Structural Evolution and Electronic Properties of Au₂Ge_n^-/0 (n=1-8) Clusters: Anion Photoelectron Spectroscopy and Theoretical Calculations

Investigating the structures and properties of Au-Ge mixed clusters can give insight into the microscopic mechanisms in gold-catalyzed Ge films and can also provide valuable information for the production of germanium-based functional materials. In this work, size-selected anion photoelectron spectroscopy and theoretical calculations were used to explore the structural evolution and electronic properties of Au₂Ge_n^-/0 (n=1-8) clusters. It is found that the two Au atoms in Au₂Ge_n^-/0 (n=1-8) showed high coordination numbers and weak aurophilic interactions. The global minima of Au₂Ge_n^- anions and Au₂Ge_n neutrals are in spin doublet and singlet states, respectively. Au₂Ge_n^- anions and Au₂Ge_n neutrals showed similar structural features, except for Au₂Ge₄^-/0 and Au₂Ge₅^-/0. The C_2v symmetric V-shaped structure is observed for Au₂Ge₁^-/0, while Au₂Ge₂^-/0 has a C_2v symmetric dibridged structure. Au₂Ge₃^-/0 can be viewed as the two Au atoms attached to different Ge-Ge bonds of Ge₃ triangle. Au₂Ge₄^- has two Au atoms edge-capping Ge₄ tetrahedron, while Au₂Ge₄ neutral adopts a C_2v symmetric double Au atoms face-capping Ge₄ rhombus. Au₂Ge_5-8^-/0 show triangular, tetragonal, and pentagonal prism-based geometries. Au₂Ge₆ adopts a C_2v symmetric tetragonal prism structure and exhibits σ plus π double bonding characters.