Density Functional Theory Investigation of Simple N-Heterocyclic Carbenes Adsorbed on the Pd/Cu(111) Single-Atom Alloy Surface

Nonlocal density functional theory calculations were utilized to investigate the interactions of four different cyclic N-heterocyclic carbenes with a Pd/Cu(111) single-atom alloy surface. We find that the molecules are chemisorbed to the surface due to relatively large binding energies and significant charge transfer between the surface and the adsorbates. We highlight that modulating the NHC backbone changes the unoccupied states on the adsorbates that participate in back-donation from the surface to the adsorbate. This contrasts with the forward donation (adsorbate HOMO to the surface) that is left relatively unchanged through modifying the backbone.