Hydrogen-bonded structures of the isomeric compounds of phthalazine with 3-chloro-2-nitro-benzoic acid, 4-chloro-2-nitro-benzoic acid and 4-chloro-3-nitro-benzoic acid

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The structures of three isomeric compounds, C 7H 4ClNO 4·C 8H 6N 2, of phthalazine with chloro-and nitro-substituted benzoic acid, namely, 3-chloro-2-nitro-benzoic acid-phthalazine (1/1), (I), 4-chloro-2-nitro-benzoic acid-phthalazine (1/1), (II), and 4-chloro-3-nitro-benzoic acid-phthalazine (1/1), (III), have been determined at 190 K. In the asymmetric unit of each compound, there are two crystallographically independent chloro-nitro-benzoic acid-phthalazine units, in each of which the two components are held together by a short hydrogen bond between an N atom of the base and a carboxyl O atom. In one hydrogen-bonded unit of (I) and in two units of (II), a weak C-H⋯O inter-action is also observed between the two components. The N⋯O distances are 2.5715 (15) and 2.5397 (17) Å for (I), 2.5655 (13) and 2.6081 (13) Å for (II), and 2.613 (2) and 2.589 (2) Å for (III). In both hydrogen-bonded units of (I) and (II), the H atoms are each disordered over two positions with (N site):(O site) occupancies of 0.35 (3):0.65 (3) and 0.31 (3):0.69 (3) for (I), and 0.32 (3):0.68 (3) and 0.30 (3):0.70 (3) for (II). The H atoms in the hydrogen-bonded units of (III) are located at the O-atom sites.

Original languageEnglish
Pages (from-to)o473-o478
JournalActa Crystallographica Section C: Crystal Structure Communications
Issue number11
Publication statusPublished - Nov 1 2011


ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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