New molybdenum(VI) complex with ONS-donor thiosemicarbazone ligand: Preparation, structural characterization, and catalytic applications in olefin epoxidation

New dioxomolybdenum(VI) complex was prepared by reacting 1-(2,4-dihydroxybenzylidene)-N-methyl-N-phenylthiosemicarbazone (H2L) as ligand and [MoO2(acac)2] in acetonitrile solution. The doubly deprotonated ligand is coordinated to molybdenum through sulfur atom, hydrazinic nitrogen atom and phenolic oxygen atom. The resulting complex with the formula [MoO2L(CH3CN)] which contains an acetonitrile molecule in sixth site of coordination, was characterized by elemental analyses, 1H NMR, IR and electronic spectroscopic studies and single crystal X-ray diffraction analysis. This complex was tested as a catalyst for the homogeneous epoxidation of olefins using tert-butyl hydrogen peroxide (TBHP) as an oxidant. The catalyst shows efficient reactivity in the olefins epoxidation reactions giving high yield and selectivity under atmospheric conditions, in most cases.