Crystal structure and Hirshfeld surface analysis of 1-{[2-oxo-3-(prop-1-en-2-yl)-2,3-dihydro-1H-1,3-benzodiazol-1-yl]methyl}-3-(prop-1-en-2-yl)-2,3-dihydro-1H-1,3-benzodiazol-2-one

In the title compound, the benzodiazolone moieties are planar to within 0.017 (1) and 0.026 (1) Å, and oriented at a dihedral angle of 57.35 (3)°. In the crystal, two sets of intermolecular C—H⋯O hydrogen bonds generate layers parallel to the bc plane.


Supramolecular features
Hydrogen bonding and van der Waals contacts are the dominant interactions in the crystal packing. In the crystal, two sets of intermolecular C-HÁ Á ÁO hydrogen bonds (Table 1) generate layers parallel to the bc plane. In these layers, one of the benzodiazole units in each molecule is approximately parallel to the bc plane while the other half of the molecule protrudes from the surface (Fig. 2).

Hirshfeld surface analysis
In order to visualize the intermolecular interactions in the crystal of the title compound, a Hirshfeld surface (HS) analysis (Hirshfeld, 1977;Spackman & Jayatilaka, 2009) was carried out by using CrystalExplorer17.5 (Turner et al., 2017). In the HS plotted over d norm (Fig. 3), the white surface indicates contacts with distances equal to the sum of van der Waals radii, and the red and blue colours indicate distances shorter (in close contact) or longer (distinct contact) than the van der Waals radii (Venkatesan et al., 2016). The bright-red spots appearing near O1, O2 and hydrogen atoms H5, H10A and H10B indicate their roles as the respective donors and The title molecule with the labelling scheme and 50% probability ellipsoids. Intramolecular C-HÁ Á ÁO hydrogen bonds are shown as dashed lines.

Figure 3
View of the three-dimensional Hirshfeld surface of the title compound plotted over d norm in the range À0.1476 to 1.2686 a.u.
acceptors in the dominant C-H Á Á Á O hydrogen bonds; they also appear as blue and red regions corresponding to positive and negative potentials on the HS mapped over electrostatic potential (Spackman et al., 2008;Jayatilaka et al., 2005) as shown in Fig. 4. The blue regions indicate positive electrostatic potential (hydrogen-bond donors), while the red regions indicate negative electrostatic potential (hydrogen-bond acceptors). The shape-index of the HS is a tool to visualize the stacking by the presence of adjacent red and blue triangles; if there are no adjacent red and/or blue triangles, then there are nointeractions. Fig. 5 clearly indicates that no interactions are present in the title structure. The overall two-dimensional fingerprint plot, Fig. 6a, and those delineated into HÁ Á ÁH, HÁ Á ÁC/CÁ Á ÁH, HÁ Á ÁO/OÁ Á ÁH, HÁ Á ÁN/NÁ Á ÁH, CÁ Á ÁC and NÁ Á ÁC/CÁ Á ÁN contacts (McKinnon et al., 2007) are illustrated in Fig. 6b-g, respectively, together with their relative contributions to the Hirshfeld surface. The most important contribution to the overall crystal packing (51.8%) is from HÁ Á ÁH interactions, which are shown in Fig. 6b as widely scattered points of high density due to the large hydrogen content of the molecule. The spike with the tip at d e = d i = 1.08 Å in Fig. 6b is due to the short interatomic HÁ Á ÁH contacts ( Table 2). The fingerprint plot, Fig. 6c, delineated into HÁ Á ÁC/CÁ Á ÁH contacts, which make a 30.7% contribution to the HS, shows a pair of characteristic wings and a pair of spikes with the tips at d e + d i $2.65 Å . The HÁ Á ÁO/OÁ Á ÁH contacts in the structure with a 11.2% contribution to the HS have a symmetrical distribution of points, Fig. 6d, with the tips at d e + d i = 2.40 Å arising from the short intra-and/or interatomic C-H Á Á Á O hydrogen bonding (Table 1) as well as from the HÁ Á ÁO/OÁ Á ÁH contacts (Table 2) Hirshfeld surface of the title compound plotted over shape-index. Table 2 Selected interatomic distances (Å ).

Figure 4
View of the three-dimensional Hirshfeld surface of the title compound plotted over electrostatic potential energy in the range À0.0500 to 0.0500 a.u. using the STO-3 G basis set at the Hartree-Fock level of theory. Hydrogen-bond donors and acceptors are shown as blue and red regions, respectively, around the atoms corresponding to positive and negative potentials.
The Hirshfeld surface analysis confirms the importance of H-atom contacts in establishing the packing. The large number of HÁ Á ÁH, HÁ Á ÁC/CÁ Á ÁH and HÁ Á ÁO/OÁ Á ÁH interactions suggest that van der Waals interactions and hydrogen bonding play the major roles in the crystal packing (Hathwar et al., 2015).  Fig. 8). In XEVJOX, the N-C-N angle connecting the two bicyclic units [114.19 (12) ] is essentially the same as in the title compound [114.04 (7) ]. In both of these, the bicyclic units are in an anti arrangement and this is basically the same for ZICNEE. Interestingly, the three bicyclic units in NOTQUI are close to all being syn to one another.

Synthesis and crystallization
To a solution of 1-(prop-1-en-2-yl)-1H-benzimidazol-2(3H)one (2.87mmol) in dichloromethane (30 ml) as reagent and solvent were added potassium carbonate (5.71 mmol) and a catalytic amount of tetra-n-butylammonium bromide (0.37 mmol). The mixture was heated for 24 h. The solid material was removed by filtration and the solvent evaporated under vacuum. The solid product was purified by recrystallization from ethanol solution to afford colourless crystals in 67% yield.

Special details
Experimental. The diffraction data were obtained from 3 sets of 400 frames, each of width 0.5° in ω, colllected at φ = 0.00, 90.00 and 180.00° and 2 sets of 800 frames, each of width 0.45° in φ, collected at ω = -30.00 and 210.00°. The scan time was 15 sec/frame. 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.