1,1,3,3,5,5,7,7-Octaphenyl-1,3,5,7-tetrasiloxane-1,7-diol and Its Organotin Derivatives. Model Compounds for Diphenylsiloxane Polymer^†

The hydrolysis of the spirotitanasiloxane Ti[(OSiPh₂)₄O]₂ provides 1,1,3,3,5,5,7,7-octaphenyl-1,3,5,7-tetrasiloxane-1,7-diol, H(OSiPh₂)₄OH (1), in high yield. The reaction of 1 with tricyclohexyltin hydroxide, cyclo-Hex₃SnOH, and di-tert-butyltin oxide, cyclo-(t-Bu₂SnO)₃, respectively, gives 1,1,3,3,5,5,7,7-octaphenyl-1,7-tricyclohexylstannyl-1,3,5,7-tetrasiloxane, (cyclo-Hex₃SnOSiPh₂OSiPh₂)₂O (2), and 1,1-di-tert-(butyl-3,5,7,9-octaphenyl-2,4,6,8,10-pentaoxa-,3,5,7,9-tetrasila-1-stannacyclododecane, cyclo-t-Bu₂Sn(OSiPh₂OSiPh₂)₂O (3). The molecular structures of 1 and 2 were determined by X-ray diffraction. In both compounds the central Si−O−Si angle amounts to 180°. Remarkably, no hydrogen bonding is observed for 1.