catena-Poly[[tetraaquacopper(II)]-μ-pyrazine-2-carboxamide-κ3N4:N1,O-[bis(sulfato-κO)copper(II)]-μ-pyrazine-2-carboxamide-κ3N1,O:N4]

In the crystal of the title polymeric compound, [Cu(2)(SO(4))(2)(C(5)H(5)N(3)O)(2)(H(2)O)(4)](n), two independent Cu(II) atoms are located on individual inversion centers. One Cu(II) atom is coordinated by four water mol-ecules and two pyrazine-2-carboxamide ligands in a distorted O(4)N(2) octa-hedral geometry; the other is N,O-chelated by two pyrazine-2-carboxamide ligands and further coordinated by two sulfate anions in a distorted O(4)N(2) octa-hedral geometry. The pyrazine-2-carboxamide ligands bridge the Cu(II) atoms to form a polymeric chain running along [110]. The crystal structure features N-H⋯O, O-H⋯O and weak C-H⋯O hydrogen bonds.