It is interesting that this mechanism has activation enthalpy of +102 ± 1 kJ/mol, a value that is half of the first-order case. In Fig. , the TS structure displays a long-distance In•••CH3 interaction of 3.26 Å, while the incoming CH3 radical is aligned toward this interaction to form a dihedral angle of 168.0°. However, its rate constant ranging from 1.45 x10 -13 to 1.84 x10 -1 is much slower than the CH3 recombination into C2H6. The kinetic simulation for this mechanism, in combination with the homolytic dissociation route, is actually identical to the plot from Mech 1 that is displayed in Fig. . This fact confirms that the radical attack is not relevant for the TMI decomposition in gas phase, as formerly verified by Buchan and collaborators in He carrier. Mech 4. The bimolecular reaction between TMI-TMI molecules is an uphill process with ΔrG = 138-140 kJ/mol at the temperature interval of interest. Such high values are mainly driven by an unfavorable enthalpy term, in which the C-C bond formation does not compensate the amount of energy that is necessary to break 2 In-C bonds. Based on these facts, it is likely that DMI could undergo dimerization to form a compound with binding energy of -204 kJ/mol.