Rapid reduction and complexation of vanadium by 1-phenyl-3-methyl-4-toluoyl-5-pyrazolone: Spectroscopic characterization and structure modelling

The reduction of vanadium(V) by 1-phenyl-3-methyl-4-toluoyl-5-pyrazolone over the pH range of 1.0-7.0 has been assessed by various spectroscopic techniques. The reaction proceeds by the transfer of one electron to vanadium(V) by the ligand via the formation of a free-radical intermediate, and subsequently the reduced vanadium species rapidly complexes with the available free ligand and forms vanadyl complex. These reduction reactions occur under physiological conditions and thus could be important to the reduction of vanadium(V)-containing coordination compounds used as insulin-enhancing agents for treatment of diabetics.