Crystal structure of 2-oxo-2H-chromen-7-yl 4-fluoro-benzoate.

In the title compound, C16H9FO4, (I), the benzene ring is oriented at an acute angle of 59.03 (15)° relative to the coumarin plane (r.m.s deviation = 0.009 Å). This conformation of (I) is stabilized by an intra-molecular C-H⋯O hydrogen bond, which closes a five-membering ring. In the crystal, mol-ecules of (I) form infinite zigzag chains along the b-axis direction, linked by C-H⋯O hydrogen bonds. Furthermore, the crystal structure is supported by π-π stacking inter-actions between neighbouring pyrone and benzene or coumarin rings [centroid-centroid distances in the range 3.5758 (18)-3.6115 (16) Å], as well as C=O⋯π inter-actions [O⋯centroid distances in the range 3.266 (3)-3.567 (3) Å]. The theoretical data for (I) obtained from quantum chemical calculations are in good agreement with the observed structure, although the calculated C-O-C-C torsion angle between the coumarin fragment and the benzene ring (73.7°) is somewhat larger than the experimental value [63.4 (4)°]. Hirshfeld surface analysis has been used to confirm and qu-antify the supra-molecular inter-actions.

2-Oxo-2H-chromen-7-yl 4-tert-butyl-benzoate.

In the title compound, C20H18O4, the benzoate ring is oriented at an acute angle of 33.10 (12)° with respect to the planar (r.m.s deviation = 0.016 Å) coumarin ring system. An intra-molecular C-H⋯O hydrogen bond closes an S(6) ring motif. In the crystal, C-H⋯O contacts generate infinite C(6) chains along the b-axis direction. Also present are π-π stacking inter-actions between neighbouring pyrone and benzene rings [centroid-centroid distance = 3.7034 (18) Å] and C=O⋯π inter-actions [O⋯centroid = 3.760 (3) Å]. The data obtained from quantum chemical calculations performed on the title compound are in good agreement with the observed structure, although the calculated C-O-C-C torsion angle between the coumarin ring system and the benzoate ring (129.1°) is somewhat lower than the observed value [141.3 (3)°]. Hirshfeld surface analysis has been used to confirm and qu-antify the supra-molecular inter-actions.

Crystal structure of 3-(2-hy-droxy-eth-yl)-2-methyl-sulfanyl-6-nitro-3H-benzimidazol-1-ium chloride monohydrate.

In the cation of the title hydrated molecular salt, C10H12N3O3S+·Cl-·H2O, the benzimidazolium ring system is almost planar (r.m.s. deviation = 0.006 Å) and the nitro group is inclined at an angle of 4.86 (9)° to this plane. In the crystal, C-H⋯O hydrogen bonds form centrosymmetric R22(20) dimers and these are further aggregated through N-H⋯O and O-H⋯Cl hydrogen bonds involving the water mol-ecules and chloride anions. Aromatic π-π stacking inter-actions are also found between two parallel benzene rings or the benzene and imidazolium rings, with centroid-centroid distances of 3.5246 (9) and 3.7756 (9) Å, respectively. Analysis of the bond lengths and comparison with related compounds show that the nitro substituent is not involved in conjugation with the adjacent π-system and hence has no effect on the charge distribution of the heterocyclic ring.