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1H and 2H NMR Spectroscopic Characterization of Heterobinuclear Ion Pairs Formed upon the Activation of Bis(imino)pyridine Vanadium(III) Precatalysts with AlMe3/[Ph3C]+[B(C6F5)4] and MAO

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journal contribution
posted on 27.05.2014, 00:00 by Igor E. Soshnikov, Nina V. Semikolenova, Artem A. Antonov, Konstantin P. Bryliakov, Vladimir A. Zakharov, Evgenii P. Talsi
Until recently, attempts to characterize vanadium­(III) species formed upon the activation of vanadium­(III) α-olefin polymerization precatalysts with AlMe3/[Ph3C]+[B­(C6F5)]4 or MAO were unsuccessful. In this contribution, 1H and 2H NMR spectroscopy was used to study the activation of bis­(imino)­pyridine vanadium­(III) chloride LVIIICl3 {L = [2,6-(ArNCMe)2C5H3N], Ar = 2,6-iPr2C6H3; 2,6-Me2C6H3; 2,4,6-Me3C6H2; 3,5-F2C6H3} with AlMe3/[Ph3C]+[B­(C6F5)]4 or MAO. Formation of heterobinuclear ion pairs of the type [L­(R)­VIII(μ-R)2AlMe2]+[A] ([A] = [B­(C6F5)]4 or [MeMAO], R = Me or Cl) was observed, which are the most likely direct precursors of active sites of ethylene polymerization.