Acta Cryst. (2012). E68, o2622
[ doi:10.1107/S1600536812033740 ]
Abstract: The title compound, C13H10N2O4, crystallized as the zwitterionic tautomer. As a result, the phenolate C-O- bond [1.296 (2) Å] is shorter than a normal Csp2-O(H) bond, and the azomethine C=N bond [1.314 (2) Å] is longer than a normal C=N double bond. The molecule is nearly planar, the mean plane of the nitro-substituted benzene ring forming dihedral angles of 9.83 (7) and 8.45 (9)° with the other benzene ring and with the nitro group, respectively. The molecular conformation is stabilized by an intramolecular N-HO hydrogen bond. In the crystal, strong O-HO hydrogen bonds link the molecules into double-stranded chains along the b-axis direction. Within the chains there are - interactions involving the benzene rings of adjacent molecules [centroid-centroid distance = 3.669 (1) Å]. The chains are linked via C-HO hydrogen bonds, forming R21(6), R21(7) and R22(10) ring motifs.
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