"C-Hπ Interaction" regulates the stereoselectivity in olefin polymerization.

Area of Science:

• Polymer Chemistry
• Organometallic Chemistry
• Computational Chemistry

Background:

• Stereoselective polymerization is crucial for tailoring polymer properties.
• Scandium (Sc)-based catalysts offer unique reactivity in olefin polymerization.
• Controlling polymer tacticity (isotactic vs. syndiotactic) remains a significant challenge.

Purpose of the Study:

• To elucidate the mechanism of stereocontrol in Sc-catalyzed polymerization of halogenated styrenes.
• To investigate the role of non-covalent interactions in dictating polymer microstructure.
• To explore the potential for switching stereoselectivity using catalyst-monomer interactions.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to model the polymerization process.
• Analysis of non-covalent interactions, specifically C-Hπ interactions, between the catalyst ligand (THF) and monomer.
• Theoretical investigation of polymerization for a range of halogenated styrene monomers.

Main Results:

• DFT calculations identified C-Hπ interactions as a key factor in regulating stereoselectivity.
• These interactions occur between the coordinating tetrahydrofuran (THF) ligand and the monomer's phenyl ring.
• The regulatory mechanism was confirmed, demonstrating the ability to shift stereoselectivity from syndiotactic to isotactic.

Conclusions:

• C-Hπ interactions provide a novel co-regulatory mechanism for stereocontrol in Sc-catalyzed styrene polymerization.
• This understanding enables rational design of catalysts and conditions for targeted polymer tacticity.
• The findings open new avenues for synthesizing advanced halogenated polymers with tailored properties.