8-(2,2,2-Trifluoroethoxy)quinolinium perchlorate–8-(2,2,2-trifluoroethoxy)quinoline (1/1)

The title compound, C11H9F3NO+·ClO4 −·C11H8F3NO or [(C11H8F3NO)H(C11H8F3NO)]ClO4, contains two 8-(2,2,2-trifluoroethoxy)quinoline molecules, one of which combines a proton from perchloric acid to form the corresponding quinolinium cation. The quinolinium and quinoline rings form a cationic unit via an intermolecular N—H⋯N hydrogen bond. The heterocyclic units are almost perpendicular to each other [interplanar angle 86.97 (6)°]. In the crystal, each perchlorate anion bridges two adjacent cationic units and creates a chain by a combination of C—H⋯O hydrogen bonds. Two inversion-related chains associate into a molecular column by π–π stacking interactions between the quinolinium rings. The perpendicular and centroid–centroid distances between adjacent quinolinium rings are 3.501 (3) and 3.634 (9) Å, respectively. The molecular column is linked to its neighbors, creating a two-dimensional network via the weak π–π stacking between the quinoline rings [perpendicular and centroid–centroid separations 3.340 (4) and 4.408 (4) Å, respectively]. Finally, a three-dimensional framework is formed by a combination of intermolecular C—F⋯π contacts. One –CF3 group is disordered over two positions of equal occupancy.

The title compound, C 11 H 9 F 3 NO + ÁClO 4 À ÁC 11 H 8 F 3 NO or [(C 11 H 8 F 3 NO)H(C 11 H 8 F 3 NO)]ClO 4 , contains two 8-(2,2,2trifluoroethoxy)quinoline molecules, one of which combines a proton from perchloric acid to form the corresponding quinolinium cation. The quinolinium and quinoline rings form a cationic unit via an intermolecular N-HÁ Á ÁN hydrogen bond. The heterocyclic units are almost perpendicular to each other [interplanar angle 86.97 (6) ]. In the crystal, each perchlorate anion bridges two adjacent cationic units and creates a chain by a combination of C-HÁ Á ÁO hydrogen bonds. Two inversion-related chains associate into a molecular column bystacking interactions between the quinolinium rings. The perpendicular and centroid-centroid distances between adjacent quinolinium rings are 3.501 (3) and 3.634 (9) Å , respectively. The molecular column is linked to its neighbors, creating a two-dimensional network via the weakstacking between the quinoline rings [perpendicular and centroid-centroid separations 3.340 (4) and 4.408 (4) Å , respectively]. Finally, a three-dimensional framework is formed by a combination of intermolecular C-FÁ Á Á contacts. One -CF 3 group is disordered over two positions of equal occupancy.
Here, we report its crystal structure.
In the crystal structure of the title complex the asymmetric unit contains one perchlorate anion and one organic cation consisting of two 8-(2,2,2-trifluoroethoxy)-quinolines and a proton (Fig. 1). In the cationic unit, one quinoline ring is protonated forming a quinolinium and is connected to the other one via a N-H···N hydrogen bond (N-H···N angle 155.33 (5)°,  Table 1). This distance is shorter than 2.729 Å reported for a similar quinoline derivative (Ouyang et al., 1998). Such a short distance may be ascribed to the presence of two weak C-F···π contacts (Prasanna & Row, 2000;Saraogi et al., 2003;Choudhury & Row, 2004) between the non-disordered trifluoromethyl group and the quinoline ring. Separations of F5···Cg1 and F6···Cg2 (Cg1 and Cg2 are the centroids of N1-C5 and C5-C9 bonds, respectively) are 3.099 (3) and 3.166 (3) Å, respectively. The quinolinium and quinoline rings are almost perpendicular to each other, with a dihedral angle of 86.97 (6)°. The other trifluoromethyl group is disordered over two orientations, with refined site-occupancy factors of 0.5.

Refinement
All non-hydrogen atoms were refined with anisotropic displacement parameters. Hydrogen atoms attached to anisotropically refined atoms were placed in geometrically idealized positions and included as riding atoms with C-H = 0.93Å and U iso (H) = 1.2U eq (C) (aromatic); C-H = 0.97Å and U iso (H) = 1.2U eq (C) (methylene); N-H = 0.86Å and U iso (H) = 1.2U eq (N).
In the title molecule, one trifluoromethyl group was disordered over two orientations, with refined site occupation factors of 0.5: 0.5. Fig. 1. Molecular structure of the title complex, with displacement ellipsoids drawn at the 30% probability level. Fig. 2. Hydrogen-bonded cationic unit, with weak C-F···π contacts. For the sake of clarity, the disordered moieties and the H atoms not involved in hydrogen bonding have been omitted. Fig. 3. Molecular column formed by hydrogen bonds and π-π stackings, viewed along the a axis. The disordered moieties and H atoms not involved in hydrogen bonding have been omitted for clarity. [Symmetry codes: (i) -x + 1, -y + 1, -z + 1; (ii) -x + 1, -y + 1, -z + 2].