EPR monitoring of in-situ catalytic oxidative assembly of MnIII-MnIV dimers via monomeric MnIV = O

The oxidative evolution of Mn-catalysts via transient high-oxidation state, Mn-III or Mn-IV, intermediates is often assumed in literature, however a direct in-situ evidence for cycling between high-oxidation states of Mn is scarce. Moreover, the involvement of dimeric [Mn-IV-Mn-III] transients, has been invoked as active catalytic intermediate. Herein, we present a study by Dual-Mode EPR and Low-Temperature UV-Vis spectroscopies, on the monitoring of cycling of Mn-II, Mn-III, Mn-IV states formed by a MnL catalytic system. It is found that, while starting as monomeric, the MnL catalyst, is capable to form in-situ stable oxo-bridged [Mn-Mn] dimers which are catalytically/redox-active.

Automated summary

The study demonstrates the cycling of Mn-II, Mn-III, and Mn-IV states formed by a MnL catalytic system, with the ability of the MnL catalyst to form stable oxo-bridged [Mn-Mn] dimers in-situ, exhibiting catalytic and redox activity.