Earth-Abundant Metal Catalysis Enabled by Counterion Activation

Area of Science:

• Catalysis
• Organometallic Chemistry
• Green Chemistry

Background:

• Developing efficient catalytic systems using earth-abundant metals is crucial for sustainable chemistry.
• Precatalyst activation strategies are essential for controlling reactivity and selectivity in metal-catalyzed reactions.
• Alkene hydroboration is a valuable transformation for synthesizing organoboron compounds.

Purpose of the Study:

• To develop a novel precatalyst activation strategy for earth-abundant metal catalysis.
• To demonstrate the utility of this strategy in alkene hydroboration reactions.
• To investigate the catalytic performance of iron and cobalt complexes activated through counterion dissociation.

Main Methods:

• Developed a precatalyst activation strategy involving counterion dissociation.
• Utilized commercially available iron and cobalt tetrafluoroborate salts.
• Investigated the hydroboration of a range of aryl and alkyl alkenes with pinacol borane.
• Employed three distinct ligands to modulate catalyst activity.

Main Results:

• Successfully activated iron and cobalt precatalysts through endogenous counterion dissociation.
• Achieved efficient alkene hydroboration with good functional group tolerance (12 substrates for Fe, 13 for Co).
• Identified fluoride as the key species generated from counterion dissociation, which activates the precatalyst via reaction with pinacol borane.

Conclusions:

• Established a facile precatalyst activation strategy for earth-abundant metal catalysis.
• Demonstrated the broad applicability and functional group tolerance of iron and cobalt catalysts in alkene hydroboration.
• Highlighted the critical role of counterion dissociation and fluoride generation in enabling catalytic activity.