Organometallic Chemistry and Photochemistry of Supported and Unsupported Metal-Metal Bonds

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Compounds containing two metal atoms directly bonded to one another are of great current interest because of their catalytic properties and also because of their utility as models of species which occur at the surfaces of heterogeneous catalysts. Many of these metal-metal bonded compounds are highly colored and consequently are susceptible to light induced reactions, so that they have potential for use as catalysts for photochemical or photoelectrochemical applications. The focus of this project is the chemistry and photochemistry of metal-metal bonded organo-transition metal complexes. Two classes of complexes will be studied: i) those which contain unsupported M-M sigma bonds, and ii) those which contain M-M bonds supported by bridging CO, CNR or di-phosphine ligands. New organometallic chemistry will be developed based on excited states of d-10-d-10 binuclear complexes with a single bridging ligand (CO, CNR, or NO+). The roles of excited states in activating the bridging ligand toward bimolecular alkylation or condensation reactions will be determined. The formal ı2+2! photocycloaddition chemistry of olefins, acetylenes, and cumulenes with the bridging ligand will be explored. New classes of bridging ligand cycloaddition reactions of the ı4+2! and ı2+2+2! types will also be developed. The ı4+2} additions of dienes to bridging CO and CNR ligands and ı2+2+2! condensations of olefins with a pair of bridging CO and CNR ligands will be examined. New chemistry of carbon dioxide will be developed, including exploration of its cycloadditions to bridging CO and CNR ligands, as well as O-atom transfers and reductive couplings to oxalate derivatives.