The aim of this book is, as its title suggests, to help sOilleone with little or no knowledge of what thermal analysis can do, to find out briefly what the subject is all about, to decide whether it will be of use to him or her, and to help in getting started on the more common techniques. Some of the less-common techniques are mentioned, but more specialized texts should be consulted before venturing into these areas. This book arose out of a set of notes prepared for courses on thermal analysis given at instrument workshops organized by'the S.A. Chemical Institute. It has also been useful for similar short courses given at various universities and technikons. I have made extensive use ofthe manufacturers' literature, and I am grateful to them for this information. A wide variety of applications has been drawn from the literature to use as examples and these are acknowledged in the text. A fuller list of the books, reviews and other literature ofthermal analysis is given towards the back of this book. The ICTA booklet 'For Better Thermal Analysis' is also a valuable source of information. I am particularly grateful to my wife, Cindy, for typing the manuscript, to Mrs Heather Wilson for the line drawings, and to Professor David Dollimore of the University of Toledo, Ohio, for many helpful suggestions.

Walter C. J. ROSS Emeritus Professor, University of London To paraphrase a statement made by Howard E. Skipper many years ago, 'We cancer chemotherapists have often exploited and overworked our chemist colleagues and they have been conveniently forgotten at award giving times'. This book is an attempt to rectify this and highlight the contribution of the chemist in modifying the structure of various types of agent to enhance their effectiveness as inhibitors of the growth of neoplastic tissues. Cancer chemotherapy is a relatively new discipline, coming later than the introduction of sulphonamides and antibiotics. Modern anti-cancer therapy started with the report of the use of a war gas methyl-di-(2-chloroethyl)amine (HN2) in 1946 for the treatment of Hodgkin's disease. The recognition that this compound acted as a bifunctional alkylating agent under physiological conditions led to the synthesis of a wide range of drugs with similar properties. Amongst these were chlorambucil, melphalan, busulphan, and cyclophos phamide which still find use today. Somewhat later, a range of antibiotics was found to be effective, for example aminopterin (1948) and 6-mercaptopurine (1958) to treat acute leukaemias and 5-fluorouracil and 6-azauracil (1957-8) which were used against a variety of cancers. Since these early days the net has been cast ever wider and, as well as ingenious modifications of the compounds mentioned above, anticancer drugs now include growing classes of compounds ranging from purely synthetic agents to natural products. Many of these are discussed in the present book."

Surface organometallic chemistry is a new field bringing together researchers from organometallic, inorganic, and surface chemistry and catalysis. Topics ranging from reaction mechanisms to catalyst preparation are considered from a molecular basis, according to which the "active site" on a catalyst surface has a supra-molecular character. This. the first book on the subject, is the outcome of a NATO Workshop held in Le Rouret. France, in May. 1986. It is our hope that the following chapters and the concluding summary of recommendations for research may help to provide a definition of surface organometallic chemistry. Besides catalysis. the central theme of the Workshop, four main topics are considered: 1) Reactions of organometallics with surfaces of metal oxides, metals. and zeolites; 2) Molecular models of surfaces, metal oxides, and metals; 3) Molecular approaches to the mechanisms of surface reactions; 4) Synthesis and modification of zeolites and related microporous solids. Most surface organometallic chemistry has been carried out on amorphous high-surf ace-area metal oxides such as silica. alumina. magnesia, and titania. The first chapter. contributed by KNOZINGER. gives a short summary of the structure and reactivity of metal oxide surfaces. Most of our understanding of these surfaces is based on acid base and redox chemistry; this chemistry has developed from X-ray and spectroscopic data, and much has been inferred from the structures and reactivities of adsorbed organic probe molecules. There are major opportunities for extending this understanding by use of well-defined (single crystal) oxide surfaces and organometallic probe molecules."

