DFT Study of Halide-Free Mechanism of the CO2 Cycloaddition onto Epoxide by [PW11O39{Zn(H2O)}]5−: Evidences for the Formation of Hydrogencarbonate Intermediates

The intertwined experimental and theoretical study of the reaction of CO₂ with styrene oxide in the presence of the tetraoctylammonium salt of [PW₁₁O₃₉Zn^II(H₂O)]⁵⁻ evidences the carbonic anhydrase-like role of the polyoxometalate center in catalyzing the reaction. We computationally propose a reaction pathway involving the transient formation of an HCO₃⁻ moiety involved in the stepwise conversion of the epoxide into a cyclic carbonate. These calculations enabled us to improve the catalytic reactivity of these polyoxometalates by introducing HCO₃⁻ as a co-catalyst in the cycloaddition reactions of CO₂ on a variety of epoxides.