期刊
MOLECULAR CATALYSIS
卷 527, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.mcat.2022.112418
关键词
Density functional theory; Ring-opening metathesis polymerization; MAP-catalyst; Stereoregular polymers; Z-selectivity
资金
- ANID through FONDECYT [3170117, 11200264, 1180158]
- CONICYT [PAI77180024]
- SCC-PIDi-UTEM FONDEQUIP [EQM180180]
In this study, a detailed mechanistic investigation of Z-selective ROMP was conducted using DFT calculations. The results showed that anti olefin attacks were kinetically more favorable than syn attacks, and the stabilization order of the ring-opening species played a crucial role in Z-selectivity.
Herein we present a detailed mechanistic investigation of Z -selective ROMP of norbornadiene (NBD) with MAP-based catalyst 3a-b by DFT (M06) calculations. The studied catalytic reaction mechanism include the initiation, interconversion, and propagation stages with anti and syn NBD olefin attacks. In the initiation, we found the inversion of the metal center from the (R) configuration in the initial reactant to the (S). Further, we found that the olefin attack anti is kinetically more favorable than syn. Following this, we found that the stabilization order of the ring-opening species (ROS) is vital for the Z-selectivity due to the 3a-b-anti-1/2-cis/trans producing cis-polymers, and 3a-b-syn-1/2-trans produces trans -polymers. Furthermore, the 3a-anti-2-cis+syn pathways form cis-syndiotactic polymers that must overcome 30.8 kcal mol(- 1), respectively, during the propagation stage. Finally, the [2+2] cycloaddition of the propagation stages determines the reaction rate, which is essential for producing stereoregular polymers.
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