Application in the cyclohexane oxidation of a scorpionate oxovanadium(IV) complex: synthesis, structure, and properties of VO(C5H7O2)(BC9H7N6I3)

An oxovanadium(IV) complex, VO(C5H7O2)(BC9H7N6I3), derived from hydrotris(4-iodinpyrazolyl) borate was designed and synthesized at room temperature in methanol. The complex was characterized by elemental analysis, IR spectra, UV-Vis spectroscopy, and single-crystal X-ray diffraction. The structural analysis shows that the vanadium(IV) center possesses a distorted-octahedral geometry with a N3O3 core, containing a tridentate hydrotris(4-iodinpyrazolyl) borate with nitrogen as three donors. The complex is the first structurally characterized example of a vanadium(IV) complex with hydrotris(4-iodinpyrazolyl)borate. It was used as a catalyst for cyclohexane oxidation under mild conditions and the effects of a variety of factors such as amount of acid and H2O2, the kind of solvent, as well as temperatures were evaluated; the maximum turnover number value reaches 321.