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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

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posted on 23.11.2020, 15:04 by Tian Xing, Timothy J Prior, Mark ElsegoodMark Elsegood, Igor E Soshnikov, Nina V Semikolenova, Konstantin P Bryliakov, Kai Chen, Carl Redshaw

Reaction of Na[VO(tBuO)4] (generated in-situ from VOCl3 and NaOtBu) with p-tertbutyltetrahomodioxacalix[6]areneH6 (L1 H6) afforded, after work-up (in MeCN), the mixed-metal complex [(VO)2(μO)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 L1 H6 afforded the product [VO(L2 )]2·4MeCN (8·4MeCN) (L2 = 2-(p-CH3-C6H4NCH)-4-tBu-C6H2O6-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-tertbutylcalix[6]areneH6) (III) and [(VO)2L8 H] (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.

Funding

Evolving a circular plastics ecomony

Engineering and Physical Sciences Research Council

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History

School

  • Science

Department

  • Chemistry

Published in

Catalysis Science & Technology

Volume

11

Issue

2

Pages

624 - 636

Publisher

Royal Society of Chemistry (RSC)

Version

VoR (Version of Record)

Publisher statement

This is an Open Access Article. It is published by Royal Society of Chemistry under the Creative Commons Attribution-NonCommercial 4.0 International Licence (CC BY-NC). Full details of this licence are available at: https://creativecommons.org/licenses/by-nc/4.0/

Acceptance date

19/11/2020

Publication date

2020-11-19

Copyright date

2021

ISSN

2044-4753

eISSN

2044-4761

Language

en

Depositor

Dr Mark Elsegood. Deposit date: 20 November 2020