4-Chloro-3-nitrobenzamide

In the crystal of the title compound, C7H5ClN2O3, the molecules are linked by N—H⋯O and C—H⋯O hydrogen bonds. The π–π contact between the benzene rings, [centroid–centroid distance = 3.803 (3) Å] may further stabilize the structure.

In the crystal of the title compound, C 7 H 5 ClN 2 O 3 , the molecules are linked by N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds. Thecontact between the benzene rings, [centroidcentroid distance = 3.803 (3) Å ] may further stabilize the structure.

Related literature
For a related structure, see: Sun et al. (2006). For bond-length data, see: Allen et al. (1987).

4-Chloro-3-nitrobenzamide
Bo-Nian Liu, Shi-Gui Tang, Hao-Yuan Li and Cheng Guo S1. Comment Some derivatives of pyridine are important chemical materials. We report herein the crystal structure of the title compound.
In the molecule of the title compound (Fig 1), the bond lengths (Allen et al., 1987) and angles are within normal ranges. In the crystal structure, intermolecular N-H···O and C-H···O hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure. The π-π contact between the benzene rings, Cg1-Cg1 i [symmetry code: (i) -x, -y, 1 -z, where Cg1 is centroid of the ring A (C1-C6)] may further stabilize the structure, with centroid-centroid distance of 3.803 (3) Å.

S2. Experimental
For the preparation of the title compound, 4-chloro-3-nitrobenzoic acid (60.3 g, 0.32 mol) was suspended in thionyl chloride (180 ml) and heated at reflux for 5 h, then concentrated in vacuum as far as possible, the oily substance obtained.
Added ice ammonia water (300 ml) to the oil, cooling to room temperature, a precipitate formed, which was collected by filtration and washed with water. Pure title compound was obtained by crystallizing from methanol (Sun et al., 2006).
Crystals suitable for X-ray analysis were obtained by slow evaporation of a methanol solution.

S3. Refinement
H atoms were positioned geometrically, with N-H = 0.86 (for NH 2 ) and C-H = 0.93 Å for aromatic H and constrained to ride on their parent atoms, with U iso (H) = 1.2U eq (C,N).  The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Hydrogen bond is shown as dashed line. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.41 e Å −3 Δρ min = −0.51 e Å −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.