title: 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.
abstract: 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].
authors.affiliation: Laboratoire de Chimie Minérale et Analytique, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Senegal.
authors.forename: Mouhamadou Birame
authors.initials: MB
authors.lastname: Diop
authors.affiliation: Laboratoire de Chimie Minérale et Analytique, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Senegal.
authors.forename: Libasse
authors.initials: L
authors.lastname: Diop
authors.affiliation: Département de Chimie, Université de Montréal, 2900 Boulevard Édouard-Montpetit, Montréal, Québec, H3C 3J7, Canada.
authors.forename: Thierry
authors.initials: T
authors.lastname: Maris
keywords: 2-methyl-1H-imidazol-3-ium cations; bifurcated hydrogen bonds; chain structure; crystal structure