Studies on the Chemistry of Platinum Group Element Complexes Relating to Catalysis

点击翻译按钮获取中文摘要

In this project, which is supported by the Inorganic, Bioinorganic and Organometallic Chemistry program, Dr. Richard Eisenberg of the University of Rochester will continue his studies on the chemistry of platinum group element complexes relating to homogeneous catalysis and bond activation. Part one of the project is a continuation of mechanistic studies involving applications of parahydrogen induced polarization (PHIP) to new organometallic systems. This method can permit the detection of new hydride intermediates and may help elucidate the mechanism of hydrogen addition. The activation of hydrogen by oxidative addition to a variety of metal centers will be investigated, including rhodium and iridium complexes capable of intramolecular C-H and C-C activation and tantalocene hydrides. The addition of hydrogen to metal-nonmetal multiple bonds contained in alkylidene, alkylidyne, imido and sulfido complexes will also be studied in an effort to provide proof for a concerted 4-center addition. Catalytic reactions that will be investigated by PHIP include asymmetric hydrogenation and hydroformylation. Part two of the project focuses on the bond activation and catalytic reactions of organometallic systems that exhibit electrophilic or radical character. Cationic diphosphine complexes of Ir(III) and complexes with specifically designed tetradentate ligands will be synthesized. These complexes will have two adjacent labile sites for substrate binding, activation, and coupling. Related electrophilic complexes of Pt and Pd with new diimine and diamine ligands will also be studied. These and related complexes will be screened for reactivity in reactions that include H/D exchange, isomerizations, C-H bond activation, and olefin polymerizataion. Bond activation by odd electron complexes will be studied with new d7 Rh(II) and Ir(II) Schiff base complexes that contain tetradentate N and S donor ligands. The metalloradical reactions that will be studied most extensively are those involving C-H activation of methane, toluene, alkanes, and zylenes, and radical driven polymerizations. A program of research on the chemistry of platinum group element compounds relating to homogeneous catalysis and bond activation will be conducted. Platinum group element complexes include the most widely used catalysts in industry today, and developments in the past decade, particularly with regard to asymmetric catalysis and polymerization catalysis, suggest that this role will increase in the future. This program will advance our understanding of the fundamental transformations that take place at the metal and will help in the design of new important catalysts for the chemical and pharmaceutical industry.