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.