Peroxo- and oxovanadium(iv) complexes with tridentate N-heterocycle ligands: synthesis, structure, and catalytic performance

Abstract

Three peroxo- and oxovanadium(IV) complexes: [VO(O₂)(bpz*eaT)·VO(C₄H₄O₆)]·H₂O (1), [VOSO₄(bpz*eaT)]·C₆H₈O₇ (2) (bpz*eaT = 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-diethylamino-1,3,5-triazine) and [VO(C₁₂H₈N₂)(C₉H₇NO₃)]·CH₃OH·0.5H₂O (3) were synthesized and characterized by elemental analysis, IR spectra, UV-Vis spectroscopy and single-crystal X-ray diffraction. In addition, the catalytic performances of complexes 1–3 and their starting materials (VO(acac)₂ and VOSO₄) were studied by the reaction of cyclohexane (Cy) oxidation. It is found that complex 1 exhibited the highest catalytic activity (TON_{(cyclohexanol)} = 220, TON_{(cyclohexanone)} = 346, Conv. = 97.9%) with H₂O₂ as an oxidant and HNO₃ as an additive at 24 h, 40 °C, indicating that it is a potential candidate catalyst to oxidize the Cy to cyclohexanol (CyOH) and cyclohexanone (CyO) under mild conditions.