title: A triclinic polymorph of 4-cyano-pyridinium hydrogen chloranilate.
abstract: THE ASYMMETRIC UNIT OF THE TRICLINIC POLYMORPH OF THE TITLE COMPOUND (SYSTEMATIC NAME: 4-cyano-pyridinium 2,5-dichloro-4-hy-droxy-3,6-dioxocyclo-hexa-1,4-dien-1-olate), C(6)H(5)N(2) (+)·C(6)HCl(2)O(4) (-), 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 inter-actions are observed between the chains.
authors.affiliation: Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530,  Japan.
authors.forename: Kazuma
authors.initials: K
authors.lastname: Gotoh
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ishida