Di-Zinc-Aryl Complexes: CO2 Insertions and Applications in Polymerisation Catalysis

Charles Romain; Jennifer A Garden; Gemma Trott; Antoine Buchard; Andrew J P White; Charlotte K Williams

doi:10.1002/chem.201701013

Di-Zinc-Aryl Complexes: CO₂ Insertions and Applications in Polymerisation Catalysis

Chemistry. 2017 May 29;23(30):7367-7376. doi: 10.1002/chem.201701013. Epub 2017 May 5.

Authors

Charles Romain¹, Jennifer A Garden², Gemma Trott³, Antoine Buchard⁴, Andrew J P White¹, Charlotte K Williams^{3

1}

Affiliations

¹ Department of Chemistry, Imperial College London, London, SW7 2AZ, UK.
² EastCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
³ Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX2 3TA, UK.
⁴ Department of Chemistry, University of Bath, Bath, BA2 7AY, UK.

Abstract

Two new di-zinc-aryl complexes, [LZn₂ Ph₂ ] and [LZn₂ (C₆ F₅ )₂ ], coordinated by a diphenol tetraamine macrocyclic ligand have been prepared and fully characterised, including by single-crystal X-ray diffraction experiments. The complexes' reactivities with monomers including carbon dioxide, cyclohexene oxide, phthalic anhydride, isopropanol and phenol were investigated using both experimental studies and density functional theory calculations. In particular, [LZn₂ Ph₂ ] readily inserts carbon dioxide to form a carboxylate, at 1 bar pressure, whereas [LZn₂ (C₆ F₅ )₂ ] does not react. Under these conditions [LZn₂ Ph₂ ] shows moderate activity in the ring-opening copolymerisation of cyclohexene oxide/carbon dioxide (TOF=20 h^-1 ), cyclohexene oxide/phthalic anhydride (TOF=33 h^-1 ) and the ring-opening polymerisations of rac-lactide (TOF=99 h^-1 ) and ϵ-caprolactone (TOF=5280 h^-1 ).

Keywords: CO2 insertion; organozinc catalysts; reactivity studies; ring-opening copolymerisation; ring-opening polymerisation; zinc.