Ca@Pb12: A Viable All-Main-Group-Metal Endofullerene That Imitates the Transition Metals

• Published in: Inorganic chemistry 2025-02, Vol.64 (6), p.3000-3007
• Main Authors: Huo, Bin, Guan, Xiao-Ling, Yuan, Caixia, Wu, Yan-Bo
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X; 1520-510X
• DOI: 10.1021/acs.inorgchem.4c05250

Herein, we report the Ca@Pb12 cluster, an all-main-group-metal endofullerene possessing the highly symmetric icosahedral (I h ) Platonic solid structure. The endohedral environment endows the Ca atom with concrete transition-metal-like bonding behaviors, as evidenced by the 18e (in 3d104s24p6 configuration) valence shell structure and five strong Pb12 → Ca­(3d) dative bonds, whose orbital interaction energy (ΔE orb, −134.2 kcal/mol) represents 54.9% of total ΔE orb (−244.4 kcal/mol) between Ca2+ and [Pb12]2–. Moreover, since the favorable orbital interactions can compensate for the enlarged steric repulsion during encapsulation, Ca@Pb12 is thermodynamically stable, dynamically rigid (up to 1300 K), and electronically robust, as verified by large HOMO–LUMO gaps (4.58 eV), high vertical detachment energy (6.39 eV), and low electron affinity (−0.71 eV). It is the first viable all-main-group-metal endofullerene, where the guest alkaline earth metal exhibits the typical bonding behaviors of transition metals.