Unveiling the Electronic Properties of Ru‐Based Olefin Metathesis Catalysts by Wielding DFT Studies

ABSTRACT A comprehensive DFT study was performed to evaluate the efficiency of various generations of Grubbs catalysts‐ruthenium‐based complexes (Ru‐X, 1–7) in promoting olefin metathesis. The primary objective was to predict which set of Grubbs catalysts exhibit superior reactivity in the activation of olefin substrates. A series of computational analyses were conducted to elucidate the electronic structure and bonding characteristics of the metal complexes. The findings indicate that the activation efficiency of the olefin is significantly influenced by the nature of the ancillary ligands coordinated to the Ru center. Among the complexes studied, the [(C 6 H 4 NO 2 )CH‐Ru(NHC)(CH 3 )2CHOCH 3 (Cl) 2 ] (complex (6)) system was found to display the most favorable electronic features for efficient olefin activation. To further probe the nature of the chemical bonding between the Ru center and the ancillary ligands, energy decomposition analysis (EDA) was employed. The EDA results reveal a combination of σ‐donation from the olefin to the metal center and π‐back donation from Ru to the olefin. The ruthenium center engages in a synergistic interaction with the carbene ligand, characterized by both σ‐donation from the carbene carbon lone pair to the Ru and π‐backdonation from the Ru d‐orbitals to the empty π*‐orbitals of the carbene. This bidirectional electron donation stabilizes the metal–carbene bond and plays a crucial role in modulating the catalyst's activity and selectivity. These insights underscore the crucial role of ligand design in modulating the electronic structure and catalytic performance of Ru‐based olefin metathesis catalysts.