茂金属催化的α-烯烃二聚反应：Zr-Al 双核反应机理的 DFT 建模。

Zirconocene-Catalyzed Dimerization of α-Olefins: DFT Modeling of the Zr-Al Binuclear Reaction Mechanism.

机构信息

A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia.

Chemistry Department, M.V. Lomonosov Moscow State University, 1 Leninskie Gory Str., Building 3, 119991 Moscow, Russia.

出版信息

Molecules. 2019 Oct 2;24(19):3565. doi: 10.3390/molecules24193565.

DOI:10.3390/molecules24193565

PMID:31581621

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC6803839/

Abstract

Zirconocene-mediated selective dimerization of α-olefins usually occurs when precatalyst (η-CH)ZrCl is activated by minimal excess of methylalumoxane (MAO). In this paper, we present the results of density functional theory (DFT) simulation of the initiation, propagation, and termination stages of dimerization and oligomerization of propylene within the framework of Zr-Al binuclear mechanism at M-06x/DGDZVP level of theory. The results of the analysis of the reaction profiles allow to explain experimental facts such as oligomerization of α-olefins at high MAO/(η-CH)ZrCl ratios and increase of the selectivity of dimerization in the presence of RAlCl. The results of DFT simulations confirm the crucial role of the presence of chloride in the selectivity of dimerization. The molecular hydrogen was found in silico and proven experimentally as an effective agent that increases the rate and selectivity of dimerization.

摘要

茂金属介导的α-烯烃选择性二聚通常发生在预催化剂（η-CH）ZrCl 被少量过量的甲基铝氧烷（MAO）激活时。在本文中，我们在 M-06x/DGDZVP 理论水平的 Zr-Al 双核机制框架内，通过密度泛函理论（DFT）模拟，展示了丙烯在二聚和齐聚反应引发、传播和终止阶段的结果。对反应轮廓的分析结果可以解释实验事实，例如在高 MAO/（η-CH）ZrCl 比下α-烯烃的齐聚以及在存在 RAlCl 时二聚选择性的增加。DFT 模拟的结果证实了氯化物存在对二聚选择性的关键作用。在硅中发现了分子氢，并通过实验证明它是一种有效提高二聚化速率和选择性的试剂。