A Mixed‐Addenda Mo/W Organofunctionalised Hybrid Polyoxometalate

A mixed-addenda W/Mo hybrid polyoxometalate cluster - K-6[P2W15Mo2O61(POC6H5)(2)] (1) was synthesised from the condensation of K-10[P2W15Mo2O61] and PO3C6H7 under acidic conditions. Single-crystal X-ray diffraction confirmed the structure of the hybrid cluster and the presence of two Mo centres in the cap of the lacunary cluster. The electronic effects of metal substitution were studied by cyclic voltammetry, spectroelectrochemistry and electron paramagnetic resonance spectroscopy and supported by density functional theory calculations. Comparing 1 to its tungsten-only analogue K-6[P2W17O61(POC6H5)(2)] (2), a more positive potential for the first reduction process was induced by the substitution of W for Mo, consistent with a significant lowering of the cluster LUMO energy.