Issue 1, 2020

Heterodinuclear complexes featuring Zn(ii) and M = Al(iii), Ga(iii) or In(iii) for cyclohexene oxide and CO2 copolymerisation

Abstract

The ring opening copolymerisation of CO2 and epoxides is a useful means to valorise waste emissions and to reduce pollution in polymer manufacturing. Heterodinuclear catalysts, particularly those of Zn(II)/Mg(II), have shown better performances than homodinuclear analogues in this reaction. As part of on-going efforts to better understand the catalytic synergy, this work describes a series of heterodinuclear complexes, combining Zn(II) with a metal from Group 13 (M = Al(III), Ga(III) or In(III)). The complexes are synthesised from a symmetrical macrocyclic ligand in high yields via sequential metalation steps and are the thermodynamic reaction products. The Zn(II)/Group 13 complexes are effective homogeneous catalysts for the ring opening copolymerisation (ROCOP) of cyclohexene oxide at 1 bar pressure of carbon dioxide, but all show inferior performances compared to the di-zinc analogue. The CO2 uptake into the polymer increases in the order Al(III) < Ga(III) < In(III) which is attributed to lower Lewis acidity heavier Group 13 homologues showing a reduced tendency to form ether linkages. Concurrently, polycarbonate activity increases down the Group 13 series consistent with weaker metal–oxygen bonds which show enhanced lability to insertion reactions.

Graphical abstract: Heterodinuclear complexes featuring Zn(ii) and M = Al(iii), Ga(iii) or In(iii) for cyclohexene oxide and CO2 copolymerisation

Supplementary files

Article information

Article type
Paper
Submitted
15 Jul 2019
Accepted
22 Oct 2019
First published
09 Dec 2019
This article is Open Access
Creative Commons BY license

Dalton Trans., 2020,49, 223-231

Heterodinuclear complexes featuring Zn(II) and M = Al(III), Ga(III) or In(III) for cyclohexene oxide and CO2 copolymerisation

A. C. Deacy, C. B. Durr and C. K. Williams, Dalton Trans., 2020, 49, 223 DOI: 10.1039/C9DT02918D

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