Mechanistic Studies into the Oxidative Addition of Co(I) Complexes: Combining Electroanalytical Techniques with...

Area of Science:

• Organometallic Chemistry
• Catalysis
• Electrochemistry

Background:

• Cobalt complexes with polydentate ligands generate carbon radicals via oxidative addition.
• Bidentate ligands offer access to Co(III)-C bonded complexes for different reactivity.
• Understanding ligand/substrate effects is crucial for optimizing cobalt-catalyzed reactions.

Purpose of the Study:

• To elucidate the kinetic and thermodynamic properties of the halogen-atom abstraction mechanism in cobalt-catalyzed reactions.
• To investigate the influence of ligand and substrate structures on elementary organometallic steps.
• To develop predictive models for reaction rates based on structural parameters.

Main Methods:

• Cyclic voltammetry combined with computational simulations.
• Analysis of kinetic isotope effects and substituent effects.
• Application of complex Hammett relationships and DFT-derived parameters.

Main Results:

• Detailed kinetic and thermodynamic data for a two-step halogen-atom abstraction mechanism were obtained.
• Individual effects of substituents on activation energy barriers and equilibrium constants were disentangled.
• Predictive statistical models were developed for reaction rates using DFT-derived parameters.

Conclusions:

• Ligand and substrate structures significantly impact the catalytic cycle of cobalt-mediated oxidative addition.
• The developed models enable prediction of reaction rates for novel ligand-substrate combinations.
• This work provides a foundation for rational catalyst design and optimization in organometallic chemistry.