COMBINED RAMAN AND V-51 NMR SPECTROSCOPIC STUDY OF VANADIUM (V) OLIGOMERIZATION IN AQUEOUS ALKALINE-SOLUTIONS

The Raman spectra of aqueous vanadium(V) solutions at different pH val ues, ranging from 13.1 to 7.0, are presented. The dominant bands in th e range 700-1100 cm-1 are assigned to the VO symmetrical stretching of the different oligomers, using additional information from V-51 NMR s pectra and empirical models. The effects of pH, concentration and ioni c strength on the oligomerization equilibria are discussed. The ionic strength is found to affect significantly the oligomer composition of vanadate solutions, which is of interest in biochemical and biological studies.