Electronic structure of the boron fullerene B14 and its silicon derivatives B13Si+, B13Si− and B12Si2: a rationalization using a cylinder model†
Geometric and electronic structures of the boron cluster B14 and its silicon derivatives B13Si+, B13Si−, and B12Si2 were determined using DFT calculations (TPSSh/6-311+G(d)). The B12Si2 fullerene, which is formed by substituting two B atoms at two apex positions of the B14 fullerene by two Si atoms, was also found as the global minimum structure. We demonstrated that the electronic structure and orbital configuration of these small fullerenes can be predicted by the wavefunctions of a particle on a cylinder. The early appearance of high angular node MOs in B14 and B12Si2 can be understood by this simple model. Replacement of one B atom at a top position of B14 by one Si atom, followed by the addition or removal of one electron does not lead to a global minimum fullerene structure for the anion B13Si− and cation B13Si+. The early appearance of the 5σ1 orbital in B13Si+ causes a lower stability for the fullerene-type structure.