Crystal-structure determination and Hirshfeld surface analysis of two new thiophene derivatives: (E)-N-{2-[2-(benzo[b]thiophen-2-yl)ethenyl]-5-fluorophenyl}benzenesulfonamide and (E)-N-{2-[2-(benzo[b]thiophen-2-yl)ethenyl]-5-fluorophenyl}-N-(but-2-yn-1-yl)benzenesulfonamide

The crystal structures of two benzothiophene derivatives are described and the intermolecular contacts in the crystals analysed using Hirshfeld surface analysis and two-dimensional fingerprint plots.

In compound (I), the molecular structure is stabilized by weak C15-H15Á Á ÁO1 intramolecular interactions formed by the sulfone oxygen atoms, which generate two S(5) ring motifs ( Fig. 1).

Supramolecular features
In the crystal of I, the C10-H10Á Á ÁO2 i hydrogen bond generates an inversion dimer with an R 2 2 (14) ring motif; within The molecular structure of compound II, with atom labelling. Displacement ellipsoids are drawn at the 30% probability level.

Figure 1
The molecular structure of compound I, with atom labelling. Displacement ellipsoids are drawn at the 30% probability level. Table 1 Hydrogen-bond geometry (Å , ) for I. the ring, N1-H1NÁ Á ÁO2 ii hydrogen bonds link the molecules into R 2 2 (8) ring motifs ( Fig. 3 and Table 1). These rings are linked by the C(10) chain formed via the C22-H22Á Á ÁF1 iii hydrogen bonds. No significant C-HÁ Á Á interactions with centroid distances of less than 4Å are observed in the structure.

Hirshfeld surface analysis
A recent article by Tiekink and collaborators (Tan et al., 2019) reviews and describes the uses and utility of Hirshfeld surface analysis (Spackman & Jayatilaka, 2009), and the associated two-dimensional fingerprint plots (McKinnon et al., 2007), to analyse intermolecular contacts in crystals. The various calculations (d norm , curvedness and shape index and 2D fingerprint plots) were performed with CrystalExplorer17 (Turner et al., 2017).
The Hirshfeld surfaces of compounds I and II mapped over d norm are given in Fig. 5, and the intermolecular contacts are illustrated in Fig. 6a for I and Fig. 7a for II. They are colourmapped with the normalized contact distance, d norm , from red (distances shorter than the sum of the van der Waals radii)  Table 2 Hydrogen-bond geometry (Å , ) for II.

Figure 4
A view along the b axis of the crystal packing of compound II. The hydrogen bonds (Table 2) are shown as dashed lines, and H atoms not involved in hydrogen bonding have been omitted.

Figure 3
A view along the a axis of the crystal packing of compound I. The hydrogen bonds (Table 1) are shown as dashed lines, and H atoms not involved in hydrogen bonding have been omitted.

Figure 5
The Hirshfeld surfaces of compounds I and II, mapped over d norm .

Figure 6
The Hirshfeld surfaces for visualizing the intermolecular contacts of compound I: (a) d norm of compound I, showing the various intermolecular contacts in the crystal, (b) shape index, (d) curvedness and (e) fragment patches.
through white to blue (distances longer than the sum of the van der Waals radii). The d norm surface was mapped over a fixed colour scale of À0.434 (red) to 1.449 (blue) for compound I and À0.119 (red) to 1.765 (blue) for compound II, where the red spots indicate the intermolecular contacts involved in the hydrogen bonding. 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 presence of interactions is indicated by a red and blue colour on the shape-index surface ( Fig. 6b for I and 7b for II). 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. 6c for I and Fig. 7c for II). 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. 6d for I and Fig. 7d for II).

Figure 8
The full two-dimensional fingerprint plot for compound I, and fingerprint

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. For compound I, the NH H atoms were located in difference-Fourier maps and freely refined. For compound II, they were included in calculated positions and refined as riding: N-H = 0.93 Å with U iso (H) = 1.2U eq (N). All C-bound H atoms were positioned geometrically and constrained to ride on their parent atoms: C-H = 0.93-0.97 Å with U iso (H) = 1.5U eq (C-methyl) and 1.2U eq (C) for other H atoms. In compound I, the thiophene ring is disordered over two positions with a refined occupancy ratio of 0.756 (4):0.244 (3). The geometries were regularized using soft restraints.

Computing details
For both structures, data collection: APEX2 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXS2018/3 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2020); software used to prepare material for publication: WinGX (Farrugia, 2012), publCIF (Westrip, 2010) and PLATON (Spek, 2020). 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.