The rate of advance in areas of science is seldom constant. Usually certain fields effloresce with activity because of the ealization that solutions are possible to long standing important problems. So it is now with asymmetric catalysis, a field which promises to change profoundly the strategic thinking of synthetic chemists. As this Report will show, reagents which can induce catalytic enantiocontrol of chemical transformations could represent the ultimate synthetic method. Nearly all synthetic strategies of complex molecules involve steps which require enantiocontrol and, in many cases, a specific catalytic transformation embodying enan tiocontrol has enormous advantages in terms of the rate and economy of the reaction. Because asymmetric catalysis is in a formative stage, workers with different backgrounds have joined the field. This Workshop had representatives with organometallic, organic, structural, kinetic, enzymatic, microbiological and industrial backgrounds. Each had his own perspective and this Report represents a consensus of this group of eleven people. The result is probably as compre hensive and balanced a view of the subject as is possible at present. It is hoped that those who have until now had but a glancing interest in asymmetric catalysis will find this Report a useful indication of its present state. We believe that asymmetric catalysis will have an increasing impact on the development of chemistry and will eventually dominate much of synthetic and industrial chemistry."

The literature contains tens of thousands of publications and patents devoted to the synthesis, characterization and processing of polymers. Despite the fact that there are more than one hundred elements, the majority of these publications and patents concern polymers with carbon backbones. Furthermore, the limited (by comparison) number of publications on polymers that contain elements other than carbon in their backbones are typically devoted to polymers based on silicon, especially those with Si-O bonds. This disparity is partially a consequence of the dearth of low cost organometallic feedstock chemicals potentially useful for polymer synthesis. It also derives from the lack of general synthetic techniques for the preparation of organometallic polymers. That is, by comparison with the numerous synthetic strategies available for the preparation of organic polymers, there are few such strategies available for synthesizing tractable, organometallic polymers. In recent years, commerical and military performance requirements have begun to challenge the performance limits of organic polymers. As such, researchers have turned to organometallic polymers as a possible means of exceeding these limits for a wide range of applications that include: (1) microelectronics processing (e.g. photoresists) [1]; (2) light weight batteries (conductors and semi-conductors) [2]; (3) non-linear optical devices [3] and, (4) high temperature structural materials (e.g. ceramic fiber processing) [4,5].

Biological inorganic chemistry is a field of research at the interface of inorganic and biological chemistry. The rapidly developing insights into the role of metals in biological systems has far-reaching implications not only for biological science but also for related disciplines, ranging from molecular medicine to the environment. In each volume the reader, whether engaged in chemistry, biochemistry, biology or molecular medicine, receives a comprehensive summary and critical overview of a topic of hight current interest written by leading international experts.

Essential themes in the biochemical cycling of mercury are the relative importance of anthropogenic versus natural sources, transformation and migration processes at the local, regional and global scale, global emission inventories of different mercury sources (both point and diffuse) of both natural and anthropogenic origin. In this regard, Siberia, with its vast territory and variety of natural zones, is of special interest in the global mercury cycle and in terms of the influence of geographical zones on source and sink terms in regional budgets. Siberia contains large areas of mercuriferous belts; natural deposits that emit mercury into the atmosphere and water. Siberian gold has been mined with the use of mercury since the early 1800s. But there, too, huge forest zones and vast areas of tundra and wetland (bogs) can act as efficient sinks for atmospheric mercury. Audience: Environmental scientists, legislators, politicians and the interested citizen wishing to gain a clear picture of the biogeochemical cycling of mercury.

