THE MARCUS INVERTED REGION FROM THEORY TO EXPERIMENT

Electron back-transfer reactions are the reactions in which the occurr ence of the inverted region predicted by the Marcus theory was detecte d for the first time in an intermolecular electron transfer. In this r egion, contrary to all intuition, a further increase in the exergonici ty causes a decrease in the reaction rate. In each case the forward re actions showed the classical Rehm-Weller behavior: the rate constant k approaches k(diff) of the diffusion-controlled reaction. This differe nce has not yet been explained satisfactorily.