We report on the synthesis, characterization, and catalysis of organorhodium- and iridium-containing derivatives of the 48-tungsto-8-phosphate wheel, Rh (Cp*) (H2O) 4P8W48O18432- (1) and Ir (Cp*) (H2O) 4P8W48O18432- (2). The novel polyanions 1 and 2 were synthesized by the reaction of (MCp*Cl2) 2 (M = RhIII, IrIII) with the mixed potassium-lithium salt of the cyclic P8W48 precursor in an aqueous medium using mild one-pot conditions, and four organometallic moieties are covalently bound to the central cavity of the P8W48 wheel via two M-O (W) oxygen bridges. Both polyanions were structurally characterized in the solid state by single-crystal X-ray diffraction, FT-IR spectroscopy, and thermogravimetric analysis, as well as in solution by 31P and 13C NMR spectroscopy. The hydrogenation of olefins was investigated after supporting polyanions 1 and 2 on mesoporous SBA15. The supported catalysts exhibited high activity in the selective hydrogenation of o-xylene with very little cracking products, even under high temperature and pressure conditions.
Mougharbel et al. (Wed,) studied this question.