The scope of this paper is to recall fundamental notions of the molecular spectroscopy and dynamics, necessary for discussion of photophysical and photochemical processes in condensed phases. We will thus treat in a more detailed way the specific features which are important for molecular systems strongly interacting with their environment. Other aspects such as the time evolution of isolated molecules, single-level excitation and state-to-state chemistry, important for the gas-phase photophysics are omitted. We start (Sec.2) with a brief description of radiative processes (light absorption and emission) in molecules. In the quantum-mechanical treatment of this problem, the appropriate basis is that of so-called zero-order states, corresponding to the traditional scheme of electronic states (singlets, doublets, triplets etc.) and vibrational levels belonging to each state. The important point will be deduction of selection rules for most radiative transitions. At this stage all molecular states are considered as stationary states. In order to treat the breakdown of simple selection rules and non-radiative transitions between individual molecular states, it is necessary to take into account the mechanisms coupling the zero-order states (Sec.3). We will first focus on intramolecular coupling effects and then discuss the solvent effects on intramolecular relaxation processes. The problem of the non-radiative transfer of the electronic energy between different molecules - closely related to that of the energy dissipation within a single molecule will be treated in Sec.4.

The analogy between the chemistry of molecular transition metal clusters and the processes of chemisorption and catalysis at metal surfaces (the Cluster Surface analogy) has for a number of years provided an interplay between experimental and theoretical inorganic and physical chemists. This collaborative approach has born fruit in the use of well defined modes of metal-ligand bonding in discrete molecular clusters, models for metal-ligand binding on surfaces. Some of the key topics discussed in The Synergy between Dynamics and Reactivity at Clusters and Surfaces are: (1) Mechanisms of the fluxional behaviour in clusters in the liquid phase and the connections with diffusion processes on extended surfaces. The role of metal-metal bond breaking in diffusion. (2) Analogies in the structure of chemisorbed species and related ligands on metallic clusters. (3) Analogies between benzene surface chemistry on extended metal surfaces and on metal surfaces in molecular cluster compounds with particular reference to structural distortions. (4) The role of mobile precursors for dissociation of chemisorption on extended metals and on clusters. Are there analogies in the ligand attachment during cluster compound synthesis? (5) The role of defect sites on metal surfaces in catalyzing chemical reactions and the connection to the special bonding properties of sites on metal clusters having lowest metal-metal coordination. (6) The size of metal clusters needed to mimic surface phenomena on bulk metal surfaces. Different sites needed for different phenomena.

In the last 15 years aqueous organometallic chemistry and catalysis has emerged from being a laboratory curiosity to become an established field of research. Topics reviewed here include mechanistic studies on the effect of water on catalyzed reactions, the preparation of water soluble phosphines as ligands for catalysis, metal catalyzed organic reactions in water (hydrogenation, hydroformylation, carbonylation, olefin metathesis, hydrophosphination, etc.), chiral ligands and enantioselective catalysis, organometallic radical photochemistry in aqueous solutions, bioorganometallic chemistry, organometallic reactions of biopolymers, and catalytic modification of biomembranes. The summary of recent results is supplemented by an assessment of probable future research trends. Audience: Researchers in both academia and industry, as well as graduate students of homogeneous catalysis.

The activation of dioxygen by metal ions has both synthetic potential and biological relevance. Dioxygen is the cleanest oxidant for use in emission-free technologies to minimize pollution of the environment. The book gives a survey of those catalyst systems based on metal complexes which have been discovered and studied in the last decade. They activate molecular oxygen and effect the oxidation of various organic compounds under mild conditions. Much of the recent progress is due to a search for biomimetic catalysts that would duplicate the action of metalloenzymes. Mechanistic aspects are emphasized throughout the book. An introductonary chapter reviews the chemistry of transition metal dioxygen complexes, which are usually the active intermediates in the catalytic reactions discussed. Separate chapters are devoted to oxidation of saturated, unsaturated and aromatic hydrocarbons, phenols, catechols, oxo-compounds, phosphorus, sulfur and nitrogen compounds.

