Deciphering the Influence of Alkylene Bridged and Chelating Mode on Pd—C and Pd—X (X = Cl, Br, and I) Bonding Interaction Within Bis‐(<scp>NHC</scp>)‐Palladium Complexes Using Quantum Chemistry Tools

Abstract

ABSTRACT In this paper, we have explored the influence of alkylene‐bridged length and coordination mode on the reactivity of a series of 24 alkylene‐bridged palladium complexes using computational tools (B3PW91/LANL2DZ//6‐31G(d) level) in gas phase and DMSO. These palladium complexes prefer a boat and chair configuration for methylene and ethylene bridge length, respectively. In addition, phenyl and nitro complexes present a higher activation for Pd—C bonds while the most stable Pd⋯C interactions are observed for abnormal mode with methylene bridge. According to the energy decomposition analysis (EDA), hydrogen and phenyl complexes in both chelation modes present a better electrostatic character. Moreover, Pd⋯C interactions are stronger compared to the Pd⋯X ones for ethylene‐bridged abnormal complexes (in gas phase). Finally, the donation/back‐donation ratio ( d / b ) values reveal the Fischer carbene character of these [bis(NHC)]⋯[PdX 2 ] interactions. Concerning the hybridization around the metal cation for the Pd—C bond, the sp 2 d type is observed for methylene‐bridged palladium complexes while the sp 3 one is observed for ethylene bridge complexes.