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

Abstract

Mononuclear MnIII–peroxo and dinuclear bis(μ‐oxo)MnIII2 complexes that bear a common macrocyclic ligand were synthesized by controlling the concentration of the starting MnII complex in the reaction of H2O2 (i.e., a MnIII–peroxo complex at a low concentration (≤1 mM) and a bis(μ‐oxo)MnIII2 complex at a high concentration (≥30 mM)). These intermediates were successfully characterized by various physicochemical methods such as UV–visible spectroscopy, ESI‐MS, resonance Raman, and X‐ray analysis. The structural and spectroscopic characterization combined with density functional theory (DFT) calculations demonstrated unambiguously that the peroxo ligand is bound in a side‐on fashion in the MnIII–peroxo complex and the Mn2O2 diamond core is in the bis(μ‐oxo)MnIII2 complex. The reactivity of these intermediates was investigated in electrophilic and nucleophilic reactions, in which only the MnIII–peroxo complex showed a nucleophilic reactivity in the deformylation of aldehydes.