Electron transfer radical closed-shell structures

Electron Transfer (ET) is a basic chemical process and is the fundamental step in oxidation-reduction reactions. Therefore it can be found in organic chemistry, inorganic chemistry, material science and biochemistry. The study of the structure and reactivity of radical ions, the primary species formed upon electron transfer of parent closed-shell systems, has been a topic of interest for several years. Initially, the research in this field focused on the experimental exploration of molecular structures in terms of their hyperfine structure. However, the interest has shifted during the past decade to the mechanistic studies of these reactive intermediates. 

A similar mechanism (Eq. 4) is operative in reactions of saturated hydrocarbons with closed-shell oxidizing electrophiles (E = Haln+, NOz+, etc.) where the H-trans-fer from a C-H bond is accompanied by an ET through the linearly H-coupled fragment (H-coupled electron transfer) [13]. The hydrocarbon part of the transition structures resembles the respective radical cation (that for the reaction of adamantane with Cl7+ is shown (6) in Scheme 2) [13]. 

Exercise 6.10 The ground and promoted states of the reactants, R and R are shown in Fig. 6.Ans.8 below using the FO—VB representation, which is the simplest one for making predictions on stereochemistry. The electronic structure of R displays an electron transfer from the nucleophile to the C C bond. A transfer to the a-orbital is not relevant, as this would generate a closed-shell cyclopropane that cannot form a bond with the oxidized nucleophile. It is therefore the a orbital that accepts the transferred electron, thus generating the triplet oo- configuration of the C-C bond. Now, since R and R differ by one-electron shift from Nu to the a orbital of the cation radical, the corresponding... 

To explain the conversion of the Fe to Fe, investigators have postulated that the two hydrated ions are linked by a structured chain of water molecules. The assumption is that one of the electrons of the Fe valence shell enters the valence shell of an oxygen atom of a neighboring water molecule. The water molecule releases a hydrogen-free radical (one hydrogen atom and one electron), which is transferred from water molecule to water molecule until it reaches a water molecule close to Fe, at which point the electron is transferred to Fe, yielding Fe. ... 

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