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

Kazuma Gotoh, Hiroyuki Ishida

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2 Citations (Scopus)


The crystal structures of the 1:2 compounds of chloranilic acid (systematic name: 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) with 2-pyridone, 3-hydroxypyridine and 4-hyroxypyridine, namely, bis(2-pyridone) chloranilic acid, 2C5H5NO·C6H2Cl2O4, (I), bis(3-hydroxypyridinium) chloranilate, 2C5H6NO+·- C6Cl2O4 2-, (II), and bis(4-hydroxypyridinium) chloranilate, 2C5H6NO+·- C6Cl2O4 2-, (III), have been determined at 120 K. In the crystal of (I), the base molecule is in the lactam form and no acid-base interaction involving H-atom transfer is observed. The acid molecule lies on an inversion centre and the asymmetric unit consists of one half-molecule of chloranilic acid and one 2-pyridone molecule, which are linked via a short O-H· · ·O hydrogen bond. 2-Pyridone molecules 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 interactions 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-hydroxypyridinium cation, while that of (III) comprises two independent halves of anions and two 4-hydroxypyridinium cations. The primary intermolecular interaction 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 interactions link the cations and the anions into a layer parallel to (301).

Original languageEnglish
Pages (from-to)1546-1550
Number of pages5
JournalActa Crystallographica Section E: Crystallographic Communications
Issue number10
Publication statusPublished - 2017


  • 2-pyridone
  • 3-hydroxypyridine
  • 4-hyroxypyridine
  • Chloranilic acid
  • Crystal structure
  • Hydrogen bond

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics


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