A novel one-dimensional CoII coordination polymer: catena-poly[[hexaaquacobalt(II)] [[diaquabis(sulfato-κO)cobalt(II)]-μ-4,4′-bipyridine-κ2N:N′] [[triaqua(sulfato-κO)cobalt(II)]-μ-4,4′-bipyridine-κ2N:N′]]

The title compound, {[Co(H2O)6][Co(SO4)(C10H8N2)(H2O)3][Co(SO4)2(C10H8N2)(H2O)2]}n, contains three crystallographically unique CoII centres, all of which are in six-coordinated environments. One CoII centre is coordinated by two bridging 4,4'-bipyridine (4,4'-bipy) ligands, one sulfate ion and three aqua ligands. The second CoII centre is surrounded by two N atoms of two 4,4'-bipy ligands and four O atoms, i.e. two O atoms from two monodentate sulfate ions and two from water molecules. The third CoII centre forms part of a hexaaquacobalt(II) ion. In the crystal structure, there are two different one-dimensional chains, one being anionic and the other neutral, and adjacent chains are arranged in a cross-like fashion around the mid-point of the 4,4'-bipy ligands. The structure features O-H center dot center dot center dot O hydrogen-bonding interactions between sulfate anions and water molecules, resulting in a three-dimensional supramolecular network.