The crystal structures of three clozapinium salts: different molecular configurations, and supramolecular assembly in one, two and three dimensions

The structures of three salts derived from clozapine, 8-chloro-11-(4-methyl­piperazin-1-yl)-5H-dibenzo[b,e][1,4]diazepine, are reported, namely, clo­za­pin­ium 3,5-di­nitro­benzoate dimethyl sulfoxide monosolvate, C₁₈H₂₀ClN₄⁺·C₇H₃N₂O₆^-·C₂H₆OS, (I), where the dimethyl sulfoxide component is disordered over two sets of atomic sites having occupancies 0.627 (2) and 0.373 (2); clo­za­pin­ium hydrogen maleate 0.21-hydrate, C₁₈H₂₀ClN₄⁺·C₄H₃O₄^-·0.21H₂O, (II), and clozapinium 2-hy­droxy­benzoate, C₁₈H₂₀ClN₄⁺·C₇H₅O₃^-, (III). In all three salts, the protonation site is the methyl­ated N atom of the piperazine ring, and the dimensions and conformations of the fused tricyclic system are very similar. However, differences are apparent in the piperazine component: in both compounds (II) and (III), the unprotonated N atom of this ring has a pyramidal geometry, but in compound (I) this atom has a planar geometry. In compound (III), both N-substituents in this ring occupy equatorial sites, but in compound (II) the fused tricyclic system occupies an axial site of the piperazine ring. The independent components of compound (I) are linked within the selected asymmetric unit by a combination of N-HO and C-HO hydrogen bonds, and these hydrogen-bonded aggregates are linked into chains by an aromatic - stacking inter­action. In compound (II), the components are linked into sheets by a combination of O-HO, N-HO and C-HO hydrogen bonds, and in compound (III), a combination of N-HO, C-HO and C-HN hydrogen bonds links the components into a three-dimensional framework structure. Comparisons are made with some similar compounds.