Iron-corrole complexes were found to copolymerize epoxides with CO2. The first iron-catalyzed propylene oxide/CO2 copolymerization has been accomplished. Moreover, the glycidyl phenyl ether (GPE)/CO2 copolymerization with this catalyst provided a crystalline material as a result of the isotactic poly(GPE) moiety.

Mechanistic studies were conducted to estimate (1) catalytic activity for PPC, (2) PPC/CPC selectivity, and (3) PPC/PPO selectivity for the metal-catalyzed copolymerization of propylene oxide with carbon dioxide [PPC: poly(propylene carbonate); CPC = cyclic propylene carbonate; PPO: poly(propylene oxide)]. Density functional theory (DFT) studies demonstrated that the ΔG(crb) - ΔG(epx) value should be an effective indicator for the catalytic activities [ΔG(epx): dissociation energy of ethylene oxide from the epoxide-coordinating metal complex; ΔG(crb): dissociation energy of methyl carbonate from the metal-carbonate complex]. In addition, metal complexes with a subthreshold ΔG(epx) value were found to show low PPC/CPC selectivity. The PPC/PPO selectivity was related to the ΔG(alk) - ΔG(epx) value and steric environment around the metal center (ΔG(alk): dissociation energy of alkoxide ligand from the metal center). Based on the mechanistic studies, two metal complexes were designed and applied to the copolymerization to support validity of these indicators. The results presented here should be useful for brand-new catalyst candidates since these indicators can be easily calculated by DFT method without computing transition states.

Manganese-corrole complexes in combination with a co-catalyst [PPN]X ([PPN](+)=bis(triphenylphosphoranylidene)iminium) were found to be new versatile catalysts for the polymerization of epoxides, copolymerization of epoxides with CO2, and copolymerization of epoxides with cyclic anhydrides affording a wide range of polymeric materials. This work should allow the synthesis of new types of improved innovative (co)polymers with original properties and would clearly increase the number of applications for polyesters, polycarbonates, and polyethers.