Electron transfer Marcus inverted region

Marcus inverted region for electron transfer) See inverted region. 

Guldi D M and Asmus K-D 1997 Electron transfer from Cjg D2) and Cjg C2 ) to radical cations of various arenes evidence for the Marcus inverted region J. Am. Chem. See. 119 5744-5... 

Gould I R, Ege D, Mattes S L and Farid S 1987 Return electron transfer with geminate radical ion pairs - observation of the Marcus inverted region J. Am. Chem. Soc. 109 3794-6... 

The PET process in the dyad is located in the normal region of the Marcus curve, while the back-electron transfer from Q0 to ZnPor+ is in the Marcus inverted region (Figure 6.27). 

The further improvement of the product yield (100%) was achieved by employing AcrPh + instead of AcrH + and this can also be ascribed to the slower back-electron transfer rate for the former than the latter [109]. In the Marcus-inverted region, the back-electron transfer becomes slower with increasing the driving force. Because the EZx value of AcrPh" (E°x versus SCE = - 0.55 V)... 

Jiang, H. Xu, H. Ye, J. Synthesis and cation-mediated electron transfer in intramolecular fluorescence quenching of donor-acceptor podands observation of Marcus inverted region in forward electron transfer reactions. 

In Ref. 142, a detailed analysis of the forward and reverse electron transfer rates for capped P-L2-Q in a variety of solvents was given. The results show that forward electron transfer is in the normal region Er > — AG° and charge recombination is in the Marcus inverted region, Er < — AG°. 

The Marcus Inverted Region (MIR) is that part of the function of rate constant versus free energy where a chemical reaction becomes slower as it becomes more exothermic. It has been observed in many thermal electron transfer processes such as neutralization of ion pairs, but not for photoinduced charge separation between neutral molecules. The reasons for this discrepancy have been the object of much controversy in recent years, and the present article gives a critical summary of the theoretical basis of the MIR as well as of the explanations proposed for its absence in photoinduced electron transfer. The role of the solvent receives special attention, notably in view of the possible effects of dielectric saturation in the field of ions. The relationship between the MIR and the theories of radiationless transitions is a topic of current development, although in the Marcus-Hush Model electron transfer is treated as a thermally activated process. 

Table 4. Examples of electron transfer reactions which show the Marcus Inverted Region...

The second article deals with probably the most fascinating predictions of modem electron transfer theories i.e. the Marcus Inverted Region (M.I.R.) . It was shown only one decade ago, nearly 20 years after the first formulation of the Marcus theory, that the M.I.R. does indeed exist First for thermal charge shifts and later for charge recombination. Even a charge separation reaction was recently found to behave according to the Marcus theory. Nevertheless, many reactions do not follow the Marcus model and therefore the second contribution of this issue is mainly concerned with this question. 

In Fig. 13.13, the CR rates in the Marcus inverted region are much slower than the CS rates from both the singlet and triplet excited states in the Marcus normal region. This allows a subsequent electron transfer from an additional electron donor such as ferrocene (Fc) to ZnP+ in the triad molecule (Fc-ZnP+ -C60 ) to produce the final CS state, Fc+-ZnP-C60 , in competition with the back electron transfer in the initial CS states [41]. Such multi-step electron-transfer processes are expanded to the tetrad molecule (Fc-ZnP-H2P-C60) as shown in Fig. 13.16a [50], In the final CS state, Fc+-ZnP-H2P-C60 , charges are separated at... 

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