77(1) 2.79(1) 2.829(6) 2.833(9) 2.84(1) 2.84(2) 2.85(1) 2.83(1) 2.71(2), 2.85(2) 2.68(2), 2.88(2) – 2.78(1), 2.93(1)

2.559(16) 2.820(2) 3.059(2) 2.627(2) 2.614(2) 2.637 2.43(2) 2.90(1) 2.651(2) 2.657(5) 2.648(2) 2.664(2) 2.747(2) 3.041(1) 2.621(1) 2.673(3)

Wong et al. (1965) Spirlet et al. (1989a) Rebizant et al. (1991) Leong et al. (1973) Blake et al. (1998) Cloke et al. (1994) Evans et al. (2000) Evans et al. (2000) Blake et al. (1998) Blake et al. (1998) Blake et al. (1998) Blake et al. (1998) Spirlet et al. (1987) Rebizant et al. (1988) Spirlet et al. (1992a) Spirlet et al. (1990)

5

Fig. 25.7 Crystal structure of (
5‐C5H5)3UBr (Spirlet et al., 1989a). (Reprinted with permission of the International Union of Crystallography.)

Carbon‐based ancillary ligands

2817

All complexes possess pseudo‐tetrahedral geometry, with the halide ligand on an approximate three‐fold axis of symmetry. The An–C and An–X bond lengths are consistent for most of the complexes; Th–C and Th–X values are slightly larger, as would be expected for the larger ionic radius. The average U–Cring and U–X bond lengths are longer than would be expected in complexes (Z5‐ C5Me5)3UX (X ¼ Cl, F); the U–Cl bond length in (Z5‐C5Me5)3UCl is ˚ longer than that for related complexes. The origin of this difference >0.15 A appears to be significant steric crowding in the molecule. Interligand repulsions between the bulky pentamethylcyclopentadienyl ligands results in the most signficant distortion from tetrahedral geometry; the cyclopentadienyl rings lie within a crystallographic plane of symmetry, requiring the angle X–U–Ccentroid to be rigorously 90 . This in turn results in repulsion between the rings and the halide, lengthening the bond. As observed in the An(indenyl)4 complexes, the tris(indenyl) complexes all evidence a ‘slip’ of the rings towards a trihapto bonding, resulting in two separate sets of U–C distances. The compound (C9HMe6)3UCl possesses a highly substituted hexamethylindenyl ligand (Spirlet et al., 1992a). The steric encumbrance associated with this ligand induces a further slippage of the ring; the resulting complex has indenyl rings that are essentially monohapto towards ˚ (Fig. 25.8). the metal center, with mean U–C bonds of 2.622(6) A A number of approaches have been employed to generate derivatives of Cp3AnX (von Ammon et al., 1969; Kanellakopulos et al., 1974b; Marks and Kolb, 1975; Fischer and Sienel, 1976, 1978; Bagnall et al., 1982a,b; Spirlet et al., 1996). Prototype reactions include protonation of (Z5‐C5H5)4U [equation (25.30)] and metathesis [equation (25.31)]. ðZ5 - C5 H5 Þ4 U þ HCN ðZ5 - C5 H5 Þ3 An
Cl þ KX

ðZ5 - C5 H5 Þ3 U
CN þ C5 H6




ðZ5 - C5 H5 Þ3 An
X þ KCl


An ¼ U; Np; Pu; X ¼ CN ; CNBH
3 ; NCS

ð25:30Þ

ð25:31Þ

Reactions such as that between (Z5‐C5H5)3UCl and KCN may be carried out in water (Bagnall et al., 1982b), indicating the stability of the metal–ligand bonding in these complexes. In fact, it has been suggested that (Z5‐C5H5)3UCl ionizes in water to yield the five‐coordinate adduct [(Z5‐C5H5)3U(H2O)2]þ (Fischer et al., 1982). This spurred further interest in investigating other five coordinate species, e.g. [(Z5‐C5H5)3UXY]–. The anionic complexes [(Z5‐C5H5)3An(NCS)2]– (An ¼ U, Np, Pu) can be isolated, provided that the cation is sufficently large (Bagnall et al., 1982b). Spectrophotometric and other evidence indicates a trigonal–bipyramidal geometry for these species. The assignment of the geometry of these species is further supported by structural characterization of neutral base adducts (Z5‐C5H5)3AnXL, such as (Z5‐C5H5)3U(NCS)(NCMe) (Fischer et al., 1978; Aslan et al., 1988) or (Z5‐C5H5)3U(NCBH3)(NCMe) (Adam et al., 1990);

2818

Organoactinide chemistry: synthesis and characterization

Fig. 25.8 Crystal structure of (C9HMe6)3UCl (Spirlet et al., 1992a). (Reprinted with permission of the International Union of Crystallography.)

these complexes exibit a trigonal‐bipyramidal geometry, with the smaller ligands adopting the axial positions. Cationic species can also be produced. The compound [(Z5‐C5H5)3U (NCMe)2]þ has been isolated as a [BPh4]– salt by the reaction of (Z5‐ C5H5)3UCl and NaBPh4 in water/acetonitrile mixtures (Aslan et al., 1988). The cationic complex [(Z5‐C5H5)3U(THF)]BPh4 was generated by protonation of the neutral amide precursor with [NHEt3]þ as illustrated in equation (25.32) (Berthet et al., 1995). THF

ðZ5 -C5 H5 Þ3 U
NR2 þ ½HNEt3 ½BPh4  ½ðZ5 - C5 H5 Þ3 UðTHFÞ½BPh4  þ HNR2 þ NEt3 R ¼ Me; Et

ð25:32Þ

Similarly, treatment of precursor alkyl or amide complexes with pyridinium triflate gives rise to the triflate complex (Z5‐C5H5)3U(O3SCF3) (Berthet et al., 2002).

Carbon‐based ancillary ligands

2819

The crystal structure of the tBuCN adduct has also been determined (Berthet et al., 1998). Metathesis and protonation routes have been used to generate L3An(IV) (L ¼ cyclopentadienyl, indenyl) complexes containing alkoxide (OR), amide (NR2), phosphide (PR2), and thiolate (SR) ligands (Jamerson et al., 1974; Goffart et al., 1977; Karraker and Stone, 1979; Arduini et al., 1981; Paolucci et al., 1985; Leverd et al., 1996; De Ridder et al., 1996). Both magnetic susceptibility measurements and 237Np Mo¨ssbauer spectroscopy have been employed to assess the qualitative order of ligand field strengths for a variety of ligands in the complexes (Z5‐C5H5)3NpX (Karraker and Stone, 1979). The
identified order of donor strength from this study is X ¼ Cl
 BH
4 > OR >

R > C 5 H5 . One of the best studied classes of (Z5‐C5H5)3AnR (Th, U, Np) complexes is that containing alkyl or aryl ligands. The literature on alkyl complexes is extensive (e.g. Brandi et al., 1973; Calderazzo, 1973; Gabala and Tsutsui, 1973; Marks et al., 1973; Tsutsui et al., 1975; Marks, 1979). The complexes are most often prepared by reaction of (Z5‐C5H5)3AnX (X ¼ halide) with Grignard [equation (25.33)] or alkyllithium [equation (25.34)] reagents. ðZ5 - C5 H5 Þ3 An
X þ RMgX0 ðZ5 - C5 H5 Þ3 An
X þ LiR

ðZ5 - C5 H5 Þ3 An
R þ MgXX0 ð25:33Þ ðZ5 - C5 H5 Þ3 An
R þ LiX

ð25:34Þ

Comparable indenylactinide derivatives have also been prepared (e.g. Goffart et al., 1977). While there is a dearth of thermally stable U(IV) hydride complexes, the complexes [Z5‐(Me3Si)C5H4]3UH and [Z5‐(Me3C)C5H4]3UH can be obtained by reaction of the corresponding chlorides with KBEt3H (Berthet et al., 1992b). The molecular structures of several (Z5‐C5H5)3AnR complexes have been determined; compounds display pseudo‐tetrahedral geometries. Typical ˚ . All three cyclopenmetal–carbon bond lengths for the alkyl ligand are 2.40 A tadienyl ligands are pentahapto, which nearly saturates the coordination environment of the metal center, as evidenced by the observation that allyl ligands can only be accomodated in a simple s‐bonded fashion (Halstead et al., 1975) as shown in Fig. 25.9. This monohapto geometry is also the low‐temperature limiting structure for (Z5‐C5H5)3U(allyl) in solution (Marks et al., 1973) although at room temperature the allyl ligand is fluxional, presumably interconverting sites by means of a p‐bound intermediate. The relative coordinative saturation is reflected in the thermal stabilities of alkyl derivatives: primary > secondary > tertiary. Primary alkyl ligands are resistant to b‐hydride elimination; thermal decomposition is presumed to take place through U–C bond homolysis and abstraction of a ring proton by the caged alkyl radical (although metal‐containing products have not been definitively identified).

2820

Organoactinide chemistry: synthesis and characterization

Fig. 25.9 Crystal structure of (
5‐C5H5)3U [CH2C(CH3)2]. (Reprinted with permission from Halstead et al. (1975). Copyright 1975 American Chemical Society.)

Further indication of the steric saturation of the complex may be found in the observation that reaction of (Z5‐C5H5)3UR with excess alkyllithium does not result ultimately in the formation of anionic bis(alkyl) complexes. Rather, reaction products either result from alkyl exchange (Tsutsui et al., 1975) or reduction of the metal center (Arnaudet et al., 1983, 1986) as shown in equation (25.35).

It has been reported that the complex [(Z5‐C5H5)3UMe2]– can be observed as an intermediate in solution by NMR spectroscopy (Villiers and Ephritikhine, 1991). Other derivatives of the Group 14 elements have been prepared. Reaction of (Z5‐C5H5)3UCl with Li(EPh3) affords the silyl- and germyluranium derivatives (Z5‐C5H5)3U(EPh3) [E ¼ Si (Porchia et al., 1986, 1989), E ¼ Ge (Porchia et al., 1987)], whereas the stannyl analog (Z5‐C5H5)3U(SnPh3) was best made from a the reaction of (Z5‐C5H5)3U(NEt2) with HSnPh3. It can also be made from the transmetallation reaction of HSnPh3 with (Z5‐C5H5)3U(EPh3) (E ¼ Si, Ge) (Porchia et al., 1989). The silyl compound is very reactive; under a number of conditions it can be transformed into (Z5‐C5H5)3U(OSiPh3). Insertion of xylylisocyanide into U–E bonds generates the corresponding Z2‐iminoacyl complexes [(Z5‐C5H5)3U{C(EPh3) ¼ N(xylyl)}] (E ¼ Si, Ge).

Carbon‐based ancillary ligands

2821

Several groups have conducted investigations of the thermochemistry of organoactinide complexes in order to determine the enthalpies of metal–ligand bonds, and thereby shed light on the nature of bonding and the anticipated reaction patterns. An excellent overview of available data on organouranium complexes has appeared recently (Leal et al., 2001). Data compiled for tris (cyclopentadienyl)uranium(IV) complexes are presented in Table 25.4. Values tabulated in Leal et al. (2001) are based upon several types of measurements: solution titration experiments involving reaction with iodine or alcohols, static bomb combustion calorimetry, or gas‐phase or solution equilibrium experiments. A few general trends may be noted. The enthalpy values for all U–C (sp3) bonds are relatively consistent; U–C(sp2) and U–C(sp) bonds increase in strength, as might be expected for a bond involving a higher degree of s‐orbital involvement. While the bonds involving all Group 14 element bonds are reasonably close in energy, uranium bonds to Group 16 or Group 17 elements are somewhat stronger. The reason for the disparity between D(U–S) for the EtS– and tBuS– may be due to the greater steric bulk associated with the latter. Comparable experiments have been carried out for the complexes (Z5‐ C5H5)3ThR (Sonnenberger et al., 1985); results of these measurements are found in Table 25.5. The thorium–carbon bond strengths are found to be overall higher than for comparable uranium species. This has been rationalized in terms of the greater stability of the U(III) complexes, resulting from homolytic loss of an alkyl radical. The reaction of carbon monoxide with (Z5‐C5H5)3AnR (An ¼ Th, U; R ¼ alkyl, hydride) yields an acyl complex as shown in equation (25.36).

2822

Organoactinide chemistry: synthesis and characterization

Table 25.4 Bond dissociation enthalpies for Cp3UX and (indenyl)3UX complexes.a Compound

R

(Z ‐C5H5)3UR

SiPh3 GePh3 SnPh3 Fe(CO)2Cp Ru(CO)2Cp Cp i‐Bu

D(U–R) (kJ mol
1)

Reference

156  18 163  19 156  17 129  13 169  17 299  10b,c D[Cp3U–Cp] – (70  35)c,d D[Cp3U–Cp] þ (247  28)c,d D[Cp3U–Cp] þ (73  31)c,d

Nolan et al. (1991) Nolan et al. (1991) Nolan et al. (1991) Nolan et al. (1991) Nolan et al. (1991) Telnoy et al. (1979) Telnoy et al. (1989)

SEt S‐t‐Bu H

185  2 152  8 168  8 149  8 223  10 363 262  1 265.6  4.3 266  9 158  8 253.7  5.1

Schock et al. (1988) Schock et al. (1988) Schock et al. (1988) Schock et al. (1988) Schock et al. (1988) Schock et al. (1988) Schock et al. (1988) Jemine et al. (1992) Jemine et al. (1994) Jemine et al. (1994) Jemine et al. (1992)

[Z5‐(Me3C)C5H4]3UR

H I SEt

251.6  5.7 246.3  5.3 252  8

Jemine et al. (1992) Jemine et al. (1992) Jemine et al. (1994)

(Z5‐C9H7)3UR

Me OCH2CF3 I

195  5 301  9 267  3

Bettonville et al. (1990) Bettonville et al. (1989, 1990) Bettonville et al. (1990)

(Z5‐C9H6Et)3UR

Me

187  6

Bettonville et al. (1989, 1990)

(Z ‐C9H6SiMe3)3UR

SEt

158  8

Jemine et al. (1994)

5

OBu Cl [Z5‐(Me3Si)C5H4]3UR

5

Me Bu CH2SiMe3 CH2Ph CH¼CH2 CCPh I

Telnoy et al. (1989) Telnoy et al. (1989)

a

Determined using reaction–solution calorimetry unless otherwise indicated. Mean bond dissociation enthalpy. c Static bomb combustion calorimetry. d This notation means that the bond is the stated amount stronger or weaker than the first bond dissociation enthalpy in U(Z5‐C5H5)4. b

These reactions have been studied mechanistically (Sonnenberger et al., 1984) for a series of thorium deriatives (R ¼ i‐Pr, s‐Bu, neo‐C5H11, n‐Bu, CH2Si(CH3)3, Me, and CH2C6H5). Under the conditions employed, insertion is first order in thorium complex and first order in CO. The relative rates of insertion for

Carbon‐based ancillary ligands Table 25.5

2823

Bond dissociation enthalpies for Cp3ThR complexes.

Compound

R

D(Th–R) (kJ mol
1)

(Z5‐C5H5)3ThR

CH3 CH(CH3)2 CH2C(CH3)3 CH2Si(CH3)3 CH2C6H5

374.9 (4.6) 342.2 (10.9) 333.0 (11.7) 367.8 (15.1) 315.1 (9.2)

the ligands was found to be i‐Pr > s‐Bu > neo‐C5H11 > n‐Bu > CH2Si(CH3)3 > Me > CH2C6H5. The relative rates of insertion correlate reasonably well with the bond enthalpies reported in Table 25.5, and as expected, were accelerated by photolysis. Where R ¼ s‐Bu, neo‐C5H11, n‐Bu, Me, and CH2C6H5, the chief isolated product was the insertion (Z2‐acyl) product shown in equation (25.36). This complex has been discussed as having a ‘carbene‐like’ resonance form:

In the case of i‐Pr and CH2Si(CH3)3, however, the only products that could be isolated were those arising from 1,2‐rearrangement [equations (25.37)–(25.38)].

2824

Organoactinide chemistry: synthesis and characterization

A comparative study of CO2 insertion to generate carbonate complexes showed that carboxylation is significantly slower than carbonylation, and exhibits different trends in the dependence of rate on the alkyl ligand (Sonnenberger et al., 1984). Similar insertion reactions of carbon monoxide have been investigated for complexes of the type (Z5‐C5H4R)3UR0 (Paolucci et al., 1984; Villiers and Ephritikhine, 1994). Villiers and Ephritikhine performed mechanistic studies, which showed that the insertion reaction appears first order under conditions of excess CO. The rate of insertion varies as a function of the cyclopentadienyl ring, with the rate decreasing in the order R ¼ H > Me > iPr > tBu, as might be expected from steric considerations. The rate also depends on the identity of the alkyl ligand in the unusual order R0 ¼ n‐Bu > tBu > Me > iPr. The resulting Z2‐ acyl product was not stable and rearranged to yield alkylbenzenes C6H4RR0 , suggested to arise from ring enlargement of the cyclopentadienyl ligand by incorporation of the CR0 fragment. The reaction was observed to follow first‐order kinetics, with the rate varying with the alkyl ligand in the order R0 ¼ Me > n‐Bu > iPr > tBu. In benzene solvent, the rates varied with R in the order tBu > iPr > Me > H, while the opposite order was observed in THF solvent. For a given solvent, the relative proportions of meta‐ and para‐ isomers were invariant with R and R0 . The proposed mechanism involved a cyclopropyl intermediate, resulting from addition of the oxycarbene group to the cyclopentadienyl ligand.

Carbon monoxide will also insert into the U–H bond of (Z5‐C5H4SiMe3)3UH (Berthet and Ephritikhine, 1992). As shown in equation (25.39), the initial product is believed to be a formate complex, which reacts further with the hydride to yield a dioxymethylene species.

Carbon‐based ancillary ligands

2825

Isoelectronic isocyanide ligands will also undergo insertion into uranium–carbon or uranium–nitrogen bonds (Dormond et al., 1984; Zanella et al., 1987) to yield Z2‐iminoalkyl and Z2‐iminocarbamoyl adducts.

A unique class of (Z5‐C5H5)3AnR complexes has been generated by Cramer et al. (1981, 1983, 1988). Reaction of (Z5‐C5H5)3AnCl with lithium ylide or phosphine imide salts yields the following species [equations (25.40) and (25.41)]:

The molecular structure of the uranium phosphine imide complex is shown in Fig. 25.10. While the overall geometry of these complexes is similar to most (Z5‐ C5H5)3AnX compounds, these species are characterized by unusually short ˚ U–C(N) bonds. The U–C(1) bond distance in the ylide complex is 2.29(3) A [significantly shorter than the average uranium–alkyl bond in (Z5‐C5H5)3UR ˚ ], and the U–N bond distance in the phosphine imide complexes, ca. 2.43 A ˚ . Two useful descriptions have been presented for the complex is 2.07(2) A bonding in these complexes, consistent with the resonance forms depicted for the phosphoylide complex:

One model would suggest that a multiple bond is formed between the metal and the carbon. This is supported by theoretical calculations at the extended Hu¨ckel level (Tatsumi and Nakamura, 1984; Cramer et al., 1988) that reveal an important overlap population in the U–C bond of the phosphoylide complex and U–N bond of the phosphine imine complex. A second description would

2826

Organoactinide chemistry: synthesis and characterization

Fig. 25.10 Crystal structure of (
5‐C5H5)3U[NP(C6H5)3]. (Reprinted with permission from Cramer et al. (1988). Copyright 1988 American Chemical Society.)

suggest that the compounds are principally ionic, with the short U–C bond attributed to the Coulombic attraction between the electropositive metal and the residual charge on the ligand, as well as the smaller radial extent of the sp2‐ hybridized ligand‐based orbital. In reality, these models are probably merely extreme descriptions of the true bonding situation, and both are valid. Unlike other complexes with metal–ligand multiple bonds (vide infra), the phosphoylide complex reacts as a U(IV) alkyl, however, undergoing a variety of insertion reactions (Cramer et al., 1982, 1984a,b, 1986, 1987a,b) as shown in Fig. 25.11. Complexes of the general formula (Z5‐C5H5)2AnX2 have proven very difficult to synthesize, given the instability of the metallocene complex with respect to ligand redistribution to yield mono‐ and tris(ring) species (Kanellakopulos et al., 1974c). Alternative approaches to generate complexes of this formula have generally involved introduction of the cyclopentadienyl ligands in the presence of other ligands that inhibit redistribution, as in equations (25.42)– (25.45) (Jamerson and Takats, 1974; Zanella et al., 1977, 1987).

Carbon‐based ancillary ligands

2827

The bis(indenyl) complex (Z5‐C9H7)2U(BH4)2 has been generated by the reaction of Na(C9H7) with U(BH4)2, and the structure reported (Spirlet et al., 1989b). Peralkylated indenyl ligands have also been used to produce metallocene derivatives. Reaction of ThCl4 with Li(C9Me7) yields the dichloride complex (Z5‐C9Me7)2ThCl2 (Trnka et al., 2001). This species serves as a reagent for the synthesis of a number of derivatives, including (Z5‐C9Me7)2ThMe2, (Z5‐C9Me7)2Th(NMe2)2, (Z5‐C9Me7)2Th(NC4H4)2, and (Z5‐C9Me7)2Th(Z3‐ H3BH)2. The permethylindenyl ligand in all of these derivatives binds with nearly an idealized Z5‐coordination mode, with the Th–C bonds for the five‐ ˚ . The membered ring of the indenyl ligands varying by no more than 0.05 A indenyl rings are not entirely planar, indicating that there are steric repulsions between the proximal methyl groups of the two (Z5‐C9Me7) ligands, although these distortions are smaller than in related zirconium compounds, consistent with the larger radius of the thorium ion. The principal synthetic means employed to stabilize bis(cyclopentadienyl) actinide complexes against ligand redistribution has been to use substituted cyclopentadienyl ligands. The first reports of successfully stabilizing bis(cyclopentadienyl) complexes involved the use of peralkylated derivatives (C5Me5: Manriquez et al., 1978; Fagan et al., 1981a; C5Me4Et: Green and Watts, 1978). The pentamethylcyclopentadienyl ligand has come to be one of the most widely used ligands in organoactinide chemistry due to the thermal stability, solubility, and crystallinity of its compounds. Initial synthetic routes involved alkylation of the metal tetrahalides by Grignard [equation (25.46)] or tin [equation (25.47)] reagents: AnCl4 þ 2ðC5 Me5 ÞMgCl  THF

UCl4 þ 2ðC5 Me4 EtÞSnBu3

ðZ5 -C5 Me5 Þ2 AnCl2 þ 2MgCl2 ð25:46Þ An ¼ Th; U ðZ5 -C5 Me4 EtÞ2 UCl2 þ 2Bu3 SnCl ð25:47Þ

The molecular structure of (Z5‐C5Me5)2UCl2 has been determined (Spirlet et al., 1992b; Fig. 25.12), as have those of (Z5‐C5Me5)2ThX2 (X ¼ Cl, Br, I) (Spirlet et al., 1992b; Rabinovich et al., 1997, 1998). All exist as monomeric complexes with a pseudo‐tetrahedral, ‘bent metallocene’ geometry. The complex (Z5‐C5Me5)2NpCl2 was generated in a manner similar to that in equation (25.46) (Sonnenberger and Gaudiello, 1986); reaction of the tetrahalide with Tl(C5Me5) had previously been reported to yield a THF

2828

Organoactinide chemistry: synthesis and characterization

Fig. 25.11 Reactions of (
5‐C5H5)3U [(CH)P(CH3)(C6H5)(R)], where R ¼ CH3, C6H5.

adduct (Karraker, 1983). The electrochemistry of (Z5‐C5Me5)2NpCl2 reveals a reversible one‐electron reduction wave at –0.68 V versus a ferrocene internal standard. A one‐electron reversible reduction is also reported for (Z5‐ C5Me5)2UCl2 at –1.30 V (Finke et al., 1982). Interestingly, the difference in

Carbon‐based ancillary ligands

2829

Fig. 25.12 Crystal structure of (
5‐C5Me5)2UCl2 (Spirlet et al., 1992b). (Reprinted with permission of the International Union of Crystallography.)

the U and Np non‐aqueous reduction potentials is very close to the difference in their aqueous reduction potentials. Other substituted cyclopentadienyl ligand sets have been generated and used to stabilize tetravalent metallocenes, particularly [1,3‐(Me3Si)2C5H3] and [1,3‐ (Me3C)2C5H3]. The metal complexes have been prepared by reaction of the metal tetrahalides with either cyclopentadienyllithium reagents [equation (25.48)] (Blake et al., 1995) or the substituted magnesocenes [equation (25.49)] (Lukens et al., 1999a). AnCl4 þ 2Li½1; 3-ðMe3 SiÞ2 C5 H3 

½Z5 -1;3-ðMe3 SiÞ2 C5 H3 2 AnCl2 þ 2LiCl An ¼ Th; U ð25:48Þ

UCl4 þ ð1; 3-R2 C5 H3 Þ2 Mg

ðZ5 -1;3-R2 C5 H3 Þ2 UCl2 þ MgCl2 ð25:49Þ R ¼ SiMe3 ; CMe3

In the latter case, all metatheses were performed with the chloride salt, and the chloride product was subsequently converted to other halides by reaction with XSiMe3 (X ¼ Br, I) or BF3  Et2O. The molecular structures of the complexes [Z5‐1,3‐R2C5H3]2UX2 (R ¼ SiMe3, X ¼ F, Cl, Br; R ¼ tBu, X ¼ F, Cl) have

2830

Organoactinide chemistry: synthesis and characterization

been reported, as has the structure of [Z5‐1,3‐(Me3Si)2C5H3]2ThCl2. All exist as monomers in the solid state, except for [{Z5‐1,3‐(Me3Si)2C5H3}2UF(m‐F)]2, which is a dimer (see Fig. 25.6). A detailed study of the solution behavior of the complexes has been conducted (Lukens et al., 1999a). Both fluoride complexes are found to display a monomer–dimer equilibrium in solution. The 1H NMR chemical shifts and magnetic susceptibility data for the complexes further suggest that the ligands [1,3‐(Me3Si)2C5H3] and [1,3‐(Me3C)2C5H3] produce significantly different electronic environments at the metal center. Despite the kinetic stability that the sterically larger cyclopentadienyl ligands provide, in a limited number of cases base adducts have been generated. The complex (Z5‐C5Me5)2UCl2(pz) (pz ¼ pyrazole) has been reported (Eigenbrot and Raymond, 1982), as has the chelating phopshine adduct [Z5‐1,3‐ (Me3Si)2C5H3]2ThCl2(dmpe) (Edelman et al., 1995). The complex (Z5‐ C5Me5)2U(OTf)2(H2O) (OTf ¼ trifluoromethylsulfonate) was isolated in low yield from the reaction of (Z5‐C5Me5)2UMe2 with triflic acid (Berthet et al., 1998). In compounds of the formula (Z5‐C5Me5)2UX2(L) (L ¼ neutral ligand), the coordinated base generally occupies the central position in the equatorial wedge. A second strategy for kinetically stabilizing actinide metallocenes against redistribution reactions is to employ the chelate effect by linking the two cyclopentadienyl rings (ansa metallocenes). The most common of these ligands are the ansa ligand sets.

The molecular structure of [(Z5‐C5Me4)2(m‐SiMe2)]U(m‐Cl)4[Li(TMEDA)]2 (TMEDA ¼ N,N,N0 ,N0 ‐tetramethylethylenediamine) is shown in Fig. 25.13. As for most ansa metallocenes, the complex is characterized by a more acute centroid–metal–centroid angle (114.1 ) than non‐linked metallocenes (133– 138 ). This leaves more room in the equatorial wedge, accounting for the ability to accommodate four bridging chloride ligands. The more open coordination environment generated by ‘tying’ back the cyclopentadienyl ligands also enhances the reactivity of the resulting metal complex. The complex [(Z5‐C5Me4)2 (m‐ SiMe2)]Th(n‐Bu)2, generated by reaction of the structurally characterized precursor [(Z5‐C5Me4)2(m‐SiMe2)]Th(m‐Cl)4[Li(DME)]2 with n‐BuLi, was found to be a very active catalyst for the dimerization of terminal alkynes and the hydrosilylation of terminal alkynes or alkenes with PhSiH3 (Dash et al., 2001).

Carbon‐based ancillary ligands

2831

Fig. 25.13 Crystal structure of [(
5‐C5Me4)2(m‐SiMe2)]U(m‐Cl)4[Li(TMEDA)]2 (Schnabel et al., 1999). (Reprinted with permission from Elsevier.)

Other ligand sets have been explored that append Lewis base groups to the ring that will coordinate to the metal center to help prevent ring redistribution. A bis(cyclopentadienyl) substituted pyridine ligand has been used to generate the complex [Z5‐C5H4(CH2)]2(C6H5N)UCl2 (Paolucci et al., 1991), and the pendant ether complex [Z5‐C5H4(CH2CH2OCH3)]2UCl2 has also been reported (Deng et al., 1996):

Metathesis and protonation reactions have been employed to produce a wide array of derivatives of the metallocene unit. A limited number of complexes exist with bonds to Group 14 elements other than carbon. Reaction of (Z5‐ C5Me5)2ThCl2 with the bulkyl silyl salt (THF)3Li[Si(SiMe3)3] yields an unstable complex (Z5‐C5Me5)2Th(Cl)[Si(SiMe3)3] that could be trapped by reaction with two equivalents of carbon monoxide to produce a ketene complex (Z5‐ C5Me5)2Th(Cl)[O–C(¼C¼O)Si(SiMe3)3].

2832

Organoactinide chemistry: synthesis and characterization

The analogous silyl compound (Z5‐C5Me5)2ThCl(SitBuPh2) could be isolated and its reaction with CO gave a similar silylthoroxyketene compound, and in this case the transient Z2‐acyl complex (Z5‐C5Me5)2ThCl[Z5‐CO(SitBuPh2)] could be detected (Radu et al., 1995). Metathesis [equations (25.50), (25.52), and (25.53)] and protonation [equations (25.42) and (25.51)] reactions are the most widely used routes to generate metallocene amide complexes (Fagan et al., 1981a,b; Eigenbrot and Raymond; 1982).

Metallocene phosphide complexes have been generated by metathesis routes [equations (25.54) and (25.55)] (Wrobleski et al., 1986a; Hall et al., 1993).

Carbon‐based ancillary ligands

2833

For the bis(trimethylsilyl)phosphide substituent, a bis(phosphido) complex cannot be produced. Solution 1H NMR spectra indicate that there is restricted rotation about the An–P bond at room temperature. The complexes (Z5‐ C5Me5)2AnMe[P(SiMe3)2] decompose thermally by elimination of methane to generate a metallacyclic complex:

The metallocene framework has also been integral to the isolation of organoimido and phosphinidene complexes. Comproportionation of U(III) and U(V) metallocenes results in the formation of uranium(IV) organoimido complexes [equation (25.56)] (Brennan et al., 1988b).

The molecular structure of [(Z5‐MeC5H4)2U(m‐NPh)]2 is shown in Fig. 25.14. The complexes exist as centrosymmetric dimers with asymmetric bridging organoimido ligands; the degree of asymmetry in the U–N bonds depends on the identity of the imido substituent. It is only recently that terminal organoimido complexes of U(IV) have been isolated (Arney and Burns, 1995). a‐Elimination reactions have been employed to generate the monoimido complex (Z5‐C5Me5)2U(¼N‐2,4,6‐tBu3C6H2) [equation (25.57)].

The complex is isolated even from ethereal solvents as a base‐free species. ˚ ], and a large The complex displays a very short U–N bond distance [1.95(1) A

2834

Organoactinide chemistry: synthesis and characterization

Fig. 25.14 Crystal structure of [(
5‐MeC5H4)2U(m‐NPh)]2. (Reprinted with permission from Brennan et al. (1988b). Copyright 1988 American Chemical Society.)

U–N–C angle [162.3(10) ]. Unlike the phosphoylide and phosphine imide complexes described previously, the organoimido complex is relatively inert; it does not undergo insertion reactions, suggestive of a bond order greater than 1. The steric bulk of the aryl group is important in stabilizing a base‐free organoimido complex; the smaller (Z5‐C5Me5)2U(¼N‐2,6‐iPr2C6H3) is best isolated as the THF adduct, and the parent phenylimido has only been isolated as a uranate salt, [Li(TMEDA)][(Z5‐C5Me5)2U(¼NC6H5)Cl]. Organoimido complexes of U(IV) and Th(IV) have been implicated as intermediates in the catalytic intermolecular hydroamination of terminal alkynes (Straub et al., 1996, 2001). It has been proposed that monoimido derivatives of the formula (Z5‐C5Me5)2An (¼NR0 ) are formed in the reaction of (Z5‐C5Me5)2AnMe2 with primary amines R0 NH2. These undergo metathesis reaction with alkynes to yield four‐ membered azametallacyclic intermediates, which can undergo subsequent amine protonation (with isomerization) to yield the product imines. The mechanism of this reaction is discussed further in Chapter 26. Although the organoimido intermediates involving aliphatic amines have not been isolated, analogs such as (Z5‐C5Me5)2Th(¼N‐2,6‐Me2C6H3)(THF) have been structurally

Carbon‐based ancillary ligands

2835

characterized (Haskel et al., 1996; Straub et al., 2001). As in the case of the uranium organoimido complex, the thorium complex displays a short Th–N ˚ ] and a near‐linear Th–N–Cipso angle (171.5(7) ). bond [2.045(8) A Similarly, bridging actinide phosphinidene complexes predated their terminal counterparts. The hydride complex [(Z5‐C5Me5)2UH2]2 reacts with P(OMe)3 to generate a bridging phosphinide complex [(Z5‐C5Me5)2U(OMe)]2(m‐PH) by P–O cleavage with sacrificial formation of (Z5‐C5Me5)2U(OMe)2 [equation (25.58)] (Duttera et al., 1984).

A terminal phosphinidene complex has also been reported (Arney et al., 1996). Reaction of (Z5‐C5Me5)2U(Me)Cl with KPH(2,4,6‐tBu3C6H2) in the presence of trimethylphosphine oxide yields the base adduct of the phosphinidene complex (Z5‐C5Me5)2U(¼P‐2,4,6‐tBu3C6H2)(OPMe3) (Fig. 25.15). ˚ ]. The U–P–C angle The complex displays a short U–P distance [2.562(3) A  143.7(3) ; the nonlinear angle is not unusual in comparison to d‐transition metal terminal phosphinidene complexes. No product is isolated in the absence of coordinating base, except for when the ancillary ligand set is [(Z5‐C5Me4)2(m‐ SiMe2)]. In the case of the less congested ansa‐metallocene; a phosphinidene‐ bridged dimer [{(Z5‐C5Me4)2(m‐SiMe2)}U(m‐PR)]2 (R ¼ 2,4,6‐tBu3C6H2) is generated.

Fig. 25.15 Crystal structure of (
5‐C5Me5)2U(¼P‐2,4,6‐t‐Bu3C6H2)(OPMe3). (Reprinted with permission from Arney et al. (1996). Copyright 1996 American Chemical Society.)

2836

Organoactinide chemistry: synthesis and characterization

An interesting series of polypnictide complexes have been generated by the reaction of (Z5‐1,3‐tBu2C5H3)2Th(Z4‐C4H6) with P4 or As4. The main group elements react to generate a hexapnictide complex: [(Z5‐1,3‐tBu2C5H3)2 Th]2(m,Z3,Z3‐E6) (E ¼ P, As) (Scherer et al., 1991, 1994).

In the presence of magnesium chloride, however, only the complex: [(Z5‐ 1,3‐tBu2C5H3)2Th](m,Z3‐P3)[Th(Cl)(Z5‐1,3‐tBu2C5H3)2] is formed in the reaction with phosphorus.

One of the earliest descriptions of metallocene thiolate complexes involved reactions of (Z5‐C5H5)2U(NEt2)2 with monothiols and dithiols (Jamerson and Takats, 1974). While compounds with the chelating thiols are stable (generally dimers), compounds of monodentate thiols (Z5‐C5H5)2U(SR)2 were reported to

Carbon‐based ancillary ligands

2837

be unstable and decomposed to form (Z5‐C5H5)2U(SR). Two other reports of bis (pentamethylcyclopentadienyl) metallocene dithiolates have been appeared: (Z5‐C5Me5)2Th(SPr)2 (Lin et al., 1988) and (Z5‐C5Me5)2U(SR)2 (R ¼ Me, iPr, t Bu, Ph) (Lescop et al., 1999). Two reports have appeared featuring cyclopentadienyl‐supported actinide chalcogenide complexes. Reaction of (Z5‐C5Me5)2ThCl2 with Li2S5 generates the compound (Z5‐C5Me5)2Th(S5) (Wrobleski et al., 1986b); the molecular structure of this complex shows that the six‐membered ring formed by the S5 ligand and the Th has a twist‐boat conformation. Bonding of the ligand was characterized as Z4 on the basis of close contacts between the b‐sulfides and the metal center. Variable temperature NMR data show that the ligand is fluxional at room temperature. The complex (Z5‐C5Me5)2U(StBu)2 is reported to undergo reduction by Na– Hg with cleavage of a C–S bond (Ventelon et al., 1999). The product was isolated with 18‐crown‐6 and proved to be a complex with a terminal sulfido ligand bound to the sodium counter‐ion. The complex [Na(18‐crown‐6)][(Z5‐ ˚ ], which is C5Me5)2U(StBu)(S)] possesses a short U–S bond distance [2.462(2) A ˚ ). significantly shorter than typical U–SR bond distances (ca. 2.64 A

Given the relative importance of d‐transition metal metallocene alkyl chemistry in Group 4 organometallic chemistry, it is to be expected that the alkyl chemistry of the actinide metallocene complexes would also be extensively studied. The majority of this chemistry has employed the more highly substituted ligand sets, although less sterically hindered metallocene frameworks can be alkylated in the presence of a stabilizing base as shown in equation (25.59) (Zalkin et al., 1987a): ðZ5 -C5 H5 Þ2 ThCl2 ðdmpeÞ þ 2LiR

ðZ5 -C5 H5 Þ2 ThR2 ðdmpeÞ þ 2LiCl R ¼ CH3 ; CH2 Ph ð25:59Þ

Complexes employing the pentamethylcyclopentadienyl ligand can be prepared for a wide range of alkyl and aryl groups (Fagan et al., 1981a; Erker et al., 1986; Smith et al., 1986), where the alkylating agents can be either alkyllithium, Grignard, or dialkylmagnesium reagents [equation (25.60)].

2838

Organoactinide chemistry: synthesis and characterization

ðZ5 -C5 Me5 Þ2 AnCl2 þ 2R
ðZ5 -C5 Me5 Þ2 AnR2 þ 2Cl
ð25:60Þ An ¼ Th; U; R ¼ CH3 ; CH2 SiMe3 ; CH2 CMe3 ; C6 H5 ; CH2 C6 H5 The corresponding mixed alkyl halide complexes can be prepared in most cases by reaction of (Z5‐C5Me5)2AnCl2 with one equivalent of alkylating agent, although the methyl chloride complex is best prepared by redistribution from the dichloride and dimethyl complexes [equation (25.61)]. ðZ5 -C5 Me5 Þ2 AnCl2 þ ðZ5 -C5 Me5 Þ2 AnMe2 An ¼ Th; U

2ðZ5 -C5 Me5 Þ2 AnðMeÞðClÞ ð25:61Þ

The complexes are generally thermally stable, although some undergo elimination reactions at elevated temperatures (vide infra). The dimethyl complexes react with acetone, alcohols, and iodine to produce the corresponding t‐butoxide, alkoxides (with generation of methane), and iodides (with generation of methyl iodide) (Fagan et al., 1981a). Competition experiments at –78 C indicate that the thorium complexes are more reactive than those of uranium, consistent with its larger ionic radius. Two alternate descriptions have appeared for the complex (Z5‐C5Me5)2Th 4 (Z ‐C4H6). The complex and its derivatives have been termed both butadiene and 2‐buten‐1,4‐diyl complexes, although the latter description is generally favored. The molecular structure of (Z5‐C5Me5)2Th(Z4‐C4H6) is shown in Fig. 25.16. The crystal structure supports the Z4‐hapticity of the organic ligand, given that the average Th–C distance to the terminal carbon atoms of the ligand [2.57 ˚ ] is only slightly smaller than that to the internal carbon atoms [2.74(2) A ˚ ], (3) A and are comparable to those found in other thorium alkyl complexes. The C(1)– C(2) and C(3)–C(4) average distances (average of four independent molecules in ˚ , and the average C(2)–C(3) distance is 1.44(3) A ˚ . The the unit cell) is 1.46(5) A complex displays fluxional behavior in solution, with equilibration of the cyclopentadienyl and a‐methylene protons occurring via the intermediacy of a planar metallacyclopentene structure.

The actinide–carbon bonds in these complexes appear to be reasonably polar; they undergo hydrogenolysis under one atmosphere of dihydrogen to yield the dihydride complexes [equation (25.62)]:

Carbon‐based ancillary ligands

2839

Fig. 25.16 Crystal structure of (
5‐C5Me5)2Th(
4‐C4H6). (Reprinted with permission from Smith et al. (1986). Copyright 1986 American Chemical Society.)

The dimeric formulation of the dihydride complexes is supported both by cryoscopic molecular weight determinations and a single‐crystal neutron diffraction structure of the thorium compound (Broach et al., 1979); 1H NMR experiments indicate that the bridge and terminal hydrides exchange rapidly in solution to – 85 C. Under an atmosphere of D2, H/D exchange in the hydride positions is very rapid. In the case of uranium, the ring methyl protons appear to interchange rapidly with the hydrides, resulting in isotopic scrambling. The thorium complex is thermally stable; in contrast, the uranium complex loses dihydrogen at room temperature in vacuo over a period of 3 h to generate a U(III) hydride.

2840

Organoactinide chemistry: synthesis and characterization

Dialkyl complexes of an ansa‐metallocene [(Z5‐C5Me4)2(m‐SiMe2)]ThR2 (R ¼ CH2SiMe3, CH2CMe3, C6H5, n‐C4H9, and CH2C6H5) have also been reported (Fendrick et al., 1988). The ring centroid‐metal‐centroid angle (118.4 ) is again much reduced from that typically found in non‐linked metallocene complexes (135–138 ). The dialkyl complexes undergo rapid hydrogenolysis under H2 to yield a light‐sensitive dihydride complex [{(Z5‐C5Me4)2(m‐SiMe2)}ThH2]2. IR ˚ ] are spectroscopy and structural data [a short ThTh distance of 3.632(2) A evidence cited in support of a formulation of the compound as one with four bridging hydride ligands. Thermochemical investigations have tabulated the bond disruption enthalpies for a number of metallocene alkyl halide and dialkyl complexes; these values are given in Table 25.6 (Bruno et al., 1983, 1986b). As noted previously, the Th–R bond enthalpies are uniformly larger than those for U–R. It has also been noted (Leal et al., 2001) that there appears to be significantly different values for certain bond enthalpy values (e.g. U–Me in Tables 25.4 and 25.6). The authors note that these values are based upon different reactions (alcholysis vs reaction with iodine), and therefore are based upon different assumed enthalpy values for product species. A potential correction was proposed, leading to a more self‐consistent description of uranium bond enthalpies. A further observation from the thermochemistry of thorium complexes is that the bond dissociation enthalpy for Th–H in [(Z5‐C5Me5)2Th(m‐H)H]2 (407.9  2.9 kJ/mol), while somewhat larger than typical Th–C values (300–380 kJ mol
1), is not larger enough to produce as strong a driving force for the Table 25.6 Mean bond dissociation enthalpies for (
5‐C5Me5)2AnR2 and (
5‐C5Me5)2AnRX complexes (Bruno et al., 1983, 1986b). Compound

R

D(An–R) (kJ mol
1)

(Z5‐C5Me5)2UR2

Me CH2Ph CH2SiMe3

300  11 244  8 307  8

(Z5‐C5Me5)2URCl

Me CH2Ph Ph

312  8 263  12 358  11

(Z5‐C5Me5)2ThR2

Me Et n‐Bu Ph CH2CMe3 CH2SiMe3

345.2  3.5 313.4  6.7 303.8  9.2 379.3  10.3 312.1  15.7 339.3  13.0

(Z5‐C5Me5)2ThRCl

Et CH2Ph Ph

302.1  7.5 285.3  5.9 380.8  16

Carbon‐based ancillary ligands

2841

formation of hydrides. Therefore, unlike mid‐ to late‐transition metal compounds, reactions such as b‐hydride elimination will not be strongly favored. This energetic situation, similar to that found for early transition metals, makes actinide metallocenes suitable species to effect C–C bond forming reactions, such as olefin polymerization (see Chapter 26). One of the predominant reaction patterns of bis(cyclopentadienyl)actinide complexes is insertion chemistry. Insertion of unsaturated substrates such as CO, CNR, CO2, and CS2 into U–C, U–Si, U–N, and U–S bonds has been observed (Fagan et al., 1981a,b; Erker et al., 1986; Porchia et al., 1989; Lescop et al., 1999). The products of insertion generally display Z2‐C(R) ¼E bonding. As an example, insertion of CO into An–R bonds yields Z2‐acyl derivatives. Theoretical studies (Tatsumi et al., 1985) have been conducted, both to explain the geometry of the Z2‐complexes, as well as to understand the origin of the ‘carbene‐like’ reactivity (Fig. 25.17). A second common reaction pattern observed in metallocene complexes is thermally induced intramolecular elimination reactions. The dominant classes of elimination reactions are those involving formation of four‐membered metallacyle complexes [equation (25.63)] (Bruno et al., 1986a).

Kinetic and labeling studies in the cyclometallation reactions indicate that intramolecular g‐C–H activation is the rate‐limiting step. It is believed that the reaction is chiefly entropically driven, with some driving force coming from relief of steric strain associated with the thorium dialkyl complex. The cyclometallated products have extensive reaction chemistry that is characterized by insertion of unsaturated substrates into Th–C bonds, as well as intermolecular activation of C–H bonds of other substrates, even saturated hydrocarbons such as methane [equation (25.64)] (Fendrick and Marks, 1986).

2842

Organoactinide chemistry: synthesis and characterization

Fig. 25.17

Reactivity of actinide
2‐Acyl complexes (Moloy et al., 1983).

A second class of reactions is the elimination of benzene from diaryl complexes to form o‐diphenylene, or benzyne‐type complexes [equation (25.65)] (Fagan et al., 1981a).

Carbon‐based ancillary ligands

2843

The uranium complexes undergo this ortho‐activation process (kU  kTh); although the intermediate benzyne complex is not stable, it can be trapped with diphenylacetylene to yield a metallacyclopentadiene product. Despite the early report of mono‐ring complexes of the formula (Z5‐C5H5) UCl3(DME) (DME ¼ 1,2‐dimethoxyethane) (Doretti et al., 1972), there are far fewer reports of compounds containing a single cyclopentadienyl ring. The complex was initially prepared by reaction of UCl4 with Tl(C5H5) in DME [equation (25.66)].

Since that time, a number of other base adducts of the uranium mono‐ring compound have been prepared using both monodentate (Bagnall and Edwards, 1974; Bagnall et al., 1978a; Bombieri et al., 1978) and bidentate bases (Ernst et al., 1979). The complex U(BH4)4 similarly reacts with Tl(C5H5) to yield (Z5‐ C5H5)U(BH4)3 (Baudry and Ephritikhine, 1988), although base adducts of this compound are reported to redistribute to generate (Z5‐C5H5)2U(BH4)2 (Baudry et al., 1988). The structure of the (Z5‐C5H5)U(BH4)3(THF)2 complex has been proposed to be mer‐octahedral with cis THF ligands on the basis of solution NMR investigations with a pentahapto cyclopentadienyl ring; this structure was confirmed for the complex (Z5‐MeC5H4)UCl3(THF)2.

A later NMR study (Le Marechal et al., 1986) reported an equilibrium between two isomers in solution for a variety of base adducts of (Z5‐C5H5) UCl3. Analogous compounds of the formula (Z5‐C5H5)AnX3L2 (X ¼ halide, NCS–) have been produced for thorium (Bagnall and Edwards, 1974), neptunium (Karraker and Stone, 1972; Bagnall et al., 1986), and plutonium (Bagnall et al., 1985).

2844

Organoactinide chemistry: synthesis and characterization

A variety of substituted cyclopentadienyl ligands have been introduced to generate cyclopentadienylthorium and cyclopentadienyluranium compounds by reaction with Grignard or alkali metal reagents. Indenyl complexes of the formula (Z5‐C9H7)AnX3L (X ¼ halide, L ¼ base) can be prepared as shown in equations (25.67) and (25.68) (Goffart et al., 1980; Meunier‐Piret et al., 1980).

The use of alkali metal cyclopentadienyl reagents can lead to the formation of uranate‐type complexes [equations (25.69) and (25.70)] (Edelman et al., 1987, 1995):

Mono‐ring pentamethylcyclopentadienyl thorium and pentamethylcyclopentadienyl uranium complexes can also be synthesized from reaction of the tetrahalides with (C5Me5)MgCl (Mintz et al., 1982; Butcher et al., 1996), and their base adducts prepared. Spectroscopic data would again indicate a meridional disposition of the chloride ligands in a pseudo‐octahedral geometry. As described in equation (25.71), these complexes can be alkylated with either organolithium or Grignard reagents to yield a limited number of stable alkyl derivatives (Mintz et al., 1982; Cymbaluk et al., 1983a; Marks and Day, 1985; Marks, 1986).

Carbon‐based ancillary ligands

2845

One study has been conducted of the metathesis chemistry of (Z5‐C5Me5) ThBr3(THF)3 with aryloxide salts (Butcher et al., 1996). Both the mono(aryloxide) and bis(aryloxide) complexes (Z5‐C5Me5)ThBr2(OAr)(THF) and (Z5‐ C5Me5)ThBr(OAr)2 (OAr ¼ O‐2,6‐tBu2C6H3) may be produced by reaction with one or two equivalents of KOAr. The dibromide complex may be further alkylated to generate (Z5‐C5Me5)Th(CH2SiMe3)2(OAr). Thermolysis of this compound in the presence of triphenylphosphine oxide permits the isolation of a rare example of an f‐element compound with a cyclometallated aryloxide ligand.

(c)

Pentavalent chemistry

Pentavalent complexes of the actinides containing organic ligands are rare. They are anticipated to be limited to uranium, given the increasing stability of lower oxidation states for the later actinides. Most pentavalent organouranium complexes are supported by multiply bonded functional groups, such as those present in the complexes (Z5‐C5H4Me)3U¼NR previously described [see equation (25.22)]. The complex [Z5‐1,3‐(Me3Si)2C5H3]2UCl(THF) has been reported to react with Me3SiN3 to liberate N2 and generate the U(V) organoimido complex [Z5‐1,3‐(Me3Si)2C5H3]2U(¼NSiMe3)(Cl) (Blake et al., 1987). Oxo transfer has also been effected to a U(III) precursor; the complex (Z5‐C5Me5)U (OAr)(THF) (Ar ¼ 2,6‐iPr2C6H3) reacts with pyridine N‐oxide to yield the oxo derivative (Z‐C5Me5)U(¼O)(OAr) (Arney and Burns, 1993). The molecular structure of this complex has been determined. The complex exists as a typical pseudo‐tetrahedral metallocene complex, with a U–O (oxo) bond length of ˚ , slightly longer than that common for a mutliply‐bonded oxo 1.859(6) A group in the uranyl ion ðUO2þ 2 Þ. Attempts to prepare U(VI) dioxo complexes supported by cyclopentadienyl groups has recently generated another rare example of a pentavalent oxo complex. Reaction of (Z5‐tBu3C5H2)2UCl2 with KC8, followed by oxidation with pyridine N‐oxide, results in the formation of the complex (Z5‐tBu3C5H2)4U6O13(bipy)2 (Duval et al., 2001) (Fig. 25.18).

2846

Organoactinide chemistry: synthesis and characterization

Fig. 25.18 Crystal structure of (
5‐tBu3C5H2)4U6O13(bipy)2 (methyl carbons of tert‐butyl groups are omitted for clarity) (Duval et al., 2001). (Reprinted with permission from John Wiley & Sons, Inc.)

Carbon‐based ancillary ligands

2847

The core of the complex is a U6O13 aggregate. Four uranium atoms in an equatorial plane are capped with a tri‐tert‐butylcyclopentadienyl ligand, while the two apical uranium atoms are ligated by 2,20 ‐bipyridine ligands, apparently derived from the by‐product pyridine. The proposed mechanism for the formation of the aggregate is the generation and assembly of ‘UO2’ and ‘(Z5‐tBu3C5H2)2UO2’ fragments from homolytic ring loss. Although the central metal oxo unit is structurally similar to the Lindqvist class of polyoxometallate anions, there is no indication of electronic delocalization in the complex. Magnetic susceptibility measurements suggest that the uranium centers behave as independent U(V) f1 paramagnets. Another approach to U(V) organometallic complexes has recently been reported. Oxidation of neutral precursors (Z5‐C5Me5)U(NMe2)3(THF) and (Z5‐C5Me5)2U(NEt2)2 with AgBPh4 gives rise to the corresponding cationic derivatives [(Z5‐C5Me5)U(NMe2)3(THF)][BPh4] and [(Z5‐C5Me5)2U(NEt2)2] [BPh4] (Boisson et al., 1995). The electronic structure of these complexes was subsequently examined by EPR in frozen solution (Gourier et al., 1997). It was shown that the interaction of the metal 5f orbitals with the cyclopentadienyl and amido ligands are sufficiently small and that the J ¼ 5/2 ground state quantum number for U(V) remains a good quantum number for the complexes; the 5f orbitals are essentially nonbonding, and any covalent bonding interaction must therefore involve metal 6d orbitals. (d)

Hexavalent chemistry

Historically, there have been extremely few examples of non‐aqueous compounds of hexavalent actinides, despite the prevalence of the actinyl ion ðAnO2þ 2 Þ for the elements U to Am. Attempts to prepare alkyl‐ or cyclopentadienyl compounds of the actinyl ions were met with reduction of the metal center (Seyam, 1982). In the last 10 years, a class of formally hexavalent cyclopentadienyluranium complexes has been prepared that is alternatively stabilized by the presence of organoimido substituents. The complex (Z5‐ C5Me5)2U(¼NC6H5)2 was first prepared by the oxidation of [Li(TMEDA)] [(Z5‐C5Me5)2U(¼NC6H5)Cl] with phenyl azide (Arney et al., 1992; Arney and Burns, 1995), although other routes have since been devised (Fig. 25.19). The structure of the complex is shown in Fig. 25.20. The complex has a pseudo‐tetrahedral bent metallocene geometry, with a N– U–N angle of 98.7(4) . This bent E¼U¼E moiety is quite different from the linear O¼U¼O angle found in the uranyl ion, and may be attributed to the strong donor character of the pentamethylcyclopentadienyl groups. The short ˚ ], and the near‐linear U–N–C bond uranium–nitrogen distances [1.952(7) A angle [177.8(6) ] are consistent with the formulation of the ligands as organoimido groups. The organoimido ligands are remarkably unreactive in comparison with their Group 4 d‐transition metal counterparts (Walsh et al., 1988, 1992, 1993; Baranger et al., 1993), showing no reaction with unsaturated

2848

Organoactinide chemistry: synthesis and characterization

Fig. 25.19 Synthetic pathways to (
5‐C5Me5)2U(¼NC6H5)2 (Arney et al., 1995).

substrates, MeI, or ammonia. This, coupled with the observation that the ˚ ] are comparable with those found U–Cring bond distances [2.72(1)–2.75(1) A in typical U(IV) metallocenes, argues for some degree of covalency in the U–N bonding. In order to invoke a higher bond order, it is necessary to suggest the involvement of 5f orbitals in stabilizing the nitrogen 2p lone pair electrons, as there is no 6d orbital of the appropriate symmetry. The U(VI) character of the complex is demonstrated in the lack of observable metal‐based electronic transitions (f–f, f–d) in the near‐IR spectrum, as well as the observation in the 1H NMR spectrum that the complex appears to act as a temperature‐independent paramagnet (Arney et al., 1992). Since the initial report, other U(VI) bis(imido) compounds have been prepared with substituted arylimido and trimethylsilylimido ligands. In addition, U(VI) imido‐oxo complexes (Z5‐C5Me5)2U(¼NAr)(¼O) (Ar ¼ 2,4,6‐ Me3C6H2, 2,4,6‐tBu3C6H2, 2,6‐iPr2C6H3) have been synthesized (Arney and Burns, 1995). These complexes have similar geometries to the bis(imido)

Carbon‐based ancillary ligands

2849

Fig. 25.20 Crystal structure of (
5‐C5Me5)2U(¼NC6H5)2. (Reprinted with permission from Arney et al. (1992). Copyright 1992 American Chemical Society.)

˚ for the complex (Z5‐ derivatives, with a U–O bond length of 1.844(4) A i C5Me5)2U(¼N‐2,6‐ Pr2C6H3)(¼O). This bond length is significantly longer than that observed for uranyl ions, which may reflect a reduced bond order. The ancillary ligand appears to make a difference in the accessibility of the U (VI) oxidation state. Complexes of uranium with the chelating ligand sets [Me2Si (Z5‐C5Me4)2]2– and [Me2Si(Z5‐C5Me4)(Z5‐C5H4)]2– have been prepared and employed in analogous reactions to prepare organoimido complexes (Schnabel et al., 1999). While the bis(tetramethylcyclopentadienyl) ansa‐metallocene successfully produces a bis(imido) compound, reaction of [Me2Si(Z5‐C5Me4)(Z5‐ C5H4)]U(CH2C6H5)2 with N,N0 ‐diphenylhydrazine yields only the tetravalent bridging imido complex and [{Me2Si(Z5‐C5Me4)(Z5‐C5H4)}U(m‐NPh)]2. Electrochemical investigations of the chloride compounds [Me2Si(Z5‐C5Me4)2] UCl2 · 2LiCl · 4(Et2O) and [Me2Si(Z5‐C5Me4)(Z5‐C5H4)]UCl2 · 2LiCl · 4(THF) suggest that the ancillary ligands have the capacity to significantly alter the redox activity of the metal center; [Me2Si(Z5‐C5Me4)(Z5‐C5H4)]UCl2 · 2LiCl · 4 (THF) is more difficult to oxidize than [Me2Si(Z5‐C5Me4)2]UCl2 · 2LiCl · 4 (Et2O) by  0.24 V (vs [Cp2Fe]0/þ). It has also been proposed that ansa bis (cyclopentadienyl) ligands sets generate more electrophilic metal centers (Lee et al., 1998; Shin et al., 1999). As mentioned previously, the uranium imido complexes are generally unreactive, although a limited number of bond activation reactions have been

2850

Organoactinide chemistry: synthesis and characterization

reported. The complex (Z5‐C5Me5)2U(¼NC6H5)2 will effect the homolytic cleavage of dihydrogen to yield a bis(amide) compound [equation (25.72)].

In an attempt to prepare more reactive organoimido functional groups, the more electron‐rich adamantylimido complex (Z5‐C5Me5)2U(¼NAd)2 (Ad ¼ Adamantyl) was prepared (Warner et al., 1998). This complex undergoes decomposition under thermolysis to generate a complex derived from C–H activation of a pentamethylcyclopentadienyl methyl group (Peters et al., 1999).

More reactive uranium–nitrogen multiple bonds may be generated by heteroatom substitution. The reaction of tetravalent (Z5‐C5Me5)2U(¼N‐2,4,6‐ tBu3C6H2) with diphenyldiazomethane generates the mixed bis(imido) complex (Z5‐C5Me5)2U (¼N‐2,4,6‐tBu3C6H2)(¼N‐N¼CPh2), which undergoes a cyclometallation reaction upon mild thermolysis to generate a uranium(IV) bis(amide) complex that results from net addition of a C–H bond of an ortho tert‐butyl group across the N¼U¼N core (Kiplinger et al., 2002).

Carbon‐based ancillary ligands

2851

In select cases, U(VI) will catalyze chemical transformations; these will be discussed further in Chapter 26. 25.2.2

Cyclooctatetraenyl ligands

The chemistry of the cyclooctatetraenyl ligand and its substituted variants is significant in the development of actinide organometallic chemistry, and highlights differences between the f‐elements and transition metals. The recognition that the lanthanides and actinides possess f‐orbitals of the appropriate symmetry to interact with this carbocyclic ligand led to the theoretical prediction that a ‘sandwich’ compound could be prepared (Fischer, 1963). This prediction was subsequently validated by the preparation of (Z8‐C8H8)2U (or ‘uranocene’) by the reaction of UCl4 and the potassium salt of the dianion of cyclooctatetraene, K2(C8H8) [equation (25.73)] (Streitwieser and Mu¨ller‐Westerhoff, 1968). Since that time, other synthetic routes to bis(cyclooctatetraenyl) complexes of the actinides have appeared [equations (25.74) and (25.75)] (Starks and Streitwieser, 1973; Starks et al., 1974; Chang et al., 1979; Rieke and Rhyne, 1979): UCl4 þ 2K2 ðC8 H8 Þ U ðpowderÞ þ 2C8 H10 UF4 þ 2MgðC8 H8 Þ

THF

ðZ8 - C8 H8 Þ2 U þ 4KCl

Hgðcat:Þ

ð25:73Þ

ðZ8 - C8 H8 Þ2 U þ 2H2

ð25:74Þ

ðZ8 - C8 H8 Þ2 U þ 2MgF2

ð25:75Þ

Bis(cyclooctatetraenyl) complexes of a number of other actinide elements have also been prepared, including Th (Streitwieser and Yoshida, 1969; Goffart et al., 1972; Starks and Streitwieser, 1973), Pa (Goffart et al., 1974; Starks et al., 1974), Np (Karraker et al., 1970), and Pu (Karraker et al., 1970). Most are prepared by the methods of equations (25.73) and (25.74), although the plutonium compound was prepared from Cs2PuCl6. A large number of substituted (cyclooctatetraenyl) complexes have also been reported. The addition of substituents has been employed to improve solubility, alter electronic properties, or investigate the dynamics of ring rotation reactions. The largest class of these are the 1,10 ‐disubstituted derivatives (Harmon et al., 1977; Spiegl, 1978; Miller and DeKock, 1979; Spiegl and Fischer, 1979) prepared by the method of equation (25.76):

1,10 ‐Disubstituted derivatives (R ¼ Et, n‐Bu) of neptunium and plutonium have also been prepared (Karraker, 1973). A number of uranocene derivatives with higher degrees of substitution have been reported (Streitwieser et al., 1971;

2852

Organoactinide chemistry: synthesis and characterization

Streitwieser and Harmon 1973; Streitwieser and Walker, 1975; Solar et al., 1980; LeVanda and Streitwieser, 1981; Miller et al., 1981; Lyttle et al., 1989), including several with exocyclic ligands (Luke et al., 1981; Zalkin et al., 1982; Streitwieser et al., 1983). The silylated derivatives [Z5‐1,3,5‐(SiMe3)3C8H5]2An have been prepared for An ¼ Th, U, and Np (Apostolidis et al., 1999). There is also one example of a bridged, or linked uranocene, [Z8:Z8‐1,2‐bis(cyclooctatetraenyldimethylsilyl)ethane]uranium (Streitwieser et al., 1993).

The molecular structure of many uranocene derivatives have been determined; the molecular structure of (Z8‐C8H8)2U is shown in Fig. 25.21 (Zalkin and Raymond, 1969, Avdeef et al., 1972). The molecule possesses rigorous D8h symmetry, with the eight‐membered rings arranged in an eclipsed conformation. The averaged U–Cring bond dis˚ ; all atoms of the cyclooctatetraene ligand lie within the plane tance is 2.647(4) A

Fig. 25.21 Crystal structure of (
8‐C8H8)2U. (Reprinted with permission from Zalkin and Raymond (1969). Copyright 1969 American Chemical Society.)

Carbon‐based ancillary ligands

2853

˚ . A comparison of the average C–C bond lengths for alternate sets of to 0.02 A ˚ ] confirms the aromatic four bonds within the rings [1.396(5) and 1.388(27) A nature of the ligand. Substituted uranocene derivatives can show staggered ring geometries in the solid state; the rings in the complex bis(Z8‐1,3,5,7‐tetraphenylcyclooctatetraene)uranium are eclipsed (Templeton et al., 1976), while the structure of bis(Z8‐1,3,5,7‐tetramethylcycloctatetraene)uranium reveals two symmetry‐independent molecules in the asymmetric unit: one with staggered rings and one in which the rings are nearly eclipsed (Hodgson and Raymond, 1973). The bonding in these highly symmetric compounds has been studied extensively by theoretical and experimental methods. The first theoretical treatments assumed that the principal metal–ligand interactions occurred through 5f orbitals, and that 6d orbitals would be too high in energy to interact with ligand‐based orbitals. Improvement in computation methods (such as the inclusion of spin–orbit coupling) and inclusion of relativistic corrections have amended this bonding description. An ab initio calculation on uranocene incorporating relativistic core potentials and spin–orbit CI calculations suggests a significant degree of covalency in metal–ligand bonding; the 6d orbitals play a primary role in these interactions, and the 5f orbital involvement is secondary (Chang and Pitzer, 1989). A qualitative molecular orbital diagram is shown in Fig. 25.22. The principal bonding interaction involves the metal 6dd and ligand 3e2g orbitals, as well as the metal 5fd and ligand 3e2u combination. Minimal interaction also exists between the metal 5ff orbitals and the ligand‐based e3u orbitals. The dashed line in the figure shows the impact of including relativistic effects in the calculations, further stabilizing a dz2 orbital, making it the lowest unoccupied molecular orbital, housing any unpaired metal electrons (the orbital is essentially metal–ligand nonbonding). Experimental probes of bonding in actinocenes have included chemical reactivity, magnetism, NMR spectroscopy, optical spectroscopy, Np‐237 Mo¨ssbauer spectroscopy, and photoelectron spectroscopy (PES) (Burns and Bursten, 1989, and references therein). The initial observation of the stability of (Z8‐C8H8)2U to hydrolysis (relative to (Z8‐C8H8)2Th) suggested a higher degree of covalency in bonding in the uranium complex. Attempts have been made to derive the magnetic moment for bis(cyclooctatetraene) complexes of U, Np, and Pu. For example, (Z8‐tBuC8H7)2Pu is reported to have a J ¼ 0 ground state and exhibits temperature‐independent paramagnetism (Karraker, 1973). The first predictions of the magnetism were based on the assumption of ionic bonding (weak crystal‐field perturbations) and simple L–S coupling models (Karraker et al., 1970). Deviations of the calculated moments from the observed were corrected by application of an empirical ‘orbital reduction factor’ described as a measure of covalency in bonding. Later non‐relativistic calculations provided a better fit to experimentally observed magnetic moments between 10 and 80 K (Hayes and Edelstein, 1972). These calculations suggested a significant degree of covalency, but it was pointed out that the high value assumed for the

2854

Organoactinide chemistry: synthesis and characterization

Fig. 25.22 Molecular orbital diagram of (
8‐C8H8)2U. (Reprinted with permission from Parry et al. (1999). Copyright 1999 American Chemical Society.)

5f valence state ionization potential could cause an overestimation of the covalence in bonding. Some of the most compelling evidence for the degree of covalency in uranocene (and particularly for a 5f orbital role) comes from variable energy photoelectron spectroscopy (Brennan et al., 1989). In general, metal‐based electrons are known to have an energy‐dependent cross section. In (Z8‐C8H8)2U (over the energy range 24–125 eV), the f‐band shows cross‐section features attributable to 5f resonant photoemission in the vicinity of the 5d–5f giant resonant absorption (hn ¼ 101 and 110 eV). The e2g and e2u bands also show small cross‐section maxima at these energies; that for the e2u ionization being the more intense. The mapping of the intensity changes of the f‐band by the e2u band provides strong evidence for f‐orbital contribution to valence orbitals in this molecule (Fig. 25.23). Ring dynamics (rotation and exchange) have been studied by means of variable‐temperature NMR spectroscopy for substituted derivatives. It is

Carbon‐based ancillary ligands

2855

Fig. 25.23 Variable energy photoelectron spectrum of (
5‐C8H8)2U. (Reprinted with permission from Brennan et al. (1989). Copyright 1989 American Chemical Society).

found that uranocenes undergo rapid ligand exchange with cyclooctatetraene dianions (LeVanda and Streitwieser, 1981). The barrier to ring rotation has been estimated at 8.3 kcal mol–1 for (Z8‐1,4‐tBu2C8H6)2U; this compares with a value of 13.1 kcal mol–1 for a d‐transition metal metallocene analog (Z5‐1,3‐tBu2C5H3)2Fe (Luke and Streitwieser, 1981). In addition to the neutral tetravalent actinocenes, synthetic routes have been devised to anionic trivalent derivatives, [(Z8‐C8H8)2An]–, either by treatment of trivalent precursors with K2(C8H8) [equation (25.77)], or by reduction of the actinocene [equation (25.78)] (Karraker and Stone, 1974; Billiau et al., 1981; Eisenberg et al., 1990). AnI3 þ 2K2 ðC8 H8 Þ

THF

K½ðZ8 -C8 H8 Þ2 An  2THF

An ¼ Np; Pu ðZ8 -C8 H8 Þ2 An þ K=Naphthalene An ¼ U; Np; Pu

K½ðZ8 -C8 H8 Þ2 An

ð25:77Þ

ð25:78Þ

The Mo¨ssbauer spectrum of the neptunium compound [(Z8‐C8H8)2Np]– confirms that the metal is in the trivalent oxidation state, and suggests a lower overall degree of covalency in metal–ligand bonding than in tetravalent derivatives. Most recently, the reduction route has been extended to generate trivalent actinocenes K(DME)2[{Z8‐1,4‐(tBuMe2Si)2C8H6}2An] (An ¼ Th, U), wherein the bulky silyl substituents are proposed to provide both kinetic and

2856

Organoactinide chemistry: synthesis and characterization

thermodynamic stabilization of the Th(III) compound (Parry et al., 1999). The complexes display asymmetric An–Cring distances, owing to the ‘capping’ of one ring by close association with the potassium counter‐ion. The observed magnetic moment for the thorium compound is 1.20mB at 293 K, which is low when compared to the spin‐only value for one unpaired electron (1.73mB). It has been proposed that the low moment is due to mixing of the ground state magnetic component with low‐lying excited states. Intermolecular electron‐transfer rates have been studied for uranocene and substituted derivatives of uranium, neptunium, and plutonium (Eisenberg et al., 1990) by examining the variable‐temperature NMR spectra of mixtures of (Z8‐C8H8)2An and [(Z8‐C8H8)2An]–. In all cases, electron transfer rates are rapid. Specific rates could not be derived for uranium and plutonium derivatives due to the small chemical shift differences between analogous An(IV) and An(III) compounds, but in the case of (Z8‐tBuC8H7)2Np, the rate has been estimated to be of the same order of magnitude as comparable lanthanide cyclooctatetraene compounds ( 107 M–1s–1). The chemistry of actinide complexes containing a single cyclooctatetraenyl ring began with a report of (Z8‐C8H8)NpI·xTHF, prepared by reaction of NpI3(THF)4 and K2(C8H8) in THF (Karraker and Stone, 1977). The first structurally characterized examples of this class of compounds included both derivatives of uranium [(Z8‐C8H8)UCl2(pyridine)2 and (Z8‐C8H8)U(MeCOCHCOMe)2; Boussie et al., 1990] and thorium [(Z8‐C8H8)ThCl2(THF)2; Zalkin et al., 1980]. Since these initial reports, other entries into mono‐ring chemistry have been established, principally those involving redistribution [equations (25.79) and (25.80)] (LeVanda et al., 1980; Gilbert et al., 1988; Baudry et al., 1990a), halogenation [equation (25.81)] (Berthet et al., 1990), and metathesis [equations (25.82) and (25.83)] (Boisson et al., 1996a). 1 8 2ðZ -C8 H8 Þ2 Th 8 1 2ðZ -C8 H8 Þ2 U

þ ThCl4

þ 12UðBH4 Þ4

ðZ8 -C8 H8 ÞThCl2 ðZ8 -C8 H8 ÞUðBH4 Þ2

L

ðZ8 -C8 H8 ÞUðBH4 Þ2 ðLÞ L ¼ THF; Ph3 P ¼ O ðZ8 -C8 H8 Þ2 U þ I2 ðNEt2 Þ2 UCl2 þ K2 ðC8 H8 Þ

THF

ðZ8 -C8 H8 Þ2 U þ 3LiNEt2

THF

ð25:79Þ

ðZ8 -C8 H8 ÞUI2 ðTHFÞ2

ð25:80Þ

ð25:81Þ

ðZ8 -C8 H8 ÞUðNEt2 Þ2 ðTHFÞ þ 2KCl ð25:82Þ Li½ðZ8 -C8 H8 ÞUðNEt2 Þ3 

ð25:83Þ

Collectively, these complexes further serve as precursors to a variety of mono (cyclooctatetraenyl) derivatives, including alkyl (Berthet et al., 1994), alkoxide (Arliguie et al., 1992), amide (Gilbert et al., 1988; Le Borgne et al., 2000), and

Carbon‐based ancillary ligands

2857

thiolate (Leverd et al., 1994; Arliguie et al., 2000) complexes. Mixed‐ring derivatives containing both cyclooctatetraenyl and cyclopentadienyl ligands have similarly been prepared by metathesis reactions (Gilbert et al., 1989; Berthet et al., 1994, Boisson et al., 1996b). The complex (Z8‐C8H8)(Z5‐C5Me5) Th[CH(SiMe3)2] undergoes hydrogenolysis to yield the hydride compound (Z8‐C8H8)(Z5‐C5Me5)ThH (Gilbert et al., 1989). An interesting example of the introduction of a bridging cyclooctatetraenyl ligand is found in the reaction of (Z5‐C5Me5)3U with cyclooctatetraene (Evans et al., 2000). As previously discussed, the bulky tris(pentamethylcyclopentadienyl) complex can act as a multi‐electron reductant. Reaction with C8H8 produces the complex [(Z8‐C8H8)(Z5‐C5Me5)U]2(m‐C8H8), along with (C5Me5)2. The complex consists of two mixed‐ring U(IV) units coordinated to a bridging C8 H2
8 ligand (Fig. 25.24). The bridging ring is non‐planar and appears bound to the two metal centers in an unusual Z3:Z3 manner, with one carbon in common. Cationic derivatives of the formula [(Z8‐C8H8)U(NEt2)(THF)2][BPh4] and [(Z8‐C8H8)U(BH4)(THF)2][BPh4] may be produced by protonation of the respective tetravalent precursors (Z8‐C8H8)UX2(THF) with [NEt3H][BPh4] (Boisson et al., 1996b; Cendrowski‐Guillaume et al., 2000). Reaction of the latter with additional ammonium salt in the presence of hexamethylphosphoramide (HMPA) yields the unique dicationic species [(Z8‐C8H8)U(HMPA)3] [BPh4]2. The U–N bond in the complex [(Z8‐C8H8)U(NEt2)(THF)2][BPh4] is susceptible to protonation by alcohols and thiols, and will insert CO2, CS2, or MeCN to generate the complexes [(Z8‐C8H8)U(E2CNEt2)(THF)2][BPh4] (E ¼ O, S) and [(Z8‐C8H8)U(NC(Me)NEt2)(THF)2][BPh4]. Few trivalent derivatives of mono(cyclooctatetraenyl)uranium have been isolated, likely due to the facile ligand redistribution and disproportionation

Fig. 25.24 Crystal structure of [(
8‐C8H8)(
5‐C5Me5)U]2(m‐C8H8) (Evans et al., 2000). (Reprinted with permission from John Wiley & Sons, Inc.)

2858

Organoactinide chemistry: synthesis and characterization

reactions that give rise to uranocene. The complex (Z8‐C8H8)(Z5‐C5Me5)U (THF) is produced by reaction of (Z5‐C5Me5)UI2(THF) with K2(C8H8) (Schake et al., 1993); the 4,40 ‐dimethyl‐2,20 ‐bipyridine adduct has been structurally characterized. The complex exists as a bent metallocene with a ring centroid– uranium–ring centroid angle of 138.2 . The average M–Cring distances are consistent with the larger ionic radius of U(III). The aforementioned dication [(Z8‐C8H8)U(HMPA)3][BPh4]2 can be reduced by sodium amalgam to generate a monocation [(Z8‐C8H8)U(HMPA)3][BPh4] (Cendrowski‐Guillaume et al., 2001). An interesting new class of pentavalent complexes supported by the cyclooctatetraenyl ligand has recently been developed. Oxidation of anionic U(IV) mono‐ring amide complexes with TlBPh4 or AgBPh4 generates the corresponding pentavalent amide complexes as shown in equations (25.84) and (25.85) (Berthet and Ephritikhine, 1993; Boisson et al., 1995). ½ðZ8 -C8 H8 ÞUðNEt2 Þ3 
þ TIBPh4 ðZ8 -C8 H8 ÞUðNEt2 Þ2 ðTHFÞ þ AgBPh4

ðZ8 -C8 H8 ÞUðNEt2 Þ3

ð25:84Þ

½ðZ8 -C8 H8 ÞUðNEt2 Þ2 ðTHFÞ ½BPh4 

ð25:85Þ

The molecular structure of [(Z ‐C8H8)U(NEt2)2(THF)][BPh4] has been determined (Boisson et al., 1996a). The amide ligands are susceptible to protonation by alcohols to yield alkoxide complexes. Pentavalent cyclooctatetraenyluranium compounds have been studied by EPR (Gourier et al., 1997) and X‐ray absorption spectroscopy (Den Auwer et al., 1997). Analysis of EPR spectra suggested that (as for cyclopentadienyl ligands) chemical bonding with the cyclooctatetraenyl ligand occurs principally with the uranium 6d orbitals, except in the case of the tris(iso‐propoxide) complex (Z8‐C8H8)U(OiPr)3. In this complex, it was proposed that the 5f–O interaction is strong, so that J is no longer a good quantum number, and the weak‐field approximation can no longer be considered valid. 8

25.2.3 (a)

Other carbocyclic ligands

Arene ligands

Although arene compounds of the d‐transition metals were prepared early in the 20th century, their identity as Z6‐ligands was not recognized until many years later. All previous carbocyclic ligands discussed in this article may be 2
regarded to have a formal charge (e.g. C5 H
5 , C8 H8 ), and so therefore may bind more strongly to actinide centers via Coulombic forces. In contrast, arenes are often regarded as neutral ligands, and so any interaction with a metal center might best be regarded as one involving significant electrostatic polarization of the ligand p‐electrons, or alternatively, covalent bonding. Given the propensity of the later actinides to engage principally in ionic bonding, it is therefore not

Carbon‐based ancillary ligands

2859

surprising that arene complexes are restricted to the early actinides. Only uranium has been found to generate arene complexes. This suggests a greater propensity for uranium to engage in covalent bonding, consistent with the observation that U–C bonding in uranocene appears to be more covalent than in its thorium analog. The initial method employed to prepare p‐arene complexes of d‐transition metals was the reducing Friedel–Crafts route developed by Fischer and Hafner (1955), involving reduction of a metal salt with aluminum powder, followed by reaction with an arene ligand. Extension of this method to reaction with UCl4 produced the first p‐arene complex, the trivalent species (Z6‐C6H6)U(AlCl4)3 (Cesari et al., 1971). The molecular structure of the complex consists of a pseudotetrahedral arrangement of the four ligands about uranium, with two bridging chlorides between each aluminum and uranium. The benzene ring was ˚. refined as an idealized model, with uranium–carbon distances of 2.91–2.92 A Toluene and hexamethylbenzene analogs have also been described (Cotton and Schwotzer, 1987; Garbar et al., 1996). Subsequently, two polymetallic tetravalent complexes were prepared by a variant of this procedure as depicted in equation (25.86) (Cotton and Schwotzer, 1985; Campbell et al., 1986):

The complex [(Z6‐C6Me6)Cl2U(m‐Cl)3UCl2(Z6‐C6Me6)][AlCl4] was isolated by further reduction with zinc powder. Once isolated, the compounds are insoluble in non‐coordinating solvents. The cation of the molecule [(Z6‐C6Me6)Cl2U(m‐ Cl)3UCl2(Z6‐C6Me6)][AlCl4] is shown in Fig. 25.25. The arene ligands in these complexes are all found to be weakly bound, and are readily displaced by other bases such as THF or acetonitrile. Detailed structural studies have been conducted on these arene complexes. In no case does the arene ring appear to significantly deviate from planarity. The U–Carene bond distances in these complexes are long for actinide–carbocyclic ligands; ˚. they fall in the range 2.89(2)–2.96(2) A 6 Z ‐Arene complexes of trivalent uranium have also been isolated from the thermolysis of U(BH4)4 in aromatic solvents (Baudry et al., 1989a). The mesitylene complex (Z6‐mesitylene)U(BH4)3 was initially isolated from that solvent. The weakly coordinated arene is readily displaced by other aromatic substrates, however, and the hexamethylbenzene complex is reported to be more stable to displacement in toluene solution. More recently, reduction of tetravalent actinide amide complexes has been found to give rise to an interesting series of ‘inverted sandwich’, or bridging arene complexes (Diaconescu et al., 2000; Diaconescu and Cummins, 2002). Reduction of [N(tBu)Ar]3UI (Ar ¼ 3,5‐Me2C6H3) by KC8 in toluene generates the complex [N(tBu)Ar]2U(m‐Z6,Z6‐C7H8)U[N(tBu)Ar]2. The related compound

2860

Organoactinide chemistry: synthesis and characterization

Fig. 25.25 Molecular structure of [(
6‐C6Me6)Cl2U(m‐Cl)3UCl2(
6‐C6Me6)]þ. (Reprinted with permission from Campbell et al. (1986). Copyright 1986 American Chemical Society.)

[N(R)Ar]2U(m‐Z6,Z6‐C7H8)U[N(R)Ar]2 (R ¼ adamantyl; Ar ¼ 3,5‐Me2C6H3), could also be generated in low yield by reaction of UI3(THF)4 with (Et2O)LiN (R)Ar in toluene. Structural characterization reveals that the complex contains a bridging toluene molecule bound symmetrically to the two metal centers (Fig. 25.26). The U–Cring distances are short relative to other Z6‐arene complexes, ranging ˚ . In addition, there is a slight distortion in the bound from 2.503(9) to 2.660(8) A ˚ toluene ligand; the average C–C distances increase by approximately 0.04 A from that in free toluene. Density functional calculations carried out on the molecule suggest that four electrons are engaged in the formation of two d‐ symmetry back‐bonds involving U 6d and 5f orbitals and the LUMO of the bridging arene molecule. The complex acts as a ‘uranium(II)’ reagents in subsequent reactions, and can effect four‐electron reduction of substrates. (b) Other carbocyclic ligands (cycloheptatrienyl, pentalene, endohedral metallofullerenes) Complexes of actinides with five‐, six‐, and eight‐membered rings have already been described. It is only recently that this series has been completed with the preparation of complexes employing the cycloheptatrienyl ligand. Unlike the other members of this series, the first complex to be prepared was not the sandwich complex, but rather the ‘inverse sandwich’ compound [X3U(m‐Z7, Z7‐C7H7)UX3]– (X ¼ NEt2, BH4), formed in the reaction of U(NEt2)4 or

Carbon‐based ancillary ligands

2861

Fig. 25.26 Molecular structure of [N(R)Ar]2U(m‐
6,
6‐C7H8)U[N(R)Ar]2 (R ¼ adamantyl, Ar ¼ 3,5‐Me2C6H3). Bulky peripheral substituents omitted for clarity. (Reprinted with permission from Diaconescu et al. (2000). Copyright 2000 American Chemical Society.)

U(BH4)4 with K(C7H9) (Arliguie et al., 1994). The sandwich complex [K(18‐ crown‐6)][(Z7‐C7H7)2U] has subsequently been prepared [equations (25.87) and (25.88)] (Arliguie et al., 1995).

UCl4 þ 4KðC7 H7 Þ

THF 18
crown
6

½Kð18-crown-6Þ½ðZ7 -C7 H7 Þ2 U

ð25:88Þ

The molecular structure of the anion [(Z7‐C7H7)2U]– is shown in Fig. 25.27. The complex consists of a sandwich of crystallographic C2h symmetry. The ˚ , and display a regular cycloheptatrienyl ligands are planar to within 0.02 A heptagonal geometry. The two rings are staggered. The uranium–carbon ˚ , significantly shorter than those found for bond distances average 2.53(2) A typical tetravalent uranium cyclopentadienyl and cyclooctatetraenyl complexes. Similar bond shortening has been observed in M–C bonds in early transition metal cycloheptatrienyl complexes, and has been explained as reflecting electron transfer from the metal to the ligand, with an increase in metal valency. Some attention has therefore been given to the assignment of oxidation state in this complex. A density functional study examined the question of bonding in the complexes (Z7‐C7H7)2An (Li and Bursten, 1997). It was found that the 5f d‐symmetry orbitals not only participate in the bonding with e002 pp orbitals of the C7H7 rings, but are as important as the

2862

Organoactinide chemistry: synthesis and characterization

Fig. 25.27 Molecular structure of [(
7‐C7H7)2U]– (Arliguie et al., 1995). (Reproduced by permission of The Royal Society of Chemistry.)

symmetry‐appropriate 6d orbitals in stabilizing the ligand‐based fragment orbitals. The 5f percentage in frontier e2 molecular orbitals increases across the series, although not the energetic stabilization. The most important bonding interactions are shown in Fig. 25.28. Although only one valence electron resides in a principally 5f localized orbital in the known uranium complex, a formal oxidation state of þ3 (5f3) was assigned to uranium, based on the fact that the 3e002 molecular orbitals (occupied by four electrons) are nearly 50% 5f in character, and so two of these electrons were assigned to the metal. EPR and ENDOR studies of [(Z7‐C7H7)2U]– suggest that the complex could be treated as 5f1, with a ground state molecular orbital comprised of both 5fp and 5fs orbitals (Gourier et al., 1998). Although the cyclooctatetraenyl dianion has been extensively employed in actinide organometallic chemistry, another C8 ligand, the pentalene dianion ðC8 H2
6 Þ has been far less studied, due to the difficulty inherent in its preparation. The ligand may be considered to be derived from C8 H2
8 by removal of two hydrogen atoms with generation of a C–C bond to yield two fused five‐membered rings.

Carbon‐based ancillary ligands

2863

Fig. 25.28 Bonding interactions in [(
7‐C7H7)2U]– under D7h symmetry. UNR and UR indicate atomic orbital energies at the nonrelativistic and relativistic levels, respectively. Ch ¼
7‐C7H7. (Reprinted with permission from Li and Bursten (1997). Copyright 1997 American Chemical Society.)

A substituted derivative of the pentalene ligand, [1,5‐(SiiPr3)2C8H4]2–, has been employed to generate the neutral bis(ligand) uranium and thorium compounds [Z8‐1,5‐(SiiPr3)2C8H4]2Th and [Z8‐1,5‐(SiiPr3)2C8H4]2U, which are rare examples of Z8‐coordinated pentalene ligands (Cloke and Hitchcock, 1997; Cloke et al., 1999). The molecular structure of the thorium compound revealed it to be a near‐equal mixture of staggered and eclipsed sandwich isomers in a disordered structure. The two isomers are generated by thorium binding to two different prochiral faces of the ligand; as such the isomers are not found in NMR studies to interconvert on any timescale in solution.

2864

Organoactinide chemistry: synthesis and characterization

The larger actinide ion accommodates a smaller bending, or ‘folding’ angle about the bridgehead C–C bond (24 , compared to 33 in a related tantalum ˚. compound). The Th–Cring bond lengths vary from 2.543(10) to 2.908(11) A Photoelectron spectroscopy studies and density functional calculations present a consistent picture of the bonding in these complexes. Metal–ligand bonding takes place chiefly through four molecular orbitals with both 6d and 5f orbital involvement (although 6d orbitals again make a larger contribution); the uranium compound further houses two unpaired electrons in 5f‐based orbitals. Both the f‐ionization and the highest lying ligand orbitals have lower ionization energies than uranocene or (Z5‐C5H5)4U, suggesting that the pentalene dianion is a stronger donor ligand than other carbocyclic groups. Among the largest discrete organometallic ligands that could be identified would be fullerenes, and many metal‐encapsulated derivatives, or endometallofullerene complexes have been identified. The first reports of possible uranium encapsulation (Haufler et al., 1990; Guo et al., 1992) suggested that the principal products from laser vaporization experiments with graphite and UO2 in a supersonic cluster beam apparatus included U@C60 and the product of the unusually small cage U@C28. XPS studies of the bulk product suggested a uranium valence of 4þ in the complex. A subsequent report identified U@C60 and U@C82 in the sublimed soot (Diener et al., 1997). Most recently, metallofullerenes of uranium, neptunium, and americium have been produced via arc‐ discharge using a carbon rod containing lanthanum as a carrier with 237U, 239 Np, and 240Am as radiotracers (Akiyama et al., 2001). The metallofullerenes were purified by CS2 extraction and toluene HPLC elution. The dominant products identified for neptunium and americium were An@C82. Two uranium‐containing metallofullerenes were identified, U@C82 and U2@C80. Based upon comparison with the optical spectra of lanthanide analogs, it was suggested that the oxidation state in these complexes might best be regarded as þ3. Electronic structure calculations have been carried out on U@C60, U@C28, and Pa@C28 (Chang et al., 1994; Zhao and Pitzer, 1996). The ground state of Pa@C28 was found to have one electron in a cage p* orbital, suggested a higher overall oxidation state for the metal. Similarly, U@C28 had a (p*)1(5f)1

Carbon‐based ancillary ligands

2865

diamagnetic ground state. In all cases, the complexes show extensive mixing of p‐orbitals with both 6d and 5f orbitals, suggesting strong bonding. 25.2.4

Allyl, pentadienyl and related p‐ligands

Allyl complexes with associated cyclopentadienyl ligands have been discussed previously. There are, however, several classes of complexes reported for thorium and uranium that contain allyl or other ‘open’ p‐system ligands. Tetrakis (allyl) and substituted allyl complexes of thorium and uranium can be prepared by the reaction of the tetrachloride complexes with the appropriate Grignard reagent (Wilke et al., 1966; Lugli et al., 1969; Brunelli et al., 1973), although they are thermally unstable and decompose at temperatures greater than –20 C [equation (25.89)].

Mixed‐ligand complexes are known to be somewhat more stable. As an example, the reaction of (Z5‐C3H5)4U with aliphatic alcohols has been reported to generate the mixed‐ligand complexes [(Z5‐C3H5)2An(OR)2]2 (Brunelli et al., 1979); the structure of the isopropoxide derivative has been determined. The complex exists as a dimer in the solid state, with two bridging alkoxide ligands, although they are proposed to be monomeric in THF solution. The allyl ligands are bound trihapto, which is consistent with the proposed mode of coordination for allyl ligands in the homoleptic compounds, as determined by solution NMR studies. A further example is provided by the reaction of (Z5‐C3H5)4U with 2,20 ‐ bipyridine. The product generated is more thermally stable, likely due to the incorporation of three Lewis bases into the coordination sphere of the metal. It is proposed that this is made possible by the transfer of two of the allyl groups to one or more of the bipyridine ligands (Vanderhooft and Ernst, 1982). A more stable ‘open’ p‐system is provided by the pentadienyl ligand. Since pentadienyl complexes are generally considered to be more reactive than cyclopentadienyl ligands, it has often proven necessary to employ substituted derivatives. The 2,4‐dimethylpentadienyl ligand was first used in the generation of a homoleptic compound of U(III) [equation (25.90)] (Cymbaluk et al., 1983b).

2866

Organoactinide chemistry: synthesis and characterization

The mixed‐ligand complex [K(18‐crown‐6)][(Z5‐2,4‐Me2C5H5)2U(BH4)2] has been prepared either by reaction of (Z5‐mesitylene)U(BH4)3 with K(2,4‐ Me2C5H5), or by reaction of (Z5‐2,4‐Me2C5H5)3U with KBH4 (Baudry et al., 1989b). The reaction of (Z5‐2,4‐Me2C5H5)3U with [Et3NH][BPh4] has been reported to generate a cationic complex [(Z5‐2,4‐Me2C5H5)2U][BPh4]. The tetravalent derivatives (Z5‐2,4‐Me2C5H5)2U(BH4)2 and (Z5‐2,4‐Me2C5H5)U (BH4)3 have been generated by the reactions of (Z5‐2,4‐Me2C5H5)3U with TlBH4 or U(BH4)4 with K(2,4‐Me2C5H5), respectively (Baudry et al., 1989c). Comparable reactions have also been carried out with the related 6,6‐ dimethylcyclohexadienyl ligand. Reaction of U(BH4)4 with K(6,6‐Me2C6H5) generates the bis(ligand) compound, (Z5‐6,6‐Me2C6H5)2U(BH4)2 as shown in equation (25.91) (Baudry et al., 1990b).

In order to generate the mono(ligand) compound, (Z5‐6,6‐Me2C6H5)U (BH4)3, it is necessary to react U(BH4)4 with (Z5‐6,6‐Me2C6H5)2U(BH4)2 in a ligand redistribution reaction (Baudry et al., 1990b). The anionic compounds [K (18‐crown‐6)][(Z5‐6,6‐Me2C6H5)2UX2] (X ¼ Cl, BH4) were synthesized by treatment of UCl4 or (Z6‐mesitylene)U(BH4)3 with K(6,6‐Me2C6H5). Although no alkyne coordination complex of an actinide has been isolated, alkyne complexes have been proposed as intermediates in the catalytic dimerization of terminal alkynes by cationic amide complexes, based upon spectroscopic evidence (Wang et al., 1999; Dash et al., 2000). 25.2.5

Alkyl ligands

Early attempts to prepare homoleptic alkyl complexes of the actinides resulted only in the formation of organic decomposition products and uranium metal, suggesting thermal instability (Gilman, 1968). Various methods of steric stabilization have been employed to enhance the stability of alkyl complexes, including reactions designed to generate uranate complexes, and the introduction of ancillary bases to block the elimination reactions believed to occur during decomposition. The reactions of uranium and thorium tetrachlorides with excess alkyllithium reagents yield isolable products [equations (25.92) and (25.93)] (Andersen et al., 1975; Sigurdson and Wilkinson, 1977; Lauke et al., 1984).

Carbon‐based ancillary ligands UCl4 þ XS RLi

xs L

½LiðLÞn 2 ½UR6 

R ¼ CH3 ; C6 H5 ; CH2 ðSiMe3 Þ2 L ¼ Et2 O; THF; n ¼ 4; L ¼ TMEDA; n ¼ 3:5 ThCl4 þ xs CH3 Li þ xs TMEDA ½LiðTMEDAÞ3 ½THðCH3 Þ7   TMEDA þ 4LiCl

2867

ð25:92Þ

ð25:93Þ

While the uranium compounds are reported to decompose above room temperature, the thorium compound is stable for hours at room temperature, and the crystal structure has been determined. The thorium is hepta‐coordinate, with a monocapped trigonal prismatic geometry. Six of the methyl groups also bridge ˚ ], while the to the three lithium counter‐ions [Th–C ¼ 2.667(8)–2.765(9) A ˚ seventh methyl group is terminal [Th–C ¼ 2.571(9) A]. The other proven route to stabilization of alkyl complexes involves the use of coordinating phosphines to sterically saturate the coordination sphere. The bis (1,2‐dimethylphosphino)ethane (dmpe) complexes of uranium and thorium tetrachloride have been prepared; metathesis reactions with these precursors yield thermally stable alkyl complexes [equations (25.94) and (25.95)] (Edwards et al., 1981, 1984): ðdmpeÞ2 AnCl4 þ 4RLi An ¼ Th; U R ¼ CH3 ; CH2 C6 H5 ðdmpeÞ2 AnCl4 þ 3LiðCH2 C6 H5 Þ þ LiCH3 An ¼ Th; U

ðdmpeÞ2 AnR4 ð25:94Þ

ðdmpeÞ2 AnðCH3 ÞðCH2 C6 H5 Þ3 ð25:95Þ

The only neutral homoleptic actinide complex characterized to date is U[CH(SiMe3)2]3, produced by the reaction of U(O‐2,6‐tBu2C6H3)3 with Li[CH(SiMe3)2] in hexane (Van Der Sluys et al., 1989). The molecular structure is shown in Fig. 25.29. Unlike comparable first‐row transition metal tris(alkyl) complexes, the compound has a pyramidal geometry, with a C–U–C angle of 107.7(4) , and a U–C ˚ . The complex is thermally stable in the solid state at bond distance of 2.48(2) A room temperature, but decomposes with loss of alkane at temperatures greater than 60 C. Reaction of UCl3(THF)x with three equivalents of Li[CH(SiMe3)2] does not generate the neutral complex, but rather an ionic complex formulated as [Li(THF)3][(Cl)U{CH(SiMe3)2}3]. The neptunium and plutonium analogs An[CH(SiMe3)2]3 have been reported (Zwick et al., 1992), although not fully characterized.

2868

Organoactinide chemistry: synthesis and characterization

Fig. 25.29 Molecular structure of [CH(SiMe3)2]3U. (Reprinted with permission from Van Der Sluys et al. (1989). Copyright 1989 American Chemical Society.) 25.3 HETEROATOM‐CONTAINING p‐ANCILLARY LIGANDS

25.3.1

Dicarbollide ligands

Although not strictly carbocyclic ligands, 1,2‐dicarbollide groups ðC2 B9 H2
11 Þ have been employed as ancillary ligands in organoactinide chemistry, and deserve inclusion owing to their structural analogy to cyclopentadienyl groups. This ligand has been used in the synthesis of a number of mono‐ and bis‐ligand analogs of cyclopentadienyl complexes. The first report of a dicarbollide complex was the generation of an anionic ‘bent metallocene analog’ [equation (25.96)] (Fronczek et al., 1977). UCl4 þ 2Li2 ðC2 B9 H11 Þ

THF

½LiðTHFÞ4 2 ½ðZ5 -C2 B9 H11 Þ2 UCl2  þ 2LiCl ð25:96Þ

The complex has a geometry analogous to a typical metallocene complex, with pentahapto dicarbollide ligands. The two carbons of the capping face could not be definitively distinguished, although a model was suggested that placed the carbon atoms closest to the coordinated chloride ligands. The U–B(C) bond ˚ . The average value of 2.73(2) A ˚ distances range from 2.64(3) to 2.86(3) A is similar to that found in typical U(IV) cyclopentadienyl complexes. A uranium(IV) dibromide analog has since been reported (Rabinovich et al., 1996), as have thorium complexes [Li(THF)4]2[(Z5‐C2B9H11)2ThX2] (X ¼ Cl, Br, I) (Rabinovich et al., 1997). The uranium(IV) dibromide complex can be chemically reduced to generate a uranium(III) complex, [Li(THF)x]2[(Z5‐C2B9H11)2UBr (THF)] (de Rege et al., 1998). Trivalent mono‐ligand complexes can also be generated by metathesis reactions with UI3(THF)4 [equation (25.97)]

Heteroatom‐containing p‐ancillary ligands

2869

(Rabinovich et al., 1996): UI3 ðTHFÞ4 þ 2Li2 ðC2 B9 H11 Þ þ TMEDA

THF

½LiðTMEDAÞ

½ðZ -C2 B9 H11 ÞUI2 ðTHFÞ2  þ LiI 5

ð25:97Þ

A single report has appeared on the complexation of uranium by another carborane anion [equation (25.98)] (Xie et al., 1999). THF

UCl3 þ 12K þ 4o-C2 B10 H12

½fK2 ðTHFÞ5 g

fðZ -C2 B10 H12 ÞðZ6 -C2 B10 H12 ÞUg2 þ 8KCl 7

25.3.2

ð25:98Þ

Phospholyl ligands

The closest p‐ligand analogs to cyclopentadienyl groups in this class are phosphole compounds and their derivatives. Of these potential ligands, the tetramethylphospholyl group has been employed to generate actinide complexes. The initial report involved introduction of the phospholyl ligand to the metal center by metathesis [equations (25.99) and (25.100)] (Gradoz et al., 1992a): UðBH4 Þ4 þ 2KðMe4 C4 PÞ UðBH4 Þ4 þ KðMe4 C4 PÞ

ðZ5 -Me4 C4 PÞ2 UðBH4 Þ2 ðZ5 -Me4 C4 PÞUðBH4 Þ3

ð25:99Þ ð25:100Þ

Reduction of these complexes in THF by sodium amalgam affords trivalent uranate anions. Reaction of trivalent uranium precursors with the phospholyl salt also yields the uranate species. The molecular structure of the U(IV) product (Z5‐Me4C4P)2U(BH4)2 has been described and is presented in Fig. 25.30 (Baudry et al., 1990c). The complex is structurally very similar to a bis(cyclopentadienyl) metallocene. The phospholyl ring remains planar upon coordination to the uranium center, and coordinates in a pentahapto manner. The average metal–carbon ˚ , comparable to that found in U(IV) metallocene bond distance is 2.81(4) A ˚ . The complex (Z5‐Me4C4P)2UCl2 complexes, and the U–P distance is 2.905(8) A was subsequently generated from the reaction of UCl4 with the potassium salt of the phospholyl (Gradoz et al., 1994a). The tris(phospholyl) complexes have been produced from uranium tetrachloride [equation (25.101)] (Gradoz et al., 1992b): UCl4 þ 3KðMe4 C4 PÞ

ðZ5 -Me4 C4 PÞ3 UCl þ 3KCl

ð25:101Þ

The chloride may be further substituted to generate alkyl, hydrido, and alkoxide species.

2870

Organoactinide chemistry: synthesis and characterization

Fig. 25.30 Molecular structure of (
5‐Me4C4P)2U(BH4)2 (Baudry et al., 1990c). (Reprinted with permission from John Wiley & Sons, Inc.)

