Gravar-mail: Bis[4-(4-pyridyl)pyridinium] μ-4,4′-bipyridine-bis­[tetra­aqua­(4,4′-bipyridine)manganese(II)] bis­(5-sulfonatobenzene-1,3-dicarboxyl­ate) 4,4′-bipyridine solvate penta­deca­hydrate