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Vanadyl complexes bearing bi-dentate phenoxyimine ligands: Synthesis, structural studies and ethylene polymerization capability

Ma, Jing; Zhao, Ke-Qing; Walton, Mark J.; Wright, Joseph A.; Frese, Josef W. A.; Elsegood, Mark R. J.; Xing, Qifeng; Sun, Wen-Hua; Redshaw, Carl

Authors

Jing Ma

Ke-Qing Zhao

Mark J. Walton

Joseph A. Wright

Josef W. A. Frese

Mark R. J. Elsegood

Qifeng Xing

Wen-Hua Sun

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Professor Carl Redshaw C.Redshaw@hull.ac.uk
Professor of Inorganic Materials Chemistry and REF Lead for Chemistry



Abstract

Reaction of [VO(OnPr)₃] with the Schiff bases 3,5-(tBu)₂-2-OH-C₆H₂CH(N(x-OR-C₆H₄)) (R = Me; x = 2, L¹H; x = 3, L²H; x = 4, L³H; R = Et (L⁴H), CF₃ (L⁵H), Ph (L⁶H)) or 4-methyl-3-(R)-2-(OH)-C₆H₄C=N(2′-(2′′-(OR₁)C₆H₄)C₆H₄) (R = adamantyl, R¹ = Ph (L⁷H) or R = C(Me)₂Ph, R¹ = Ph (L⁸H)) afforded the bis(chelate) vanadium(IV) complexes [VO(Ln)₂] (n = 1 (1·2MeCN); n = 2 (2); n = 3 (3·2MeCN); n = 4 (4); n = 5 (5); n = 6 (6); n = 6, (7·1.5MeCN); n = 7, (8); n = 8, (9)); in the case of L⁶H, the oxo-bridged vanadium(V) complexes [VO(μ-O)(L⁶)]₂ (10) was also isolated. By contrast, interaction of 4-methyl-3-(R)-2-(OH)-C₆H₄C=N(2′-(2′′-(OR₁)C₆H₄)C₆H₄) (R = adamantyl, R¹ = Me (L⁹H); R = tBu, R¹ = Me (L¹⁰H); R = C(Me)₂Ph, R1 = Me (L¹¹H)) with [VO(OnPr)₃] led to the isolation of the dinuclear complexes [VO(μ-OH)(μ-OnPr)(Ln)]₂ (n = 9, (11·4MeCN); 10, (12); 11, (13)), respectively. The molecular structures of 1 to 13 are reported. All complexes have been screened as pre-catalysts for the polymerization of ethylene in the presence of the co-catalyst diethylaluminium chloride (DEAC) with or without ethyltrichloroacetate (ETA) present at 1 or 10 bar of ethylene. Under high pressure, all pre-catalysts exhibited high activity and afforded high molecular weight (Mw ≈ 200000 to 675000 g mol⁻¹), linear polyethylene with activities (in the presence of ETA) in the range 4960–16400 g mmol⁻¹ h⁻¹; at one bar, the products were generally of lower molecular weight. The use of methylaluminoxane (MAO) or modified MAO (MMAO) as co-catalyst led to trace or poor (≤110 g mmol⁻¹ h⁻¹) activity, respectively.

Citation

Ma, J., Zhao, K., Walton, M. J., Wright, J. A., Frese, J. W. A., Elsegood, M. R. J., …Redshaw, C. (2014). Vanadyl complexes bearing bi-dentate phenoxyimine ligands: Synthesis, structural studies and ethylene polymerization capability. Dalton transactions : an international journal of inorganic chemistry / RSoC, 43(22), 8300-8310. doi:10.1039/c4dt00021h

Journal Article Type Article
Acceptance Date Mar 9, 2014
Online Publication Date Mar 12, 2014
Publication Date Jun 14, 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 22
Pages 8300-8310
DOI https://doi.org/10.1039/c4dt00021h
Keywords Ethylene polymerization, Vanadyl complexes
Public URL https://hull-repository.worktribe.com/output/374932
Publisher URL http://pubs.rsc.org/en/Content/ArticleLanding/2014/DT/c4dt00021h#!divAbstract
Additional Information Author's accepted manuscript of article published in: Dalton transactions, 2014, v.43, issue 22.

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