Structural studies of Schiff-base [2 + 2] macrocycles derived from 2,2′-oxydianiline and the ROP capability of their organoaluminium complexes

Yang, Wenxue; Zhao, Ke-Qing; Prior, Timothy J.; Hughes, David L.; Arbaoui, Abdessamad; Elsegood, Mark R. J.; Redshaw, Carl

Abstract

The molecular structures of a number of solvates of the [2+2] Schiff-base macrocycles {[2-(OH)-5-(R)-C₆H₂-1,3-(CH)₂][O(2-C₆H₄N)₂]}₂ (R = Me L¹H₂, tBu L²H₂, Cl L³H₂), formed by reacting 2,6-dicarboxy-4-R-phenol with 2,2/-oxydianiline (2-aminophenylether), (2-NH₂C₆H₄)₂O, have been have been determined. Reaction of LnH₂ with two equivalents of AlR/₃ (R/ = Me, Et) afforded dinuclear alkylaluminium complexes [(AlR/₂)₂L1-3] (R = R/ = Me (1), R = tBu, R/ = Me (2), R = Cl, R/ = Me (3), R = Me, R/ = Et (4), R = tBu, R/ = Et (5), R = Cl, R/ = Et (6)). For comparative studies, reactions of two equivalents of AlR/₃ (R/ = Me, Et) with the macrocycle derived from 2,2/-ethylenedianiline and 2,6-dicarboxy-R-phenols (R = Me L⁴H₂, tBu L⁵H₂) were conducted; the complexes [(AlMe)(AlMe2)L⁵]·21/4MeCN (7·21/4MeCN) and [(AlEt₂)₂L⁴] (8) were isolated. Use of limited AlEt₃ with L³H₂ or L⁵H₂ afforded mononuclear bis(macrocyclic) complexes [Al(L³)(L³H)]·4toluene (9·4toluene) and [Al(L⁵)(L⁵H)]·5MeCN (10·5MeCN), respectively. Use of four equivalents of AlR/₃ led to transfer of alkyl groups and isolation of the complexes [(AlR/₂ )₄L1′-3′] (R = L²′, R/ = Me (11); L³′, R/ = Me (12); L¹′, R/ = Et (13); L²′, R/ = Et (14); L³′, R/ = Et (15)), where L1′-3′ is the macrocycle resulting from double alkyl transfer to imine, namely {[2-(O)-5-(R)C₆H₂-1-(CH)-3-(C(R/)H][(O)(2-(N)-2/-C₆H₄N)₂]}₂. Molecular structures of complexes 7·21/4MeCN, 8, 9·4toluene, 10·5MeCN and 11·1¾toluene·11/4hexane are reported. These complexes act as catalysts for the ring opening polymerisation (ROP) of epsilon-caprolactone and rac-lactide; high conversions were achieved over 30 mins at 80 oC for epsilon-caprolactone, and 110 oC over 12 h for rac-lactide.

Citation

Yang, W., Zhao, K.-Q., Prior, T. J., Hughes, D. L., Arbaoui, A., Elsegood, M. R. J., & Redshaw, C. (2016). Structural studies of Schiff-base [2 + 2] macrocycles derived from 2,2′-oxydianiline and the ROP capability of their organoaluminium complexes. Dalton Transactions : an international journal of inorganic chemistry, 45(30), 11990-12005. https://doi.org/10.1039/c6dt01997h

• Journal Article Type: Article
• Acceptance Date: Jun 17, 2016
• Online Publication Date: Jun 20, 2016
• Publication Date: Aug 14, 2016
• Deposit Date: Jun 24, 2016
• Publicly Available Date: Jun 24, 2016
• Journal: Dalton transactions
• Print ISSN: 1477-9226
• Electronic ISSN: 1477-9234
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 45
• Issue: 30
• Pages: 11990-12005
• DOI: https://doi.org/10.1039/c6dt01997h
• Keywords: Schiff-base [2+2] macrocycles, 2,2/-oxydianiline , organoaluminium complexes
• Public URL: https://hull-repository.worktribe.com/output/474191
• Publisher URL: http://pubs.rsc.org/en/Content/ArticleLanding/2016/DT/C6DT01997H#!divAbstract
• Additional Information: : This document is Similarity Check deposited; : Supplementary Information; : Crystal Structure Data; : The Royal Society of Chemistry has an exclusive publication licence for this journal; OPEN ACCESS: This article is freely available. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (CC BY 3.0); : Single-blind; : Received 18 May 2016; Accepted 17 June 2016; Accepted Manuscript published 20 June 2016; Advance Article published 7 July 2016; Version of Record published 26 July 2016
• Contract Date: Jun 24, 2016