2,3-Dibromo-1,3-bis(4-chlorophenyl)propan-1-one

In the title compound, C15H10Br2Cl2O, the terminal benzene rings make a dihedral angle of 31.1 (2)° with each other. In the crystal, molecules are stacked along the a axis and consolidated by C—H⋯π interactions. Short Cl⋯Cl [3.1140 (17) Å] and Br⋯Cl [3.4565 (13) Å] contacts are observed.


Experimental
Cg1 is the centroid of C1-C6 ring.
Chalcones are prepared by the condensation of acetophenone with appropriately substituted aromatic aldehydes in ethanol medium employing sodium hydroxide as catalyst. Bromination of these propenones were carried out using bromine in glacial acetic acid medium to give dibromopropanones (Rai et al., 2008). In view of the importance of chalcones, the synthesis and crystal structure of the title compound has been carried out.
In the crystal packing, Fig. 2, the molecules are stacked down the a axis and consolidated by C11-H11A···Cg1 (Table   1) interactions, where Cg1 is the centroid of the C1-C6 benzene ring. There is no significant hydrogen bond observed in this compound.
Experimental 1,3-Bis(p-chlorophenyl)prop-2-en-1-one (0.01 mol) was dissolved in glacial acetic acid (25 ml) by gentle warming. A solution of bromine in glacial acetic acid [30% (w/v)] was added to it with constant stirring till the yellow color of the bromine persisted. The reaction mixture was kept aside at room temperature for overnight. Crystals of dibromopropanones separated out were collected by filtration and washed with ethanol and dried. It was then recrystallized from ethanol. Crystals suitable for X-ray analysis were obtained from ethanol by slow evaporation.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.
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 > 2sigma(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.