Oxo-carboxylato-molybdenum(VI) complexes possessing dithiolene ligands related to the active site of type II DMSOR family molybdoenzymes.

Spectroscopic and kinetic studies indicate that oxo-carboxylato-molybdenum(VI) bis-dithiolene complexes, (Mo(VI)O(p-X-OBz)L2), have been generated at low temperature as active site structural models for the type II class of pyranopterin molybdenum DMSOR family enzymes. A DFT analysis of low energy charge transfer bands shows that these complexes possess a Mo-S(dithiolene) π-bonding interaction between the Mo(d(xy)) redox active molecular orbital and a cis S(p(z)) donor orbital located on one of the dithiolene ligands.