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Synthesis and Structure of 1,3,5-Tris(diorganohydroxysilyl)benzenes. Novel Building Blocks in Supramolecular Silanol Chemistry

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journal contribution
posted on 27.09.2004, 00:00 by Jens Beckmann, Andrew Duthie, Gregor Reeske, Markus Schürmann
The 1,3,5-tris(diorganohydroxysilyl)benzenes 1,3,5-(HOR2Si)3C6H3 (TMSB, R = Me; TPSB, R = Ph) have been prepared and fully characterized by X-ray crystallography. The crystal structure of TMSB features pairwise connected layers, in which the molecules are involved in interlayer hydrogen bonding. The supramolecular hydrogen bond motif may be described as a 12-membered ring that adopts a chair conformation. TPSB forms an equimolar inclusion complex with water, which is associated via hydrogen bonding and apparently fills a void in the crystal packing. In this case, the supramolecular hydrogen bond motif may be described as an eight-membered ring. Two of the water molecules are also associated, giving rise to a water dimer entrapped in the silanol matrix. Besides the hydrogen bonds, the crystal structure of the TPSB·H2O complex reveals intra- and intermolecular C−H···π stacking of most of the phenyl groups. Electrospray mass spectrometry shows that TPSB undergoes supramolecular complex formation with a variety of N-donors such as 4-(dimethylamino)pyridine, N,N,N,N-tetramethylethylenediamine, imidazole, 2-(dimethylamino)pyridine, and 2,2‘-dipyridylamine.