Manganese-dependent dioxygen activation under mild conditions is common to a variety of biological enzymes including lypoxygenase and homoprotocatechuate 2,3-dioxygenase. In spite of these enzymatic examples, biomimetic manganese model complexes that can activate dioxygen are rare, and designing such compounds continues to be a challenging task. Furthermore, aerobic substrate oxidation using manganese catalysts is of great significance in developing green, inexpensive metal oxidants for industrial applications. The main focus of this work is in designing novel bio-inspired Mn(II) species that are capable of activating dioxygen under ambient conditions, and using these compounds to gain insight into O2 activation mechanisms and substrate oxidation pathways using O2 as the oxidant. We report a series of monomeric Mn(II) complexes supported by anionic ligands with axial amido coordination that activate dioxygen in solution to generate mid-valent MnIII–OR compounds in quantitative yields. These Mn(III) complexes are extremely stable, and exhibit unique kinetic properties in the oxidation of weak O–H bond substrates. The kinetic and thermodynamic properties of these mid-valent oxidants and the prospects of this chemistry to be utilized in devising environmentally friendly O–H activation catalysts are discussed.

Dioxygen activation under ambient conditions using bio-inspired manganese(II) complexes to generate mid-valent oxidants for catalytic O–H bond oxidations

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.