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)W<sub>11</sub>O<sub>39</sub>]<sup>4-</sup>, with a variety of <i>n</i>-nucleophiles including primary, secondary, and tertiary amines and a tertiary phosphine, yielded tin-centered Lewis acid−base adducts, [PSn(Cl)W<sub>11</sub>O<sub>39</sub>]<sup>4-</sup>−<i>n</i>-nucleophile; with more nucleophilic secondary amines such as diisopropylamine, apparently some [PSnN[CH(CH<sub>3</sub>)<sub>2</sub>]<sub>2</sub>W<sub>11</sub>O<sub>39</sub>]<sup>4-</sup> was formed as a minor product. The compounds were identified by <sup>1</sup>H, <sup>119</sup>Sn, <sup>15</sup>N, <sup>31</sup>P, and <sup>183</sup>W NMR, ESI-MS, and elemental analyses. The key connectivity of the Sn−Cl center with the amine was clarified by the observation of <sup>3</sup><i>J</i> Sn−H couplings (Sn from the polyoxometalate cluster and H from the amine moiety) in a 2D <sup>119</sup>Sn−<sup>1</sup>H heteronuclear multiple-bond correlation NMR experiment. This new, rather simple synthetic method was also utilized for preparing amino acid−polyoxometalate hybrid compounds.