Abstract Cycloborasiloxanes [PhB (OSiPh 2) O] 2 (1) and RB [(OSiPh 2) 2][R= Ph (2); 2, 4, 6- Me 3 C 6 H 2 (3)] containing eight-and six-membered rings, respectively, have been synthesized by the reaction of RB (OH) 2 with 1, 1, 3, 3-tetraphenyl-1-3-dihydroxy-1, 3- disiloxane or diphenylsilanediol. The structures of 1 and 2 have been determined, and both contain essentially planar Si O B rings, although the Si O and B O bonds are shorter ...
