Raman spectra and conformational analyses for a series of diethyl ether and its organosilicon derivatives, CH3MH2OM′H2CH3 (M, M′=C and Si), by density functional theory

The molecular structures of a series of diethyl ether and its organosilicon derivatives of CH3MH2OM′H2CH3 (M, M′=C and Si) have been studied by Raman spectroscopy and density functional theory (DFT) with the B3LYP/6-31G* and 6-311+G** methods. Raman spectra for these molecules were measured in the liquid and solid states. Normal vibrations and calculated Raman spectra were also obtained by using the Raman activities and the scaled wavenumbers from the B3LYP/6-311+G** method. For diethyl ether, CH3CH2OCH2CH3, the trans–trans (TT) and trans–gauche (TG) forms were the stable conformers in the liquid state, while only the TT form existed in the solid state. Additionally, two solid states were obtained and the conformer in both the stable and metastable solids was the TT. For bis(methylsilyl) ether, CH3SiH2OSiH2CH3, geometry optimization and the DFT calculation showed that only the TT and skew–skew (SS) forms existed in the liquid state and the SS form existed in the solid state. While, for ethyl methylsilyl ether, CH3CH2OSiH2CH3, the TT, TG and GT forms coexisted in the liquid state and only the TT form existed in the solid state.