Tip-substituted cage and cyclic silanols

Synthesis of novel cage and cyclic silanols bearing Tip (2,4,6-triisopropylphenyl) groups was performed. Tip-substituted silanetriol, TipSi(OH)3 (1) was prepared from TipSiCl3, and can be handled without special care in the air. The versatility of this silanol is amply demonstrated as a starting material of various silanols with novel frameworks. Thus, the condensation of 1 using 2-chloro-1,3-dimethylimidazolinium chloride as a dehydrating agent afforded (TipSi)5O7OH (2) in 45% yield. When 1 was treated with (TipSiCl2)2O, cis,trans-cyclotrisiloxanetriol (3) as well as a novel incompletely condensed silsesquioxane, (TipSi)4O5(OH)2 (4) were obtained. In addition, the dehydrochlorinative condensation of (TipSiCl2)2O and (TipSi(OH)2)2O afforded 4 as single product. The structures of all these novel silanols were determined by X-ray crystallography, and their unique structures (hydrogen-bonded aggregates or intramolecular hydrogen bonding) were demonstrated.