Theoretical Study of Addition Reactions of LM(M = Rh, Ir) and LM(M = Pd, Pt) to Li@C.

The addition reaction of M(Cl)(CO)(PPh) (M = Rh, Ir) and M(PPh) (M = Pd, Pt) fragments with X@C (X = 0, Li) were characterized by density functional theory (DFT) and the artificial force-induced reaction (AFIR) method. The calculated free energy profiles suggested that the η[6:6]-addition is the most favorable reaction, which is consistent with the experimental observations. In the presence of Li ion, the reaction is highly exothermic, leading to η[6:6] product of LIrLi@C. In contrast, an endothermic reaction was observed in the absence of a Li ion. The encapsulated Li ion can enhance the thermodynamic stability of the η[6:6] product. The energy decomposition analysis showed that the interaction between metal fragment and X@C fragment is the key for the thermodynamic stability. Among the group IA and IIA metal cations, Be encapsulation is the best candidate for the development of new fullerene-transition metal complexes, which will be useful for future potential applications such as solar cells, catalysts, and electronic devices.