The Marcus Inverted Region from Theory to Experiment

Electron back‐transfer reactions are the reactions in which the occurrence of the inverted region predicted by the Marcus theory was detected for the first time in an inter molecular electron transfer. In this region, contrary to all intuition, a further increase in the exergonicity causes a decrease in the reaction rate. In each case the forward reactions showed the classical Rehm–Weller behavior the rate constant k approaches k diff of the diffusion‐controlled reaction. This difference has not yet been explained satisfactorily.