This volume contains the papers and reports presented at the First International Conference on Dye-Protein Interaction, held 24-28 July 1988 at the University of Compiegne, France. This was the first international meeting dealing entirely with dye-protein interaction. The major focus of the conference was on the better understanding of the mechanism of interaction of proteins with different triazine dyes and the synthesis of novel structural dyes having good biomimetic activities. The potentials and limits of their use in biotechnology, mainly for purification, were stressed. Current contributions in developing dye-based affinity methods were highlighted in such areas as affinity partition, affinity precipitation and new support matrices for efficient affinity chromatography, etc. The interrelation between metal chelates and dyes in terms of their interactions with proteins was underlined. It is our belief that this proceedings volume will be a stimulus for broad and creative applications of dye affinity concepts in many fields of biomedical research and biotechnology. for understanding the In addition, a discussion session emphasised the necessity toxicological aspects of these dyes, their fragments and their metabolites. This helped to trigger plans for future work, and this topic will be one of the priorities in a future meeting on dye-protein interactions. C. R. The help of the International Scientific Committee, which included Drs Lowe (UK), G. KopperschHiger (GDR) , E. Stellwagen (USA), D. Thomas (France), G. Birkenmeier (GDR), S. Rajgopal-Narayan (USA), J. P. Dandeu (France), D. Muller (France) and E. Dellacherie (France), in organising this meeting is gratefully acknowledged.

Solid-State NMR is a branch of Nuclear Magnetic Resonance which is presently experiencing a phase of strongly increasing popularity. The most striking evidence is the large number of contributions from Solid-State Resonance atNMR meetings, approaching that ofliquid state resonance. Important progress can be observed in three areas: Methodological developments, applications to inorganic matter, and applications to organic matter. These developments are intented to be captured in three volumes in this series, each of them being devoted to more or less one of these areas. The present volume on Solid-State NMR III is devoted mainly to organic matter. The recent developments of deuteron NMR and their applications are reviewed in the first chapter. Crosspolarization, MAS, and dynamic angle spinning are being explored for enhancement of information and sensitivity. In addition to the analysis of classical relaxation times and modern 2D spectra, detailed dynamic information becomes accessible from investigations of the relaxation time anisotropies. The second chapter examines cross-polarization in static and rotating solids under conditions of spin diffusion and thermal motion. The underlying dipole-dipole interaction is further exploited by the techniques described in the third chapter for studies of polymer-polymer miscibility. Short range techniques are discriminated from long-range techniques based on spin diffusion. The use ofthese techniques is illustrated by a case study ofPMMAJPVF blends. The last chapter addresses novel z methods and applications of two-dimensional exchange NMR for investigations of relative molecular orientations, polymer morphology, molecular dynamics, and macroscopic molecular order."

The design, -synthesis, and selective pyrolytic conversion of organo metallic precursdrs to materials of high purity or specific morphology (for electronic or optical applications), high strength and/or high-temperature stability (for structural or refractory applications) represents a poten tial area of extreme growth at the overlap of chemistry and materials science (materials chemistry). Research in this area is likely to have considerable impact at both the academic and societal levels because it will require development of scientific expertise in areas currently not well understood. Examples include: (1) The thermodynamics of molecular rearrangements in organometallic molecules at temperatures above 200 DegreesC; (2) The electronic properties of amorphous ceramic materials; (3) The phys icochemical properties of ceramic molecular composites; and (4) The optical properties of multicomponent glasses made by sol-gel processing. The opportunity to establish the scientific principles needed to pursue useful research goals in "materials chemistry" requires communica tion between chemists, ceramists, metallurgists, and physicists. To date, there have been few opportunities to create an environment where such communication might occur. The objective of this NATO Advanced Research Workshop was to promote discussions between experts in the varibus disci plines aligned with "materials chemistry. " These discussions were intended to identify the scope and potential rewards of research efforts in the development of: Custom-designed precursors to common and exotic materials, methods of selectively transforming these precursors in high yield to the desired material, and methods of characterizing the final products.

