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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.

Journal Article Type Article
Publication Date Jun 14, 2014
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
Institution 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
DOI https://doi.org/10.1039/c4dt00021h
Keywords Ethylene polymerization, Vanadyl complexes
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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