This project supported by the Inorganic Bioinorganic and Organometallic Chemistry Program will support the continuation of studies of transition metal, homogeneous catalysis by Professor A. Sen of the Pennsylvania State University. Professor Sen will perform in-depth investigations of two new catalytic systems that offer promise for selective, metal catalyzed, oxidative functionalization of organic molecules. The first of these systems is the platinum(II) mediated hydroxylation of remote C-H bonds in certain functionalized organic compounds. The second is the rhodium catalyzed hydroxylation and hydroxycarbonylation of C-H and C-C bonds of alkanes, including methane and ethane, using molecular oxygen as the oxidant. The catalyst precursors contain no oxidizable ligands so that there is the possibility that catalyst degradation will not occur. To be addressed in both cases are the structure and reactivity of the organometallic intermediates, the nature of the C-H (C-C) activation step, and the mechanistic origins of the observed selectivities. This research is concerned with the development of homogeneous catalysts based upon transition metals that may allow for the selective functionalization of saturated hydrocarbons. Homogeneously catalyzed reactions typically offer much greater selectivity than heterogeneous reactions, when they can be used. However, only the latter types of catalysts are used industrially to promote reactions of saturated hydrocarbons because known homogeneous catalysts normally are not sufficiently reactive, if they even react. The initial discoveries upon which this research is based suggest that homogeneous catalysts may ultimately be used for the selective functionalization of such molecules. If the catalytic activities are great enough, there is a high probability that commercially viable processes will result.
