Theoretical Investigations of Para-Methoxystyrene/Styrene Polymerization Catalyzed by Cationic Methyl- and Dibenzobarrelene-Based α-Diimine Palladium Complexes DOI Creative Commons

Ling Zhu,

Yi Luo, Xin Wen

et al.

Inorganics, Journal Year: 2024, Volume and Issue: 12(12), P. 315 - 315

Published: Dec. 5, 2024

The polymerization mechanism of para-methoxystyrene catalyzed by cationic α-diimine palladium complexes with various ancillary ligands was rigorously examined using density functional theory. In the classical methyl-based complex [{(2,6-iPr2C6H3)-N=C(Me)-C(Me)=N-2,6-iPr2C6H3)}PdMe]+ (A+), 2,1-insertion is favored over 1,2-insertion, both thermodynamically and kinetically, during chain initiation step. resulting η3-π-benzyl intermediates face a substantial energy barrier, yielding only trace amounts polymer, as experimentally verified. contrast, dibenzobarrelene-based [{(2,6-iPr2C6H3)-N=C(R)-C(R)=N-2,6-iPr2C6H3)}PdMe]+ (R = dibenzobarrelene, B+) shows similar barriers for 2,1- 1,2-insertions. Continuous 2,1/2,1 or 2,1/1,2 insertions are impeded excessive barriers. However, theoretical calculations reveal that 1,2-insertion product can seamlessly transition into propagation stage, producing polymer high 1,2-regioselectivity. observed activity A+ B+ towards stems from barrier differences between 1,2- 2,1-insertions, influenced steric hindrance ligands. Further investigation effects on stage involved computational modeling analogous increased bulk. These studies established direct correlation difference ∆∆G (1,2–2,1) van der Waals volume ligand. Larger volumes correspond to reduced differences, thus enhancing regioselectivity polymerization. Moreover, experimental inertness styrene attributed formation stable kinetic thermodynamic intermediates, which obstruct further monomer insertion due an extremely reactive barrier. findings contribute deeper understanding mechanistic aspects offer insights designing new metal catalysts para-alkoxystyrenes.

Language: Английский

Theoretical Investigations of Para-Methoxystyrene/Styrene Polymerization Catalyzed by Cationic Methyl- and Dibenzobarrelene-Based α-Diimine Palladium Complexes DOI Creative Commons

Ling Zhu,

Yi Luo, Xin Wen

et al.

Inorganics, Journal Year: 2024, Volume and Issue: 12(12), P. 315 - 315

Published: Dec. 5, 2024

The polymerization mechanism of para-methoxystyrene catalyzed by cationic α-diimine palladium complexes with various ancillary ligands was rigorously examined using density functional theory. In the classical methyl-based complex [{(2,6-iPr2C6H3)-N=C(Me)-C(Me)=N-2,6-iPr2C6H3)}PdMe]+ (A+), 2,1-insertion is favored over 1,2-insertion, both thermodynamically and kinetically, during chain initiation step. resulting η3-π-benzyl intermediates face a substantial energy barrier, yielding only trace amounts polymer, as experimentally verified. contrast, dibenzobarrelene-based [{(2,6-iPr2C6H3)-N=C(R)-C(R)=N-2,6-iPr2C6H3)}PdMe]+ (R = dibenzobarrelene, B+) shows similar barriers for 2,1- 1,2-insertions. Continuous 2,1/2,1 or 2,1/1,2 insertions are impeded excessive barriers. However, theoretical calculations reveal that 1,2-insertion product can seamlessly transition into propagation stage, producing polymer high 1,2-regioselectivity. observed activity A+ B+ towards stems from barrier differences between 1,2- 2,1-insertions, influenced steric hindrance ligands. Further investigation effects on stage involved computational modeling analogous increased bulk. These studies established direct correlation difference ∆∆G (1,2–2,1) van der Waals volume ligand. Larger volumes correspond to reduced differences, thus enhancing regioselectivity polymerization. Moreover, experimental inertness styrene attributed formation stable kinetic thermodynamic intermediates, which obstruct further monomer insertion due an extremely reactive barrier. findings contribute deeper understanding mechanistic aspects offer insights designing new metal catalysts para-alkoxystyrenes.

Language: Английский

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