Studies of hydrogen-hydrogen and carbon-sulfur bond cleavage; Lewis acid modified molybdenum sulfide complexes; and Syntheses and reactions of pyrrole complexes. Final report

摘要

The reactions of hydrogen with dinuclear cyclopentadienyl molybdenum complexes containing bridging sulfido ligands have been identified, and detailed kinetic and mechanistic studies have been carried out on selected systems. The work has led to a detailed proposal for the mechanism of heterolytic hydrogen activation by these homogeneous dinuclear complexes. The hydrogen activation reactions have been further applied in reactions with heterocycles and other small molecules, and pathways for the cleavage of carbon- nitrogen, carbon-sulfur, and carbon-oxygen bonds have been determined. The studies have established well characterized pathways for these transformations which involve reactions at the sulfido ligands of the complexes. These systems provide potential models for important hydrotreating reactions which occur on heterogeneous metal sulfide catalysts. In a related project fundamental factors which might promote the activation of nitrogen heterocycles in the hydrotreating process have been explored. New transition metal complexes containing pyrrole and indole have been synthesized, and the coordination modes of the cyclic ligands and their resulting reactivity have been characterized. Complexes which activate the rings toward both nucleophilic addition and nucleophilic substitution reactions have been identified, and further reductions of the cyclic ligands have also been observed.