Peroxovanadium(V) Complexes of L-Lactic Acid as Studied by NMR Spectroscopy

Abstract

A multinuclear (1H, 13C, 17O, 51V) 1D and 2D NMR study of the complexation of l-lactic acid with vanadium(V) and hydrogen peroxide shows that four peroxo complexes are formed in aqueous solution in the pH range 1-7. Two isomeric 2:2:1 (metal:ligand:peroxo) complexes, together with a 2:2:2 species, are found over the entire pH range. At pH values below 2 an additional 1:1:1 complex is formed. The acid was found in all cases to act as a bidentate ligand through the carboxylic and the adjacent hydroxyl groups. To the best of our knowledge, this is the first report of dinuclear peroxovanadium complexes in which one of the metal centres is an oxovanadium centre (2:2:1 species).