Mixed-valent vanadium substituted polyoxometalates: the wheel shaped [Rb-3 subset of{(VV3O7)-V-V-O-IV(H2O)(6)}(2){H6P6W39O147(H2O)(3)}](15-)

The wheel shaped polyoxoanion [Rb-3 subset of{(VV3O7)-V-V-O-IV(H2O)(6)}(2){H6P6W39O147(H2O)(3)}](15-) comprising a macrocyclic tungstophosphate template wheel [P6W39O147(H2O)(3)](30-) ({P6W39}) capped by two unprecedented mixed-valent oxovanadium {(V-V=O)(V-IV=O)(3)(mu(2)-O)(3)(H2O)(6)}(3+) groups has been prepared and characterized by X-ray diffraction, elemental analysis, TGA, IR and P-31 NMR spectroscopy. The title polyanion represents the first example of the {P6W39} unit stabilizing a polynuclear metal assembly.