The mechanism of ethylene oligomerization with chromium(III) complexes of bis(carbene)pyridine ligands in combination with MAO has been investigated. Oligomerization with mixtures of CH2CH2/ CD 2CD2 reveals that this system produces α-olefins via an extended metallacycle mechanism. Deviation form a Schulz-Flory distribution has been explained on the basis of less favorable product release at the early stages of metallacycle growth (Cr-C4 (±Cr-C6)). Significant amounts of branched olefins (methylidenes) and linear internal olefins are produced at the high catalyst loadings employed in this study, and these result from secondary incorporation of α-olefins into the metallacycle mechanism. Changing the ligand C∧N∧C coordination mode in any way resulted in a sharp loss of activity. In the case of bidentate carbene-pyridine and carbene-thiophene ligands, this is due to a change in the mechanism from metallacycle to linear chain growth. Thus, only those catalysts which support a metallacycle mechanism promote oligomerization with high activity. © 2008 American Chemical Society.

Item Type:	Refereed Article
Research Division:	Chemical Sciences
Research Group:	Inorganic chemistry
Research Field:	Transition metal chemistry
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the chemical sciences
UTAS Author:	McGuinness, DS (Dr David McGuinness)
UTAS Author:	Suttil, JA (Mr James Suttil)
UTAS Author:	Gardiner, MG (Associate Professor Michael Gardiner)
UTAS Author:	Davies, NW (Associate Professor Noel Davies)
ID Code:	52363
Year Published:	2008
Web of Science® Times Cited:	114
Deposited By:	Chemistry
Deposited On:	2008-06-30
Last Modified:	2009-05-01
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