Crystal structure, Hirshfeld surface analysis and interaction energy and DFT studies of 1-(1,3-benzothiazol-2-yl)-3-(2-hydroxyethyl)imidazolidin-2-one

The title molecule is only a few degrees out of planarity except for the 2-hydroxyethyl substituent. In the crystal, O—H⋯N hydrogen bonds form stepped chains along the c-axis direction, which are formed into layers parallel to the bc plane by weak C—H⋯O and C—H⋯π (ring) interactions. Completion of the overall layer structure occurs through weak C—H⋯O, C—H⋯π (ring) and head-to-tail slipped π-stacking interactions.

The title compound was obtained for the first time and characterized by single crystal X-ray diffraction techniques as well as by Hirshfeld surface analysis. The results of the calculations by density functional theory (DFT), carried out at the B3LYP/6-311G (d,p) level, are compared with the experimentally determined molecular structure in the solid state.

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

Figure 2
A portion of the O-H Hydethy Á Á ÁN Thz (Hydethy = hydroxyethyl and Thz = thiazole) (red dashed lines) hydrogen bonded chain in I viewed along the a axis.

Hirshfeld surface analysis
In order to visualize the intermolecular interactions in the crystal of I, a Hirshfeld surface (HS) analysis (Hirshfeld, 1977;Spackman & Jayatilaka, 2009) was carried out using Crystal Explorer 17.5 (Turner et al., 2017). In the HS plotted over d norm (Fig. 5), 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 (distant contact) than the van der Waals radii, respectively (Venkatesan et al., 2016). The bright-red spots appearing near O1 and hydrogen atoms H5, H2A, H8B indicate their roles as donors and/or acceptors; 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) shown in Fig. 6. The blue regions indicate positive electrostatic potential (hydrogen-bond donors), while the red regions indicate negative electrostatic potential (hydrogen-bond acceptors).  Table 1 Hydrogen-bond geometry (Å , ).

Figure 4
A partial packing diagram viewed along the b axis with intermolecular interactions depicted as in Fig. 3. Three unit cells along the a axis are shown.

Figure 3
Portions of two chains, viewed along the b axis, showing the interactions between them. O-H Hydethy Á Á ÁN Thz hydrogen bonds are shown by red dashed lines while the weak C-H Imdz Á Á ÁO Imdz and C-H Bnz Á Á ÁO Imdz (Hydethy = hydroxyethyl, Thz = thiazole, Imdz = imidazolidine and Bnz = benzene) interactions are shown by black dashed lines. The weak C-H Imdz Á Á Á(ring) and the head-to-tail slipped -stacking interactions are shown, respectively, by green and orange dashed lines.

Figure 5
View of the three-dimensional Hirshfeld surface of I plotted over d norm in the range À0.5793 to 1.2827 a.u.

Figure 6
View of the three-dimensional Hirshfeld surface of I 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 around the atoms corresponding to positive and negative potentials, respectively.

Figure 8
The

DFT calculations
The main aim of these computations is to provide an interpretation of the experimental results. For this purpose, the structural parameters of equilibrium geometry for I in the gas phase have been computed using the B3LYP functional level of theory and the 6-31G (d,p) basis set (Becke, 1993) implemented in GAUSSIAN-09 (Frisch et al., 2009). The molecule adopts a geometry very close to that obtained using DFT calculations (Table 3). The largest differences between the calculated and experimental values are observed for the S1-C6 (0.1 Å ) and S1-C7 (0.08 Å ) bond lengths and the C11-N3-C9 bond angle (1.6 ). These disparities can be linked to the fact that these calculations relate to the isolated molecule, whereas the experimental results correspond to interacting molecules in the crystal lattice where intra and intermolecular interactions with the neighboring molecules are present.  Kozísek et al., 1995). In all four, the benzothiazole moiety is more nearly planar than in I, with the dihedral angle between the constituent planes being < 1 except for VI where it is 1.3 . In I, the dihedral angle between the planes defined by C7/N1/C1/C6/S1 and C7/N2/C8/C10 is

Synthesis and crystallization
To a mixture of 2-aminobenzothiazole (2.22 mmol), bis(2chloroethyl)amine (1.11 mmol) and potassium carbonate (3.21 mmol) in DMF (25 mL) was added a catalytic amount of tetra-n-butylammonium bromide (0.37 mmol). The mixture was stirred at 353 K for 24 h. The solid material was removed by filtration and the solvent evaporated in vacuo. The solid product was purified by recrystallization from ethanol to give colourless crystals (yield: 70%).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 4. All hydrogen atoms were located in a difference-Fourier map and their coordinates and isotropic displacement parameters refined without restraints.

Funding information
The support of NSF   program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg & Putz, 2012); software used to prepare material for publication: SHELXTL (Sheldrick, 2008). 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.