2-Hydroxy-N′-methyl-5-nitrobenzohydrazide

In the title compound, C8H9N3O4, there are two molecules in the asymmetric unit, one of which is in the zwitterionic form. The zwitterion contains an intramolecular N—H⋯O hydrogen bond and the other molecule contains both an intramolecular N—H⋯O and an intramolecular O—H⋯O hydrogen bond. In the crystal, N—H⋯O and N—H⋯N hydrogen bonds link the molecules, formimg a two-dimensional network parallel to (10-1).

In the title compound, C 8 H 9 N 3 O 4 , there are two molecules in the asymmetric unit, one of which is in the zwitterionic form. The zwitterion contains an intramolecular N-HÁ Á ÁO hydrogen bond and the other molecule contains both an intramolecular N-HÁ Á ÁO and an intramolecular O-HÁ Á ÁO hydrogen bond. In the crystal, N-HÁ Á ÁO and N-HÁ Á ÁN hydrogen bonds link the molecules, formimg a two-dimensional network parallel to (101).
Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009  Derivatives of salicylhydrazide exhibit prominent biological activites such as antimicrobial activity, inhibitor of receptor and enzyme inhibitor (Bagchi et al., 2004;Thompson et al., 2004;Al-Mawsawi et al., 2007). Several coordination sites exist in these compounds to lead to potential supramolecular structures. In our previous work, some anologs and their metal complexes were successfully sythesized and some latent functional studies were made (Jin et al., 2006a,b). As part of our ongoing studies, the preparation and X-ray structure determination of the title compound (I) was undertaken.
The asymmetric unit of (I) is shown in Fig. 1. There are two molecules in the asymmetric unit. One of the molecules is in the zwitterionic form. In the zwitterion N2 is protonated and O1 deprotonated. The bond lengths and angles in each molecule are unexceptional and agree with those reported for similar structures Luo et al., 2007;Xu & Liu, 2006;Zhang, 2012). In each molecule the non-H atoms, with the exception of the methyl and nitro groups, lie in an

Experimental
The title compound was systhesized by refluxing a mixture of ethyl 5-nitro-salicylate (0.1 mol) and methylhydrazine (0.2 mol) for 14 h. To the resulting solution acetic acid was added and it was cooled to room temperature. The mixture was evaporated and washed with diethyl ether. Single crystals suitable for X-ray diffraction analysis were grown by slow evaporation from a solution of (I) in methanol at room temperature.

Refinement
H atoms bonded to C atoms were placed in calculated positions, with C-H distances of 0.93-0.96 Å. They were included in the refinement in the riding-model approximation, with isotropic displacement parameters set to 1.2U eq of the carrier atom (1.5U eq for CH 3 H atoms). The amide and hydroxy H atoms were located in a difference Fourier map and refined isotropically.

Computing details
Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009   The asymmetric unit of (I) showing 30% probability displacement ellipsoids. Dashed lines indicate hydrogen bonds. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.