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Rationale for the reactivity differences between main group and d0 transition metal complexes toward olefin polymerisation

Citation

Tabatabaie, ES and Dehghanpour, S and Mosaddegh, E and Babaahmadi, R and Chipman, A and Yates, BF and Ariafard, A, Rationale for the reactivity differences between main group and d0 transition metal complexes toward olefin polymerisation, Dalton Transactions, 48, (20) pp. 6997-7005. ISSN 1477-9226 (2019) [Refereed Article]

Copyright Statement

The Royal Society of Chemistry 2019

DOI: doi:10.1039/c9dt01017c

Abstract

In contrast to early transition metal complexes of d0 electron configuration, their main group metal analogues are usually poor catalysts for ethylene polymerisation due to their diminished tendency to insert ethylene into an M-R bond. Interestingly, we found that ring strain in the transition structure of the insertion reaction is most likely responsible to set the ease of the process. Ethylene insertion into an M-R bond requires a four-membered ring transition structure. Strain in a four-membered ring was shown to be dependent on the metal identity (transition or main group/d or p block). For early transition metals, due to the presence of empty valence d orbitals, the strain is negligible but, for main group metals, the strain is significant and so destabilizes the corresponding transition structure. Our claim gains support from investigation of ethylene insertion into an M-allyl bond. In this case, the relevant insertion preferentially passes through a six-membered ring transition structure with an accessibly low activation barrier. In contrast to four-membered ring transition structures, six-membered ones do not suffer significantly from ring strain, causing the insertion activation barrier to become independent of the metal identity. It becomes obvious from our study that this previously undisclosed factor should play the pivotal role in determining the reactivity of many catalysts.

Item Details

Item Type:Refereed Article
Keywords:density functional theory, activation energy, polymerization, ring strain
Research Division:Chemical Sciences
Research Group:Organic Chemistry
Research Field:Physical Organic Chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
UTAS Author:Babaahmadi, R (Mr Rasool Babaahmadi)
UTAS Author:Chipman, A (Mr Antony Chipman)
UTAS Author:Yates, BF (Professor Brian Yates)
UTAS Author:Ariafard, A (Associate Professor Alireza Ariafard)
ID Code:134558
Year Published:2019
Funding Support:Australian Research Council (DP180100904)
Deposited By:Chemistry
Deposited On:2019-08-20
Last Modified:2019-12-10
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