Vanadyl calix[6]arene complexes: Synthesis, structural studies and ethylene homo-(co-)polymerization capability

Redshaw, Carl; Walton, Mark; Michiue, Kenji; Chao, Yimin; Walton, Alex; Elo, Pertti; Sumerin, Victor; Jiang, Chengying; Elsegood, Mark R. J.

Abstract

Treatment of p-tert-butylcalix[6]areneH₆ (L⁶H₆) with in situ [LiVO(Ot-Bu)₄] afforded, after work-up, the dark green complex [Li(MeCN)₄][V₂(O)₂Li(MeCN)(L⁶H₂)₂]·8MeCN (1·8MeCN). On one occasion, the reaction led to the formation of a mixture of products, the bulk of which differing from 1 only in the amount of solvate, viz.2·9.67MeCN. The second minor, yellow product has the formula {[(VO₂)₂(L⁶H₂)(Li(MeCN)₂)₂]·2MeCN}n (3·2MeCN), and comprises a 1D polymeric structure with links through the L⁶H₂ ligand and Li₂O₂ units. When the reverse order of addition was employed such that lithium tert-butoxide (7.5 equivalents) was added to L⁶H₆, and subsequently treated with VOCl₃ (2 equiv.), the complex {[VO(THF)][VO(μ-O)]₂Li(THF)(Et₂O)][L⁶]}·2Et₂O·0.5THF (4·2Et₂O·0.5THF), which contains a trinuclear motif possessing a central, octahedral vanadyl centre linked via oxo bridges to two tetrahedral (C₃v) vanadyl centres, was isolated. The calix[6]arene in 4 is severely twisted and adopts a ‘down, down, down, down, out, out’ conformation. Use of excess lithium tert-butoxide led to a complex very similar to 4, differing only in the solvent of crystallization, namely 5·Et₂O·2THF. The ability of 1 and 5 to act as pre-catalysts for ethylene polymerization in the presence of a variety of co-catalysts and under various conditions has been investigated. Co-polymerization of ethylene with propylene and with 1-hexene have also been conducted; results are compared versus VO(OEt)Cl₂.

Citation

Redshaw, C., Walton, M., Michiue, K., Chao, Y., Walton, A., Elo, P., Sumerin, V., Jiang, C., & Elsegood, M. R. J. (2015). Vanadyl calix[6]arene complexes: Synthesis, structural studies and ethylene homo-(co-)polymerization capability. Dalton Transactions : an international journal of inorganic chemistry, 44(27), 12292-12303. https://doi.org/10.1039/c5dt00376h

• Journal Article Type: Article
• Acceptance Date: Mar 2, 2015
• Online Publication Date: Mar 3, 2015
• Publication Date: Jul 21, 2015
• Deposit Date: Jul 22, 2015
• Publicly Available Date: Jul 22, 2015
• Journal: Dalton transactions
• Print ISSN: 1477-9226
• Electronic ISSN: 1477-9234
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 44
• Issue: 27
• Pages: 12292-12303
• DOI: https://doi.org/10.1039/c5dt00376h
• Keywords: Vanadyl; Calix[6]arene; Ethylene polymerization; Ethylene/1-hexene co-polymerization; Ethylene/propylene co-polymerization; Homogenous; Heterogeneous
• Public URL: https://hull-repository.worktribe.com/output/376739
• Publisher URL: http://pubs.rsc.org/en/Content/ArticleLanding/2015/DT/C5DT00376H#!divAbstract
• Additional Information: Author's accepted manuscript of article which has been published in: Dalton transactions, 2015, v.44, issue 27.
• Contract Date: Jul 22, 2015