8-Hy­droxy­quinolinium tri­chlorido­(pyridine-2,6-di­carb­oxy­lic acid-κ3O,N,O′)copper(II) dihydrate

The title compound, (C₉H₈NO)[CuCl₃(C₇H₅NO₄)]·2H₂O, was synthesized by reacting Cu^II acetate, 8-hy­droxy­quinoline, and pyridine-2,6-di­carb­oxy­lic acid in dilute hydro­chloric acid in a 1:1:1 molar ratio. The Cu^II atom exhibits a distorted octa­hedral geometry coordinated by the H₂pydc ligand and chloride atoms. In the crystal structure, various hydrogen bonds and weak inter­actions lead to the formation of a three-dimensional network.

The title compound, (C₉H₈NO)[CuCl₃(C₇H₅NO₄)]·2H₂O, was prepared by reacting Cu^II acetate dihydrate, solid 8-hy­droxy­quinoline (8-HQ), and solid pyridine-2,6-di­carb­oxy­lic acid (H₂pydc), in a 1:1:1 molar ratio, in an aqueous solution of dilute hydro­chloric acid. The Cu^II atom exhibits a distorted CuO₂NCl₃ octa­hedral geometry, coordinating two oxygen atoms and one nitro­gen atom from the tridentate H₂pydc ligand and three chloride atoms; the nitro­gen atom and one chloride atom occupy the axial positions with Cu—N and Cu—Cl bond lengths of 2.011 (2) Å and 2.2067 (9) Å, respectively. In the equatorial plane, the oxygen and chloride atoms are arranged in a cis configuration, with Cu—O bond lengths of 2.366 (2) and 2.424 (2) Å, and Cu—Cl bond lengths of 2.4190 (10) and 2.3688 (11) Å. The asymmetric unit contains 8-HQ⁺ as a counter-ion and two uncoordinated water mol­ecules. The crystal structure features strong O—H⋯O and O—H⋯Cl hydrogen bonds as well as weak inter­actions including C—H⋯O, C—H⋯Cl, Cu—Cl⋯π, and π–π, which result in a three-dimensional network. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing involving the main residues are from H⋯Cl/Cl⋯H inter­actions, contributing 40.3% for the anion. Weak H⋯H contacts contribute 13.2% for the cation and 28.6% for the anion.