01/2016

Synthetic cobalt complexes have been known to bind to molecular oxygen for over 100 years. However, upon addition of oxygen most Co(II) complexes form kinetically inert low-spin Co(III) terminal superoxides or peroxide compounds that are catalytically inactive. Active compounds can be synthetically generated through the introduction of a coreductant, but in nature redox non-innocent ligands are employed to supply the electrons when activating oxygen.

This collaborative report from the Berry, MacBeth and Lancaster groups take inspiration from nature and explore a recently reported dimeric Co(II) complex that has shown some interesting reactivities.

Using a panel of techniques, including EPR, K-edge XANES and DFT-simulations, the properties of this Cobalt system are explored and the origins of the unusual divergent electrophilic and nucleophilic reactivity of this system are deduced.

Understanding the role of the non-innocent redox ligands in the stabilization of these complexes is one of the key factors for the development of catalysts based on first row transition metals.