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Tri- and tetra-dentate imine vanadyl complexes: synthesis, structure and ethylene polymerization/ring opening polymerization capability

Ma, Jing; Zhao, Ke-Qing; Walton, Mark; Wright, Joseph A.; Hughes, David L.; Elsegood, Mark R. J.; Michiue, Kenji; Sun, Xinsen; Redshaw, Carl


Jing Ma

Ke-Qing Zhao

Mark Walton

Joseph A. Wright

David L. Hughes

Mark R. J. Elsegood

Kenji Michiue

Xinsen Sun

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Professor Carl Redshaw
Professor of Inorganic Materials Chemistry and REF Lead for Chemistry


Reaction of the ligand 2,4-tert-butyl-6-[(2-methylquinolin-8-ylimino)methyl]phenol (L¹H) with [VOCl₃] in the presence of triethylamine afforded the complex [VOCl₂L¹] (1), whereas use of [VO(OnPr)₃] led to the isolation of [VO₂L¹] (2) or [VO₂L¹]·2/3MeCN (2·2/3MeCN). Reaction of 2-((2-(1H-benzo[d]imidazol-2-yl)quinolin-8-ylimino)methyl)-4,6-R¹,R²-phenols (R¹ = R² = ᵗBu; L²H), (R¹ = R² = Me; L³H) or (R¹ = Me, R² = Ad; L⁴H) with [VO(OnPr)₃] afforded complexes of the type [L²⁻⁴VO] (where L² = 3, L³ = 4, L⁴ = 5). The molecular structures of 1 to 3 are reported; the metal centre adopts a distorted octahedral, trigonal bipyramidal or square-based pyramidal geometry respectively. In Schlenk line tests, all complexes have been screened as pre-catalysts for the polymerization of ethylene using diethylaluminium chloride (DEAC) as co-catalyst in the presence of ethyltrichloroacetate (ETA), and for the ring opening polymerization (ROP) of ε-caprolactone in the presence of benzyl alcohol. All pre-catalyst/DEAC/ETA systems are highly active ethylene polymerization catalysts affording linear polyethylene with activities in the range 3000–10700 g (mol h bar)⁻¹; the use of methylaluminoxane (MAO) or modified MAO as co-catalyst led to poor or no activity. In a parallel pressure reactor, 3–5 have been screened as pre-catalysts for ethylene polymerization in the presence of either DEAC or DMAC (dimethylaluminium chloride) and ETA at various temperatures and for the co-polymerization of ethylene with propylene. The use of DMAC proved more promising with 3 achieving an activity of 63000 g (mol h bar)⁻¹ at 50 °C and affording UHMWPE (Mw ~ 2000000). In the case of the co-polymerization, the incorporation of propylene was 6.9–8.8 mol%, with 3 exhibiting the highest incorporation when using either DEAC or DMAC. In the case of the ring opening polymerization (ROP) of ε-caprolactone, systems employing complexes 1–5 were virtually inactive at temperatures <110 °C; on increasing the CL:V ratio at 110 °C, conversions of the order of 80% were achievable.


Ma, J., Zhao, K., Walton, M., Wright, J. A., Hughes, D. L., Elsegood, M. R. J., …Redshaw, C. (2014). Tri- and tetra-dentate imine vanadyl complexes: synthesis, structure and ethylene polymerization/ring opening polymerization capability. Dalton Transactions : an international journal of inorganic chemistry, 43(44), 16698-16706.

Journal Article Type Article
Acceptance Date Sep 18, 2014
Online Publication Date Sep 18, 2014
Publication Date Nov 28, 2014
Deposit Date Jun 9, 2015
Publicly Available Date Jun 9, 2015
Journal Dalton transactions
Print ISSN 1477-9226
Electronic ISSN 1477-9234
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 43
Issue 44
Pages 16698-16706
Keywords Polymerization; Ethylene; Synthesis
Public URL
Publisher URL!divAbstract
Additional Information Author's accepted manuscript of article published in: Dalton transactions, 2014, v.43, issue 44 at!divAbstract


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