Synthesis and crystal structure of catena-poly[[hexa­aqua{μ(3)-2-[bis­(carboxyl­atometh­yl)amino]­terephthalato}dicobalt(II)] penta­hydrate] containing water tapes and penta­mers

The title coordination polymer, {[Co(2)(C(12)H(7)NO(8))(H(2)O)(6)]·5H(2)O}(n), was crystallized at room temperature from an aqueous solution of 2-aminodi­acetic terephthalic acid (H(4)adtp) and cobalt(II) nitrate. The asymmetric unit consists of one adtp(4−) ligand, one and two half Co(II) ions, six water ligands coordinated to Co(II) ions and five uncoordinated water mol­ecules. Two of the cobalt cations lie on centres of inversion and are coordinated in octa­hedral O(2)(OH(2))(4) environments, whereas the other adopts a slightly distorted octa­hedral NO(3)(OH(2))(2) environment. The crystal structure contains parallel stacked, one-dimensional zigzag chains, {[Co(2)(C(12)H(7)NO(8))(H(2)O)(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.