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

[Image: see text] 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.