AB-INITIO MOLECULAR-DYNAMICS STUDY OF METALLOCENE-CATALYZED ETHYLENE POLYMERIZATION

This is the first report on the simulation of the full dynamics, at a quantum mechanical level, of a catalytic chemical reaction. Ab initio molecular dynamics simulations on ethylene insertion in a bridged dicy clopentadienyl-methylzirconocene have revealed that the entire reactio n path starting from the pi-coordinated ethylene-zirconocene complex u p to and including propyl formation takes place in about 150 fs, which is unexpectedly fast. This observation suggests the absence of any si gnificant barrier of activation, as confirmed by static energy minimiz ations. The Cp rings are very flexible. Starting from a reactant struc ture without alpha(-)agostic interaction, at T = 400 K such an interac tion evolves during the course of the insertion reaction and before th e propyl is formed. The product state exhibits gamma-H agostic interac tion.