Crystal structure of 3-benzamido-1-(4-nitrobenzyl)quinolinium trifluoromethanesulfonate

In the title salt, each cation shows a moderate distortion between the planes of the amide groups and the quinolinium rings. The trifluoromethanesulfonate anions are linked to organic cations via N—H⋯O hydrogen-bonding interactions involving the NH amide groups. In the crystal, weak C—H⋯O hydrogen bonds and π-stacking interactions between the quinolinium and phenyl rings link the organic cations into chains.

In the title compound, C 23 H 18 N 3 O 3 + ÁCF 3 SO 3 À , the asymmetric unit contains two crystallographically independent organic cations with similar conformations. Each cation shows a moderate distortion between the planes of the amide groups and the quinolinium rings with dihedral angles of 14.90 (2) and 31.66 (2) . The quinolinium and phenyl rings are slightly twisted with respect to each other at dihedral angles of 6.99 (4) and 8.54 (4) . The trifluoromethanesulfonate anions are linked to the organic cations via N-HÁ Á ÁO hydrogenbonding interactions involving the NH amide groups. In the crystal, the organic cations are linked by weak C-HÁ Á ÁO(nitro group) interactions into supramolecular chains propagating along the b-axis direction.

Synthesis and crystallization
A mixture of 6-aminoquinoline (1.0 g, 6.9 mmol) and benzoyl chloride (0.49 g, 3.45 mmol) in 30 mL of dry toluene-acetone (1:1 v/v) was stirred under reflux for 2.5 h. The white precipitate was collected by filtration and washed with acetone and 5% NaHCO 3 to give N-(3-quinolinyl)benzamide in 90% yield, which was reacted with 1.5 equiv. of p-nitro benzyl chloride in 30 mL of dry DMF for 5 h. The resulting yellow powder was filtered and washed with cold MeOH to give the chloride salt in 85% yield. The chloride salt was dissolved in 100 mL of hot H 2 O-MeOH (1:1 v/v) then one equiv. of silver triflate was added, the mixture was stirred at room temperature for 4 h. The precipitate of silver chloride was filtered off and yellow crystals were obtained by evaporation of the solvent at room temperature.

Refinement
Crystal data, data collection and structure refinement details are summarized in Perspective view of a fragment of the crystal structure of the title compound with hydrogen bonds N-HÁ Á ÁO shown as dashed lines. Displacement ellipsoids are drawn at the 30% probability level. H atoms have been omitted for clarity.

Figure 3
A view approximately along the a axis, showing the offset face-to-faceinteractions between the benzamide and the quinolinium group. H atoms and trifluoromethanesulfonate anions have been omitted for clarity.

Figure 4
View of the -aggregated structure. Hydrogen atoms and trifluoromethanesulfonate anions have been omitted for clarity. refined anisotropically. H atoms attached to C atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C-H = 0.93-0.98 Å and U iso (H) = 1.2U eq (C) for aromatic groups and U iso (H) = 1.5 U eq (C) for aliphatic groups (Sheldrick, 2008). N-H hydrogen atoms were localized in difference Fourier maps and refined with the bond lengths fixed at 0.90 A and the isotropic temperature factors fixed at 1.2 times those of the corresponding nitrogen atom.
Acta Cryst. (2016). E72, 747-750 research communications  Computer programs: APEX2 and SAINT (Bruker, 2012), SHELXTL (Sheldrick, 2008) and SHELXL2013 (Sheldrick, 2015). program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2015); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).  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.