Theoretical Study on Epoxide Ring-opening in CO2/Epoxide Copolymerization Catalyzed by Bifunctional Salen-Type Cobalt(III) Complexes: Influence of Stereoelectronic Factors

Propylene oxide (PO) binding and ring-opening reaction with the bifunctional CO2/epoxide copolymerization catalyst, based on Co(III)-salcy complex including two quaternary ammonium salts n-butyl substituents (N+-chains) were investigated by Density Functional Theory (DFT) calculations compared model systems without N+-chains. The importance of different possible stereoisomers stereoselectivity these processes for (S)- (R)-enantiomers PO considered. To explore conformational space real a approach, developed previously was applied. directly demonstrate that PO-ring opening proceeds preferentially in trans catalysts’ configuration no participation cis-β isomers is viable; nucleophilic attack at methylene-carbon atom preferred over methine-carbon atom. For (S,S)-configuration cyclohexane, results indicate preference (R)-PO (S)-PO (ca. 6:5). Concerning resulting from orientation N+-chains groups structures participate (R)-PO, (S)-PO. high population nonreactive complexes may be key factor responsible decreasing activity analyzed catalyst epoxide reaction.