Mono‐ring complexes of the formula (Z5‐Me4C4P)UCl3(DME) and (Z5‐ Me4C4P)UCl3(THF)2 are prepared by the reaction of UCl4 and K(Me4C4P) in the appropriate solvent (Gradoz et al., 1994a). It is the borohydride derivative (Z5‐Me4C4P)U(BH4)3 and its pentamethylcyclopentadienyl analog (Z5‐C5Me5) U(BH4)3 that serve as reagents in most reported subsequent metathesis reactions as illustrated in equation (25.102) for the preparation of the mixed‐ring complex (Z5‐C5Me5)(Z5‐Me4C4P)U(BH4)2:

The complexes (Z5‐Me4C4P)2U(BH4)2, (Z5‐Me4C4P)U(BH4)3, and (Z5‐C5Me5) (Z5‐Me4C4P)U(BH4)2 serve as precursors for a number of alkyl and alkoxide derivatives (R ¼ Me, CH2SiMe3, OEt, OiPr, and OtBu). The mixed‐ring compounds (Z8‐C8H8)(Z5‐Me4C4P)U(BH4)(THF) and K [(Z8‐C8H8)(Z‐Me4C4P)2U(BH4)(THF)x] can be generated by the reaction of

Heteroatom‐containing p‐ancillary ligands

2871

(Z8‐C8H8)U(BH4)2(THF) or [(Z8‐C8H8)U(BH4)(THF)2][BPh4], respectively, with K(Me4C4P). The cationic complex [(Z8‐C8H8)U(Z5‐Me4C4P)(HMPA)2] [BPh4] is isolated from the reaction of [(Z8‐C8H8)U(HMPA)3][BPh4] with the potassium phospholyl salt (Cendrowski‐Guillaume et al., 2002). The dimeric trivalent compound [(Z5‐Me4C4P)(m,Z5,Z1‐Me4C4P)U(BH4)]2 constitutes a rare example of a dimeric phospholyl complex, in which each phospholyl ligand phosphorus atom serves as a donor to the other uranium atom (Gradoz et al., 1994b). The molecular structure of the complex reveals pseudo‐tetrahedral uranium coordination, with the borohydride ligands on the same side of the U2P2 plane (Fig. 25.31). The metrical data indicate no apparent strain introduced by the dimer formation; U‐ring atom bond distances and centroid‐metal‐centroid angles are not significantly distorted from the values found for (Z5‐Me4C4P)2U ˚ , U–Pave ¼ 2.970(3) A ˚ ] (Fig. 25.30). The bridging (BH4)2 [U–Cave ¼ 2.84(3) A ˚ . Although it has been suggested that the phosphoP!U distance is 2.996(3) A rus lone pair of the phospholyl group should lie in the ring plane, the P!U‐ring centroid angle in this complex is 159.0(3) , suggesting that U2P2 ‘ring closure’ imposes a steric requirement for bending about the donor phosphorus atom. 25.3.3

Pyrrole‐based ligands

The nitrogen‐based analog, the pyrrole ligand, has not been found by itself to support pentahapto coordination to actinide centers, presumably due to the relative ‘hard’ basic character of the nitrogen in the heterocycle. Examples of (Z5‐C4N) coordination may instead be found in the reaction products of uranium halides with the tetraanion of the macrocycle [{(–CH2–)5}4‐calix[4]tetrapyrrole] (Korobkov et al., 2001a). As described in equation (25.103), the reaction of UI3(THF)4 with the potassium salt of the tetrapyrrolide in THF generates a dinuclear U(IV) complex, [{[{(–CH2–)5}4‐calix[4]tetrapyrrole]UK(THF)3}2 (m‐O)]·2THF; the oxo group is proposed to come from deoxygenation of a THF molecule.

2872

Organoactinide chemistry: synthesis and characterization

Fig. 25.31 Molecular structure of [(
5‐Me4C4P)(m
5
1‐Me4C4P)U(BH4)]2. The H atoms of the BH4 ligand have been omitted for clarity (Gradoz et al., 1994b). (Reprinted with permission from Elsevier.)

Reaction of UI3(THF)4 with the corresponding lithium tetrapyrrolide salt in a 1:2 ratio generates instead [{[(–CH2–)5]4‐calix[4]tetrapyrrole}ULi(THF)2]2 · hexane, in which the b‐carbon of one of the pyrrole rings has undergone a metallation reaction (Fig. 25.32). Reaction of the potassium salt with UI3(DME)4 avoids the complication of THF activation, and the simple trivalent uranate complex, [{[(–CH2–)5]4‐calix [4]tetrapyrrole}U(DME)][K(DME)], is generated. The geometry about the metal center in these compounds is qualitatively similar to a metallocene complex. The ligand adopts a s/p‐bonding mode, in which two of the four pyrrole rings in the macrocycle are Z5‐bonded to the uranium, and the other two rings are s‐coordinated only through the pyrrole nitrogen. The U–N (s) bond ˚ ; these distances lengths for the tetravalent derivatives range from 2.39 to 2.47 A ˚ ). The p‐coordination of are slightly longer in the trivalent derivative (ca. 2.53 A ˚ in the pyrrole ring yields somewhat longer U–N bond distances (ca. 2.65 A ˚ in the trivalent compound), and U–Cpyrrole bond tetravalent compounds, 2.74 A ˚. distances that range from 2.68 to 2.88 A Reaction of UI3(THF)4 with [Li(THF)]4{[(–CH2–)5]4‐calix[4]tetrapyrrole} in a substoichiometric (2:1) ratio generates the dinuclear complex [Li(THF)4]2 [U2I4{[(–CH2–)5]4‐calix[4]‐tetrapyrrole}] (Fig. 25.33) in moderate yield (Korobkov et al., 2001b).

Heteroatom‐containing p‐ancillary ligands

2873

Fig. 25.32 Molecular structure of [{(–CH2–)4‐calix[4]‐pyrrole}ULi(THF)2]2. (Reprinted with permission from Korobkov et al. (2001a). Copyright 2001 American Chemical Society.)

Partial reduction of UCl4, followed by reaction with one half of an equivalent of the lithium salt is reported to generate the mixed‐valence compound [Li (THF)2](m‐Cl)2{U2[(–CH2–)5]4‐calix[4]tetrapyrrole}Cl2·THF. Both of these complexes display alternate s/Z5, p‐coordination to opposite pairs of pyrrole ligands in a single tetrapyrrole group. The bridging nature of the macrocyclic ligand brings the uranium centers into relatively close proximity (3.4560(8) and ˚ , respectively); magnetic susceptibility measurements on the U(III)/U 3.365(6) A (III) dimer suggests weak antiferromagnetic coupling occurs between metal centers. 25.3.4

Other nitrogen‐containing p‐ligands

Amidinate ligands have been employed as ancillary ligands in the generation of organometallic compounds of tetravalent uranium and thorium, as well as complexes with the uranyl ion. Reaction of Li[N(SiMe3)2] and Na[N(SiMe3)2] with para‐substituted benzonitriles yields the benzamidinate ligands M[4‐ RC6H4C(NSiMe3)2] (M ¼ Li, Na; R ¼ H, Me, OMe, CF3).

2874

Organoactinide chemistry: synthesis and characterization

Fig. 25.33 Molecular structure of [Li(THF)4]2[U2I4{[(–CH2–)5]4‐calix[4]‐tetrapyrrole}]. (Reprinted with permission from Korobkov et al. (2001b). Copyright 2001 American Chemical Society.)

Alternatively, more substituted ligands Li[2,4,6‐R3C6H2C(NSiMe3)2] (R ¼ CF3, Me) are generated by the addition of aryllithium reagents to Me3SiN¼C¼NSiMe3. The amidinate ligands (L) have been used to generate complexes of the formula L2AnCl2 (An ¼ Th, U) and L3AnCl (for less

Heteroatom‐containing p‐ancillary ligands

2875

sterically demanding substituents) by metathesis reactions (Wedler et al., 1990). Substitution of the halide precursors has been reported to generate methyl and borohydride derivatives (Wedler et al., 1992a). The molecular structure of the complex [C6H5C(NSiMe3)2]3UMe has been determined. The benzamidinate ligands coordinate to the metal center in a Z3‐manner; the relatively long U–C ˚ is taken as an indication of steric crowding in the complex. s bond of 2.498(5) A The benzamidinate ligands have been found to support a range of oxidation states in uranium chemistry. The uranyl complex [C6H5C(NSiMe3)2]2UO2 complex was prepared by a metathesis reaction with UO2Cl2 (Wedler et al., 1988), and the interesting pentavalent derivative [4‐MeC6H4C(NSiMe3)2]2UCl3 was produced by adventitious aerobic oxidation during reaction of UCl4 with the corresponding silylated benzimidine [equation (25.104)] (Wedler et al., 1992b).

Related amidinate and 1‐aza‐allyl ligands also have been shown to generate bis(ligand)thorium dichloride complexes (Hitchcock et al., 1997), as well as an interesting mixed‐valence U(III)/U(VI) complex (Hitchcock et al., 1995).

A rare example of a U–C interaction in hexavalent actinide chemistry is found in the isolation of a bis(iminophosphorano)methanide uranyl complex (Sarsfield et al., 2002). Reaction of [UO2Cl2(THF)2]2 with Na[CH(Ph2P¼ NSiMe3)2] generates the dimer [UO2(m‐Cl){CH(Ph2P¼NSiMe3)2}]2.

2876

Organoactinide chemistry: synthesis and characterization

˚ ; the length indicates a very weak interThe U–C distance is 2.691(8) A action, although it falls within the sum of the van der Waals radii of the two atoms. 25.4 HETEROATOM‐BASED ANCILLARY LIGANDS

Although complexes containing primarily heteroatom‐donor ligands are less likely to be regarded as organometallic species, these ligands are playing an increasing important role in the development of non‐aqueous f‐element chemistry. The flexible steric and electronic characteristics of these ligands can stabilize unusual oxidation states and promote novel substrate activation reactions at actinide centers, making their study more attractive. Although not all ‘inorganometallic’ chemistry will be comprehensively reviewed here, discussion is warranted for certain classes of ligands that have played a significant role in the development of non‐aqueous actinide chemistry. 25.4.1

Bis(trimethylsilyl)amide

As an ancilliary ligand, the bis(trimethylsilyl)amide ligand [N(SiMe3)2]– has been shown to support a wide array of oxidation states of uranium. It has further been used in tetravalent actinide chemistry (An ¼ U, Th) to support metal centers that can effect a number of organic transformations. Trivalent homoleptic complexes [(SiMe3)2N]3An have been prepared for uranium, neptunium, and plutonium (Andersen, 1979; Clark et al., 1989; Zwick et al., 1992) by metathesis reactions [equations (25.105) and (25.106)]. UCl3  ðTHFÞx þ 3Na½NðSiMe3 Þ2  AnI3 ðTHFÞ4 þ 3Na½NðSiMe3 Þ2  An ¼ U; Np; Pu

THF

THF

½ðSiMe3 Þ2 N3 U

ð25:105Þ

½ðSiMe3 Þ2 N3 An

ð25:106Þ

The molecular structure of [(SiMe3)2N]3U has been determined (Stewart and Andersen, 1998). The geometry about the uranium center is trigonal pyramidal, ˚ , and a N–U–N angle of 116.24(7) . The with a U–N distance of 2.320(4) A

Heteroatom‐based ancillary ligands

2877

magnetic susceptibility shows that the complex has effective moments comparable to those determined for trivalent metallocenes and halides (meff ¼ 3.354(4), y ¼ –13 K at 5 kG), consistent with a 5f3 electronic configuration. This is confirmed by the photoelectron spectroscopy, which demonstrates a low‐energy 5f ionization band (Green et al., 1982). The steric congestion about the metal center prohibits isolation of stable base coordination compounds. Tetravalent complexes of the formula [(SiMe3)2N]3AnCl (An ¼ Th, U) have been prepared (Turner et al., 1979a) from the 3:1 reaction of NaN(SiMe3)2 with AnCl4 [(equation (25.107)], and the complex [(SiMe3)2N]2UCl2(DME) can be generated from a 2:1 reaction of ligand:halide salt (McCullough et al., 1981). AnCl4 þ 3Na½NðSiMe3 Þ2  An ¼ Th; U

THF

½ðSiMe3 Þ2 N3 An
Cl

ð25:107Þ

Substituted complexes of the formula [(SiMe3)2N]3AnR (An ¼ Th, U; R ¼ Me, Et, iPr, Bu, BH4) are formed by the reaction of [(SiMe3)2N]3AnCl with the appropriate lithium or magnesium reagent (Turner et al., 1979a; Dormond et al., 1988). Unlike comparable cyclopentadienyl analogs, the methyl compound does not undergo ready insertion of CO, although a number of other insertion and protonation reactions have been reported, including insertion of ketones, aldehydes, isocyanides, and aliphatic nitriles (Dormond et al., 1987b, 1988). The methyl ligand is further susceptible to removal by protic reagents such as secondary amines. The hydride compounds [(SiMe3)2N]3AnH (An ¼ Th, U) are the sole products of attempts to introduce an additional equivalent of the bis(trimethylsilyl) amide ligand to [(SiMe3)2N]3AnCl (Turner et al., 1979b). Pyrolysis of the hydride results in the loss of dihydrogen and the formation of an unusual metallacycle (Simpson and Andersen, 1981a).

The metallacycles of uranium and thorium have been shown to undergo a large number of insertion and protonation reactions (Simpson and Andersen, 1981b; Dormond et al., 1985, 1986a,b, 1987a,b, 1989a,b; Baudry et al., 1995), as shown in Fig. 25.34. In some cases these reactions (such as reduction of carbonyl‐containing organic compounds) have been found to be stereoselective. As in the case of substituted cyclopentadienyl complexes, the bis(trimethylsilyl)amide ligand is capable of supporting the formation of organoimido

Fig. 25.34 Reactions of uranium metallacycle.

Heteroatom‐based ancillary ligands

2879

complexes. The tetravalent uranium dimer [{(SiMe3)2N}2U(m‐N‐p‐C6H4Me)]2 was prepared by reaction of [(SiMe3)2N]3UCl with Li[N(H)(p‐C6H4Me)] [equation (25.108)] (Stewart and Andersen, 1995), presumably by a‐elimination of HN(SiMe3)2 from an intermediate amide complex:

As in the case of the related cyclopentadienyl compound, the arylimido ligand bridges the two metal centers in an asymmetric fashion, with U–N bond ˚. distances of 2.378(3) and 2.172(2) A Reaction of [(SiMe3)2N]3U with Me3SiN3 generates the uranium(V) organoimido complex [(Me3Si)2N]3U(¼NSiMe3) (Zalkin et al., 1988b). Both this and the related phenylimido complex are oxidized by mild oxidants such as AgPF6 or [Cp2Fe][PF6] to generate the U(VI) imido fluoride complexes [(Me3Si)2N]3U (¼NR)F (R ¼ SiMe3, Ph) as shown in equation (25.109) (Burns et al., 1990).

Both U(VI) complexes are trigonal bipyramidal with the bis(trimethylsilyl) amido groups occupying the equatorial positions. The F–U–Nimido angles are near linear, as are the U–N–Si(C) angles. The U¼Nimido bond lengths are 1.85 ˚ , respectively, for the silylimido and phenylimido complexes. (2) and 1.979(8) A

2880

Organoactinide chemistry: synthesis and characterization 25.4.2

Pyrazolylborate



Monoanionic poly(pyrazolyl)borate ligands ðBðpzÞ
4 ; HBðpzÞ3 ; H2 BðpzÞ2 , and substituted derivatives, pz ¼ pyrazol‐1‐yl) have found broad application as ancillary ligands in d‐transition metal chemistry as substitutes for cyclopentadienyl ligands (Trofimenko, 1993). Their s‐donor strength is comparable to that of a cyclopentadienyl ligand, although the precise ordering depends on the metal (Tellers et al., 2000). These ligands most commonly bind to f‐ elements in either a trihapto or dihapto geometry through nitrogen atoms in the pyrazolyl substituents. The first report of an actinide complex employing a poly(pyrazolyl)borate ligand was the preparation of complexes of the formula [H2B(pz)2]4U, [HB (pz)3]4U, and [HB(pz)3]2UCl2 by reaction of UCl4 with the potassium salt of the appropriate ligand (Bagnall et al., 1975). On the basis of 13C NMR spectroscopy, the HB(pz)3 ligands were assigned as bidentate in the complex [HB (pz)3]2UCl2, while the complex [HB(pz)3]4U was speculated to have two bidentate and two tridentate ligands (Bagnall et al., 1976). Since the initial identification of these compounds, the chemistry of poly‐ (pyrazolyl)borate ligands has expanded to include representatives involving trivalent actinides, most encompassing the substituted ligand HB(3,5‐Me2pz)3. The complex [HB(3,5‐Me2pz)3]UCl2 has been generated either by metathesis reaction of UCl3 with K[HB(3,5‐Me2pz)3] (Santos et al., 1985, 1986) or reduction of the U(IV) precursor [HB(3,5‐Me2pz)3]UCl3 with sodium naphthalenide (Santos et al., 1987). The complex is somewhat unstable, and upon recrystallization can be oxidized to generate the tetravalent oxo complex [{HB (3,5‐Me2pz)3}UCl(m‐O)]4 (Domingos et al., 1992a).

Recently, the use of uranium triiodide has become more common in the synthesis of trivalent complexes. Reaction of UI3(THF)4 with M[HB(3,5‐ Me2pz)3] (M ¼ Na, K) in a 1:1 or 1:2 ratio results in the formation of the compounds [HB(3,5‐Me2pz)3]UI2(THF)2 and [HB(3,5‐Me2pz)3]2UI, respectively (McDonald et al., 1994; Sun et al., 1994). In the monoligand compound,

Heteroatom‐based ancillary ligands

2881

the pyrazolylborate ligand is tridentate, while the bis(ligand) compound demonstrates two different coordination modes for the two [HB(3,5‐Me2pz)3] groups.

One of the ligands is Z3‐coordinated to the metal center, while in the second ligand, one of the pyrazolyl rings appears to coordinate in a ‘side‐on’ type of arrangement with the N–N bond of the ring within a bonding distance to the uranium atom. Upon abstraction of the iodide ligand with TlBPh4, however, this ligand reverts to a conventional tridentate geometry; the uranium center is seven‐coordinate in [{HB(3,5‐Me2pz)3}2U(THF)]þ, with the tetrahydrofuran ligand occupying the seventh site (McDonald et al., 1994). A limited number of U(III) complexes have been reported with other pyrazolylborate ligands. Uranium trichloride or triiodide reacts with the bis(pyrazolyl) borate ligands H2B(3,5‐Me2pz)2 and H2B(pz)2 to generate the species [H(m‐H)B (3,5‐Me2pz)2]3U and [H(m‐H)B(pz)2]3U(THF) (Carvalho et al., 1992; Sun et al., 1995). The coordinated tetrahydrofuran may be removed from the latter to yield the base‐free complex [H(m‐H)B(pz)2]3U. The solid state structure of [H(m‐H)B (3,5‐Me2pz)2]3U reveals that the metal lies in a trigonal prismatic arrangement of six pyrazole nitrogen atoms, with the three rectangular faces of the trigonal prism capped by three B–H bonds (Fig. 25.35). When a related ligand devoid of B–H bonds is employed (Ph2B(pz)2), the resulting tris(ligand) complex [Ph2B(pz)2]3U contains a six‐coordinate uranium center (Maria et al., 1999). The lower coordination number is considered to be ˚ versus 2.59(3) or the origin of slightly shorter U–N bond distances (2.53(3) A ˚ 2.58(3) A in the ten‐ and nine‐coordinate complexes, respectively). A mixed‐ alkyl substituted bis(pyrazolyl)borate complex has been produced by the reaction of UI3(THF)4 with K[H2B(3‐tBu,5‐Mepz)2]. The complex [H2B (3‐tBu,5‐Mepz)2]UI2(THF)2 reacts with Ph3P¼O to yield the base adduct [H2B(3‐tBu,5‐Mepz)2]UI2(O¼PPh3)2 (Maria et al., 1999).

2882

Organoactinide chemistry: synthesis and characterization

Fig. 25.35 Molecular structure of [H(m‐H)B(3,5‐Me2pz)2]3U. The PLUTO view is in the plane of one of the triangular faces of the trigonal prism (Carvalho et al., 1992). (Reprinted with permission from Elsevier.)

Only one complex of a trivalent transuranic metal has been reported; reaction of PuCl3 with K[HB(3,5‐Me2pz)3] in refluxing THF generates the dimeric complex [PuCl(m‐Cl){HB(3,5‐Me2pz)3}(3,5‐Me2pzH)]2 (Apostolidis et al., 1991, 1998).

Heteroatom‐based ancillary ligands

2883

The chemistry of tetravalent actinides with poly(pyrazolyl)borates has been explored more extensively. The first report of metathesis reactions with thorium involved the preparation of the compounds [HB(pz)3]4–nThXn (n ¼ 2, X ¼ Cl, Br; n ¼ 1, X ¼ Cl), [HB(3,5‐Me2pz)3]2ThCl2, [B(pz)4]2ThBr2, and base adducts of the complexes [HB(pz)3]ThCl3 and [HB(pz)3]4Th (Bagnall et al., 1978b), although subsequent reports have appeared describing other derivatives, including [HB(3,5‐Me2pz)3]ThCl3 (Ball et al., 1987). The larger ionic radius of thorium enables higher coordination numbers; unlike the uranium complexes, the thorium derivatives [HB(pz)3]2ThX2 (X ¼ Cl, Br) were shown spectoscopically to possess tridentate pyrazolylborate ligands. Several routes have been identified to produce [HB(pz)3]2UI2, including reaction of UI4 with two equivalents of K[HB(pz)3] in CH2Cl2 (Campello et al., 1994), oxidation of [HB(pz)3]2UI(THF)2 with iodine, and reaction of the tetravalent alkyl [HB(pz)3]2U(CH2SiMe3)2 with iodine (Campello et al., 1993). The reaction of UI4 with two equivalents of K[HB(pz)3] in THF does not yield the same compound, however. Instead, the iodobutoxide complex [HB (pz)3]2U(I)[O(CH2)4I] was isolated, presumably generated by ring‐opening of solvent (Collin et al., 1993; Campello et al., 1994). The smaller size of the U(IV) ion, combined with the larger steric size of the [HB(3,5‐Me2pz)3] ligand, inhibits formation of bis(ligand) complexes of the substituted poly(pyrazolyl)borate; reaction of UCl4 with two equivalents of K[HB(3,5‐Me2pz)3] leads to ligand degradation and the formation of [HB(3,5‐Me2pz)3]UCl2(3,5‐Me2pz) [equation (25.110)] (Marques et al., 1987a).

The complex [HB(3,5‐Me2pz)3]UCl3(THF) contains a relatively weakly coordinated solvent molecule; the base‐free complex can be isolated, and has been crystallographically characterized (Domingos et al., 1990). The THF is also readily replaced by a number of other coordinating bases, permitting comparisons of relative ligand affinity. The relative affinities of a series of bases for [HB (3,5‐Me2pz)3]UCl3 was found to be O ¼ PPh3 > C6 H11 NC > PhCN > MeCN > O ¼ PðOEtÞ3 > O ¼ PðO
nBuÞ3 > C5 H5 N > THF Attempts to introduce a larger poly(pyrazolyl)borate ligand have established the steric limits of this system. Reaction of UCl4 with one equivalent of the thallium salt of [HB(3‐Mspz)3]– (Ms ¼ mesityl) generates only the product containing an isomerized ligand, [HB(3‐Mspz)2(5‐Mspz)]UCl3 (Silva et al., 2000).

2884

Organoactinide chemistry: synthesis and characterization

A variety of metathesis reactions have been carried out with the bis(ligand) actinide species [HB(pz)3]2AnCl2 (An ¼ Th, U) to generate complexes containing oxygen, nitrogen, or sulfur donors (Santos et al., 1987; Domingos et al., 1989a, 1992b,c), as depicted in Fig. 25.36.

Fig. 25.36 Chemical reactions of [HB(pz)3]2AnCl2 (An ¼ Th, U).

Heteroatom‐based ancillary ligands

2885

Steric factors can be significant in these reactions. For example, reaction of bulky alkylamides with [HB(pz)3]2UCl2 generates only the monoamide complexes [HB(pz)3]2UCl(NR2). These complexes display restricted rotation about the U–N bond at room temperature, indicating a significant degree of steric saturation. Relatively few complexes have been isolated containing alkyl ligands. Many reactions of U(IV) with alkyllithium reagents result in reduction of the metal center. The complexes [HB(pz)3]2Th(CH2SiMe3)2, [HB(pz)3]2U(R) Cl (R ¼ Me, CH2SiMe3, o‐NMe2CH2C6H4) and [HB(pz)3]2UR2 (R ¼ Me, CH2SiMe3) have been reported (Domingos et al., 1992c; Campello et al., 1997). In an attempt to reduce the steric constraints of the ancillary ligand, derivatives of the mono(pyrazolylborate) complexes [HB(3,5‐Me2pz)3]AnCl3(THF) (An ¼ Th, U) have also been prepared (Marques et al., 1987b; Domingos et al., 1989b, 1992d; Leal et al., 1992). As before, the degree of substitution is often dependent on the size of the ligand introduced; tris(amide) derivatives such as [HB(3,5‐Me2pz)3]An(NR2)3 can be produced for R ¼ Et, Ph, whereas for the larger ligand [N(SiMe3)2]–, only a monoamide complex can be isolated. The monoalkoxide and monoaryloxide complexes of thorium have been reported to be unstable; uranium mono(phenoxide) and bis(phenoxide) complexes are only stable in the presence of a coordinating molecule of THF (Domingos et al., 1989b). The complex [HB(3,5‐Me2pz)3]UCl3(THF) is also susceptible to reduction by alkyllithium reagents; the full range of [HB(3,5‐ Me2pz)3]U(Cl)3–x(R)x complexes have been prepared only for R ¼ CH2SiMe3. Reaction of [HB(3,5‐Me2pz)3]UCl3(THF) with phenyllithium results in the formation of U(III) species (Silva et al., 1995), but the use of aryllithium reagents with bulky ortho‐substituents permits isolation of mono(aryl) products, [HB (3,5‐Me2pz)3]UCl2R. The reactivity of [HB(3,5‐Me2pz)3]UCl2(CH2SiMe3) and [HB(3,5‐Me2pz)3]UCl2[CH(SiMe3)2] toward unsaturated substrates has been investigated (Domingos et al., 1994); insertion similar to that reported in other alkyl complexes is observed. As an example, [HB(3,5‐Me2pz)3]UCl2(CH2SiMe3) reacts with stoichiometric amounts of aldehydes, ketones, nitriles, and isonitriles to yield the corresponding secondary and tertiary alkoxide, azomethine, and iminoalkyl products. The neptunium derivatives [HB(pz)3]2NpCl2 and [HB(3,5‐Me2pz)3] NpCl3(THF) have been produced from NpCl4 (Apostolidis et al., 1990). The reaction of uranium tetrachloride with two equivalents of the bulky ligand [B(pz)4]– as the potassium salt yields the complex [B(pz)4]2UCl2 (Campello et al., 1999). Although a limited number of derivatives of this compound could be produced, in general the ligand set provided less thermal stability than comparable complexes of the ‘[HB(pz)3]2U’ fragment. The complex [B(pz)4]2UCl2 displays eight‐coordinate geometry in the solid state, in a distorted square antiprismatic arrangement of ligands (Fig. 25.37). The complex is fluxional in solution; 1H NMR spectra demonstrate that all coordinated pyrazolylborate rings are equivalent. For the derivatives [B(pz)4]2UCl(OtBu), [B(pz)4]2UCl(O‐2,4,6‐Me3C6H2), [B(pz)4]2U(SiPr)2, and

2886

Organoactinide chemistry: synthesis and characterization

Fig. 25.37 Molecular structure of [B(pz)4]2UCl2 (Campello et al., 1999). (Reprinted with permission from Elsevier.)

[B(pz)4]2U(OtBu)2, it is possible to slow down the interconversion of the typical eight‐coordinate polyhedra (square antiprism ↔ dodecahedron ↔ bicapped trigonal prism). At higher temperatures, it was possible for some of these compounds to reach a regime where all pyrazolyl groups were equivalent on the NMR timescale, indicating dissociative exchange of free and coordinated rings. 25.4.3

Tris(amidoamine)

As in the case of early transition metals, the tris(amido)amine class of ligands, [N(CH2CH2NR)3]3– (R ¼ trialkylsilyl), has proven to be a versatile ligand set that supports unusual reactivity in the early actinides. Complexes of both thorium and uranium have been generated by metathesis reactions involving both the ligands [N(CH2CH2NSiMe3)3]3– and [N(CH2CH2NSitBuMe2)3]3–. The complexes [{N(CH2CH2NSiMe3)3}AnCl]2 (An ¼ Th, U) were the first to be reported (Scott and Hitchcock, 1994); the molecular structure of the uranium complex demonstrated it was dimeric in the solid state. The chloride ligand may

Heteroatom‐based ancillary ligands

2887

be substituted, and derivatives incorporating cyclopentadienyl, borohydride, alkoxide, amide, and diazabutadiene derivatives have been characterized (Scott and Hitchcock, 1995a,b; Roussel et al., 1997a, 1999). Attempts to alkylate the complex [N(CH2CH2NSitBuMe2)3]UI with alkyllithium or alkylpotassium reagents resulted in the isolation of a metallacyclic product resulting from intramolecular activation of a methyl group, as shown in equation (25.111) (Boaretto et al., 1999).

˚ ], The U–C bond length in the metallacyclic unit is unusually long [2.752(11) A and is susceptible to protonation by alcohols, amines, and terminal alkynes; reaction with pyridine leads to the generation of a Z2‐pyridyl complex. Initial attempts to reduce the complex [N(CH2CH2NSitBuMe2)3]UCl resulted in the formation of a mixed‐valence complex [{N(CH2CH2NSitBuMe2)3}U]2(m‐Cl) (Roussel et al., 1996, 1997b). The complex is thought to possess electronically distinct U(III) and U(IV) centers. Fractional sublimation results in the isolation of a purple species, identified as the trivalent [N(CH2CH2NSitBuMe2)3]U (Roussel et al., 1997b). This complex can also be produced by reduction of [N(CH2CH2NSitBuMe2)3]UI by potassium in pentane. A variety of base adducts of this complex have been reported (Roussel et al., 2002). The U(III) complex can similarly be oxidized by trimethylamine N‐ oxide, trimethylsilyazide, and trimethylsilyldiazomethane to yield m‐oxo, imido, and hydrazido derivatives, respectively (Roussel et al., 2002). One of the most unusual adducts isolated in this system is prepared by the reaction of the U(III) complex with dinitrogen [equation (25.112)].

The molecular structure of the complex has been reported (Roussel and Scott, 1998) (Fig. 25.38). The N–N distances in the dinitrogen unit are essentially unperturbed. Metrical data, along with magnetic data, suggest that the complex

2888

Organoactinide chemistry: synthesis and characterization

Fig. 25.38 Molecular structure of [{N(CH2CH2NSitBuMe2)3}U](m2‐
2:
2‐N2). (Reprinted with permission from Roussel and Scott (1998). Copyright 1998 American Chemical Society.)

may be best formulated as a U(III) species. The electronic structure of this complex has been investigated; the only significant U–N2–U interaction was found to consist of U!N2 p‐backbonding (Kaltsoyannis and Scott, 1998). 25.4.4

Other

Few other ligands have been developed with the steric bulk and solubility to stabilize mononuclear actinide complexes and support organometallic chemistry. A bulky amide ligand set has been developed for uranium that supports novel coordination complexes of lower valent uranium. Complexes of the formula (NRAr)3UI (R ¼ tBu, adamantyl; Ar ¼ 3,5‐Me2C6H3) may be prepared by the reaction of UI3(THF)4 with Li[NRAr] (Odom et al., 1998); oxidation of the uranium center is presumed to be accompanied by sacrificial generation of U(0). A limited number of tetravalent derivatives of this ligand set have been reported, including the silyl complex (NtBuAr)3U[Si(SiMe3)3] (Diaconescu et al., 2001) and the bridging cyanoimide complex (NtBuAr)3U¼ N¼C¼N¼U(NtBuAr)3 (Ar ¼ 3,5‐Me2C6H3) (Mindiola et al., 2001).

Bimetallic complexes

2889

Reduction of the uranium (IV) complex by sodium amalgam results in the isolation of (NtBuAr)3U(THF) (Ar ¼ 3,5‐Me2C6H3). Reaction of the trivalent complex with Mo[N(Ph)(R0 )]3 (R0 ¼ tBu, adamantyl) under dinitrogen results in the formation of [NtBuAr]3U(m‐N2)Mo[N(Ph)(R0 )]3, which contains a linear Mo–N–N–U unit. It is suggested that both metals are best regarded as tetravalent. As previously mentioned, reduction of (NtBuAr)3UI also provides entry into an interesting class of m‐arene complexes (vide supra). 25.5 BIMETALLIC COMPLEXES

One of the least explored aspects of the non‐aqueous chemistry of the actinides is that of complexes containing other metals. Bimetallic complexes have been studied with the intent of creating complexes with two centers of reactivity for effecting chemical transformations. In addition, interest has grown in creating true metal–metal bonds. These complexes are rare; metal–metal bonding is disfavored in the f‐elements with respect to d‐transition metals, perhaps due to the limited radial extent of valence d‐ and f‐orbitals most likely to be employed in bonding between two metal centers. Many of the early attempts to generate bimetallic complexes focused on metathesis reactions involving the introduction of anionic metal carbonylate ligands onto actinide cations (Bennett et al., 1971; Dormond and Moise, 1985). These reactions invariably resulted in the isolation of isocarbonyl species in which the actinide was bound by the oxygen atom of one or more carbonyl ligands [equation (25.113)]. UCl4 þ 4Na½MnðCOÞ5 

THF

U½MnðCOÞ5 4 þ 4NaCl

ð25:113Þ

More recently, synthetic efforts have been further expanded to include several classes of compounds in which bridging ligands hold two metal centers in close proximity, but no evidence exists for a metal–metal interaction. Bridging hydride complexes (Z5‐C5H5)3UH6ReL2 (L ¼ PPh3, P(p‐F‐C6H4)3) have been prepared by the reaction of (Z5‐C5H5)3UCl with [K(THF)2][L2ReH6] in THF (Baudry and Ephritikhine, 1986). The compounds are fluxional at room temperature in solution, judging from the equivalence of all hydride ligands in the 1H NMR spectrum, but it has been hypothesized that the Re and U centers are bridged by multiple hydride ligands. Ring‐substituted analogs (Z5‐ C5H4R)3UH6Re(PPh3)2 could not be prepared directly from (Z5‐C5H4R)3UCl; rather, the cationic reagent [(Z5‐C5H4R)3U][BPh4] was employed (Cendrowski‐ Guillaume and Ephritikhine, 1996). Reaction of (Z5‐C5Me5)2UCl(THF) with [K(THF)2][(PPh3)2ReH6] does not result in simple metathesis. Instead, an anionic product of the formula [K(THF)2][(Z5‐C5Me5)2U(Cl)H6Re(PPh3)2] is obtained (Cendrowski‐Guillaume et al., 1994; Cendrowski‐Guillaume and Ephritikhine, 1996). NMR data suggest that three hydride ligands bridge the two metal centers.

2890

Organoactinide chemistry: synthesis and characterization

Other examples of bimetallic complexes are generated using ligands on the actinide center that have pendant phosphine groups capable of binding transition metal centers. The diphenylphosphidocyclopentadienyl ligand acts as an electron‐poor carbocyclic ligand in the synthesis of bis‐ and tris‐cyclopentadienyl uranium complexes (Z5‐C5H4PPh2)3UX and (Z5‐C5H4PPh2)2UX2 (X ¼ Cl, OR, R, NEt2, BH4) (Dormond et al., 1990; Baudry et al., 1993). In reactions with suitable transition metal reagents, complexes can be prepared in which the diphenylphosphide group binds to a second metal center (Dormond et al., 1990; Baudry et al., 1993; Hafid et al., 1994) (equation (25.114)).

A second approach involves the use of cyclopentadienyl complexes in which the other substituents have pendant phosphine groups. A series of alkoxyphosphido complexes of uranium have been prepared for both bis‐ and tris‐cyclopentadienyl frameworks: (Z5‐C5Me5)2UCl[O(CH2)nPPh2], (Z5‐C5Me5)2U[O (CH2)nPPh2]2, and (Z5‐C5H5)3U[O(CH2)nPPh2] (n ¼ 0,1) (Dormond et al., 1994). These species react with (norbornadiene)M(CO)4 (M ¼ Mo, W) to yield bimetallic compounds. The complexes (Z5‐C5Me5)2U[O(CH2)nPPh2]2 generate 1:1 (U:M) products in which both phosphorus atoms are bound to a single transition metal. As illustrated in equation (25.115), the complexes (Z5‐ C5Me5)2UCl[O(CH2)nPPh2] and (Z5‐C5H5)3U[O(CH2)nPPh2] react to form 2:1 (U:M) adducts in which the metal carbonyl fragment is bound to one ‘arm’ of each of the uranium units:

The compounds containing the sterically less hindered OCH2PPh2 ligand react more quickly in substitution reactions that their counterparts containing OPPh2. The phospholyl ligand has also demonstrated the ability to bridge two metal centers in a m‐Z5,Z1 manner. Reduction of NiCl2 in the presence of the previously mentioned uranium phospholyl compound (Z5‐C5Me4P)2UCl2 yields the complex Cl2U(m‐Z5,Z1‐C5Me4P)2Ni(m‐Z5,Z1‐C5Me4P)2UCl2 in which the

Bimetallic complexes

2891

central nickel atom is bound in a near‐tetrahedral fashion by four phosphorus atoms from the four phospholyl ligands (Arliguie et al., 1996).

The dimeric nickel phospholyl complex (Z5‐C5Me4P)Ni(m‐Z1‐C5Me4P)2Ni (Z5‐C5Me4P) can also be prepared; reduction of this in the presence of two equivalents of (Z5‐C5Me4P)2UCl2 yields a tetrametallic complex [Cl2U(m‐Z5,Z1‐ C5Me4P)2Ni(m‐Z1‐C5Me4P)2Ni(m‐Z5,Z1‐C5Me4P)2UCl2] (Fig. 25.39). In these ˚ ) preclude direct metal–metal interaction. complexes, long U···Ni distances (>3.3 A Select compounds have been prepared in which the bridging ligands appear to coexist with a direct metal–metal interaction. The phosphido‐bridged complexes (Z5‐C5Me5)2Th(m‐PPh2)2MLn [MLn ¼ Ni(CO)2, Pt(PMe3)] are prepared by the reaction of the thorium phosphide precursor, (Z5‐C5Me5)2Th (PPh2)2 with an olefin complex of the appropriate transition metal species in the presence of additional ligand [equations (25.116) and (25.117)] (Ritchey et al., 1985; Hay et al., 1986).

Calculations performed on both complexes suggest the presence of a direct M– Th interaction (Hay et al., 1986; Ortiz, 1986). This contention appears to be supported both by 31P NMR and structural evidence. The thorium–metal distance in each compound is shorter than that expected on the basis of metal radii derived from related structures without metal–metal nonbonded distances ˚ , Th–Pt ¼ 2.984(1) A ˚ ]. Furthermore, the Th–M–P2 unit is [Th–Ni ¼ 3.206(2) A ‘folded’ about the phosphide ligands in each case to bring the two metal atoms

2892

Organoactinide chemistry: synthesis and characterization

Fig. 25.39 Molecular structure of [Cl2U(m‐
5,
1‐C5Me4P)2Ni(m‐
1‐C5Me4P)2Ni(m‐
5,
1‐ C5Me4P)2UCl2] (Arliguie et al., 1996). (Reprinted with permission from Elsevier.)

in closer proximity. Theoretical examination of these compounds suggest that the interaction is essentially a M!Th (M ¼ Ni, Pt) dative donor–acceptor bond, involving principally metal d‐orbitals. One class of compounds exist which possess an unsupported metal–metal interaction. Reaction of (Z5‐C5Me5)2ThX2 (X ¼ Cl, I) with Na[(Z5‐C5H5)Ru (CO)2] produces the complexes (Z5‐C5Me5)2Th(X)Ru(Z5‐C5H5)(CO)2 [equation (25.118)] (Sternal et al., 1985). This synthetic methodology has also been extended to include derivatives of the tris(cyclopentadienyl) framework [equation (25.119)] (Sternal and Marks, 1987).

The molecular structure of (Z5‐C5Me5)2Th(I)Ru(Z5‐C5H5)(CO)2 has been determined (Fig. 25.40); it confirms the presence of a direct metal–metal interac˚. tion, with a Th–Ru bond length of 3.0277(6) A

Neutral carbon‐based donor ligands

2893

Fig. 25.40 Molecular structure of (
5‐C5Me5)2Th(I)Ru(
5‐C5H5)(CO)2. (Reprinted with permission from Sternal et al. (1985). Copyright 1985 American Chemical Society.)

The bond distance is sensitive to the identity of the metal; the Th–Fe distance ˚ . Variable temperin the complex (Z5‐C5H5)3ThFe(Z5‐C5H5)(CO)2 is 2.940(5) A ature NMR data for the complexes (Z5‐C5H5)3AnM(Z5‐C5H5)(CO)2 (M ¼ Fe, Ru) suggest rotation about the metal–metal bond is hindered in solution at room temperature. Thermochemical measurements have determined U–M bond disruption enthalpies for the derivatives (Z5‐C5H5)3UM(Z5‐C5H5)(CO)2 [M ¼ Fe, 30.9 (3.0) kcal/mol; M ¼ Ru, 40.4 (4.0) kcal/mol], indicating relatively weak metal–metal interactions (Nolan et al., 1991). Consistent with this observation, the An–M interactions are easily disrupted by protic reagents. In addition, reaction of (Z5‐C5Me5)2Th(Cl)Ru(Z5‐C5H5)(CO)2 with coordinating bases (such as ketones or acetonitrile) generates (Z5‐C5H5)Ru(CO)2H, along with thorium products arising from C–H activation of the Lewis base substrate, followed by insertion of a second (and third) equivalent of the Lewis base (Sternal et al., 1987). Theoretical examination of the bonding (Z5‐C5Me5)2Th (I)Ru(Z5‐C5H5)(CO)2 (Bursten and Novo‐Gradac, 1987) demonstrates that once again, the bonding is best described as a Ru!Th dative donor–acceptor bond, involving principally Th 6d and Ru 4d orbitals.

25.6 NEUTRAL CARBON‐BASED DONOR LIGANDS

One of the most common ligands in d‐transition metal organometallic chemistry, the carbonyl ligand, is virtually unknown in actinide chemistry. Aside from the carbon monoxide adducts of tris(cyclopentadienyl)uranium previously described (see Section 25.2.1.1), there are no actinide carbonyl complexes that are

2894

Organoactinide chemistry: synthesis and characterization

isolable at room temperature and pressure. Uranium carbonyl complexes U (CO)n (n ¼ 1–6) were first reported to form in matrix isolation experiments and were produced by the condensation of thermally generated uranium vapor with carbon monoxide in an argon matrix at 4 K (Slater et al., 1971; Sheline and Slater, 1975). More recent studies indicate that thermal and pulsed‐laser evaporated uranium atoms undergo reaction with CO in argon matrices to generate the linear triatomic species CUO (Tague et al., 1993). Tague et al. (1993) indicate that higher uranium carbonyls (n > 2) are only produced upon subsequent annealing of the matrices to 15—30 K. Photolysis was reported to regenerate CUO from the carbonyls. The most recent class of Group 14 donor ligands to be employed in actinide chemistry is that of N‐heterocyclic carbenes. These ligands act as s‐donor bases toward a number of metals in coordination chemistry. Reaction of [UO2Cl2(THF)2]2 with 1,3‐dimesitylimidazole‐2‐ylidene and its 4,5‐dichlorosubstituted derivative generate 1:2 (uranium:carbene) adducts UO2Cl2(L)2 (Oldham et al., 2001). Crystallographic characterization reveals an octahedral metal center with trans oxo, chloro, and carbene ligands. The uranium–carbon ˚ , consistent bond distances in these species are long at 2.626(7) and 2.609(4) A with the formulation of the C–U bond as a dative interaction.

ACKNOWLEDGMENTS

C. J. Burns gratefully acknowledges support at LANL by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. M. S. Eisen thanks the Fund for the Promotion of Research at The Technion. C. J. Burns thanks Dr. J. Kiplinger for intellectual input and technical assistance.

REFERENCES Adam, M., Yunlu, K., and Fischer, R. D. (1990) J. Organomet. Chem., 387, C13–16. Adam, R., Villiers, C., Ephritikhine, M., Lance, M., Nierlich, M., and Vigner, J. (1993) J. Organomet. Chem., 445, 99–106. Andersen, R., Carmona‐Guzman, E., Mertis, K., Sigurdson, E., and Wilkinson, G. (1975) J. Organomet. Chem., 99, C19–20. Andersen, R. A. (1979) Inorg. Chem., 18, 1507–9. Apostolidis, C., Kanellakopulos, B., Maier, R., Marques, N., Pires de Matos, A., and Santos, I. (1990) 20e Journe´es des Actinides, Prague. Apostolidis, C., Kanellakopulos, B., Maier, R., Meyer, D., Marques, N., and Rebizant, J. (1991) 21e Journe´es des Actinides, Montechoro, Portugal.

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Starks, D. F. and Streitwieser, A. Jr (1973) J. Am. Chem. Soc., 95, 3423–4. Starks, D. F., Parson, T. C., Streitwieser, A. Jr, and Edelstein, N. (1974) Inorg. Chem., 13, 1307–8. Sternal, R. S., Brock, C. P., and Marks, T. J. (1985) J. Am. Chem. Soc., 107, 8270–2. Sternal, R. S. and Marks, T. J. (1987) Organometllics, 6, 2621–3. Sternal, R. S., Sabat, M., and Marks, T. J. (1987) J. Am. Chem. Soc., 109, 7920–1. Stewart, J. L. and Andersen, R. A. (1995) New J. Chem., 19, 587–95. Stewart, J. L. and Andersen, R. A. (1998) Polyhedron, 17, 953–8. Straub, T., Frank, W., Reiss, G. J., and Eisen, M. S. (1996) J. Chem. Soc., Dalton Trans., 2541–6. Straub, T., Haskel, A., Neyroud, T. G., Kapon, M., Botoshansky, M., and Eisen, M. S. (2001) Organometallics, 20, 5017–35. Streitwieser, A. Jr and Mu¨ller‐Westerhoff, U. (1968) J. Am. Chem. Soc., 90, 7364. Streitwieser, A. Jr and Yoshida, N. (1969) J. Am. Chem. Soc., 91, 7528. Streitwieser, A. Jr, Dempf, D., La Mar, G. N., Karraker, D. G., and Edelstein, N. M. (1971) J. Am. Chem. Soc., 93, 7343–4. Streitwieser, A. Jr and Harmon, C. A. (1973) Inorg. Chem., 12, 1102–4. Streitwieser, A. Jr and Walker, R. (1975) J. Organomet. Chem., 97, C41–2. Streitwieser, A. Jr, Kluttz, R. Z., Smith, K. A., and Luke, W. D. (1983) Organometallics, 2, 1873–7. Streitwieser, A. Jr, Barros, M. T., Wang, H. K., Boussie, T. R. (1993) Organometallics, 12, 5023–4. Strittmatter, R. J and Bursten, B. E. (1991) J. Am. Chem. Soc., 113, 552–9. Stults, S. D., Andersen, R. A., and Zalkin, A. (1989) J. Am. Chem. Soc., 111, 4507–8. Stults, S. D., Andersen, R. A., and Zalkin, A. (1990) Organometallics, 9, 1623–9. Sun, Y., McDonald, R., Takats, J., Day, V. W., and Eberspracher, T. A. (1994) Inorg. Chem., 33, 4433–4. Sun, Y., Takats, J., Eberspracher, T., and Day, V. (1995) Inorg. Chim. Acta, 229, 315–22. Tague, T. J. Jr, Andrews, L., and Hunt, R. D. (1993) J. Phys. Chem., 97, 10920–4. Tatsumi, K. and Nakamura, A. (1984) J. Organomet. Chem., 272, 141–54. Tatsumi, K., Nakamura, A., Hofmann, P., Stauffert, P., and Hoffmann, R. (1985) J. Am. Chem. Soc., 107, 4440–51. Tellers, D. M., Skoog, S. J., Bergman, R. G., Gunnoe, T. B., and Harman, W. D. (2000) Organometallics, 19, 2428–32. Telnoy, V. I., Rabinovich, I. B., Leonov, M. R., Solov’yova, G. V., and Gramoteeva, N. I. (1979) Dokl. Akad. Nauk. SSSR, 245, 1430–2. Telnoy, V. I., Rabinovich, I. B., Larina, V. N., Leonov, M. R., and Solov’yova, G. V. (1989) Sov. Radiochem., 31, 654–6. Templeton, L. K., Templeton, D. H., and Walker, R. (1976) Inorg. Chem., 15, 3000–3. Trnka, T. M., Bonanno, J. B., Bridgewater, B. M., and Parkin, G. (2001) Organometallics, 20, 3255–64. Trofimenko, S. (1993) Chem. Rev., 93, 943–80. Tsutsui, M., Ely, N., and Gebala, A. (1975) Inorg. Chem., 14, 78–81. Turner, H. W., Andersen, R. A., Zalkin, A., and Templeton, D. H. (1979a) Inorg. Chem., 18, 1221–4. Turner, H. W., Simpson, S. J., and Andersen, R. A. (1979b) J. Am. Chem. Soc., 101, 2782.

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CHAPTER TWENTY SIX

HOMOGENEOUS AND HETEROGENEOUS CATALYTIC PROCESSES PROMOTED BY ORGANOACTINIDES Carol J. Burns and Moris S. Eisen 26.1 26.2 26.3 26.4 26.5

26.6 26.7

26.8

26.9

Intramolecular hydroamination by constrained‐geometry organoactinide complexes 2990 26.10 The catalytic reduction of azides and hydrazines by high‐valent organouranium complexes 2994 26.11 Hydrogenation of olefins promoted by organoactinide complexes 2996 26.12 Polymerization of a‐olefins by cationic organoactinide complexes 2997 26.13 Heterogeneous supported organoactinide complexes 2999 References 3006

Introduction 2911 Reactivity of organoactinide complexes 2912 Oligomerization of alkynes 2923 Dimerization of terminal alkynes 2930 Cross dimerization of terminal alkynes catalyzed by [(Et2N)3U][BPh4] 2947 Catalytic hydrosilylation of olefins 2953 Dehydrocoupling reactions of amines with silanes catalyzed by [(Et2N)3U][BPh4] 2978 Intermolecular hydroamination of terminal alkynes 2981

26.1 INTRODUCTION

During the last two decades, the chemistry of organoactinides has flourished, reaching a high level of sophistication. The use of organoactinide complexes as stoichiometric or catalytic compounds to promote synthetically important organic transformations has matured due to their rich, complex, and 2911

2912

Homogeneous and heterogeneous catalytic processes

uniquely informative organometallic chemistry. Compared to early or late transition metal complexes, the actinides sometimes exhibit parallel and sometimes totally different reactivities for similar processes. In many instances the regiospecific and chemical selectivities displayed by organoactinide complexes are complementary to that observed for other transition metal complexes. Several recent review articles (Edelman et al., 1995; Edelmann and Gun’ko, 1997; Ephritikhine, 1997; Hitchcock et al., 1997; Berthet and Ephritikhine, 1998; Blake et al., 1998; Edelmann and Lorenz, 2000), dealing mostly with the synthesis of new actinide complexes, confirm the broad and rapidly expanding scope of this field. The aim of this chapter is to survey briefly and in a selective manner the catalytic chemistry of organoactinide complexes in homogeneous and heterogeneous catalytic reactions. A comprehensive review of the reactivities of actinide compounds has been published covering the literature until 1992 (Edelmann, 1995). This chapter reviews the new literature for the last decade. The treatment of this chapter is necessarily concise. We encourage the reader to seek the recent review articles and additional references given as an integral part of the subchapters for additional details and background material.

26.2 REACTIVITY OF ORGANOACTINIDE COMPLEXES

26.2.1

Modes of activation

Interest in the reactivity of organoactinide complexes is based on their ability to effect bond‐breaking and bond‐forming of distinctive moieties. The factors influencing these processes are both steric and electronic. A number of articles have been devoted to the steric control in organo‐5f‐complexes. Xing‐Fu et al. (1986a) have proposed a model for steric saturation, suggesting that the stability of a complex is governed by the sum of the ligand cone angles (Xing‐Fu et al., 1986a,b; Xing‐Fu and Ao‐Ling, 1987). In this model, highly coordinated ‘oversaturated’ complexes will display low stability. An additional model concerning steric environments has been proposed by Pires de Matos (Marc¸alo and Pires de Matos, 1989). This model assumes pure ionic bonding, and is based on cone angles defining the ‘steric coordination number’. A more important and unique approach to the reactivity of organo‐5f‐complexes regards the utilization of thermochemical studies. The knowledge of the metal–ligand bond enthalpies is of fundamental importance to allow the estimation of new reaction pathways (Marks et al., 1989; Jemine et al., 1992, 1993; King et al., 1992; Leal et al., 1992; Leal and Martinho Simo˜es, 1994; King and Marks, 1995; Leal et al., 2001). In addition, neutral organoactinides have been shown to follow a four‐center transition state in insertion reactions [equation (26.1)], suggesting that prediction of new actinide patterns of reactivity is possible taking into account the negatives entropies of activation (Marks and Day, 1985).

Reactivity of organoactinide complexes

2913

This chapter deals with the reactions of organoactinide complexes that comprise intermediate and key steps in catalytic processes, whereas the preceding chapter focuses in a more detailed and comprehensive fashion on the synthesis and characterization of similar complexes.

26.2.2

Stoichiometric reactions of organoactinide complexes of the type (C5Me5)2AnMe2

The different catalytic reactivity found for similar organoactinides, previously unprecedented in the chemistry of organoactinides, was the driving force for Haskel et al. (1999) to study the stoichiometric reactivity of organoactinide complexes of the type (C5Me5)2AnMe2 (An ¼ Th, U). These complexes have been widely used for the hydrogenation of olefins under homogeneous conditions (Fagan et al., 1981a; Fendrick et al., 1988; Lin and Marks, 1990). The reactivity of the actinide complexes towards alkynes and/or amines is outlined in Schemes 26.1 and 26.2 for Th and U, respectively. (C5Me5)2ThMe2 (1) was found to react with terminal alkynes producing the bisacetylide complexes (C5Me5)2Th(CCR)2 (2) (R ¼ tBu, TMS). The reaction of these bisacetylide complexes 2 with equimolar amounts of amine yielded half of an equivalent of the corresponding bisamido complexes (C5Me5)2Th(NHR)2 (5) and half of an equivalent of the starting bisacetylide complex, indicating that the second amine insertion into the thorium monoamido monoacetylide complex 4 was faster than the first insertion. The reaction of (C5Me5)2Th(CH3)2 (1) with an equimolar amount of amine resulted in the formation of the monoamido thorium methyl complex 3, which upon subsequent reaction with another equivalent of amine produced the bisamido complex 5. Heating complex 5, in THF, allowed the elimination of an amine molecule producing the formation of the thorium–imido complex 7. This complex also was formed by eliminating methane by heating complex 3 (Haskel et al., 1996). In the presence of an excess of amine, the bisamido complex 5, was found to be in rapid equilibrium with the bisamido–amine complex 6 (Straub et al., 1996), resembling lanthanide complexes (Gagne´ et al., 1992a,b; Giardello et al., 1994) though the equilibrium was investigated and found to lie towards the bisamido complex. Similar reactivity has been found for the corresponding uranium complex, 8 (Scheme 26.2). The reaction with alkynes produced the bisacetylide complexes (C5Me5)2U(CCR)2 (9) (R ¼ Ph, TMS) but in contrast to the thorium species, these bisacetylide complexes are extremely stable and the bisamido complex 12 can be formed only by adding large excess of the amine, indicating that the

2914

Homogeneous and heterogeneous catalytic processes

Scheme 26.1 Stoichiometric reactions of the complex (C5Me5)2ThMe2 with amines and terminal alkynes.

equilibrium between complexes 9 and 12 lies preferentially towards the bisacetylide complexes, instead of either the monoamido monoacetylide 11 or the bisamido complexes 12. Attempts to isolate the monomethyl–amido complex 10, by reacting one equivalent of amine with complex 8, yielded only half of an equivalent of the bisamido complex 12. Similar to the reactivity of the thorium complex, in the presence of an excess of amine, complex 12 was found to be in fast equilibrium with complex 13, with the equilibrium favoring the bisamido complex. By heating the bisamido complex 12 in THF, elimination of an amine molecule was observed allowing the formation of the corresponding uranium–imido complex 14 (Eisen et al., 1998). The U(IV) arene–imido complexes have also been prepared following a parallel pathway through a potassium salt [equation (26.2)] (Arney and Burns, 1995).

Reactivity of organoactinide complexes

2915

Scheme 26.2 Stoichiometric reactions of the complex (C5Me5)2UMe2 with amines and terminal alkynes.

2916

Homogeneous and heterogeneous catalytic processes

The only base‐free monomeric organo‐imido complex of U(IV) has been obtained for the bulky tris‐tert‐butyl phenyl amine derivative [equation (26.3)] [32].

The crystal structure of this coordinatively unsaturated organoimido uranium (IV) complex (16) exhibits almost a linear U–N‐ipso‐C linkage with and almost C2 symmetry along the U–N bond. The U–N‐ipso‐C angle is 162.30(10), with the aryl substituent canted towards the uranium through the methyl group in the ortho‐ position of the aromatic ring. Interestingly, besides this close disposition, no chemical evidence was found regarding any agostic interactions. The remarkable feature in this complex was found to be the extremely short ˚ resembling the distance of aryl–imido comU–N bond length of 1.952(12) A plexes of U(V) and U(VI) (Brennan and Andersen, 1985; Burns et al., 1990; Arney and Burns, 1993) when the differences in ionic radii due to the variation in the U oxidation states were taken into account (Shannon, 1976). Thus, it was suggested that in this aryl–imido uranium (IV) complex 16, there is a high formal bond order presumably formed by donation of a lone pair of electrons from the nitrogen to the uranium center. 26.2.3

Stoichiometric reactions between (C5Me5)2AnMe2 (An ¼ Th, U), alkynes and silanes

In order to detect the key organometallic intermediates in the hydrosilylation process (vide infra), a consecutive series of stoichiometric reactions were investigated, using the organoactinide precursor (C5Me5)2AnMe2 (An ¼ Th, U), reacting with iPrCCH and PhSiH3. The stoichiometric reaction of PhSiH3 with (C5Me5)2UMe2 induced the dehydrogenative coupling of the silane (PhSiH3) to give oligomers, but the reaction PhSiH3 with (C5Me5)2ThMe2 produced only the dimer and the corresponding [(C5Me5)2ThH(m‐H)]2, as described in the literature (Fagan et al., 1981b; Aitken et al., 1989). The reaction of the organoactinide complexes (C5Me5)2AnMe2 (An ¼ Th, U) with alkynes in stoichiometric amounts allowed the preparation and characterization of monoacetylide and bisacetylide complexes of organoactinides as described in Scheme 26.3.

Reactivity of organoactinide complexes

2917

Scheme 26.3 Stoichiometric reactivity of the organoactinide complexes (C5Me5)2AnMe2 (An ¼ Th, U ) with terminal alkynes.

In stoichiometric reactions of iPrCCH with (C5Me5)2UMe2, methane gas was evolved leading to the formation of the orange (mono)acetylide methyl complex, (C5Me5)2U(CCPri)(Me) (17). This transient species was found to be very reactive, and the addition of a second equivalent of iPrCCH converted complex 17 rapidly into the deep red brown bisacetylide complex (C5Me5)2U (CCPri)2 (9). Addition of one equivalent of PhSiH3 at room temperature to a benzene solution of any of the bisacetylide organoactinide complexes resulted in the quantitative formation of the silylalkenyl acetylide actinide complexes (C5Me5)2An(PhSiH2C¼CHiPr)(CCiPr) (An ¼ Th (18), U (19)), which were found to be intermediates in the catalytic cycle for the hydrosilylation reactions [equation (26.4)].

Formation of the intermediate was indicated by the change in color of the reaction from pale yellow to dark red for 18, and orange to dark orange brown for complex 19. The structure of 18 and 19 were unambiguously confirmed by 1H‐, 13C‐, 29Si‐NMR spectroscopy as well as by nuclear overhauser effect (NOE) experiments. The silyl group was found to be in the cis‐configuration with respect to the iso‐propyl group in the organometallic

Homogeneous and heterogeneous catalytic processes

2918

complex. Corroboration of this stereochemistry of the organometallic intermediate 18 was found by the quenching of 18 with H2O producing the corresponding cis‐vinylsilane product 20 [equation (26.5)].

Intriguingly, no further reaction was observed with an excess of PhSiH3 with complexes 18 or 19, strongly suggesting that at room temperature, neither the silane nor the alkyne is able to induce the s‐bond metathesis or the protonolysis of the hydrosilylated alkene or the alkyne. The addition of an excess of alkyne at room temperature to complex 18 in the presence of PhSiH3 yielded the unexpected trans‐hydrosilylated alkyne, in addition to the corresponding alkene, silylalkyne, and the bis(acetylide) complex. 26.2.4

Synthesis of ansa‐organoactinide complexes of the type Me2Si (C5Me4)2AnR2

Stoichiometric and catalytic properties of organo‐f‐element complexes are profoundly influenced by the nature of the p ancillary ligands (Bursten and Strittmatter, 1991; Edelmann, 1995a,b; Anwander, 1996; Anwander and Herrmann, 1996; Edelmann, 1996; Molander, 1998). It has proven possible to generate a more open coordination sphere at the metal center by introducing a bridge metallocene ligation set as in the complex ansa-Me2 SiCp002 MR2 (Cp00 ¼ C5Me4) (Fendrick et al., 1984; Jeske et al., 1985a,b; Fendrick et al., 1988). The effect of opening the coordination sphere of organolanthanides in some catalytic processes resulted in an increase (10‐fold to 100‐fold) in rates for the olefin insertion into the M–R bond (Jeske et al., 1985a,b; Gagne´ and Marks, 1989; Giardello et al., 1994). In organoactinides, this modification was shown to cause an increase (103‐fold) in their catalytic activity for the hydrogenation of 1‐hexene (Fendrick et al., 1984). The syntheses of the complexes Me2Si(C5Me4)2ThCl2 (21) and Me2Si(C5Me4)2ThnBu (22) have been reported as presented in equation (26.6) (Gagne´ and Marks, 1989; Dash et al., 2001). The complex Me2Si(C5Me4)2ThCl2 was isolated in 82% yield as a lithium chloride adduct. The single‐crystal X‐ray diffraction revealed a typical bent metallocene complex. The ring–centroid–Th–centroid angle (113.3 ) is smaller than that observed in unbridged bis(pentamethylcyclopentadienyl) thorium complexes (130–138 ) (Bruno et al., 1986), and slightly smaller than the angle determined for the bridged thorium dialkyl complex Me2Si(C5Me4)2Th

Reactivity of organoactinide complexes

2919

(CH2Si(CH3)3)2 (118.4 ) (Fendrick et al., 1984). The thorium–carbon (carbon ¼ cyclopentadienyl ring carbons) bond lengths are not equidistant; the complex displays a shorter distance between the metal and the first carbon adjacent to the silicon bridge because of the strain generated by the Me2Si‐bridge, similar to that reported for other ansa types of complexes (Bajgur et al., 1985).

The X‐ray analysis of complex 21 showed that two of the thorium–chloride ˚ , Th(1) – Cl(2) ¼ bonds are shorter than the other two Th(1) – Cl(1) ¼ 2.770(2)A ˚ ˚ ˚ . The 2.661(2)A, Th(1) – Cl(3) ¼ 2.950(2)A, and Th(1) – Cl(4) ¼ 2.918(2)A longer Th–Cl distances are those corresponding to the chlorine atoms disposed in the three‐fold bridging positions and coordinated to both lithium atoms. Each of the other two chlorine atoms is coordinated only to one lithium atom. All the Th–Cl distances are longer than those observed for terminal ˚ for Cp ThCl2 or 2.65A ˚ for Cp ThðClÞMeÞ. Th–Cl distances (Th–Cl ¼ 2.601A 2 2 ansa‐Chelating bis(cyclopentadienyl) complexes of uranium have been prepared as presented in Scheme 26.4. Schnabel et al. (1999) have described an effective high yield procedure for these desired U(IV) complexes (Schnabel et al., 1999). The uranium complexes (23–25) were obtained as dark‐red air‐ and moisture‐sensitive materials. The complexes are soluble in aromatic solvents but insoluble in hexane. In solution, these complexes have shown no dynamic behavior. The molecular structure of complex 23 reveals a normal bent metallocene with an angle of 114.1 for the ring centroid–metal–ring centroid. This angle is smaller as compared to the non‐bridged uranium complexes (133–138 ) (Fagan et al., 1981b; Eigenbrot and Raymond, 1982; Duttera et al., 1984; Cramer et al., 1989a,b). The uranium atom is bound to four bridging chloride ligands; two bonds are much longer than the others U–(Cl(1)) ¼ 2.885(3), U–(Cl ˚ , the longer U–Cl (2)) ¼ 2.853(3), U–(Cl(3)) ¼ 2.760(3), U–(Cl(4)) ¼ 2.746(3)A bonds are those associated with chlorides that bridge to one lithium atom. For the preparation of the dialkyl complexes, the corresponding chloride–TMEDA complex 24 was used as a precursor. The alkylation of the halide precursors with Grignard reagents produced the corresponding alkyl complexes using a large excess of dioxane as the precipitating solvent for the magnesium salts.

2920

Homogeneous and heterogeneous catalytic processes

Scheme 26.4 Synthetic pathway for the preparation of ansa‐organouranium complexes.

Interestingly, complex 28 is very stable in comparison to the corresponding dimethyl thorium complex (Fendrick et al., 1984). The dimethyl complex of the mixed cyclopentadienyl precursor 25 could not be isolated. Instead, the precipitation of insoluble material and the evolution of gas were observed. In contrast, the dibenzyl complexes 27 and 28 were obtained in high yields. The mixed benzyl–chloride complex was obtained by protonation of the dibenzyl complex 27 with [HNMe3]Cl as described in equation (26.7).

26.2.5

Synthesis of high‐valent organouranium complexes

The reactivity of organoactinide (IV) alkyl, amido, or imido complexes towards unsaturated organic substrates such as olefin, alkynes, and nitriles follows a four‐center transition state as described in equation (26.1). These complexes

Reactivity of organoactinide complexes

2921

display this type of reactivity due to the high‐energy orbital impediment to oxidative addition and reductive elemination. Consequently, the synthesis, characterization, and reactivity studies of high‐valent organouranium complexes are of primary importance. The ability to transform U(IV) to U(VI) and vice versa can create complementary modes of activation inducing unique and novel reactivities. The first high‐valent organouranium(VI) bis(imido) complex 29 was prepared by Arney et al. (1992) by the oxidation of a lithium salt of an organoimido uranium chloride complex with phenylazide [equation (26.8)] (Arney et al., 1992).

Other bis(imido) organouranium (VI) complexes have been prepared as described in Scheme 26.5. The reactions involve the oxidation of uranium (IV)

Scheme 26.5 Alternative synthetic pathways for the preparation of high‐valent organouranium–imido complexes and their reactivity with dihydrogen.

2922

Homogeneous and heterogeneous catalytic processes

bis(alkyl) or uranium (IV) imido complexes with the two‐electron atom transfer reagents in high yield (Brennan and Andersen, 1985). A very elegant and simple procedure for the generation of high‐valent bis (imido) organouranium (VI) complexes has been described starting from an organometallic uranium (III) species. The reaction involves the direct reduction of diazenes or azides [equation (26.9)] (Warner et al., 1998). Complex 30 was found to react at elevated temperature activating one methyl of the cyclopentadienyl ring (Peters et al., 1999a) [equation (26.10)].

26.2.6

Reactivity of the cationic complex [(Et2N)3U][BPh4] with primary amines

As will be presented in the course of this chapter, a large amount of work has been dedicated towards catalytic reactions using the cationic complex [(Et2N)3U][BPh4] (Berthet et al., 1995). In order to tailor the possibilities of such cationic complexes, stoichiometric reactions with amines have been studied. Under mild conditions (room temperature in benzene), the amido ligands of [(Et2N)3U][BPh4] were straightforwardly activated. The reaction of [(Et2N)3U][BPh4] with n‐propylamine yielded an organoactinide intermediate that upon consecutive quenching reaction with water, after all volatiles were removed, yielded n‐propylamine with no traces of Et2NH. This result indicated that all three amido groups were easily transaminated [equation (26.11)] (Wang et al., 2000). NMR spectroscopy has indicated that complexes

Oligomerization of alkynes

2923

of the type [(R2N)3U][BPh4] normally adopts a zwitterionic structure in non‐ coordinating solvents, with two phenyl groups of BPh4 coordinated to the metal center (Wang et al., 2002a).

Similarly reaction of [(Et2N)3U][BPh4] with tbutylamine allowed the formation of the complex [(tBuNH2)3(tBuNH)3U][BPh4] (33) [equation (26.12)]. The X‐ray diffraction analysis of 33 revealed a uranium atom in a slightly distorted octahedral environment, with the three amido and three amine ligands ˚ arranged in a mer geometry. The U–N(amido) bond lengths average 2.20(2)A and were similar to those determined in the distorted facial octahedral cation ˚ ) (Wang et al., 2002a). The complex [(Et2N)3(THF)3U]þ (mean value of 2.18(1)A [(tBuNH2)3(tBuNH)3U][BPh4] is a unique uranium(IV) complex with primary amine ligands that have been crystallographically characterized (Wang et al., ˚ can be compared 2002a). The mean U–N(amino) bond distance of 2.67(3)A ˚ in [UCl4(Me2NCH2CH2NMe2)2 with the average U–N bond length of 2.79(2)A ˚) (Zalkin et al., 1986). The shorter U–N(amido) bond length (U–N ¼ 2.185(7) A ˚ ) were found to be and the longer U–N(amine) bond length (U–N ¼ 2.705(8) A those which are in trans positions. The small octahedral distortion was manifested in the different angles between the amine–amido, amine—amine, and amido–amido groups. 26.3 OLIGOMERIZATION OF ALKYNES

The last decade has witnessed an intense investigation of the chemistry of electrophilic d0/f lanthanide and actinide metallocenes (Edelmann, 1995a,b). A substantial impact was encountered in diverse catalytic areas, where the key step is an insertion of an olefinic (alkene or alkyne) functionality into a metal– alkyl, metal—hydride, or metal–heteroatom moiety [equation 26.13; Cp* ¼ Z5‐ C5Me5; X ¼ alkyl, H, NR2).

2924

Homogeneous and heterogeneous catalytic processes

For organolanthanides, such processes include hydrogenation (Molander and Hoberg, 1992; Giardello et al., 1994; Haar et al., 1996; Molander and Winterfeld, 1996; Roesky et al., 1997a,b), dimerization (Heeres et al., 1990), oligomerization/polymerization (Jeske et al., 1985c; Watson and Parshall, 1985; Heeres and Teuben, 1991; Schaverien, 1994; Fu and Marks, 1995; Ihara et al., 1996; Mitchell et al., 1996), and other related reactions that will be discussed later in this chapter, whereas for organoactinides, until 1991 C–H activation (Smith et al., 1986a; Fendrick et al., 1988) and hydrogenation (Fagan et al., 1981a,b; Fendrick et al., 1988; Lin and Marks, 1990) comprised all such processes. Mechanistically, these insertion reactions are not in general well understood and are certainly more efficient in very different metal–ligand environments than the more extensive studied analogs of the middle‐ and late‐ transition metals (Collman et al., 1987; Elschenbroich and Salzer, 1989; Hegedus, 1995). Hence, the d0/f metal ions are likely to be in a high formal oxidation state, and in neutral complexes are expected to be electronically unsuitable for p‐back‐donation. In addition, these types of complexes are unlikely to form stable olefin/alkyne complexes, due to the relatively polar metal–ligand bonding with strong affinity for ‘hard’ ligands, and to feature startling M–C/M–H bond disruption enthalpy patterns as compared with those of the late transition elements (Marthino Simo˜es and Beauchamp, 1990; Nolan et al., 1990; King and Marks, 1995). 26.3.1

Bisacetylide organoactinide complexes

Organometallic complexes containing an acetylide moiety have played an important role in the development of organolanthanide chemistry (Evans et al., 1983, 1989; Den Haan et al., 1987; Shen et al., 1990). A number of synthetic routes applicable to the preparation of this class of compounds have been developed, examples of which include the salt metatheses between lanthanide halides with main group acetylides, and the s‐bond metatheses between lanthanide alkyl or hydrides and terminal alkynes. Bisacetylide organoactinide complexes can be synthesized at room temperature by the reaction of (C5Me5)2AnMe2 (An ¼ Th, U) with either stoichiometric or excess amounts of the corresponding terminal alkynes (Schemes 26.1 and 26.2). The reaction is faster for the organoactinide uranium complex than for the corresponding thorium complex. In all cases, the bisacteylide complexes

Oligomerization of alkynes

2925

were obtained instead of the uranium methyl acetylide complex (34) [equation (26.14)], indicating that the metathesis substitution of the second methyl ligand by the terminal alkyne is normally much faster than the first s‐bond metathesis.

An ¼ Th; R ¼ TMS; i Pr; An ¼ U; R ¼ Ph; t Bu; i Pr Due to the paramagnetism of the 5f2 uranium (IV) center and its rapid electron spin–lattice relaxation times, the chemical shifts of the magnetically non‐ equivalent ligand protons were found to be generally sharp, well‐separated, and readily resolved in the 1H‐NMR spectra. 26.3.2 Oligomerization of terminal alkynes catalyzed by neutral organoactinide complexes of the type (C5Me5)2AnMe2 The reaction of (C5Me5)2AnMe2 (An ¼ Th, U) with an excess of tert‐butylacetylene yielded the regioselective catalytic formation of the head‐to‐tail dimer, 2,4‐di‐tert‐butyl‐1‐butene‐3‐yne (Th ¼ 99%; U ¼ 95%), whereas with trimethylsilylacetylene the head‐to‐tail geminal dimer, 2,4‐bis(trimethylslyl)‐1‐butene‐3‐yne (Th ¼ 10%; U ¼5%), and the head‐to‐tail‐to‐head trimer, (E,E)‐1,4,6‐tris(trimethylsilyl)‐1‐3‐hexadiene‐5‐yne (Th ¼ 90%; U ¼ 95%), were the exclusive products [equation (26.15)] (Straub et al., 1995):

For other terminal alkynes such as HCCPh, HCCPri, HCCC5H9, the (C5Me5)2AnMe2 complexes also produced mixtures of the head‐to‐head and

2926

Homogeneous and heterogeneous catalytic processes

head‐to‐tail dimers and the formation of higher oligomers with no specific regio‐ selectivity and chemo‐selectivity. For the bulky 4‐Me‐PhCCH, a different reactivity was found for the different organoactinide complexes. Whereas (C5Me5)2ThMe2 generated a mixture of dimers and trimers, the corresponding (C5Me5)2UMe2 afforded only the head‐to‐head trans‐dimer. In contrast to the reactivity of lanthanide complexes, the organoactinides did not induce the formation of allenic compounds. Although the turnover frequencies for both of the organoactinide complexes were in the range of the 1–10 h–1, the turnover numbers were found to be higher, in the range of 200–400. 26.3.3

Key intermediate complex in the oligomerization of terminal alkynes promoted by neutral (C5Me5)2AnMe2 organoactinides

When the reaction of TMSCCH with (C5Me5)2ThMe2 was followed spectroscopically, two different compounds were observed. The first compound observed at room temperature was the bisacetylide complex. The oligomerization reaction started only upon heating the reaction mixture to 70 C, whereupon the bisacetylide complex disappeared and the new complex 35 (Fig. 26.1) was spectroscopically characterized, indicating that both acetylide positions at the metal center were active sites. 26.3.4 Kinetic, thermodynamic, and thermochemical data in the oligomerization of terminal alkynes promoted by neutral (C5Me5)2AnMe2 organoactinides A kinetic study of the trimerization of TMSCCH with Cp 2 UMe2 was monitored in situ by 1H‐NMR spectroscopy. From the kinetic data, the empirical rate law for the organoactinide‐catalyzed oligomerization of TMSCCH is given by equation (26.16). The derived rate constant at 70 C for the production

Fig. 26.1 Bis(dienyne) organoactinide complex 35 found in the linear oligomerization of terminal alkynes.

Oligomerization of alkynes

2927

of the corresponding trimer was found to be k ¼ 7.6 10–4 (6) s–1. n ¼ k½alkyne1 ½U1

ð26:16Þ

A similar kinetic dependence on alkyne and catalyst concentration was observed over a range of temperatures permitting the derivation of the activation parameters from the corresponding Eyring analysis. The values measured were Ea ¼ 11.8(3) kcal mol–1, DH{ ¼ 11.1(3) kcal mol—1, and DS{ ¼ – 45.2(6) eu, respectively (Straub et al., 1999). Thermodynamically, higher oligomers and even polymers were expected (Ohff et al., 1996; Wang and Eisen, 2003). The reaction of either the Th or U organoactinide complex with acetylene (HCCH) resulted in the precipitation of black cis‐polyacetylene. The cis‐polyacetylene was thermally converted to the corresponding trans‐polyacetylenes at 80 C. The enthalpies of reaction may be calculated for the addition of triple bonds in a conjugated manner (Scheme 26.6), The DHcalc for the dimer formation is exothermic by 27 kcal mol–1, whereas additional insertions are calculated to be exothermic by an additional 20 kcal mol–1. Thus, DHcalc for the trimer formation is exothermic by 47 kcal mol–1, supporting the results in which non‐bulky terminal alkynes were oligomerized with no chemoselectivity. A plausible pathway was proposed for the organoactinide‐oligomerization of terminal alkynes, presented in Scheme 26.7. The mechanism is a sequence of well‐established reactions such as insertion of an alkyne into a M–C s‐bond and

Scheme 26.6 Calculated enthalpies of reaction for the oligomerization of terminal alkynes.

2928

Homogeneous and heterogeneous catalytic processes

Scheme 26.7 Proposed mechanism for the linear oligomerization of terminal alkynes catalyzed by organoactinide bisacetylide complexes.

s‐bond metathesis. The first step in the catalytic cycle involves the protonation of the alkyl groups in the organoactinide precatalyst at room temperature, yielding the bisacetylide complexes (C5Me5)2An(CCR)2 (A), with the concomitant elimination of methane (step 1). In general, this is a very rapid reaction extremely exothermic as calculated for the reaction of the organoactinides with PHCCH [equation (26.17)] The 1,2‐head‐to‐tail‐insertion of the alkyne into the actinide–carbon s‐bond was proposed to yield the plausible bisalkenyl actinide complex B (step 2). Complex B may undergo either a s‐bond metathesis with the C–H bond of another alkyne producing the corresponding geminal dimer and A (step 5), or an additional 2,1‐tail‐to‐head‐insertion of an alkyne, with the expected regioselectivity (for TMSCCH), into the organoactinide alkenyl complex B, yielding the bis(dienyl)organoactinide complex C (step 3). The reaction of complex C with an incoming alkyne was proposed to yield the corresponding trimer and regenerating the active actinide bisacetylide complex A (step 4). The turnover‐ limiting step for the catalytic trimerization was identified to be the elimination of the organic trimer from the organometallic complex C. This result indicated that the rate for s‐bond metathesis between the actinide–carbyl and the alkyne and the rate of insertion of the alkyne into the metal–acetylide (steps 1 and 2)

Oligomerization of alkynes

2929

were much faster than the rate for s‐bond metathesis of the alkyne with the metal–dialkenyl bond in the catalytic cycle (step 4).

26.3.5

Cross oligomerization of tBuCCH and TMSCCH promoted by (C5Me5)2UMe2

In the oligomerization of tBuCCH with (C5Me5)2UMe2, the geminal dimer was found to be the major product, indicating that the addition of the alkyne to the metal acetylide was regioselective with the bulky group pointing away from the cyclopentadienyl groups (Fig. 26.2). The reaction of equimolar amounts of tBuCCH and TMSCCH with (C5Me5)2UMe2 produced two dimers (14%) and three specific trimers (86%). The dimers generated in the reaction were characterized to be the geminal dimer 36 (10%) and the cross geminal dimer 37 (4%), resulting from the insertion of a tBuCCH with the same regioselectivity as observed in Fig. 26.2 into the uranium bis(trimethylsilylacetylide) complex. The trimers obtained were the head‐to‐tail‐to‐head trimer, (E,E)‐1,4,6‐tris(trimethylsilyl)‐ 1‐3‐hexadiene‐5‐yne (38), as the major product (43%), the trimer 39 (15%), resulting from the insertions of two TMSCCH into the tert‐butylacetylide complex, and the unexpected trimer 40 (27%) [equation (26.18)]. Trimer 40 was

Fig. 26.2 Regioselectivity of the insertion of tBuCCH into an organoactinide acetylide bond.

2930

Homogeneous and heterogeneous catalytic processes

formed by the consecutive insertion of tBuCCH after the TMSCCH insertion. These results indicated that in the formation of trimers, the last insertion rate must be fast and competitive for both alkynes, and that the metathesis of the free alkyne is the rate‐determining step.

26.4 DIMERIZATION OF TERMINAL ALKYNES

Due to the different reactivities displayed in the selective dimerization of terminal alkynes by different neutral and cationic organo‐5f‐complexes, this topic will be divided based on the nature of the catalytic species. 26.4.1 Dimerization of terminal alkynes promoted by neutral (C5Me5)2AnMe2 complexes in the presence of amines An interesting rationale has been presented in connection with the proposed mechanism, suggesting the means to permit the formation of a specific dimer while limiting the formation of higher oligomers. This would, in effect block steps 3 and 4 in Scheme 26.7 and restrict the reaction to follow steps 2 and 5. Haskel et al. (1999) have reported a principle for the selective control over the extent of the oligomerization of terminal alkynes by using an acidic chain‐ transfer agent. The basic approach employs a chain transfer reagent not ending up in the product and not involving subsequent elimination from the product to release the unsaturated oligomer (in contrast to e.g. ethene oligomerization by metallocene catalysts or magnesium reagents) (Samsel, 1993; Pelletier et al., 1996). The dimerization was performed in the presence of an amine (primary or

Dimerization of terminal alkynes

2931

secondary); this resulted in minimal alteration of the turnover frequencies compared with the non‐controlled process. The selectivity control (i.e. the amount of the different oligomers obtained by the different complexes (Th, U)) of the new catalytic cycle is explained by considering the difference in the calculated bond‐disruption energies between an actinide–alkenyl‐ and an actinide–amido‐bond, and combining non‐selective catalytic pathways with individual stoichiometric reactions. Organoactinide complexes of the type (C5Me5)2AnMe2 (An ¼ Th, U) reacted with terminal alkynes in the presence of primary amines yielding preferentially alkyne dimers [equation (26.19)] and for certain alkynes small amounts of regioselective trimers [equation (26.20)]. This selectivity was opposite to that found in the oligomerization of alkynes under the same conditions in the absence of amines. In general, the initial reaction of (C5Me5)2AnMe2 (An ¼ Th, U) with an alkyne yielded the bisacetylide complex, though in the presence of amines, for the thorium complex, the corresponding (C5Me5)2Th(NHR)2 (5) was formed. For the uranium complex, no bisamido complex is observed unless large excess of the amine was used.

When comparing the oligomerization of terminal alkynes promoted by the thorium complex in the presence of amines as to the results obtained without amines, a dramatic reduction in the extent of oligomerization was observed. When EtNH2 or other primary amines were used with aliphatic alkynes, mixtures of the corresponding geminal and trans dimer were produced, while for aromatic alkynes, just the trans dimer was formed. Increasing the bulkiness of the primary amine for aliphatic alkynes allowed only the formation of the geminal dimer, and the specific trimer as represented in equation (26.20). These results indicated that the insertion of the second alkyne into the metalla–eneyne D complex and the trimer elimination [equation (26.20)] are faster than either the insertion of an alkyne into the intermediate complex E,

2932

Homogeneous and heterogeneous catalytic processes

and/or the protonolysis of E by either the alkyne or the amine, eliminating the corresponding isomeric trimer and/or dimer, respectively [equation (26.21)]. Reactions of the thorium precursor with secondary amines allowed the formation of higher oligomers (up to pentamers), however in lower yields, as compared with the results obtained in the reactions in the absence of amines. It was proposed that for secondary amines, the protonolysis of the growing oligomer from the metal was much slower as compared to the insertion of the alkynes and cutting the oligomer chain by the alkyne itself.

For uranium, the oligomerization of non‐bulky alkynes with secondary amines showed no control whereas for primary amines (R0 NH2), the intermolecular hydroamination product obtained was exclusively (RCH2CHN¼R0 ) (Haskel et al., 1996). While the dimerization of tBuCCH produced the geminal dimer, in the presence of tBuNH2, a mixture of both dimers were obtained, which suggested the attachment of the amine to the metal center at the time of the alkyne insertion allowing different regioselectivities. Previously, for the non‐ controlled oligomerization reactions, the actinide–bisacetylide complex was proposed as the active species in the catalytic cycle. In the controlled oligomerization reaction, the formation of the organoactinide bisamido complex, which was the predominant species, provided strong evidence that the amine was the major protonolytic agent. A novel strategy was implemented in support of the protonolytic theory to increase the selectivity towards the trimeric isomer. Enhanced selectivity was attained by providing a kinetic delay for the fast protonolysis using deuterated amine. The kinetic effect allowed more trimer formation, in a reaction producing both dimer and trimer [equation (26.22)]. The strategy biased the chemoselectivity of the oligomerization increasing the trimer:dimer ratio.

Dimerization of terminal alkynes

2933

When the product formation was followed as a function of time, the first deuterium was observed at the geminal position, but at higher conversions, more olefinic positions were deuterated, suggesting that the alkyne and the deuterated amine were in equilibrium through a metal complex only exchanging hydrogen/deuterium atoms.

(a) Kinetic, thermodynamic, and mechanistic studies of the controlled oligomerization of terminal alkynes Kinetic measurements of the controlled oligomerization reaction of nBuCCH with iBuNH2 promoted by (C5Me5)2ThMe2 revealed a first‐order dependence of the catalytic rate on substrate concentration, an inverse first‐order in amine and first‐order dependence in precatalyst. Thus, the rate law for the controlled oligomerization of terminal alkynes promoted by organoactinides can be written as presented in equation (26.23). n ¼ k ½Th1 ½alkyne1 ½amine
1 {

{

ð26:23Þ

The derived DH and DS values from an Eyring analysis were measured to be 15.1(3) kcal mol–1 and –41.2(6) eu, respectively. An inverse proportionality in catalytic systems is consistent with a rapid equilibrium before the rate‐limiting step. For this reaction, it was consistent with the equilibrium between the bisamido complex and a bisamido–amine complex, as found in the hydroamination of terminal alkynes promoted by early transition complexes (Walsh et al., 1992; Baranger et al., 1993) and in the hydroamination of olefins promoted by organolanthanide complexes (Gagne´ et al., 1992a,b; Molander and Hoberg, 1992). A reasonable mechanism for the controlled oligomerization of terminal alkynes is described in Scheme 26.8. The mechanism presented in Scheme 26.8 consists of a sequence of simple reactions, such as insertion of acetylene into an M–C s‐bond, and s‐bond metathesis. The starting complex (C5Me5)2ThMe2 reacts fast with amines to the bisamido complex G and the bisamido–amine complex F. These complexes were found to be in rapid equilibrium and responsible for the inverse proportionality in the kinetic dependence of the amine (Straub et al., 1996). Complex G, which was found to be the resting state for the catalytic species, reacted with one equivalent of alkyne in the rate‐limiting step, producing complex H (step 1). Comparison of the results obtained for the oligomerization of phenylacetylene in the absence of amines (with amines only a dimer was obtained), in which both dimers and higher oligomers were obtained, indicated that an amido acetylide and not the bisacetylide complex was responsible for the regio‐differentiation. Complex H reacts with an alkyne, yielding the actinide–alkenyl amido complex I (step 2), which may undergo either a s‐bond protonolysis with the amine to yield the corresponding dimer and the bisamido complex G (step 3), or another

2934

Homogeneous and heterogeneous catalytic processes

Scheme 26.8 Plausible mechanism for the oligomerization of terminal alkynes, in the presence of amines, promoted by organothorium complexes.

insertion of an alkyne and concomitant s‐bond protonolysis by the amine, yielding the oligomeric trimer and the bisamido complex G. Thus the reaction rate law presented in equation (26.23) was compatible with rapid, irreversible alkyne insertion (step 2), rapid s‐bond protonolysis of the oligomer by the amine (step 3), a slow pre‐equilibration involving the bis‐amido G and the mono amido‐acetylide complex (H) (step 1), and a rapid equilibrium between the bisamido complex G and the bisamido–amine complex F. Control over the oligomerization was accomplished by a kinetic competition between the insertion reaction of a new alkyne molecule into the metal–alkenyl bond [equation (26.24)] and the protonolysis by the amine [equation (26.25)]. The insertion reaction produces a larger metalla–oligomer complex, whereas the competing protonolysis produces the organic product and the bisamido organometallic complex. The difference in selectivity found for the thorium and uranium complexes was corroborated using bond disruption energy data (Bruno et al., 1983; Smith et al., 1986b; Marthino Simo˜es and Beauchamp, 1990; Giardello et al., 1992). For thorium, both reactions [equations (26.24) and (26.25)] were calculated to be exothermic by almost equal amounts generating control over the extent of oligomerization. For the corresponding uranium complex, where no control over chain length was observed, the formation of the bisamido complex was calculated to be endothermic, limiting the control over the degree of oligomerization.

Dimerization of terminal alkynes

26.4.2

2935

Dimerization of terminal alkynes promoted by the ansa‐organothorium complex Me2Si(C5Me4)2ThBu2

The ansa‐bridged organoactinide complex Me2Si(C5Me4)2ThnBu2 was found to be an excellent precatalyst for the chemo‐ and regio‐selective dimerization of terminal alkynes. At room temperature, head‐to‐tail geminal dimers were obtained, whereas at higher temperature (78 C), the geminal dimer and some minor amounts of the specific head‐to‐tail‐to‐tail trimer (up to 5%) were also observed particularly for the specific alkynes iPrCCH and nBuCCH [equation (26.26)] (Dash et al., 2001). Although no large difference was observed among similar alkyne substituents, the dimerization reaction of either i PrCCH or nBuCCH with Me2Si(C5Me4)2ThnBu2 was much faster and more selective than the dimerization with Cp 2 ThMe2 . The most striking result regarding the dimerization/oligomerization of terminal alkynes was found for TMSCCH (TMS ¼ Me3Si). No catalytic reaction was observed by using the ansa‐bridged complex (butane was evolved), in contrast to the results obtained in the reaction of TMSCCH with Cp 2 ThMe2 , in which the geminal dimer (10%) and the head‐to‐tail‐to‐head trimer (90%) were obtained with high regioselectivity (Straub et al., 1995).

2936

Homogeneous and heterogeneous catalytic processes

A domino reaction was observed in the dimerization of the alkene‐ functionalized alkyne producing dimer 41, which undergoes a quantitative intermolecular Diels–Alder cyclization to produce compound 42 [equation (26.27)].

(a) Kinetic studies of the dimerization of terminal alkynes promoted by Me2Si(C5Me4)2ThnBu2 The kinetics for the dimerization of iPrCCH promoted by Me2Si (C5Me4)2ThnBu2 were studied. The reaction displayed a first‐order dependence in precatalyst, and two different kinetic domains were observed, with differing alkyne dependence (Fig. 26.3). At low concentrations of alkyne, an inverse proportionality was observed indicating that the reaction is in an inverse first‐ order, but at higher concentrations, the reaction exhibited a zero order in alkyne (Eisen et al., 1998). The change from an inverse rate to a zero rate was rationalized by invoking two equilibrium processes. In one of these equilibrium processes, the complex was removed from the catalytic cycle (inverse order), whereas the second equilibrium was found to be the rate‐determining step in the dimer formation. The latter was measured only at high alkyne concentrations. The derived activation parameters Ea, DH{, and DS{ from an Eyring analysis were 11.7(3) kcal mol–1, 11.0(3) kcal mol–1, and 22.6(5) eu, respectively. Given that the stereochemical approach of the alkyne to the organometallic moiety is likely side‐on, the highly regioselective production of the geminal dimers was rationalized by suggesting that the insertion of the alkyne occurs with the substituent away from the metal center. The methyl groups of the cyclopentadienyl spectator ligand also disfavor the disposition of the alkyne substituent facing the metal center.

Dimerization of terminal alkynes

2937

Fig. 26.3 Alkyne dependence in the dimerization of iPrCCH promoted by Me2Si (C5Me4)2ThnBu2.

A plausible mechanism for the selective dimerization of iPrCCH promoted by Me2Si(C5Me4)2ThnBu2 is presented in Scheme 26.9. The initial step in the catalytic cycle is the alkyne C–H activation by the complex Me2Si (C5Me4)2ThnBu2 and the formation of the bisacetylide complex J together with butane (step 1). Complex J is proposed to be in equilibrium with an alkyne, forming the proposed p‐alkyne acetylide complex K, which removes the active species from the catalytic cycle (inverse rate dependence). Alternatively, J undergoes a head‐to‐tail insertion with another alkyne into the thorium–carbon s‐bond, producing the substituted alkenyl complex L (step 2). Complex L goes through a s‐bond protonolysis with an additional alkyne (step 3), yielding the corresponding dimer and regenerating the active acetylide complex J. In contrast to the general expectations for organoactinides, complex K was the first p‐olefin intermediate complex (vide infra) exhibiting new rich and versatile reactivity for actinide complexes. The turnover‐limiting step for the catalytic dimerization was measured to be the insertion of the alkyne into the thorium–acetylide complex J (step 2). Thus, the derived rate law based on the mechanism proposed in Scheme 26.9 for the oligomerization of terminal alkynes promoted by the complex Me2 SiCp002 Thn Bu2 is given by equation (26.28), fitting the kinetic performances of the alkyne and catalysts.

2938

Homogeneous and heterogeneous catalytic processes

Scheme 26.9 Proposed mechanism for the dimerization of terminal alkynes promoted by Me2 SiCp002 Thn Bu2 .

n¼

k
1 k2 ½Cat 2 k
2 k1 þ k2
k3k½alkyne

ð26:28Þ

26.4.3 Catalytic dimerization of terminal alkynes promoted by the cationic actinide complex [(Et2N)3U][BPh4]. First f‐element alkyne p‐complex [(Et2N)2U(CCtBu)(h2‐HCCtBu)][BPh4] Unlike neutral organoactinide complexes, homogeneous cationic d0/f n actinide complexes have been used as catalysts for the polymerization of a‐olefins (Jia et al., 1997; Chen et al., 1998), as have their isolobal group 4 complexes. The alkyne oligomerization reaction has been mentioned as a useful probe for the insertion and s‐bond metathesis reactivity of organoactinide complexes. For the corresponding cationic actinide complexes, little was known regarding their reactivity with terminal alkynes (Wang et al., 1999). Reaction of the cationic complex [(Et2N)3U][BPh4] (Berthet et al., 1995) with the terminal alkynes RCCH, (R ¼ Me, nBu, iPr) resulted in the chemo‐ and regio‐selective catalytic formation of the head‐to‐tail gem‐dimers without the formation of the trans dimer or any other major oligomers [equation (26.29)]. For PhCCH, the

Dimerization of terminal alkynes

2939

reaction was less chemoselective, allowing the formation of some trimers (dimer:trimer ratio ¼ 32:58). For TMSCCH, besides the formation of the geminal head‐to‐tail dimer, the trans‐head‐to‐head dimer, and the regioselective head‐to‐tail‐to‐head‐trimer (E,E)‐1,4,6‐tris(trimethylsilyl)1‐3‐hexadien‐5‐yne, the unexpected head‐to‐head cis dimer was also formed [equation (26.30)]. For tBuCCH, besides the geminal dimer also the unexpected cis‐dimer was formed [equation (26.31)].

As already mentioned, mechanistically, the relatively polar metal–ligand bonds, the absence of energetically accessible metal oxidation states for oxidative addition/reductive elimination processes and the presence of relatively low‐lying empty s‐bonding orbitals, implicate a ‘four‐center’ heterolytic transition state in the metal–carbon bond cleavage (Marks and Day, 1985; Marks, 1986a,b). The reaction of the metal acetylide with a terminal alkyne occurs in a syn mode and the s‐bond protonolysis of the resulting alkenyl complex will be expected to maintain the cis‐stereochemistry at the product (Fig. 26.4). Hence, the formation of the trans dimers [equations (26.30) and (26.31)] argued for an isomerization pathway before the products were released from the metal center. For comparison, in the oligomerization of terminal alkynes promoted by the cationic complexes ½Cp 2 AnMe½BðC6 F5 Þ4  (An ¼ Th, U), the

2940

Homogeneous and heterogeneous catalytic processes

Fig. 26.4 Modes of activation of an actinide–acetylide complex with an alkyne through a syn four‐centered transition state pathway towards the formation of the intermediates I or/and II.

geminal dimer was chemoselectively formed with no trace formation of either cis or trans dimers (Haskel et al., 1999). Mechanistically, in the reaction of [(Et2N)3U][BPh4] with terminal alkynes, one equivalent of the Et2NH amine was released in solution, forming the bisamido acetylide cationic complex [(Et2N)2U–CCR][BPh4]. This reaction was shown to be a slow equilibrium, and the addition of different equimolar amounts of external Et2NH to the reaction mixture led to a linear lowering of the reaction rate (Fig. 26.5). Considering that in the reactions with alkynes, the amount of the released free amine was stoichiometric, it was deduced that the free terminal alkyne was also the major protonolytic agent. The confirmation of this protonolytic hypothesis was obtained by generating a kinetic delay for the presumed fast protonolysis by the alkyne to allow trimer formation, through replacement of the terminal hydrogen with deuterium [equation (26.32)]. By using that strategy, the chemoselectivity of the oligomerization was altered allowing formation of the deuterated geminal dimer, and some trimer (Dash et al., 2000).

The kinetics of the dimerization reaction of nBuCCH was studied, indicating that the reaction behaved with a first‐order dependence in precatalyst, and as

Dimerization of terminal alkynes

2941

Fig. 26.5 Following the dimer formation as a function of time in the reaction of iPrCCH catalyzed by [(Et2N)2U–CCR][BPh4]. Absence of external amine (●), presence of one equivalent of external Et2NH (▪).

a function of alkyne, the kinetic plots showed two domains (Fig. 26.6). At low alkyne concentrations, an inverse proportionality was observed, indicating that the reaction was inverse first‐order, and at higher concentrations, the reaction exhibits a zero‐order in alkyne, similar to the behavior displayed in Fig. 26.3. The activation parameters derived for the dimerization of nBuCCH were characterized by a small enthalpy of activation (DH{ ¼ 15.6(3) kcal mol–1) and a negative entropy of activation (DS{ ¼ –11.4(6) eu). The proposed mechanism for the dimerization of nBuCCH is presented in Scheme 26.10. The initial step in the catalytic cycle is the alkyne C–H activation by the cationic uranium amide complex and the formation of the bisamido carbyl complex [(Et2N)2U‐CCnBu] [BPh4] (M) together with Et2NH. Complex M can be in equilibrium with an alkyne forming the p‐alkyne acetylide uranium complex N, which drives the active species out of the catalytic cycle (inverse rate dependence), or undergoes with an alkyne a head‐to‐tail insertion into the uranium–carbon s‐bond, yielding the substituted uranium alkenyl complex O. Complex O may undergo a s‐bond metathesis with an additional alkyne, leading to the corresponding dimer and regenerating the active carbyl complex M. Complex N (for R ¼ tBu) was trapped and its structure spectroscopically determined. The 1H‐ and 13C‐NMR spectra of complex N showed sharp lines as found for other actinide‐IV type of complexes. The 1H‐NMR spectrum exhibited the acetylide signal (C–H) at d ¼ –2.14 which correlated in the distortionless enhancement by polarization transfer (DEPT) and in the 2D C–H correlation NMR experiments to the carbon having the signal at d ¼ –19.85

2942

Homogeneous and heterogeneous catalytic processes

Fig. 26.6 Alkyne dependence in the dimerization of nBuCCH promoted by [(Et2N)3U] [BPh4].

Scheme 26.10 Proposed mechanism for the dimerization of terminal alkynes promoted by [(Et2N)3U][BPh4].

ppm, with a coupling constant of 1J ¼ 250 Hz. A confirmation of the formation of an alkyne Z2‐complex, as compared to an acetylide complex or to a free alkyne was also obtained by FT‐IR spectroscopy. The CC stretching of the free alkyne (2108 cm–1) disappeared, giving rise to two signals at lower

Dimerization of terminal alkynes

2943

frequencies, as expected for Z2‐transition metal complexes, one at 2032 cm–1 similar to acetylide lanthanides, and the second one at 2059 cm–1. The turnover‐ limiting step for the catalytic dimerization was found to be the insertion of the alkyne into the uranium–carbyl complex M. The proposed mechanism also agreed with the formation of trimer oligomers, which are only expected if a kinetic delay in the protonolysis was operative [equation (26.32)]. For sterically demanding alkyne substituents (TMS, tBu), it was proposed that the rate of the protonolysis step is lower than that of the isomerization of the metalla–alkenyl complex 43, producing the unexpected cis‐dimer 45, probably through the metalla–cyclopropyl cation (44), via the ‘envelope isomerization’ [equation (26.33)] (Faller and Rosan, 1977). The preference for the cis‐ isomer was suggested to arise from an agostic b‐hydrogen interaction to the metal center (Wang et al., 1999; Dash et al., 2000).

(a) Effect of external amines in the dimerization of alkynes promoted by the cationic complex [(Et2N)3U][BPh4] Since the formation of the cationic complex M is an equilibrium reaction (Scheme 26.10), it was possible to tailor the regiochemistry of the dimerization by using external amines. The expectation was that the amine would be bonded to the cationic metal center, causing a kinetic delay, but also allowing unique regiochemistry. As presented above in the reaction of 1‐hexyne with a catalytic amount of the cationic complex [(Et2N)3U][BPh4] [equation (26.29)] the geminal dimer was chemoselectively obtained. However, when the reaction was carried out in a polar solvent like THF, the reaction was much slower, yielding besides the dimer a mixture of trimers [equation (26.34)]. The result was rationalized by the lower reactivity of the THF adduct [(Et2N)3(THF)3U]þ resulting in slower protonolysis of the corresponding alkenyl intermediate [(Et2N)2(THF)3U (C¼C(H)CCR)]þ (R ¼ nBu), and allowing further alkyne insertion with the formation of trimers, but with a total lack of regioselectivity.

2944

Homogeneous and heterogeneous catalytic processes

For 1‐hexyne, the addition of equimolar amounts of the external amine EtNH2 (alkyne:amine ¼ 1:1) to the reaction mixture impeded the occurrence of the dimerization process. The same behavior was found for propyne [equation (26.35)]. This lack of reactivity for these alkynes was proposed to be a consequence of either their inability to engage in the equilibrium reaction (Scheme 26.10), resulting in the formation of the acetylide complex M in the presence of external EtNH2, or the formation of an inactive p‐alkyne complex, similar to N in Scheme 26.10. When 1‐hexyne was reacted in the presence of an equimolar amount of the bulkier amine tBuNH2, the gem dimer and the unexpected cis dimer were obtained [equation (26.36)], indicating that the bulky amine probably allowed the formation of the acetylide intermediate [(tBuNH2)x(tBuNH)2U(CCnBu)]þ by the reaction of nBuCCH with the trisamido cation [(tBuNH2)3(tBuNH)3U]þ. This acetylide would then undergo insertion of an alkyne molecule to give the corresponding alkenyl species and dimerization products.

(b) Dimerization and hydroamination of iPrCCH and tBuCCH catalyzed by [(Et2N)3U][BPh4] in the presence of amines Unpredictably, the reactions of iPrCCH and tBuCCH followed a quite distinct course. These alkynes were found to be more reactive than 1‐hexyne or propyne in the presence of different amines. The nature of the diverse products were found to be strongly dependent on the size or steric encumbrance of the amine. The reaction of iPrCCH with [(Et2N)3U][BPh4] in the presence of EtNH2 or iPrNH2 afforded the cis dimer, trace amounts of the gem dimer, and depending on the amine, one or both of the two corresponding hydroamination products were generated. By using the bulkier amine tBuNH2 both dimers and only one hydroamination product were observed [equation (26.37)] (Wang et al., 2002a).

