CUBIC, BUTTERFLY, AND OXYGEN-CAPPED CLUSTERS OF n-BUTYLOXOTIN PHOSPHINATES. A NEW CLASS OF ORGANOTIN COMPOUNDS

Reaction of n-butylstannoic acid with the phosphinic acids, R 2 PO 2 H, where R = tert-butyl, benzyl, and cyclohexyl, has led to new types of structural forms for hexacoordinated tin: two cubic clusters; [n-BuSn(O)O 2 P(t-Bu) 2 ] 4 (1) and [n-BuSn(O)O 2 ,P(CH 2 Ph) 2 ] 4 (2), respectively, and a "butterfly" cluster, [n-BuSn(OH)(O 2 P(C 6 H 11 ) 2 ] 2 (3). Interesting transformations of cubes and the butterfly derivative yield oxygen-capped cluster formulations, [(R'Sn(OH)O 2 PR 2 ) 3 O][R 2 PO 2 ], where R = n-Bu and R = C 6 H 11 or CH 2 Ph. 119 Sn and 31 P NMR show these structural characteristics in solution. The 119 Sn 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 P42 1 c 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).