Racemic mefloquinium chloro-difluoro-acetate: crystal structure and Hirshfeld surface analysis.

In the racemic title mol-ecular salt, CHFNO·CClFO (systematic name: 2-{[2,8-bis-(tri-fluoro-meth-yl)quinolin-4-yl](hy-droxy)meth-yl}piperidin-1-ium chloro-difluoro-acetate), the cation, which is protonated at the piperidine N atom, has the shape of the letter, , with the piperidin-1-ium group being approximately orthogonal to the quinolinyl residue [the C-C-C-N (q = quinolinyl; m = methine; a = ammonium) torsion angle is 177.79 (18)°]. An intra-molecular, charge-assisted ammonium--⋯(hydrox-yl) hydrogen bond ensures the hy-droxy-O and ammonium-N atoms lie to the same side of the mol-ecule [O-C-C-N (h = hydrox-yl) = -59.7 (2)°]. In the crystal, charge-assisted hydroxyl-O-H⋯O(carboxyl-ate) and ammonium-N-H⋯O(carboxyl-ate) hydrogen bonds generate a supra-molecular chain along [010]; the chain is consolidated by C-H⋯O inter-actions. Links between chains to form supra-molecular layers are of the type C-Cl⋯π(quinolinyl-C) and the layers thus formed stack along the -axis direction without directional inter-actions between them. The analysis of the calculated Hirshfeld surface points to the dominance of F⋯H contacts to the surface (40.8%) with significant contributions from F⋯F (10.5%) and C⋯F (7.0%) contacts.