New Routes for Multiple Derivatization of Polyoxometalates. Bis(acetato)dirhodium-11-tungstophosphate, [(PO4)W11O35{Rh2(OAc)2}]5-

Hydrothermal reaction of lacunary [(PO4)W11O35]7- with rhodium acetate dimer yields the novel dirhodium-substituted Keggin anion, [(PO4)W11O35{Rh2(OAc)2}]5- (1). An X-ray structure determination of the guanidiunium salt of the dimethyl sulfoxide derivative of 1 confirms the structure deduced from proton and tungsten NMR spectroscopy. Oxidation of 1 to an unstable RhII,III derivative, and synthesis of other polytungstate analogs is possible. The tetrabutylammonium salt of 1 exhibits modest catalytic reactivity for cyclopropanation.