Steric and Electronic Effects in Gold N‐Heterocyclic Carbene Complexes Revealed by Computational Analysis

A computational analysis of a series of cationic and neutral gold imidazolylidene and benzimidizolylidene complexes is reported. The Bond Dissociation Energies of the various ligands in the complexes calculated at the PBE0‐D3/def2‐TZVP level of theory increase with increasing ligand volume, except for those of complexes containing t‐butyl‐substituted ligands, which are anomalously low particularly for the benzimidazolylidene species. Atoms in Molecules studies show the presence of a variety of weak intramolecular interactions, characterised by the presence of bond critical points with a range of different properties. Energy Decomposition Analysis and calculation of Electrostatic Surface Potentials indicate that some interactions are weakly attractive dispersion‐type interactions, while others are repulsive. The octanol/water partition coefficients (log P values) were calculated as a measure of the lipophilicities of the complexes and were found to increase with increasing volume.