2-[(E)-2-(3,4-Dichlorobenzylidene)hydrazin-1-yl]quinoxaline

The 21 non-H atoms of the title compound, C15H10Cl2N4, are almost planar (r.m.s. deviation = 0.032 Å); the conformation about the N=C bond [1.277 (6) Å] is E. In the crystal, zigzag supramolecular chains along the c axis (glide symmetry) are formed via N—H⋯N hydrogen bonds. These associate along the b axis by π–π interactions between the fused and terminal benzene rings [intercentroid distance = 3.602 (3) Å] so that layers form in the bc plane.

The 21 non-H atoms of the title compound, C 15 H 10 Cl 2 N 4 , are almost planar (r.m.s. deviation = 0.032 Å ); the conformation about the N C bond [1.277 (6) Å ] is E. In the crystal, zigzag supramolecular chains along the c axis (glide symmetry) are formed via N-HÁ Á ÁN hydrogen bonds. These associate along the b axis byinteractions between the fused and terminal benzene rings [intercentroid distance = 3.602 (3) Å ] so that layers form in the bc plane.
The use of the EPSRC X-ray crystallographic service (Coles & Gale, 2012) at the University of Southampton, England, and the valuable assistance of the staff there is gratefully acknowledged. JLW acknowledges support from CAPES (Brazil). Structural studies are supported by the Ministry of Higher Education (Malaysia) and the University of Malaya through the High-Impact Research scheme (UM.C/HIR/ MOHE/SC/3).
Supporting information for this paper is available from the IUCr electronic archives (Reference: HG5372).

Refinement
Intensity data was collected at the National Crystallographic Service, England (Coles & Gale, 2012). The C-bound H atoms were geometrically placed (C-H = 0.95 Å) and refined as riding with U iso (H) = 1.2U eq (C). The N-bound H atom was located from a difference map and refined with U iso (H) = 1.2U eq (N).
In the crystal packing, zigzag supramoelcular chains (glide symmetry) are formed via N-H···N hydrogen bonds, Fig. 2 and Table 1     A view in projection down the b axis of the unit-cell contents for (I). The N-H···H and π-π interactions are shown as orange and purple dashed lines, respectively.  Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 > 2σ(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