Magnesium dimer entrapped in cyclo[18]carbon: Mg2@C18.

[Display omitted] • The size makes cyclo[18]carbon a suitable candidate to accommodate Mg 2 molecules inside to form stable endohedral Mg 2 @C 18. • Charge transfer between Mg 2 and C 18 forms stable [Mg 2 ]2+[C 18 ]2– ionic complexes. • Large binding energy and aromaticity indicate that Mg 2 @C 18 is a remarkable stable system. The recent discovery of cyclo[18]carbon has attracted widespread attention. Density functional theory (DFT) study was carried out to evaluate the viability of the encapsulation of magnesium dimer inside the all-carboatomic ring, that is, Mg 2 @C 18. Results indicated that Mg 2 @C 18 possesses a perfect endohedral structure. Charge transfer resulted in forming typical [Mg 2 ]2+[C 18 ]2– ionic complexes. The high stability of the complex could be due to the strong electrostatic interaction between the guest Mg 2 and the host C 18 ring. The structure and bonding properties of the C 18 ring of the system is different from those of pristine cyclo[18]carbon. Mg 2 @C 18 shows remarkable aromatic character. [ABSTRACT FROM AUTHOR]