文献类型：期刊文献

英文题名：Selective Co-Oligomerization of Ethylene and 1-Hexene by Chromium-PNP Catalysts: A DFT Study

作者：Gong, Minglan[1];Liu, Zhen[1];Li, Yuanhui[1];Ma, Yue[1];Sun, Qiaoqiao[1];Zhang, Jialong[1];Liu, Boping[1]

机构：[1]E China Univ Sci & Technol, State Key Lab Chem Engn, Meilong Rd 130, Shanghai 200237, Peoples R China

年份：2016

卷号：35

期号：7

起止页码：972

外文期刊名：ORGANOMETALLICS

收录：;EI(收录号：20161802331093);WOS:【SCI-EXPANDED(收录号:WOS:000374077200009)】；

基金：The authors thank the National Natural Science Foundation of China (No. 21174037, No. 21304033). This work is also financially supported by the Research Program of the State Key Laboratory of Chemical Engineering, the Program of Introducing Talents of Discipline to Universities (B08021), and the Fundamental Research Funds for the Central Universities.

语种：英文

外文关键词：Isomers - Oligomers - Catalysts - Free energy - Density functional theory - Oligomerization - Chromium compounds - Gibbs free energy - Chlorine compounds - Phosphorus compounds - Chromium

摘要：The mechanism of selective co-oligomerization of ethylene and 1-hexene by the catalyst [CrCl3(PNPOMe)] (a, PNPOMe = N,N-bis(bis(o-methoxyphenyl)phosphine)methylamine) has been explored in detail using the density functional theory (DFT) method. The full catalytic cycles for the formation of 1-hexene and 1-decenes were calculated on the basis of the metallacyclic mechanism, and the distribution of all decene isomers was explained by locating Gibbs free energy surfaces of various pathways, which is in good agreement with the experimental results. A spin surface crossing through a minimum energy crossing point (MECP) from a sextet to a quartet surface takes place before the formation of metallacydopentane, which opens up a much lower energy pathway and thus facilitates the following co-oligomerization reactions. It is worth noting that beta-hydrogen agostic-assisted hydrogen transfer is of crucial importance for the decomposition of the metallacycle intermediates to give 1-hexene or decenes. Moreover, an analysis of the Cr-O bond distance and NBO charges indicates the important role of a hemiliable methoxy moiety, which acts as a pendant group in the co-oligomerization of ethylene and 1-hexene by CrCl3(PNPOMe) catalyst.