Diabatic activation free energy, ∆A ‡ IJ , varies greatly: the DMDQ +2/+1 , OH-Vi +2/+1 , Me-Vi +2/+1 , and 2HNQ 0/-1 reactions are nearly barrierless, the dBR5 -1/-2 reaction has a substantial barrier, and the remainders are in the middle. When compared to the first ETs, all of the second ETs exhibit a large increase in the barrier energy. According to Section , dBR5 becomes very nucleophile after the first ET. This makes it difficult to add the second electron, leading to an unreachable activation barrier. The activation barrier free energy for dBR5 -1/-2 emphasizes the possibility for protonation after the first ET. Hence, we believe that these amplitudes of couplings suggest adiabatic ET reactions.