Nickel Fluorocarbene Metathesis with Fluoroalkenes

Area of Science:

• Organometallic Chemistry
• Fluorine Chemistry
• Catalysis

Background:

• Alkene metathesis is a powerful synthetic tool, but its application to directly fluorinated alkenes remains challenging.
• The field of fluoro-organic chemistry is rapidly expanding, necessitating new methods for incorporating fluorine into organic molecules.

Purpose of the Study:

• To develop a novel catalytic system for alkene metathesis reactions involving fluorinated alkenes.
• To investigate the reaction mechanism and explore the scope of products obtainable.

Main Methods:

• Synthesis and characterization of a nickel tris(phosphite) fluoro(trifluoromethyl)carbene complex.
• Reactions of the nickel complex with tetrafluoroethylene (TFE) and vinylidene fluoride (VDF).
• Density Functional Theory (DFT) calculations to elucidate reaction pathways and intermediates.

Main Results:

• The nickel carbene complex successfully mediated metathesis reactions with TFE and VDF, yielding perfluorocarbene and metallacyclobutane products.
• Reactions with trifluoroethylene produced metathesis products but formed metallacyclopropanes and fluoronickel alkenyl species, suggesting alternative pathways.
• Experimental and computational data confirmed that observed metallacyclobutanes are not intermediates in product formation, indicating a novel mechanistic variant.

Conclusions:

• A new nickel-based catalytic system enables challenging alkene metathesis with fluorinated substrates.
• The study reveals a novel variant of the Chauvin mechanism, driven by unique four-coordinate transition states, expanding the mechanistic understanding of metathesis.
• This work provides a valuable new tool for fluoro-organic synthesis, paving the way for novel fluorinated compounds.