Encapsulation of Mg₂ inside a C₆₀ 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, Mg₂ @C₆₀ . It is observed that the minimum energy structure of the Mg₂ @C₆₀ system is C_2h symmetry. The MgMg bond distance in the Mg₂ @C₆₀ system is much shorter than that in the free Mg₂ and Mg₂ ²⁺ ion. The formation of the endohedral Mg₂ @C₆₀ system is thermochemically spontaneous in nature. The natural bond orbital (NBO) analysis showed the presence of an Mg₂ ²⁺ fragment with an MgMg bond inside the C₆₀ cage. The electron density descriptors have identified the covalency in the MgMg bond. A non-nuclear attractor (NNA) is present in the middle of the two Mg-atoms. The bonding interaction between the Mg₂ and C₆₀ fragments is ionic in nature and the [Mg₂ ²⁺ ] and [C₆₀ ^2- ] represent the bonding pattern in the Mg₂ @C₆₀ system. The designed endohedrally encapsulated system behaves as an electride.