The serious study of the reaction mechanisms of transition metal com plexes began some five decades ago. Work was initiated in the United States and Great Britain; the pioneers ofthat era were, inalphabetical order, F. Basolo, R. E. Connick, 1. O. Edwards, C. S. Garner, G. P.Haight, W. C. E. Higgision, E.1. King, R. G. Pearson, H. Taube, M.1. Tobe, and R. G. Wilkins.A larger community of research scientists then entered the field, many of them stu dents ofthose just mentioned. Interest spread elsewhere as well, principally to Asia, Canada, and Europe. Before long, the results ofindividual studies were being consolidated into models, many of which traced their origins to the better-established field of mechanistic organic chemistry. For a time this sufficed, but major revisions and new assignments of mechanism became necessary for both ligand sub stitution and oxidation-reduction reactions. Mechanistic inorganic chemistry thus took on a shape of its own. This process has brought us to the present time. Interests have expanded both to include new and more complex species (e.g., metalloproteins) and a wealth of new experimental techniques that have developed mechanisms in ever-finer detail. This is the story the author tells, and in so doing he weaves in the identities of the investigators with the story he has to tell. This makes an enjoyable as well as informative reading."

Contents: Kilian Muniz: Transition Metal Catalyzed Electrophilic Halogenation of C-H bonds in alpha-Position to Carbonyl Groups; Arkadi Vigalok * and Ariela W Kaspi: Late Transition Metal-Mediated Formation of Carbon-Halogen Bonds; Paul Bichler and Jennifer A. Love*: Organometallic Approaches to Carbon-Sulfur Bond Formation; David S. Glueck: Recent Advances in Metal-Catalyzed C-P Bond Formation; Andrei N. Vedernikov: C-O Reductive Elimination from High Valent Pt and Pd Centers; Lukas Hintermann: Recent Developments in Metal-Catalyzed Additions of Oxygen Nucleophiles to Alkenes and Alkynes; Moris S. Eisen: Catalytic C-N, C-O and C-S bond formation promoted by organoactinide complexes."

Alexander L. Reznichenko and Kai C. Hultzsch: Catalytic -Bond Metathesis Zhichao Zhang, Dongmei Cui, Baoli Wang, Bo Liu, Yi Yang: Polymerization of 1,3-Conjugated Dienes with Lanthanide Precursors Frank T. Edelmann: Homogeneous Catalysis using Lanthanide Amidinates and Guanidinates Tianshu Li, Jelena Jenter, Peter W. Roesky: Rare Earth Metal Post-metallocene Catalysts with Chelating Amido Ligands

Zeolites, with their crystalline microporous structures, are cordial hosts to a wide variety of guests. However, it was the abrupt and unexpected departure of one of these guests (water) from a host (stilbite) on heating which led Cronstedt, in 1756, to coin the term "zeolite" (from the Greek meaning "boiling stone") to describe this material. Since that time, approximately 40 different naturally-occurring zeolites have been discovered on earth. Recent studies of meteorite compositions have shown that these guest-host materials (e. g. , sodalite) occur in other parts of the universe as well. However, it wasn't until the twentieth century that synthetic routes to zeolites and other non-aluminosilicate molecular sieves were discovered. In addition, with the development of X-ray diffraction and the various spectroscopies, better understanding of the nature of the cavities, cages, and channels of these materials has led to the industrial exploitation of their guest-host properties. The world of zeolites has now expanded into a greater than 2 billion pound per year business, with major applications in detergent formulations, catalysis, and as adsorbents and desiccants. Their economic impact is difficult to determine; however, the improvement in gasoline yields alone (from catalytic cracking) must account for hundreds ofbillions ofdollars in increased GDP. In this volume, we have brought together a sampling of recent developments in various areas of guest-host or inclusion chemistry in zeolites.