Dimerization of terminal alkynes

2945

The rather large effect of alkyne concentration on the distribution of the products was revealed by the relative proportions of the dimers (gem to cis), which vary from 40:24 in the reaction of tBuND2 with two equivalents of i PrCCH to 70:8 in the reaction of tBuNH2 with one equivalent of iPrCCH. The results agreed with a dimerization mechanism such as that in Scheme 26.11. The mechanism consists of the formation of complex Q by the reaction of the cationic complex P with the alkyne (step 1). The acetylide complex reacts with an additional alkyne, producing the mixture of alkenyl compounds R and S (step 2). Isomerization of complex R through an envelope mechanism [equation (26.33)] allowed the formation of complex T (step 3) that by protonolysis yielded the unexpected cis‐dimer (step 4). The addition of a large amount of alkyne in combination with a source of deuterium (as tBuND2) removed complex S from the catalytic cycle as the geminal product (step 5). This latter species was found partially deuterated since the alkyne served also as a protonolytic reagent. The rate‐determining step in the reaction was proposed to be the isomerization reaction (step 3). (c) Regioselective oligomerization of tBuCCH promoted by [(Et2N)3U] [BPh4] in the presence of amines Reaction of the bulkier alkyne tBuCCH with the cationic uranium complex [(Et2N)3U][BPh4] in the presence of ethylamine gave mainly the cis dimer and small amounts of the gem isomer (up to 2%), showing the remarkable influence of the nature of the amine on the dimerization reaction, by transposing the regioselectivity [see equation (26.31)]. With other primary or secondary amines, the cis dimer was the major product although the concomitant formation of one regiospecific trimer and one regiospecific tetramer were also observed.

2946

Homogeneous and heterogeneous catalytic processes

Scheme 26.11 Proposed mechanisms for the formation of the gem‐ and cis‐dimers, promoted by the cationic complex [(Et2N)3U][BPh4] in the reaction of iPrCCH with primary amines.

The most remarkable result, aside from the formation of only one trimer and one tetramer, was the fact that the regiochemistry of these oligomers was unpredictable, regardless of amine [equation (26.38)]. The trimer and the tetramer corresponded to the consecutive insertions of an alkyne molecule into the vinylic CH bond trans to the bulky tert‐butyl group.

Cross Dimerization Of Terminal Alkynes Catalyzed By [(Et2N)3U][BPh4] 2947 To reveal the role of the amine, and to examine the possibility that the initially cis isomer was reactivated to yield the regioselective trimer and tetramer, the reactions with deuterated amine tBuND2 and deuterated alkyne tBuCCD were performed (Scheme 26.12). The reaction of tBuCCD with tBuNH2 gave the products with no deuterium, indicating that tBuCCD was transformed into tBuCCH. The reaction for the H/D exchange between tBuCCH and t BuND2 was found to be active in the presence of the catalyst, to give tBuCCD and tBuNHD. These compounds were also observed at early stages of the catalytic oligomerization of tBuCCH in the presence of tBuND2, which afforded the cis dimer as a mixture of mono‐ and non‐deuterated compounds. The amount of the non‐deuterated dimer was always larger than that of the mono‐deuterated dimer. The deuterium atom in the dimer was found only in the trans position relative to the tBu group. Mixtures of non‐ and mono‐deuterated compounds were also obtained for the trimer and tetramer having the deuterium atom always in the internal position, trans to the tBu group. The presence of only one deuterium atom in the oligomers, in unique positions, strongly suggested that this D atom was introduced during the protonolysis steps of the catalytic cycle. In agreement with this hypothesis was the increasing proportion of the trimer and dimer, which likely results from the slower cleavage of the alkenyl intermediate by the deuterated amine or alkyne, permitting further insertion of an alkyne molecule into the U–C bond. The proposed mechanism for the regiospecific formation of the trimer and tetramer is described in Scheme 26.13. The same intermediate 44, which was proposed to explain the trans–cis isomerization of the alkenyl intermediate by the envelope mechanism [equation (26.33)] was proposed to explain conceptually the regiospecific formation of one trimer and one tetramer. The mechanism is based on the 1,2‐hydride shift isomerization of the metal–alkenyl complex 44, leading to the isomeric compound U (step 1). Deuterolysis at this stage liberates the deuterated dimer regioselectively (step 2). Insertion of an alkyne molecule into the U–C bond of U leads to the formation of complex V. The regioselectivity of this insertion (step 3) results from the steric hindrance between the alkyne substituent at the a‐position of the metal–alkenyl chain and the incoming alkyne. The same isomerization process as before converts complex V into the syn complex W (step 4). Protonolysis of W regenerates the catalyst and produces the specific trimer (step 5), whereas the additional insertion of the alkyne, envelope isomerization, and protonolysis yielded the specific tetramer.

26.5 CROSS DIMERIZATION OF TERMINAL ALKYNES CATALYZED BY [(Et2N)3U][BPh4]

Based on the different regioselectivities observed for the cationic complex [(Et2N)3U][BPh4], it was proposed that selective cross dimerization of alkynes could be induced. In the reaction of an equimolar mixture of tBuCCH

Scheme 26.12 Deuterium labeling experiments in the oligomerization of tBuCCH with tBuND2 and tBuCCD with tBuNH2 promoted by [(Et2N)3U][BPh4].

Scheme 26.13 Proposed mechanism for the regioselective dimerization and trimerization of tBuCCH promoted by [(Et2N)3U][BPh4] in the presence of tBuNH2.

2950

Homogeneous and heterogeneous catalytic processes

and iPrCCH with [(Et2N)3U][BPh4], the gem‐dimer of iPrCCH and the gem‐ codimer were obtained [equation (26.39)] (Wang et al., 2002b).

This result was extremely important, since it pointed out that the formation of both metal–acetylide complexes, M–CCR (R ¼ iPr, tBu), was rapid and of comparable rates, although the insertion of iPrCCH into both M–CCR (R ¼ iPr, tBu) moieties was much faster than that of tBuCCH. The lack of any trimer formation implied that the protonolysis of the metal–alkenyl fragments by either one of the terminal alkynes was faster than any additional alkyne insertion. When a mixture of iPrCCH and PhCCH was reacted at room temperature (to avoid trimers), the gem‐codimer was obtained. This codimer was the result of the protonolysis of the metal–alkenyl fragment produced from the insertion of iPrCCH into the M–CCPh moiety. Along with the codimer, a small amount of the gem‐dimer of PhCCH was also produced by the insertion of PhCCH into the M–CCPh moiety before the protonolysis [equation (26.40)]. This result showed that PhCCH preferentially reacted with the precatalyst [(Et2N)3U][BPh4] forming the acetylide complex U–CCPh into which iPrCCH inserted faster as compared with the aromatic alkyne. To shed light on which of the alkynes is the major protonolytic reagent the reaction of a mixture of iPrCCD and PhCCH was performed [equation (26.41)].

Cross Dimerization Of Terminal Alkynes Catalyzed By [(Et2N)3U][BPh4] 2951

The favored formation of the codimer was substantiated with the following observations: (i) the aromatic metal–acetylide moiety was initially formed; (ii) iPrCCD inserted faster than the corresponding aromatic alkyne; (iii) the protonolysis by PhCCH was faster than that of the aliphatic alkyne; (iv) the formation of the deuterated gem‐dimer was obtained due to some excess of the aliphatic alkyne that was present in the reaction. The scrambling of the deuterium atom at the geminal position (only one deuterium at each dimer) was the result of the exchange of acidic H/D atoms between the two aliphatic and aromatic alkynes through the metal center. With an excess of the aliphatic alkyne, the deuterolysis of the most stable U–CCPh by iPrCCD produced PhCCD and U–CCPri that reacted again with the aromatic alkyne yielding back U–CCPh and iPrCCH. The intermediate U–CCPri was the fragment responsible for the formation of the gem unlabelled dimer when the aliphatic alkyne was present in excess. The absence of trimers was an indication that the protonolysis by the PhCCH/D was much faster than any alkyne insertion, aromatic or aliphatic, into the metal–alkenyl complex.

As mentioned above, when the bulkier alkyne tBuCH was dimerized, the cis product was formed in addition to the geminal dimer [equation (26.31)]. Thus, in the codimerization of tBuCH with PhCCH [equation (26.42)], the

2952

Homogeneous and heterogeneous catalytic processes

gem‐codimer and the two dimers (gem and cis) of the aromatic alkyne were characterized as products. This result argued once more for the preferred formation of the aromatic metal–acetylide U–CCPh into which both tBuCCH or PhCCH are able to insert. PhCCH inserted in this codimerization with low regioselectivity and the protonolysis was found to be not as fast as the insertion, since mixtures of trimers of PhCCH were also found in trace quantities.

To avoid the trimers and to allow a better regioselectivity a larger excess (two equivalent) of tBuCCH and one equivalent of PhCCH were used in the cross dimerization [equation (26.43)] producing the gem‐codimer as the major isomer (83%), the gem‐dimer of the aliphatic alkyne (12%), and small amounts of the codimer (5%). This result indicated again that the U–CCPh moiety was the first intermediate formed. To this acetylide intermediate, tBuCCH inserts preferentially in the head‐to‐tail manner to obtain the precursor of the codimer. The effect of external amines in the cross dimerization of terminal alkynes with the cationic complex [(Et2N)3U][BPh4] was investigated by the reaction of an excess of PhCCH with iPrCCH in the presence of EtNH2. The reaction generated low yields of the codimer CH2¼C(iPr)CCPh (17%), as compared with the reaction without external amine, and remarkably the cis aromatic dimer, was the major product [equation (26.44)].

Catalytic hydrosilylation of olefins 26.6

26.6.1

2953

CATALYTIC HYDROSILYLATION OF OLEFINS

Catalytic hydrosilylation of terminal alkynes promoted by neutral organoactinides

The metal‐catalyzed hydrosilylation reaction, which is the addition of a Si–H bond across a carbon–carbon multiple bond, is one of the most important reactions in organosilicon chemistry and has been studied extensively for half a century. The hydrosilylation reaction is used in the industrial production of organosilicon compounds (adhesives, binders, and coupling agents), and in research laboratories, as an efficient route for the syntheses of a variety of organosilicon compounds, silicon‐based polymers, and new type of dendrimeric materials. The versatile and rich chemistry of vinylsilanes has attracted considerable attention in recent years as they are considered important building blocks in organic synthesis (Chan, 1977; Colvin, 1988; Fleming et al., 1989). The syntheses of vinylsilanes have been extensively studied and one of the most convenient and straightforward methods is the hydrosilylation of alkynes (Esteruelas et al., 1993; Takeuchi and Tanouchi, 1994; Asao et al., 1996). In general, hydrosilylation of terminal alkynes produces the three different isomers, cis, trans, and geminal, as a result of both 1,2 (syn and anti) and 2,1 additions, respectively, as shown in equation (26.45). The distribution of the products is found to vary considerably with the nature of the catalyst, substrates, and the specific reaction conditions.

(a) Hydrosilylation of terminal alkynes: scope at room temperature by (C5Me5)2AnMe2 complexes The room temperature reaction of (C5Me5)2AnMe2 (An ¼ Th, U) with an excess of terminal alkynes RCCH (R ¼ tBu, iPr, nBu) and PhSiH3 resulted in the catalytic formation of the corresponding trans‐vinylsilanes RCH ¼ CHSiH2Ph, the dehydrogenative silylalkyne RCCSiH2Ph and alkenes RCH¼CH2 (R ¼ tBu, iPr, nBu) [equation (26.46)] (Dash et al., 1999).

2954

Homogeneous and heterogeneous catalytic processes

Irrespective of the alkyl substituents and the metal center, the major product in the hydrosilylation reaction was the regio‐ and stereoselective trans‐vinylsilane without any trace formation of the other two hydrosilylation isomers (geminal or cis). For bulky alkynes (tBuCCH), the product distribution was nearly the same for both catalytic systems, whereas for other terminal alkynes, it varies from one catalytic system to another. In the hydrosilylation reaction of the alkynes with (C5Me5)2ThMe2 and PhSiH3, similar amounts of the alkene and the silylalkyne were obtained. This result suggested a mechanistic pathway involving two organometallic complexes formed possibly in a consecutive manner, each species being responsible for each one of the products. The reaction of (C5Me5)2UMe2 with TMSCCH (TMS ¼ Me3Si) and PhSiH3 was slow producing the trans‐TMSCH ¼ CHSiH2Ph and the silylalkyne TMSCCSiH2Ph respectively, whereas for the analogous (C5Me5)2ThMe2, no hydrosilylation or dehydrogenative coupling products were observed [equation (26.47)].

(b) Hydrosilylation of terminal alkynes: scope of catalysis at high temperature by (C5Me5)2AnMe2 complexes The chemoselectivity and the regioselectivity of the vinylsilanes formed in the organoactinide‐catalyzed hydrosilylation of terminal alkynes with PhSiH3 at high temperature (65–78 C) were found to be diverse, as compared to the hydrosilylation results obtained at room temperature. The hydrosilylation of RCCH (R ¼ tBu, iPr, nBu) with PhSiH3 catalyzed by (C5Me5)2UMe2, produced in addition to the hydrosilylation products at room temperature [equation (26.46)] the corresponding cis‐hydrosilylated compounds, cis‐ RCH¼CHSiH2Ph, and small to moderate yields of the unexpected double hydrosilylation products RCH¼C(SiH2Ph)2 (R ¼ tBu, iPr, nBu), in which the

Catalytic hydrosilylation of olefins

2955

two silyl moieties are attached to the same carbon atom [equation (26.48)] (Dash et al., 1999).

Whereas (C5Me5)2UMe2 catalyzed the hydrosilylation yielding a mixture of both cis‐ and trans‐vinylsilane, remarkably, (C5Me5)2ThMe2 afforded only the trans‐vinylsilane. In the hydrosilylation reaction of TMSCCH with PhSiH3 catalyzed by (C5Me5)2UMe2, besides the trans‐vinylsilane and the silylalkyne products, which were also obtained at room temperature [equation (26.47)], the cis‐vinylsilane and the olefin TMSCH¼CH2 were also observed [equation (26.49)]. For (C5Me5)2ThMe2, the same products as in the hydrosilylation reaction promoted by (C5Me5)2UMe2 were formed except for the cis‐vinylsilane, in contrast to the room temperature reaction, in which no products were found.

2956

Homogeneous and heterogeneous catalytic processes

(c) Effect of the Ratio Alkyne:Silane and the Silane Substituent in the Hydrosilylation Reaction The effect of PhSiH3 on the formation of the different products was studied by performing comparative experiments. Large chemoselectivity and regioselectivity dependence of the products on the silane concentrations was observed [equation (26.50)].

When the hydrosilylation reaction was carried out using a 1:2 ratio of PrCCH:PhSiH3 with (C5Me5)2ThMe2, the trans‐vinylsilane was found to be the major product. When the reaction was conducted with the opposite ratio between the substrates (iPrCCH:PhSiH3 ¼ 0.5), the olefin iPrCH¼CH2 was found to be the major product, in addition to the other products (trans‐iPrCH¼CHSiH2Ph, iPrCCSiH2Ph, the double hydrosilylated olefin, and the tertiary silane trans‐iPrCH¼CHSiH(Ph)(CCiPr)). The tertiary silane was obtained by the dehydrocoupling metathesis between the trans‐alkenylsilane and the metal acetylide complex. The replacement of a hydrogen atom on PhSiH3 by either an alkyl or a phenyl group generated a reduction in the hydrosilylation reaction rate when compared to the rate obtained utilizing phenylsilane. The selectivities of the products were appreciably different when compared to those obtained using PhSiH3 as the hydrosilylating agent [equation (26.51)]. i

Catalytic hydrosilylation of olefins

2957

(d) Kinetic studies on the hydrosilylation of iPrCCH with PhSiH3 catalyzed by (C5Me5)2ThMe2 The kinetic study of the hydrosilylation of iPrCCH with PhSiH3 catalyzed by (C5Me5)2ThMe2 shows a first‐order dependence in alkyne, silane, and catalyst. The empirical rate law expression for the (C5Me5)2ThMe2 catalyzed hydrosilylation of iPrCCH with PhSiH3 is given by equation 26.52. n ¼ k½i PrC  CH½PhSiH3 ½ðC5 Me5 Þ2 ThMe2 

ð26:52Þ

From the Eyring analysis, the derived activation parameters, Ea, DH{, and DS{ values are 6.9 (3) kcal mol–1, 6.3(3) kcal mol–1, and 51.1(5) eu, respectively. (e) Formation of active species, mechanism, and thermodynamics in the hydrosilylation of alkynes We have already seen that in the reaction of either bisacetylide organoactinide complex with PhSiH3 the quantitative isolation of complexes 18 and 19, for thorium and uranium, respectively, was observed [equation (26.4)]. These complexes were formed by the s‐bond metathesis with the silane forming the corresponding actinide hydrides and the silylalkyne, which rapidly reinsert producing 18 or 19 [equation (26.53)].

The regioselectivity of the insertion of PhSiH2CCPri into the actinide hydride bond is electronically favored, driven by the polarity of the organoactinides and the p* orbital of the alkyne (Apeloig, 1989). In addition, since the insertion occurs through a four‐center transition state mechanism, the cis‐ stereochemistry is expected, as corroborated by the H2O poisoning experiment and the high‐temperature reactions with alkyne or silane [equation (26.5)]. The same regioselective insertion of TMSCCH into an organothorium

2958

Homogeneous and heterogeneous catalytic processes

alkenyl complex Th–C bond was observed in the organoactinide‐catalyzed oligomerization of alkynes (Straub et al., 1995, 1999). The formation of an organoactinide–silane intermediate 46 as described in Scheme 26.14 was shown to be not operative by the following experiments: (1) quenching experiments with water gave exclusively the cis vinylsilane; (2) under stoichiometric conditions, the addition of silane did not induce the protonolysis of the acetylide–alkenylsilane complex (18 or 19), to yield complex 46; (3) no geminal hydrosilylated products were obtained (as would be expected were complex 48 an intermediate); (4) no cis hydrosilylated products can be obtained from complex 46, and (5) no cis double hydrosilylated product was observed (if s‐bond metathesis occurred from complex 47 or 48) (Dash et al., 1999). The reactions of complexes 18 or 19 yielding the double hydrosilylated product [equation (26.54)] were proposed to be stereoselectively favored, due to the assumed polarization of the PhSiH3 towards the metal center, as well as the preferred thermodynamics, as compared to the protonolysis by the silane producing complex 46 and the cis hydrosilylated product (DH(Th) ¼ þ 15 (4) kcal mol–1; DH(U) ¼
3 (2) kcal mol–1). The most remarkable observation concerned the reaction products of complexes 18 or 19 with alkyne at either low or high temperatures. At elevated temperatures, the expected cis‐hydrosilylated product was obtained, but at low temperatures, the unexpected trans isomer was achieved. These results have been explained through a competitive mechanism in which an equilibrium gives the different hydrosilylation products at different temperatures.

Different alkynes displayed different reactivities. TMSCCH exhibited a total lack of reactivity with PhSiH3 in the presence of (C5Me5)2ThMe2 at room temperature. However, at high temperature, the trans vinylsilane, the silylalkyne, and the alkene were obtained. This type of reactivity was explained, in general, as the result of a kinetic effect suggesting also an equilibrium between the organometallic complexes 50 and 51 (Scheme 26.15). Complex 51 was obtained by the insertion of the silylalkyne into a hydride complex. Complex 51 is able to react with another alkyne, yielding the alkene and the bis(acetylide) complex (protonolysis route) or react with a silane producing the organometallic hydride and the trans‐product (s‐bond metathesis route). The low activity

Scheme 26.14 Expected organoactinide intermediates in the stoichiometric hydrosilylation of terminal alkynes through a transient organoactinide–silicon bond.

Scheme 26.15 Protonolysis and s‐bond metathesis routes for the high‐temperature hydrosilylation of TMSCCH with PhSiH3 catalyzed by (C5Me5)2ThMe2.

Catalytic hydrosilylation of olefins

2961

obtained for TMSCCH was explained by an elevated activation energy to perform both the metathesis or protonolysis of complex 51, as compared with other alkynes (Dash et al., 1999). The ratio between the silane and the alkyne were found to govern the kinetics leading to the different products. Thus, when the PhSiH3:iPrCCH ratio was two, the trans‐ and the double‐hydrosilylation products were the major products (metathesis route). Increasing the alkyne concentration routed the reaction towards the alkene and the bis(acetylide) complex (protonolysis route). A likely mechanism for the hydrosilylation of terminal alkynes catalyzed by Cp 2 ThMe2 was proposed and described in Scheme 26.16. The mechanism presented in Scheme 26.16 consists of insertion of acetylene into a metal–hydride s‐bond, s‐bond metathesis by a silane, and protonolysis by an acidic alkyne hydrogen. The precatalyst (C5Me5)2ThMe2 in the presence of alkyne was converted to the bis(acetylide) complex Z. Complex Z reacts with PhSiH3 towards the silylalkyne and the organoactinide hydride X (step 1), which was found to be in equilibrium with the intermediate AA after reinsertion of the silylalkyne with the preferential stereochemistry (step 2). Complex AA was found to be the principal complex under silane and alkyne starvation. Complex X will react with an alkyne producing the alkenyl acetylide organothorium complex Y (step 3), which is presumably in equilibrium with complex X (first‐order in alkyne). Complex Y was proposed to react with PhSiH3, as the rate‐determining step, regenerating the hydride complex X and the trans‐hydrosilylated product (step 4). Under the catalytic conditions, complex Y may also react with a second alkyne producing the alkene and the bis (acetylide) complex Z (step 5). A similar insertion of the alkene into complex X with the concomitant reaction with an additional alkyne produced the double hydrogenated product, as found for isopropylacetylene. At high temperature, complex AA may react with a silane (step 6), yielding complex X and the double hydrosilylation product or with an alkyne (step 7), yielding complex Z and the cis‐isomer. Thus, the reaction rate law [equation (26.52)] was rationalized with rapid irreversible phenylsilane metathesis with complex Z, rapid pre‐equilibrium involving the hydride, and alkenyl complexes X and Y, and a slow metathesis by the PhSiH3. For the thorium complex, step 6 was found to be much faster than step 7 since the amounts of the cis‐product were obtained in trace amounts. The mechanistic pathway as proposed, takes into the account comparable yields for the alkene and silylalkyne even when the alkyne concentration was in excess (the sum of the silylated products must equal the amount of the alkene). For the thorium or uranium complexes, the amount of the hydrosilylated product was always similar to or larger than that of the alkene, indicating that a competing equilibrium should be operative, responsible for the transformation of the hydride complex back to the bisacetylide complex, allowing the production of the silylalkyne without producing the alkene [equation (26.55)].

Scheme 26.16 Proposed mechanism for the room‐ and high‐temperature hydrosilylation of isopropylacetylene with PhSiH3 promoted by (C5Me5)2ThMe2.

Catalytic hydrosilylation of olefins

2963

Thermodynamically, it is very interesting to compare the possible mechanistic silane and hydride intermediates towards the possible hydrosilylation trans‐ product as presented in equations (26.56) and (26.57), respectively.

Homogeneous and heterogeneous catalytic processes

2964

The calculated enthalpy of reaction for the insertion of an alkyne into an actinide–silane bond [equation (26.56)] (DHTh ¼ –52 kcal mol–1, DHU ¼ –34 kcal mol–1) or into an actinide hydride bond [equation (26.57)] (DHTh ¼ –33 kcal mol–1, DHU ¼ –36 kcal mol–1) was expected to be exothermic. However, the protonolysis by the silane yielding the An‐Si bond and the trans‐product [equation (26. 56)] was for thorium an endothermic process (DHTh ¼ þ 15 kcal mol–1), as compared to the exothermicity of the s‐bond metathesis [equation (26.57) of the thorium alkenyl complex with the silane (DHTh ¼ –19 kcal mol–1), yielding the corresponding Th–H bond and the trans‐product. For the corresponding uranium complexes, the latter processes were calculated to be exothermic although the s‐bond metathesis route [equation (26.57)] was more exothermic (DHU ¼ –26 kcal mol–1) than the protonolysis route [equation (26.56)] (DHU ¼ –3 kcal mol–1). 26.6.2

Catalytic hydrosilylation of terminal alkynes promoted by the bridged complex Me2 SiCp002 Thn Bu2

The hydrosilylation reaction of terminal alkynes and PhSiH3 catalyzed by Me2 SiCp002 Thn Bu2 resulted in the speedy and regioselective formation of the hydrosilylated trans‐vinylsilane as the unique product regardless of the alkyne substituent [equation (26.58)].

When an olefin‐functionalized alkyne was used for the reaction with PhSiH3, the alkyne moiety was regioselectively hydrosilylated to yield the corresponding trans‐diene [equation (26.59)]. Addition of an excess of PhSiH3 did not induce any subsequent hydrosilylation.

Catalytic hydrosilylation of olefins

2965

The addition of an excess of PhSiH3 to any of the vinylsilane products did not induce further hydrosilylation. However, addition of a second equivalent of an alkyne to a hydrosilylation product allowed the formation of the corresponding alkene and the dehydrogenative coupling of the alkyne with the trans‐vinylsilane [equation (26.60)] (Forsyth et al., 1991; Harrod, 1991; Corey et al., 1993; Tilley, 1993).

(a) Kinetic and thermodynamic studies for the hydrosilylation of terminal alkynes with primary silanes promoted by the bridged complex Me2Si(C5Me4)2ThnBu2 Kinetic measurements on the hydrosilylation iPrCCH with PhSiH3 catalyzed by Me2Si(C5Me4)2ThnBu2 indicated that the reaction behaved with a first‐order dependence in precatalyst and silane, and exhibited an inverse proportionality (inverse first‐order) in alkyne [equation (26.61)]. The inverse proportionality was consistent with a rapid equilibrium before the turnover limiting‐step, removing one of the key organoactinide intermediates from the catalytic cycle. n ¼ k½Me2 SiðC5 Me4 Þ2 Thn Bu2 ½silane1 ½alkyne
1

ð26:61Þ

The derived DH{ and DS{ parameter values from a thermal Eyring analysis were measured to be 10.07(5) kcal mol–1 and –22.06(5) eu, respectively (Dash et al., 2001). It is important to note the difference between the kinetic behavior of the alkyne in the hydrosilylation reaction and that in the dimerization process (vide supra). In the latter process, the alkyne was involved in two parallel routes, both sensitive to the alkyne concentration. In one route, the alkyne exhibited an inverse kinetic order (removing one of the active compounds from catalytic cycle), whereas in the second pathway the alkyne was involved in the rate‐ determining step. Thus, at high alkyne concentrations the overall dependence

2966

Homogeneous and heterogeneous catalytic processes

on alkyne is cancelled out. In the hydrosilylation process, the alkyne was proposed to be only involved in routing an active compound out of the catalytic cycle, with the silane presumably reacting in the rate‐limiting step. Thus, modification of the alkyne order was observed. In the hydrosilylation reactions of organo‐f‐element complexes, two Chalk–Harrod mechanisms have been proposed as plausible routes, differing in the inclusion of a s‐bond metathesis instead of the classical oxidative addition–reductive elimination processes. The two mechanisms differ in the reactive intermediates; the hydride (M–H) route and the silane (M–SiR3) route (Chalk and Harrod, 1965; Harrod and Chalk, 1965; Ruiz et al., 1987; Seitz and Wrighton, 1988; Tanke and Crabtree, 1991; Duckett and Perutz, 1992; Marciniec et al., 1992; Takeuchi and Yasue, 1996; Bode et al., 1998; Ojima et al., 1998; Reichl and Berry, 1998; Sakaki et al., 1998). The use of terminal alkynes with bridged organoactinides was an excellent probe to investigate which of the two routes was the major pathway followed. Thus, taking into account that the alkyne was expected to insert with the substituent group pointing away from the metal center (as observed in the dimerization) the following mechanistic insights were obtained. If the hydrosilylation reaction goes through a M–SiR3 intermediate, the gem‐hydrosilylated vinyl isomer will be formed, whereas only the trans‐isomer will be obtained via the M–H route (if the insertion stereochemistry is not maintained, the cis product will be observed). The exclusive selectivity obtained for Me2Si(C5Me4)2ThnBu2 towards the trans hydrosilylated isomer argued that the hydride route was acting as the major mechanistic pathway. (b) Hydrosilylation of terminal alkynes with primary silanes promoted by the bridged complex Me2Si(C5Me4)2ThnBu2: scope and mechanism The hydrosilylation of terminal alkynes with PhSiH3 promoted by the bridged complex Me2Si(C5Me4)2ThnBu2 produced regioselectively and chemoselectively the trans‐hydrosilylated vinylsilane without any other by‐products. The lack of silylalkynes, the dehydrogenative silane coupling products, or any other geometrical isomer of the vinylsilane strongly indicated that the Th–H pathway was the major operative route in the hydrosilylation reaction. A plausible mechanism for the hydrosilylation of terminal alkynes towards trans‐vinylsilanes was proposed and is presented in Scheme 26.17. The precatalyst Me2Si(C5Me4)2ThnBu2 in the presence of silane and alkyne was converted into the hydride complex BB (step 1), as observed by the stoichiometric formation of n‐BuSiH2Ph. Rapid insertion of an alkyne into complex BB allows the formation of the vinylic complex CC (step 2). Complex CC was found to be in rapid equilibrium with the proposed p‐complex DD (step 3), responsible for the inverse order in alkyne, and undergoes a s‐bond metathesis with PhSiH3, as the rate‐determining step (step 4), producing selectively the trans‐hydrosilylated vinyl product and regenerating complex BB. Since no

Catalytic hydrosilylation of olefins

2967

Scheme 26.17 Proposed mechanism for the hydrosilylation of terminal alkynes with PhSiH3 promoted by the bridged complex Me2Si(C5Me4)2ThnBu2.

geometrical isomers or different products were observed by adding an excess of PhSiH3 to any of the vinylsilanes, neither the hydride complex BB nor the alkenyl complex CC were found to be the resting catalytic state, indicating complex DD is the resting state. However, the subsequent addition of a second equivalent of an alkyne to the reaction mixture formed the corresponding alkene and the silylalkyne. The formation of these two compounds was proposed to follow the mechanistic pathway as shown in Scheme 26.18. Complex CC reacts, in the absence of a primary silane, with another alkyne (step 5) producing the corresponding alkene and the acetylide complex EE. A s‐bond metathesis with the Si–H bond of the vinylsilane (step 6) formed the

Scheme 26.18 Proposed mechanism for the formation of alkene and silylalkyne in the presence of vinylsilanes and terminal alkynes promoted by Me2Si(C5Me4)2ThnBu2. Only one of the equatorial ligations at the metal center is shown for clarity.

Catalytic hydrosilylation of olefins

2969

dehydrogenative coupling product and regenerated the hydride complex BB (Dash et al., 2001). The yield of the alkene was found to be lower than that of the silylalkyne product. Therefore, an additional equilibrium reaction was proposed to exist, responsible for the transformation of complex BB into the acetylide complex EE, allowing the formation of the silylalkyne without forming the alkene. This pathway was also observed for non‐bridged organoactinides [equation (26.55)] (Dash et al., 1999, 2001). Examination of the measured rates of the hydrosilylation process catalyzed by the bridged complex revealed larger turnover frequencies as compared to (C5Me5)2YCH3 ·THF or other lanthanide complexes (Schumann et al., 1999). The yttrium complex was found to induce the hydrosilylation reaction of internal alkynes preferentially towards the E‐ isomer, although in some case the Z‐isomer was found in comparable amounts. Mechanistically, the active species for the yttrium hydrosilylation of internal alkynes was proposed to be the corresponding hydride (Molander and Knight, 1998). It is well known that the hydrosilylation of alkynes is induced either by radical initiators (Selin and West, 1962) or by transition metal catalysts (Weber, 1983; Hiyama and Kusumoto, 1991; Sudo et al., 1999). The radical procedure often provides a mixture of trans‐ and cis‐hydrosilylation products. In contrast, the transition metal catalyzed reaction proceeds with high stereoselectivity via a cis‐hydrosilylation pathway usually producing a mixture of two regio‐isomers (terminal and internal adducts). Thus, the organoactinide process seems to contain a unique chemical environment allowing the production of the trans‐vinylsilane, complementing the chemistry of other transition metal complexes. 26.6.3

Catalytic hydrosilylation of alkenes promoted organoactinide complexes

The organoactinide complexes (C5Me5)2ThMe2 and Me2Si(C5Me4)2ThnBu2 were also found to be good precatalysts for the highly regio‐selective hydrosilylation of alkenes. The chemoselectivity of the reactions was moderate since the hydrogenated alkane was always encountered as a concomitant product. The reactions of (C5Me5)2ThMe2 and Me2Si(C5Me4)2ThnBu2 with an excess of an alkene and PhSiH3 resulted in the formation of the regioselective 1,2‐ addition hydrosilylated alkene and the alkane with no major differences between the two organoactinides [equation (26.62)] and Table 26.1 (Dash et al., 2001).

d

c

b

n

Bu Bu n Bu n Bu n C6H13 n C6H13 PhCH2 PhCH2 Ph Ph

n

R in RHC¼CH 20 20 78 78 20 20 78 78 78 78

Temperature ( C) 12 12 6 1 12 12 6 1 36 36

Time (h) 54 63 57 62 68 65 61 71 65(6)d 31(30)d

Yield of 1‐silylalkane (%)

Solvent ¼ benzene. B ¼ Me2Si(C5Me4)2ThnBu2, NB ¼ (C5Me5)2ThMe2. Turnover frequency for the hydrosilylation process. The number in parentheses corresponds to the 2,1‐addition hydrosilylation product, 2‐(phenylsilyl)ethylbenzene.

NB B NB B NB B NB B NB B

1 2 3 4 5 6 7 8 9 10

a

Cat.b

Entry 44 35 41 36 30 33 38 29 28 37

Yield of alkane (%)

Table 26.1 Activity data for the hydrosilylation of alkenes promoted by (C5Me5)2ThMe2 and Me2Si(C5Me4)2ThnBu2.a

1.5 5.5 3.2 64.5 1.9 4.6 4.8 83.1 0.9 1.9

Ntc (h–1)

Catalytic hydrosilylation of olefins

2971

Since for the substrate allyl benzene only one hydrosilylated product was formed, a comparison of the effect of distance between the aromatic ring and the metal center was performed. In the hydrosilylation of styrene with each of the organoactinides [equation (26.63)], both 1,2‐ and 2,1‐hydrosilylation products were obtained, in addition to ethylbenzene. For (C5Me5)2ThMe2, a small amount of the branched silane was obtained whereas for the coordinatively unsaturated complex Me2Si(C5Me4)2ThnBu2 equal amounts of both (linear and branched) isomers were found (entries 9,10 in Table 26.1).

The presence of the two major products (hydrosilylation and hydrogenation) indicated the existence of two parallel catalytic pathways. The formation of the hydrogenation products required considering the possibility that intermediates with Th–Si/Th–H bonds were formed [equation (26.64)]. Thus, the production of alkanes might be considered, to some extent, as indirect evidence of the existence of complexes containing an actinide–Si bond. Protonolysis of a Th–alkyl by the silane will yield the Th–Si bond and the hydrogenation product, whereas metathesis of the Th–alkyl by the silane will produce the hydrosilylated compound regenerating the hydride complex.

Another pathway to obtain a hydrogenation product from a Th–alkyl complex may be proposed, consisting of cutting the alkyl chain with an additional alkene, forming a transient vinyl complex. Therefore, the reaction between (C5Me5)2ThMe2 and an excess of 1‐octene was studied. Although no hydrogenation product was observed, ruling out the protonolysis by an alkene, a stoichiometric reaction, resulting in the production of 2‐methyl‐1‐octene, 2‐nonene, and 3‐nonene in almost equal amounts, and the additional slow catalytic isomerization of the starting 1‐octene to E‐4‐octene (3.8%), E‐3‐octene (39.4%), E‐2‐octene (13.0%), and Z‐2‐octene (41.8%), was observed [equation (26.65)] (Dash et al., 2001).

2972

Homogeneous and heterogeneous catalytic processes

This result indicated that the Th–Me bond underwent insertion by the alkene moiety, forming a Th–alkyl complex, followed by a b‐hydrogen elimination to the corresponding metal–hydride (Th–H) and equimolar amounts of all three isomeric nonenes. The hydride was proposed to be the active species in the isomerization of 1‐octene. The same reaction with 2‐octene showed a slower reaction and different product ratios (E‐3‐octene (11.2%), E‐2‐octene (82.2%), and Z‐2‐octene (6.6%)), indicating a non‐equilibrium process between 1‐octene and 2‐octene. In order to study the resting state of the organoactinide catalyst given that only two complexes with either a thorium hydride (Th–H) or a thorium–alkyl (Th–R) were expected, the isomerization reaction was followed until full conversion of 1‐octene (>98%) was obtained. All the volatiles were removed under vacuum and new solvent was reintroduced. The ratio between the products that remained in the reaction mixture was measured by gas chromatography, demonstrating the disappearance of 1‐octene. Quenching of the reaction mixture with a slight excess of D2O at low temperatures, and analysis of the solution showed the presence of a mono‐deuterated 1‐d‐octane, indicating that the Th–alkyl moiety was the resting organoactinide. The most astounding result was the presence of equimolar amounts of 1‐octene, based on the metal complex. This result indicated that a p‐alkene thorium–alkyl complex (HH in Scheme 26.19) was the resting catalytic state of the organoactinide complex; addition of D2O liberated the alkene and the alkane from the metal. (a)

Kinetic studies of the hydrosilylation of alkenes with PhSiH3

Kinetic measurements of the hydrosilylation of allylbenzene with PhSiH3 catalyzed by (C5Me5)2ThMe2 were performed. The reaction was found to follow a first‐order dependence in precatalyst and silane, and exhibits an inverse first‐ order dependence in alkene. The inverse proportionality as described for alkynes is consistent with a rapid equilibrium before the rate‐determining step, steering an intermediate out of the catalytic cycle. Thus, the rate law for the hydrosilylation of alkenes with PhSiH3 promoted by (C5Me5)2ThMe2 can be expressed as presented in the following equation: n ¼ k½ðC5 Me5 Þ2 ThMe2 ½silane1 ½alkene
1

ð26:66Þ

The derived Ea, DH{, and DS{ parameter values from an Arrhenius and a thermal Eyring analysis were measured to be 11.0(4) kcal mol–1, 10.3(4) kcal mol–1, and –45 eu, respectively. A comparison of the product distribution for both bridged and non‐bridged organoactinides revealed that no special effects were introduced by increasing the coordinative unsaturation of the organothorium complex. The presence of double hydrosilylation products suggested the presence of two parallel interconnecting competing pathways. The formation of the alkane required the presence of the intermediate Th–H/Th–Si moieties (Eisen, 1997, 1998). The only evidence available so far for the formation of a Th–Si bond was obtained

Scheme 26.19 Proposed mechanism for the hydrosilylation of alkenes with PhSiH3 promoted by (C5Me5)2ThMe2 or Me2Si(C5Me4)2ThnBu2. The scheme depicts the mechanism for the unbridged metallocene. Only one of the equatorial ligations at the metal center is shown for clarity.

Homogeneous and heterogeneous catalytic processes

2974

from the formation of a metalloxy ketene via the double insertion of carbon monoxide into a Th–Si bond (Radu et al., 1995). The proposed mechanism for the hydrosilylation of alkenes promoted by organoactinides is described in Scheme 26.19. The first step in the proposed mechanism is the reaction of the precatalyst (C5Me5)2ThMe2 with PhSiH3, yielding the hydride complex FF and PhSiH2Me. Complex FF may react with an alkene producing the alkyl complex GG (step 1), which can undergo three parallel pathways. The first route is a reaction with an alkene, to produce a p‐alkene complex HH, removing the complex GG from the catalytic cycle (step 2), and giving rise to the inverse order in alkene. The second and third paths are metathesis and protonolysis reactions between the Th–alkyl fragment and the Si‐H moiety, yielding in the former case the substituted silane and regenerating complex FF (step 3), and yielding in the latter process the Th– SiH2Ph complex and the alkane (step 4). The proposed scheme also takes into account the formation of materials in trace amounts. For styrene, the formation of both hydrosilylation products in similar amounts indicates comparable activation energy for both processes, differing only in the disposition of the silane with respect to the thorium alkyl complex. The Th–SiH2Ph bond can be activated by two different paths. The metathesis reaction with the Si–H bond in PhSiH3 produces the dehydrogenative dimer and the hydride FF (step 5), whereas in the reaction with a Si–Ph bond, Ph2SiH2, and a complex containing the Th–SiH3 (II) moiety will be obtained (step 6), which will then rapidly react with an additional silane yielding the oligomeric dehydrogenative coupling of silanes (step 7). In the hydrosilylation of styrene, the formation of the branched isomer was rationalized by the stereochemistry of the insertion reaction of the styrene with the metal hydride complex (Scheme 26.20); the alkyl formed is presumably stabilized by the p‐arene interaction (JJ0 ). For alkenes, the hydrosilylation reaction promoted by organolanthanides of the type (C5Me5)2LnR (Ln ¼ Sm, La, Lu) or Me2Si(C5Me4)2SmR are much faster (by one order of magnitude) than those obtained with organoactinides. The major difference is found for linear a‐alkenes, which lanthanides will hydrosilylate forming both isomers, whereas actinides will exclusively yield the 1,2‐adduct product (Harrod, 1991; Ojima et al., 1998; Schumann et al., 1999). Mechanistically, the lanthanide hydrides have been proposed as the primary pathway towards the hydrosilylated products. Thus, organoactinides represent again complementary catalysts to organolanthanides and other transition metal complexes for the regioselective hydrosilylation of a‐olefins. 26.6.4

Catalytic hydrosilylation of alkynes promoted by the cationic complex [(Et2N)3U][BPh4]

The hydrosilylation reactions of terminal alkynes promoted by neutral organoactinides has motivated similar studies whose goal is the formation of a cationic hydride complex as an intermediate in the catalytic hydrosilylation of

Catalytic hydrosilylation of olefins

2975

Scheme 26.20 Proposed mechanism for the hydrosilylation of styrene and PhSiH3 promoted by (C5Me5)2ThMe2 or Me2Si(C5Me4)2ThnBu2.

terminal alkynes. Reactions promoted by the cationic complex [(Et2N)3U] [BPh4] were studied (Dash et al., 2000). The reaction of [(Et2N)3U][BPh4] with terminal alkynes RCCH (R ¼ iPr, tBu) and PhSiH3 resulted in the catalytic formation of a myriad of products. The observed products cis‐ and trans‐vinylsilane (RCH¼CHSiH2Ph), the dehydrogenative silylalkyne (RCCSiH2Ph), alkenes (RCH¼CH2) (R ¼ iPr, tBu), and the aminosilane Et2NSiH2Ph were found to account for 100% conversion with respect to the alkyne. For the bulky tBuCCH, the tertiary silanes trans‐tBuCH¼CHSi(HPh) (CCtBu), and tBuCH¼C(SiH2Ph)Si(HPh)(CCtBu) were also observed [equation (26.67)]. Formation of the tertiary silanes can be accounted for by metathesis reactions of the trans‐alkenylsilane and the double hydrosilylated compound with the metal acetylide complex 52, respectively, as shown in equations (26.68) and (26.69).

2976

Homogeneous and heterogeneous catalytic processes

At high temperatures (65–78 C), the chemoselectivity and regioselectivity of the products formed in the cationic organouranium‐catalyzed hydrosilylation of terminal alkynes with PhSiH3 were found to be different in comparison to those obtained at room temperature. The hydrosilylation of RCCH (R ¼ n Bu, iPr, tBu) with PhSiH3 catalyzed by [(Et2N)3U][BPh4] produced, in addition to the hydrosilylation products at room temperature [equation (26.67)], the corresponding double hydrosilylated compounds: RCH¼C(SiH2Ph)2 (R ¼ n Bu, iPr, tBu), and small amounts of the corresponding geminal dimers and trimers. A similar type of mechanism as observed for the neutral organoactinides was proposed, based on kinetic data and product distributions. The formation of an active uranium hydride complex 53 was proposed to occur either by the reaction of the cationic complex with a silane molecule, giving the corresponding aminosilane, and/or by the reaction of the acetylide complex 52 with a silane, producing the corresponding silylalkyne [equations (26.70) and (26.71), respectively).

The proposed mechanism, which takes into account the formation of all products, is described in Scheme 26.21 (Dash et al., 2000). The precatalyst [(Et2N)3U][BPh4] in the presence of alkyne was converted to the acetylide complex 52 by removal of one of the amido ligands. Complex 52 was proposed to react with PhSiH3 to give the silylalkyne and the actinide hydride 53 (step 1). The hydride 53 may reinsert the silylalkyne forming complex 55 (step 2) or react with the alkyne to produce the alkenyl uranium complex 54 (step 3). Complex 54 is then proposed to react with PhSiH3, regenerating the organouranium hydride complex 53 and the trans‐hydrosilylated product

Scheme 26.21 Proposed mechanism for the room‐ and high‐temperature hydrosilylation of terminal alkynes promoted by [(Et2N)3U][BPh4]. The transformation of the starting complex into the acetylide complex [(Et2N)2U–CCR][BPh4] (52) was described in Scheme 26.10, and is omitted here for clarity.

2978

Homogeneous and heterogeneous catalytic processes

(step 4). Under catalytic conditions, complex 54 may also react with a second alkyne giving the alkene and the acetylide complex 52 (step 5). Complex 55 may react with a silane (step 6) yielding complex 53 and the double hydrosilylation product, or with an alkyne (step 7) yielding complex 52 and the cis‐isomer. This mechanistic scenario took into account the higher yields observed for the alkene compound as compared with those obtained for the silylalkyne. For TMSCCH and iPrCCH at high temperature, the amount of the hydrosilylated products is larger than that of the alkenes, indicating that a competing equilibrium route was present. This would again involve the transformation of the hydride 53 back into the acetylide complex 52 by reaction with the alkyne [equation (26.72)], allowing the production of more silylalkyne without producing the alkene. The hydride 53 could alternatively react with PhSiH3 to give the organometallic silyl compound [(Et2N)2USiH2Ph][BPh4] [equation (26.73)], which would further react with PhSiH3 or RCCH to regenerate the hydride 53 and PhH2Si‐SiH2Ph or PhH2SiCCR, respectively.

In the hydrosilylation reaction of tBuCCH at high temperature, a small amount of the dehydrogenative coupling of phenylsilane was observed. This product argued for the formation of a compound with an uranium–silicon bond, although not as a major intermediate. The compound [(Et2N)2USiH2Ph] [BPh4] can be theoretically postulated instead of the hydride complex 53 either from steps 1, 4, or 6 in the catalytic cycle (Scheme 26.21). In these steps, the silane would act as the protonolytic source.

26.7 DEHYDROCOUPLING REACTIONS OF AMINES WITH SILANES CATALYZED BY [(Et2N)3U][BPh4]

The catalytic processes involving the cationic uranium amide complex, [(Et2N)3U][BPh4], have been found to be particularly efficient in the controlled dimerization of terminal alkynes and in the hydrosilylation reactions of terminal alkynes and alkenes with PhSiH3. These processes have been characterized

Dehydrocoupling reactions of amines with silanes

2979

through the activation of the corresponding amido uranium–acetylide or the amido uranium–hydride species that were the active intermediates, respectively. A conceptual question that arose from those studies concerned the possibility of activating the amido ancillary ligands in [(Et2N)3U][BPh4] with a silane molecule producing the corresponding aminosilane and an organometallic hydride complex. The ability to transform the hydride into the starting amido complex using another amine with the attendant elimination of dihydrogen would give a way to perform the catalytic dehydrogenative coupling of amines and silanes. Thermodynamic calculations have predicted this process as plausible (King and Marks, 1995). The dehydrogenative coupling of amines and silanes has been performed by either late transition metal catalysts (Blum and Laine, 1986; Biran et al., 1988; Wang and Eisenberg, 1991) or early transition metal complexes (Liu and Harrod, 1992; He et al., 1994; Lunzer et al., 1998). These reactions are an alternate route to silazanes, which are precursors for the synthesis of silicon nitride materials. The reaction of nPrNH2 and PhSiH3 promoted by the cationic complex [(Et2N)3U][BPh4] produced dihydrogen and the aminosilanes PhSiH (NHPrn)2 and PhSi(NHPrn)3 [equation (26.74)]. The use of a large excess of amine allowed for full conversion of the silane into the di‐ and tri‐aminosilanes. The monoaminosilane, PhSiH2(NHPrn), was not detected, indicating that in this compound the Si–H hydride bonds were more reactive than those in the starting PhSiH3 (Wang et al., 2000). The reaction of iPrNH2 and PhSiH3 gave dihydrogen together with PhSiH2NHPri (33%) and PhSiH(NHPri)2 (56%) with a total conversion of 89% for PhSiH3. The use of large amine excess promoted the reaction towards the bisaminosilane PhSiH(NHPri)2. The bulky tBuNH2 reacted with PhSiH3 producing PhSiH2NHBut quantitatively. This monoaminosilane reacted further with an excess of amine to produce an additional equivalent of dihydrogen and exclusively the bisaminosilane PhSiH(NHBut)2. This latter compound was transformed back slowly into the mono aminosilane, PhSiH2NHBut, after the addition of one equivalent of PhSiH3 [equation (26.75)], which indicated that the production of aminosilanes promoted by the cationic complex [(Et2N)3U][BPh4] was in equilibrium.

2980

Homogeneous and heterogeneous catalytic processes

Ethylenediamine H2NCH2CH2NH2 reacted with PhSiH3 in the presence of the catalyst, yielding dihydrogen and the spiro chelated complex PhSi(Z2‐NHCH2CH2NH)(Z2‐NHCH2CH2NH2) quantitatively. When the spiro product was heated at 25 C under vacuum, ethylenediamine was removed and PhSi(Z2‐NHCH2CH2NH)(Z2‐NHCH2CH2NH2) was transformed into a mixture of oligomers [equation (26.76)].

From these results it was concluded that the reactivity of primary amines RNH2 in the formation of aminosilanes with PhSiH3 catalyzed by the cationic uranium complex [(Et2N)3U][BPh4] follows the order primary > secondary > tertiary. Secondary amines and secondary silanes were found to be less reactive than the corresponding primary amine and silanes. The reaction of Et2NH with PhSiH3 produced H2 and a mixture of PhSiH(NEt2)2 and PhSiH2NEt2. No reaction was observed between (iPr)2NH and PhSiH3, presumably because of the steric hindrance of the amine. The bulk of the silane was also found to have an effect. nPrNH2 reacted with the secondary silane PhSiMeH2, generating H2, PhSiHMe(NHPrn) and PhSiMe(NHPrn)2. [(Et2N)3U][BPh4] reacted directly with stoichiometric or excess amounts of PhSiH3, creating in both cases one equivalent of the corresponding aminosilane PhSiH2NEt2 and [(Et2N)UH][BPh4]; when an excess of silane was used, trace formation of the homodehydrogenative coupling product of the silane was observed. These results identified the monohydride complex as the active intermediate, since no other amido moieties were found to react with the phenylsilane. Therefore, the synthesis of a uranium hydride was accomplished by treatment of the corresponding amide with a silane, as has been reported in zirconium chemistry. Similar exchange reactions with boranes, alanes, and stannanes have been observed (Lappert et al., 1980; Hays and Fu, 1997; Liu et al., 1999). A plausible mechanism for the dehydrocoupling of amines with silanes promoted by the cationic complex [(Et2N)3U][BPh4] is described in Scheme 26.22. The first step of the mechanism was proposed to be the transamination reaction of [(Et2N)3U][BPh4] with RNH2 giving [(NHR)3U][BPh4] (KK) (step 1). Complex KK may react with PhSiH3 to afford the monoaminosilane PhSiH2NHR and the corresponding hydride [(NHR)2UH][BPh4] (LL) (step 2). The last step of the catalytic cycle (step 3) is the reaction of LL and the amine, regenerating KK with the concomitant elimination of dihydrogen.

Intermolecular hydroamination of terminal alkynes

2981

Scheme 26.22 Proposed mechanism for the coupling of amine with silanes promoted by [(Et2N)3U][BPh4].

The different polyaminosilanes PhSiH3–n(NHR)n are obtained by replacing PhSiH3 with PhSiH4–n(NHR)n–1 (n  1) in step 2. Since in the presence of an excess of amine the reactive hydrogen atoms were found to be those of the silane, a study of the reactivity of the aminosilane products towards a silane was conducted. The reaction of PhSi(NHPrn)3 with an excess of PhSiH3 in the absence of amine was considered in order to determine a possible equilibrium and/or a tailoring approach to specific products by activation of the amine hydrogen atoms of the aminosilane. PhSi(NHPrn)3 reacted with an excess of PhSiH3 in the presence of [(Et2N)3U][BPh4] to give a mixture of four compounds (MM, NN, OO, PP) (Scheme 26.23). The explanation of how only four compounds were obtained may be found by consideration of the formation of all possible compounds as outlined in Scheme 26.24. These results show how a cationic organoactinide complex offered an alternative route for the dehydrogenative coupling of amines with silanes by a mechanism consisting of activation of an amido ligand by a silane, producing the aminosilane and an organometallic hydride, which was recycled by addition of amine.

26.8 INTERMOLECULAR HYDROAMINATION OF TERMINAL ALKYNES

26.8.1 Intermolecular hydroamination of terminal alkynes catalyzed by neutral organoactinide complexes: scope and mechanistic studies Catalytic C–N bond formation is a process of cardinal importance in organic chemistry, and the hydroamination of unsaturated substrates by the catalytic addition of a N–H moiety epitomizes a desirable atom‐economic transformation

2982

Homogeneous and heterogeneous catalytic processes

Scheme 26.23 Reactivity of PhSi(NHPrn)3 with an excess of PhSiH3 in the presence of [(Et2N)3U][BPh4].

with no by‐products. This reaction remains a challenge [equation (26.77)] and current catalytic research activities in this area is widespread and spans to the entire periodic table (Nobis and Driessen‐Ho¨lscher, 2001; Molander and Romero, 2002; Pohlki and Doye, 2003; Seayad et al., 2003; Trost and Tang, 2003; Utsunoyima et al., 2003). The intermolecular functionalization of olefins and alkynes with amines has been mentioned as one of the ten most important challenges in catalysis (Haggin, 1993).

Thermodynamically, the addition process of amines to alkenes is close to thermoneutral whereas the addition to alkynes is more enthalpically favored.

Scheme 26.24

Formation of compounds MM, NN, OO, and PP in the coupling of amine and silanes catalyzed by [(Et2N)3U][BPh4].

2984

Homogeneous and heterogeneous catalytic processes

Because of the mode of activation of these organoactinides, the negative entropy of the reaction thwarts the use of high temperatures. Organolanthanide complexes have been found to be extremely good catalysts for the intramolecular hydroamination/cyclization of aminoalkenes, aminoalkynes, and aminoallenes (Gagne´ et al., 1992a,b; Li and Marks, 1996; Roesky et al., 1997b; Buergstein et al., 1998; Li and Marks, 1998; Arredondo et al., 1999a,b; Molander and Dowdy, 1999; Tian et al., 1999; Ryu et al., 2001; Douglass et al., 2002; Hong and Marks, 2002; O’Shaughnessy et al., 2003), and enantioselective intramolecular amination reactions have been performed using chiral organolanthanide precatalysts (Gagne´ et al., 1992a). The organoactinide complexes (C5Me5)2AnR2 (An ¼ Th, U, R ¼ Me, NHR0 0 R ¼ alkyl) were found to be excellent precatalysts for the intermolecular hydroamination of terminal aliphatic and aromatic alkynes in the presence of primary aliphatic amines yielding the corresponding imido compounds (Haskel et al., 1996; Straub et al., 2001). The reactivity exhibited for the uranium complexes was different, depending on the alkynes, when compared to organothorium complexes [equations (26.78) and (26.79)]. The intermolecular process [equations (26.78) and (26.79)] showed two hydroamination regioselectivities depending on the precatalyst. The intermolecular hydroamination catalyzed by the uranium compound exhibited large regioselectivity and chemoselectivity with the E‐isomer of the imine usually formed. For the thorium catalyst, the methyl alkyl‐substituted imines were obtained. In the latter case, the imines were produced in moderate yields with the concomitant formation of the alkyne gem dimer.

Intermolecular hydroamination of terminal alkynes

2985

When the alkyne reactions catalyzed by the uranium complexes were performed using the bulky tBuNH2 as the primary amine, no hydroamination products were obtained. The products observed were only the selective gem dimers corresponding to the starting alkyne. This result has indicated that with t BuNH2, the proposed active species responsible for the intermolecular hydroamination was not generated. Using this bulky amine, the observed organouranium complexes in solution were the corresponding uranium bis(acetylide) (9) and the uranium bis(amido) (12) complexes. These two compounds were found to be in rapid equilibrium with the monoamido acetylide complex (56), responsible for the oligomerization of alkynes in the presence of amines [equation (26.80)].

When comparing the hydroamination rates for a specific alkyne utilizing the various amines, the bulkier the amines, the lower the turnover frequency, and when comparing the hydroamination rates for a particular amine (MeNH2) using various alkynes, similar turnover frequencies were observed. The lack of effect on the turnover frequency suggested no steric effect of the alkynes on the hydroamination process. The intermolecular hydroamination catalyzed by the analogous organothorium complex (C5Me5)2ThMe2 exhibited similar reactivities with TMSCCH and MeNH2 or EtNH2 [equation (26.78)]. However, in the intermolecular hydroamination with nBuCCH or PhCCH and MeNH2 or EtNH2 a dramatic change in the regioselectivity was obtained, generating the unexpected imines [equation (26.79)]. For all the organoactinides, no hydroamination products were formed by using either secondary amines or internal alkynes. With secondary amines, the chemoselective alkyne dimers and in some cases trimers were obtained. The catalytic hydroamination of nBuCCH or TMSCCH with EtNH2 with either the organothorium complexes 1 or 5 gave identical results (rate, yields, stereochemistry of the products, and kinetic curves) indicating that both reactions occurred through a common active species, in a similar manner to that observed for the uranium complexes. It is interesting to point out that when the mixture of imines 57 and 58 were obtained, 57 was found to undergo a non‐ catalyzed Brook silyl rearrangement to form the corresponding enamine 59 [equation (26.81)] (Brook and Bassindale, 1980). The rearrangement followed

Homogeneous and heterogeneous catalytic processes

2986

first‐order kinetics with direct conversion of 57 to 59, leaving the concentration of 58 unaffected:

The formation of the corresponding oligomers in the hydroamination reactions catalyzed by the thorium complexes indicated that two different complexes were active in solution, possibly interconverting, resulting in two parallel processes. It was possible to discriminate between the two most probable mechanistic pathways to find the key organometallic intermediate responsible for the hydroamination process (Scheme 26.25). The first route proposed involved the insertion of an alkyne into a metal–amido bond, as found in lanthanide chemistry (Gagne´ et al., 1992a,b; Roesky et al., 1997a,b; Tian et al., 1999). The second route consisted of insertion of an alkyne into a metal–imido (M¼N) bond, as observed for early transition metal complexes (Walsh et al., 1992, 1993).

26.8.2

Kinetic studies of the hydroamination terminal alkynes with primary amines

Kinetic measurements of the hydroamination of TMSCCH with EtNH2 revealed that the reaction has a inverse first‐order dependence in amine, first‐order dependence in precatalyst, and zero‐order dependence in alkyne

Scheme 26.25 Expected pathways for the organoactinide‐catalyzed intermolecular hydroamination of primary amines with terminal alkynes.

Intermolecular hydroamination of terminal alkynes

2987

concentration. Thus, the rate law for the hydroamination of terminal alkynes promoted by organoactinides can be formulated as presented in equation (26.82). The derived DH{ and DS{ parameter values (in the range 60–120oC) (error values are in parenthesis) from a thermal Eyring analysis were 11.7(3) kcal mol–1 and –44.5(8) eu, respectively. n ¼ k½An½amine
1 ½alkyne0

ð26:82Þ

Since the approach of either alkyne or an amine to the organometallic catalyst is expected to occur in a side‐on manner in the metallocene, the lack of alkyne concentration dependence in the kinetic hydroamination rate suggested that the proposed pathway 1 (Scheme 26.25) was not a major operative route. The zero kinetic order on alkyne suggests pathway 2 (Scheme 26.25) is consistent with the high coordinative unsaturation of the imido complexes that allows a fast insertion of the different alkynes with indistinguishable rates. When bulky amines were utilized, the formation of the corresponding imido complexes was hindered due to the encumbered transition state [equation (26.83)], reaching the highest steric hindrance with tBuNH2

The different activation mode for the two organoactinides is very unusual. For both organoactinide–imido complexes, a selective metathesis with the p‐bond of the alkyne was found to exist (demonstrated by the production of hydroamination products), whereas for the thorium complex a protonolysis reaction was observed as a competing reaction. The competing reaction was found to be responsible for the selective dimerization of the terminal alkynes (Scheme 26.26). A likely scenario for the intermolecular hydroamination of terminal alkynes promoted by the organothorium complex is shown in Scheme 26.27. The first step in the catalytic cycle involved the N–H s‐bond activation of the primary amine by the starting organoactinide, yielding methane and the bisamido–amine complex (C5Me5)2Ac(NHR0 )2 ·H2NR0 6 (step 1), which was found to be in rapid equilibrium with the corresponding bis(amido) complex 5 (step 2) (Straub et al., 1996; Eisen et al., 1998) An additional starting point

2988

Homogeneous and heterogeneous catalytic processes

Scheme 26.26 Distinctive modes of activation for organoactinide–imido complexes in the presence of terminal alkynes.

involved a similar C–H activation of an alkyne with the organoactinide yielding methane and the bis(acetylide) complex 2 (step 3). This complex may react rapidly in the presence of amines either in equivalent amounts (step 4) or with an excess (step 5) yielding complexes 4 or 6, respectively. Complex 5 followed two competitive equilibrium pathways. The s‐bond metathesis with a terminal alkyne yielded complex 4 (step 6), which induced the production of selective dimers (step 13). The second pathway (step 7), as the rate‐limiting step, involves elimination of an amine molecule producing the corresponding imido complex 7. The imido complex participated in a rapid p‐bond metathesis with an incoming alkyne, yielding the metallacycle 60 (step 8). Rapid protonolytic ring opening of complex 60 by an amine yielded the actinide–enamine amido complex 61 (step 9). Complex 61 rapidly isomerized to the actinide–alkyl(imine) amido, 62, by an intramolecular 1,3 sigmatropic hydrogen shift (step 10), which upon a subsequent protonolysis by an additional amine (step 11) produced the imine and regenerates the bis(amido) complex 5.

Scheme 26.27 Proposed mechanism for the intermolecular hydroamination of terminal alkynes and primary amines promoted by neutral organoactinide complexes.

2990

Homogeneous and heterogeneous catalytic processes

The preferential formation of the E imine isomer as compared to that of the Z isomer may be explained by the steric hindrance of the amine substituents in the isomerization pathway as described in Scheme 26.28. The distinct products formed by the two organoactinide catalysts in the hydroamination reaction are a result of a stereochemical difference in the approach of the alkyne to the imido complex (Scheme 26.29). It has been proposed that the regiochemistry of the intermolecular hydroamination between U and Th is driven by the differences in their electronic configurations, rather than the difference in their thermochemistry (potentially the f2 electronic configuration of the uranium complex).

26.9 INTRAMOLECULAR HYDROAMINATION BY CONSTRAINED‐GEOMETRY ORGANOACTINIDE COMPLEXES

Recently novel types of constrained‐geometry actinide complexes were synthesized by the amine elimination syntheses using a protic ligation and the corresponding homoleptic amido‐actinide precursor (Scheme 26.30) (Stubbert et al., 2003). The equilibrium position of the elimination reaction was controlled by the dialkylamine concentration, whereas the removal of this by‐product was the key step to obtain good yields for both actinide metals (Th, U). A slight excess of the ancillary ligand was used to obtain the complexes under mild conditions in up to 77% yield. All three uranium complexes were crystallized as well as the (CGC)Th(NMe2)2 (CGC¼Me2Si(Z5‐Me4C5)‐(tBuN)). The observed trends for the Cp(centroid)– metal–nitrogen angles for the actinide complexes and their respective comparison to lanthanides are Th > U > Sm > Yb, indicating a more open coordination for the 5f elements (Tian et al., 1999; Stubbert, et al., 2003). The tert‐butylamido‐metal bond length in all the complexes was found to be larger than the corresponding metal–NR2 bond. The longer bonds are plausibly due to the lower basicity of the (Me2Si tert‐ButylN) as compared to that of the NR2 moieties. Table 26.2 shows the turnover frequency for the hydroamination/ cyclyzation of aminoalkenes and aminoalkynes. In addition, a nice comparison for the different abilities of the constrained geometry complexes with organoactinide metallocenes Cp 2 AnMe2 ðAn ¼ Th; UÞ in the hydroamination is illustrated. Kinetic studies on the hydroamination/cyclization reaction shows similar behavior as found for lanthanides. The kinetic rate law exhibits a first‐order dependence on the precatalyst and zero order on the substrate i.e. rate a [precatalyst]1[substrate]0. This result argues that the protonolysis of the precatalyst amido moieties by the substrate is rapid, and that the rate determining step of the reaction is the olefin (alkene or alkyne) insertion into the An–NHR bond. For aminoalkenes, faster reactions are observed for the organoactinide

Scheme 26.28 Formation of imines E and Z by a 1,3‐sigmatropic hydrogen shift from the two possible organoactinide complexes. The curved arrow shows the steric interaction between the amine substituents present in the top route as compared to the bottom route.

2992

Homogeneous and heterogeneous catalytic processes

Scheme 26.29 Opposite reactivity exhibited in the reaction of organoactinide–imido complexes with terminal alkynes.

Scheme 26.30

Synthetic route towards constrained geometry organoactinides.

Intramolecular hydroamination

2993

Table 26.2 Catalytic hydroamination/cyclization by various organoactinide complexes.

with a larger ionic radius, while for aminoalkynes, the faster reactions are observed for the organoactinide with the smaller ionic radius. A plausible mechanism for the hydroamination/cyclization is presented in Scheme 26.31. It can be seen that the more sterically open environment of the constrained geometry complexes induces to a greater turnover frequencies for the aminoalkene substrates by allowing a greater access to the metal center without interfering with the kinetics and the stability of the complexes. For both aminoalkene and aminoalkynes, the constrained geometry complexes react much faster than the corresponding organoactinide metallocenes.

2994

Homogeneous and heterogeneous catalytic processes

Scheme 26.31 Plausible mechanism for the intramolecular hydroamination/cyclization of aminoolefins promoted by constrained geometry organoactinide complexes.

26.10 THE CATALYTIC REDUCTION OF AZIDES AND HYDRAZINES BY HIGH‐VALENT ORGANOURANIUM COMPLEXES

U(IV) metallocene compounds frequently show reactivities comparable to lanthanide and group IV transition metal metallocenes. Common types of processes among these metals (as demonstrated above) include olefin insertion, s‐bond metathesis, and protonolysis. In contrast to the lanthanides and group IV metals, however, uranium can also access the 6þ oxidation state, giving rise to the possibility of two‐electron (4þ/6þ) redox processes. When the complexes (C5Me5)2U(¼NR)2 (R ¼ Ph, 29; R ¼ Ad ¼ 1‐adamantyl), 30; are exposed to an

The catalytic reduction of azides and hydrazines

2995

atmosphere of hydrogen, they are reduced to the corresponding bis(amide) complexes (C5Me5)2U(NHR)2 (12) (R ¼ Ph, Ad,) [equation (26.84)]. The rate of hydrogenation of complex 30 was found to be much faster than that of complex 29. When AdN3 was added to a solution of the bis(amide) 12, the bis (imido) 30 and AdNH2 were formed [equation (26.85)]. Therefore, when complex 12 (R ¼ Ad) was reacted with AdN3 under an atmosphere of dihydrogen, catalytic hydrogenation of AdN3 to AdNH2 was observed (Scheme 26.32) (Peters et al., 1999b).

N,N0 ‐diphenylhydrazine was also used as the oxidant converting (C5Me5)2UMe2 (8) to 29. This reaction was shown to occur by the protonation of the methyl groups, liberating methane. When (C5Me5)2U(¼NPh)2 was treated with an excess of N,N0 diphenylhydrazine in the absence of hydrogen, the substrate was entirely consumed, and aniline and azobenzene were observed to form in a 2:1 ratio [equation (26.86)]. This disproportionation indicated that the N,N0 ‐diphenylhydrazine functioned as both oxidant and reductant. The formation of aniline during this reaction suggested that the U(IV) bis(amide) 12 is formed and serves to reduce the hydrazine, although the only observed uranium species in solution throughout the reaction was (C5Me5)2U(¼NPh)2, indicating that the oxidation from U(IV) to U(VI) is faster than the subsequent reduction (Peters et al., 1999b).

Homogeneous and heterogeneous catalytic processes

2996

Scheme 26.32 Catalytic reduction of azides by organouranium complexes.

This reaction is favored both enthalpically and entropically. The calculated DHf for converting two molecules of N,N’‐diphenylhydrazine to two molecules of aniline and one molecule of azobenzene is –14.6 kcal/mol. Entropy considerations also qualitatively favor product formation; two molecules of starting material are converted to three molecules of product. The catalytic activity of (C5Me5)2U(¼NAd)2 (30) was also examined. The expectation was that if the mechanism of catalysis proceeds by protonation of the U(IV) bis(amide) by N,N0 ‐diphenylhydrazine, similar to the reaction of N,N0 ‐diphenylhydrazine with (C5Me5)2UMe2, initial product formation would include adamantylamine and azobenzene, with the concomitant formation of (C5Me5)2U(¼NPh)2. However upon performing that reaction, (C5Me5)2U(¼NAd)2, aniline and azobenzene were the only products observed, indicating that the imido ligands plausibly operated as sites for mediating H‐atom transfer. No reaction was observed in the stoichiometric reaction of 29 with 1‐adamantanamine ruling out the possibility of U–N bond rupture in which compound 29 is formed and undergoes subsequent rapid reaction with 1‐ adamantanamine regenerating 30 (Peters et al., 1999a,b). The catalytic transformations of substrates by two‐electron processes are a novel type of reactivity for f‐element complexes. The involvement of U(VI) species strongly argued for the requirement of f‐orbital participation. 26.11

HYDROGENATION OF OLEFINS PROMOTED BY ORGANOACTINIDE COMPLEXES

The insertion of olefinic functionalities into metal–hydride bonds is an important step in various stoichiometric and homogeneous catalytic processes. A rich and versatile chemistry of organoactinide hydride complexes has been observed

Polymerization of a‐olefins by cationic organoactinide complexes

2997

for the complexes (C5Me5)2AnR2 (An ¼ Th, U; R ¼ alkyl). The formation of the hydride complexes has been obtained by hydrogenolysis of the corresponding organoactinide hydrocarbyl bonds [equations (26.87) and (26.88)] (Fagan et al., 1981a,b; Marks, 1982, 1986a,b).

These reactions have been studied thoroughly, mechanistically following a four‐center transition state. Kinetic studies show that the reaction displays a first‐order dependence in both actinide complex and in dihydrogen (Lin and Marks, 1987, 1990). The organoactinide hydrides of the type [(C5Me5)2AnH2]2 react rapidly and quantitatively with olefins yielding the corresponding 1,2‐addition product. For example, the hydride complex [(C5Me5)2UH2]2 catalyzes the hydrogenation of 1‐hexene at 25 C and 1 atm of H2 in toluene with a turnover frequency of 63000 h–1. Scheme 26.33 shows the proposed hydrogenation mechanism of alkenes. The mechanism was derived from kinetic investigations similar to the hydrogenations promoted by the organolanthanide hydride [(C5Me5)2Lu(m‐H)]2. 26.12 POLYMERIZATION OF a‐OLEFINS BY CATIONIC ORGANOACTINIDE COMPLEXES

The synthesis of the cationic actinide complexes [(C5Me5)2ThMe][BPh4] and [(C5Me5)2ThMe][B(C6F5)4] has led to their study for the polymerization of ethylene and 1‐hexene (Yang et al., 1991). Mechanistically, the complexes (C5Me5)2AnMe2 (An ¼ Th, U) react with a strong Lewis acid, like methylalumoxane (MAO), resulting in the formation of a cationic complex of the type [(C5Me5)2AnMe]þ[MAO–Me]
. These cationic complexes insert a‐olefins many

2998

Homogeneous and heterogeneous catalytic processes

Scheme 26.33 Proposed mechanism for the catalytic hydrogenation of alkenes promoted by [(C5Me5)2UH2]2.

times before a b‐hydrogen elimination or a b‐methyl elimination occurs, producing polymers. For ethylene, high‐density polyethylene has been obtained whereas for propylene, atactic polypropylene was the product. The search for different cocatalysts (instead of MAO) has brought the development of new and versatile perfluoroaromatic boron compounds. These highly coordinative unsaturated cationic organothorium complexes have been recently prepared and found active for the polymerization of olefins [equation (26.89)] (Jia et al., 1994, 1997).

The reactivity of the organothorium complexes for the polymerization of ethylene follows the order: [(C5Me5)2ThMe][B(C6F5)4] > [(C5Me5)2ThMe]

Heterogeneous supported organoactinide complexes

2999

[B(C6F4TIPS)4] > [(C5Me5)2ThMe][B(C6F4TBS)4]; however, their activity is an order of magnitude lower that observed for the corresponding zirconium complexes.

26.13 HETEROGENEOUS SUPPORTED ORGANOACTINIDE COMPLEXES

26.13.1

Hydrogenation of arenes by supported organoactinide complexes, kinetic, and mechanistic studies

Supporting homogeneous complexes on metal oxides creates a substantial alteration in their activity as compared to that observed in solutions (Iwasawa and Gates, 1989). For early transition metals (Yermakov et al., 1981) and actinide alkyl complexes (Burwell and Marks, 1985; Finch et al., 1990; Gillespie et al., 1990; Marks, 1992) adsorbed upon metal oxide (e.g. alumina), large enhancements in the activities for catalytic hydrogenation were observed. The increase in coordinative unsaturation in metallocene organometallic‐f‐ complexes generates a remarkable increase in the reactivity of these adsorbed complexes towards polymerization and hydrogenation of simple olefins, rivaling the activity of supported rhodium (He et al., 1985; Marks, 1992), although these complexes are inefficient for the hydrogenation of arenes. Chemisorption of organoactinides involves the transfer of an alkyl group to the Al3þ (coordinatively unsaturated surfaces) sites and the formation of a ‘cation–like’ organothorium center as shown schematically in equation (26.90) (Jia et al., 1997).

To address the question of how coordinatively unsaturated an organometallic‐f‐element complex was needed for the efficient reduction of arenes, a series of complexes of the type R1 R23 ThðR1 ¼ Z5
ðCH3 Þ5 C5 ; R2 ¼ CH2 C6 H5 ; R1 ¼ R2 ¼ 1; 3; 5
ðCH3 Þ3 C6 H2 ; R1 ¼ R2 ¼ Z3
C3 H5 Þchemisorbed on highly dehydroxilated g‐alumina (DA) were prepared (Eisen and Marks, 1992a). Presumably, the adsorption of these organometallic‐f‐complexes is similar as displayed in equation (26.90), transferring an allyl group from the

3000

Homogeneous and heterogeneous catalytic processes

thorium coordination to the strong Lewis acid site at the surface [equation (26.91)].

The hydrogenation reactivity of the latter complexes towards the hydrogenation of arenes (Table 26.3) shows that faster rates of hydrogenation are observed for less sterically hindered substrates.

26.13.2

Assessment of the percentage of Th(h3‐C3H5)4/DA active sites

The percentage of supported organoactinide sites active in the olefin hydrogenation was estimated by dosing the catalyst with measured quantities of CO in a H2 stream, measuring the amount of CO adsorbed by the catalyst, and determining the effect on subsequent catalytic activity. Similar results were found for H2O/D2O, and CH3Cl poisoning experiments. The CO poisoning chemistry presumably involved migratory insertion equation (26.92) to produce surface Z2‐formyl, which may then undergo various possible subsequent reactions. Table 26.3 Product and kinetic data for the Th(
3‐C3H5)4/DA catalyzed hydrogenation of various arenesa

Heterogeneous supported organoactinide complexes

3001

Additional confirmation of the estimated number of active sites was provided by measurement of the metal–hydride content by adding aliquots of D2O, and studying the catalytic activity after each addition. This stepwise titration of active sites indicated that 8  1% of the total Th(Z3‐C3H5)4/DA sites present on the support were responsible for the majority of the catalysis [equation (26.93)].

Another additional complementary experiment for measuring the number of hydrides was undertaken by reacting the adsorbed Th(Z3‐C3H5)4/DA with hydrogen and measuring the amount of organic gas recovery from the reaction. The amount of propane per thorium was found to be only 10% of the total amount expected [equation (26.94)]. No propylene was released from the reaction, indicating that the hydrogenation of propylene was extremely fast, and indeed, the turnover frequency for the hydrogenation of propylene was measured separately to be (Nt(25oC) ¼ 25 s–1).

The number of thorium hydride sites formed was confirmed to be the same by reaction with methyl chloride and measurement of the amount of methane per Th that was evolved from the reaction [equation (26.95)].

The importance of these poisoning experiments is that they indicate that only a very small fraction of the organothorium adsorbate sites on dehydroxylated alumina were responsible for the bulk of the catalytic reactivity. It is likely that one or more different structures of the suggested ‘cation‐like’ organothorium moieties constitute the catalytic sites on alumina, but the exact structural characteristics defining these structures remain to be elucidated.

3002

Homogeneous and heterogeneous catalytic processes

For arene hydrogenation, the kinetic data can be accommodated by three repetitions of a two‐step sequence: (i) arene insertion (olefin insertion for the subsequent step) into a Th–H bond; (ii) hydrogenolysis of the resulting Th–alkyl bond. The kinetic data measured for benzene conforms to the rate law Nt ¼ k [benzene]0[pH2]1[Th]1 (Th ¼ tetraallyl complex). The kinetic isotope measurements for the hydrogenation of benzene indicated Nt(H2)/Nt(D2) ¼ 3.5  0.3 at 90 C and 180 psi of H2. In the hydrogenation reaction of benzene with D2, the product C6H6D6 was obtained as a mixture of two geometric isomers as refers to the disposition of the deuterium atoms: all cis and cis, cis, trans, cis, trans in a ratio of 1:3 respectively. The Arrhenius activation energies for the catalytic hydrogenation of benzene was measured to be 16.7  0.3 kcal mol–1 and the corresponding thermodynamic activation parameters were DH{ ¼ 16.0  0.3 kcal/mol and DS{ ¼ 32.3  0.6 eu (Eisen and Marks, 1992). The mechanism proposed for the hydrogenation of arenes is described in Scheme 26.34. The process takes into account the lack of facial selectivity by which the ratio 1:3 among the geometrical isomers were formed. As a function of substrate, the relative rates of Th(Z3‐C3H5)4/DA‐catalyzed hydrogenation of arenes was found to be in the order benzene > toluene > p‐xylene > naphthalene. In the hydrogenation of benzene no H/D scrambling is observed during the process but H/D scrambling is observed after complete hydrogenation of the starting material. In the reaction between toluene‐d8 and H2 or toluene and D2 significant C–H/C–D exchange at the benzylic positions was observed during the hydrogenation. Significant incorporation of deuterium atoms into the starting toluene and subsequently into the cyclohexane product was observed at partial conversions. The C–H/C–D exchange was suggested to occur through a benzylic activation as shown in equation (26.96).

Competition experiments confirmed the large kinetic discrimination for the different arenes. The hydrogenation reaction of equimolar quantities of p‐xylene and benzene yielded cyclohexane with almost complete selectivity (97%) and a mixture of 3:1 cis:trans 1,4‐dimethylcyclohexane (3%). 26.13.3

Facile and selective alkane activation by supported tetraallylthorium

C–H activation processes involving alkanes are considered high‐energy demanding transformations. Although significant advances have been made in the functionalization of C–H bonds by f‐ and early transition complexes (Shilov, 1984; Gillespie et al., 1990; Ryabov, 1990; Watson, 1990; Basset et al., 1998;

Heterogeneous supported organoactinide complexes

3003

Scheme 26.34 Proposed mechanism for the hydrogenation of arenes by cationic supported organoactinide complexes.

Schneider et al., 2001), the catalytic intermolecular activation of inert alkane molecules with favorable rates and selectivities is still a major challenge. As noted above, studies on benzene reduction with D2 revealed C–H/C–D exchange in the cyclohexane product only after benzene conversion was complete. This observation prompted detailed studies of the activation of hydrocarbons. The results from slurry reaction studies of C–H/C–D exchange for a variety of alkanes catalyzed by thorium tetraallyl complex/DA under a D2 atmosphere are summarized in Table 26.4 (Eisen and Marks, 1992b). Rapid C–H/C–D exchange was promoted by the tetraallyl complex/DA, with turnover frequencies comparable to or exceeding those of conventional group 9 heterogeneous alkane activation catalysts (Butt and Burwell, 1992). C–H functionalization occurred with substantial selectivity and in an order which does not parallel the C–H bond dissociation energies: primary > secondary > tertiary,

3004

Homogeneous and heterogeneous catalytic processes

Table 26.4 Kinetic and product structure/deuterium distribution data for Th(
3‐C3H5)4/ DA catalyzed C–H/C–D fuctionalization.

and sterically less hindered > sterically more hindered. NMR and GC‐MS measurements as a function of conversion indicated single C‐H exchanges, with no evidence for multiple exchange processes (e.g. non‐statistical amounts of RD2 species). Unexpectedly, the CH/CD exchange reaction of cis‐dimethylcyclohexanes produced isomerization towards a cis–trans mixture. Based on the same two reasonable assumptions as for the arene hydrogenation, a plausible mechanistic scenario for the activation and isomerization of alkanes was proposed and summarized in Scheme 26.35. The mechanistic sequence invokes presumably endothermic Th–C bond formation and HD elimination via a ‘four‐ center’, heterolytic ‘s‐bond metathesis’ (step 1), followed by deuterolysis

Heterogeneous supported organoactinide complexes

3005

(step 2). Cycloalkane skeletal isomerization would then occur via a b‐H elimination (step 3) and re‐addition of the Thþ–H to the opposite face of the double bond (step 4). This process would involve the rapid dissociation and re‐ addition of the alkene, although other mechanisms have been proposed as conceivable. Insertion (step 5) and deuterolysis (step 6) produced the isomerized cycloalkane. The isotopic labeling experiments revealed little D incorporation at the dimethylcyclohexane tertiary carbon centers and negligible differences in the D label distribution of the isomerized and un‐isomerized hydrocarbons. These results indicated that the ancillary ligands L and L0 in Scheme 26.35 are either non‐D in identity (e.g. Z3‐allyl or oxide), or that such Th–D functionalities were chemically and stereochemically inequivalent to that formed in a b‐H abstraction, since they do not compete for olefin addition.

Scheme 26.35 Proposed scenario for the Th(
3‐allyl )4/DA‐catalyzed C–H activation and isomerization of alkanes.

3006

Homogeneous and heterogeneous catalytic processes

In summary, these results demonstrate that supported organo‐f‐complexes are extremely active catalysts for a number of high‐energy organic chemistry transformations.

ACKNOWLEDGMENTS

C. J. B. gratefully acknowledges support at LANL by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. M. S. E. thanks the Fund for the Promotion of Research at The Technion. REFERENCES Aitken, C., Barry, J. P., Gauvin, F. G., Harrod, J. F., Malek, A., and Rousseau, D. (1989) Organometallics, 8, 1732–6. Anwander, R. (1996) in Applied Homogeneous Catalysis with Organometallic Compounds, vol. 2 (eds. B. Cornils and W. A. Herrmann) VCH Publishers, New York. Anwander, R. and Herrman, W. A. (1996) Top. Curr. Chem., 179, 1–32. Apeloig, Y. (1989) in The Chemistry of Organic Silicon Compounds (eds. S. Patai and Z. Rappoport), Wiley‐Interscience, New York, pp. 57––225. Arney, D. S. J., Burns, C. J., and Smith, D. C. (1992) J. Am. Chem. Soc., 114, 10068–9. Arney, D. S. J. and Burns, C. J. (1993) J. Am. Chem. Soc., 115, 9840–1. Arney, D. S. J. and Burns, C. J. (1995) J. Am. Chem. Soc., 117, 9448–60. Arredondo, V. M., Tian, S., McDonald, F. E., and Marks, T. J. (1999a) J. Am. Chem. Soc., 121, 3633–9. Arredondo, V. M., McDonald, F. E., and Marks, T. J. (1999b) Organometallics, 18, 1949–60. Asao, N., Sudo, T., and Yamamoto, Y. (1996) J. Org. Chem., 61, 7654–5. Bajgur, C. S., Tikkanen, W. R., and Petersen, J. L. (1985) Inorg. Chem., 24, 2539–46. Baranger, A. M., Walsh, P. J., and Bergman, R. G. (1993) J. Am. Chem. Soc., 115, 2753–63. Basset, J. M., Lefebvre, F., and Santini, C. (1998) Coord. Chem. Rev., 178–180, 1703–23. Berthet, J. C., Boisson, C., Lance, M., Vigner, J., Nierlich, M., and Ephritikhine, M. (1995) J. Chem. Soc., Dalton Trans., 3019–25. Berthet, J. C. and Ephritikhine, M. (1998) Coord. Chem. Rev., 178–180, 83–116. Biran, C., Blum, Y. D., Glaser, R., Tse, D. S., Youngdahl, K. A., and Laine, R. M. (1988) J. Mol. Catal., 48, 183–97. Blake, P. C., Edelman, M. A., Hitchcock, P. B., Hu, J., Lappert, M. F., Tian, S., Mu¨ller, G., Atwood, J. L., and Zhang, H. (1998) J. Organomet. Chem., 551, 261–70. Blum, Y. and Laine, R. M. (1986) Organometallics, 5, 2081–6. Bode, B. M., Day, P. N., and Gordon, M. S. (1998) J. Am. Chem. Soc., 120, 1552–5. Brennan, J. G. and Andersen, R. A. (1985) J. Am. Chem. Soc., 107, 514–16. Brook, A. G. and Bassindale, A. R. (1980) in Rearrangements in Ground and Excited States, vol. 2, Academic Press, New York.

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Schumann, H., Keitsch, M. R., Demtschuk, J., and Molander, G. A. (1999) J. Organomet. Chem., 582, 70–82. Seayad, A. M., Selvakumar, K., Ahmed, M., and Beller, M. (2003) Tetrahedron Lett., 44, 1679–83. Seitz, F. and Wrighton, M. S. (1988) Angew. Chem., Int. Edn. Engl., 27, 289–91. Selin, T. J. and West, R. (1962) J. Am. Chem. Soc., 84, 1860–3. Shannon, R. D. (1976) Acta Crystallogr., A32, 751–67. Shen, Q., Zheng, D., Lin, L., and Lin, Y. (1990) J. Organomet. Chem., 391, 307–12. Shilov, A. E. (1984) Activation of Saturated Hydrocarbons by Transition Metal Complexes, Reidel, Hingham, MA. Smith, G. M., Carpenter, J. D., and Marks, T. J. (1986a) J. Am. Chem. Soc., 108, 6805–7. Smith, G. M., Susuki, H., Sonnenberg, D. C., Day, V. W., and Marks, T. J. (1986b) Organometallics, 5, 549–61. Straub, T., Haskel, A., and Eisen, M. S. (1995) J. Am. Chem. Soc., 117, 6364–5. Straub, T. R. G., Frank, W., and Eisen, M. S. (1996) J. Chem. Soc., Dalton Trans., 2541–6. Straub, T., Haskel, A., Dash, A. K., and Eisen, M. S. (1999) J. Am. Chem. Soc., 121, 3014–24. Straub, T., Haskel, A., Neyroud, T. G., Kapon, M., Botoshansky, M., and Eisen, M. S. (2001) Organometallics, 20, 5017–35. Stubbert, B. D., and Stern, C. L., Marks, T. J. (2003) Organometallics, 22, 4836–8. Sudo, T., Asao, N., Gevorgyan, V., and Yamamoto, Y. (1999) J. Org. Chem., 64, 2494–9. Takeuchi, R. and Tanouchi, N. (1994) J. Chem. Soc., Perkin Trans. 1, 2909–13. Takeuchi, R. and Yasue, H. (1996) Organometallics, 15, 2098–102. Tanke, R. S. and Crabtree, R. H. (1991) Organometallics, 10, 415–18. Tian, S., Arredondo, V. M., Stern, C. L., and Marks, T. J. (1999) Organometallics, 18, 2568–70. Tilley, T. D. (1993) Acc. Chem. Res., 26, 22–9. Trost, B. M. and Tang, W. J. (2003) J. Am. Chem. Soc., 125, 8744–5. Utsonomiya, M., Kuwano, R., Kawatsura, M., and Hartwig, J. F. (2003) J. Am. Chem. Soc., 125, 5608–9. Walsh, P. J., Baranger, A. M., and Bergman, R. G. (1992) J. Am. Chem. Soc., 114, 1708–19. Walsh, P. J., Hollander, F. J., and Bergman, R. G. (1993) Organometallics, 12, 3705–23. Wang, W. D. and Eisenberg, R. (1991) Organometallics, 10, 2222–7. Wang, J. Q., Dash, A. K., Berthet, J. C., Ephritikhine, M., and Eisen, M. S. (1999) Organometallics, 18, 2407–9. Wang, J. X., Dash, A. K., Berthet, J. C., Ephritikhine, M., and Eisen, M. S. (2000) J. Organomet. Chem., 610, 49–57. Wang, J., Dash, A. K., Kapon, M., Berthet, J. C., Ephritikhine, M., and Eisen, M. S. (2002a) Chem. Eur. J., 8, 5384–96. Wang, J., Kapon, M., Berthet, J. C., Ephritikhine, M., and Eisen, M. S. (2002b) Inorg. Chim. Acta, 344, 183–92. Wang, J. Q. and Eisen, M. S. (2003) unpublished results. Warner, B. P., Scott, B. L., and Burns, C. J. (1998) Angew. Chem., Int. Edn. Engl., 37, 959–60.

3012

Homogeneous and heterogeneous catalytic processes

Watson, P. L. and Parshall, G. W. (1985) Acc. Chem. Res., 18, 51–6. Watson, P. L. (1990) in Selective Hydrocarbon Activation (eds. J. A. Davies, P. L. Watson, J. F. Liebman, and A. Greenberg), VCH, New York, ch. 4. Weber, W. P. (1983) Silicon Reagents for Organic Synthesis, Springer‐Verlag, Berlin. Xing‐Fu, L., Xi‐Zhang, F., Ying‐Ting, X., Hai‐Tung, W., Jie, S., Li, L., and Peng‐Nian, S. (1986a) Inorg. Chim. Acta, 116, 85–93. Xing‐Fu, L., Ying‐Ting, X., Xi‐Zhang, F., and Peng‐Nian, S. (1986b) Inorg. Chim. Acta, 116, 75–83. Xing‐Fu, L. and Ao‐Ling, G. (1987) Inorg. Chim. Acta, 134, 143–53. Yang, X., Stern, C. L., and Marks, T. J. (1991) Organometallics, 10, 840–2. Yermakov, Y. I., Kuznetsov, B. N., and Zakharov, V. A. (1981) Catalysis by Supported Complexes, Elsevier, Amsterdam. Zalkin, A., Edwards, P. G., Zhang, D., and Andersen, R. A. (1986) Acta Crystallogr., C42, 1480–2.

CHAPTER TWENTY SEVEN

IDENTIFICATION AND SPECIATION OF ACTINIDES IN THE ENVIRONMENT Claude Degueldre 27.1 27.2 27.3

27.4

Combining and comparing analytical techniques 3065 27.5 Concluding remarks 3072 Glossary 3073 References 3075

Background 3013 Sampling, handling, treatment, and separation 3021 Identification and speciation 3025

27.1 BACKGROUND

All actinide isotopes are radioactive. Since the middle of the last century, new actinide and transactinide isotopes have been artificially produced and the use of several of the naturally occurring actinide isotopes has increased. This production is due to the nuclear power industry and the military fabrication and use of nuclear weapons. These activities have created anxiety about the introduction of actinide elements into the environment. Consequently, environmental systems that contain or are exploited for natural actinides, or, are potentially contaminated by anthropogenic actinides, must be investigated. The analytical techniques introduced in this chapter are used, after sampling when required, to identify and quantify the actinide isotopes and to determine the species in which they are present. The amounts or concentrations of actinide elements or isotopes in the environmental samples need to be identified and quantified. Moreover, since transport properties and bioavailability are closely linked to species and atomic environment of the actinide elements, both radiotoxicity and speciation of actinides in the studied phases must be determined to understand the behavior of these elements in the environment (Livens, 2001). In this chapter, analysis of a broad range of environmental systems are considered such as fluid phases from air or waters from surface to subsurface, samples from terrestrial 3013

3014

Identification and speciation of actinides in the environment

to oceanic, and samples from rocks to organic or bio‐related phases. These samples range from depleted to rich in actinides and from inorganic to organic or bioorganic. The actinides are either dissolved in solid or liquid solutions, or associated with particles dispersed in the sample phase: in air or water, or in heterogeneous solids. Actinide species may also be located at phase boundaries such as rock–water or dispersed in vivo, associated with biofunctional environments. The phases of interest range from the nanometer to the kilometer in size, in surface or in volume. In all cases, accurate or quantifiable sampling is required, together with identification, quantification, and determination of the redox states or of the complexes in the phases or at the interfaces, as well as characterization of the molecular environment, or emphasis on the crystalline or the amorphous phases that contain actinide isotopes, elements, or species. This information is required to understand how actinide species will behave in the environment and the way in which actinides can migrate or be retained. However, contamination may concentrate via bioaccumulation mechanisms (Holm and Fukai, 1986; Skwarzec et al., 2001) or a geochemical process specific to a local hydrogeochemical environment (Bundt et al., 2000). Spatial information is needed, ranging from the subnanometer to the micrometer size to understand migration behavior from the microscopic to the geographic scale, and temporal information is needed, ranging from second fractions to millions of years. Figure 27.1 schematizes the source, location, or occurrence of natural actinides and of present or potential contamination including man‐made actinide elements in the environment. The actinide elements and isotopes considered are the natural ones, with Th and U (primordial nuclides formed in the buildup of the terrestrial matter and still present today) being the major elements at the 1013 ton level in the Earth’s crust (Wasserburg et al., 1964) and with Ac and Pa being the trace elements formed by decay of the major natural actinide isotopes. Naturally occurring Np and Pu are present at the ultratrace level generated by nuclear reactions in the environment, and are also residual traces of primordial actinides, or produced man‐made, as discussed below. Natural actinide isotopes are present in rocks or minerals, e.g. phosphates containing uranium or thorium (232Th and 235U, 238U) (Heier and Rogers, 1963; Khater et al., 2001). The minor components (227Ac, 228Ac, 227Th, 228Th, 230Th, 231 Th, 234Th, 231Pa, 234mPa, 234U) are produced by decay of the major actinide isotopes (e.g. Murray et al., 1987; Arslanov et al., 1989). Natural 236U has been detected at an atomic ratio, 236U/238U, of 6 10–10 in uranium deposits such as at the Cigar Lake, Saskatchewan, Canada (Zhao et al., 1994). It may be generated by neutron capture on 235U. Similarly, a long‐lived actinide such as 237 Np was found in ultratrace levels (237Np/238U: 2 10–12) in uranium ores from Katanga (Myers and Lindner, 1971). Ultratrace components such as 239Np or 239Pu are also generated by neutron capture (Curtis et al., 1987; Barth et al., 1994), with typical concentrations in the order of 10–12 g Pu per gram sample

Fig. 27.1 Natural and anthropogenic actinide species in the environment. (1) Natural major actinides, (2) minor actinides, (3) actinides at the ultratrace level generated from the majors by neutron capture in environment, (4) actinides of primordial origin, (5) natural actinide contamination around uranium mining and milling plants. Anthropogenic actinides: (6) released intentionally below legal norms from nuclear power plants, (7) by accident, or (8) reprocessing facilities. Actinides released from military activities, e.g. weapons production: (9) atmospheric tests, (10) underground detonations, or (11) objects from nuclear naval vessels, or (12) depleted uranium warheads. Waste management activities: (13) intermediate or (14) geologic and (15) oceanic disposal. Unexpected events from nuclear power sources, e.g. (16) satellite reentry in atmosphere, (17) nuclear icebreaker, or (18) nuclear submarine sinking; ‘part’ stands for colloidal particles.

3016

Identification and speciation of actinides in the environment

in pitchblende, 10–14 g Pu per gram U ore, and maximum concentrations in the order of 5 10–15 g Pu per gram lava (Hawaiian), 10–15 to 3 10—17 g Pu per gram granite (Kontinentales Tiefbohrprogramm). 244Pu, which was found in a rare earth mineral to the extent of 1 part per 1018, is likely to have been produced during Earth formation (Hoffman et al., 1971). As identification techniques become increasingly sensitive, it may be possible that specific isotopes such as heavy curium isotopes may be found at the ultratrace level as natural components as it was targeted in a study about supernova producing long‐living radionuclides in terrestrial archives (Wallner et al., 2000). The specific case of the natural fossil reactors in the Oklo region (e.g. Oklo, Oklobonde, Bagombe), which underwent spontaneous chain neutronic reaction some 2 109 years ago, was studied extensively and revealed the buildup of large quantities of transuranium elements during chain reactions. However, most of them have now decayed. Natural plutonium has been produced and has remained in the environment even before it was produced artificially. It remains the heaviest natural element found in the environment at the level of milligrams per 100 tons of uranium ore residues (Peppard et al., 1951). Artificial or anthropogenic actinides are those generated by civilian and military activities. Actinide isotopes that have been artificially produced in significant amounts are 233Pa, 233U, 236U, 237Np, 238Pu, 239Pu, 240Pu, 241Pu, 242 Pu, 241Am, 243Am, 242Cm, 243Cm, and 244Cm (Mitchell et al., 1995b; Lujaniene et al., 1999), with about 2000 tons Pu produced until now, which some groups would like to reuse in a very pragmatic way (Degueldre and Paratte, 1999). The amount of artificially produced actinides is larger than that occurring naturally. Actinide isotopes such as 239Np and 239Pu belong to both classes and are qualified as natural or anthropogenic according to their origin. Recently, attention has also been drawn to depleted uranium and its use in projectiles. Its dispersal in the environment has been the subject of investigations with regard to its toxic potential. Natural processes typically disperse, transport, and dilute contaminants. Some local geophysical, hydrochemical, or bioorganic processes can concentrate them. Usually, however, atmospheric flow transports particulate contaminants through the atmosphere or the stratosphere. Water flows allow contaminants to migrate to the geosphere or at its surface. In these systems, naturally occurring actinides may be used as tracers to estimate element residence time in particulate form in air or in water systems. For example, 234 Th is used as a natural marker to study particles in Lake Michigan (Nelson and Metta, 1983) or Lake Geneva (Dominik et al., 1989). Similarly, Th isotopes may be used to investigate their scavenging by colloidal mechanisms in seawater (Baskaran et al., 1992). Similar studies may be applied to study actinides in particulate phases, or aerosols, in the atmosphere (Salbu, 2001). The naturally occurring actinides U and Th, as well as Ra, may be utilized in studies of paleoclimate, dating old groundwaters, rock–water interaction processes (Ivanovich, 1994), and geochronology systems (Balescu et al., 1997), using

Background 234

3017

U/238U or 230Th/234U ratios. Anthropogenic actinides may also be used as markers; for example, the use of 239þ240Pu to replace 137Cs as an erosion tracer in agricultural landscapes contaminated with the Chernobyl fallout (Schimmack et al., 2001) was recently suggested. Actinides from human activities have also been occasionally released into the environment. The potential of contamination begins at the uranium mine with tailings and the problems associated with, for example, the release of U and Th, and their daughter products (e.g. Winkelmann et al., 2001); hazards continue all along the nuclear fuel cycle with research, commercial, or military activities and the potential for real spread and contaminations of the environment, as for example, the Irish Sea, Semipalatinsk, and Maralinga (Kim et al., 1992; Cooper et al., 1994; Kazachevskiy et al., 1998), due to commercial or military activities or accidental events. Actinides may be dispersed, at restricted levels and below legal limits, from electric power utilities during operations (Ma´tel et al., 1993), or may be instantaneously dispersed in large doses, for example, as a consequence of an accident involving a reactor (Holm et al., 1992), an aircraft carrying nuclear weapons (Mitchell et al., 1995a; Rubio Montero and Martin Sa´nchez, 2001a,b), or during nuclear bomb testing (Wolf et al., 1997; Kudo, 1998). These actinide releases contaminate the environment, such as desert (Church et al., 2000) or forest soil, but contaminate flora specimens such as mushrooms insignificantly (Mietelski et al., 1993). However, diluted in water, actinides undergo bioaccumulation, e.g. in a marine environment (Baxter et al., 1995), within phytoplankton and macro algae (Holm and Fukai, 1986), crustacean (Swift and Nicholson, 2001a,b), and fish (Skwarzec et al., 2001). The reentry of a satellite equipped with a 238Pu power source in the atmosphere and its disintegration through the stratosphere has been a source of contamination. In the ocean the leakage of objects from naval reactor pressure vessels in submarines (Mount et al., 1995) or waste dumping on the seabed (Rastogi and Sjoeblom, 1999) are also potential sources of actinide contamination. In the geosphere, contaminants may affect the saturated or the unsaturated zones (Penrose et al., 1990). All these cases schematized in Fig. 27.1 depict situations for which actinides are present as a main or a diluted phase. They also may be in a ‘dissolved’ state or present as colloidal particles in the liquid or gas environment. Consequently, the analytical techniques used range from major component quantitative analysis to detection at the ultratrace level. The analytical methods used to identify and characterize, i.e. provide speciation information for the actinides, must be efficient, accurate, very sensitive, and able to provide information on the chemical characterization of the environment of the actinide. This allows the reconstruction of the history of the actinide‐loaded phases and consequently the prediction of actinide behavior in the environment to be made. For example, an oxide phase produced at low temperature will dissolve faster in water than a high‐temperature oxide phase. Size distribution of these particles is a relevant parameter to estimate dissolution or transport behavior.

