Unravelling the chain growth mechanism in Cr/NNN-catalysed ethylene oligomerization

文献情報

出版日 2023-08-07

DOI 10.1039/D3CY00954H

インパクトファクター 6.119

著者

Jiale Peng, Mengyu Zhu, Long Chen, Zhen Liu

要旨

A special and controversial Cr/NNN ethylene oligomerization system delivering oligomers in a Schulz–Flory distribution, which was suggested to follow a metallacycle mechanism, has been systematically investigated by means of density functional theory (DFT) methods. Both Cossee–Arlman and metallacycle mechanisms have been considered. DFT calculation results demonstrated that Cossee-type chain propagation operates in this case while the metallacyclic chain growth is less likely to occur. A larger kinetic isotope effect (KIE) on the β-H elimination was found to hinder the transfer of deuterium atoms to the metal centre. As such, abundant even-numbered isotopomers were observed in the GC-MS spectrum while odd-numbered products only occupied a small portion. The presence of the KIE has a significant effect on the distribution of isotopomers. The Cossee–Arlman catalytic cycle with a strong KIE may lead to unnoticeable H/D scrambling and for this reason the analysis of isotopic product peaks in C2H4/C2D4 co-oligomerization should be taken with good care.

掲載誌

Catalysis Science & Technology

CiteScore: 5.91

自己引用率: 4.5%

年間論文数: 600

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