Crystal structure of 1H,1′H-[2,2′-biimidazol]-3-ium hydrogen tartrate hemihydrate

Abstract

In the crystal of the title hydrated salt, C6H7N4+·C4H5O6−·0.5H2O, the biimidazole monocation, 1H,1′H-[2,2′-biimidazol]-3-ium, is hydrogen bonded,viaN—H...O, O—H...O and O—H...N hydrogen bonds, to the hydrogen tartrate anion and the water molecule, which is located on a twofold rotation axis, forming sheets parallel to (001). The sheets are linkedviaC—H...O hydrogen bonds, forming a three-dimensional structure. There are also C=O...π interactions present [O...π distances are 3.00 (9) and 3.21 (7) Å], involving the carbonyl O atoms and the imidazolium ring, which may help to consolidate the structure. In the cation, the dihedral angle between the rings is 11.6 (2)°.