Infrared and Fourier transform Raman spectroscopic study of lithium trifluoromethanesulfonate solutions in acrylonitrile

Solutions of lithium trifluoromethanesulphonate (lithium triflate) in acrylonitrile (propenenitrile), in a range of concentrations between 0.37 and 2.07 mol dm(-3) have been analysed by infrared (dispersive) and FT-Raman spectroscopy. The new band in the v(C=N) region arising from the coordinated species Li+...(acrilonitrile)(n), has been examined in derail. A solvation number of three (at infinite dilution) was obtained from the results of both techniques. This solvation number diminishes with increasing salt concentration as a result of the ionic pairing. The data obtained in the analysis of the triflate anion v(4) (SO3 symmetric stretch) and v(10) (SO3 antisymmetric stretch) IR bands, indicates the presence of two different species of ionic pairs. The stoichiometry and structure of these ionic pairs are discussed.