Synthesis and structures of bis(alkyldihydroxysilyl)methanes

Bis(alkyldihydroxysilyl)methanes 1 [R(HO)2SiCH2Si(OH)2R: R = methyl (a) and cyclopentyl (b)] were prepared in 65% and 86% yields by the hydrolysis of the corresponding bis(alkyldichlorosilyl)methanes using aniline as HCl scavenger in diethyl ether. They were isolated in pure forms, fully characterized, and studied on their thermal properties. In single crystal X-ray structures, the molecules of 1a and 1b crystallize in the tetragonal (a = b = 22.884 Å, c = 6.1485 Å; α = β = γ = 90° in a unit cell) and triclinic [a = 5.1729(14) Å [α = 89.133(4)], b = 11.394(3) Å [β = 85.065(4)], c = 12.548(3) Å [γ = 79.956(4) in a unit cell] space groups, respectively. In their solid state, the remarkable hydrogen bondings of compounds 1a and 1b lead to three dimensional network structure and one dimensional columnar tube, respectively. From the studies on their thermal analyses, both compounds 1a and 1b were stable below their melting points and then the losses of waters, which were formed by the self-condensation coincident with their melting, occurred.