Skip to main content

Research Repository

Advanced Search

Vanadium(V) tetra-phenolate complexes: synthesis, structural studies and ethylene homo-(co-)polymerization capability

Michiue, K.; Redshaw, Carl; Walton, Mark J.; Elsegood, Mark R. J.; Prior, Timothy J.; Michiue, Kenji

Authors

K. Michiue

Profile Image

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

Mark J. Walton

Mark R. J. Elsegood

Kenji Michiue



Abstract

Reaction of α,α,α′,α′-tetrakis(3,5-di-tert-butyl-2-hydroxyphenyl)-p-xylene (p-L¹H₄) with two equivalents of [VO(OR)₃] (R = nPr, tBu) in refluxing toluene afforded, after work-up, the complexes {[VO(OnPr)(THF)]₂ (μ-p-L¹)}·2(THF) (1·2(THF)) or {[VO(OtBu)]₂ (μ-p-L¹)}·2MeCN (2·2MeCN), respectively in moderate to good yield. A similar reaction using the meta pro-ligand, namely α,α,α′,α′-tetrakis(3,5-di-tert-butyl-2-hydroxyphenyl)-m-xylene (m-L²H₄) afforded the complex {[VO(OnPr)(THF)]₂ (μ-p-L²)} (3). Use of [V(Np-R¹C₆H₄)(tBuO)₃] (R¹ = Me, CF₃) with p-L¹H₄ led to the isolation of the oxo–imido complexes {[VO(tBuO)][V(Np-R¹C₆H₄) (tBuO)](μ-p-L¹)} (R¹ = Me, 4·CH2Cl₂; CF₃, 5·CH2Cl₂), whereas use of [V(Np-R¹C₆H₄)CL³] (R¹ = Me, CF₃) in combination with Et₃N/p-L¹H₄ or p-L¹Na₄ afforded the diimido complexes {[V(Np-MeC₆H₄)(THF)Cl]₂ (μ-p-L¹)}·4toluene (6·4toluene) or {[V(Np-CF₃C₆H₄)(THF)Cl]₂ (μ-p-L¹)} (7). For comparative studies, the complex [(VO)(μ-OnPr)L³]₂ (8) has also been prepared via the interaction of [VO(nPrO)₃] and 2-(α-(2-hydroxy-3,5-di-tert-butylphenyl)benzyl)-4,6-di-tert-butylphenol (L³H2). The crystal structures of 1·2THF, 2·2MeCN, 3, 4·CH2Cl₂, 5·CH2Cl₂, 6·4toluene·THF, 7 and 8 have been determined. Complexes 1–3 and 5–8 have been screened as pre-catalysts for the polymerization of ethylene in the presence of a variety of co-catalysts (with and without a re-activator), including DMAC (dimethylaluminium chloride), DEAC (diethylaluminium chloride), EADC (ethylaluminium dichloride) and EASC (ethylaluminium sesquichloride) at various temperatures and for the co-polymerization of ethylene with propylene; results are compared versus the benchmark catalyst [VO(OEt)Cl₂]. In some cases, activities as high as 243 400 g mmol⁻¹ V⁻¹ h⁻¹ (30.43 kgPE mmol V⁻¹ h⁻¹ bar⁻¹) were achievable, whilst it also proved possible to obtain higher molecular weight polymers (in comparable yields to the use of [VO(OEt)Cl₂]). In all cases with dimethylaluminium chloride (DMAC)/ethyltrichloroacetate (ETA) activation, the activities achieved surpassed those of the benchmark catalyst. In the case of the co-polymerization of ethylene with propylene, complexes 1–3 and 5–8 showed comparable or higher molecular weight than [VO(OEt)Cl₂] with comparable catalytic activities or higher in the case of the imido complexes 6 and 7.

Citation

Redshaw, C., Walton, M. J., Elsegood, M. R. J., Prior, T. J., & Michiue, K. (2015). Vanadium(V) tetra-phenolate complexes: synthesis, structural studies and ethylene homo-(co-)polymerization capability. RSC advances, 5(109), 89783-89796. https://doi.org/10.1039/c5ra20177b

Journal Article Type Article
Acceptance Date Oct 7, 2015
Online Publication Date May 1, 2015
Publication Date Oct 8, 2015
Deposit Date Nov 23, 2015
Publicly Available Date Nov 23, 2017
Journal RSC advances
Print ISSN 2046-2069
Electronic ISSN 2046-2069
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 5
Issue 109
Pages 89783-89796
DOI https://doi.org/10.1039/c5ra20177b
Keywords Vanadium, Tetra-phenolate, Polyethylene, Ethylene/propylene copolymer, Crystal structures
Public URL https://hull-repository.worktribe.com/output/381726
Publisher URL http://pubs.rsc.org/EN/content/articlelanding/2015/ra/c5ra20177b#!divAbstract
Copyright Statement ©2016 University of Hull
Additional Information Authors' accepted manuscript of article published in: RSC advances, 2015, v.5, issue 109.

Files



You might also like



Downloadable Citations