Atom/group transfer

Besides, iron(IV) imides have also been implicated as reaction intermediates in nitrogen atom/group transfer reactions [36]. The first structurally characterized iron-imide complex was reported by Lee and coworkers [37] through the reaction of FeCls with 2 equiv. of LiNH Bu in THF, giving one of the products as a stable site-differentiated cubane having three Fe(lll) and one Fe(IV) centers and the Fe(IV) center has a terminally bonded imido ligand (Scheme 4). 

Title Metal Complexes for Use in Olefin Metathesis and Atom Group Transfer Reactions... 

To unlock its full potential, C-H activation has to be coupled with a functionalization event (e.g., 3—>4). For instance, a hydride elimination occurring after the formation of metal complexes such as 3 furnishes olefins, versatile intermediates for further modification reactions. Transition metal-catalyzed atom- or atom group-transfer reactions that permit the introduction of oxygen-, carbon-, and boron-containing groups are also presented. 

Arenesulfonyl iodide and bromide are rather unstable compounds because of low bond dissociation energies of their S02-I and S02-Br. Therefore, treatment of p-tosyl bromide (47) with alkene or allene (48) produces 1,2-adduct (49) through the addition of the formed p-tosyl radical onto the allene as shown in eq. 4.19 [52]. Here, the p-tosyl radical attacks the central sp carbon of the allene group to generate the stable allylic radical, and then it reacts with p-tosyl bromide to give 1,2-adduct (49) and a p-tosyl radical again, i.e., chain pathway. So, this is also an atom(group)-transfer reaction. 

The most traditional theory for chemical reaction rates is the transition state theory (TST) established in 1940 s. It has recently been disclosed, however, that the TST caimot be applied to varieties of solution reactions. Examples can be found in biological enzymatic reactions, electron or proton transfer reactions atom-group transfer reactions, and isomerization reactions. Smdy of solution reactions is one of the most traditional as well as the most fundamental subjects in chemistry. The situation mentioned above means, nevertheless, that we have not yet established a general expression on rates of solution reactions. Accordingly, many discussions have been stimulated for investigating the unknown general expression. ... 

Usually, X is proportional to the viscosity of the solvent, t]. In many kinds of solution reactions, the rate constant decreases with an increase in t] [32]. These reactions cover not only elementary reactions such as electron-, excitation-, atom-group-transfer reactions, and isomerization reactions, but also composite reactions such as biological ones, including enzymatic reactions. The general formula for rates of solution reactions has not been clarified fully yet, in spite of solution reactions being one of the most central subjects in chemistry. 

Electron and Atom Group Transfer Properties of Protein Systems Hans E. M. Christensen, Lars S. Conrad, Jens Ulstrup,... 

Ulstrup J. Temperature dependence of the transfer coefficient in electron and atom group transfer processes. Electrochim Acta 1984 29 1377-80. 

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