7-[(3-Chloro-6-methyl-6,11-dihydrodibenzo[c,f][1,2]thiazepin-11-yl)amino] heptanoic acid S,S-dioxide hydrochloride

In the title compound, C₂1H₂6ClN₂O ₄S^.Cl, also known as tianeptine hydrochloride, the seven-membered ring adopts a boat conformation. The dihedral angle between the mean planes of the benzene rings is 44.44(7)°. There is an intramolecular hydrogen bond formed via S= O⋯H-N. In the crystal, molecules are connected via pairs of N-H.·O, N-H⋯Cl and O-H⋯Cl hydrogen bonds, forming inversion dimers, which are consolidated by C-H⋯O interactions. The dimers are linked by C-H⋯O and C-H⋯Cl interactions, forming a two-dimensional network lying parallel to (011).