Cyclic Polysilanes. VIII. The Crystal Structure of 1,2,3,4-Tetra-Tert-Butyltetra-Methylcyclotetrasilane.

摘要

The crystal structure of (Si(CH3)(t-C4H9))4 has been determined by single crystal x-ray diffraction. The crystals are tetragonal. The structure was determined using 745 independent data and refined with anisotropic least-squares to a final unweighted R-value of 3.5%. Each tetrameric molecule was found to be arranged about a 4 axis, with independent crystallographic unit comprising one silicon atom, one methyl and one tert-butyl group. The four-membered ring of silicon atoms is nonplanar with an unusually large dihedral angle of 36.8 deg. The principal mean bond lengths are Si-Si 2.377(1), Si-C(methyl) 1.893(4), Si-C(tert-butyl) 1.918(3) A, and the Si-Si-Si bond angle is 86.99 deg. The Si-Si bond length is somewhat longer than in other polysilanes.