Crystal and molecular structure of 1,8-bis(trimethylsilyl)octatetrayne

Abstract

A structural analysis of 1,8-bis(trimethylsilyl)octatetrayne has been carried out by X-ray diffraction. Crystals are orthorhombic, space group Pbcn, a= 11·966(2), b= 12·544(3), c= 22·809(3)Å, Z= 8. The structure has been refined by least-squares to R 0·056 for 1093 reflections. The chain of carbon atoms comprising the conjugated triple bonds has a slight curve, and shows clear bond-length alternation: 1·20 for the formal triple-bonds and 1·38 Å for the formal single bonds, except for the central single bond which is significantly shorter, viz. 1·33 Å.