Mechanistic insights on acrylate insertion polymerization.

Area of Science:

• Organometallic Chemistry
• Polymerization Catalysis
• Coordination Chemistry

Background:

• Palladium complexes with PwedgeO ligands serve as single-component precursors for catalytic acrylate oligomerization.
• Understanding the mechanism of acrylate insertion into palladium-alkyl bonds is crucial for controlling polymerization.

Purpose of the Study:

• To investigate the catalytic oligomerization of acrylates using novel palladium complexes.
• To elucidate the mechanism of consecutive acrylate insertions into palladium-methyl bonds.
• To model intermediates involved in acrylate insertion polymerization and ethylene-acrylate copolymerization.

Main Methods:

• Synthesis and characterization of palladium complexes, including NMR spectroscopy and single crystal X-ray diffraction.
• Kinetic studies of substrate binding and polymerization inhibition.
• Density Functional Theory (DFT) calculations to model reaction pathways and energy barriers.

Main Results:

• Two diastereomeric chelate complexes were formed via consecutive 2,1-insertions of methyl acrylate into the Pd-Me bond.
• Binding studies revealed that monomer coordination hinders acrylate insertion, significantly retarding polymerization.
• DFT studies provided detailed insights into the pathways and energy barriers of multiple consecutive acrylate insertions.

Conclusions:

• The synthesized palladium complexes are effective models for intermediates in acrylate insertion polymerization.
• Monomer coordination plays a critical role in regulating the rate of polymerization.
• Theoretical calculations support experimental observations, offering a deeper understanding of the catalytic process.