Synthesis and Characterization of Gallium-Containing Silsesquioxanes

The reaction of [(c-C6H11)7Si7O9(OH)3] (1a) with GaX3 (X = Cl or I) in the presence of Proton Sponge (C14H18N2) affords [(c-C6H11)7Si7O12GaX]- [C14H18N2·H]+ (2a, R = Cl; 2b, R = I). A single-crystal X-ray diffraction study of 2a reveals discrete ions with no significant interactions. Upon thermolysis both 2a and 2b liberate an equivalent of [C14H18N2·H]+X- to produce quantitative yields of [(c-C6H11)7Si7O12Ga]2 (3), a siloxy-bridged dimer which is isomorphous with previously characterized dimers containing Ti3+ and V3+. The reaction of 3 with Ph3PO affords [(c-C6H11)7Si7O12Ga(OPPh3)] (5), which was characterized by a single-crystal X-ray diffraction study. The reaction of trisilanol 1a with Ga(CH2SiMe3)3 affords 6, an interesting cluster derived from the reaction of two molecules of 1a with six molecules of Ga(CH2SiMe3)3 and six molecules of water.