The field of low-dimensional conductors has been very active for more than twenty years. It has grown continuously and both the inorganic and organic materials have remark able properties, such as charge and spin density waves and superconductivity. The discovery of superconductivity at high temperature in copper-based quasi two-dimensional conducting oxides nearly ten years ago has further enlarged the field and stimulated new research on inorganic conductors. It was obviously impossible to cover such a broad field in a ten day Institute and it seemed pertinent to concentrate on inorganic conductors, excluding the high Tc superconducting oxides. In this context, it was highly desirable to include both physics and chemistry in the same Institute in order to tighten or in some cases to establish links between physicists and chemists. This Advanced Study Institute is the continuation of a series of similar ones which have taken place every few years since 1974. 73 participants coming from 13 countries have taken part in this School at the beautiful site of the Centre de Physique des Houches in the Mont-Blanc mountain range. The scientific programme included more than forty lectures and seminars, two poster sessions and ten short talks. Several discussion sessions were organized for the evenings, one on New Materials, one on New Topics and one on the special problem of the Fermi and Luttinger liquids. The scientific activity was kept high from the beginning to the end of the Institute."

This, the second and final volume of Reactions of Coordinated Ligands, describes the chemistry of ligands bound through non-carbon atoms, and of coordinated carbon dioxide. As before, emphasis is on the underlying mechanisms, which provide a unity of understanding for superficially disparate processes. The wide range of topics covered illustrates well both the versatility and the usefulness of coordination chemistry in the controlled activation of ligands. Looking to the future, carbon dioxide is the feedstock of last resort. The homogeneous reduction of dinitrogen to ammonia now seems unlikely to replace the Haber process, but solution reactions also lead to more complex, varied, and valuable products. Nitrogen monoxide, a "non innocent" ligand, impinges as pollutant and reagent. Its rich chemistry stems from its linked roles as three-electron donor, and as extremely powerful -acceptor. In the hydrolysis and condensation of complexed amides, esters etc., metals act both as templates and as tunable and poly functional Lewis acids. Here the control of hydrophobic and steric interactions begins to model the subtle mechanisms of biological specificity. Finally, phosphorus and sulfur are imporant both as ligand atoms in themselves, and as anchors for other functionalities. I would like to thank all those who have been involved in the writing and production of this work, and also my colleagues old and new, at Glasgow and the University of North Texas, for their support. Paul S. Braterman v CONTENTS 1. Reactions of Coordinated Carbon Dioxide 1 J. D. Miller 1."

Combined oxygen, in the form of water, metal oxides, silicates and other oxyions, accounts for about 50% by weight of the earth's crust. The chemistry of this most abundant element has two major aspects: that of water and aqueous solutions of electrolytes, and that of the solid state. The methodology and techniques appropriate for the study of these fields are sufficiently different that there have been very few points of contact between solution- and solid state chemists. One such contact, of great potential value, is provided by the extensive class of polyoxoanions formed by the transition metals of groups 5 and 6. As 'heteropoly and isopoly acids' these polyanions have been known and investigated for more than a century. The pre sent book is an attempt to survey the chemistry, structures, and applications of these species. Although the book forms part of a series in inorganic chemistry, the field of polyoxometalates deserves wider attention, for example, from organic chemists, especially those concerned with homogeneous and heterogeneous catalysis, and from biochemists, solid state- and materials scientists."

In this book, originally published in 1983, a synthesis of old and new notions straddling the disciplines of physics and chemistry is described; and this provides a means of exploiting ligan-field properties of transition-metal and lathanide complexes leading to a quantified chemical insight into the individual metal-ligand interactions in these molecular species. Electronic spectroscopy and the ESR technique are well documented, but there has long been a need for a thorough description of magnetochemistry. A major section of this book therefore provides a details account of the physics and chemistry of paramagnetism. The second main section is concerned with those aspects of ligand-field theory that are required to construct the working composite defining ligand-field analysis. Though the book is intended for the research chemist, the subject matter and level of some of the material is suitable for both advanced undergraduate and postgraduate chemists and solid-state physicists.

