Olefin Insertion into a Pd-F Bond: Catalyst Reactivation Following β-F Elimination in Ethylene/Vinyl Fluoride...

Area of Science:

• Organometallic Chemistry
• Polymer Science
• Fluorine Chemistry

Background:

• Palladium catalysts are crucial for olefin polymerization.
• Understanding chain termination mechanisms is vital for controlling polymer properties.
• Fluorinated polymers offer unique material characteristics.

Purpose of the Study:

• To elucidate the mechanism of vinyl fluoride (VF) and ethylene (E) copolymerization using a discrete (phosphinoarenesulfonate)Pd fluoride complex.
• To investigate the formation pathways of -CHF2 and -CH2F chain ends in the resulting E/VF copolymer.
• To assess the role of beta-F elimination in catalyst deactivation during this copolymerization process.

Main Methods:

• Synthesis and characterization of the (phosphinoarenesulfonate)Pd fluoride complex, (POBp,OMe)PdF(lutidine).
• Investigation of vinyl fluoride insertion reactions with the palladium complex.
• Analysis of ethylene insertion and chain growth in the presence of vinyl fluoride.
• Characterization of the resulting polyethylene chain ends (-CHF2 and -CH2F).

Main Results:

• The (phosphinoarenesulfonate)Pd fluoride complex successfully inserted vinyl fluoride, yielding (POBp,OMe)PdCH2CHF2(lutidine).
• Multiple ethylene insertions led to polyethylene with -CH2F chain ends.
• The study provides evidence that -CHF2 and -CH2F chain ends originate from beta-F elimination, followed by VF or E insertion and chain growth.
• Beta-F elimination was found not to be a significant catalyst deactivation pathway in this system.

Conclusions:

• The mechanism for forming -CHF2 and -CH2F chain ends in E/VF copolymers has been clarified.
• The findings suggest that the (phosphinoarenesulfonate)Pd catalyst system is robust against deactivation via beta-F elimination.
• This research contributes to the understanding of catalytic processes involving fluorinated monomers and palladium complexes.