Non-Heme Tri-Iron(II) Complex as a Precursor for Dioxygen Activation and Oxygen Reduction Reaction Catalysis

Area of Science:

• Bioinorganic Chemistry
• Catalysis
• Electrochemistry

Background:

• Nonheme iron complexes are promising for bioinspired oxidation and oxygenation reactions.
• Their potential in the oxygen reduction reaction (ORR) remains underexplored.

Purpose of the Study:

• To present a novel nonheme iron system with O2 activation and ORR catalytic selectivity towards H2O generation.
• To characterize the iron complex and its reactivity with O2 and under ORR conditions.

Main Methods:

• Synthesis and characterization of a triiron(II) complex [FeII L]3(BF4)3, where L- is a thiolate-containing N3S donor ligand.
• Spectroscopic and structural analysis in solid state and solution.
• Electrocatalytic studies of the oxygen reduction reaction (ORR) using the iron complex in the presence of a proton source and reducing agent.

Main Results:

• The iron complex dissociates in solution to a mononuclear species [FeL(MeCN)]+.
• [FeL(MeCN)]+ reacts with O2 to form μ-oxo diiron(III) and subsequently an {Fe4OF5}3+ core.
• The system catalyzes ORR with exclusive production of H2O under chemical conditions.

Conclusions:

• This work presents a rare example of a nonheme iron catalyst with significant ORR activity and selectivity for water production.
• The findings contribute to the understanding of nonheme iron complexes in oxygen activation and electrocatalysis.
• This system offers a new perspective for developing efficient and selective ORR catalysts.