title: 1H-Benzimidazol-3-ium-2-carboxyl-ate dihydrate.
abstract: The title compound, C(8)H(6)N(2)O(2)·2H(2)O, crystallized as a zwitterion with the carboxyl group deprotonated and the imidazole group protonated. The dihedral angle between the benzimidazole ring and the pendant -CO(2) group is 0.62 (2)°. In the crystal, mol-ecules are linked into a three-dimensional network by N-H⋯O and O-H⋯O hydrogen bonds.
authors.forename: Xing-Jun
authors.initials: XJ
authors.lastname: Yao
authors.forename: Qian
authors.initials: Q
authors.lastname: Yuan