1. D.M.P. Mingos, J.E. McGrady, A. L. Rohl Moments of Inertia in Cluster and Coordination Compounds 2. M. Drillon, J. Darriet Progress in Polymetallic Exchange-Coupled Systems, Some Examples in Inorganic Chemistry 3. P. Zanello Stereochemical Aspects Associated with the Redox Behaviour of Heterometal Carbonyl Clusters 4. R. G. Denning Electronic Structure and Bonding in Actinyl Ions 5. M. Evain, R. Brec ANew Approach to Structural Description of Complex Polyhedra Containing Polychalcogenide Anions 6. E. Brese, M. O'Keeffe Crystal Chemistry of Inorganic Nitrides

"Imagination and shrewd guesswork are powerful instruments for acquiring scientific knowledge . . . " 1. H. van't Hoff The last decades have witnessed a rapid growth of quantum chemistry and a tremendous increase in the number of very accurate ab initio calculations of the electronic structure of molecules yielding results of admirable accuracy. This dramatic progress has opened a new stage in the quantum mechanical description of matter at the molecular level. In the first place, highly accurate results provide severe tests of the quantum mecha nics. Secondly, modern quantitative computational ab initio methods can be synergetically combined with various experimen tal techniques thus enabling precise numerical characterization of molecular properties better than ever anticipated earlier. However, the role of theory is not exhausted in disclosing the fundamental laws of Nature and production of ever increasing sets of data of high accuracy. It has to provide additionally a means of systematization, recognition of regularities, and ratio nalization of the myriads of established facts avoiding in this way complete chaos. Additional problems are represented by molecular wavefunctions provided by the modern high-level computational quantum chemistry methods. They involve, in principle, all the information on molecular system, but they are so immensely complex that can not be immediately understood in simple and physically meaningful terms. Both of these aspects, categorization and interpretation, call for conceptual models which should be preferably pictorial, transparent, intuitively appealing and well-founded, being sometimes useful for semi quantitative purposes."

Metal-ligand interactions are currently being studied in different fields, from a variety of points of view, and recent progress has been substantial. Whole new classes of compounds and reactions have been found; an arsenal of physical methods has been developed; mechanistic detail can be ascertained to an increasingly minute degree; and the theory is being developed to handle systems of ever-growing complexity. As usual, such multidisciplinarity leads to great opportunities, coupled with great problems of communication between specialists. It is in its promotion of interactions across these fields that Metal-Ligand Interactions: From Atoms, to Clusters, to Surfaces makes its timely contribution: the tools, both theoretical and experimental, are highly developed, and fundamental questions remain unanswered. The most fundamental of these concerns the nature of the microscopic interactions between metal atoms (clusters, surfaces) and ligands (atoms, molecules, absorbates, reagents, products) and the changes in these interactions during physical and chemical transformation. In Metal-Ligand Interactions, leading experts discuss the following, vital aspects: ab initio theory, semi-empirical theory, density functional theory, complexes and clusters, surfaces, and catalysis.

The fields of hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) continue to attract the attention of researchers in the various disciplines connected to these fascinating problems that represent two of the key outstanding chemical challenges for the petroleum refining industry in view of their very strong environmental and commercial implications. One area that has flourished impressively over the last 15 years is the organometallic chemistry of thiophenes and other related sulfur-containing molecules. This has become a powerful method for modeling numerous surface species and reactions implicated in HDS schemes, and nowadays it represents an attractive complement to the standard procedures of surface chemistry and heterogeneous catalysis, for understanding the complex reaction mechanisms involved in this process. Similar developments have begun to appear in connection with HDN mechanisms, although in a much more modest scale and depth. Some years ago when, encouraged by Prof. B. R. James, this book was planned, several excellent reviews and monographs treating different aspects of HDS were already available including some on the subject of organometallic models. However, it seemed appropriate to try to summarize the most striking features of this chemistry in an updated and systematic way, and inasmuch as possible in connection with the common knowledge and beliefs of the mechanisms of heterogeneous HDS catalysis. Hopefully, this attempt to build some conceptual bridges between these two traditionally separated areas of chemistry has met with some success.

