Synthesis, crystal structure, and Hirshfeld surface analysis of 1,3-di-hydro-2-benzimidazol-2-iminium 3-carb-oxy-4-hy-droxy-benzene-sulfonate.

The asymmetric unit of the title salt, CHN ·CHOS, comprises two 1,3-di-hydro-2-benzimidazol-2-iminium cations and two 2-hy-droxy-5-sulfobenzoate anions (' = 2). In the crystal, the mol-ecules inter-act through N-H⋯O, O-H⋯O hydrogen bonds and C-O⋯π contacts. The hydrogen-bonding inter-actions lead to the formation of layers parallel to (01).