Role of Metal Sulfides in Carbon-Heteroatom Bond Cleavage

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Dr. Mary Rakowski-DuBois of the Chemistry Department, University of Colorado at Boulder, is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program for investigation of C=O, C-S, and C-N bond cleavage reactions promoted by transition metal complexes containing sulfide ligands. In the case of C=O, for example, it is expected that carbon monoxide would insert into an SH bond of an SH ligand which serves as a bridge for a molybdenum dimer. The formylthiolate thus produced is susceptible to reductive cleavage of the C=O bond by hydrogen. This could model a first step of the conversion of CO to methane, a reaction not commonly promoted by transition metal complexes, and here promoted by bonding to sulfur rather than to the metal. This study might provide insight into the mechanism of CO reduction catalyzed by heterogeneous molybdenum sulfides. In studies of C-N bond cleavage by hydrogen, the sulfided metal complexes would serve as models of the heterogeneous catalysts used in commercial HDN (hydrodenitrogenation) processes. In addition to the reactions described above, novel complexes containing Ir, Rh, Re, Mo, and Mo-Cr and a variety of sulfur- and nitrogen-containing ligands will be prepared. %%% This project is expected to provide insight into the reactions of transition metal complexes with small molecules, which are important in the use of such complexes as heterogeneous and homogeneous catalysts. Specifically, these studies may provide information pertinent to understanding the behavior of commercial heterogeneous catalysts used for hydrodenitrogenation.