Far-Infrared Spectra and Hydrogen-Bond Frequencies of Imidazole

Abstract

Far-infrared spectra of imidazole, imidazole-d4, 1-methyl imidazole, and 1-methyl-d3 imidazole have been examined in the 300 − 33-cm− 1 range. Six of the nine infrared-active lattice modes of crystalline imidazole have been observed and assigned. A tentative assignment of these frequencies in terms of hydrogen-bond motion is given. Far-infrared spectra of solid and liquid imidazole and its methyl derivatives are compared and discussed. There is no obvious relationship between the hydrogen-bond frequencies and the structure of the νNH absorption band of crystalline imidazole.