Computational prediction of the endohedral metalloborofullerenes Ti n @B40 (n = 1, 2)

Abstract

The recent discovery of the B40−/0 borospherenes (Zhai et al. in Nat Chem 6:727–731, 2014) has stimulated a large number of experimental/theoretical studies on the small all-boron fullerenes. At the same time, their capabilities to accommodate various metal species are predicted by calculations. However, the simultaneous encapsulation of two metal atoms has never been touched probably due to the limited cavities of these boron cages. In this work, systematic density functional theory calculations reveal that B40 tends to entrap one and even two titanium atoms. The formed Tin@B40 (n = 1, 2) complexes possess large binding energies and sizable HOMO–LUMO gap energies, and are highly robust at different temperatures (300–1000 K), suggesting their excellent stabilities. Interestingly, Ti2@B40 features two filled pentagonal (B@B5) motifs with protruding central atom, which are reminiscent of the B12 icosahedral unit in bulk boron. The analysis on the electronic properties and bonding patterns of Tin@B40 reveal that both of them have σ plus π double electron delocalization. Furthermore, various spectroscopies were simulated for the future experimental characterization.