Origin of the High Activity of Second-Generation Grubbs Catalysts

New phenoxybenzylidene ruthenium chelates were synthesised from the second generation Grubbs catalysts bearing a triphenylphosphine ligand (or its para-substituted analogues) by metathesis exchange with substituted 2-vinylphenols. The complexes behave like a latent catalyst and are characterized by an improved catalytic behaviour as compared to that of the known analogues, i.e., they exhibit high catalytic inactivity in their dormant forms and a profound increase in activity after activation with HCl. The strong electronic influence of substituents in the chelating ligand on the catalytic activity was demonstrated. The catalytic properties were tested in ROMP of cyclooctadien (COD) and a single selected norbornene derivative.

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Synthesis and activity for ROMP of bidentate Schiff base substituted second generation Grubbs catalysts

Journal of Molecular Catalysis A Chemical ◽

10.1016/j.molcata.2006.07.006 ◽

2006 ◽

Vol 260 (1-2) ◽

pp. 221-226 ◽

Cited By ~ 46

Author(s):

Bart Allaert ◽

Nicolai Dieltiens ◽

Nele Ledoux ◽

Carl Vercaemst ◽

Pascal Van Der Voort ◽

...

Keyword(s):

Schiff Base ◽

Second Generation ◽

Grubbs Catalysts

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Polydicyclopentadiene aerogels from first- versus second-generation Grubbs’ catalysts: a molecular versus a nanoscopic perspective

Journal of Sol-Gel Science and Technology ◽

10.1007/s10971-015-3718-0 ◽

2015 ◽

Vol 75 (2) ◽

pp. 460-474 ◽

Cited By ~ 13

Author(s):

Abhishek Bang ◽

Dhairyashil Mohite ◽

Adnan Malik Saeed ◽

Nicholas Leventis ◽

Chariklia Sotiriou-Leventis

Keyword(s):

Second Generation ◽

Grubbs Catalysts

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A comprehensive study of olefin metathesis catalyzed by Ru-based catalysts

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.11.192 ◽

2015 ◽

Vol 11 ◽

pp. 1767-1780 ◽

Cited By ~ 20

Author(s):

Albert Poater ◽

Luigi Cavallo

Keyword(s):

Dft Calculations ◽

Olefin Metathesis ◽

Second Generation ◽

Phosphine Ligands ◽

Grubbs Catalyst ◽

Heterocyclic Ligand ◽

Grubbs Catalysts ◽

Wide Range ◽

First And Second Generation ◽

Comprehensive Study

During a Ru-catalyzed reaction of an olefin with an alkylidene moiety that leads to a metallacycle intermediate, the cis insertion of the olefin can occur from two different directions, namely side and bottom with respect to the phosphine or N-heterocyclic ligand (NHC), depending on the first or second generation Grubbs catalyst. Here, DFT calculations unravel to which extent the bottom coordination of olefins with respect is favored over the side coordination through screening a wide range of catalysts, including first and second generation Grubbs catalysts as well as the subsequent Hoveyda derivatives. The equilibrium between bottom and side coordination is influenced by sterics, electronics, and polarity of the solvent. The side attack is favored for sterically less demanding NHC and/or alkylidene ligands. Moreover the generation of a 14-electron species is also discussed, with either pyridine or phosphine ligands to dissociate.

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