Crystal structure of N,N'-bis-(pyridin-3-ylmeth-yl)cyclo-hexane-1,4-di-ammonium dichloride

The title salt, C₁₈H₂₆N₄²⁺·2Cl^-, was obtained by the protonation of N,N-bis-(pyridin-4-ylmeth-yl)cyclo-hexane-1,4-di-amine with hydro-chloric acid in ethanol. The asymmetric unit consists of one half of an N,N-bis-(pyridin-3-ylmeth-yl)cyclo-hexane-1,4-di-ammonium dication, with a crystallographic inversion centre located at the centre of the cyclo-hexyl ring, and a chloride anion. The central cyclo-hexyl ring in the dication adopts a chair conformation. The two trans-(4-pyridine)-CH₂-NH₂- moieties at the 1- and 4-positions of the central cyclo-hexyl ring occupy equatorial sites. The terminal pyridine ring is tilted by 53.72 (6)° with respect to the mean plane of the central cyclo-hexyl ring (r.m.s. deviation = 0.2413 Å). In the crystal, N⁺-H⋯Cl^- hydrogen bonds between the dications and the chloride anions, and π-π stacking inter-actions between the pyridine rings of the dications afford a two-dimensional sheet extending parallel to the ab plane. These sheets are further connected through weak C-H⋯Cl^- hydrogen bonds, resulting in the formation of a three-dimensional supra-molecular network.