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(SO4)(C17H13N5O2)(H2O)(4)]center dot 2H(2)O or [Mn(H2L1)(SO4)(H2O)(4)]center dot 2H(2)O, (I), and tetraaquabis[N, N'-bis(pyridin-4-yl)pyridine-2,6-dicarboxamide]cadmium(II) sulfate tetrahydrate, [Cd(C17H13N5O2)(2)(H2O)(4)]SO4 center dot 4H(2)O or [Cd(H2O)(4)(H2L1)(2)]center dot SO4 center dot 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 H2L1 and an oxygen atom from the sulfate anion, whereas in (II), the axial positions contain two nitrogen atoms from two different H2L1 ligands and the sulfate anion acts as the charge-balancing ion. pi-pi 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.