Crystal structure and Hirshfeld surface analysis of a new benzodiazepine derivative: 4-dichloromethyl-2,3-dihydro-1H-1,5-benzodiazepin-2-one

In the title compound, the seven-membered diazepine ring adopts a boat-shaped conformation. In the crystal, molecules are linked by pairs of N—H⋯O hydrogen bonds, forming inversion dimers with an (8) ring motif.


Supramolecular features
In the crystal, molecules are linked by pairs of N-HÁ Á ÁO hydrogen bonds, forming inversion dimers with an R 2 2 (8) ring motif (Table 1 and Fig. 2). The dimers are linked by C-HÁ Á Á interactions, forming layers that lie parallel to the (101) plane ( Fig. 3 and Table 1). There are no other significant intermolecular interactions present. The HÁ Á ÁH or HÁ Á ÁCl intermolecular distances all exceed the sum of their van der Waals radii.  Table 1 Hydrogen-bond geometry (Å , ).

Figure 3
A view normal to (101) of the crystal packing of the title compound. The N-HÁ Á ÁO hydrogen bonds are shown as dashed lines and the C-HÁ Á Á interactions as blue arrows (see Table 1; H atoms not involved in these interactions have been omitted).

Figure 1
The molecular structure of the title compound, with the atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
A partial view along the b-axis of the crystal packing of the title compound. The N-HÁ Á ÁO hydrogen bonds are shown as blue dashed lines and the C-HÁ Á Á(ring) interactions as purple dashed lines (see Table 1; H atoms not involved in these interactions have been omitted).
the title compound. Hence, the various geometrical parameters mentioned above for the title compound are typical for 2,3-dihydro-1H-1,5-benzodiazepin-2-ones. In the crystals of all but one compound, molecules are linked by pairs of N-HÁ Á ÁO hydrogen bonds, forming inversion dimers with an R 2 2 (8) ring motif. The same arrangement is observed in the crystal of the title compound.

Hirshfeld surface analysis
The molecular Hirshfeld surfaces were generated using a standard (high) surface resolution with the three-dimensional d norm surfaces mapped over a fixed colour scale of À0.456 (red) to 1.092 (blue) Å using the CrystalExplorer program (Turner et al., 2017). The red spots on the surface indicate the intermolecular contacts involved in the hydrogen bonds. In Figs. 4 and 5, the red spots are attributed to the HÁ Á ÁO close contacts. Hirshfeld surface mapped over d norm to visualize the intermolecular interactions.

Figure 6
The overall fingerprint plot for the title compound.

Figure 4
The Hirshfeld surfaces of the title compound mapped over d norm , d i and d e .
represents the OÁ Á ÁH/HÁ Á ÁO contacts (30.4%) between the oxygen atoms inside the surface and the hydrogen atoms outside the surface at d e + d i = 2.5 Å and two symmetrical points at the top, bottom left and right. These data are characteristic of C-HÁ Á ÁO hydrogen bonding.
The HÁ Á ÁH graph in Fig. 7 shows the two-dimensional fingerprint of the (d i , d e ) points associated with hydrogen atoms. It is characterized by an end point that points to the origin and corresponds to d i = d e = 1.08 Å , which indicates the presence of the HÁ Á ÁH contacts in this study, which make a contribution of 54.3% to the crystal packing. The CÁ Á ÁH/ HÁ Á ÁC graph in Fig. 7 shows the contacts between carbon atoms inside the Hirshfeld surface and hydrogen atoms outside and vice versa and has two symmetrical wings on the left and right sides (6.8%). Much weaker CÁ Á ÁC (5.5%), OÁ Á ÁN/NÁ Á ÁO (2.4%), OÁ Á ÁO (0.3%) and SÁ Á ÁH/HÁ Á ÁS (0.2%) contacts also occur.
A view of the three-dimensional Hirshfeld surface of the title compound plotted over electrostatic potential energy in the range À0.082 to 0.042 a.u. using the STO-3G basis set at the Hartree-Fock level of theory is shown in Fig. 8 where the N-HÁ Á ÁO and C-HÁ Á Á hydrogen-bond 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.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. All H atoms were located in a difference-Fourier map and freely refined.

Figure 8
A view of the three-dimensional Hirshfeld surface plotted over electrostatic potential energy

4-Dichloromethyl-2,3-dihydro-1H-1,5-benzodiazepin-2-one
Crystal data Extinction correction: SHELXL2018 (Sheldrick, 2015b), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.0137 (7) 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. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.