N′-(4-Bromophenylsulfonyl)isonicotinohydrazide

The title compound, C12H10BrN3O3S, crystallizes with two crystallographically independent molecules in the asymmetric unit. The dihedral angles between the two six-membered rings in the molecules are 34.1 (3) and 45.1 (2)°. In the crystal structure, molecules are connected via N—H⋯O and N—H⋯N hydrogen bonding.

The title compound crystallizes with two crystallographically independent molecules in the asymmetric unit. The dihedral angle in each of these molecules amount to 34.1 (3) ° in molecule A, while it is 45.1 (2) ° ( Fig. 1).
In the crystal structure the molecules are connected via intermolecular and intramolecular N-H···O and N-H···N hydrogen bonding ( Fig. 2 and Tab. 1). One of the two indpenendent molecules is connected into dimers via N-H···O hydrogen bonding of the sulfonamide group into R 2 2 (8) rings (Bernstein et al., 1995). These dimers are further linked by additional N-H···O and N-H···N hydrogen bonding.

Experimental
To the solution of Isoniazid (0.5 g, 3.646 mmol) in distilled water (10 ml), 4-Bromobenzenesulfonyl chloride(0.9316 g, 3.65 mmol) was suspended. The reaction mixture was stirred at room temperature for 4 hrs at constant pH 8-9, which was adjusted by 1M sodium carbonate solution. After completion of the reaction which was observed by the consumption of suspended 4-Bromobenzenesulfonyl chloride, the pH was adjusted at 2-3 using 1 N HCl solution, which results the formation of a light yellow coloured precipitate, which was filtered off and dried. The prodcut was recrystallized from methanol.

Refinement
The C-H H-atoms were positioned with idealized geometry with C-H = 0.93 Å and were refined using a riding model with U iso (H) = 1.2 U eq (C). The N-H H atoms were located in difference map and refined isotropic ( U iso (H) = 1.2 U eq (N) with varying coordinates.
supplementary materials sup-2 Figures Fig. 1. The structure of (I) with labeling and displacement ellipsoids drawn at the 50% probability level.

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.
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.