THE CRYSTAL AND MOLECULAR-STRUCTURE OF 2,2-DIPHENYL-1,3,2-OXATHIASTANNOLANE

The crystal structure of 2,2-diphenyl-1,3,2-oxathiastannolane, (C6H5)2S activated n(OCH2CH2S), has been determined by means of X-ray diffraction. The space group is P21/c, M(r) = 349.04, a = 8.807(4) angstrom, b b = 13.867(4) angstrom, c = 11.645(5) angstrom, beta = 104.73(3)-degrees, V = 1375.43 angstrom 3, Z = 4, D(x) = 1.685 g cm-3, lambda(MoK-alpha) = 0.71069 angstrom, mu = 19.91 cm-1, F(000) = 687.93, T = 213(5) K. The least-squares refinement was based on 4224 independent reflections with I > 3 sigma(I) and R-factors in the last refinement were R = 0.0279 and wR = 0.0295. Two molecules of the formula unit are dimerized by a Sn - O' and a Sn' - O bond. Because of the dimerization the coordination number of tin becomes 5. The strongly distorted coordination polyhedron of tin can be described as intermediate between a trigonal bipyramid, with S and O' on the axial positions and a square pyramid, with the atom C(1) of the first phenyl ring at the apex. The distortion seems to be due to the constraints, which are imposed by the tricyclic ring system of the dimeric molecule.