Structure of 2,2,5,5,6,6,9,9-octamethyl-2,5,6,9-tetrasiladecane,a structural precursor of poly[(tetramethyldisilanediyl)ethylene]

In order to obtain information for suggesting the most likely molecular and crystal structure of poly[(tetramethyldisilanediyl)ethylene] (PTMDSE) an X-ray study of the structural precursor 2,2,5,5,6,6,9,9-octamethyl-2,5,6,9-tetrasiladecane (TSD) is carried out. The TDS molecule is centrosymmetric, the CSiCCSiSiCCSiC chain having an almost planar all-trans conformation. In the crystal of TSD one can distinguish molecular layers parallel to the a b plane; the long axes of the TSD molecules form an angle of 24,4° with the layer plane; intermolecular contacts in layers are shorter, on the average, than interlayer contacts.