A Theoretical Study on the Stability of PtL 2 Complexes of Endohedral Fullerenes: The Influence of Encapsulated Ions, Cage Sizes, and Ligands.

The {η ² -(X@C _n )}PtL ₂ complexes possessing three kinds of encapsulated ions (X = F ^- , Ø, Li ⁺ ), three various ligands (L = CO, PPh ₃ , NHC ^Me ), and twelve cage sizes (C ₆₀ , C ₇₀ , C ₇₂ , C ₇₄ , C ₇₆ , C ₇₈ , C ₈₀ , C ₈₄ , C ₈₆ , C ₉₀ , C ₉₆ , C ₁₀₀ ) are theoretically examined by using the density functional theory (M06/LANL2DZ). The present computational results demonstrate that the backward-bonding orbital interactions, rather than the forward-bonding orbital interactions, play a dominant role in the stability of {η ² -(X@C _n )}PtL ₂ complexes. Additionally, our theoretical study shows that the presence of the encapsulated Li ⁺ ion can greatly improve the stability of {η ² -(X@C _n )}PtL ₂ complexes, whereas the existence of the encapsulated F ^- ion can heavily reduce the stability of {η ² -(X@C _n )}PtL ₂ complexes. Moreover, the theoretical evidence strongly suggests that the backward-bonding orbital interactions as well as the stability increase in the order {η ² -(X@C _n )}Pt(CO) ₂ < {η ² -(X@C _n )}Pt(PPh ₃ ) ₂ < {η ² -(X@C _n )}Pt(NHC ^Me ) ₂ . As a result, these theoretical observations can provide experimental chemists a promising synthetic direction.
Competing Interests: The authors declare no competing financial interest.