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Alternating α-Olefin Distributions via Single and Double Insertions in Chromium-Catalyzed Ethylene Oligomerization

Citation

Tomov, AK and Nobbs, JD and Chirinos, JJ and Prabhjot, KS and Malinowski, R and Ho, SKY and Young, CT and McGuinness, DS and White, AJP and Elsegood, MRJ and Britovsek, GJP, Alternating α-Olefin Distributions via Single and Double Insertions in Chromium-Catalyzed Ethylene Oligomerization, Organometallics pp. 1-13. ISSN 0276-7333 (In Press) [Refereed Article]


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DOI: doi:10.1021/acs.organomet.6b00671

Abstract

The catalytic oligomerization of ethylene with chromium-based complexes containing bis(benzimidazolemethyl)amine (BIMA) ligands results in alternating distributions of linear α-olefins (LAOs). Extremely high activities are obtained (>100 000 g mmol1 h1 bar1) with N-alkyl-substituted BIMA ligands, whereas bulky groups on the central nitrogen or alternative central donors result in much lower activities. Variations in the ligand backbone, as well as methylation of the benzimidazole units, lead to reduction in activity. The alternating LAO distributions have been mathematically analyzed using second-order recurrence relations. The shape of the distributions is affected by ethylene pressure (14 bar) and by the cocatalyst to some degree. On the basis of the results and analysis presented herein, we propose that the alternating behavior originates from the ability of these chromium BIMA catalysts to undergo single as well as double ethylene insertion reactions. A minor second distribution (<5 wt %) of 2-ethyl-1-alkenes is obtained under certain conditions, resulting from incorporation of 1-butene. DFT studies (M06L) and experimental observations regarding the reaction between AlMe3 and the N-methyl BIMA ligand 2 have shown that deprotonation of the benzimidazole NH units can occur, which suggests a change in coordination of the BIMA ligand under oligomerization conditions.

Item Details

Item Type:Refereed Article
Keywords:oligomerisation, DFT
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:McGuinness, DS (Dr David McGuinness)
ID Code:113507
Year Published:In Press
Funding Support:Australian Research Council (FT100100609)
Deposited By:Chemistry
Deposited On:2017-01-05
Last Modified:2017-01-13
Downloads:0

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