Crystal structure and Hirshfeld surface analysis of 4-{2,2-dichloro-1-[(E)-(4-chlorophenyl)diazenyl]ethenyl}-N,N-dimethylaniline

The asymmetric unit of the title compound comprises three independent molecules of similar geometry. The crystal structure is stabilized by intermolecular C—H⋯N and C—H⋯Cl hydrogen bonds in addition to C—Cl⋯π interactions.


Chemical context
Non-covalent interactions, such as hydrogen bonds, halogenhalogen or chalcogen-chalcogen bonds, van der Waals interactions orstacking, Á Á Ácation and Á Á Áanion interactions, etc. are much weaker than covalent bonds. Nevertheless, they can control the reactivity of molecules, the crystal packing, tautomerization and other properties (Asadov et al., 2016;Mahmudov et al., 2019). For example, such kinds of weak interactions can create interesting supramolecular networks in coordination compounds, involving monomeric, oligomeric or polymeric subunits, which affects their catalytic activity (Afkhami et al., 2017;Gurbanov et al., 2018).

Supramolecular features and Hirshfeld surface analysis
In the crystal, the molecules are connected by intermolecular C-HÁ Á ÁN and C-HÁ Á ÁCl hydrogen bonds and C-ClÁ Á Á interactions, which contribute to the overall packing, forming a three-dimensional network (Table 1; Fig. 3).
Hirshfeld surface analysis was used to investigate the presence of hydrogen bonds and intermolecular interactions in the crystal structure. The Hirshfeld surfaces (Spackman & Jayatilaka, 2009) and the associated two-dimensional fingerprint plots (McKinnon et al., 2007) of the title compound were calculated using Crystal Explorer 17.5 (Turner et al., 2017). The three-dimensional molecular Hirshfeld surfaces of the three molecules Mol-N1, Mol-N1A and Mol-N1B and the overall surface were generated using a high standard surface resolution colour-mapped over the normalized contact distance. The red, white and blue regions visible on the d norm surfaces indicate contacts with distances shorter, longer and equal to the van der Waals radii (Fig. 4a). The shape-index of the Hirshfeld surface is a tool to visualizestacking interactions; Fig. 4b clearly suggest that there are nointeractions in the title compound. The red spots in Fig. 4a 1034 Atioglu et al. The molecular structures of the three molecules in the asymmetric unit of the title compound, showing the atom labelling and displacement ellipsoids drawn at the 30% probability level.

Figure 2
Overlay image of the three molecules in the asymmetric unit of the title compound. Table 1 Hydrogen-bond geometry (Å , ).

Figure 3
A partial view of the crystal packing of the title compound. Intermolecular interactions are shown as dashed lines.
correspond to the relatively strong C-HÁ Á ÁN hydrogenbonding interactions in the crystal structure; in Mol-N1A it involves the N3A atoms of the N,N-dimethylaniline group as acceptors with the aromatic H2A donor atom of the chlorobenzene ring in Mol-N1 (C2-H2AÁ Á ÁN3A). Two-dimensional fingerprint plots are presented in Fig. 5. The red points, which represent closer contacts and negative d norm values on the surface, correspond to C-HÁ Á ÁCl interactions. The reciprocal ClÁ Á ÁH/HÁ Á ÁCl interactions appear as two symmetrical broad wings with d e + d i ' 2.85 Å and contribute 33.6% to the Hirshfeld surface (Fig. 5b). Another significant reciprocal interaction (HÁ Á ÁH) with a contribution of 27.9% is present as broad symmetrical spikes at diagonal axes d e + d i ' 2.2 Å (Fig. 5c). The pair of characteristic wings in the fingerprint plot delineated into CÁ Á ÁH/HÁ Á ÁC contacts (Tables 2 and 3 Table 2 Summary of short interatomic contacts (Å ) in the title compound.

Contact
Distance Symmetry operation

Figure 4
Hirshfeld surface of the title compound (symmetry-independent molecules Mol-N1, Mol-N1A and Mol-N1B, and overall), with (a) the interaction of neighbouring molecules mapped over d norm and (b) mapped over shape-index.  In the crystal structures of HONBOE and HONBUK, the aromatic rings form dihedral angles of 60.9 (2) and 64.1 (2) , respectively. Molecules are linked through weak XÁ Á ÁCl contacts [X = Br for HONBOE, and Cl for HONBUK], C-HÁ Á ÁCl and C-ClÁ Á Á interactions into sheets parallel to (001). Additional van der Waals interactions consolidate the three-dimensional packing. In the crystal of HODQAV, molecules are stacked in columns along [100] via weak C-HÁ Á ÁCl hydrogen bonds and face-to-facestacking interactions. The crystal packing is further stabilized by short ClÁ Á ÁCl contacts. In XIZREG, molecules are linked by C-HÁ Á ÁO hydrogen bonds into zigzag chains running along [001]. The crystal packing is further stabilized by C-ClÁ Á Á, C-FÁ Á Á and N-OÁ Á Á interactions. In the crystal of LEQXIR, C-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds and ClÁ Á ÁO contacts were found, and in LEQXOX, C-HÁ Á ÁN and ClÁ Á ÁCl contacts are observed.

4-{2,2-Dichloro-1-[(E)-(4-chlorophenyl)diazenyl]ethenyl}-N,N-dimethylaniline
Crystal data 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.