3.3 TST Calculation:
From TST calculation, shown in Table S1, it is evident that for neutral C60, for both the ‘Direct’ as well as ‘Alternative’ approaches, each step of the 6-6 MDA reaction is kinetically feasible at 400 K. The second DA step via ‘Direct’ approach is observed to be 10 times faster than the ‘Alternative’ approach. In harmony with the activation barrier calculation, the rate constants for the third functionalization are calculated to be comparable enough irrespective of the approaches. The rate constant (k) for the fourth DA reaction is observed to be 1.48 sec-1 at 400 K. However, the change in magnitudes of rate constants for the 6-6 MDA reaction of Li+@C60 is in accordance with the diminished activation barrier for each step compared to its neutral analogue. From Table S2 , it is apparent that each step of the MDA reaction via ‘Direct’ as well as ‘Alternative’ approaches is kinetically achievable in between 300 K - 400 K. However, the associated rate constants for both second and third DA reactions in ‘Direct’ pathway are 10 times faster than the respective ‘Alternative’ pathway at 300 K. The value of k for the final functionalization step at 300 K is calculated to be 0.89 sec-1.
The kinetic study also infers that a relatively higher temperature is required for the kinetic attainment of 6-5 MDA reaction than their 6-6 counterpart for both neutral C60 as well as Li+@C60 (Table S3 andTable S4 ). The magnitudes of rate constants suggest that temperature range 500 K-600 K is suitable for 6-5 MDA reaction in the absence of Li+, which eventually changes to 400 K-500 K due to Li+ encapsulation.