3-Chlorobenzohydrazide

In the title compound, C7H7ClN2O, the hydrazide group is inclined at a dihedral angle of 32.30 (11)° with respect to the benzene ring. The amino H atoms form intermolecular N—H⋯O hydrogen bonds with the O atoms of two adjacent molecules, resulting in 10-membered rings of graph-set motif R 2 2(10). The imino H atom is also involved in an intermolecular hydrogen bond with an amino N atom of a symmetry-related molecule, resulting in a zigzag chain along the b axis. The structure is further consolidated by an intramolecular N—H⋯O interaction, which results in a five-membered ring.

In the title compound, C 7 H 7 ClN 2 O, the hydrazide group is inclined at a dihedral angle of 32.30 (11) with respect to the benzene ring. The amino H atoms form intermolecular N-HÁ Á ÁO hydrogen bonds with the O atoms of two adjacent molecules, resulting in 10-membered rings of graph-set motif R 2 2 (10). The imino H atom is also involved in an intermolecular hydrogen bond with an amino N atom of a symmetry-related molecule, resulting in a zigzag chain along the b axis. The structure is further consolidated by an intramolecular N-HÁ Á ÁO interaction, which results in a five-membered ring.

Comment
Hydrazides are known to have different biological activities (Ashiq, Ara et al., 2008;Ara et al., 2007). In order to study the biological activity of 3-chlorobenzohydrazide, we undertook the synthesis of the title compound and report its crystal structure in this paper. The title compound was found to be antifungal (Maqsood et al., 2006). The structures of benzhydrazide (Kallel et al., 1992), and its p-chloro (Saraogi et al., 2002), m-methoxy (Jamal et al., 2009), m-nitro (Ratajczak et al. 2001), p-bromo  and p-iodo  analogues have been reported.
The bond lengths and bond angles in the title compound ( Fig. 1) are comparable with the corresponding distances and angles reported in its analogues quoted above. The hydrazide moiety, C7/O1/N1/N2, is oriented at a dihedral angle of 32.30 (11)° with respect to the plane of benzene ring C1-C6. The H atoms bonded to N2 form intermolecular hydrogen bonds of the type N-H···O with O atoms of two adjacent molecules, resulting in 10-membered rings which may be assigned to R 2 2 (10) motif in graph set notation (Bernstein et al., 1995). The H-atom bonded to N1 is also involved in an intermolecular hydrogen bond with N2, linking the molecules into a zigzag chain along the b axis (Tab. 1 and Fig. 2). The structure is further stabilized by an intramolecular interaction, N2-H2···O1, resulting in a five membered ring in S(5) motif (Bernstein et al., 1995).

Experimental
All reagent-grade chemicals were obtained from Aldrich and Sigma Chemical companies and were used without further purification. To a solution of ethyl-3-chlorobenzoate (3.69 g, 20 mmol) in 75 ml ethanol, hydrazine hydrate (5.0 ml, 100 mmol) was added. The mixture was refluxed for 5 h and a solid was obtained upon removal of the solvent by rotary evaporation. The resulting solid was washed with hexane to afford the title compound (yield 75%). The crystals of the title compound suitable for crystallographic study were grown from a solution of methanol by slow evaporation at room temperature.

Refinement
H atoms were positioned geometrically, with C-H = 0.93 Å for aromatic and constrained to ride on their parent atoms. The H-atoms attached to N1 and N2 were taken from Fourier maps and their coordinates were refined. The thermal parameters, U iso , of H-atoms were allowed at 1.2 times of the U eq of their parent atoms. Fig. 1. The molecular structure of the title compound with displacement ellipsoids drawn at 50% probability level.

Special details
Experimental. the reflection 1 0 0 has been obscured by the beam stop so it was omitted in the final refinement 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 > 2σ(F 2 ) is used only for calculating Rfactors(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.