Encapsulation of Mg 2 inside a C 60 cage forms an electride

Density functional theory (DFT) based calculations have been carried out for the endohedral encapsulation of magnesium dimer inside fullerene, that is, Mg 2 @C 60 . It is observed that the minimum energy structure of the Mg 2 @C 60 system is C 2 h symmetry. The MgMg bond distance in the Mg 2 @C 60 system is much shorter than that in the free Mg 2 and Mg 2 2+ ion. The formation of the endohedral Mg 2 @C 60 system is thermochemically spontaneous in nature. The natural bond orbital (NBO) analysis showed the presence of an Mg 2 2+ fragment with an MgMg bond inside the C 60 cage. The electron density descriptors have identified the covalency in the MgMg bond. A non‐nuclear attractor (NNA) is present in the middle of the two Mg‐atoms. The bonding interaction between the Mg 2 and C 60 fragments is ionic in nature and the [Mg 2 2+ ] and [C 60 2− ] represent the bonding pattern in the Mg 2 @C 60 system. The designed endohedrally encapsulated system behaves as an electride.