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Indenylidene Complexes of Ruthenium Bearing NHC Ligands - Structure Elucidation and Performance as Catalysts for Olefin Metathesis

Stijn Monsaert UGent, Els De Canck UGent, Renata Drozdzak, Pascal Van Der Voort UGent, Francis Verpoort UGent, José Martins UGent and Pieter Hendrickx UGent (2009) European Journal of Organic Chemistry. p.655-665
abstract
Second-generation catalysts of the general formula Cl2Ru-(SIMes)(L)(3-phenylinden-1-ytidene), 3a (L = PCy3), 3b (L = PPh3), 3c (L = py), and Cl2Ru(SIMe)(L)(3-phenyhnden-1-yl-idene), 4a (L = PCy3), 4b (L = PPh3), 4c (L = py) were found to be of interest in various metathesis transformations. The catalysts containing SIMe ligands showed improved initiation compared to the more robust SIMes substituted catalysts. A strong temperature effect was noted on all of the reactions tested. Interestingly, complex 3a, showing the lowest initiation rate at room temperature, emerged as the most productive of all systems examined at elevated temperature. It is shown that complexes containing the SIMe ligand display higher initiation efficiency than their corresponding SIMes analogues. Since the higher initiation is related to the ease of phosphane dissociation while phosphane dissociation also promotes catalyst decomposition, complexes bearing the SIMe ligand decompose faster. The complete H-1, C-13 and P-31 resonance assignment and the procedure applied to obtain these from a combination of 1D and 2D NMR techniques, is also reported. Combined with the ROESY technique, these enabled to investigate several conformational processes involving rotations around N-phenyl and C-Ru bonds on the millisecond to second timescale. A clear correlation is demonstrated between the bulkiness of the axial ligand (L) and the rotational freedom of the SIMe(s) ligand. A qualitative analysis also suggests that the extra para-methyl of SIMes leads to additional steric interactions with the 3-phenylinden-1-ylidene ligand. The data reported in this paper demonstrates that substitution patterns of the N-aryl have a significant influence on the activity of the second-generation indenylidene catalysts for a given metathesis reaction.
Please use this url to cite or link to this publication:
author
organization
year
type
journalArticle (original)
publication status
published
subject
keyword
Homogeneous catalysis, PHOSPHINE, EFFICIENT, N-HETEROCYCLIC CARBENE, 4-POLYBUTADIENE SYSTEM, Conformation analysis, CROSS-METATHESIS, Olefin metathesis, Ruthenium, RUCL2(=CHR)(PR(3))(2), Indenylidene, RING-CLOSING METATHESIS, DONOR, ACTIVATION
journal title
European Journal of Organic Chemistry
Eur. J. Org. Chem.
issue
5
pages
655 - 665
Web of Science type
Article
Web of Science id
000263512300007
JCR category
CHEMISTRY, ORGANIC
JCR impact factor
3.096 (2009)
JCR rank
15/57 (2009)
JCR quartile
2 (2009)
ISSN
1434-193X
DOI
10.1002/ejoc.200800973
language
English
UGent publication?
yes
classification
A1
id
516201
handle
http://hdl.handle.net/1854/LU-516201
date created
2009-03-10 09:29:15
date last changed
2009-03-11 10:21:46
@article{516201,
  abstract     = {Second-generation catalysts of the general formula Cl2Ru-(SIMes)(L)(3-phenylinden-1-ytidene), 3a (L = PCy3), 3b (L = PPh3), 3c (L = py), and Cl2Ru(SIMe)(L)(3-phenyhnden-1-yl-idene), 4a (L = PCy3), 4b (L = PPh3), 4c (L = py) were found to be of interest in various metathesis transformations. The catalysts containing SIMe ligands showed improved initiation compared to the more robust SIMes substituted catalysts. A strong temperature effect was noted on all of the reactions tested. Interestingly, complex 3a, showing the lowest initiation rate at room temperature, emerged as the most productive of all systems examined at elevated temperature. It is shown that complexes containing the SIMe ligand display higher initiation efficiency than their corresponding SIMes analogues. Since the higher initiation is related to the ease of phosphane dissociation while phosphane dissociation also promotes catalyst decomposition, complexes bearing the SIMe ligand decompose faster. The complete H-1, C-13 and P-31 resonance assignment and the procedure applied to obtain these from a combination of 1D and 2D NMR techniques, is also reported. Combined with the ROESY technique, these enabled to investigate several conformational processes involving rotations around N-phenyl and C-Ru bonds on the millisecond to second timescale. A clear correlation is demonstrated between the bulkiness of the axial ligand (L) and the rotational freedom of the SIMe(s) ligand. A qualitative analysis also suggests that the extra para-methyl of SIMes leads to additional steric interactions with the 3-phenylinden-1-ylidene ligand. The data reported in this paper demonstrates that substitution patterns of the N-aryl have a significant influence on the activity of the second-generation indenylidene catalysts for a given metathesis reaction.},
  author       = {Monsaert, Stijn and De Canck, Els and Drozdzak, Renata and Van Der Voort, Pascal and Verpoort, Francis and Martins, Jos{\'e} and Hendrickx, Pieter},
  issn         = {1434-193X},
  journal      = {European Journal of Organic Chemistry},
  keyword      = {Homogeneous catalysis,PHOSPHINE,EFFICIENT,N-HETEROCYCLIC CARBENE,4-POLYBUTADIENE SYSTEM,Conformation analysis,CROSS-METATHESIS,Olefin metathesis,Ruthenium,RUCL2(=CHR)(PR(3))(2),Indenylidene,RING-CLOSING METATHESIS,DONOR,ACTIVATION},
  language     = {eng},
  number       = {5},
  pages        = {655--665},
  title        = {Indenylidene Complexes of Ruthenium Bearing NHC Ligands - Structure Elucidation and Performance as Catalysts for Olefin Metathesis},
  url          = {http://dx.doi.org/10.1002/ejoc.200800973},
  year         = {2009},
}

Chicago
Monsaert, Stijn, Els De Canck, Renata Drozdzak, Pascal Van Der Voort, Francis Verpoort, José Martins, and Pieter Hendrickx. 2009. “Indenylidene Complexes of Ruthenium Bearing NHC Ligands - Structure Elucidation and Performance as Catalysts for Olefin Metathesis.” European Journal of Organic Chemistry (5): 655–665.
APA
Monsaert, S., De Canck, E., Drozdzak, R., Van Der Voort, P., Verpoort, F., Martins, J., & Hendrickx, P. (2009). Indenylidene Complexes of Ruthenium Bearing NHC Ligands - Structure Elucidation and Performance as Catalysts for Olefin Metathesis. European Journal of Organic Chemistry, (5), 655–665.
Vancouver
1.
Monsaert S, De Canck E, Drozdzak R, Van Der Voort P, Verpoort F, Martins J, et al. Indenylidene Complexes of Ruthenium Bearing NHC Ligands - Structure Elucidation and Performance as Catalysts for Olefin Metathesis. European Journal of Organic Chemistry. 2009;(5):655–65.
MLA
Monsaert, Stijn, Els De Canck, Renata Drozdzak, et al. “Indenylidene Complexes of Ruthenium Bearing NHC Ligands - Structure Elucidation and Performance as Catalysts for Olefin Metathesis.” European Journal of Organic Chemistry 5 (2009): 655–665. Print.