Reactivity of diiron(II) complexes with molecular oxygen

A variety of dinuclcating ligands (L) have been developed for preparation of diiron-dioxygen complexes, where L represents N6O donor Ligands with a phenolate or alkoxide bridging group. They form five-coordinate diiron(II,II) complexes with an exogenous bridging carboxylate, [Fe-2(L)(RCOO)](2+), which react with O-2 to give mu-peroxo species. Their oxygen affinity and thermal stability of mu-peroxo species toward the irreversible oxidation have been found to be highly dependent on the electron donor ability of coordinating atoms, steric bulkiness and the stereochemistry of the bridging skeleton of' the dinuclcating ligands.