3.2.2 MDA reaction on 6-6 double bond of Li+@C60:
The preliminary adduct complex, A16-6SL (7.7kcal/mol) is identified as equally stable like its direct counterpart. As depicted inFigure 5 , the activation barrier corresponding to the conversion of A16-6SL to R16-6SL via TS16-6SL is lowered by 4.2 kcal/mol compared to its neutral counterpart. The associated enthalpy change (-32.1kcal/mol) indicates that the second functionalization on Li+-encapsulated fullerene via alternative way is also thermodynamically feasible. In the third DA reaction, the barrier height (TS16-6SL) corresponding to R26-6Lformation is 14.1 kcal/mol, which is almost comparable to its ‘Direct’ analogue. The exothermic nature of the third DA reaction is also noted from the associated enthalpy change (-27.3kcal/mol). Similar to the neutral C60 analogue, for Li+@C60 also, the addition of fourth butadiene molecule will be obtained in a similar way to that of the ‘Direct’ one. Like the neutral C60 fabrication, for Li+@C60also, all three DA steps are synchronous as the maximum difference of bond length between the two C-C bonds forming between the diene moiety and fullerene surface in the TS is 0.026 Å.