This volume reports the main lectures and seminars given at the NATO Advanced Study Institute on Vibronic Processes in Inorganic Chemistry held at Riva del Sole, Tuscany, Italy between 7th and 18th September 1988. In addition to the about 40 hours of lectures repres ented by this volume, a further fifteen lectures on current research topics were given by the other participants. Many factors contributed to the decision to hold this ASI but the final trigger was given at a meeeting in Padova when Marco Bettinelli, Lorenzo Disipio and Gianluigi Ingletto asked me to recommend a text where the diverse conceptual, spectroscopic and structural consequences of the impossibility of treating the motions of the electrons and nuclei independantly in inorganic compounds were presented. There seemed to be no suitable comprehensive text where the relationship between the relatively simple theoretical ideas and the huge range of their application in inorganic chemistry and physics was developed. The Institute and this text are a contribution to filling this gap. Seventy-nine participants from fifteen countries attended the Institute. Topics raised in the lectures and from the participants own research frequently led to discussions which went on long into the night."

Molten salts have been used for many years in a large number of industrial applications, and interest in them has increased mark edly in the present century. There is a vast amount of experi mental data published on molten salt systems, and much of this is due to Russian workers. In 1961 the Russian Academy of Sciences published a manual dealing with work in the period 1886-1955. These were updated in 1979 with the publication of a 3-volume collection of binary phase diagrams. The present volume is a translation of the Russian books but is restricted to the systems involving halides. In order to keep the length of the book within bounds the data have been recast. The Russian work treats each system in detail, giving data, methods of study, references, and figures, where available, all together. In this translation all the information is given, but to keep the length down the methods have been classified, the references collected at the end of the volume, and the data given in tabular form. All the figures for halide systems in the Russian volume are included. In the tables, concentrations are given in mole percent; in some cases these have been converted from weight per cent in the original Russian. Where the Russian work was. in tabular form, these have been translated as given. Where the figures exist, these are referred to in the text."

The nitrides and carbides of boron and silicon are proving to be an excellent choice when selecting materials for the design of devices that are to be employed under particularly demanding environmental and thermal con- tions. The high degree of cross-linking, due to the preferred coordination numbers of the predominantly covalently bonded constituents equalling or exceeding three, lends these non-oxidic ceramics a high kinetic stability, and is regarded as the microscopic origin of their impressive thermal and mechanical durability. Thus it does not come as a surprise that the chemistry, the physical properties and the engineering of the corresponding binary, ternary, and even quaternary compounds have been the subject of intensive and sustained efforts in research and development. In the five reviews presented in the volumes 101 and 102 of "Structure and Bonding" an attempt has been made to cover both the essential and the most recent advances achieved in this particular field of materials research. The scope of the individual contributions is such as to address both graduate students, specializing in ceramic materials, and all scientists in academia or industry dealing with materials research and development. Each review provides, in its introductory part, the chemical, physical and, to some extent, historical background of the respective material, and then focuses on the most relevant and the most recent achievements.

Phase transitions in minerals are of interest to a wide spectrum of scientists - geolo- gists, mineralogists, solid state chemists, and physicists. We have now reached the point where mean field theory or Landau Theory of phase transitions as a function of temperature, pressure, or chemical composition can be usefully applied to natural materials, resulting in an improved understanding of the thermodynamics of signifi- cant constituents of the earth. Given the chemical complexity of so many silicate solid solutions, there are two distinct approaches to the problems posed by common minerals: one is to con- centrate on model compounds which could be synthetic analogs or natural end- members; the other is to work on typical minerals, with all the disorder and inhomogeneity that this implies. Model compounds provide the elements needed to build up a realistic understanding of the thermodynamic behavior of natural inor- ganic materials in all their complexity. In the first part of the book, a number of papers are devoted to structural phase transitions in quartz, Na-and Ca-feldspars, MgSi0 perovskite, and PbI , where Landau Theory and lattice and molecular 3 2 dynamics have been used to explain or predict thermodynamic behavior. A different thermodynamic approach has been used to understand phase separation and atomic ordering in solid solutions such as olivines, pyroxenes, rhombohedral carbonates and oxides. E. Salje (Chapter 1) applies the Landau Theory for the second-order phase transi- tion to the feldspar end-members albite, NaAlSi0 , and anorthite, CaAlSi0 .

