Poly[octa-μ-aqua-tetra-aqua-bis(μ-5-sul-fon-atobenzene-1,3-dicarboxyl-ato)cobalt(II)tetra-sodium].

The title compound, [CoNa(4)(C(8)H(3)O(7)S)(2)(H(2)O)(12)](n), is a three-dimensional coordination polymer bridged by sulfoisophthalate trianions and water mol-ecules. The Co(II) atom, located on an inversion centre, is coordinated by two carboxyl-ate groups of the sulfoisophthalate trianions and by four water mol-ecules in a distorted CoO(6) octa-hedral geometry. Two independent Na(I) atoms also have a distorted octa-hedral coordination geometry formed by water, carboxyl-ate O and sulfonate O atoms. An extensive O-H⋯O and C-H⋯O hydrogen-bonding network is present in the crystal structure, as well as weak π-π stacking [centroid-centroid distance = 3.9553†(11)†à ].