3018

Identification and speciation of actinides in the environment

Before analysis, sampling and/or sample treatment, with separation if needed, must be utilized when the analytical technique is not applied in situ.The investigated analytical techniques are classified according to the interaction (if any) between irradiation particles or reagent and the analyzed sample, and for the signal detected or recorded (see Table 27.1). For passive techniques, excitations are absent. For interactive techniques, irradiations or reagent additions are made with phonons, photons, electrons, neutrons, or ions with a known energy, flux, chemical affinity, or mass. The irradiation or injection is done locally while the reception may be carried out in a given space at a given angle from the stimuli direction or the incident beam, instantaneously or after a certain time after irradiation. The detection tools are spectroscopy (S), microscopy (M), or radiography (RAD) instruments. The reaction takes place within or without a specific field such as electrical and magnetic flow or mechanical acceleration. The detected signal may be the same in nature as the incident one, with the same energy, or a signal with lower energy, with particles being phonons, photons, electrons, neutrons, or ions. In addition to these analytical tools or techniques, neutral species such as atoms or molecules may also be used to interrogate the material. They are treated in this chapter as ions (from a mass point of view). The techniques are classified according to increasing energy of reagents or incident particles. The combination of all excitation or reagent addition and reception or product detections makes the analytic potential very rich for identification of elements or isotopes, quantitative determination, and spatial speciation in a broad way. The sensitivity k (units of M·au–1, with M: mol·L–1, and au: arbitrary unit), and detection limit DL of the concentration C(M) of isotope, element, or species, or their amount N(mol) must be discussed at both theoretical and experimental levels. From the experimental side these concentration and amount limits are given by: CDL ¼ 3 ð27:1Þ NDL ¼ Vmin CDL

ð27:2Þ

where s(au) is the standard deviation of the limiting noise and Vmin(L) is the minimum volume that can be analyzed (e.g. 1 mL). From the theoretical side, a detection limit may be evaluated from the physical–chemical process and from the performance of the analytical unit, while it remains usually an experimental limit. For all analyses, sample volume, mass, or amount, the flux of the reagent, the size of the analyzed part of the sample, and the acquisition time or time of analysis are key parameters linked to the detection limit. The nature and origin of the environmental sample dictate the size of the sample. However, the size of the sample is also coupled with the analytical technique for which time and detection limits (DLs) are key parameters for its application. DL is a function of the number

Table 27.1 Analytical techniques including excitation (if any) and detection for isotope, element, or species characterization (see list of abbreviations in the glossary). Note: excitation or detection is performed with phonons, photons, electrons, neutrons, ions (or atoms or molecules) considering the particles ( plain, solvated, or cluster) or their associated waves.

3020

Identification and speciation of actinides in the environment

of actinide atoms, the volume of the sample, the subsample excitation conditions (see Section 27.2), and the acquisition quality of the detector, and interferences such as quenching or peak overlapping. It may, however, be desirable to split the speciation range according to ‘macro concentration’ > 10–6 M > ‘trace concentration’. Analysis may be performed in‐line, on‐line, on a flow bypass with direct detection of activity, for example, or at‐line with intermediate samples, or off‐line with the transfer of the sample in the laboratory. The analysis may be carried out in situ, for example using an atmospheric balloon, or in an underground rock laboratory in the considered phase, or ex situ with transfer of the sample and separation. To complete the picture it must be mentioned that separation techniques such as filtration, centrifugation, diffusion, electrodiffusion, electroplating, partitioning (liquid–liquid or solid–liquid) may also be applied, making the analysis more specific or efficient. Information required such as activity (chemical, radioisotopic), amount (mass), concentration (fraction), and structures of the actinides in the studied phases have to be determined at the nuclear (pm), atomic, molecular (nm), microscopic (mm), macroscopic structural (mm), bulk scale (cm), at the component or system scale (m), or at environmental or geographic scale (km) according to the requirements of the study. Identification concerns the actinide elements and isotopes, but speciation may be understood not only at the molecular scale but also in a broader sense such as at the environmental scale. Understanding in the macroscopic scale by plain washing, leaching, or extraction tests would be a step for remediation investigations. In many types of soil the mitigation approach could be some type of soil washing to remove selectively the contaminating species (Burnett et al., 1995). The selective extraction tests are also discussed in this chapter; the phases are, however, analyzed using the techniques discussed below. Passive and active analytical methods will be reviewed (Table 27.1) through Sections 27.2 and 27.3, with examples of their utilization in transmission, injection diffusion, or reflective modes. The sampling area, beam size, and reagent quantities are macroscopic, microscopic, or nanoscopic in nature, while spatial–temporal conditions make excitation vs detection direction through solid angle, with synchronous detection or with temporal delay, possible. In Section 27.4, combinations of techniques are discussed. For example, seismic reflection (SR), which cannot be used by itself for identifying thorium or uranium, can be used in combination with other techniques as a prospecting tool. Atomic force microscopy (AFM) morphological studies also provide useful information; however, they must be complemented with other technique results to provide the required identification result (e.g. Walther, 2003). Similarly, Eh electrode (EHE) measurements may contribute to the speciation of redox‐sensitive actinides such as U, Np, or Pu in waters. They are, however, generally completed by spectroscopic investigations. Chromatography, which is basically a separation technique, must be combined with detectors and is also studied in this chapter.

Sampling, handling, treatment, and separation

3021

Separation of elements of interest, which are later analyzed by different analytical techniques, is an important prerequisite of any analytical method, as discussed in Section 27.2. The analytical procedure typically includes sampling or sample preparation (e.g. decomposition), separation, and/or enrichment before analysis in either a passive or an interactive way.

27.2 SAMPLING, HANDLING, TREATMENT, AND SEPARATION

In environmental systems, actinides may sometimes be analyzed on site. This requires a probe or detector installation in situ and direct detection or measurement of actinide concentration, activity, or amount. This is an ideal case. Because of interferences, low levels of concentrations, or difficulties in transporting the analytical unit, sampling is generally the best solution, with transfer of samples or subsamples to the laboratory for further analysis. The sampling and sample handling are performed taking into account (Salbu, 2000): representative samples and fractionation of samples, treatment in situ, at‐site, or shortly after sampling, and dilution or pre‐concentration, and chemical yield (efficiency of handling).

Sampling, pretreatment, shipment to laboratory, and analysis are areas where contaminations, losses, or speciation changes can occur (Harvey et al., 1987). Corrections for these artifacts must be applied by using isotopic tracers or specific handling conditions.

27.2.1

Sample and data collection of compounds

The two main strategies are either to make measurements on site without sampling and adapting the probe in situ or to collect samples and then perform the analysis ex situ, as discussed below. Sample amounts and collection techniques are dependent on the nature of the sample and on its actinide content. Samples with high actinide contents do not generally need enrichment phases, while very dilute actinide samples may require treatment, enrichment, and other time‐consuming protocols. The strategy may be very different for fluids (such as air or water) than for solids (such as rock or biospecimen). In air samples, actinides are usually present as liquid aerosols or particles since their partial pressure as gaseous species is insignificant. A particulate phase must be characterized in terms of size distribution and nature, because its behavior in the environment may be function of production mode and history, which have a direct impact on composition, nature, specific size distribution, and actinide‐release properties.

3022

Identification and speciation of actinides in the environment

In water samples, the actinides may be present as truly dissolved species, as separate particulate, and/or as colloidal phases. Here again the particle structure and size distribution must be determined to understand the actinide migration potential. In solid samples, actinides are either present as constituents of solid solutions or as phases that are heterogeneously dispersed within the matrix phases. This is also valid for biospecimens. The sample in all cases must be preserved from degradation, contamination, or other physicochemical changes. Specific protocols such as collection under a controlled atmosphere, a preservative reagent, and storage in the dark and at a reduced temperature may be required. The larger the sample volume and the corresponding contact area of the vessel, the smaller will be the loss by sorption on the vessel wall and the shorter the storage time, and the less will be degradation of the sample by contamination or particle aggregation. As an example, typical air sample volumes range over several hundred meters (Iwatschenko‐Borho et al., 1992). Rainwaters, for example, require collectors of 1 m2 active surface, and water samples of the order of 100 L (Rubio Montero and Martin Sa´nchez, 2001b). Analysis of river water may also require some 100 L (Garcia et al., 1996) for Pu and Am determination. Seawater sampling also requires very large volumes, processed up to 6000 L (Livingston and Cochran, 1987; Robertson, 1985), in order to achieve concentration measurements of trace level of Th, Pu, and Am isotopes. Rock samples may be as large as the 100 kg amount that was required for the detection of 244Pu (Hoffmann et al., 1971) in nature. 27.2.2

Sample treatment and separation

Sample preparation and separation of ions or other species of interest, which are later analyzed by different analytical techniques, are usually important prerequisite steps of any analytical method. Radiotracer techniques may be applied for each step of the separation: sample decomposition, trace–matrix separation (precipitation, ion exchanger, solvent extraction), volatilization, and other treatment without any restriction on the chemical and physical forms of sample. All these techniques may be quantitatively applied using isotope dilution, e.g. with 235Np, 236Pu (Bellido et al., 1994), or 244Pu spikes according to the specific requirements. Air samples are generally treated in a way such that their particulate content may be collected on filters or impactors (Iwatschenko‐Borho et al., 1992). Aerosol analysis generally requires treatment of a very large volume of air. Aqueous solutions are generally filtered, typically through a 0.45 mm pore membrane, followed by a series of ultrafiltration (Orlandi et al., 1990; Francis et al., 1998) or centrifugation (Kim et al., 1997; Dominik et al., 1989; Itagaki et al., 1991) steps. Centrifugation requires larger instrumentation compared to filtration. This limits the use of centrifugation on site and

Sampling, handling, treatment, and separation

3023

furthermore in situ. The two new samples produced are: (1) single particle or colloid cake on the collector surface, or colloid concentrate; and (2) the filtered liquid phase with its soluble content. Treatments of restricted volumes of water are required, depending on the level of contamination of the water. For example, observation of chemical speciation of plutonium was carried out after filtration of Irish Sea and western Mediterranean Sea waters (Mitchell et al., 1995). The redox state distribution of 239,240Pu and 238Pu in these waters shows little variation with 87% as Pu(V). Pu(IV) is mostly associated with particles. In situ dialysis has also been applied to concentrate the colloid phase associated with actinides. Extraction of an actinide from the particulate phase or from a rock sample may be carried out by applying a successive leaching technique (e.g. Szabo´ et al., 1997; Nagao et al., 1999), with reagents successively more and more aggressive such as, for example, the following: 1. water at 25 C to desorb exchangeable actinides; 2. sodium acetate at pH 5 and 25 C to dissolve carbonate phases; 3. ammonium oxalate at pH 3 and 25 C to separate reducible phases, i.e. (Fe, Mn); 4. sodium hydroxide 0.3 M at 60 C to leach actinide associated with organics; 5. hydrogen peroxide at pH 1 and 60 C to dissolve sulfide phases; 6. nitric acid 8 M at 80 C to leach mineralized phases including actinide oxides. Each step must be characterized by a reagent, a pH value, a temperature, a sample/reagent volume or mass ratio, and a given time. Each extraction step may be repeated several times before the next extraction step in order to follow the reversibility of the desorption or leaching process (Salbu, 2000). Sequential leaching has been applied to perform speciation of uranium associated with particulates in seawater (Hirose, 1994). The major species consists of an insoluble complex that dissolves by leach test at pH 1. Co‐precipitation is usually applied as an enrichment technique of an actinide from an aqueous solution with Fe(OH)3 (Morello et al., 1986), LaF3 (Nelson and Lovett, 1978), or Ba(SO4) for Ac assay on Ra (Niese, 1994), as a carrier phase, followed by dissolution and separation. Electroplated sources are very useful for alpha spectroscopy (aS). Electroplating is the preparation of very thin and uniform actinide films obtained by electrodeposition onto stainless steel disks. The literature on electrodeposition describes the procedure (see Chapter 30), which remains empirical, perhaps because electrodeposition is a multiparametric process that includes the electrolyte solution (concentration, pH ), the hydrodynamic profile in the cell, the nature and geometry of the electrodes, the deposition current and potential, and the electrodeposition time. The electrodeposition of americium was reviewed with emphasis on the physicochemical behavior of the solution (Becerril‐Vilchis et al., 1994). The use of a tracer may be required to evaluate losses by adsorption of the studied actinides, or a quantitative method is

3024

Identification and speciation of actinides in the environment

followed such as the use of a hydrogen sulfate–sodium sulfate buffer (Bajo and Eikenberg, 1999). The effect of a counter‐ion was also studied in detail (Zarki et al., 2001). Recently, however, specific microprecipitation followed by ultrafiltration has been used as an alternative for source preparation. The separation and/or concentration of elements or species as soluble entities may be performed by applying partitioning between two phases such as: liquid–liquid, with specific complexes soluble in an organic phase: e.g.

2,4‐pentanedione (Haa) in toluene (Engkvist and Albinsson, 1992), thenoyltrifluoroacetone (TTA) in xylene for Np extraction (Dupleissis et al., 1974), tri‐n‐octylphosphine oxide (TOPO) in toluene for Pu, Am, and Cm extraction (Kosyakov et al., 1994), and solvent liquid extraction can be used for the analytical determination of actinides in urine (Harduin et al., 1993); liquid–solid, with specific polymers: anionic or cationic, organic (Qu et al., 1998) or inorganic (Kobashi et al., 1988). For example, actinides from contaminated soil samples can be separated by use of anion‐exchanger columns for Am, Cm, and Pu spectroscopy (Michel et al., 1999), and uranium from waters may be pre‐concentrated using an ion exchanger and filtered off before desorption in small aliquot acidic solution and analyzed using inductively coupled plasma optical emission spectroscopy (ICPOES) (Van Britsom et al., 1995). Chromatography is discussed in combination with detections in Section 27.4. The separation of colloidal species may be performed by applying specific techniques such as: field‐free techniques: ultrafiltration, gel permeation, or size exclusion

chromatography (Taylor and Farrow, 1987; Hafez and Hafez, 1992), or within a controlled field: flow‐field fractionation (Bouby et al., 2002),

density gradient fractionation (Mohan et al., 1991), or capillary or gel electrophoresis.

The latter technique has been performed for actinide separation by applying an electrical field during liquid–solid distribution. Speciation and solubility of neptunium has been studied in an underground environment by paper electrophoresis, ion exchange, and ultrafiltration (Nagasaki et al., 1988). Gradient gel electrophoresis was used to characterize 13 kDa polysaccharide ligands complexing 234Th from marine organic matter (Quigley et al., 2002). Capillary electrophoresis is growing in importance as a versatile assay for speciation; however, there are still major challenges that limit the practical acceptance of the technique. The potential problems are inadequate attention to sample preparation (species stability, matrix effect), ignoring possible change in speciation during electrophoresis, inappropriate treatment on method validation and system suitability, and no sample enrichment methodology. Recommendations have recently been suggested (Timerbaev, 2001).

Identification and speciation

3025

27.3 IDENTIFICATION AND SPECIATION

27.3.1

Passive techniques

Radiometric techniques dominate the analyses of short‐ and medium‐lived actinide nuclides. The passive techniques currently used for actinide detection are summarized in Table 27.2. They include spectroscopy (S) or RAD of X‐rays or gamma photons, along with Mo¨ssbauer emission spectroscopy (MBES), conversion electrons or b–, neutrons, and ions such as alpha or spontaneous fission products that are emitted during decay of actinide nuclides. The investigated systems range from geographic to microscopic in size and the detection tool may also be adapted to these scales. The actinide isotopes considered in the environmental studies are not bþ emitters; they may be neutron emitters that can consequently be detected by neutron spectroscopy (NS). Nothing is reported so far for the detection of the phonons generated by the actinide decays. Ion‐ selective electrodes (ISEs) may be used to detect actinide elements in a passive way, while gravimetry (GRAV) may be applied for concentrated phases. The passive techniques and more especially the radiometric techniques remain widely used for the analysis of actinides because they utilize low‐cost instrumentation, are simple to operate, achieve low‐cost of analysis per sample, and have the possibility to perform non‐destructive sample analysis. In X‐ray spectroscopy (XS) and g‐ray spectroscopy (gS), the most important developments include the production of high‐efficiency coaxial and well‐ type detectors operating with anti‐cosmic ray or anti‐Compton shielding. Detection is currently carried out using a semiconductor crystal or by scintillation. Typical analytes include natural actinides such as 234Th or anthropogenic actinides with detection limits of the order of 1 mBq. Based on this activity limit, the detection limits for actinide isotope amounts are calculated for relevant isotopes in Table 27.2. Sample preparation may require classical specific treatments before radioanalysis, such as separation or enrichment, as treated in Section 27.2. Measurements of transuranics, in particular several isotopes of plutonium, are especially difficult to carry out due to the low‐penetrating nature of their radiations (a‐ and X‐rays). Direct alpha detection is difficult; therefore thin scintillators that rely on the detection of L‐shell X‐rays (13–21 keV) are used for survey work (Miller, 1994). These instruments may be used for environmental detection and for X‐ray astronomical measurements in space. Theoretical detection limits for thin‐layer samples are given in Table 27.2. Determination of actinides in solution may also be carried out by using a high‐purity germanium crystal detector, allowing for plutonium a detection limit near 10–10 mol (Gatti et al., 1994). Classically, 227Ac may be determined in environmental samples from the beta or gamma activity of its daughter products (Khokhrin and Denisov, 1995). Gamma‐ray spectroscopy was used in situ and in the laboratory to determine

Ion GRAV, ISE, aS, LSC, RAD

Electron bS, LSC, RAD

Photon XS, gS, MBES, RAD

Detection

determination of mass or of isotope activity and identification of isotope

concentration or activity determination

determination of isotope activity and identification of isotope

Goal

solid film electroplated or liquid bulk scintillation

solid film electroplated or liquid bulk scintillation

solid or liquid bulk or film

Sample

228

Ac Th, 230Th, 232Th 231 Pa 234 U, 235U, 238U 237 Np 238 Pu, 239Pu, 240Pu 241 Am 242 Cm, 248Cm

227

234

Ac Th 233 Pa U Np 241 Pu Am Cm

228

230

Ac Th, 232Th 231 Pa 234 U, 238U 237 Np 239 Pu, 240Pu 241 Am 242 Cm, 244Cm

An(Y)

227

A

4 10–18 1 10
21, 6 10–17, 1 10–11. 2 10–17 2 10–21, 4 10–17, 3 10–11 2 10–15 7 10–20, 2 10–17, 5 10–18 3 10–19 3 10–22, 10–20

5 10–22 5 10–20 5 10–20 – – 1 10–17 – –

2 10–14 1 10–11, 5 10–7 2 10–14 2 10–11, 2 10–8 2 10–12 7 10–12, 1 10–12 1 10–16 5 10–15, 1 10–16

Detection limit

(Bojanoswki, 1987) (Yu‐fu, 1990) (Degueldre, 1994)

aS, DL: 10 mBq

(Yu‐fu, 1990)

b LSC, DL: 10 mBq, in 1 mL

(Bojanoswki, 1987) (Guillot, 2001)

gS, DL: 1 mBq

Remarks

Table 27.2 Passive analytical techniques used for actinide isotope, element, or species identification. Detection limit (DL) in mol recalculated from DL in Bq.

Identification and speciation 228

3027

Ac activities in eight sites around the proposed Yucca Mountain repository in Nevada (Benke and Kearfott, 1997). The in situ determined specific activities were consistently within the ±15% of the laboratory soil sample results. Despite the good correlation between field and laboratory results, in situ counting with calibrated detector was recommended. Gamma‐ray spectroscopy has been systematically used to detect 232Th or 238U from environmental samples. The detection of these isotopes may be done using gamma photons from daughter nuclides. In situ determination of uranium in surface soil was performed by gamma spectroscopy measuring 234Th and 234mPa using a high‐resolution g‐ray spectrometer and assuming secular equilibrium (Miller et al., 1994). On the other hand, uranium and thorium were also detected in soil samples by measuring 208Tl and 214Bi (LaBreque, 1994), respectively, which were as well assumed to be in secular equilibrium with their respective parents. The determination of the specific activity of these major natural actinides may be carried out by airborne gamma spectroscopy using the above key nuclides, or other nuclides, e.g. U by Ra (Kerbelov and Rangelov, 1997). This method enables analysis during fixed‐wing aircraft or helicopter flight (Guillot, 2001). The sensitivity of the spectral analysis of windows at 2615 and 1764 keV for 232Th (by 208Tl) and 238U (by 214Bi), respectively, was optimized by subtraction of the Compton continuum in the detection window. The detection of 232Th and 238U is possible in their natural background of 33 Bq kg–1 in a large‐volume NaI detector (16 L) and a short sampling time (1–5 s) at 40 m ground clearance. The calculation of the concentrations is then simple and reliable. A quantitative estimate of radioactive anomalies can also be obtained easily. The spectral profile analysis is of great interest and has been applied within the framework of environmental monitoring studies. Fig. 27.2(a) shows a map obtained for 232Th during a mapping exercise. Similarly, aerial measurements above uranium mining and milling area have also been reported (Winkelmann et al., 2001). A gamma‐logging (gS) probe has been used to monitor thorium and uranium as a function of depth in a borehole (Nagra, 1991; Mwenifumbo and Kjarsgaard, 1999), as presented in Fig. 27.2(b). The technique is used for uranium exploration; it discriminates between valuable uranium ore and other radioactive material of little value. Here again, lateral resolution is linked to detector geometry and improvements, e.g. coaxial logging cables are suggested (Conaway et al., 1980). Gamma logging has been used recently in a well contaminated with plutonium (Hartman and Dresel, 1998). In addition, the use of gamma spectroscopy for identifying and measuring plutonium isotopes in contaminated soil samples has been reported (Kadyrzhonov et al., 2000). The application of marine g‐ray measurements follows similar principles. The difference from the aerial technique is that water absorbs g‐rays rather strongly and that the detector must move at the surface of the seabed while being towed. The emitters are detectable if they are present in sufficient quantities and have energies above 100 keV. Consequently, if 238U and 232Th are

3028

Identification and speciation of actinides in the environment

Fig. 27.2 (a) 232Th maps (from exercise in Finland, Area 2) processed by the filtering and window methods (Guillot, 2001). (b) Th and U profiles from gamma spectroscopic (gS) instrumental analysis in Leuggern borehole (north Switzerland ). Note the uranium (opposite scale) depletion through defined faults in formation (Nagra, 1991).

detectable with daughter isotopes, low‐energy g emitters such as 241Am and the plutonium isotopes are very difficult to measure by applying this in situ technique (Jones, 2001). The radiometric technique alone is not effective for speciation. Only MBES, a resonant emission of gamma photons, can provide information. Among the actinide isotopes, 231Pa, 232Th, 238U, 237Np, and 243Am are active as the Mo¨ssbauer nucleus. While 237Np is an excellent Mo¨ssbauer nuclide, little speciation has been done for environmental samples, perhaps because Mo¨ssbauer spectroscopy requires macroconcentrations. In the field of beta spectroscopy (bS), introduction of a very low background liquid scintillation counting (LSC) spectrometer enables the analysis of soft b emitters such as 241Pu with detection limits of the order of 10 mBq (Yu‐fu et al., 1990). This makes it possible to estimate the detection limit for beta

Identification and speciation

3029

spectroscopy in Table 27.2. However, since the beta spectrum is continuous, application of beta spectroscopy cannot be directly used for the identification of actinides in environmental samples without the use of specific separation techniques. The counting yield of beta scintillation counting is always smaller than 100%. NS can be applied in a plain counting mode to detect spontaneously fissile actinides in the environment and in the framework of trafficking. Plutonium239 is hard to detect by means of its a‐, x‐, or g‐rays, but neutrons are more penetrating and can be specifically detected. Recently, sensitive neutron detectors including 3He proportional counter tubes moderator and integrated electronic have been developed to detect 239Pu down to the gram (5 10–3 mol) level at 20 cm in 5 s (Klett, 1999). GRAV belongs to the last class of passive techniques. Actinide GRAV, e.g. from ore samples, may be carried out after dissolution and separation with, for example, oxalate or oxinates at pH 5–9. Uranium in neutral conditions gives a red precipitate with oxine, UO2(C9H6NO)2·(C9H7NO) (Hecht and Reich‐Rohrwig, 1929), which should be washed with oxine solution (Claassen and Vissen, 1946). However, this technique suffers from a lack of specificity. ISEs belong to the class of electron detection passive tools for species analysis, and while the hydrated electrons themselves are not detected, the electronic exchange remains the driving force. Poly(vinyl chloride) matrix membrane uranyl ion‐sensitive electrodes based on organophosphorous sensors were successfully tested (Moody et al., 1988). Recently, multi‐sensors were developed for the determination of Fe(II), Fe(III), U(VI), and U(IV) in complex solutions (Legin et al., 1999). Twenty‐nine different sensors (selective electrodes) with various solid‐state crystalline and vitreous materials with enhanced electronic conductivity and redox and ionic cross‐sensitivity have been incorporated into the sensor array. The system was tested for Fe(II) and Fe(III) concentrations in the range 10–7 to 10–4 M, as well as for U(VI) and U(IV), the latter being determined with a precision of 10–40%, depending on the concentration. The developed multi‐sensor system could be applied in the future for the analysis of mining and borehole waters, and other contaminated natural media; it can include on‐site measurements. For alpha spectroscopy, the high‐resolution silicon detectors have proved to be sensitive down to 10 mBq levels for analysis of both natural Th and U isotopes and daughter nuclides, as well as for the anthropogenic actinides. The isotope 227Ac was quantitatively determined in environmental samples after sample treatment and electrodeposition: a first alpha count at 4.85–4.95 MeV for the 1.38% alpha decay of 227Ac and a second at 5.5–6.1 MeV after 227 Th buildup to equilibrium (Bojanowski et al., 1987) were obtained. After sample treatment 232Th and 238U from environmental samples are better characterized by alpha spectroscopy than by gamma spectroscopy as, for example, in urine analysis (Eikenberg et al., 1999) (Fig. 27.3(a)). Natural (U, Th) and anthropogenic (Pu, Am) actinides were, for example, determined and their

3030

Identification and speciation of actinides in the environment

Fig. 27.3 (a) An alpha spectrum of naturally occurring nuclides in urine with an added 229 Th spike for determination of the chemical recovery of Th. At high energy, the peaks of 224 Ra and 225Ac are daughter products of 228Th and 229Th, respectively. Isotopes of U are also present because the fast procedure for actinide extraction does not separate between Th and U (Eikenberg et al., 1999). (b) Alpha spectrum obtained for an air filter; 242Cm is identified at 6.1 MeV; the sampling was 960 m3 air through a 154 cm2 filter, without hot spot and with a hot spot (0.03 Bq a, ~10–21 mol 242Cm), note the 5.3 MeV peak is due to natural 210Po (Ga¨ggeler et al.,1986).

speciation determined in Venice canal sediment samples (Testa et al., 1999). Here sequential extraction was applied before extraction chromatography, followed by electroplating and alpha spectroscopy. Pu and Am were found at the 1.0 and 0.3 Bq kg
1 level, respectively, with a 241Am/239þ240Pu ratio of 0.3,

Identification and speciation

3031

while Th and U were at the 20 and 30 Bq kg–1 levels. These isotopic analyses show that the sediments were not affected by the Chernobyl fallout but have been contaminated by nuclear weapon test fallout. An activity may be measured after separation of the sample on a membrane after filtration or ultrafiltration. This may be applied for electrolytic fluids, solutions, or gas. Activity measurements on size‐fractionated aerosols indicate different transport mechanisms for I and Ru, Cs (gaseous), or actinides (particulate) released during the Chernobyl accident. A hot particle found by autoradiography on an air filter sample was measured with a surface barrier detector (Ga¨ggeler et al., 1986). Its alpha activity was identified to be mainly due to 242 Cm (Fig. 27.3(b)). Alpha LSC is attractive because it offers a nearly 4p geometry and because the counting yield for an actinide a emitter is about 100%, but with a lower energy resolution than for alpha spectroscopy. Improvements for alpha energy resolution and background reduction are key needs. An improvement of alpha energy resolution for determining low‐level plutonium has been achieved using combined solvent extraction low‐level liquid scintillation counter (Yu‐fu et al., 1990) and can also be applied for 239þ40Pu and 241Pu activity measurements in seawater (Irish Sea and North Sea) and soils (Cumbria and Belorussia) (Yu‐fu et al., 1990). Resolution of the order of 275 keV for liquid scintillation spectra can be achieved, which allows low‐level determination of plutonium (see Fig. 27.4(a)). Autoradiography (RAD) consists of using a photographic film or an organic‐ sensitive polymer to record tracks induced by the decay products from hot spots or contaminated phases in seawater, sediments, or marine organisms (Wong, 1971; Baxter et al., 1995) (e.g. Fig. 27.4(b)) or, for example, natural rock samples sorbed with uranium and americium (Smyth et al., 1980). After development, quantification of the tracks can be performed by counting the tracks or using a densitometer. Extensive work has also been performed with rock samples contacted with actinide solutions or simply contaminated (e.g. Fig. 27.4(c)). 241 Am and 233U sorbed onto the rock cause tracks in the autoradiographic emulsions, which may be revealed and observed with an optical microscope. Direct detection with a grid detector and an image reconstruction of the source can also be carried out (Ward et al., 1998). In all passive techniques, geometrical parameters such as size of the system analyzed, size of the detector, and object–detector distance are key parameters, which, together with acquisition time, rule the detection limit for actinide identification. Radon and helium contents in groundwater, rock, or soil may be analyzed as actinide by‐products to identify uranium‐ or thorium‐rich phase locations. Radon and uranium contents may be correlated (Virk, 1997). However, radon data need to be correlated with helium to yield more accurate results (Virk et al., 1998). It must be noted that radon emanations and helium data are controlled not only by the uranium content of the rock and soil but also by structural zones (thrust, fault, etc.) that help in the easy migration of helium and radon from

Fig. 27.4 (a) Liquid scintillation counting spectrum from a soil layer, showing (A) 241Pu (b) and alpha activities including both 239Pu þ 240Pu (B) and the 236Pu tracer (C ) (Yu‐fu et al., 1990). Note that compared to alpha spectrometry, LSC resolution is lower. (b) Heterogeneous alpha‐track distribution in the digestive gland of the winkle following 13 day uptake of 239Pu from labeled food. A 19 day exposure (3 cm ¼ 500 mm) (Baxter et al., 1995). (c) Alpha tracks of a hot spot from the analysis of the humus layer, exposure time 46 days, total number of alpha tracks about 600, corresponding to an activity of ~0.5 mBq (Carbol et al., 2003).

Identification and speciation

3033

deeper parts of the Earth’s crust. Consequently, for uranium prospection, the use of helium and radon data must be verified by combining other techniques, as discussed in Section 27.4. 27.3.2

Interactive photon–photon techniques

The techniques derived from the interaction of photons with a sample and subsequent detection and spectral analysis of photons are numerous, taking advantage of the potential of the large energy spectrum available. They are listed by increasing energy of the incident photon beam as follows: nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), infrared Fourier transform spectroscopy (IRFT), diffuse reflection spectroscopy (DRS), near‐infrared and visible spectroscopy (NIR‐VIS), or spectrophotometry, or colorimetry (COL), Raman spectroscopy (RAMS), atomic absorption spectroscopy (AAS), laser ablation inductively coupled plasma optical emission spectroscopy (LAICPOES), time‐resolved laser‐induced fluorescence spectroscopy (TRLIFS), phosphometry (PHOS), ultraviolet spectroscopy (UVS), X‐ray absorption spectroscopy (XAS), X‐ray fluorescence spectroscopy (XRF), X‐ray tomography (TOM), Mo¨ssbauer absorption spectroscopy (MBAS), and photoactivation (PHOTA). Table 27.3 depicts the way in which these techniques may be used in spatial (transmission, reflection) and temporal (with or without delay) modes when applied to actinide identification or speciation. In transmission mode, single‐ or double‐beam techniques are applied, the second technique subtracting automatically the blank. In reflection or scattering mode the axis along the detection probe forms an angle with the incident beam. In the delayed mode, detection is carried out at a specific time after excitation of the sample. NMR is a radiofrequency spectroscopy method that utilizes the interaction of a nuclear magnetic dipole or an electric quadrupole moment with an external or internal magnetic field. Information collected from these investigations characterizes chemical atomic environments. Actinide isotopic species such as 229 Th(IV), 233U(VI), and 235U(VI) are active in NMR (Fisher, 1973) at concentration above 10–2 M, and for 231Pa(V) and 237Np(VII) above 10–4 M. However, very little NMR is done in actinide environmental science except using the NMR signals of actinide neighbor nuclides (1H, 17O,. . .). EPR is a spectroscopy involving the interaction of electrons in magnetic field, allowing magnetic characterization and indirectly speciation. This technique has been mostly used to study the effect of actinide decay on the magnetic properties dictated by the paramagnetic center concentration of the sample, e.g. soil matrix (Rink and Odom, 1991; Li and Li, 1997; Kadyrzhanov et al., 2000). Infrared spectroscopy (IRS) has occasionally been used for the study of actinides under environmental conditions. It has been used in the transmission mode as well as in the diffuse reflectance mode, both with and without the

determination of species

Reflected scattered photon NMR, EPR, DRS, RAMS, PHOS, UVF, XRF

determination of elements species or isotopes

identification and determination of species

Transmitted photon IRS, IRFT, NIR‐VIS, PCS, COL, AAS, UVS, XAS, TOM, MBAS

Delayed photon LAICPOES, TRLIFS, PHOTA

Goal

Detection

liquid bulk or solid bulk

solid bulk or liquid bulk

solid or liquid bulk, or interphases

Sample

Ac(III) Th(IV) 2331–234 Pa(V) 234–238 U(VI) 237,239 Np(IV–VI) 238–244 Pu(IV–VI) 241,243 Am(III) 242–250 Cm(III) 227–232

Ac(III) Th(IV) Pa(IV,V) U(IV–VI) Np(IV–VI) Pu(IV–VI) Am(III–V) Cm(III)

Ac(III) Th(IV) Pa(V) U(VI) Np(V) Pu(IV–VI) Am(III–VI) Cm(III)

An (Y)

A

– – – 1 10–12 M 1 10–9 M 4 10–8 M 4 10–9 M 4 10–11 M

– – – 6 10–10 mol 2 10–9 mol 1 10–9 mol 1 10–9 mol –

– 3 10–8 M COL – 4 10–8 M COL 1 10–7 M VIS – – –

Detection limit

(Moulin et al., 1991) (Stepanov, 1990) (Moulin, 1995) (Beitz, 1980, 1988)

TRLIFS

(Civici, 1997) (Akopov et al., 1988)

XRF

(Keil, 1981) (Keil, 1979) (Gauthier et al., 1983)

VIS or COL

Remarks

Table 27.3 Interactive analytical techniques including photon–photon for actinide isotope, element, or species characterization.

Identification and speciation

3035

application of the Fourier transform. IRS may provide useful information on the speciation of an actinide when present in relatively large concentrations. For example the complexation and reduction of uranium by lignite was determined with site‐specific material (Nakashima, 1992). An alternative way to determine actinide speciation may be obtained applying RAMS. The vibrational frequencies concerned are assigned to AnOiþ 2 , which yields a peak near 870 nm for U(VI) to 860 nm for Np(VI), 767 nm for Np(V), and 835 for Pu(VI) and for actinide concentrations above 10–3 M (Basile et al., 1978; Maya and Begun, 1981). The speciation of uranyl in water and sorbed on a smectite (see Fig. 27.5 (a) and (b)) was investigated by Raman vibrational spectroscopy (Morris et al., 1994). The uranium loading was from 0.1 to about 50% of the cation‐exchange capacity. The spectral peaks varied in shape and morphology, suggesting speciation changes during the loading. RAMS may be applied at the macroscale (cubic millimeter) as well as at the microscale (cubic micrometer). NIR‐VIS of the 5f elements is a powerful technique for the characterization of oxidation state (e.g. Gauthier et al., 1983) for Np and complexes (e.g. Runde et al., 1997) of actinides. Molar absorptivities (ε) of actinide ions are however smaller than 500 M–1 cm–1, limiting the detection limit of the actinide solutions to ~10–5 M. Consequently, for actinide ion speciation in natural waters ((An) 100 mesh); KOH‐bone (bone powder heated in KOH and ethylene glycol to digest the organic matrix); EDTA‐bone (decalcified organic matrix). Carborundum, alundum, and pumice were included as particulate controls. Samples of each powder were shaken for 24 h with 100 to 200 mL of the Pu4þ‐lactate buffer solution, and the clear supernatant was sampled periodically after allowing the solids to settle. After 24 h, the four particulates

3408

Actinides in animals and man

containing bone mineral had taken up 95% of the Pu4þ in the medium. The initial uptake rates of the bone mineral samples were in the order: bone ash (fine) > bone ash (coarse) >> KOH‐bone >> whole bone. At equilibrium, the EDTA‐decalcified organic fraction took up 10% of the available Pu4þ. The Pu4þ did not adhere to the three inert mineral powders. Addition of 0.2 M Ca2þ or 0.2 M Naþ to the buffer medium did not change either the rates or 24 h uptakes of Pu4þ by the whole bone or bone ash powders. Foreman (1962) also prepared whole rat femora, as follows: fresh bone cleaned of adhering soft tissue; bone ash (700 C furnace); KOH‐bone; and EDTA‐bone. Four replications of each femur preparation were sealed in cellophane bags and surgically implanted in the peritoneal cavities of ‘host’ rats. The ‘host’ rats were injected iv with 239Pu4þ citrate 24 h later and killed 48 h after the Pu4þ injection. Uptake of the Pu4þ in the living femora of the ‘host’ rats was reproducible, on average, 164 400  66 000 cpm per whole bone. Uptakes of Pu4þ in the implanted femora that had been heat or chemically ashed were nearly the same, about 40% of that in the living bone of their ‘hosts’, while Pu4þ uptakes in the implanted fresh bone and EDTA‐decalcified bone were 15 and 6%, respectively. The chemically or heat ashed bone preparations that were essentially free of organic tissue barriers had the greatest affinities for the Pu4þ, while the affinity of the decalcified bone matrix was the least. An important outcome of this experiment was the demonstration of the passage of Pu4þ through the semipermeable cellophane membrane, implying the presence of a filterable Pu4þ complex in the interstitial fluid of the peritoneal cavity. Chipperfield and Taylor (1972) prepared dilute solutions of 239Pu4þ, 241 Am3þ, and 244Cm3þ nitrates, each of these was mixed with 3 mL of solutions of tris buffer pH 7.2 containing chelators, including: 3.4 10
4 M sodium citrate, 3.2 10
4 M EDTA, 2.4 10
4 M DTPA, 3.4 10
6 M Tf, or 4

10
6 M bone sialoprotein or bone chondroitin sulfate–protein complex. Fine cortical bone ash powder (200–300 mesh) was added (10 mg) to each actinide‐ chelator solution and stirred vigorously for 1 h. Supernatant containing unbound actinide and solids containing bound actinide were separated by centrifugation. In the absence of a chelator, all three actinides were quantitatively associated with the bone mineral fraction. The fractions bound to the bone mineral (100% – reported solution content) for Pu4þ, Am3þ, and Cm3þ, respectively, were as follows: Tf (98, 99, 84); citrate (73, 100, 100); bone glycoproteins, on average (79, 92, 92); EDTA (91, 70, 61); DTPA (14, 0, 0). Effectiveness for preventing actinide binding to bone mineral, which can be viewed as the stabilities of their complexes with the chelators relative to those formed with the bone ash is in the order: Tf citrate < bone glycoproteins < EDTA < DTPA. Binding of Am3þ and Cm3þ to bone mineral was the same in this test system and nearly quantitative in the presence of Tf, citrate, or the bone glycoproteins; it was partially prevented by EDTA and completely prevented

Actinide binding in bone

3409

by DTPA. Binding of Pu4þ to bone mineral was nearly quantitative in the presence of Tf, partially prevented by EDTA, the bone glycoproteins, or citrate, and incompletely prevented by DTPA. Guilmette et al. (1998, 2003) prepared solutions of 238Pu4þ, 239Pu4þ, and 241 Am3þ in 0.0034 to 0.005 M sodium citrate. Finely ground bovine bone ash and synthetic bone mineral (hydroxyapatite, HAP) were characterized by X‐ray diffraction, and their measured specific surface areas were 10.7 and 65 m2 g
1, respectively. Each actinide was stirred for 24 h with 10 mg of a mineral powder in 0.1 M HEPES buffer pH 7.2. The solid and supernatant were separated by ultrafiltration. Under these conditions 99% of the actinide was bound to the minerals. Varying masses of 238Pu4þ and 239Pu4þ (0.001–100 mg) and 241Am3þ (0.001–1.0 mg) were added to 10 mg of bone ash or HAP to characterize the relationships between actinide binding and mineral surface area, that is, the binding capacity. For Pu4þ, masses 10 mg, and for all 241Am3þ masses studied, binding to both minerals was 99% in 24 h. However, when the mass of 239Pu4þ was 100 mg, more than 50% incubated with bone ash and 20% incubated with HAP remained unbound at 24 h. The data are consistent with the larger specific surface area of HAP presenting more binding sites, and they may also be interpreted as signifying that the mineral surfaces contain a saturatable number of potential metal‐binding sites per unit area. The DTPA chelates of 238Pu4þ and 241Am3þ were incubated with 10 mg of HAP. There was no indication that the 241Am3þ–DTPA complex dissociated in favor of mineral binding. In contrast, 50% of the 238Pu4þ–DTPA complex dissociated in 24 h in favor of binding to the bone mineral. The stability of 241Am3þ–DTPA is evidently greater, while that of 238Pu4þ–DTPA is somewhat less, than the stabilities of their respective bone mineral complexes. Guilmette et al. (2003) investigated removal of 238Pu4þ and 241Am3þ from bone mineral by 24 h incubation of those actinides prebound to HAP by chelators in solutions of 0.1 M HEPES buffer pH 7.2. Binding of 238Pu4þ and 241 Am3þ by HAP is sufficiently stable that ZnNa3–DTPA removed only 1.4% of the Am3þ and 0.1% of the Pu4þ sorbed to the mineral. Actinide removal from HAP was tested with a set of tetra‐, hexa‐, and octadentate ligands with linear or branched backbones containing bidentate catecholate (CAM) or hydroxypyridinonate (HOPO) metal‐binding groups. Removal of Pu4þ (4–54%) was achieved only by the linear octadentate CAM and HOPO ligands. Removal of Am3þ (5–21%) was achieved with several linear or branched tetra‐, hexa‐, or octadentate ligands. Bostick et al. (2000), Moore et al. (2003), and Thomson et al. (2003) conducted investigations in support of the management and remediation of actinide‐contaminated groundwaters, sediments, and wastewaters. Batch sorption 3þ þ 4þ and column tests demonstrated the great affinities of UO2þ 2 , NpO2 , Pu , Am , 3þ and stable Ce for natural and synthetic apatites, including hydroxyapatite, Ca3(PO4)2, and bone ash.

Actinides in animals and man

3410 31.8.4

Actinide binding by bone glycoproteins

A case can be made for the participation of some low abundance organic matrix constituents in the binding of actinides in living bone (reviewed by Duffield and Taylor, 1986). In vitro complexation of Th4þ and Pu4þ, and to a lesser degree, Am3þ and Cm3þ by isolated mucoprotein substituents of bone matrix has been demonstrated. All of the multivalent lanthanides and actinides studied autoradiographically deposit most intensely on fully mineralized bone surfaces, anatomical sites that also stain positively with PAS for the presence of mucosubstances (Jowsey, 1956; Herring et al., 1962; Williamson and Vaughan, 1964; Vaughan et al., 1973). Paraphrasing Jowsey (1956) in response to a conference participant’s question: In areas of bone resorption, the PAS staining is the result of the depolymerized state of the mucopolysaccharides in the ground substance (matrix). In such state there are presumably free side chains of the mucopolysaccharide molecules (containing potentially chelating 1,2‐hydroxy groups), which are oxidized by the periodic acid to aldehydes and take up the Schiff stain. Nearly 90% of the organic bone matrix is collagen, which contributes about 20% of the weight of native bone. Five distinct glycoprotein fractions were extracted from bovine cortical bone. Their designations and weight fractions of native bone (% by weight) are, as follows: bone sialoprotein, 0.25%; bone chondroitin sulfate–protein complex, 0.18%; three less well‐characterized glycoprotein fractions – glycoprotein I and II, 1.57% combined; cetylpyridonium chloride (cpc) soluble glycoprotein, 0.1%. While not regarded as conclusive, supporting experiments indicate that the sialoprotein content (and perhaps also the other mucosubstances) of bone are formed and laid down in the matrix during bone formation. The functions of the mucosubstances of mature bone are not known (Herring, 1964). Bone sialoprotein contains large proportions of sialic, glutamic, and aspartic acids; 15, 20, and 15 moles of acids per mole of protein, respectively. Chipperfield and Taylor (1968, 1970, 1972) used gel filtration (Sephadex G‐25 and G‐50) to investigate the bonding of ultrafiltered dilute solutions of 228Th4þ, 239 Pu4þ, 241Am3þ, and 244Cm3þ nitrates incubated with the isolated bone glycoproteins noted above. The proteins were dissolved in tris buffer pH 7.2, and the protein:metal molar ratios were 1:1 for Pu4þ and 10:1 for the higher specific activity radionuclides. The results of those studies are collected in Table 31.13. Those results, although variable and regarded by the authors as semiquantitative, indicate that at physiological pH the isolated glycoprotein fractions of bone matrix can form complexes with Th4þ and Pu4þ, and to a lesser degree, with Am3þ and Cm3þ. Under these experimental conditions, the affinities of the bone glycoprotein fractions for Th4þ and Pu4þ apparently exceed the affinities for these actinides of reconstituted human Tf or apo‐Tf. Two of the bone glycoproteins, bone sialoprotein and bone chondroitin sulfate–protein

Actinide binding in bone

3411

Table 31.13 Collected data for association of selected actinides with isolated bone glycoproteins, human transferrin, and poly‐L‐glutamic acid.a Percent of applied actinide eluted with protein Protein

228

Bone sialoprotein Bone chondroitin sulfate–protein complex Glycoprotein I Glycoprotein II Cpc‐soluble glycoprotein Human transferrin Apotransferrin Soluble collagen Poly‐L‐glutamic acid

96d 78d, 22e

71b, 52c, 55d 72b, 49d, 13e

30b, 10d 5.0b, 15d, 0.3e

12d 10d, 0.3e

13d 72d 83d 61c,e 30c – 80e

30d 50d 37d 24b,c, 19e 43c 2.8b, 23d 69e

2.8d 5.1d 4.6d 0.17b, 0.2e – 0.6d, 0e 8.0e

38d 8.2d 8.7d 0e – 0.9d 27e

Th4þ

239

Pu4þ

241

Am3þ

244

Cm3þ

a

Reported values of protein binding rounded to two significant figures. Ultrafiltered actinide nitrates incubated with proteins dissolved in tris buffer at pH 7.2. Mixtures eluted with buffer from G‐25 or G‐50 Sephadex gel columns to determine amount bound to protein. b Chipperfield and Taylor (1968). c Chipperfield and Taylor (1970). d Table I of Chipperfield and Taylor (1972). e Table II of Chipperfield and Taylor (1972).

complex, were about as effective as EDTA in competing with bone ash for Pu4þ, Am3þ, and Cm3þ. Supporting studies demonstrated that actinide binding by the bone glycoproteins was pH dependent; maximum binding of Pu4þ by bone sialoprotein is at pH 6, and of Am3þ and Cm3þ at pH 8. These results were interpreted by the authors to mean that Pu4þ was bound by the abundant carboxyl groups of the protein’s amino acid side chains, but that those carboxyl groups were less important for binding the trivalent actinides. Binding of Pu4þ by bone sialoprotein was reduced, but not abolished, by mild acid hydrolysis (removal) of the terminal sialic acid moieties, which suggests that the sialic acid groups may also participate in metal binding. 31.8.5

Summary

Actinide binding in bone is a surface phenomenon. However, except for UO2þ 2 , binding of the trivalent and tetravalent actinides and NpOþ 2 to bone surfaces is so stable that those metals neither migrate into the bone volume via the canaliculi nor are released back into the circulation by ion exchange or complexation with the ligands of the constantly flowing plasma and tissue fluid. At physiological pH, trivalent and tetravalent lanthanides and actinides, þ UO2þ 2 and NpO2 , bind stably to native and synthetic bone mineral in vitro. Actinide uptake by various bone mineral preparations was nearly quantitative

3412

Actinides in animals and man

from buffered solutions (lactate, tris, HEPES, pH 7–7.4) even from those solutions that also contained 0.3 to 0.5 mM citrate, whole plasma, or human Tf. In general, actinide uptake by the crystalline bone mineral preparations (synthetic HAP, chemically ashed KOH‐glycol bone, or ED‐bone) was faster than for bone ash, Ca3(PO4)2, or powdered defatted whole bone, in which about one‐half of the exposed particle surface is organic matrix. Actinide uptake by bone mineral is positively correlated with the surface area of the particles and appears to be saturable, indicating a fixed number of binding sites per unit surface area. Hydroxyapatite [Ca10(PO4)6(OH)2] presents an organized Ca2þ‐poor negatively charged surface with unsatisfied negative charges on adjacent phosphates. If Ca2þ is replaced, as is the case for UO2þ 2 , there is access to the oxygens of two and perhaps three phosphates. The complexes of Th4þ and Pu4þ with bone mineral are more stable than the complexes that these metal ions form with ZnNa3-DTPA, indicating that the crystals themselves provide spatially suitable multidentate binding sites. The PAS‐positive staining at the organic–mineral interface of bone surfaces, which are the actinide deposition sites in the skeleton, suggested that bone glycoproteins may participate in actinide binding, even though powdered decalcified bone matrix does not bind actinides. Five isolated low abundance bone glycoproteins form variably stable actinide complexes. The binding units of these proteins are considered to be mainly free sialic acid, the monodentate carboxyl groups of glutamic acid, and the bidentate alpha‐hydroxy‐carboxyl groups of aspartic acid. The mineral crystals of native bone are sandwiched between layers of matrix collagen fibers, and the exposed bone surfaces do not present as many metal‐ binding sites as isolated bone mineral crystals. The most stable complexes of the trivalent lanthanides and actinides are six‐coordinate (six M–O bonds), and those of the tetravalent actinides are eight‐coordinate (eight M–O bonds). It would seem that in situ the number and configuration of the exposed potential binding groups of the glycoproteins alone would be insufficient to provide enough suitably arranged binding groups for stable actinide complexation. However, in living bone, both the mineral crystals and the neighboring matrix constituents (glycoproteins) combined may furnish sufficient numbers of binding groups suitably arranged in three‐dimensional space for rapid stable actinide complexation in situ. 31.9 IN VIVO CHELATION OF THE ACTINIDES

The potential hazards to human health of the radioactive fission products and new heavy elements created by nuclear fission were recognized early, stimulating the search for effective ways to remove internally deposited radioelements

In vivo chelation of the actinides

3413

from the body (Schubert, 1955; Voegtlin and Hodge, 1949, 1953; Stone, 1951). Chemical agents that form stable excretable actinide complexes were soon recognized as the only practical therapy for internal contamination (decorporation) (Voegtlin and Hodge, 1949, 1953; Schubert, 1955; Rosenthal, 1956; Catsch, 1964). Such agents should have greater affinity for actinides at physiological pH than the biological ligands, low affinities for essential divalent metals, and low toxicity at effective dose. Reviews and proceedings of conferences on the development of chelators suitable for removal of internally deposited actinides have dealt with the chemistry of metal chelates, animal studies to determine ligand effectiveness for reducing actinide burdens in the tissues and amelioration of actinide‐induced chemical and radiation damage, ligand toxicity, and clinical applications (Rosenthal, 1956; Seven and Johnson, 1960; Kornberg and Norwood, 1968; Volf, 1978; NCRP, 1980; Raymond and Smith, 1981; Taylor, 1991; Bhattacharyya et al., 1992; Durbin et al., 1997a, 1998a,b; Stradling et al., 2000a,b; Wood et al., 2000; Gorden et al., 2003). 31.9.1

Polyaminopolycarboxylic acids

The first chelating agent investigated was ethylenediaminetetraacetic acid (H4‐EDTA). Its Ca2þ salt, CaNa2–EDTA, was introduced to avoid toxic depletion of serum Ca2þ. It enhanced excretion of 91Y3þ, 144Ce3þ, and 239Pu4þ in rats (Foreman and Hamilton, 1951; Hamilton and Scott, 1953). But CaNa2–EDTA is a poor actinide decorporation agent: it is renally toxic at effective dose; it depletes essential Zn2þ and other divalent metals; its efficacy cannot be improved except by increasing the administered dose. Pentacarboxyl diethylenetriaminepentaacetic acid (H5‐DTPA) and its Ca2þ and Zn2þ salts (CaNa3–DTPA introduced in 1957 and ZnNa3–DTPA introduced in 1965) improved lanthanide and actinide decorporation compared with CaNa2–EDTA (Catsch and Leˆ, 1957; Kroll et al., 1957; Smith, 1958; Catsch and von Wedelstaedt, 1965). Those clinically approved DTPA salts are effective decorporation agents for the trivalent lanthanides and actinides, less effective for Pu4þ and Th4þ, and nearly ineffective for reducing the body content of þ UO2þ 2 or NpO2 . [See references cited in Volf, 1978; Durbin et al., 1997a, 1998a,b; Gorden et al., 2003]. Although nominally octadentate, CaNa3–DTPA appears not to coordinate fully with Pu4þ, and it does not remove Pu4þ bound to bone mineral in vitro (Raymond and Smith, 1981; Guilmette et al., 2003). Several variants and derivatives of DTPA have been prepared and tested in animals, including polyaminopolycarboxylic acids with longer central bridges or additional carboxyl groups (Catsch, 1964); a dihydroxamic acid derivative, ZnNa–DTPA–DX (Durbin et al., 1989b; Stradling et al., 1991; Volf et al., 1993); lipophilic derivatives containing long alkane side chains (Volf, 1978; Raymond and Smith, 1981; Miller et al., 1993). None of those DTPA‐based

Actinides in animals and man

3414

ligands was substantially more effective for in vivo chelation of lanthanides or Pu4þ or less toxic than native CaNa3–DTPA, and most have been abandoned. 31.9.2

Desferrioxamine

Desferrioxamine (DFO), a linear tris‐hydroxamate ligand, is a member of a class of compounds (siderophores) elaborated by microorganisms to obtain iron from the environment (Raymond and Smith, 1981). In vivo Pu4þ chelation is hampered by the weak acidity of the hydroxamic groups, which are not ionized at pH < 8; they are deprotonated only slowly at pH 7.4 by Fe3þ and Pu4þ but not by trivalent actinides (Taylor, 1967; Durbin et al., 1980, 1989b; Rodgers and Raymond, 1983).

31.9.3

Siderophores as model chelators

Investigations of the siderophores and their structures and coordination chemistry identified the powerful hexadentate iron‐sequestering agent, enterobactin (EB). EB is produced by enteric bacteria (E. coli) to obtain Fe3þ from the nearly neutral contents of the mammalian intestine (see references in Raymond and Smith, 1981 and Gorden et al., 2003). It contains three bidentate catecholate binding groups attached through amide linkages to a cyclic 1‐serine backbone and is preorganized for binding. The properties and structure of EB and similarities in the coordination properties of Pu4þ and Fe3þ provided the basis for rational design of highly selective multidentate actinide chelators that would be effective at physiological pH. (a)

Catecholate ligands

Multidentate catecholate ligands based on the EB model (denticity 4–8) were prepared containing catechol (CAM), sulfocatechol [CAM(S)], carboxycatechol [CAM(C)], or catecholamide (TAM) metal‐binding groups (Fig. 31.15) attached through amide linkage to linear (LI‐), cyclic (CY‐), aromatic (ME‐), or branched (TREN‐, H(2,2)‐) backbones. Syntheses and structures of the CAM ligands are collected in Gorden et al. (2003). All of those ligands were evaluated for promotion of excretion of 238Pu4þ from mice (30 mmol kg
1 ligand ip 1 h after iv injection of 238Pu4þ citrate, kill at 24 h). Catecholate ligands of denticity hexadentate > tetradentate (Guilmette et al., 2003). The octadentate ligands more than satisfy the requirement for six‐coordination preferred by Am3þ, and if three of their bidentate metal‐binding units can bind to Am3þ without steric hindrance, the extra binding group appears to enhance the stabilities of their Am3þ complexes. As noted above, in vivo chelation of Am3þ by the octadentate ligands containing carboxy‐ or sulfocatechol [CAM (C), CAM(S)] or by hydroxamate (as in the octadentate ligands with the DFO‐ backbone) is weak because too few of the hydroxyl groups of those ligands can be deprotonated by Am3þ (and presumably other trivalent actinides) to form stable complexes at physiological pH (Lloyd et al., 1984c; Kappel et al., 1985; Stradling et al., 1986, 1989; Volf, 1986; Volf et al., 1986; Zhu et al., 1988). Four HOPO ligands have been investigated in rats and mice for in vivo chelation of Am3þ: octadentate 3,4,3‐LI(1,2‐HOPO), hexadentate TREN‐ (Me–3,2‐HOPO), tetradentate 5‐LI(Me–3,2‐HOPO), and 5‐LIO(Me–3,2‐ HOPO). When given by injection or orally (30 mmol kg
1) to rats or mice contaminated with 241Am3þ by injection or infiltration into a wound, all four of those ligands were more effective than an equimolar amount of

In vivo chelation of the actinides

3421

CaNa3–DTPA. Octadentate 3,4,3‐LI(1,2‐HOPO) was about as effective as CaNa3–DTPA, while the other HOPO ligands of lesser denticity were less effective than CaNa3–DTPA for reducing body and lung Am3þ when the Am3þ had been inhaled (Stradling et al., 1992; 1993, 1995b; Volf et al., 1993, 1996; Durbin et al., 1994; Gray et al., 1994; Volf, 1996; Gorden et al., 2003). (e)

Ligands for UO2þ 2

Soluble uranyl ion, UO2þ 2 , is nephrotoxic, and because bone is the major storage organ for UO2þ 2 , the high specific activity uranium isotopes also induce bone cancer (Voegtlin and Hodge, 1949, 1953; Finkel and Biskis, 1968; Hodge, 1973). Although sought since the 1940s, no multidentate ligand was identified that would efficiently bind UO2þ 2 in vivo, promote its excretion, and reduce deposits in kidneys and bone (reviewed by Durbin et al., 1997a). The modest reductions of acute UO2þ 2 poisoning obtained with tiron, a bidentate sulfocatecholate, suggested that multidentate ligands containing similar binding groups would be effective in vivo UO2þ 2 chelators. Representative tetra‐, hexa‐, and octadentate ligands with linear or branched backbones containing CAM(S), CAM(C), MeTAM, 1,2‐HOPO, or Me‐3,2‐ HOPO groups (20 in all) were evaluated in mice for in vivo chelation of UO2þ 2 . Experimental conditions were: 232 þ 235UO2Cl2 or 233UO2Cl2 pH 4 injected iv, 30 mmol kg
1 of ligand injected ip at 5 min (see Fig. 31.11), ligand: U molar ratio 75 to 91, kill at 24 h. All of the test chelators were screened for acute toxicity. Except for the two tetradentate 1,2‐HOPO ligands and CaNa3–DTPA, all of the injected test chelators significantly reduced UO2þ 2 in the kidneys compared with controls, and ligands containing CAM(S), CAM(C), or MeTAM groups also significantly reduced UO2þ 2 in the skeleton. Administered orally at molar ratios from 90 to 300, the linear tetradentate ligands containing Me‐3,2‐HOPO, CAM (S), or CAM(C) and 3,4,3‐LI(1,2‐HOPO) significantly reduced UO2þ 2 binding in the kidneys, but not in the skeleton. The combined assessments of ligand efficacy and acute toxicity identified tetradentate 5‐LIO(Me‐3,2‐HOPO) and 5‐LICAM(S) as the most effective low toxicity agents for UO2þ 2 . They efficiently removed circulating UO2þ at molar ratios as low as 20, removed useful amounts 2 of newly deposited UO2þ from kidneys and/or bone at molar ratios 100, 2 and reduced kidney UO2þ significantly when given orally at molar ratios 2 100. 5‐LIO(Me‐3,2‐HOPO) has greater affinity for UO2þ in the kidneys, 2 5‐LICAM(S) has greater affinity for UO2þ 2 in bone, and a 1:1 mixture of the two ligands (total ligand: U molar ratio 91) reduced kidney and bone UO2þ 2 to 15 and 58% of control, respectively – more than an equimolar amounts of either ligand alone (Durbin et al., 1989b; 1997a, 2000a; Gorden et al., 2003). Crystals of uranyl chelates with the set of linear tetradentate Me–3,2‐HOPO ligands demonstrate a 1:1 structure and show that those ligands bind in a nearly planar ring perpendicular to the plane of the dioxo oxygens (Fig. 31.19) (Xu and Raymond, 1999).

Actinides in animals and man

3422

Fig. 31.19 Molecular structure of UO2[5‐LI(Me‐3,2,‐HOPO)] (Xu and Raymond, 1999).

(f)

Ligands for NpOþ 2

As noted above in the sections dealing with tissue distribution, circulatory transport, and tissue uptake kinetics, the oxidation state of Np in vivo is uncertain and probably variable. Rapid plasma clearance and substantial uri2þ nary excretion of NpOþ 2 resemble the behavior of UO2 , while the deposition in the skeleton of nearly one‐half of Np taken into blood and its prolonged retention resemble Pu4þ. Redox conditions in vivo range from an oxidizing environment in the lungs to more reducing environments in the tissues. Depending on the oxidation state of the Np introduced into the blood 2þ (Np4þ ; NpOþ 2 ; NpO2 ), the local conditions in the blood and tissues, and the availability of stabilizing bioligands, both reduction of NpOþ 2 and oxidation of Np4þ may be expected (Duffield and Taylor, 1986; NCRP, 1988; Taylor, 1998). 4þ The complexes formed by NpOþ are about as 2 are weak, while those of Np 4þ stable as those of Pu with the same ligands (Table 31.8). CaNa3–DTPA was injected ip at ligand:Np molar ratios 50 in rats that had been injected iv with 237Np or 239Np citrate solutions (oxidation states uncertain). Excretion of both Np isotopes was increased, the Np content of liver and kidneys was reduced, but there was little reduction in skeleton Np (Smith, 1972b). Effective reduction of 239Np in the body of rats was achieved by ip injection of octadentate 3,4,3‐LICAM(C), given at very large ligand:Np molar ratios 1 h after iv injection of 239NpO2NO3. But similarly to the experience with in vivo chelation of Pu4þ by that ligand, the Np complex formed in the blood partially dissociated leaving a residue of Np in the kidneys (Volf and Wirth, 1986). These observations were taken as an indication of the presence in vivo of chelatable Np4þ. Based on that encouraging result, a systematic investigation was undertaken of the in vivo chelation of Np by a set of representative multidentate ligands. The ligands assessed for Np chelation were tetra‐, hexa‐, and octadentate with linear or branched backbones containing CAM(C), CAM(S), 1,2‐HOPO, or Me‐3,2‐ HOPO binding groups. Mice were injected ip with a ligand (30 mmol kg
1,

of Materials on actinide biology

3423

ligand:Np molar ratio 22) 5 min after the iv injection of 237NpO2Cl (see Fig. 31.12) and killed at 24 h. All 10 test ligands, but not CaNa3–DTPA, significantly reduced body Np, regardless of denticity or the identity of the binding group. Most ligands significantly reduced Np in the liver, and except for 3,4,3‐LICAM (C), also in the kidneys. Significant reduction of Np in the skeleton was also achieved with tetradentate 5‐LIO(Me‐3,2‐HOPO) and 5‐LI(Me‐3,2‐HOPO), and octadentate H(2,2)‐(1,2‐HOPO), H(2,2)‐(Me‐3,2‐HOPO), and 3,4,3‐ LICAM(C). Except for tetradentate 5‐LI(Me‐3,2‐HOPO), which was orally active at lower dose, ligand:Np molar ratios 22 were required to obtain significant reductions in body Np, when the test ligands were given orally at 5 min (Durbin et al., 1994, 1998a,b). Experiments were undertaken to examine the efficacy of 3,4,3‐LI(1,2‐HOPO) for in vivo chelation of 237Np in contaminated wounds in rats. Ligand:Np molar ratios ranged from 4.3 to 285. Early infiltration of the wound site with the ligand was effective, but delayed treatments were progressively less effective. 3,4,3‐LI (1,2‐HOPO) was able to complex the Np at the wound site before it was translocated to blood, but Np deposited in the tissues became progressively less accessible to the ligand (Paquet et al., 1997, 2000). Based on the combined considerations of ligand efficacy and acute ligand toxicity, the most promising ligands for in vivo chelation of Np are in order: tetradentate 5‐LIO(Me‐3,2‐HOPO) and 5‐LI(Me‐3,2‐HOPO), octadentate 3,4,3‐LI(1,2‐HOPO), and hexadentate TREN‐(Me‐3,2‐HOPO). ACKNOWLEDGMENTS

The author wishes to thank the following members of the Lawrence Berkeley National Laboratory, Chemical Sciences Division, for their essential contributions to the preparation of this manuscript: Dr. Wayne W. Lukens, Jr. for the speciation calculations for UO2þ and NpOþ 2 2 in blood plasma; Lindarae M. Aubert and Lynne A. Dory for manuscript preparation; and Dr. Norman M. Edelstein for his patience and assistance. Flavio Robles of the Creative Services Group and Dr. Jide Xu of the U. C. Department of Chemistry provided the illustrations.

APPENDIX: SOURCES OF MATERIALS ON ACTINIDE BIOLOGY

The pioneering biological studies with actinides conducted during World War II (1942–1946) encompassed the following: pharmacology and toxicology of injected, ingested, and inhaled uranium compounds (Tannenbaum, 1951a,b; Voegtlin and Hodge, 1949, 1953); biokinetics of injected and ingested fission products, plutonium, and actinide fission by‐products (Lanz et al., 1946; 1947a,b, 1948a,b, 1949b; Carritt et al., 1947; Finkle et al., 1946; Hamilton,

3424

Actinides in animals and man

1947b, 1948c); acute toxicity of injected fission products and plutonium (Painter et al., 1946; Bloom, 1948; Fink, 1950); biokinetics and acute toxicity of inhaled or intratracheally intubated fission products and plutonium (Abrams et al., 1946a,b, 1947; Scott et al., 1947b, 1949a). Stannard (1988) summarized the designs and major findings of those studies and provided the tables of contents for the otherwise unpublished Plutonium Project documents and reports. Actinide biology summaries and reviews include: General reviews – (Durbin, 1960, 1962), Finkel and Biskis (1968), Stover and Jee (1972), Nenot and Stather (1979), ICRP (1972, 1986), Duffield and Taylor (1986), Stannard (1988), Thompson (1989); Element‐specific reviews, uranium – Hursh and Spoor (1973), Yuile (1973), Durbin and Wrenn (1975); neptunium – Thompson (1982), NCRP (1988); plutonium – Bair et al. (1973), Vaughan et al. (1973), Bair (1974), Durbin (1975); transplutonium elements – Durbin (1973); conference proceedings – Rosenthal (1956), Dougherty et al., 1962), Thompson (1962), Mays et al. (1969), Thompson and Bair (1972), Healy (1975), Wrenn (1975), Jee (1976), Wrenn (1981), Gerber et al. (1989), Stather and Karaoglou (1994), Me´tivier et al. (1998), Stather et al. (2003); databases compiled for radiation protection guidance – ICRP (1959, 1972, 1979, 1980, 1986). The bibliographies of three reports dealing with the deposition and biological effects of plutonium and other selected radionuclides provide an introduction to the large research program on internally deposited radionuclides undertaken in the USSR (Buldakov et al., 1969; Moskalev et al., 1969; Moskalev, 1972).

LIST OF ABBREVIATIONS

CN d DFO DTPA EB ECF EDTA GI h HAP HEPES ICRP im ip ISW iv min NCRP

coordination number days desferrioxamine diethylenetriaminepentaacetic acid enterobactin extracellular fluid ethylenediaminetetraacetic acid gastrointestinal hours synthetic hydroxyapatite 4‐(2‐hydroxyethyl)1‐piperazine ethanesulfonic acid International Commission on Radiological Protection intramuscular intraperitoneal interstitial water intravenous minutes National Council on Radiation Protection

References PAS r s sc Tf tris y

3425

periodic‐acid Schiff ionic radius seconds subcutaneous transferrin tris‐(hydroxy methyl) aminomethane hydrochloride years

REFERENCES Abrams, R., Seibert, H. C., Forker, L., Greenberg, D., Lisco, H., Jacobson, L. O., and Simmons, E. L. (1946a) Acute Toxicity of Intubated Plutonium, USAEC, CH-3875. Abrams, R., Seibert, H. C., Potts, A. M., Lohr, W., and Postel, S. (1946b) Metabolism of Inhaled Fission Products, CH-3485 MDDC-248. Abrams, R., Seibert, H. C., Potts, A. M., Forker, L. L., Greenberg, D., Postel, S., and Lohr, W. (1947) Metabolism and Distribution of Inhaled Plutonium in Rats CH-3655 MDDC-677. Ahrland, S. (1986) Solution chemistry and kinetics of ionic reactions, in The Chemistry of the Actinide Elements (eds. J. J. Katz, G. T. Seaborg, and L. R. Morss), Chapman and Hall, London, pp. 1480–546. Aisen, P. and Listowsky, I. (1980) Ann. Rev. Biochem., 49, 357–93. Altman, P. L. and Dittmer, D. S. (1971) Blood and Other Body Fluids, Federation of American Societies for Experimental Biology, Bethesda, MD. Ansoborlo, E., Chiappini, R., and Moulin, V. (2003) Clefs CEA, 48, 14–18. Arnold, J. S. and Jee, W. S. S. (1957) Am. J. Anat., 101, 367–418. Arnold, J. S. and Jee, W. S. S. (1959) Lab. Invest. 8, 194–204. Arnold, J. S. and Jee, W. S. S. (1962) Health Phys., 8, 705–8. Arnold, J. S. and Wei, C.‐T. (1972) Quantitative morphology of vertebral trabecular bone, in Radiobiology of Plutonium (eds. B. J. Stover and W. S. S. Jee), The J. W. Press, University of Utah, pp. 333–54. Atherton, D. R. and LLoyd, R. D. (1972) Health Phys., 22, 675–8. Atherton, D. A., Bruenger, F. W., and Stevens, W. (1974) On the early retention and distribution of 253Es by the beagle, in Research in Radiobiology, University of Utah School of Medicine Annual Report COO-119-249, pp. 247–54. Atherton, D. A., Stevens, W., and Bruenger, F. W. (1973) Early retention and distribution of curium in soft tissues and blood of the beagle, in Research in Radiobiology, University of Utah School of Medicine Annual Report COO-119-248, pp. 178–85. Axelrod, D. (1947) Anat. Rec., 98, 19–24. Bair, W. J. (1974) Toxicology of plutonium, in Advances in Radiation Biology, vol. 4, Academic press, New York, pp. 255–315. Bair, W. J., Ballou, J. E., Park, J. F., and Sanders, C. L. (1973) Plutonium in soft tissue with emphasis on the respiratory tract, in Uranium, Plutonium, Transplutonic Elements (eds. H. C. Hodge, J. N. Stannard, and J. B. Hursh), Springer‐Verlag, New York, pp. 503–68. Ballatori, N. (1991) Drug Metabol. Rev., 23, 83–132.

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Volf, V., Burgada, R., Raymond, K. N., and Durbin, P. W. (1996b) Int. J. Radiat. Biol., 70, 109–14. White, D. L., Durbin, P. W., Jeung, N., and Raymond, K. N. (1988) J. Med. Chem., 31, 11–18. Williamson, M. and Vaughan, J. (1964) A preliminary report on the sites of deposition of Y, Am, and Pu in cortical bone and in the region of the epiphyeal cartiledge plate, in Bone and Tooth (ed. H. J. J. Blackwood), Pergamon Press, London. Wills, J. H. (1949) Characteristics of uranium poisoning, in Pharmacology and Toxicology of Uranium Compounds, vol. 1 (eds. C. Voegtlin and H. C. Hodge), McGraw‐Hill, New York, pp. 237–280. Winter, R. and Seidel, A. (1982) Radiat. Res., 89, 113–23. Wirth, R. and Volf, V. (1984) Int. J. Radiat. Biol., 46, 787–92. Wirth, R., Taylor, D. M., and Duffield, J. (1985) Int. J. Nucl. Med. Biol., 12, 327–30. Wong, N. L., Reitzik, M., and Quamme, G. A. (1986) Renal Physiol., 9, 29–37. Wood, R., Sharp, C., Gourmelon, P., Le Guen, B., Stradling, G. N., Taylor, D. M., and Henge´‐Napoli, M.‐H. (2000) Radiat. Protect. Dosim., 87, 51–6. Wrenn, M. E. (ed.) (1975) Conference on Occupational Health Experience with Uranium, ERDA Report 93. Wrenn, M. E. (ed.) (1981) Actinides in Man and Animals, RD Press, University of Utah, Salt Lake City. Wrenn, M. E., Durbin, P. W., Howard, B., Lipsztein, J., Rundo, J., Still, E. T., and Willis, D. L. (1985) Health Phys., 48, 601–33. Wronski, T. J., Smith, J. M., and Jee, W. S. (1980) Radiat. Res., 83, 74–89. Xu, J. D. and Raymond, K. N. (1999) Inorg. Chem., 38, 308–15. Xu, J., Kullgren, B., Durbin, P. W., and Raymond, K. N. (1995) J. Med. Chem., 38, 2606–14. Xu, J., Radkov, E., Ziegler, M., and Raymond, K. N. (2000) Inorg. Chem., 39, 4156–64. Xu, J., Durbin, P. W., and Raymond, K. N. (2001) Actinide sequestering agents: design, structural, and biological evaluations, in Nuclear Science – Evaluation of Speciation Technology – Workshop Proceedings Tokai-mura, Ibaraki, Japan, 26-28 October 1999, OECD, pp. 247–54. Xu, J., Durbin, P. W., Kullgren, B., Ebbe, S. N., Uhlir, L. C., and Raymond, K. N. (2002) J. Med. Chem., 45, 3963–71. Xu, J. D., Whisenhunt, D. W., Veeck, A. C., Uhlir, L. C., and Raymond, K. N. (2003) Inorg. Chem., 42, 2665–74. Youmans, W. B. and Siebens, A. A. (1973) ‘Respiration’ in Best and Taylor’s Physiological Basis of Medical Practice, 9th edition, (Brobeck, J. R., ed.), pp. 6–1 to 6–90, The Williams and Wilkins Co., Baltimore. Yuile, C. L. (1973) Animal experiments, in Uranium, Plutonium, Transplutonic Elements (eds. H. C. Hodge, J. N. Stannard, and J. B. Hursh), Springer‐Verlag, New York, pp. 165–96. Zak, O. and Aisen, P. (1988) Biochemistry, 27, 1075–80. Zhu, D.-H., Kappel, M. J., and Raymond, K. N. (1988) Inorg. Chim. Acta, 147, 115–21. Zirkle, R. E. (1947) Radiology, 49, pp. 269–365.

APPENDIX I

NUCLEAR SPINS AND MOMENTS OF THE ACTINIDES Nuclear spins and nuclear moments are used to test the single‐particle models and nuclear quadrupole moments provide the deformation of the nucleus. In the following table, we present measured values of ground state spin in units of h, magnetic dipole moment (m) in units of nuclear magneton, and spectroscopic
quadrupole moment (Q) in units of barns. The data have been taken from Raghavan (1989) and Firestone and Shirley (1996).

Nuclide 217

Ac Ac 229 Th 228 Pa 230 Pa 231 Pa 233 Pa 233 U 235 U 237 Np 238 Np 239 Np 239 Pu 241 Pu 241 Am 242 Am 242m Am 243 Am 243 Cm 245 Cm 247 Cm 249 Bk 249 Cf 253 Es 254m Es 227

Nuclear spin (ħ)

Nuclear magnetic moment (nuclear magneton)

9/2 3/2 5/2 3 2 3/2 3/2 5/2 7/2 5/2 2 5/2 1/2 5/2 5/2 1 5 5/2 5/2 7/2 9/2 7/2 9/2 7/2 2

þ3.825(45) þ1.1(1) þ0.46(4) þ3.48(33) þ2.00(29) þ2.01(2) þ3.39(70) 0.59(5)
0.38(3) þ3.14(4) þ0.203(4)
0.683(15) þ1.61(3) þ0.3879(15) þ1.00(5) þ1.61(4) 0.41 0.5 (1) 0.37 2.0(4)
0.28 þ4.10(7) 2.90(7)

Electric quadrupole moment (barns) þ1.7(2) þ4.3(9) –1.72(5)
3.0 3.663(8) 4.936(6) þ3.886(6)

þ5.6(20) þ4.2(13)
2.4(7) þ6.5(20) þ4.30(3)

þ5.79 6.7(8) 3.7(5)

Firestone, R.B. and Shirley, V.S. (eds.) (1996). Table of Isotopes, 8th edn. John Wiley, New York. Raghavan, P. (1989) At. Nucl. Data Tables, 42, 189–291.

3441

APPENDIX II

NUCLEAR PROPERTIES OF ACTINIDE AND TRANSACTINIDE NUCLIDES Irshad Ahmad

DISCUSSION

In this appendix, an elementary discussion of the nuclear properties of heavy elements is presented. For a better understanding of the subject, the reader should refer to nuclear chemistry textbooks (Krane, 1988; Choppin et al., 2002) and for the information on decay data, the Table of Isotopes (Firestone and Shirley, 1996) or the Table of Radioactive Isotopes (Browne and Firestone, 1986) or Nuclear Data Sheets (Tuli, 2004) should be consulted. Isotopes of all elements with Z  89 are radioactive. The most common mode of decay for these nuclei is by the emission of alpha particles (4He ions). Alpha decay energies have been experimentally measured (Browne and Firestone, 1986; Firestone and Shirley, 1996) for most nuclides and these can also be calculated from atomic masses (Wapstra et al., 2003). The a decay of a nucleus with atomic number Z and atomic mass A produces a daughter nucleus with atomic number Z–2 and atomic mass A–4. During the a decay, about 2% of the available decay energy is imparted to the recoiling daughter nucleus and the remaining energy is carried off by the fast moving a‐particle. Several groups of a‐particles are emitted by a sample of a nuclide, each with a definite energy. For the actinide nuclides, a‐particle energies range from about 4 to 11 MeV. As a rule, a‐particle energy increases with increasing Z, and for a given element, it decreases with increasing mass number. The a‐decay half‐life decreases exponentially with increasing energy. As a guide, every 50 keV increase in the decay energy reduces the half‐life by a factor of 2. The dependence of the a‐decay half‐life on the decay energy is given by the well‐known Geiger–Nuttall law and more recently by Viola–Seaborg formula. A very useful quantity that facilitates the understanding of the mechanism of a‐decay is the concept of hindrance factor. It is defined as the ratio of the experimental partial a‐decay half‐life to the theoretical half‐life calculated on the assumption that the a‐particle pre‐exists in the nucleus and during its emission, it carries no angular momentum. An alpha transition in which the 3442

Nuclear properties of actinide and transactinide nuclides

3443

ground state configuration of the parent nucleus remains unchanged is called ‘favored transition’. All alpha transitions between the ground states of even– even nuclei are favored transitions and are assigned a hindrance factor of one. Like elements of lower Z, each actinide element has one or more b‐stable isotopes. Isotopes heavier than the b‐stable isotope decay by the emission of b
particles (electrons) and isotopes lighter than the b‐stable isotopes decay by electron capture (EC). Electron capture decay is usually accompanied by the emission of K x‐rays of the daughter nuclide. These x‐rays provide a signature of the decaying nuclide. In heavy nuclei, bþ/EC ratio is very small and, as a consequence, positron (bþ) emission has been observed only in a few nuclei. The b‐decay energy increases as the mass of the isotope gets further away from the line of b‐stability. A quantity denoted by log ft is very useful in classifying the b transitions and estimating the b‐decay half‐lives of unknown nuclei. The ft value, also called the reduced b transition probability, is the energy‐independent transition rate. Spontaneous fission is a decay process in which a nucleus breaks up into two almost equal fragments. Each fission event is accompanied by the release of about 200 MeV energy and the emission of two to four neutrons. More than hundred nuclides are produced in fission of a nuclide sample and the mass yields and charge distributions have been measured for many fissioning systems (Wahl, 1989; Ahmad and Phillips, 1995). The fission half‐life depends on the fissility parameter Z2/A and is the major decay mode for many isotopes of element 100 and beyond. Nuclides with reasonable fission branch and available for experiments and industrial use are 248Cm (t1/2 ¼ 3.40 105 years) and 252Cf (t1/2 ¼ 2.64 years). The isotope 252Cf is widely used as a neutron source in industry and research. Another rare mode of decay for heavy elements is the decay by the emission of intermediate mass fragments. These fragments are heavier than a particles but smaller than fission fragments. The branching ratio for this kind of radioactivity is extremely small (10
10). Examples of such radioactivity are the 24Ne emission by 231Pa and 232U (Price, 1989). Alpha and b transitions usually populate excited states in addition to the ground states of the daughter nuclei. The excited states then decay to the ground state by emission of g rays and conversion electrons. Typical half‐lives of the excited states range from 10
9 to 10
14 s. However, in some cases, the decay of an excited state is forbidden for fast magnetic dipole (M1), electric dipole (E1), or electric quadrupole (E2) transitions because of the angular momentum selection rule. Such states have half‐lives between nanoseconds and years. An excited state that has a half‐life value greater than a nanosecond is called a ‘metastable’ state or ‘isomer’. The isomeric state either de‐excites to the ground state of the same nucleus by an internal transition (IT) or it decays by the usual mode of disintegration. Most isomers occur because of the large difference between the spins of the excited state and the ground state. However, there are isomers which result not

3444

Discussion

by the difference in the spins of the states but by the difference in the shapes. These isomers decay by fission and are called ‘fission isomers’ or ‘shape isomers’ and have half‐lives between 10
9 and 10
3 s. These isomers have deformations that are twice as large as the deformations of the ground states. More than 50 fission isomers have been discovered (Vandenbosch, 1977). Very neutron‐deficient nuclides decay predominantly by electron capture (EC). In some of these nuclei, the EC decay energy is quite large (> 4 MeV) and hence states at high excitation energy are populated in the daughter nucleus and a small fraction of these excited states decay by fission. Delayed fission of many nuclei has been observed (Hall and Hoffman, 1992). Nuclear structure studies of actinide nuclides have been performed using a variety of techniques. These include high‐resolution alpha, electron and gamma‐ray spectroscopy, charged‐particle transfer reaction spectroscopy, and Coulomb excitation studies. These investigations have provided significant information on the shape, size, and single‐particle potential of actinide nuclei. The available data establish a spheroidal shape for nuclei with A  225, with major to minor axes ratio of 1.25. The intrinsic quadrupole moments of actinide nuclei have been measured to be about 10–23 e cm2 and the nuclear radii are about 10
12 cm. Although most actinide nuclei have spheroidal shapes, there are indications that some neutron‐deficient Ac and Pa nuclei have small octupole deformation in their ground states. These nuclei are pear‐shaped and are axially symmetric but they are reflection asymmetric. Examples of such nuclei are 229Pa and 225Ac (Ahmad and Butler, 1993). In nuclei, nucleons (neutrons and protons) move in orbits under the influence of the central nuclear potential. Nilsson (1955) and others (Chasman et al., 1977) have calculated the eigenvalues and eigenfunctions of nucleons in a deformed potential as a function of the deformation b. Plots of the eigenvalues versus the deformation, commonly known as Nilsson diagrams, are extremely useful in understanding the single‐particle properties of actinide nuclei. Each Nilsson state is characterized by a set of quantum numbers O p, N, Nz, and L. The quantum number O is the projection of the single‐particle angular momentum on the nuclear symmetry axis and p is the parity of the wavefunction. The asymptotic quantum numbers N, Nz and L denote the oscillator shell number, the number of the oscillator quanta along the symmetry axis, and the projection of the orbital angular momentum on the symmetry axis, respectively. In heavy nuclei, neutrons (protons) fill each orbital above the closed shell of 126 (82) pairwise and thus the ground state of an odd‐mass nucleus is simply the orbital occupied by the last unpaired nucleon. All even–even nuclei have ground state spin‐parity of 0þ. A spheroidal nucleus rotates about an axis perpendicular to the nuclear symmetry axis. The projection, K, of the total angular momentum, I, on the symmetry axis is the same as O. The rotation of a spheroidal nucleus generates a rotational band with spin sequence K, Kþ1, Kþ2, . . . . The

Nuclear properties of actinide and transactinide nuclides

3445

rotational energy EI of a level with spin I is given by the expression EI ¼

h
2 IðI þ 1Þ; 2=

where
h is Planck’s constant and = is the nuclear moment of inertia. Typical values of
h2/2= are 7.0 keV for even–even actinide nuclei and 6.0 keV for odd‐ mass nuclei. The ground state band of an even–even nucleus has spin‐parity sequence 0þ, 2þ, 4þ . . .; odd spin values are not allowed. Qualitative and quantitative analysis of actinide samples can be performed by using a variety of techniques (Knoll, 2000). Gross counting with a 2p (50%) geometry gas proportional counter can be used to determine the a or b
count rate in a sample. These counters have very low background for a particles but somewhat higher background for electrons. Background of 0.1 a count per minute can be easily achieved for these counters. Alpha pulse height analysis can be used to identify nuclides in a sample. Alpha spectra are measured either by Au–Si surface barrier detectors or passivated implanted planar silicon (PIPS) detectors. For best resolution (full width at half maximum), which can be as low as 9.0 keV, extremely thin sources are required. Precise energies and intensities of alpha groups have been tabulated by Ritz (1991). Gamma‐ray spectroscopy with high‐resolution germanium spectrometers provides a powerful technique for qualitative and quantitative analysis of actinide samples. For high‐energy g rays in the range of 200 keV to 1.5 MeV, large volume Ge detectors provide the best sensitivity. Resolutions (FWHM) of less than 2.0 keV at the 60Co 1332.5 keV line are easily achieved. In actinide nuclei, K x‐ray energies lie in the 80–160 keV range and can be measured with high‐resolution low-energy planar spectrometers (LEPS). K x‐rays are produced when a vacancy in the K shell of an atom, created by electron capture or internal conversion, is filled by an electron from a higher shell. These K x‐rays energies depend on the atomic number and there is sufficient separation between the energies of adjacent elements for them to be clearly identified. The Cm K x‐ray spectrum produced in the alpha decay of 251Cf and measured with a high‐ resolution LEPS is displayed in Fig. A.2.1. The resolution (FWHM) of the spectrometer is about 500 eV. Measurements of gamma ray spectrum and K x‐ray spectrum are very useful in identifying and quantifying odd‐mass nuclei. L x‐rays of actinide nuclei, which are produced when a vacancy in the L subshell of an atom is filled by an electron from a higher shell, have energies in the 10–30 keV range. Spectra of L x‐rays can be measured with lithium‐ drifted silicon, Si(Li), detectors with resolutions (FWHM) of 300 eV. A Np L x‐ray spectrum from 241Am alpha decay, measured with a Si(Li) spectrometer, is shown in Fig. A.2.2. These spectra are also characteristic of the element but are more complex. The definition of x‐ray components is given in (Firestone and Shirley, 1996). Even–even nuclei decay to excited levels of daughter nuclei which de‐excite by highly L converted transitions generating L x‐rays. Thus even–even

3446

Discussion

Fig. A.2.1 K X‐ray spectrum of Cm, produced in the alpha decay of a 2 cm2 1 cm LEPS spectrometer.

251

Cf, measured with

nuclei, which do not have any intense g rays, can be analyzed by L X‐ray spectroscopy. Fissioning nuclides like 252Cf can be assayed by measuring the gamma‐ray spectrum with large‐volume Ge detectors and using the intensities of gamma rays emitted in the decay of the abundant fission fragments (Ahmad et al., 2003). Some actinide nuclides have very long half‐lives and hence they occur in nature. These include 232Th, 235U and 238U which decay through a series of isotopes terminating at stable Pb isotopes. Isotopes of Ac, Th, and Pa are usually separated from the parent nuclides and used in the chemical and nuclear studies of these elements. Transuranium isotopes are produced by long irradiations in nuclear reactors. In the US, there is a national program for the production and isolation of transuranium isotopes utilizing the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory. The heaviest nuclide produced in this program is the 100 day 257Fm. Neutron‐deficient actinide isotopes are usually produced by nuclear reactions in charged particle accelerators. All data in the tables of nuclear properties given in the preceding chapters and in this appendix have been taken from Browne and Firestone (1986), Firestone and Shirley (1996), Nuclear Data Sheets (Tuli, 2004) and from the

Nuclear properties of actinide and transactinide nuclides

Fig. A.2.2 L X‐ray spectrum of Np, produced in the alpha decay of a 1 cm diameter and 5 mm thick Si(Li) detector.

241

3447

Am, measured with

web sites at the Isotope Project, Lawrence National Berkeley Laboratory (http://www.lbl.gov) and at the Nuclear Data Center, Brookhaven National Laboratory (http://www.nndc.bnl.gov). For the heaviest elements, data were taken from Armbruster (2000) and Hofmann and Mu¨nzenberg (2000). The cut‐off date for literature survey was June 2004. The notations for decay modes in the tables are: a for alpha decay, b
for b
decay, bþ for positron decay, EC for electron capture decay, IT for isomeric transition, and SF for spontaneous fission. The letter m after a mass number represents an isomer. Isomers with half‐lives of less than 1 s (except for the heaviest elements) and fission isomers are omitted from the tables. Energies and intensities are given for the most abundant a groups and most intense g rays; for b
particles, the maximum energy bmax is given. In the last column of Table A2.1, only the convenient methods of production are given; ‘nature’ denotes that the nuclide occurs in nature and ‘multiple neutron capture’ means that the nucleus is produced by multiple neutron capture in a high‐flux reactor such as HFIR. The specific activity S in disintegrations per minute per microgram was calculated using the expression S¼

4:17449 1017 ; t1=2 A

3448

References

where t1/2 is half‐life of the nuclide in minutes and A is the atomic mass in atomic mass units. The half‐lives and atomic masses were taken from the references mentioned earlier in this text.

REFERENCES Ahmad, I. and Butler, P. A. (1993) Annu. Rev. Nucl. Part. Sci., 43, 71–117. Ahmad, I. and Phillips, W. R. (1995) Rep. Prog. Phys., 58, 1415–63. Ahmad, I., Moore, E. F., Greene, J. P., Porter, C. E., and Felker, L. K. (2003) Nucl. Instrum. Methods, A505, 389–92. Armbruster, P. (2000) Annu. Rev. Nucl. Part. Sci., 50, 411–79. Browne, E. and Firestone, R. B. (1986) Table of Radioactive Isotopes (ed. V. S. Shirley), John Wiley, New York. Chasman, R. R., Ahmad, I., Friedman, A. M., and Erskine, J. R. (1977) Rev. Mod. Phys., 49, 833–91. Choppin, G. R., Liljenzin, J.‐O., and Rydberg, J. (2002) Radiochemistry and Nuclear Chemistry, 3rd edn., Butterworth‐Heinemann, Woburn. Firestone, R. B. and Shirley, V. S. (eds.) (1996) Table of Isotopes, 8th edn., John Wiley, New York. Hall, H. L. and Hoffman, D. C. (1992) Annu. Rev. Nucl. Part. Sci., 42, 147–75. Hofmann, S. and Mu¨nzenburg, G. (2000) Rev. Mod. Phys., 72, 733–67. Knoll, G. F. (2000) Radiation Detection and Measurement, John Wiley, New York. Krane, K. S. (1988) Introductory Nuclear Physics, John Wiley, New York. Nilsson, S. G. (1955) Kgl. Dansk Videnskab. Selskab. Matt.‐Fys. Medd., 29, 16. Price, P. B. (1989) Annu. Rev. Nucl. Part. Sci., 39, 19–42. Ritz, A. (1991). At. Data Nucl. Data Tables, 47, 205–39. Tuli, (ed.) J. K. (2004) Nuclear Data Sheets, Academic Press, San Diego, CA. Vandenbosch, R. (1977) Annu. Rev. Nucl. Sci., 27, 1–35. Wahl, A. C. (1989) At. Nucl. Data Tables, 39, 1–156. Wapstra, A. H., Audi, G., and Thibault, C. (2003) Nucl. Phys., A729, 129–336.

3449 TABLES

In the following tables we reproduce the tables in each of the chapters 2 through 14 that contain the nuclear properties of the actinide and transactinide isotopes. We then give a table of specific activities of these isotopes.

Nuclear properties of actinium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

a a a a a a a

a 7.750 a 7.790 a 7.712 a 7.572 a 7.758 a 7.59 a 7.46

175

Lu(40Ar,9n)

175

Lu(40Ar,8n) Lu(40Ar,7n)

209 210

33 ms 22 ms 22 ms 95 ms 25 ms 0.10 s 0.35 s

211

0.25 s

a

a 7.48

212

0.93 s

a

a 7.38

213

0.80 s

a

a 7.36

214

8.2 s

215

0.17 s

a 7.214 (52%) 7.082 (44%) a 7.604

216 216 m

0.33 ms 0.33 ms

a  86% EC 14% a 99.91% EC 0.09% a a

217 218 219 220

69 ns 1.08 ms 11.8 ms 26.4 ms

a a a a

221

52 ms

a

222

5.0 s

a

222 m

63 s

223

2.10 min

224

2.78 h

a > 90% EC  1% IT < 10% a 99% EC 1% EC  90% a  10%

206 207 208

a 9.072 a 9.108 (46%) 9.030 (50%) a 9.650 a 9.20 a 8.66 a 7.85 (24%) 7.68 (21%) 7.61 (23%) a 7.65 (70%) 7.44 (20%) a 7.00 a 7.00 (15%) 6.81 (27%) a 6.662 (32%) 6.647 (45%) a 6.211 (20%) 6.139 (26%)

175 197

Au(20Ne,8n) Au(20Ne,7n) 203 Tl(16O,9n) 197 Au(20Ne,6n) 203 Tl(16O,8n) 203 Tl(16O,7n) 197 Au(20Ne,5n) 197 Au(20Ne,4n) 203 Tl(16O,6n) 203 Tl(16O,5n) 197 Au(20Ne,3n) 203 Tl(16O,4n) 209 Bi(12C,6n) 209 Bi(12C,5n) 197

208

Pb(14N,5n) Pa daughter 223 Pa daughter 208 Pb(15N,3n) 224 Pa daughter 222

205

Tl(22Ne,a2n) Pb(18O,p4n) 226 Ra(p,5n) 208 Pb(18O,p3n) 208 Pb(18O,p3n) 209 Bi(18O,an) 208

227

Pa daughter

228

Pa daughter

3450 Nuclear properties of actinium isotopes. (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

225

10.0 d

a

225

Ra daughter

226

29.37 h

226

Ra(d,2n)

227

21.772 yr

b
83% EC 17% a 6 10
3% b
98.62% a 1.38%

228

6.15 h

b


229

62.7 min

b


230

122 s

b


231

7.5 min

b


232 233 234

119 s 145 s 44 s

b
b
b


a 5.830 (51%) 5.794 (24%) g 0.100 (1.7%) a 5.399 b
1.10 g 0.230 (27%) a 4.950 (47%) 4.938 (40%) b
0.045 g 0.086 b
2.18 g 0.991 b
1.09 g 0.165 b
1.4 g 0.455 b
2.1 g 0.282

nature

nature 229

Ra daughter Th(g,p2n) 232 Th(g,pn) 232

232

Th(g,p) Th(n,pn) 238 U þ Ta 238 U þ Ta 238 U þ Ta 232

Nuclear properties of thorium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

209 210 211 212 213 214 215

3.8 ms 9 ms 37 ms 30 ms 140 ms 100 ms 1.2 s

a a a a a a a

32

216 217 218

28 ms 0.237 ms 0.109 ms

a a a

a 8.080 a 7.899 a 7.792 a 7.82 a 7.691 a 7.686 a 7.52 (40%) 7.39 (52%) a 7.92 a 9.261 a 9.665

219 220 221

1.05 ms 9.7 ms 1.68 ms

a a a

222

2.8 ms

a

a 9.34 a 8.79 a 8.472 (32%) 8.146 (62%) a 7.98

S þ 182W Cl þ 181Ta 35 Cl þ 181Ta 176 Hf(40Ar,4n) 206 Pb(16O,9n) 206 Pb(16O,8n) 206 Pb(16O,7n) 35

206

Pb(16O,6n) Pb(16O,5n) 206 Pb(16O,4n) 209 Bi(14N,5n) 206 Pb(16O,3n) 208 Pb(16O,4n) 208 Pb(16O,3n) 206

208

Pb(16O,2n)

3451 Nuclear properties of thorium isotopes. (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

223

0.60 s

a

208

Pb(18O,3n)

224

1.05 s

a

228

U daughter Pb(22Ne,a2n)

225

8.0 min

a  90% EC  10%

226

30.57 min

a

227

18.68 d

a

228

1.9116 yr

a

229

7.340 103 yr

a

230

7.538 104 yr

a

231

25.52 h

b


232 233

1.405 1010 yr > 1 1021 yr 22.3 min

a SF b


234

24.10 d

b


235 236

7.1 min 37.5 min

b
b


a 7.32 (40%) 7.29 (60%) a 7.17 (81%) 7.00 (19%) g 0.177 a 6.478 (43%) 6.441 (15%) g 0.321 a 6.335 (79%) 6.225 (19%) g 0.1113 a 6.038 (25%) 5.978 (23%) g 0.236 a 5.423 (72.7%) 5.341 (26.7%) g 0.084 a 4.901 (11%) 4.845 (56%) g 0.194 a 4.687 (76.3%) 4.621 (23.4%) g 0.068 b
0.302 g 0.084 a 4.016 (77%) 3.957 (23%) b
1.23 g 0.086 b
0.198 g 0.093

237 238

5.0 min 9.4 min

b
b


g 0.111

208 229 231 230

U daughter Pa(p,a3n) U daughter

nature nature 233

U daughter

nature nature Th(n,g) nature

230

232

Th(n,g)

nature 238

U(n,a) U(g,2p) 238 U(p,3p) 18 O þ 238U 18 O þ 238U 238

Nuclear properties of protactinium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

212 213 214

5.1 ms 5.3 ms 17 ms

a a a

a 8.270 a 8.236 a 8.116

182

W(35Cl,5n) Er(51V,8n) 170 Er(51V,7n) 170

3452 Nuclear properties of protactinium isotopes. (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

a a a a a a a a a

223

6 ms

a

224 225

0.9 s 1.8 s

a a

226

1.8 min

227

38.3 min

a 74% EC 26% a 85% EC 15%

228

22 h

EC 98% a 2%

229

1.5 d

230

17.7 d

231

3.28 104 yr

EC 99.5% a 0.48% EC 90% b– 10% a 3.2 10–3% a

232

1.31 d

b–

233

27.0 d

b–

234

6.75 h

b–

234 m

1.175 min

235

24.2 min

b– 99.87% IT 0.13% b–

a 8.170 a 7.865 a 8.340 a 10.160 a 9.614 (65%) a 9.900 a 9.15 a 9.080 a 8.54 (30%) 8.18 (50%) a 8.20 (45%) 8.01 (55%) a 7.49 a 7.25 (70%) 7.20 (30%) a 6.86 (52%) 6.82 (46%) a 6.466 (51%) 6.416 (15%) g 0.065 a 6.105 (12%) 6.078 (21%) g 0.410 a 5.669 (19%) 5.579 (37%) a 5.345 b– 0.51 g 0.952 a 5.012 (25%) 4.951 (23%) g 0.300 b– 1.29 g 0.969 b– 0.568 g 0.312 b– 1.2 g 0.570 b– 2.29 g 1.001 b– 1.41

181

218 219 220 221 222

14 ms 0.2 s 4.9 ms 1.6 ms 0.12 ms 53 ns 0.78 ms 5.9 ms 5.7 ms

236

9.1 min

b–

237

8.7 min

b–

238

2.3 min

b–

239

106 min

b–

215 216 217

b– 3.1 g 0.642 b– 2.3 g 0.854 b– 2.9 g 1.014

Ta(40Ar,6n) Au(24Mg,5n) 181 Ta(40Ar,4n) 197

206

Pb(16O,4n) Pb(19F,4n) 204 Pb(19F,3n) 209 Bi(16O,4n) 209 Bi(16O,3n) 206 Pb(19F,3n) 208 Pb(19F,4n) 205 Tl(22Ne,4n) 208 Pb(19F,3n) 232 Th(p,8n) 209 Bi(22Ne,a2n) 232 Th(p,7n) 204

232

Th(p,6n)

232

Th(p,5n) Th(p,3n)

230 230

Th(d,3n) Th(d,2n) 230 Th(d,2n) 232 Th(p,3n) 229

nature 231

Pa(n,g) Th(d,2n) 233 Th daughter 237 Np daughter nature 232

nature 235

Th daughter U(n,p) 236 U(n,p) 238 U(d,a) 238 U(g,p) 238 U(n,pn) 238 U(n,p) 235

18

O þ 238U

3453 Nuclear properties of uranium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

217 218 219 222 223 224 225 226 227

16 ms 1.5 ms 42 ms 1.0 ms 18 ms 0.9 ms 59 ms 0.35 s 1.1 min

a a a a a a a a a

a 8.005 a 8.625 a 8.680 a 9.500 a 8.780 a 8.470 a 7.879 a 7.430 a 6.87

182

228

9.1 min

a  95% EC 5%

229

58 min

EC  80% a  20%

230

20.8 d

a

231

4.2 d

232

68.9 yr  8 1013 yr

EC > 99% a 5.5 10
3% a SF

233

1.592 105 yr 1.2 1017 yr

a SF

234

2.455 105 yr 2 1016 yr 7.038 108 yr 3.5 1017 yr

a SF a SF

a 6.68 (70%) 6.60 (29%) g 0.152 a 6.360 (64%) 6.332 (20%) g 0.123 a 5.888 (67.5%) 5.818 (31.9%) g 0.072 a 5.46 g 0.084 a 5.320 (68.6%) 5.264 (31.2%) g 0.058 a 4.824 (82.7%) 4.783 (14.9%) g 0.097 a 4.777 (72%) 4.723 (28%) a 4.397 (57%) 4.367 (18%) g 0.186

25 min 2.3415 107 yr 2.43 1016 yr 6.75 d

IT a SF b


239

4.468 109 yr 8.30 1015 yr 23.45 min

a SF b


240

14.1 h

b


242

16.8 min

b


235 235 m 236 237 238

a 4.494 (74%) 4.445 (26%) b
0.519 g 0.060 a 4.196 (77%) 4.149 (23%) b
1.29 g 0.075 b
0.36 g 0.044 b
1.2 g 0.068

W(40Ar,5n) Au(27Al,6n) 197 Au(27Al,5n) W(40Ar,xn) 208 Pb(20Ne,5n) 208 Pb(20Ne,4n) 208 Pb(22Ne,5n) 232 Th(a,10n) 232 Th(a,9n) 208 Pb(22Ne,3n) 232 Th(a,8n) 197

230 232 230 231

Th(3He,4n) Th(a,7n) Pa daughter Pa(d,3n)

230

Th(a,3n) Pa(d,2n) 232 Th(a,4n) 231

233

Pa daughter

nature nature 239 235

Pu daughter U(n,g)

236

U(n,g) Pu daughter nature

241

238

U(n,g)

244

Pu daughter

244

Pu(n,2pn)

3454 Nuclear properties of neptunium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

226 227 228 229

31 ms 0.51 s 61.4 s 4.0 min

a 8.044 a 7.677

209

2.144 106 yr >1 1018 yr

EC, a EC, a EC, a a  50% EC 50% a > 99% EC 0.97% EC < 99% a > 1% EC EC < 99% a10–3% EC 99.95% bþ 0.05% EC > 99% a 1.6 10
3% b
50% EC 50% EC 87% b
13% a SF

230

4.6 min

231

48.8 min

232 233

14.7 min 36.2 min

234

4.4 d

235

396.1 d

236a

22.5 h

236a

1.54 105 yr

237 238

2.117 d

b


239

2.3565 d

b


240

1.032 h

b


240 m

7.22 min

b


241

13.9 min

b


242 g or m

5.5 min

b


242 g or m

2.2 min

b


243 244

1.85 min 2.29 min

b
b


a

Not known whether ground‐state nuclide or isomer.

a 6.890

Bi(22Ne,5n) Bi(22Ne,4n) 209 Bi(22Ne,3n) 233 U(p,5n) 209

a 6.66

233

a 6.28 g 0.371 g 0.327 a 5.54 g 0.312 g 1.559

233

a 5.022 (53%) 5.004 (24%) b
0.54 g 0.642 g 0.163

235

U(d,2n)

235

U(d,n)

235

U(d,n)

a 4.788 (51%) 4.770 (19%) g 0.086 b
1.29 g 0.984 b
0.72 g 0.106 b
2.09 g 0.566 b
2.05 g 0.555 b
1.31 g 0.175 b
2.7 g 0.786 b
2.7 g 0.736 g 0.288 g 0.681

237

U daughter Am daughter

U(p,4n)

U(d,4n) U(d,6n) 233 U(d,3n) 233 U(d,2n) 235 U(d,4n) 235 U(d,3n) 235

241 237

Np(n,g)

243

Am daughter U daughter 238 U(a,pn) 239

240

U daughter U(a, pn) 238 U(a,p) 244 Pu(n,p3n) 244 Pu(n,p2n) 242 Pu(n,p) 242 U daughter 238

136 136

Xe þ 238U Xe þ 238U

3455 Nuclear properties of plutonium isotopes. Mass number

Half‐life

228 229 230 231

1.1 s – 2.6 min 8.6 min

232

33.1 min

233

20.9 min

234

8.8 h

235

25.3 min

236

2.858 yr 1.5 109 yr 45.2 d

237 238

Mode of decay

Main radiations (MeV)

Method of production

a a EC, a EC 90% a 10% EC 80% a 20% EC 99.88% a 0.12% EC 94% a 6% EC > 99.99% a 3 10
3% a SF EC > 99.99% a 4.2 10
3%

a 7.772 a 7.460 a 7.055 a 6.72

198

a 6.600 (62%) 6.542 (38%) a 6.30 g 0.235 a 6.202 (68%) 6.151 (32%) a 5.85 g 0.049 a 5.768 (69%) 5.721 (31%) 5.356 (17.2%) 5.334 (43.5%) g 0.059 a 5.499 (70.9%) 5.457 (29.0%) a 5.157 (70.77%) 5.144 (17.11%) 5.106 (11.94%) g 0.129 a 5.168 (72.8%) 5.123 (27.1%) a 4.896 (83.2%) 4.853 (21.1%) b
0.021 g 0.149 a 4.902 (76.49%) 4.856 (23.48%) b
0.58 g 0.084 a 4.589 (81%) 4.546 (19%) b
0.878 (51%) g 0.327 (25.4%) b
0.15 (91%) g 0.224 (25%)

233

U(a,5n)

233

U(a,4n)

233

U(a,3n)

87.7 yr 4.77 1010 yr 2.411 104 yr 8 1015 yr

a SF a SF

6.561 103 yr 1.15 1011 yr 14.35 yr

a SF b
> 99.99% a 2.4 10
3%

3.75 105 yr 6.77 1010 yr 4.956 h

a SF b


245

8.08 107 yr 6.6 1010 yr 10.5 h

a 99.88% SF b


246

10.84 d

b


239

240 241

242 243 244

247

2.27 d




b

Pt(34S,4n) Pb(26Mg,4n) 208 Pb(26Mg,4n) 233 U(3He,5n) 207

235

U(a,4n) U(a,2n) 235 U(a,3n) 236 Np daughter 235 U(a,2n) 237 Np(d,2n) 233

242

Cm daughter Np daughter 239 Np daughter 238

multiple n capture multiple n capture

multiple n capture multiple n capture multiple n capture 244

Pu(n,g)

multiple n capture multiple n capture

3456 Nuclear properties of americium isotopes. Mass number 232 233 234 235 236

Half‐life

Mode of decay

237 238

1.63 h

239

11.9 h

240

50.8 h

EC > 99% a 1.9 10–4%

241

432.7 yr 1.15 1014 yr

a SF

242

16.01 h

242 m

141 yr 9.5 1011 yr

b
82.7% EC 17.3% IT 99.5% SF a (0.45%)

243

7.38 103 yr 2.0 1014 yr

a SF

244

10.1 h

b


244 m

26 min

245

2.05 h

b
> 99% EC 0.041% b


246a

25.0 min

b


246a

39 min

b


b
0.895 g 0.253 (6.1%) b
2.38 g 0.799 (25%) g 0.679 (52%)

247

24 min

b


g 0.285 (23%)

Not known whether ground‐state nuclide or isomer.

