Reorganization self-exchange

It has been shown so far that internal and external factors can be combined in the control of the electron-transfer rate. Although in most cases a simple theoretical treatment, e.g. by the Marcus approach, is prevented by the coincidence of these factors, it is clear that the observed features for the isoenergetic self-exchange differ by the electronic coupling and the free energy of activation. Then it is also difficult to separate the inner- and outer-sphere reorganization energies. 

The reorganization energy of a self-exchange reaction is denoted A(0) (from the fact that AG° = 0) and is an important quantity in the Marcus theory, where it can be shown that the activation free energy of a self-exchange reaction, AG(0), is equal to X.(0)/4. It is also possible to measure rate constants of self-exchange processes experimentally and thus get access to (0) via this relationship. 

This concept of the prior reorganization of the solvent is best illustrated by a charge shift e.t, something like the self-exchange reaction of a neutral molecule M with its ion M+ see scheme 3 [57]. 

The reorganization energy for the (cross) ET reactions of NO+/arene pairs is about 2.5 eV (as evaluated from the self-exchange rates of aromatic donors and the NO+ acceptor) [28],... 

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