4-Ammonio-benzamidinium dichloride.

The crystal structure of the title compound, C(7)H(11)N(3) (2+)·2Cl(-), has been determined as part of a project focusing on the ability of the benzamidine system to form strong hydrogen bonds in aqueous media. It is commonly used as a ligand in affinity chromatography for purification and immobilization of enzymes. A twofold rotation axis runs along the axis of the cation. The orientation of the amidinium group with respect to the benzene ring is indicated by the N-C-C-C torsion angle of 40.2 (1)°. In the crystal structure, cations and anions are linked via hydrogen bonds. The chloride anion is surrounded by four ammonium cations in a tetra-hedral environment. The aromatic rings of the amidinium cations are π-stacked, with a centroid-centroid distance of 4.178 (1) Å.