Contrasting Extremes Among Homologous Transition Metal Complexes: Eliciting Enhanced Reactivity

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This award in the Inorganic, Bioinorganic, and Organometallic Chemistry Program provides continued support to Dr. Kenneth G. Caulton of the Chemistry Department, Indiana University, for the synthesis and study of complexes of an unusually electron-rich amide ligand, (RNPR2)2N (-), and a carbene ligand, (RNPR2)2C:, that is exceptionally electron withdrawing. Together these two ligand classes are at opposite extremes in terms on electron donating ability. Both ligands will be used to form complexes of mid-transition metals (largely, but not exclusively, Re) and the ability of these complexes to cleave normally unreactive C-H, C-C, and C-F bonds will be evaluated. The underlying hypothesis is that the frontier orbital occupancy and energy of a metal complex can be tailored by varying the electron donor/acceptor ability of the ligand. Thus, the ability of a metal to effect various reactions can be tuned by proper ligand choice. The chemistry to be studied in this proposal is important to obtaining a basic understanding of the behavior of homogeneous catalysts. The goal of this work is to provide a basis for the rational development of new and useful metal-mediated chemical processes. The discovery of new bonding patterns and reactivity modes will be followed by attempts to use this information in the design of new reagents and catalysts for significant chemical processes.