Reactions and Properties of Molybdenum Bis(dithiolene) Complexes Based on Bis(trifluoromethyl) Dithiolene and Labile Ligands.

摘要

Metal dithiolenes [M(S2C2R2)n] have been studied for decades since their discovery due to their interesting spectroscopic, redox, biological and catalytic properties.;S2C2(CF3)2-containing complexes have been studied but there is still much left unexplored due to the difficulty of obtaining the precursors and synthesizing the ligand. We present a synthetic method that uses easily obtained precursors and we built a relatively inexpensive apparatus to safely isomerize and react the gaseous intermediates.;Molybdenum disulfide is used extensively in the petrochemical industry as catalyst for hydrodesulfurization of petroleum resources. We use dithiolenes to create homogenous structural model complexes of the proposed active sites of the molybdenum disulfide catalyst. We also experimentally determine competitive binding affinities for dihydrothiophene and tetrahydrothiophene, and explore some basic catalytic properties.;Dithiolenes undergo reactions with alkenes to form new bonds. We present a new dithiolene reaction where it is attacked by a nucleophile (triphenylphosphine) to create a zwitterionic ligand as well as open an active site on a previously coordinatively saturated molybdenum tris(dithiolene). This technique is used to create a structural model complex for DMSO reductase and produce a pre-catalyst for that same reaction.;After the determination that the actual catalyst for previously observed activity was a molybdenum bis-dithiolene complex, kinetic determination experiments were performed to elucidate the mechanism. Kinetic investigations suggest the binding of the phosphine oxide created from the use of triphenylphosphine as the oxygen acceptor competes with DMSO in the binding to the active site of the molybdenum bis(dithiolene). Additionally, the removal of oxygen from DMSO using the catalyst appears to involve a polar transition state.