NMR and ESI-MS studies on the interactions between oxodiperoxooxalatovanadate and organic ligands

Coordination interactions between oxodiperoxooxalatovanadate (K-3[ VO (O-2)(2) ( C-2 O-4)] . H2O, abbr. dpV(Ox)) and several organic ligands in solutions I were studied by H-1, C-13, and V-51 NMR spectroscopies and electrospray ionization mass spectrometry under the condition of nearly physiological pH value. It shows that these spectroscopic methods are powerful for analyzing and characterizing the structure and the chemistry of peroxovanadate species in the interaction systems. The order of strength of the interactions is that inudazole > 4-methylimidazole > pyridine. A series of newly-formed peroxovanadate species [OV (O-2)(2)L](-) ( L = pyridine, 4-methylimidazole and imidazole) was observed. For L=4-methylimidazole, a pair of new isomers was suggested.