title: Redetermination of pyridine-4-carbonitrile-chloranilic acid (1/1) at 180 K.
abstract: In the crystal structure of the title compound, C(6)H(4)N(2)·C(6)H(2)Cl(2)O(4), two chloranilic acid (systematic name: 2,5-dichloro-3,6-dihydr-oxy-1,4-benzoquinone) mol-ecules are connected by O-H⋯O hydrogen bonds to form a dimeric unit. The pyridine-4-carbonitrile mol-ecules are linked on both sides of the dimer via N⋯H⋯O hydrogen bonds to give a centrosymmetric 2:2 complex of pyridine-4-carbonitrile and chloranilic acid. The H atom in the N⋯H⋯O hydrogen bond is disordered over two positions with approximately equal occupancies. The pyridine ring makes a dihedral angle of 61.54 (14)° with the chloranilic acid plane. The 2:2 units are further linked by inter-molecular C-H⋯O and C-H⋯Cl hydrogen bonds. This determination presents a siginficantly higher precision crystal structure than the previously published structure [Tomura & Yamasshita (2008 ▶). X-ray Struct. Anal. Online, 24, x31-x32].
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: Hirokazu
authors.initials: H
authors.lastname: Nagoshi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ishida