Structural studies of octahydridooctasilsesquioxane – H8Si8O12

There has been an increasing amount of interest in silsesquioxanes recently. The most important group of polyhedral oligomeric silsesqioxanes (POSS) is octasilsesquioxanes. The attention is particularly focused on octahydridooctasilsesquioxanes, also known as T8H. The aim of the presented work is a detailed study of the structure of T8H = H8Si8O12. Powder X-ray diffraction and infrared spectroscopy FTIR are the main measurement techniques on which the detailed structural studies are based. The results undoubtedly point to the conclusion that T8H molecule symmetry is lower (C3i) than expected (Th) and matches site symmetry in the trigonal crystal structure.

► Synthesis of octahydridooctasilsesquioxane (T8H).
► X-ray powder diffraction measurements.
► Structure determination based on the full pattern fit and Monte-Carlo calculations.
► Observation of T8H molecule symmetry lowering from expected Th to C3i.
► Infrared Spectroscopy measurements with DFT calculations.