Synthesis and structure of clozapine N -oxide hemi(hydro-chloride): an infinite hydrogen-bonded poly[ n ]catenane.

The structure of the title compound, 2C 18 H 19 ClN 4 O·HCl or (CNO) 2 ·HCl (C 36 H 39 Cl 3 N 8 O 2 ), at 100 K has tetra-gonal ( I 4/ m ) symmetry. The dihedral angle between the benzene rings of the fused ring system of the CNO mol-ecule is 40.08 (6)° and the equivalent angle between the seven-membered ring and its pendant N -oxide ring is 31.14 (7)°. The structure contains a very strong, symmetrical O-H⋯O hydrogen bond [O⋯O = 2.434 (2) Å] between two equivalent R 3 N + -O - moieties, which share a proton lying on a crystallographic twofold rotation axis. These units then form a (CNO) 4 ·(HCl) 2 ring by way of two equivalent N-H⋯Cl hydrogen bonds (Cl - site symmetry m ). These rings are catenated into infinite chains propagating along the c -axis direction by way of shape complementarity and directional C-H⋯N and C-H⋯π inter-actions.