Reduction of Vanadium(V) with ascorbic acid and isolation of the generatedoxovanadium(IV) species

The interaction of sodium metavanadate and VOCl3 with ascorbic acid, one of the possible natural reducing agents of vanadium(V) to oxovanadium(IV), ha s been investigated. Three new VO2+, complexes could be isolated as microcr ystalline powders. One of them, of composition K1.5Na0.5[VO(HAsc)(OH)(3)], contains ascorbic acid as a monodentate ligand. In the other two, K[VO(Dike to)(OH)].H2O and Na-3[VO(Diketo)(2)(OH)], the enolized form of 2,3-diketogu lonic acid (one of the oxidation products of ascorbic acid), acts as a bide ntate ligand. The complexes were characterized by means of electronic (abso rption and reflectance) and infrared spectroscopy and magnetic susceptibili ty measurements. Their thermal behavior was investigated by thermogravimetr ic and differential thermal analyses. The interest of the investigated syst em in relation to vanadium detoxification is also discussed.