Method of production 230

1.4 min 3.2 min 2.6 min 15 min 4.4 min 3.7 min 1.22 h

a

SF isomer a EC EC EC EC EC > 99% a 0.025% EC > 99% a 1.0 10–4% EC > 99% a 0.010%

Main radiations (MeV ) a 6.780

a 6.042 g 0.280 (47%) a 5.94 g 0.963 (29%) a 5.776 (84%) 5.734 (13.8%) g 0.278 (15%) a 5.378 (87%) 5.337 (12%) g 0.988 (73%) a 5.486 (84%) 5.443 (13.1%) g 0.059 (35.7%) b
0.667 g 0.042 weak a 5.207 (89%) 5.141 (6.0%) g 0.0493 (41%) a 5.277 (88%) 5.234 (10.6%) g 0.075 (68%) b
0.387 g 0.746 (67%) b
1.50

Th(10B, 8n) U(6Li, 6n) 230 Th(10B, 6n) 238 Pu(1H, 4n) 235 U(6Li, 5n) 237 Np(6He, 4n) 237 Np(a, 4n) 237 Np(3He, 3n) 237 Np(a, 3n) 238

237 239 237 239

Np(a, 2n) Pu(d, 2n) Np(a, n) Pu(d, n)

241

Pu daughter multiple n capture

241

Am(n, g)

241

Am(n, g) Am(n, g)

241

multiple n capture 243

Am(n, g)

243

Am(n, g)

245

Pu daughter

246

Pu daughter

244

Pu(a, d) Pu(3He, p) 244 Pu(a, p) 244

3457 Nuclear properties of curium isotopes. Mass number

Half‐life

237 238

– 2.3 h

239 240

2.9 h 27 d 1.9 106 yr 32.8 d

241 242

Mode of decay

Main radiations (MeV)

Method of production

EC, a EC < 90% a > 10% EC a SF EC 99.0% a 1.0%

a 6.660 a 6.52

237

g 0.188 a 6.291 (71%) 6.248 (29%) a 5.939 (69%) 5.929 (18%) g 0.472 (71%) a 6.113 (74.0%) 6.070 (26.0%) a 5.785 (73.5%) 5.741 (10.6%) g 0.278 (14.0%) a 5.805 (76.7%) 5.764 (23.3%) a 5.362 (93.2%) 5.304 (5.0%) g 0.175 a 5.386 (79%) 5.343 (21%)

239

a 5.266 (14%) 4.869 (71%) g 0.402 (72%) a 5.078 (82%) 5.034 (18%) b
0.9 g 0.634 (1.5%)

multiple n capture

162.8 d 7.0 106 yr 29.1 yr

a SF a 99.76% EC 0.24%

18.10 yr 1.35 107 yr 8.5 103 yr

a SF a

246

4.76 103 yr 1.80 107 yr

247

1.56 107 yr

a SF b stable a

248

3.48 105 yr

249

64.15 min

a 91.61% SF 8.39% b


250 251

8.3 103 yr 16.8 min

SF b


243 244 245

b
1.42 g 0.543 (12%)

239

239 239

Np (6Li,6n) Pu(a,5n) Pu(a,4n) Pu(a,3n) Pu(a,2n)

239

Pu(a,n) Am daughter 242 Cm(n,g) 242

multiple n capture Am daughter multiple n capture

244

multiple n capture

multiple n capture 248

Cm(n,g)

multiple n capture Cm(n,g)

250

Nuclear properties of berkelium isotopes. Mass number

Half‐life

Mode of decay

238 240 241 242

2.4 min 4.8 min 4.6 min 7.0 min

EC EC EC EC

243

4.5 h

EC 99.85% a 0.15%

Main radiations (MeV)

Method of production 241

Am(a,7n) Th(14Ne,6n) 239 Pu(6Li,4n) 232 Th(14N,4n) 232 Th(15N,5n) 243 Am(a,4n) 232

g 0.2623 a 6.758 (15%) 6.574 (26%)

3458 Nuclear properties of berkelium isotopes. (Contd.) Mass number

Half‐life

244

4.35 h

EC > 99% a 6 10
3%

245

4.94 d

EC 99.88% a 0.12%

246 247

1.80 d 1.38 103 yr

EC a

248a

23.7 h

248a 249

> 9 yr 330 d

b
70% EC 30% decay not observed b
> 99% a 1.45 10
3%

250

3.217 h

b


251

55.6 min

b


a

Mode of decay

Main radiations (MeV) g 0.755 a 6.667 (50%) 6.625 (50%) g 0.218 a 6.349 (15.5%) 6.145 (18.3%) g 0.253 (31%) g 0.799 (61%) a 5.712 (17%) 5.532 (45%) g 0.084 (40%) b
0.86 g 0.551 a 5.417 (74.8%) 5.390 (16%) b
0.125 g 0.327 weak b
1.781 g 0.989 (45%) b
1.1 g 0.178

Method of production 243

Am(a,3n)

243

Am(a,2n)

243

Am(a,n) Cf daughter 244 Cm(a,p) 247

248

Cm(d,2n)

246

Cm(a,pn) multiple n capture

254

Es daughter Bk(n,g) 255 Es daughter 249

Not known whether ground‐state nuclide or isomer.

Nuclear properties of californium isotopes. Mass number

Half‐life

Mode of decay

239 240 241 242

39 s 1.1 min 3.8 min 3.5 min

a a a a

243

10.7 min

244

19.4 min

EC 86% a 14% a

245

43.6 min

246

35.7 h 2.0 103 yr

247

3.11 h

EC 70% a 30% a SF b stable EC 99.96% a 0.035%

Main radiations (MeV)

Method of production

a 7.63 a 7.59 a 7.335 a 7.385 (80%) 7.351 (20%) a 7.06

243

a 7.210 (75%) 7.168 (25%) a 7.137

244

a 6.758 (78%) 6.719 (22%) a 6.296 (95%) g 0.294 (1.0%)

Fm daughter U(12C,5n) 233 U(12C,4n) 233 U(12C,3n) 235 U(12C,5n) 235 U(12C,4n) 233

Cm(a,4n) U(12C,4n) 244 Cm(a,3n) 238 U(12C,5n) 244 Cm(a,2n) 246 Cm(a,4n) 236

246 244

Cm(a,3n) Cm(a,n)

3459 Nuclear properties of californium isotopes. (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

a 6.258 (80.0%) 6.217 (19.6%)

246

Cm(a,2n)

a 6.194 (2.2%) 5.812 (84.4%) g 0.388 (66%) a 6.031 (83%) 5.989 (17%) a 5.851 (27%) 5.677 (35%) a 6.118 (84%) 6.076 (15.8%) a 5.979 (95%) 5.921 (5%) a 5.834 (83%) 5.792 (17%)

249

Bk daughter

248

334 d 3.2 104 yr

249

351 yr 6.9 1010 yr

a SF b stable a SF

250 251

13.08 yr 1.7 104 yr 898 yr

a SF a

252

2.645 yr

253

17.81 d

254

60.5 d

255 256

1.4 h 12.3 min

a 96.91% SF 3.09% b 99.69% a 0.31% SF 99.69% a 0.31% b
SF

multiple n capture multiple n capture multiple n capture multiple n capture multiple n capture 254 254

Cf(n,g) Cf(t,p)

Nuclear properties of einsteinium isotopes. Mass number

Half‐life

241 242 243 244

8s 13.5 s 21 s 37 s

245

1.1 min

246

7.7 min

247

4.55 min

248

27 min

249

1.70 h

250a 250a

8.6 h 2.22 h

Mode of decay

Main radiations (MeV)

Method of production

a a a EC 96% a  4% EC 60% a 40% EC 90% a 10% EC  93% a  7% EC 99.7% a  0.3% EC 99.4% a 0.57% EC EC

a 8.11 a 7.92 a 7.89 a 7.57

245

a 7.73

Md daughter U(14N,5n) 233 U(15N,5n) 233 U(15N,4n) 237 Np(12C,5n) 237 Np(12C,4n) 233

a 7.35

241

a 7.32

241

a 6.87 g 0.551 a 6.770 g 0.380 g 0.829 g 0.989

Am(12C,a3n)

Am(12C,a2n) U(14N,5n) 249 Cf(d,3n) 238

249

Cf(d,2n)

249

Cf(d,n) Cf(d,n)

249

3460 Nuclear properties of einsteinium isotopes. (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

251

33 h

EC 99.5% a 0.49%

249

Bk(a,2n)

252

471.7 d

a 78% EC 22%

249

Bk(a,n)

253

20.47 d 6.3 105 yr

254 g

275.7 d > 2.5 107 yr

a SF b stable a SF

254 m

39.3 h > 1 105 yr

a 6.492 (81%) 6.463 (9%) g 0.177 a 6.632 (80%) 6.562 (13.6%) g 0.785 a 6.633 (89.8%) 6.592 (7.3%) g 0.389 a 6.429 (93.2%) 6.359 (2.4%) g 0.062 a 6.382 (75%) 6.357 (8%)

255

39.8 d

256a 256a

25.4 min 7.6 h

a

b
99.6% SF a 0.33% EC 0.08% b
92.0% a 8.0% SF 4 10–3% b
b


multiple n capture multiple n capture 253

a 6.300 (88%) 6.260 (10%)

Es (n,g)

multiple n capture 255 254

Es(n,g) Es(t,p)

Not known whether ground‐state nuclide or isomer.

Nuclear properties of fermium isotopes. Mass number

Half‐life

Mode of decay

242 243 244

0.8 ms 0.18 s 3.3 ms

SF a SF

245 246

4.2 s 1.1 s

247a

35 s

247a 248

9.2 s 36 s

249

2.6 min

a a 92% SF 8% a  50% EC 50% a a 99.9% SF 0.1% a

250

30 min

250 m

1.8 s

a SF 5.7 10–4% IT

Main radiations (MeV)

Method of production 204

a 8.546 a 8.15 a 8.24 a 7.93 ( 30%) 7.87 (70%) a 8.18 a 7.87 (80%) 7.83 (20%) a 7.53 a 7.43

Pb(40Ar,2n) Pb(40Ar,3n) 206 Pb(40Ar,2n) 233 U(16O,5n) 233 U(16O,4n) 235 U(16O,5n) 239 Pu(12C,5n) 239 Pu(12C,4n) 206

239 240 238

Pu(12C,4n) Pu(12C,4n)

U(16O,5n) Cf(a,4n) 249 Cf(a,3n) 238 U(16O,4n) 249 Cf(a,3n) 249

3461 Nuclear properties of fermium isotopes. (Contd.) Mass number

Half‐life

251

5.30 h

252

25.39 h

253

3.0 d

254

3.240 h

255

20.07 h

256

2.63 h

257

100.5 d

258 259 260

0.37 ms 1.5 s 4 ms

a

Mode of decay

Main radiations (MeV)

Method of production

EC 98.2% a 1.8% a SF 2.3 10–3% EC 88% a 12%

a 6.834 (87%) 6.783 (4.8%) a 7.039 (84.0%) 6.998 (15.0%) a 6.943 (43%) 6.674 (23%) g 0.272 a 7.192 (85.0) 7.150 (14.2%) a 7.022 (93.4%) 6.963 (5.0%) a 6.915

249

Cf(a,2n)

249

Cf(a,n)

252

Cf(a,3n)

a > 99% SF 0.0592% a SF 2.4 10–5% SF 91.9% a 8.1% a 99.79% SF 0.21%

a 6.695 (3.5%) 6.520 (93.6%) g 0.241

SF SF SF

254m

Es daughter

255

Es daughter

256

Md daughter Es daughter multiple n capture

256

257

Fm(d,p) Fm(t,p) 260 Md decay product 257

Not known whether ground‐state nuclide or isomer.

Nuclear properties of mendelevium isotopes. Mass number 245

Half‐life

248

0.4 s 0.9 ms 1.0 s 1.12 s 0.27 s 7s

249

24 s

250

52 s

251

4.0 min

252

2.3 min

253 254a 254a 255

6 min 10 min 28 min 27 min

246 247

Mode of decay

Main radiations (MeV)

Method of production

a SF a a 80% SF EC  80% a  20% EC 80% a  20% EC 94% a 6% EC  94% a 6% EC > 50% a < 50% EC EC EC EC 92%

a 8.680

209

Bi(40Ar,4n)

a 8.740 a 8.424

209

Bi(40Ar,3n) Bi(40Ar,2n)

a 8.36 (25%) 8.32 (75%) a 8.03

241

a 7.830 (25%) 7.750 (75%) a 7.55

243

a 7.73

209

Am(12C,5n) Pu(14N,5n) 241 Am(12C,4n) 239

Am(12C,5n) Pu(15N,5n) 243 Am(12C,4n) 240 Pu(15N,4n) 243 Am(13C,4n) 240

238

U(19F,4n) Es(a,3n) 253 Es(a,3n) 253 Es(a,2n) 253

a 7.333

3462 Nuclear properties of mendelevium isotopes. (Contd.) Mass number

Half‐life

256

1.27 h

257

5.52 h

258a

51.5 d

258a 259 260

57.0 min 1.60 h 31.8 d

a

Mode of decay

Main radiations (MeV)

Method of production

a 8% EC 90.7% a 9.9% EC 90% a 10% a

g 0.453 a 7.205 (63%) 7.139 (16%) a 7.069

254

254

Es(a,n)

a 6.790 (28%) 6.716 (72%)

255

Es(a,n)

EC ? SF SF > 73% EC < 15%

253

Es(a,3n) Es(a,n)

255

Es(a,n) No daughter 254 Es(18O,12C) 259

Not know whether ground state nuclide or isomer.

Nuclear properties of nobelium isotopes. Mass number

Half‐life

Mode of decay

251

0.25 ms 39.2 ms 0.76 s

SF SF a

252

2.27 s

253

1.62 min

a 73% SF 27% a

a 8.68 (20%) 8.60 (80%) a 8.415 ( 75%) 8.372 ( 25%) a 8.01

254

51 s

a

a 8.086

254 m

0.28 s

IT

255

3.1 min

256

2.91 s

257

25 s

a 61.4% EC 38.6% a  99.7% SF  0.3% a

258 259

1.2 ms 58 min

260 262

106 ms 5 ms

250

SF a  75% EC  25% SF, a SF

Main radiations (MeV)

a 8.121 (46%) 8.077 (12%) a 8.43

Method of production 233

U(22Ne,5n)

244

Cm(12C,5n)

244

Cm(12C,4n) Pu(18O,5n) 246 Cm(12C,5n) 242 Pu(16O,5n) 246 Cm(12C,4n) 242 Pu(16O,4n) 246 Cm(12C,4n) 249 Cf(12C,a3n) 248 Cm(12C,5n) 249 Cf(12C,a2n) 248 Cm(12C,4n) 239

a 8.27 (26%) 8.22 (55%)

248

Cm(12C,3n)

248

a 7.551 (22%) 7.520 (25%)

248

Cm(13C,3n) Cm(18O,a3n)

254 262

Es(18O,x) Lr daughter

3463 Nuclear properties of lawrencium isotopes. Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

252 253 m 253 254 255

0.36 s 1.5 s 0.57 s 13 s 21.5 s

a a a a a, EC

256

256

25.9 s

a, EC

257

0.65 s

a, EC

258

3.9 s

a

259 260 261 262

6.2 s 3.0 min 39 min 3.6 h

a, SF a, EC SF SF, EC

a 9.018 (75%) a 8.722 a 8.794 a 8.460 (64%) a 8.43 (40%) 8.37 (60%) a 8.52 (19%) 8.43 (37%) a 8.86 (85%) 8.80 (15%) a 8.621 (25%) 8.595 (46%) a 8.45 a 8.03

Db daughter Db daughter 257 Db daughter 258 Db daughter 243 Am(16O,4n) 249 Cf(11B,5n) 243 Am(18O,5n) 249 Cf(11B,4n) 249 Cf(11B,3n) 249 Cf(14N,a2n) 248 Cm(15N,5n) 249 Cf(15N,a2n) 248 Cm(15N,4n) 248 Cm(15N,3n) 254 Es(22Ne,x) 254 Es(22Ne,x) 257

Nuclear properties of transactinide elements. Mass number

Half‐life

rutherfordium (Rf) 253  48 ms 254 22.3 ms 255 1.64 s 256 257

6 ms 4.7 s

258 259

12 ms 3.1 s

260 261

20 ms 75.5 s 4.2 s 2.1 s 47 ms

262

Mode of decay SF SF a 48% SF 52% SF, a a 80% SF 2% EC 18% SF a 93% SF 7% SF a a, SF SF SF

Main radiations (MeV)

Method of production 206

Pb(50Ti,3n) Pb(50Ti,2n) 207 Pb(50Ti,2n) 206

a 8.722 (94%) a 8.79 a 9.012 (18%) 8.977 (29%)

208

Pb(50Ti,2n) Pb(50Ti,n) 249 Cf(12C,4n) 208

246

a 8.87 (40%) 8.77 (60%) a 8.28 8.52

Cm(16O,4n) Cf(13C,3n) 248 Cm(16O,5n) 248 Cm(16O,4n) 248 Cm(18O,5n) 249

248

Cm(18O,4n)

3464 Nuclear properties of transactinide elements. (Contd.) Mass number

Half‐life

dubnium (Db) 256 1.6 s 257 1.5 s 257 m 0.76 s 258 4.4 s 259 260

0.51 s 1.5 s

261

1.8 s

262

34 s

263 268

27 s 16 h

seaborgium (Sg) 258 2.9 ms 259 0.48 s 260 3.6 ms 261 0.23 s 262 6.9 ms 263 265 266

0.9 s 0.3 s 7.4 s 21 s

Mode of decay

Main radiations (MeV)

Method of production

EC, a a, SF a, SF a

a 9.014 (67%) a 8.967, 9.074 9.163 a: 9.19 9.07 a 9.7 a: 9.082 (25%) 9.047 (48%)

209

a 8.93

243

a a  90% SF 9.6% EC 2.5% a  75% SF  25% a > 67% SF þ EC < 33% a, SF SF SF a a, SF a, SF a 22% SF > 78% a a a a

a 8.66 (20%) 8.45 (80%) a 8.36

Bi(50Ti,3n) Bi(50Ti,2n) 209 Bi(50Ti,2n) 262 Bh daughter 209

241

Am(22Ne,4n) Cf(15N,4n) 243 Am(22Ne,5n) 249

Am(22Ne,4n) Bk(16O,4n) 249 Bk(18O,5n) 249

249

Bk(18O,4n) 115 decay product 209

Bi(51V,2n) Pb(54Cr,3n) 208 Pb(54Cr,2n) 208 Pb(54Cr,n) 270 110 decay product

a 9.62 (78%) a 9.77 (83%) a 9.56 (60%)

208

a 9.06 (90%) a 9.25 a 8.84 (46%) a 8.77, 8.52

249

Cf(18O,4n)

248

Cm(22Ne,5n) Cm(22Ne,4n)

209

248

bohrium (Bh) 261 12 ms 262 0.1 s 8.0 ms 264 1.0 s 266 1 s 267 17 s 272 9.8 s

a a a a a a a

a 10.10 (40%) a 10.06, 9.91, 9.74 a 10.37, 10.24 a 9.48, 9.62 a 9.3 a 8.85 a 9.02

Bi(54Cr,2n) Bi(54Cr,n) 209 Bi(54Cr,n) 111 decay product 249 Bk(22Ne,5n) 249 Bk(22Ne,4n) 115 decay product

hassium (Hs) 264 0.26 ms 265 1.7 ms 0.8 ms

a, SF a a

a 10.43 a 10.30 (90%) a 10.57 (63%)

207

209

Pb(58Fe,n) Pb(58Fe,n) 208 Pb(58Fe,n) 208

3465 Nuclear properties of transactinide elements. (Contd.) Mass number

Half‐life

Mode of decay

Main radiations (MeV)

Method of production

266 267 269 270

2.3 ms 59 ms 14 s 4 s

a a a a

a 10.18 a 9.88, 9.83, 9.75 a 9.23, 9.17

270

meitnerium (Mt) 266 1.7 ms 268 42 ms 276 0.72 s

a a a

a 10.46, 11.74 a 10.10, 10.24 a 9.71

209

darmstadtium (Ds) 267 3.1 ms 269 0.17 ms 270 0.10 ms 6.0 ms 271 56 ms 1.1 ms 273 0.15 ms 280 7.6 s

a a a a a a a SF

a 11.6 a 11.11 a 11.03 a 12.15 a 10.71 a 10.74, 10.68 a 11.08

209

roentgenium (Rg) 272 1.6 ms 280 3.6 s

a a

a 11.0 a 9.75

209

element 112 277 0.6 ms 283 3 min

a a, SF

a 11.65, 11.45

208

284

a

a 9.15

Pb(70Zn,n) U(48Ca,3n); 114 daughter 114 daughter

element 113 284 0.48 s

a

a 10.00

115 daughter

element 114 287 5s 288 2.6 s

a a

a 10.29 a 9.82

242 244

Pu(48Ca,3n) Pu(48Ca,4n)

element 115 288 87 ms

a

a 10.46

243

Am(48Ca,3n)

element 116 292 53 ms

a

a 10.53

248

Cm(48Ca,4n)

0.75 min

110 daughter 110 daughter 112 decay product 248 Cm(26Mg,4n) 271

Bi(58Fe,n) 111 daughter 115 decay product

Bi(59Co,n) Pb(62Ni,n) 207 Pb(64Ni,n) 207 Pb(64Ni,n) 208 Pb(64Ni,n) 208

112 daughter 114 decay product Bi(64Ni,n) 115 decay product

238

3466 Specific activities of actinide and transactinide nuclides. Major decay modea

Half‐life

209 210 211 212 213 214 215 216 216 m 217 218 219 220 221 222 222 m 223 224 225 226 227 228 229 230 231 232 233 234

a a a a a a a a a a a a a a a a a a a a a a EC a b
b
b
b
b
b
b
b
b


33 ms 22 ms 22 ms 95 ms 25 ms 0.10 s 0.35 s 0.25 s 0.93 s 0.80 s 8.2 s 0.17 s  0.33 ms 0.33 ms 69 ns 1.08 ms 11.8 ms 26.4 ms 52 ms 5.0 s 63 s 2.10 min 2.78 h 10.0 d 29.37 h 21.772 yr 6.15 h 62.7 min 122 s 7.5 min 119 s 145 s 44 s

209 210 211 212 213 214 215 216 217 218 219 220 221

a a a a a a a a a a a a a

3.8 ms 9 ms 37 ms 30 ms 140 ms 100 ms 1.2 s 28 ms 0.237 ms 0.109 ms 1.05 ms 9.7 ms 1.68 ms

Nuclide Ac

206 207 208

Th

b

Sc (dis min–1 mg–1) 3.68 1018 5.50 1018 5.50 1018 1.27 1018 4.82 1018 1.20 1018 3.41 1017 4.75 1017 1.27 1017 1.47 1017 1.43 1016 6.85 1017 3.51 1020 3.51 1020 1.67 1024 1.06 1023 9.69 1021 4.31 1018 2.18 1018 2.26 1016 1.79 1015 8.91 1014 1.12 1013 1.29 1011 1.048 1012 1.6058 108 4.96 1012 2.91 1013 8.92 1014 2.41 1014 9.67 1014 7.41 1014 2.43 1015 3.15 1019 1.3 1019 3.21 1018 3.94 1018 8.40 1017 1.17 1018 9.71 1016 4.14 1018 4.87 1020 1.05 1024 1.09 1023 1.17 1022 6.75 1019

Sd (Ci g–1)

5.80 104 72.332

3467 Specific activities of actinide and transactinide nuclides. (Contd.) Major decay modea

Half‐life

Sc (dis min
1 mg
1)

222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238

a a a a a a a a a b
a b
b
b
b
b
b


2.8 ms 0.60 s 1.05 s 8.0 min 30.57 min 18.68 d 1.9116 yr 7.340 103 yr 7.538 104 yr 25.52 h 1.405 1010 yr 22.3 min 24.10 d 7.1 min 37.5 min 5.0 min 9.4 min

4.03 1019 1.87 1017 1.06 1017 2.32 1014 6.042 1013 6.836 1010 1.8208 109 4.721 105 4.577 104 1.180 1012 0.2435 8.03 1013 5.140 1010 2.50 1014 4.72 1013 3.52 1014 1.87 1014

212 213 214 215 216 217 g 217 m 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 234m 235 236 237

a a a a a a a a a a a a a a a a a EC EC EC a b
b
b
b
b
b
b


5.1 ms 5.3 ms 17 ms 14 ms 0.2 s 3.8 ms 1.08 ms 0.12 ms 53 ns 0.78 ms 5.9 ms 2.9 ms 5.1 ms 0.79 s 1.7 s 1.8 min 38.3 min 22 h 1.50 d 17.4 d 3.276 104 yr 1.31 d 26.967 d 6.70 h 1.17 min 24.5 min 9.1 min 8.7 min

2.32 1019 2.22 1019 6.88 1018 8.32 1018 5.8 1017 3.04 1019 1.07 1020 9.57 1020 2.16 1024 1.46 1023 1.92 1022 3.89 1019 2.20 1019 1.42 1017 6.55 1016 1.03 1015 4.80 1013 1.39 1012 8.44 1011 7.24 1010 1.049 105 9.54 1011 4.6129 1010 4.44 1012 1.52 1015 7.25 1013 1.94 1014 2.02 1014

Nuclide

Pa

b

Sd (Ci g
1)

820.20 0.2127 0.02062 1.097 10–7

0.04724 2.0779 104

3468 Specific activities of actinide and transactinide nuclides. (Contd.) Major decay modea

Nuclide

U

Np




Half‐life

b

Sc (dis min
1 mg
1)

Sd (Ci g
1)

7.62 1014 1.64 1013

238 239

b b


2.3 min 106 min

217 218 219 222 223 224 225 226 227 228 229 230 231 232 233 234 235 235 m 236 237 238 239 240 242

a a a a a a a a a a EC a EC a a a a IT a b
a b
b
b


16 ms 1.5 ms 42 ms 1.0 ms 18 ms 0.9 ms 59 ms 0.35 s 1.1 min 9.1 min 58 min 20.8 d 4.2 d 68.9 yr 1.592 105 yr 2.455 105 yr 7.038 108 yr 25 min 2.3415 107 yr 6.75 d 4.468 109 yr 23.45 min 14.1 h 16.8 min

7.21 1018 7.66 1019 2.72 1021 1.13 1023 6.24 1021 1.2 1020 1.89 1018 3.17 1017 1.67 1015 2.01 1014 3.14 1013 6.06 1010 2.99 1011 4.96 107 2.139 104 1.381 104 4.798 7.10 1013 1.4361 102 1.81 1011 0.7462 7.447 1013 2.06 1012 1.03 1014

226 227 228 229 230 231 232 233 234 235 236 236 237 238 239 240 240 m 241 242

EC, a EC, a EC, a a a EC EC EC EC EC EC, b
EC a b
b
b
b
b
b


31 ms 0.51 s 61.4 s 4.0 min 4.6 min 48.8 min 14.7 min 36.2 min 4.4 d 396.1 d 22.5 h 1.54 105 yr 2.144 106 yr 2.117 d 2.3565 d 1.032 h 7.22 min 13.9 min 5.5 min

3.57 1018 2.16 1017 1.79 1015 4.56 1014 3.94 1014 3.70 1013 1.22 1014 4.95 1013 2.82 1011 3.114 109 1.31 1012 2.18 104 1.562 103 5.752 1011 5.1461 1011 2.808 1013 2.41 1014 1.25 1014 3.14 1014

22.4 9.724 10–3 6.223 10–3 2.161 10–6 3.20 107 6.4687 10–5 3.361 10–7

7.035 10–4

3469 Specific activities of actinide and transactinide nuclides. (Contd.) Major decay modea

Nuclide

Pu

Am

Cm




Half‐life

b

Sc (dis min
1 mg
1)

Sd (Ci g
1)

7.83 1014 9.28 1014 7.47 1014

242 243 244

b b
b


2.2 min 1.85 min 2.29 min

228 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247

a EC, a EC, a EC EC EC EC a EC a a a b
a b
a b
b
b


1.1 s 2.6 min 8.6 min 33.1 min 20.9 min 8.8 h 25.3 min 2.858 yr 45.2 d 87.7 yr 2.411 104 yr 6.564 103 yr 14.35 yr 3.733 105 yr 4.956 h 8.08 107 yr 10.5 h 10.84 d 2.27 d

1.0 1017 6.98 1014 2.10 1014 5.44 1013 8.57 1013 3.38 1012 7.02 1013 1.177 109 2.71 1010 3.80 107 1.377 105 5.037 105 2.295 108 8.784 103 5.776 1012 4.02 101 2.70 1012 1.087 1011 5.17 1011

232 233 234 235 236 236 237 238 239 240 241 242 242 m 243 244 244 m 245 246 246 247

EC EC, a EC, a EC, a EC, a EC EC EC EC EC a b– IT a b– b– b– b– b– b–

1.32 min 3.2 min 2.32 min 10.3 min 3.6 min 2.9 min 1.22 h 1.63 h 11.9 h 50.8 h 432.2 yr 16.02 h 141 yr 7.37 103 yr 10.1 h 26 min 2.05 h 25.0 min 39 min 23.0 min

1.36 1015 5.60 1014 7.69 1014 1.72 1014 4.91 1014 6.10 1014 2.41 1013 1.79 1013 2.45 1012 5.71 1011 7.618 106 1.794 1012 2.33 107 4.43 105 2.82 1012 6.58 1013 1.38 1013 6.79 1013 4.35 1013 7.35 1013

238 239

EC EC

2.3 h 2.9 h

1.27 1013 1.00 1013

17.1 0.06203 0.2269 103.4 3.957 10–3 1.81 10–5

3.432 0.1996

3470 Specific activities of actinide and transactinide nuclides. (Contd.)

Half‐life

240 241 242 243 244 245 246 247 248 249 250 251

a EC a a a a a a a b
SF b


27 d 32.8 d 162.8 d 29.1 yr 18.10 yr 8.5 103 yr 4.76 103 yr 1.56 107 yr 3.48 105 yr 64.15 min 8.3 103 yr 16.8 min

4.47 1010 3.67 1010 7.356 109 1.12 108 1.797 108 3.81 105 6.78 105 2.06 102 9.19 103 2.613 1013 3.82 105 9.10 1013

238 240 241 242 243 244 245 246 247 248 248

2.4 min 4.8 min 4.6 min 7.0 min 4.5 h 4.35 h 4.94 d 1.80 d 1.38 103 yr 23.7 h >9 yr

7.31 1014 3.62 1014 3.8 1014 2.46 1014 6.36 1012 6.55 1012 2.39 1011 6.55 1011 2.33 106 1.18 1012 < 3.6 108

249 250 251

EC EC EC EC EC EC EC EC a b– decay not observed b– b– b–

330 d 3.217 h 55.6 min

3.53 109 8.648 1012 2.99 1013

237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254

EC, SF EC, SF a a a a EC a EC a EC a a a a a b
SF

2.1 s 21 ms 39 s 1.06 min 3.8 min 3.7 min 10.7 min 19.4 min 45.0 min 35.7 h 3.11 h 333.5 d 351 yr 13.08 yr 898 yr 2.645 yr 17.81 d 60.5 d

5.03 1016 5.01 1018 2.69 1015 1.64 1015 4.56 1014 4.66 1014 1.61 1014 8.82 1013 3.79 1013 7.92 1011 9.05 1012 3.504 109 9.08 106 2.426 108 3.52 106 1.190 109 6.431 1010 1.89 1010

Nuclide

Bk

Cf

Sc (dis min
1 mg
1)

Major decay modea

b

Sd (Ci g
1)

3.314 103 50.5 80.93 0.172 0.305 9.28 10–5 4.14 10–3

1.05

1.59 103

4.09 109.3 1.59 536.2

3471 Specific activities of actinide and transactinide nuclides. (Contd.) Major decay modea

Nuclide

Es

Fm

Md




Half‐life

b

Sc (dis min
1 mg
1)

255 256

b SF

1.4 h 12.3 min

1.95 1013 1.33 1014

241 242 243 244 245 246 247 248 249 250a 250a 251 252 253 254 g 254 m 255 256 256

a a a EC EC EC EC EC EC EC EC EC a a a b
b
b
b


8s 13.5 s 21 s 37 s 1.1 min 7.7 min 4.55 min 27 min 1.70 h 8.6 h 2.22 h 33 h 471.7 d 20.47 d 275.7 d 39.3 h 39.8 d 25.4 min 7.6 h

1.3 1016 7.66 1015 4.91 1015 2.77 1015 1.55 1015 2.20 1014 3.71 1014 6.23 1013 1.64 1013 3.24 1012 1.25 1013 8.40 1011 2.438 109 5.596 1010 4.138 109 6.97 1011 2.86 1010 6.42 1013 3.57 1012

242 243 244 245 246 247 247 248 249 250 250 m 251 252 253 254 255 256 257 258 259 260

SF a SF a a a a a a a IT EC a EC a a SF a SF SF SF

0.8 ms 0.18 s 3.3 ms 4.2 s 1.1 s 35 s 9.2 s 36 s 2.6 min 30 min 1.8 s 5.30 h 25.39 h 3.0 d 3.240 h 20.07 h 2.63 h 100.5 d 0.37 ms 1.5 s 4 ms

1.3 1020 5.72 1017 3.11 1019 2.43 1016 9.25 1016 2.90 1015 1.10 1016 2.80 1015 6.45 1014 5.56 1013 5.56 1016 5.23 1012 1.087 1012 3.82 1011 8.451 1012 1.359 1012 1.03 1013 1.122 1010 2.62 1020 6.44 1016 2.4 1019

245

a SF

0.4 s 0.9 ms

2.6 1017 1.14 1020

Sd (Ci g
1)

1.098 103 2.521 104 1.864 103 1.286 104

6.122 105 5.054 103

3472 Specific activities of actinide and transactinide nuclides. (Contd.) Sc (dis min
1 mg
1)

Major decay modea

Half‐life

246 247 248 249 250 251 252 253 254 254 255 256 257 258 258 259 260

a a EC EC EC EC EC EC EC EC EC EC EC a EC SF SF

1.0 s 1.12 s 7s 24 s 52 s 4.0 min 2.3 min 6 min 10 min 28 min 27 min 1.27 h 5.52 h 51.5 d 57.0 min 1.60 h 31.8 d

1.02 1017 9.05 1016 1.4 1016 4.19 1015 1.93 1015 4.16 1014 7.20 1014 2.8 1014 1.64 1014 5.87 1013 6.06 1013 2.14 1013 4.90 1012 2.18 1010 2.84 1013 1.68 1013 3.50 1010

250 251 252 253 254 254 m 255 256 257 258 259 260 262

SF SF a a a a IT a a a SF a SF, a SF

0.25 ms 39.2 ms 0.76 s 2.27 s 1.62 min 51 s 0.28 s 3.1 min 2.91 s 25 s 1.2 ms 58 min 106 ms 5 ms

4.01 1020 2.55 1018 1.25 1017 4.38 1016 1.02 1015 1.93 1015 3.52 1017 5.28 1014 3.36 1016 3.90 1015 8.09 1019 2.78 1013 9.08 1017 1.9 1019

Lr

252 253 m 253 254 255 256 257 258 259 260 261 262

a a a a a, EC a, EC a, EC a a, SF a, EC SF SF, EC

0.36 s 1.5 s 0.57 s 13 s 21.5 s 25.9 s 0.65 s 3.9 s 6.2 s 3.0 min 39 min 3.6 h

2.76 1017 6.60 1016 1.74 1017 7.58 1015 4.57 1015 3.78 1015 1.50 1017 2.49 1016 1.56 1016 5.35 1014 4.10 1013 7.37 1012

Rf

253 254

SF SF

 48 ms 22.3 ms

 2.1 1021 4.42 1021

Nuclide

No

b

Sd (Ci g
1)

3473 Specific activities of actinide and transactinide nuclides. (Contd.)

Nuclide 255 256 257 258 259 260 261 262

Major decay modea

Half‐life

Sc (dis min
1 mg
1)

a SF, a a SF a SF a a, SF SF SF

1.64 s 6 ms 4.7 s 12 ms 3.1 s 20 ms 75.5 s 4.2 s 2.1 s 47 ms

5.99 1016 1.63 1019 2.07 1016 8.08 1018 3.12 1016 4.82 1018 1.271 1015 2.28 1016 4.55 1016 2.03 1018

b

Db

256 257 257 m 258 259 260 261 262 263 268

EC, a a, SF a, SF a a a a SF a, SF SF

1.6 s 1.5 s 0.76 s 4.4 s 0.51 s 1.5 s 1.8 s 34 s 27 s 16 h

6.11 1016 6.50 1016 1.28 1017 2.21 1016 1.90 1017 6.42 1016 5.33 1016 2.81 1015 3.53 1015 1.62 1012

Sg

258 259 260 261 262 263

SF a a a, SF SF a a a a

2.9 ms 0.48 s 3.6 ms 0.23 s 6.9 ms 0.9 s 0.3 s 7.4 s 21 s

3.35 1019 2.01 1017 2.67 1019 4.17 1017 1.38 1019 1.06 1017 3.2 1017 1.28 1016 4.48 1015

a a a a a a a

12 ms 0.1 s 8.0 ms 1.0 s 1 s 17 s 9.8 s

8.0 1018 9.6 1017 1.19 1019 9.5 1016 9.4 1016 5.52 1015 9.40 1015

a a a a a a a

0.26 ms 1.7 ms 0.8 ms 2.3 ms 59 ms 14 s 4 s

3.65 1020 5.56 1019 1.18 1020 4.09 1019 1.59 1018 6.65 1015 2.3 1016

265 266 Bh

261 262 264 266 267 272

Hs

264 265 266 267 269 270

Sd (Ci g
1)

3474 Specific activities of actinide and transactinide nuclides. (Contd.)

Nuclide

Major decay modea

Half‐life

b

Sc (dis min
1 mg
1)

Mt

266 268 276

a a a

1.7 ms 42 ms 0.72 s

5.54 1019 2.22 1018 1.26 1017

Ds

267 269 270

273 280

a a a a a a a SF

3.1 ms 0.17 ms 0.10 ms 6.0 ms 56 ms 1.1 ms 0.15 ms 7.6 s

3.02 1022 5.47 1020 9.27 1020 1.54 1019 1.65 1018 8.40 1019 6.11 1020 1.18 1016

Rg

272 280

a a

1.6 ms 3.6 s

5.75 1019 2.48 1016

112

277 283 284

a SF a

0.6 ms 3 min 0.75 min

1.51 1020 4.9 1014 1.96 1015

113

284

a

0.48 s

1.84 1017

114

287 288

a a

5s 2.6 s

1.7 1016 3.34 1016

115

288

a

87 ms

1.00 1018

116

292

a

53 ms

1.62 1018

271

Sd (Ci g
1)

a Decay modes are denoted by: a for alpha decay, b
for beta decay, EC for electron capture, IT for isomeric transition, and SF for spontaneous fission. The decay mode given in this column represents either the major decay mode or the only observed decay mode. b 1 year ¼ 365.243 days. c Specific activity is given in units of disintegrations per minute per microgram and contains one more significant figure than the half‐life in order to avoid rounding‐off errors. d For commonly used isotopes, specific activities are also given in units of Curies per gram. 1 Ci ¼ 2.22 1012 disintegrations per minute ¼ 3.7 1010 Bq.

SUBJECT INDEX Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440. Page numbers suffixed by t and f refer to Tables and Figures respectively.

AAS. See Atomic absorption spectrometry Ab initio model potentials (AIMP) for actinyl spectroscopic study, 1930 for electronic structure calculation, 1908 Absorption cross section, neutron scattering and, 2233 Absorption spectra of actinides, cyclopentadienyl complexes, 1955 of americium, 1364–1368 americium (III), 1364–1365, 1365f americium (IV), 1365 americium (V), 1366, 1367f americium (VI), 1366, 1367f americium (VII), 1367–1368, 1368f of berkelium, 1455 berkelium (III), 1444–1445, 1455, 1456f berkelium (IV), 1455 of californium, 1515–1516 californium (III), 2091, 2092f compounds, 1542–1545, 1544f halides, 1545 organometallic, 1541 in solution, 1557–1559, 1557t, 1558f, 1559t of curium curium (III), 1402–1404, 1404f curium (IV), 1402–1404, 1405f of einsteinium, 1600–1602, 1601f in borosilicate glass, 1601–1602, 1602f–1603f intensity of, 2089–2093 of liquid plutonium, 963 of neptunium, 763–766, 763f, 786–787 neptunium (VII) ternary oxides, 729 tetrafluoride, 2068, 2070f of neptunyl ion, aqueous solution, 2080, 2081f of plutonium hexafluoride, 1088, 1089f, 2084–2085, 2086f ions, 1113–1117, 1116t plutonium (IV), 849 polymerization, 1151, 1151f tetrachloride, 1093–1094, 1094f

tribromide, 1099t, 1100 trichloride, 1099, 1099t of plutonyl ion, aqueous solution, 2080, 2081f of protactinium protactinium (V), 212, 212f protactinium (V) sulfates, 216, 218f in solution, 1604–1605, 1604f of uranium bromide complexes, 496–497 halides, 442, 443f, 529, 557 hexachloride, 567 hexafluoride, 561 iodide complexes, 499 oxochloride, 526 pentavalent and complex halides, 501 pentavalent oxide fluorides and complexes, 521 tetrabromide, 495 tetrafluoride, 2068, 2069f trichloride, 447 trichloride hydrates, 449–450 trifluoride, 445 uranium (III), 2057–2058, 2057f, 2091, 2092f uranium oxobromo complexes, 573 uranium pentachloride, 523, 523f of uranium dioxide, 2276–2278, 2277f of uranium tetravalent halides, 482–483, 483f Absorption spectroscopy, resonance effects in, 2236 Accelerator mass spectrometry (AMS) applications of, 3318–3319 components of, 3316, 3317f development of, 3317–3318 for environmental actinides, 3059t, 3062–3063 fundamentals of, 3316–3318, 3317f historical development of, 3316 for mass spectrometry, 3310 of neptunium, 790 overview of, 3315–3316 problems of, 3329 requirements for, 3317

I-1

I-2

Subject Index Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440

Accelerator mass spectrometry (AMS) (Contd.) sensitivity of, 3316 TIMS v., 3329 for trace analysis, 3315–3319 Accelerator transmutation, of SNF, 1812 Accelerator transmutation of waste (ATW), overview of, 2693–2694 Acetates of actinide elements, 1796 of americium, 1322, 1323t coordination with, glycolate v., 590 of plutonium, 1177, 1180 structural chemistry of, 2439t–2440t, 2440–2445, 2444f of thorium, 114 properties of, 114 of uranium, 603–605, 604t Acetone derived compounds, of americium, 1322, 1323t, 1324 protactinium extraction with, 185 Acetonitrile, with uranium trichloride, 452 Acetylacetonates, of thorium, 115 Acetylacetones actinide complexes with, 1783 californium extraction with, 1513 SFE separation with, 2680 Acid decomposition, 3279–3281 acids for, 3280 description of, 3279–3280 systems for, 3280–3281 Acid leaching, for uranium ore, 305 limitations of, 306–307 Acid pugging, of uranium ore, 306 Acid redox speciation of americium (III), 3114t, 3115 of berkelium (IV/III), 3109–3110 of californium (III), 3110, 3114t, 3115 of curium (III), 3110, 3114t of environmental samples, 3100–3124 EXAFS, 3100–3103 monatomic An (III) and An (IV) ions, 3100–3118 triatomic An (V) and An (VI) ions, 3118–3124 of neptunium neptunium (III), 3111t–3112t, 3116–3117 neptunium (IV), 3106–3108, 3111t–3112t neptunyl (V), 3111t–3112t, 3121–3122 neptunyl (VI), 3111t–3112t, 3122–3123 of plutonium of plutonium (III), 3113t, 3117–3118 of plutonium (IV), 3108–3109, 3113t plutonyl (VI/V), 3113t, 3123–3124 of thorium (IV), 3103–3105, 3103t of uranium, 3100–3103, 3101t–3102t uranium (III), 3101t–3102t, 3116

uranium (IV), 3105–3106 uranyl (VI), 3101t–3102t, 3118–3121 Acidic extractants, for solvent extraction, 2650–2652, 2651f Acids for acid decomposition, 3280 for Purex process, 711 for solvent extraction, 839 uranium metal reactions with, 328 Actinide cations complexes of, 2577–2591 with inorganic ligands, 2578–2580, 2579t, 2581t with inorganic oxo ligands, 2580–2584, 2582t with organic ligands, 2584–2591, 2585t–2586t, 2588f, 2589t correlations in, 2567–2577 Gibbs energy, 2568–2570, 2568f–2569f ligand basicity, 2567–2568 hydration of, 2528–2544 in concentrated solution, 2536–2538, 2537f hexavalent, 2531–2532 in non-aqueous media, 2532–2533 overview, 2528 pentavalent, 2531–2532 tetravalent, 2530–2531 thermodynamic properties, 2538–2544, 2540t–2541t, 2542f, 2543t, 2544f trivalent, 2528–2530, 2529f, 2529t TRLF technique, 2534–2536, 2535f, 2535t–2536t hydrolysis of, 2545–2556, 2545f hexavalent, 2553–2556, 2554f–2555f, 2554t–2555t pentavalent, 2552–2553 tetravalent, 2547–2552, 2549t–2550t, 2551f–2552f trivalent, 2546, 2547f, 2547t–2548t inner v. outer sphere complexations, 2563–2566, 2566f, 2567t oxidation states of, 2525–2527, 2525f stability constants of, 2558–2559 correlations, 2567–2577 trivalent, 2562, 2563t Actinide chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Actinide chemistry actinide element properties, 1753–1830 biological behavior, 1813–1818 electronic structure, 1770–1773 environmental aspects, 1803–1813 experimental techniques, 1764–1769 metallic state, 1784–1790 oxidation states, 1774–1784 practical applications, 1825–1829 solid compounds, 1790–1803

Subject Index

I-3

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 sources of, 1755–1763 toxicology, 1818–1825 actinium, 18–44 applications of, 42–44 atomic properties of, 33–34 compounds of, 35–36 metallic state of, 34–35 nuclear properties of, 20–26 occurrence in nature of, 26–27 preparation and purification of, 27–33 solution and analytical chemistry of, 37–42 americium analytical chemistry and spectroscopy, 1364–1370 aqueous solution chemistry, 1324–1356 atomic properties, 1295–1297 compounds, 1302–1324 coordination chemistry and complexes, 1356–1364 history of, 1265 isotope production, 1267–1268 metal and alloys, 1297–1302 nuclear properties of, 1265–1267 separation and purification of, 1268–1295 in animals and man, 3339–3424 binding in bone, 3406–3412 in bone, 3400–3406 clearance from circulation, 3367–3387 initial distribution, 3340–3356 in liver, 3395–3400 tissue deposition kinetics, 3387–3395 transport in body fluids, 3356–3367 in vivo chelation, 3412–3423 berkelium analytical chemistry, 1483–1484 compounds, 1462–1472 free atom and ion properties, 1451–1457 history of, 1444–1445 ions in solution, 1472–1483 metallic state, 1457–1462 nuclear properties, availability, and applications, 1445–1447 production, 1448 separation and purification, 1448–1451 californium, 1499–1563 applications, 1505–1507 compounds, 1527–1545 electronic properties and structure, 1513–1517 gas-phase studies, 1559–1561 metallic state, 1517–1527 preparation and nuclear properties, 1502–1504 separation and purification, 1507–1513 solution chemistry, 1545–1559 complexation and kinetics in solution, 2524–2607 bonding, 2556–2563

cation hydration, 2528–2544 cation hydrolysis, 2545–2556 cation-cation complexes, 2593–2596 complexation reaction kinetics, 2602–2606 complexes, 2577–2591 correlations, 2566–2577 inner v. outer sphere, 2563–2566 redox reaction kinetics, 2597–2602 ternary complexes, 2591–2593 curium, 1397–1434 analytical chemistry of, 1432–1434 aqueous chemistry of, 1424–1432 atomic properties of, 1402–1406 compounds of, 1412–1424 history of, 1397–1398 metallic state of, 1410–1412 nuclear properties of, 1398–1400 production of, 1400–1402 separation and purification of, 1407–1410 einsteinium, 1577–1613 atomic and ionic radii, and promotion energies, 1612–1613 compounds, 1594–1612 electronic properties and structure, 1586–1588 metallic state, 1588–1594 nuclear properties, 1579–1583 production, 1579–1583 purification and isolation, 1583–1585 electronic structures of compounds of, 1893–1998 actinyl ions and oxo complexes, 1914–1933 halide complexes, 1933–1942 matrix-isolated, 1967–1991 organometallics, 1942–1967 relativistic approaches, 1902–1914 speciated ions, 1991–1992 unsupported metal-metal bonds, 1993–1994 environmental identification and speciation, 3013–3073 background, 3013–3021 combining and comparing analytical techniques, 3065–3071 sampling, handling, treatment, and separation, 3021–3024 specifics of, 3024–3065 fermium, 1622–1630 atomic properties of, 1626, 1627t isotopes of, 1622–1624, 1623t metallic state, 1626–1628 preparation and purification of, 1624–1625, 1625f solution chemistry, 1628–1630 handling, storage, and disposition, 3199–3266

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Subject Index Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440

Actinide chemistry (Contd.) compound formation and properties, 3204–3215 disposition options, 3262–3266 hazard assessment, 3248–3259 hazard mitigation, 3259–3262 kinetic considerations, 3201–3204 plutonium compound reaction kinetics, 3215–3223 plutonium metal corrosion kinetics, 3223–3238 radiolytic reactions, 3246–3248 uranium compounds and metal corrosion kinetics, 3238–3246 lawrencium, 1641–1647 atomic properties, 1643–1644 isotopes, 1642 metallic state, 1644 preparation and purification, 1642–1643 solution chemistry, 1644–1647 magnetic properties, 2225–2295 5f0 compounds, 2239–2240 5f1 compounds, 2240–2247 5f2 compounds, 2247–2257 5f3 compounds, 2257–2261 5f4 compounds, 2261–2262 5f5 compounds, 2262–2263 5f6 compounds, 2263–2265 5f7 compounds, 2265–2268 5f8 compounds, 2268–2269 5f9 compounds, 2269–2271 5f10 compounds, 2271 5f11 compounds, 2271–2272 actinide dioxides, 2272–2294 mendelevium, 1630–1636 atomic properties, 1633–1634 isotopes, 1630–1631 metallic state, 1634–1635 preparation and purification, 1631–1633 solution chemistry, 1635–1636 metallic state and 5f-electron phenomena, 2307–2373 basic properties, 2313–2328 cohesion properties, 2368–2371 general observations, 2328–2333 magnetism, 2353–2368 overview of, 2309–2313 strong correlations, 2341–2350 strongly hybridized, 2333–2339 superconductivity, 2350–2353 weak correlations, 2339–2341 neptunium, 699–795 analytical chemistry and spectroscopic techniques, 782–795 in aqueous solution, 752–770 compounds of, 721–752 coordination complexes in solution, 771–782

history of, 699–700 isotope production, 702–703 metallic state of, 717–721 in nature, 703–704 nuclear properties of, 700–702 separation and purification, 704–717 nobelium, 1636–1641 atomic properties, 1639 isotopes, 1637–1638 metallic state, 1639 preparation and purification, 1638–1639 solution chemistry, 1639–1641 optical spectra and electronic structure, 2013–2103 divalent and high valence states, 2076–2089 modeling of crystal-field interaction, 2036–2056 modeling of free-ion interactions, 2020–2036 radiative and nonradiative electronic transitions, 2089–2103 relative energies of, 2016–2020 tetravalent spectra interpretation, 2064–2076 trivalent spectra interpretation, 2056–2064 organoactinide catalytic processes, 2911–3006 alkyne dimerization, 2930–2947 alkyne hydroamination, 2981–2990 alkyne oligomerization, 2923–2930 amine, silane reactions, 2978–2981 azide and hydrazine reduction, 2994–2996 heterogeneous, 2999–3006 intramolecular hydroamination, 2990–2993 olefin hydrogenation, 2996–2997 olefin hydrosilylation, 2953–2978 olefin polymerization, 2997–2999 reactivity, 2912–2923 terminal alkyne cross dimerization, 2947–2952, 2948f–2949f organoactinide chemistry, 2799–2894 bimetallic complexes, 2889–2893 carbon-based ancillary ligands, 2800–2867 heteroatom-based ancillary ligands, 2876–2889 heteroatom-containing ancillary ligands, 2868–2876 neutral carbon-based donor ligands, 2893–2894 plutonium atomic properties of, 857–862 compounds of, 987–1108 metal and intermetallic compounds of, 862–987

Subject Index

I-5

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 natural occurrence of, 822–824 nuclear properties of, 815–822 separation and purification of, 826–857 solution chemistry of, 1108–1203 protactinium, 161–232 analytical chemistry of, 223–231 atomic properties of, 189–191 metallic state of, 191–194 nuclear properties of, 164–170 occurrence in nature of, 170–171 preparation and purification of, 171–189 simple and complex compounds of, 194–209 solution chemistry of, 209–223 separation of, 2622–2769 applications, 2725–2767 future of, 2768–2769 historical development of, 2627–2631 systems for, 2631–2725 spectra and electronic structures of, 1836–1887 actinide parameters, 1864–1866 configuration summary, 1866–1872 einsteinium electrodeless lamps, 1885–1886 electronic structures, 1852–1860 empirical analysis, 1841–1852 experimental spectroscopy, 1838–1841 ionization potentials with laser spectroscopy, 1873–1875 ionization potentials with resonance ionization mass spectrometry, 1875–1879 laser spectroscopy, 1873 laser spectroscopy of super-deformed fission isomers, 1880–1884 new properties from, 1872–1873 radial parameters, 1862–1863 theoretical term structure, 1860–1862 structural chemistry of, 2380–2495 coordination compounds, 2436–2467 metals and inorganic compounds, 2384–2436 organoactinide compounds, 2467–2491 solid state structural techniques, 2381–2384 thermodynamic properties, 2113–2213 carbides, 2195–2198 chalcogenides, 2204–2205 complex halides, oxyhalides, and nitrohalides, 2179–2187 elements, 2115–2123 halides, 2157–2179 hydrides, 2187–2190 hydroxides and oxyhydrates, 2190–2195 ions in aqueous solutions, 2123–2133 ions in molten salts, 2133–2135 other binary compounds, 2205–2211

oxides and complex oxides, 2135–2157 pnictides, 2200–2204 thorium, 52–134 atomic spectroscopy of, 59–60 compounds of, 63–117 history of, 52–53 metal of, 60–63 nuclear properties of, 53–55 occurrence of, 55–56 processing and separation of, 56–59 solution chemistry of, 117–134 trace analysis, 3273–3330 atomic spectrometric techniques, 3307–3309 chemical procedures, 3278–3288 mass spectrometric techniques, 3309–3328 nuclear techniques, 3288–3307 transactinide elements and future elements, 1652–1739 elements 104–112 chemical property measurements, 1690–1721 elements 104–112 chemical property predictions, 1672–1689 elements beyond 112, 1722–1739 nuclear properties, 1661 one-atom-at-a-time chemistry, 1661–1666 relativistic effects on chemical properties, 1666–1671 transfermium elements, 1621–1622 uranium, 253–639 analytical chemistry of, 631–639 chemical bonding of, 575–578 compounds of, 328–575 free atom and ion properties, 318 history of, 253–639 metal of, 318–328 natural occurrence of, 257–302 nuclear properties of, 255–257 ore processing and separation, 302–317 organometallic and biochemistry of, 630–631 solution chemistry of, 590–630 structure and coordination chemistry of, 579–590 X-ray absorption spectroscopy, 3086–3184 future direction, 3183–3184 sorption studies, 3140–3183 terrestrial aquatic environment, 3095–3140 Actinide complexes, 2577–2591 bonding in, 2556–2563 coordination numbers, 2558–2560, 2559f covalent contribution to, 2561–2562, 2563t ionicity of f-element, 2556, 2557f steric effects in, 2560

I-6

Subject Index Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440

Actinide complexes (Contd.) strength of, 2560–2561 thermodynamics of, 2556–2557, 2558t cation-cation, 2593–2596, 2596f, 2596t complexation kinetics, 2602–2606, 2605f, 2606t americium, 2604–2605 Eigen mechanism, 2602–2603 multidentate ligands, 2603–2604 simple v. complex, 2602 trivalent complexes, 2605–2606, 2605f, 2606t fluorides, 2578 halides, 2578–2580, 2581t hexafluorides, 1933–1939 with inorganic ligands, 2578–2580, 2579t, 2581t with inorganic oxo ligands, 2580–2584, 2582t carbonates, 2583 complex, 2583–2584 nitrates, 2581 phosphates, 2583 sulfates, 2581–2582, 2582t with organic ligands, 2584–2591, 2585t–2586t, 2588f, 2589t carboxylates, 2584, 2585t–2586t, 2586–2587, 2590 catecholamine, 2590–2591 crown ether, 2590 fulvic acid, 2590–2591 humic acid, 2590–2591 hydroxypyridonate, 2590–2591 siderophores, 2590–2591 overview of, 2577 redox reaction kinetics, 2597–2602 An-O bond breakage, 2598–2600, 2599t complexation effect, 2601–2602, 2602t disproportionation reactions, 2600–2601, 2600t electron exchange reactions, 2597–2598 ternary, 2591–2593 hydrolytic behavior of, 2592–2593 modeling of, 2593 overview of, 2591–2592 use of, 2592–2593 Actinide compounds electronic structure of, 1893–1998 actinyl ions and oxo complexes, 1914–1933 actinyl complexes, 1920–1928 ‘bare’ species and ions in solids, 1928–1932 high oxidation oxygen species, 1932–1933, 1932t uranyl ion and related species, 1914–1920

halide complexes, 1933–1942 oxyhalides, 1939–1942 uranium hexafluoride and related complexes, 1933–1939 matrix-isolated, 1967–1991 binary carbonyls, 1984–1987 carbide oxides, 1976–1984 description of, 1968 developments of, 1969 dioxides, 1970–1976 nitride-oxides, 1989–1991 nitrides, 1987–1989 overview of, 1968–1970 organometallics, 1942–1967 actinocenes, 1943–1952 cyclopentadienyl complexes, 1952–1959 miscellaneous, 1965–1967 six- and seven-membered ring complexes, 1959–1962 uranium (III) complexes, 1962–1965 relativistic approaches, 1902–1914 double groups, 1910–1914 excited electronic states, 1909–1910 Hartree-Fock and density functional approaches, 1902–1904 RECPs, 1907–1909 relativistic effects, 1904–1907 speciated ions, 1991–1992 unsupported metal-metal bonds, 1993–1994 magnetic properties of, 2361–2362 thermodynamic properties of, 2113–2213 antimonides, 2197t, 2203–2204 arsenides, 2197t, 2203–2204 carbides, 2195–2198 chalcogenides, 2203t, 2204–2205 complex halides, 2179–2182 group IIA elements, 2205, 2206t–2207t group IIIA elements, 2205–2206, 2206t–2207t, 2208f group IVA elements, 2206–2208, 2206t–2207t halides, 2157–2179 hydrides, 2187–2190 nitrides, 2200–2203 nitrohalides, 2182–2185 oxides, 2192–2195 oxides and complex oxides, 2135–2157 oxyhalides, 2182–2187 oxyhydroxides, 2193–2195 phosphides, 2197t, 2203–2204 pnictides, 2200–2204 selenides, 2203t, 2204–2205 sulfides, 2203t, 2204, 2204f

Subject Index

I-7

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 tellurides, 2203t, 2204–2205 transition elements, 2208–2211 trihydroxides, 2190–2192 transition metal characteristics of, 2333–2334 Actinide concept history of, 3, 1754–1755 periodic table and, 10–11 Actinide-CU. See DIPEX resin Actinide elements, 1753–1830 absorption cross section of, 2233 atomic volumes of, 922–923, 923f biological behavior, 1813–1818 bioremediation, 1817–1818 in body fluids, 1814–1815 bone uptake, 1817 general considerations, 1813–1814 liver uptake, 1815–1816 in bone, 1817, 3400–3406 americium (III), 3403 binding of, 3406–3412 blood supply of, 3402 composition of, 3406 as deposition site, 3344–3445 neptunyl ion, 3404 plutonium (IV), 3403 retention of, 3404–3406 surfaces of, 3401–3402 uranyl ion, 3403 cyclopentadienyl complexes of, 1952–1959 3 ligands þ X, 1956–1957 4 ligands, 1953–1954 ‘base-free’ 3 ligands, 1954–1956, 1955f metal-metal bonds, 1958–1959 mixed ligands, 1957–1958 overview of, 1952–1953, 1953f structure of, 1953, 1953f definition of, 18 discovery of, 4, 5f–7f, 8–10 divalent, 2525–2526 electronic structures of, 2024, 2024t observed spectra of, 2077–2079 electronic structures of, 1770–1773, 1842t–1850t, 1851–1860, 1851f, 1894–1897, 1896f–1897f, 1896t–1897t crystal-field interaction, 2036–2056 determination of, 1858–1860, 1860f energies of, 1853–1858, 1854f, 1855t, 1856f, 1859f free-ion interactions, 2020–2036 general considerations, 1770 periodic table position, 1773, 1774f redox potentials v., 1859–1860, 1860f relative energies, 2016–2020 relativistic approaches for, 1902–1914 relativistic effects on, 1898–1900 spectroscopic studies, 1770–1771 structure, 1771–1773, 1772t, 1773f electrorecovery of, 2719–2721

elution of, 1625f entropy of, 2539, 2542f, 2543t in environment, 3013–3014, 3015f analytical techniques for, 3018–3020, 3019t anthropogenic, 3016 dispersal of, 3016–3017 mining, 3017 natural occurrence, 3014–3016, 3015f separation of, 3021 environmental aspects of, 1803–1813 in hydrosphere, 1807–1810 man-made, 1805–1807 of natural origin, 1804–1805 nuclear waste disposal, 1811–1813 overview of, 1803 sorption and mobility, 1810–1811 experimental techniques, 1764–1769 column partition chromatography, 1769 hazards, 1764–1765 ion-exchange chromatography, 1767–1768, 1768f liquid-liquid extraction, 1768–1769 long-lived nuclides, 1765–1766 tracer techniques, 1766 ultramicrochemical manipulation, 1767 extraction of DIDPA, 1276 HDEHP, 1275 organophosphorus and carbamoylphosphonate reagents, 1276–1278 reductive, 2719 stripping of, 1280–1281 TRPO, 1274–1275 f-d promotion energies of, 1560, 1561f, 1586–1588, 1587f ground state configuration of, 1895, 1897t heptavalent, 2527 hexavalent, 2527 cyclopentadienyl complexes, 2847–2851 energy levels, 2081–2082, 2083t, 2084f hydrolytic behavior of, 2553–2556, 2554f–2555f, 2554t–2555t observed spectra of, 2079–2085, 2080t stability constants of, 2571–2572, 2573f ionization potentials of by laser spectroscopy, 1873–1875, 1874t by RIMS, 1875–1879, 1877t, 1878f–1879f lanthanide elements v., 2, 10–11 atomic volume, 1578–1579, 1578f bonding in, 584–585 extraction from, 1286–1289, 1407 free-ion interaction and crystal-field strength, 2062–2064, 2063t ligand displacement series for, 2806 phonon energy relaxation, 2096

I-8

Subject Index Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440

Actinide elements (Contd.) relativistic effects on, 1898, 1899f separation from, 2635, 2635f lanthanide separation from, 2669–2677, 2757–2760 Cyanex 301, 2675–2676 dithiophosphinic acids, 2676 LIX–63, 2759–2760 process applications, 2670–2671 separation factors for, 2669–2670, 2670t soft-donor complexants for, 2670–2671, 2673 sulfur donor extractants, 2676–2677, 2677t TALSPEAK, 2671–2673, 2672f, 2760 TPTZ, 2673–2675, 2674t TRAMEX process, 2758–2759, 2759f laser spectroscopy of, 1873 ionization potentials by, 1873–1875, 1874t super-deformed fission isomers of americium, 1880–1884, 1881f, 1883f–1884f, 1883t ligand bonding of, 1900–1901 long-lived, 1763, 1764t lowest level of configurations of, 1841, 1842t–1850t magnetism in, 2354–2356 in mammalian tissues, 3339–3424 binding in bone, 3406–3412 bone, 3400–3406 liver, 3395–3400 matrix-isolated, 1967–1991 binary carbonyls, 1984–1987 carbide oxides, 1976–1984 description of, 1968 developments of, 1969 dioxides, 1970–1976 nitride-oxides, 1989–1991 nitrides, 1987–1989 overview of, 1968–1970 metallic state and 5f-electron phenomena of, 2307–2373 basic properties, 2313–2328 cohesion properties, 2368–2371 general observations, 2328–2333 magnetism, 2353–2368 overview of, 2309–2313 strong correlations, 2341–2350 strongly hybridized, 2333–2339 superconductivity, 2350–2353 weak correlations, 2339–2341 metallic state of, 1–2, 964, 1784–1790 crystal structure, 1785–1787, 1786t electronic structures, 1788–1789, 1789f polymorphic transformation, 1787 preparation, 1784–1785

properties of, 1786t superconductivity, 1789–1790 natural occurrence of, 1755–1756, 1804–1805, 3014–3016, 3273, 3274t–3275t, 3276 new properties of, 1872–1873 optical spectra and electronic structure of, 2013–2103 crystal-field interaction, 2036–2056 divalent, 2077–2079 free-ion interactions, 2020–2036 penta- and hexavalent, 2079–2085, 2080t tetravalent, 2064–2076 trivalent, 2056–2064 f orbital in, 1894–1895, 1896f, 1896t overview of, 1–2, 2f oxidation states, 1774–1784 complex-ion formation, 1782–1784 hydrolysis and polymerization, 1778–1782 ion types, 1777–1778, 1777t, 1779f, 1780t ions in aqueous solution, 1774–1776, 1775t parameters of, 1864–1866 least-squares fitted values, 1864–1865, 1864f radial integral comparisons, 1865, 1866 pentavalent, 2526–2527 circulation clearance of, 3376–3379 cyclopentadienyl complexes, 2845–2847 energy levels, 2081–2082, 2083t, 2084f hydrolytic behavior of, 2552–2553 initial distribution in mammalian tissues, 3350–3354 observed spectra of, 2079–2085, 2080t plutonium oxidation and reduction by ions of, 1133–1137, 1134t–1135t practical applications, 1825–1829 medical and other, 1828–1829 neutron sources, 1827–1828 nuclear power, 1826–1827 portable power sources, 1827 production of, 2729–2736 bismuth phosphate process, 2730 BUTEX process, 2731 CMPO, 2738–2752 DHDECMP, 2737–2738 DIDPA, 2753–2756 DMDBTDMA, 2756 extractant comparisons, 2763–2764, 2763t methods under development, 2760–2763 neptunium partitioning, 2756–2757 PUREX process, 2732–2733 REDOX process, 2730–2731 THOREX process, 2733–2736 TLA process, 2731–2732 trivalent actinide/lanthanide group separation, 2757–2760

Subject Index

I-9

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 TRPO, 2752–2753 around the world, 2764–2767 in pyroprocessing, 2694 quadrupole moments of, 1884, 1884f questions of, 14–15 separation of, rare earth metals, 2719, 2720t, 2721f six- and seven-membered ring complexes of, 1959–1962, 1961f solid compounds, 1790–1803 binary, 1790, 1791t–1795t crystal structure and ionic radii, 1798, 1799t introductory remarks, 1790 organoactinide, 1800–1803 other, 1796 oxides and nonstoichiometric systems, 1796–1798 sorption studies of, 1810–1811, 3140–3183 bacterial interactions, 3177–3183 carbonate incorporation, 3159–3164 iron-bearing mineral phases, 3164–3169 natural soil samples, 3171–3177 overview of, 3140, 3151 phosphates, 3169–3171 silicates, 3151–3158 sources of, 1755–1763 atomic weights, 1763 heavy-ion bombardment, 1761–1763 natural, 1755–1756 neutron irradiation, 1756–1761 spin-orbit coupling in, 1899–1900, 1899f structures of, 2369f, 2370–2371, 2371f superconductivity of, 1789–1790, 2239 synthesis of, 2630, 2631t systematics of, 10–13 tetravalent, 2526 circulation clearance of, 3376–3379 cyclopentadienyl complexes, 2814–2845 electronic structures of, 2024, 2024t energy levels, 2081–2082, 2083t, 2084f hydrolytic behavior of, 2547–2552, 2549t–2550t, 2551f–2552f initial distribution in mammalian tissues, 3350–3354 observed spectra of, 2064–2076 stability constants of, 2571–2572, 2573f thermodynamic properties of, 2113–2223 in aqueous solutions, 2123–2133, 2128t in condensed phase, 2115–2118, 2119t–2120t, 2121f in gas phase, 2118–2123, 2119t–2120t in molten salts, 2133–2135 toxicology, 1818–1825 ingestion and inhalation, 1818–1820 plutonium acute toxicity, 1820–1821 plutonium long-term effects, 1821–1822 removal of, 1822–1825

trivalent, 2526 circulation clearance of, 3370–3376 cyclopentadienyl complexes, 2800–2814 electronic structures of, 2024, 2024t energy levels of, 2032, 2033t hydrolytic behavior of, 2546, 2547f, 2547t–2548t initial distribution in mammalian tissues, 3341t–3347t, 3345–3350, 3348f observed spectra of, 2056–2064 stability constants of, 2571–2572, 2573f Wigner-Seitz radius of, 2310–2312, 2311f Actinide ions absorption cross section of, 2233 in aqueous phase, 2123–2133 electrode potentials, 2127–2131 enthalpy of formation, 2123–2125, 2124f–2125f entropies, 2125–2127 heat capacities, 2132–2133 EPR measurements of, 2226 for SFE, 2683–2684 speciated, 1991–1992, 1992f thermodynamic properties of in aqueous solutions, 2123–2133, 2128t in molten salts, 2133–2135 Actinide metals Bloch states in, 2316 cohesion properties of, 2368–2371 magnetism in, 2353–2368 electronic transport and, 2367–2368 exchange interactions and magnetic anisotropy, 2364–2366, 2365f–2366f general features of, 2353–2354 intermetallic compounds, 2356–2361 magnetic structures, 2366–2367 orbital moments, 2362–2364, 2363f other compounds, 2361–2362 in pure elements, 2354–2356 overview of, 2309–2313 crystal structure of, 2312–2313, 2312f electrical resistivity of, 2309, 2310f Wigner-Seitz radius of, 2310–2312, 2311f properties of, 2313, 2314t–2315t Brillouin zones, 2317–2318 complex and hybridized bands, 2318–2319, 2318f density functional theory, 2326–2328 density of states, 2318f, 2319 electrical resistivity, 2324 electron-electron correlations, 2325–2326 electronic heat capacity, 2323 Fermi energy and effective mass, 2319–2322 Fermi surface, 2322–2323 formation of energy bands, 2313–2317 one-electron band model, 2324–2325

I-10

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Actinide metals (Contd.) strongly hybridized 5f bands in, 2333–2339 Fermi surface measurements, 2334 photoemission measurement background, 2334–2336 strong correlations, 2341–2350 UIr3 PES, 2336–2339, 2337f weak correlations, 2339–2341 structural chemistry of, 2384–2388 actinium, 2385 americium, 2386–2387 berkelium, 2388 californium, 2388 curium, 2387–2388 einsteinium, 2388 neptunium, 2385–2386 overview, 2384–2385, 2384f plutonium, 2386, 2387f protactinium, 2385 thorium, 2385 uranium, 2385 superconductivity of, 2350–2353 Actinide oxides, structure of, 2390 Actinide oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Actinide phosphates, structural chemistry of, 2430–2433, 2431t–2432t Actinium applications of, 42–44 as geochemical tracer, 44 as heat sources, 42–43 as neutron sources, 43 for tumor radiotherapy, 43–44 atomic properties of, 33–34 compounds of, 35, 36t enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t half-life of, 20 heat capacity of, 2119t–2120t, 2121f history of, 19–20 ionization potentials of, 33, 1874t isotopes of, 18–19, 22t–23t, 31–32 lanthanide elements v., 2 lanthanum v., 18, 40 metallic state of, 34–35 structure of, 2385 nuclear properties of, 20–26 actinium–225, 22t–23t, 24f, 25–26 actinium–227, 20–24, 21f, 22t–23t, 25f–26f actinium–228, 22t–23t, 23f, 24–25 occurrence in nature of, 26–27, 162 origin of, 162 oxidation states of

in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t preparation and purification of, 27–33 gram quantities, 32–33 by ion-exchange chromatography, 30–32 purification of, 28–30 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f solution and analytical chemistry of, 37–42 complexation, 40, 41t radiocolloid formation, 41–42 redox behavior, 37–38 solubility, 38–40, 39t sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f from uranium–235, 42–44 Actinium (III) detection of, limits to, 3071t energy level structure of, 2058, 2059f hydration of, 2528–2530, 2529f, 2529t in mammalian tissues, circulation clearance of, 3368f, 3370–3371 Actinium (I), electron configurations of, 2018–2019, 2018f Actinium sesquioxide formation enthalpy of, 2143–2146, 2144t, 2145f structure of, 2390 Actinium trihalides, structural chemistry of, 2416, 2417t Actinium-225 as bismuth-231 generator, 44 decay series of, 24f, 25 identification of, 42 properties of, 22t–23t, 25–26 from protactinium–233, 171 in radiotherapy, 43–44, 1829 synthesis of, 28 actinium-227 decay series of, 20, 21f detection of limits to, 3071t αS, 3029 as geochemical tracer, 44 identification of, 20–24, 25f–26f, 42 from neutron irradiation, 1756 nuclear properties of, 3274t–3275t, 3298t occurrence in nature, 26–27 properties of, 20–24, 22t–23t from protactinium–231, 164, 166f purification of, 28–31, 29f, 31f gram quantities of, 32–33 synthesis of, 27 Actinium-228 decay series of, 23f, 24 identification of, 42

Subject Index

I-11

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 nuclear properties of, 3274t–3275t, 3298t properties of, 22t–23t, 24 purification of, 29, 29f synthesis of, 28 Actinocenes, 1943–1952 bonding in, 2853–2854, 2854f electronic configurations, ground states, and oxidation states of, 1946–1948 electronic transitions in, 1949–1952 protactinocene, 1949–1951 thorocene and uranocene, 1951–1952 geometric structures of, 1943–1944, 1944t, 1945f history of, 1943 metal-ring covalency, 1948–1949, 1948f optimized metal-ring distances, 1943, 1944t orbital interactions in, 1944–1945, 1946f Actinometer, history of, 626 Actinouranium (AcU). See Uranium–235 Actinyl ions complexes of, 1920–1928, 2578–2580, 2579t, 2581t aqua, 1921–1925 bidentate ligands, 1926–1928, 1928t chlorides, 2579–2580, 2581t hydroxide complexes, 1925–1926 oxyhalides, 1939–1942 compounds, structural chemistry of, 2399–2402 species and ions in solids, 1928–1932 structure of, 2085–2089 XAFS of, 2532 AcU. See Uranium–235 Adsorption behavior of californium, 1524 of fermium, 1628 of oxidation states, 3287 of protactinium, 176 of rutherfordium, 1696 Adsorption enthalpy of dubnium, 1705 of element 112, 1721 gas-phase chromatography for, 1663 of nobelium, 1705 of rutherfordium, 1693, 1694f of tantalum, 1705 transactinide predictions of, 1684 AE calculations. See All-electron calculations Aerosol release fraction (ARF) description of, 3252 plutonium release of, 3253 AES. See Atomic emission spectrometry; Auger electron spectroscopy Aging of plutonium, metal and intermetallic compounds, 979–987 AIMP. See Ab initio model potentials

Air plutonium hydrides reaction with, 3218 plutonium metal reaction with, 3225–3238, 3231–3232 uranium corrosion by, 3242–3245, 3243f, 3244t Air samples actinide handling in, 3021–3022 treatment of, 3022 Albumin, actinide distribution with, 3362–3363 Aliquat 336 actinium extraction with, 30 americium extraction with, 1293 curium extraction with, 1410 dubnium extraction with, 1705 fermium extraction with, 1624 neptunium extraction with, 714–715, 715f protactinium extraction with, 185–186 Alkali metals actinide oxides with, 2150–2153 enthalpy of formation, 2151 entropy, 2151, 2152t high-temperature properties, 2151–2153 cyclopentadienyl complexes with, 2844 neptunium (IV) ternary oxides, 730 neptunium (V) ternary oxides, 730 neptunium (VI) ternary oxides, 729–730 neptunium (VII) ternary oxides, 728–729 oxoplutonates of, preparation of, 1056–1057 for pyrochemical processes, 2692 with thorium molybdates, 112 with thorium sulfates, 104–105 uranates (V) and (IV) of, 380–382 crystal structures of, 381 non-stoichiometry in, 382–383 physicochemical properties of, 372t–378t, 381–382 preparation of, 381 uranates (VI) of, 371–380 non-stoichiometry in, 382–383 physicochemical properties of, 372t–378t, 380 preparation of, 371, 379 in uranium mixed halogeno-complexes, 575 with uranium selenites, 298–299 Alkaline earth metals actinide chelation v. sequestration of, 1823–1824 actinide oxides with, 2153–2157 enthalpy of formation, 2153–2156, 2154f, 2155t, 2156f entropy, 2155t, 2156–2157 high-temperature properties, 2157, 2158t mendelevium separation with, 1633 neptunium (IV) ternary oxides, 730 neptunium (V) ternary oxides, 730

I-12

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Alkaline earth metals (Contd.) neptunium (VI) ternary oxides, 729–730 neptunium (VII) ternary oxides, 728–729 nobelium v., 1639–1640 oxoplutonates of, preparation of, 1057–1059 for pyrochemical processes, 2692 uranates (V) and (IV) of, 380–382 crystal structures of, 381 non-stoichiometry in, 382–383 physicochemical properties of, 372t–378t, 381–382 preparation of, 381 uranates (VI) of, 371–380 non-stoichiometry in, 382–383 physicochemical properties of, 372t–378t, 380 preparation of, 371, 379 Alkaline solutions, actinide separations from, 852, 2667–2668 Alkane, activation of, 3002–3006, 3004t Alkenes, hydrosilylation of activity data for, 2970t kinetic studies of, 2972–2974 organoactinide complex promotion, 2969–2974 products of, 2971 Alkoxides, of plutonium, 1185–1186 Alkyl ligands, 2866–2867 complexation with, 2866–2867 cyclopentadienyl complexes with, tetravalent, 2539f, 2819–2820, 2820f, 2837–2839 of plutonium, 1186 preparation of, 2866 stabilization of, 2867 structure of, 2867, 2868f Alkylamines, fermium complexes with, 1629 Alkylphosphoric extraction of curium, 1407 for uranium leach recovery, 312–313 Alkylpyrocatechols, actinide separation with, 1408 Alkyne complexes, 2866 cross dimerization of, 2947–2952, 2948f–2949f dimerization of, 2930–2947 external amines in, 2943–2944 hydroamination and, 2944–2945 promotion of, 2938–2947, 2940f–2941f terminal, 2930–2935 terminal ansa-organothorium promotion, 2935–2937 hydroamination of, 2981–2990 kinetic studies, 2986–2990 rates of, 2985 regioselectivities, 2984

scope and mechanistic studies, 2981–2986 thermodynamics of, 2982–2984 hydrosilylation of active species formation, 2957–2961 alkyne:silane ratio, 2956 bridged complex promotion, 2964–2969 cationic complex promotion, 2974–2978 kinetic studies, 2957, 2965–2966 mechanism, 2961–2963 neutral organoactinide promotion, 2953–2964 with primary silanes, 2966–2969 scope at room temperature, 2953–2954 scope of catalysis at high temperature, 2954–2955 thermodynamics, 2963–2966 oligomerization of, 2923–2930 bisacetylide organoactinide, 2924–2925 cross, 2929–2930 key intermediate complex in, 2926, 2926f kinetic, thermodynamic, and thermochemical data in, 2926–2929 regioselective, 2945–2947 terminal, 2925–2926, 2928f stoichiometric reactions of, with pentamethyl-cyclopentadienyl and silanes, 2916–2918, 2917f Allanite, thorium in, 56t All-electron (AE) calculations, of uranyl, 1918 Allotropes of plutonium, 1, 877–890, 880f, 881t α phase, 879–882, 882f–884f, 884t β phase, 882, 882f–883f, 885t δ phase, 882–883, 882f–883f, 886f, 892–897, 899, 916–917 δ0 phase, 882f–883f, 883 e phase, 882f–883f, 883 γ phase, 882, 882f–883f transformations, 886–890, 888f–889f ζ phase, 882f–883f, 883, 890, 891f of uranium α-phase, 320–326, 328–339, 344 β-phase, 321–323, 325–326, 328–339, 344, 347 γ-phase, 321–323, 347 Alloys of americium, 1302, 1304t of berkelium, 1461–1462 of californium, 1526 of curium, 1411–1412, 1413t–1415t of einsteinium, 1592–1593 magnetic studies of, 2238 mechanical properties of, 972–973 of neptunium, 719–721 tellurium, 742 of plutonium, 862–987, 3213 aluminum, 894, 895f–896f, 919–920, 920f applications of, 862

Subject Index

I-13

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 α and β stabilizers, 897 δ field expansion, 892–897 electronic structure, theory, and modeling, 921–935 eutectic-forming elements, 897 gallium, 892–894, 893f–896f, 899, 916–917, 916f–917f, 917–919, 918f history of, 862 indium, 896, 896f interstitial compounds, 898 microsegregation in δ-phase alloys, 899, 916–917 nature of, 863 oxidation and corrosion, 973–979 phase transformations, 891–921 phase transformations in δ-phase alloys, 917–921 physical and thermodynamic properties of, 935–968 thallium, 896, 896f theory and modeling of, 925–929, 926f of protactinium, 194, 194t of thorium, 63 of uranium, 325–326, 325t Allyl ligands, 2865 Alpha decay actinium actinium–225, 25–26, 43–44 actinium–227, 20–23, 25f americium, 1265–1267, 1266t americium–241, 1267, 1337–1338 americium–243, 1337–1338 ARCA and measurement of, 1665 of bohrium, detection with, 1711 californium, californium–252, 1505 curium curium–242, 1432 curium–243, 1432 curium–244, 862, 1432 of dubnium detection with, 1705 dubnium–262, 1703–1704 einsteinium, einsteinium–253, 1594 element 112, 1719 of hassium, detection with, 1714 lawrencium, 1641 lawrencium–257, 1641–1642 lawrencium–258, 1642 neptunium, neptunium–237, 712, 782–785 nobelium, 1637 plutonium decay, 980 hexafluoride, 1090–1092 redox behavior of, 1143–1146, 1146t transmutation products from, 984–987, 985f protactinium, 164 protactinium–231, 164, 166, 167f, 224

protactinium–233, 162–163 in radioactive displacement principle, 162 rutherfordium, 1639 detection with, 1701 rutherfordium–261, 1698 of seaborgium, detection with, 1708 superactinide elements, 1735 uranium, uranium–232, 256 α-Phase of plutonium, 879–882, 882f–884f, 884t americium influence on, 985 atomic volume, 923, 923f density of, 936t, 937 diffusion rate, 958–960, 959t elastic constants, 942–943, 944t electrical resistivity of, 2309–2310, 2310f, 2345–2347, 2346f fine-grain plasticity, 968, 970–971, 970f ground state, 924 heat capacity, 947–949, 947f, 950t–951t, 952f lattice changes in, 981–982, 982f, 982t, 984 magnetic properties of, 2355 thermal conductivity, 957 thermal expansion, 938t, 939–942, 940f thermoelectric power, 957–958, 958t of uranium electrical properties of, 324 general properties of, 321–323, 322t–323t hydrogen system of, 328–339, 329t, 334f intermetallic compounds and alloys, 325–326, 325t magnetic susceptibility of, 323–324 β phase transformation of, 344 physical properties of, 320–321, 321f resistivity-temperature curve of, 324, 324f Alpha spectroscopy (αS) of actinium, 20–23, 25f advantages/disadvantages of, 3329 americium, 3295–3296 of americium, 1364 applications of, 3292–3296, 3294f curium, 3296 for environmental actinides, 3026t, 3029–3031, 3030f fundamentals of, 3291–3292, 3291f ICPMS v., 3329 βS and, 3070 of neptunium, 783–785, 3294–3295 overview of, 3289 performance of, 3292 of plutonium, 3295 of protactinium, 3294 protactinium–231, 224 of thorium, 133–134, 3293–3294 TIMS v., 3329 for trace analysis, 3289–3296

I-14

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Alpha spectroscopy (αS) (Contd.) tracers for, 3289–3291, 3290t uranium, 3293 bioassay with, 3293 α−α Correlation for rutherfordium identification, 1701–1702 for seaborgium identification, 1708 for transactinide identification, 1659, 1662 Alpha-spectrometers, multi-channel, for protactinium–231, 224 Aluminates, actinide adsorption on, 3158 Aluminum actinide compounds with, thermodynamic properties of, 2205–2206, 2206t–2207t for arene preparation, 2859 in curium complex, 1413t–1415t, 1422–1423 for neptunium halide preparation, 738 in plutonium alloy, 894, 895f–896f damage recovery of, 983–984, 983f δ-phase lattice, 930f, 932–933 elastic constants, 943, 944t heat capacity, 948 oxidation of, 976, 977t solubility ranges, 930, 930f transformation of, 919–920, 920f protactinium extraction with, 176–178, 177f uranium v., 318 Amberlite XAD–4, for actinide extraction, 715–716 Americium analytical chemistry and spectroscopy, 1364–1370 radioanalytical chemistry, 1364 spectroscopy, 1364–1370 aqueous solution chemistry, 1324–1356 complexation reactions, 1338–1356, 1339t oxidation states, 1324–1338 atomic properties, 1295–1297 atomic and ionic radii, 1295–1296 electron configuration, 1295 emission spectra, 1296 ionization potentials, 1296 Mo¨ssbauer spectrum, 1297 photoelectrom spectrum, 1296–1297 x-ray spectrum, 1296 in biological systems in bone, 1817 health hazard of, 1814 ingestion and inhalation of, 1818–1820 in liver, 1815–1816 in organs, 1815 complexes of cyclopentadienyl, 2803 tris-cyclopentadienyl, 2470–2476, 2472t–2473t compounds of, 1302–1324 acetate, 1322, 1323t

acetone, 1322, 1323t, 1324 arsenate, 1321 borides, 1321 carbides, 1305t–1312t, 1319 carbonates, 1305t–1312t, 1319 chalcogenides, 1305t–1312t, 1316–1319 chromates, 1321 cyclooctatetraene, 1323t, 1324 cyclopentadiene, 1323t, 1324 formate, 1322, 1323t halides, 1305t–1312t, 1314–1316 hydrides, 1305t–1312t, 1314 hydroxides, 1303, 1305t–1312t, 1313–1314 inorganic, 1303–1321, 1305t–1312t molybdate, 1321 organic, 1322–1324, 1323t oxalate, 1322, 1323t oxides, 1303, 1305t–1312t, 1313–1314 phosphates, 1305t–1312t, 1319–1321, 1355 pnictides, 1305t–1312t, 1316–1319 silicates, 1321 sulfates, 1305t–1312t, 1319–1321 tungstate, 1321 coordination chemistry and complexes, 1356–1364 inorganic ligands, 1356–1361 organic ligands, 1361–1364 discovery of, 5t, 8 enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f history of, 8, 1265 ionization potentials of, 1296, 1874t isotope production, 1267–1268 isotope shifts of, 1882–1884, 1883f, 1883t isotopes of, 9–10, 12, 1265–1267, 1266t lanthanide elements v., 2 laser spectroscopy of super-deformed fission isomers, 1880–1884, 1881f, 1883f–1884f, 1883t magnetic properties of, 2355–2356 metal and alloys, 1297–1302 metal preparation, 1297 properties of, 1297–1302, 1298t, 1301f metallic state of, structure of, 2386–2387 MSE oxidation of, 869 natural occurrence of, in marine organisms, 1809 nuclear properties of, 1265–1267 oxidation states of, 2526 in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t α-phase plutonium influence of, 985 in plutonium alloy δ-phase lattice, 930–931, 930f

Subject Index

I-15

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 neptunium v., 931, 931f solubility ranges, 930, 930f from plutonium decay, 985, 985f production of, 1758–1759 pyrochemical methods for, molten chlorides, 2699–2700 quadrupole moments of, 1884, 1884f reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f separation and purification of, 1268–1295 from curium, 2672–2673 DDP, 2706 from europium, 2676–2677, 2677t extraction chromatographic processes, 1293–1295 history of, 1268–1269 ion-exchange processes, 1289–1293 from plutonium, 869–870, 877, 878f precipitation processes, 1270–1271 pyrochemical processes, 1269–1270 solvent extraction processes, 1271–1289 TALSPEAK for, 2672–2673 sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f superconductivity of, 1789 synthesis of, 8–9 Americium (II) electrode potentials of, 1328, 1329t magnetic properties of, 2265–2268 oxidation of, by water, 1337 preparation of, 1325 stabilization of, 2077 Americium (III) absorption spectra of, 1364–1365, 1365f autoreduction of, 1330–1331 chlorides of, magnetic data, 2229–2230, 2230t complexes of, 1321 carbonate, 1340–1341 formation constants of, 1273 organic ligands, 1341, 1342t–1352t, 1353–1354, 1353f strengths of, 1353 compounds of carbides, 1319 halides, 1315 sulfates, 1320 detection of limits to, 3071t UVS, 3037 electrode potentials of, 1328–1329, 1329t extraction of, 1274 bis(2,3,4-trimethylpentyl)dithiophosphinic acid, 1286–1287 Cyanex 301, 1287–1289, 1288f, 2675–2676 DBBP, 1274 DHDECMP, 1277–1278, 2737–2738

from europium (III), 1283, 1287–1289, 2665–2666, 2667t HDEHP, 1275–1276, 1409 organophosphorus and carbamoylphosphonate reagents, 1276–1278 from picric acid, 1284 separation factors for, 2669–2670, 2670t TBP, 1271–1272 TPEN, 2675 TPTZ and HDNNS, 1286–1287, 2673–2675, 2674t from trivalent lanthanides, 1286–1289, 1288f formation constants of, 1338, 1339t hydration numbers of, 2534, 2535t hydrolysis, 1339–1340 hydrolytic behavior of, 2546, 2547f, 2547t–2548t in hydrosphere, 1807–1810 interaction parameters of, 2062–2064, 2063t ligands for, 3420–3421 luminescence of, 1368–1369, 1369f, 2098 magnetic properties of, 2263–2265 in mammalian tissues bone, 3403 bone binding, 3409 circulation clearance of, 3368–3369, 3368f–3375f, 3371–3376 glycoproteins, 3410–3411, 3411t initial skeletal fractions of, 3349 transferrin binding to, 3365 peroxydisulfate oxidation of in acid media, 1333–1334, 1333f in carbonate media, 1335 preparation of, 1325 purification of, 1290–1293 anion-exchange, 1291–1292 cation-exchange, 1290–1291 from curium (III), 1410 inorganic exchangers, 1292–1293 zirconium based sorbents, 1409 radii of, 1295–1296 separation of, HDEHP for, 2651, 2651f speciation of, 3114t, 3115 TIP of, 2263–2264 XANES of, 3087, 3089f Americium (IV) absorption spectra of, 1365 autoreduction of, 1331 complexes of, carbonate, 1341 compounds of, halides, 1315 disproportionation of, 1331 electrode potentials of, 1328–1329, 1329t hydrolysis, 1340 magnetic properties of, 2262–2263 peroxydisulfate oxidation of, in nitric acid, 1334

I-16

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Americium (IV) (Contd.) preparation of, 1325–1326 radii of, 1295–1296 stabilization of, 1355–1356 XANES of, 3087, 3089f Americium (V) absorption spectra of, 1366, 1367f autoreduction of, 1330–1331 complexes of, carbonate, 1341 compounds of carbides, 1319 halides, 1315 sulfates, 1320–1321 disproportionation of, 1332, 1332f electrode potentials of, 1329, 1329t hydrolysis, 1340 preparation of, 1326 reduction of by hydrogen peroxide, 1335–1336 by neptunium (IV), 1336 by neptunium (V), 1336–1337 in sodium hydroxide, 1336 by uranium (IV), 1337 uranium (VI) interaction with, 1356 Americium (VI) absorption spectra of, 1366, 1367f in americium precipitation, 1271 autoreduction of, 1331 complexes of, carbonate, 1341 compounds of halides, 1315 sulfates, 1321 electrode potentials of, 1329, 1329t extraction of, HDEHP, 1275 hydrolysis, 1340 preparation of, 1326–1327 reduction of by hydrogen peroxide, 1335 by other reductants, 1335 TBP extraction of, 1272 Americium (VII) absorption spectra of, 1367–1368, 1368f electrode potentials of, 1329, 1329t preparation of, 1327 Americium antimonide, 1318 Americium bismuthide, 1318 Americium carbide entropy of, 2196, 2197t formation enthalpy of, 2195–2196, 2197t high-temperature properties of, 2198, 2198f, 2199t Americium (V) carbonate, in americium precipitation, 1271 Americium carbonates, structural chemistry of, 2426–2427, 2427t Americium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t

Americium dibromide, structure of, 2415 Americium dichloride, 2179, 2180t structure of, 2415 Americium diiodide magnetic properties of, 2266 structure of, 2415 Americium dioxide, 1303, 1313 enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 EPR of, 2292 heat capacity of, 2138–2141, 2139f, 2142t magnetic properties of, 2291–2292 phase relations of, 2396 phase transformation of, 2292 Americium (III) fluoride, stability constants of, 1354–1355 Americium hexafluoride, thermodynamic properties of, 2164t Americium hydrides entropy of, 2188, 2189t formation enthalpy of, 2187–2188, 2187t, 2189t, 2190f high-temperature properties of, 2188–2190, 2190t structure of, 2404 Americium monoxide, structure of, 2395 Americium nitride, 1317–1319 Americium oxalate, in americium precipitation, 1270–1271 Americium oxides phase relations of, 2395–2396 structure of, 2395–2396 Americium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Americium phosphates, structural chemistry of, 2430–2433, 2431t–2432t Americium phosphide, 1318 Americium pnictides, structure of, 2409–2414, 2410t–2411t Americium sesquioxide formation enthalpy of, 2143–2146, 2144t, 2145f high-temperature properties of, 2139f, 2146–2147 structure of, 2395, 2396t Americium sesquisulfide, 1316–1317 Americium sulfates, structural chemistry of, 2433–2436, 2434t Americium tetrahalides, structural chemistry of, 2416, 2418t Americium (III) thiocyanate, 1355 Americium trichloride, thermodynamic properties of, 2170t, 2172, 2173t Americium trihalides, structural chemistry of, 2416, 2417t Americium tritelluride, 1317

Subject Index

I-17

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Americium–240 deformation of, 1880 isotope shift of, 1882–1884, 1883f, 1883t Americium–241 applications of, 1267–1268, 1828 autoreduction of, 1330–1331 curium–242 from, 1267, 1397, 1401–1402 detection of γS, 3301–3302 ICPMS, 3328 limits to, 3071t αS, 3295 environmental hazards of, 1807 importance of, 1267 isotope shift of, 1882–1884 laser spectroscopy of, 1873 neutrons from, 1827 nuclear properties of, 3277t production of, 1265, 1268 radiolysis of, 1337–1338 separation and purification of, pyrochemical processes, 1269–1270 study of, 1765 Americium–242 isotope shift of, 1882–1884, 1883f, 1883t laser spectroscopy of, 1880–1882, 1881f nuclear properties of, 3277t production of, 1267 Americium–243 applications of, 1267–1268 autoreduction of, 1330 curium from, 1400 detection of MBAS, 3043 MBES, 3028 importance of, 1267 isotope shift of, 1882–1884 laser spectroscopy of, 1873 nuclear properties of, 3277t production of, 1268 radiolysis of, 1337–1338 study of, 1765 Americium–244, isotope shift of, 1882–1884, 1883f, 1883t Americyl ion, complexes of cation-cation, 2594 structure of, 2400–2402 Amide extractants, for americium, 1285–1286 Amides complexes of, with cyclopentadienyl complexes, 2832 of plutonium, 1184–1185 Amidinate ligands, 2873–2875 Amine extractants for americium, 1284 quaternary ammonium salts, 1284 tertiary amine salts, 1284

for berkelium, 1448–1449 for separation, 2660, 2661f Amine extraction, for uranium leach recovery, 312 Amine, silane reactions with, 2978–2981 Amines, with terminal alkyne complexes cross dimerization, 2952 dimerization, 2943–2944 Aminex A6 for rutherfordium extraction, 1699 for seaborgium extraction, 1710 Aminopolycarboxylate americium and curium extraction with, 1286 complexes of, 2587, 2588f, 2589t californium, 1554 Ammonia plutonium processing with, reduction and oxidation reactions, 1141–1142 with uranium trichloride, 452 Ammonium carbonate, for uranium carbonate leaching, 308 Ammonium citrate, for californium separation, 1508 Ammonium lactate, for californium separation, 1508 Ammonium nitrate, actinium solubility in, 38–39 Ammonium oxalate, actinide stripping with, 1280 Amperometric method, for protactinium, 227 AMS. See Accelerator mass spectrometry Analytical chemistry for actinide elements, 3018, 3019t requirements for, 3018–3020 separation for, 3021 of actinium, 42 comparing techniques for, 3065–3071 of neptunium, 782–795 of thorium, 133–134 of uranium, 631–639 chemical techniques, 631–635 nuclear techniques, 635–636 spectrometric techniques, 636–639 Angle-resolved photoemission spectroscopy (ARPES) description of, 2336 of UIr3, 2336–2339, 2337f Angular coefficients, of actinide elements, 1863 Angular function, of f-orbitals, 1895, 1896t Angular momentum of band structure, 2319 spin-orbit coupling with, 1911 Animals actinide clearance from circulation, 3367–3387 dioxo ions, 3379–3387

