A triclinic polymorph of 4-cyano­pyridinium hydrogen chloranilate

The asymmetric unit of the triclinic polymorph of the title compound (systematic name: 4-cyano­pyridinium 2,5-dichloro-4-hy­droxy-3,6-dioxocyclo­hexa-1,4-dien-1-olate), C₆H₅N₂⁺·C₆HCl₂O₄⁻, consists of two crystallographically independent cation–anion units, in each of which the cation and the anion are linked by an N—H...O hydrogen bond. In the units, the dihedral angles between the cation and anion rings are 78.43 (11) and 80.71 (11)°. In the crystal, each unit independently forms a chain through N—H...O and O—H...N hydrogen bonds; one chain runs along the c axis while the other runs along [011]. Weak C—H...O, C—H...N and C—H...Cl inter­actions are observed between the chains.