Syntheses and crystal structures of 2-methyl-1,1,2,3,3-penta-phenyl-2-sila-propane and 2-methyl-1,1,3,3-tetra-phenyl-2-silapropan-2-ol.

The sterically hindered silicon compound 2-methyl-1,1,2,3,3-penta-phenyl-2-sila-propane, CHSi (), was prepared the reaction of two equivalents of di-phenyl-methyl-lithium (benzhydryllithium) and di-chloro-methyl-phenyl-silane. This bis-benzhydryl-substituted silicon compound was then reacted with tri-fluoro-methane-sulfonic acid, followed by hydrolysis with water to give the silanol 2-methyl-1,1,3,3-tetra-phenyl-2-silapropan-2-ol, CHOSi (). Key geometric features for are the Si-C bond lengths that range from 1.867 (2) to 1.914 (2) Å and a τ descriptor for fourfold coordination around the Si atom of 0.97 (indicating a nearly perfect tetra-hedron). Key geometric features for compound include Si-C bond lengths that range from 1.835 (4) to 1.905 (3) Å, a Si-O bond length of 1.665 (3) Å, and a τ descriptor for fourfold coordination around the Si atom of 0.96. In compound , there is an intra-molecular C-H⋯O hydrogen bond present. In the crystal of , mol-ecules are linked by two pairs of C-H⋯π inter-actions, forming dimers that are linked into ribbons propagating along the -axis direction. In the crystal of , mol-ecules are linked by C-H⋯π and O-H⋯π inter-actions that result in the formation of ribbons that run along the -axis direction.