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)](2)W11O39](4-) was formed as a minor product. The compounds were identified by H-1, Sn-119, N-15, P-31, and W-183 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 Sn-119-H-1 heteronuclear multiple-bond correlation NMR experiment. This new, rather simple synthetic method was also utilized for preparing amino acid-polyoxometalate hybrid compounds.