Inorganic Chemistry Concepts – serie

There are both a remote and a proximate history in the development of this book. We would like to acknowledge first the perceptiveness of the technical administrators at RCA Laboratories, Inc. during the 1970s, and in particular Dr. P. N. Yocom. Buoyed up by the financial importance of yttrium oxysulfide: europium as the red phosphor of color television tubes, they allowed us almost a decade of close cooperation aimed at understanding the performance of this phosphor. It is significant that we shared an approach to research in an industrial laboratory which allowed us to avoid the lure of "first-principles" approaches (which would have been severely premature) and freed us to formulate and to study the important issues directly. We searched for a semiquantitative understanding of the properties observed in luminescence, i. e. , where energy absorption occurs, where emission occurs, and with what efficiency this conversion process takes place. We were aware that the nonradi­ ative transition rates found in practice vary enormously with temperature and, for a given activator, with small changes in its environment. We traced the source of this enormous variation to the magnitude of the vibrational overlap integrals, which have strong dependences on the rearrangements occurring during optical transitions and on the vibrational number of the initial electronic state. We were willing to excise from the problem the electronic aspects - the electronic wavefunctions' and their transition integrals -by treating them as parameters to be obtained from the experimental data.

The phenomenon of Extended X-Ray Absorption Fine Structure (EXAFS) has been known for some time and was first treated theoretically by Kronig in the 1930s. Recent developments, initiated by Sayers, Stern, and Lytle in the early 1970s, have led to the recognition of the structural content of this technique. At the same time, the availability of synchrotron radiation has greatly improved both the acquisition and the quality of the EXAFS data over those obtainable from conventional X-ray sources. Such developments have established EXAFS as a powerful tool for structure studies. EXAFS has been successfully applied to a wide range of significant scientific and technological systems in many diverse fields such as inorganic chemistry, biochemistry, catalysis, material sciences, etc. It is extremely useful for systems where single-crystal diffraction techniques are not readily applicable (e.g., gas, liquid, solution, amorphous and polycrystalline solids, surfaces, polymer, etc.). Despite the fact that the EXAFS technique and applications have matured tremendously over the past decade or so, no introductory textbook exists. EXAFS: Basic Principles and Data Analysis represents my modest attempt to fill such a gap. In this book, I aim to introduce the subject matter to the novice and to help alleviate the confusion in EXAFS data analysis, which, although becoming more and more routine, is still a rather tricky endeavor and may, at times, discourage the beginners.

Metal complexes play important roles as catalysts or other participants in synthetic and biological reactions. Substrates and sometimes attacking reagents also are activated through coordination with metal atoms or ions. In these events the natures not only of the central metals but also of ancillary ligands exert important influences on the stability and reactivity of the coordinated substrates. A ligand in general can adopt various coordination modes depending on its chemical environment, thus functioning as a probe. The number of coordination modes increases with increasing complexity of the ligand. In this book it is shown that even the simplest mono- and diatomic ligands such as H, CO, and N2 exhibit a variety of coordination modes, which are related to their reactions. The thiocyanate anion is taken up as a representative of the triatomic ambidentate ligands, and factors influencing the preferences for N- und S-bonding are summarized. Coordination chemistry of ß-dicarbonyl compounds is a highlight of this book. Acetylacetone, one of the most familiar Werner ligands, is shown to favor -carbon and n-allylic bonding in many instances. Its versatile behaviour in changing coordination modes is revealed.

Even brilliant colors are all bound to scatter, Who in our changing world can stay forever? From Iroha-uta, ancient Buddhistic poem of Japan For many years we have been engaged in the preparation and characterization of new metal complexes and chelates, and especially the interpretation of their electronic spectra in solutions. In the course of these studies, we have encountered a number of strange changes in color which occur upon heating, cooling or compressing the solutions, or changing the nature of the solvent. Similar effects of temperature and pressure on the color were often also observed in the solid state. Records of visual observations, spectral measurements, and their interpretations and analyses accumulated each year, until we found ourselves, quite suddenly, in the middle of a fantastic world of color changes - the world of inorganic thermochromism and related chromo tropic phenomena. This book is a result of the reviews by Sone and Prof. S. Utsuno (Kagaku no Ryoiki, 22, 222 (1968); Bunko Kenkyu, 25,123 (1976)), and a series of papers by Fukuda, Sone et al. published in the 1. Inorg. Nucl. Chern., Bull. Chern. Soc. Japan, and various other journals after 1970.

