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Formation and evolution of chain-propagating species upon ethylene polymerization with neutral salicylaldiminato nickel(II) catalysts

Formation and evolution of chain-propagating species upon ethylene polymerization with neutral salicylaldiminato nickel(II) catalysts

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SOSHNIKOV, Igor E., Nina V. SEMIKOLENOVA, Vladimir A. ZAKHAROV, Heiko MÖLLER, Franz ÖLSCHER, Anna OSICHOW, Inigo GÖTTKER-SCHNETMANN, Stefan MECKING, Evgenii P. TALSI, Konstantin P. BRYLIAKOV, 2013. Formation and evolution of chain-propagating species upon ethylene polymerization with neutral salicylaldiminato nickel(II) catalysts. In: Chemistry - A European Journal. 19(34), pp. 11409-11417. ISSN 0947-6539. eISSN 1521-3765. Available under: doi: 10.1002/chem.201301037

@article{Soshnikov2013-08-19Forma-24339, title={Formation and evolution of chain-propagating species upon ethylene polymerization with neutral salicylaldiminato nickel(II) catalysts}, year={2013}, doi={10.1002/chem.201301037}, number={34}, volume={19}, issn={0947-6539}, journal={Chemistry - A European Journal}, pages={11409--11417}, author={Soshnikov, Igor E. and Semikolenova, Nina V. and Zakharov, Vladimir A. and Möller, Heiko and Ölscher, Franz and Osichow, Anna and Göttker-Schnetmann, Inigo and Mecking, Stefan and Talsi, Evgenii P. and Bryliakov, Konstantin P.} }

eng Soshnikov, Igor E. 2013-08-19 Mecking, Stefan 2013-08-27T13:11:21Z Göttker-Schnetmann, Inigo Semikolenova, Nina V. Osichow, Anna Chemistry - A European Journal ; 19 (2013), 34. - S. 11409–11417 Zakharov, Vladimir A. Ölscher, Franz Mecking, Stefan Talsi, Evgenii P. Formation and evolution of chain-propagating species upon ethylene polymerization with neutral salicylaldiminato nickel(II) catalysts Semikolenova, Nina V. Bryliakov, Konstantin P. Talsi, Evgenii P. Göttker-Schnetmann, Inigo Zakharov, Vladimir A. Formation of Ni–polymeryl propagating species upon the interaction of three salicylaldiminato nickel(II) complexes of the type [(N,O)Ni(CH<sub>3</sub>)(Py)] (where (N,O)=salicylaldimine ligands, Py=pyridine) with ethylene (C<sub>2</sub>H<sub>4</sub>/Ni=10:30) has been studied by <sup>1</sup>H and <sup>13</sup>C NMR spectroscopy. Typically, the ethylene/catalyst mixtures in [D<sub>8</sub>]toluene were stored for short periods of time at +60 °C to generate the [(N,O)Ni(polymeryl)] species, then quickly cooled, and the NMR measurements were conducted at −20 °C. At that temperature, the [(N,O)Ni(polymeryl)] species are stable for days; diffusion <sup>1</sup>H NMR measurements provide an estimate of the average length of polymeryl chain (polymeryl=(C<sub>2</sub>H<sub>4</sub>)<sub>n</sub>H, n=6–18). At high ethylene consumptions, the [(N,O)Ni(polymeryl)] intermediates decline, releasing free polymer chains and yielding [(N,O)Ni(Et)(Py)] species, which also further decompose to form the ultimate catalyst degradation product, a paramagnetic [(N,O)<sub>2</sub>Ni(Py)] complex. In [(N,O)<sub>2</sub>Ni(Py)], the pyridine ligand is labile (with activation energy for its dissociation of (12.3±0.5) kcal mol<sup>−1</sup>, ΔH<sup>≠</sup><sub>298</sub>=(11.7±0.5) kcal mol<sup>−1</sup>, ΔS<sup>≠</sup><sub>298</sub> =(−7±1) cal K<sup>−1</sup> mol<sup>−1</sup>). Upon the addition of nonpolar solvent (pentane), the pyridine ligand is lost completely to yield the crystals of diamagnetic [(N,O)<sub>2</sub>Ni] complex. NMR spectroscopic analysis of the polyethylenes formed suggests that the evolution of chain-propagating species ends up with formation of polyethylene with predominately internal and terminal vinylene groups rather than vinyl groups. 2013-08-27T13:11:21Z Osichow, Anna Bryliakov, Konstantin P. deposit-license Soshnikov, Igor E. Ölscher, Franz Möller, Heiko Möller, Heiko

Dateiabrufe seit 01.10.2014 (Informationen über die Zugriffsstatistik)

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