Amitriptylinium picrate: Conformational disorder

In the structure of the title salt [systematic name: 3-(10,11-dihydro-5H- dibenzo[a,d][7]annulen-5-yl-idene)-N,N-dimethyl-propan-1-aminium 2,4,6-trinitro-phenolate] of a tricyclic anti-depressant, C20H24N +·C6H2N3O7 -, the dimethyl-amino-propyl subunit possesses a classical static conformational disorder. The central cyclo-hepta-diene ring adopts a bent conformation that is inter-mediate between boat and chair forms, leading to a butterfly shape for the hetero-tricyclic moiety. In a complementary fashion, donors from amitriptyline and acceptors from picrate form inter-molecular C - H⋯O hydrogen bonds and N - H⋯O salt bridges. These hydrogen bonds cluster amitriptyline and picrate ions into a closed R 4 4(36) hetero-tetra-mer, whereas inter-molecular C - H⋯π inter-actions between amitriptyline ions cluster them into homo-dimers. Significant π-π stacking inter-actions are also observed between aromatic rings of amitriptyline and picrate, and these, combined with the C - H⋯π inter-actions, associate mol-ecules into linear arrays along the [1 1] direction.