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This study presents the synthesis, characterization and Hirshfeld surface analysis of 1-[6-bromo-2-(3-bromophenyl)-1,2,3,4-tetrahydroquinolin-4-yl]pyrrolidin-2-one, C19H18Br2N2O. In the title compound, the pyrrolidine ring adopts a distorted envelope configuration. In the crystal, molecules are linked by intermolecular N—H...O, C—H...O and C—H...Br hydrogen bonds, forming a three-dimensional network. In addition, pairs of molecules along the c axis are connected by C—H...π interactions. According to a Hirshfeld surface study, H...H (36.9%), Br...H/H...Br (28.2%) and C...H/H...C (24.3%) interactions are the most significant contributors to the crystal packing.

The dinuclear molecule of the title compound, [Mo2(C9H13)2(CO)6] or [Mo(tBuCp)(CO)3]2 where tBu and Cp are tert-butyl and cyclopentadienyl, is centrosymmetric and is characterized by an Mo—Mo bond length of 3.2323 (3) Å. Imposed by inversion symmetry, the tBuCp and the carbonyl ligands are in a transoid arrangement to each other. In the crystal, intermolecular C—H...O contacts lead to the formation of layers parallel to the bc plane.

The title compound, bis[dithiobis(formamidinium)] hexabromidoruthenium dibromide trihydrate, [(NH2)2CSSC(NH2)2]2[RuBr6]Br2·3H2O, crystallizes in the orthorhombic system, space group Cmcm, Z = 4. The [RuBr6]2− anionic complex has an octahedral structure. The Ru—Br distances fall in the range 2.4779 (4)–2.4890 (4) Å. The S—S and C—S distances are 2.0282 (12) and 1.783 (2) Å, respectively. The H2O molecules, Br− ions, and NH2 groups of the cation are linked by hydrogen bonds. The conformation of the cation is consolidated by intramolecular O—H...Br, O—H...O, N—H...Br and N—H...O hydrogen bonds. The [(NH2)2CSSC(NH2)2]2+ cations form a hydrogen-bonded system involving the Br − ions and the water molecules. Two Br − anions form four hydrogen bonds, each with the NH2 groups of two cations, thus linking the cations into a ring. The rings are connected by water molecules, forming N—H...O—H...Br hydrogen bonds.

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 title molecule, C18H26O4, consists of two symmetrical halves related by the inversion centre at the mid-point of the central –C—C– bond. The hexene ring adopts an envelope conformation. In the crystal, the molecules are connected into dimers by C—H...O hydrogen bonds with R22(8) ring motifs, forming zigzag ribbons along the b-axis direction. According to a Hirshfeld surface analysis, H...H (68.2%) and O...H/H...O (25.9%) interactions are the most significant contributors to the crystal packing. The contribution of some disordered solvent to the scattering was removed using the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18] in PLATON. The solvent contribution was not included in the reported molecular weight and density.

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, C6H4BrF3N4O2, the oxadiazole ring is essentially planar with a maximum deviation of 0.003 (2) Å. In the crystal, molecular pairs are connected by N—H...N hydrogen bonds, forming dimers with an R22(8) motif. The dimers are linked into layers parallel to the (10\overline{4}) plane by N—H...O hydrogen bonds. In addition, C—O...π and C—Br...π interactions connect the molecules, forming a three-dimensional network. The F atoms of the trifluoromethyl group are disordered over two sites in a 0.515 (6): 0.485 (6) ratio. The intermolecular interactions in the crystal structure were investigated and quantified using Hirshfeld surface analysis.

In the title compound, C19H17NO5S, the cyclohexene ring adopts nearly an envelope conformation. In the crystal, molecules are linked by C—H...O hydrogen bonds, forming a three-dimensional network. In addition, C—H...π interactions connect the molecules by forming layers parallel to the (010) plane. According to the Hirshfeld surface analysis, H...H (36.9%), O...H/H...O (31.0%), C...H/H...C (18.9%) and S...H/H...S (7.9%) interactions are the most significant contributors to the crystal packing.

In the title compound, C20H17BrO5S, molecules are connected by intermolecular C—H...S hydrogen bonds with R22(10) ring motifs, forming ribbons along the b-axis direction. C—H...π interactions consolidate the ribbon structure while van der Waals forces between the ribbons ensure the cohesion of the crystal structure. According to a Hirshfeld surface analysis, H...H (40.5%), O...H/H...O (27.0%), C...H/H...C (13.9%) and Br...H/H...Br (11.7%) interactions are the most significant contributors to the crystal packing. The thiophene ring and its adjacent dicarboxylate group and the three adjacent carbon atoms of the central hexene ring to which they are attached were refined as disordered over two sets of sites having occupancies of 0.8378 (15) and 0.1622 (15). The thiophene group is disordered by a rotation of 180° around one bond.

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%.

The asymmetric unit of the title compound, C25H18N6·H2O, comproses two molecules (I and II), together with a water molecule. The terminal phenyl groups attached to the methyl groups of the molecules I and II do not overlap completely, but are approximately perpendicular. In the crystal, the molecules are connected by N—H...N, C—H...N, O—H...N and N—H...O hydrogen bonds with each other directly and through water molecules, forming layers parallel to the (001) plane. C—H...π interactions between these layers ensure the cohesion of the crystal structure. A Hirshfeld surface analysis indicates that H...H (39.1% for molecule I; 40.0% for molecule II), C...H/H...C (26.6% for molecule I and 25.8% for molecule II) and N...H/H...N (24.3% for molecules I and II) interactions are the most important contributors to the crystal packing.

In the ten-membered 1,3,4,6-tetrahydro-2H-pyrido[1,2-a]pyrimidine ring system of the title compound, C17H15N5, the 1,2-dihydropyridine ring is essentially planar (r.m.s. deviation = 0.001 Å), while the 1,3-diazinane ring has a distorted twist-boat conformation. In the crystal, molecules are linked by N—H...N and C—H...N hydrogen bonds, forming a three-dimensional network. In addition, C—H...π interactions form layers parallel to the (100) plane. Thus, crystal-structure cohesion is ensured. According to a Hirshfeld surface study, H...H (40.4%), N...H/H...N (28.6%) and C...H/H...C (24.1%) interactions are the most important contributors to the crystal packing.

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 R12(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.

In the title compound, C21H15N5OS2, molecular pairs are linked by N—H...N hydrogen bonds along the c-axis direction and C—H...S and C—H...O hydrogen bonds along the b-axis direction, with R22(12) and R22(16) motifs, respectively, thus forming layers parallel to the (10\overline{4}) plane. In addition, C=S...π and C[triple-bond]N...π interactions between the layers ensure crystal cohesion. The Hirshfeld surface analysis indicates that the major contributions to the crystal packing are H...H (43.0%), C...H/H...C (16.9%), N...H/H...N (11.3%) and S...H/H...S (10.9%) interactions.

The crystal structures and Hirshfeld surface analyses of three similar compounds are reported. Methyl 4-[4-(difluoromethoxy)phenyl]-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, (C21H23F2NO4), (I), crystallizes in the monoclinic space group C2/c with Z = 8, while isopropyl 4-[4-(difluoromethoxy)phenyl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, (C23H27F2NO4), (II) and tert-butyl 4-[4-(difluoromethoxy)phenyl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, (C24H29F2NO4), (III) crystallize in the orthorhombic space group Pbca with Z = 8. In the crystal structure of (I), molecules are linked by N—H...O and C—H...O interactions, forming a tri-periodic network, while molecules of (II) and (III) are linked by N—H...O, C—H...F and C—H...π interactions, forming layers parallel to (002). The cohesion of the molecular packing is ensured by van der Waals forces between these layers. In (I), the atoms of the 4-difluoromethoxyphenyl group are disordered over two sets of sites in a 0.647 (3): 0.353 (3) ratio. In (III), the atoms of the dimethyl group attached to the cyclohexane ring, and the two carbon atoms of the cyclohexane ring are disordered over two sets of sites in a 0.646 (3):0.354 (3) ratio.

In the crystal of the title compound, C6H9ClN2O, molecular pairs form dimers with an R22(8) motif through N—H...O hydrogen bonds. These dimers are connect into ribbons parallel to the (100) plane with R44(10) motifs by N—H...O hydrogen bonds along the c-axis direction. In addition, π–π [centroid-to-centroid distance = 3.4635 (9) Å] and C—Cl...π interactions between the ribbons form layers parallel to the (100) plane. The three-dimensional consolidation of the crystal structure is also ensured by Cl...H and Cl...Cl interactions between these layers. According to a Hirshfeld surface study, H...H (43.3%), Cl...H/H...Cl (22.1%) and O...H/H...O (18.7%) interactions are the most significant contributors to the crystal packing.

In the title compound, C10H8N4O3·C3H7NO, the asymmetric unit contains two crystallographically independent molecules A and B, each of which has one DMF solvate molecule. Molecules A and B both feature intramolecular N—H...O hydrogen bonds, forming S(6) ring motifs and consolidating the molecular configuration. In the crystal, N—H...O and O—H...O hydrogen bonds connect molecules A and B, forming R22(8) ring motifs. Weak C—H...O interactions link the molecules, forming layers parallel to the (\overline{2}12) plane. The DMF solvent molecules are also connected to the main molecules (A and B) by N—H...O hydrogen bonds. π–π stacking interactions [centroid-to-centroid distance = 3.8702 (17) Å] between the layers also increase the stability of the molecular structure in the third dimension. According to the Hirshfeld surface study, O...H/H...O interactions are the most significant contributors to the crystal packing (27.5% for molecule A and 25.1% for molecule B).

The crystal structures and Hirshfeld surface analyses of three similar azo compounds are reported. Methyl 4-{2,2-dichloro-1-[(E)-phenyldiazenyl]ethenyl}benzoate, C16H12Cl2N2O2, (I), and methyl 4-{2,2-dichloro-1-[(E)-(4-methylphenyl)diazenyl]ethenyl}benzoate, C17H14Cl2N2O2, (II), crystallize in the space group P21/c with Z = 4, and methyl 4-{2,2-dichloro-1-[(E)-(3,4-dimethylphenyl)diazenyl]ethenyl}benzoate, C18H16Cl2N2O2, (III), in the space group P\overline{1} with Z = 2. In the crystal of (I), molecules are linked by C—H...N hydrogen bonds, forming chains with C(6) motifs parallel to the b axis. Short intermolecular Cl...O contacts of 2.8421 (16) Å and weak van der Waals interactions between these chains stabilize the crystal structure. In (II), molecules are linked by C—H...O hydrogen bonds and C—Cl...π interactions, forming layers parallel to (010). Weak van der Waals interactions between these layers consolidate the molecular packing. In (III), molecules are linked by C—H...π and C—Cl...π interactions forming chains parallel to [011]. Furthermore, these chains are connected by C—Cl...π interactions parallel to the a axis, forming (0\overline{1}1) layers. The stability of the molecular packing is ensured by van der Waals forces between these layers.

The title compound, C13H11NO, adopts an E configuration about the C=C double bond. The pyrrole ring is inclined to the phenyl ring at an angle of 44.94 (8)°. In the crystal, molecules are linked by N—H...O hydrogen bonds, forming ribbons parallel to (020) in zigzag C(7) chains along the a axis. These ribbons are connected via C—H...π interactions, forming a three-dimensional network. No significant π–π interactions are observed.

In the title compound, C18H22O7, two hexane rings and an oxane ring are fused together. The two hexane rings tend toward a distorted boat conformation, while the tetrahydrofuran and dihydrofuran rings adopt envelope conformations. The oxane ring is puckered. The crystal structure features C—H...O hydrogen bonds, which link the molecules into a three-dimensional network. According to a Hirshfeld surface study, H...H (60.3%) and O...H/H...O (35.3%) interactions are the most significant contributors to the crystal packing.

In the title compound, C20H18N2S, the asymmetric unit comprises two similar molecules (A and B). In molecule A, the central thiophene ring makes dihedral angles of 89.96 (12) and 57.39 (13)° with the 1H-pyrrole rings, which are bent at 83.22 (14)° relative to each other, and makes an angle of 85.98 (11)° with the phenyl ring. In molecule B, the corresponding dihedral angles are 89.49 (13), 54.64 (12)°, 83.62 (14)° and 85.67 (11)°, respectively. In the crystal, molecular pairs are bonded to each other by N—H...N interactions. N—H...π and C—H...π interactions further connect the molecules, forming a three-dimensional network. A Hirshfeld surface analysis indicates that H...H (57.1% for molecule A; 57.3% for molecule B), C...H/H...C (30.7% for molecules A and B) and S...H/H...S (6.2% for molecule A; 6.4% for molecule B) interactions are the most important contributors to the crystal packing.

The title compound, [RuCl2(C33H43N3O)], is an example of a new generation of N,N-dialkyl ruthenium catalysts with an N—Ru coordination bond as part of a six-membered chelate ring. The Ru atom has an Addison τ parameter of 0.244, which indicates a geometry intermediate between square-based pyramidal and trigonal–bipyramidal. The complex shows the usual trans arrangement of the two chlorides, with Ru—Cl bond lengths of 2.3515 (8) and 2.379 (7) Å, and a Cl—Ru—Cl angle of 158.02 (3)°. One of the chlorine atoms and the atoms of the 2-methoxy-N-methyl-N-[(2-methylphenyl)methyl]ethane-1-amine group of the title complex display disorder over two positions in a 0.889 (2): 0.111 (2) ratio.

In the title compound, C25H25NO7S, the molecular conformation is stabilized by intramolecular O—H...O and N—H...O hydrogen bonds, which form S(6) and S(8) ring motifs, respectively. The molecules are bent at the S atom with a C—SO2—NH—C torsion angle of −70.86 (11)°. In the crystal, molecules are linked by C—H...O and N—H...O hydrogen bonds, forming molecular layers parallel to the (100) plane. C—H...π interactions are observed between these layers.

In the title compound, C24H29F2NO4, which crystallizes in the orthorhombic Pca21 space group with Z = 4, the 1,4-dihydropyridine ring adopts a distorted boat conformation, while the cyclohexene ring is in a distorted half-chair conformation. In the crystal, the molecules are linked by N—H...O and C—H...O interactions, forming supramolecular chains parallel to the a axis. These chains pack with C—H...π interactions between them, forming layers parallel to the (010) plane. The cohesion of the crystal structure is ensured by van der Waals interactions between these layers. Hirshfeld surface analysis shows the major contributions to the crystal packing are from H...H (56.9%), F...H/H...F (15.7%), O...H/H...O (13.7%) and C...H/H...C (9.5%) contacts.

In the title compound, C22H19NO5S·C2D6OS, the central six-membered ring has a slightly distorted boat conformation, while the fused pyrrolidine ring adopts an envelope conformation. These conformations are stabilized by O—H...O hydrogen bonds between the main compound and solvent molecules. In addition, intramolecular C—H...O hydrogen bonds in the main molecule form two S(6) rings. Molecules are connected by pairs of intermolecular C—H...O hydrogen bonds, forming dimers with a R22(8) motif. These dimers form a three-dimensional network through O—H...O, O—H...S and C—H...O hydrogen bonds with each other directly and through solvent molecules. In addition, weak π–π stacking interactions [centroid-to-centroid distances = 3.9937 (10) and 3.9936 (10) Å, slippages of 2.034 and 1.681 Å] are observed. 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 41.7%, O...H/H...O 27.7%, C...H/H...C 17.0%, and S...H/H...S 7.5%.

In the title compound, C15H14N2O2·H2O, the 1H-pyrrole ring makes a dihedral angle of 59.95 (13)° with the phenyl ring. In the crystal, the molecules are connected by C—H...O hydrogen bonds into layers parallel to the (020) plane, while two molecules are connected to the water molecule by two N—H...O hydrogen bonds and one molecule by an O—H...O hydrogen bond. C—H...π and π–π interactions further link the molecules into chains extending in the [\overline{1}01] direction and stabilize the molecular packing. According to a Hirshfeld surface study, H...H (49.4%), C...H/H...C (23.2%) and O...H/H...O (20.0%) interactions are the most significant contributors to the crystal packing.

In the title compound, C6H8N2OS, all atoms except for the methyl H atoms are coplanar, with a maximum deviation of 0.026 (4) Å. In the crystal, pairs of molecules are linked by N—H...N hydrogen bonds, forming R22(8) ring motifs. Dimers are connected by N—H...O hydrogen bonds, forming layers parallel to the (102) plane. Consolidating the molecular packing, these layers are connected by C—H...π interactions between the center of the 1,3-thiazole ring and the H atom of the methyl group attached to it, as well as C=O...π interactions between the center of the 1,3-thiazole ring and the O atom of the carboxyl group. According to a Hirshfeld surface study, H...H (37.6%), O...H/H...O (16.8%), S...H/H...S (15.4%), N...H/H...N (13.0%) and C...H/H...C (7.6%) interactions are the most significant contributors to the crystal packing.

The overall molecular configuration of the title compound, C12H16N6OS2·C3H7NO, is stabilized in the solid state by intramolecular C—H...N, C—H...O, N—H...N and N—H...O interactions, forming S(5) ring motifs. In the crystal, molecules are linked to each other and solvent dimethylformamide molecules by N—H...S, N—H...O, C—H...O and C—H...S hydrogen bonds, forming a three dimensional network. The phenyl ring of the title compound is disordered over two sites with an occupancy ratio of 0.57 (4):0.43 (4). A Hirshfeld surface analysis was performed to quantify the contributions of the different intermolecular interactions, indicating that the most important contributions to the crystal packing are from H...H (38.7%), S...H / H...S (24.0%), C...H / H...C (18.5%) and N...H / H...N (9.8%) interactions.

In the title salt, C15H12FN2O+·Cl−·H2O, the imidazo[1,2-a]pyridin-1-ium ring system of the cation is almostly planar [maximum deviaition = −0.047 (2) Å for the ring C atom with the attached arene ring] and forms a dihedral angle of 61.81 (6)° with the plane of the fluorophenyl ring. In the crystal, water molecules form an R24(8) motif parallel to the (100) plane by bonding with the chloride ions via O—H...Cl hydrogen bonds. The cations are connected along the b axis via N—H...O hydrogen bonds involving the O atoms of water molecules, and C—H...O, C—H...Cl and π–π interactions [centroid-to-centroid distance = 3.6195 (8) Å] form layers parallel to the (100) plane. Furthermore, these layers are connected via π–π interactions [centroid-to-centroid distance = 3.8051 (9) Å] that further consolidate the crystal structure.

In the title compound, C16H13N7O2, the 3,5-dimethylphenyl and 4-nitrophenyl rings are inclined to the central 2H-1,2,3-triazole ring by 1.80 (7) and 1.79 (7)°, respectively, and to one another by 2.16 (7)°. In the crystal, the molecules are linked by C—H...N hydrogen bonds and π–π stacking interactions [centroid-to-centroid distances = 3.7295 (9) and 3.7971 (9) Å], forming ribbons along the b-axis direction. These ribbons are connected to each other by weak van der Waals interactions and the stability of the crystal structure is ensured. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H...H (31.5%), N...H/H...N (19.2%), O...H/H...O (14.5%), N...C/C...C (10.9%) and C...H/H...C (10.2%) contacts.

In the title compound, C16H13BrO, the planes of the aromatic rings are inclined at an angle of 23.49 (15)°, and the configuration about the C=C bond is E. In the crystal, the molecules are linked into chains by weak C—H...O interactions along the b axis. Successive chains form a zigzag structure along the c axis, and these chains are connected to each other by face-to-face π–π stacking interactions along the a axis. These layers, parallel to the (001) plane, are linked by van der Waals interactions, thus consolidating the crystal structure. Hirshfeld surface analysis showed that the most significant contacts in the structure are H...H (43.1%), C...H/H...C (17.4%), Br...H/H...Br (14.9%), C...C (11.9%) and O...H/H...O (9.8%).

The title compound, C11H3I3N4O4·C2H6O, crystallizes in the triclinic P\overline{1} space group with one independent molecule and one ethanol solvent molecule in the asymmetric unit. The benzene ring and the methylcarbonohydrazonoyl dicyanide group of the main molecule makes a dihedral angle of 57.91 (16)°. In the crystal, O—H...O and N—H...O hydrogen bonds link pairs of molecules, forming dimers with R22(14) motifs. These dimers are connected by O—H...O hydrogen bonds into chains along the a-axis direction, forming R22(16) ring motifs. Further O—H...O interactions involving the ethanol solvent molecule connect the chains into a three-dimensional network. In addition, C—I...π interactions are observed. The intermolecular interactions in the crystal structure were quantified and analysed using Hirshfeld surface analysis.

In the hydrated title salt, C7H12N5S2+·Cl−·H2O, the asymmetric unit comprises one 2-amino-5-{(1E)-1-[(carbamothioylamino)imino]ethyl}-4-methyl-1,3-thiazol-3-ium cation, one chloride anion and one water molecule of crystallization. The cation is nearly flat (r.m.s. deviation of non-H atoms is 0.0814 Å), with the largest deviation of 0.1484 (14) Å observed for one of the methyl C atoms. In the crystal, the cations are linked by O—H...Cl, N—H...Cl, N—H...O, N—H...S and C—H...S hydrogen bonds, forming a tri-periodic network. The most important contributions to the crystal packing are from H...H (35.4%), S...H/H...S (24.4%), N...H/H...N (8.7%), Cl...H/H...Cl (8.2%) and C...H/H...C (7.7%) interactions.

In the title compounds, N,N-dimethylacetamide–1-(dimethyl-λ4-azanylidene)ethan-1-ol tribromide (1/1), C4H9NO·C4H10NO+·Br3− or [(C4H9NO)·(C4H10NO)](Br3), (I), N,N-dimethylacetamide–1-(dimethyl-λ4-azanylidene)ethan-1-ol dibromidoiodate (1/1), C4H9NO·C4H10NO+·Br2I− or [(C4H9NO)·(C4H10NO)](Br2I), (II), and N,N-dimethylacetamide–1-(dimethyl-λ4-azanylidene)ethan-1-ol dichloridoiodate (1/1), C4H9NO·C4H10NO+·Cl2I− or [(C4H9NO)·(C4H10NO)]·(Cl2I), (III), all the anions are almost linear in geometry and all the cations, except for the methyl H atoms, are essentially planar. In the crystal structure of (I), the cations are linked by pairs of C—H...O hydrogen bonds, forming inversion dimers with an R22(8) ring motif. These dimers also exhibit O—H...O hydrogen bonding. Dimerized cation pairs and anions are arranged in columns along the a axis. In the crystal of (II), the cations are linked by pairs of O—H...O and C—H...O hydrogen bonds, forming an R44(14) ring motif. These groups of cations and the anions form individual columns along the a axis and jointly reside in planes roughly parallel to (011). In the crystal of (III), cations and anions also form columns parallel to the a axis, resulting in layers parallel to the (020) plane. Furthermore, the crystal structures of (I), (II) and (III) are consolidated by strong halogen (Br and/or I and/or Cl)...H and weak van der Waals interactions. In addition to the structural evaluation, a Hirshfeld surface analysis was carried out.

The title compound, C15H14O2, adopts an E configuration about the C=C double bond. The furan ring is inclined to the phenyl ring by 12.03 (9)°. In the crystal, pairs of molecules are linked by C—H...O hydrogen bonds, forming dimers with R22(14) ring motifs. The molecules are connected via C—H...π interactions, forming a three dimensional network. No π–π interactions are observed.

In the title compound, C25H17N3O5S2, intramolecular π–π interactions [centroid-to-centroid distance = 3.5640 (9) Å] are observed between the furan and benzene rings of the 4-cyanophenyl group. In the crystal, molecules are connected via C—H...O and C—H...N hydrogen bonds, forming layers parallel to the (100) plane. These layers are interconnected by C—H...π interactions and weak van der Waals interactions. Hirshfeld surface analysis indicates that H...H (30.2%), N...H/H...N (22.3%), C...H/H...C (17.9%) and O...H/H...O (15.4%) interactions make the most significant contributions to the crystal packing.

The crystal structures and Hirshfeld surface analyses of four similar azo compounds are reported. (E)-1-[1-(4-tert-Butylphenyl)-2,2-dichloroethenyl]-2-phenyldiazene, C18H18Cl2N2, (I), and (E)-1-[1-(4-tert-butylphenyl)-2,2-dichloroethenyl]-2-(4-methylphenyl)diazene, C19H20Cl2N2, (II), crystallize in the monoclinic space group C2/c with Z = 8, and (E)-1-[1-(4-tert-butylphenyl)-2,2-dichloroethenyl]-2-(4-methoxyphenyl)diazene, C19H20Cl2N2O, (III), in the monoclinic space group P21/c with Z = 4. (E)-1-[1-(4-tert-Butylphenyl)-2,2-dichloroethenyl]-2-(3-methylphenyl)diazene, C19H20Cl2N2, (IV), crystallizes in the triclinic space group P\overline{1} with Z = 4 and comprises two molecules (A and B) in the asymmetric unit. In the crystal structures of (I) and (II), molecules are linked by C—H...π and C—Cl...π interactions, forming layers parallel to (\overline{2}02), while molecules of (III) are linked by C—H...O contacts, C—H...π and C—Cl...π interactions forming layers parallel to (\overline{3}02). The stability of the molecular packing is ensured by van der Waals forces between these layers. In the crystal structure of (IV), molecules are linked by C—H...π and C—Cl...π interactions, forming a tri-periodic network.

In the title complex, [Ni(C6H6N3OS)2]·2CH3OH, the NiII atom is coordinated by the S and N atoms of two N′-[(Z)-(furan-2-yl)methylidene]carbamohydrazonothioic acid ligands in a distorted square-planar geometry. The two mutual ligands bound to NiII are also connected by C—H...S interactions, while the H atoms of the NH2 group of the ligands form R44(8) motifs with the O atoms of the solvent ethyl alcohol molecules. At the same time, the OH groups of the solvent ethyl alcohol molecules form parallel layers to the (011) plane by the O—H...N interactions with the ligand N atom that is not bonded to the NiII atom.. The layers are connected by van der Waals interactions. A Hirshfeld surface analysis indicates that the most important contacts are H...H (37.7%), C...H/H...C (14.6%), O...H/H...O (11.5%) and S...H/H...S (10.6%).

The 1,4-dihydropyridine ring of the title compound, C24H29F2NO4, adopts a distorted boat conformation, while the cyclohexene ring is in an almost twist-boat conformation. In the crystal, N—H...O and C—H...O hydrogen bonds as well as C—H...π interactions connect molecules, forming layers parallel to the (100) plane. These layers are linked by van der Waals forces and C—H...F interactions, which consolidate the crystal structure. Hirshfeld surface analysis shows the major contributions to the crystal packing are from H...H (54.1%), F...H/H...F (16.9%), O...H/H...O (15.4%) and C...H/H...C (12.6%) contacts.

In the title compound, C20H12N6O·C2H6OS, the [1,2,4]triazolo[1,5-a]pyridine ring system is almost planar and makes dihedral angles of 16.33 (7) and 46.80 (7)°, respectively, with the phenylamino and phenyl rings. In the crystal, molecules are linked by intermolecular N—H...O and C—H...O hydrogen bonds into chains along the b-axis direction through the dimethyl sulfoxide solvent molecule, forming C(10)R21(6) motifs. These chains are connected via S—O...π interactions, π–π stacking interactions between the pyridine rings [centroid-to-centroid distance = 3.6662 (9) Å] and van der Waals interactions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H...H (28.1%), C...H/H...C (27.2%), N...H/H...N (19.4%) and O...H/H...O (9.8%) interactions.

In the title compound, C19H15N5S, the thiophene ring is disordered in a 0.6:0.4 ratio by an approximate 180° rotation of the ring around the C—C bond linking it to the pyridine ring. In the crystal, the molecules are linked by N—H...N hydrogen bonds into dimers with an R22(12) motif, forming chains along the b-axis direction. These chains are connected to each other by further N—H...N hydrogen bonds, forming a three-dimensional network. Furthermore, N—H...π and π–π [centroid–centroid separations = 3.899 (8) and 3.7938 (12) Å] interactions also contribute to the crystal cohesion. A Hirshfeld surface analysis indicated that the most important contributions to the surface contacts are from H...H (46.1%), N...H/H...N (20.4%) and C...H/H...C (17.4%) interactions.

The asymmetric unit of the title compound, C11H7N5OS, contains two independent molecules (1 and 2). The thiophene ring in molecule 2 is rotationally disordered (flip disorder) by ca 180° (around the single C—C bond, to which it is attached) over two sites with the site-occupation factors of 0.9 and 0.1. These two orientations of the thiophene ring in molecule 2 are not equivalent. In the crystal, molecules are linked by intermolecular N—H...O and N—H...N hydrogen bonds into ribbons parallel to (022) along the a axis. Within the (022) planes, these ribbons are connected by van der Waals interactions and between the (022) planes by N—H...O hydrogen bonds. In molecule 1, Hirshfeld surface analysis showed that the most important contributions to the crystal packing are from N...H/H...N (27.1%), H...H (17.6%), C...H/H...C (13.6%) and O...H/H...O (9.3%) interactions, while in molecule 2, H...H (25.4%) interactions are the most significant contributors to the crystal packing.

