Issue 27, 2008
From the journal:

Dalton Transactions

Lanthanide chloride complexes of amine-bis(phenolate) ligands and their reactivity in the ring-opening polymerization of ε-caprolactone†

Charlotte E. Willans,a   Mikhail A. Sinenkov,b   Georgy K. Fukin,b   Kristina Sheridan,c   Jason M. Lynam,a   Alexander A. Trifonov*b  and  Francesca M. Kerton*c  

* Corresponding authors

a Department of Chemistry, University of York, Heslington, York, UK

b G. A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Tropina str. 49, Nizhny Novgorod, Russia
E-mail: trif@imoc.sinn.ru

c Department of Chemistry, Memorial University of Newfoundland, St. John's, Canada
E-mail: fkerton@mun.ca
Fax: +1-709-7373702

Abstract

Reaction of two equivalents of n-BuLi with sterically demanding amine-bis(phenol) compounds, H2O2NN′R (Me2NCH2CH2N{CH2-3,5-R2-C6H2OH}2; R = t-Bu or t-Pe (tert-pentyl)) yields isolable lithium complexes, Li2(O2NN′R), in good yields. Upon reaction with one equivalent of LnCl3(THF)x, the lithium salts afford rare earth amine-phenolate chloride complexes in good yields, Ln(O2NN′R)Cl(THF); Ln = Y, Yb, Ho, Gd, Sm, Pr. Crystals of Y(O2NN′t-Bu)Cl(THF), 1, and Sm(O2NN′t-Bu)Cl(DME), 2, suitable for single crystal X-ray crystallographic analysis were obtained. In contrast to previously reported [{Gd(O2NN′t-Pe)(THF)(μ-Cl)}2] and related La and Sm complexes, these species are monomeric. 1 contains Y in a distorted octahedral environment bonded to two amine, two phenolate, one THF and one chloride donor. 2 contains Sm in a distorted capped trigonal prismatic environment bonded to two amine, two phenolate, two DME oxygens and one chloride donor. The Ln(O2NN′t-Pe)Cl(THF) complexes were active initators for the controlled ring-opening polymerization of ε-caprolactone with a tendency to form low molecular weight cyclic polyesters (Mn 3000–5000). The conversion rates, although slower than related amido and alkyl species, were different for monomeric and dimeric initiators. The size of the metal centre also affected the conversions and the molecular weights achieved.

Graphical abstract: Lanthanide chloride complexes of amine-bis(phenolate) ligands and their reactivity in the ring-opening polymerization of ε-caprolactone

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Article information

DOI
https://doi.org/10.1039/B802219D
Article type
Paper
Submitted
08 Feb 2008
Accepted
16 Apr 2008
First published
20 May 2008

Dalton Trans., 2008, 3592-3598

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Lanthanide chloride complexes of amine-bis(phenolate) ligands and their reactivity in the ring-opening polymerization of ε-caprolactone

C. E. Willans, M. A. Sinenkov, G. K. Fukin, K. Sheridan, J. M. Lynam, A. A. Trifonov and F. M. Kerton, Dalton Trans., 2008, 3592 DOI: 10.1039/B802219D

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