Crystal structures of three hydrogen-bonded 1:2 compounds of chloranilic acid with 2-pyridone, 3-hy-droxy-pyridine and 4-hyroxypyridine.

ABSTRACT: The crystal structures of the 1:2 compounds of chloranilic acid (systematic name: 2,5-di-chloro-3,6-dihy-droxy-1,4-benzo-quinone) with 2-pyridone, 3-hy-droxy-pyridine and 4-hyroxypyridine, namely, bis-(2-pyridone) chloranilic acid, 2C₅H₅NO·C₆H₂Cl₂O₄, (I), bis-(3-hy-droxy-pyridinium) chloranilate, 2C₅H₆NO⁺·C₆Cl₂O₄^2-, (II), and bis-(4-hy-droxy-pyridinium) chloranilate, 2C₅H₆NO⁺·C₆Cl₂O₄^2-, (III), have been determined at 120?K. In the crystal of (I), the base mol-ecule is in the lactam form and no acid-base inter-action involving H-atom transfer is observed. The acid mol-ecule lies on an inversion centre and the asymmetric unit consists of one half-mol-ecule of chloranilic acid and one 2-pyridone mol-ecule, which are linked via a short O-H?O hydrogen bond. 2-Pyridone mol-ecules form a head-to-head dimer via a pair of N-H?O hydrogen bonds, resulting in a tape structure along [201]. In the crystals of (II) and (III), acid-base inter-actions involving H-atom transfer are observed and the divalent cations lie on an inversion centre. The asymmetric unit of (II) consists of one half of a chloranilate anion and one 3-hy-droxy-pyridinium cation, while that of (III) comprises two independent halves of anions and two 4-hy-droxy-pyridinium cations. The primary inter-molecular inter-action in (II) is a bifurcated O-H?(O,O) hydrogen bond between the cation and the anion. The hydrogen-bonded units are further linked via N-H?O hydrogen bonds, forming a layer parallel to the bc plane. In (III), one anion is surrounded by four cations via O-H?O and C-H?O hydrogen bonds, while the other is surrounded by four cations via N-H?O and C-H?Cl hydrogen bonds. These inter-actions link the cations and the anions into a layer parallel to (301).

SUBMITTER: Gotoh K 

PROVIDER: S-EPMC5730315 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature