(E)-2-(2-Hydroxy-5-iodobenzylidene)hydrazinecarboxamide

In the title molecule, C8H8IN3O2, there is an intramolecular O—H⋯N hydrogen bond between the hydroxy group and the imine N atom, which generates an S(6) ring. In the crystal, the carbonyl O atom accepts two different N—H⋯O hydrogen bonds, which connect molecules with two R 2 2(8) motifs.

In the title molecule, C 8 H 8 IN 3 O 2 , there is an intramolecular O-HÁ Á ÁN hydrogen bond between the hydroxy group and the imine N atom, which generates an S(6) ring. In the crystal, the carbonyl O atom accepts two different N-HÁ Á ÁO hydrogen bonds, which connect molecules with two R 2 2 (8) motifs.
Bond distances are in the normal range for similar hydrazone compounds (Abboud et al., 1995). The molecule is approximately planar, with an r.m.s. deviation from the mean plane through all 14 non-H atoms of 0.181 (2) Å. The dihedral angle between the phenyl ring plane and the least-squares plane through the N3-C8-O2-N2 unit is 14.00 (13)°. In the crystal structure of the title compound, the molecule adopts an E configuration with respect to the C7=N1 bond. In the crystal structure of the title compound, there is an intramolecular O-H···N hydrogen bonding between the hydroxyl group and imine nitrogen atom. The carbonyl group forms two different intermolecular N-H···O hydrogen bonds parallel to ac-plane which connects molecules with two R 2 2 (8) motifs (Table 1, Fig. 2).

Experimental
For preparing the title compound a methanol (10 ml) solution of 2-hydroxy-5-iodobenzaldehyde (1.5 mmol) was added drop-wise to a methanol solution (10 ml) of semicarbazide (1.5 mmol), and the mixture was refluxed for 3 h. The solution was then evaporated on a steam bath to 5 ml and cooled to room temperature. The light-yellow precipitates of the title compound were separated and filtered off, washed with 3 ml of cooled methanol and then dried in air. Colorless crystals were obtained from its methanol solution by slow solvent evaporation. Yield: 92%. IR  (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figure 1
The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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.