(E)-6-Chloro-N′-(3,5-dichloro-2-hydroxybenzylidene)nicotinohydrazide

The title Schiff base compound, C13H8Cl3N3O2, was synthesized by the condensation reaction of 3,5-dichlorosalicylaldehyde with 6-chloronicotinic acid hydrazide in 95% ethanol. The molecule is nearly planar, with a dihedral angle of 1.9 (2)° between the aromatic ring planes, and an intramolecular O—H⋯N hydrogen bond is observed. In the crystal, the molecules are connected by intermolecular N—H⋯O hydrogen bonds into infinite chains propagating in [100].

The title Schiff base compound, C 13 H 8 Cl 3 N 3 O 2 , was synthesized by the condensation reaction of 3,5-dichlorosalicylaldehyde with 6-chloronicotinic acid hydrazide in 95% ethanol. The molecule is nearly planar, with a dihedral angle of 1.9 (2) between the aromatic ring planes, and an intramolecular O-HÁ Á ÁN hydrogen bond is observed. In the crystal, the molecules are connected by intermolecular N-HÁ Á ÁO hydrogen bonds into infinite chains propagating in [100].

C. Ren
Comment Schiff base compounds have been widely investigated over a century (Fan et al., 2007;Kim et al., 2005). Some of the complexes derived from Schiff bases have been found to have pharmacological and antitumor properties (Ren et al., 2002;Takeuchi,et al., 1998). In this paper, the crystal structure of the title compound, (I), a new Schiff base compound derived from the condensation reaction of 3,5-dichlorosalicylaldehyde with 6-chloronicotinic acid hydrazide is reported.
The molecule of (I) displays a trans configuration with respect to the C=N and C-N bonds (Fig. 1). All the bond lengths are within normal ranges (Allen et al., 1987), and are comparable to those in the related compound 6-chloro-N'-(2-hydroxy-1-naphthylmethylene)nicotinohydrazide (Zhi 2008). The Schiff base molecule is nearly planar, with a dihedral angle between the benzene ring and the pyridine ring of 1.9 (2)°. An intramolecular O-H···N hydrogen bond is observed. The molecules are connected via intermolecular N-H···O hydrogen bonds into infinite chains along the a axis (Table 1, Fig. 2).
Experimental 3,5-Dichlorosalicylaldehyde (0.1 mmol, 19.0 mg) and 6-chloronicotinic acid hydrazide (0.1 mmol, 17.1 mg) were dissolved in a 95% ethanol solution (10 ml). The mixture was stirred at room temperature to give a clear colorless solution. Light yellow blocks of (I) were formed by gradual evaporation of the solvent over a period of five days at room temperature.

Refinement
All H atoms were placed in geometrically idealized positions, with C-H = 0.93 Å, O-H = 0.82 Å and N-H = 0.86 Å and refined as riding with U iso (H) = 1.2U eq (C,N) or 1.5U eq (O). Fig. 1. The molecular structure of (I), with displacement ellipsoids drawn at the 30% probability level. The dashed lines indicate hydrogen bonds.  as those based on F, and R-factors based on ALL data will be even larger.