In the title compound, C₁₉H₁₈BrFN₂O, the pyrrolidine ring adopts an envelope conformation. In the crystal, molecules are linked by intermolecular N—H...O, C—H...O, C—H...F and C—H...Br hydrogen bonds, forming a three-dimensional network. In addition, C—H...π interactions connect molecules into ribbons along the b-axis direction, consolidating the molecular packing. The intermolecular interactions in the crystal structure were quantified and analysed using Hirshfeld surface analysis.

The asymmetric unit of the title compound, 2C₃₁H₂₈N₂O₄S·C₂H₆O, contains a parent molecule and a half molecule of ethanol solvent. The main compound stabilizes its molecular conformation by forming a ring with an R ₁ ²(7) motif with the ethanol solvent molecule. In the crystal, molecules are connected by C—H...O and O—H...O hydrogen bonds, forming a three-dimensional network. In addition, C—H...π interactions also strengthen the molecular packing.

The asymmetric unit of the title salt, C₆H₄FN₂Se⁺·Cl⁻, contains one planar 4-fluorobenzo[c][1,2,5]selenadiazol-1-ium molecular cation and a chloride anion. In the crystal, intermolecular N—H...Cl hydrogen bonds link the 4-fluorobenzo[c][1,2,5]selenadiazol-1-ium molecules, which are arranged in parallel layers along (104), to the chloride anions. The cationic layers, in turn, are stacked along [001]. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H...Cl/Cl...H (22.6%), H...F/F...H (13.9%), H...N/N...H (11.9%), H...C/C...H (10.2%) and H...H (7.7%) interactions. The volume of the crystal voids and the percentage of free space were calculated to be 44.80 ų and 5.91%, showing that there is no large cavity in the crystal packing.

In the title compound, C₁₅H₁₃NO₃S, the molecular conformation is stable with the intramolecular O—H...O hydrogen bond forming a S(7) ring motif. In the crystal, molecules are connected by C—H...O hydrogen bonds, forming C(8) chains running along the a-axis direction. Cohesion of the packing is provided by weak van der Waals interactions between the chains. A Hirshfeld surface analysis was undertaken to investigate and quantify the intermolecular interactions. The thiophene ring is disordered in a 0.9466 (17):0.0534 (17) ratio over two positions rotated by 180°.

In the title compound, C₁₆H₁₇BF₂N₂OSi, the molecular conformation is consolidated by an intramolecular C—H...O hydrogen bond, forming an S(6) motif. In the crystal, pairs of molecules are connected by C—H...π and π–π interactions [centroid-to-centroid distance = 3.6155 (8) Å] between the furan rings. These dimers are linked by π–π interactions [centroid-to-centroid distance = 3.4041 (9) Å] between similar five-membered rings of the twelve-membered ring system, forming ribbons along the a-axis direction. As a result, the van der Waals interactions between the ribbons provide crystal cohesion. Hirshfeld surface analysis indicates that H...H (48.6%), F...H/H...F (19.8%) and C...H/H...C (19.0%) interactions make the most significant contributions to the crystal packing.

In the title compound, C₂₄H₂₁NO₃S, the cyclopentene ring adopts an envelope conformation. In the crystal, molecules are linked by C—H...π interactions, forming ribbons along the a axis. Intermolecular C—H...O hydrogen bonds connect these ribbons to each other, forming layers parallel to the (0\overline{1}1) plane. The molecular packing is strengthened by van der Waals interactions between the layers. The intermolecular contacts were quantified using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H...H 46.0%, C...H/H...C 21.1%, O...H/H...O 20.6% and S...H/H...S 9.0%.