Operando Analysis of Nickel Catalyst Speciation in Reductive Biaryl Synthesis Using Thin Layer Electrochemistry and a...

Area of Science:

• Organometallic Chemistry
• Catalysis
• Analytical Chemistry

Background:

• Nickel-catalyzed cross-electrophile coupling reactions are vital in organic synthesis.
• Understanding nickel speciation is crucial for optimizing these reactions.
• Existing analytical methods lack the capability for operando monitoring.

Purpose of the Study:

• To develop and demonstrate an analytical method for operando monitoring of nickel speciation.
• To gain insights into the temporal evolution of nickel catalysts during reactions.
• To identify and quantify nickel intermediates in catalytic cycles.

Main Methods:

• Integration of a thin-layer electrode (TLE) platform with microelectrode (ME) voltammetry.
• Operando monitoring of nickel species during the reductive homocoupling of aryl halides.
• Identification and quantitation of Ni-based intermediates.

Main Results:

• Revealed previously unrecognized patterns in nickel speciation.
• Observed accumulation of mono- and bisaryl Ni^II species.
• Demonstrated variation in Ni⁰/Ni^II oxidation states with ligand concentration.

Conclusions:

• The developed TLE-ME voltammetry technique is effective for operando monitoring of nickel speciation.
• The findings provide a deeper understanding of nickel catalyst behavior in cross-electrophile coupling.
• This methodology can be adapted for studying other metal-catalyzed reactions.