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)Mn III 2 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 Mn III-peroxo complex at a low concentration (≤ 1 mM) and a bis(μ-oxo)MnIII 2 complex at a high concentration (≥30mM)). 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 demon-strated 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)MnIII 2 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. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA.