Octasilsesquioxane chemistry - II. Hydrosilylation reaction of octa(hydrido)silsesquioxane with unsaturated substrates and product properties

The hydrosilylation reaction of octa(hydrido)silsesquioxane with omega-halo-1-alkenes and other unsaturated substrates allows attachment of 8 long-chain functionalized alkyls on the cubic Si8O12 skeleton. Pt/C and H2PtCl6 have been adopted as the catalysts, the yields being 74-98% for compounds 2-9. For terminal alkenes, the hydrosilylation follows the anti-Markonikov's rule. The morphological state of 2-9 ranges from viscous liquid to crystalline materials. The pyrolysis results indicate that 7, a material of hard spherical core and soft flexible shell, may likely act as nanometer-size ball bearings up to more than 400degreesC. The X-ray structure of 9 reveals that the molecule is required to possess a center of symmetry crystallographically. The linear arms on 9, except for two of them, are virtually all-trans in conformation, not counting the omega-C-Cl bond.