This volume documents the proceedings of the Symposium on Polymers in Information Storage Technology held as a part of the American Chemical Society meeting in Los Angeles, September 25-30, 1988. It should be recorded here that this symposium was cosponsored by the Division of Polymeric Materials: Science and Engineering, and the Division of Polymer Chemistry. Polymers are used for a variety of purposes in both optical and magnetic information storage technologies. For example, polymers find applications as substrate, for storing information directly, as protective coating, as lubricant, and as binder in magnetic media. In the last few years there has been a high tempo of research activity dealing with the many ramifications of polymers in the exciting arena of information storage. Concomitantly, we decided to organize this symposium and I believe this was the premier event on this topic. This symposium was conceived and organized with the following objectives in mind: (1) to bring together those actively involved (polymer chemists, polymer physicists, photochemists, surface and colloid chemists, tribo10gists and so on) in the various facets of this topic; (2) to provide a forum for discussion of latest R&D activity in this technology; (3) to provide an opportunity for cross-pollination of ideas; and (4) to identify and highlight areas, within the broad purview of this topic, which needed intensified or accelerated R&D efforts.

All existing introductory reviews of mineralogy are written accord ing to the same algorithm, sometimes called the "Dana System of Mineralogy." Even modern advanced handbooks, which are cer tainly necessary, include basic data on minerals and are essentially descriptive. When basic information on the chemistry, structure, optical and physical properties, distinguished features and para genesis of 200-400 minerals is presented, then there is practically no further space available to include new ideas and concepts based on recent mineral studies. A possible solution to this dilemma would be to present a book beginning where introductory textbooks end for those already famil iar with the elementary concepts. Such a volume would be tailored to specialists in all fields of science and industry, interested in the most recent results in mineralogy. This approach may be called Advanced Mineralogy. Here, an attempt has been made to survey the current possibilities and aims in mineral mater investigations, including the main characteristics of all the methods, the most important problems and topics of mineralogy, and related studies. The individual volumes are composed of short, condensed chap ters. Each chapter presents in a complete, albeit condensed, form specific problems, methods, theories, and directions of investigations, and estimates their importance and strategic position in science and industry."

This volume documents the proceedings of the Second Symposium on Particles on Surfaces: Detection, Adhesion and Removal held as part of the 19th Annual Meeting of the Fine Particle Society in Santa Clara, California, July 20-25, 1988. The premier symposium on this topic was l organized in 1986 and has been properly chronicled . Based on the success of these two events and the high interest evinced by the technical community, we plan to regularly hold symposia on this topic on a biennial basis and the next one is slated for August 20-24, 1990 in San Diego, California. l As pointed out in the Preface to the first volume , the topic of particles on surfaces is of paramount importance in legion of technological areas. Particularly in the semiconductor device fabrication area, all signals indicate that the understanding of the behavior of particles on surfaces and their removal will attain heightened importance in the times to come. As the device dimensions are shrinking at an accelerated pace, so the benign particles of today will become the killer defects in the not too distant future. The tempo of research and development activity in the field of particles on surfaces is very high, and better and novel ways are continuously being devised to remove smaller and smaller particles.

The 6th course of the futernational School of Solid State Physics was held in Erice, Sicily, at the Ettore Majorana Centre for Scientific Culture, 19-29 June, 1995. The course was organized as a NATO Advanced Study Institute and received generous support from NATO's Nanoscale Science Program. This volume is based on the lectures presented during the course. fudispensable for the planning of the summer school was the support of the Director of the Ettore Majorana Centre, Professor A. Zichichi. We wish to express our sincere appreciation to the center staff, Dr. Maria Zaini, Dr. Alberto Gabriele, Dr. Pinola Savalli and Dr. Jerry Pilarski for their expert assistance in all organizational matters. A special word of thanks must go to the director of the International School of Solid State Physics, Professor Giorgio Benedek, not only for his valuable advice in the planning stage, but also for his active participation in the program itself. I would like to thank my coworkers, Stefan Frank, Nikola Malinowski, Renee Stotz, Frank Tast and Kristin Wirth for their valuable assistance in preparing these proceedings of the meeting. The success of a school is, in the last analysis, determined by the inter- est and commitment of the lecturers and participants. I am very grateful to the lecturers for their carefully prepared formal presentations, to the par- ticipants for their contributions to the spontaneous evening "workshops", and to all for their inexhaustible enthusiasm.

