Desipramine hydro­chloride: a non-merohedrally twinned structure

The title compound, C(18)H(23)N(2) (+)·Cl(−), is a non-merohedrally twinned salt [domains 0.9288 (3) and 0.0712 (3)] which crystallizes with four independent cation–anion pairs in the asymmetric unit. The seven-membered ring in each of the cations adopts a boat conformation, thus creating a butterfly effect within the ring system. The average value of the dihedral angle between the two aromatic rings in the four cations is 57.1 (1)°. The crystal packing is stabilized only slightly by a collection of inter­mediate N—H⋯Cl hydrogen-bonding inter­actions, which produce a weak, but cooperative, infinite, one-dimensional, inter­molecular hydrogen-bond network along the a axis. A MOPAC PM3 computational calculation gives support to these observations.