Crystal structure determination, Hirshfeld surface analysis and energy frameworks of 6-phenylsulfonyl-6H-thieno[3,2-c]carbazole

Intramolecular C—H⋯O hydrogen bonds involving the sulfone O atoms and the carbazole moiety result in two S(6) rings. In the crystal, molecules are linked via pairs of C—H⋯O hydrogen bonds forming inversion dimers with an (12) graph-set motif.


Structural commentary
The molecular structure of the title compound is illustrated in Fig.1. The title compound comprises a carbazole ring system, which is attached to a phenyl sulfonyl ring and a thiopene ring. The carbazole ring system forms a dihedral angle of 89.08 (1) with the sulfonyl-substituted phenyl ring. The tetrahedral configuration is distorted around the atom S2. The increase in the O2-S2-O1 angle [120.14 (9) ], with a simultaneous ISSN 2056-9890 decrease in the N1-S2-C15 angle [104.96 (9) ] from the ideal tetrahedral value (109.5 ) are attributed to the Thorpe-Ingold effect (Bassindale, 1984). The N1-C6 [1.428 (2) Å ] and N1-C7 [1.429 (2) Å ] bond lengths in the molecule are longer than the mean Nsp 2 -Csp 2 bond length value of 1.355 (14) Å (Allen et al., 1987;Groom et al., 2016). The elongation observed may be due to the electron-withdrawing character of the phenylsulfonyl group. The molecular struc-ture is stabilized by C1-H1Á Á ÁO2 and C9-H9Á Á ÁO1 intramolecular interactions involving the sulfone oxygen atoms, which generate two S(6) ring motifs (Fig. 1).

Supramolecular features
In the crystal packing ( Fig. 2), the molecules are linked via pairs of C-HÁ Á ÁO hydrogen bonds (Table 1), forming inversion dimers with an R 2 2 (12) graph-set motif. Each molecule is involved in the formation of two dimers that propagate as a ribbon in the c-axis direction.

Hirshfeld surface analysis, interaction energies and energy frameworks
In order to investigate the weak intermolecular interactions in the crystal, the Hirshfeld surfaces (d norm , curvedness and shape index) and 2D fingerprint plots were generated using CrystalExplorer 17.5 (Turner et al., 2017). The d norm mapping uses the normalized functions of d i and d e (Fig. 3a), with white, red and blue coloured surfaces where d i (x axis) and d e (y axis) are the closest internal and external distances from a given point on the Hirshfeld surface to the nearest atom. The white surface indicates those contacts with distances equal to the sum of van der Waals (vdW) radii, red indicates shorter The molecular structure of the title compound with the atom labelling. Displacement ellipsoids are drawn at the 50% probability level. Dashed lines indicate the intramolecular C-HÁ Á ÁO hydrogen bonds, which generate S(6) ring motifs.

Figure 2
The crystal packing of the title compound, viewed along the a axis. Dashed lines indicate intermolecular hydrogen bonds. For clarity, only the H atoms involved in these interactions have been included. Table 1 Hydrogen-bond geometry (Å , ).

Figure 3
Hirshfeld surfaces for visualizing the intermolecular contacts of the title compound: (a) d norm highlighting the regions of C-HÁ Á ÁO hydrogen bonds, (b) electrostatic potential, (c) shape index, (d) curvedness and (e) fragment patches.
contacts (< vdW radii) and blue longer contacts (> vdW radii). The electrostatic potential was also mapped on the Hirshfeld surface using a STO-3G basis set and the Hartee-Fock level of theory (Spackman et al., 2008;Jayatilaka et al., 2005). The C-HÁ Á ÁO hydrogen-bond donors and acceptors are shown as blue and red regions around the atoms corresponding to positive and negative electrostatic potentials, respectively (Fig. 3b). The presence ofstacking interactions is indicated by red and blue triangles on the shape-index surface (Fig. 3c). Areas on the Hirshfeld surface with high curvedness tend to divide the surface into contact patches with each neighbouring molecule. The coordination number in the crystal is defined by the curvedness of the Hirshfeld surface (Fig. 3d). The nearest neighbour coordination environment of a molecule is identified from the colour patches on the Hirshfeld surface depending on their closeness to adjacent molecules (Fig. 3e). Two-dimensional fingerprint plots showing the occurrence of all intermolecular contacts (McKinnon et al., 2007) are presented in Fig. 4a. The fingerprint plot of HÁ Á ÁH contacts, which represent the largest contribution to the Hirshfeld surfaces (40%), shows a distinct pattern with a minimum value of d e = d i ' 1.2 Å (Fig. 4b). The CÁ Á ÁH/HÁ Á ÁC interactions appear as the next largest region of the fingerprint plot, highly concentrated at the edges, having almost the same d e + d i ' 2.7 Å ( (Fig. 4f). These are the weak interactions that contribute the most to the packing of the title compound.
The interaction energy between the molecules is expressed in terms of four components: electrostatic, polarization, dispersion and exchange repulsion. These energies were obtained using monomer wavefunctions calculated at the B3LYP/6-31G(d,p) level. The total interaction energy, which is the sum of scaled components, was calculated for a 3.8 Å radius cluster of molecules around the selected molecule (Fig. 5a) Table 3 Interaction energies (kJ mol À1 ) between a reference molecule and its neighbours.
N is the number of equivalent neighbours, R is the distance between molecular centroids (mean atomic position) in Å . The colours identify molecules in Fig. 5a, with the reference molecule shown in grey.  Figure 5 (a) Interactions between the selected reference molecule (highlighted in yellow) and the molecules present in a 3.8 Å cluster around it, (b) Coulomb energy framework, (c) dispersion energy framework and (d) total energy framework. marked energy model (Mackenzie et al., 2017) are given in Table 2. The interaction energies calculated by the energy model reveal that the interactions in crystal have a significant contribution from dispersion components (Table 3). Using energy frameworks, the magnitudes of the intermolecular interaction energies are represented graphically and the supramolecular architecture of the crystal structure is visualized. Energies between molecular pairs are represented as cylinders joining the centroids of pairs of molecules, with the cylinder radius proportional to the magnitude of the interaction energy. Frameworks were constructed for E elec as red cylinders, E dis as green and E tot as blue ( Fig. 5b-5d) and these cylinders represent the relative strength of molecular packing in different directions.

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.