title: (E)-2-[(2-Hydr-oxy-5-nitro-phen-yl)iminiometh-yl]phenolate.
abstract: In the title mol-ecule, C(13)H(10)N(2)O(4), the dihedral angle between the mean planes of the benzene and phenolate rings is 21.6 (4)°. The nitro O atoms are twisted slightly out of the plane of the ring to which the nitro group is attached [dihedral angle 8.4 (3)°]. The amine group forms an intra-molecular hydrogen bond with both nearby O atoms. An extended π delocalization throughout the entire mol-ecule exists producing a zwitterionic effect in this region of the mol-ecule. The shortened C-O bond [1.2997 (15) Å] in concert with the slightly longer C-OH bond [1.3310 (16) Å] provide evidence for this effect. The crystal packing is influenced by strong inter-molecular O-H⋯O hydrogen bonding. As a result, mol-ecules are linked into an infinite zigzag chain running along the b axis. A MOPAC PM3 calculation provides support to these observations.
authors.forename: Yousef M
authors.initials: YM
authors.lastname: Hijji
authors.forename: Belygona
authors.initials: B
authors.lastname: Barare
authors.forename: Ray J
authors.initials: RJ
authors.lastname: Butcher
authors.forename: Jerry P
authors.initials: JP
authors.lastname: Jasinski