Sr-centered monocyclic carbon ring Sr@C₁₄: A new stable cluster

The study of stable neutral metal endohedral cyclo[n]carbon is helpful for discovering single-molecule devices. Extensive structural search and density functional theory calculations performed here indicate that the perfect planar alkaline metal-doped complexes Sr@C₁₄ possess the well-defined global minima of the system with the metal atom located exactly at the center of the carbon ring. The configuration and bonding properties of C₁₄ are different from those of pristine cyclo [14]carbon. The significant stabilization when forming Sr@C₁₄ predominantly originates from the electrostatic interaction between Sr²⁺ and C₁₄^2-. The detailed molecular orbital, nucleus-independent chemical shift (NICS), and ring current analyses indicate that Sr@C₁₄ is aromatic in nature. The NICS values of Sr@C₁₄ are considerably larger than those of benzene. Ab initio molecular dynamics simulations at different temperatures reveal that this system exhibits certain stability at low or moderate temperatures. The findings of this study effectively enrich the chemical structures and bonding patterns of metal-doped cyclo[n]carbon and provide the knowledge required to obtain novel structures of Sr@C₁₄ in future experiments.