Crystal structure of 4-chloro-2-nitrobenzoic acid with 4-hydroxyquinoline: a disordered structure over two states of 4-chloro-2-nitrobenzoic acid–quinolin-4(1H)-one (1/1) and 4-hydroxyquinolinium 4-chloro-2-nitrobenzoate

The title compound, C 9 H 7.5 NO·C 7 H 3.5 ClNO 4 , was analysed as a disordered structure over two states, viz . co-crystal and salt, accompanied by a keto–enol tautomerization in the base molecule. The co-crystal is 4-chloro-2-nitrobenzoic acid–quinolin-4(1 H )-one (1/1), C 7 H 4 ClNO 4 ·C 9 H 7 NO, and the salt is 4-hydroxyquinolinium 4-chloro-2-nitrobenzoate, C 9 H 8 NO + ·C 7 H 3 ClNO 4 − . In the compound, the acid and base molecules are held together by a short hydrogen bond [O...O = 2.4393 (15) Å], in which the H atom is disordered over two positions with equal occupancies. In the crystal, the hydrogen-bonded acid–base units are linked by N—H...O and C—H...O hydrogen bonds, forming a tape structure along the a- axis direction. The tapes are stacked into a layer parallel to the ab plane via π–π interactions [centroid–centroid distances = 3.5504 (8)–3.9010 (11) Å]. The layers are further linked by another C—H...O hydrogen bond, forming a three-dimensional network. Hirshfeld surfaces for the title compound mapped over shape-index and d norm were generated to visualize the intermolecular interactions.

Abstract licence: CC BY

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