[μ-6,9-Bis(carboxylatomethyl)-3,12-bis(car­boxymethyl)-3,6,9,12-tetraaza­tetradecanedioato]bis­[aqua­cobalt(II)] tetra­hydrate

The binuclear title complex, [Co₂(C₁₈H₂₆N₄O₁₂)(H₂O)₂]·4H₂O, lies about a centre of inversion, the Co^II atom being coordinated in a distorted octa­hedral arrangement defined by one water mol­ecule and N₂O₃ donors derived from one end of a 6,9-bis(carboxylatomethyl)-3,12-bis(car­boxy­methyl)-3,6,9,12-tetraaza­tetradecanedioate (H₂TTHA⁴⁻) tetra­anion. In the crystal, numerous O—H...O hydrogen bonds link the mol­ecules into a three-dimensional network.