C─C Bond Formation via Reductive Elimination at Rare Earth Centers

Area of Science:

• Organometallic Chemistry
• Rare Earth Chemistry
• Synthetic Organic Chemistry

Background:

• Reductive elimination is vital for chemical bond formation in transition metal catalysis.
• Rare earth (RE) elements were traditionally excluded from promoting reductive elimination due to their electronic properties.
• This limitation restricted the application of RE complexes in synthetic chemistry.

Purpose of the Study:

• To investigate the reactivity of rare earth complexes in reductive elimination reactions.
• To demonstrate that rare earth centers can indeed promote reductive elimination.
• To expand the synthetic applications of rare earth complexes.

Main Methods:

• Reactions of β-diketiminate-supported dialkyl RE(III) complexes with azobenzene.
• Isolation and structural identification of key intermediates, including a lutetium complex.
• Computational studies to elucidate the reaction mechanism.

Main Results:

• Formation of new RE(III) complexes and a C-C cross-coupled product via reductive elimination.
• Isolation and characterization of a key intermediate demonstrating ortho-H deprotonation.
• Computational analysis revealed the mechanism involving azobenzene π*-orbitals as electron acceptors.

Conclusions:

• Rare earth complexes can promote reductive elimination, challenging previous assumptions.
• The N═N π*-orbitals of azobenzene facilitate the electron transfer for reductive elimination.
• This study opens new avenues for utilizing rare earth elements in synthetic transformations.