(4-Bromophenyl)(1H-indol-7-yl)methanone

In the crystal, the molecules of the title compound, C15H10BrNO, are connected into centrosymmetric dimers by pairs of N—H⋯O hydrogen bonds. The dihedral angle between the planes of indole ring system and benzene ring is 50.13 (5)°. The indole plane is significantly less twisted from the plane of the central C—C(=O)—C bridge than the benzene plane [dihedral angles = 15.51 (3) and 40.13 (7)°, respectively]. The bond angles within the benzene ring show an approximately additive effect of the influence of both substituents.

In the crystal, the molecules of the title compound, C 15 H 10 BrNO, are connected into centrosymmetric dimers by pairs of N-HÁ Á ÁO hydrogen bonds. The dihedral angle between the planes of indole ring system and benzene ring is 50.13 (5) . The indole plane is significantly less twisted from the plane of the central C-C( O)-C bridge than the benzene plane [dihedral angles = 15.51 (3) and 40.13 (7) , respectively]. The bond angles within the benzene ring show an approximately additive effect of the influence of both substituents.
CSC thanks the University of Mysore for research facilities.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: ER2074).

Comment
The synthesis of indole derivatives has long been a topic of fundamental interest to organic and medicinal chemists (Murphy et al., 1997). Indole derivatives are important pharmacologically, possessing anti-allergic (Shigenaga et al., 1993), central-nervous-system depressant (Sen Gupta et al., 1982), muscle relaxant (Butera et al.,2001), and anti-cancer (Al-Soud et al.,2004) properties. The Fischer indole synthesis is the most widely used method for the preparation of indole derivatives (e.g., Robinson, 1982). The title compound (I) is an intermediate for preparation of bromofenac, which is used as analgesic.
There are only few crystal structures of 7-substituted indoles in the Cambridge Crystallographic Database (Allen, 2002).
The conformation of the molecule I can be described by the mutual orientation of the three approximately planar fragments ( Fig. 1): indole system (maximum deviation from the least-squares plane of 0.0142 (7) Å), phenyl ring (maximum deviation 0.0145 (13) Å), and the central C-C(=O)-C bridge (0.0040 (16) Å). The dihedral angle between the terminal planes, of indole and phenyl fragments, is 50.13 (5)°, while it can be noted that the indole plane is less inclined with respect to the central bridge plane (15.51 (3)°) than is the phenyl one (40.13 (7)°). The geometry of the phenyl ring is affected by the presence of substituents; using the values given by Domenicano (1988) and obtained form the search of the CSD (Allen, 2002), it might be shown that the overall influence on the bond angles pattern is close to additivity of separate effects of both Br and COAr substituents.
In the crystal structure the molecules of (I) are connected into the centrosymmetric, hydrogen bonded pairs -R 2 2 (12) motifs -by means of relatively strong and linear N-H···O hydrogen bonds (Fig. 2). These dimers are packed by means of van der Waals and weak C-H···π interactions.

Refinement
Hydrogen atoms were put in the idealized positions, and refined as riding model. Fig. 1. Anisotropic ellipsoid representation of the compound I together with atom labelling scheme. The ellipsoids are drawn at 50% probability level, hydrogen atoms are depicted as spheres with arbitrary radii.  (4-Bromophenyl)(1H-indol-7-yl)methanone