I-18

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Animals (Contd.) rates of, 3367–3369, 3368f–3375f tetravalent and pentavalent, 3376–3379 trivalent, 3370–3376 actinide elements in, 3339–3424 binding in bone, 3406–3412 bone, 3400–3406 liver, 3395–3400 in vivo chelation, 3412–3423 desferrioxamine, 3414 polyaminopolycarboxylic acids, 3413–3414 siderophores, 3414–3423 initial distribution in, 3340–3356 access to, 3340–3341 beagle dogs, 3343t dioxo ions, 3354–3356 ionic radii and stability constants, 3346, 3347t Kenya baboons, 3345t Macaque monkeys, 3344t mice, 3343t pentavalent, 3350–3354 rats, 3341t–3342t skeletal fraction, 3346–3349, 3348f soft tissues, 3349–350 tetravalent, 3350–3354 trivalent, 3345–3350 tissue deposition kinetics, 3387–3395 in mice, 3388–3395, 3389f–3392f, 3394t in rats, 3387–3388 transport in body fluids, 3356–3367 extracellular fluid circulation, 3357–3359 loose connective tissue, 3359 plasma and tissue fluid composition, 3356–3357, 3357t–3358t plasma distribution of, 3357t–3358t, 3359–3361 Anion exchange historical development of, 2635–2637, 2635f, 2642 for trace analysis, 3283, 3286f Anion-exchange chromatography for actinium purification, 31 for americium purification, 1291–1292 chloride solutions, 1291–1292 thiocyanate solutions, 1291 for californium separation, 1509 for curium separation, 1409, 1433 for einsteinium separation, 1585 flow sheet for, 849, 850f improvements of, 851 liquid, 851–852 for neptunium extraction, 714 operation of, 850–851 for plutonium concentration, 848–851, 850f plutonium (IV), 848–849, 848f for protactinium purification, 187–188

for rutherfordium extraction, 1695–1696, 1700 Anisotropic ligand polarization effect, crystalfield splittings and, 2054 Annealing, of plutonium, after selfirradiation, 982–983, 983f Ansa-organoactinide complexes dimerization of, 2935–2937 synthesis of, 2918–2920, 2920f Ansa-organothorium complexes alkyne complexes, dimerization of, 2935–2937 terminal alkyne complexes, dimerization of, 2935–2937 Anthropogenic actinides, 3015f, 3016 Antimonides of americium, 1318 of neptunium, 743–744 of plutonium, 1022–1023 preparation of, 1022 structure of, 1023, 1024f thermodynamic properties of, 2197t, 2203–2204 of uranium, 411–412 Antimony protactinium compound of, 204 thorium compound of, 98t, 100 uranium oxides with, preparative methods of, 383–389, 384t–387t Apatite, thorium in, 56t Aqueous phase actinide ions in, 1774–1776, 1775t, 2123–2133 electrode potentials, 2127–2131 enthalpy of formation, 2123–2125, 2124f–2125f entropies, 2125–2127 heat capacities, 2132–2133 separation in, 2638, 2649, 2649f, 2666–2667 for transactinide elements, measured v. predicted, 1717, 1718t Aqueous raffinate, protactinium enrichment with, 175–176 Aragonite uranium in, 291 uranyl in, 3160–3161, 3161t ARCA. See Automated Rapid Chemistry Apparatus Arene complexes, structural chemistry of, 2489–2491, 2490t–2491t, 2493f Arene ligands, 2858–2860 bond distances, 2860 bonding of, 2859 bridging, 2859–2860, 2861f hydrogenation of, 2999–3000 kinetic data, 3002 overview of, 2858–2859 preparation of, 2859, 2860f

Subject Index

I-19

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 AREP. See Average RECP ARF. See Aerosol release fraction Argon uranium carbide oxide in matrix of, 1978–1980 uranium carbonyl in matrix of, 1985 uranium dioxide in matrix of, 1971–1976 uranium nitride in matrix of, 1988–1989 ARPES. See Angle-resolved photoemission spectroscopy Arrhenius curves for plutonium corrosion, 3225–3226, 3226f for uranium corrosion, in air and water vapor, 3242–3243, 3243f, 3244t Arsenates of actinide elements, 1796 of americium, 1321 structural chemistry of, 2430–2433 of thorium, 113 of uranium, 265t–266t autunite structures, 294–295 chain structures, 295–296 groups of, 294 natural occurrence of, 293 phosphuranylite structures, 295 synthetic, 296–297 uranophane structures, 295 Arsenazo-III. See 3,6-Bis-[(2-arsenophenyl) azo]–4,5-dihydroxy–2,7-naphthalene disulfo acid Arsenides of neptunium, 743 of plutonium, 1022 of protactinium, 204, 206t preparation of, 204 properties of, 207 thermodynamic properties of, 2197t, 2203–2204 of thorium, 98t, 100 of uranium, 411–412 Aryls, cyclopentadienyl complexes with, tetravalent, 2539f, 2819–2820, 2820f, 2837–2839 αS. See Alpha spectroscopy Ascorbate, for plutonium removal, 1823 Atomic absorption spectrometry (AAS) for environmental actinides, 3034t, 3036 overview of, 3307–3308 of uranium, 636 Atomic emission spectrometry (AES) for electronic structure, 1770 overview of, 3307–3308 of plutonium, oxides, 3208 of uranium, 636–637 Atomic properties of actinium, 33–34 of americium, 1295–1297 atomic and ionic radii, 1295–1296

electron configuration, 1295 emission spectra, 1296 ionization potentials, 1296 Mo¨ssbauer spectrum, 1297 photoelectrom spectrum, 1296–1297 x-ray spectrum, 1296 of curium absorption spectra, 1402–1404, 1404f–1405f electronic structure, 1404–1405 fluorescence spectroscopy, 1405–1406, 1406f of einsteinium, 1586–1588, 1589t–1590t of fermium, 1626, 1627t of lawrencium, 1643–1644 of mendelevium, 1633–1634, 1634t of nobelium, 1634t, 1639 of plutonium, 857–862 core-level spectra, 861 ionization potentials, 859 Mo¨ssbauer spectra, 861–862 optical emission spectra, 857–859, 858f, 860t x-ray spectra, 859–861 of protactinium, 189–191 emission spectrum, 190 ground state configuration, 190 Mo¨ssbauer effect, 190–191 X-ray atomic energy levels, 190, 190t of transactinide elements, 1672–1676 electronic structures of, 1672–1673, 1672t ionic radii and polarizability, 1674f, 1675–1676, 1676t oxidation state stabilities and IPs, 1673–1675, 1673t, 1674f–1675f Atomic radii of americium, 1295–1296 of berkelium, 1458 of californium, 1519–1521 of einsteinium, 1612–1613 of element 119, 1729, 1730f of element 120, 1729, 1730f Atomic spectroscopy of actinide elements, 2016–2018, 2018f overview of, 3307–3308 of thorium, 59–60 for trace analysis, 3307–3309 Atomic vapor laser isotope separation (AVLIS), history of, 1840 Atomic volumes of actinides, 922–923, 923f of einsteinium, 1578–1579, 1578f of lawrencium, 1644 of plutonium, 886, 887t in alloys, 934, 934f of δ-plutonium, 2345–2347, 2346f of rare earths, 922–923, 923f of transition metals, 922–923, 923f

I-20

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Atomic-beam magnetic resonance technique for electronic structure, 1770 for fermium, 1626 ATW. See Accelerator transmutation of waste Auger electron spectroscopy (AES), for environmental actinides, 3049t, 3051 Automated Rapid Chemistry Apparatus (ARCA) dubnium study with, 1704–1705 overview of, 1665 rutherfordium study with, 1695, 1698 seaborgium study with, 1710 Automated systems for superactinide element chemical studies, 1734–1735 for transactinide element chemical studies, 1663 Autoradiography (RAD) of actinide elements in bones, 1817 for environmental actinides, 3026t, 3031, 3032f Autunite at Oklo, Gabon, 271–272 uranium in, 259t–269t of uranium phosphates and arsenates, 294–295 Average RECP (AREP), for scalar relativistic mode, 1907–1908 AVLIS. See Atomic vapor laser isotope separation Azide complexes of, 2580, 2581t cyclopentadienyl complex reaction with, 2809 of neptunium, equilibrium constants for, 773t organouranium catalytic reduction of, 2994–2996 of uranium, 602, 603t B. sphaericus, plutonium adsorption, 3182–3183 Bacterial interactions, sorption studies of, 3177–3183 DMRB, 3178, 3181 examples, 3182–3183 overview, 3177–3178, 3179t–3180t reduction potentials, 3181 solubility and mobility, 3181–3182 surface complexation model, 3182 Bacterial leaching, of uranium ore, 306 Bacterial reduction, of uranium (VI), 297 Band structure filling of, 2320 free-electron model with, 2324 metal properties from, 2320, 2321f of uranium metal, 2318, 2318f

Barium, in curium metal production, 1411–1412 Base redox speciation in carbonate solution systems, 3129–3137 in hydroxide solution systems, 3124–3129 of neptunium neptunium (IV), 3111t–3112t, 3135–3136 neptunium (VII/VI), 3111t–3112t, 3124, 3125 of neptunyl (V), 3111t–3112t, 3133–3134 of plutonium plutonium (IV), 3113t, 3136 of plutonium (VII/VI), 3126 of plutonyl (VI), 3113t, 3134 of tetravalent ions, 3134–3135 of thorium thorium (IV), 3136–3137 of thorium (IV), 3129 uranium (IV), 3101t–3102t, 3136 of uranyl (VI), 3101t–3102t, 3126–3133 Bassetite at Oklo, Gabon, 271–272 uranium in, 259t–269t Bastnasite ore, plutonium–244 in, 824 Becquerelite at Shinkolobwe deposit, 273 uranium in, 259t–269t Bentonite, thorium and uranyl complexes of, 3157–3158 Benzamidinate ligands, 2875 Benzene, actinide complexes of, 1959–1960, 1961f Benzoates, structural chemistry of, 2439t–2440t 4-Benzoyl–2,4-dihydro–5-methyl–2phenyl–3H-pyrazol–3-thione, for americium/europium extraction, 2676–2677, 2677t N-Benzoylphenylhydroxylamine (BPHA), protactinium extraction with, 184 Berkeley. See Lawrence Berkeley National Laboratory Berkeley Gas-filled Separator (BGS) pre-separation by, 1666 hassium, 1713 rutherfordium, 1701 superactinide element, 1734 SISAK with, 1666 Berkelium analytical chemistry, 1483–1484 complexes of, tris-cyclopentadienyl, 2470–2476, 2472t–2473t compounds, 1462–1472, 1464t–1465t chalcogenides, 1470 coordination, 1471 general summary of, 1462–1463 halides, 1467–1470 hydrides, 1463 magnetic behavior of ions, 1472, 1473f

Subject Index

I-21

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 organometallic, 1471 other inorganic, 1470–1471 oxides, 1466–1467 pnictides, 1470 discovery of, 5t, 8 einsteinium separation from, 1584, 1584f enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t free atom and ion properties, 1451–1457 electronic energies, 1452–1453 emission spectra, 1453–1454 ion-molecule reactions in gas phase, 1455–1457, 1457f solid-state absorption spectra, 1455, 1456f thermochromatographic behavior, 1451 Gibbs formation energy of hydrated ion, 2539, 2540t half-life of, 1445–1447, 1446t heat capacity of, 2119t–2120t, 2121f history of, 1444–1445 ionization potentials of, 1452, 1874t ions in solution, 1472–1483 hydrolysis and complexation behavior, 1475–1479, 1477t–1478t oxidation states, 1472–1473, 1485 redox behavior and potentials, 1479–1482, 1481t, 1482f spectra in solution, 1473–1475, 1475f–1476f thermodynamic properties, 1482–1483, 1483t isotopes of, 9–10, 1445–1447, 1446t lanthanide elements v., 2 magnetic properties of, 2355–2356 metallic state of, 1457–1462 alloys, 1461–1462 chemical properties, 1460–1461 intermetallic compounds, 1461 physical properties, 1458–1460 preparation of, 1457–1458 structure of, 2388 theoretical treatment, 1461 nuclear properties, availability, and applications, 1445–1447, 1446t oxidation states of in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t production, 1446t, 1448 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f separation and purification, 1448–1451 TALSPEAK for, 2672 sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f synthesis of, 8–9

Berkelium (II) absorption spectra of, 1475 overview of, 1473 Berkelium (III) absorption spectra of, 1444–1445, 1473–1475, 1475f chlorides of, magnetic data, 2229–2230, 2230t compounds of β-diketonate, 1471 cyclopentadienyl, 1471 halides, 1468 orthophosphate, 1470–1471 oxalate, 1479 electronic spectra of, 1475 extraction of, 1479 hydrolytic behavior of, 2546, 2548t initial skeletal fractions of, 3349 ionic radii values of, 1463 magnetic properties of, 2268–2269, 2270t overview of, 1472–1473 oxidation of, 1448 redox behavior of, 1479–1482, 1481t, 1482f separation and purification of, 1448–1451 speciation of, 3109–3110, 3114t stability constants of, 1475–1476, 1477t–1478t Berkelium (IV) absorption spectra of, 1474–1475, 1476f californium (III) separation from, 1508–1509 compounds of fluorides, 1467–1468 halides, 1468 iodate, 1479 electronic spectra of, 1475 energy levels of, 2075–2076, 2075f hydration of, 2531 ionic radii values of, 1463 magnetic properties of, 2265–2268 overview of, 1472–1473 redox behavior of, 1479–1482, 1481t, 1482f speciation of, 3109–3110, 3114t Berkelium (V), overview of, 1472 Berkelium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Berkelium dioxide enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 heat capacity of, 2138–2141, 2139f, 2142t magnetic susceptibility of, 2268 structure of, 2398 Berkelium hydride, 1463, 1464t–1465t structure of, 2404 Berkelium orthophosphate, 1470–1471

I-22

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Berkelium oxide identification of, 1466 metal production with, 1457–1458 oxygen decomposition of, 1466 structure of, 2397–2398, 2398t Berkelium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Berkelium pnictides, structure of, 2409–2414, 2410t–2411t Berkelium sesquioxalate, 1471 high-temperature properties of, 2139f, 2146–2147 Berkelium sesquioxide, 1466–1467 formation enthalpy of, 2143–2146, 2144t, 2145f structure of, 2397, 2398t Berkelium tetrafluoride metal production with, 1457 properties of, 1467–1468 Berkelium tetrahalides, structural chemistry of, 2416, 2418t Berkelium tribromide, 1469 structural chemistry of, 2416, 2417t Berkelium trichloride monitoring of, 1469–1470 properties of, 1468–1469 Berkelium trifluoride, 1469 metal production with, 1457 Berkelium trihalides, structural chemistry of, 2416, 2417t Berkelium triiodide, 1469 Berkelium–249 adsorption of, 1451 availability of, 1445 californium alloy with, 1462 californium–249 from, 1504, 1511, 1766 decay of, 1447 dubnium production from, 1703 from einsteinium–253, 1579 electron-binding energies of, 1452 emission spectrum of, 1453–1454 lawrencium–260 from, 1642 physical properties of, 1445–1447 production of, 1444, 1448, 1504 for transactinide element production, 1661–1662 Berkelium–250 adsorption of, 1451 decay of, 1447 Beryllium foil, berkelium separation from, 1450 thermodynamic properties of actinide compounds with, 2205, 2206t–2207t Beta decay actinium as, 19–20 actinium–225, 25–26 actinium–227, 20 actinium–228 as, 24

americium, 1265–1267, 1266t berkelium berkelium–249, 1461 in study of, 1446 californium–253, 1582 neptunium as neptunium–238 as, 861 neptunium–239 as, 814 plutonium as plutonium–241, 825 plutonium–243, 825 protactinium as, 164 protactinium–233, 225–226 protactinium–234, 162, 225 in radioactive displacement principle, 162 uranium as uranium–237, 256 uranium–239, 825, 825f β-Phase of plutonium, 882, 882f–883f, 885t density of, 936t diffusion rate, 958–960, 959t fine-grain plasticity, 969–970 lattice changes in, 981–982, 982f, 982t magnetic properties of, 2355 thermal conductivity, 957 thermoelectric power, 957–958, 958t of uranium general properties of, 321–323, 322t–323t hydrogen system of, 328–339, 329t, 334f, 335t intermetallic compounds and alloys, 325–326, 325t α phase transformation of, 344 γ phase transformation of, 347 physical properties of, 321 thermal expansion, 938f Beta spectroscopy (βS) for environmental actinides, 3026t, 3028–3029 ICPMS v. αS and, 3070 BGS. See Berkeley Gas-filled Separator Bicarbonates, in plasma, 3361 for uranyl ion, 3380–3381 Bijvoetite natural occurrence of, 290 structure of, 290 Billietite at Shinkolobwe deposit, 273 uranium in, 259t–269t Bimetallic complexes, 2889–2893 bond distance in, 2893 bridging ligands in, 2889 cyclopentadienyl complexes and, 2890 metal-metal interaction in, 2891–2892, 2893f metathesis reactions for, 2889 overview of, 2889

Subject Index

I-23

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 phosphine groups in, 2890 phospholyl ligand in, 2890–2892, 2892f Binding energy of fermium, 1626, 1627t of uranium carbide oxides, 1980 Biochemistry, of uranium, 630–631 Biocolloids, formation of, 3181 Biokinetics studies, of actinides, 3339–3340 Biologic effects of berkelium, 1445 of californium, californium–252, 1507 of einsteinium, 1579 Biological behavior, of actinide elements, 1813–1818 bioremediation, 1817–1818 in body fluids, 1814–1815 bone uptake, 1817 general considerations, 1813–1814 liver uptake, 1815–1816 Biological matrices, trace analysis in, 3273–3330 atomic spectrometric techniques, 3307–3309 chemical procedures, 3278–3288 mass spectrometric techniques, 3309–3328 nuclear techniques, 3288–3307 Bio-Rad AG MP–1, for rutherfordium extraction, 1700 Biosorption solubility and mobility with, 3181–3182 of uranium and thorium by RA, 2669 Biotechnology, for neptunium extraction, 717 3,6-Bis-[(2-arsenophenyl)azo]–4,5dihydroxy–2,7-naphthalene disulfo acid (Arsenazo-III), protactinium compound with, 219 extraction with, 183, 2666–2667 in spectrophotometric methods, 228 Bisacetylide organoactinide complexes magnetic properties of, 2925 synthesis of, 2924–2925 Bis(trimethylsilyl)amide, 2876–2879 geometry of, 2876–2877 hydride compounds, 2877 metallacycles, 2877, 2878f organoimido complexes, 2877–2879 tetravalent complexes of, 2877 trivalent homoleptic complexes with, 2876 Bis-cyclopentadienyl complexes, structural chemistry of, 2476–2482, 2478f, 2479t–2480t, 2481f–2483f Bis(2,3,4-trimethylpentyl)-dithiophosphinic acid, americium (III) extraction with, 1287 Bismuth phosphate for coprecipitation, 2634 for plutonium coprecipitation, 835

Bismuth phosphate process, for actinide production, 2730 Bismuth, uranium oxides with, 383–389, 384t–387t Bismuth–214, nuclear properties of, 3298t Bismuth–231, actinium–225 generation of, 44 Bismuthides of americium, 1318 of neptunium, 744 thorium compound of, 98t, 100 of uranium, 411–412 Bis(2-ethyl)orthophosphoric acid, californium extraction with, 1513 Bisphosphine oxide, lanthanide extraction with, 2657 Bis(2-ethylhexyl)phosphoric acid (HDEHP) actinide extraction with, 1769 actinium extraction with, 30, 1293 americium extraction with, 1275–1276, 2671 berkelium extraction with, 1448–1450, 1450f californium extraction with, 1509 curium extraction with, 1407, 1434, 2672 einsteinium extraction with, 1585 lawrencium extraction with, 1646–1647 mendelevium extraction with, 1633 neptunium extraction with, 708–709 nobelium extraction with, 1638–1640 protactinium extraction with, 172, 184 separation with, 2639–2640, 2641t, 2650–2651, 2651f, 3282 Bistriazinylpyridine (BTP), americium extraction with, 2674–2675, 2674t Bloch states in actinide metals, 2316 overview of, 2316 representation of, 2317 Body fluids, actinide transport in, 3356–3367 plasma and tissue fluid composition, 3356–3357, 3357t–3358t Bohrium berkelium–249 in production of, 1447 chemical properties of, 1691t, 1711–1712 discovery of, 6t, 1653, 1653t, 1762 electronic structures of, 1676–1682, 1677f–1678f, 1680t–1681t, 1682f ionic radii of, 1674f, 1675–1676, 1676t ionization potential of, 1674, 1674f isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, in aqueous solution, 1774–1776, 1775t relativistic orbital energies for, 1669f solution chemistry of complexation of, 1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f

I-24

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Bohrium–264, from meitnerium–268, 1717 Bohrium–267 decay chains of, 1711 discovery of, 1735 production of, 1711 Boiling point, of californium, metal, 1523 Bomb reduction furnace, for plutonium metal production, 866, 867f Bond lengths of actinide nitride oxides, 1990, 1990t of actinide nitrides, 1988, 1989f of actinyl complexes, 1926–1927, 1928t of plutonium, 884t of superactinide elements, 1732 of uranium hexafluroride, 1935–1937, 1937t oxides, 1973, 1974t–1975t of uranium and oxygen, in silicate glass, 276–277 Bond valence approach for crystal structure, 286 expression for, 3093 for uranyl (VI), 3093–3094, 3094f Bonding in actinide complexes, 2556–2563 coordination numbers, 2558–2560, 2559f covalent contribution to, 2561–2562, 2563t ionicity of f-element, 2556, 2557f steric effects in, 2560 strength of, 2560–2561 thermodynamics of, 2556–2557, 2558t in actinide compounds, 1894 relativistic effects on, 1898, 1899f in actinocenes, 2853–2854, 2854f in berkelium, 1452, 1455–1457, 1457f of cyclopentadienyl complexes, tetravalent, 2815–2817, 2816f, 2816t, 2818f DFT for, 923–924 in f-orbital, 1915–1916 in halides, 2415 in metallic state, 2308, 2319 oxidation state, coordination numbers and distance in, 3093 in plutonium, 1191–1203 dioxide, 1196–1199, 1197f, 1200f hexafluoride, 1194–1196, 1195f ionic and covalent, 1191–1192 plutonocene, 1199–1203, 1201f–1202f specific examples, 1192–1203 in transactinide elements, 1677 in uranium hexafluoride and pentafluoride, 576–575 hydrides, 333–336, 334f, 335t in uranyl polyhedra, 280–281 Bone accumulation of protactinium–231, 188 actinide binding in, 3406–3412

glycoproteins, 3410–3411 in vitro, 3407–3409 in vivo, 3406–3407 actinide elements in, 1817, 3400–3406 americium (III), 3403 neptunyl ion, 3404 plutonium (IV), 3403 retention of, 3404–3406 uranyl ion, 3403 blood supply of, 3402 composition of, 3406 as deposition site, 3344 liver v., 3344–3345 surfaces of, 3401–3402 transuranium elements in, 12 Borates, of thorium, 113 Borides of americium, 1321 of plutonium, 996–1003 history of, 997 phase diagram, 997, 997f preparation of, 998 properties of, 1002–1003 solid-state structures of, 998–1002, 999t, 1000f–1002f structural chemistry of, 2405–2408, 2406t of thorium, 66–67, 71t–73t structure of, 66–67 ternary, 67, 74f of uranium, 398–399, 399f, 401t–402t phase diagram of, 398, 400f preparation of, 398 properties of, 398–399, 401t–402t structure of, 398, 399f Boron, thermodynamic properties of actinide compounds with, 2205–2206, 2206t–2207t Born equation, for complexation, 2574–2577 Borohydrides of plutonium, 1187 structural chemistry of, 2404–2405, 2405f Borosilicate glass einsteinium in, 1601–1602, 1602f–1603f SNF disposal in, 1812–1813 BPHA. See N-Benzoylphenylhydroxylamine Brannerites natural occurrence of, 280 uranium in, 269t, 274, 280 Bravais lattice, description of, 2317 Breit effects, on element 121, 1669 Brevium. See Protactinium Brillouin zones of actinide metals, 2317–2318 in crystal structure, 2321 description of, 2317 in magnetism, 2367 Brinell hardness, of uranium metal, 323

Subject Index

I-25

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Bromates, of actinide elements, 1796 Bromides of actinide elements, 1796 of berkelium, 1469 of californium, 1533 of curium, 1413t–1415t, 1417–1418 of dubnium, 1703, 1705–1706 of einsteinium, 1599 of neptunium, 737–738 equilibrium constants for, 772t tetrabromide, 737 tribromide, 737–738 of plutonium, 1092–1100 preparation of, 1092–1095 properties of, 1087t, 1098–1100 solid-state structures of, 1084t, 1096–1097, 1096f–1098f protactinium derivatives of, 197–199, 207 of uranium bromo complexes, 454 dioxide monobromide, 527–528 oxide and nitride, 497, 500 oxide tribromide, 527 oxobromo complexes, 572–574 pentabromide, 526 ternary and polynary compounds, 495–497 tetrabromide, 494–495 tribromide, 453 tribromide hexahydrate, 453–454 of uranyl bromide, 571–572 hydroxide bromide and bromide hydrates, 572 βS. See Beta spectroscopy BTP. See Bistriazinylpyridine Butenouranocene, structure of, 2487, 2488t, 2489f BUTEX process for actinide production, 2731 REDOX process v., 2731 BUTEX process, PUREX process v., 842 t-Butylbenzene (TBB), americum extraction with, 2673–2675, 2674t Tert-Butylhydrazine (tert-BHz), neptunium (VI) reduction with, 761 By-product, uranium as, 314 Cadmium nitridation in, 2725 with thorium molybdates, 112 Calcination, of uranium ore, 304 Calcite uranium in, 289–291, 3160 natural occurrence of, 3163 surface site incorporation of, 3162 uranyl in, 3160–3161, 3161t

Calcium in DOR process, 866–867 in einsteinium alloy, 1592 reduction, plutonium production, 2722 for uranium reduction, 319 Calcium carbonate, for oxidation state speciation, 2726 Calculation of phase diagrams (CALPHAD), application of, 927–928 Californium, 1499–1563 applications, 1505–1507 berkelium alloy with, 1461–1462 complexes of, tris-cyclopentadienyl, 2470–2476, 2472t–2473t compounds of, 1527–1545, 1530t–1531t chalcogenides, 1539–1540 dipivaloylmethanato complex, 1541 general comments, 1527–1529, 1530t–1531t halides, 1529–1534, 1532f, 1542–1545, 1544f hydrides, 1540–1541 magnetic properties of, 1541–1542 organometallic, 1541 other, 1538–1541 oxides, 1534–1538 oxyhalides, 1529–1534, 1532f oxysulfates, 1541 pnictides, 1538–1539 solid-state absorption spectra, 1542–1545, 1544f sulfates, 1549 thiocyanates, 1554 discovery of, 5t, 8–9 einsteinium separation from, 1585 einsteinium v., 1613 electronic properties and structure, 1513–1517, 1514t emission spectra, 1516 x-ray emission spectroscopy, 1516–1517 fermium separation from, 1624–1625 gas-phase studies, 1559–1561 Gibbs formation energy of hydrated ion, 2539, 2540t half-life of, 1503–1504 ionization potentials of, 1874t isotopes of, 9–10, 12, 1499–1502, 1500t lanthanide elements v., 2 lawrencium from, 1641 magnetic properties of, 2355–2356 metallic state of, 1517–1527 chemical and mechanical properties of, 1525–1526 physical properties of, 1519–1525, 1520t preparation of, 1517–1519 structure of, 2388 theoretical treatments of, 1526–1527

I-26

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Californium (Contd.) nobelium v., 1640 nuclear properties of, 1499, 1500t, 1502–1504 oxidation states of, 1528, 1545, 1548, 1562, 2526 in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t preparation of, 1499–1500, 1502–1504 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f separation and purification, 1507–1513, 1510f solution chemistry, 1545–1559 absorption spectra, 1557–1559, 1557t, 1558f, 1559t complexation chemistry, 1549–1555, 1550t–1553t general comments, 1545–1546 redox reactions, 1546–1549, 1547t thermodynamic data, 1555–1557, 1556t sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f synthesis of, 8–9 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t heat capacity of, 2119t–2120t, 2121f Californium (II) absorption spectra of, 1516, 1543–1544 existence of, 1547 overview of, 1501 preparation of, 1534, 1537 Californium (III) absorption spectra of, 1515–1516, 1543–1544, 2091, 2092f berkelium (IV) separation from, 1508–1509 compounds of halides and oxyhalides, 1529–1534, 1532f oxides, 1534–1538 EPR of, 2269 extraction procedures for, 1512–1513 hydration of, 2528–2530, 2529f, 2529t hydrolytic behavior of, 1554, 2546, 2548t magnetic properties of, 2269–2271, 2270t magnetic susceptibility of, 2269–2271, 2270t in mammalian tissues circulation clearance of, 3368–3369, 3368f–3375f, 3371–3376 initial skeletal fractions of, 3349 transferrin binding to, 3365 overview of, 1501 oxidation of, 1546 reduction of, 1548 speciation of, 3110, 3114t, 3115

Californium (IV) compounds of, oxides, 1534–1538 magnetic properties of, 2268–2269, 2270t Californium (V), generation of, 1549 Californium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Californium dibromide, 1533 Californium dichloride, 1533–1534 absorption spectra of, 1542–1544, 1544f structure of, 2416 Californium diiodide, 1533 structure of, 2416 Californium dioxide, 1536 enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 structure of, 2399 Californium monoxide, 1535 Californium oxides, structure of, 2398–2399, 2398t Californium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Californium pnictides, structure of, 2409–2414, 2410t–2411t Californium sesquioxide, 1535–1537, 1535f formation enthalpy of, 2143–2146, 2144t, 2145f structure of, 2398, 2398t Californium tetrafluoride, 1529 Californium tetrahalides, structural chemistry of, 2416, 2418t Californium tribromide, 1533 thermodynamic properties of, 2170t, 2172, 2173t Californium trichloride, 1532 Californium trifluoride, 1529, 1532 Californium trihalides, structural chemistry of, 2416, 2417t Californium triiodide, 1533 Californium–242, production of, 1502 Californium–249 from berkelium–249, 1446, 1461, 1511, 1579 in compounds, 1462 curium–245 from, 1401 energy spectrum of, 1516 IS of, 1872 lawrencium from, 1641–1642 metal production from, 1517–1518, 1518f nuclear magnetic moments of, 1872 production of, 1504 study of, 1766 for transactinide element production, 1661–1662 Californium–250 half-life of, 1504 IS of, 1872

Subject Index

I-27

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Californium–251 IS of, 1872 nuclear magnetic moments of, 1872 production of, 1504 Californium–252 for cancer treatment, 1829 curium–248 from, 1400, 1765–1766 decay of, 1766 energy spectrum of, 1516 half-life of, 1503 IS of, 1872 metal production from, 1518 neutrons from, 1827–1828, 3302–3303 production of, 1401, 1501, 1503–1504 spontaneous fission of, 1505 Californium–253, production of, 1504 Californium–254, spontaneous fission of, 1505 Calixarenes description of, 2456 structural chemistry of, 2456–2463 3 coordination, 2459–2460 4 coordination, 2460, 2461f 5 coordination, 2460–2461 8 coordination, 2461, 2462f 12 coordination, 2461–2462, 2463f other coordination, 2461 CALPHAD. See Calculation of phase diagrams CAM. See Catecholamine Cancer treatment, californium–252 for, 1829 Capillary electrophoresis, ICPMS with, 3069 Carbamoylmethylenephosphine oxide (CMPO), americium extraction with, 1278–1284 Carbamoylphosphonate reagents americium extraction with, 1276–1278 in solvating extraction systems, 2653 Carbide oxides, of actinides, matrix-isolated, 1976–1984 Carbides of americium, 1305t–1312t, 1319 of neptunium, 744 of plutonium, 1003–1009 chemical properties of, 1007–1008 crystal structures of, 1004–1007, 1005t, 1006f–1007f phase diagram of, 1003–1004, 1003f preparation of, 1004 ternary phases, 1009 thermodynamic properties of, 1008–1009 of protactinium, 195 structural chemistry of, 2405–2408, 2406t thermodynamic properties of, 2195–2198 gaseous, 2198 solid, 2195–2198 of thorium, 67–69, 68f, 71t–73t halogens with, 68

structures of, 67–69, 68f ternary, 68–69, 74f of uranium, 399–405, 401t–402t, 403f–404f application of, 405 hydrolytic behavior of, 403–405 phase diagram of, 399, 403f preparation of, 400 structure of, 400, 404f ternary, 405 Carbocyclic ligands, 2858–2865 arene ligands, 2858–2860 bond distances, 2860 bonding of, 2859 bridging, 2859–2860, 2861f overview of, 2858–2859 preparation of, 2859, 2860f cycloheptatrienyl ligand, 2860–2862 bonding in, 2862, 2863f formation of, 2860–2861 structure of, 2861–2862, 2862f fullerenes, 2864–2865 electronic structure of, 2864–2865 overview of, 2864 pentalene, 2862–2864 bond lengths in, 2864 derivation of, 2862 use of, 2863 Carbon dioxide reactions, with cyclopentadienyl complexes, 2824 uranium mineral adsorption and, 3158 Carbon, hydrogen, oxygen, nitrogen principle (CHON principle), actinide extraction by, 1285, 1287 Carbonate leaching, of uranium ore, 307–309, 309f, 632 benefits of, 307 flow chart of, 308, 309f oxygen for, 307–308 Carbonates of actinide elements, 1796 actinide speciation in, 3159 of actinyl complexes, 1926, 1928t, 1929f of americium, 1305t–1312t, 1319, 1340–1341 common mineral phases of, 3159, 3159t complexes of, 2583 of neptunium, 745 equilibrium constants for, 774t–775t in plasma, 3361 of plutonium, 1159–1166 application of, 1159 formation constants, 1160–1161t heptavalent, 1163–1165 hexavalent, 1165–1166 tetravalent, 1162–1163 trivalent, 1159 precipitation

I-28

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Carbonates (Contd.) with DDP, 2706, 2707f protactinium enrichment with, 174–175 sorption studies of, 3159–3164 structural chemistry of, 2426–2427, 2427t, 2428f of thorium, 108–109 crystallization of, 109 with fluoride, 109 as ligands, 129 solubility and, 127–128 synthesis of, 108–109 of uranium, 261t–263t EXAFS of, 3160–3161, 3161t formation of, 289 natural occurrence of, 291 properties of, 289–290 structures of, 290 Carbonyl complexes of actinides, 1987–1987 of d-transition metals, 2893 Carboxylates complexes of, 2584, 2585t–2586t, 2586–2587, 2590 entropy change, 2557, 2558t of curium, 1429 of neptunium (IV), EXAFS investigations of, 3137–3140, 3147t–3150t organophosphorus ligands v., 2585t–2586t, 2588 of plutonium, 1176–1181, 1178t structural chemistry of, 2437–2448, 2438f, 2439t–2443t, 2443f–2447f acetates, 2439t–2440t, 2440–2445, 2444f di-, 2441t–2443t, 2445–2448, 2445f–2447f dipicolinates, 2441t–2443t, 2446–2447, 2446f formates, 2437–2440, 2439t–2440t malonates, 2441t–2443t, 2447–2448 mono-, 2438–2445, 2439t–2440t, 2444f overview of, 2437 oxalate, 2441t–2443t, 2445–2446, 2445f tetra- and hexa, 2443t, 2448 of thorium, 113–114 EXAFS investigations of, 3137–3140, 3147t–3150t in solvent extraction, 113–114 of uranyl (VI), EXAFS investigations of, 3137–3140, 3141t–3150t Carnotite description of, 297–298 natural occurrence of, 297–298 plutonium in, 822 uranium production with, 297 Catalytic processes, by organoactinides, 2911–3006 alkyne dimerization, 2930–2947 promotion of, 2938–2947, 2940f–2941f

terminal, 2930–2935 terminal ansa-, 2935–2937 alkyne hydroamination, 2981–2990 kinetic studies of, 2986–2990 neutral organoactinide complex promotion, 2981–2986 alkyne oligomerization, 2923–2930 bisacetylide organoactinide, 2924–2925 cross, 2929–2930 key intermediate complex in, 2926, 2926f terminal, 2925–2926, 2928f amine, silane reactions, 2978–2981 azide and hydrazine reduction, 2994–2996 constrained-geometry hydroamination, 2990–2994 heterogeneous, 2999–3006 active site assessment, 3000–3002 alkane activation, 3002–3006 arene hydrogenation, 2999–3000 olefin hydrogenation, 2996–2997 olefin hydrosilylation, 2953–2978 of alkenes, 2969–2974 promotion for alkynes, 2974–2978 promotion for terminal alkynes, 2964–2969 of terminal alkynes, 2953–2964 olefin polymerization, 2997–2999 reactivity, 2912–2923 activation modes, 2912–2913 alkyne and silane stoichiometric reactions of, 2916–2918, 2917f [(Et2N)3U][BPh4], 2922–2933 stoichiometric reactions of, 2913–2916, 2914f–2915f synthesis of ansa- complexes, 2918–2920, 2920f synthesis of high-valent organouranium complexes, 2920–2922, 2921f terminal alkyne cross dimerization, 2947–2952, 2948f–2949f Catalyzed ignition, of plutonium, 3236–3237 Catcher foil. See Foil Catecholamine (CAM) complexes of, 2590–2591 for plutonium removal, 1824 Catecholate ligands, as chelating agents, 3414–3416, 3415f Cation exchange of berkelium, 1449–1450 of californium, 1512 of curium, 1433 historical development of, 2636–2641, 2637f for trace analysis, 3282–3283 of uranium, 633 Cation-cation interaction actinide complexes of, 2593–2596, 2596f, 2596t model of, 2593–2595

Subject Index

I-29

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 structures of, 2595, 2596f thermodynamic properties of, 2595–2596, 2596t in neptunium (V) coordination complexes, 748 in pentavalent and hexavalent actinides, 1356 Cation-exchange chromatography for actinium purification, 30–32, 31f for americium purification, 1290–1291 chromatographic elution schemes, 1290–1291 distribution coefficients, 1290 for dubnium extraction, 1704–1705 for fermium purification, 1629 for lawrencium extraction, 1643, 1645 for rutherfordium extraction, 1699–1700 for seaborgium extraction, 1710–1711 CC. See Complexant concentrate CCF. See Correlation crystal-field CCSDs. See Single double coupled cluster excitations Central field approximation effective-operator Hamiltonian with, 2027 for free-ion interactions modeling, 2020–2023 overview of, 2020 Ceramic capacitors, protactinium in, 189 Cerium americium interaction with, 1302 berkelium separation from, 1449 extraction of, TALSPEAK for, 2672 Cerium (IV), detection of, VOL, 3061 Cerocene, thorocene v., 1947 Cesium, with thorium sulfates, 105 CF. See Crystal-field Chain structures factors in, 579 in soddyite, 293 in studtite, 288–289 of uranium phosphates and arsenates, 295–296 in uranyl minerals, 281 selenites and tellurites, 298 in weeksite, 292–293 Chalcogenides of americium, 1305t–1312t, 1316–1317 coordination of, 1358–1359 of berkelium, 1464t–1465t, 1470 preparation of, 1460 of californium, 1530t–1531t, 1539–1540 of curium, 1413t–1415t, 1420–1421 cyclopentadienyl complexes with, 2837 of neptunium, 739–742 selenides, 740–741 sulfides, 739–740 tellurides, 741–742 of plutonium, 1023–1077

oxides, 1023–1052 sulfides, tellurides, and selenides, 1052–1056 ternary and polynary, 1056–1069 ternary oxides, 1069–1070 structural chemistry of, 2409–2414, 2412t–2413t, 2414f thermodynamic properties of, 2203t, 2204–2205 of thorium, 75t, 95–97 structures of, 95–96 of uranium, 412–420, 414t–417t Charge-density waves, quantization of, 2317–2318 Charge-transfer transitions of actinide ions, 2085–2089 of neptunyl, 2089 overview of, 2085–2086 of uranyl, 2086–2089 Chelate chromatography, neptunium extraction with, 714–716, 715f Chelate formation, by glycolate and acetate, 590 Chelating agents desferrioxamine, 3414 for plutonium removal examples of, 1822–1823 new, 1824–1825 problems with, 1823–1824 polyaminopolycarboxylic acids, 3413–3414 siderophores, 3414–3423 Chemical methods for transactinide elements, 1734–1735 of uranium ore processing, 302 Chemical precipitation, for uranium leach recovery, 313–314 history of, 313 materials for, 314 process of, 313–314 Chemical reactions, of uranium metal, 327, 327t Chemical reactivity of neptunium hexafluoride, 733–734 of thorium, 63 Chemical transport reactions, for uranium oxide preparation, 343 Chernikovite at Oklo, Gabon, 271–272 uranium in, 259t–269t Chitosan, uranyl adsorption on, 2669 Chloride solutions, for americium purification, 1291–1292 Chlorides of actinide elements, 1796 of berkelium, 1468–1470 of californium, 1532–1534 absorption spectra of, 1542–1544, 1544f complexes of, 2579–2580, 2581t

I-30

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Chlorides (Contd.) of curium, 1413t–1415t, 1417–1418 of dubnium, 1703, 1705 of einsteinium, 1595 Gibbs energy of formation for, 2710t of neptunium, 736–737 equilibrium constants for, 772t tetrachloride, 736–737 trichloride, 737 of plutonium, 1092–1100 preparation of, 1092–1095 properties of, 1087t, 1098–1100 solid-state structures of, 1084t, 1096–1097, 1096f–1098f of protactinium derivatives of, 197–199, 198f, 207 protactinium (V), 213, 215t in pyrochemical methods, 2694–2700 americium, 2699–2700 curium and transcurium, 2700 neptunium, 2697–2698 plutonium, 2698–2699, 2699f protactinium, 2695 thorium, 2694–2695 uranium, 2695–2696, 2697f of seaborgium, 1707 TRUEX processing of waste, 2742, 2742f of uranium anhydrous complexes, 450–452 complexes, 492–493, 523–524 dioxide dichloride, 567–569 hexachloride, 567 nitride, 500 oxide, 524–525 oxochloride, 525–526 pentachloride, 522–523 perchlorates, 494 perchlorates and related compounds, 570–571 tetrachloride, 490–492 trichloride, 446–448, 447f trichloride hydrates, 448–450 Chlorination, of dubnium, 1705 Chlorinator-electrolyzer, for DDP, 2707 Chlorine, from radiolysis, 1145–1146, 1146t Chloroplutonate compounds application of, 1104 phase diagram of, 1104, 1108f preparation of, 1104 properties of, 1108, 1109t CHON principle. See Carbon, hydrogen, oxygen, nitrogen principle Chromates of americium, 1321 of neptunium, equilibrium constants for, 775t of thorium, 112 structure of, 112 synthesis of, 112

Chromatography, overview of, 3067 CI. See Configuration interaction Circulation. See Plasma Citrates in plasma, 3360–3361 for plutonium removal, 1823 for separation, 2638–2639, 2639t of thorium, as ligands, 131, 132t Citrobacter sp., uranyl phosphate precipitation by, 297 Clarification, in uranium ore processing, 308–309 Clarkeite, transformation of, 288 Clay groups of, 3151–3152 silicates in, 3151 for SNF storage, 1813 Cliffordite, as uranyl tellurite, 298 CMPO. See Carbamoylmethylenephosphine oxide; n-Octyl(phenyl)-N,N-diisobutylcarbamoyl methylphosphine oxide Cobalt, plutonium melting point and, 897 Coffinite natural occurrence of, 275–276 at Oklo, Gabon, 271–272 structure of, 586, 587f uranium in, 259t–269t, 274 Cohesion properties of actinide metals, 2368–2371 in transplutonium materials, 2370–2371 COL. See Colorimetry COLD. See Cryo On-Line Detector ‘Cold’ fusion, element production by, 1737 Colloidal materials, actinide association with, 3287–3288 Color of actinium, 34–35 of protactinium, 194 of thorium, 61 Color cathode ray tube, protactinium for, 188–189 Colorant, uranium as, 254 Colorimetry (COL), for environmental actinides, 3034t, 3035 Column partition chromatography. See Partition chromatography Comilling, of plutonium and uranium oxides, 1074 Complexant concentrate (CC), TRUEX process for, 2740 Complexation of actinide elements, 1782–1784, 2524–2607 bonding, 2556–2563 cation hydration, 2528–2544 cation hydrolysis, 2545–2556 cation-cation complexes, 2593–2596 complexation reaction kinetics, 2602–2606

Subject Index

I-31

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 complexes, 2577–2591 correlations, 2566–2577 in hydrosphere, 1808–1809 inner v. outer sphere, 2563–2566 redox reaction kinetics, 2597–2602 ternary complexes, 2591–2593 of actinium, 40, 41t of americium, 1338–1356, 1339t by carbonate, 1340–1341 hydrolysis, 1339–1340 by organic ligands, 1341, 1342t–1352t, 1353–1354, 1353f by others, 1354–1356 of berkelium, 1475–1479, 1477t–1478t of californium, 1549–1555, 1550t–1553t of dubnium, 1705 effect of, 2601–2602, 2602t of einsteinium, 1607–1609 of fermium, 1629 inner v. outer sphere, 2563–2566, 2566f, 2567t kinetics of, 2602–2606, 2605f, 2606t americium, 2604–2605 Eigen mechanism, 2602–2603 multidentate ligands, 2603–2604 simple v. complex, 2602 trivalent complexes, 2605–2606, 2605f, 2606t in mammalian body, 3340 of mendelevium, 1635 of plutonium, 1156–1182 carbonates, 1159–1166, 1160t–1161t carboxylates, 1176–1181, 1178t cation-cation, 1181–1182 halides, 1181 iodates, 1172–1173 nitrates, 1160t–1161t, 1167–1168 overview of, 1156–1158 oxalates, 1173–1175 oxoanions, 1158–1176 perchlorates, 1173 peroxide, 1175–1176 phosphates, 1160t–1161t, 1170–1172 sulfates, 1160t–1161t, 1168–1170 of seaborgium, 1710–1711 of thorium, 129–133, 130t coordination compounds for, 115 formation constants, 131, 132t inorganic ligands, 129–131, 130t solubility curves of, 129 stability constants, 129, 130t study of, 130–131 of transactinide elements, 1687–1689 Complexation enthalpy of complex halides, 2182, 2183t–2184t, 2185f of halides, 2578–2580, 2579t, 2581t

Composition-pressure-temperature relationship, of plutonium dioxide, 1031, 1031f Compreignacite at Shinkolobwe deposit, 273 uranium in, 259t–269t Condensed phase actinide thermodynamic properties in, 2115–2118, 2119t–2120t, 2121f entropy, 2115–2116, 2116f high-temperature properties, 2116–2118, 2117t, 2119t–2120t, 2121f energy levels and free-ion correlation with, 2037–2039, 2038t ion electronic structures in, 2036–2037 Configuration interaction (CI) of actinide elements, 1852 cyclopentadienyl complexes, 1958 for excited state energy calculations, 1910 for relativistic correlation effects, 1670 Congruently vaporizing composition (CVC), of uranium oxides, 365 Conversion chemistry, precipitation and crystallization for, of plutonium, 836–839 plutonium (III) oxalate precipitation, 836–837 plutonium (IV) oxalate precipitation, 837 plutonium (IV) peroxide precipitation, 837–838 Coordination chemistry of cyclopentadienyl complexes, trivalent, 2804 water in, 3096 Coordination compounds of berkelium, 1471 of neptunium, 745–750 structural chemistry of, 2436–2467 calixarenes, 2456–2463, 2457t–2458t, 2459f, 2461f–2463f with carboxylic acids, 2437–2448, 2438f, 2439t–2443t, 2443f–2447f crown ethers, 2448–2456 overview of, 2436–2437 porphyrins and phthalocyanines, 2463–2467, 2464t, 2466f–2467f of thorium, 114–115 ligands of, 115 properties of, 115 Coordination geometry in actinide complex bonding, 2558–2560, 2559f of americium, 1327, 1328f chalcogenides, 1358–1359 cyclopentadienyl and cyclooctatetraenyl compounds, 1363–1364 halides, 1356–1357, 1358f inorganic ligands, 1356–1361

I-32

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Coordination geometry (Contd.) nitrogen-donor ligands, 1363 others, 1361 oxides, 1357–1358, 1358f oxoanionic ligands, 1359–1360, 1360f oxygen-donor ligands, 1361–1362 pnictides, 1358–1359 silicides, 1359 sulfur-donor ligands, 1363 bond distance and oxidation states with, 3093 hexagonal bipyramidal of uranyl (V), 588–589 of uranyl (VI), 580–581, 580f, 582f–583f of neptunium in biological systems, 1814 metallic state, 719 pentagonal bipyramidal of uranyl (V), 589 of uranyl (VI), 580, 581f–582f peroxide complexes, of uranyl (VI), 583–584, 584f of plutonium, 883, 887t, 1112, 1157 anions, 1158–1159 six-coordination, of uranyl (VI), 582, 583f structure and, 579 of uranium hydroxide complexes, 600 uranium (III), 610 uranium (IV), 595, 610 uranium (V), 610 uranium (VI), 610 uranyl (VI), 580–584, 580f–584f, 3132 Copper spark method, for protactinium, 226 Copper, with thorium molybdates, 112 Coprecipitation bismuth phosphate for, 2634 of californium, 1547–1548 historical development of, 2627–2628 of mendelevium, 1633, 1635 methods of, 3281–3282 of neptunium, 716 for oxidation state extraction, 3287 of plutonium, 833–835 bismuth phosphate process, 835 lanthanum fluoride method for, 833–835 oxides with uranium oxides, 1074 for sample concentration, 3023 for separation, 2633–2634, 3281–3282 of uranium oxides with plutonium oxides, 1074 of uranyl ion, with iron-bearing mineral phases, 3168–3169 Core-level spectra, of plutonium, 861 Correlation crystal-field (CCF), Hamiltonian of, 2054–2055 Corrosion of curium metal, 1412

nitrogen in, 3212 of plutonium catalyzed, 3236–3237 dry, 3227–3228 hydrogen- and hydride-catlyzed, 977–979 kinetic behavior, 3225–3227 metal and intermetallic compounds of, 973–979, 3223–3238, 3226f, 3227t, 3229t salt-catalyzed, 3238 thermal ignition, 3232–3235 unalloyed, 3231–3232 by water vapor, 3228–3230 rates of, 3200–3201 plutonium metal, 3225–3226, 3226f of uranium with hydrogen, 3239–3242, 3240f, 3241t kinetics of, 3239–3246 metal, 327–328, 327t with oxygen, water, and air, 3242–3245, 3243f, 3244t uranyl with water, 3239 COUL. See Coulometry Coulomb repulsion, in actinide metals, 2325 Coulometry (COUL) for berkelium, 1484 for californium, 1548–1549 for environmental actinides, 3049t, 3052 for mendelevium, 1636 for neptunium, 757–759, 758f determination of, 790–791 Coulopotentiogram, of neptunium, 758–759, 758f Counter-current leaching, of uranium ore, 306 Coutinhoite, description of, 293 Covalency in actinide complex bonding, 2561–2562, 2563t in actinocene, 1948–1949, 1948f in plutonium, 1191–1192 dioxide, 1196–1199, 1197f, 1200f hexafluoride, 1193–1196 of uranium tetrachloride, 2249–2251 in uranocene, 2854, 2855f in uranyl ion, 1915–1916 CP. See Cupferron Critical mass, of americium, 1268 Critical parameters, plutonium–239, 820–821, 821t Cross-relaxation, of luminescence, 2103 Crown ether, complexes of, 2590 description of, 2448–2449 structural chemistry of, 2448–2456 Cryo On-Line Detector (COLD), for hassium study, 1713, 1714f Cryo-Thermochromatographic Separator (CTS), for hassium study, 1712–1713

Subject Index

I-33

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Crystal chemistry site distortion in, 2047 of uranium (IV), 281 Crystal morphology, prediction of uranium (IV) sheets, 286–287 Crystal structure. See also Structure of actinide elements metallic state, 1785–1787, 1786t solid compounds, 1798 of actinide metals, 2312–2313, 2312f, 2320 low-symmetry, 2330–2331, 2331t, 2369–2370 of actinocenes, 1943–1944, 1944t, 1945f Brillouin zones in, 2321 mechanical properties and, 968 of neptunium dioxide, 2287–2288, 2287f optimization of, 2048–2049 of plutonium, 879, 881t dioxide, 2289–2290 Crystal-field (CF), ground state of magnetic susceptibility and, 2226 uranium dioxide, 2274 Zeeman interaction and, 2225–2226 Crystal-field Hamiltonian corrections to, 2053–2056 ECM with, 2052–2053, 2053t free-ion Hamiltonian with, 2041 matrix element evaluation with, 2039–2042 parameters of, 2054–2055 initial, 2048 symmetry rules for, 2043 of trivalent ions, 2056 Crystal-field interactions of 5f1 compounds, 2242–2243 of 5f7 compounds, 2265 of actinide fluorides, 2071, 2073f of actinide ions, importance of, 2076 crystal field parameters empirical evaluation, 2047–2049 theoretical evaluation, 2049–2053 crystal-field Hamiltonian corrections to, 2053–2056 matrix element evaluation and, 2039–2042 free-ion and condensed phase correlation, 2036–2039, 2038t free-ion interactions with, 2044, 2062–2064, 2063t magnetic field with, 2044 modeling of, 2036–2056 symmetry rules, 2043–2047 tensor operators for, 2040 weak in crystals, 2055 Crystal-field operators geometric properties of, 2043 for ions, 2043–2044 Crystal-field parameters, 2044, 2045t accuracy of, 2047

calculation of, 2050–2052 computation of, 2058 effective-operator Hamiltonian with, 2050 empirical evaluation of, 2047–2049 expression of, 2051 free-ion states and, 2056 tetravalent ions, 2074 of neptunium dioxide, 2284 quantum mechanical calculations of, 2049 rank 2, 2051–2052 rank 4, 2052 rank 6, 2052 signs of, 2048–2049 theoretical evaluation, 2049–2053 of uranocene, 2253 Crystal-field splittings of 5f states of actinide ions, 2081, 2082f computation of, 2076 contributions to, 2054 of curium (III), 2266 of f-element spectroscopy, 2074–2075 of plutonium dioxide, 2288–2289 of tetravalent actinides, 2075–2076 of uranium dioxide, 2278–2279 tetrachloride, 2249 uranium (III), 2057–2058, 2057f uranium (IV), 2247–2248 Crystal-field theory for f-element ions in crystals, 2047–2048 for uranium dioxide, 2278, 2279f Crystallization of einsteinium, 1607 of mendelevium, 1636 of plutonium, 831–839 conversion chemistry, 836–839 precipitation v., 832–833 Crystallography, of organometallic actinide compounds, 1800 CTS. See Cryo-Thermochromatographic Separator Cupferron (CP), protactinium extraction with, 184 Cupferronates, of protactinium, gravimetric methods with, 230–231 Cuprosklodowskite at Shinkolobwe deposit, 273 uranium in, 259t–269t Curie law for 5f6 compounds, 2264 for magnetic susceptibility data, 2230 Curie-Weiss law for einsteinium (III), 2271 for magnetic susceptibility data, 2230–2231 of UBe13, 2342, 2343f for uranium (IV) compounds, 2254

I-34

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Curite anion topology of, 283, 284f–285f from clarkeite, 288 at Koongarra deposit, 273 uranium in, 259t–269t with uranium phosphates, 294 Curium, 1397–1434 analytical chemistry of, 1432–1434 analysis of, 1432–1433 separations, 1433–1434 aqueous chemistry of, 1424–1432 inorganic, 1424–1430, 1426t–1428t organic, 1426t–1428t, 1430–1432 atomic properties of, 1402–1406, 1403t absorption spectra, 1402–1404, 1404f–1405f electronic structure, 1404–1405 fluorescence spectroscopy, 1405–1406, 1406f in biological systems, ingestion and inhalation of, 1818–1820 complexes of cyclopentadienyl, 2803 tris-cyclopentadienyl, 2470–2476, 2472t–2473t compounds of, 1412–1424 chalcogenides, 1413t–1415t, 1420–1421 general, 1412–1416, 1413t–1415t halides, 1413t–1415t, 1417–1418 hydrides, 1413t–1415t, 1416–1417 organometallics, 1413t–1415t, 1423–1424 oxides, 1413t–1415t, 1419–1420 pnictides, 1413t–1415t, 1421 difficulty of working with, 1397–1398 discovery of, 5t, 8 half-life of, 1399t, 1400 history of, 8, 1397–1398 ionization potentials of, 1874t isotopes of, 9–10, 12, 1397–1400, 1399t lanthanide elements v., 2 magnetic properties of, 2355–2356 metallic state of, 1410–1412 chemical properties of, 1412 magnetic susceptibility, 2266, 2267t, 2268 physical properties of, 1410–1411, 1413t–1415t preparation of, 1411–1412 structure of, 2387–2388 natural occurrence of, in marine organisms, 1809 nuclear properties of, 1398–1400, 1399t oxidation states of, 1416, 2526 in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t in plutonium alloy δ-phase lattice, 930f, 931–932 elastic constants, 943

solubility ranges, 930, 930f thermal conductivity, 957 plutonium v., 935 production of, 1400–1402, 1758–1759 pyrochemical methods for, molten chlorides, 2700 quadrupole moments of, 1884, 1884f reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f separation and purification of, 1407–1410 from americium, 2672–2673 DDP, 2706 ion exchange, 1409–1410 precipitation, 1410 solvent extraction, 1407–1409 TALSPEAK for, 2672 synthesis of, 8–9 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f UO2 solid solutions with oxygen potentials of, 394–396, 395t properties of, 391t–392t, 392 Curium (II), 1430 stabilization of, 2077 Curium (III) absorption spectra of, 1402–1404, 1404f aqueous chemistry of, 1424–1432, 1426t–1428t chlorides of, magnetic data, 2229–2230, 2230t complexation of, 1424–1430, 1426t–1428t TTA, 2532 detection of limits to, 3071t TRLF, 3037 UVS, 3037 electronic structure of, 1404–1405 energy levels of, 2075–2076, 2075f energy levels, structure of, 2059–2061 excitation spectra of, 2061–2062, 2061f extraction of, 1431 aminopolycarboxylic acid, 1286 HDEHP, 1409 organophosphorus and carbamoylphosphonate reagents, 1276–1278 fluorescence decays of, 2101–2102, 2101f hydration numbers of, 2534, 2535f, 2535t–2536t in concentrated solutions, 2536–2538, 2537f

Subject Index

I-35

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 hydration of, 2528–2530, 2529f, 2529t hydrolytic behavior of, 2546, 2548t in hydrosphere, 1807–1810 luminescence of, 2096–2097, 2097f study of, 2098–2099 magnetic properties of, 2265–2268 in mammalian tissues circulation clearance of, 3368–3369, 3368f–3375f, 3371–3376 glycoproteins, 3410–3411, 3411t initial skeletal fractions of, 3349 transferrin binding to, 3365 oxidation of, 1416, 1429–1430 purification of from americium (III), 1410 zirconium based sorbents, 1409 separation from americium, 1271 solution reactions of, 1424–1425, 1425f speciation of, 3110, 3114t stability constants of, 1425, 1426t–1428t TRLF of, 2534–2535, 2536t Curium (IV) absorption spectra of, 1402–1404, 1405f complex of, 1416 electronic structure of, 1404–1405 excitation spectra of, 2068, 2071f magnetic properties of, 2263–2265 magnetic susceptibility of, 2264–2265 TIP of, 2263–2264 preparation of, 1429–1430 uranium (IV) v., coordination numbers, 585–586 Curium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Curium dioxide, 1413t–1415t, 1419 enthalpy of formation, 2136–2137, 2137t, 2138f heat capacity of, 2138–2141, 2139f, 2142t IPNS of, 2292–2293 magnetic properties of, 2292–2293 magnetic susceptibility of, 2293 structure of, 2397 Curium hydrides entropy of, 2188, 2189t formation enthalpy of, 2187–2188, 2187t, 2189t, 2190f high-temperature properties of, 2188–2190, 2190t structure of, 2404 Curium monoxide dissociative energy of, 2149–2150, 2150f structure of, 2396 Curium nitrate, 1413t–1415t, 1422 Curium oxalate, 1413t–1415t, 1419, 1421–1422 Curium oxides, structure of, 2396–2397 Curium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Curium oxysulfate, 1413t–1415t, 1420

Curium peroxide, in americium separation, 1271 Curium phosphates, 1413t–1415t, 1422 structural chemistry of, 2430–2433, 2431t–2432t Curium pnictides, structure of, 2409–2414, 2410t–2411t Curium sesquioxide, 1413t–1415t, 1419–1420 formation enthalpy of, 2143–2146, 2144t, 2145f in gas-phase, 2148t, 2149 high-temperature properties of, 2139f, 2146–2147 structure of, 2396–2397, 2396t Curium sesquiselenide, 1413t–1415t, 1420 Curium sesquisulfide, 1413t–1415t, 1420 Curium sulfate, 1413t–1415t, 1422 Curium tetrafluoride, 1413t–1415t, 1418 Curium tetrahalides, structural chemistry of, 2416, 2418t Curium tribromide, 1413t–1415t, 1417–1418 Curium trichloride, 1413t–1415t, 1417 Curium trifluoride, 1413t–1415t, 1417 Curium trihalides, structural chemistry of, 2416, 2417t Curium trihydroxide, 1413t–1415t, 1421 Curium–242 alpha decay of, 1432 from americium–242, 1759 applications of, 1398–1400 californium–244 from, 1499 detection of, limits to, 3071t heat output of, 1398 history of, 1397–1398 nuclear properties of, 3277t plutonium–238 from, 817 production of, 1401–1402 solutions of, 1424–1425, 1425f study of, 1765 Curium–243 alpha decay of, 1432 detection of, αS, 3296 nuclear properties of, 3277t Curium–244 alpha decay of, 1432 from americium–244, 1759 applications of, 1398–1400 detection of ICPMS, 3328 limits to, 3071t αS, 3296 half-life of, 1759 heat output of, 1398 history of, 1398 isolation of, 1401–1402 nobelium from, 1636–1637 nuclear properties of, 3277t plutonium–240 from, 862

I-36

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Curium–244 (Contd.) production of, 1400–1401 radioactivity of, 1759 study of, 1765 Curium–245, production of, 1400–1401 Curium–246, production of, 1400 Curium–247, production of, 1400 Curium–248 berkelium alloy with, 1462 from californium–252, 1505 for hassium production, 1713 history of, 1398 lawrencium from, 1641 neutron emission from, 1505 production of, 1400–1401 study of, 1765–1766 for transactinide element production, 1661–1662 Curium–249, decay of, 1447 Curium–252, detection of, NAA, 3055–3057, 3056t, 3058f Cyanates, of actinide elements, 1796 Cyanex 301 americium (III) extraction with, 1287–1289, 1288f, 2675–2676 concerns of, 1288–1289 disadvantages of, 1289 for solvent extraction, 2665 trivalent actinide/lanthanide separation, 2762–2763 Cyanides, of actinide elements, 1796 Cycloheptatrienyl complexes, of uranium, 2253–2254 Cycloheptatrienyl ligand, 2860–2862 bonding in, 2862, 2863f formation of, 2860–2861 structure of, 2861–2862, 2862f Cyclooctadienyl compounds, americium ligands of, 1363–1364 Cyclooctatetraene complexes of americium, 1323t, 1324 of plutonium, 1188–1189 structural chemistry of, 2485–2487, 2488t, 2489f Cyclooctatetraenyl complexes, 2851–2858 americium ligands of, 1363–1364 bonding in, 2853–2854, 2854f bridging in, 2857, 2857f cationic derivatives of, 2857–2858 chemistry of, 2851, 2856–2857 electron transfer rates in, 2856 metathesis reactions, 2857 pentavalent, 2858 ring dynamics of, 2854–2855 single ring, 2856–2857 synthesis of, 2851–2852 trivalent derivatives of, 2855–2856 uranocene derivatives, 2851–2853, 2852f

Cyclooctatetraene compounds, of neptunium, 751–752 Cyclopentadiene complexes, of americium, 1323t, 1324 Cyclopentadienyl complexes, 2800–2851 of actinide elements, 1801–1803, 1952–1959 3 ligands þ X, 1956–1957 4 ligands, 1953–1954 ‘base-free’ 3-ligand, 1954–1956, 1955f metal-metal bonds, 1958–1959 mixed ligands, 1957–1958 overview of, 1952–1953, 1953f structure of, 1953, 1953f of berkelium, 1464t–1465t, 1471 bimetallic complexes and, 2890 of californium, 1544 dicarbollide complexes v., 2868 hexavalent, 2847–2851 adamantylimido complex, 2850 bis(imido), 2848–2850 geometry of, 2847–2848 heteroatom substitution, 2850–2851 prevalence of, 2847 reactivity of, 2847–2850 structure of, 2847, 2849f synthesis of, 2847–2849, 2848f of neptunium, 750–751 pentavalent, 2845–2847 electronic structure, 2847 preparation of, 2845–2847, 2846f prevalence of, 2845 structure of, 2846f, 2847 phospholyl complexes v., 2869 of plutonium, 1189–1191 pyrazolylborate v., 2880 structural chemistry of, 2468–2485 bis, 2476–2482, 2478f, 2479t–2480t, 2481f–2483f mono, 2482–2485, 2484t, 2485f–2487f tetrakis, 2469, 2469t, 2470f tris, 2470–2476, 2472t–2473t, 2474f–2475f, 2477f tetravalent, 2814–2845 alkali metal reagents, 2844 alkyl or aryl ligands, 2539f, 2819–2820, 2820f, 2837–2839 amide complexes, 2832 bis(indenyl) complex, 2827 bonding and structure of, 2815–2817, 2816f, 2816t, 2818f carbon dioxide reactions, 2824 carbon monoxide reactions, 2821–2824 cationic species, 2818–2819 chalcogenide complexes, 2837 dialkyl complexes, 2840 Group 14 derivatives, 2820–2821 history of, 2815 importance of, 2814–2815

Subject Index

I-37

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 indenyl complexes, 2844 isocyanide ligand insertion, 2825, 2826f metal-carbon bond in, 2825–2826 metathesis and protonation routes for, 2819, 2831–2833, 2845 mono-ring complexes, 2843–2844 organoimido complexes, 2833–2835 pentamethyl- ligand, 2827–2829, 2829f phosphide complexes, 2832–2833 phosphine imide complex, 2825 phosphinidene complexes, 2833, 2834f–2835f, 2835 phosphorylide complex, 2826, 2828f polypnictide complexes, 2836 pyrazole adduct, 2830 reaction patterns, 2841–2843, 2842f reactions for, 2817–2818 stabilization of, 2829–2830, 2831f thermochemistry, 2821, 2822t, 2840–2841, 2840t thiolate complexes, 2836–2837 of thorium, 116 trivalent, 2800–2814 anionic reactions of, 2806 cationic complex, 2812 chalcogen transfer reagents, 2808 coordination chemistry of, 2804 dimeric, 2812, 2813f dioxygen reaction, 2808 electronic structure of, 2803 metal-to-ligand donation, 2806, 2807f monomeric adducts, 2810–2812, 2811f oxidation reactions, 2807–2809, 2814 permethylated, 2803–2804 reduction of, 2801–2802 solubility of, 2802 starting material for, 2802 structure of, 2802 synthesis of, 2800–2801, 2801t, 2803 trimeric, 2809–2810 of uranium (III), 2812, 2813f uranium triiodide THF, 2813–2814 D2EHIBA. See Di–2-ethylhexyl isobutylamide DAAP. See Diamyl(amyl)phosphonate Damage recovery, of plutonium, 982–983, 983f Darmstadtium chemical methods for, 1720–1721 chemical properties of, 1717–1721 discovery of, 6t, 1653 electronic structures of, 1682–1684 half-life of, 1719 isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659

oxidation states of, 1720 production of, 1719–1720 relativistic orbital energies for, 1669f solution chemistry of complexation of, 1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f Darmstadtium–292, half-life of, 1736 Dating, with protactinium–231, 231 and thorium–230, 170–171 and uranium–235, 189 DBBP. See Dibutyl butylphosphonate DBM. See Dibenzoylmethane DCB. See Dirac-Coulomb-Breit Hamiltonian DCTA. See 1,2-Diaminocyclohexane tetraacetic acid DDCP. See Dibutyl-N,Ndiethylcarbamylphosphonate DDP. See Dimitrovgrad Dry Process de Haas-van Alphen frequencies, of UIr3, 2334, 2335f 4n þ 2 decay chain thorium–230 from, 53 thorium–234 from, 53 uranium–238 in, 255–256 Decay chains of actinium, 20–26, 21f–26f of berkelium–249, 1447 of berkelium–250, 1447 of bohrium–267, 1711 of einsteinium–253, 1447 of hassium–269, 1714 of hassium–270, 1714 of plutonium, 1143–1146 of uranium, 21f Decay process, heat generation in, 985–986 Decomposition acid, 3279–3281 fusion, 3278–3279 for trace analysis, 3278–3281 Decontamination, of irradiated nuclear fuel, 826, 828–830 DEH. See N,N-Diethyl hydroxylamine Delayed neutron activation analysis (DNAA), for environmental actinides, 3056t, 3057 δ-Phase, of plutonium, 882–883, 882f–883f, 886f 5f-electrons, 925 atomic volume, 923, 923f density of, 935–937, 936t DFT predictions of, 2329–2330, 2330f diffusion rate, 958–960, 959t, 961f elastic constants, 942–943, 944t, 946f electrical resistivity of, 955–957, 955f–956f, 2345–2347, 2346f field expansion, 892–897 heat capacity, 945–947, 950t–951t

I-38

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 δ-Phase, of plutonium (Contd.) heavy-fermion behavior of, 2342 lattice changes in, 981–982, 982f, 982t, 984 magnetic properties of, 2355 magnetic susceptibility, 949, 953–954, 953f microsegregation, 899, 916–917 phase transformations, 917–921, 918f–920f self-irradiation defects in, 986 solid solubility of, 927 solubility ranges of, 930, 930f stability and alloying of, 928–929 strength of, 968f, 970–971 thermal conductivity, 957 thermal expansion, 938t, 939–942, 940f thermoelectric power, 957–958, 958t uranium and neptunium influence on, 985 Demesmaekerite, as uranyl selenite, 298 Density functional theory (DFT) of actinide metals, 2326–2328 of actinocenes, 1947–1948 basis of, 1903 charge density with, 2330 δ-phase plutonium and, 925, 929, 2329–2330, 2330f developments of, 1904 electronic structure and bonding properties with, 923–924 for ground state properties calculation, 1671 in HF calculations, 1903 of neptunium neptunium (III), 3116 neptunium (VII/VI), 3125 for thorium, 3105 total energy functional of, 2327–2328 of uranium dioxide, 1973 hexafluoride, 1935–1937, 1936t of uranyl, 1920–1921 hydroxide complexes, 1925 Density, of plutonium, 935–937, 936t oxides with uranium oxides, 1075–1076 Density of states (DOS) of actinide metals, 2318f, 2319 description of, 2316–2317 Fermi-Dirac distribution function with, 2320 of UIr3, 2338, 2338f Depleted uranium (DU) description of, 1755 in environment, 3173–3174 scope of concern of, 3202 Derriksite, as uranyl selenite, 298 Descent-of-symmetry method complications of, 2046 use of, 2044 Desferrioxamine (DFO) as chelating agents, 3414

iron removal with, 1824 for plutonium removal, with DTPA, 1824 Deuterides, of plutonium, 989–996 applications, 995–996, 996f electronic structure of, 995, 995t history of, 989 physical properties of, 990, 995, 995t preparation and reactivity of, 989–990 solid state structures, 992–994, 993f, 993t stoichiometry and phase relationships, 990–992, 991f–992f storage and handling of, 989 Dewar-Chatt-Duncanson model, of synergic bonding, 1956 Dewindite, description of, 297 DF. See Dirac-Fock DΦDBuCMPO. See Diphenyl-N,Ndibutylcarbamoylmethylenephosphine oxide DF-LCAO. See Dirac-Fock linear combination of atomic orbitals DFO. See Desferrioxamine DFT. See Density functional theory DHDECMP. See Dihexyl-N,Ndiethylcarbamoylmethyl phosphonate DHHA. See Di-n-hexyl hexanamide Di–2-ethylhexyl isobutylamide (D2EHIBA) protactinium extraction with, 184 for THOREX process, 2736 Dialkyl complexes, with cyclopentadienyl, 2840 Dialysis, for sample concentration, 3023 DIAMEX process, for actinide extraction, 1769, 2657–2658 Diamide extractants actinide extraction with, 1285–1286, 1408 overview of, 1285 1,2-Diaminocyclohexane tetraacetic acid (DCTA) fermium complexes with, 1629 mendelevium complexes with, 1635 Diamyl(amyl)phosphonate (DAAP) for THOREX process, 2736 in U/TEVA•Spec, 3284 1,3-Diazidobenzene, cyclopentadienyl complex reaction with, 2809, 2810f 1,4-Diazidobenzene, cyclopentadienyl complex reaction with, 2809, 2810f DIBC, protactinium extraction with, 182, 188 Dibenzoylmethane (DBM), actinide extraction with, 3287 Dibenzyl sulfoxide, for protactinium extraction, 181–182 DIBK, protactinium extraction with, 182 Dibutyl butylphosphonate (DBBP), americium extraction with, 1274 Dibutyl-N,N-diethylcarbamylphosphonate (DDCP), extraction with, 3282

Subject Index

I-39

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Dibutylphosphoric acid (HDBP), separation with, 2650 Dicarbollide ligands, 2868–2869 cyclopentadienyl v., 2868 generation of, 2868–2869 geometry of, 2868 Dicarboxylic acids, in plasma, 3360–3361 5,7-Dichloro–8-hydroxyquinoline, californium extraction with, 1513 DIDPA. See Diisodecylphosphoric acid N,N-Diethyl hydroxylamine (DEH), neptunium (VI) reduction with, 761 Diethylenetriamine pentaacetate (DTPA) americium separation with, 2671–2672 in bone binding study, 3408–3409 as chelating agent, 3413–3114 curium separation with, 1409, 2672 extraction with, 3282 plutonium complex with, 1176–1177, 1178t, 1179–1181 for removal, 1823 for plutonium removal, with DFO, 1824 separation with, 2640–2641 Differential pulse polarography (DPP), for environmental actinides, 3049t, 3052, 3053f Differential pulse voltammetry (DPV), for environmental actinides, 3049t, 3052, 3053f Diffusion rates of einsteinium, 1606 of plutonium, 958–960, 959t Diglycolamides, for solvating extractant system, 2659–2660 Dihalides structural chemistry of, 2415–2416 thermodynamic properties of, 2178–2179, 2180t–2181t, 2181f gaseous, 2179 solid, 2178–2179 Dihexyl-N,N-diethylcarbamoylmethyl phosphonate (DHDECMP) in actinide production, 2737–2738 americium extraction with, 1277–1278 extractant comparison with, 2763–2764, 2763t in solvating extractant system, 2655, 2656t Di-isobutylketone (DIPK), protactinium extraction with, 176, 178, 182, 188 Diisodecylphosphoric acid (DIDPA) actinide extraction with, 2753–2756 flow sheet for, 2755, 2755f overview of, 2753–2755, 2755f tests for, 2755–2756 americium extraction with, 1276 extractant comparison with, 2763–2764, 2763t neptunium extraction with, 713

Di-isopropylcarbinol (DIPC), protactinium extraction with, 175 β-Diketone complexes of actinide elements, 1783 of californium, 1554 of fermium, 1629 for oxidation state speciation, 2726 separation with, 2632, 2680 TTA v., 2650 Dimethyl oxalate, actinium precipitation with, 38 Dimethyl sulfoxide (DMSO), for protactinium extraction, 181–182 1,1-Dimethylhydrazine (DMHz), neptunium (VI) reduction with, 761 N,N-Dimethyl-N0 ,N0 -dibutyl–2hexoxyethylmalonamide, actinide extraction with, 1769 N,N-Dimethyl-N,N-dibutyl–2-tetradecyl malonamide (DMDBTDMA) actinide extraction with, 1285–1286, 2658–2659, 2756 extractant comparison with, 2763–2764, 2763t N,N0 -Dimethyl-N,N0 -dibutyldodecyloxyethyl malonamide (DMDBDDEMA), actinide extraction with, 2658 N,N0 -Dimethyl-N,N0 -dioctylhexyloxyethyl malonamide (DMDOHEMA), actinide extraction with, 2658 Dimitrovgrad Dry Process (DDP) applications, separation efficiency in, 2707–2708 dissolution for, 2705 minor actinide behavior in, 2706–2707, 2707f for MOX fuel reprocessing, 2692–2693 uranium and plutonium recovery, 2705–2706 Di-n-hexyl hexanamide (DHHA), for THOREX process, 2736 Dinonylnapthalene sulfonic acid (HDNNS), americum extraction with, 1286–1287, 2673–2675, 2674t Dioxide dichloride, of uranium, 567–570 Dioxides magnetic properties of, 2272–2294 americium, 2291–2292 curium, 2292–2293 neptunium, 2282–2288 plutonium, 2288–2290 uranium, 2272–2282 of plutonium, reactions of, 3219–3222 thermodynamic properties of, 2136–2143 enthalpy of formation, 2136–2137, 2137t, 2138f entropy, 2137–2138

I-40

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Dioxides (Contd.) high-temperature properties, 2138–2141, 2139f, 2142t nonstoichiometry, 2141–2143 Dioxouranium (V), aqua ions of, 594t, 595 Dioxouranium (VI), aqua ions of, 594t, 596, 596f DIPC. See Di-isopropylcarbinol DIPEX resin for americium extraction, 1294 for separation, 3284–3285 Diphenyl sulfoxide, for protactinium extraction, 181–182 Diphenyl-N,Ndibutylcarbamoylmethylenephosphine oxide (DΦDBuCMPO), in TRUEX process, 1283, 2739 Diphonix resin for actinide extraction, 716 for americium extraction, 1293–1294 for ion exchange, 2642–2643, 2643f Dipicolinates, structural chemistry of, 2441t–2443t, 2446–2447, 2446f Dipivaloylmethanato complex, of californium, 1541 DIPK. See Di-isobutylketone Dirac equation, for relativistic methods, 1904–1905 Dirac-Coulomb-Breit (DCB) Hamiltonian, for relativistic treatments, 1670 Dirac-Fock (DF) for electronic structure calculation, 1670, 1900 element 113–184 ground state configurations, 1722, 1722t RECPs with, 1907–1908 Dirac-Fock linear combination of atomic orbitals (DF-LCAO), for electronic structure calculation, 1670–1671 Dirac-Hartree-Fock calculations, on uranyl, 1917–1918 Dirac-HF methods, equations for, 1905 Dirac-Kohn-Sham methods, equations for, 1905 Dirac-Slater discrete-variational method (DS-DV method), for electronic structure calculation, 1671 Dirac-Slater (DS) method, for electronic structure calculation, 1670 Direct oxide reduction (DOR) MSE v., 869 for plutonium metal production, 866–869, 868f–869f furnace for, 868f process for, 866–868 results of, 868–869, 869f

in pyroprocessing, 2694 pyroredox v., 875 use of, 2692 Di-S-butylphenyl phosphonate (DSBPP), uranium extraction with, 175 Disposition options for, 3262–3266 interim storage, 3266 issues of, 3262–3263 metals and oxides, 3263–3266 of plutonium, 3199–3266 by ceramification, 3265–3266 immobilization, 3264 metal, 3263 as MOX fuel, 3263–3264 by vitrification, 3265 of uranium, 3199–3266 Disproportionation reactions of actinide complexes, 2600–2601, 2600t of americium, 1331–1332 redox behavior v., 2601 Dissimilatory metal-reduction bacteria (DMRB), redox behavior of, 3178, 3181 Dissociative energy, of actinide monoxides, 2149–2150, 2150f Dissolution, in RTILs, 2690 Distribution coefficients for americium purification, 1290 of californium, 1554 of fission products, 842, 842t of lawrencium, 1645 Dithiophosphinic acids, as trivalent actinide and lanthanide separating agent, 1289, 1408, 2676 DMDBDDEMA. See N,N0 -Dimethyl-N,N0 dibutyldodecyloxyethyl malonamide DMDBTDMA. See N,N-Dimethyl-N,Ndibutyl–2-tetradecyl malonamide DMDOHEMA. See N,N0 -Dimethyl-N,N0 dioctylhexyloxyethyl malonamide DMFT. See Dynamical mean-field theory DMHz. See 1,1-Dimethylhydrazine DMRB. See Dissimilatory metal-reduction bacteria DMSO. See Dimethyl sulfoxide DNA footprinting, photochemical oxidation for, 630–631 DNAA. See Delayed neutron activation analysis Dolomite, uranium in, 3160 DOR. See Direct oxide reduction DOS. See Density of states Double groups, for electronic structure calculations, 1910–1914 Double perovskites, solid state structures of, 1060t–1061t, 1062–1063, 1063f

Subject Index

I-41

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Dowex 1, for separation, 2636, 2636f Dowex 50 actinide elution with, 1624, 1625f for actinium purification, 30–31 for californium purification, 1508 for curium separation, 1433–1434 for fermium separation, 1624 for nobelium purification, 1639 for separation, 2636–2638, 2637f Dowex–1 anion-exchange column, protactinium separation on, 180, 180f DPP. See Differential pulse polarography DPV. See Differential pulse voltammetry DS method. See Dirac-Slater method DSBPP. See Di-S-butylphenyl phosphonate DS-DV method. See Dirac-Slater discretevariational method DTPA. See Diethylenetriamine pentaacetate DU. See Depleted uranium Dubna seaborgium production at, 1706–1707 transactinide element claims of LBNL v., 1659–1660 Dubnium chemical properties of, 1666, 1691t, 1703–1706 discovery of, 6t, 1653, 1653t electronic structures of, 1676–1682, 1677f–1678f, 1680t–1681t, 1682f gas-phase chemistry of, 1705–1706 history of, 1703 ionic radii of, 1674f, 1675–1676, 1676t ionization potential of, 1674, 1674f isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, in aqueous solution, 1774–1776, 1775t relativistic effects in, 1666–1667, 1667f relativistic orbital energies for, 1669f solution chemistry of, 1703–1705 complexation of, 1688–1689 hydrolysis, 1686–1687, 1687t oxidation states of, 1703–1704 redox potentials, 1685–1686, 1685f–1686f volatility of, 1664 Dubnium–258, chemical properties of, 1666 Dubnium–260 lawrencium–256 from, 1644 from meitnerium–268, 1717 Dubnium–261, study of, 1703 Dubnium–262, gas-phase chemistry of, 1705–1706 Dynamical mean-field theory (DMFT) plutonium magnetism with, 2355 SIM v., 2344 Dysprosium, californium v., 1545

ECF. See Extracellular fluid ECM. See Exchange charge model ECPs. See Effective core potentials EDL. See Electrodeless discharge lamp EDS. See Energy-dispersed X-ray spectroscopy EDTA. See Ethylenediaminetetraacetate EELS. See Electron energy loss spectroscopy Effective core potentials (ECPs), for scalarrelativistic methods, 1906–1907 Effective mass, of actinide metals, 2319–2322 Effective moment, for magnetic susceptibility data, 2230–2231 Effective-operator Hamiltonian, 2026–2030 corrective terms for, 2029–2030, 2055 crystal field parameters with, 2050 crystal field theory with, 2036–2037 expansion with CCF, 2054–2055 free-ion parameters in, 2071–2072, 2073f for penta- and hexavalent actinides, 2080–2081 use of, 2030 EHEH. See N,N-Ethyl (hydroethyl) hydroxylamine Eigen mechanism, in complexation, 2602–2603 Eigenfunctions of crystal field level, 2041–2042 free-ion, 2042 magnetic data for, 2226 magnetic susceptibility for, 2226 for N-electron ion, 2022 Eigen-Wilkins mechanism ligand substitution and, 608–610 organic and inorganic ligand formation and, 615–616 Einsteinium, 1577–1613 atomic and ionic radii, and promotion energies, 1612–1613 complete spectrum of, 1872–1873 compounds of, 1594–1612 crystal data, 1594–1600, 1596t oxychloride, 1595 sesquioxide, 1595–1599 solids other results of, 1602–1603 solids spectrometry of, 1600–1602, 1601f solutions related studies, 1605–1609, 1606t solutions spectrometry of, 1604–1605, 1604f trichloride, 1595 in vapor state, 1609–1612 discovery of, 5t, 9, 1577, 1761 in electrodeless lamps, 1885–1886, 1885f electronic properties and structure of, 1586–1588, 1587f, 1589t–1590t, 1864–1865, 1864f fermium separation from, 1624–1625

I-42

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Einsteinium (Contd.) half-life of, 1579 ionization potentials of, 1588, 1590f, 1874t isotopes of, 10, 1579, 1581t, 1582 lanthanide elements v., 2 metallic state of, 1588–1594, 1591t alloys of, 1592–1593 other actinide metals v., 1591–1592, 1591t production of, 1590, 1593–1594 properties of, 1590–1591, 1591t structure of, 2388 thermodynamic properties of, 1592–1593 nuclear properties, 1580–1583, 1581t oxidation states of, 2526 in aqueous solution, 1774–1776, 1775t production of, 1577–1578, 1580–1583 purification and isolation, 1583–1585 chromatographic methods for, 1583–1584 overview of, 1583 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f synthesis of, 9 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f Einsteinium (III) absorption spectra of, 1604–1605, 1604f hydration of, 2528–2530, 2529f, 2529t hydrolytic behavior of, 2546, 2548t interaction parameters of, 2062–2064, 2063t ionic radius of, 1613 magnetic properties of, 2271 in mammalian tissues circulation clearance of, 3368–3369, 3368f–3375f, 3371–3376 initial skeletal fractions of, 3349 reduction of, 1602 Einsteinium (I), atomic properties of, 1588, 1589t Einsteinium (VI), existence of, 1611 Einsteinium (II), magnetic properties of, 2271–2272 Einsteinium oxides, structure of, 2399, 2399t Einsteinium oxychloride, 1595, 1596t Einsteinium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Einsteinium sesquioxide, 1595–1599 bond dissociation of, 1611 electron diffraction pattern of, 1597, 1597f formation enthalpy of, 2143–2146, 2144t, 2145f

lanthanides v., 1613 production of, 1595–1597 properties of, 1596t, 1597–1598, 1599f self-irradiation and, 1598 structure of, 1598–1599, 2399, 2399t Einsteinium tetrafluoride, formation of, 1611–1612 Einsteinium tribromide, 1599 Einsteinium trichloride, 1595, 1596t Einsteinium trifluoride, tetrafluoride from, 1611–1612 Einsteinium trihalides, structural chemistry of, 2416, 2417t Einsteinium–253 atomic properties of, 1588, 1589t–1590t in borosilicate glass, 1601–1602, 1602f–1603f from californium–253, 1504 decay of, 1447 discovery of, 1580 half-life of, 1580 mendelevium–256 from, 1630–1631 production of, 1582–1583 in rutherfordium extraction, 1700 from rutherfordium–261, 1695 Einsteinium–254 production of, 1582–1583 thermochromatography of, 1611–1612 Einsteinium–255 discovery of, 1580 fermium–255 from, 1622 half-life of, 1580 production of, 1582–1583 Eisenstein-Pryce theory, optical transitions to, 2227t Ekanite, structural data for, 113 Elastic constants of plutonium, 942–943, 944t, 945f–946f role of, 943 Elastic recoil detection analysis (ERDA), for environmental actinides, 3059t, 3065 Eldorado mine, uraninite at, 274 Electrical conductivity, of uranium, oxides, 368–369 Electrical properties of plutonium hydrides, 3205 of uranium metal, 324, 324f, 324t Electrical resistivity of actinide metals, 2309, 2310f, 2324 of americium, 1298t, 1299 of Fermi liquid, 2340–2341, 2341f of plutonium, 954–957, 954f–956f, 2345–2347, 2346f δ-phase, 955–957, 955f–956f unalloyed, 954–955, 954f of UBe13, 2342, 2343f of uranium hydrides, 333 metallic state, 322

Subject Index

I-43

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Electrochemical methods for neptunium determination of, 790–792 electrolysis, 761–762 for protactinium, 227 gravimetric methods, 229–231 polarographic, 227 potentiometric and amperometric, 227 spectrophotometric methods, 227–228 Electrochemical separation, of uranium, 632–633 Electrode potentials of actinide ions, 2127–2131, 2130f–2131f of americium, 1328–1330, 1329t of einsteinium, 1606 of element 113, 1725 Electrodeless discharge lamp (EDL) for actinide spectroscopy, 1839 design and construction of, 1839, 1885–1886, 1885f Electrodeposition of neptunium, 717 in RTILs, 2690–2691 Electrolysis of actinium, 38 of neptunium, 761–762 of protactinium, 220 of thorium, 60–61 Electrolytes, plasma and urine concentrations of, 3356–3357, 3357t Electrolytic behavior, of neptunium, 755–759 coulometric behavior, 757–759, 758f voltammetric behavior, 755–757, 756t, 757f Electromagnetic separation, of plutonium isotopes, 821–822 Electrometallurgical technology (EMT) overview of, 2693 in pyroprocessing, 2694 Electron behavior in actinides, 1–2 parameters for, 2054 Electron diffraction techniques, for einsteinium, 1595–1598, 1597f Electron energy loss spectroscopy (EELS), for environmental actinides, 3049t, 3051–3052 Electron exchange reactions, of actinide complexes, 2597–2598 Electron microprobe analysis (EMPA), for environmental actinides, 3049t, 3050 Electron microscopy, for actinide element study, 14 Electron paramagnetic resonance (EPR) of 5f1 compounds, 2241 of 5f7 compounds, 2265 actinide ion measurements with, 2226 of americium

americium (IV), 2263 dioxide, 2292 of californium (III), 2269 of cyclopentadienyl complexes, trivalent, 2803 of einsteinium, 1602 einsteinium (II), 2272 for electronic structure, 1770 Kramers degeneracy and, 2228 of neptunium hexafluoride, 2243 tetrachloride, 2258t, 2261 neutron scattering v., 2232 non-Kramers degeneracy and, 2228 of organouranium (V) complexes, 2246 of plutonium (III), 2262–2263 of thorium dioxide, 2265 thorium (III), 2240 of uranium bis-cycloheptatrienyl, 2246 tris-cyclopentadienyl, 2259, 2259t uranium (III), 2259 Electron repulsion, spin-orbit coupling v., 1928–1929 Electron transfer rates, in cyclooctatetraenyl complexes, 2856 Electron-electron correlations in actinide metals, 2325–2326 Fermi surface in, 2334 Hartree term and, 2328 Electronic energies of berkelium, 1452–1453 of californium, 1513–1515, 1514t Electronic spectra. See also Absorption spectra of actinides, 1950–1951 of berkelium, 1475 of plutonium, ions, 1113–1114, 1115f of uranium dioxide, 1973 Electronic structures of actinide compounds, 1893–1998 actinyl ions and oxo complexes, 1914–1933 divalent, 2024, 2024t halide complexes, 1933–1942 matrix-isolated, 1967–1991 organometallics, 1942–1967 relativistic approaches, 1902–1914 speciated ions, 1991–1992 tetravalent, 2024, 2024t trivalent, 2024, 2024t unsupported metal-metal bonds, 1993–1994 of actinide elements, 1770–1773, 1842t–1850t, 1851–1860, 1851f, 1894–1897, 1896f–1897f, 1896t–1897t

I-44

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Electronic structures (Contd.) charge-transfer transitions and actinyl structures, 2085–2089 configuration, 1771–1773, 1772t, 1773f crystal-field interaction, 2036–2056 determination of, 1858–1860, 1860f divalent, 2077–2079 energies of, 1853–1858, 1854f, 1855t, 1856f, 1859f free-ion interactions, 2020–2036 general considerations, 1770 metallic state, 1788–1789, 1789f penta- and hexavalent, 2079–2085, 2080t periodic table position, 1773, 1774f redox potentials v., 1859–1860, 1860f relative energies, 2016–2020 relativistic approaches to, 1902–1914 spectroscopic studies, 1770–1771 structure, 1771–1773, 1772t, 1773f tetravalent, 2064–2076 theoretical term structure, 1860–1862 trivalent, 2056–2064 of actinide metals, 2318–2319, 2318f of actinocenes, 1946–1948 of americium, 1295 of berkelium, 1452–1453, 1461 berkelium (III), 1445 of curium curium (III), 1404–1405 curium (IV), 1404–1405 of cyclopentadienyl complexes pentavalent, 2847 trivalent, 2803 DFT for, 923–924 of dubnium, 1703 of einsteinium, 1586–1588 of element 113, 1722t, 1723–1725 of element 114, 1722t, 1725–1727 of element 115, 1722t, 1727–1728 of fullerenes, 2864–2865 of ion in condensed-phase medium, 2036–2037 Kramers degeneracy, 2228 of lawrencium, 1643 of mendelevium, 1633–1634, 1634t of 5f orbital, determination of, 2019–2020 of 6d orbital, determination of, 2020 of plutonium, 857, 921–935, 922–923, 923f, 1191–1203 alloy theory and modeling, 925–929, 926f α-phase, 923–924, 923f δ-phase, 923f, 925 hydrides and deuterides, 995, 995t ionic and covalent bonding models, 1191–1192 lattice effects and local structure, 930–935 novel interactions of, 921–922, 922f

plutonium dioxide, 1044, 1196–1199, 1197f, 1976 plutonium hexafluoride, 1194–1196, 1195f pnictides, 1023 radial probability densities, 1192, 1193f specific examples, 1192–1203 of thorium, 1869, 1870t carbide oxide, 1982, 1983t of transactinide elements calculation of, 1670 gas-phase compounds, 1676–1684, 1677f–1678f, 1680t–1681t, 1682f of tris(amidoamine) complexes, 2888 of uranium carbide oxide, 1977–1978, 1977t, 1982, 1983t metallic state, 2318–2319, 2318f uranium dioxide, 1973 uranyl ion, 1915 Electronic transition spectroscopy, for electronic structure, 1770–1771 Electronic transitions in actinocenes, 1949–1952 protactinocene, 1949–1951 thorocene and uranocene, 1951–1952 radiative and nonradiative, 2089–2103 5f–5f transitions, 2089–2093 fluorescence lifetimes, 2093–2095 ion-ion interaction and energy transfer, 2101–2103 nonradiative phonon relaxation, 2095–2100 Electronic transport, and magnetism, 2367–2368 Electron-nuclear double resonance (ENDOR) fluorine structure measurement by, 2243 of uranium bis-cycloheptatrienyl, 2246 Electroplating, for sample concentration, 3023–3024 Electrorecovery, of actinide elements, 2719–2721 Electrorefining (ER), 2712–2717 electro-transport in, 2714–2715 historical development of, 2712–2713 IFR and, 2713 reprocessing in, 2713–2714 for plutonium metal production, 870–872, 873f–875f equipment for, 871–872, 873f–874f process for, 870 product of, 872, 875f pyroredox after, 872–876 use of, 2692 separation efficiencies in, 2715–2717, 2718t Electrospray ionization mass spectroscopy (ESMS), for environmental actinides, 3049t, 3052–3055, 3054f

Subject Index

I-45

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Electrostatic concentration methods, for uranium ore, 303 Electrostatic integrals, of actinide elements, 1862–1863 divalent and 5þ valent, 2076 Electrothermal vaporization (ETV), for ICPMS, 3323 Element 112 chemical methods for, 1720–1721 chemical properties of, 1717–1721 discovery of, 1653–1654 electronic structures of, 1682–1684 isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, 1720 production of, 1719, 1720 relativistic orbital energies for, 1669f solution chemistry of complexation of, 1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f Element 113 chemical properties of, 1723–1725, 1724t electronic structure of, 1722t, 1723–1725 ionization potentials of, 1723, 1726t isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1659 production of, 1737 relativistic orbital energies for, 1669f Element 114 chemical properties of, 1724t, 1725–1727 electronic structure of, 1722t, 1725–1727 ionization potentials of, 1725, 1726t isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1659 oxidation states of, 1727 production of, 1738 relativistic orbital energies for, 1669f Element 114–287, discovery of, 1735 Element 114–288, discovery of, 1735 Element 114–289, discovery of, 1735–1736 Element 114–298, half-life of, 1736 Element 115 chemical properties of, 1724t, 1727–1728 electronic structure of, 1722t, 1727–1728 ionization potentials of, 1725f, 1726t, 1727 isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1659 oxidation states of, 1727–1728 relativistic orbital energies for, 1669f Element 116 chemical properties of, 1724t, 1728–1729 ionization potentials of, 1726t, 1728 isotopes of, 1657f–1658f

nuclear properties of, 1655t–1656t orbital filling in, 1659 oxidation states of, 1728 production of, 1737–1738 relativistic orbital energies for, 1669f Element 116–292, discovery of, 1736 Element 117 chemical properties of, 1724t, 1728–1729 ionization potentials of, 1726t, 1728 orbital filling in, 1659 oxidation states of, 1728 relativistic orbital energies for, 1669f Element 118 chemical properties of, 1724t, 1728–1729 ionization potentials of, 1726t, 1728–1729 orbital filling in, 1659 oxidation states of, 1729 relativistic orbital energies for, 1669f Element 118–293 decay of, 1737 production of, 1737 Element 119 chemical properties of, 1724t, 1729–1731 ionization potentials of, 1729, 1730f orbital filling in, 1659 Element 119–294, production of, 1737 Element 120 chemical properties of, 1724t, 1729–1731 ionization potentials of, 1729, 1730f orbital filling in, 1659 Element 120–295, production of, 1737 Element 121 breit effects on, 1669 chemical properties of, 1724t, 1729–1731 orbital filling in, 1659 Element 122 elements beyond, 1659, 1731–1734 orbital filling in, 1659 Element 164, chemical properties of, 1732 Element 165, properties of, 1732–1733 Element 166, properties of, 1732–1733 Element 171, properties of, 1733 Element 172, properties of, 1733 Element 184, properties of, 1733 El’kon District deposit, brannerite at, 280 Elution chromatography, in ion-exchange chromatography, 1289–1290 Embrittlement, of plutonium, 981 from radiogenic helium, 986 Emission spectrum of americium, 1296 of berkelium, 1453–1454, 1484 of californium, 1516 of plutonium, 857–859, 858f, 860t of protactinium, 190, 226 protactinium (IV), 2067–2068, 2068f EMPA. See Electron microprobe analysis EMT. See Electrometallurgical technology

I-46

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 ENAA. See Epithermal neutron activation analysis Endocytosis, actinide elements in liver and, 1816 ENDOR. See Electron-nuclear double resonance Energy bands in actinide metals, 2313–2317 energy levels in, 2316–2317 Energy-dispersed X-ray spectroscopy (EDS), for environmental actinides, 3049t, 3051–3052 Energy levels of 5f electrons, 2347, 2348f–2349f of 5f1 compounds, 2241, 2242f of actinide cyclopentadienyl complexes, 1954, 1955f of actinide ions in crystals, 2013, 2014t of actinium (III), 2058, 2059f of crystal fields, 2044, 2046t of curium (III), 2059–2061, 2266 deduction of, 2019 effective-operator Hamiltonian for, 2026–2027 in energy band, 2316–2317 of free-ions, 2042 condensed phase correlation and, 2037–2039, 2038t magnetic data for, 2226 in metallic state, 2308 of neptunium hexafluoride, 2083–2085, 2083t, 2085f neptunium (IV), 2067 of f orbitals, 2014–2016, 2015f 5f, 2019–2020 6d, 2020 Hamiltonian of, 2031–2032 of plutonium hexafluoride, 2083–2085, 2083t, 2085f of protactinium (IV), 2065–2066, 2066t of radiative relaxation, 2094–2095, 2094f for RIMS analysis, 3319, 3320f for tetra-, penta-, and hexavalent ions, 2081–2082, 2083t, 2084f of tetravalent actinide ions, 2070, 2072t, 2075–2076, 2075f of thorium carbide oxide, 1981, 1982f carbonyl, 1986, 1987f of trivalent actinide elements, 2032, 2033t, 2058–2061, 2058f–2060f of uranium carbide oxides, 1980f charge-transfer, 2086, 2087f hexafluoride, 1934–1935, 1934f, 1936t oxides, 1973, 1975f uranium (III), 2058, 2058f uranium (IV), 2066–2067, 2066t

Enthalpy. See also specific enthalpies of alkyne complexes oligomerization, 2627f, 2926–2929 of americium, 1328–1330, 1329t of berkelium, 1459–1460 of californium metal, 1523–1524, 1524f oxides, 1537 of curium dioxide, 1419 sesquioxide, 1419 of cyclopentadienyl complexes, tetravalent, 2821, 2822t–2823t of electron exchange reactions, 2597 of fermium, 1627–1628 of halides, 2578–2580, 2579t, 2581t of lawrencium, 1644 of mendelevium, 1634–1636 of metal-ligand bonds, 2912–2913 of plutonium oxides with uranium oxides, 1076 tribromide, 1100 Enthalpy of formation. See Formation enthalpy Entropy of actinide elements, 2115–2116, 2116f, 2539, 2542f, 2543t of actinide ions, 2125–2127 of actinide oxides with alkali metals, 2151, 2152t with alkaline earth metals, 2155t, 2156–2157 of americium, 1298t, 1299 of californium, 1527 of carbides, 2196, 2197t of curium, 1411 of dihalides, 2179, 2180t–2181t of dioxides, 2137–2138 of electron exchange reactions, 2597 of halides, 2578–2580, 2579t, 2581t of hexahalides, 2159–2160, 2160t, 2164t of hydrides, 2188, 2189t of mendelevium, 1635 of monohalides, 2179, 2180t–2181t of nitrides, 2197t, 2201–2202 of oxyhalides, 2182, 2183t–2184t, 2186t–2187t of pentahalides, 2160t, 2161, 2164, 2164t of sesquioxides, 2146, 2146f of tetrahalides, 2166t, 2167, 2168f of thorium, 119, 119t of transition metal compounds, 2206t, 2210–2211 of trihalides, 2170t, 2176 tribromides, 2172f, 2174t, 2176 trichlorides, 2172f, 2173t, 2176 trifluorides, 2171t, 2172f, 2176 triiodides, 2172f, 2175t, 2176

