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 dicyclopentadienyl-methylzirconocene have revealed that the entire reaction path starting from the pi-coordinated ethylene-zirconocene complex up to and including propyl formation takes place in about 150 fs, which is unexpectedly fast. This observation suggests the absence of any significant barrier of activation, as confirmed by static energy minimizations. The Cp rings are very flexible. Starting from a reactant structure without alpha(-)agostic interaction, at T = 400 K such an interaction evolves during the course of the insertion reaction and before the propyl is formed. The product state exhibits gamma-H agostic interaction.