Complexation shifts the redox electron level

We compare a simple electron transfer reaction of hydrated redox particles, OX , + e(STD) = RED, with an electron transfer reaction of complex redox particles. 

+ e sTD) = L RED where L is the ligand coordinated with redox particles and ejsTD, is the electron in the gaseous standard state at the outer potential of the aqueous solution (Refer to Chap. 4.). The following reaction cycle may be used to obtain the energy relationship between the two redox reactions  

Complexation therefore raises the standard Fermi level of redox electrons ep(KEDcs) provided that the affinity of ligand coordination is greater with the oxidant particle than with the reductant particle (- dGox - dG c) whereas, the complexation lowers the standard Fermi level of redox electrons Ef(redox) provided that the affinity of ligand coordination is smaller with the oxidant particle than with the reductant particle (- dGox - dG o)- With a shift of the standard Fermi level of redox electrons due to complexation, the most probable electron levels esED and cox of the redox particles are also shifted in the same direction. 

The concentration of complex particles is obtained in Eqn. 8-80 by assuming that the complexation processes of Eqns. 8-76 and 8-78 are in equilibrium  

we consider a redox reaction involving the transfer of anodic electrons in which the complexation of redox particles is involved at metal electrodes. The anodic reaction current, i, may be represented, to a first approximation, by the reaction current, i Cenio), at the Fermi level of the electrode cnn). From Eqns. 8-6 and 8-10 we obtain Eqn. 8-81 for the transfer ciurent of anodic electrons, iX, of simply hydrated redox particles or complex redox particles at the Fermi level of the electrode as follows  

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