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Sequential Immobilization of ansa-Hafnocene Complexes for Propene Polymerization.pdf (4.33 MB)

Sequential Immobilization of Ansa-Hafnocene Complexes for Propene Polymerization

submitted on 23.10.2019, 08:59 and posted on 25.10.2019, 19:13 by Marius Arz, Tim Kratky, Sebastian Günther, Katia Rodewald, Thomas Burger, Manfred Heuberger, Bernhard Rieger
We report the immobilization of the ultrarigid ansa-hafnocene complexes [Me2Si(Ind*)2HfCl2] (Ind* = 7,(3',5'-Di-tert-butylphenyl)-4-methoxy-2-methylindenyl) on silica as heteregeneous catalysts for propene polymerization. A sequential three-step synthesis on the siliceous surface led to pre-catalysts of the generalized structure SiO2-Si(Ind*)2HfCl2, which possess the silylene bridge of the substituted bis(indenyl) ligand directly attached to the surface. The immobilized pre-catalysts show very poor performance in the polymerization of propene, independent on the reaction conditions and the employed silica. Based on the results, we suggest that the close proximity of the catalyst to the surface combined with the steric congestion provoked by the ligand prevents a continuous polymerization, most likely due to a blockage of the catalytically active sites with growing polymer.


Alexander von Humboldt foundation


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Technical University of Munich, Department of Chemistry



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in Journal of Organometallic Chemistry