Naeimeh Bahri-Laleh - Department of Polymerization Engineering, Iran Polymer and Petrochemical Institute, P.O. Box۱۴۹۶۵/۱۱۵, Tehran, Iran.
Laura Falivene - Department of Chemistry and Biology, University of Salerno, Via Papa Giovanni Paolo II, FiscianoI-۸۴۰۸۴, Italy.
Luigi Cavallo - Department of Chemistry and Biology, University of Salerno, Via Papa Giovanni Paolo II, FiscianoI-۸۴۰۸۴, Italy

In this study we have tested the ability of a standard DFT computational protocol to reproduce the experimentally obtained stereoselectivity of 26 different C2-symmetric zirconocene catalysts active in propylene polymerization. The catalysts werechosen for their relevance in metallocene catalyzed polymerization of propylene. To this end, primary insertion of both si- andre-propylene enantiofaces into the Zr-CH2-CH(CH3)2 bond was considered to simulate the growing chains step. The energydifference between these two transition states, ΔEre-si, was taken as a measure of the stereoselectivity (pentad: mmmm%) ofdifferent catalysts. The results clearly indicated that there was a good agreement between ΔEre-si and the mmmm% values, sothat greater ΔEre-si could correspond to higher mmmm%. A model was ftted to the experimentally obtained mmmm% againsttheoretical ΔEre-si. The coeffcient of determination (R2) of the resultant plot was 0.9793, which indicated a good accuracy of themodel. Finally, to quantify the steric role of the studied ligands in the observed stereoselectivity, the analysis of the buried volume(VBur) and of the steric maps was performed for two representative complexes. The images revealed that a greater asymmetriclocalization of the %VBur around the metal center led to a higher mmmm% in the resultant polymer. Polyolefns J (2014) 1:139-146

Metallocene catalysts, DFT, Molecular simulation, Setereoselective polymerization, Isotactic polypropylene