N′-[(E)-1-(4-Bromophenyl)ethylidene]-2-(2-methyl-4-nitro-1H-imidazol-1-yl)acetohydrazide

In the title compound, C14H14BrN5O3, the mean plane of the imidazole ring (r.m.s deviation = 0.004 Å) forms a dihedral angle of 58.13 (7)° with the benzene ring. In the crystal, molecules are linked via N—H⋯O, C—H⋯O and C—H⋯N hydrogen bonds into a three-dimensional network. A short Br⋯Br contact of 3.4932 (2) Å also occurs.


Hoong-Kun Fun, Ching Kheng Quah, Priya V Frank, Damodara N and Balakrishna Kalluraya Comment
The chemistry of imidazole derivatives has been the subject of much interest due to their importance in various applications and also due to their widespread potential as well as proven biological and pharmacological activities (Priya & Kalluraya, 2005). Various applications of imidazoles have been listed in the literature with functions as widely divergent as antidepressant agents (Krapcho & Turk, 1966), as a marker for imaging tumor hypoxia ( Chu et al., 2004), and in antibacterial activity (Khalafi-Nezhad et al., 2005). In view of the obvious importance of imidazole derivatives as potential pharmacological agents, herein we report the crystal structure of the above imidazole derivative.

Experimental
The title compound was synthesized by refluxing a mixture of 2-(2-methyl-4-nitro-1H-imidazol-1-yl)acethydrazide (0.1 mol) and 1-(4-bromophenyl)ethanone (0.1 mol) in glacial acetic acid for 1 hour. After cooling the reaction mixture to room temperature and evaporation of the solvent under reduced pressure, the solid separated was filtered, washed with water and dried. The recrystallization of the sample was done using an ethanol-dioxane (1:1 v/v) mixture. The melting point of the compound was found to be 549 K. The slow evaporation of the ethanol-dioxane mixture of the compound gave crystals suitable for X-ray analysis.

Refinement
Atom H1N2 was located in a difference Fourier map and refined freely [N-H = 0.81 (2) Å]. All other hydrogen atoms were positioned geometrically and refined using a riding model with C-H = 0.95-0.99 Å and U iso (H) = 1.2 or 1.5 U eq (C).
A rotating-group model was applied for the methyl groups.

Computing details
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009    The crystal structure of the title compound, viewed along the a axis. H atoms not involved in hydrogen bonds (dashed lines) have been omitted for clarity.  (Cosier & Glazer, 1986) operating at 100.0 (1) K. 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 > 2sigma(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq