9-(7-Fluoro-4-oxo-4H-chromen-3-yl)-3,3,6,6-tetra­methyl-2,3,4,5,6,7,8,9-octa­hydro-1H-xanthene-1,8-dione

In the title compound, C₂₆H₂₅FO₅, the terminal cyclo­hexane rings of the xanthene ring system adopt half-boat conformations. The 4H-chromene ring make a dihedral angle of 87.94 (5)° with the xanthene ring system and its carbonyl O atom lies above the xanthene O atom. In the crystal, mol­ecules are linked into ribbons propagating along the a-axis direction by C—H...O hydrogen bonds. Aromatic π–π stacking inter­actions [centroid–centroid distance = 3.7367 (12) Å] also occur.

2,2′-[2,4-Bis(naphthalen-1-yl)cyclo­butane-1,3-di­yl]bis­(1-methyl­pyridinium) diiodide: thermal-induced [2 + 2] cyclo­addition reaction of a heterostilbene

The asymmetric unit of the title compound, C₃₆H₃₂N₂²⁺·2I⁻, consists of one half-mol­ecule of the cation and one I⁻ anion. The cation is located on an inversion centre. The dihedral angle between the pyridinium ring and the naphthalene ring system in the asymmetric unit is 19.01 (14)°. In the crystal, the cations and the anions are linked by C—H...I inter­actions into a layer parallel to the bc plane. Intra- and inter­molecular π–π inter­actions with centroid–centroid distances of 3.533 (2)–3.807 (2) Å are also observed.

4-(4-Bromo­phen­yl)-1-(2,6-difluoro­benz­yl)-3-(3,4,5-trimeth­oxy­phen­yl)-1H-1,2,4-triazole-5(4H)-thione

In the title compound, C₂₄H₂₀BrF₂N₃O₃S, the triazole ring (r.m.s. deviation = 0.0107 Å) makes dihedral angles of 28.18 (14), 63.76 (14) and 77.01 (18)°, respectively, with the trimeth­oxy-, bromo-, and difluoro-substituted benzene rings. The C atoms of the meta meth­oxy groups are roughly coplanar with their ring [displacements = −0.289 (4) and 0.083 (7) Å], whereas the C atom of the para group is displaced [1.117 (3) Å]. In the crystal, inversion dimers linked by two pairs of C—H...O hydrogen bonds occur. The ring motif of the two hydrogen bonds to their symmetry-generated O-atom acceptors is R₂²(8).

2-Amino-5-chloro­pyrimidin-1-ium hydrogen maleate

In the title salt, C₄H₅ClN₃⁺·C₄H₃O₄⁻, the 2-amino-5-chloro­pyrimidinium cation is protonated at one of its pyrimidine N atoms. In the roughly planar (r.m.s. deviation = 0.026 Å) hydrogen malate anion, an intra­molecular O—H...O hydrogen bond generates an S(7) ring. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl­ate O atoms of the anion via a pair of N—H...O hydrogen bonds, forming an R²₂(8) ring motif. The ion pairs are connected via further N—H...O hydrogen bonds and a short C—H...O inter­action, forming layers lying parallel to the bc plane.

1-(4,4′′-Difluoro-5′-meth­oxy-1,1′:3′,1′′-terphenyl-4′-yl)ethanone

In the title compound, C₂₁H₁₆F₂O₂, the central benzene ring is inclined at dihedral angles of 30.91 (8) and 46.88 (7)° to the two terminal fluoro-substituted rings. The dihedral angle between the two terminal fluoro-subsituted rings is 68.34 (8)°. An intra­molecular C—H...O hydrogen bond generates an S(6) ring motif. The crystal structure is stabilized by weak C—H...π inter­actions.

Ethyl 4,4′′-difluoro-5′-meth­oxy-1,1′:3′,1′′-terphenyl-4′-carboxyl­ate

In the title compound, C₂₂H₁₈F₂O₃, the two fluoro-substituted rings form dihedral angles of 25.89 (15) and 55.00 (12)° with the central benzene ring. The eth­oxy group in the mol­ecule is disordered over two positions with a site-occupancy ratio of 0.662 (7):0.338 (7). In the crystal, mol­ecules are linked by C—H...O hydrogen bonds into chains along the a axis. The crystal packing is further stabilized by C—H...π and π—π inter­actions, with centroid–centroid distances of 3.8605 (15) Å.

(E)-2-[(E)-3-(Hy­droxy­imino)­butan-2-yl­idene]-N-methyl­hydrazinecarbothio­amide

In the title compound, C₆H₁₂N₄OS, an intra­molecular N—H...N hydrogen-bond is present giving rise to an S(5) ring motif. In the crystal, double-stranded chains propagating along [10] are formed via pairs of O—H...S and N—H...S hydrogen bonds. The chains are further stabilized by C—H...S interactions.

2,3-Diamino­pyridinium sorbate–sorbic acid (1/1)

In the title mol­ecular salt–adduct, C₅H₈N₃⁺·C₆H₇O₂⁻·C₆H₈O₂, the 2,3-diamino­pyridinium cation is essentially planar, with a maximum deviation of 0.013 (2) Å, and is protanated at its pyridine N atom. The sorbate anion and sorbic acid mol­ecules exist in extended conformations. In the crystal, the protonated N atom and one of the two amino-group H atoms are hydrogen bonded to the sorbate anion through a pair of N—H...O hydrogen bonds, forming an R₁²(6) ring motif. The carboxyl groups of the sorbic acid mol­ecules and the carboxyl­ate groups of the sorbate anions are connected via O—H...O hydrogen bonds. Furthermore, the ion pairs and neutral mol­ecules are connected via inter­molecular N—H...O hydrogen bonds, forming sheets lying parallel to (100).