Direct observation of reaction intermediates for a well defined heterogeneous alkene metathesis catalyst

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.


Published in:
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 105, 34, 12123-12127
Year:
2008
Publisher:
NATL ACAD SCIENCES
ISSN:
0027-8424
Keywords:
Laboratories:




 Record created 2015-01-08, last modified 2018-12-03


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