Determining the Impact of Ligand and Alkene Substituents on Bonding in Gold(I)–Alkene Complexes Supported by N-Heterocyclic Carbenes: A Computational Study

The nature of the gold(I)–alkene bond in [(NHC)Au(alkene)]+ complexes (where NHC is the N-heterocyclic carbene 1,3-bis(2,6-dimethylphenyl)imidazole-2-ylidine and its derivatives) has been studied using density functional theory. By utilization of a series of electron-withdrawing and electron-donating substituents ranging from −NO2 to −NH2, an examination of substituent effects has been undertaken with 4-substituted NHC ligands, monosubstituted ethylene derivatives, and 4-substituted styrene derivatives. Natural population, natural bond orbital (NBO), molecular orbital, and bond energy decomposition analysis (EDA) methods have been used to quantify a number of important parameters, including the charge of the coordinated alkenes and the magnitude of alkene→[(NHC)Au]+ and [(NHC)Au]+→alkene electron donation. EDA methods have also been used to quantify the strength of the [(NHC)Au]+−(alkene) bond and the impact of both ligand and alkene substitution on different components of the interaction, including polar...