{2-[(3-Bromobenzylidene)amino]-5-chlorophenyl}(phenyl)methanone

In the title compound, C20H13BrClNO, the azomethine double bond [C=N = 1.246 (4) Å] adopts an E conformation. The bromo- and chlorophenyl rings are inclined to one another by 13.70 (11)°, and form dihedral angles of 76.68 (10) and 74.24 (7)°, respectively, with the phenyl ring. In the crystal, molecules are linked by C—H⋯O hydrogen bonds to form double stranded chains propagating along the b-axis direction.

In the title compound, C 20 H 13 BrClNO, the azomethine double bond [C N = 1.246 (4) Å ] adopts an E conformation. The bromo-and chlorophenyl rings are inclined to one another by 13.70 (11) , and form dihedral angles of 76.68 (10) and 74.24 (7) , respectively, with the phenyl ring. In the crystal, molecules are linked by C-HÁ Á ÁO hydrogen bonds to form double stranded chains propagating along the b-axis direction.   Table 1 Hydrogen-bond geometry (Å , ).

Comment
The title compound was prepared as a part of our ongoing reasearch on schiff bases (Khan et al., 2009;Aslam et al., 2011a,b;Zeb & Yousuf, 2011).

Experimental
A mixture of 3-bromobenzaldehyde (1 mol) and 2-amino-5-chlorobenzophenone (1 mol) in ethanol (50 ml) along with 3 drops of conc. H 2 SO 4 was refluxed for 5 h at 343 K. After cooling, the mixture was concentrated to one third under reduced pressure. The concentrated reaction mixture was kept at room temperature and orange red crystals were obtained after five days. The crystalline product was collected, washed with methanol and dried to afford the title compound in 87% yield. Slow evaporation of a methanol solution afforded yellow crystals suitable for single-crystal X-ray diffraction studies. All chemicals were purchased from Sigma-Aldrich.

Refinement
H atoms were positioned geometrically with C-H = 0.93 Å, and constrained to ride on their parent atoms with U iso (H) = 1.2U eq (C).  The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are presented as small spheres of arbitrary radius.

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.