Bis(2,4,6-triamino-1,3,5-triazin-1-ium) hexa­aqua­cobalt(II) bis­[bis­(pyridine-2,6-dicarboxyl­ato)cobaltate(II)] tetra­hydrate

The title compound, (C(3)H(7)N(6))(2)[Co(H(2)O)(6)][Co(C(7)H(3)NO(4))(2)](2)·4H(2)O, or (tataH)(2)[Co(H(2)O)(6)][Co(pydc)(2)](2)·4H(2)O (where tata is 2,4,6-triamino-1,3,5-triazine and pydc is pyridine-2,6-dicarboxylic acid), was obtained by reaction of Co(NO(3))(2)·6H(2)O with the proton-transfer compound (tataH)(2)(pydc) in aqueous solution. The [Co(pydc)(2)](2−) anion is a six-coordinate Co(II) complex with a distorted octa­hedral coordination geometry. The structure also contains hexa­aqua­cobalt(II) cations (site symmetry [Image: see text]), (tataH)(+) cations and uncoordinated water mol­ecules. The two(pydc)(2−) ligands in each [Co(pydc)(2)](2−) anion are almost perpendicular to each other [dihedral angle between their mean planes = 82.3 (1)°]. There is extensive O—H⋯O, N—H⋯N, O—H⋯N and C—H⋯O hydrogen bonding in the structure, as well as π–π stacking between (pydc)(2−) ligands with an inter­planar distance of 3.484 (15) Å.