Stabilisation of high-valent Cu3+ in a Keggin-type polyoxometalate

An unprecedented Keggin-type Cu3+-containing polyoxometalate Cs3H[CuIIIPW11O39]·11H2O (1-Cs) was successfully synthesised through a newly-developed Ag+-promoted chemical oxidation by S2O82- in aqueous medium and systematic characterisation with powder XRD, XPS, IR, UV-vis and 31P NMR spectroscopies proves the effective stabilisation of a high-valent Cu3+ center by a mono-lacunary Keggin type polyoxometalate ligand.