A non-heme diiron complex for (electro)catalytic reduction of dioxygen: tuning the selectivity through electron-delivery
Résumé
In the Oxygen Reduction Reaction (ORR) domain, the investigation of new homogeneous catalysts is a crucial step towards the full comprehension of the key structural and/or electronic factors that control catalytic efficiency and selectivity. Herein, we report a unique non-heme diiron complex that can act as a homogeneous ORR catalyst in acetonitrile solution. This iron(II)-thiolate dinuclear complex, [FeII2(LS)(LSH)] ([Fe2SH]+) (LS2- = 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(1,1-diphenylethanethiolate)) contains a thiol group in the metal coordination sphere. [Fe2SH]+ is an efficient ORR catalyst both in the presence of a one-electron reducing agent as well as under electrochemically assisted conditions. However, its selectivity is dependent on the electron delivery pathway, in particular, the process is selective for H2O2 production under chemical conditions (up to ~95%), whereas H2O is the main product during electrocatalysis (less than ~10% H2O2). Based on computational work alongside the experimental data, a mechanistic proposal is discussed that rationalizes the selective and tunable reduction of dioxygen.
Domaines
Catalyse
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