ATTENUATED TOTAL REFLECTION FOURIER-TRANSFORM INFRARED SPECTROSCOPIC STUDY OF ION SOLVENT AND ION ION INTERACTIONS IN LITHIUM PERCHLORATE NITROMETHANE SOLUTIONS

Lithium perchlorate solutions in nitromethane, 0.04-0.18 mol dm-3, have been investigated using attenuated total reflection Fourier-transform infrared (ATR FTIR) spectroscopy. Despite the relatively poor electron-donating ability of nitromethane, some evidence for lithium ion coordination is seen. Frequency shifts for the symmetric NO2 stretching fundamental of +7 cm-1, and for the symmetric CH3 bending fundamental of +2 cm-1 are found for nitromethane complexed to the alkali-metal cation. The infrared-active absorption for the CIO4- anion at 1100 cm-1 shows substantial splitting, an effect due to the extensive ion-pairing of the solute species. The distribution and relative concentrations of the different electrolyte species were found to be concentration dependent.