Structural evolution and bonding properties of Au2Sin-/0 (n=1-7) clusters: Anion photoelectron spectroscopy and theoretical calculations

The photoelectron spectra of Au2Sin-(n = 1-7) clusters were measured, and the structural evolution and bonding properties of Au2Si1-7- anions and their corresponding neutral counterparts were investigated by theoretical calculations. The two Au atoms in Au2Si1-7-/0 prefer to occupy low coordinate sites and form fewer Au-Si bonds. The aurophilic interaction is fairly weak in these clusters. The most stable structures of both Au2Sin- anions and Au2Sin neutrals can be described as the two Au atoms interacting with the Si-n frameworks. The most stable isomers of Au2Sin- anions are in spin doublet states, while those of the neutral clusters are in spin singlet states. The lowest-lying isomers of Au2Si1-/0 have C-2v symmetric V-shaped structures. The global minimum of the Au2Si2- anion has a D-2h symmetric planar rhombus structure, while that of the Au2Si2 neutral adopts a C-2v symmetric dibridged structure. In Au2Si3-/0, the two Au atoms independently interact with the different Si-Si bonds of the Si-3 triangular structure. The global minima of Au2Si4 (-/0)(7) primarily adopt prismatic based geometries. Interestingly, Au2Si6-/0 have significant 3D aromaticity and possess sigma plus pi double bonding characters, which play important roles in their structural stability. Published by AIP Publishing.