HIGH-YIELD ROUTES TO HEXA(DIMETHYLSILYLOXY)SILSESQUIOXANE AND HEXA(BROMODIMETHYLSILYLOXY)SILSESQUIOXANE

Examination of the structures adopted by zeolites and related material s shows that the channels and cavities comprise closed polyhedra made up of silicon/aluminium and oxygen atoms. The smallest such unit obser ved in zeolites is the cubane [Si8O12] cage (I) although much larger p olyhedra also occur. Closed vertex spherosilicates of the general form ula (XSiO1.5)(n) (n greater than or equal to 6; X = reactive functiona l group) are ideal candidates as precursors for the construction of th ree-dimensional polymeric architectures [1,2]. Whereas the cubane [Si8 O12] cage is isotropic, the [Si6O9] cage is anisotropic and should, th erefore, lead to microporous polymeric materials with father different characteristics. Unfortunately, suitable high yield routes to molecul ar precursors possessing these frameworks are not available. In this p aper we report convenient, high yield routes to both hexa(dimethylsily loxy)silsesquioxane, Si6O15(SiMe2H)(6), and imethylsilyloxy)silsesquio xane,Si6O15(SiMe2Br)(6), via the ionic salt (NEt4)(6){Si6O15}.