Oxidovanadium(IV) complexes with tridentate N-heterocycle ligands: Synthesis, structure, and efficient catalyst for cyclohexane oxidation to cyclohexanone

A series of coordination oxidovanadium(IV) complexes: [VOSO4 (bpz-eaT)]·C4H6O4 (1), [VOSO4(bpz-eaT)]·0.5(C10H18O4) (2) and [VOSO4 (bpz-eaT)]·C5H8O4·CH3CN (3) (bpz-eaT=2,4-bis (3,5-dimethyl-1H-pyrazol-1-yl)-6-diethylamino-1,3,5-triazine) were synthesized in MeCN. All of the complexes are characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. The single-crystal X-ray diffraction analyses reveal that the vanadium atoms are six-coordinated in all complexes. In the study of Cyclohexane (Cy) oxidation, promoted by our complexes, the effects of the amount of H2O2 and HNO3 were investigated. It was found that complex 3 exhibited the highest catalytic activity in MeCN at 9h, 60°C, which is the first oxidovanadium(IV) complex catalyst that we found can catalyze Cy produce more cyclohexanone (CyO) than cyclohexanol (CyOH) oxidated by H2O2.