The possibility of stimulated light emission was discussed by Einstein in 1917, eight years before the quantum-mechanical description of energy levels of many-electron systems. Though it is imperative to use samples having optical properties greatly different from the stan­ dard continuous spectrum of opaque objects ("black body" radia­ tion) it is not always necessary to restrict the study to monatomic entities. Thus, spectral lines can be obtained (in absorption and in emission) from lanthanide compounds, containing from one to thir­ teen 4f electrons going from trivalent cerium to ytterbium, that are nearly as sharp as the ones from gaseous atoms. However, the presence of adjacent atoms modifies the simple picture of an isolated electron configuration, and in particular, it is possible to pump excited levels efficiently by energy transfer from species with intense absorption bands, such as the inter-shell transitions of other lanthanides and of thallium(I), lead(II) and bismuth(III) or the electron transfer bands of the uranyl ion or other complexes. On the other hand, it is possible to diminuish the mUlti-phonon relaxation (competing with sharp line luminescence) by selecting vitreous or crystalline materials with low phonon energies. Obviously, one cannot circumvent the conservation of energy by lasers, but they may have unprecedented consequences for the future by allowing nuclear fusion of light elements, effects of non-linear optics and time-resolved spectroscopy, besides the more conventional applications of coherent light beams with negligible angular extension.

As early as 1874 van't Hoff and Le Bel introduced the concept of antipodes for molecules containing an asymmetric carbon atom. This was the first insight into the spacial arrangement of atoms in a mole- cule. These antipodes exhibit opposite optical rotatory power, but it was not possible to determine specific configuration and direction of the rotatory power. The convention of Fischer, however, gained general acceptance. Eighty years later Bijvoet and his co-workers showed that the Fischer convention happens to be in agreement with reality (I 951). Organic stereochemistry is that of tetrahedral carbon atoms, while stereochemistry of co-ordination compounds mainly concerns octahedrally co-ordinated metal atoms. The stereochemistry of octa- hedrons was founded by Werner. In his magnum opus, Neuere Anschauungen auf dem Gebiete der anorganischen Chemie, are sum- marised his highlights on optical isomerism, beginning with the third edition published in 1913. After about forty years, the author and his co-workers determined the absolute configuration of the tris( ethyl- enediamine )cobaJt(III) ion.Thus an absolute basis was given to dis- cuss the-optical activity and molecular structure of co-ordination compounds. This book deals with the absolute stereochemistry of transition- metal complexes, the charge-density distribution in them and their circular dichroism spectra. The book is directed to students of inor- ganic chemistry and to others seeking a general impression of the recent advances in the field.

Hot-atom chemistry is a unique field of chemistry dealing with highly excited chemical species resulting from nuclear reactions or radioactive decay processes. Modern hot-atom chemistry includes a broad range of disciplines such as fundamental studies from physical chemistry of gas-phase energetic reactions to inorganic solid-state chemistry, as well as recent practical applications in life sciences and energy-related research. In spite of the importance of hot-atom chemistry and its appli­ cations, its relevance to the other fields of chemistry and related disciplines has attracted little attention and only books and review articles for dedicated hot-atom chemists have been published to date. In this volume, we illustrate the essential aspects of modern hot-atom chemistry for non-specialists, with considerable emphasis on its applications in the related fields. We sincerely hope that this volume can promote mutual understanding and collaboration between hot-atom chemists and researchers in other disciplines. After a brief introduction (Chap. 1) the 2nd chapter gives the non-specialist an idea of experimental techniques commonly used for the production and analysis of hot chemical species. In Chap. 3, we have explained the concepts of hot-atom reac­ tions in gas, liquid and solid phases with typical examples rather than a comprehensive review of the literature. In view of the current state of accomplishment, the greater part of this chapter is concerned with gas phase studies. Regarding the solid-phase hot­ atom chemistry, we have confined ourselves only to introducing new concepts and discussing modern aspects.

