Theoretical infrared and Raman spectroscopic parameters for H2O and the H2O ⋯ Li+ system

Abstract

The force constants of symmetric OH stretching and HOH bending vibrations in H₂O and H₂O ⋯ Li⁺ and the i.r. and Raman intensities of the corresponding bands are computed by using the ab initio SCF LCAO MO approach. A comparison of the calculated data for H₂O and H₂O ⋯ Li⁺ shows that: (i) the cation–water interaction does not substantially affect the vibration frequencies of H₂O, (ii) the i.r. intensities increase considerably for both bands, and (iii) the Raman intensities of ν₁ and ν₂ decrease due to the cation–water interaction. The results of calculations are used for the discussion of the i.r. and Raman spectra of aqueous solutions of electrolytes. Some proposals concerning the interpretation of the absence of the cation effects in these spectra are made.