Loughborough University
Leicestershire, UK
LE11 3TU
+44 (0)1509 263171
Loughborough University

Loughborough University Institutional Repository

Please use this identifier to cite or link to this item: https://dspace.lboro.ac.uk/2134/18645

Title: Tetraphenolate niobium and tantalum complexes for the ring opening polymerization of epsilon-caprolactone
Authors: Al-Khafaji, Yahya
Sun, Xinsen
Prior, Timothy J.
Elsegood, Mark R.J.
Redshaw, Carl
Issue Date: 2015
Publisher: © The Royal Society of Chemistry
Citation: AL-KHAFAJI, Y. ...et al., 2015. Tetraphenolate niobium and tantalum complexes for the ring opening polymerization of epsilon-caprolactone. Dalton Transactions, 44(27), pp.12349-12356.
Abstract: Reaction of the pro-ligand α,α,α’,α’-tetra(3,5-di-tert-butyl-2-hydroxyphenyl-p-)xylene-para-tetraphenol (p-L1H4) with two equivalents of [NbCl5] in refluxing toluene afforded, after work-up, the complex {[NbCl3(NCMe)]2(μ-p-L1)}·6MeCN (1·6MeCN). When the reaction was conducted in the presence of excess ethanol, the orange complex {[NbCl2(OEt)(NCMe)]2(μ-p-L1)}·312 MeCN·0.614toluene (2·312 MeCN·0.614toluene) was formed. A similar reaction using [TaCl5] afforded the yellow complex {[TaCl2(OEt)(NCMe)]2(μ-p-L1)}·5MeCN (3·5MeCN). In the case of the meta pro-ligand, namely α,α,α’,α’tetra (3,5-di-tert-butyl-2-hydroxyphenyl-m-)xylene-meta-tetraphenol (m-L2H4) only the use of [Nb(O)- Cl3(NCMe)3] led to the isolation of crystalline material, namely the orange bis-chelate complex {[Nb-(NCMe)Cl(m-L2H2)2]}·312 MeCN (4·312MeCN) or {[Nb(NCMe)Cl(m-z2H2)2]}·5MeCN (4·5MeCN). The molecular structures of 1–4 and the tetraphenols L1H4 and m-L2H4·2MeCN have been determined. Complexes 1–4 have been screened as pre-catalysts for the ring opening polymerization of ε-caprolactone, both with and without benzyl alcohol or solvent present, and at various temperatures; conversion rates were mostly excellent (>96%) with good control either at >100 °C over 20 h (in toluene) or 1 h (neat).
Description: This paper is in closed access.
Version: Accepted for publication
DOI: 10.1039/c5dt00272a
URI: https://dspace.lboro.ac.uk/2134/18645
Publisher Link: http://dx.doi.org/10.1039/c5dt00272a
ISSN: 1477-9226
Appears in Collections:Closed Access (Chemistry)

Files associated with this item:

File Description SizeFormat
C5DT00272A_proof.pdfAccepted version1.67 MBAdobe PDFView/Open


SFX Query

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.