Stabilization of X–Au–X Complexes on the Au(111) Surface: A Theoretical Investigation and Comparison of X = S, Cl, CH3S, and SiH3S

Stabilities of linear X–Au–X complexes on the Au(111) surface, with different ligands X = S, Cl, CH3S, and SiH3S, are studied using density functional theory (DFT). For X = CH3S and SiH3S, AuX2 complexes are more stable compared with the configuration where X are individually chemisorbed and Au is incorporated into the bulk. AuS2 complexes, however, are less stable than chemisorbed S. The relative stability of AuCl2 complexes depends on the functionals used. Bond strengths of the X–Au–X complexes in the gas phase are calculated by using DFT and the coupled cluster method and found to be similar. This implies that the stabilities of adsorbed complexes are controlled by the bond strength of the ligand to the surface. These results explain why complexes with X = CH3S and sometimes Cl are observed on Au(111), whereas complexes with X = S are not.