Electrostatic and Charge-Induced Methane Activation by a Concerted Double C-H Bond Insertion

Area of Science:

• Organometallic Chemistry
• Computational Chemistry
• Catalysis

Background:

• Methane (CH4) conversion is crucial for energy and chemical production.
• Understanding metal-carbide reactivity is key to developing new catalytic processes.
• Coinage metal complexes offer unique electronic properties for chemical transformations.

Purpose of the Study:

• To investigate the reaction mechanism between cationic copper carbide, [Cu-C]+, and methane.
• To elucidate the simultaneous activation of two C-H bonds in methane.
• To compare the reactivity of [Cu-C]+ with cationic gold carbide, [Au-C]+.

Main Methods:

• High-level quantum chemical calculations.
• Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) in a highly diluted gas phase.
• Mechanistic analysis of reaction pathways.

Main Results:

• Identified a unique, simultaneous activation of two C-H bonds in methane by [Cu-C]+.
• Observed a contrasting stepwise activation mechanism for the analogous [Au-C]+ complex.
• Provided a theoretical explanation for the distinct mechanistic differences between copper and gold complexes.
• Demonstrated that the [Cu-C]+/CH4 reaction can be modeled by a carbon atom reacting with methane under an external electric field.

Conclusions:

• Cationic copper carbide exhibits a novel simultaneous C-H bond activation pathway for methane.
• The electronic structure of coinage metals dictates distinct reaction mechanisms in methane activation.
• This study provides fundamental insights into C-H bond activation and methane functionalization relevant to catalysis.