O2 reduction by a functional heme/nonheme bis-iron NOR model complex.

Area of Science:

• Biomimetic chemistry
• Catalysis
• Spectroscopy

Background:

• Understanding oxygen reduction mechanisms is crucial for catalysis.
• Functional models of non-heme oxygenases (NOR) are key to studying these processes.

Purpose of the Study:

• Investigate the oxygen (O2) reactivity of a functional NOR model.
• Elucidate the reaction pathway and intermediates involved in O2 reduction.

Main Methods:

• Electrochemical measurements using interdigitated electrodes.
• Spectroscopic characterization, including resonance Raman spectroscopy.
• Trapping intermediates at cryogenic temperatures under single-turnover conditions.

Main Results:

• The NOR model exhibits high selectivity for four-electron (4e) O2 reduction.
• Minimal production of partially reduced oxygen species (PROS) was observed.
• A trans heme/nonheme bis-ferryl intermediate was identified, capable of oxygenating substrates.

Conclusions:

• The functional NOR model effectively mimics key aspects of enzymatic O2 activation.
• The identified bis-ferryl intermediate is a crucial species in the catalytic cycle.
• This research provides insights into the mechanisms of oxygen reduction catalysis.