Monooxo Molybdenum(VI) Complexes Possessing Olefinic Dithiolene Ligands: Probing Mo-S Covalency Contributions to Electron Transfer in DMSO Reductase Family Molybdoenzymes

摘要

A monooxo Mo(VI) model complex for the oxidized active site in the DMSOR family of molybdoenzymes has been synthesized and structurally characterized. The compound was obtained from the desoxo Mo(IV) derivative by clean oxygen atom transfer from an amine N–oxide in a manner similar to that observed in the enzyme. A combination of electronic absorption and resonance Raman spectroscopies, coupled with the results of bonding and excited state calculations, has been used to provide strong support for a highly covalent Mo(dxy)-S(dithiolene) π* bonding interaction in the Mo(VI) complex. It is proposed that the resulting Mo-S covalency facilitates electron transfer regeneration of the catalytically competent DMSOR Mo(IV) active site.