Catalytic activity of a new dioxidomolybdenum(vi) complex with a bipodal N2O-donor ligand in sulfur compound oxidation

A new dinuclear dioxidomolybdenum(vi) complex [(MoO2)2(BPA)2(μ-O)] was synthesized by the reaction between the tridentate N2O-donor ligand N-(2-hydroxybenzyl)-N-(pyridin-2-ylmethyl)amine (HBPA) and molybdenum trioxide (MoO3). This complex was analyzed by FT-IR, UV-visible, ESI-MS, elemental (CHN), thermogravimetric and electrochemical analyses. The crystal structure was solved by single crystal X-ray diffraction, which shows two non-equivalent molybdenum(vi) ions bridge-coordinated by an oxido ligand. The complex was studied using DFT calculations, resulting in a molecular structure with a geometry similar to the one obtained by X-ray diffraction. The dinuclear dioxidomolybdenum(vi) complex [(MoO2)2(BPA)2(μ-O)] was evaluated as a catalyst in the reaction involving the oxidation of sulfur compounds, at 25 and 50 °C, using hydrogen peroxide as an oxidant and acetonitrile as a solvent. The catalyst is able to oxidize thioanisole, diphenyl sulfide and dibenzothiophene producing sulfoxide and sulfone with conversions of 94%, 76% and 27%, respectively.