THE CRYSTAL AND MOLECULAR-STRUCTURE OF DODECAHYDRIDOSILASESQUIOXANE, H12SI12O18

The title compound belongs to a family of cage-shaped spherosiloxane m olecules which show, as a common and systematic feature, smaller or la rger distortions from their respective ideal point-group symmetry. By means of statistical methods in combination with rigid-body analysis, the molecular distortions involved in the lowering of the molecular sy mmetry of H12Si12O18 and (C6H5)12Si12O18 have been analysed. The magni tudes and types of the deformations may be described in terms of a sma ll number of symmetry displacement coordinates involving displacement of flexibly joined, but otherwise rigid, corner-sharing tetrahedra.