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ToolsWalton, Mark J., Lancaster, Simon J. and Redshaw, Carl (2014) Highly selective and immortal magnesium calixarene complexes for the ring-opening polymerization of rac-lactide. ChemCatChem, 6 (7). pp. 1892-1898. ISSN 1867-3880
Full text not available from this repository. (Request a copy)Abstract
The lithiation of 1,3-dipropoxy-p-tert-butylcalix[4]arene (LH2) followed by reaction with nBuMgBr in THF resulted in the formation of the hetero-bimetallic complex [Li(THF)Mg(nBu)L] (1). By contrast, the treatment of tripropoxy-p-tert-butylcalix[4]arene (L′H) with nBu2Mg afforded a mononuclear complex [L′Mg(nBu)] (2). Single-crystal XRD studies revealed that in both structures the calix[4]arene adopts a cone conformation, and a Li cation resides in the cavity for 1. Both 1 and 2 were active for the ring-opening polymerisation of rac-lactide. Compound 2 displayed not only exceptional activity (100 equivalents, 3 min, 92 % conversion, BnOH, room temperature) but also high selectivity (probability to form an r dyad, Pr=0.85) and exhibited an immortal character in THF. Surprisingly, compound 2 also showed isotactic bias (Pr=0.30–0.36) and an immortal character if toluene was employed as the solvent; 2 D J-resolved 1H NMR spectroscopy was employed for the assignment of the stereoselectivity.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | calixarenes,heterometallic complexes,magnesium,nmr spectroscopy,ring-opening polymerization |
| Faculty \ School: | Faculty of Science > School of Chemistry Faculty of Science |
| UEA Research Groups: | Faculty of Science > Research Groups > Synthetic Chemistry (former - to 2017) |
| Depositing User: | Pure Connector |
| Date Deposited: | 21 Aug 2014 08:34 |
| Last Modified: | 16 Apr 2024 13:30 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/49971 |
| DOI: | 10.1002/cctc.201490040 |
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