In Silico Olefin Metathesis with Ru‐Based Catalysts Containing N‐Heterocyclic Carbenes Bearing C₆₀ Fullerenes

Abstract

Density functional theory calculations have been used to explore the potential of Ru-based complexes with 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (SIMes) ligand backbone (A) being modified in silico by the insertion of a C60 molecule (B and C), as olefin metathesis catalysts. To this end, we investigated the olefin metathesis reaction catalyzed by complexes A, B, and C using ethylene as the substrate, focusing mainly on the thermodynamic stability of all possible reaction intermediates. Our results suggest that complex B bearing an electron-withdrawing N-heterocyclic carbene improves the performance of unannulated complex A. The efficiency of complex B is only surpassed by complex A when the backbone of the N-heterocyclic carbene of complex A is substituted by two amino groups. The particular performance of complexes B and C has to be attributed to electronic factors, that is, the electronic-donating capacity of modified SIMes ligand rather than steric effects, because the latter are predicted to be almost identical for complexes B and C when compared to those of A. Overall, this study indicates that such Ru-based complexes B and C might have the potential to be effective olefin metathesis catalysts.

The activity of indenylidene derivatives in olefin metathesis catalysts

“…Although most of the olefin metathesis catalysts are based on ruthenium [ 21 – 22 ], because these are more stable to oxygen and moisture [ 23 ] than their molybdenum counterparts, they display sensitivity to decomposition while in solution [ 24 – 25 ]. Understanding and/or the elimination of potential pathways that leads to catalyst decomposition is extremely important [ 26 – 28 ], since any knowledge obtained in this area can guide the catalyst design efforts [ 29 – 31 ].…”

In Silico Switch from Second- to First-Row Transition Metals in Olefin Metathesis: From Ru to Fe and from Rh to Co

“…Chemical hardness analyses determined that Ru is more prone to react with a nucleophilic olefin than Fe-based catalysts. Still, ruthenium continues leading the list for new generations of olefin metathesis catalysts [63][64][65]. However, we have to keep going on the research to stabilize the metallacycle bearing Co as a metal center, which was the only drawback found for this metal in this study.…”

Mechanistic Aspects of the Palladium‐Catalyzed Suzuki‐Miyaura Cross‐Coupling Reaction

“…However, the need to overcome new challenging substrate transformations with higher selectivity and/or under mild conditions [45] has caused the emergence of the ligand design field. Over the past 25 years, a better understanding of the steric[ 46 , 47 , 48 , 49 ] and electronic [46] properties of ligands[ 50 , 51 , 52 ] as well as the binding properties of metals has led to the creation of well‐defined organometallic complexes as highly effective (pre)catalysts. [53] Therefore, the greatest success in the field of catalysis has been achieved through ligand design.…”