Infrared matrix isolation studies of complexes between N,N-dimethylacetamide and hydrogen halides. Part 2.—Hydrogen iodide complexes

Abstract

Infrared spectra are reported of strongly hydrogen-bonded 1:1 and 1:2 complexes of N,N-dimethylacetamide with hydrogen iodide in argon, krypton and nitrogen matrices. Two forms of the 1:1 complex were found in a nitrogen matrix. The 1:1 complexes in argon and krypton matrices and one form in a nitrogen matrix exhibit a small degree of proton transfer to the amide; these complexes are dissociated by infrared irradiation in the CH stretching region to form weakly interacting DMA–HI pairs. The process may be reversed by annealing the matrix. The second form of the 1:1 complex in a nitrogen matrix exhibits a greater degree of proton transfer and is unaffected by infrared irradiation. In the 1:2 complexes, the second hydrogen iodide molecule hydrogen bonds to the nitrogen atom of the amide; these complexes are unaffected by infrared irradiation.