Iron Olefin Metathesis: Unlocking Reactivity and Mechanistic Insights

Area of Science:

• Organometallic Chemistry
• Catalysis
• Green Chemistry

Background:

• Ruthenium catalysts dominate olefin metathesis, but iron offers a more abundant and less toxic alternative.
• Iron carbene complexes often undergo undesired cyclopropanation, hindering their metathesis applications.
• Understanding iron's reaction pathways is crucial for unlocking its catalytic potential.

Purpose of the Study:

• To investigate the olefin metathesis capabilities of iron complexes with strained olefins.
• To elucidate the reaction mechanism of iron carbene complexes in metathesis.
• To provide evidence supporting the Chauvin mechanism for iron-catalyzed olefin metathesis.

Main Methods:

• Synthesis and characterization of iron carbene complexes, specifically [{PC(sp2)P}Fe(L)(N2)].
• Reaction of the iron complex with strained olefins like norbornadiene derivatives.
• Isolation and structural characterization of reaction intermediates, including metallacyclobutanes.

Main Results:

• Iron complexes successfully yielded metathesis-related products with strained olefins.
• A structurally characterized metallacyclobutane intermediate was isolated during reactions with norbornadiene derivatives.
• The formation of a ring-opened iron alkylidene was observed.

Conclusions:

• Iron complexes can effectively catalyze olefin metathesis reactions.
• The isolated metallacyclobutane intermediate provides strong evidence that iron complexes follow the Chauvin olefin metathesis mechanism.
• These findings pave the way for developing more efficient and sustainable iron-based metathesis catalysts.