2,2,2-Tribromo-N-(3-chlorophenyl)acetamide

In the title compound, C8H5Br3ClNO, the conformation of the N—H bond is anti to the 3-chloro substituent in the benzene ring. An intramolecular N—H⋯Br hydrogen bond occurs. In the crystal, molecules are packed into infinite chains in the a-axis direction by N—H⋯O hydrogen bonds.

In the title compound, C 8 H 5 Br 3 ClNO, the conformation of the N-H bond is anti to the 3-chloro substituent in the benzene ring. An intramolecular N-HÁ Á ÁBr hydrogen bond occurs. In the crystal, molecules are packed into infinite chains in the aaxis direction by N-HÁ Á ÁO hydrogen bonds.

P.A.S. thanks the Council of Scientific and Industrial
Research (CSIR), Government of India, New Delhi, for the award of a research fellowship.  The structure of (I), was determined as a part of our ongoing study of the effect of ring and side chain substituents on the crystal structures of N-aromatic amides (Gowda et al., 2008(Gowda et al., , 2009(Gowda et al., , 2010. In (I) the conformation of the N-H bond is anti to the 3-chloro substituent in the benzene ring ( Fig.1), similar to that observed in N-(3-chlorophenyl)acetamide (II) (Gowda et al., 2008), and that between the N-H bond and the 3-methyl group in N-(3-methylphenyl)2,2,2-tribromoacetamide (III) (Gowda et al., 2009), but contrary to the syn conformation observed between the N-H bond and the 2-Chloro group in N-(2-chlorophenyl)2,2,2-tribromoacetamide (IV) (Gowda et al., 2010).
The structure of (I) shows both intramolecular N-H···Br and intermolecular N-H···O H-bonding. A packing diagram ( Fig. 2) illustrates the N1-H1N···O1 hydrogen bonds (Table 1) involved in the formation of molecular chains along the a-axis of the unit cell.

Experimental
The title compound was prepared from 3-chloroaniline, tribromoacetic acid and phosphorylchloride according to the literature method (Gowda et al., 2003). The purity of the compound was checked by determining its melting point. It was further characterized by recording its infrared spectra. Rod like colourless single crystals of the title compound used for X-ray diffraction studies were obtained by a slow evaporation of its ethanolic solution at room temperature.

Refinement
The H atoms were positioned with idealized geometry using a riding model [N-H = 0.86 Å, C-H = 0.93 Å] and were refined with a riding model conith isotropic displacement parameters (set to 1.2 times of the U eq of the parent atom).
The residual electron-density features are located in the region of Br1 and Br2. The highest peak is 0.98 Å from Br1 and the deepest hole is 1.39 Å from Br2. Fig. 1. Molecular structure of (I), showing the atom labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are represented as small spheres of arbitrary radii.

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