Abnormal N‐heterocyclic carbenes ( a NHCs) have recently attracted significant attention as ligands in transition‐metal catalysis due to their stronger σ‐donating ability compared to normal NHCs ( n NHCs). In this study, we employ density functional theory to explore the bonding characteristics and electronic properties of palladium complexes containing both n NHC and a NHC ligands. The analysis focuses on the nature of the PdC carbene interaction, evaluating bond strength, charge distribution, and orbital contributions. Frontier orbital analysis reveals that the highest occupied molecular orbital in a NHCs corresponds to a destabilized σ ‐lone pair on the carbene carbon, which enhances their donor capacity relative to n NHCs. Natural bond orbital (NBO) and bond dissociation energy calculations confirm that a NHC ligands transfer electron density more effectively, resulting in shorter and stronger PdC bonds. At the same time, reduced π‐backbonding is observed in a NHC complexes, consistent with their weaker π ‐acceptor character. Quantum theory of atoms in molecules and energy decomposition analysis further demonstrate that the PdC carbene bonds possess mixed ionic–covalent character, with electrostatics dominating the interaction. Collectively, these results explain the greater reactivity and catalytic efficiency of a NHCPd complexes and provide guiding principles for the design of next‐generation carbene ligands in organometallic catalysis.
Velmurugan et al. (Thu,) studied this question.