Theoretical Insights into Covalent Interactions between Bowl-Shaped Norcorrole and C₆₀ Fullerene

In this work, we report covalent and noncovalent interactions between M(II) norcorroles (M = Ni and Zn) and C₆₀. Density functional theory analyses show that the bowl-shaped norcorrole complex supports two distinct binding modes with C₆₀: in a rim orientation, π-π dispersion interactions dominate, whereas in a bottom orientation, the metal center approaches a C-C bond of the fullerene. Energy decomposition and electronic structure analyses confirm weak Zn-C₆₀ covalent bonding in Zn(II) norcorrole. Subsequent studies on the trimer with one norcorrole complex connecting two C₆₀ molecules reveal stronger interactions compared with the Zn(II) norcorrole/C₆₀ dimer. Furthermore, the dynamic behavior of these complexes demonstrates a low energy barrier for norcorrole migration on the C₆₀ surface. These findings enlighten how the positively curved bowl-shaped norcorrole complexes form frameworks with C₆₀, providing a new concept for designing fullerene-based coordination frameworks and supramolecular materials.