Structure and vibrational spectra of dimethylsilanediol and methylsilanetriol dimers

Equilibrium geometries of methylsilanetriol monomer and dimers are obtained at B3LYP/DZP + diff level and differences in electron density distribution and in hydrogen bonding between them and analogous structures of dimethylsilanediol are discussed. Five isomers are found as energy minima in the [CH3Si(OH)3]2 system, from which the most stable corresponds to a structure in which all three OH groups of the monomers are involved in hydrogen bonding. The predicted vibrational spectra of dimethylsilanediol and methylsilanetriol dimers reveal the considerable decrease of νOH and increase of δSiOH frequencies in silanetriol dimers.