C-13 AND V-51 NUCLEAR-MAGNETIC-RESONANCE STUDIES OF VANADIUM(V)-ALPHA-HYDROXYCARBOXYLATE COMPLEXES

The interaction of vanadium(V) with various alpha-hydroxycarboxylate l igands in aqueous solution at pH 3.2 have been studied by V-51 and C-1 3 NMR spectroscopies. From the results it is supposed that vanadates m ainly form the octahedral complexes with lactate, 2-hydroxybutyrate, g lycerate, and malate. While, vanadates form the trigonal-bipyramidal c omplexes with glycolate, tartarate, and 2-hydroxy-3-methylbutyrate, an d tetrahedral complexes with pyruvate(diol), 2-hydroxyisobutyrate, and 2-hydroxy-3-methylbutyrate. The bipyramidal products are formed as mo nomeric compounds. The octahedral products are formed as dimeric compo unds with no evidence for a significant proportion of the monomeric de rivatives. The complexes are mainly formed through the coordination at the carboxylate and the 2-hydroxyl groups of the ligands.