Poly[[tetra­aqua­(μ(4)-imidazole-4,5-dicarboxyl­ato)(μ(3)-imidazole-4,5-dicarboxyl­ato)-μ(3)-sulfato-μ(2)-sulfato-cobalt(II)dierbium(III)] monohydrate]

The asymmetric unit of the title compound, {[CoEr(2)(C(5)H(2)N(2)O(4))(2)(SO(4))(2)(H(2)O)(4)]·H(2)O}(n), contains a Co(II) ion, two Er(III) ions, two imidazole-4,5-dicarboxyl­ate (imdc) ligands, two SO(4) (2−) anions, four coordinated water mol­ecules and one uncoordinated water mol­ecule. The Co(II) ion is six-coordinated by two O atoms from two coordinated water mol­ecules and two O atoms and two N atoms from two imdc ligands in a slightly distorted octa­hedral geometry. Both Er(III) ions are eight-coordinated in a bicapped trigonal–prismatic coordination geometry. One Er(III) ion is coordinated by four O atoms from two imidazole-4,5-dicarboxyl­ate ligands, three O atoms from three SO(4) (2−) anions and one water O atom; the other Er(III) ion is bonded to five O atoms from three imdc ligands, two O atoms from two SO(4) (2−) anions as well as one coordinated water mol­ecule. The coordinated metal units are connected by bridging imdc ligands and sulfate ions, generating a two-dimensional heterometallic layer. The two-dimensional layers are stacked along the b axis via N—H⋯O, O—H⋯O and C—H⋯O hydrogen-bonding inter­actions between water mol­ecules, SO(4) (2−) anions, and imdc ligands, generating a three-dimensional framework.