Perfluoroaryl Zinc Catalysts Active in Cyclohexene Oxide Homopolymerization and Alternating Copolymerization with Carbon Dioxide

The zinc complex Zn(C6F5)(2)(toluene) (1) behaves as a very active and selective catalyst in cyclohexene oxide (CHO) polymerization to produce poly(cyclohexene oxide) (PCHO) by the trans-ring-opening of CHO with remarkable TOF values at room temperature. The ring-opening copolymerization (ROCOP) of CO2 with CHO catalysed by 1 yields poly(cyclohexene carbonate) (PCHC) when using benzyl alcohol (BnOH) as an initiator at 120 degrees C. The H-1 NMR monitoring of the in situ reaction of 1 with BnOH highlighted the formation of the dinuclear species [(C6F5)(2)Zn-2(BnO)(2)] (2) that was isolated and found an active catalyst in the ROCOP of CO2 with CHO in the absence of initiators. Interestingly, PCHCs by 2 in solventless conditions show polydispersity index (M-w/M-n) values close to 2, corresponding to those expected for a single-site catalyst; on the contrary, a broader polydispersity index of the polymer products was found in toluene solution, suggesting the formation of new zinc catalysts during the polymerization reaction.

Automated summary

The zinc complex demonstrates high catalytic activity and selectivity in the polymerization of cyclohexene oxide (CHO), producing poly(cyclohexene oxide) (PCHO) with remarkable TOF values at room temperature. The complex also catalyzes the ring-opening copolymerization of CO2 with CHO, yielding poly(cyclohexene carbonate) (PCHC) with high polydispersity index values. The formation of dinuclear species during the reaction highlights potential new zinc catalysts that impact the polymerization process.