Coupling reactions of CO2 with neat epoxides catalyzed by PPN salts to yield cyclic carbonates.

The off-the-shelf reagent PPN+Cl- and PPN-manganese carbonylates [PPN]+[Mn(CO)4L]- (L = CO, PPh3) are good catalysts for the coupling reactions of CO2 with neat epoxides without the use of organic solvents to afford cyclic carbonates. PPN salts with weak nucleophilic anions such as PPN+BF4- and PPN+OTf- are, however, inactive for the coupling reactions.