(E)-1-(4-Bromophenyl)ethan-1-one semicarbazone

In the title compound, C9H10BrN3O, the hydrazone portion and aliphatic chain are essentially coplanar [maximum deviation 0.057 (15) Å] and the mean plane makes a dihedral angle of 70.9 (6)° with the benzene ring. The main feature of the crystal structure is the intermolecular N—H⋯O hydrogen bond, which links molecules into zigzag chains along the a axis. These chains are further stacked along the b axis. The crystal structure features non-classical intermolecular C—H⋯O interactions. The crystal studied was a nonmerohedral twin, with a twin ratio of 0.505 (1):0.495 (1).

In the title compound, C 9 H 10 BrN 3 O, the hydrazone portion and aliphatic chain are essentially coplanar [maximum deviation 0.057 (15) Å ] and the mean plane makes a dihedral angle of 70.9 (6) with the benzene ring. The main feature of the crystal structure is the intermolecular N-HÁ Á ÁO hydrogen bond, which links molecules into zigzag chains along the a axis. These chains are further stacked along the b axis. The crystal structure features non-classical intermolecular C-HÁ Á ÁO interactions. The crystal studied was a nonmerohedral twin, with a twin ratio of 0.505 (1):0.495 (1).

Comment
In organic chemistry, a semicarbazone is a derivative of an aldehyde or ketone formed by a condensation between a ketone or aldehyde and semicarbazide. Semicarbazones find immerse applications in the field of synthetic chemistry, such as in medicinal chemistry (Warren et al., 1977), organometalics (Chandra & Gupta, 2005), polymers (Jain et al., 2002) and herbicides (Pilgram, 1978). 4-Sulphamoylphenyl semicarbazones were synthesized and were found to posses anticonvulsant activity (Yogeeswari et al., 2004). We hereby report the crystal structure of the semicarbazone of commercial importance keeping in view of their synthetic importance.
The bond lengths (Allen et al., 1987) and angles in the molecule ( Fig. 1) are within normal ranges and are comparable to a closely related structure (Fun et al., 2009). Atoms C7, C8, N1, N2, N3 and O1 lie on the same plane with a maximum deviation of 0.057 (15) Å for atom N1. This plane makes dihedral angle of 70.9 (6)° with the C1-C6 benzene ring.
In the crystal packing (Fig. 2), N3-H3A···O1 hydrogen bonds link the molecules into one-dimensional zig-zag extended chains along the a axis. These chains are further stacked along the b axis and thus forming two-dimensional extended networks parallel to the ab plane. The crystal structure is further stabilized by intermolecular C9-H9A···O1 interactions.
Experimental 0.57 g (5.11 mmol) of semicarbazide hydrochloride and 0.54 g (6.60 mmol) of crystallized sodium acetate was dissolved in 10 ml of water (Furniss et al., 1978). The reaction mixture was stirred at room temperature for 10 minutes. 1 g (5.02 mmol) 4-Bromoacetophenone was added to this and shaken well. A little alcohol was added to dissolve the turbidity. It was shaken for 10 more minutes and allowed to stand. The semicarbazone crystallizes on standing for 6 h. The separated crystals were filtered, washed with cold water and recrystallized from alcohol. Yield was found to be 1.158 g, 90.05 %. M.p. 479-481 K.

Refinement
The H-atoms bound to N2 and N3 was located from the difference Fourier map and refined freely. The rest of the hydrogen atoms were placed in calculated positions, with C-H = 0.93 Å, U iso = 1.2U eq (C) for aromatic, and C-H = 0.96 Å, U iso = 1.5U eq (C) for CH 3 atom. A rotating group model was used for the methyl group. The N1-N2 bond was restrained with a N-N bond distance of 1.37 (1) Å. The crystal studied was a twin with the refined BASF parameter of 0.495 (1).
The final difference Fourier map had a peak/hole in the vicnity of Br1.
supplementary materials sup-2 Figures   Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom-numbering scheme.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (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.