title: Cationic Silica-Supported N-Heterocyclic Carbene Tungsten Oxo Alkylidene Sites: Highly Active and Stable Catalysts for Olefin Metathesis.
abstract: Designing supported alkene metathesis catalysts with high activity and stability is still a challenge, despite significant advances in the last years. Described herein is the combination of strong σ-donating N-heterocyclic carbene ligands with weak σ-donating surface silanolates and cationic tungsten sites leading to highly active and stable alkene metathesis catalysts. These well-defined silica-supported catalysts, [(≡SiO)W(=O)(=CHCMe2 Ph)(IMes)(OTf)] and [(≡SiO)W(=O)(=CHCMe2 Ph)(IMes)(+) ][B(Ar(F) )4 (-) ] [IMes=1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene, B(Ar(F) )4 =B(3,5-(CF3 )2 C6 H3 )4 ] catalyze alkene metathesis, and the cationic species display unprecedented activity for a broad range of substrates, especially for terminal olefins with turnover numbers above 1.2 million for propene.
authors.affiliation: Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland.
authors.forename: Margherita
authors.initials: M
authors.lastname: Pucino
authors.affiliation: Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland.
authors.forename: Victor
authors.initials: V
authors.lastname: Mougel
authors.affiliation: Institute of Polymer Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
authors.forename: Roman
authors.initials: R
authors.lastname: Schowner
authors.affiliation: Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland.
authors.forename: Alexey
authors.initials: A
authors.lastname: Fedorov
authors.affiliation: Institute of Polymer Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany. michael.buchmeiser@ipoc.uni-stuttgart.de.
authors.forename: Michael R
authors.identifier: http://orcid.org/0000-0001-6472-5156
authors.initials: MR
authors.lastname: Buchmeiser
authors.affiliation: Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland. ccoperet@ethz.ch.
authors.forename: Christophe
authors.initials: C
authors.lastname: Copéret
keywords: N-heterocyclic carbene; metathesis; structure elucidation; supported catalysts; tungsten