Effets de la liaison hydrogene sur la vibration ν(CH) dans les complexes R2CHOH…Y

Complexation effect on CH stretching vibration is investigated in R₂CHOH…Y complexes (R = CF₃, CD₃ ; Y = base) by infrared spectroscopy ; it depends on the alcohol molecular conformation. When the CH and OH bands are in the trans position, the observed down shifts of $\text{ν}$(CH) and $\text{ν}$(OH) in the complexation are linearly related ; for the gauche forms, the relation between the down shifts of $\text{ν}$(CH) and $\text{ν}$(OH) depends on R and when R = CF₃ it moreover depends on the basicity of Y. So, the directional character of the electronic displacement in H bonding is shown. No significant effect of the complexation on the integrated intensity of the ν(CH) band is observed. Solvatation of (CF₃)₂CHOH…Y by Y bases may be due to a C-H…Y hydrogen bonding.