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.