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

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.