Mechanistic Aspects of a Highly Active Dinuclear Zinc Catalyst for the Co-polymerization of Epoxides and CO2

Abstract

The dinuclear zinc complex reported by us is to date the most active zinc catalyst for the co-polymerization of cyclohexene oxide (CHO) and carbon dioxide. However, co-polymerization experiments with propylene oxide (PO) and CO2 revealed surprisingly low conversions. Within this work, we focused on clarification of this behavior through experimental results and quantum chemical studies. The combination of both results indicated the formation of an energetically highly stable intermediate in the presence of propylene oxide and carbon dioxide. A similar species in the case of cyclohexene oxide/CO2 co-polymerization was not stable enough to deactivate the catalyst due to steric repulsion.

Keywords: carbon dioxide; co-polymerization; density functional calculations; epoxides; zinc.