This award in the Inorganic, Bioinorganic and Organometallic Program is made to Dr. Marcetta Y. Darensbourg of the Chemistry Department, Texas A&M University, for fundamental work on the chemistry of transition metal complexes containing both hydrogen and sulfur-containing ligands. The goal of the research is to find direct evidence for some of the individual steps in S-H, C-S and C-H activation by nickel, iron, and cobalt. Specifically Darensbourg plans to investigate the mechanism of four types of reactions: metal hydrides with organosulfur reagents; dihydrogen release from hydrido-thiolate complexes of iron and nickel; oxidation-reduction of sulfur-bound nickel complexes with various ligand environments; and transition metal promoted heterolysis of metal-proximate C-H bonds. In the studies of sulfur-bound nickel complexes, dependence of the oxidation potential and of the oxidative addition of hydrogen on the presence of sulfur and phosphorus ligands will be investigated. %%% The results of these experiments are relevant to the action of hydrogenase enzymes in methanogenic bacteria and heterogeneous hydrodesulfurization catalysts, in which reaction mechanisms involving simultaneous bonding of sulfur and hydrogen have been proposed.
