Cubic, butterfly, and oxygen-capped clusters of n-butyloxotin phosphinates. A new class of organotin compounds

Abstract

Reaction of n-butylstannoic acid with the phosphinic acids, R₂PO₂H, where R = tert-butyl, benzyl, and cyclohexyl, has led to new types of structural forms for hexacoordinated tin: two cubic clusters; [n-BuSn(O)O₂P(t-Bu)₂]₄ (1) and [n-BuSn(O)O₂,P(CH₂Ph)₂]₄ (2), respectively, and a "butterfly" cluster, [n-BuSn(OH)(O₂P(C₆H₁₁)₂]₂ (3). Interesting transformations of cubes and the butterfly derivative yield oxygen-capped cluster formulations, [(R'Sn(OH)O₂PR₂)₃O][R₂PO₂], where R = n-Bu and R = C₆H₁₁ or CH₂Ph. ¹¹⁹Sn and ³¹P NMR show these structural characteristics in solution. The ¹¹⁹Sn chemical shift correlates with increasing cluster complexity, i.e., with an increasing ligand to tin component in the various formulations discovered so far. 1 crystallizes in the triclinic space group P1 with a = 13.616 (4) Å, b = 13.857 (3) Å, c = 20.544 (4) Å, α = 79.95 (2)°, β = 69.16 (2)°, γ = 71.15 (2)°, and Z = 2. 2 crystallizes in the tetragonal space group P42₁c with a = 17.630 (4) Å, c = 11.825 (3) Å, and Z = 2.3 crystallizes in the triclinic space group P1 with a = 10.758 (3) Å, b = 12.133 (4) Å, c = 13.038 (4) Å, a = 79.93 (2)°, β = 73.72 (2)°, γ = 89.53 (2)°, and Z = 1. The conventional unweighted residuals were 0.038 (1), 0.042 (2), and 0.042 (3).