Coupled Electron Transfer

Synonyms

Electron transfer; Kinetically coupled electron transfer

Definition

Coupled electron transfer is a process in which a relatively slow electron transfer reaction is preceded by a rapid but thermodynamically unfavorable nonelectron transfer reaction that is required to activate the system for electron transfer.

Basic Characteristics

Coupled electron transfer occurs when a relatively slow nonadiabatic (true electron transfer) reaction is preceded by a rapid but thermodynamically unfavorable, adiabatic (nonelectron transfer) reaction that is required to activate the system for electron transfer. Since the activated and unreactive states exist in an equilibrium that favors the unreactive state, the observed rate constant (k_obs) for the redox reaction under saturating conditions is an apparent value equal to the product of the true electron transfer rate constant (k_ET) and the equilibrium constant for the preceding reaction step (Eq. 1).

$$ {k}_{\mathrm{obs}}={k_{\mathrm{ET}}}^{\ast...