In the presence of cobalt (nickel) acetate, a chiral tetrahedral intermediate ligand of (S)-(C5NH4)(2)C(OH)(C4NH7CO2H) was first formed from the nucleophilic addition of (L)-proline as a secondary amine to ketone (di-2-pyridyl ketone). Based on the ligand synthesized in situ, two chiral tetranuclear isomorphous complexes 1 and 2 with the formula {Na[M4L3(OAc)(3)](ClO4)(1.5)(H2O)(1.5)}(ClO4)(OH)(0.5)center dot 3H(2)O (M = Co, Ni) have been achieved. The Co-4 cluster (1) behaves as a ferromagnet.