Styrene selective oxidation to benzaldehyde catalyzed by acylhydrazone Mo complexes: reaction parameter effects and kinetics

Abstract Three acylhydrazone molybdenum complexes were synthesized for the first time: [MoO2L1(EtOH)] (1), [MoO2L2(EtOH)] (2), [MoO2L3(EtOH)] (3), [H2L1 = 4-bromo- N’-(3,5-dichloro-2-hydroxybenzylidene)benzohydrazide, H2L2 = N’-(3,5-dichloro-2-hydr- oxybenzylidene)-3-hydroxy-4-methoxybenzohydrazide, H2L3 = N’-(3,5-dichloro-2-hydro- xybenzylidene)-4-trifluoromethylbenzohydrazide]. They were characterized by FT-IR, UV–vis, 1H NMR and thermogravimetric method. Their crystal structures were determined by single crystal X-ray diffraction. The Mo atoms in the complexes were in octahedral coordination, with the equatorial plane defined by the phenolate O, imino N and enalate O atoms of the hydrazone ligands and one oxo group, with the axial positions occupied by one oxo group and one ethanol O atom. The catalytic properties of the three complexes for styrene oxidation were studied.