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

Ab-initio Molecular Dynamics simulations on ethylene insertion in a bridged di(cyclopentadienyl) 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 femto-seconds, which is unexpectedly fast, and suggesting the absence of any significant barrier of activation. Starting from a reactant structure without alpha-H 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.