In the title compound, C31H44O5, molecules are connected by O—H...O and C—H...O hydrogen bonds, forming hydrogen-bonded zigzag chains running along the b axis and parallel to the (001) plane. The molecular packing is stabilized by van der Waals interactions between these chains along the a and c axes. The intermolecular interactions in the crystal structure were quantified and analysed using Hirshfeld surface analysis.

In the title compound, C20H26O5, the two cyclohexane rings adopt boat and half-chair conformations. In the crystal, adjacent molecules are connected by intermolecular C—H...O hydrogen bonds, forming a three-dimensional network. According to a Hirshfeld surface study, H...H interactions are the most significant contributors to the crystal packing (63.0%).

In the polymeric title compound, {[Na(C10H9N4O4S)(H2O)3]·2H2O}n, sixfold coordinated Na+ cations are linked into a chain parallel to [010] by sharing common water molecules. Next to the four bridging water molecules, each Na+ cation of the chain is bonded to the O atom of a terminal water molecule and an O atom of the SO3− group of the sulfonate anion. Classical O—H...O, O—H...N and N—H...O hydrogen bonds and additional π–π interactions connect these chains into a three-dimensional network.

In the title compound, C23H17N3O9S2, C—H...O hydrogen bonds link adjacent molecules in a three-dimensional network, while π–π stacking interactions, with centroid–centroid distances of 3.8745 (9) Å, between the furan and an arene ring of one of the two (3-nitrophenyl)sulfonyl groups, result in chains parallel to the a axis. The Hirshfeld surface analysis indicates that O...H/H...O (40.1%), H...H (27.5%) and C...H/H...C (12.4%) interactions are the most significant contributors to the crystal packing.

The crystal structures and Hirshfeld surface analyses of three salts of 1-(4-nitrophenyl)piperazine with 2-chlorobenzoic acid, 2-bromobenzoic acid and 2-iodobenzoic acid are reported. The chlorobenzoate salt, C10H14N3O2+·C7H4ClO2−, contains whole-ion-disordered cations and anions, which were modeled with two equivalent conformations with occupancies of 0.745 (10)/0.255 (10) and 0.563 (13)/0.437 (13), respectively. The bromobenzoate and iodobenzoate derivatives are isomorphous and crystallize as hemihydrates, viz. C10H14N3O2+·C7H4BrO2−·0.5H2O and C10H14N3O2+·C7H4IO2−·0.5H2O, respectively [the water molecule is disordered over two locations with occupancies of 0.276 (3)/0.223 (3) for the iodobenzoate derivative]. In the extended structures, all three salts feature an R44(12) loop of two anions and two cations linked by N—H...O hydrogen bonds.

In the title compound, C32H29N5O2·C3H7NO, the bicyclo[3.3.1]nonane ring system adopts a half-chair/twist-boat conformation, with the phenyl rings in equatorial orientations with respect to the piperidine ring. The two oxane rings of the 2-oxabicyclo[2.2.2]octane ring system exhibit a distorted boat conformation. Intermolecular C—H...O and C—H...N hydrogen bonds connect the molecules in the crystal, generating layers extending parallel to (100). These layers are connected by C—H...π interactions. A Hirshfeld surface analysis was performed to quantify the contributions of the different intermolecular interactions, indicating that the most important contributions to the crystal packing are from H...H (52.5%), N...H/H...N (19.2%), C...H/H...C (18.8%) and O...H/H...O (8.3%) interactions.

The title compound, C20H21F3N2O4, features a main twelve-membered difuryl ring with which the furan rings make dihedral angles of 76.14 (5) and 33.81 (5)°. The dihedral angle between the furan rings is 42.55 (7)°. The six-membered nitrogen heterocycle has a twist-boat conformation. In the crystal, pairs of molecules are connected by intermolecular C—H...O interactions, generating an R22(14) ring motif. These pairs of molecules form zigzag chains along the a-axis direction by means of C—H...F interactions. Furthermore, C—H...π and C–F...π interactions link the molecules into chains along the b-axis direction, forming sheets parallel to the (001) plane. These sheets are also connected by van der Waals interactions.