Small-to-Gigantic Transition Metal Clusters

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The focus of this project in the Inorganic, Bioinorganic and Organometallic Chemistry Program is the the chemistry of transition metal cluster compounds. The project involves the synthesis of new cluster compounds, characterization of their structures and bonding, and studies of their electrochemical and chemical reactivity patterns. A major objective of the research is to provide a unified correlation, based on molecular orbital theory, between molecular geometries and electronic configurations for various kinds of metal clusters, many of which gain and/or lose electrons without rupture of their atomic frameworks. Transition metal cluster compounds comprise an important class of industrial catalysts, and some very large clusters are of intense current interest because they display anomalous magnetic behavior ("quantum size" effects) not seen in small clusters or bulk solids. The main thrust of the project will be the synthesis, isolation and characterization of platinum, nickel and mixed-metal cluster anions, with emphasis on the design of rational synthetic routes to high-nuclearity metal clusters and the development of appropriate separation techniques to enable the isolation and crystallization of pure species for structural and physical studies. Another overall goal is to bridge the gap between discrete and extended solid-state clusters via appropriate oligomerization/condensation reactions. New metal clusters will be synthesized which contain main-group ligands with S, Se, Te, N, P, As or Sb atoms. New metal phosphorus clusters will be prepared by the photolysis of molecular tetraphosphorus. An attempt will be made to use the parameter-free Fenske-Hall model to provide a quantitative electronic basis for the results of crystallographic and spectrocopic analyses of small metal clusters.