(ETHYL-, ETHENYL- AND ETHYNYLSILYLOXY)ALUMINUM COMPOUNDS GENERATED BYHETEROLYTIC 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 availabl e in high yields by the reaction of organo(phenyl)silanes with liquid HBr. Asymmetrical cleavage of these disiloxanes with AlCl3 leads to th e formation of organo(chloro)silanes and aluminosiloxane dimers [RH(2) SiOAlCl(2)](2) (R = C2H5, 10; C2H3, 11; C2H, 12) Crystal structure det erminations of 11 and 12 reveal a planar centrosymmetrical Si-OAl2OSi skeleton with three-coordinate oxygen atoms and tetrahedral four-coord inate 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 asymmetric al 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 byprodu ct in the synthesis of 15. The crystal structure of 16 shows a disorde r of the molecules leading to pseudosymmetry with a center of inversio n.