4-(piperidin-1-yl)pyridinium hexafluorophosphate at 150 K

Structural characterization of the title compound, C₁₀H₁₅N₂⁺·PF₆ ^-, shows it to be ionic, with the pyridine rather than the piperidine N atom being protonated and forming hydrogen bonds to the counter-ions, resulting in two independent ion pairs. A number of unusual features are noted, in particular the remarkably close inter-ring hydrogen contacts [1.97 (3)-2.00 (3) Å] and the considerable differences in the pair of cations, in respect of the torsion angles within the piperidine ring involving the bonds to either side of the N atom.