Analysis Of Chemical Bonding in the C₆₀Br₂ System Based on NBO, AIM, And Bond Topology Analysis

Fullerene C₆₀ is recognized as a carbon nanostructure with distinctive electronic, optical, and redox properties, making it a highly promising functional material. Although halogenation is an important strategy for modifying the properties of fullerenes, the interactions between heavy halogens and the fullerene surface require further investigation. This study evaluated the chemical bonding characteristics of the C₆₀–Br₂ system using computational approaches based on Natural Bond Orbital (NBO) theory, Atoms in Molecules (

Aim

theory, and electron-density topology analysis. Geometry optimization revealed a Br–C interatomic distance of 2.07 Å, indicating a pronounced intermediate bonding character. Although structural visualization did not indicate the formation of a rigid conventional covalent bond, NBO analysis revealed significant orbital interactions, as reflected by the Wiberg Bond Index (WBI), while

Aim

analysis indicated weak and polarized bonding characteristics based on the topology of the electron density and its Laplacian, consistent with established computational criteria for characterizing bonding interactions in functionalized fullerene systems. Furthermore, topological analysis confirmed the presence of a bond critical point (BCP) with a negative local total energy density, indicating a stabilizing interaction between the bromine and carbon atoms. Overall, the C₆₀–Br₂ system exhibited bonding characteristics intermediate between classical covalent bonding and noncovalent interactions, suggesting that the Br–C interaction can be classified as a partially covalent, polarized interaction.