Theoretical study on effects of substituent, ligand, and metal on Pd-catalyzed polymerization of norbornene

► The mechanism of Pd-catalyzed polymerization of norbornene is elucidated. ► Insertion of the second norbornene monomer is the slowest step of initiation. ► The activation barrier of initiation is much higher than that of propagation. ► The resting state is a Pd complex with two norbornene and the growing chain. ► The rate of initiation of trichloro-allyl Pd catalyst is slower than propagation.