Metal-Oxo and Metal-Peroxo Intermediates in Oxidative Catalysis

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This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Professor John T. Groves at Princeton University involving research in three inter-related areas: (1) Oxygen activation and transfer mediated by metalloporphyins, (2) Chemistry and oxidative catalysis by high-valent iron in aqueous solution, (3) Alkene and Alkane functionalization by rhodium and cobalt porphyrins. Oxo-manganese(V) porphyrin complexes have an unusual reactivity profile with more electron deficient porphyrins leading to more stable oxidants. The hypothesis for this unexpected behavior is that spin state crossings and variations in the acidty of metal-coordinated water lead to variations in catalyst activity. Rapid kinetic techniques will be used to test this hypothesis using a related family of Cr, Mn, and Fe catalysts. Oxometalloporphyrins can efficiently transfer their oxo ligand to bromide ion in a rapid and reversible manner. The forward reaction mimics the halide oxidation reaction catalyzed by haloperoxidases, while the reverse reaction is the catalyst activation step in substrate oxygenation by metalloporphyrins. Experiments are described for the complete mapping of the energetics of these reactive intermediates. This information will be used to achieve the catalytic formation of hypochlorite and the oxidation of water. An approach is also being taken to the catalytic anti-Markovnikov hydrofunctionalization of olefins through the analysis of the several reaction steps required to achieve catalysis and developing methods to make these reactions practical. The research aims to discover the basic principles by which chemical catalysis operates and to use those insights to drive the invention of the next generation of catalysts. The effort also aims to train the personnel that are necessary for the nation to achieve the technological advances offered by these discoveries and to train the teachers of science for the future. New discoveries and invention in oxidative catalysis are necessary to address both manufacturing and environmental concerns arising from presently used technologies.