TY - JOUR
T1 - Di-cobalt(ii) catalysts for the copolymerisation of CO2 and cyclohexene oxide: support for a dinuclear mechanism?
AU - Kember, Michael R.
AU - Jutz, Fabian
AU - Buchard, Antoine
AU - White, Andrew J. P.
AU - Williams, Charlotte K.
PY - 2012/4/1
Y1 - 2012/4/1
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=84858018612&partnerID=8YFLogxK
UR - http://dx.doi.org/10.1039/C2SC00802E
U2 - 10.1039/C2SC00802E
DO - 10.1039/C2SC00802E
M3 - Article
SN - 2041-6520
VL - 3
SP - 1245
EP - 1255
JO - Chemical Science
JF - Chemical Science
IS - 4
ER -