10.1021/ja8078913.s001
Ian C. Stewart
Ian C.
Stewart
Diego Benitez
Diego
Benitez
Daniel J. O’Leary
Daniel J.
O’Leary
Ekaterina Tkatchouk
Ekaterina
Tkatchouk
Michael W. Day
Michael W.
Day
William A. Goddard
William A.
Goddard
Robert H. Grubbs
Robert H.
Grubbs
Conformations of N-Heterocyclic Carbene Ligands in Ruthenium Complexes Relevant to Olefin Metathesis
American Chemical Society
2009
B 3LYP
Ligand
symmetry
metathesi
noncovalent interactions
catalyst 2.
Due
ligand
tilt
sterically
Conformation
M 06
complex
Carbene
olefin
ruthenium center
Ruthenium Complexes
geometrie
accuracy
Olefin MetathesisThe structure
DFT
mol
data
methyl substituents
substrate
solution
analysis
crystal
M 06 functionals
kcal
model
b 3LYP
reactivity
2009-02-11 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Conformations_of_N_Heterocyclic_Carbene_Ligands_in_Ruthenium_Complexes_Relevant_to_Olefin_Metathesis/2879173
The structure of ruthenium-based olefin metathesis catalyst <b>3</b> and model π-complex <b>5</b> in solution and in the solid state are reported. The <i>N</i>-tolyl ligands, due to their lower symmetry than the traditional <i>N</i>-mesityl substituents, complicate this analysis, but ultimately provide explanation for the enhanced reactivity of <b>3</b> relative to standard catalyst <b>2</b>. The tilt of the <i>N</i>-tolyl ring provides additional space near the ruthenium center, which is consistent with the enhanced reactivity of <b>3</b> toward sterically demanding substrates. Due to this tilt, the more sterically accessible face bears the two methyl substituents of the <i>N</i>-aryl rings. These experimental studies are supported by computational studies of these complexes by DFT. The experimental data provides a means to validate the accuracy of the B3LYP and M06 functionals. B3LYP provides geometries that match X-ray crystal structural data more closely, though it leads to slightly less (∼0.5 kcal mol<sup>−1</sup>) accuracy than M06 most likely because it underestimates attractive noncovalent interactions.