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Vanadium complexes derived from oxacalix[6]arenes: structural studies and use in the ring opening homo-/co-polymerization of ε-caprolactone/δ-valerolactone and ethylene polymerization

Xing, Tian; Prior, Timothy J.; Elsegood, Mark Robert James; Semikolenova, Nina V; Soshnikov, Igor E; Bryliakov, Konstantin P.; Chen, Kai; Redshaw, Carl

Authors

Tian Xing

Mark Robert James Elsegood

Nina V Semikolenova

Igor E Soshnikov

Konstantin P. Bryliakov

Kai Chen

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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 Na[VO(tBuO)4] (generated in-situ from VOCl3 and NaOtBu) with p-tert-butyltetrahomodioxacalix[6]areneH6 (L1H6) afforded, after work-up (in MeCN), the mixed-metal complex [(VO)2(μ-O)Na2(L1)(MeCN)4]·5(MeCN) (1·5MeCN), whilst the oxo complex {[VO]4L1} (2·6MeCN) was isolated via the use of [VO(OnPr)3]. Reaction of L1H6 with [V(Np-CH3C6H4)(OtBu)3] afforded the complex {[V(Np-CH3C6H4)]2L1} (3·7MeCN·0.5CH2Cl2). Use of similar methodology afforded the imido complexes {[V(Np-RC6H4)]2L1} (R = OMe (4); CF3(5); Cl (6); F (7)); on one occasion, reaction of [V(Np-CH3C6H4)(OEt)3] with L1H6 afforded the product [VO(L2)]2·4MeCN (8·4MeCN) (L2 = 2-(p-CH3-C6H4NCH)-4-tBu-C6H2O-6-CH2)-4-tBuC6H2OH) in which L1 has been cleaved. For comparative catalytic ring opening polymerization (ROP) studies, the known complexes [VOL3] (L3 = oxacalix[3]arene) (I), [V(Np-CH3-C6H4)L3]2 (II), [Li(MeCN)4][V2(O)2Li(MeCN)(L6H2)2] (L6H6 = p-tert-butylcalix[6]areneH6) (III) and [(VO)2L8H] (L8H8 = p-tert-butylcalix[8]areneH8) (IV) have also been prepared. ROP studies, with or with external alcohol present, indicated that complexes 1 to 8 exhibited moderate to good conversions for ε-Cl, δ-VL and the co-polymerization thereof. Within the imido series, a positive influence was observed when electron withdrawing substituents were present. These systems afforded relatively low molecular weight products and were also inactive toward the ROP of rac-lactide. In the case of ethylene polymerization, complexes 3, 5 and 7 exhibited highest activity when screened in the presence of dimethylaluminium chloride/ethyltrichloroacetate; the activity of 4 was much lower. The products were highly linear polyethylene with Mw in the range 74-120x103 Da.

Citation

Xing, T., Prior, T. J., Elsegood, M. R. J., Semikolenova, N. V., Soshnikov, I. E., Bryliakov, K. P., …Redshaw, C. (2021). Vanadium complexes derived from oxacalix[6]arenes: structural studies and use in the ring opening homo-/co-polymerization of ε-caprolactone/δ-valerolactone and ethylene polymerization. Catalysis science & technology, 11(2), 624-636. https://doi.org/10.1039/d0cy01979h

Journal Article Type Article
Acceptance Date Nov 19, 2020
Online Publication Date Nov 19, 2020
Publication Date Jan 21, 2021
Deposit Date Nov 19, 2020
Publicly Available Date Dec 17, 2020
Journal Catalysis Science and Technology
Print ISSN 2044-4753
Electronic ISSN 2044-4761
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 11
Issue 2
Pages 624-636
DOI https://doi.org/10.1039/d0cy01979h
Keywords Catalysis
Public URL https://hull-repository.worktribe.com/output/3664233
Publisher URL https://pubs.rsc.org/en/Content/ArticleLanding/2020/CY/D0CY01979H#!divAbstract

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