Vibrational spectroscopic studies, conformations and quantum chemical calculations of 3,3,3-trifluoropropyl- silane and 3,3,3-trifluoropropylsilane-d3

摘要: Infrared spectra of 3,3,3-trifluoropropylsilane (CF3CH2CH2SiH3) and 3,3,3-trifluoropropylsilane-d3 (CF3 CH2CH2SiD3) were obtained in the vapour, liquid, crystalline solid phases range 4000–50 cm−1. Additional argon matrices at 5 K recorded before after annealing to temperatures 20–34 K. Raman compounds as liquids various between 296 183 amorphous solids obtained. The revealed existence two conformers (anti gauche) fluid matrices. When vapours shock-frozen on a cold finger 78 K, they turned partly immediately. After subsequent 140–150 ca 7–9 bands both molecules present vanished crystal. Similar variations intensity observed corresponding infrared annealing. The one conformer (anti) crystal. From three independent pairs anti gauche 298 173 for parent compound, deuterated analogue, values ΔconfHo(gauche−anti) = 4.1 ± 0.3 kJ mol−1 compound same value species liquid state. Annealing experiments show that vanish annealing, demonstrating also has lower energy here barrier inter-conversion is around 5–6 mol−1. have been interpreted detail. Ab initio DFT calculations HF/6–311G**, B3LYP/6–311 G** MP2/6–311 levels gave optimized geometries, intensities vibrational wavenumbers conformers. conformational enthalpy difference derived from was 6.0 with being low conformer. Copyright © 2006 John Wiley & Sons, Ltd.