Hirshfeld surface analysis and crystal structure of 7-methoxy-5-methyl-2-phenyl-11,12-dihydro-5,11-methano-1,2,4-triazolo[1,5-c][1,3,5]benzoxadiazocine

In the crystal, classical N—H⋯N hydrogen bonds, weak C—H⋯O hydrogen bonds and weak C—H⋯π interactions link the molecules into a three-dimensional supramolecular network.


Chemical context
One of the earliest known multi-component reactions (MCRs) is the Biginelli multi-component cyclocondensation. Its variations are still a timely subject for research because of the near unlimited scope of this approach and the constant demand for molecular diversity of small molecules in many areas such as drug discovery, combinatorial and medicinal chemistry (Kappe, 2000;Slobbe et al., 2012). As we had previously synthesized a type of oxygen-bridged Biginelli compounds derivatives, (Gü mü ş et al., 2017), we decided to examine the structure of this heterocyclic system by X-ray analysis Gü mü ş et al., 2018). In this study, a novel Biginelli-like assembly of 3-amino-5-(phenyl)-1,2,4-triazole with acetone and 2-hydroxy-3-methoxybenzaldehyde has been developed to offer easy access to 7-methoxy-5-methyl-2-(phenyl)-11, 12-dihydro-5,11-methano-[1,2,4]

Supramolecular features
In the crystal, weak C-HÁ Á ÁO interactions link the pairs of independent molecules into layers parallel to (100) ( Table 1; Fig. 2). The layers are further connected by weak C-HÁ Á Á interactions, generating a three-dimensional supramolecular structure.

Hirshfeld surface analysis
Hirshfield surface analysis was performed using Crystal-Explorer (Turner et al., 2017) to quantify the various intermolecular interactions in the synthesized complex. The Hirshfeld surfaces of the title compound mapped over d norm , d i and d e are illustrated in Fig. 3. The red spots on the surface indicate the intermolecular contacts involved in strong hydrogen bonding and interatomic contacts (Sen et al., 2018) and correspond to C-HÁ Á ÁO hydrogen bonds in the title compound ( Figs. 3 and 4). The Hirshfeld surfaces were calculated using a standard (high) surface resolution with the three-dimensional d norm surfaces mapped over a fixed colour scale of À0.249 (red) to 1.531 (blue) a.u..  Table 1 Hydrogen-bond geometry (Å , ).

Figure 2
The view of the crystal packing of C 19 H 18 N 4 O 2 . Dashed lines denote the N-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds.

Figure 3
Hirshfeld surfaces of the title compound mapped over d norm , d i and d e .

Figure 1
The molecular structure of the title compound, showing the atom labelling. Displacement ellipsoids are drawn at the 20% probability level.

Figure 4
Hirshfeld surface mapped over d norm for visualizing the intermolecular interactions of the title compound. The view of the three-dimensional Hirshfeld surface of the title compound plotted over the electrostatic potential energy in the range À0.083 to 0.046 a.u. using the STO-3G basis set at the Hartree-Fock level of theory is shown in Fig. 7. The donors and acceptors are shown as blue and red areas around the atoms related with positive (hydrogen-bond donors) and negative (hydrogen-bond acceptors) electrostatic potentials, respectively.

Figure 5
Fingerprint plot for the title compound.

Synthesis and crystallization
The synthesis (Fig. 8) of the title compound was described by Gü mü ş et al. (2017). 3-Amino-5-(phenyl)-1,2,4-triazole (1.0 mmol), 2-hydroxy-3-methoxybenzaldehyde (1.0 mmol), acetone (0.22 mL, 3.0 mmol), and abs. EtOH (2.0 mL) were mixed in a microwave process vial, after which a 4 N solution of HCl in dioxane (0.07 mL, 0.3 mmol) was added. The mixture was irradiated at 423 K for 30 min. The reaction mixture was cooled by an air flow and stirred for 24 h at room temperature for complete precipitation of the product. The precipitate was filtered off, washed with EtOH (1.0 mL) and Et 2 O (3 Â 1.0 mL), and dried. The compound was obtained in the form of a white solid with %53 yields. It was recrystallized from ethanol.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2 The synthesis of the title compound.  (Farrugia, 1999); program(s) used to refine structure: SHELXL2017 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: WinGX (Farrugia, 2012) and PLATON (Spek, 2009). 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.