The renowned theoretical physicist Victor F. Weisskopf rightly pointed out that a real understanding of natural phenomena implies a clear distinction between the essential and the peripheral. Only when we reach such an understanding - that is to say when we are able to separate the relevant from the irrelevant, will the phenomena no longer appear complex, but intelectually transparent. This statement, which is generally valid, reflects the very essence ofmodelling in the quantum theory of matter, on the molecular level in particular. Indeed, without theoretical models one would be swamped by too many details embodied in intricate accurate molecular wavefunctions. Further, physically justified simplificqtions enable studies of the otherwise intractable systems and/or phenomena. Finally, a lack of appropriate models would leave myriads of raw experimental data totally unrelated and incomprehensible. The present series ofbooks dwells on the most important models of chemical bonding and on the variety of its manifestations. In this volume the electronic structure and properties of molecules are considered in depth. Particular attention is focused on the nature of intramolecular interactions which in turn are revealed by various types ofmolecular spectroscopy. Emphasis is put on the conceptual and interpretive aspects of the theory in line with the general philosophy adopted in the series."

The present book is based on the work of M.N.Bochkarev, G.S.Kalinina, L.N. zakharov and S.Ya.Khorshev. The Russian edition of that book appeared under the same title in 1989 and covered literature data up to the middle of 1986. Since that time the number of publications on this subject increased significantly. In this volume we include all the data published up to the end of 1990, as well as some of the most important relevant articles of 1991. Therefore, this book should be considered as a new book, devoted to the same problems, rather than as just a translation of the mentioned issue. This book deals with compounds of scandium, yttrium, lanthanum and lanthanoids containing direct metal-carbon bond, Le. with the real organometallic complexes of these metals. Besides, the volume includes the rare earth complexes, in which organic ligand is bonded to the metal atom via the atom of another element of the Periodic Table. In other words, the book includes all classes of rare earth organoderivatives. Carboxilates, fl-diketonates and related chelates are the exceptions, because their properties are closer to inorganic compounds and they were fully described elsewhere. It should be noted, that "rare earth elements," "rare earth metals," "lanthanoids" and related terms are used in this book for indicating scandium, yttrium, lanthanum and the following 14 elements of the Periodic Table.

Over the past several decades, vanadium has increasingly attracted the interest of biologists and chemists. The discovery by Henze in 1911 that certain marine ascidians accumulate the metal in their blood cells in unusually large quantities has done much to stimulate research on the role of vanadium in biology. In the intervening years, a large number of studies have been carried out to investigate the toxicity of vanadium in higher animals and to determine whether it is an essential trace element. That vanadium is a required element for a few selected organisms is now well established. Whether vanadium is essential for humans remains unclear although evidence increasingly suggests that it probably is. The discovery by Cantley in 1977 that vanadate is a potent inhibitor of ATPases lead to numerous studies of the inhibitory and stimulatory effects of vanadium on phosphate metabolizing enzymes. As a consequence vanadates are now routinely used as probes to investigate the mechanisms of such enzymes. Our understanding of vanadium in these systems has been further enhanced by the work of Tracy and Gresser which has shown striking parallels between the chemistry of vanadates and phosphates and their biological compounds. The observation by Shechter and Karlish, and Dubyak and Kleinzeller in 1980 that vanadate is an insulin mimetic agent has opened a new area of research dealing with the hormonal effects of vanadium. The first vanadium containing enzyme, a bromoperoxidase from the marine alga Ascophyllum nodosum, was isolated in 1984 by Viltner.