Synthesis and structural characterization of cycloborasiloxanes: The X-ray crystal structures of cyclo-1,3,3,5,5-pentaphenyl-1-bora-3,5-disiloxane and cyclo-1,3,3,5,7,7-hexaphenyl-1,5-dibora-3,7-disiloxane
摘要:
Cycloborasiloxanes [PhB(OSiPh2)O]2 (1) and RB[(OSiPh2)2)O] [R = Ph (2); 2,4,6-Me3C6H2 (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 in the larger ring. The factors affecting the structural parameters of related heterocyclic ring systems are reviewed.