A density functional study of silicon fullerene endohedral X@Si20F20 and exohedral X-Si20F20 (X=O2−, S2−, Se2−) complexes

This study reports the structure and electronic properties of three stable endohedral X@Si20F20 and exohedral X-Si20F20 (X=O2−, S2−, Se2−) complexes. The study revealed that the endohedral complexes with S2− and Se2− result as energy minimum structures, with the guest anion located in the cage center. In the case of endohedral O2−-complexes, the pattern is quite different whereas the O2− complexes dramatically deviated from the architecture of S2− and Se2−, by having O2− located toward one of silicon atoms in the cage. With respect to the exohedral form, the energy minimized structure is obtained by positioning the anion between two silicon atoms and forming two Si–X bonds. For both cases, the strength of the interactions is calculated to increase accordingly to the pattern: Se2−@Si20F20 (Se2−-Si20F20)