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

The dihedral angle between the two aromatic rings of the title compound is 64.12 (14)°. The crystal structure is stabilized by a short Cl⋯H contact, C—Cl⋯π and van der Waals interactions.


Supramolecular features and Hirshfeld surface analysis
In the crystal, the molecules are connected by a short Cl2Á Á ÁH13A contact (2.96 Å ) and C-ClÁ Á Á interactions, which contribute to the overall packing energy stabilization, into infinite columns along the a-axis direction (Table 1; Fig. 2).
In order to visualize the intermolecular interactions in the crystal of the title compound, a Hirshfeld surface analysis (Hirshfeld, 1977;Spackman & Jayatilaka, 2009) was carried out using CrystalExplorer17.5 (Turner et al., 2017). Threedimensional molecular Hirshfeld surfaces 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. 3 The molecular structure of the title compound, showing the atom labelling and displacement ellipsoids drawn at the 30% probability level. Table 1 C-ClÁ Á Á interaction geometry (Å , ).
Cg1 is the centroid of the C1-C6 ring.

Figure 2
A partial packing diagram of the title compound showing chain formation along the a-axis direction. Symmetry operators: (a) À1 + x, y, z; (b) 1 + x, y, z. Cg1 is the centroid of the C1-C6 ring.

Figure 3
Front and back sides of the three-dimensional Hirshfeld surface of the title compound plotted over d norm in the range 0.0350 to 0.8404 a.u.
The bright-red spots near atoms Cl2 and C13 in Fig.3a refer to the short Cl2Á Á ÁH13A contact, and near the atoms F1 and C10 in Fig. 3b to the F1Á Á ÁH10A contact. The shape-index of the Hirshfeld surface is a tool to visualize thestacking by the presence of adjacent red and blue triangles; if there are no adjacent red and/or blue triangles, then there are nointeractions. Fig. 4 clearly suggests that there are nointeractions in the crystal structure.
The overall two-dimensional fingerprint plot, Fig. 5a, and those delineated into HÁ Á ÁH, ClÁ Á ÁH/HÁ Á ÁCl, CÁ Á ÁH/HÁ Á ÁC, FÁ Á ÁH/HÁ Á ÁF, NÁ Á ÁH/HÁ Á ÁN, CÁ Á ÁC and ClÁ Á ÁC/CÁ Á ÁCl contacts (McKinnon et al., 2007) are illustrated in Fig. 5b-h, together with their relative contributions to the Hirshfeld surface while details of the various contacts are given in Table 2. The most important interaction is HÁ Á ÁH, contributing 33.3% to the overall crystal packing, which is reflected in Fig. 5b as widely scattered points of high density due to the large hydrogen content of the molecule with the tip at d e = d i = 1.10 Å . The reciprocal ClÁ Á ÁH/HÁ Á ÁCl interactions appear as two symmetrical broad wings with d e + d i ' 2.80 Å and contribute 22.9% to the Hirshfeld surface (Fig. 5c). The pair of characteristic wings in the fingerprint plot delineated into HÁ Á ÁC/ CÁ Á ÁH contacts ( Fig. 5d; 15.5% contribution to the Hirshfeld surface), have the tips at d e + d i ' 2.95 Å . The fingerprint plot for FÁ Á ÁH/HÁ Á ÁF contacts (9.0% contribution), Fig. 5e, has a pair of spikes with the tips at d e + d i = 2.55 Å . The remaining contributions from the other different interatomic contacts to the Hirshfeld surfaces are listed in Table 3 Hirshfeld surface of the title compound plotted over shape-index. Table 2 Summary of short interatomic contacts (Å ) in the title compound.  (Hathwar et al., 2015). 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) and C-HÁ Á ÁCl and C-ClÁ Á Á interactions into sheets parallel to the ab plane. Additional van der Waals interactions consolidate the three-dimensional packing. In the crystal of HODQAV, molecules are stacked in columns along the a axis 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 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. 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.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 4. All C-bound H atoms were refined using a riding model with d(C-H) = 0.93 Å , U iso (H) = 1.2U eq (C) for aromatic and 0.96 Å , U iso (H) = 1.5U eq (C) for methyl H atoms.

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.