Metal Clusters And Their Reactivity

This book discusses current techniques and instrumentation for cluster chemistry. It addresses both the experimental and theoretical aspects of gas-phase metal cluster reactivities, especially those pertaining to pollution removal, energetic reactions and corrosion and anticorrosion. These metal cluster systems have attracted enormous interest as they display a completely new class of physical, chemical, electronic, magnetic and catalytic properties. As these properties change with size and composition, it can thus be understood how their nature evolves from atoms to bulk solids. The book offers readers a basic understanding of the structural chemistry and reactivity of metal clusters in both gas-phase and wet chemistry. Further, the lessons they learn here regarding metal cluster chemistry will prepare researchers for the study of condensed phase dynamics that pertain to wet chemical synthesis, soft-landing deposition and cluster assembly.

Seven chapters summarize the current status of organometallic cluster chemistry from the viewpoints of synthesis, structure and bonding, ligand substitution reactions, ligand transformations, polyhedral rearrangement, cluster fragmentation reactions, and metal clusters as homogeneous catalysts. An eighth provides an extensive bibliography of reviews for the period from 1965 to 1988. Annotation copyrighted by Book News, Inc., Portland, OR

Transition metal carbonyl clusters (TMCCs) continue to inspire great interest in chemical research, as much for their fascinating structures as for potential industrial applications conferred by their unique properties. This highly accessible book introduces the bonding, structure, spectroscopic properties, and characterization of clusters, and then explores their synthesis, reactivity, reaction mechanisms and use in organic synthesis and catalysis. Transition Metal Carbonyl Cluster Chemistry describes models and rules that correlate cluster structure with electron count, which are then applied in worked examples. Subsequent chapters explain how bonding relates to molecular structure, demonstrate the use of spectroscopic techniques such as NMR, IR and MS in cluster chemistry, and outline the factors contributing to the stability, dynamics and reactivity of clusters. The second part of this book discusses the synthesis and applications of TMCCs. It emphasizes the differences between the reactivities of clusters vs. mononuclear metal complexes, contingent to the availability of multiple-bonding sites and heterosite reactivity. The final chapters discuss reactions in which clusters act as homogeneous catalysts; including discussion on the use of solid and biphasic liquid-liquid supported clusters in heterogeneous catalysts. A useful reference for those commencing further research or post-graduate study on metal carbonyl clusters and advanced organometallic chemistry, this book is also a cornerstone addition to academic and libraries as well as private collections.

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.

Metal clusters, an intermediate state between molecules and the extended solid, show peculiar bonding and reactivity patterns. Their significance is critical to many areas, including air pollution, interstellar matter, clay minerals, photography, catalysis, quantum dots, and virus crystals. In Aromaticity and Metal Clusters, dozens of international experts explore not only the basic aspects of aromaticity, but also the structures, properties, reactivity, stability, and other consequences of the aromaticity of a variety of metal clusters. Although the concept of aromaticity has been known for nearly two centuries, there is no way to measure it experimentally and no theoretical formula to calculate it. In order to gain insight into its exact nature, the authors of this volume examine various indirect characteristics such as geometrical, electronic, magnetic, thermodynamic, and reactivity considerations. The book begins by discussing the evolution of aromaticity from benzene to atomic clusters. Next, more specialized chapters focus on areas of significant interest. Topics discussed include: Computational studies on molecules with unusual aromaticity Electronic shells and magnetism in small metal clusters A density functional investigation on the structures, energetics, and properties of sodium clusters through electrostatic guidelines and molecular tailoring The correlation between electron delocalization and ring currents in all metallic aromatic compounds Phenomenological shell model and aromaticity in metal clusters Rationalizing the aromaticity indexes used to describe the aromatic behavior of metal clusters 5f orbital successive aromatic and antiaromatic zones in triangular uranium cluster chemistry This collection of diverse contributions, composed of the work of scientists worldwide, is destined to not only answer puzzling questions about the nature of aromaticity, but also to provoke further inquiry in the minds of researchers.

The findings reported in this book on the methods of cluster measurements will lead to new avenues using nondestructive mass spectrometry and dipole mass isomers. Much attention is given to the physics and chemistry of fullerenes and nanotubes, including the problems surrounding the formation and growth of nanotubes, electron characteristics of fullerenes, the influence of solvents, simulation of the properties of carbon clusters, etc. Some unique experimental data on the conversion of aerosols into aerogels with the formation of fractal structures is provided. In addition, the book covers one of the most interesting subjects of modern physics -- fractal clusters.

Atomic Clusters with Unusual Structure, Bonding and Reactivity: Theoretical Approaches, Computational Assessment and Applications reviews the latest computational tools and approaches available for accurately assessing the properties of a cluster, while also highlighting how such clusters can be adapted and utilized for the development of novel materials and applications. Sections provide an introduction to the computational methods used to obtain global minima for clusters and effectively analyze bonds, outline experimental approaches to produce clusters, discuss specific applications, and explore cluster reactivity and usage across a number of fields.Drawing on the knowledge of its expert editors and contributors, this book provides a detailed guide to ascertaining the stability, bonding and properties of atomic clusters. Atomic clusters, which exhibit unusual properties, offer huge potential as building blocks for new materials and novel applications, but understanding their properties, stability and bonding is essential in order to accurately understand, characterize and manipulate them for further use. Searching for the most stable geometry of a given cluster is difficult and becomes even more so for clusters of medium and large sizes, where the number of possible isomers sharply increase, hence this book provides a unique and comprehensive approach to the topic and available techniques and applications. Introduces readers to the vast structural and bonding diversity that clusters show and reflects on their potential for novel application and material development Highlights the latest computational methods and theoretical tools available for identification of the most stable isomers and accurate analysis of bonding in the clusters Focuses on clusters which violate the rules established in traditional chemistry and exhibit unusual structure, bonding and reactivity

Cluster chemistry is one of the recent, exciting areas of Inorganic Chemistry. The occurence of molecular clusters, like fullerene C60, constitutes a fundamental feature midway between the chemistry of isolated chemical compounds and that of the elements. Main features of the Cluster Chemistry of both main group and transition metal elements are treated in this book. The author highlights aspects releated to the synthesis, the structure, the special bonding and the reactivity of these species. The book is written as a textbook for senior undergraduate and postgraduate students. References in tables andillustrations permit the reader to reach relevant original information. Professor Gonzalez-Moraga fills a demand for a publication appropriate for dissemination and specially for teaching this exciting subject. From the Contents: Current Concepts in Modern Chemistry - Transition Metal Cluster Chemistry - Main Group-Transition Metal Mixed Clusters - Cluster Compounds of the Main Group Elements - Synthetic Analogues of the Active Sites of Iron-Sulfur Proteins.