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

In the title compound, the benzene rings make a dihedral angle of 62.73 (9)° with each other. In the crystal, molecules are linked by a pair of C—Cl⋯π interactions, forming an inversion dimer. A short HL⋯·HL contact links the dimers, forming a ribbon propagating along the c-axis.


Chemical context
Although non-covalent interactions are weaker than the covalent bonds, they are common and play critical roles in micellization, synthesis and catalysis as well as in forming supramolecular structures as a result of their significant contribution to the self-assembly process (Asadov et al., 2016;Maharramov et al., 2010;Mahmudov et al., 2019). Similar to well-explored hydrogen bonds and -interactions Mahmoudi et al., 2018), all aspects of chemistry and physics of halogen bonding have been subject to rapidly growing interest over the past decade. Thus, the attachment of halogen-bond donor site(s) to organic molecules can be used in the regulation of the solvatochromic, analytical, catalytic etc. properties of materials Mahmudov et al., 2016). In a continuation of our work in this area we have functionalized the title compound, a new azo dye, which provides weak intermolecular interactions of the C-ClÁ Á Á and C-ClÁ Á ÁCl types.

Supramolecular features
In the crystal, there are no classical hydrogen bonds observed. Molecules are linked by a pair of C-ClÁ Á Á interactions (Table 1), forming an inversion dimer. A short intermolecular HLÁ Á ÁHL contact [Cl2Á Á ÁCl2 (1 À x, 2 À y, 2 À z) = 3.2555 (9) Å ] links the dimers to form a ribbon along the caxis direction (Figs. 2 and 3). The molecular packing is further stabilized by van der Waals interactions between these ribbons.
Hirshfeld surfaces (McKinnon et al., 2007) and their associated two-dimensional fingerprint plots (Spackman & McKinnon, 2002) were calculated using CrystalExplorer17 (Turner et al., 2017) to visualize the intermolecular interactions in the title compound. In the Hirshfeld surface mapped over d norm (Fig. 4), a bright-red spot near atom Cl2 indicates the short ClÁ Á ÁCl contact. Other contacts are equal to or longer than the sum of van der Walls radii.

Figure 3
A packing diagram of the title compound, viewed along the a-axis direction. All hydrogen atoms were omitted for clarity.

Figure 1
The molecular structure of the title compound with displacement ellipsoids for the non-hydrogen atoms drawn at the 30% probability level.

Database survey
The title compound is similar to 4 The crystal structure of DULTAI is stabilized by C-ClÁ Á Á and van der Waals interactions. In the crystals of HONBOE and HONBUK, 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 the ab plane. In HODQAV, molecules are stacked in columns along the a axis via weak C-HÁ Á ÁCl hydrogen bonds and faceto-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 the c-axis direction. The crystal packing is further stabilized by C-ClÁ Á Á, C-FÁ Á Á and N-OÁ Á Á interactions.

Refinement details
Crystal data, data collection and structure refinement details are summarized in Table 2. The C-bound H atoms were positioned geometrically (C-H = 0.93-0.96 Å ) and refined as riding with U iso (H) = 1.5 or 1.2U eq (C).

Computing details
Data collection: APEX3 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXT2016/6 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2016/6 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: PLATON (Spek, 2020). 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.