Synthesis and Characterization of a Soluble Vanadium-Containing Keggin Polyoxoniobate by ESI-MS and 51V NMR: (TMA)9[V3Nb12O42]•18H2O

The vanadium-containing heteropolyoxoniobate (TMA)9[V3Nb12O42]center dot 18H2O was synthesised by hydrothermal reaction of V2O5 and hydrous niobium oxide in tetramethylammonium hydroxide solution. The cluster has an -Keggin structure with a central VO4 and two trans-bicapped VO5. The water-soluble product was characterised by X-ray crystallography, ESI-MS and both liquid- and solid-state 51V NMR spectroscopy. The solid- and solution-phase 51V NMR spectra indicate two major peaks corresponding to one VO4 and two VO5 sites.