crystal structure of 2-(1h-imidazol-3-ium-4-yl)ethanaminium dichloride, a re-determination

The crystal structure of the title molecular salt, C5H11N3+·2Cl−, was redetermined. In comparison with the previous study [Bonnet et al. (1975). Bull. Soc. Fr. Mineral. Crist. 98, 208–213.], the positions of some H atoms were corrected, allowing a more accurate description of the hydrogen-bonding scheme. In addition, the absolute structure was also determined. The maximum differences in terms of bond lengths and angles between the two determinations are 0.022 Å and 1.43°, respectively. The organic cation display a anti conformation of the protonated amine function and the imidazolium ring. The dihedral angle between the imidazolium plane and the plane through the C—C—N side chain is 29.58 (3)°. In the crystal, the organic cations and Cl− anions are stacked alternatively into layers parallel to (100). N—H...Cl hydrogen bonds between all H atoms of the ammonium group and both N—H groups of the imidazolium ring and the Cl− acceptor anions lead to the linkage of organic and inorganic layers into a three-dimensional network.