Increasing Olefin Metathesis Activity of Silica‐Supported Molybdenum Imido Adamantylidene Complexes through E Ligand σ‐Donation

Molybdenum imido adamantylidene complexes with different substituents on the imido ligand (dipp=2,6‐diisopropylphenyl, ArF5=C6F5, and tBu) having distinct electron donating abilities were investigated for the metathesis of internal and terminal olefins, for both molecular and silica‐supported specie...

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Bibliographic Details
Published in:Helvetica chimica acta 2021-11, Vol.104 (11), p.n/a
Main Authors: Nater, Darryl F., Paul, Bhaskar, Lätsch, Lukas, Schrock, Richard R., Copéret, Christophe
Format: Article
Language:English
Subjects:
adamantylidenes
Alkenes
Coordination compounds
electron donation
Immobilization
Intermediates
Ligands
Metathesis
Molybdenum
olefin metathesis
Silica
Silicon dioxide
surface chemistry
surface organometallic chemistry
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Summary:Molybdenum imido adamantylidene complexes with different substituents on the imido ligand (dipp=2,6‐diisopropylphenyl, ArF5=C6F5, and tBu) having distinct electron donating abilities were investigated for the metathesis of internal and terminal olefins, for both molecular and silica‐supported species using standardized protocols. Here we show that surface immobilization of these compounds results in dramatically increased activity compared to their molecular counterparts. Additionally, we show that electron withdrawing imido groups increase the activity of the compound towards terminal olefins while they simultaneously decrease the ability to metathesize internal olefins. Furthermore, these systems also show high stability when used as initiators in olefin metathesis, although the species that display higher initial activity deactivate faster than those that show more a more moderate reaction rate at first. Our catalytic studies, augmented by DFT calculations, show that all investigated compounds have a remarkably small energy difference between the trigonal bipyramidal (TBP) and square planar (SP) configurations of the metallacyclobutane intermediates, which has previously been linked to high activity.
ISSN:0018-019X
1522-2675
DOI:10.1002/hlca.202100151