Effect of 1,1,2,2-Tetrachloroethane on the IR Spectra of Molecular and Ionic Complexes of Methanesulfonic Acid with Aprotic Bases

The method of multiple attenuated total internal reflection (MATIR) infrared spectroscopy is used to study the effect of 1,1,2,2-tetrachloroethane (TCE) on the spectra of the BH⁺ · (AHA)^– ionic pairs formed by methanesulfonic acid (MSA) with DMF or 2-pyrrolidone and the spectra of molecular complexes of MSA with ethyl acetate. In TCE solutions, the structure with a strong symmetric hydrogen bond in the (AHA)^– anions is preserved and the strength of the hydrogen bond practically does not change in molecular complexes. Changes in the absorption coefficients in the spectra are observed in the region of skeletal vibrations at frequencies below 1800 cm^–1 up to a onefold excess of TCE for the ionic pairs BH⁺ · (AHA)^– and up to a fourfold excess of TCE for molecular complexes.