Vanadium Oxide Complexes in Room-Temperature Chloroaluminate Molten Salts

The dissolution of vanadium(V) oxide (V2O5) in various ionic liquids has been studied to determine the complexes formed with respect to melt composition and V2O5 concentration. Vanadium oxide did not dissolve in either 1-n-butyl-3-methylimidazolium tetrafluoroborate or 1-n-butyl-3-methylimidazolium trifluoromethanesulfonate ionic liquids. V2O5 was found to dissolve at temperatures greater than 70 °C in 1-ethyl- and 1-n-butyl-3-methylimidazolium tetrachloroaluminate ionic liquids. Analyses of vanadium-containing melts by 51V, 1H, and 13C NMR and infrared spectroscopy indicate the emergence of different species as a function of melt acidity. In basic and neutral melts, VO2Cl2 - and a metavanadate species of the form [(VO3) n ] n - are observed. The species VO2Cl2 - is the prominent product in basic melts, but as the melt becomes neutral or as the concentration of V2O5 is increased, the concentration of the metavanadate species is found to increase. However, V2O5 has been found to react in acidic melts to form volatile VOCl3.