A Theoretical Study on the Stability of PtL2 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.