Ionic Structure and Interactions in 1-Methyl-3-Ethylimidazolium Chloride-AlCl3 Molten Salts

Room temperature chloroaluminate molten salts formed by mixing 1-methyl1-3 -ethylimidazolium chloride (ME1C1) with Aluminum Chloride are of interest as electrolytes and nonaqueous reaction media. Results of NMR studies of MEI(+) in melts of various composition (determined by the mole fraction, N, of A1C13 used in forming a melt) were originally explained by a stack model of the ionic structure. In this model, the anions are located between stacked parallel MEI(+) ring planes. An alternative model has been suggested in which C1(-) forms ion pairs with MEI(+) by a H-bonding interaction through the H on the C-2 in the ring. Our IR studies particularly on deuteriated MEI(+), now show that C1(-) interacts with the hydrogens at the C-2, C-4, and C-5 members of the MEI(+) ring. Reprints. Pub. in Jnl. of the American Chemical Society, p2722-2726, 27 Apr 1988.