Structure and Stability of a Trefoil Leaf Motif of Metal-Doped Silicon and Germanium Clusters: M@E with E = Si and Ge and M = Fe, Ru, and Os.

The first trefoil leaf-shaped cluster, a novel structural motif, was discovered by quantum chemical computations using density functional theory methods for both binary M@E silicon and germanium clusters in which a metallic M cycle is encapsulated within a Si or Ge cage. The triatomic transition metal Fe, Ru, and Os cycles exhibit a suitable size to be placed inside both Si and Ge cages and satisfy electronic conditions, which thermodynamically stabilize the mixed clusters. Stabilizing orbital interactions between the M cycle and E cage crucially contributes to the high stability of the resulting M@E trefoil cluster. The novel trefoil leaf-shaped clusters can be used as building units to create different nanoassemblies.