catena-Poly[diammonium [diaqua­bis(pyridine-2,4-dicarboxyl­ato-κ(2) N,O (2))cuprate(II)] [[diaqua­copper(II)]-μ-pyridine-2,4-dicarboxyl­ato-κ(3) N,O (2):O (2′)-[tetra­aqua­cadmium(II)]-μ-pyridine-2,4-dicarboxyl­ato-κ(3) O (2):N,O (2′)] hexa­hydrate]

The title mixed-metal complex, {(NH(4))(2)[Cu(C(7)H(3)NO(4))(2)(H(2)O)(2)][CdCu(C(7)H(3)NO(4))(2)(H(2)O)(6)]·6H(2)O}(n), contains one octa­hedrally coordinated Cd(II) center and two octa­hedrally coordinated Cu(II) centers, each lying on an inversion center. The two Cu(II) atoms are each coordinated by two O atoms and two N atoms from two 2,4-pydc (2,4-H(2)pydc = pyridine-2,4-dicarboxylic acid) ligands in the equatorial plane and two water mol­ecules at the axial sites, thus producing two crystallographically independent [Cu(2,4-pydc)(2)(H(2)O)(2)](2−) metalloligands. One metalloligand exists as a discrete anion and the other connects the Cd(H(2)O)(4) units, forming a neutral chain. O—H⋯O and N—H⋯O hydrogen bonds connects the polymeric chains, complex anions, ammonium cations and uncoordinated water mol­ecules into a three-dimensional supra­molecular network.