A long-standing challenge is to understand the mechanism of dioxygen (O2) activation by natural and synthetic oxidation catalysts. Presented here is the discovery of an unprecedented autocatalytic O2 activation by a chromium(III) oxidation catalyst via the formation of a CrIV �-oxo dimer. Metal �-oxo dimers are well-known nuisance formed during catalysis from Mn+ and M=O(n+2)+ species which inhibit catalysis; however, definitive structural and electronic characterization is decidely absent. We introduce the first EPR and X-ray crystallographically characterized CrIV �-oxo dimer. Finally, the trianionic OCO3- pincer CrIV �-oxo dimer displays higher reactivity towards O2 activation than original CrIII complex yielding its unique autocatalytic mechanism.

Unprecedented autocatalytic O2 activation by a trianionic OCO3- pincer chromium(III) oxidation catalyst and the role of μ-oxo dimer (CrIV-O-CrIV) intermediate

243rd National Meeting (2012)

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