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) center dot 4H(2)O, or (tataH)(2)[Co(H(2)O)(6)][Co(pydc)(2)](2)center dot 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 center dot 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 (1) over bar), (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) degrees]. There is extensive O-H center dot center dot center dot O, N-H center dot center dot center dot N, O-H center dot center dot center dot N and C-H center dot center dot center dot O hydrogen bonding in the structure, as well as pi-pi stacking between (pydc)(2)-ligands with an interplanar distance of 3.484 (15) angstrom.