4-Formyl-2-nitrophenyl 4-bromobenzoate

In the title compound, C14H8BrNO5, the benzene rings form a dihedral angle of 62.90 (7)°. The central ester group is twisted away from the nitro-substituted and bromo-substituted rings by 71.67 (7) and 8.78 (15)°, respectively. The nitro group forms a dihedral angle of 7.77 (16)° with the benzene ring to which it is attached. In the crystal, molecules are linked by weak C—H⋯O interactions, forming C(12) chains which run along [001]. Halogen–halogen interactions [Br⋯Br = 3.523 (3) Å] within the chains stabilized by C—H⋯O interactions are observed.

In the title compound, C 14 H 8 BrNO 5 , the benzene rings form a dihedral angle of 62.90 (7) . The central ester group is twisted away from the nitro-substituted and bromo-substituted rings by 71.67 (7) and 8.78 (15) , respectively. The nitro group forms a dihedral angle of 7.77 (16) with the benzene ring to which it is attached. In the crystal, molecules are linked by weak C-HÁ Á ÁO interactions, forming C(12) chains which run along [001]. Halogen-halogen interactions [BrÁ Á ÁBr = 3.523 (3) Å ] within the chains stabilized by C-HÁ Á ÁO interactions are observed.

Tenorio Comment
Esters containing aromatic nitro-substituted rings can be used as precursors for the preparation of compounds with potential analgesic and anti-inflammatory properties (Jefford & Zaslona, 1985). Indeed, many pharmaceuticals come from a variety of nitroaromatic compounds. Acetaminophen for example, a widely used drug, is sinthesized from p-nitrophenol (Bhattacharya et al., 2006). Other nitro-aromatic esters show marked inhibitory activity against ischemic-induced electrocardiographic changes (Benedini et al., 1995). In order to complement the structural information about nitroaryl compounds the title ester, 4-formyl-2-nitrophenyl 4-bromo benzoate, (I), was synthesized. The molecular structure of (I) is shown in Fig respectively. The ester group is twisted away from the nitro-substituted and bromo-substituted benzene rings by 71.67 (7)° and 8.78 (15)° respectively. The nitro group forms a dihedral angle with the benzene ring to which it is attached of 7.77 (16)°.
Recent theoretical calculations show that halogen···halogen interactions are controlled by electrostatic forces and they display directional character (Awwadi et al., 2006). In the title structure, halogen···halogen interactions [Br···Br = 3.523 (3) Å] within the chains stabilized by C-H···O interactions are observed. This Br···Br distance is much shorter than the sum of the van der Waals radii (3.70 Å) (Bondi, 1964). These interactions can be considered type I with trans geometry (Hathwar et al., 2010).

Experimental
The reagents and solvents for the synthesis were obtained from the Aldrich Chemical Co., and were used without leaving the solvent to evaporate. IR spectra were recorded on a FT-IR SHIMADZU IR-Affinity-1 spectrophotometer.

Refinement
All the H-atoms attached to C atoms were positioned at geometrically idealized positions and treated as riding with C-H= 0.96 Å and U iso (H) = 1.2 U eq (C).

Figure 1
Molecular conformation and atom numbering scheme for the title compound with displacement ellipsoids drawn at the 50% probability level. H atoms are shown as spheres of arbitrary radius. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.43 e Å −3 Δρ min = −0.39 e Å −3 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 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.