(ETHYL-, ETHENYL- AND ETHYNYLSILYLOXY)ALUMINUM COMPOUNDS GENERATED BY HETEROLYTIC CLEAVAGE OF 1,3-DISUBSTITUTED DISILOXANES

sym-Diorganodisiloxanes RH(2)SiOSiH(2)R (R = C2H5, 7; C2H3, 8; C2H, 9) are prepared by hydrolysis of organo(bromo)silanes which are available in high yields by the reaction of organo(phenyl)silanes with liquid HBr. Asymmetrical cleavage of these disiloxanes with AlCl3 leads to the formation of organo(chloro)silanes and aluminosiloxane dimers [RH(2)SiOAlCl(2)](2) (R = C2H5, 10; C2H3, 11; C2H, 12) Crystal structure determinations of 11 and 12 reveal a planar centrosymmetrical Si-OAl2OSi skeleton with three-coordinate oxygen atoms and tetrahedral four-coordinate aluminum atoms. Treatment of 7-9 with Me(2)AlCl yields volatile dimethylaluminumorganosilyl oxides [RH(2)SiOAlMe(2)](x) (R = C2H5, 13; C2H3, 14; C2H, 15; x = 2, 3, 4). NMR studies confirm the presence of more than one oligomer in solutions of these compounds. The asymmetrical compound (HC drop CSiH2O)(2)Me(3)Al(2)Cl (16), resulting from small amounts of MeAlCl(2), in the Me(2)AlCl used, is isolated as a byproduct in the synthesis of 15. The crystal structure of 16 shows a disorder of the molecules leading to pseudosymmetry with a center of inversion.