Crystal structure of 7,7′-[(pyridin-2-yl)methylene]bis(5-chloroquinolin-8-ol)

In the crystal, molecules of the title compound, a potential ligand containing two 8-quinolinol and one 2-pyridine units, are linked by intermolecular O—H⋯N and O—H⋯O quadruple hydrogen bonds, forming an inversion dimer with two (7) ring motifs. The dimers are associated through a C—H⋯O hydrogen bond and four C—H⋯π interactions.

In the title compound, C 24 H 15 Cl 2 N 3 O 2 , one quinoline ring system is essentially planar and the other is slightly bent. An intramolecular O-HÁ Á ÁN hydrogen bond involving the hydroxy group and a pyridine N atom forms an S(5) ring motif. In the crystal, two molecules are associated into an inversion dimer with two R 2 2 (7) ring motifs through intermolecular O-HÁ Á ÁN and O-HÁ Á ÁO hydrogen bonds. The dimers are further linked by an intermolecular C-HÁ Á ÁO hydrogen bond and four C-HÁ Á Á interactions, forming a two-dimensional network parallel to (001).

Structural commentary
The molecular structure of the title compound is shown in Fig. 1. One quinoline ring system is essentially planar, the dihedral angle between the mean planes through C22-C24/N6 and C26/C18-C20 being 0.5 (2) . The other quinoline ring system is slightly bent, the dihedral angle between the mean planes through N5/C10-C12 and C14-C16/C8 being 5.77 (18) .

Figure 2
A centrosymmetric dimeric structure of the title compound. The intraand intermolecular hydrogen bonds are shown as dashed lines. H atoms not involved in these interactions have been omitted for clarity.

Figure 3
A packing diagram of the title compound, showing the ribbon structure. The C-HÁ Á Á interactions between the dimers are shown as dashed lines. H atoms not involved in the interactions have been omitted for clarity.

Figure 1
The molecular structure of the title compound, with the atom labelling. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented by spheres of arbitrary radius. The intramolecular O-HÁ Á ÁN hydrogen bonds are shown as dashed lines.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. Hydroxy H atoms were located in a difference-Fourier map and freely refined. C-bound H atoms were placed in geometrically calculated positions (C-H = 0.95-1.00 Å ) and refined as part of a riding model with U iso (H) = 1.2U eq (C). One outlier (111) was omitted from the refinement.

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. Refinement. Refinement was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F 2 . R-factor (gt) are based on F. The threshold expression of F 2 > 2.0 sigma(F 2 ) is used only for calculating Rfactor (gt).