Exploiting the Marcus inverted region for first-row transition metal-based photoredox catalysis

Area of Science:

• Inorganic chemistry
• Photocatalysis
• Organic synthesis

Background:

• First-row transition metals are underutilized in photocatalysis due to rapid excited-state decay.
• Second- and third-row transition metals are common but less sustainable photocatalysts.

Purpose of the Study:

• To explore a novel reactivity mode for photocatalysis using earth-abundant first-row transition metals.
• To overcome the limitations of short excited-state lifetimes in first-row transition metal complexes.

Main Methods:

• Utilized cobalt polypyridyl complexes as photocatalysts.
• Exploited Marcus inverted region behavior to enhance excited-state properties.
• Investigated oxidative C(sp2)-N coupling reactions.

Main Results:

• Demonstrated productive photocatalysis with cobalt (III) complexes.
• Achieved efficient oxidative C(sp2)-N coupling of aryl amides with sterically hindered aryl boronic acids.
• Observed increased excited-state lifetimes coupled with increased excited-state energies.

Conclusions:

• Cobalt polypyridyl complexes can be designed for productive photocatalysis via Marcus inverted region behavior.
• This strategy enables the use of earth-abundant metals in photoredox catalysis.
• The findings open new avenues for designing sustainable photocatalytic systems.