Crystal structure of 3,9,9-trimethyl-2,3,3a,4,9,9a-hexa-hydro-1H-cyclo-penta[b]quinolin-4-ium chloride.

The title mol-ecular salt, C15H22N(+)·Cl(-), arose as an unexpected product of the reaction between aniline and melanol in the presence of HCl. The central heterocyclic ring has a half-chair conformation and the five-membered ring has an envelope conformation, with the C atom linked to the N atom as the flap. In the crystal, the ions are linked by N-H⋯Cl hydrogen bonds, generating chains propagating in the [100] direction. The crystal studied was a merohedral twin with a 0.64 (3):0.36 (3) domain ratio.