Organometallic chemistry is a well established research area at the interface of organic and inorganic chemistry. In recent years this field has undergone a ren aissance as our understanding of organometallic structure, properties and mechanism has opened the way for the design of organometallic compounds and reactions tailored to the needs of such diverse areas as medicine, biology, materials and polymer sciences and organic synthesis. For example, in the de velopment of new catalytic processes, organometallic chemistry is helping meet the challenge to society that the economic and environmental necessities of the future pose. As this field becomes increasingly interdisciplinary, we recognize the need for critical overviews of new developments that are of broad significance. This is our goal in starting this new series Topics in Organometallic Chemistry. The scope of coverage includes a broad range of topics of pure and applied or ganometallic chemistry, where new breakthroughs are being achieved that are of significance to a larger scientific audience. Topics in Organometallic Chemistry differs from existing review series in that each volume is thematic, giving an overview of an area that has reached a stage of maturity such that coverage in a single review article is no longer possible. Furthermore, the treatment addresses a broad audience of researchers, who are not specialists in the field, starting at the graduate student level. Discussion of possible future research directions in the areas covered by the individual volumes is welcome."

The book highlights some of the important present day roles played by Main Group Elements as well as their emergent new roles in the fields of materials science, chemical synthesis and structure, and biological-cum-environmental aspects. Rarely can one find a single book on Main Group elements that comprehensively discusses their impact on fundamental and applied sciences with a multidisciplinary flavour, while catering for the special interests of a wide cross-section of readers.

Our understanding of the basic processes of crystal growth has meanwhile reached the level of maturity at least in the phenomenological concepts. This concerns for example the growth of pure crystals from a low-density nutrient phase like vapor or dilute solution with various aspects of pattern formation like spiral and layer growth, facetting and roughening, and the stability of smooth macroscopic shapes, as well as basic mechanisms of impurity incorporation in melt growth of (in this sense) simple materials like silicon or organic model substances. In parallel the experimental techniques to quantitatively ana lyze the various growth mechanisms have also reached a high level of reproducibility and precision, giving reliable tests on theoretical predictions. These basic concepts and appli cations to experiments have been recently reviewed by one of us (A. A. C. ) in "Modern Crystallography III. Crystal Growth" (Springer Series on Solid State Sciences, 1983). It has to be emphasized, however, that for practical applications we are still unable to quantitatively calculate many important parameters like kinetic coefficients from first principles. For mixed systems such as complex oxides, solutions and systems with chemi cal reactions, our degree of understanding is even lower. As a few examples for present achievements we note that experiments with vapour and molecular beam condensation of alkali halides confirmed the qualitatively predicted mechanisms of screw dislocations and two-dimensional nucleation for layer-growth.

The second edition of this textbook is identical with its fourth German edi tion and it thus has the same goals: precise definition of basic phenomena, a broad survey of the whole field, integrated representation of chemistry, physics, and technology, and a balanced treatment of facts and comprehen sion. The book thus intends to bridge the gap between the often oversimpli fied introductory textbooks and the highly specialized texts and monographs that cover only parts of macromolecular science. The text intends to survey the whole field of macromolecular science. Its organization results from the following considerations. The chemical structure of macromolecular compounds should be inde pendent of the method of synthesis, at least in the ideal case. Part I is thus concerned with the chemical and physical structure of polymers. Properties depend on structure. Solution properties are thus discussed in Part II, solid state properties in Part III. There are other reasons for dis cussing properties before synthesis: For example, it is difficult to understand equilibrium polymerization without knowledge of solution thermodynamics, the gel effect without knowledge of the glass transition temperature, etc. Part IV treats the principles of macromolecular syntheses and reactions.