Subject Index

I-47

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 of trihydroxides, 2191, 2191t Environment actinide species in, 3013–3014, 3015f analytical techniques for, 3018–3020, 3019t anthropogenic, 3016 dispersal of, 3016–3017 humic and fulvic acids with, 3139–3140 mining, 3017 natural occurrence, 3014–3016, 3015f separation of, 3021 depleted uranium in, 3173–3174 identification and speciation in, 3013–3073 background, 3013–3021 combining and comparing analytical techniques, 3065–3071 electron-photon, -electron, -ion techniques, 3047–3055 ion-photon, -electron, -neutron, -ion techniques, 3058–3065 neutron-photon, -electron, -neutron, -ion techniques, 3055–3057 passive techniques, 3025–3033 photon-phonon, -electron, -neutron, -ion techniques, 3043–3047 photon-photon techniques, 3033–3043 specifics of, 3024–3065 sampling, handling, treatment, and separation in, 3021–3024 issues with, 3021 sample and data collection in, 3021–3022 treatment and separation of, 3022–3024 trace analysis in, 3273–3330 atomic spectrometric techniques, 3307–3309 chemical procedures, 3278–3288 mass spectrometric techniques, 3309–3328 nuclear techniques, 3288–3307 Environmental aspects, of actinide elements, 1803–1813, 2769 in hydrosphere, 1807–1810 man-made, 1805–1807 of natural origin, 1804–1805 nuclear waste disposal, 1811–1813 overview of, 1803 separation techniques for, 2725–2727 sorption and mobility, 1810–1811 Environmental problems actinide chemistry for, 3 of neptunium, 782–783, 786 of nuclear power, 1826 transuranium elements released, 1807, 1808t, 3095 of uranium, 270 Environmental sample collection of, 3021–3022

issues with, 3021 sorption studies on, 3140–3183 bacterial interactions, 3177–3183 carbonate incorporation, 3159–3164 iron-bearing mineral phases, 3164–3169 natural soil samples, 3171–3177 overview of, 3140, 3151 phosphates, 3169–3171 silicates, 3151–3158 synchrotron XAS for, 3086–3087, 3095–3140 acid redox speciation, 3100–3124 base redox speciation, 3124–3137 organic acids, 3137–3140 overview, 3095–3100 treatment and separation of, 3022–3024 coprecipitation, 3023 dialysis of, 3023 electroplating, 3023–3024 gel electrophoresis, 3024 liquid-liquid partitioning, 3024 liquid-solid partitioning, 3024 Epidote, thorium in, 56t Epithermal neutron activation analysis (ENAA), description of, 3303 EPR. See Electron paramagnetic resonance e-Phase, of plutonium, 882f–883f, 883 density of, 936t diffusion rate, 958–960, 959t strength of, 968f, 970 thermal expansion, 938t, 939 thermoelectric power, 957–958, 958t Equilibrium constants of neptunium inorganic ligands, 771, 772t–775t, 781 organic ligands, 776t–780t, 781–782 of plutonium, 1158 hexafluoride, 1088–1090, 1091f of protactinium (V), 211, 211t of uranium hydroxide complexes, 598, 599t inorganic ligand complexes, 601t, 602 organic ligand complexes, 603–605, 604t ternary complexes, 605–606, 606t uranium (III), 598, 601t, 604t ER. See Electrorefining ERDA. See Elastic recoil detection analysis Erythrocytes, actinide association with, 3366–3367 ESMS. See Electrospray ionization mass spectroscopy Ethereal sludge, protactinium enrichment from, 176–178, 177f N,N-Ethyl (hydroethyl)hydroxylamine (EHEH), neptunium (VI) reduction with, 760–761 Ethylene sulfide, cyclopentadienyl complex oxidation by, 2814

I-48

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Ethylenediaminetetraacetate (EDTA) actinide element complexes with, 1783–1784 in bone binding study, 3407–3409 californium separation with, 1509 as chelating agent, 3413 complexes of, 2587, 2588f, 2589t stability constants, 2257f, 2556 curium separation with, 1409 neptunium extraction with, 708 plutonium complex with, 1176–1179, 1178t, 1181 for removal, 1823 separation with, 2639–2640, 2641t of thorium, as ligands, 131 with uranium, 603–605, 604t 2-Ethylhexylphenylphosphonic acid (HEMΦP), einsteinium extraction with, 1585 ETV. See Electrothermal vaporization Europium in einsteinium alloy, 1592 einsteinium v., 1578–1579 extraction of from americium, 2676–2677, 2677t TALSPEAK for, 2672 UO2 solid solutions with, oxygen potentials of, 395t, 396 Europium (III) extraction of, 1274 americium (III), 1283, 1287–1289, 2665–2666, 2667t separation factors for, 2669–2670, 2670t hydration numbers of, 2534, 2535t in concentrated solutions, 2536–2538, 2537f separation factors for, 2669–2670, 2670t XANES of, 3087, 3088f Europium (II), XANES of, 3087, 3088f EXAFS. See Extended X-ray absorption fine structure analysis Exchange charge model (ECM) calculation of, 2053, 2053t with crystal-field Hamiltonian, 2052–2053 Excitation schemes, of actinide elements, 1876–1877, 1877t, 1878f Excitation spectra of curium (III), 2061–2062, 2061f of curium (IV), 2068, 2071f Extended X-ray absorption fine structure analysis (EXAFS) for acid redox speciation, 3100–3103 of actinyl complexes, 1921 hydroxides, 1925 water, 1923 of americium (III), 3115 of californium (III), 3110, 3115 for coordination number analysis, 586, 588, 602, 3087–3088

of curium (III), 3110 FT data with, 3090–3091, 3092f of iron-bearing phases, 3165–3167 LAXS v., 589 of neptunium (III), 3116–3117 of neptunium (IV), 3106–3107, 3135–3136 carboxylates, 3137–3140, 3147t–3150t of neptunium (VII/VI), 3124–3125 of neptunyl (V), 3133–3134 for obtaining structural information, 589 organic acid analyses with, 3137–3140 model systems, 3138–3139 natural systems, 3139–3140 of plutonium dioxide, 1041–1042, 1043f plutonium (III), 3117–3118 plutonium (IV), 3108–3109, 3136 plutonium (VII/VI), 3126 of plutonyl plutonyl (V), 3210 plutonyl (VI), 3134 plutonyl (VI/V), 3123–3124 problems with, coordination numbers, 3103 of tetravalent ions, 3134–3135 of thorium (IV), 3104–3105, 3129, 3136–3137 carboxylates, 3137–3140, 3147t–3150t of thorium, silicate adsorption, 3152–3154 of uranium in carbonates, 3160–3161, 3161t silicate adsorption, 3154–3155 silicate phosphate, 3170 uranium (III), 3116 of uranium (IV), 3105–3106, 3136 in silicate glass and, 276 of uranyl (V), 3122 of uranyl (VI), 3118–3123, 3126–3129, 3131–3133 carboxylates, 3137–3140, 3141t–3150t use of, 3090–3091 of XAS, 3087, 3088f Extracellular fluid (ECF) circulation of, 3357–3359 clearance from of mice, 3388–3395, 3389f–3392f, 3394t of rats, 3387–3388 Extraction chromatography for americium purification, 1293–1295 for berkelium extraction, 1449 for californium separation, 1509 for curium purification, 1434 for einsteinium extraction, 1585 n-Octyl(phenyl)-N,N-diisobutyl-carbamoyl methylphosphine oxide for, 2748–2749 overview of, 844–845, 1293 plutonium extraction with, 844–845 protactinium purification with, 181–186, 183f

Subject Index

I-49

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 resins for, 3284–3285 of rutherfordium, 1692 for trace analysis, 3284–3285, 3286f use of, 845 Extractive metallurgy, of uranium, 303 FA. See Fulvic acid FAAS. See Flame source atomic absorption spectrometry Fast breeder reactors (FBR), plutonium and uranium oxides for, 1070 FBR. See Fast breeder reactors 0 5f Compounds magnetic properties of, 2239–2240 magnetic susceptibilities of, 2240f 5f1 Compounds energy levels of, 2241, 2242f EPR of, 2241 magnetic properties of, 2240–2247 oxides, 2244, 2245t magnetic susceptibility of, 2241 optical data for, 2227t 5f2 Compounds magnetic interactions on, 2228, 2229f magnetic properties of, 2247–2257, 2255t 6 5f Compounds magnetic properties of, 2263–2265, 2264t TIP of, 2263–2264 5f7 Compounds magnetic properties of, 2265–2268, 2266t–2267t magnetic susceptibility of, 2266, 2267t, 2268 5f3 Compounds, magnetic properties of, 2257–2261, 2258t–2260t 5f4 Compounds, magnetic properties of, 2261–2262 5f5 Compounds, magnetic properties of, 2262–2263, 2263t 5f8 Compounds, magnetic properties of, 2268–2269, 2270t 5f9 Compounds, magnetic properties of, 2269–2271, 2270t 5f10 Compounds, magnetic properties of, 2271 5f11 Compounds, magnetic properties of, 2271–2272 f-d promotion energies of actinides, 1560, 1561f, 1586–1588, 1587f, 1609–1610, 1609f–1610f, 1859–1860, 1860f of tetravalent ions, 2065 FEFF role of, 3091–3092 for XAS, 3089 5f-Electron. See 5f Orbital Fermi energy of actinide metals, 2319–2322

electronic heat capacity with, 2323 in free-electron model, 2320–2321 Fermi liquid, 2339–2441 electrical resistivity of, 2340–2341, 2341f plutonium as, 2345–2347 Fermi surface in actinide metals, 2322–2323 description of, 2322 in electron-electron correlations, 2334 in Luttinger theorem, 2334 in magnetism, 2367 topology of, 2322–2323 UIr3 measurements of, 2334 Fermi-Dirac distribution function with DOS, 2320 Pauli exclusion principle with, 2323 Fermium, 1622–1630 atomic properties of, 1626, 1627t chemical properties of, 1628–1630, 1646t discovery of, 5t, 9, 1622, 1761 einsteinium separation from, 1585 ionization potential of, 1877 isotopes of, 10, 1622–1624, 1623t lanthanide elements v., 2 mendelevium separation from, 1632–1633 metallic state of, 1626–1628 nobelium v., 1640 oxidation states of, 2526 in aqueous solution, 1774–1776, 1775t preparation and purification of, 1624–1625, 1625f reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f solution chemistry, 1628–1630 synthesis of, 9, 1622 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t Fermium (III) hydration of, 2528–2530, 2529f, 2529t hydrolytic behavior of, 2546, 2548t Fermium–251, X-rays emitted by, 1626 Fermium–253, in rutherfordium extraction, 1700 Fermium–255 availability of, 1624 from einsteinium–255, 1582 production of, 1622 Fermium–257 availability of, 1624 production of, 1582, 1623–1624 Ferrihydrate, uranium (VI) adsorption on, 3166–3167 Ferritin, in liver, 3397 Ferrocene, history of, 1952

I-50

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 FES. See Flame emission spectrometry f-f transitions of actinyl ions, 1930 of divalent ions, 2078, 2079f intensity of, 2089–2093 Judd-Ofelt theory for, 2093 of tetravalent ions, 2065, 2067 of uranyl, 2088–2089 FI. See Flow injection Filtration for actinide speciation, 3069 for oxidation state speciation, 2726 Fission process history of, 3–4, 2628 of plutonium, 815 plutonium–239, 820 products of, 826, 827t–828t, 828 of uranium, 1804–1805 Fission track analysis (FTA) applications of, 3307 description of, 3303 Flame emission spectrometry (FES), overview of, 3307–3308 Flame source atomic absorption spectrometry (FAAS), of uranium, 636 Floating zone technique, for uranium oxide preparation, 343 Flocculants, for uranium ore processing, 309 Flotation concentration methods, for uranium ore, 303–304 Flow coulometry, for neptunium, 757–759, 758f Flow injection (FI), for separation, 3281 Fluorescence of actinide elements, history of, 1894 of americium (III), 1368–1369 of berkelium, 1454 intensity of, 626 lifetimes of, 2093–2095 overview of, 625, 625f phosphorescence v., 625 quenching of, 625 of uranyl, 2087–2088, 2088f uranyl (VI), 624–630 Fluorescence spectroscopy of curium, 1405–1406, 1406f, 1433 laser-induced, 628–629 of neptunium, 786–787 photochemical studies and, 627 Fluorescence spectrum, of uranium, uranium oxobromo complexes, 573 FLUOREX, for plutonium separation, 856–857 Fluorides of actinide elements, 1796 free-ion and crystal-field interactions of, 2071, 2073f of berkelium, 1457, 1467–1469

of californium, 1529, 1532, 1546 complexes of, 2578 of curium, 1413t–1415t, 1417–1418, 1429 of dubnium, 1705 of mendelevium, 1635 of neptunium, 730–736 equilibrium constants for, 772t hexafluoride, 732–734 pentafluoride, 731–732 tetrafluoride, 730–731 trifluoride, 730 optical spectroscopic data of, 2069–2070, 2069f–2070f precipitation with, 2633–2634 plutonium, 836, 838 of protactinium (V), 213–215, 216f, 217t protactinium derivatives of, 197–199, 198f, 207 alkali, 200–203, 202t in pyrochemical methods, 2700–2701 of rutherfordium, extraction of, 1699–1700 of seaborgium, 1710–1711 with thorium carbonates, 109 as thorium ligand, 129 of uranium, 444–446, 484–489, 518–521, 557–564 fluoro complexes, 445–446, 487–489, 520–521, 520t, 563–564, 564t hexafluoride, 557–563 hexavalent oxide fluoride complexes, 566–567 oxide difluoride, 565–566 oxide tetrafluoride, 564–565 oxides and nitrides of, 489–490 pentafluoride, 518–520 pentavalent oxide fluorides and complexes, 521 polynuclear, 579 tetrafluoride, 484–486 tetrafluoride hydrates, 486–487 trifluoride, 444–445 trifluoride monohydrate, 445–446 Fluorination of dubnium, 1705 of einsteinium, 1611 of plutonium, 1080–1082, 1081f for plutonium metal production, 866, 867f of rutherfordium, 1699–1700 of seaborgium, 1710–1711 of uranium, 315–317, 316f, 317t by uranium hexafluoride, 561 Fluorination reactors, for plutonium fluorination, 1080–1081, 1081f Fluorometry applications of, 3308 fundamentals of, 3308 of uranium, 636–637

Subject Index

I-51

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Fluoroplutonate compounds preparation of, 1103–1104 properties of, 1104, 1105t–1107t Fluxed fusion decomposition, of uranium, 631–632 FOD. See 6,6,7,7,8,8,8-Heptafluoro–2,2dimethyl–3,5-octanedione Foil for lawrencium capture, 1643 for mendelevium capture, 1632–1633 for nobelium capture, 1638–1639 for one-atom-at-a-time chemistry, 1663 Foldy-Wouthuysen transformation, for electronic structure calculation, 1906 Formates of americium, 1322, 1323t of neptunyl, 2257 structural chemistry of, 2437–2440, 2439t–2440t of thorium, 114 synthesis of, 114 Formation constants for americium, 1338, 1339t americium (III), 1273 for plutonium, 1158, 1160t–1161t Formation enthalpy. See also Complexation enthalpy of actinide ions, 2123–2125, 2124f–2125f, 2539, 2541t of actinide oxides with alkali metals, 2151 with alkaline earth metals, 2153–2156, 2154f, 2155t, 2156f of carbides, 2195–2196, 2197t of dihalides, 2179, 2180t–2181t of dioxides, 2136–2137, 2137t, 2138f of hexahalides, 2159–2160, 2160t, 2164t of hydrides, 2187–2188, 2187t, 2189t, 2190f of hydroxides, 2193–2195, 2194t between Lewis acid and Lewis base, 2576–2577 of monohalides, 2179, 2180t–2181t of nitrides, 2197t, 2200–2201, 2201f of oxyhalides, 2182, 2183t–2184t, 2186t–2187t of pentahalides, 2160t, 2161, 2164t of plutonium oxides, 1971 of sesquioxides, 2143–2146, 2144t, 2145f of tetrahalides, 2165–2167, 2166t, 2168f of transition metal compounds, 2206t, 2208–2210, 2210f of trihalides, 2169–2172, 2170t tribromides, 2169–2172, 2172f, 2174t trichlorides, 2169–2172, 2172f, 2173t trifluorides, 2169–2172, 2171t, 2172f triiodides, 2169–2172, 2172f, 2175t of trihydroxides, 2190–2191, 2191t

Fourier transform ion resonance mass spectrometry (FTIRMS), of californium, 1560 Fourier transform spectrometers (FTS), actinide element infrared spectra with, 1840 Fourier transform spectrum (FT) of berkelium, 1474 EXAFS with, 3088, 3090–3091, 3092f of plutonium, 858, 858f Fourmarierite anion topology of, 282–283, 284f–285f at Oklo, Gabon, 271–272 at Shinkolobwe deposit, 273 uranium in, 259t–269t Fractional crystallization, for actinium and lanthanum separation, 18 Francium–223, from actinium–227, 20 Franc¸oisite at Oklo, Gabon, 271–272 uranium in, 259t–269t Free-electron model band structure with, 2324 Fermi energy in, 2320–2321, 2323 Free-ion Hamiltonian adjustment of, 2054 correction terms on, 2076 Coulomb interaction of, 2055 crystal field theory with, 2036–2037 crystal-field Hamiltonian with, 2041, 2054 matrix of, 2031 parameterization of, 2031–2036 parameters of, 2054–2055 of trivalent ions, 2056 Free-ion interactions of actinide fluorides, 2071, 2073f condensed-phase v., 2037–2039, 2038t crystal-field interactions with, 2044, 2062–2064, 2063t of f orbital, 2024, 2025t–2026t HF calculations of, 2022–2023, 2050 modeling of, 2020–2036 central field approximation, 2020–2023 effective-operator Hamiltonian, 2026–2030 LS coupling and intermediate coupling, 2023–2026 parameterization of free-ion Hamiltonian, 2031–2036 reduced matrices and free-ion state representation, 2030–2031 Free-ion parameters of actinide elements, 2038–2039, 2038t computation of, 2058 crystal field parameters and, 2050 tetravalent ions, 2074 in effective-operator Hamiltonian, 2071–2072, 2073f

I-52

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 FTA. See Fission track analysis FTIRMS. See Fourier transform ion resonance mass spectrometry FTS. See Fourier transform spectrometers Fullerenes, 2864–2865 electronic structure of, 2864–2865 overview of, 2864 Fulvic acid (FA) americium (III) complexation with, 1353–1354 complexes of, 2590–2591 environmental actinides and, 3139–3140 for thorium complexation, 132–133 Fusion decomposition, 3278–3279 description of, 3278–3279 disadvantage of, 3279 Gadolinium (III), energy levels of, 2075–2076, 2075f Gadolinium, UO2 solid solutions with, oxygen potentials of, 395t, 396, 397f Gallium in plutonium alloy, 892–894, 893f–896f δ-phase lattice, 930f, 932–933 δ-phase self-irradation damage, 986–987, 987f elastic constants, 942–943, 944t, 946f electrical resistivity, 955–957, 955f–956f hardness of, 971–972, 971f–972f heat capacity, 947–948, 950t–951t magnetic susceptibility, 949, 953–954, 953f microsegregation, 899, 916–917, 916f–917f solubility ranges, 930, 930f thermal conductivity, 957 thermal expansion, 937–942, 940f–941f transformations in, 917–919, 918f thermodynamic properties of actinide compounds with, 2205–2206, 2206t–2207t γ-Phase of plutonium, 882, 882f–883f density of, 936t diffusion rate, 958–960, 959t strength of, 968f, 970 thermal expansion, 938t thermoelectric power, 957–958, 958t of uranium β transformation of, 347 general properties of, 321–323, 322t–323t physical properties of, 321 Gamma radiation, from berkelium–249, 1447 Gamma source, americium as, 1267 Gamma-ray spectroscopy (γS) of actinium actinium–227, 23–24, 26f

actinium–228, 24–25 detector for, 3299–3300 advantages of, 3329 of americium, 1364 applications of, 3300–3302 for environmental actinides, 3025–3028, 3026t, 3028f fundamentals of, 3297–3300, 3299f of neptunium, 783–785 neptunium–237, 784–785 overview of, 3296–3297, 3299f of protactinium protactinium–231, 166, 168f, 224–225 protactinium–233, 225–226 protactinium–234, 170, 171f of thorium, 133–134 for trace analysis, 3296–3302 tracers for, 3297, 3298t Gas adsorption chromatography, for lawrencium, 1643 Gas transport systems, for transactinide element chemical studies, 1663 Gas-jet method of mendelevium production, 1632 of nobelium production, 1638–1639 Gas-phase of californium, 1559–1561 of dubnium, 1705–1706 of einsteinium, 1586–1588, 1609–1610 with laser ablation technique, 1612 of rutherfordium, 1693, 1694f of seaborgium, 1707–1709 of superactinide elements, 1734 thermodynamic properties in, 2118–2123, 2119t–2120t of actinide compounds, 2147–2150, 2148t, 2150f of halides, 2160–2161, 2164–2165, 2169, 2177–2179 of transactinide compounds, 1676–1685 electronic structures, 1676–1684, 1677f–1678f, 1680t–1681t, 1682f volatility predictions, 1684–1685 for transactinide elements, 1663–1665 measured v. predicted, 1715, 1716t GDMS. See Glow discharge mass spectrometer Gel electrophoresis, of environmental sample, 3024 General Purpose Heat Source-Radioisotope Thermoelectric Generators (GPHSRTGs) pellet-formation for, 1032–1033 plutonium–238 in, 818–819, 819f Generalized gradient approximations (GGA), for HF calculations, 1904 Generalized least-squares (GLS), for actinides, 1865

Subject Index

I-53

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Geochemical tracer, actinium–227 as, 44 Geological matrices, trace analysis in, 3273–3330 atomic spectrometric techniques, 3307–3309 chemical procedures, 3278–3288 mass spectrometric techniques, 3309–3328 nuclear techniques, 3288–3307 Geometries, of uranyl polyhedra, 281–282, 284f–286f Germanates, of thorium, 113 Germanium thermodynamic properties of actinide compounds with, 2206–2208, 2206t–2207t uranium compounds with, 407 Gesellschaft fu¨r Schwerionenforschung (GSL), darmstadtium discovery at, 1653 GFAAS. See Graphite furnace source atomic absorption spectrometry GGA. See Generalized gradient approximations Gibbs energy of actinide cation correlations, 2568–2570, 2568f–2569f, 2572–2574 chemical reaction and, 3202 of complexation, 2577 of halides, 2578–2580, 2579t, 2581t of electron exchange reactions, 2597 of formation, 2539, 2540t for chlorides, 2710t of hydration, 2539, 2540t of thorium, 119, 119t of reactions, of oxyhalides, 2182 of transfer, for americium and curium, 2098 Globulins, actinide distribution with, 3362–3363 Gloved boxes, for actinide element study, 11–12, 11f Glow discharge mass spectrometer (GDMS), for mass spectrometry, 3310 GLS. See Generalized least-squares Glycine, of uranium, 603–605, 604t Glycolate coordination with, acetate v., 590 of uranium, 603–605, 604t Glycolates, structural chemistry of, 2439t–2440t Glycoproteins actinide bone binding by, 3410–3411 in plutonium fixation, 1817 Gold foil berkelium separation from, 1450 mendelevium capture on, 1632 GPHS-RTGs. See General Purpose Heat Source-Radioisotope Thermoelectric Generators

Graphite furnace source atomic absorption spectrometry (GFAAS), of uranium, 636 GRAV. See Gravimetry Gravimetric methods for protactinium, 229–231 cupferronate, 230–231 hydroxide, 229 iodate, 230 peroxide, 230 phenylarsonate, 229–230 for uranium, 634–635 Gravimetry (GRAV), for environmental actinides, 3026t, 3029 Gravitational concentration methods, for uranium ore, 303 Ground crystal field state, Zeeman interaction and, 2225–2226 Ground state configuration of actinide elements, 1895, 1897t, 2016–2018, 2018f cyclopentadienyl complexes, 1955 three-electron configurations, 2018–2019, 2018f of actinide metals, 2328 of actinocenes, 1946–1948 of actinyl, 1929–1930, 1930t of cerocene, 1947 DFT calculation of, 1671 of element 184, 1722t, 1733 of heavy fermions, 2342 of neptunocene, 1946 of neptunyl, 1931 of 5f orbital, 2042 of plutonium, 924 compounds, 2345–2347 dioxide, 2288 of plutonyl, 1931 of protactinium, 190 of protactinocene, 1946 scalar-relativistic methods for, 1900 of superactinide elements, 1722, 1722t, 1731 of thorium carbonyl, 1986, 1988f thorium (III), 2240–2241 of thorocene, 1947 of transactinide elements, 1722, 1722t, 1895, 1897t of uranium carbide oxide, 1978–1979, 1979f dioxide, 1972–1973, 2279 hexavalent and complex halides, 557 of uranyl, 1972, 2086–2087, 2087f Group 14 ligands in actinide chemistry, 2894 cyclopentadienyl complex derivatives of, 2820–2821

I-54

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Group IIA elements, thermodynamic properties of, 2205, 2206t–2207t Group IIIA elements, thermodynamic properties of, 2205–2206, 2206t–2207t, 2208f Group IVA elements, thermodynamic properties of, 2206–2208, 2206t–2207t γS. See Gamma-ray spectroscopy GSL. See Gesellschaft fu¨r Schwerionenforschung Guilleminite, as uranyl selenite, 298 HA. See Humic acid Hafnium dubnium v., 1703 extraction with TTA, 1701 rutherfordium v., 1692–1693, 1694f, 1702 extraction of, 1696–1700 studies of, 1696 Hafnium–169, rutherfordium–261 study with, 1696 Half-life of actinide isotopes, 1764t of actinium actinium–227, 20 actinium–228, 24 of americium, 1265–1267, 1266t of berkelium, 1445–1447, 1446t of californium, 1503–1504 of curium, 1399t, 1400 curium–244, 1759 of darmstadtium, 1719 of einsteinium, 1579 einsteinium–253, 1580 einsteinium–255, 1580 of lawrencium, 1642, 1642t lawrencium–260, 1645 of meitnerium–271, 1718 of mendelevium, 1630–1631, 1631t of nobelium, 1637, 1638t of plutonium, 815 isotopes, 822–823 plutonium–24, 822–823 plutonium–238, 815, 817 plutonium–239, 820, 822–823 of protactinium, 162–163 protactinium–231, 166, 170 protactinium–233, 169 protactinium–233 (IV), 221 protactinium–234, 186 of roentgenium, 1719 of superactinide isotopes, 1735–1737 of transactinide isotopes, 1661 Halide slagging, 2709–2710 description of, 2709, 2710t results of, 2709–2710

Halide volatility processes overview of, 855 for plutonium separation, 855 Halides of actinide elements, 1790, 1791t–1795t, 1933–1942 oxyhalides, 1939–1942 uranium hexafluoride and related complexes, 1933–1939 of americium, 1305t–1312t, 1314–1316 coordination of, 1356–1357, 1358f overview of, 1315–1316 preparation of, 1314–1315 of berkelium, 1464t–1465t, 1467–1470 berkelium (III), 1464t–1465t, 1468–1470 berkelium (IV), 1464t–1465t, 1467–1468 of californium, 1529–1534, 1530t–1531t, 1532f complexes of, 2578–2580, 2579t, 2581t of curium, 1413t–1415t, 1417–1418 high-temperature properties of, 2162t–2163t of neptunium, 730–739 preparation of, 730–739 structures of, 731t of plutonium, 1077–1108 chlorides, bromides, and iodides, 1092–1100 fluorides, 1077–1092 oxyhalides of, 1100–1102 as sigma-bonded ligands, 1182–1184 stability of, 1077 ternary halogenoplutonates, 1102–1108 of protactinium, 197–204, 201t alkali, 200–203, 202t preparation of, 197–199, 198f–199f properties of, 199–200 structural chemistry of, 2414–2421, 2417t–2418t, 2419f, 2420t–2421t bonding in, 2415 dihalides, 2415–2416 hexahalides, 2419, 2421, 2421t overview of, 2414–2415 pentahalides, 2416, 2419, 2419f, 2420t tetrahalides, 2416, 2418t trihalides, 2416, 2417t thermodynamic properties of, 2157–2179 complex, 2179–2182, 2183t–2184t, 2185f di- and monohalides, 2178–2179, 2180t–2181t, 2181f hexahalides, 2159–2161 pentahalides, 2161–2165 tetrahalides, 2165–2169 trihalides, 2169–2178 of thorium, 78–94 binary, 78–84, 78t crystallographic data of, 87t–89t fluoride, 78–80, 78t, 79f

Subject Index

I-55

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 nitride reaction with, 98–99 phases of, 84–86, 85f, 86t polynary, 84–94 tetrabromide, 81–82, 81f tetrachloride, 78t, 80–81, 81f tetraiodide, 78t, 82–84, 83f of uranium, 420–575. See also Uranium halides applications of, 420 chemistry of, 421 oxidation states in, 420–421 tervalent and complex, 421–456 Hamiltonian. See also Pauli Hamiltonian crystal-field ECM with, 2052–2053 free-ion Hamiltonian with, 2041 initial parameters of, 2048 matrix element evaluation with, 2039–2042 symmetry rules for, 2043 effective-operator, 2026–2030 corrective terms for, 2029–2030 use of, 2030 free-ion crystal-field Hamiltonian with, 2041, 2054 matrix of, 2031 parameterization of, 2031–2036 for N-electron ion, 2021 for spin-orbit coupling, 2028 Handling atmosphere for, 3259–3260 hazard assessment, 3248–3259 case studies, 3256–3259 chemical property uncertainty, 3255 metal incidents, 3256–3257 nuclear criticality, 3255–3256 nuclear material release and dispersal, 3252–3255 oxide incidents, 3257–3258 potential hazards, 3248–3256 residue incidents, 3258–3259 thermal hazards, 3251–3252 hazard mitigation, 3259–3262 atmosphere for, 3259–3260 conditions for, 3260–3262 of plutonium, 3199–3266 alloys, 3213 hydrides, 3204–3206 metals, 3223–3238 other compounds, 3212–3213 oxides, 3206–3212 reaction kinetics, 3215–3223 scope of concerns, 3201–3202 radiolytic reactions, 3246–3248 of uranium, 3199–3266 compounds, 3213–3215 scope of concerns, 3201–3202

Hartree-Fock (HF) calculations of actinide elements, 1852 with central field approximations, 2020–2023 of crystal-field interactions, 2050–2051 developments of, 1904 of electronic structure calculation, 1900, 1902–1904 of f electrons, 2032, 2034f, 2035 of free-ion interactions, 2022–2023, 2050 of free-ion parameters, 2039 hybrid approach to, 1904 one-electron band structures from, 2325 of plutonium, 1857–1858, 1857f of trivalent ions, 2056 of uranium hexafluoride, 1935–1937, 1936t of uranyl, 1920 Hartree-Fock-Slater (HFS) approach, 1903 Hartree-Fock-Wigner-Seitz band calculation of berkelium metal, 1461 of californium, 1513, 1514t of lawrencium, 1643 of nobelium, 1640 Hassium chemical properties of, 1712–1715, 1715f chemical studies of, 1664 discovery of, 6t, 1653, 1653t, 1762 electronic structures of, 1676–1682, 1677f–1678f, 1680t–1681t, 1682f ionic radii of, 1674f, 1675–1676, 1676t ionization potential of, 1674, 1674f isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, in aqueous solution, 1774–1776, 1775t production of, 1662, 1713 relativistic orbital energies for, 1669f solution chemistry of complexation of, 1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f Hassium–269 decay chains of, 1714 discovery of, 1735 production of, 1713 Hassium–270 decay chains of, 1714 discovery of, 1735 production of, 1713 Hausmannite, plutonium (VI) reactions with, 3176–3177 HAW. See High-level aqueous raffinate waste Hazards assessment of, 3248–3259 case studies, 3256–3259 chemical property uncertainty, 3255 metal incidents, 3256–3257

I-56

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Hazards (Contd.) nuclear criticality, 3255–3256 nuclear material release and dispersal, 3252–3255 oxide incidents, 3257–3258 potential hazards, 3248–3256 residue incidents, 3258–3259 thermal hazards, 3251–3252 mitigation of, 3259–3262 atmosphere for, 3259–3260 conditions for, 3260–3262 of plutonium, 3200 alloys, 3213 corrosion, 3204 hydrides, 3204–3206 hydroxides, 3213 metals, 3223–3238 nitrides, 3212–3213 oligomerized, 3210–3211 other compounds, 3212–3213 oxides, 3206–3212, 3219–3222 reaction kinetics of, 3215–3223 surface chemistry, 3209–3210 radiolytic reactions, 3246–3248 rate-controlling factors and mechanisms in, 3202–3204 scope of concerns, 3201–3202 storage for, 3199 of uranium, 3200 compounds, 3213–3215 HDBP. See Dibutylphosphoric acid HDEHP. See Bis(2-ethylhexyl)phosphoric acid HDNNS. See Dinonylnapthalene sulfonic acid Heap leaching, of uranium ore, 306 Heat capacity of actinide elements, 2116–2118, 2117t, 2119t–2120t, 2121f of actinide ions, 2132–2133 of actinide metals, 2323 of americium, 1298t, 1299 of carbides, 2198, 2198f, 2199t of dioxides, 2138–2141, 2139f, 2142t of hydrides, 2188–2190, 2190t of neptunium dioxide, 2272–2273, 2273f hydrides, 723–724 of nitrohalides, 2182, 2187t of oxyhalides, 2182, 2187t of plutonium, 945–949 history of, 945–947 oxides, 1076 of protactinium, 192, 193t of tetrahalides, 2166t, 2167, 2168f of thorium, dioxide, 2272–2273, 2273f of transition metal compounds, 2206t, 2210–2211

of trihalides, 2170t, 2176 tribromides, 2172f, 2174t, 2176 trichlorides, 2172f, 2173t, 2176 trifluorides, 2171t, 2172f, 2176 triiodides, 2172f, 2175t, 2176 of uranium dioxide, 2272–2273, 2273f hydrides, 333–334, 334f oxide difluoride, 565 oxides, 1076 Heat source actinium as, 42–43 plutonium–238 as, 703, 817 oxides, 1023–1025 Heavy Element Volatility Instrument (HEVI) for isothermal chromatographic systems, 1664 for rutherfordium study, 1693, 1694f Heavy fermions behavior of, 2342–2343, 2343f description of, 2341–2342 ground states of, 2342 magnetic properties of, 2360 Heavy-ion bombardment problems with, 1761–1762 as source of actinide elements, 1761–1763 HEDPA. See 1-Hydroxyethylene–1,1diphosphonic acid HE-EELS. See High-energy electron energy loss spectroscopy HEHA. See 1,4,7,10,13,16Hexaazacyclohexadecane-N,N0 ,N00 , N000 ,N0000 -hexaacetic acid Helium, from plutonium decay, 980, 985–987, 985f, 987f accumulation of, 986 amount of, 985 study of, 986–987, 987f HEMΦP. See 2-Ethylhexylphenylphosphonic acid Hemosiderin, in liver, 3397–3398 6,6,7,7,8,8,8-Heptafluoro–2,2-dimethyl–3,5octanedione (FOD), separation with, 2632, 2680 HEU. See Highly enriched uranium HEVI. See Heavy Element Volatility Instrument 1,4,7,10,13,16-Hexaazacyclohexadecane-N, N0 ,N00 ,N000 ,N0000 -hexaacetic acid (HEHA), for tumor radiotherapy, 43 Hexafluorides of actinide elements, 2083–2085, 2083t, 2084f–2085f complexes of, 2578 Hexafluoroacetylacetone (HFA), SFE separation with, 2680 Hexahalides structural chemistry of, 2419, 2421, 2421t

Subject Index

I-57

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 thermodynamic properties of, 2159–2161, 2160t gaseous, 2160–2161, 2164t solid, 2159–2160, 2160t HF calculations. See Hartree-Fock calculations HFA. See Hexafluoroacetylacetone HFIR. See High-Flux Isotope Reactor HFO. See Hydrous ferric oxide HFS approach. See Hartree-Fock-Slater approach α-HIBA. See α-Hydroxyisobutyric acid High resolution inductively coupled plasma mass spectrometry (HR-ICPMS), 3324–3326, 3325f High-energy electron energy loss spectroscopy (HE-EELS), for plutonium study, 967 Highest occupied molecular orbit (HOMO) of thorocene, 1946 of uranyl, 1916–1917, 1917f High-Flux Isotope Reactor (HFIR) berkelium–249 from, 1445, 1448 californium production in, 1501, 1503 einsteinium production in, 1582 neutron irradiation at, 1759–1760 plutonium–239 in, 821 target preparation for, 1401 for transcurium element production, 9 for transfermium element production, 12 High-flux nuclear reactors, for transplutonium element production, 9 High-level aqueous raffinate waste (HAW), TRUEX process for, 2743–2744 High-level liquid waste (HLLW), actinide recovery from, 2717 High-level waste (HLW) electrodeposition for, 717 ‘light glass’ v., 1273 long-lived actinides in, 2729, 2729t neptunium in intermetallic compounds, 721 neptunium–237 in, 702, 783 partitioning of, 712–713, 2756–2757 problem of, 2728–2729 reprocessing of, 704 DMDBTDMA, 2756 n-Octyl(phenyl)-N,N-diisobutylcarbamoyl methylphosphine oxide for, 1407–1408 Purex process for, 710–712, 710f, 1273–1276, 1285 TRPO for, 2753, 2754t TRUEX process for, 1275, 2740–2745 uranium in, 270 Highly enriched uranium (HEU) description of, 1755 production and use of, 1755–1758

High-performance liquid chromatography (HPLC) ARCA with, 1665 berkelium separation with, 1449–1450, 1450f curium separation with, 1433 einsteinium separation with, 1585 ICPMS and, 3068–3069, 3068f for separation, 3281 High-purity germanium detector (HPGe) for gamma-spectroscopy, 3297–3299, 3299f for uranium analysis, 635 High-purity product refinement, of uranium ore, 314–317, 315f–316f, 317t High-temperature properties of carbides, 2198, 2198f, 2199t of dioxides, 2138–2141, 2139f, 2142t of halides, 2162t–2163t of hexahalides, 2162t–2163t of hydrides, 2188–2190, 2190t ions in condensed phase, 2116–2118, 2117t, 2119t–2120t, 2121f of nitrides, 2199t, 2202 of oxides with alkali metals, 2151–2153 with alkaline earth metals, 2157, 2158t of oxyhalides, 2182, 2183t–2184t, 2186t–2187t of pentahalides, 2162t–2163t of sesquioxides, 2139f, 2146–2147 of tetrahalides, 2166t, 2167–2168 of transition metal compounds, 2207t, 2208f, 2211 of trihalides, 2162t–2163t, 2176–2177, 2177f Hill plot, for uranium compounds, 2331–2333, 2332f HLLW. See High-level liquid waste HLW. See High-level waste HOMO. See Highest occupied molecular orbit HOPO. See Hydroxypyridonate ‘Hot fusion’, element production by, 1738 Hot-wire deposition, for uranium metal preparation, 319 HPGe. See High-purity germanium detector HPLC. See High-performance liquid chromatography HR-ICPMS. See High resolution inductively coupled plasma mass spectrometry Hu¨ckel calculations, on cyclopentadienyl complexes, 1957–1959 Human actinide elements in, 3339–3424 binding in bone, 3406–3412 bone, 3400–3406 liver, 3395–3400 clearance from circulation, 3367–3387 dioxo ions, 3379–3387 rates of, 3367–3369, 3368f–3375f

I-58

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Human (Contd.) tetravalent and pentavalent, 3376–3379 trivalent, 3370–3376 in vivo chelation, 3412–3423 desferrioxamine, 3414 polyaminopolycarboxylic acids, 3413–3414 siderophores, 3414–3423 initial distribution in, 3340–3356 access to, 3340–3341 adult men, 3346t dioxo ions, 3354–3356 ionic radii and stability constants, 3346, 3347t pentavalent, 3350–3354 skeletal fraction, 3346–3349, 3348f soft tissues, 3349–350 tetravalent, 3350–3354 trivalent, 3345–3350 tissue deposition kinetics, 3387–3395 tissue sample, DIPEX resin for, 3284 transport in body fluids, 3356–3367 extracellular fluid circulation, 3357–3359 loose connective tissue, 3359 plasma and tissue fluid composition, 3356–3357, 3357t–3358t plasma distribution of, 3357t–3358t, 3359–3361 Humic acid (HA) americium (III) complexation with, 1353–1354 complexes of, 2590–2591 environmental actinides and, 3139–3140 for thorium complexation, 132–133 Huttonite, thorium in, 55–56 Huzinaga-Cantu equation, RECPs v., 1908 Hydration enthalpy, calculation of, 2538–2539 Hydration numbers of actinide cations, 2532–2533, 2533t hexavalent, 2531–2532 pentavalent, 2531–2532 tetravalent, 2530–2531 trivalent, 1605, 2528–2530, 2529f, 2529t of americium, 1327, 1328f americium (III), 2534, 2535t of curium (III), 2534, 2535f, 2535t–2536t in concentrated solutions, 2536–2538, 2537f of einsteinium, 1605 of europium (III), 2534, 2535t in concentrated solutions, 2536–2538, 2537f of neodynium (III), 2534, 2535t of neptunyl ion, 2531 of thorium, 118 of uranyl ion, 2531–2532

Hydration, of actinide cations, 2528–2544 in concentrated solution, 2536–2538, 2537f hexavalent, 2531–2532 in non-aqueous media, 2532–2533 overview, 2528 pentavalent, 2531–2532 tetravalent, 2530–2531 thermodynamic properties, 2538–2544, 2540t–2541t, 2542f, 2543t, 2544f trivalent, 2528–2530, 2529f, 2529t Hydrazine organouranium catalytic reduction of, 2994–2996 plutonium processing with, 1142 Hydrides of actinide elements, 1790, 1791t–1795t of americium, 1305t–1312t, 1314 of berkelium, 1463, 1464t–1465t preparation of, 1460 of californium, 1540–1541 of curium, 1413t–1415t, 1416–1417 of neptunium, 722–724 chemical behavior, 724 heat capacity, 723–724 physical properties of, 722, 723f, 724t thermodynamic properties, 722–723 of plutonium, 989–996 air reaction with, 3218 applications, 995–996, 996f corrosion, 977–979 electrical properties of, 3205 electronic structure of, 995, 995t history of, 989 hydrogen reaction with, 3215–3216 magnetic properties, 3205–3206 nitrogen reaction with, 3217–3218 oxygen reaction with, 3216–3217 phase diagram of, 990, 991f–992f physical properties of, 990, 995, 995t preparation and reactivity of, 989–990 solid state structures, 992–994, 993f, 993t stoichiometry and phase relationships, 990–992, 991f–992f storage and handling of, 989 thermodynamic properties of, 3205, 3206t water reaction with, 3219 of protactinium, 194 structural chemistry of, 2402–2404 americium, 2404 berkelium, 2404 curium, 2404 neptunium, 2403–2404 plutonium, 2403–2404 protactinium, 2402–2403 thorium, 2402 uranium, 2403

Subject Index

I-59

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 thermodynamic properties of, 2187–2190 enthalpy of formation, 2187–2188, 2187t, 2189t, 2190f entropy, 2188, 2189t high-temperature properties, 2188–2190, 2190t of thorium, 64–66, 66t decomposition of, 65 formation of, 64–65 properties of, 64 reaction with, 65 structure of, 64 ternary, 65–66, 66t of uranium, 328–339, 3213–3214 chemical properties of, 336–337, 337t crystal structures of, 329–330, 329t electrical resistivity, 333 magnetic properties and bonding of, 333–336, 334f, 335t other compounds of, 337–339 phase relations and dissociation pressures of, 330–332, 330f–331f preparative methods for, 329 reactions of, 337, 337t thermodynamic properties, 332–333, 332t use of, 333 Hydrobiotite, uranyl-loaded, 3156 Hydrobromic acid, rutherfordium extraction with, 1697–1698 Hydrocarbyls, of neptunium, 752 Hydrochloric acid curium separation in, 1409 dubnium separation in, 1705 plutonium processing in, 836 rutherfordium extraction with, 1696–1699 uranates (V) and (IV) dissolution in, 381–382 uranium compound dissolution in, 632 metal reactions with, 328 oxide reactions with, 370–371 Hydrofluoric acid protactinium (IV) precipitation by, 222 as protactinium solvent, 176, 178–179 rutherfordium extraction with, 1699–1700 Hydrofluorination, of uranium, 319, 320f Hydrogen plutonium corrosion by, 977–979 hydrides reaction with, 3215–3216 metal reaction with, 3223–3225, 3224f and water formation of, 3250 radiolytic formation of, 3246–3247 hazards of, 3248–3249 uranium metal solubility of, 330f, 331–332 reaction with, 3239–3242, 3240f, 3241t Hydrogen peroxide berkelium extraction with, 1448

protactinium extraction with, 175, 179 reduction by americium (V), 1335–1336 americium (VI), 1335 UO2 dissolution in, 371 Hydrolytic behavior of actinide cations, 2545–2556, 2545f hexavalent, 2553–2556, 2554f–2555f, 2554t–2555t pentavalent, 2552–2553 tetravalent, 2547–2552, 2549t–2550t, 2551f–2552f trivalent, 2546, 2547f, 2547t–2548t of actinide complexes, ternary, 2592–2593 of actinide elements, 1555, 1778–1782, 1810–1811 of americium, 1339–1340 of berkelium, 1475–1479, 1477t–1478t of californium, californium (III), 1554 in mammalian body, 3340 of neptunium, 766–770 neptunium (III), 768 neptunium (IV), 768–769 neptunium (V), 727, 769–770 neptunium (VI), 770 neptunium (VII), 770 tendency towards, 766, 767t of 5f orbital, 3100 of plutonium characterization of, 1146–1147 importance of, 1146 ions, 1110–1111 nitrides, 1019 plutonium (III), 1147–1149, 1148t plutonium (IV), 1148t, 1149–1150, 1781 plutonium (V), 1154–1155 plutonium (VI), 1155–1156 plutonium (VII), 1156 stability of, 1146–1156 of protactinium, 170–171, 179 protactinium (IV), 222, 1780 protactinium (V), 209–212, 210f, 211t, 212f, 1782 of rutherfordium, 1701 of seaborgium, 1711 sorption process v., 1810 of thorium, 119–120, 121t, 122f of transactinide elements, 1686–1687, 1687t of uranium aqueous complexes, 597–600, 599t carbides, 403–405 pentavalent and complex halides, 501 uranium (IV), 585–586, 1780–1781 Hydrometallurgy, 2727–2729 long-lived actinides in HLW, 2729, 2729t problem for, 2728–2729 SNF overview, 2727–2728

I-60

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Hydrosilylation, organometallic intermediates in, 2916–2918, 2917f Hydrosphere, actinide elements in, 1807–1810 Hydrous ferric oxide (HFO), uranyl interaction with, 3166 Hydroxamic acid, for plutonium removal, 1824 Hydroxides of actinide elements, 1796 of actinyl, 1925–1926, 1926t, 1927f of americium, 1303, 1305t–1312t, 1313–1314 history of, 1313 preparation of, 1313–1314 of mendelevium, 1635 of neptunium, 724–730 heptavalent, 726–727 hexavalent, 727 pentavalent, 727 tetravalent, 727–728 of plutonium, 3213 precipitation with, 836, 838 precipitation with, 2633–2634 of protactinium, 207–208 gravimetric methods with, 229 of seaborgium, 1709 thermodynamic properties of, 2190–2192 enthalpy of formation, 2190–2191, 2191t entropy, 2191, 2191t solubility products, 2191–2192 of thorium, 76 of uranium, 259t of uranyl, 1925–1926, 1926t, 1927f Hydroxycarboxylic acids, fermium complexes with, 1629 1-Hydroxyethylene–1,1-diphosphonic acid (HEDPA), actinide stripping with, 1280–1281 α-Hydroxyisobutyric acid (α-HIBA) berkelium separation with, 1449–1450, 1450f californium separation with, 1508 curium separation with, 1409 dubnium separation with, 1704–1705 fermium separation with, 1624, 1629 lawrencium separation with, 1643, 1645 separation with, 2639–2641, 2640f, 2641t, 2650 α-Hydroxyl–2-methyl butyrate, californium extraction with, 1512 Hydroxylamine, plutonium processing with, reduction and oxidation reactions, 1140–1141 Hydroxypyridinonate ligands, as chelating agents, 3415f, 3416–3417, 3417f–3418f Hydroxypyridonate (HOPO) complexes of, 2590–2591 for plutonium removal, 1824–1825, 1825f

8-Hydroxyquinoline actinide complexation with, 1783 californium extraction with, 1513 Ianthinite at Pen˜a Blanca, Chichuhua District, Mexico, 272–273 uranium in, 259t–269t ICPAES. See Inductively coupled plasma atomic emission spectrometry ICPMS. See Inductively coupled plasma mass spectrometry ID analysis. See Isotope dilution analysis IDA. See Iminodiacetate Identification electron-photon, -electron, -ion techniques for, 3047–3055 AES, 3049t, 3051 COUL, 3049t, 3052 DPV and DPP, 3049t, 3052, 3053f EDS, 3049t, 3050–3051 EELS, 3049t, 3051–3052 EMPA, 3049t, 3050 ESMS, 3049t, 3052–3055, 3054f overview of, 3047, 3049t, 3050 SEM, 3049t, 3050, 3051f SSMS, 3049t, 3055 in environment, 3013–3073 background, 3013–3021 combining and comparing analytical techniques, 3065–3071 sampling, handling, treatment, and separation, 3021–3024 specifics of, 3024–3065 ion-photon, -electron, -neutron, -ion techniques for, 3058–3065 AMS, 3059t, 3062–3063 ERDA, 3059t, 3065 ICPMS, 3059t, 3061–3062 NRA, 3059t, 3061 overview of, 3058–3060, 3059t PIGE, 3059t, 3061 PIXE, 3059t, 3060–3061 RBS, 3059t, 3063–3064, 3064f SIMS, 3059t, 3062, 3063f VOL, 3059t, 3061 neutron-photon, -electron, -neutron, -ion techniques for, 3055–3057 DNAA, 3056t, 3057 NAA, 3055–3057, 3056t, 3058f overview of, 3055–3057, 3056t passive techniques for, 3025–3033 βS, 3026t, 3028–3029 GRAV, 3026t, 3029 γS, 3025–3028, 3026t, 3028f ISEs, 3026t, 3029

Subject Index

I-61

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 LSC, 3026t, 3031, 3032f MBES, 3026t, 3028 NS, 3026t, 3029 overview of, 3025, 3026t RAD, 3026t, 3031, 3032f αS, 3026t, 3029–3031, 3030f XS, 3025, 3026t photon-phonon, -electron, -neutron, -ion techniques for, 3043–3047 LAICPMS, 3044t, 3046–3047 LAMMA, 3044t, 3046 LIBS, 3044t, 3045 LIPAS, 3043–3045, 3044t, 3045f overview of, 3043 PHOTN, 3044t, 3046 RIMS, 3044t, 3047, 3048f RIS, 3044t, 3047 SEXAS, 3044t, 3046 TIMS, 3044t, 3046–3047 UPS, 3044t, 3045 XPS, 3044t, 3045–3046 photon-photon techniques for, 3033–3043 AAS, 3034t, 3036 COL, 3034t, 3035 IRS, 3033–3035, 3034t LAICPOES, 3034t, 3036–3037 MBAS, 3034t, 3043 NIR-VIS, 3034t, 3035 NMR, 3033, 3034t overview of, 3033, 3034t PCS, 3034t, 3035–3036 PHOTA, 3034t, 3043 RAMS, 3034t, 3035, 3036f TOM, 3034t, 3040–3043, 3042f TRLF, 3034t, 3037, 3038f UVS, 3034t, 3037 XANES, 3034t, 3039, 3040f XAS, 3034t, 3037–3039, 3040f XRF, 3034t, 3039, 3041f Ignition of plutonium catalyzed, 3236–3237 thermal, 3232–3235, 3233f of uranium, thermal, 3245–3246 Iminodiacetate (IDA) plutonium complex with, 1176–1177, 1178t, 1180–1181 of uranium, 603–605, 604t Immobilization, of SNF, 1812–1813 In situ leaching, of uranium ore, 306 INAA. See Instrumental neutron activation analysis Indenyl complexes with cyclopentadienyl, 2844 structural chemistry of, 2487–2489, 2490t–2491t Indium, in plutonium alloy, 896, 896f

Inductively coupled plasma atomic emission spectrometry (ICPAES), overview of, 3307–3308 Inductively coupled plasma mass spectrometry (ICPMS) with AES, 636, 1770 αS v., 3329 βS and, 3070 applications of, 3326–3328 capillary electrophoresis with, 3069 components of, 3323–3324, 3324f development of, 3329 for electronic structure, 1770 for environmental actinides, 3059t, 3061–3062 fundamentals of, 3323–3326, 3324f HPLC and, 3068–3069, 3068f HR, 3324–3326, 3325f INAA v., 3329 for mass spectrometry, 3310 MC, 3326–3327 nebulizers for, 3323 neptunium neptunium–237 determination, 789, 790f separation with, 783, 784f, 793 overview of, 3322 requirements of, 3323 spectra from, 3324–3326, 3325f for thorium, 133 for trace analysis, 3322–3328 of uranium, 637–639 Infrared spectroscopy (IRS) of actinide dioxides, 1971 of actinide nitrides, 1988–1989 of americium, 1369 of californium, 1544–1545 of cyclopentadienyl complexes, tetravalent, 2814–2815 for environmental actinides, 3033, 3034t of neptunium, 764 overview of, 2014 of plutonium halides, 1183 of thorium disulfide, 1976 of uranium cyclopentadienyl complexes, 2807, 2807t of uranium oxides, 1971 XRD and, 3065 XRF and RAMS with, 3069 Ingestion, of actinide elements, 1818–1820 Inhalation, of actinide elements, 1818–1820 Inner sphere, complexation, 2563–2566, 2566f, 2567t confusion over, 2564 conversion to, 2564–2565 stability constant, 2565, 2566f thermodynamic data, 2566, 2567f

I-62

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 In-situ Volatilization and On-line detection apparatus (IVO), for hassium study, 1713, 1714f Instrumental neutron activation analysis (INAA) applications of, 3303–3305 description of, 3303 ICPMS v., 3329 RNNA v., 3305–3306 sensitivity of, 3305 for uranium, 636 Integral fast reactor (IFR) electrorefining with, 2713 reprocessing in, 2713–2714 Intense Pulsed Neutron Source (IPNS) of curium dioxide, 2292–2293 of plutonium dioxide, 2289, 2290f Intermediate coupling for free-ion interactions modeling, 2023–2026 overview of, 2023 Intermetallic compounds of americium, 1302, 1304t of berkelium, 1461 magnetic studies of, 2238, 2356–2361 heavy-fermion materials, 2360 high uranium content, 2357 itinerant ferromagnets, 2358–2359 low uranium concentration, 2359 lower uranium content, 2358 other compounds, 2360–2361 very low uranium concentration, 2359–2360 of plutonium, 862–987 applications of, 862 crystal structure data for, 899, 900t–915t electronic structure, theory, and modeling, 921–935 history of, 862 mechanical properties, 968–973 nature of, 863 overview of, 898–899 oxidation and corrosion, 973–979 physical and thermodynamic properties of, 935–968 of uranium, 325–326, 325t hydrides as, 338–339 molybdenum, 326, 326f noble metals, 325–326 transition-metal compounds, 325 x-ray crystallography for, 325 Iodates of actinide elements, 1796 of neptunium, equilibrium constants for, 773t of plutonium, 1172–1173 of protactinium, gravimetric methods with, 230

Iodides of actinide elements, 1796 of berkelium, 1469 of californium, 1533 of neptunium, 738 equilibrium constants for, 773t triiodide, 738 of plutonium, 1092–1100 preparation of, 1092–1095 properties of, 1087t, 1098–1100 solid-state structures of, 1084t, 1096–1097, 1096f–1098f protactinium derivatives of, 197–199, 207–208 of uranium complexes, 498–499 oxide and nitride, 499–500 uranium tetraiodide, 497–498 uranium triiodide, 454–455 Ion exchange chromatography for actinide and lanthanide separation, 2669–2670 for actinide element study, 1767–1768, 1768f actinium purification by, 18, 30–32 for americium purification, 1289–1293 anion-exchange resin systems, 1291–1292 cation-exchange resin systems, 1290–1291 inorganic exchangers, 1292–1293 ARCA for microscale, 1665 for berkelium extraction, 1449 for californium separation, 1508–1509, 1510f, 1512 for curium separation, 1409–1410 deployment of, 846 for einsteinium separation, 1585 flow sheet for, 849, 850f improvements of, 851 for metal ion separation, 846 methods for anion exchange, 2635–2637, 2635f, 2642 in aqueous phase, 2638 cation exchange, 2636–2641, 2637f citric acid for, 2638–2639, 2639t Diphonix, 2642–2643, 2643f EDTA and HDEHP for, 2639–2640, 2641t α-HIBA for, 2639–2641, 2640f, 2641t historical development of, 2634–2635 lactic acid for, 2639, 2639t, 2641t NTA and DTPA for, 2640–2641 trivalent actinides from lanthanides, 2635, 2635f for neptunium extraction, 714 operation of, 850–851 overview of, 845–846 for plutonium concentration, 845–852 after extraction, 846–847

Subject Index

I-63

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 history of, 851 overview of, 847 plutonium–238, 817 for protactinium purification, 180–181, 180f for rutherfordium extraction, 1699 for trace analysis, 3282–3283 for transfermium element identification, 13 for uranium leach recovery, 310–311 problems with, 311 process for, 310 solvent extraction v., 311 species absorbed, 310–311 Ion pair formation systems, for extraction, 2660, 2661f Ionic radii of actinide elements, 1798, 1799t of actinide (III) ions, 1605–1607 in mammalian tissues, 3346, 3347t of americium, 1295–1296 of californium, 1528–1529, 1528f of einsteinium, 1604, 1605–1607 importance of, 1612–1613 sesquioxide, 1598 of lawrencium, 1645 of mendelevium, 1635 of nobelium, 1640 oxidation states and, 2558 skeletal fraction v., 3349 stability constants and, 2574, 2575f Ion-ion interaction of actinides, 2101–2103 nonexponential luminescence decay from, 2102–2103 Ionium. See Thorium–230 Ionization potentials (IP) of actinide elements by laser spectroscopy, 1873–1875, 1874t by RIMS, 1875–1879, 1877t, 1878f–1879f of actinium, 33, 1874t of americium, 1296, 1874t of berkelium, 1452, 1874t breit effect on, 1669 of californium, 1874t of curium, 1874t of einsteinium, 1588, 1590f, 1874t of element 113, 1723, 1726t of element 114, 1725, 1726t of element 115, 1725f, 1726t, 1727 of element 116, 1726t, 1728 of element 117, 1726t, 1728 of element 118, 1726t, 1728–1729 of element 119, 1729, 1730f of element 120, 1729, 1730f of fermium, 1877 of neptunium, 1874t, 1875 of plutonium, 859, 1874t of protactinium, 1874t

of superactinide elements, 1731 of thorium, 59–60, 1874t of transactinide elements, 1673–1675, 1673t, 1674f–1675f of uranium, 1874t Ion-selective electrodes (ISEs), for environmental actinides, 3026t, 3029 IP. See Ionization potentials IPNS. See Intense Pulsed Neutron Source Iriginite umohoite transformation to, 299, 300f uranium molybdates in, 299 Iron in aqueous environment, 3097, 3097f in curium complex, 1413t–1415t, 1422 in environment, 3164–3165 in plutonium alloy, 972 reduction, 1138–1139 plutonium melting point and, 897, 898f protactinium separation from, 179–180, 180f sorption on mineral phases of, 3164–3169 with carbonates, 3168 with citrates, 3167–3168 neptunium, 3165, 3165t uranium, 3165, 3165t, 3167 in transferrin, 3363–3364 uranate preparation with, 388 Iron (II), analyses of ISEs, 3029 VOL, 3061 Iron (III), analyses of, ISEs, 3029 IRS. See Infrared spectroscopy IS. See Isotope shift ISEs. See Ion-selective electrodes Island of stability overview of, 14 SHEs v., 1653 substantiation of, 1735–1736, 1736f Isocyanide ligand, cyclopentadienyl complexes insertion of, 2825, 2826f Isothermal chromatographic systems for gas-phase chemistry, 1663–1665, 1705 for seaborgium study, 1708–1709, 1709f for superactinide elements, 1734 Isotope dilution (ID) analysis for ICPMS, 3326 with TIMS, 3313 of uranium, 638 Isotope dilution mass spectrometry, for protactinium–231, 231 Isotope shift (IS) of actinide elements, 1841, 1842t–1850t, 1851–1852, 1853f, 2015–2016 of americium, 1882–1884, 1883f, 1883t of californium, 1872

I-64

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Isotopes of actinium, 18–19, 22t–23t, 31–32 of americium, 9–10, 12, 1265–1267, 1266t of berkelium, 9–10, 1445–1447, 1446t of bohrium, 1657f–1658f of californium, 9–10, 12, 1499–1502, 1500t of curium, 9–10, 12, 1397–1400, 1399t of darmstadtium, 1657f–1658f of dubnium, 1657f–1658f of einsteinium, 10, 1579, 1581t, 1582 of element 112, 1657f–1658f of element 113, 1657f–1658f of element 114, 1657f–1658f of element 115, 1657f–1658f of element 116, 1657f–1658f of fermium, 10, 1622–1624, 1623t of hassium, 1657f–1658f of lawrencium, 1642, 1642t, 1657f–1658f longer-lived, 14 of meitnerium, 1657f–1658f of mendelevium, 1630–1631, 1631t of neptunium, 9–10, 12, 700–702, 701t production of, 702–704 of nobelium, 1637, 1638t of plutonium, 4, 8–10, 12, 815–817, 816t decay of, 1143–1146 formation of, 821, 825–826, 825f from nuclear power reactors, 826, 827t–828t, 828 separation of, 821–822, 828–831 of protactinium, 161–162, 164–170, 165t of roentgenium, 1657f–1658f of rutherfordium, 1657f–1658f of seaborgium, 1657f–1658f of thorium, 53–55, 54t–55t of transactinide elements, 1657f–1658f of uranium, 4, 8–10, 255–257, 256t, 258t Isotopomers, for matrix-isolated actinide molecules, 1968 Itinerant electron behavior, in actinides, 1–2 IVO. See In-situ Volatilization and On-line detection apparatus Ja´chymov mine, marecottite and zippeite in, 292 Jahn-Teller effect, low-symmetry structures from, 2369 JINR. See Joint Institute for Nuclear Research J-j coupling for coupling spin and angular momenta, 1911 LS coupling transition to, 1912–1914 Joint Institute for Nuclear Research (JINR), darmstadtium discovery at, 1653 Joint Working Party (JWP), darmstadtium analysis by, 1653

JT effect, on plutonium dioxide, 2290 Judd-Ofelt theory absorption spectra analysis with, 2091–2093, 2092f–2093f for fluorescence lifetime calculation, 2093–2095 matrix elements computation with, 2090–2091 JWP. See Joint Working Party Kidneys accumulation of protactinium–231, 188 actinide elements in, 1815 uranium in, 1820–1821 uranyl ion in, 3380 complexes, 3382–3383 Kinetics considerations for handling, storage, and disposition, 3201–3204 rate-controlling factors and mechanisms, 3202–3204 scope of concerns, 3201–3202 of corrosion plutonium metal, 3223–3227, 3226f, 3227t, 3237 uranium metal and compounds, 3239–3246 of hydroamination by organoactinide complexes, 2990–2993 terminal alkyne complexes, 2986–2990 of hydrogenation, arene ligands, 3002 of hydrosilylation, terminal alkyne complexes, 2957, 2965–2966 of plutonium reactions, 3215–3223 of tissue deposition, 3387–3395 in mice, 3388–3395, 3389f–3392f, 3394t in rats, 3387–3388 Kohn-Sham (KS) orbitals, with HF equations, 1903 Koongarra deposit, uranium deposits at, 273 Kopmans’ theorem, overview of, 2335–2336 Kramers degeneracy, description of, 2228 Kramer’s degeneracy, overview of, 2044 KS orbitals. See Koshn-Sham orbitals Kyzylsai deposit, mourite in, 301 Laboratoire Aime´ Cotton (LAC), FTS at, 1840 Lactic acid, for separation, 2639, 2639t, 2641t LAICPMS. See Laser ablation inductively coupled plasma mass spectroscopy LAICPOES. See Laser ablation inductively coupled plasma optical spectroscopy LAMMA. See Laser ablation micro mass analysis

Subject Index

I-65

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 LAMS. See Laser ablation mass spectrometry Lanthanide elements actinide elements relativistic effects on, 1898, 1899f actinide elements v., 2, 10–11 atomic volume, 1578–1579, 1578f bonding in, 584–585 extraction from, 1286–1289, 1407 free-ion interaction and crystal-field strength, 2062–2064, 2063t ligand displacement series for, 2806 phonon energy relaxation, 2096 separation from, 2635, 2635f thermodynamic properties of hydration, 2542–2544, 2544t actinide separation from, 2669–2677, 2757–2760 Cyanex 301, 2675–2676 dithiophosphinic acids, 2676 LIX–63, 2759–2760 process applications, 2670–2671 separation factors for, 2669–2670, 2670t soft-donor complexants for, 2670–2671, 2673 sulfur donor extractants, 2676–2677, 2677t TALSPEAK, 2671–2673, 2672f, 2760 TPTZ, 2673–2675, 2674t TRAMEX process, 2758–2759, 2759f bisphosphine oxide extraction of, 2657 elution of, 1625f fermium separation from, 1624–1625 ionic radii of, 1528–1529, 1528f oxides with plutonium oxides, 1069–1070 Wigner-Seitz radius of, 2310–2312, 2311f Lanthanocenes, properties of, 1947 Lanthanum actinium v., 18, 40 americium interaction with, 1302 separation from, 1271 in californium metal production, 1517 fluoride, for plutonium coprecipitation, 833–835 Large-Angle X-ray Scattering (LAXS) for coordination number analysis, 586 EXAFS v., 589 for obtaining structural information, 589 Larisaite, as uranyl selenite, 298 Laser ablation inductively coupled plasma mass spectroscopy (LAICPMS), for environmental actinides, 3044t, 3046–3047 Laser ablation inductively coupled plasma optical emission spectroscopy (LAICPOES), for environmental actinides, 3034t, 3036–3037

Laser ablation mass spectrometry (LAMS), for mass spectrometry, 3310 Laser ablation micro mass analysis (LAMMA), for environmental actinides, 3044t, 3046 Laser ablation technique, in gas-phase studies, of einsteinium, 1612 Laser fluorescence spectroscopy for actinide element study, 14 of californium, 1544 of hydrolytic behavior, 2546 Laser spectroscopy of actinide elements, 1873 ionization potentials by, 1873–1875, 1874t super-deformed fission isomers of americium, 1880–1884, 1881f, 1883f–1884f, 1883t of uranium (III), 2064 Laser-induced breakdown spectroscopy (LIBS) for environmental actinides, 3044t, 3045 neptunium study with, 766 Laser-induced isotope enrichment, of uranium hexafluoride, 1933 Laser-induced photoacoustic spectroscopy (LIPAS) americium study with, 1880 for environmental actinides, 3043–3045, 3044t, 3045f neptunium study with, 766, 787 Lattice constant of berkelium berkelium–249, 1462 metallic state, 1458 of neptunium, hydrides, 722, 724t of plutonium, 2329–2330, 2329f gallium alloys, 939, 941t of thorium nitrides, 99 Lattice parameters of berkelium chalcogenides, 1470 of californium metal, 1519–1521, 1520t pyrochlore oxides, 1538, 1540f sesquioxide, 1536–1537 of curium pnictides, 1421 of einsteinium sesquioxide, 1598–1599, 1599f of neptunium coordination compounds, 746t–747t hexafluoride, 731t, 732 metallic state, 719 sulfides, 740 tellurides, 742 of plutonium, 935–937 alloys and, 930, 930f intermetallic compounds, 899, 900t–915t oxides with uranium oxides, 1071–1073, 1072f self-irradiation damage to, 981–984

I-66

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Lattice parameters (Contd.) of uranium dioxide, 390, 391t–392t halides, 422, 423t–441t, 530t–556t oxide, 344, 345t–346t oxides with plutonium oxides, 1071–1073, 1072f Lawrence Berkeley National Laboratory (LBNL) darmstadtium discovery at, 1653 hassium study at, 1712–1713 rutherfordium production at, 1701 transactinide element claims of Dubna v., 1659–1660 Lawrence Livermore National Laboratory (LLNL), seaborgium production at, 1707 Lawrencium, 1641–1647 atomic properties, 1643–1644 berkelium–249 in production of, 1447 chemical properties of, 1644–1647, 1646t discovery of, 6t, 13, 1641 half-life of, 1642, 1642t isotopes of, 1642, 1642t, 1657f–1658f lanthanide elements v., 2 metallic state of, 1644 oxidation states of, in aqueous solution, 1774–1776, 1775t preparation and purification, 1642–1643 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f solution chemistry, 1644–1647 synthesis of, 13, 1641 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t Lawrencium–255, production of, 1641, 1642t Lawrencium–256 half-life of, 1642, 1642t isolation of, 1642–1643 production of, 1641–1642 x-ray emission of, 1644 Lawrencium–257 half-life of, 1641–1642, 1642t production of, 1641 Lawrencium–258 from dubnium–262, 1704 half-life of, 1642, 1642t Lawrencium–260 half-life of, 1645 production of, 1642 LAXS. See Large-Angle X-ray Scattering Layer structures. See Sheet structures LBNL. See Lawrence Berkeley National Laboratory

LCAO. See Linear combinations of atomic orbitals LDA. See Local density approximation Lea, Leask, and Wolf method, application of, 2229–2230 Leaching calcination prior to, 304 of uranium ores, 303 forms of, 305–306 object of, 304 oxidizer for, 305 reagent for, 304–305 recovery of, 309–317 Lead element 164 v., 1732 thermodynamic properties of actinide compounds with, 2206–2208, 2206t–2207t in uraninite, 274 uranium compounds with, 407 oxides, 383–389, 384t–387t uranyl oxyhydroxides with, 287–288 Lead–212, nuclear properties of, 3298t Lead–214, nuclear properties of, 3298t Least-squares fitted values, of actinide elements, 1864–1865, 1864f Lepersonnite, description of, 293 Lermontovite, uranium in, 259t–269t, 275 LEU. See Low-enriched uranium Lewis acids, actinide elements as, 1901 Ligands actinide element bonding of, 1900–1901 carbon-based, 2800–2867 alkyl, 2866–2867 allyl, pentadienyl and related, 2865–2866 cyclooctatetraenyl, 2851–2858 cyclopentadienyl, 2800–2851 other carboxylic, 2858–2865 in coordination number, 2558 for thorium in coordination compounds, 115 inorganic, 129–131, 130t ‘Light glass,’ radioisotopes in, 1273 Light water reactor (LWR) fuel recovery from calcium reduction, 2722 lithium reduction, 2722–2723 pyrochemical methods for, 2721–2723 plutonium in, 826 uranium oxides with, 1070 Light Weight Radioisotope Heater Units (LWRHUs) fuel formation for, 1032–1034 plutonium–238 in, 819, 820f Linear combinations of atomic orbitals (LCAO), MO levels as, 1902 LINEX process, overview of, 2724–2725

Subject Index

I-67

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 LIPAS. See Laser-induced photoacoustic spectroscopy Lipofuscin, americium binding to, 1816 Liquid anion-exchange chromatography, 851–852 Liquid plutonium, 960–963 melting point of, 960–962 properties of, 962–963 Liquid scintillation counting (LSC), for environmental actinides, 3026t, 3031, 3032f Liquid scintillation spectrometry for neptunium, 785 for thorium, 133–134 Liquid-liquid extraction (LLE). See also Solvent exchange for actinide elements study, 1768–1769 in RTILs, 2691 of rutherfordium, 1702, 1702f SFE v., 2678 of superactinides, 1735 for trace analysis, 3282 of uranium, 633 Liquid-liquid partitioning, of environmental sample, 3024 Liquid-solid partitioning, of environmental sample, 3024 Lithium in californium metal production, 1517 in curium metal production, 1411–1412 protactinium compounds with, 208 reduction of, for electrorefining, 2722–2723 Lithium chloride curium extraction in, 1407, 1409 einsteinium extraction in, 1585 in electrorefining, 2714–2715 lanthanide, actinide separation with, 1407 Liver actinide elements in, 1815–1816, 3395–3400 stored iron association with, 3398–3399 uptake, 3399–3400 blood supply to, 3396 as deposition site, 3344 bone v., 3344–3345 iron storage in, 3397–3398 actinide elements with, 3398–3399 ferritin, 3397 hemosiderin, 3397–3398 metal transport into, 3396–3397 microanatomy of, 3396 LIX–63, for actinide/lanthanide separation, 2759–2760 LLE. See Liquid-liquid extraction LLNL. See Lawrence Livermore National Laboratory Local density approximation (LDA) for actinide metals, 2328 δ-phase plutonium and, 925

electron density and gradient with, 924 for excited state energies, 1910 Localized electron behavior, in actinides, 1–2 Loose connective tissue, actinides in, 3359 Low-enriched uranium (LEU), description of, 1755 LS coupling for coupling spin and angular momenta, 1911 for free-ion interactions modeling, 2023–2026 j-j coupling transition of, 1912–1914 overview of, 2023 spin-orbit coupling with, 2024–2026 in tetravalent actinide ions, 2075–2076 truncation of, terms, 2042 Luminescence of actinide cations, 2536–2538, 2537f of americium, 1368–1369, 1369f americium (III), 2098 of berkelium, 1453–1454 of curium, 1425, 1429 curium (III), 2096–2097, 2097f decay of, 2101–2102, 2101f of einsteinium, 1579, 1580f, 1602 energy transfer in, 2102–2103 lifetimes of, 2098–2100, 2099t, 2100f measurement of, neptunium, 787–788 of neptunium hexafluoride, 2084–2085 overview of, 627 of plutonium hexafluoride, 2084–2085 Luminescence decay, for hydration study, 2528 Lungs actinide elements in, 1819–1820 transuranium elements in, 12 Lutetium, lawrencium v., 1644 Luttinger theorem, Fermi surface in, 2334 LWR. See Light water reactor LWRHUs. See Light Weight Radioisotope Heater Units Lymphatic system, actinide elements in, 1815 Lysosomes, actinide element uptake with, 1816 MACS. See Magnetically assisted chemical separation Madelung energy, loss of, 2369 Magnesium UO2 solid solutions with, oxygen potentials of, 395t, 396–397 for uranium reduction, 319 uranium v., 318 Magnetic anisotropy exchange interactions in, 2364–2366, 2365f–2366f large groups, 2365–2366

I-68

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Magnetic anisotropy (Contd.) overview of, 2364–2365 two-ion, 2365, 2365f–2366f Magnetic concentration methods, for uranium ore, 303–304 Magnetic dipole moment, neutron scattering and, 2232 Magnetic moment of californium metal and compounds, 1542, 1543t of uranium hydrides, 334–336, 335t Magnetic polyamine-epichlorohydrin resin (MPE resin), americium purification with, 1292–1293 Magnetic properties, 2225–2295 5f0 compounds, 2239–2240 5f1 compounds, 2240–2247 5f2 compounds, 2247–2257 5f3 compounds, 2257–2261 5f4 compounds, 2261–2262 5f5 compounds, 2262–2263 5f6 compounds, 2263–2265 5f7 compounds, 2265–2268 5f8 compounds, 2268–2269 5f9 compounds, 2269–2271 5f10 compounds, 2271 5f11 compounds, 2271–2272 of actinide dioxides, 2272–2294 of actinide elements, 1541–1542, 1542t of actinide metals, 2353–2368 electronic transport and, 2367–2368 exchange interactions and magnetic anisotropy, 2364–2366, 2365f–2366f general features of, 2353–2354 intermetallic compounds, 2356–2361 magnetic structures, 2366–2367 orbital moments, 2362–2364, 2363f other compounds, 2361–2362 in pure elements, 2354–2356 of americium, 2355–2356 americium (II), 2265–2268 americium (III), 2263–2265 americium (IV), 2262–2263 of anhydrous uranium chloride complexes, 451 of berkelium, 2355–2356 berkelium (III), 2268–2269, 2270t berkelium (IV), 2265–2268 ions, 1472, 1473f metallic state, 1460 of californium, 2355–2356 californium (III), 2269–2271, 2270t californium (IV), 2268–2269, 2270t compounds, 1541–1542, 1542t metal, 1525 of curium, 2355–2356 curium (III), 2265–2268 curium (IV), 2263–2265

metallic state, 1411 pnictides, 1421 of dioxides, 2272–2294 americium, 2291–2292 curium, 2292–2293 neptunium, 2282–2288 plutonium, 2288–2290 uranium, 2272–2282 of einsteinium, 1602–1603 einsteinium (II), 2271–2272 einsteinium (III), 2271 of fermium, 1626 of heavy fermions, 2360 of lanthanides, 1541–1542, 1542t of neptunium, 2356–2357 alloys, 719–720 chalcogenides, 742 neptunium (III), 2261–2262 neptunium (IV), 2257–2261 neptunium (V), 2247–2257 neptunium (VI), 2240–2247 neptunium dioxide, 2236–2237, 2237f tetrachloride, 2258t, 2260–2261 of neptunyl ion, 2240–2247, 2255t of plutonium, 949–954, 2355–2357 hexafluoride, 1086–1088 hydrides, 3205–3206 intermetallic compounds, 2361 phosphides, 1022 plutonium (III), 2262–2263 plutonium (IV), 2261–2262 plutonium (V), 2257–2261 plutonium (VI), 2247–2257 plutonium (VII), 2240–2247 pnictides, 1023 silicides, 1015–1016 susceptibility, 949, 953–954, 953f trichloride, 2262 of plutonocene, 1946 of protactinium, 192, 193t carbides, 195 halides, 203 pnictides, 207 protactinium (IV), 2240–2247 protactinium (V), 2239–2240 quantization of, 2317–2318 source of, 2225–2226 superconductivity and, 2238–2239 of thorium, 61–63 antimony, 100 borides, 67 phosphides, 99–100 thorium (III), 2240–2247 thorium (IV), 2239–2240 of thorocene, 1946 of uranium, 2354–2357 arsenide, 2234–2235, 2235f bromide complexes, 496

Subject Index

I-69

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 dioxide solid solutions, 389–390 halides, 443–444, 483 hexafluoride, 561, 2239–2240 hydrides, 333–336, 334f, 335t intermetallic compounds, 2357–2360 iodide complexes, 499 oxides, 389–390 pentavalent and complex halides, 501, 518 silicides, 406 tetrachloride, 491–492, 2248–2251 tetravalent halides, 483 tribromide, 453 trichloride, 448 trifluoride, 445 trihydride, 2257 triiodide, 455 UNiAlHy, 338–339 uranium (III), 2257–2261 uranium (IV), 2247–2257, 2255t uranium (V), 2240–2247, 2247t uranium (VI), 2239–2240 uranium pentachloride, 523 uranium tetrachloride, 491–492 of uranyl ion, 2239–2240 Magnetic scattering of neptunium dioxide, 2283–2284, 2284f of uranium dioxide, 2281, 2282f Magnetic spin-orbit interaction, with effective-operator Hamiltonian, 2029–2030 Magnetic susceptibility of 5f0 compounds, 2240f of 5f1 compounds, 2241 of 5f7 compounds, 2266, 2267t, 2268 of berkelium berkelium (III), 1445, 2268–2269 dioxide, 2268 ions, 1472, 1473f metallic state, 1460 of californium californium (III), 2269–2271, 2270t metal, 1525 of curium curium (IV), 2264–2265 dioxide, 1419, 2293 fluorides, 1418 sesquioxide, 1419 for eigenfunctions, 2226 from empirical wave functions, 2047 of neptunium dioxide, 2283 hexafluoride, 2243 tetrachloride, 2258t, 2260–2261 of plutonium, 2345–2347, 2346f dioxide, 2290, 2291f plutonium (IV), 2261–2262

of protactinium tetrachloride, 2241 tetraformate, 2241 representation of, data, 2230–2231 temperature dependence of, 2365–2366, 2366f of UBe13, 2342, 2343f of uranium dioxide, 2272–2273 hexachloride, 2245–2246 metallic state, 323–324 oxides, 380, 382 sulfates, 2252 tetrachloride, 2248, 2249f tribromide, 2257–2258, 2258t trichloride, 2257–2258, 2258t trifluoride, 2257, 2258t triiodide, 2257–2258, 2258t uranium (III), 2260, 2260t of uranocene, 2252–2253 Magnetically assisted chemical separation (MACS) CMPO in, 2751–2752 design of, 2751, 2751f historical development of, 2750–2751 Magnetite, thorium in, 56t Magnon dispersion curves, of uranium dioxide, 2280–2281, 2280f Malonamide extractants new compounds as, 2659 for solvating extractant system, 2657–2659 Malonates, structural chemistry of, 2441t–2443t, 2447 Mammalian tissues actinide elements in, 3339–3424 binding in bone, 3406–3412 bone, 3400–3406 liver, 3395–3400 clearance from circulation, 3367–3387 dioxo ions, 3379–3387 rates of, 3367–3369, 3368f–3375f tetravalent and pentavalent, 3376–3379 trivalent, 3370–3376 in vivo chelation, 3412–3423 desferrioxamine, 3414 polyaminopolycarboxylic acids, 3413–3414 siderophores, 3414–3423 initial distribution in, 3340–3356 access to, 3340–3341 beagle dogs, 3343t dioxo ions, 3354–3356 ionic radii and stability constants, 3346, 3347t Kenya baboons, 3345t Macaque monkeys, 3344t mice, 3343t pentavalent, 3350–3354

I-70

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Mammalian tissues (Contd.) rats, 3341t–3342t skeletal fraction, 3346–3349, 3348f soft tissues, 3349–350 tetravalent, 3350–3354 trivalent, 3345–3350 tissue deposition kinetics, 3387–3395 in mice, 3388–3395, 3389f–3392f, 3394t in rats, 3387–3388 transport in body fluids, 3356–3367 extracellular fluid circulation, 3357–3359 loose connective tissue, 3359 plasma and tissue fluid composition, 3356–3357, 3357t–3358t plasma distribution of, 3357t–3358t, 3359–3361 Manganese plutonium melting point and, 897 protactinium separation from, 188 sorption studies of, 3176–3177 with thorium sulfates, 105 Manganese dioxide, for uranium leaching, 305 Manganite, plutonium (VI) reactions with, 3176–3177 Many-body perturbation theory (MBPT), for relativistic correlation effects, 1670 Marecottite, uranium sulfates in, 292 Marine organisms, actinide elements in, 1809 Marthozite, as uranyl selenite, 298 Mass spectrometry of berkelium, 1455–1457, 1457f, 1484 of californium, 1560 historical development of, 3309–3310 of neptunium, 788–790 of protactinium and thorium, 231 radiometric techniques v., 3309 techniques for, 3310 for trace analysis, 3309–3328 AMS, 3315–3319 ICPMS, 3322–3328 RIMS, 3319–3322 TIMS, 3311–3315 of uranium, 636–637 for uranium–235, 255 Mass spectrometry time-of-flight, of californium, 1560 Mass spectroscopy, for actinide element study, 14 Matrix elements of absorption intensity calculations, 2089–2090 Judd-Ofelt theory computation of, 2090–2091 Matrix-isolated actinide elements, 1967–1991 binary carbonyls, 1984–1987 carbide oxides, 1976–1984 description of, 1968 developments of, 1969

dioxides, 1970–1976 nitride-oxides, 1989–1991 nitrides, 1987–1989 overview of, 1968–1970 MBES. See Mo¨ssbauer emission spectroscopy MBPT. See Many-body perturbation theory MCDF. See Multi-configuration Dirac-Fock MC-ICPMS. See Multicollector inductively coupled plasma mass spectrometry MD calculations. See Molecular dynamics calculations Mechanical hardening, of plutonium, 981 Mechanical properties of alloys, 972–973 of californium, 1525–1526 of plutonium, metal and intermetallic compounds of, 968–973 of uranium metal, 322–323, 323t Medical applications of actinide elements, 1828–1829 of californium, 1502 californium–252, 1505–1507 of curium, 1398–1400 Meitnerium chemical methods for, 1720–1721 chemical properties of, 1717–1721 discovery of, 6t, 1653, 1653t electronic structures of, 1682–1684 half-life of, 1661 isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, 1720 in aqueous solution, 1774–1776, 1775t production of, 1720 relativistic orbital energies for, 1669f solution chemistry of complexation of, 1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f Meitnerium–268, half-life of, 1661, 1717 Meitnerium–271 half-life of, 1718 production of, 1717–1718 Melt refining historical development of, 2708 under molten salts, 2709–2710 oxide slagging in, 2709 process for, 2708–2709 Melting behavior, of plutonium oxides, 1045 with uranium oxides, 1074–1075, 1075f Melting point of actinide dioxides, 2139, 2139f of berkelium, sesquioxide, 1467 of californium, metal, 1522 of einsteinium, metal, 1592 mechanical properties and, 968

Subject Index

I-71

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Mendelevium, 1630–1636 atomic properties, 1633–1634, 1634t chemical properties of, 1635–1636, 1646t discovery of, 5t, 13 half-life of, 1630–1631, 1631t isotopes, 1630–1631, 1631t lanthanide elements v., 2 metallic state of, 1634–1635 oxidation states of, 2526 in aqueous solution, 1774–1776, 1775t preparation and purification, 1631–1633 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f solution chemistry, 1635–1636 synthesis of, 13 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t Mendelevium (III), hydration of, 2528–2530, 2529f, 2529t Mendelevium–256 importance of, 1630–1631 production of, 1631 Mendelevium–258, half-life of, 1630, 1631t Mercury americium interaction with, 1302 element 112 v., 1720–1721 element 164 v., 1732 Mesothorium II. See Actinium–228 Metabolic effects, of berkelium, 1445 Metallic conduction with thorium boride, 67 with thorium hydride, 64 Metallic radii of actinides, 2313 of americium, 1295 of californium, 1527 of lawrencium, 1644 of plutonium, 886, 887t Metallic state. See also Actinide metals 5f-electron phenomena in, 2307–2373 basic properties, 2313–2328 cohesion properties, 2368–2371 general observations, 2328–2333 magnetism, 2353–2368 overview of, 2309–2313 strong correlations, 2341–2350 strongly hybridized, 2333–2339 superconductivity, 2350–2353 weak correlations, 2339–2341 of actinide elements, 1–2, 964, 1591–1592, 1591t, 1784–1790 crystal structure, 1785–1787, 1786t electronic structures, 1788–1789, 1789f

polymorphic transformation, 1787 preparation, 1784–1785 properties of, 1786t superconductivity, 1789–1790 of actinium, 34–35 of americium, 1297–1302 phases of, 1297–1299 preparation of, 1297 properties of, 1297–1302, 1298t, 1301f structure of, 1300 of berkelium, 1457–1462 chemical properties, 1460–1461 physical properties, 1458–1460 preparation of, 1457–1458 theoretical treatment, 1461 of californium, 1517–1527 chemical and mechanical properties of, 1525–1526 physical properties of, 1519–1525 preparation of, 1517–1519 theoretical treatments of, 1526–1527 of curium, 1410–1412 chemical properties of, 1412 physical properties of, 1410–1411, 1413t–1415t preparation of, 1411–1412 of einsteinium, 1588–1594, 1591t alloys of, 1592–1593 other actinide metals v., 1591–1592, 1591t problems of, 1588 production of, 1590, 1593–1594 properties of, 1590–1591, 1591t thermodynamic properties of, 1592–1593 of element 164, 1732 of fermium, 1626–1628 of lawrencium, 1644 magnetic studies of, 2238 of mendelevium, 1634–1635 of neptunium, 717–721 history of, 717 lattice parameters, 719 production of, 717–718 properties of, 718 thermodynamic properties of, 718–719 of nobelium, 1639 of plutonium, 862–987 applications of, 862, 996, 996f corrosion kinetics of, 3223–3238 electronic structure, theory, and modeling, 921–935 hazards of, 3202, 3256–3257 history of, 862 mechanical properties, 968–973 nature of, 863 oxidation and corrosion, 973–979, 3226f, 3227–3235, 3227t, 3229t physical and thermodynamic properties of, 935–968

I-72

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Metallic state (Contd.) preparation of, 863–864, 995–996, 996f pyrochemical preparation and refining, 865–877 safe storage, 3260–3262, 3261f strength of, 968, 969f of protactinium, 191–194 physical parameters of, 191–194, 193t preparation of, 191 of thorium, 60–63 of uranium, 318–328 chemical properties of, 327–328, 327t corrosion kinetics, 3239–3246 electrical properties, 324, 324f, 324t general properties of, 321–323, 322t hazards of, 3202 intermetallic compounds and alloys, 325–326, 325t magnetic susceptibility, 323–324 physical properties of, 320–321, 321f preparation of, 318–324, 320f safe storage, 3262 Metallothermic process, for uranium metal preparation, 319, 320f Metal-metal interaction, in bimetallic complexes, 2891–2892, 2893f Metal-metal processes, of pyrochemical methods, 2708–2709 Metamagnetism, of neptunyl, 2255t, 2257 Metamictization, of uraninite, 275 Metathesis, of cyclopentadienyl complexes, 2819 Methane, radiolytic formation of, 3246–3247 Methyltrioctylammonium chloride. See Aliquat 336 MHW-RTGs. See Multihundred Watt Radioisotope Thermoelectric Generators MIBK, lawrencium extraction with, 1645 Mice initial distribution in, 3343t tissue deposition kinetics in, 3388–3395, 3389f–3392f, 3394t Microcracking, of plutonium, 890 Microsegregation, in plutonium gallium alloy, 899, 916–917, 916f–917f Micro-XANES. See Micro-X-ray absorption near-edge structure spectroscopy Micro-XAS. See Micro-X-ray absorption spectroscopy Micro-X-ray absorption near-edge structure spectroscopy (Micro-XANES), of solid samples, sorption studies of, 3174 Micro-X-ray absorption spectroscopy (Micro-XAS), of solid samples, sorption studies of, 3172–3173 MIK, protactinium extraction with, 188 Military purposes, plutonium for, 4

Mineralogy, of uranium, 257, 259t–269t, 270–273 Minerals, with uranium, 259t–269t, 274–275 bonding in, 280–281 crystal morphology prediction, 286–287 geometry of, 281–282, 284f–285f Mixed oxide fuel (MOX) DDP for, 2692–2693, 2707–2708 production of, 1070 transmutation with, 1812 MO levels. See Molecular orbital levels Moctezumite, as uranyl tellurite, 298 Molecular dynamics (MD) calculations, on thorium ion, 1991 Molecular orbital (MO) levels of actinocene, 1949 excited-state energies with, 1910 in HF calculations, 1902 seaborgium predictions of, 1707 of thorium carbonyl, 1986, 1988f in transactinide elements, 1677, 1677f of U2, 1994, 1995f of uranium molecules, 1969–1970, 1970f Molecular volumes, for actinide sesquioxides, 1535–1536, 1539f Møller-Plesset perturbation theory fourth-order (MP4), in HF calculations, 1902 Møller-Plesset perturbation theory secondorder (MP2), in HF calculations, 1902 Molten metal-salt extraction Argonne salt transport process, 2710–2712, 2712f other applications, 2712 Molten salt breeder reactor (MSBR), molten salt-metal extraction at, 2712 Molten salt extraction (MSE) for plutonium metal production, 868f, 869–870 use of, 2692 Molten salts actinide ions in, thermodynamic properties of, 2133–2135, 2134t, 2135f for pyrochemical processes, 2692 Molybdates of americium, 1321 in pyrochemical methods, 2702–2703 of thorium, 111–112 with alkali metals, 112 structure of, 111–112 synthesis of, 111 tungstates v., 113 of uranium, 266t natural occurrence of, 299 uranium (IV), 275 Molybdenum in uranium amine extraction, 312 in uranium intermetallic compound, 326, 326f

Subject Index

I-73

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Monazite processing of, 56–58, 57f–59f thorium in, 56t Monocarbides, structural chemistry of, 2406t, 2407 Mono-cyclopentadienyl complexes, structural chemistry of, 2482–2485, 2484t, 2485f–2487f Monohalides, thermodynamic properties of, 2178–2179, 2180t–2181t, 2181f gaseous, 2179 solid, 2178–2179 Monopicolinates, structural chemistry of, 2439t–2440t Monoxides dissociative energy of, 2149–2150, 2150f thermodynamic properties of, 2147 Monte Carlo program for bohrium study, 1711–1712 for hassium study, 1713–1715 for isothermal chromatographic systems, 1665 for rutherfordium study, 1693 Montmorillonite thorium complexes, 3156–3157 uranium complexes on, 301–302 uranyl-loaded, 3155–3156 Mo¨ssbauer absorption spectroscopy (MBAS), for environmental actinides, 3034t, 3043 Mo¨ssbauer effect of neptunium–237, 792 of protactinium, 190–192 Mo¨ssbauer emission spectroscopy (MBES), for environmental actinides, 3026t, 3028 Mo¨ssbauer spectroscopy of americium, 1297 of neptunium–237, 792–793 neutron scattering v., 2232 of plutonium, 861–862 Mourite, uranium molybdates in, 301 MOX. See Mixed oxide fuel MP2. See Møller-Plesset perturbation theory second-order MP4. See Møller-Plesset perturbation theory fourth-order MPE resin. See Magnetic polyamineepichlorohydrin resin MSE. See Molten salt extraction Multicollector inductively coupled plasma mass spectrometry (MC-ICPMS), 3326–3327 RNAA v., 3329 Multi-configuration Dirac-Fock (MCDF) for electronic structure calculation, 1670 of rutherfordium, 1692–1693

Multihundred Watt Radioisotope Thermoelectric Generators (MHWRTGs), plutonium-238 in, 818, 818f NAA. See Neutron activation analysis Natural occurrence of actinide elements, 1755–1756, 1804–1805, 3014–3016, 3273, 3274t–3275t, 3276 of actinium, 26–27 actinium-227, 26–27 uranium v., 162 of bijvoetite, 290 of brannerite, 280 of carnotite, 297–298 of coffinite, 275–276 of neptunium, 703–704, 1804 neptunium-237, 782–783, 1756 neptunium-239, 704, 1756 of parsonsite, 297 of pitchblende, 1804–1805 of plutonium, 822–824, 823t, 1804, 3016 plutonium-239, 822–824, 823t, 1756 plutonium-244, 822, 824 of protactinium, 161, 231 protactinium-231, 170 protactinium-233, 171 of pyrochlore, 279 of sale´eite, 293 of thorite, 275–276 of thorium, 133, 1804 thorium-232, 3273, 3276 of transactinide elements, 1661, 1755–1756 of uranium, 170, 255, 256t, 257–302, 1804 arsenates, 293 in calcite, 3163 carbonates, 291 molybdates, 299 phosphates, 293 selenites, 298 silicates, 292 uranium-234, 255, 256t uranium-235, 26–27, 170, 255–256, 256t, 3273, 3276 uranium-238, 255, 256t, 3273, 3276 of uranophane, 292 of zirconolite, 277–278 Natural uranium, description of, 1755 NCP. See Neocupferron NCRW. See Neutralized cladding removal waste Near-infrared and visible spectroscopy (NIR-VIS), for environmental actinides, 3034t, 3035 Nebulizers, for ICPMS, 3323 Neocupferron (NCP), protactinium extraction with, 184 Neodymium, in pitchblende, 1804

I-74

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Neodymium tris-cyclopentadienyl, magnetic susceptibility of, 2259, 2259t Neodynium (III), hydration numbers of, 2534, 2535t Neptunium, 699–795 analytical chemistry and spectroscopic techniques, 782–795 electrochemical methods, 790–792 luminescence methods, 787–788 mass spectrometry, 788–790 miscellaneous methods, 793–795 Mo¨ssbauer spectroscopy, 792–793 radiometric methods, 782–786 spectrophotometric methods, 786–787 XRF, 788 in aqueous solution, 752–770 control of oxidation states, 759–763, 760t diproportionation of neptunium dioxide, 759 electrolytic behavior, 755–759 hydrolysis behavior, 766–770 optical spectroscopy, 763–766 oxidation states of ions, 752–763 in biological systems in bone, 1817 health hazard of, 1814 in liver, 1815–1816 in organs, 1815 complexes of cyclopentadienyl, 2803 mono-cyclopentadienyl, 2482–2485, 2484t, 2485f tetrakis-cyclopentadienyl, 2814–2815 compounds of, 721–752 antimonides, 743–744 arsenides, 743 bismuthides, 744 bromides, 737–738 carbides, 744 carbonates, 745 chalcogenides, 739–742 chlorides, 736–737 coordination, 745–750, 746t–747t fluorides and complexes, 730–736, 735t–736t halides, 730–739, 731t hydrides, 722–724 hydrocarbyl, 752 hydroxides, 724–730 iodides, 738 nitrides, 742–743 nonstoichiometric, 1797–1798 organometallic, 750–752 overview of, 721–722 oxides, 724–730 oxychlorides, 738 oxyfluorides, 734–736, 736t oxyhalides, 738

oxyiodides, 738 oxyselenides, 741 oxysulfides, 740 oxytellurides, 741–742 phosphates, 744–745 phosphides, 743 pnictides, 742–744 selenides, 740–741 sulfates, 745 sulfides, 739–740 tellurides, 741–742 coordination complexes in solution, 771–782 inorganic ligands, 771, 772t–775t, 781 organic ligands, 776t–780t, 781–782 d transition elements v., 2 discovery of, 4, 5t, 699–700 history of, 4, 699–700 ionization potentials of, 1874t, 1875 isotopes of, 9–10, 12, 700–702, 701t production of, 702–704 laser spectroscopy of, 1873 magnetic properties of, 2356–2357 metallic state of, 717–721 alloys and intermetallic compounds, 719–721 metal, 717–719 structure of, 2385–2386 natural occurrence of, 703–704, 1756, 1804 in marine organisms, 1809 nuclear properties of, 700–702 oxidation states of, 2526–2527 in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t partitioning of, in HLW, 712–713, 2756–2757 as plutonium α- and β-phase stabilizer, 897 in plutonium alloy, americium v., 931, 931f plutonium and δ-phase plutonium influence of, 985 from plutonium decay, 985, 985f pyrochemical methods for, molten chlorides, 2697–2698 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f, 2525, 2525f in RTILs, 2689 separation and purification, 704–717 biotechnology, 717 chromatography, 714–716 coprecipitation, 716 electrodeposition, 717 solvent extraction, 705–713, 706f–708f, 709t studies on, 11 synthesis of, 4 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t

Subject Index

I-75

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f Neptunium (III) in acidic media, 753 chlorides of, magnetic data, 2229–2230, 2230t coordination compounds of, 745, 746t–747t cyclooctatetraene, 751–752 cyclopentadienyl, 750 halide complexes of, 739 hydrolytic behavior of, 768, 2546, 2548t magnetic properties of, 2261–2262 with pyrochemical processes, 2697–2698 redox behavior of, Nernst plot for, 3099f, 3100, 3108 speciation of, 3111t–3112t, 3116–3117 Neptunium (IV) absorption spectra of, 764–766 in acidic media, 753 carboxylates, EXAFS investigations of, 3137–3140, 3147t–3150t coordination complexes of, 745, 746t–747t, 748 preparation of, 745, 748 separation of, 748 coulometry for, 791 cyclooctatetraene, 751 cyclopentadienyl, 750–751 energy level of, 2067 equilibrium constants of, 771, 772t–775t, 781 fluoro complexes of, 734, 735t halide complexes of, 739 hydration of, 2531 hydrolytic behavior of, 768–769 hydroxide, synthesis of, 727–728 isomer shift of, 793–794, 794f magnetic properties of, 2257–2261 in mammalian tissues circulation clearance of, 3368–3369, 3368f–3375f, 3377 initial distribution, 3342t, 3352 transferrin binding to, 3365 with pyrochemical processes, 2697–2698 redox behavior of, Nernst plot for, 3099f, 3100, 3108 reduction of, 762 by americium (V), 1336 to neptunium (III), 745 speciation of, 3106–3108, 3111t–3112t, 3135–3136 Neptunium (V) absorption spectra of, 764–765 in acidic media, 753 adsorption, Pseudomonas fluorescens, 3182

coordination complexes of, 746t–747t, 748–749 cation-cation interaction in, 748 preparation of, 748–749 properties of, 748–749 detection of limits to, 3071t RAMS, 3035, 3036f VOL, 3061 equilibrium constants of, 771, 772t–780t, 781–782 fluoro complexes of, 734, 735t halide complexes of, 739 hydrolytic behavior of, 727, 769–770 in hydrosphere, 1807–1810 hydroxide, synthesis of, 727 isomer shift of, 793–794, 794f magnetic properties of, 2247–2257 mobility of, 1814 Mo¨ssbauer spectroscopy of, 793 oxidation of, 762 polarography for, 791–792 with pyrochemical processes, 2697–2698 redox potential of, 756–757 reduction of, 762 by americium (V), 1336–1337 separation of, HDEHP for, 2651, 2651f speciation with XAFS, 795 Neptunium (VI) absorption spectra of, 764 in acidic media, 753 coordination complexes of, 746t–747t, 749 coulometry for, 791 detection of RAMS, 3035 VOL, 3061 equilibrium constants of, 771, 772t–775t, 781 fluoro complexes of, 734, 735t halide complexes of, 739 hydrolytic behavior of, 770 hydroxide, synthesis of, 727 infrared spectra of, 764 isomer shift of, 793–794, 794f magnetic properties of, 2240–2247 oxidation of, 761–762 redox potential of, 756–757 reduction kinetics of, 760–761 separation of, PUREX process, 2732 speciation of, 3111t–3112t, 3124–3125 Neptunium (VII) absorption spectra of, 764 coordination complexes of, 746t–747t, 749–750 preparation of, 749–750 properties of, 749–750 detection of, NMR, 3033 fluoro complexes of, 734, 735t

