Structure and properties of Be- and Mg-doped cyclo[18]carbon.

An intriguing solid-state all-carboatomic ring, cyclo[18]carbon was observed recently in experiment. In this paper, the structures, bonding characters and electronic properties of Be- and Mg-doped cyclo[18]carbon ( BeC 18 and MgC 18 ) were studied using density functional theory. The most stable structures of BeC 18 and MgC 18 are still ring-like configurations. Bond order analysis shows the characteristic of alternative bond length for the doped C 18 . Compared with primitive C 18 ring, the long C–C bond length of doped C 18 became longer and the bond order became smaller on the whole. However, the short C–C bond gets shorter and the bond order gets larger. The features of frontier molecular orbital of BeC 18 and MgC 18 were different from that of primitive C 18 . The results of bond order, electron difference density, localized orbital locator, binding energies and metal–carbon bonding interactions revealed that the structure of BeC 18 is more stable than MgC 18 . Both BeC 18 and MgC 18 are weak aromaticity. [ABSTRACT FROM AUTHOR]