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

Efficient Synthesis of Polyethylene Wax Using 8-(Arylimino)-5,6,7-Trihydroquinoline Sio 2 -Supported Heterogeneous Nickel Catalysts DOI

Shan Xu,

Xu Hu,

Mengna Lei

et al.

Published: Jan. 1, 2025

Language: Английский

Citations

0
Efficient synthesis of polyethylene wax using 8-(arylimino)-5,6,7-trihydroquinoline SiO2-supported heterogeneous nickel catalysts DOI

Shan Xu,

Hu Xu,

Mengna Lei

et al.

Polymer, Journal Year: 2025, Volume and Issue: unknown, P. 128367 - 128367

Published: April 1, 2025

Language: Английский

Citations

0
Flexible α‐Diimine Ni(II) and Pd(II) Catalysts Featuring Backbone and Axial Cycloalkyl Substituents in Ethylene (Co)polymerization DOI Open Access

Jianjian Dai,

Shengyu Dai

Journal of Polymer Science, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 5, 2025

ABSTRACT Recently, axial flexible substituents have found widespread application in ethylene (co)polymerization catalyzed by late transition metals, yielding impressive results. In this research, we designed and synthesized a novel class of α‐diimine Ni(II) Pd(II) catalysts, distinguished their backbones that both incorporate cycloalkyl moieties. During nickel‐catalyzed polymerization, these nickel catalysts demonstrated high activity (well above 10 6 g/(mol Ni·h)) thermal stability, producing polyethylenes with very molecular weights (up to 1022 kg/mol) branching densities 103/1000C). Interestingly, the catalyst reported study exhibits higher compared classic rigid backbones. The resultant polyethylene materials exhibited outstanding mechanical properties elastic recovery (with strain (SR) up 79%), qualifying them as high‐performance thermoplastic elastomers. contrast, during palladium‐catalyzed palladium showed moderate (level 5 Pd·h)) generated 99/1000C) 203 kg/mol). case copolymerization methyl acrylate (MA), was notably reduced homopolymerization, resulting E‐MA copolymers lower densities. However, under experimental conditions, successfully obtained significant incorporation (1.53–4.54 mol%) MA. It is worth noting cyclohexyl group displayed superior chain transfer inhibition systems cyclopentyl group. Nevertheless, notable difference observed influence on density regulation: system, facilitated formation branching, while it had opposite effect when

Language: Английский

Citations

0
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

Citations

0