In Situ Generation of Co(III) -Salen Complexes for Copolymerization of Propylene Oxide and CO2.

A simple admixture of Co(II) -salcy complexes with [Cp2 Fe(III) ]PF6 resulted in reproduction of the results with isolated Co(III) -salcy complexes in the copolymerization of epoxide and carbon dioxide. By using this in situ-generated active species with bis(triphenylphosphoranilydene)ammonium 2,4-dinitrophenolate, a para-methoxy-substituted Co-salcy complex was proven to be more active than the parent tert-butyl-substituted system. In contrast, the Co(II) -salcy complex substituted with the more strongly electron-donating NMe2 group did not show any activity for this copolymerization.