1. R.C. Mehrotra, Jaipur, India Present Status and Future Potential of the Sol-Gel Process 2. J. Fricke, A. Emmerling, Wuerzburg, FRG Aerogels - Preparation, Properties, Applications 3. S. Sakka, T. Yoko, Kyoto, Japan Sol-Gel-Derived Coating Films and Applications 4. H. Schmidt, Saarbruecken, FRG Thin Films, the Chemical Processing up to Gelation 5. M. Henry, J.P. Jolivet, J. Livage, Paris, France Aqueous Chemistry of Metal Cations: Hydrolysis, Condensation and Complexation 6. R. Reisfeld, Jerusalem, Israel, C.K. Joergensen, Geneva, Switzerland Optical Properties of Colorants or Luminescent Species in Sol-Gel Glasses

It is presently well recognized that total concentrations of trace elements in any environmental compartment supply insufficient information to understand important phenomena. The distinction and separate analysis of specific chemical species are essential for understanding cycles in the aquatic environment, involving identification and quantification of sources, transport pathways, distributions and sinks, or, in the area of interactions between trace elements and organisms to understand uptake, distribution, excretion mechanisms and effects. In the past, various ways have been developed to determine the nature and extent of complexation of trace elements in natural systems. Approaches have been followed along very different lines. These have not always been fully appreciated by specialists working in even related fields of complexation research. The first International Symposium on the Complexation of Trace metals in Natural Waters was held at the Netherlands Institute for Sea Research (NIOZ, Texel, the Netherlands from 2-6 May 1983. The scientific programme was planned by the chief organizers Drs. C.J.M. Kramer and J.C. Duinker (NIOZ) together with Prof. Dr. H.W. Nurnberg (Kernforschungsanlage, Julich, Federal Republic of Germany) and Dr. M. Branica (Rudjer Boskovic Institute, Zagreb, Yugoslavia).

Ion-exchange Technology I: Theory and Materials describes the theoretical principles of ion-exchange processes. More specifically, this volume focuses on the synthesis, characterization, and modelling of ion-exchange materials and their associated kinetics and equilibria. This title is a highly valuable source not only to postgraduate students and researchers but also to industrial R&D specialists in chemistry, chemical, and biochemical technology as well as to engineers and industrialists.

This book contains the proceedings of the Symposium on FT-IR Characterization of Polymers, which was held under the auspices of the Division of Polymer Chemistry, American Chemical Society (ACS) during the annual ACS meeting in Philadelphia, August, 1984. The content of each paper has been substantially extended from the papers presented during the conference. Due to the accidental, irrecoverable loss of the entire contents of the book by the computer system used for editorial purposes, the publication of this book has been delayed more than one year over the initial scheduled date. It has been a continuous, frustrating experience for the editor as well as for the authors. An extended Murphy's law, -anything can go wrong goes multiply wrong- has been demonstrated in editor's office. It necessitated, otherwise unnecessary, repeated proof reading during which time the editor had valuable experience ~n familiarizing himself with each paper much more than usual. The papers in this book are state-of-the-art even after such a delay. It is the authors pride and integrity toward the quality of each paper that makes the value of this book long lasting, while responsibility of the loss of any timeliness rests at the editor's hand. For the purpose of official records, submission and acceptance dates must be stated. All papers had been submitted by September, 1984, and had been accepted for publication by November, 1984, after the critical review processes.

The aesthetically pleasing molecular architectures of fullerenes and nanotubes are appealing not only because of their beauty but also because they are responsible for the many unprecedented chemical and physical properties of this compound class. Although succession of exciting new discoveries continues unabated fullerene research has become a mature science. It is now possible to predict fullerene chemistry, to design new structure variations like open fullerene clusters, heterofullerenes and endohedral fullerenes, and to develop fullerene materials and modified nanotubes with high potential for technological applications. This volume represents the state-of-the-art of fullerene research, focussing on areas showing high potential for future growth and practical applications. The authors are leading scientists whose groups are making major contributions in the field.