Crystal structure and Hirshfeld surface analysis of two (E)-N′-(para-substituted benzylidene) 4-chlorobenzenesulfonohydrazides

The crystal structures of (E)-4-chloro-N′-(4-chlorobenzylidene)benzenesulfonohydrazide and (E)-4-chloro-N′-(4-nitrobenzylidene)benzenesulfonohydrazide have been studied to investigate the effect of substituents on the structural parameters. The two-dimensional fingerprint plots of these two p-substituted compounds indicate that in the 4-chloro-substituted compound, the largest contribution to the Hirshfeld surface comes from the H⋯H contacts (26.6%), in contrast to the 34.8% contribution of the O⋯H/H⋯O contacts in the 4-nitro-substituted compound.


Chemical context
In the field of synthetic chemistry, hydrazones are frequently used as nucleophiles and electrophiles (Ogawa et al., 2004). They also play an important role in organic synthesis as one of the reaction intermediates due to their ring-closure reactions (Rollas & Kü çü kgü zel, 2007). Hydrazones have drawn considerable attention in the field of coordination chemistry (Weber et al., 2007). They also find various industrial applications (Reis et al., 2013) and exhibit a wide spectrum of biological activities (da Silva et al., 2011). Arylsulfonylhydrazones have shown antitumour activity in addition to their role as a versatile source of diazo compounds in many metal-catalysed and metal-free reactions (Hashemi, 2012). In a continuation of our efforts to explore the effect of site and nature of substituents on the crystal structures of 4-chloroarylsulfonohydrazide derivatives (Salian et al., 2018), we report herein the synthesis, characterization, crystal structures ISSN 2056-9890 and Hirshfeld surface analysis of the title compounds, (I) and (II), and compare them with those of the recently reported structures of (E)-4-chloro-N 0 -(benzylidene) benzenesulfonohydrazide (III), (E)-4-chloro-N 0 -(2-methylbenzylidene)benzenesulfonohydrazide (IV) and (E)-4-chloro-N 0 -(4methylbenzylidene)benzenesulfonohydrazide (V) (Salian et al., 2018).

Structural commentary
Compound (I), crystallizes in the triclinic crystal system, space group P1, with one molecule in the asymmetric unit ( Fig. 1), while compound (II) crystallizes in the monoclinic crystal system, space group P2 1 /c, with two independent molecules [(IIA) and (IIB)] in the asymmetric unit (Fig. 2). For both the compounds, the configuration about the C=N bond is E and the conformations of the N-H and C-H bonds in the hydrazone segments are syn to each other.
The C N bond lengths of 1.269 (3), 1.269 (3) and 1.269 (3) Å in (I), (IIA) and (IIB), and the N-N bond lengths of 1.388 (2) 1.397 (3) and 1.390 (2) Å in (I), (IIA) and (IIB), respectively, indicate the delocalization of the -electron density over the hydrazone part of the molecules. The other bond lengths are in close agreement with those of the parent compound (III), and the ortho-methyl (IV) and para-methyl (V) derivatives (Salian et al., 2018). Selected geometrical parameters of compounds (I)-(V) are compared in Molecular structure of (II), with the atom labelling and displacement ellipsoids drawn at the 50% probability level.

Figure 1
Molecular structure of (I), with the atom labelling and displacement ellipsoids drawn at the 50% probability level. Table 1 Comparison of selected geometrical parameters (Å , ) of compounds (I)-(V).

Supramolecular features
The pattern of the hydrogen-bonding interactions in the crystal structures of (I) and (II) are different. In the crystal of (I), molecules are linked by pairs of N-HÁ Á ÁO hydrogen bonds, forming inversion dimers enclosing R 2 2 (8) loops (Fig. 3, Table 2). The dimers are linked by C-ClÁ Á Á interactions, forming a three-dimensional arrangement (Fig. 3). This is very similar to the situation observed in the crystal of compound (V) [(E)-4-chloro-N 0 -(4-methylbenzylidene)benzenesulfonohydrazide; Salian et al., 2018].
Replacement of the 4-chloro group in (I) by the 4-nitro group to produce compound (II) introduces C-HÁ Á ÁO interactions, which stabilize the crystal packing (Table 3 and Crystal packing of (I), viewed along the a axis, with hydrogen bonds (Table 2) shown as dashed lines and C-ClÁ Á Á interactions as blue arrows. C-bound H atoms have been omitted.

Figure 4
A partial view along the a axis of the crystal packing of (II), with hydrogen bonds (Table 3) shown as dashed lines. H atoms not involved in these interactions have been omitted. Colour code: black A molecules; red B molecules.

Figure 5
Crystal packing of (II), viewed along the b axis, with hydrogen bonds shown as dashed lines. H atoms not involved in these interactions have been omitted.
shows bifurcated hydrogen bonding, one with the amino H atom of the hydrazide segment and the other with one of the aromatic H atoms (H25), adjacent to the nitro group. These interactions link the chains, forming layers lying parallel to the bc plane (Table 3 and Fig. 5).

Hirshfeld surface analysis
Hirshfeld surfaces and two-dimensional fingerprint plots were generated for the two substituted compounds (I) and (II) using CrystalExplorer (Turner et al., 2017) to visualize the intermolecular interactions, to investigate the impact of each kind of intermolecular contact on the crystal packing and to study the relative strengths of the different interactions in the two compounds. The molecular Hirshfeld surfaces were generated using a standard (high) surface resolution. Two-dimensional fingerprint plots for (a) (I) and (b) (II). d i is the closest internal distance from a given point on the Hirshfeld surface and d e is the closest external contact.   Table 2 Hydrogen-bond geometry (Å , ) for (I).

D-HÁ
Cg3 is the centroid of the C14-C19 ring.

Database survey
The structures reported in the literature similar to the title (Hussain et al., 2017a) and (E)-4-methyl-N 0 -(4-nitrobenzylidene)benzenesulfonohydrazide (Hussain et al., 2017b). In all of these structures, intermolecular N-HÁ Á ÁO hydrogen bonds link neighbouring molecules to form chains, which are linked by C-HÁ Á ÁO hydrogen bonds. There are also intermolecularinteractions present, which further stabilize the crystal structures.

Synthesis of compounds (I) and (II)
A mixture of 4-chlorobenzenesulfonohydrazide (0.01 mol) and 4-chlorobenzaldehyde (0.01 mol) for (I), and 4-nitrobenzaldehyde (0.01 mol) for (II), in ethanol (30 ml) and two drops of glacial acetic acid were stirred for 4 h. The reaction mixtures were cooled to room temperature and concentrated by evaporating off the excess of solvent. The solid products obtained were washed with cold water, dried and recrystallized to constant melting points from ethanol to obtain the pure compounds. The purity of the compounds was checked by TLC.
Crystals of compounds (I) and (II), suitable for X-ray diffraction analysis, were obtained by slow evaporation of their DMF solutions at room temperature.
Both compounds were characterized by measuring their IR, 1 H and 13 C NMR spectra.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 4. C-bound H atoms were positioned with idealized geometry and refined using a riding model: C-H = 0.93 Å with U iso (H) = 1.2U eq (C). The amino H atoms were located in difference-Fourier maps and refined with an N-H distance restraint of 0.86 (2) Å and U iso (H) = 1.2U eq (N). In (I), reflection 011 was masked by the beam stop and omitted from the refinement. In (II), atom O3 is disordered and was refined using a split model. The corresponding site-occupation factors were fixed at 0.55:0.45 and the corresponding N-O bond lengths in the disordered group were restrained to be equal. The U ij components of O3 and O3 0 were restrained to be approximately isotropic.  SHELXS2013 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015).

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.

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.