Two N,N′-bis­(pyridin-4-yl)pyridine-2,6-dicarboxamide coordination compounds

The molecular structures of tetra­aqua­[N,N′-bis­(pyridin-4-yl)pyridine-2,6-dicar­boxamide]­sulfatomanganese(II) dihydrate, [Mn(SO(4))(C(17)H(13)N(5)O(2))(H(2)O)(4)]·2H(2)O or [Mn(H(2) L (1))(SO(4))(H(2)O)(4)]·2H(2)O, (I), and tetra­aqua­bis[N,N′-bis­(pyridin-4-yl)pyridine-2,6-dicar­boxamide]cadmium(II) sulfate tetra­hydrate, [Cd(C(17)H(13)N(5)O(2))(2)(H(2)O)(4)]SO(4)·4H(2)O or [Cd(H(2)O)(4)(H(2) L (1))(2)]·SO(4)·4H(2)O, (II), both contain a central metal atom in a distorted octa­hedral geometry coordinated equatorially by four oxygen atoms from water mol­ecules. In (I), the axial positions are occupied by a nitro­gen atom from H(2) L (1) and an oxygen atom from the sulfate anion, whereas in (II), the axial positions contain two nitro­gen atoms from two different H(2) L (1) ligands and the sulfate anion acts as the charge-balancing ion. π–π stacking between pyridine rings and a network of hydrogen bonds involving the water molecules and the sulfate anions play a crucial role in the mol­ecular self-assembly of the two structures.