Redox non-innocent ligands are playing an increasingly important role in catalysis with first row transition metals due to the access it provides to two-electron redox chemistry. Indeed nature has exploited this approach for example in tyrosine based biological systems. The phenolato moiety, is well-known to provide substantial redox flexibility to metal complexes due to its accessible redox chemistry. The inclusion of phenol moieties in ligands used for oxidation catalysis was explored with a range of transition metals in recent years, however, the role that these redox non-innocent ligands play in the catalysis observed is unclear. Here we show that a µ-oxido-diiron(III) polypyridyl complex (1), based on the ligand 2-(((di(pyridin-2-yl)methyl)(pyridin-2-ylmethyl)amino)methyl)phenol undergoes drastic ligand modification within seconds of addition of H2O2 after which the modified complex becomes active in the oxidation of benzyl alcohols to aldehydes. The changes to the complex (1) over the entire course of the reaction are monitored by a combination of time-resolved UV/Vis absorption, resonance Raman and EPR spectroscopy and DFT methods and evidence for the formation of an Fe(III)-OOH species is provided.

Mechanism for the oxidation of alcohols by a µ-oxido-diiron(III)bis-phenolato polypyridyl complex

253rd National Meeting (2017)

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