ATTENUATED TOTAL REFLECTION FOURIER-TRANSFORM INFRARED SPECTROSCOPIC STUDY OF ION SOLVENT AND ION ION INTERACTIONS IN ALKALI-METAL PERCHLORATE ACETONITRILE SOLUTIONS

A detailed study of the effect of alkali-metal perchlorates, especially LiClO4 and NaClO4, on the spectral features of acetonitrile has been made using attenuated total reflection FTIR spectroscopy. The effect of the electrolyte on the C-H stretching and deformation modes together with new information on the C=N and C-C stretching modes is analysed in detail. It is shown on the basis of spectra obtained in the deuteriated acetonitrile that the Cl-O symmetrical stretching vibration (nu1) is IR active when the anion is paired to a cation. Analysis of the perchlorate region of the spectrum provided further information on ion pairing in this system.