Single Electron Transfer Reactions in Organic Chemistry

1 Single Electron Transfer Reactions in Organic Chemistry 

Electron transfer as an elementary step is a necessary part of the stoichiometric mechanism of all redox and, as has recently been shown, some heterolytic reactions. The most important reactions are those of single-electron transfer (SET). The multi-electron transport in chemical and biochemical transformations consists, as a rule, of a series of consecutive single-electron transfer reactions, while the one-step two-electron transfers are relatively rare. 

In organic chemistry, the reactions under consideration could first be registered in pure form by characteristic broadening of lines in the ESR spectra of radical-ions  

The general theory of the elementary act of charge transfer in polar solvents has been well worked out and described in great detail in a number of monographs [2,4,14] and special reviews [15-19]. Here we offer some extracts from it that may give an idea of which energy and structural requirement must be satisfied by the system where the electron transfer takes place and how these characteristics affect the rate of a given reaction. 

Important for the choice of a physical mechanism of the electron transfer step is the degree of interaction between the electron states Ei and Ef in the area of their intersection qif. In case the interaction is not spin-forbidden, the split of the energy level effected by it will be determined by the off-diagonal 

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