Mono- and tetra-nuclear copper complexes bearing bis(imino)phenoxide derived ligands: catalytic evaluation for benzene oxidation and ROP of ε-caprolactone

Wang, Xue; Zhao, Ke-Qing; Elsegood, Mark R. J.; Prior, Timothy J.; Liu, Xiaoming; Wu, Li; Sanz, Sergio; Brechin, Euan K.; Redshaw, Carl

Abstract

Complexes of the type [Cu(L)₂] (1) and [Cu₄L₂(μ₄-O)(OAc)₄] (2) have been obtained from the reaction of the phenoxydiimine 1,3-(2,6-R²₂C₆H₃N=CH)₂-5-R¹ C₆H₂OH-2 (LH) (where R¹ = Me, tBu, Cl; R² = Me, iPr) with copper(II) acetate [Cu(OAc)₂]; changing the molar ratio of the reactants affords differing amounts of 1 or 2. Reaction of the parent dialdehyde [1,3-(CHO)₂-5-MeC₆H₂OH-2] with [Cu(OAc)₂] in the presence of Et₃N afforded, following work-up, a polymeric chain (3) comprising {[Cu₂(OAc)₄]OAc}n, HNEt₃ and MeCN. The crystal structures of 1 (R¹ = Me, R² = iPr 1a; R¹ = Cl, R² = iPr 1b), 2 (R¹ = Me, R² = Me 2a; R¹ = Me, R² = iPr 2b; R¹ = tBu, R² = Me 2c; R¹ = Cl, R² = Me 2d; R¹ = Cl, R² = iPr 2e; R¹ = tBu, R² = iPr 2f) and 3 are reported (synchrotron radiation was necessary for 3). The magnetic properties of the cluster 2b are presented. Complexes of type 2 and 3 were screened for the ring opening polymerization (ROP) of ε-caprolactone, with or without benzyl alcohol present, under a variety of conditions, however only trace polymer was isolated. The electrochemistry of all complexes was also investigated, together with their ability to catalyze benzene oxidation (using hydrogen peroxide); although low conversions were observed, the tetra-nuclear complexes exhibited excellent selectivity.

Citation

Wang, X., Zhao, K.-Q., Elsegood, M. R. J., Prior, T. J., Liu, X., Wu, L., Sanz, S., Brechin, E. K., & Redshaw, C. (2015). Mono- and tetra-nuclear copper complexes bearing bis(imino)phenoxide derived ligands: catalytic evaluation for benzene oxidation and ROP of ε-caprolactone. RSC advances, 5(71), 57414-57424. https://doi.org/10.1039/c5ra08696e

• Journal Article Type: Article
• Acceptance Date: Jun 8, 2015
• Online Publication Date: Jun 8, 2015
• Publication Date: Jan 1, 2015
• Deposit Date: Jul 22, 2015
• Publicly Available Date: Jul 22, 2015
• Journal: RSC advances
• Print ISSN: 2046-2069
• Electronic ISSN: 2046-2069
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 5
• Issue: 71
• Pages: 57414-57424
• DOI: https://doi.org/10.1039/c5ra08696e
• Keywords: Ring opening polymerization , Bis(imino)phenoxide derived ligands, ε-caprolactone, Benzene oxidation
• Public URL: https://hull-repository.worktribe.com/output/376772
• Publisher URL: http://pubs.rsc.org/en/Content/ArticleLanding/2015/RA/C5RA08696E#!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: The accepted version of this article will be made freely available after a 12 month embargo period; : Single-blind; : Received 10 May 2015; Accepted 8 June 2015; Accepted Manuscript published 8 June 2015; Version of Record published 1 July 2015
• Contract Date: Jul 22, 2015