The mechanism of ethylene trimerization and tetramerization with a chromium-diphosphinoamine (Cr-PNP) catalyst system has been studied by theoretical (DFT) methods. Two representative ligands have been explored, namely Ph₂PN(Me)PPh₂ and (o-MeC₆H₄)₂PN(Me)P(o-MeC₆H₄)₂. Calculations on the former ligand reveal how a combination of single and double ethylene insertion mechanisms may lead to 1-hexene, 1-octene and the major side products (cyclopentanes and n-alkanes). For the latter ligand, introduction of o-alkyl substitution leads to a more sterically congested active species, which suppresses the available pathways for tetramerization and side product formation. Hence, the high selectivity of o-aryl substituted PNP ligands for trimerization can be rationalized.

Item Type:	Refereed Article
Keywords:	trimerisation, tetramerisation, DFT
Research Division:	Chemical Sciences
Research Group:	Inorganic chemistry
Research Field:	Organometallic chemistry
Objective Division:	Manufacturing
Objective Group:	Industrial chemicals and related products
Objective Field:	Organic industrial chemicals (excl. resins, rubber and plastics)
UTAS Author:	McGuinness, DS (Dr David McGuinness)
ID Code:	113506
Year Published:	2016
Funding Support:	Australian Research Council (FT100100609)
Web of Science® Times Cited:	33
Deposited By:	Chemistry
Deposited On:	2017-01-05
Last Modified:	2017-08-29
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