Tetra-kis(2,4,6-triamino-1,3,5-triazin-1-ium) tris-(pyridine-2,6-dicarboxyl-ato)calcate(II) hexa-hydrate.

The title compound, (C(3)H(7)N(6))(4)[Ca(C(7)H(3)NO(4))(3)]·6H(2)O or (tataH)(4)[Ca(pydc)(3)]·6H(2)O (where tata is 2,4,6-triamino-1,3,5-triazine and pydcH(2) is pyridine-2,6-dicarboxylic acid), was obtained by reaction of Ca(NO(3))(2)·4H(2)O with the proton-transfer compound (tataH)(2)(pydc) in aqueous solution. The Ca(pydc)(3) anion has twofold crystallographic symmetry. It is a nine-coordinate Ca(II) complex with a distorted tricapped trigonal-prismatic coordination geometry. The structure also contains four tataH(+) cations and six uncoordinated water mol-ecules. There are extensive O-H⋯O, O-H⋯N, N-H⋯O, N-H⋯N and C-H⋯O hydrogen bonds in the crystal structure.