In the metallofullerene Sc3N@C80, the transition metal is scandium Sc . The coordination number of a transition metal in a complex refers to the number of ligands atoms, ions, or molecules that are directly bonded to it. In this case, the three scandium atoms are coordinated to a single nitrogen atom, forming a Sc3N cluster that is encapsulated inside the C80 fullerene cage.The coordination number of each scandium atom in the Sc3N cluster is 4, as each Sc atom is bonded to the nitrogen atom and its two neighboring Sc atoms. The Sc3N cluster does not have direct bonds with the carbon atoms of the C80 fullerene cage, but it does interact with the cage through van der Waals forces and other weaker interactions.The presence of the Sc3N cluster inside the C80 fullerene affects the electronic structure and reactivity of the molecule compared to an empty fullerene. The transition metal cluster donates some of its electrons to the carbon cage, which leads to a change in the electronic properties of the fullerene. This results in a more stable and less reactive molecule compared to an empty C80 fullerene.Additionally, the encapsulated Sc3N cluster can act as a Lewis acid, which can interact with electron-rich species Lewis bases and participate in redox reactions. This gives the Sc3N@C80 metallofullerene unique catalytic properties and potential applications in various fields, such as materials science, catalysis, and nanotechnology.