Mechanisms of electron transfer

Fig. 11. Mechanism of electron transfer from an excited dye molecule to a silver haUde crystal where HOMO and LUMO are highest occupied and lowest...

N2 recognized as a bridging ligand in ((NH3)5RuN2Ru(NH3)5] by D. F. Harrison, E. Weissterger, and H. Taute. (H. Taute, 1983 Nobel Prize for chemistry for his work on the mechanisms of electron transfer reactions especially in metal complexes ). 

H. Taube (Stanford) mechanisms of electron transfer reactions of metal complexes. 

Mechanisms of electron transfer reactions the bridge activated complex. A. Haim, Prog. Inorg. Chem., 1983, 30, 273-358 (196). 

How deeply one wishes to query the mechanism depends on the detail sought. In one sense, the quest is never done a finer and finer resolution of the mechanism may be obtained with further study. For example, the rates and mechanisms of electron transfer reactions have been studied experimentally and theoretically since the 1950s. but the research continues unabated as issues of ever finer detail and broader import are examined. The same can be said of other reactions—nucleophilic substitution, hydrolysis, etc. 

Butler-Volmer kinetics and mechanism of electron transfer, 587... 

W. L. Reynolds and R. W. Lumry, Mechanisms of Electron Transfer, Ronald Press, New York, 1966. 

The main goal of the present study was to discover new ecl-ac-tive complexes. But the first example may demonstrate that complexes known to show eel can serve to gain more insight into the mechanism of electron transfer processes. 

Nowadays, studies of direct electrochemistry of redox proteins at the electrodesolution interface have held more and more scientists interest. Those studies are a convenient and informative means for understanding the kinetics and thermodynamics of biological redox processes. And they may provide a model for the study of the mechanism of electron transfer between enzymes in biological systems, and establish a foundation for fabricating new kinds of biosensors or enzymatic bioreactors. 

Meeting these design criteria requires a sound knowledge of the fundamental mechanisms of electron transfer processes. Although ET is the most fundamental of all chemical reactions, it is by no means simple This realization is particularly evident in the case of long-range ET processes which forms the basis of this essay. 

Marcus theory is based on certain assumptions that will be discussed later. The main goal of computer simulations of electron transfer is to check some of these assumptions and to provide additional microscopic insight into the mechanism of electron transfer and the microscopic factors that influence the rate of transfer. We discuss these issues in the following section for the simple case of outer-sphere electron transfer reactions. 

B37. W. L. Reynolds and R. W. Lumry, Mechanisms of Electron Transfer, Ronald Press, NY, 1966. B38. D. B. Rorabacher and J. F. Endicott (eds.) Mechanistic Aspects of Inorganic Reactions, ACS Symposium Series, 198, American Chemical Society, Washington, D.C. 1982. 

Scheme 1.5 represents case f, that is, an anion-radical belonging to the borderline between moderately and completely delocalized species. Its optical spectra, along with frontier orbital analysis, testifies that in this anion-radical there is a positive overlap between C-N bonds and the psendo-geminal carbons of the opposite rings, as shown by the dashed lines in the strnctnre of Scheme 1.5 (Nelsen et al. 2005). Taken together, the experimental results considered provide direct evidence for the throngh-bond mechanism of electron transfer in these paracyclophane systems.

Temperature Dependence of the Kinetics. In an earlier article (22) we gave a detailed analysis of the temperature dependence of the rate of electron transfer from 1 (BPh ) to Q (Figure 4). Here we summarize some of the important considerations and discuss further the possible insights that the temperature and detection-wavelength dependence of the kinetics may give into the molecular mechanism of electron transfer and the overall charge separation process. 

Kuzmin MG, Soboleva IV, Dolotova EV (2007) The behavior of exciplex decay processes and interplay of radiationless transition and preliminary reorganization mechanisms of electron transfer in loose and tight pairs of reactants. J Phys Chem A 111 206... 

At this point it is necessary to consider the mechanism of electron-transfer luminescence in solutions which cannot involve ion-radical annihilation because both cation and anion of the fluorescer are not formed. Such emission can be achieved by treating anion radicals with chemical oxidants or electrochemically under conditions where the corresponding cation cannot be produced, and it may also be achieved by electrochemical reduction of cations without producing the corresponding anion. In addition to triplets, three types of processes and pathways have been proposed to help explain why such emission occurs. These may be described as (7) impurities, (2) ion-radical aggregates, and (5) heterogeneous electron transfer. It is evident63 that impurities,... 

Harry Gray Two points in Prof. Taube s paper quoted as experiments in progress haven t been mentioned. Both are concerned with the mechanism of electron transfer, because the transmission in the ligand, wherever the attack is, is through the 7r-system, and in cobalt(III) in the detectable radical ion intermediate, because of the improbability of resonance transfer from tt to electron resonance experiment in which one tries the reduction by chromous and looks for the ESR signal of the radical ion. 

Shiga, K., Tollin, G. Studies on the mechanism of electron transfer in flavodoxins. In Flavins and flavoproteins (Singer, T. P. ed.) pp. 422-433. Amsterdam, Elsevier 1976... 

In studies of analogs of the redox cofactor pyrroloquinoline quinone (PQQ), synthetic efforts have focused initially on isosteric, isomeric structures that reflect on important mechanisms of electron-transfer catalysis mediated by PQQ. These studies provide insight into the choice of PQQ as an electron-transfer catalyst in nature, and bear directly on pharmaceutical applications of this vitamin-like nutritional factor. 

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