Syntheses, X-ray structures, and catalytic oxidations of dioxomolybdenum(VI) complexes with tridentate benzohydrazones

Two new dioxomolybdenum(VI) complexes, [MoO2L1(CH3OH)]CH3OH (1) and [MoO2L2(CH3OH)] (2), where L-1 and L-2 are dianionic forms of N '-(3-bromo-2-hydroxybenzylidene)-4-hydroxybenzohydrazide and N '-(2-hydroxybenzylidene)-2-hydroxy-3-methylbenzohydrazide, respectively, have been synthesized. The complexes have been characterized by elemental analyzes, IR spectra, molar conductance data, and single crystal X-ray determination. Mo in each complex is octahedral. The crystals of the complexes are stabilized by hydrogen bonds and weak pi center dot center dot center dot pi stacking interactions. The complexes function as effective olefin epoxidation catalysts with hydrogen peroxide as oxidant and sodium hydrogen carbonate as a co-catalyst at room temperature.