Crystal structures of the two salts 2-methyl-1H-imidazol-3-ium nitrate–2-methyl-1H-imidazole (1/1) and 2-methyl-1H-imidazol-3-ium nitrate

摘要

The title salts, C4H7N2+·NO3?·C4H6N2, (I), and C4H7N2+·NO3?, (II), were obtained from solutions containing 2-methyl-imidazole and nitric acid in different concentrations. In the crystal structure of salt (I), one of the –NH H atoms of the imidazole ring shows half-occupancy, hence only every second mol-ecule is in its cationic form. The nitrate anion in this structure lies on a twofold rotation axis. The neutral 2-methyl-imidazole mol-ecule and the 2-methyl-1H-imidazol-3-ium cation inter-act through N—H?N hydrogen bonds to form [(C4H6N2)?(C4H7N2)+] pairs. These pairs are linked with two nitrate anions on both sides through bifurcated N—H?(O,O) hydrogen bonds into chains running parallel to [001]. In the crystal structure of salt (II), the C4H7N2+ cation and the NO3? anion are both located on a mirror plane, leading to a statistical disorder of the methyl H atoms. The cations and anions again inter-act through bifurcated N—H?(O,O) hydrogen bonds, giving rise to the formation of chains consisting of alternating anions and cations parallel to [100].