catena-Poly[[[diaquacobalt(II)]-μ-(3,5-dinitro-2-oxidobenzoato)-κ3O1,O2:O1′-[tetraaquacobalt(II)]-μ-(3,5-dinitro-2-oxidobenzoato)-κ3O1:O1′,O2] dihydrate]

In polymeric title compound, {[Co-2(C7H2N2O7)(2)(H2O)(6)]center dot 2H(2)O}(n), obtained from the reaction of 3,5-dinitrosalicylic acid with cobalt(II) acetate, both Co-II atoms are located on inversion centres and exhibit a distorted octahedral coordination geometry. The coordination sphere about one Co-II atom comprises four O-atom donors from two bidentate chelate (O-phenolate and O-carboxyl) and bridging dianionic ligands and two water molecules [Co-O range = 2.0249 (11)-2.1386 (14) angstrom], while that about the second Co-II atom has four water molecules and two bridging carboxylate O-donor atoms [Co-O range = 2.0690 (14)-2.1364 (11) angstrom]. The coordinated water molecules as well as the water molecules of solvation give O-H center dot center dot center dot O water-water and water-carboxyl hydrogen-bonding interactions in the three-dimensional framework structure.