Thermally stable manganese(III) peroxido complexes with hindered N3 tripodal ligands: Structures and their physicochemical properties

Mononuclear manganese(III) peroxido complexes are candidates for the reaction intermediates in manganese containing proteins, such as manganese superoxide dismutase (Mn-SOD) etc. In this study, manganese(III) peroxido complexes [Mn(O-2)(L3)] and [Mn(O-2)(L10)] ligated by anionic N3 type ligands with sterically hindered substituents, hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl)borate (L3(-)) and hydrotris(3-adamantyl-5-isopropyl-1-pyrazolyl)borate (L10(-)), respectively, were structurally characterized. These complexes are the first examples of structurally characterized five-coordinate manganese(III) peroxido complexes. Their characteristic nu(O-O) and nu(Mn-O) stretchings were determined by using (H2O2)-O-18 for the first time. Theoretical calculations were performed to obtain further insight into their structural parameters. The decomposed products were obtained as [{Mn-III(mu-O)(L3)}(2)Mn-IV] and [Mn-III(OH){L10(O)}] from [Mn(O-2)(L3)] and [Mn(O-2)(L10)], respectively.