2-(4-Bromophenyl)-N-(pyrazin-2-yl)acetamide

In the title compound, C12H10BrN3O, the dihedral angle between the mean planes of the 4-bromophenyl and pyrazin-2-yl rings is 54.6 (3)°. An intramolecular C—H⋯O hydrogen bond generates an S(6) graph-set motif. In the crystal, weak N—H⋯N hydrogen bonds link the molecules into chains along [100]. The chains are linked via C—H⋯N and C—H⋯O hydrogen bonds, forming two-dimensional networks lying parallel to the ab plane.

In the title compound, C 12 H 10 BrN 3 O, the dihedral angle between the mean planes of the 4-bromophenyl and pyrazin-2-yl rings is 54.6 (3) . An intramolecular C-HÁ Á ÁO hydrogen bond generates an S(6) graph-set motif. In the crystal, weak N-HÁ Á ÁN hydrogen bonds link the molecules into chains along [100]. The chains are linked via C-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds, forming two-dimensional networks lying parallel to the ab plane.
BN thanks the UGC for financial assistance through a BSR one-time grant for the purchase of chemicals. PSN thanks Mangalore University for research facilities and the DST-PURSE for financial assistance. JPJ acknowledges the NSF-MRI program (grant No. CHE-1039027) for funds to purchase the X-ray diffractometer.
In (I) the dihedral angle between the mean planes of the 4-Bromophenyl and pyrazine rings is 54.6 (3)° ( Fig. 1). An intramolecular C-H···O hydrogen bond generates an S(6) graph-set motif. Bond lengths are in normal ranges (Allen et al., 1987). In the crystal, weak N-H···N hydrogen bonds link the molecules into chains along [100]. The chains are linked via weak C-H···N and C-H···O intermolecular interactions, forming two-dimensional networks lying parallel to the ab plane.
Experimental 4-Bromophenylacetic acid (0.213 g, 1 mmol), 2-aminopyrazine (0.095 g, 1 mmol) and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (1.0 g, 0.01 mol) were dissolved in dichloromethane (20 mL) (Fig. 3). The mixture was stirred in presence of triethylamine at 273 K for about 3 h. The contents were poured into 100 ml of ice-cold aqueous hydrochloric acid with stirring, which was extracted thrice with dichloromethane. The organic layer was washed with saturated NaHCO 3 solution and brine solution, dried and concentrated under reduced pressure to give the title compound (I). Single crystals were grown from methylene chloride by the slow evaporation method (M.P.: 433-435 K).

Refinement
All of the H atoms were placed in their calculated positions and then refined using the riding model with Atom-H lengths of 0.93Å (CH) or 0.97Å (CH 2 ). Isotropic displacement parameters for these atoms were set to 1.2 (CH, CH 2 ) times U eq of the parent atom.

Computing details
Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2012 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).    Reaction scheme. 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.