Endohedral metalloborofullerenes M@B44 (M = Ca, Sr, Ba): a computational investigation.

For the first time, the structures, stabilities and electronic properties of alkaline-earth metal doped B44 fullerenes were investigated by means of density functional theory calculations. Our results reveal that M@B44 (M = Ca, Sr, Ba) possess endohedral configurations as their lowest energy structures, whereas the exohedral form is favored when metal is Be or Mg. The large binding energies and sizable HOMO-LUMO gap energies of Ca@B44, Sr@B44 and Ba@B44 suggest the considerable possibility to achieve these novel endohedral borofullerenes experimentally. Born-Oppenheimer molecular dynamics (BO-MD) simulations at various temperatures further confirmed the extreme dynamic stabilities of these endohedral complexes. Their bonding patterns were also analyzed in detail. Finally, we simulated their infrared absorption spectra and 11B nuclear magnetic resonance spectra to help future structural characterization. Graphical Abstract Stuffing B44 fullerene with metals.