X-ray diffraction investigation of siloxanes. III. Structure and configuration of cyclic tetra-and pentasiloxanes bearing different organic substituents at silicon atoms

Single crystal X-ray diffraction is applied to elucidate the structures of six tetra-and one penta-siloxane compounds differing in the nature and position of silicon-sitting organic substituents (Me — methyl, Ph — phenyl, mPh — methoxyphenyl, 2mPh — dimethoxyphenyl, 3mPh — trimethoxypehnyl, and C₄H₆N — butironitrile). Charge states of atoms in the siloxane molecules are calculated, and the effect of oxygen-containing radicals on the Si-O bond lengths and Si-O-Si bond angles affecting the configurations of the tetra-and pentasiloxane cycles is shown.