Formation and characterization of mononuclear and dinuclear manganese oxide-dioxygen complexes in solid argon

A manganese atom reacts with dioxygen to form the previously characterized MnO 2 molecule in solid argon under UV-visible light irradiation. Subsequent sample annealing allows the dioxygen molecules to diffuse and to react with MnO 2 to give the (eta (2)-O 2)MnO 2 complex, which is characterized to be a side-on bonded peroxo manganese dioxide complex. The manganese tetraoxide MnO 4, which was predicted to be less stable than the (eta (2)-O 2)MnO 2 isomer, was not observed. However, the (eta (2)-O 2)MnO 2 complex reacts with another weakly coordinated dioxygen to give the (eta (2)-O 2)MnO 4 complex via visible light irradiation, in which the manganese tetraoxide is coordinated and stabilized by a side-on bonded O 2 molecule. Manganese dimer reacts with dioxygen to form the cyclic Mn(mu-O) 2Mn cluster spontaneously upon annealing, which further reacts with dioxygen to give the (eta (2)-O 2) 2Mn(mu-O) 2Mn cluster, a side-on bonded disuperoxide complex with a planar D 2 h structure.