Direct observation of reaction intermediates for a well defined heterogeneous alkene metathesis catalyst
- 26 August 2008
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 105 (34) , 12123-12127
- https://doi.org/10.1073/pnas.0802147105
Abstract
Grafting of [W( NAr)(=CHtBu)(2,5-Me2NC4H2)(2)] on a silica partially clehydroxylated at 700 degrees C (SiO2-(700)) generates the corresponding monosiloxy complex [( SiO)W( NAr)(=CHtBu)(2,5-Me2NC4H2)] as the major species (approximate to 90%) along with [( SiO)W( NAr)(CH(2)tBu)(2,5-Me2NC4H2)(2)], according to mass balance analysis, IR, and NMR studies. This heterogeneous catalyst displays good activity and stability in the metathesis of propene. Very importantly, solid state NMR spectroscopy allows observation of the propagating alkylidene as well as stable metallacyclobutane intermediates. These species have the same reactivity as the initial surface complex [( SiO)W( NAr)(=CHtBu)(2,5-Me2NC4H2)], which shows that they are the key intermediates of alkene metathesis.Keywords
This publication has 45 references indexed in Scilit:
- CH3-ReO3 on γ-Al2O3: Activity, selectivity, active site and deactivation in olefin metathesisJournal of Catalysis, 2008
- CH3ReO3 on γ‐Al2O3: Understanding Its Structure, Initiation, and Reactivity in Olefin MetathesisAngewandte Chemie International Edition in English, 2007
- Synthesis and Reactions of Tungsten Alkylidene Complexes That Contain the 2,6-Dichlorophenylimido LigandOrganometallics, 2007
- Ruthenium Metallacycles Derived from 14-Electron Complexes. New Insights into Olefin Metathesis IntermediatesJournal of the American Chemical Society, 2006
- Direct Observation of a 14-Electron Ruthenacyclobutane Relevant to Olefin MetathesisJournal of the American Chemical Society, 2005
- Dissociation of Acetaldehyde on β-Mo2C To Yield Ethylidene and Oxo Surface Groups: A Possible Pathway for Active Site Formation in Heterogeneous Olefin MetathesisJournal of the American Chemical Society, 2004
- Molecular design of heterogeneous catalysts: the case of olefin metathesisNew Journal of Chemistry, 2003
- Alkylidene and Metalacyclic Complexes of Tungsten that Contain a Chiral Biphenoxide Ligand. Synthesis, Asymmetric Ring-Closing Metathesis, and Mechanistic InvestigationsJournal of the American Chemical Society, 2003
- Evaluation of Enantiomerically Pure Binaphthol-Based Molybdenum Catalysts for Asymmetric Olefin Metathesis Reactions that Contain 3,3‘-Diphenyl- or 3,3‘-Dimesityl-Substituted Binaphtholate Ligands. Generation and Decomposition of Unsubstituted Molybdacyclobutane ComplexesOrganometallics, 2001
- Trigonal-bipyramidal and square-pyramidal tungstacyclobutane intermediates are both present in systems in which olefins are metathesized by complexes of the type W(CHR')(N-2,6-C6H3-iso-Pr2)(OR)2Organometallics, 1989