Hydrogen-bonded sheets in 2-(2-aminophenyl)-1H-benzimidazol-3-ium dihydrogen phosphate.

The title salt, C(13)H(12)N(3)(+).H(2)PO(4)(-), contains a nonplanar 2-(2-aminophenyl)-1H-benzimidazol-3-ium cation and two different dihydrogen phosphate anions, both situated on twofold rotation axes in the space group C2. The anions are linked by O-H...O hydrogen bonds into chains of R(2)(2)(8) rings. The anion chains are linked by the cations, via hydrogen-bonding complementarities and electrostatic interactions, giving rise to a sheet structure with alternating rows of organic cations and inorganic anions. Comparison of this structure with that of the pure amine reveals that the two compounds generate characteristically different sheet structures. The anion-anion chain serves as a template for the assembly of the cations, suggesting a possible application in the design of solid-state materials.