Mononuclear Manganese–Peroxo and Bis ACHTUNGTRENNUNG(m-oxo)dimanganese Complexes Bearing a Common N-Methylated Macrocyclic Ligand

Metal–oxygen adducts (Mx Ox, x=1 or 2), such as metal– superoxo, –peroxo, and –oxo species, are key intermediates often detected in the catalytic cycles of dioxygen activation by metalloenzymes. In biomimetic and synthetic chemistry, numerous Mx Ox complexes have been prepared and characterized with various physicochemical methods as structural and functional models of enzymes. Among the Mx O2 adducts, manganese–oxygen species (Mnx O2) have attracted much attention, since the intermediates have been invoked as reactive species in Mn-containing enzymes such as catalase, superoxide dismutase, and the oxygen-evolving complex (OEC) of photosystem II. Recent advances in synthetic model chemistry have provided fundamental information on the structures and chemical properties of Mnx O2 species. For example, a number of bis ACHTUNGTRENNUNG(m-oxo)Mn2 complexes have been synthesized and investigated in water exchange, oxidation reaction, and redox chemistry to understand the OEC. We have also reported the synthesis, characterization, and reactivity of Mn–peroxo complexes that bear N-methylated cyclam ligands, [Mn ACHTUNGTRENNUNG(13TMC)(O2)] + and [Mn ACHTUNGTRENNUNG(14-TMC)(O2)] + (Scheme 1) and