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Single- and double-coordination mechanism in ethylene tri- and tetramerization with Cr/PNP catalysts

Citation

Britovsek, GJP and McGuinness, DS and Wierenga, TS and Young, CT, Single- and double-coordination mechanism in ethylene tri- and tetramerization with Cr/PNP catalysts, ACS Catalysis, 5, (7) pp. 4152-4166. ISSN 2155-5435 (2015) [Refereed Article]

Copyright Statement

Copyright 2015 American Chemical Society.

DOI: doi:10.1021/acscatal.5b00989

Abstract

The mechanism of ethylene trimerization and tetramerization with a chromium–diphosphinoamine (Cr–PNP) catalyst system has been studied with combined experimental and theoretical methods. Of the total product output, 1-octene, cyclopentanes, n-alkanes, and higher (C10+) olefins are formed with a fractional (∼1.4) order response to ethylene concentration, whereas 1-hexene formation is approximately first-order in ethylene. Theoretical studies suggest a mechanism involving a cationic monometallic catalyst in Cr(I) and Cr(III) formal oxidation states. A key feature of the developed model is the occurrence of a double-coordination mechanism in which a bis(ethylene) chromacyclopentane intermediate is responsible for 1-octene formation as well as the other coproducts that have a greater than first-order response to ethylene. In contrast, 1-hexene is formed primarily from a mono(ethylene) chromacyclopentane intermediate. The selectivity of catalysis is governed by the competition between single- and double-coordination pathways. The mechanistic model developed displays excellent correlation with experimental observations and is able to fully explain the formation of all products generated with this catalyst.

Item Details

Item Type:Refereed Article
Keywords:catalysis, olefin, ethylene, tetramerisation, trimerization, oligomerization, chromium, reaction mechanism
Research Division:Chemical Sciences
Research Group:Other Chemical Sciences
Research Field:Organometallic Chemistry
Objective Division:Manufacturing
Objective Group:Industrial Chemicals and Related Products
Objective Field:Organic Industrial Chemicals (excl. Resins, Rubber and Plastics)
Author:Britovsek, GJP (Dr George Britovsek)
Author:McGuinness, DS (Dr David McGuinness)
Author:Wierenga, TS (Miss Tanita Wierenga)
ID Code:105977
Year Published:2015
Funding Support:Australian Research Council (FT100100609)
Web of Science® Times Cited:21
Deposited By:Chemistry
Deposited On:2016-01-21
Last Modified:2017-11-02
Downloads:0

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