Abstract A detailed study on the mechanism for the alternating copolymerization of cyclohexene oxide (CHO) and CO 2 mediated by an [Al{amino‐tri(phenolate)}]/NBu 4 I binary catalyst system was performed by using DFT‐based methods. Four potential mechanisms (one monometallic and three bimetallic) were considered for the first propagation cycle of the CHO/CO 2 copolymerization. The obtained Gibbs free energies provided a rationale for the relative high activity of a non‐covalent dimeric structure formed in situ and thus for the feasibility of a bimetallic mechanism to obtain polycarbonates quantitatively. Gibbs free energies also indicated that the alternating copolymerization was favored over the cyclic carbonate formation.