Bis[triaqua-(1H-1,2,4-triazole-3,5-dicarboxyl-ato-κO,N)copper(II)] di-μ-aqua-bis-[diaqua-(1H-1,2,4-triazole-3,5-dicarboxyl-ato-κO,N)copper(II)].

In the title compound, [Cu(C(4)HN(3)O(4))(H(2)O)(3)](2)[Cu(2)(C(4)HN(3)O(4))(2)(H(2)O)(6)], both monomeric and dimeric mol-ecules are present in the solid state. In the monomeric compound, the Cu(II) atom is five-coordinated in a square-pyramidal configuration by one O atom and one N atom from one 1H-1,2,4-triazole-3,5-dicarboxyl-ate (TZDCA(2-)) ligand and three O atoms from water mol-ecules. In the centrosymmetric binuclear complex, each Cu(II) atom is six-coordinated in an octa-hedral geometry by one O atom and one N atom from one TZDCA(2-) ligand and four O atoms from water mol-ecules, two of which bridge the Cu(II) atoms. In the structure, there are intra-molecular O-H⋯O and N-H⋯O hydrogen bonds, and in the crystal, inter-molecular O-H⋯O, O-H⋯N and N-H⋯O hydrogen bonds link symmetry-related mol-ecules, forming a three-dimensional supra-molecular structure.