Reactivity of bio-inspired Cu(II) (N2/Py2) complexes with peroxide at room temperature

Area of Science:

• Coordination Chemistry
• Catalysis
• Oxidation Reactions

Background:

• Developing earth-abundant metal catalysts for substrate oxidation under mild conditions remains a significant challenge in chemistry.
• Copper complexes are attractive due to their abundance and versatile redox properties.

Purpose of the Study:

• To investigate the reactivity of mononuclear copper complexes with hydrogen peroxide (H2O2) as an oxidant.
• To explore the potential for these complexes to mediate substrate oxidation and identify reactive intermediates.

Main Methods:

• Synthesis and characterization of two mononuclear copper complexes.
• Reaction of complexes with H2O2, including studies with and without substrate.
• Spectroscopic analysis (e.g., EPR, UV-Vis) to determine complex structures and oxidation states.
• Computational studies to elucidate reaction mechanisms.

Main Results:

• Both copper complexes underwent ligand oxidation upon reaction with H2O2, forming mononuclear Cu(II) products.
• In the presence of a substrate, ligand oxidation was intercepted, leading to preferential substrate oxidation.
• Spectroscopic and computational data suggest a copper-oxyl intermediate is responsible for both ligand and substrate oxidation.

Conclusions:

• This work presents the first copper-mediated system capable of ligand oxidation, oxo-transfer, and external hydrocarbon oxidation under stoichiometric conditions.
• The findings offer a new pathway for developing efficient and selective oxidation catalysts based on earth-abundant metals.