Crystal structure and Hirshfeld surface analysis of 4-(2,6-dichlorobenzyl)-6-[(E)-2-phenylethenyl]pyridazin-3(2H)-one

In the title pyridazinone derivative, the chlorophenyl and pyridazinone rings being almost perpendicular, while the phenyl ring of the styryl group is coplanar with the pyridazinone ring. In the crystal, N—H⋯O hydrogen bonds form inversion dimers with an (8) ring motif and C—H⋯Cl hydrogen bonds also occur.


Figure 2
View of the crystal structure of the title compound. N-HÁ Á ÁO hydrogen bonds are represented by red dashed lines and C-HÁ Á ÁN and C-HÁ Á ÁO interactions are shown as blue dashed lines.

Figure 1
The molecular structure of the title compound, with the atom labelling. Displacement ellipsoids are drawn at the 50% probability level.    The phenyl ring and the pyridazine ring are twisted with respect to each other, making a dihedral angle of 21.76 (18) and the phenyl ring (C1-C6) of the benzyl group is inclined to the pyridazine ring by 79.61 (19) . Relevant bond lengths in (II) are C17 O1 = 1.229 (5), C17-N2 = 1.388 (5) Å and C10-N1 =1.299 (4) Å . The N1-N2 bond lengths in (I) and (II) are virtually the same, with values of 1.348 (2) and 1.353 (4) Å , respectively. In the structure of YOTVIN, N-HÁ Á ÁO bonds are also observed.

Hirshfeld surface analysis
A Hirshfeld surface (HS) study of the title compound was undertaken using CrystalExplorer17.5 (Turner et al., 2017) to visualize and study the intermolecular contacts. The d norm surface of the title compound is illustrated in Fig. 4a. The shape-index, a tool for visualizingstacking interactions by the presence of adjacent red and blue triangles is given in Fig. 4b while Fig. 4c shows the curvedness map of the title compound. The absence of prominent red and blue triangles in the shape-index map, as well as the absence of large green regions in the curvedness map, confirms thatand C-HÁ Á Á interactions are weak. Fig. 5 shows fingerprint plots that quantitatively summarize the nature and type of intermolecular contacts. The highest contribution to the Hirshfeld surface is from HÁ Á ÁH contacts (Fig. 5b). Other interactions and their respective contributions are CÁ Á ÁH/HÁ Á ÁC (18.7%), ClÁ Á ÁH/HÁ Á ÁCl (16.4%), ClÁ Á ÁC/CÁ Á ÁCl (6.7%), OÁ Á ÁH/HÁ Á ÁO (6.5%), NÁ Á ÁH/HÁ Á ÁN (4.8%), CÁ Á ÁO/OÁ Á ÁC (3.3%) and CÁ Á ÁN/NÁ Á ÁC (2.5%). The acceptor and donor atoms participating in the hydrogen bond appear as blue (donors) and red regions (acceptors) corresponding to positive and negative potential, respectively, in the HS mapped over the electrostatic potential, in the range À0.099-0.165 a.u., as shown in Fig. 6.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. C-bound H atoms were positioned geometrically with C-H distances of 0.93-0.97 Å and refined as riding, with U iso (H) = 1.2U eq (C). The N-bound H atom was located in a difference-Fourier map and refined with N-H = 0.86 Å .

Figure 6
A view of the three-dimensional Hirshfeld surface of the title compound plotted over electrostatic potential.