I-76

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Neptunium (VII) (Contd.) hydrolytic behavior of, 770 hydroxide, synthesis of, 726–727 infrared spectra of, 764 isomer shift of, 793–794, 794f in solution, 1933 speciation of, 3111t–3112t, 3124–3125 Neptunium carbide entropy of, 2196, 2197t formation enthalpy of, 2195–2196, 2197t high-temperature properties of, 2198, 2198f, 2199t Neptunium carbonates, structural chemistry of, 2426–2427, 2427t Neptunium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Neptunium dioxide crystal structure of, 2287–2288, 2287f enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 in gas-phase, 2148–2149, 2148t heat capacity of, 2138–2141, 2139f, 2142t, 2272–2273, 2273f magnetic properties of, 2236–2237, 2237f, 2282–2288 magnetic susceptibility of, 2283 neptunium hexafluoride from, 732–733 neutron scattering of, 2284–2286, 2285f–2286f phase diagram of, 724–725, 725f RXS of, 2288 scattering experiments of, 2236–2237, 2237f stability of, 725–726 structure of, 2394 synthesis of, 725 Neptunium disulfide preparation of, 739 properties of, 739–740 Neptunium hexafluoride chemical behavior of, 733 crystal structure of, 731t energy level analysis of, 2083–2085, 2083t, 2085f lattice parameters of, 731t, 732 magnetic susceptibility of, 2243 physical properties of, 733 preparation of, 732–734 structural chemistry of, 2419, 2421, 2421t studies of, 1938 thermodynamic properties of, 2160–2161, 2160t, 2162t–2164t Neptunium hydrides entropy of, 2188, 2189t formation enthalpy of, 2187–2188, 2187t, 2189t, 2190f

high-temperature properties of, 2188–2190, 2190t structure of, 2403–2404 Neptunium monophosphide, 743 Neptunium monoxide dissociative energy of, 2149–2150, 2150f in gas-phase, 2148–2149, 2148t structure of, 2394 Neptunium nitride, 742–743 preparation of, 742–743 properties of, 743 Neptunium oxides structure of, 2394 thermodynamic properties of, 2136, 2136t Neptunium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Neptunium pentafluoride, structural chemistry of, 2416, 2419, 2420t crystal structure of, 731t preparation of, 731–732 Neptunium pentahalides, structural chemistry of, 2416, 2419, 2420t Neptunium pentaoxide, synthesis of, 726 Neptunium pentasulfide preparation of, 740 properties of, 740 Neptunium phosphates, structural chemistry of, 2430–2433, 2431t–2432t Neptunium pnictides, structure of, 2409–2414, 2410t–2411t Neptunium series (4n þ 1), 24f actinium–225 in, 20, 24f in nature, 27 thorium–229 from, 53 Neptunium sesquioxide, formation enthalpy of, 2143–2146, 2144t, 2145f Neptunium sulfates, structural chemistry of, 2433–2436, 2434t Neptunium tetrabromide, preparation of, 737 Neptunium tetrachloride identification of, 737 magnetic properties of, 2258t, 2260–2261 oxychloride preparation from, 738 preparation of, 736 properties of, 736–737 Neptunium tetrafluoride absorption spectra of, 2068, 2070f crystal structure of, 731t preparation of, 730–731 thermodynamic properties of, 2165–2169, 2166t Neptunium tetrahalides, structural chemistry of, 2416, 2418t Neptunium tribromide, preparation of, 737–738 Neptunium trichloride oxychloride preparation from, 738 preparation of, 737

Subject Index

I-77

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Neptunium trifluoride crystal structure of, 731t preparation of, 730 Neptunium trihalides, structural chemistry of, 2416, 2417t Neptunium triiodide, preparation of, 738 Neptunium trisulfide preparation of, 740 properties of, 740 Neptunium–235 stability of, 702 synthesis of, 702–703 Neptunium–236 stability of, 702 synthesis of, 702–703 Neptunium–237 absorption cross section of, 2233 from americium-241, 1828 detection of AMS, 3062–3063 γS, 3302 ICPMS, 3327–3328 limits to, 3071t MBAS, 3043 MBES, 3028 NAA, 3055–3057, 3056t, 3058f NMR, 3033 PCNAA, 3307 αS, 3294–3295 TIMS, 3314–3315 determination of, 705, 706f, 783–785 with ICPMS, 789, 790f DIDPA extraction of, 1276 environmental hazards of, 1807 half-life of, 700, 703 mo¨ssbauer spectroscopy of, 793 natural occurrence of, 704, 782–783, 1756 from neutron irradiation, 1756–1757 nuclear properties of, 3277t plutonium–236 and 238 from, 703, 817, 1758 from plutonium-241, 705, 706f, 783–785 protactinium-233 from, 171 significance of, 700 SIMS of, 788–789 synthesis of, 701–703 toxicity of, 1820 Neptunium–238 half-life of, 702 nuclear properties of, 3277t Neptunium–239 detection of, INAA, 3304–3305 determination of, 784 half-life of, 702 natural occurrence of, 704, 1756 nuclear properties of, 3277t SIMS of, 788–789 synthesis of, 702

from uranium–238, 702, 704 from uranium–239, 255 Neptunocene properties of, 1946–1948 structure of, 2486, 2488t Neptunyl (V) disproportionation of, 759 speciation of, 3111t–3112t, 3121–3122, 3133–3134 stability constants of, 2571, 2572f Neptunyl (VI), speciation of, 3111t–3112t, 3122–3123 Neptunyl ion aqueous solution absorption spectra of, 2080, 2081f charge-transfer transition of, 2089 complexes of porphyrins and phthalocyanines, 2464t, 2465–2466, 2466f–2467f structure of, 2400–2402 complexes with, 1923 crown ether complex of, 2449t, 2450 in DDP, 2706 formates of, 2257 hydration number of, 2531, 2533t hydrolytic behavior of, 2553 ligands for, 3422–3423 magnetic properties of, 2240–2247, 2255t in mammalian tissues bone, 3404 circulation clearance of, 3368–3369, 3368f–3375f, 3377, 3384–3386 initial distribution, 3342t–3344t, 3355–3356 transferrin binding to, 3364 reduction of, 2591 stability constants of, 2576, 2576f study of, 1931, 1933 Nernst analysis of berkelium (IV) and (III), 3108 of neptunium (IV) and (III), 3108 Nernst equation, for aqueous actinide elements, 3097–3098 Nernst plot for aqueous actinide elements, 3099, 3099f of neptunium, 3099, 3099f, 3108 Network structures, factors in, 579 Neutralized cladding removal waste (NCRW), TRUEX process for, 2740 Neutron activation analysis (NAA) for berkelium, 1484 californium-252 for, 1828 for environmental actinides, 3055–3057, 3056t, 3058f fundamentals of, 3302–3303 INNA, 3303–3305 for neptunium, 785–786, 789 RNNA, 3305–3307

I-78

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Neutron activation analysis (NAA) (Contd.) for trace analysis, 3302–3307 for uranium, 635–636 Neutron capture in actinide elements, 1828 berkelium, 1444 curium curium–244, 1400 production of, 1400 einsteinium from, 1582 plutonium isotope formation, 825–826, 825f plutonium–239 formation with, 823–824 Neutron crystallography, for electronic structure, 1770 Neutron diffraction for coordination geometry study, 602–603 description of, 2383 for hydration study, 2528 sources for, 2383 for structural chemistry, 2383–2384 types of, 2383–2384 X-ray diffraction v., 2383 Neutron emissions from actinide elements, 1827–1828 actinium for, 43 californium–252 for, 1505–1507, 1506t californium–254 for, 1505, 1506t curium–248 for, 1505, 1506t Neutron irradiation for actinide and transactinide element production, 1756–1761, 1761t actinium from, 1756 of americium, 1268 of californium–252, 1507 neptunium from, 1757 in nuclear power, 1826–1827 of plutonium, 1757 protactinium from, 1756 for SNF transmutation, 1811–1812 of uranium, 3–4, 1756–1757 Neutron scattering for actinide element study, 14 advantages of, 2232–2233 disadvantages of, 2233–2234 history of, 2232 magnetic dipole moment and, 2232 of neptunium dioxide, 2284–2286, 2285f–2286f RXS v., sample size, 2237–2238 of uranium dioxide, 2274, 2285–2286, 2286f tetrachloride, 2248, 2250f x-ray scattering v., sample size, 2233–2234 Neutron spectroscopy (NS), for environmental actinides, 3026t, 3029

Neutrons in actinide synthesis, 3–4, 8–9 thermonuclear device production of, 9 NFL. See Non-Fermi liquid Nickel, plutonium melting point and, 897 Ningyoite, uranium in, 259t–269t, 275 Niobates, of uranium, uranium (IV), 277–280 Niobium foil, berkelium adsorption on, 1451 Niobium, protactinium purification from, 178–186 ion exchange, 180–181, 180f precipitation and crystallization, 178–186 solvent extraction and extraction chromatography, 181–186, 183f NIR-VIS. See Near-infrared and visible spectroscopy Nitrate solution, radiolysis of plutonium in, 1144–1145 Nitrates of actinide elements, 1796 of actinyl complexes, 1927, 1928t, 1929f complexes of, 2581 of curium, 1413t–1415t, 1422 of neptunium, equilibrium constants for, 773t of plutonium, 1167–1168 of protactinium (V), 212–213, 214t in pyrochemical methods, 2704 structural chemistry of, 2428–2430, 2429f of thorium, 106–108, 107f extraction of, 107–108 properties of, 106–107 structure of, 106, 107f synthesis of, 106 ternary, 108 Nitric acid actinide stripping with, 1280 berkelium, extraction in, 1448–1449 curium extraction in, 1407 separation in, 1409, 1434 dubnium, extraction in, 1703–1704 mendelevium extraction with, 1633 neptunium absorption spectra in, 764 extraction from, 706–708, 708f nobelium extraction with, 1640 plutonium processing in, 836 anion-exchange chromatography, 848–849 PUREX process, 841 reduction and oxidation reactions, 1139–1140 seaborgium, study in, 1710–1711 TRPO actinide extraction in, 2752–2753 uranates (V) and (IV) dissolution in, 381–382 uranium compound dissolution in, 632

Subject Index

I-79

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 metal reactions with, 328 oxide reactions with, 370–371 Nitride oxides, of actinides, 1989–1991 Nitride-nitride process, 2723–2725 actinide nitride recovery, 2724–2725 dissolution step, 2724 historical development of, 2723–2724 Nitrides of actinides, 1987–1989 of americium, 1317–1319 of neptunium, 742–743 of plutonium, 1017–1021, 3212–3213 phase diagram, 1017, 1017f preparation of, 1018 properties of, 1019, 1021t reactions of, 3222–3223 structure of, 1019, 1020t thermodynamic properties of, 2200–2203 enthalpy of formation, 2197t, 2200–2201, 2201f entropy, 2197t, 2201–2202 high-temperature properties, 2199t, 2202 of thorium, 97–99, 98t, 99f, 1989 halide reaction with, 98–99 lattice constant of, 99 preparation of, 97–98 structure of, 98–99 of uranium, 407–411, 408t–409t, 411f, 1988–1989, 3215 bromides, 497, 500 chlorides, 500 fluorides, 489–490 iodides, 499–500 phases, 407, 410, 411f preparation of, 410 properties of, 408t–409t stability of, 410 structure of, 410–411 Nitrilotriacetate (NTA) plutonium complex with, 1176–1177, 1178t, 1181 separation with, 2640–2641 Nitrogen americium ligands of, 1363 plutonium hydrides reaction with, 3217–3218 uranium metal reactions with, 327–328, 327t Nitrohalides, thermodynamic properties of, 2182–2185, 2187t NMR. See Nuclear magnetic resonance Nobelium, 1636–1641 atomic properties, 1634t, 1639 chemical properties of, 1640–1641, 1646t in curium complex, 1413t–1415t, 1422 discovery of, 5t, 13 dubnium v., 1703–1706 half-life of, 1637, 1638t isotopes, 1637, 1638t

lanthanide elements v., 2 metallic state of, 1639 oxidation states of, 2525–2526 in aqueous solution, 1774–1776, 1775t preparation and purification, 1638–1639 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f solution chemistry, 1639–1641 synthesis of, 13 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t Nobelium–253, x-ray emission of, 1634t, 1639 Nobelium–255 cation-exchange and coprecipitation experiments, 1639–1640 production of, 1637–1639 Nobelium–257, from rutherfordium–261, 1698 Nobelium–259, half-life of, 1637 Noble metals in intermetallic compounds of uranium, 325–326 reductive extraction of, 2717–2719 Nonaqueous separation methods overview of, 853 for plutonium, 853–857 combination processes, 856–857 halide volatility processes, 855 pyrochemical, 853–854 RTILs, 854 supercritical fluid extraction, 855–856 Non-Fermi liquid (NFL) description of, 2348 models for, 2349–2350 quantum critical point and, 2348–2350 Non-Kramers ion description of, 2228 uranium (IV), 2254 NRA. See Nuclear reaction analysis NS. See Neutron spectroscopy NTA. See Nitrilotriacetate Nuclear criticality, hazard of, 3255–3256 Nuclear energy. See also Thermoelectric generator actinide elements for, 1826–1827 californium–252 for, 1507 curium for, 1398–1400 decontamination after, 826, 828–830 environment and, 3013 fuels for, 826 plutonium for, 4, 813 carbides, 744 metals and intermetallic compounds, 862 nitrides, 1019, 1021t

I-80

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Nuclear energy (Contd.) oxides, 1023–1025 plutonium–239, 815, 820 uranium oxides with, 1070–1071 thorium for, 53 uranium for, 255 plutonium oxides with, 1070–1071 Nuclear fission. See also Nuclear energy of uranium discovery of, 255 uranium–235, 256 Nuclear ‘incineration,’ of SNF, 1811–1812 Nuclear magnetic moments, of californium, 1872 Nuclear magnetic resonance (NMR) for environmental actinides, 3033, 3034t for hydration study, 2528 for ligand exchange reactions, 607–608 intramolecular, 617, 617f organic and inorganic, 614–615 for magnetic susceptibility measurements, 2226 of neptunium, 766 of organometallic actinide compounds, 1800–1803 for structure study, 589 of thorium hydrides, 64 of uranium dioxide, 2280 of uranyl (V), 3121–3122 Nuclear properties of actinium, 20–26, 21f–26f, 22t–23t of americium, 1265–1267 of berkelium, 1445–1447 of curium, 1398–1400, 1399t of einsteinium, 1580–1583, 1581t of neptunium, 700–702 of plutonium, 815–822 of protactinium, 164–170 of superactinide elements, 1735–1737 alpha emission, 1735 of thorium, 53–55, 54t–55t of uranium, 255–257 Nuclear reaction analysis (NRA), for environmental actinides, 3059t, 3061 Nuclear spent fuel. See Spent nuclear fuel Nuclear spins, of californium, 1872 Nuclear systematics, development of, 10 Nuclear waste. See also Radioactive waste actinide chemistry for, 3 californium for, 1538 curium–244 in, 1759 disposal of, 1811–1813 in environment, 3013 hydride-dehydride or -oxidation process for, 996, 996f immobilization of brannerite for, 280

pyrochlore for, 278–279, 279f zirconolite for, 277–278 neptunium hydrated oxides and disposition of, 726 plutonium in iron and, 1138–1139 metal and intermetallic compounds, 862 oxides for, 1023–1024 phosphates for, 1170–1171 polymerization of, 1150 precipitation from, 2634 protactinium clean-up in, 189 scope of concern of, 3202 uranium predictions in, 270 Nuclear weapons. See also Thermonuclear device actinide chemistry for, 3 aging of, 979–980 environment and, 3013 hydride-dehydride or -oxidation process for, 996, 996f neptunium–237 in, 703 plutonium in, 813, 1757–1758 metal and intermetallic compounds, 862 testing of, 1805–1806 n-Octyl(phenyl)-N,N-diisobutyl-carbamoyl methylphosphine oxide (CMPO) actinide extraction with, 1769, 2738–2752 curium separation with, 1409, 1434 degradation, cleanup, and reusability of, 2747–2748 development of, 2652, 2655 extractant comparison with, 2763–2764, 2763t for extraction chromatography, 2748–2749 magnetically assisted chemical separation with, 2750–2752 neptunium extraction with, 707–708, 713 overview of, 2738 separation with, 2652 in SLM separation, 2749–2750, 2749f transuranium element recovery with, 1407–1408 in TRUEX process, 2739 in TRU•Spec, 3284 Oklo, Gabon pitchblende at, 1804–1805, 3016 plutonium–239 formation at, 824 uraninite at, 274 uranium deposits at, 271–272 Olefins, organoactinide complexes hydrogenation, 2996–2997 polymerization, 2997–2999 OLGA. See On-Line Gas Analyzer Oligonucleotides, uranyl ion for synthesis of, 631

Subject Index

I-81

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 One-atom-at-a-time chemistry challenges of, 1661–1662 chemical procedures of, 1662–1666 gas-phase chemistry, 1663–1665 overview of, 1662–1663 solution chemistry, 1665–1666 for element identification, 10 for mendelevium identification, 13 production methods and facilities required for, 1662, 1662t transactinide element study with, 1661–1666 for transactinides, 3 One-electron band model beyond, 2326 for actinide metals, 2324–2325 DFT with, 2326–2328 On-Line Gas Analyzer (OLGA) for bohrium study, 1711 for isothermal chromatographic systems, 1664, 1705 for rutherfordium study, 1693 for seaborgium study, 1707–1708, 1709f Optical properties of liquid plutonium, 963 of uranium dioxide, 2276–2278, 2277f Optical spectroscopy. See also Absorption spectra of actinide elements, 2013–2103 charge-transfer transitions and actinyl structures, 2085–2089 crystal-field interaction, 2036–2056 divalent, 2077–2079 free-ion interactions, 2020–2036 lanthanides v., 2016, 2017f penta- and hexavalent, 2079–2085, 2080t tetravalent, 2064–2076 trivalent, 2056–2064 of californium, californium (III), 2091, 2092f of fluorides, 2069–2070, 2069f–2070f free-ion interactions for, 2020–2036 of lanthanide elements, actinides v., 2016, 2017f of neptunium, 763–766 of organometallic actinide compounds, 1800 overview of, 2014 of protactinocene, 1951 of uranium, uranium (III), 2091, 2092f 4f Orbital free-ion parameters of, 2038, 2038t 5f orbital v., 1901, 2016, 2017f, 2062–2064, 2063f, 2353–2354 SIM of, 2343–2344 Wigner-Seitz radius of, 2310–2312, 2311f 5d Orbital electronic structures of, 1672–1673, 1672t

relativistic destabilization of, 1666, 1667f Wigner-Seitz radius of, 2310–2312, 2311f 5f Orbital in actinide metals, bonding, 2319 in actinides, 1–2, 10–11, 1770–1771, 1894–1895, 1896f, 1896t bonding of, 1898 contraction of, 1901 metallic state, 1787–1789 organometallic compounds, 1800–1803 role of, 1917–1918, 1918f superconductivity, 1789–1790 in americium, 1299–1301 in back-bonding, 576 in berkelium, 1445, 1456–1458, 1461, 1472–1473 in californium, 1526–1527, 1546, 1562–1563 in curium, stability of, 1402 in einsteinium, 1578–1579, 1586–1588 electronic excitations of, 2049–2050 electronic structure of, 2019–2020 free-ion energy levels of, 2014–2016, 2015f free-ion parameters of, 2038–2039, 2038t general observations of, 2329–2333 Hill plot, 2331–2333, 2332f low-symmetry structures, 2330–2331, 2331t narrow bands, 2329–2330, 2329f ground states of, 2042 hydrolytic behavior of, 3100 luminescence decay of, 2101–2102, 2101f lifetimes of, 2099–2100, 2099t, 2100f magnetic properties from, 719–720, 2353, 2356 metallic state and phenomena of, 2307–2373 basic properties, 2313–2328 cohesion properties, 2368–2371 general observations, 2328–2333 magnetism, 2353–2368 overview of, 2309–2313 strong correlations, 2341–2350 strongly hybridized, 2333–2339 superconductivity, 2350–2353 weak correlations, 2339–2341 4f orbital v., 1901, 2016, 2017f, 2062–2064, 2063f, 2353–2354 6d orbital v., 1901 in plutonium, 814, 921–925 in bonding, 1192, 1193f δ-phase, 925 ions, 1113–1114 α-phase, 924 in plutonium dioxide, 1196–1199, 1197f, 1200f in plutonium hexafluoride, 1194–1196, 1195f

I-82

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 5f Orbital (Contd.) in plutonocene, 1199–1203, 1201f–1202f qualitative representations of, 1193, 1194f relativistic effects on, 1898 SIM of, 2343–2344 strongly hybridized, 2333–2339 Fermi surface measurements, 2334 photoemission measurement background, 2334–2336 strong correlations, 2341–2350 UIr3 PES, 2336–2339, 2337f weak correlations, 2339–2341 in transactinide elements, 1654, 1659 unpaired electrons in, 1909–1910 in uranium bonding, 577 uranyl, 1915–1916 Wigner-Seitz radius of, 2310–2312, 2311f 6d Orbital as acceptor orbitals, 1901 in actinides, role of, 1917–1918, 1918f in cyclopentadienyl complexes, trivalent, 2803 electronic structures of, 1672–1673, 1672t ionization potentials of, 1673–1675, 1673t, 1674f 5f orbital v., 1901 relativistic destabilization of, 1666, 1667f in transactinide elements, 1659 7p Orbital filling of, 1722t, 1723, 1728 transactide contraction of, 3 in transactinide elements, 1659 7s Orbital filling of, 1722t, 1729 relativistic stabilization of, 1666, 1667f–1668f transactide contraction of, 3 8s Orbital filling of, 1722t, 1729 in transactinide elements, 1659 9p Orbital bonding of, 1732 filling of, 1733 9s Orbital bonding of, 1732 filling of, 1732–1733 f Orbital in actinide and lanthanide elements, 1894–1895, 1896f, 1896t angular momentum, 2041 crystal formation with, 2047–2048 energy levels and stability of, 2014–2016, 2015f free-ion interactions of, 2024, 2025t–2026t HF calculations of, 2032, 2034f, 2035 ionicity of bonding in, 2556, 2557f relativistic effects on, 1898 spin-orbit coupling on, 1949–1950

Orbital energies, of actinides v. lanthanides, 1898, 1899f 5g Orbital, filling of, 1722t, 1731 6f Orbital, filling of, 1722t, 1731 7d Orbital, filling of, 1732 8p Orbital, filling of, 1722t, 1730–1731 6p Orbital, in actinides, role of, 1917–1918, 1918f Orbital interaction diagram for actinocenes, 1945, 1946f for plutonium dioxide, 1197f, 1200f hexafluoride, 1195f for plutonocene, 1201f for uranyl (VI) ion, 577, 577f 4d Orbital, relativistic destabilization of, 1666, 1667f 5s Orbital, relativistic stabilization of, 1666, 1667f 6s Orbital, relativistic stabilization of, 1666, 1667f–1668f Ore thorium processing and separation from, 56–59 from monazite, 56–58 problems with, 58 from uraninite or uranothorianite, 58 uranium processing and separation from, 302–317 complexities of, 302–303 methods of, 302 pre-concentration, 303–304 recovery from leach solutions, 309–317 roasting or calcination, 304 Organic acids, EXAFS analyses in, 3137–3140 model systems, 3138–3139 natural systems, 3139–3140 Organic phases, for solvent extraction, 840–841 Organoactinide chemistry, 2799–2894 bimetallic complexes, 2889–2893 bond distance, 2893 bridging ligands, 2889 cyclopentadienyl complexes, 2890 metal-metal interaction, 2891–2892, 2893f metathesis reactions, 2889 overview of, 2889 phosphine groups, 2890 phospholyl ligand, 2890–2892, 2892f carbon-based ancillary ligands, 2800–2867 alkyl ligands, 2866–2867 allyl, pentadienyl and related ligands, 2865–2866 cyclooctatetraenyl complexes, 2851–2858 cyclopentadienyl complexes, 2800–2851 other carbocyclic ligands, 2858–2865

Subject Index

I-83

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 heteroatom-based ancillary ligands, 2876–2889 bis(trimethylsilyl)amide, 2876–2879 other, 2888–2889 pyrazolylborate, 2880–2886 tris(amidoamine), 2886–2888 heteroatom-containing ancillary ligands, 2868–2876 dicarbollide ligands, 2868–2869 other nitrogen-containing ligands, 2873–2876 phospholyl ligands, 2869–2871 pyrrole-based ligands, 2871–2873, 2873f–2874f neutral carbon-based donor ligands, 2893–2894 Organoactinide complexes. See also Organometallic compounds alkyne dimerization with, 2930–2947 promotion of, 2938–2947, 2940f–2941f terminal, 2930–2935 terminal ansa-, 2935–2937 alkyne hydroamination, 2981–2990 kinetic studies of, 2986–2990 neutral organoactinide complex promotion, 2981–2986 alkyne oligomerization, 2923–2930 amine, silane reactions, 2978–2981 azide and hydrazine reduction, 2994–2996 catalytic processes promoted by, 2911–3006 constrained-geometry hydroamination, 2990–2994 heterogeneous, 2999–3006 active site assessment, 3000–3002 alkane activation, 3002–3006 arene hydrogenation, 2999–3000 olefin hydrogenation, 2996–2997 olefin hydrosilylation, 2953–2978 of alkenes, 2969–2974 promotion for alkynes, 2974–2978 promotion for terminal alkynes, 2964–2969 of terminal alkynes, 2953–2964 olefin polymerization, 2997–2999 reactivity of, 2912–2923 activation modes, 2912–2913 alkyne and silane stoichiometric reactions of, 2916–2918, 2917f [(Et2N)3U][BPh4], 2922–2933 stoichiometric reactions of, 2913–2916, 2914f–2915f synthesis of ansa- complexes, 2918–2920, 2920f synthesis of high-valent organouranium complexes, 2920–2922, 2921f terminal alkyne cross dimerization, 2947–2952, 2948f–2949f

Organoimido complexes with bis(trimethylsilyl)amide, 2877–2879 with cyclopentadienyl, 2833–2835 with pentamethyl-cyclopentadienyl, 2916 Organometallic chemistry history of, 1942–1943 of plutonium, 1182–1191 pi-bonded ligands, 1188–1191 sigma-bonded ligands, 1182–1187 of uranium, 630–631 Organometallic compounds of actinide elements, 1800–1803, 1942–1967 actinocenes, 1943–1952 cyclopentadienyl complexes, 1952–1959 miscellaneous, 1965–1967 six- and seven-membered ring complexes, 1959–1962 uranium (III) complexes, 1962–1965 of berkelium, 1464t–1465t, 1471 of californium, 1541 in gas phase, 1560 of curium, 1413t–1415t, 1423–1424 of einsteinium, 1611 history of, 2467–2468 of lanthanides, 2468 of neptunium, 750–752 cyclooctatetraene, 751–752 cyclopentadienyl, 750–751 other, 752 overview of, 1800–1801 structural chemistry of, 2467–2497 cyclooctatetraene, 2485–2487, 2488t, 2489f cyclopentadienyl, 2468–2485 other, 2487–2491, 2490t–2491t, 2492f–2493f of uranium, magnetic properties of, 2252–2254 Organophosphorus esters, fermium complexes with, 1629 Organophosphorus ligands carboxylates v., 2585t–2586t, 2588 complexes of, 2585t–2586t, 2587–2590 Organophosporus extractants for americium, 1271–1284 carbamoylmethylenephosphine oxide, 1278–1284 DBBP, 1274 DIDPA, 1276 HDEHP, 1275–1276 TBP, 1271–1274 TRPO, 1274–1275 for berkelium, 1479 for curium, 1407 extraction properties of, 1283 for separation, 2651–2652, 2680–2682 Organothorium complexes active sites of, 3000–3002

I-84

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Organothorium complexes (Contd.) examples of, 116 study of, 117 Organouranium complexes azide and hydrazine catalytic reduction by, 2994–2996 high-valent synthesis of, 2920–2922, 2921f Orthophosphates of berkelium, 1470–1471 impurities in, 2058–2059 Orthosilicates, of uranium, 261t uranium (IV), 275–276 Oscillator strengths, of uranium chlorides, 447–448 halides, 442–443 Osmium, in hassium studies, 1712–1715, 1714f–1715f Outer sphere complexation, 2563–2566, 2566f, 2567t confusion over, 2564 conversion of, 2564–2565 description of, 2564 stability constant, 2565, 2566f thermodynamic data, 2566, 2567f Oxalates of actinide elements, 1796 of americium, 1322, 1323t of californium, 1546 of curium, 1413t–1415t, 1419, 1421–1422 of plutonium, 1173–1175 precipitation with, 836–837, 837 precipitation with, 2633–2634 structural chemistry of, 2441t–2443t, 2445–2446, 2445f of thorium, 114 as ligands, 131–132, 132t of uranium, 603–605, 604t Oxalic acid actinide stripping with, 1280 protactinium (V), 219 Oxidation of americium americium (II), 1337 americium (III), 1333–1335, 1333f americium (IV), 1334 of berkelium, 1460–1461, 1485 berkelium (III), 1448 of californium, 1526, 1546–1547 for cyclopentadienyl complexes, pentavalent, 2847 of neptunium neptunium (V), 762 neptunium (VI), 761–762 potential, 755 photochemical, of polydeoxynucleotides, 630–631 of plutonium by actinide ions, 1133–1137, 1134t–1135t

in air, 974, 975f of alloys, 975f, 976, 977t in aqueous solution, 1117–1146 metal and intermetallic compounds of, 3226f, 3227–3235, 3227t, 3229t moisture-enhanced, 974–976 by nonactinide ions, 1137–1143 preparation and stability of, 1125–1133 pyrophoricity, 975f, 976–977, 978f self-sustained, 3233–3235 of uranium carbonate leaching, 307–308 dioxide solid solutions, 394 processing, 305 self-sustained, 3245–3246 uranium (III), 598 by uranium hexafluoride, 562 Oxidation states of actinide cations, 2525–2527, 2525f of actinide elements, 1, 1774–1784 complex-ion formation, 1782–1784 hydrolysis and polymerization, 1778–1782 ion types, 1777–1778, 1777t, 1779f, 1780t ions in aqueous solutions, 1774–1776, 1775t of actinocenes, 1946–1948 of actinyl, 1928 of americium, 1324–1338, 2526 autoreduction, 1330–1331 disproportionation, 1331–1332 electrode potentials and thermodynamic properties, 1328–1330, 1329t hydration and coordination numbers, 1327, 1328f preparation of, 1325–1327 radiolysis, 1337–1338 redox kinetics, 1333–1337 of berkelium, 1472–1473 of californium, 1528, 1545, 1548, 1562, 2526 coordination number and bond distance with, 3093 of curium, 1416, 2526 of darmstadtium, 1720 determination of, 2725–2726 of dubnium, 1703–1704 of einsteinium, 1578, 2526 of element 112, 1720, 1724t of element 114, 1724t, 1727 of element 115, 1724t, 1727–1728 of element 116, 1724t, 1728 of element 117, 1724t, 1728 of element 118, 1724t, 1729 extraction for, 3287 of fermium, 2526 ionic radii and, 2558 of meitnerium, 1720 of mendelevium, 2526

Subject Index

I-85

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 of neptunium, 710, 710f, 724, 752–763, 2526–2527 control of, 759–763, 760t examples of, 752–753 redox potentials of, 753–755 stability of, 752 of nobelium, 2525–2526 of plutonium, 814, 1123–1125, 1124f–1125f, 1126t–1130t, 2525–2527, 2525f adjustment of, 849 equilibria, 1123–1125, 1124f–1125f, 1126t–1130t in separation of, 831–835 sorbed, 3175–3176 of protactinium, 161, 209, 2526 of roentgenium, 1720 of thorium, 117, 2526 of transactinide elements, stability of, 1673–1675, 1673t, 1674f–1675f of uranium, 257, 276–277, 328, 590, 1914–1915, 2526 in uraninite, 274–275 of uranyl, 1928 Oxide slagging, for plutonium reprocessing, 2709–2710 Oxide-metal processes, 2717–2721 actinide and rare earth separation, 2719, 2720t, 2721f actinide electrorecovery, 2719–2721 actinide recovery from HLLW, 2717 reductive extraction actinide and rare earth element, 2719 noble metals, 2717–2719 Oxide-oxide process, as pyrochemical method, 2704 Oxides of actinides, 1790, 1791t–1795t, 1796–1798 matrix-isolated, 1970–1976 of actinyl ions, 1932–1933, 1932t of americium, 1303, 1305t–1312t, 1313–1314 americium dioxide, 1303, 1313 coordination of, 1357–1358, 1358f phase relationships and thermodynamic data, 1303 of berkelium, 1464t–1465t, 1466–1467 of californium, 1530t–1531t, 1534–1538 behavior of, 1537–1538 complex, 1538 preparation of, 1534–1535 sesquioxide, 1535–1537, 1535f of curium, 1413t–1415t, 1419–1420 description of, 2388 of einsteinium, 1595–1599 of hassium, 1712–1715, 1714f–1715f magnetic properties of, 5f1 compounds, 2244, 2245t of neptunium, 724–730

dioxide, 725–726 hydrated, 726 pentaoxide, 726 phase diagram of, 724, 725f ternary, 728–730 of plutonium, 1023–1049, 3206–3212 applications of, 1023–1025 chemical properties, 1048–1049 container material compatibility, 1049 dioxide, 1031–1034 hazards of, 3202, 3257–3258, 3258t interface of, 976–977, 978f melting behavior, 1045 monoxide, 1028–1029 oxygen diffusion, 1044–1045 phase diagram, 1025, 1026f, 1039–1041, 1040f, 3206–3208, 3207f, 3211–3212, 3211f phase equilibria, 1025–1026, 1026f preparation of, 1028–1036, 3206–3207 reaction rates of, 3219–3222 safe storage, 3260–3262, 3261f sesquioxide, 1029–1031 solid-state structures, 1027t, 1036–1044, 1038f–1040f, 1042f–1043f ternary and quarternary, 1065–1069, 1066t–1067t ternary with actinides, 1070–1077 ternary with lanthanide oxides, 1069–1070 thermodynamic properties, 1047–1048, 1047t vaporization behavior, 1045–1047, 1046f of protactinium, 195–197 binary, 195, 196t polynary, 195–197, 197t of seaborgium, 1707, 1709 structural chemistry of, 2388–2399 actinium, 2390 americium, 2394–2396, 2396t berkelium, 2397–2398, 2398t californium, 2398–2399, 2398t curium, 2396–2397, 2396t einsteinium, 2399, 2399t history of, 2389 protactinium, 2391 thorium, 2390 uranium, 2391–2394, 2393f thermodynamic properties of, 2135–2157 with alkali metal ions, 2150–2153 with alkaline earth ions, 2153–2157 binary, 2135–2136, 2136t dioxides, 2136–2143 in gas phase, 2147–2150, 2148t, 2150f monoxides, 2147 sesquioxides, 2143–2147 ternary and quaternary oxides/oxysalts, 2157–2159t

I-86

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Oxides (Contd.) of thorium, 70, 75–76 as catalysts, 70, 76 properties of, 70, 75, 75t research of, 70 unit cell constants for, 2389, 2389t of uranium, 259t, 339–398, 3214–3215. See also Uranium oxides alkali and alkaline-earth metals, 371–383, 372t–378t binary, 339–371 bromides, 497, 527–528, 571–574 chlorides, 524–525 fluorides, 489–490, 564–567 geometric parameters of, 1973, 1974t halides, 456 hazards of, 3202 history of, 253–254 iodides, 499 safe storage, 3262 Oxide-water reaction, of plutonium, 3209–3210, 3209t Oxine, in thorium compounds, 115 Oxobromides, of uranium, 528 Oxochlorides, of uranium, 525–526 Oxoplutonates alkali metals, preparation of, 1056–1057 alkaline earth metals, preparation of, 1057–1059 solid state structures of, 1059–1064, 1060t–1061t double perovskites, 1062–1063, 1063f heptavalent, 1064 hexavalent, 1063–1064, 1064f perovskites, 1059–1062, 1062f Oxybromides, of berkelium, 1470 Oxychlorides of berkelium, 1470 of bohrium, 1711–1712, 1712f of californium, 1532 of neptunium, 738 of seaborgium, 1706–1707 of uranium, 494 Oxyfluorides, of neptunium, 734–736 preparation of, 734–736 properties of, 734, 736t Oxygen americium ligands of, 1361–1362 plutonium hydrides reaction with, 3216–3217 metal reaction with, 3225–3238 oxide generation of, 3250 in plutonium catalyzed corrosion, 3237 in uranium aqua ions, 592–593 carbonate leaching, 307–308 corrosion by, 3242–3245, 3243f, 3244t metal reactions with, 327–328, 327t

Oxygen diffusion in plutonium oxide, 1044–1045 of UO2, 367 Oxygen potential, of uranium oxides, 360–364, 361f–363f solid solutions, 394–398, 395t Oxyhalides of actinyl ions, 1939–1942, 1940t structures of, 1939–1941, 1940t, 1941f–1942f of californium, 1529–1534, 1530t–1531t, 1532f of dubnium, 1706 of neptunium, 738 of plutonium, 1100–1102 overview of, 1100 preparation and properties of, 1101–1102 solid-state structures, 1102, 1103f structural chemistry of, 2421–2424, 2422t, 2424t–2426t hexavalent, 2423, 2426t pentavalent, 2423, 2425t tetravalent, 2421, 2423, 2424t trivalent, 2421, 2422t thermodynamic properties of, 2182–2187, 2183t–2184t, 2186t–2187t Oxyhydroxides thermodynamic properties of, 2193–2195, 2194t of uranium, 259t–260t, 287 Oxyiodides of berkelium, 1470 of neptunium, 738 Oxyselenides, of neptunium, 741 Oxysulfates of berkelium, 1470 of californium, 1541 Oxysulfides of berkelium, 1470 of neptunium, 740 Oxytellurides, of neptunium, 741–742 PAA. See Phenylarsonic acid Pacemaker, plutonium–238 powered, 817, 1828–1829 Palladium, californium alloy with, 1518 PAM. See Periodic Anderson model Paramagnetic susceptibility measurements, for electronic structure, 1770 PARC process. See Partitioning Conundrum Key process Parsonsite natural occurrence of, 297 structure of, 295–296, 296f Particle-induced gamma emission spectroscopy (PIGE), for environmental actinides, 3059t, 3061

Subject Index

I-87

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Partition chromatography for actinide elements extraction, 1769 for actinium purification, 31–32 for SNF, 2728 Partitioning Conundrum Key process (PARC process), for americium extraction, 1272f, 1273 Passivated Ion-implanted Planar Silicon (PIPS) detectors, for seaborgium study, 1708 Paul Scherrer Institute (PSI) element 112 study at, 1721 rutherfordium production at, 1698 Pauli exclusion principle in actinide metals, 2320 description of, 2316–2317 Fermi-Dirac with, 2323 Pauli Hamiltonian, for electronic structure calculation, 1906 PCNAA. See Preconcentration neutron activation analysis PCS. See Photon correlation spectroscopy Peierls mechanism, for crystal structure, 2331 Pen˜a Blanca, Chichuhua District, Mexico, uranium deposits at, 272–273 Penning trap, for gas-phase ion chemistry, 1735 Pentadienyl ligands, 2865–2866 Pentahalides structural chemistry of, 2416, 2419, 2419f, 2420t thermodynamic properties of, 2160t, 2161–2165 gaseous, 2164–2165, 2164t solid, 2160t, 2161–2164 Pentahapto complexes, structural chemistry of, 2489, 2490t–2491t, 2492f Pentalene, 2862–2864 bond lengths in, 2864 derivation of, 2862 use of, 2863 Pentamethyl-cyclopentadienyl complexes, stoichiometric reactions of, 2913–2916, 2914f–2915f with alkynes and silanes, 2916–2918, 2917f PERALS, for soil sample measurement, 3066, 3067f Perchlorates of actinide elements, 1796 of plutonium, 1173 of thorium, 101, 102t–103t preparation of, 101 of uranium, 494, 570–571 Perchloric acid media, reduction in, americium (V), 1336 Percolation leaching, of uranium ore, 306 Periodic Anderson model (PAM), SIM v., 2344

Periodic potential, of metallic state, 2307–2308 Perovskites, solid state structures of, 1059–1062, 1060t–1061t, 1062f Peroxides of plutonium, 1175–1176 precipitation with, 836–838, 837–838 processing with, 1143 of protactinium, 208 gravimetric methods with, 229–230 of thorium, 76–77 formation of, 76–77 properties of, 77 of uranium, 259t, 288–289 Peroxydisulfate, oxidation by americium (III), 1333–1335, 1333f americium (IV), 1334 Perrhenates, of thorium, 113 PES. See Photoemission spectroscopy PFP. See Plutonium finishing plant Phase diagram of actinide elements, pressure v., 2368–2369, 2369f of actinide metals, 2312–2313, 2312f, 2384, 2384f of actinide sesquioxides, 1535, 1535f of berkelium oxide, 1466 of curium, plutonium alloys, 1412 of neptunium hydrides, 722, 723f oxides, 724, 725f of plutonium, 879, 882f–883f alloys, 925–929, 926f aluminum alloy, 894, 895f–896f borides, 997, 997f carbides, 1003–1004, 1003f determination of, 892 gallium alloy, 894, 894f–896f history of, 891–892 hydrides, 990, 991f–992f, 3204–3205, 3205f indium alloy, 896, 896f iron alloy, 897, 898f nitrides, 1017, 1017f oxides, 1025, 1026f, 1039–1041, 1040f, 1071–1073, 1073f, 3206–3208, 3207f, 3211–3212, 3212f silicides, 1009, 1011f thallium alloy, 896, 896f trichloride, 1099–1100 of uranium borides, 398, 400f carbides, 399, 403f hydrides, 331, 331f nitrides, 410, 411f oxides, 352–353, 352f, 354f, 1071–1073, 1073f selenides, 418, 419f

I-88

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Phase diagram (Contd.) sulfides, 413, 413f tellurides, 418, 419f uranium hexafluoride, 563, 563f Phase relations of plutonium hydrides and deuterides, 990–992, 991f–992f of uranium oxides, 351–357, 352f UO2.00-UO2.25, 353–354, 354f UO2.25-UO2.667, 354f, 355–356, 358t UO2.667-UO3, 356–357, 358t uranium-uranium dioxide region, 351–353, 352f Phase stability of californium, 1545 of plutonium, 877–890 allotropes of, 877–883, 980 atomic volumes, 886, 887t α and β stabilizers, 897 crystal structure data, 882, 886f δ field expansion, 892–897 density of, 886, 888t eutectic-forming elements, 897 interstitial compounds, 898 microcracking, 890 microsegregation in δ-phase alloys, 899, 916–917 oxides, 1025–1026 phase diagram, 925–929, 926f phase transformations in δ-phase alloys, 917–921, 918f–920f thermodynamic properties of, 890, 891f, 891t transformations, 886–890, 888f–889f vacancy clusters and, 984 valence electrons and, 927 Phase transformations of americium, 1297–1301, 1301f dioxide, 2292 of plutonium, 891–921 α- and β-phase stabilizers, 897 in δ-phase alloys, 917–921, 918f–920f eutectic-forming elements, 897 expand δ-phase alloys, 892–897 interstitial compounds, 898 microsegregation in δ-phase alloys, 899, 916–917 other elements, 898–899 for separation, 2648–2649 of uranium, 344, 347 1-Phenyl–3-methyl–4-benzoylpyrazolone (PMBP) neptunium extraction with, 705–706, 707f protactinium extraction with, 184 synergistic separation with, 2661–2662 3-Phenyl–4-bezoyl–5-isoxazolone, neptunium (IV) extraction with, 706

Phenylarsonates, of protactinium, gravimetric methods with, 229–230 Phenylarsonic acid (PAA), protactinium precipitation by, 179 Phonon energy, relaxation of, 2095–2100 actinides v. lanthanides, 2096 multi-, 2096–2097 Phonon spectrum, of plutonium, 964–967, 965f–966f Phosphates of actinide elements, 1783, 1796 of americium, 1305t–1312t, 1319–1321, 1355 complexes of, 2583 of curium, 1413t–1415t, 1422 of neptunium, 744–745 equilibrium constants for, 775t of plutonium, 1170–1172 precipitation with, 2633–2634 of protactinium (V), 217–218 sorption studies of, 3169–3171 uranium, 3169–3171 uranyl, 3171 structural chemistry of, 2430–2433, 2431t–2432t, 2433f of thorium, 109–110 arsenates v., 113 as ligands, 129 solubility and, 128 structure of, 109–110 study and use of, 109 synthesis of, 109–110 ternary, 110 vanadates v., 110 of uranium, 263t–265t autunite structures, 294–295 chain structures, 295–296 groups of, 294 natural occurrence of, 293 phosphuranylite structures, 295 synthetic, 296–297 uranium (IV), 275 uranium (VI), 297 uranophane structures, 295 in uranyl crown ether complex, 2455–2456 Phosphides of americium, 1318 complexes of, with cyclopentadienyl, 2832–2833 of neptunium, 743 of plutonium, 1021–1022 preparation of, 1021–1022 properties of, 1022 of protactinium, 204, 206t thermodynamic properties of, 2197t, 2203–2204 of thorium, 98t, 99–100 synthesis of, 99–100 of uranium, 411–412

Subject Index

I-89

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Phosphine imide complex, with cyclopentadienyl, 2825 Phosphinic acids, as trivalent actinide and lanthanide separating agent, 1408, 2657, 2665, 2684, 2753 Phosphinidene complexes, with cyclopentadienyl, 2833, 2834f–2835f, 2835 Phospholipids, in actinide fixation, 1817 Phospholyl ligands, 2869–2871 in bimetallic complexes, 2890–2892, 2892f cyclopentadienyl ligands v., 2869 dimeric trivalent compound, 2871, 2872f mixed-ring complexes, 2870–2871 mono-ring complexes, 2870 production of, 2869–2870 structure of, 2869, 2870f Phosphonic acids, as trivalent actinide and lanthanide separating agent, 2651, 2652, 2655, 2753 Phosphorescence, fluorescence v., 625 Phosphorimetry applications of, 3309 fundamentals of, 3309 of uranium, 636 Phosphorylide complex, with cyclopentadienyl, 2826, 2828f Phosphuranylite structures, of uranium phosphates and arsenates, 295 PHOTA. See Photoactivation PHOTN. See Photoneutron logging Photoactivation (PHOTA), for environmental actinides, 3034t, 3043 Photochemical oxidation of neptunium, 762 of polydeoxynucleotides, 630–631 Photochemistry experimental basis for, 627 history of, 626 overview of, 624–625 in Purex process, 712 of uranyl (VI), 624–630 Photoelectron spectroscopy of americium, 1296–1297 of californium, 1515–1516 of einsteinium oxide, 1605 of organometallic actinide compounds, 1800 of thorium hydrides, 64 of uranocene, 2854, 2855f Photoemission spectroscopy (PES) background of, 2334–2336 example of, 2339–2340, 2340f Photon correlation spectroscopy (PCS), for environmental actinides, 3034t, 3035–3036 Photoneutron logging (PHOTN), for environmental actinides, 3044t, 3046

Photothermal spectroscopy, of plutonium, ions, 1114 Phthalocyanine complexes, structural chemistry of, 2463–2467, 2464t, 2466f–2467f Physical concentration methods types of, 303 of uranium ore processing, 302 Pi-bonded ligands, of plutonium, 1188–1191 cyclooctatetraene complexes, 1188–1189 cyclopentadienyl complexes, 1189–1191 PIPS. See Passivated Ion-implanted Planar Silicon detectors Pitchblende. See also Uraninite actinide species in, 3014–3016 complexity of, 302–303 natural occurrence of, 1804–1805 plutonium in, 822 uranium in, 253 PIXE. See Proton-induced X-ray emission spectroscopy Plasma actinide clearance from, 3367–3387 dioxo ions, 3379–3387 rates of, 3367–3369, 3368f–3375f tetravalent and pentavalent, 3376–3379 trivalent, 3370–3376 actinide distribution in, 3357t–3358t, 3359–3361 albumin and globulins, 3362–3363 carbonate and bicarbonate, 3361 citric and other alpha-hydroxy dicarboxylic acids, 3360–3361 with erythrocytes, 3366–3367 transferrin, 3363–3364 transferrin binding, 3364–3366 description of, 3358 electrolytes concentrations in, 3356–3357, 3357t fluid volumes and protein and iron concentration in, 3357, 3358t neptunyl ion in, 3384–3386 plutonyl ion in, 3386–3387 uranyl ion in complexes, 3381–3382, 3382t complexes in bladder urine, 3383–3384 complexes in proximal renal tubular fluid, 3382–3383 Plasma protein, uranyl bonding to, 3380–3381 Plutonium allotropes of, 1, 877–890, 880f, 881t, 1787 α phase, 879–882, 882f–884f, 884t, 2309–2310, 2310f behavior of, 879, 880f, 881t β phase, 882, 882f–883f, 885t δ phase, 882–883, 882f–883f, 886f, 892–897, 899, 916–917, 2329–2330, 2329f

I-90

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Plutonium (Contd.) δ0 phase, 882f–883f, 883 discovery of, 877–879 e phase, 882f–883f, 883 γ phase, 882, 882f–883f transformation of, 879, 882f ζ phase, 882f–883f, 883, 890, 891f americium separation from, 1269–1270 in aqueous solution, 1110–1182 complex ions, 1156–1182 hydrolytic stability, 1146–1156 overview of, 1110–1111 oxidation and reduction reactions, 1117–1146 spectroscopic properties, 1113–1117 stoichiometry and structure of ions, 1111–1113 atomic properties of, 857–862 core-level spectra, 861 ionization potentials, 859 Mo¨ssbauer spectra, 861–862 optical emission spectra, 857–859, 858f, 860t x-ray spectra, 859–861 in biological systems acute toxicity of, 1820–1821 in bone, 1817 health hazard of, 1814 ingestion and inhalation of, 1818–1820 in liver, 1815–1816 long-term effects of, 1821–1822 in organs, 1815 removal of, 1822–1825 transferrin bonding of, 1814–1815 complexes of cyclopentadienyl, 2803 tris-cyclopentadienyl, 2470–2476, 2472t–2473t compounds of, 987–1108 antimonides, 1022–1023 arsenides, 1022 borides, 996–1003 bromides, 1092–1100 carbides, 1003–1009 carbonates, 1159–1166, 1160t–1161t carboxylates, 1176–1181, 1178t chalcogenides, 1023–1077 chlorides, 1092–1100 deuterides, 989–996 fluorides, 1077–1092 halides, 1077–1108, 1180t, 1181 history of, 987–988 hydrides, 989–996 iodates, 1172–1173 iodides, 1092–1100 nitrates, 1167–1168 nitrides, 1017–1021 oxalate, 1173–1175

oxides, 1023–1049 oxyhalides, 1100–1102 perchlorates, 1173 peroxide, 1175–1176 phosphates, 1170–1172 phosphides, 1021–1022 pnictides, 1016–1023 reaction kinetics of, 3215–3223 safety and handling of, 988 selenides, 1049–1056 silicides, 1009–1016 sulfates, 1168–1170 sulfides, 1049–1056 tellurides, 1049–1056 corrosion of catalyzed, 3236–3237 dry, 3227–3228 hydrogen- and hydride-catlyzed, 977–979 kinetic behavior, 3225–3227 metal and intermetallic compounds of, 973–979, 3223–3238, 3226f, 3227t, 3229t salt-catalyzed, 3238 thermal ignition, 3232–3235 unalloyed, 3231–3232 by water vapor, 3228–3230 crystal structure data for, 879, 881t curium v., 935 discovery of, 4, 5t, 8 extraction of neptunium v., 709 Purex process for, 710–712, 710f THOREX process, 2745 with TTA, 1701, 3282 half-life of, 815 handling of, 3201 hazards of, 3200 corrosion, 3204 HF calculations of, 1857–1858, 1857f HFIR target preparation of, 1401 history of, 4, 8, 814–815 ionization potentials of, 859, 1874t isotopes of, 4, 8–10, 12, 815–817, 816t decay of, 1143–1146 formation of, 821, 825–826, 825f from nuclear power reactors, 826, 827t–828t, 828 separation of, 821–822, 828–831 laser spectroscopy of, 1873 liquid, 960–963 melting point of, 960–962 properties of, 962–963 magnetic properties of, 2229–2230, 2230t, 2240–2263, 2355–2357 intermetallic compounds, 2361 man-made, 1805–1807 nuclear fuel processing and storage, 1806–1807, 1807t–1808t

Subject Index

I-91

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 nuclear weapons testing, 1805–1806 satellite disintegration, 1806 metal and intermetallic compounds of, 862–987 aging and self-irradiation damage, 979–987 alloys and phase transformations, 891–921 applications of, 862 corrosion kinetics of, 3223–3238 crystal structure data for, 899, 900t–915t electronic structure, theory, and modeling, 921–935 hazards of, 3256–3257 history of, 862 hydrogen reaction with, 3223–3225, 3224f mechanical properties, 968–973 metal preparation, 863–864 nature of, 863 oxidation and corrosion, 973–979, 3226f, 3227–3235, 3227t, 3229t oxygen, water, and air reaction with, 3225–3238 phase stability, 877–890 physical and thermodynamic properties of, 935–968 pyrochemical preparation and refining, 865–877 safe storage, 3260–3262, 3261f special case of, 2345–2347 structure of, 2386, 2387f natural occurrence of, 822–824, 1756, 1804, 3016 in marine organisms, 1809 states of, 3086 neutron irradiation of, 1757 nuclear properties of, 815–822 oxidation states of, 814, 2525–2527, 2525f in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t sorbed, 3175–3176 oxide-water reaction of, 3209–3210, 3209t production of, 814–815, 1757–1758, 2629 bismuth phosphate process, 2730 REDOX process, 2730–2731 TLA process, 2731–2732 pyrochemical methods for molten chlorides, 2698–2699, 2699f molten fluorides, 2701 processing for, 2702 quadrupole moments of, 1884, 1884f radial functions of, 895, 1897f radiolytic reactions of, 3246–3248 reaction with steel, 3238 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f, 2525, 2525f for RTGs, 43 in RTILs, 2689

rutherfordium extraction with, 1697–1699 separation and purification of, 826–857 in aqueous alkaline solutions, 852 aqueous-based, 830–831 DDP, 2705–2706 ion-exchange processes for, 845–852 from irradiated nuclear fuel, 828–830 non aqueous processes, 853–857 oxalates in, 1173–1174 precipitation and crystallization, 831–839 solvent extraction processes, 839–845 solution chemistry of, 1108–1203 aqueous, 1110–1182 electronic structure and bonding, 1191–1203 history of, 1108–1110 nonaqueous and organometallic, 1182–1191 storage of, 3201 studies on, 11 sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f superconductivity of, 1789 synthesis of, 4, 8–9 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f Plutonium (I) emission spectrum of, 857–859, 858f, 860t isotope shifts of, 1852, 1853f Plutonium (II) emission spectrum of, 857–859, 858f, 860t free-ion parameters of, 2038–2039, 2038t isotope shifts of, 1852, 1853f Plutonium (III) chlorides of, magnetic data, 2229–2230, 2230t compounds of carbonate of, 1159 carboxylates, 1177–1180, 1178t fluoride, 838 oxalate, 836–837, 1174 phosphates, 1171 silicates, 1065, 1068 sulfates of, 1168–1169 coordination numbers of, 1112 distribution coefficients of, 842, 842t free-ion parameters of, 2038–2039, 2038t hydrolytic behavior of, 1147–1149, 1148t, 2546, 2548t magnetic properties of, 2262–2263 oxidation state equilibrium of, 1123–1125, 1124f–1125f, 1126t–1130t

I-92

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Plutonium (III) (Contd.) preparation and stability of, 1125, 1131 oxoplutonates of, alkaline earth metals, 1058 precipitation with fluoride, 838 oxalate, 836–837 reduction potentials of, 2715, 2716f reduction to metal, 870–872, 873f speciation of, 3113t, 3117–3118 structure of, 593 Plutonium (IV) absorption spectrum of, 849 adsorption of, B. sphaericus, 3182–3183 anion-exchange chromatography for, 848–849, 848f in biological systems, 1819 compounds of carbonate of, 1162–1163 carboxylates, 1177–1180, 1178t hydroxide, 838 iodates, 1172–1173 nitrates of, 1167–1168 oxalate, 837, 1174–1175 peroxide, 837–838, 1175–1176 perrhenates, 1068 phosphates, 1171–1172 sulfates of, 1169–1170 vanadates, 1069 coordination numbers of, 1112 detection of, limits to, 3071t disproportionation of, 1119–1122 distribution coefficients of, 842, 842t, 848, 848f extraction of, DHDECMP, 2737–2738 free-ion parameters of, 2038–2039, 2038t hydrolytic behavior of, 1148t, 1149–1150 ligands for, 3417–3420, 3420f magnetic properties of, 2261–2262 magnetic susceptibilities, 2261–2262 in mammalian tissues bone, 3403 bone binding, 3407–3409 circulation clearance of, 3368–3369, 3368f–3375f, 3378 glycoproteins, 3410–3411, 3411t initial distribution, 3341t–3344t, 3346t, 3352–3353 liver, 3398–3400 transferrin binding to, 3364, 3365 natural occurrence of in hydrosphere, 1807–1810 sorption and mobility, 1810 oligomerized, 3210–3211 oxidation state equilibrium of, 1123–1125, 1124f–1125f, 1126t–1130t preparation and stability of, 1131–1132

oxoplutonates of alkali metals, 1056 alkaline earth metals, 1058 crystallographic data of, 1060t–1061t polymerization of, 1150–1154, 1151f, 1153f applications of, 1150 characterization of, 1152–1153 history of, 1151–1152 precipitation with hydroxide, 838 oxalate, 837 peroxide, 837–838 reduction of, 1139–1140 rutherfordium extraction with, 1697–1698 separation of HDEHP for, 2651, 2651f PUREX process, 2732 from SNF, 2646 solvating extractant system for, 2654–2655 speciation of, 3108–3109, 3113t, 3136 Plutonium (V) adsorption, B. sphaericus, 3182–3183 compounds of carbonate of, 1163–1165 carboxylates, 1178t, 1180–1181 nitrates of, 1168 oxalate, 1175 peroxide, 1175–1176 phosphates, 1172 coordination numbers of, 1112 disproportionation of, 1122–1123 hydrolytic behavior of, 1154–1155 in hydrosphere, 1807–1810 magnetic properties of, 2257–2261 oxidation state equilibrium of, 1123–1125, 1124f–1125f, 1126t–1130t preparation and stability of, 1132 oxoplutonates of alkali metals, 1056 alkaline earth metals, 1058 crystallographic data of, 1060t–1061t with pyrochemical processes, 2698–2699, 2699f reduction of, 1143 Plutonium (VI) adsorption, B. sphaericus, 3182–3183 compounds of carbonate of, 1165–1166 carboxylates, 1178t, 1180–1181 iodates, 1173 nitrates of, 1167–1168 peroxide, 1175–1176 phosphates, 1172 distribution coefficients of, 842, 842t hydrolytic behavior of, 1155–1156 magnetic properties of, 2247–2257

Subject Index

I-93

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 manganite and hausmannite reactions with, 3176–3177 oxidation state equilibrium of, 1123–1125, 1124f–1125f, 1126t–1130t preparation and stability of, 1132 oxoplutonates of alkali metals, 1057 alkaline earth metals, 1058–1059 crystallographic data of, 1060t–1061t oxygen exchange with solvent water, 1133 with pyrochemical processes, 2698–2699, 2699f reduction of, 1138–1139, 1142–1143 alpha-induced, 1145–1146, 1146t kinetics, 760–761 separation of, PUREX process, 2732 speciation of, 3113t, 3126 Plutonium (VII) coordination numbers of, 1112–1113 hydrolytic behavior of, 1156 magnetic properties of, 2240–2247 oxidation state, preparation and stability of, 1132–1133 oxoplutonates of alkali metals, 1057 alkaline earth metals, 1059 crystallographic data of, 1060t–1061t speciation of, 3113t, 3126 Plutonium carbide entropy of, 2196, 2197t formation enthalpy of, 2195–2196, 2197t high-temperature properties of, 2198, 2198f, 2199t Plutonium carbonates, structural chemistry of, 2426–2427, 2427t, 2428f Plutonium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Plutonium diboride, 999t, 1000, 1000f Plutonium dicarbide chemical properties of, 1008 structure of, 1005t, 1006–1007, 1007f Plutonium dioxide covalency in, 1196–1199, 1197f, 1200f crystal structure of, 2289–2290 crystal-field splittings of, 2288–2289 electronic structure of, 1044, 1196–1199, 1197f, 1200f, 1976 gas pressure generation with, 3248–3251 in gas-phase, 2148t, 2149 handling of, 3201 hazards of, 3249 IPNS of, 2289, 2290f JT effect of, 2290 magnetic properties of, 2288–2290 magnetic susceptibility of, 2290, 2291f oxidation of plutonium metal, 973, 3229 physical properties of, 1032, 1032t

plutonium metal production from, 866 preparation of, 1031–1034 pellets, 1032–1033 single crystals, 1033–1034 spheres, 1033 reactions of, 3219–3222 stability of, 3200 storage of, 3201 structure of, 1027t, 1037, 1038f, 1041–1044, 1042f–1043f, 2395 thermodynamic properties of, 1047t, 1048, 3250 enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 heat capacity of, 2138–2141, 2139f, 2142t XPS of, 861 Plutonium disilicide, structure of, 1015, 1016f Plutonium dodecaboride, 999t, 1002, 1002f Plutonium finishing plant (PFP), TRUEX process at, 2740, 2741f Plutonium fluorides, 1077–1092 chemical properties of, 1092 precipitation with, 838 preparation of, 1077–1082 overview of, 1077–1078 plutonium hexafluoride, 1080–1082, 1081f plutonium pentafluoride, 1079–1080 plutonium tetrafluoride, 1078–1079 plutonium trifluoride, 1078 properties of, 1083–1092 radiation decomposition of, 1090–1092 solid-state structures of, 1082–1083, 1084t, 1085f plutonium hexafluoride, 1083, 1084t plutonium tetrafluoride, 1083, 1084t, 1085f plutonium trifluoride, 1082, 1084t Plutonium halides, 1077–1108 chlorides, bromides, and iodides, 1092–1100 preparation of, 1092–1095 properties of, 1098–1100 solid-state structures of, 1096–1097 fluorides, 1077–1092 preparation of, 1077–1082 properties of, 1083–1092 solid-state structures of, 1082–1083 oxyhalides of, 1100–1102 preparation and properties of, 1101–1102 solid-state structures of, 1102 stability of, 1077 ternary halogenoplutonates, 1102–1108 phase diagram of, 1104, 1108f preparation of, 1103–1104 Plutonium hectoboride, 999t, 1002 Plutonium hexaboride, 999t, 1001–1002, 1002f

I-94

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Plutonium hexafluoride absorption spectra of, 2084–2085.2086f chemical properties of, 1092 covalency in, 1193–1196 electronic structure of, 1194–1196, 1195f energy level analysis of, 2083–2085, 2083t, 2085f preparation of, 1080–1082, 1081f properties of, 1086–1090, 1087t radiation decomposition of, 1090–1092 structure of, 1083, 1084t, 2419, 2421, 2421t studies of, 1938 thermodynamic properties of, 2160–2161, 2160t, 2162t–2164t Plutonium hydrides air reaction with, 3218 electrical properties of, 3205 entropy of, 2188, 2189t formation enthalpy of, 2187–2188, 2187t, 2189t, 2190f high-temperature properties of, 2188–2190, 2190t hydrogen reaction with, 3215–3216 nitrogen reaction with, 3217–3218 oxygen reaction with, 3216–3217 phase diagram of, 990, 991f–992f, 3204–3205, 3205f reaction rates of, 3215 structure of, 2403–2404 thermodynamic properties of, 3205, 3206t water reaction with, 3219, 3229 Plutonium hydroxides, 3213 precipitation with, 838 Plutonium monocarbide chemical properties of, 1007–1008 structure of, 1004–1006, 1005t Plutonium monophosphide, 1021–1022 Plutonium monosilicide, structure of, 1014, 1015f Plutonium monoxide dissociative energy of, 2149–2150, 2150f in gas-phase, 2148t, 2149 physical properties of, 1028 preparation of, 1028–1029 structure of, 2394–2395 Plutonium nitride, 3212–3213 enthalpy of formation of, 2197t, 2200–2201 entropy of, 2197t, 2201–2202 high-temperature properties of, 2199t, 2202 reactions of, 3222–3223 Plutonium oxalate, precipitation with, 837 Plutonium oxides, 1023–1049, 3206–3212 applications of, 1023–1025 container material compatibility with, 1049 dioxide, 1031–1034 formation enthalpies of, 1971 hazards of, 3257–3258, 3258t

interface of, 976–977, 978f monoxide, 1028–1029 phase diagram of, 1025, 1026f, 1039–1041, 1040f, 1071–1073, 1073f, 3206–3208, 3207f, 3211–3212, 3211f phase equilibria, 1025–1026, 1026f plutonium (VIII), 1932–1933 preparation of, 1028–1036, 3206–3207 higher oxides, 1034–1036 plutonium dioxide, 1031–1034 plutonium monoxide, 1028–1029 plutonium sesquioxide, 1029–1031 properties of chemical, 1048–1049 melting behavior, 1045 oxygen diffusion, 1044–1045 thermodynamic properties, 1047–1048, 1047t vaporization behavior, 1045–1047, 1046f reaction rates of, 3219–3222 safe storage, 3260–3262, 3261f sesquioxide, 1029–1031 sesquioxide phase with, 3208 solid-state structures of, 1027t, 1036–1044, 1038f–1040f, 1042f–1043f stability of, 3207 structure of, 2394–2395 ternary with actinides, 1070–1077 with lanthanide oxides, 1069–1070 thermal decomposition of, 3211 thorium oxides with, 1070–1071 uranium oxides with, 1070–1077 applications of, 1070–1071 phase diagram of, 1071–1073, 1073f preparation of, 1073–1074 properties of, 1074–1077 Plutonium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Plutonium pentafluoride, preparation of, 1079–1080 Plutonium peroxide, precipitation with, 837–838 Plutonium phosphates, structural chemistry of, 2430–2433, 2431t–2432t Plutonium pnictides, structure of, 2409–2414, 2410t–2411t Plutonium sesquioxide formation enthalpy of, 2143–2146, 2144t, 2145f high-temperature properties of, 2139f, 2146–2147 layer formation, 3208 oxide phase with, 3208 phase relationships of, 3207 physical properties of, 1030 preparation of, 1029–1031 reactions of, 3219

Subject Index

I-95

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 structure of, 1027t, 1037–1038, 1038f–1039f, 2395 thermodynamic properties of, 1047–1048, 1047t Plutonium silicides, structural chemistry of, 2406t, 2408 Plutonium sulfates, structural chemistry of, 2433–2436, 2434t Plutonium tetraboride, 999t, 1000–1001, 1001f Plutonium tetrachloride preparation of, 1093–1094, 1094f stabilization of, 1184 Plutonium tetrafluoride plutonium metal from, 866 from plutonium with americium–241, 1270 preparation of, 1078–1079 properties of, 1085–1086, 1087t structure of, 1083, 1084t, 1085f thermodynamic properties of, 2165–2169, 2166t Plutonium tetrahalides, structural chemistry of, 2416, 2418t Plutonium tribromide organic-solvent soluble, 1182–1183 preparation of, 1095 properties of, 1087t, 1098–1100, 1099t solid-state structure of, 1084t, 1096–1097, 1097f–1098f structural chemistry of, 2416, 2417t Plutonium trichloride magnetic properties of, 2262 organic-solvent soluble, 1182–1183 preparation of, 1092–1093 properties of, 1087t, 1098–1100, 1099t solid-state structure of, 1084t, 1096, 1096f, 1098f Plutonium trifluoride organic-solvent soluble, 1182–1183 preparation of, 1078 properties of, 1083–1085, 1087t structure of, 1082, 1084t thermodynamic properties of, 2169, 2170t–2171t Plutonium trihalides, structural chemistry of, 2416, 2417t Plutonium triiodide organic-solvent soluble, 1182–1183 preparation of, 1095 solid-state structure of, 1084t, 1096–1097 Plutonium tritelluride, structure of, 1053, 1053f Plutonium, Uranium, Reduction, Extraction process. See PUREX process Plutonium-231, discovery of, 815 Plutonium-236 detection of, αS, 3295 from neptunium-237, 703 nuclear properties of, 3277t ultrapure preparation of, 822

Plutonium-237, ultrapure preparation of, 822 Plutonium-238 applications of, 817–819 curium-242 and -244 v., 1400 detection of limits to, 3071t RIMS, 3321 αS, 3295 discovery of, 814–815, 817 as energy production by-product, 1805 half-life of, 815, 817 as heat source, 703, 1758 Mo¨ssbauer spectroscopy of, 861 from neptunium–237, 703 from neptunium–238, 861 nuclear properties of, 3277t for power generation, 1827–1828 uranium–234 from, 257 Plutonium–239 absorption cross section of, 2233 americium–241 from, 1268, 1758 critical parameters of, 820–821, 821t curium from, 1758–1759 detection of AMS, 3062–3063, 3319 FTA, 3307 γS, 3302 ICPMS, 3327–3328 limits to, 3071t RIMS, 3321 αS, 3295 TIMS, 3314 discovery of, 815 environmental hazards of, 1807 half-life of, 820 heat capacity of, 945 importance of, 820 ionization potential of, 1875 IP of, 859 maximum allowed dose of, 1821 Mo¨ssbauer spectroscopy of, 861–862 natural occurrence of, 822–824, 823t, 1756 neutron capture formation of, 823–824 nuclear energy with, 815 nuclear properties of, 3277t for nuclear weapons, 1805 production of from neptunium–239, 861 in nuclear reactor, 1826 from uranium–239, 255, 1757 radioactivity of, 1765 security risk of, 1758 study with, 1765 toxicity of, 1820 transmutation products of, 984–985, 985f Plutonium–240 detection of AMS, 3319

I-96

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Plutonium–240 (Contd.) γS, 3302 ICPMS, 3328 limits to, 3071t RIMS, 3321 αS, 3295 TIMS, 3314 as energy production by-product, 1805 environmental hazards of, 1807 Fourier transform spectrum of, 858, 858f Mo¨ssbauer spectroscopy of, 862 nuclear properties of, 3277t Plutonium-241 as beta emitter, 825 detection of RIMS, 3321 TIMS, 3315 as energy production by-product, 1805 maximum allowed dose of, 1821 neptunium–237 from, 705, 706f, 783–785 nuclear properties of, 3277t Plutonium-242 americium-243 from, 1268 curium from, 1400 detection of ICPMS, 3328 RIMS, 3321 αS, 3295 TIMS, 3315 as energy production by-product, 1805 Fourier transform spectrum of, 858, 858f heat capacity of, 947, 947f nuclear properties of, 3277t study with, 1765 Plutonium-243, as beta emitter, 825 Plutonium-244 detection of, AMS, 3062–3063 Fourier transform spectrum of, 858, 858f natural occurrence of, 822, 824 nuclear properties of, 3277t spontaneous fission of, 824 study with, 1765 Plutonocene electronic structure of, 1199–1203, 1201f–1202f HOMO of, 1946 properties of, 1946–1948 Plutonyl (V) formation of, 3210 speciation of, 3113t, 3123–3124 Plutonyl (IV), hydrolytic behavior of, 2551–2552, 2551f–2552f Plutonyl (VI), speciation of, 3113t, 3123–3124, 3134 Plutonyl ion aqueous solution absorption spectra of, 2080, 2081f complexes of, 1922–1923

cation-cation, 2594 structure of, 2400–2402 extraction of, REDOX process, 2730–2731 highest composition of, 3210 hydrolytic behavior of, 2553 in mammalian tissues circulation clearance of, 3378, 3386–3387 erythrocytes association with, 3366–3367 initial distribution, 3342t, 3356 reduction of, 2591 study of, 1931–1932 PMBP. See 1-Phenyl–3-methyl–4benzoylpyrazolone Pnictides of americium, 1305t–1312t, 1317–1319 coordination of, 1358–1359 of berkelium, 1464t–1465t, 1470 preparation of, 1460 of californium, 1530t–1531t, 1538–1539 of curium, 1413t–1415t, 1421 of neptunium, 742–744 applications of, 742 of plutonium, 1016–1023 antimony system, 1022–1023 arsenic system, 1022 families of, 1016–1017 nitrogen system, 1017–1021 phosphorus system, 1021–1022 valency and electronic structure, 1023 of protactinium, 204–207 structural chemistry of, 2409–2414, 2410t–2411t thermodynamic properties of, 2200–2204 gaseous nitrides, 2202–2203 phosphides, arsenides, and antimonides, 2203–2204 solid nitrides, 2200–2202 of thorium, 97–101, 98t, 99f antimony, 98t, 100 arsenides, 98t, 100 bismuth, 98t, 100 nitrides, 97–99, 98t, 99f phosphides, 98t, 99–100 of uranium, 407–412, 408t–409t nitride, 407–411, 408t–409t, 411f others, 411–412 preparation of, 411–412 Polarizabililty, of transactinide elements, 3, 1675–1676 Polarography for californium, 1548 for neptunium, determination of, 791–792 for protactinium, 220, 227 for uranium, 3066 Polonium, discovery of, 245 Polonium–212, seaborgium study interference by, 1708

Subject Index

I-97

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Polyaminopolycarboxylic acids, as chelating agents, 3413–3414 Polymerization of actinide elements, 1778–1782 of plutonium (IV), 1150–1154, 1151f, 1153f, 1781, 1810 of protactinium (IV), 1780 of thorium (IV), 1778–1781 of uranium (IV), 1780–1781 Polypnictide, complexes of, with cyclopentadienyl, 2836 Porphyrin complexes, structural chemistry of, 2463–2467, 2464t, 2466f–2467f Potassium chloride, in electrorefining, 2714–2715 permanganate, for uranium carbonate leaching, 307–308 with thorium molybdates, 112 with thorium sulfates, 105 Potentiometric method for neptunium, 781–782 determination of, 790–791 for protactinium, 227 Powder diffraction techniques, for oxides, 2389 Powder neutron scattering, overview of, 2383–2384 Powder X-ray diffraction of cyclopentadienyl complexes, tetravalent, 2814–2815 overview of, 2382–2383 Power production. See Nuclear energy PPs. See Pseudopotentials Praseodymium, UO2 solid solutions with, oxygen potentials of, 395t, 396 Precipitation of americium, 1270–1271 of berkelium, 1449 crystallization v., 832–833 of curium, 1410 historical development of, 2627–2628 of plutonium, 831–839 conversion chemistry, 836–839 coprecipitation, 833–835 decontamination factors for, 832, 833t reactions for, 831, 832t in RTILs, 2690 for separation, 2633–2634 Preconcentration neutron activation analysis (PCNAA) application of, 3307 description of, 3303 Pressure leaching, of uranium ore, 306 Pressure-composition diagram, of uranium-hydrogen system, 330–331, 330f Propionates, structural chemistry of, 2439t–2440t

Protactinium, 161–232 actinium separation from, 38 analytical chemistry of, 223–231 determination in environment, 231 electrochemical methods, 227 radioactivation methods, 226 radiometric methods, 223–226 spectral and X-ray methods, 226–227 applications of, 188–189 ceramic capacitors, 189 color cathode ray tube, 188–189 dating methods, 189 nuclear waste clean-up, 189 X-ray detection, 188 atomic properties of, 189–191 emission spectrum, 190 ground state configuration, 190 Mo¨ssbauer effect, 190–191 X-ray atomic energy levels, 190, 190t complexes of, tetrakis-cyclopentadienyl, 2814–2815 d transition elements v., 2 dubnium v., 1704–1705 half-life of, 162–163 ionization potentials of, 1874t isotopes of, 161–162, 164–170, 165t metallic state of, 191–194 alloys of, 194 physical parameters of, 191–194, 193t preparation of, 191 structure of, 2385 natural occurrence of, 170–171, 1755 nonstoichiometric compounds of, 1797 nuclear properties of, 164–170 oxidation states of, 2526 in aqueous solution, 1774–1776, 1775t ion types, 1777–1778, 1777t preparation of, 172–189 of 234 and 234m isotopes, 186–187 aqueous raffinate enrichment for, 175–176 carbonate precipitate enrichment for, 174–175 ethereal sludge enrichment for, 176–178, 177f industrial-scale enrichment for, 174 procurement of, 172–173 of protactinium–233, 187–188 raw material analysis for, 172, 173t purification of, 178–186 ion exchange, 180–181, 180f large-scale recovery of protactinium–231, 186 precipitation and crystallization, 178–179 solvent extraction and extraction chromatography, 181–186, 183f pyrochemical methods for molten chlorides, 2695

I-98

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Protactinium (Contd.) molten fluorides, 2701 processing for, 2702 reduction potentials of, 1778, 1779f, 2127–2131, 2130f–2131f simple and complex compounds of, 194–209 borohydride, 206t, 208 carbides, 195 cyclooctatetraene, 206t, 208 halides, 197–204, 201t hydrides, 194 miscellaneous, 207–209 oxides, 195–197, 196t–197t pnictides, 204–207 tropolone, 206t, 208 solution chemistry of, 209–223 oxidation states of, 209 protactinium (IV) aqueous chemistry, 222–223, 223f protactinium (V) complexes in aqueous solution, 218–219, 219t protactinium (V) complexes in mineral acids, 212–218, 214t–215t, 216f, 217t, 218f protactinium (V) hydrolysis, 209–212, 210f, 211t, 212f redox behavior in aqueous solution, 220–221 structure of, 191–194, 193t superconductivity of, 1789 thermodynamic properties of enthalpy of formation, 2123–2125, 2124f–2125f, 2539, 2541t entropy of, 2539, 2542f, 2543t Gibbs formation energy of hydrated ion, 2539, 2540t heat capacity of, 2119t–2120t, 2121f sublimation enthalpy of, 2119t–2120t, 2122–2123, 2122f toxic properties of, 188 from uranium–235, 42–44 Protactinium (III) electron configurations of, 2018–2019, 2018f free-ion parameters of, 2038–2039, 2038t Protactinium (IV) aqueous chemistry of, 222–223, 223f emission spectra of, 2067–2068, 2068f free-ion parameters of, 2038–2039, 2038t hydrolytic behavior of, 2550 initial distribution in mammalian tissues, 3342t, 3347t, 3353–3354 magnetic properties of, 2240–2247 polymerization of, 1780 spectroscopic properties of, 2065–2066, 2066t Protactinium (V) absorption spectra of, 212, 212f

complexes in aqueous solution of, 218–219, 219t complexes in mineral acids of, 212–218 fluoro complexes, 213–215 ionic species in hydrochloric acid, 213, 215t ionic species in nitric acid, 212–213, 214t miscellaneous with inorganic ligands, 217–218 sulfuric acid, 215–216, 217t, 218f detection of limits to, 3071t NMR, 3033 dubnium v., 1704 equilibrium constants of, 211, 211t hydrolytic behavior of, 209–212, 210f, 211t, 212f magnetic properties of, 2239–2240 in mammalian tissues circulation clearance of, 3368–3369, 3368f–3375f, 3378–3379 transferrin binding to, 3365 thermodynamics of, 211, 211t Protactinium chalcogenides, structural chemistry of, 2409–2414, 2412t–2413t Protactinium dioxide Dirac-Hartree-Fock calculations on, 1917–1918 enthalpy of formation, 2136–2137, 2137t, 2138f entropy of, 2137–2138 in gas-phase, 2148, 2148t heat capacity of, 2138–2141, 2139f, 2142t structure of, 2391 Protactinium hydrides entropy of, 2188, 2189t formation enthalpy of, 2187–2188, 2187t, 2189t, 2190f high-temperature properties of, 2188–2190, 2190t structure of, 2402–2403 Protactinium monoxide dissociative energy of, 2149–2150, 2150f structure of, 2391 Protactinium oxides structure of, 2391 thermodynamic properties of, 2136, 2136t Protactinium oxyhalides, structural chemistry of, 2421, 2422t, 2423, 2424t–2426t Protactinium pentachloride structural chemistry of, 2416, 2419, 2419f, 2420t thermodynamic properties of, 2160t, 2161, 2164–2165, 2164t Protactinium pentafluoride structural chemistry of, 2416, 2419, 2419f, 2420t

Subject Index

I-99

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 thermodynamic properties of, 2160t, 2161, 2164–2165, 2164t Protactinium pentahalides, structural chemistry of, 2416, 2419, 2419f, 2420t Protactinium phosphates, structural chemistry of, 2430–2433, 2431t–2432t Protactinium pnictides, structure of, 2409–2414, 2410t–2411t Protactinium sulfates, structural chemistry of, 2433–2436, 2434t Protactinium tetrachloride, magnetic susceptibility of, 2241 Protactinium tetraformate, magnetic susceptibility of, 2241 Protactinium tetrahalides, structural chemistry of, 2416, 2418t Protactinium trihalides, structural chemistry of, 2416, 2417t Protactinium–231, 164–167, 165t, 166f actinium–227 from, 20 alpha-spectrum of, 166, 167f dating with TIMS, 171 with uranium–235, thorium–230, and, 170–171 detection of γS, 3301 limits to, 3071t MBAS, 3043 MBES, 3028 NMR, 3033 αS, 3294 TIMS, 3314 discovery of, 162–163 emission spectrum of, 190 gamma-ray spectrum of, 166, 168f half-life of, 166, 170 importance of, 164 isotope dilution mass spectrometry for, 231 large-scale recovery of, 186 natural occurrence of, 170 from neutron irradiation, 1756 nuclear properties of, 3274t–3275t, 3290t, 3298t overview of, 161 procurement of, 167 protactinium–232 from, 256 radioactivation methods for, 226 radiometric methods for alpha-counting, 224 gamma rays, 225 toxicity of, 188 Protactinium–232 from protactinium–231, 256 uranium–232 from, 256 Protactinium–233, 165t, 167–169 adsorption behavior of, 176 detection of, TIMS, 3314

half-life of, 169 importance of, 164, 167–169 natural occurrence of, 171 neptunium–237 equilibrium with, 785 nuclear properties of, 3274t–3275t, 3298t overview of, 161 preparation of, 187–188 procurement of, 167–169, 169t radiometric methods for, 225–226 Protactinium–234, 170, 170f discovery of, 162 gamma-ray spectrum of, 170, 171f half-life of, 186 importance of, 164 nuclear properties of, 3274t–3275t, 3298t protactinium–234 v. protactinium–234m, 170, 170f preparation of, 186–187 radiometric methods for, 225 Protactinocene electronic transitions in, 1949–1951 properties of, 1946–1948 structure of, 1944, 1944t, 1945f Protasite, anion topology of, 282, 284f–285f Protonation routes, for cyclopentadienyl complexes, 2819 Proton-induced X-ray emission spectroscopy (PIXE) for environmental actinides, 3059t, 3060–3061 RBS with, 3069 PSD. See Pulse shape discrimination Pseudomonas fluorescens, neptunium (V) adsorption, 3182 Pseudopotentials (PPs), for electronic structure calculation, 1671 PSI. See Paul Scherrer Institute Pulse shape discrimination (PSD), neptunium–237 determination with, 785 PUREX process actinide extraction with, 1274–1276, 1285, 1408, 1769 for actinide production, 2732–2733 alternative to, 1273 americium extraction with, 1273 BUTEX and REDOX processes v., 842 flow sheet for, 843, 843f historical development of, 841, 2629, 2732 improvements to, 844, 2733 for neptunium extraction, 710–712, 710f, 2756–2757 acids for, 711 advanced, 711 controlling of, 712 overview of, 710–711 other operations of, 844

I-100

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 PUREX process (Contd.) plutonium separation with, 829–830, 841–844, 856–857 steps of, 841–842 redox agents for, 760 separation with, 2646 steps of, 2732–2733 Pyrazole adduct, of cyclopentadienyl complexes, 2830 Pyrazolylborate complexes, 2880–2886 chemistry of, 2880 cyclopentadienyl ligands v., 2880 fluxional, 2885–2886 formation of, 2880–2881 metathesis reactions, 2884–2885, 2884f neptunium derivatives, 2885 steric factors, 2885 tetravalent, 2883, 2885, 2886f trivalent, 2882 uranium (III), 2881, 2882f Pyrochemical methods actinide chemistry in, 2694 for americium, 1269–1270 DDP applications, efficiency, 2707–2708 electrorefining, 2712–2717 electro-transport, 2714–2715 IFR, 2712–2714 separation efficiencies, 2715–2717, 2718t melt refining under molten salts, 2709–2710 metal-metal processes, 2708–2709 molten chlorides in, 2694–2700 americium, 2699–2700 curium and transcurium, 2700 neptunium, 2697–2698 plutonium, 2698–2699, 2699f protactinium, 2695 thorium, 2694–2695 uranium, 2695–2696, 2697f molten fluorides in, 2700–2701 plutonium, 2701 protactinium, 2701 thorium, 2701 uranium, 2701 molten metal-salt extraction, 2710–2712 Argonne salt transport process, 2710–2712, 2712f other applications, 2712 molten oxy-anion salts, 2702–2704 molybdates, 2702–2703 nitrates, 2704 sulfates, 2704 tungstates, 2703–2704 molten-salt processing in, 2701–2702 nitride-nitride process, 2723–2725 actinide nitride recovery, 2724–2725 dissolution step, 2724 historical development of, 2723–2724 overview of, 853–854, 2691–2694

oxide-metal processes, 2717–2721 for plutonium metal production, 864–877 direct oxide reduction, 866–869, 868f–869f electrorefining, 870–872, 873f flow diagram for, 865, 865f fluorination and reduction, 866, 867f molten salt extraction, 869–870 need for, 865 pyroredox or anode recovery, 872–876 vacuum melting and casting, 870, 871f–872f zone-refining, 876–877 for plutonium separation, 854 processing requirements of, 2701 recovery from LWR fuels, 2721–2723 calcium reduction, 2722 lithium reduction, 2722–2723 for separation, 2691–2725 separation techniques for, 2704–2707 DDP basis, 2705–2707 oxide-oxide process, 2704 Pyrochlore californium oxides, 1538, 1540f description of, 278–279 natural occurrence of, 279 structure of, 278, 279f uranium (V) in, 279 Pyrophoricity, of plutonium, 3251 in air, 975f, 976–977, 978f Pyroredox, for plutonium metal production, 872–876 equipment for, 868f, 875 process for, 875–876 product from, 876 Pyrrole-based ligands, 2871–2873, 2873f–2874f QED effect. See Quantum electrodynamic effect Quantum critical point, NFL and, 2348–2350 Quantum electrodynamic effect (QED effect), on inner orbitals, 1669 Quantum mechanical calculations, of crystal field parameters, 2049 ‘Quasiparticles,’ description of, 2339 Quaternary amines, for actinide extraction, 1769 Quaternary ammonium salts, for americium extraction, 1284 Quenching mechanisms, of uranyl (VI), 629 RA. See Rhizopus arrhizus RAD. See Autoradiography Radial functions, of plutonium atom, 895, 1897f

Subject Index

I-101

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Radial integrals, of actinide elements, 1863 comparisons of, 1865–1866, 1867f Radioactinium. See Thorium–227 Radioactive decay, of plutonium, consequences, 980 Radioactive displacement principle, description of, 162 Radioactive waste. See also Nuclear waste immobilization of, neptunium phosphate, 744 protactinium isolation from, 179 Radioactive-detected resonance ionization spectroscopy (RADRIS), of americium, 1880–1881, 1881f, 1884 Radioactivity of actinides, 1, 1764–1765 of curium–244, 1759 discovery of, 254 of plutonium–239, 1765 Radioanalytical chemistry of americium, 1364 of berkelium, 1483–1484 Radiochemical Engineering Development Center (REDC), for transcurium element production, 9 Radiochemical neutron activation analysis (RNAA) applications of, 3305–3307 description of, 3303 INAA v., 3305–3306 MC-ICPMS v., 3329 Radiocolloid formation, by actinium, 41–42 Radioisotope Engineering Development Center (REDC), production at, 1760 Radioisotope heater units (RHU), plutonium for, 703 plutonium–238, 817 Radioisotope thermoelectric generator (RTG) actinium for, 42–43 plutonium for, 43, 703 plutonium–238, 817 Radiolysis of adsorbed water, 3221–3222 of americium, 1337–1338 of einsteinium, 1579 of plutonium, 1143–1146 reactions of, 3246–3248 of water at SNF, 289 Radiometric methods for neptunium, 783–786 activation analysis, 785–786 alpha- and gamma-ray spectrometry, 783–785 liquid scintillation counting method, 785 of protactinium, 223–226 protactinium–231, 224–225 protactinium–233, 225–226 protactinium–234, 225

for uranium, 635–636 Radiopolarography of einsteinium, 1606–1607 of fermium, 1630 of mendelevium, 1636 of nobelium, 1640–1641 Radiothorium. See Thorium–228 Radiotoxicity, measuring of, 3339–3340 Radiotracer techniques, for environmental samples, 3022 Radium discovery of, 254 recovery of, 172–173 Radium–226 actinium–227 from, 1756 nuclear properties of, 3298t Radium–228, actinium–228 from, 25, 28 Radon, in actinium isolation, 32 RADRIS. See Radioactive-detected resonance ionization spectroscopy Raman spectroscopy (RAMS) of berkelium, berkelium (III), 1455 of californium, 1544, 1554 for environmental actinides, 3035 XRF and IRS with, 3069 RAMS. See Raman spectroscopy Rare earth metals actinide separation from, 2706 actinium separation from, 30 atomic volumes of, 922–923, 923f neptunium v., 700 reduction potentials of, 2715, 2716f reductive extraction of, 2719 separation of, actinide elements, 2719, 2720t, 2721f uranium oxides with, 389 Rate constants of actinide complexation, 2606, 2606t of An-O bond breakage, 2598–2600, 2599t comparison of, 2601–2602, 2602t of electron exchange reactions, 2597 of ligand exchange reactions, 608, 609t, 611t–612t redox reactions, 622–623 Rats initial distribution in, 3341t–3342t tissue deposition kinetics in, 3387–3388 RBS. See Rutherford backscattering Reaction rates, of plutonium hydrides, 3215 Reagent classes, for separation, 2645–2646 Recoil nucleus, from plutonium decay, 980–981 Recoil Transfer Chamber (RTC) in rutherfordium study, 1701 for superactinide element study, 1734 RECPs. See Relativistic effective core potentials

I-102

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 REDC. See Radiochemical Engineering Development Center; Radioisotope Engineering Development Center Redox behavior of actinide complexes, 2596–2602 An-O bond breakage, 2598–2600, 2599t complexation effect, 2601–2602, 2602t disproportionation reactions, 2600–2601, 2600t electron exchange reactions, 2597–2598 of actinide elements, 1778, 1780t in water, 3096 of actinium, 37–38 of americium autoreduction, 1330–1331 disproportionation, 1331–1332 electrode potentials and thermodynamic properties, 1328–1330, 1329t hydration and coordination numbers, 1327, 1328f kinetics of, 1333–1337 radiolysis, 1337–1338 of berkelium, 1448, 1479–1482 of californium, 1546–1549, 1547t disproportionation reactions v., 2601 of humic and fulvic acids, 2591 of neptunium, 753–755, 793–794, 794f in acidic media, 753 in basic media, 754–755 in biological systems, 1814 coulometry for, 757–759, 758f sodium hydroxide and, 756 voltammetric behavior of, 755–757, 756t, 757f of plutonium actinide ions and, 1133–1137, 1134t–1135t ammonia, 1141–1142 autoradiolysis, 1143–1146 hydrazine, 1142 hydroxylamine, 1140–1141 ions, 1117–1119, 1118f, 1118t, 1120t iron, 1138–1139 nitric acid, 1139–1140 nonactinide ions and, 1137–1143 oxidation state equilibrium, 1123–1125 peroxide, 1143 plutonium (IV) disproportionation, 1119–1122 plutonium (V) disproportionation, 1122–1123 plutonium (VI) oxygen exchange with solvent water, 1133 preparation and stability of oxidation states, 1125–1133 of protactinium, 220–221

of thorium, 60–61, 117–118 of transactinide elements, 1685–1686, 1685f–1686f of uranium aqua ions, 590–591, 592f, 594t dioxouranium (VI), 594t, 596 hexafluoride, 562 rates and mechanisms of, 622–624, 623f reduced phases, 274–280 REDOX process for actinide production, 2730–2731 bismuth phosphate process v., 2731 historical development of, 2629, 2730 PUREX process v., 842 Redox reagents, for neptunium, 759–761, 760t Redox speciation acid americium (III), 3114t, 3115 berkelium (IV/III), 3109–3110, 3114t californium (III), 3110, 3114t, 3115 curium (III), 3110, 3114t of environmental samples, 3100–3124 monatomic An (III) and An (IV) ions, 3100–3118 neptunium (III), 3111t–3112t, 3116–3117 neptunium (IV), 3106–3108, 3111t–3112t neptunyl (V), 3111t–3112t, 3121–3122 neptunyl (VI), 3111t–3112t, 3122–3123 plutonium (III), 3113t, 3117–3118 plutonium (IV), 3108–3109, 3113t plutonyl (VI/V), 3113t, 3123–3124 thorium (IV), 3103–3105, 3103t triatomic An (V) and An (VI) ions, 3118–3124 uranium (III), 3101t–3102t, 3116 uranium (IV), 3105–3106 uranyl (VI), 3101t–3102t, 3118–3121 base carbonate solution systems, 3129–3137 hydroxide solution systems, 3124–3129 of neptunium (IV), 3111t–3112t, 3135–3136 neptunium (VII/VI), 3111t–3112t, 3124–3125 neptunyl (V), 3111t–3112t, 3133–3134 plutonium (IV), 3113t, 3136 plutonium (VII/VI), 3126 plutonyl (VI), 3113t, 3134 of tetravalent ions, 3134–3135 thorium (IV), 3129, 3136–3137 uranium (IV), 3101t–3102t, 3136 uranyl (VI), 3101t–3102t, 3126–3133 Reduced phase, of uranium, 274–280 Reduction of americium, 1330–1331 americium (V), 1335–1337 americium (VI), 1335

Subject Index

I-103

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 of calcium, plutonium production, 2722 of californium, 1548 potentials, 1546–1547, 1547t of cyclopentadienyl complexes, trivalent, 2801–2802 of einsteinium einsteinium (III), 1602, 1607 for metal production, 1590 of lithium, for electrorefining, 2722–2723 of mendelevium, 1635–1636 of neptunium hexafluoride, 733 neptunium (IV), 762 neptunium (V), 762 neptunium (IV) to neptunium (III), 745 potential, 755 by nobelium, 1640 of plutonium by actinide ions, 1133–1137, 1134t–1135t in aqueous solution, 1117–1146 by nonactinide ions, 1137–1143 of uranium, 319 hexafluoride, 562 UO2 solid solutions, 392, 393t by uranium (III), 598 Reduction potentials of actinide elements, 1778, 1779f in water, 3097–3098, 3098t of actinide ions, 2127–2132, 2130f–2131f of neptunium, 1778, 1779f, 2127–2131, 2130f–2131f, 2525, 2525f of plutonium, 1778, 1779f, 2127–2131, 2130f–2131f, 2525, 2525f plutonium (III), 2715, 2716f of uranium, 1778, 1779f, 2127–2131, 2130f–2131f, 2525, 2525f uranium (III), 2715, 2716f Relativistic approaches, for electronic structure calculations, 1902–1914 double groups, 1910–1914 excited electronic states, 1909–1910 Hartree-Fock and density functional approaches, 1902–1904 RECPs, 1907–1909 relativistic effects, 1904–1907 Relativistic effective core potentials (RECPs) alternatives to, 1908 development of, 1908 for electronic structure calculation, 1671, 1907–1909 for element 118, 1729 of uranyl, 1918–1920 Relativistic effects on actinide cyclopentadienyl complexes, 1955 of actinides v. lanthanides, 1898, 1899f on actinocenes, 1949–1952

protactinocenes, 1949–1951 thorocene and uranocene, 1951–1952 of atomic electronic shells, 1666–1669, 1667f–1669f on chemical properties of transactinide elements, 1666–1671 description of, 1666–1669 on electronic structures, 1898–1900 5f electrons, 1898, 1899f calculation inclusion of, 1900 subshell splitting, 1899–1900 QED effect, 1669 quantum-chemical methods for, 1669–1671 spin-orbit splitting, 1668–1669 of superactinide elements, 1733 Relativistic elimination of small components (RESC), for electronic structure calculation, 1908–1909 Relativistic general gradient approximation (RGGA), for DFT, 1671 Relativistic Hartree-Fock (HFR) calculations, of f electrons, 2032, 2034f, 2035 Remote control, for actinide element study, 12, 12f–13f REMPI. See Resonance-enhanced multiphoton ionization RESC. See Relativistic elimination of small components Resistance furnace, for electrorefining, 782, 784f Resistivity tensor, of uranium, 324, 324t Resonance ionization mass spectrometry (RIMS) of actinide elements, 1875–1879, 1877t, 1878f–1879f excitation schemes, 1876–1877, 1877t, 1878f experimental v. predictions, 1878–1879, 1879f of fermium, 1877 ionization energies, 1878 precision of, 1879 applications of, 3321–3320 of berkelium, 1452 for environmental actinides, 3044t, 3047, 3048f experimental setup for, 1876 fundamentals of, 3319–3320, 3320f for mass spectrometry, 3310 of neptunium, 789–790 overview of, 3319 of plutonium, 859 problems of, 3329 of thorium, 60 TIMS v., 3329 for trace analysis, 3319–3322 Resonance ionization spectrometry (RIS), for environmental actinides, 3044t, 3047

I-104

Subject Index

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 Resonance-enhanced multiphoton ionization (REMPI), of uranium dioxide, 1973 Resonant photoemission, of PES, 2336 Resonant X-ray scattering (RXS) description of, 2234 of neptunium dioxide, 2288 neutron scattering v., sample size, 2237–2238 of uranium dioxide, 2281 Respirable release fraction (RRF) of plutonium, 3252–3255, 3254t dioxide, 3254t, 3255 variations in, 3253–3254 RGGA. See Relativistic general gradient approximation Rhizopus arrhizus (RA), for extraction, 2669 RHU. See Radioisotope heater units RIMS. See Resonance ionization mass spectrometry RIS. See Resonance ionization spectrometry RKKY interaction. See Ruderman-KittelKasuya-Yosida interaction RNAA. See Radiochemical neutron activation analysis Roasting functions of, 304 of uranium ore, 304 Rock salt formations, for SNF storage, 1813 Roentgenium chemical methods for, 1720–1721 chemical properties of, 1717–1721 discovery of, 7t, 1653–1654 electronic structures of, 1682–1684 half-life of, 1719 isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, 1720 in aqueous solution, 1774–1776, 1775t production of, 1719–1720 relativistic orbital energies for, 1669f solution chemistry of complexation of, 1689 hydrolysis, 1686–1687, 1687t redox potentials, 1685–1686, 1685f–1686f Room temperature ionic liquids (RTILs) actinides in, 2685–2691 properties of, 2687 description of, 854, 2686–2687 historical development of, 2685–2686 neptunium chemistry in, 2689 plutonium chemistry in, 2689 separation with, 854 separation techniques with, 2689–2691 dissolution, 2690 electrodeposition, 2690–2691

LLE, 2691 precipitation, 2690 uranium chemistry in, 2687–2688, 2689f RRF. See Respirable release fraction RTC. See Recoil Transfer Chamber RTG. See Radioisotope thermoelectric generator RTILs. See Room temperature ionic liquids Rubidium, with thorium sulfates, 105 Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction 5f v. 4f moments in, 2354 magnetic anisotropy with, 2364–2365 Rutherford backscattering (RBS) for environmental actinides, 3059t, 3063–3064, 3064f PIXE with, 3069 Rutherfordine, schoepite and, 289–290 Rutherfordium berkelium–249 in production of, 1447 chemical properties of, 1666, 1690–1702, 1691t historical, 1690–1693 discovery of, 6t, 1653, 1653t electronic structures of, 1676–1682, 1677f–1678f, 1680t–1681t, 1682f half-life of, 1661 hydrolytic behavior of, 1701 ionic radii of, 1674f, 1675–1676, 1676t ionization potential of, 1674, 1674f isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659 oxidation states of, in aqueous solution, 1774–1776, 1775t production of, 1662 relativistic orbital energies for, 1669f solution chemistry of, 1695–1702 anionic species extraction, 1695–1696 cationic species extraction, 1700–1702, 1702f complexation of, 1688–1689 fluoride complexes, 1699–1700 hydrolysis, 1686–1687, 1687t neutral complex extraction, 1696–1699 redox potentials, 1685–1686, 1685f–1686f volatility of, 1664 Rutherfordium tetrabromide, study of, 1693 Rutherfordium tetrachloride historical, 1690 study of, 1693, 1694f Rutherfordium tetrahalides, study of, 1693, 1694f Rutherfordium–257, chemical properties of, 1666 Rutherfordium–260, history of, 1690 Rutherfordium–261 chemical studies of, 1692

Subject Index

I-105

Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440 extraction of, 1695–1696 half-life of, 1661 in seaborgium study, 1710 Rutherfordium–262, seaborgium–266 α−α correlation with, 1708 RXS. See Resonant X-ray scattering Sale´eite at Koongarra deposit, 273 natural occurrence of, 293 uranium in, 259t–269t Salicylates, structural chemistry of, 2439t–2440t Salt roasting, functions of, 304 Samarium, californium v., 1521–1522, 1545, 1548 Satellites, disintegration of, 1806 Sayrite, anion topology of, 283, 284f–285f SBHLW. See Sulfate-bearing high-level waste solutions Scalar-relativistic methods AREP for, 1907–1908 ECPs for, 1906–1907 for ground state calculations, 1900 for thorium carbonyl, 1985 Scanning electron microscopy (SEM), for environmental actinides, 3049t, 3050, 3051f SCF equations. See Self-consistent field equations Schmitterite, as uranyl tellurite, 298 Schoepite at Pen˜a Blanca, Chichuhua District, Mexico, 272–273 rutherfordine and, 289–290 at Shinkolobwe deposit, 273 uranium in, 259t–269t, 287, 289–290 Schro¨dinger equation for actinide metals, 2327 for multiple electrons, 2021–2022 Scintillation detection for berkelium, 1484 gamma-spectrometry and, 3297 for uranium, 635 Seaborgium chemical properties of, 1691t, 1706–1711 discovery of, 6t, 1653, 1653t, 1762 electronic structures of, 1676–1682, 1677f–1678f, 1680t–1681t, 1682f gas-phase chemistry of, 1707–1709 history of, 1706–1707 ionic radii of, 1674f, 1675–1676, 1676t ionization potential of, 1674, 1674f isotopes of, 1657f–1658f nuclear properties of, 1655t–1656t orbital filling in, 1654, 1659

oxidation states of, in aqueous solution, 1774–1776, 1775t relativistic orbital energies for, 1669f solution chemistry of, 1709–1711 complexation of, 1688–1689 redox potentials, 1685–1686, 1685f–1686f Seaborgium–263, study of, 1706–1707 Seaborgium–265 decay products of, 1708–1709 discovery of, 1735 study of, 1707–1708 Seaborgium–266 decay products of, 1708–1709 discovery of, 1735 rutherfordium–262 α−α correlation with, 1708 study of, 1707–1708 Seawater, neptunium in, 782–783 Secondary electron multiplier (SEM), for TIMS, 3313 Secondary electron X-ray absorption spectroscopy (SEXAS), for environmental actinides, 3044t, 3046 Secondary ion mass spectroscopy (SIMS) for environmental actinides, 3059t, 3062, 3063f for mass spectrometry, 3310 Se´elite, uranophane structure in, 295 Selenates, of actinide elements, 1796 Selenides of americium, 1316–1317 of neptunium, 740–741 of plutonium, 1049–1056 preparation of, 1052 properties of, 1055–1056 solid-state structure, 1053–1055, 1053f–1054f thermodynamic properties of, 2203t, 2204–2205 of thorium, 75t, 96–97 of uranium, 414t–417t, 418–420, 420f phases of, 418, 419f preparation of, 418–420 properties of, 414t–417t, 420 Selenites of actinide elements, 1796 of uranium, 268t with alkaline metals, 298–299 natura