[μ-6,9-Bis(carboxylatomethyl)-3,12-bis(car-boxymethyl)-3,6,9,12-tetraaza-tetradecanedioato]bis-[aqua-cobalt(II)] tetra-hydrate.

The binuclear title complex, [Co(2)(C(18)H(26)N(4)O(12))(H(2)O)(2)]·4H(2)O, lies about a centre of inversion, the Co(II) atom being coordinated in a distorted octa-hedral arrangement defined by one water mol-ecule and N(2)O(3) donors derived from one end of a 6,9-bis(carboxylatomethyl)-3,12-bis(car-boxy-methyl)-3,6,9,12-tetraaza-tetradecanedioate (H(2)TTHA(4-)) tetra-anion. In the crystal, numerous O-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.