Synthesis and structure of 1,3,5-tris(diorganohydroxysilyl)benzenes.: Novel building blocks in supramolecular silanol chemistry

The 1,3,5-tris(diorganohydroxysilyl)benzenes 1,3,5-(HOR2Si)(3)C6H3 (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.H(2)o complex reveals intra- and intermolecular C-H...pi 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' ,N'-tetramethylethylenediamine, imidazole, 2-(dimethylamino)pyridine, and 2,2'-dipyridylamine.