Homogeneous catalysis plays an important role both in the laboratory and in the industry. Successful applications in industry involve new polymerisation processes with complexes of zirconium and related metals, new carbonylation processes employing palladium and rhodium, ring opening polymerisations, and new enantioselective isomerisation catalysts as in the preparation of menthol. Also in the synthesis of organic compounds in the laboratory highly selective homogeneous catalysts represent an irreplaceable part of the toolbox of the synthetic chemist. Examples of such reactions are cross-coupling (Ni, Pd), nucleophilic substitution of allylpalladium complexes, Heck reactions (Pd), asymmetric epoxidation, Wacker type reactions (Pd), asymmetric hydrogenations (Rh, Ru), reactions of chromium complexes, enantioselective reactions with Lewis acids, reactions with the McMurry reagent, etc. There is hardly any multistep organic synthesis that does not involve one of these metal catalysed reactions. Most of these catalysts have been developed by empiricism. The metal catalysed processes consist of a series of elementary steps which often have been studied in isolation in organometallic chemistry. The knowl- edge of such elementary steps - effect ofligands, anions, coordination number, valence states - has greatly contributed to the development of improved cata- lysts for the reactions mentioned above. In addition to the empirical approach theoretical methods have given support and guidance to the development of improved processes. Often the key steps of a cycle escape from a direct ob- servation and then theoretical contributions are even more wanted.

Arvind Kumar, Shih-Sheng Sun, and Alistair J. Lees: Photophysics and Photochemistry of Organometallic Rhenium Diimine Complexes; Conor Long: Photophysics of CO Loss from Simple Metal Carbonyl Complexes; Antonin Vlcek Jr: Ultrafast Excited-State Processes in Re(I) Carbonyl-Diimine Complexes: From Excitation to Photochemistry; Kenneth Kam-Wing Lo: Exploitation of Luminescent Organometallic Rhenium(I) and Iridium(III) Complexes in Biological Studies; Maria L. Muro, Aaron A. Rachford, Xianghuai Wang, and Felix N. Castellano: Platinum II Acetylide Photophysics; Andreas F. Rausch, Herbert H. H. Homeier, and Hartmut Yersin: Organometallic Pt(II) and Ir(III) Triplet Emitters for OLED Applications and the Role of Spin Orbit Coupling: A Study Based on High-Resolution Optical Spectroscopy."

Contents: Yves Canac and Remi Chauvin: Neutral eta1-carbon ligands: beyond carbon monoxide; Esteban P. Urriolabeitia: Ylide Ligands; Wolfgang Petz and Gernot Frenking: Carbodiphosphoranes and related ligands; Mareike C. Jahnke and F. Ekkehardt Hahn: Chemistry of N-Heterocyclic Carbene Ligands; Tsuyoshi Kato, Eddy Maerten, Antoine Baceiredo: Non-NHCs stable singlet carbene ligands; Victorio Cadierno, Sergio E. Garcia-Garrido: All-Carbon-Substituted Allenylidene and Related Cumulenylidene Ligands; Victorio Cadierno, Sergio E. Garcia-Garrido: Heteroatom-Conjugated Allenylidene and Related Cumulenylidene Ligands."

S. Di Bella, C. Dragonetti, M. Pizzotti, D. Roberto, F. Tessore, R. Ugo: Coordination and Organometallic Complexes as Second-Order Nonlinear Optical Molecular Materials.- M. G. Humphrey, M.P. Cifuentes, M. Samoc: NLO Molecules and Materials Based on Organometallics: Cubic NLO Properties.- L. Murphy, J. A. G. Williams: Luminescent Platinum Compounds: From Molecules to OLEDs. - Z. Liu, Z. Bian, C. Huang: Luminescent Iridium Complexes and Their Applications.- N. C. Fletcher, M. C. Lagunas: Chromo- and Fluorogenic Organometallic Sensors.- V. Guerchais, H. Le Bozec: Metal Complexes Featuring Photochromic Ligands.

