Electron transfer complex reduction potential values

Simple thermodynamic considerations state that the reduction process is favoured (i.e. more positive cu(ii)/cu(p potential values are obtained) if the electron transfer is exothermic (AH° negative) and if the molecular disorder increases (AS° positive). It is therefore evident that the positive potential value for the reduction of azurin (as well as that of the most blue copper proteins) is favoured by the enthalpic factor. This means that the metal-to-ligand interactions inside the first coordination sphere (which favour the stability of the reduced form over the oxidized form) prevail over the metal complex-to-solvent interactions inside the second... 

In the presence of oxygen, the lifetimes of both radical ion pairs (i.e., ZnP +-C6o and ZnP +-H2P-C6o ) are decreased significantly due to oxygen-catalyzed back-electron transfer (BET) processes between Ceo and ZnP " [76]. The catalytic participation of O2 in an intramolecular BET between Ceo and ZnP + in ZnP-linked Ceo is depicted in Scheme 6 [76]. The intermolecular ET from Ceo to O2 is facilitated by the partial coordination of O2 to ZnP " in the transient state (denoted as in Scheme 6) [76]. Consequently, the one-electron reduction potential of the resulting 02 is shifted toward positive values, namely in favor of the ET event. The strong coordination of O2 to Zn(II) ion has been well established [77]. The complexation is then followed by a rapid intramolecular... 

Redox-Mediated Metal Deposition. A reduced polyimide surface can function as a reducing substrate for subsequent deposition of metal ions from solution. For metal reduction to occur at a polymer surface, the electron transfer reaction must be kinetically uninhibited and thermodynamically favored, i.e., the reduction potential of the dissolved metal complex must be more positive than the oxidation potential of the reduced film. Redox-mediated metal deposition results in oxidation of the polymer film back to the original neutral state. The reduction and oxidation peak potential values for different metal complexes and metal deposits in nonaqueous solvents as measured by cyclic voltammetry are listed in Table III. 

Tohnan and Lee constructed a type 1-like site linked to a type 2-like site and investigated the potential for intramolecular electron transfer between the two. Their coordination scheme is illustrated in Figme 6(a) the structure of their complex in shown in Figure 6(b). Cyclic voltammetry showed the two Cu(II) atoms to undergo quasi-reversible, independent reduction with 1/2 values consistent with the two copper atoms coordination -0.911 V for the CuSR site, -0.112 V for the CuPyr one. These studies did not address the question of intramolecular electron transfer between the two sites, however. 

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