Single-electron-transferring agents

This could be explained in terms of disproportionation of the radical-anion to dianion with subsequent protonation. However, a much more complete explanation followed the realisation that, in most cases, the radical-anion acts not only as a base but also as a single electron-transfer agent (the so-called DISP mechanisms). In particular a comparison of observed cyclic voltammetric behaviour of substituted azobenzenes in the presence of weak acids with that predicted using digital simulation based on various mechanistic possibilities has established the DISPl route given in Eq. (3) (reactions 1-4). 

New Sequential Reactions with Single Electron Transferring Agents... 

Basicity is not the only general property of radical anions, anions, and dianions. Each may act as a nucleophile, a single-electron transfer agent, and as a base—sometimes all three As with conventionally generated bases, in what Baizer has dubbed secular chemistry, sterically hindered EGBs are useful because proton abstraction becomes favored over nucleophilic substitutions and additions. 

Peroxydisulphate ions are reduced by solvated electrons to give tbe sulphate radical-anion which is a powerful oxidising agent, functioning by single electron transfer to form sulphate dianion, fhus irradiation of solutions containing peroxydisulphate and an alkyl or alkoxybenzene gives the substrate radical-cation in a diffusion-controlled reaction [63],... 

Mononuclear octahedral/trigonal bipyramidal iron centers are found in either the ferric or the ferrous oxidation state (Whittaker etal., 1984 Arciero et ai, 1983). Because the iron may participate directly in catalysis as either a Lewis acid or base, only one state is the active form for a given enzyme. Transient redox changes may occur during turnover, but the enzyme returns to its initial condition. In contrast the tetrahedral mononuclear iron proteins appear to function primarily as electron transfer agents and therefore change oxidation state with a single turnover. 

For the reductive desulfonylation step, necessary when the formation of a single bond is wanted, a number of electron transfer agents are available [397]. A mild and convenient method makes use of magnesium in ethanol... 

Under modified conditions not only the defluorination of perfluorocycloalkanes to per-fluoroaromatics was achieved, but also the formation of perfluorocycloalkenes and pcrfluoroal-kenes. In this process the photosensitizer decamethylferrocene plays the role of the single-electron-transfer (SET) reducing agent.211... 

Iron is the most abundant metal on earth and the commonest electron transfer agents involve iron complexes. Life is thought to have evolved in reductive conditions, in which the dominant form of iron would be as iron sulfide, not iron oxide. The simplest forms of electron transfer agents (found in plants and bacteria) involve iron with thiolate ligands. Some simple electron transfer proteins, such as rubredoxin, contain a single iron centre in an S4 donor environment within a protein (Fig. 10-7). 

The reactions of the aqueous electron (e aq) with specific organic and inorganic compounds have been studied extensively [4-6]. The e aq is a powerful reducing agent, with a reduction potential of —2.77 V. The reactions of the e aq are single-electron transfer, the general form of which is ... 

The role of the silver salt is not completely understood. No evidence for a single electron transfer mechanism has been found. Although extremely reactive electrophilic fluorinating agents, such as xenon fluoride triflate (FXeOTf) or trifluoromcthanesulfonyloxy fluoride (TfOF), may be generated from the combination of xenon difluoride and silver(l) triflate, the reaction appears to proceed following initial interaction of the alkcnc with the silver ion. ... 

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