N′-(2-Hydroxy-3,5-diiodobenzylidene)-2-methoxybenzohydrazide

The title compound, C15H12I2N2O3, was synthesized by the condensation of equimolar amounts of 3,5-diiodosalicylaldehyde and 2-methoxybenzohydrazide in a methanol solution. There are two independent molecules, A and B, in the asymmetric unit. The dihedral angle between the two benzene rings is 30.2 (2)° for molecule A and 21.7 (2)° for molecule B. There are intramolecular O—H⋯N and N—H⋯O hydrogen bonds in each molecule. The crystal studied was an inversion twin with a 0.59 (3):0.41 (3) domain ratio.


S1. Comment
Schiff bases such as hydrazides are known to act as versatile ligands in coordination chemistry (Ali et al., 2005). We report herein the crystal structure of the new title benzohydrazide derivative (I), Fig. 1.
Compound (I) consists two independent molecules, A and B in the asymmetric unit. The dihedral angles between the two benzene rings are 30.2 (2)° for A and 21.7 (2)° for B, respectively. All the bond lengths are comparable to those observed in other similar compounds (Yehye et al., 2008a,b;Jing et al., 2006);Ling et al., 2008). There are two intramolecular O-H···N and N-H···O hydrogen bonds (Table 1) in each molecule.

S3. Refinement
The crystal studied was an inversion twin with a 0.59 (3):0.41 (3) domain ratio. The number of Friedel pairs in the data set is 3436. Atoms H2 and H4B were located in a difference Fourier map and refined isotropically, with the N-H distance restrained to 0.90 (1) Å, and with U iso set to 0.08 Å 2 . All H atoms bound to carbon and oxygen were refined using riding models with d(C-H) = 0.93-0.96 Å, d(O-H) = 0.82 Å, U iso = 1.2U eq (C) and 1.5U eq (O and methyl C).

Figure 1
The molecular structure of (I), showing the atom-numbering scheme and 30% probability displacement ellipsoids. H atoms are shown as spheres of arbitrary radii.

N′-(2-Hydroxy-3,5-diiodobenzylidene)-2-methoxybenzohydrazide
Crystal data C 15 H 12 I 2 N 2 O 3 M r = 522.07 Orthorhombic, Pna2 1 Hall symbol: P 2c -2n a = 16.073 (2)   where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.78 e Å −3 Δρ min = −0.56 e Å −3 Absolute structure: Flack (1983), 3436 Friedel pairs Absolute structure parameter: 0.59 (3) 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.  0.093 (7) 0.053 (6) 0.076 (7