Issue 4, 2012

Di-cobalt(ii) catalysts for the copolymerisation of CO2 and cyclohexene oxide: support for a dinuclear mechanism?

Abstract

The synthesis and characterisation of a series of di-cobalt(II) halide complexes, coordinated by a macrocyclic ancillary ligand, is reported. The new complexes show excellent activity as catalysts for the copolymerisation of cyclohexene oxide (CHO) and carbon dioxide, under just 1 atmosphere of pressure of CO2. The complexation of a series of co-ligands has been investigated, including nucleophiles of varying strength, (4-dimethylaminopyridine (DMAP), N-methylimidazole (MeIm) and pyridine), and the anionic donor (Cl) from bulky ammonium salts, ([HNEt3]Cl, [DBU-H]Cl and [MTBD-H]Cl). Structure–activity studies of the complexes, including X-ray crystallography data, in conjunction with mass spectrometry experiments, are used to support a proposed dinuclear mechanism. The initial rate of copolymerisation, determined using in situ attenuated total reflectance infrared (ATR-IR) spectroscopy, shows a first order dependence on both the catalyst concentration and the concentration of cyclohexene oxide. A dinuclear mechanism is proposed in which catalysis occurs on the convex face of the molecule, leading to chain growth from a single site.

Graphical abstract: Di-cobalt(ii) catalysts for the copolymerisation of CO2 and cyclohexene oxide: support for a dinuclear mechanism?

Supplementary files

Article information

Article type
Edge Article
Submitted
14 Oct 2011
Accepted
10 Jan 2012
First published
06 Feb 2012

Chem. Sci., 2012,3, 1245-1255

Di-cobalt(II) catalysts for the copolymerisation of CO2 and cyclohexene oxide: support for a dinuclear mechanism?

M. R. Kember, F. Jutz, A. Buchard, A. J. P. White and C. K. Williams, Chem. Sci., 2012, 3, 1245 DOI: 10.1039/C2SC00802E

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