217 2. COPOLYMERIZATION OF PROPENE OR HIGHER I-ALKENES WITH 218 CARBON MONOXIDE 2. 1. Ligands and polymerization conditions 218 2. 2. Spiroketal formation 221 2. 3. Enantioselectivity 222 2. 4. Higher I-Alkenes 226 3. COPOLYMERIZATION OF STYRENE OR ITS DERIVATIVES WITH 226 CARBON MONOXIDE 4. COPOLYMERIZATION OF OTHER OLEANS WITH CARBON MONOXIDE 230 5. ASYMMETRIC TERPOLYMERIZATION OF MORE THAN Two KINDS OF 232 OLEFINS WITH CARBON MONOXIDE 6. POLYKETONE CONFORMATION 233 7. CONCLUSION 234 Chapter 8. Chain Propagation Mechanisms 237 Ayusman Sen 1. INTRODUCTION 237 2. PALLADIUM (II) BASED SYSTEMS 238 3. NICKEL (II) BASED SYSTEMS 256 4. RHODIUM (I) BASED SYSTEMS 257 5. CONCLUSION 261 Chapter 9. Theoretical Studies on Copolymerization of Polar Monomers 265 Peter Margl, Artur Michalak, and Tom Ziegler 1. INTRODUCTION 265 2. COPOLYMERIZATION OF CARBON MONOXIDE WITH ETHYLENE 267 2. 1. Experimental and calculated rates for the insertion processes for 267 copolymerization catalysed by Pd(II) systems. 2. 2. A more detailed look at the productive and unproductive cycles 270 in copolymerization catalysed by Pd(II) complexes. 2. 2. 1. The productive cycle 270 2. 2. 2. C2H4 misinsertion into an ethylene terminated polyketone 275 chain 2. 3. Experimental and calculated rates for the insertion processes for 277 alternating copolymerization catalyzed by Ni(II) systems 3. COPOLYMERIZATION OF OLEFINS WITH POLAR MONOMERS OTHER 280 THAN CO 3. 1. Preferred binding mode of oxygen containing monomers 282 3. 2. Preferred binding mode of nitrogen containing monomers 285 3. 3.

A very large number of organo derivatives is formed by the Group IV ele ments silicon, germanium, tin, and lead. In comparing the general properties of these elements, Table 1. 1 shows that the first ionization energies decrease (though not in a regular way) with increase in size and atomic number, con sistent with the general increase in metallic character of the elements. Electro negativity values (which have been the subject of considerable controversy) show no clear trend. Although purely inorganic compounds of tin(n) and leaden) are well known, almost all organo Group IV derivatives show an oxidation state of IV. Bonds to carbon become weaker on passing from silicon to lead, as do the element-element bonds themselves. With any particular element M (M = Si, Ge, Sn, or Pb), there is a small decrease in bond energy in the order: M-Ph > M - Me > M - Et. Although accurate data for organo derivatives are lacking, strengths of bonds to other elements probably decrease in the order: M-F> M-O > M-CI > M-H ~ M-N ~ M-S ~ M-Br > M-I, while for a particular element X, the order is: Si-X > Ge-X > Sn-X > Pb-X. It is therefore understandable that reactions leading to Si-F, Si-O, or Si-CI bonds are especially favoured in a thermodynamic sense.

When this book was first conceived as a project the expanding interest in the clinical use of platinum and gold complexes made a survey of the relevant biological properties of metal complexes timely and appropriate. This timeliness has not diminished during the gestation and final publica tion of the manuscript. The introduction contains an explanation of the layout and approach to the book, which I wrote as an overall survey of the wide variety of biological properties of metal complexes. Hopefully, the reader will see the parallels in mechanisms and behavior, even in different organisms. The writing was considerably helped by the enthusiasm and confidence (totally unearned on my part) in the project of Professor Brian James and lowe him my special thanks. I also owe a great debt of gratitude to my colleagues, and especially to Eucler Paniago, of the Universidade Federal de Minas Gerais, for their comprehension and for the initial leave of absence which allowed me to begin the project. To those who read some or all of the manuscript and made suggestions, Bernhard Lippert, Kirsten Skov, and Tom Tritton, as well as the editor's reviewer I am also grateful. As usual, the final responsibility for errors or otherwise rests with the author."

Metal-Ligand Interactions - Structure and Reactivity emphasizes the experimental determination of structure and dynamics, supported by the theoretical and computational approaches needed to establish the concepts and guide the experiments. Leading experts present masterly surveys of: clusters, inorganic complexes, surfaces, catalysis, ab initio theory, density functional theory, semiempirical methods, and dynamics. Besides the presentations of the fields of study themselves, the papers also bring out those aspects that impinge on, or could benefit from, progress in other disciplines. Refined in the fire of an interactive and stimulating conference, the papers presented here represent the state of the art of current research.

