Structural Evolution and Bonding Properties of Cr₂Si_<i>n</i>^– (<i>n</i> = 1–12) Clusters: Mass-Selected Anion Photoelectron Spectroscopy and Theoretical Calculations

Abstract

We investigated the structural characteristics and bonding properties of Cr₂Si_<i>n</i>^- (<i>n</i> = 1-12) clusters by using anion photoelectron spectroscopy combined with density functional theory calculations. The experimental and theoretical results reveal that Cr atoms of the most stable structures of Cr₂Si_<i>n</i>^- clusters with <i>n</i> < 8 are located at the surface, while the most stable structures of Cr₂Si_<i>n</i>^- clusters with <i>n</i> ≥ 8 have one Cr encapsulated in the cage consisting of the other Cr atom and the Si atoms. The Cr-Cr interaction in the most stable structures of Cr₂Si_<i>n</i>^- clusters is strong, except that the Cr-Cr interaction in the lowest lying isomer of the Cr₂Si₅^- cluster is weak. The structure of Cr₂Si₆^- can be viewed as the Cr₂ surrounded by a chair-shaped silicon six-membered ring with the C_2h symmetry. Cr₂Si₁₂^- has a C_6v symmetric antihexagonal prism structure with two Cr atoms located at the center and the surface of the Si₁₂ cage, respectively. The magnetic moments of Cr₂Si_<i>n</i>^- are 1 μB except that the magnetic moment of Cr₂Si₅^- is 9 μB.