4-Ammonio­benzamidinium 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 tetra­hedral environment. The aromatic rings of the amidinium cations are π-stacked, with a centroid–centroid distance of 4.178 (1) Å.