This book brings together and makes easily accessible data on flash points pres- ently listed in the standard references, plus many values measured in American indus- trial laboratories and European data as represented by the Fluka catalog and by values given in Nabert and Schoen. It is a collection that should be useful to those involved in manufacturing, handling, and shipping the many organics and organometallics now in production. The author would like to thank David Harvey, President, and Chuck Pouchert, of Aldrich Chemical Company, for permission to use their material and for provid- ing a computer printout of some six thousand chemicals listed in the Aldrich cata- log. Flash points for most of these chemicals were measured in the Aldrich laboratories and are not available elsewhere. Thanks are due also to Dr. Marjan Bace of Elsevier Science Publishing Co., Inc., who recognized the need for a handbook on flash points and handled the pub- lishing arrangements. Particular thanks go to my wife, Mary, who prepared the entire camera-ready manuscript. Richard M. Stephenson The University of Connecticut Storrs, Connecticut December, 1986 v Introduction Flash points are of particular importance to those involved with the handling and ship- ping of organics and organometaliics. As each country has its own shipping regula- tions, this can be a real problem for international shippers. Many flash points have been determined by individual chemical manufacturers in answer to their own needs.

An overview of modern organometallic thermochemistry, made by some of the most active scientists in the area, is offered in this book. The contents correspond to the seventeen lectures delivered at the NATO ASI Energetics of Organometallic Species (Curia, Portugal, September 1991), plus three other invited contributions from participants of that summer school. These papers reflect a variety of research interests, and discuss results obtained with several techniques. It is therefore considered appropriate to add a few preliminary words, attempting to bring some unity out of that diversity. In the first three chapters, results obtained by classical calorimetric methods are described. Modern organometallic thermochemistry started in Manchester, with Henry Skinner, and his pioneering work is briefly surveyed in the first chapter. The historical perspective is followed by a discussion of a very actual issue: the trends of stepwise bond dissociation enthalpies. Geoff Pilcher, another Manchester thermochemist, makes, in chapter 2, a comprehensive and authoritative survey of problems found in the most classical of thermochemical techniques - combustion calorimetr- applied to organometallic compounds. Finally, results from another classical technique, reaction-solution calorimetry, are reviewed in the third chapter, by Tobin Marks and coworkers. More than anybody else, Tobin Marks has used thermochemical values to define synthetic strategies for organometallic compounds, thus indicating an application of thermochemical data of which too little use has been made so far.

Born and initially developed in various industrial laboratories, mainly in U.S.A. and Gennany, homogeneous phase catalytic carbon monoxide hydrogenation and alcohols and their derivatives carbonylation and homologation, have generally been considered and reviewed separately in the course of their 40 years history without concern for common aspects in the chemical transfonnations and in catalysis. Thanks to researchers of Japanese companies participating in the National C 1 Chemistry Project (1980-1987) the scientific and technical approaches in this field have been unified and applied in parallel, in the light of some common aspects of the chemical reactions and mechanisms. Now, at a moment when research seems becahned, a general presentation and discussion of the most recent topics might be an useful basis for further development of this chemistry. To delimit and simplify the discussion of the chemical aspects and the nature of the catalysts involved, the present review is limited to reactions employing homogeneous metal complexes for the direct conversion of syngas to oxygenates and to the hydrocarbonylation of these last to homologous derivatives. Since the previous practically contemporary reviews by Dombek [in Adv. Organomet. Chern. (1983)] on CO hydrogenation and by the present authors [in Asp.Homog.Catal.(Reidel Pu.l984)] on alcohol homologation fully cover the literature up to 1982, here we mainly refer to work done after 1982, and consider the cited reviews as covering the historical development of research in the 1940- 1980 period.

For several years, the two parallel worlds of Molecular Conductors in one hand and Molecular Magnetism in the other have grown side by side, the former essentially based on radical organic molecules, the latter essentially based on the high spin properties of metal complexes. Over the last few years however, organometallic derivatives have started to play an increasingly important role in both worlds, and have in many ways contributed to open several passages between these two worlds. This volume recognizes this important emerging evolution of both research areas. It is not intended to give a comprehensive view of all possible organometallic materials, and polymers for example were not considered here. Rather we present a selection of the most recent research topics where organometallic derivatives were shown to play a crucial role in the setting of conducting and/or magnetic properties in crystalline materials. First, the role of organometallic anions in tet- thiafulvalenium-based molecular conductors is highlighted by Schlueter, while Kubo and Kato describe very recent ortho-metalated chelating ligands appended to the TTF core and their conducting salts. The combination of conducting and magnetic properties and the search for p-d interactions are analyzed in two comp- mentary contributions by Myazaki and Ouahab, while Valade focuses on the only class of metal bis(dithiolene) complexes to give rise to superconductive molecular materials, in association with organic as well as organometallic cations.

