1-Carboxymethyl-3-methyl-1H-imidazol-3-ium chloride 2-(3-methyl-1H-imidazol-3-ium-1-yl)acetate monohydrate: a crystal stabilized by imidazolium zwitterions

The title compound, C6H9N2O2+center dot Cl-center dot C6H8N2O2 center dot H2O, contains one 2-(3-methyl-1H-imidazol-3-ium-1-yl)acetate inner salt molecule, one 1-carboxymethyl-3-methyl-1H-imidazol-3-ium cation, one chloride ion and one water molecule. In the extended structure, chloride anions and water molecules are linked via O-H center dot center dot center dot Cl hydrogen bonds, forming an infinite one-dimensional chain. The chloride anions are also linked by two weak C-H center dot center dot center dot Cl interactions to neighbouring methylene groups and imidazole rings. Two imidazolium moieties form a homoconjugated cation through a strong and asymmetric O-H center dot center dot center dot O hydrogen bond of 2.472 (2) angstrom. The IR spectrum shows a continuous D-type absorption in the region below 1300 cm(-1) and is different to that of 1-carboxymethyl-3-methylimidazolium chloride [Xuan, Wang & Xue (2012). Spectrochim. Acta Part A, 96, 436-443].