Electron transfer synchronous

This scheme includes ET rate constants only for the d - d electron-transfer processes, in which the system conformation is conserved, and conformational and ET steps only occur sequentially. Intuitively, it might be expected that the kinetic scheme must include ET that is synchronous with a conformational change in the medium coordinate. However, we showed [10a] that it is not necessary to include the diagonal processes (e.g., A Ig) when considering stable substates. 

For most substituents, in the region of neutrality and at higher pH values, the half-wave potential becomes independent of pH. In this region, electron transfer is synchronous with bond cleavage and loss of the leaving group creates a carbon... 

Transition into the Kolbe region at platinum is associated with the formation of an oxide layer. Acetate ions are believed to be more strongly adsorbed on this layer than is water. Conversion of water to oxygen is then suppressed in favour of the oxidation of acetate ions [59, 60. Electron transfer from acetate is synchronous with cleavage of the alkyl-carboxylate bond leaving adsorbed carbon dioxide and... 

Manecke et al.16s synthesized a semiconducting polymeric complex which possessed both bis(ethylene-l,2-dithiolato)Cu(II) and a phthalocyanine-Cu(II)-type structure 54. This Cu complex exhibited high catalytic activity in the oxidative polymerization of XOH, about 50 times higher than that of pyridine-Cu. A synchronous four-electron-transfer mechanism was proposed for the catalysis of 54. The phthalo-cyanine-Cu(II) type structure of 54 is presumed to form a complex with molecular... 

Such a mechanism might play an important role in a metal-ion-catalyzed enzymic oxidation in vivo, in which metal ions work cooperatively 166. A synchronous four-electron-transfer requires a specific spatial arrangement which should be posable in a macromolecular environment. 

Phenol radical cations exist only in strong acidic solutions (pKa -1) [1, 2]. However, in non-polar media phenol radical cations with lifetimes up to some hundred nanoseconds were obtained by pulse radiolysis [3], The free electron transfer from phenols (ArOH) to primary parent solvent radical cations (RX +) (1) resulted in the parallel and synchroneous generation of phenol radical cations as well as phenoxyl radicals in equal amounts, caused by an extremely rapid electron jump in the time scale of molecule oscillations since the rotation of the hydroxyl groups around the C - OH is strongly connected with pulsations in the electron distribution of the highest molecular orbitals [4-6]. 

The species NuT R of Scheme 1-2 is not a radical pair it is a covalent molecule of the product resulting from the SN2 reaction. The process of transfer of the R group to a Nu reactant proceeds in synchronicity with a one-electron shift and R-Z bond disruption. At that time, two radical particles, Nu and R (formed in the course of reaction) remain immediately close and therefore unite rapidly. A one-electron shift may or may not lead to the formation of radical particles. There are many reactions that consist not of a one-electron shift, but of a one-electron transfer. The initial results of such one-electron transfers involves the formation of ion radicals. 

Here, the longer arrow indicates the direction of the preferred electron transfer from the metal to the substrate (S), and the shorter arrow indicates the direction of the reverse transfer. It is obvious that four protons accompanied by the water molecule rearrangement cannot be transferred in one synchronous step. Owing to the high degree of electron delocalization in the polynuclear metal complexes, these complexes are more suitable for multi-electron processes. 

Summary BusSnH is an effective reagent for partial conversion of Si-Cl into Si-H groups. The hydrogenation mechanism postulates the coordination of the catalyst or the solvent to silicon giving a hypervalent intermediate in the first step, followed by the attack of tributyltin hydride by a single electron transfer or a synchronous hydride transfer. This mechanism implies that the intermediate containing a hypervalent silicon atom reacts faster than the starting tetracoordinate silane. 

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