There are only few topics in organometallic chemistry, which have stimulated research activities in as many areas, as transition-metal carbene (alkylidene) complexes. About 25 years after the first planned synthesis of a carbene complex in E.O. Fischer's laboratory in Munich the NATO Advanced Research Workshop on Transition-Metal Carbene Complexes was the first meeting which, brought together scientists from different disciplines to discuss inorganic, organic, theoretical structural catalysis-related aspects of metal carbene chemistry. The 70th birthday of Professor E.O. Fischer was a good occasion for this enterprise. The organizers of the meeting (K.D. Dotz, Marburg; F.R. KreiBl, Munchen; U. Schubert, Wurzburg) were encouraged by the fact that most of the leading scientists in this area were able to participate in the workshop. The very high standard of the contributions is reflected in this book, which contains papers from the majority of the participants. The Proceedings show the state of the art in metal carbene chemistry and will hopefully be a landmark in the development of this area of chemistry. Generous financial support for the workshop and for the preparation of this book was provided by the Scientific Affairs Division of NATO and some companies. The organizers also acknowledge the efforts of the staff of the Bildungs zentrum der Hans-Seidel-Stiftung in Wild bad Kreuth for creating a pleasant and stimulating atmosphere during the conference."

Well tailored metal catalysts are catalysts of the new generation resulting from scientific development at the boundary between homogeneous and hetero- geneous chemistry. The main factors involved in making tailored metal catalysts are not those of traditional impregnation in which the chemistry is in general unknown and ill-defined, or of simple ion exchange which involves long-range forces with little control on the local structure through definite and special bond direction. Tailored Metal Catalysts thus has a rather different emphasis from normal review publications in the field of catalysis. Here we concentrate more on the distinct surface chemistry and catalytic properties of important established materials with well-characterized active structures or precursors, although at the same time providing a systematic presentation of relevant data. Many pioneering works have been undertaken in the field of tailored metal catalysts since the early research on polymer-attached homogeneous metal complexes by the British Petroleum Company Ltd. and the Mobil Oil Corpora- tion around 1969; transition metal complexes attached on polymers by Grubbs (1971), Heinemann (1971), Manassen (1971), Pittman (1971), Bursian et al. (1972), Kagan (1973), Bailar (1974); transition metal complexes attached on inorganic oxides by Allum et al. (1972), Ballard (1973), Candlin and Thomas (1974), Murrell (1974), Yermakov (1974); metal carbonyls/polymers by Moffat (1970); metal carbonyls/inorganic oxides by Parkyns (1965), Davie et al. (1969), Banks et al. (1969), Howe (1973), Burwell (1975); metal carbonyl clusters/ polymers by Colhnan (1972); metal carbonyl clusters/inorganic oxides by Robertson and Webb (1974), Anderson (1974), Smith et al. (1975).

It is now IS years since the first patents in polymer supported metal complex catalysts were taken out. In the early days ion-exchange resins were used to support ionic metal complexes. Soon covalent links were developed, and after an initially slow start there was a period of explosive growth in the mid to late 1970s during which virtually every homogeneous metal complex catalyst ever reported was also studied bound to a support. Both polymers and inorganic oxides were studied as supports, although the great preponderance of workers studied polymeric supports, and of these polystyrene was by far the commonest used. This period served to show that by very careful design polymer-supported metal complex catalysts could have specific advantages over homogeneous metal complex catalysts. However the subject was a complicated one. Merely immobilising a successful metal complex catalyst to a functionalised support rarely yielded other than an inferior version of the catalyst. Amongst the many discouraging results of the 1970s, there were more than enough results that were sufficiently encouraging to demonstrate that, by careful design, supported metal complex catalysts could be prepared in which both the metal complex and the support combined together to produce an active catalyst which, due to the combination of support and complex, had advantages of activity, selectivity and specificity not found in homogeneous catalysts. Thus a new generation of catalysts was being developed.

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.