7-Chloro-4-[(E)-2-(2,5-dimethoxybenzylidene)hydrazin-1-yl]quinoline

In the nearly planar title compound (r.m.s. deviation for the 24 non-H atoms = 0.064 Å), C18H16ClN3O2, the conformation about the N=C bond is E. Supramolecular chains propagated by glide symmetry along [001] are found in the crystal packing. These are sustained by N—H⋯N hydrogen bonds with the quinoline N atom being the acceptor. The chains are connected into a three-dimensional architecture by π–π interactions involving all three aromatic rings [centroid–centroid distances = 3.5650 (9)–3.6264 (9) Å].

In the nearly planar title compound (r.m.s. deviation for the 24 non-H atoms = 0.064 Å ), C 18 H 16 ClN 3 O 2 , the conformation about the N C bond is E. Supramolecular chains propagated by glide symmetry along [001] are found in the crystal packing. These are sustained by N-HÁ Á ÁN hydrogen bonds with the quinoline N atom being the acceptor. The chains are connected into a three-dimensional architecture byinteractions involving all three aromatic rings [centroidcentroid distances = 3.5650 (9)-3.6264 (9) Å ].
The use of the EPSRC X-ray crystallographic service at the University of Southampton, England, and the valuable assistance of the staff there is gratefully acknowledged. JLW acknowledges support from CAPES (Brazil). Support from the Ministry of Higher Education, Malaysia, High-Impact The quinoline nucleus is an important moiety found in various synthetic and natural products with a wide range of pharmacological activities (de Souza et al., 2009), including anti-tubercular (Candea et al., 2009) and anti-tumour (Montenegro et al., 2012) activities. Among the derivatives studied have been arylaldehyde 7-chloroquinoline-4hydrazones (Candea et al., 2009;Montenegro et al., 2011). Some crystal structures of the these hydrazones, including related methoxy-substituted derivatives have been reported de Lima Ferreira et al., 2010). We now wish to report the crystal structure of the title compound, (I).
In (I), Fig. 1, the entire molecule is planar with the r.m.s. deviation of all 24 non-hydrogen atoms being 0.064 Å. The maximum deviations from the least-squares plane are 0.108 (2) for the C5 atom and -0.165 (1) Å for the Cl1 atom. The The most prominent feature of the crystal packing is the formation of supramolecular chains via N-H···N hydrogen bonds with the quinolinyl-N atom being the acceptor, Table 1. The chains a propagated by glide symmetry along the c axis, Fig. 2. Molecules are consolidated into a three-dimensional architecture by π-π interactions whereby the dimethoxybenzene ring interacts with both components of the quinolinyl residue along with symmetry related dimethoxybenzene rings [centroid(dimethoxybenzene)···centroid(NC 5 ) i ; (C 6 ) i ; (dimethoxybenzene) ii = 3.5650 (9), 3.6264 (9) and 3.5872 (9) Å, with angles of inclination = 2.36 (7) 4.20 (7) and 0° for symmetry operations i: 1 -x, -y, 1 -z and ii: 2 -x,y, 1 -z]. The π-π interactions between the dimethoxybenzene and quinolinyl residues lead to zigzag layers in the bc plane and the π(dimethoxybenzene)···π(dimethoxybenzene) interactions link these layers along the a axis, Fig. 3.

Experimental
The compound was prepared from 7-chloro-4-quinolinylhydrazone with 2,5-dimethoxybenzaldehyde (Montenegro et al., 2012). The crystals used in the structure determination were grown from an ethanol solution of the compound.

Refinement
The C-bound H atoms were geometrically placed (C-H = 0.95-0.98 Å) and refined as riding with U iso (H) = 1.2-1.5U eq (C). The N-bound H-atom was located in a difference Fourier map and refined with a N-H distance = 0.88±0.01 Å, and with U iso (H) = 1.2U eq (N). Owing to poor agreement, the (1 0 2) and (2 3 0) reflections were omitted from the final cycles of refinement.

Figure 1
The molecular structure showing the atom-labelling scheme and displacement ellipsoids at the 50% probability level.

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.