4-Bromo-N-phenylaniline

In the title compound, C12H10BrN, the dihedral angle between the benzene rings is 52.5 (1)°, whereas the pitch angles, or the angles between the mean plane of each aryl group ‘propeller blade’ and the plane defined by the aryl bridging C—N—C angle, are 19.6 (2) and 36.2 (3)°. While the N—H group is not involved in hydrogen-bonding interactions, the structure exhibits a network of intermolecular C—H⋯π and N—H⋯π interactions.

In the title compound, C 12 H 10 BrN, the dihedral angle between the benzene rings is 52.5 (1) , whereas the pitch angles, or the angles between the mean plane of each aryl group 'propeller blade' and the plane defined by the aryl bridging C-N-C angle, are 19.6 (2) and 36.2 (3) . While the N-H group is not involved in hydrogen-bonding interactions, the structure exhibits a network of intermolecular C-HÁ Á Á and N-HÁ Á Á interactions.

Comment
Diphenylamines have uses in chemical synthesis and materials chemistry, and they have been investigated for their biological activity (Krzymiński et al., 2009). The title compound, a brominated diphenyl amine, was first synthesized by the photolysis of 4-diazodiphenylamine in the presence of HBr (Sus, 1947). More recently, halogenated diphenylamines have been prepared by copper catalyzed coupling reactions (He et al., 2008). The title compound is an amine analogue of a class of brominated diphenyl ether materials (de Wit, 2002). Polybrominated diphenyl ethers are commonly used as flame retardants in consumer products and electronics and have been found in humans (Lunder et al., 2010). The title compound is a monobrominated diphenyl amine derivative with a "propeller blade" disposition of the aryl rings about the bridging nitrogen atom. The aryl-bridging C4-N1-C7 angle is 126.4 (2)°, similar to the C-N-C bond angle of 126.1 (2)° found in the isomorphous structure of 4-methoxy-N-phenylaniline (Krzymiński et al., 2009). The dihedral angle is found to be 52.5 (1)°, whereas the pitch angles are 19.6 (2)° and 36.2 (3)°. The pitch angles are the angles between the mean plane of each aryl group "propeller blade" and the plane defined by the three atoms C4-N1-C7 (Lim & Tanski, 2007;Duong & Tanski, 2011).
In 4-methoxy-N-phenylaniline, the dihedral angle is somewhat larger, 59.9 (2) The structure reveals that there is no intermolecular hydrogen bonding, however, a network of intermolecular C-H···π and N-H···π bonds exists (Table 1), as in the isomorphous structure of 4-methoxy-N-phenylaniline (Krzymiński et al., 2009). These interactions are shorter in the title compound. The N-H···π centroid distance of 2.65 Å (Fig. 2) is shorter than the 2.88 Å distance observed in 4-methoxy-N-phenylaniline, and the N-H···π centroid angle of 175° is closer to linear than the 142° angle observed in 4-methoxy-N-phenylaniline, resulting in an interaction where the amine proton is directed at the center of the aromatic ring (Fig. 2), as opposed to at the edge of the ring as found the structure of 4-methoxy-N-phenylaniline.

Refinement
All non-hydrogen atoms were refined anisotropically. Hydrogen atoms on carbon were included in calculated positions and were refined using a riding model at C-H = 0.95Å and U iso (H) = 1.2 × U eq (C) of the aryl C-atoms. The hydrogen atom on nitrogen was refined semifreely with the help of a distance restraint, d(N-H) = 0.85 (2) Å and U iso (H) = 1.2 × U eq (N).
There are three difference peaks > 1 e/Å 3 . The first and third highest difference peaks of 1.72 and 1.10 e/Å 3 are < 0.8 Å from Br1, and the second highest difference peak of 1.64 e/Å 3 is very close to the calculated H10 position. The extinction parameter (EXTI) refined to zero and was removed from the refinement.  Fig. 1. A view of the title compound, with displacement ellipsoids shown at the 50% probability level. Fig. 2. A view of the N-H···π intermolecular interaction with displacement ellipsoids shown at the 50% probability level [Symmetry codes: (i) x -1/2, y + 3/2, -z]. 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.