catena-Poly[[[diaqua-nickel(II)]-μ-pyrazine-2-carboxyl-ato-silver(I)-μ-pyrazine-2-carboxyl-ato] nitrate dihydrate].

In the polymeric complex of the title compound, {[AgNi(C(5)H(3)N(2)O(2))(2)(H(2)O)(2)]NO(3)·2H(2)O}(n), the Ag(I) ion displays an angular coordination geometry with two N atoms from pyrazine-2-carboxyl-ate ligands, and the Ni(II) ion is hexa-coordinated by two O atoms from two water mol-ecules, two O and two N atoms from pyrazine-2-carboxyl-ate ligands in a distorted octa-hedral geometry. In the crystal, the Ag(I) and Ni(II) ions lie on a mirror plane and an inversion centre, respectively. The complex chains, the nitrate ions and the uncoordinated water mol-ecules are linked together through O-H⋯O hydrogen bonds and weak Ag⋯O inter-actions [2.619 (17)-2.749 (17) Å] into a three-dimensional network.