Synthesis of polycarbonates using a cationic zirconocene complex

The cationic alkyl zirconocene complex Cp₂Zr⁺Me[CH₃B⁻(C₆F₅)₃] is found to initiate the ringopening polymerization of 1,5,7,11-tetraoxaspiro[5,5]undecane under mild condition to give poly(oxypropylenepropylenecarbonate) with low polydispersity. The rate of the polymerization is first-order with respect to monomer and catalyst concentration. At high monomer concentration, the initial rate of polymerization becomes zero-order with respect to monomer concentration.