New polyhedral oligosilsesquioxanes via the catalytic hydrogenation of aryl-containing silsesquioxanes

Abstract

The hydrolytic condensation of RSiCl 3 (R = benzyl, m-tolyl, 3,5-dimethylphenyl) gives good yields of the corresponding octameric aryl silsesquioxanes ( 1). A single-crystal X-ray diffraction study of highly soluble 1 (R = benzyl) reveals that highly efficient crystal packing can be accomplished without the inclusion of solvent or the strong intermolecular π-stacking arrangements that normally lead to poor solubility properties. The catalytic hydrogenation of aryl polyhedral oligosilsesquioxanes (POSS) affords high yields of the corresponding aliphatic silsesquioxanes. These new silsesquioxanes display thermal and physical properties comparable to the corresponding aryl-containing POSS but generally have much greater solubilities in common organic solvents. The catalytic hydrogenation of [Ph 12Si 12O 20] affords iso-[Cy 12Si 12O 20], which possesses local C 2 v rather than D 6 h symmetry.