Synthesis and crystal structure of catena-poly[[hexa-aqua{μ3-2-[bis-(carboxyl-atometh-yl)amino]-terephthalato}dicobalt(II)] penta-hydrate] containing water tapes and penta-mers.

The title coordination polymer, {[Co2(C12H7NO8)(H2O)6]·5H2O}n, was crystallized at room temperature from an aqueous solution of 2-aminodi­acetic terephthalic acid (H4adtp) and cobalt(II) nitrate. The asymmetric unit consists of one adtp4− ligand, one and two half CoII ions, six water ligands coordinated to CoII ions and five uncoordinated water mol­ecules. Two of the cobalt cations lie on centres of inversion and are coordinated in octa­hedral O2(OH2)4 environments, whereas the other adopts a slightly distorted octa­hedral NO3(OH2)2 environment. The crystal structure contains parallel stacked, one-dimensional zigzag chains, {[Co2(C12H7NO8)(H2O)6]}n, which assemble into a three-dimensional supra­molecular architecture via networks of hydrogen bonds involving the coordinated and free water mol­ecules. One-dimensional `water tapes' are formed, containing alternating six-membered and twelve-membered rings of water mol­ecules, together with water penta­mers, in which a central uncoordinated water mol­ecule is hydrogen bonded to two coordinated and two free water mol­ecules in a tetra­hedral arrangement.