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 (I4/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)†à ] 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.