Reductive NO Coupling at Dicopper Center via a [Cu₂(NO)₂]²⁺ Diamond-Core Intermediate.

Area of Science:

• Inorganic Chemistry
• Bioinorganic Chemistry
• Coordination Chemistry

Background:

• Nitric oxide (NO) plays crucial roles in biological systems and industrial processes.
• Understanding the reactivity of metal-nitrosyl complexes is key to controlling NO transformations.
• Dicopper complexes are involved in various biological redox processes.

Purpose of the Study:

• To synthesize and characterize a dicopper dinitrosyl complex.
• To investigate the reversible release of NO from this complex.
• To elucidate the mechanism of reaction between the dicopper dinitrosyl complex and NO, leading to N2O formation.

Main Methods:

• Synthesis of a dicopper(I,I) complex.
• Treatment with excess nitric oxide (NO).
• Resonance Raman spectroscopy for structural characterization.
• Kinetic studies to determine reaction mechanisms.

Main Results:

• Formation of a dicopper dinitrosyl [Cu2(NO)2]2+ complex with a symmetric diamond-core structure and bis-μ-NO ligands.
• Reversible release of two equivalents of NO in 90% yield.
• Reaction with an additional NO equivalent yields N2O and a dicopper nitrosyl oxo species [Cu2(NO)O]2+.
• The conversion to the oxo species proceeds via a rate-limiting reaction with NO, distinct from diFe-mediated pathways.

Conclusions:

• The synthesized dicopper dinitrosyl complex exhibits unique NO binding and release capabilities.
• A novel reaction pathway for NO conversion to N2O mediated by dicopper complexes has been identified.
• This dicopper-mediated mechanism differs significantly from known iron-based systems, offering new insights into metal-NO chemistry.