Low-dimensional compounds containing bioactive ligands. IV. Unusual ionic forms of 5-chloro­quinolin-8-ol

Bis(5-chloro-8-hy­droxy­quinolinium) tetra­chloridopalladate(II), (C₉H₇ClNO)₂[PdCl₄], (I), catena-poly[dimethyl­ammonium [[di­chloridopalladate(II)]-μ-chlorido]], {(C₂H₈N)[PdCl₃]}_n, (II), ethyl­enediammonium bis­(5-chloro­quinolin-8-olate), C₂H₁₀N₂²⁺·2C₉H₅ClNO⁻, (III), and 5-chloro-8-hy­droxy­quinolinium chloride, C₉H₇ClNO⁺·Cl⁻, (IV), were synthesized with the aim of preparing biologically active complexes of Pd^II and Ni^II with 5-chloro­quinolin-8-ol (ClQ). Compounds (I) and (II) contain Pd^II atoms which are coordinated in a square-planar manner by four chloride ligands. In the structure of (I), there is an isolated [PdCl₄]²⁻ anion, while in the structure of (II) the anion consists of Pd^II atoms, lying on centres of inversion, bonded to a combination of two terminal and two bridging Cl⁻ ligands, lying on twofold rotation axes, forming an infinite [–μ₂-Cl–PdCl₂–]_n chain. The negative charges of these anions are balanced by two crystallographically independent protonated HClQ⁺ cations in (I) and by dimethyl­ammonium cations in (II), with the N atoms lying on twofold rotation axes. The structure of (III) consists of ClQ⁻ anions, with the hy­droxy groups deprotonated, and centrosymmetric ethyl­ene­di­ammonium cations. On the other hand, the structure of (IV) consists of a protonated HClQ⁺ cation with the positive charge balanced by a chloride anion. All four structures are stabilized by systems of hydrogen bonds which occur between the anions and cations. π–π inter­actions were observed between the HClQ⁺ cations in the structures of (I) and (IV).