Molecular stereochemistry is a fundamental aspect of all areas of chemistry. It is especially important in inorganic chemistry where the coordination numbers are variable and occasionally quite high. The present book evolved naturally from a series of articles written by Professor Kepert for Progre88 in Inorganic Ohemi8try, elucida­ ting aspects of the stereochemistry of inorganic compounds of co­ ordination numbers 4-12. In the present volume, Professor Kepert has added new sections and synthesized these individual chapters into a unified treatment, updating his references when necessary to the most recent contributions in the literature, and inter­ weaving the various themes as deemed appropriate. The result is a major contribution, describing the stereochemistry of coordi­ nation compounds having both unidentate and multidentate ligands. The viability of the repulsion approach to stereochemistry is tested to the limit in this treatise and shown to be an extremely good way of rationalizing a diverse body of data.

This book is the completely revised and extended version of the German edition "Einfiihrung in die Elektrochemie fester Stoffe" which appeared in 1973. Since then, the subject of the electro­ chemistry of solids has developed further and a large number of new solid electrolytes have been discovered. With the help of solid electrolytes, i. e. solid ionic conductors, galvanic cells are constantly being built for thermodynamic or kinetic investigations and for technical applications. Though the book takes these new develop­ ments into consideration, its main aim is to provide an introduction to the electrochemistry of solids, emphasizing the principles of the subject but not attempting to present a complete account of the existing literature. The latter can be found in handbooks and specialists' reports of conferences in this field; these are referred to in the text. This book is written for scientists and graduate stu­ dents who require an approach that will familiarize them with this field. It is assumed that the reader will be acquainted with the fundamentals of physical chemistry. The various chapters have been written so that most of them can be read independently of each other. Parts which may be omitted during a first reading are printed in small type. Of vital importance for the publication of this English edition have been the comments, suggestions and the help of colleagues and co-workers. I would particularly like to express my thanks to Dr. Holzapfel, Dl'. Lohmar, Professor Mitchell, Dr.

This is a textbook of what is often called magnetochemistry. We take the point of view that magnetic phenomena are interesting because of what they tell us about chemical systems. Yet, we believe it is no longer tenable to write only about such subjects as distinguishing stereochemistry from the measurement of a magnetic susceptibility over a restricted temper­ ature region; that is, paramagnetism is so well-understood that little remains to explore which is of fundamental interest. The major purpose of this book is to direct chemists to some of the recent work of physicists, and in particular to a lengthy exposition of magnetic ordering phenomena. Chemists have long been interested in magnetic interactions in clusters, but many have shied away from long-range ordering phenomena. Now however more people are investigating magnetic behavior at temperatures in the liquid helium region, where ordering phenomena can scarcely be avoided. The emphasis is on complexes of the iron-series ions, for this is where most of the recent work, both experimental and theoretical, has been done. The discussion therefore is limited to insulating crystals; the nature of magnetism in metals and such materials as semiconductors is sufficiently different that a discussion of these substances is beyond our purposes. The book is directed more at the practical experimentalist than at the theoretician.

This book introduces the concept of crystallographic non-rigidity and asymmetry of the transition elements as centralatoms organometallic compounds. This intrinsic behavior ofcentral atoms in condensed matter is quantified by applyingstatistical approach. Averaging of extrinsic factors incrystal structures is tested by using variance analysis.Introductionof the above mentioned concept and applicationsof variance analysis as an approximation for consideringfactors influencing properties of central atomin thecrystal is original and new.

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.