Hydroxonium hydrate tris(2,4,6-triamino-1,3,5-triazin-1-ium) bis[bis(pyridine-2,6-dicarboxylato)manganate(II/III)] hydroxide pyridine-2,6-dicarboxylic acid solvate pentahydrate.

For charge balance in the title compound, (H(5)O(2))(C(3)H(7)N(6))(3)Mn(C(7)H(3)NO(4))(2)(OH).C(7)H(5)NO(4).5H(2)O, it is assumed that the metal atom site is disordered Mn(II)/Mn(III), probably due to partial air oxidation of the starting Mn(II) species. The formula unit of the complex contains a hydroxonium hydrate cation, H(5)O(2)(+), also known as the Zundel cation, with twofold symmetry. The O...O [2.445 (10) A] and O...H distances [1.24 (2) A] in the H(5)O(2)(+) cation indicate a strong hydrogen bond. In addition, there is a hydroxide ion that is disordered with respect to a twofold rotation axis. One of the melaminium groups and the pyridine-2,6-dicarboxylate (pydc) ligand also reside on crystallographic twofold axes. The coordination environment of the Mn ion is distorted octahedral. Three intermolecular C=O...pi interactions are observed, with distances of 3.536 (4), 3.262 (4) and 3.750 (4) A between carboxylate C=O groups and the centroids of the aromatic rings of pydc and melaminium. There are numerous O-H...O, O-H...N, N-H...O, N-H...N and C-H...O hydrogen bonds. Most of the components of the structure are organized into one plane.