Poly[[diaqua­bis­(μ2-4,4′-bipyrid­yl)cobalt(II)] dinitrate tetra­hydrate]

The title compound, {[Co(C10H8N2)2(H2O)2](NO3)2·4H2O}n, (C10H8N2 = 4,4′-bipyridine = 4,4′-bpy) is a layered coordination polymer built up from a cationic square grid extending in (101) enclosing uncoordinating nitrate ions and water mol­ecules. The CoII ion has site symmetry 2 and one of the 4,4′-bpy ligands is generated by twofold symmetry [two N atoms and two C atoms lie on the rotation axis and the dihedral angle between the pyridine rings is 45.66 (5)°]. The other 4,4′-bpy ligand is generated by a crystallographic inversion center. The CoII ion exhibits a slightly distorted octa­hedral coordination geometry defined by two O atoms of two coordinating water mol­ecules and four N atoms from four bridging 4,4′-bpy ligands. The structure is consolidated by O—H⋯O, C—H⋯O and C—H⋯N hydrogen bonds.