A New Method for the Synthesis of Organopolyoxometalate Hybrid Compounds

The reaction of a quaternary ammonium salt of the tin chloride-substituted polyoxometalate, [PSn(Cl)W11O39]4-, with a variety of n-nucleophiles including primary, secondary, and tertiary amines and a tertiary phosphine, yielded tin-centered Lewis acid−base adducts, [PSn(Cl)W11O39]4-−n-nucleophile; with more nucleophilic secondary amines such as diisopropylamine, apparently some [PSnN[CH(CH3)2]2W11O39]4- was formed as a minor product. The compounds were identified by 1H, 119Sn, 15N, 31P, and 183W NMR, ESI-MS, and elemental analyses. The key connectivity of the Sn−Cl center with the amine was clarified by the observation of 3 J Sn−H couplings (Sn from the polyoxometalate cluster and H from the amine moiety) in a 2D 119Sn−1H heteronuclear multiple-bond correlation NMR experiment. This new, rather simple synthetic method was also utilized for preparing amino acid−polyoxometalate hybrid compounds.