Toward the Prediction of Activity in the Ethylene Polymerisation of ansa-Bis(indenyl) Zirconocenes: Effect of the Stereochemistry and Hydrogenation of the Indenyl Moiety

Design and prediction of high potent ansa-zirconocene catalyst for olefin polymerizations: combined DFT calculations and QSPR approach

Density functional calculations were carried out to predict activities, regio- and stereoselectivity, and to design new ansa-zirconocene catalysts for olefin polymerizations.

Experimental and Theoretical Study of Zirconocene-Catalyzed Oligomerization of 1-Octene

Zirconocene-catalyzed coordination oligomerization of higher α-olefins is of theoretical and practical interest. In this paper, we present the results of experimental and theoretical study of α-olefin oligomerization, catalyzed by (η⁵-C₅H₅)]₂ZrX₂1/1′ and O[SiMe₂(η⁵-C₅H₄)]₂ZrX₂2/2′ (X = Cl, Me) with the activation by modified methylalymoxane MMAO-12 or by perfluoroalkyl borate [PhNMe₂H][B(C₆F₅)₄] (NB^F) in the presence and in the absence of organoaluminium compounds, Al(CH₂CHMe₂)₃ (TIBA) and/or Et₂AlCl. Under the conditions providing a conventional mononuclear reaction mechanism, 1′ catalyzed dimerization with low selectivity, while 2′ initiated the formation of oligomers in equal mass ratio. The presence of TIBA and especially Et₂AlCl resulted in an increase of the selectivity of dimerization. Quantum chemical simulations of the main and side processes performed at the M-06x/ DGDZVP level of the density functional theory (DFT) allowed to explain experimental results involving traditional mononuclear and novel Zr-Al₁ and Zr-Al₂ mechanistic concepts.