| Summary: | 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 (η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)]<sub>2</sub>ZrX<sub>2</sub> <b>1</b>/<b>1′</b> and O[SiMe<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)]<sub>2</sub>ZrX<sub>2</sub> <b>2</b>/<b>2′</b> (X = Cl, Me) with the activation by modified methylalymoxane MMAO-12 or by perfluoroalkyl borate [PhNMe<sub>2</sub>H][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] (NB<sup>F</sup>) in the presence and in the absence of organoaluminium compounds, Al(CH<sub>2</sub>CHMe<sub>2</sub>)<sub>3</sub> (TIBA) and/or Et<sub>2</sub>AlCl. Under the conditions providing a conventional mononuclear reaction mechanism, <b>1′</b> catalyzed dimerization with low selectivity, while <b>2′</b> initiated the formation of oligomers in equal mass ratio. The presence of TIBA and especially Et<sub>2</sub>AlCl 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-Al<sub>1</sub> and Zr-Al<sub>2</sub> mechanistic concepts.
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