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Zirconocene allyl complexes : dynamics in solution, reaction with aluminum alkyls, B(C 6 F 5) 3 -induced propene insertion, and density-functional calculations on possible formation and reaction pathways

Zirconocene allyl complexes : dynamics in solution, reaction with aluminum alkyls, B(C 6 F 5) 3 -induced propene insertion, and density-functional calculations on possible formation and reaction pathways

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LIEBER, Susanna, Marc-Heinrich PROSENC, Hans-Herbert BRINTZINGER, 2000. Zirconocene allyl complexes : dynamics in solution, reaction with aluminum alkyls, B(C 6 F 5) 3 -induced propene insertion, and density-functional calculations on possible formation and reaction pathways. In: Organometallics. 19(4), pp. 377-387. ISSN 0276-7333. eISSN 1520-6041

@article{Lieber2000Zirco-23737, title={Zirconocene allyl complexes : dynamics in solution, reaction with aluminum alkyls, B(C 6 F 5) 3 -induced propene insertion, and density-functional calculations on possible formation and reaction pathways}, year={2000}, doi={10.1021/om9906058}, number={4}, volume={19}, issn={0276-7333}, journal={Organometallics}, pages={377--387}, author={Lieber, Susanna and Prosenc, Marc-Heinrich and Brintzinger, Hans-Herbert} }

Organometallics ; 19 (2000), 4. - S. 377-387 Lieber, Susanna Lieber, Susanna eng Prosenc, Marc-Heinrich The complex (C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>Zr(Me)(methallyl) (1) was prepared and studied as a model for Zr-bound allyl species which are likely to arise in zirconocene-based polymerization systems. 1 undergoes allyl−alkyl exchange with trimethyl aluminum (TMA) or with methyl alumoxane (MAO) at rates that are proportional to the Al concentration, but remain 1−2 orders of magnitude below those of typical olefin insertions. Its perfluorotriphenylborane adduct 2, i.e., the contact ion pair (C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>Zr(methallyl)<sup>+</sup>H<sub>3</sub>CB(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub><sup>-</sup>, has been characterized with regard to the rearrangement dynamics of its allyl ligand. Propene reacts with 2, at rates which are substantially lower again than those of cationic Zr−alkyl species, under insertion between Zr and one of the allylic termini. Scrambling of deuterium from an allylic CD<sub>2</sub> terminus over several C atom positions next to the unsaturated chain end indicates rather extensive metal migration within an initial olefin insertion product. Density-functional calculations indicate that insertion of propene directly into an η<sup>3</sup>-coordinated Zr−allyl unit occurs with lower activation energy than insertion into an η<sup>1</sup>-bound Zr−allyl species and that the lowest-energy pathway for the reactivation of a cationic zirconocene allyl species is its reconversion to the corresponding Zr−alkyl species by molecular hydrogen. Brintzinger, Hans-Herbert 2000 Prosenc, Marc-Heinrich Brintzinger, Hans-Herbert deposit-license 2013-06-24T17:03:55Z Zirconocene allyl complexes : dynamics in solution, reaction with aluminum alkyls, B(C 6 F 5) 3 -induced propene insertion, and density-functional calculations on possible formation and reaction pathways 2013-06-24T17:03:55Z

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