The title isotypic complexes, bis-[μ-5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxylato]-κ4N1,O2,N6:O3;κ4O3:N1,O2,N6-bis-[di-aqua-manganese(II)] tetra-hydrate, [Mn2(C16H8N4O4)2(H2O)4]·4H2O, (I), and bis-[μ-5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ato]-κ4N1,O2,N6:O3;κ4O3:N1,O2,N6-bis-[di-aqua-iron(II)] tetrahydrate, [Fe2(C16H8N4O4)2(H2O)4]·4H2O, (II), are, respectively, the mangan-ese(II) a...