Cyclic trimer of tripodal trisilanol with new hydrogen bonding motif

Tripodal trisilanols tris[4-(diisopropylhydroxysilyl)phenyll-phenylsilane and -methylsilane (3a and 3h) as well as 1,3,5-tris(diisopropylhydroxysilylmethyl)-2,4,6-triethylbenzene (3c) were synthesized by treatment of the corresponding tribromide with alkyl lithium or magnesium, followed by silylation with diisopropylchlorosilane, halogenation with trichloroisocyanuric acid (TCCA) or N-bromosuccinimide (NBS), and subsequent alkaline hydrolysis. X-ray analyses of the tripodal silanols (3a c) revealed the first example of a cyclic trimer in the silanol hydrogen bonding pattern. The connectivity of silanol hydrogen bonding in the silanol products was found to produce a 1D network, based on X-ray packing structures. Substituent effects for this new mode of silanol hydrogen bonding were estimated by hydrogen bonding energy [Efi_bond] based on DFT calculations. Other new silanol hydrogen bonding features were characterized using Bader's Atom in Molecules (AIM) analyses. (C) 2015 Elsevier B.V. All rights reserved.