4,4′-Dibromo-2-nitrobiphenyl

The title compound, C12H7Br2NO2, a biphenyl derivative, displays a twisted conformation with the two benzene rings making a dihedral angle of 55.34 (14)°. The dihedral angle between the nitro group and its parent benzene ring is 26.8 (2)°. The crystal structure is stabilized by intermolecular C—H⋯Br and C—H⋯O interactions, which lead to the formation of chains propagating along the c-axis direction.

The title compound, C 12 H 7 Br 2 NO 2 , a biphenyl derivative, displays a twisted conformation with the two benzene rings making a dihedral angle of 55.34 (14) . The dihedral angle between the nitro group and its parent benzene ring is 26.8 (2) . The crystal structure is stabilized by intermolecular C-HÁ Á ÁBr and C-HÁ Á ÁO interactions, which lead to the formation of chains propagating along the c-axis direction.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SU2358).
for dye carriers used in textile dyeing and polychlorinated biphenyls used in insecticides. The C-Br bond in certain biphenyl derivatives is labile and the compound can be used for the preparation of carboxylic acid functionalized biphenyl derivatives. 4,4'-Dibromo-2-nitro-biphenyl is used as an crucial precursor in the formation of 2,7-disubstituted carbazole derivatives (Dierschke et al., 2003;Blouin et al., 2007), which have been found to display unusual electronic properties when compared to the 3,6-disubstituted analogs (Thomas et al., 2001).
Structures of biphenyl and its derivatives have been studied extensively in the past and even now, because of the differences found in the inter-ring torsion angle φ in the solid state (Rajnikant et al., 1995), which alters the electronic properties.
In a continuation of our on-going research program aimed at investigating the trends in crystallization and crystal growth of some substituted biphenyl derivatives, the crystal and molecular structure of the title compound is presented herein.
In the crystal, there are no classical hydrogen bonds and the crystal structure is stabilized by intermolecular C-H···Br and C-H···O interactions (Table 1 and Fig. 2), which lead to the formation of one-dimensional chains propagating along the c axis direction.

Experimental
The title compound was synthesized by following a protocol reported in literature (Dierschke et al., 2003), in which the expensive fuming nitric acid was replaced by a potassium nitrate and sulfuric acid mixture. 4,4,-Dibromobiphenyl (25 g) was suspended in 120 ml of glacial acetic acid and heated to 363 K for 45 min. with efficient stirring. A preformed mixture of KNO 3 (18 g) and H 2 SO 4 (36 ml) was added drop wise maintaining the temperature at 363 K. After the addition was complete the mixture was heated and stirred for further 30 min. On completion of the reaction, the mixture was cooled and poured into water. The yellow precipitate formed was filtered and recrystallized from ethanol [Yield: 82%]. The spectral data matched with those reported in the literature (Dierschke et al., 2003).

Refinement
All the H atoms were included in calculated positions and treated as riding atoms: C-H = 0.93 Å with U iso (H) = 1.2U eq (C). Fig. 1. The molecular structure of the title compound, with atom numbering and displacement ellipsoids drawn at the 50% probability level.  Table 1 for details). 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.