Chemical Activation by Electron Transfer in Charge-Transfer Complexes. Formation and Reactions of Transient Ion Radical Pairs.

Kochi, Jay K.; Carlson, Rolf; Ragnarsson, Ulf; Ericsson, Tore; Yamada, H.; Långström, Bengt; Tokii, Tadashi

doi:10.3891/acta.chem.scand.44-0409

Cited by 83 publications

(37 citation statements)

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“…This assumption is consistent with the data on the formation of a CTC between arenes and their ARFs 56,57 and on the detection of the CTCs as key inter mediates of the reactions that proceed via the ET mecha nism [58][59][60]. Cyanophenylation of aromatic nitriles by the terephthalonitrile dianion…”

supporting

confidence: 78%

Reductive activation of arenecarbonitriles for the reactions with some carbon-centered electrophiles: the reaction mechanisms and synthetic applications

2008

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Synthetic and mechanistic aspects of the developed approach to the activation of aromatic nitriles are considered. The approach is based on the transformation of aromatic nitriles into stable anionic reduced forms. The latter, as shown for the reactions with alkyl halides and cyanoarenes, are promising reactants for the reactions with carbon centered electrophiles.Numerous methods for the modification of basic com pounds of the aromatic series aimed at obtaining various practically important substances and materials are based on electrophilic substitution. For electron deficient are nes, this reaction is hindered and limited to a narrow range of the most reactive electrophiles with the reaction center on an atom different from carbon, and their interaction with carbon centered electrophiles is virtually impossible. The reductive activation of the substrate provides a basic possibility for overcoming this restriction. The essence of the approach is that one or two electron reduction of electron withdrawing arenes in aprotic media makes it possible to generate relatively stable anionic reduced forms (ARFs), viz., radical anions, dianions, and cyclohexadie nyl anions retaining, as a whole, the structure of precur sors and used in syntheses as reactants.In our opinion, arenecarbonitriles are especially valu able as substrates in the framework of this approach. These compounds are prone, to a considerable extent, to the formation of ARFs combining stability in aprotic media with high reactivity toward electrophiles. A possi bility to generate ARFs of arenecarbonitriles in concen trations significant for preparative syntheses allows their use as highly reactive nucleophilic and radical (in the case of radical anions) synthons. In addition, they are valuable models for studying the structure and reactivity of the ARFs, first of all, from the viewpoint of a general theoretical problem of the competition between the prop erties of a nucleophile/base (S N mechanism) and a one electron reducing agent (ET mechanism). It is also im portant to know the factors that determine this competi tion for planning the synthesis on the basis of reductive activation, because the mechanism of the interaction of the ARFs with the electrophile determines the nature of the products formed.The results of recent studies generalized in the present review show that the specific features of the electronic structure of the ARFs of basic arenecarbonitriles, name ly, benzonitrile (1), o (2), m (3), and p tolunitrile (4), 1 naphthonitrile (5), 9 cyanoanthracene (6), phthaloni trile (7), terephthalonitrile (8), and 9,10 dicyanoan thracene (9), predetermine products of their interaction with carbon centered electrophiles. These products are valuable from the synthetic point of view. First, the reac tions proceed exclusively at the aromatic moiety and, second, the products containing the readily and variably modifiable cyano group provide wide possibilities of their further use for preparing practically important substan ces and materials. Nature and el...

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supporting

confidence: 78%

Reductive activation of arenecarbonitriles for the reactions with some carbon-centered electrophiles: the reaction mechanisms and synthetic applications

2008

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“…This distance is even shorter than those that have been observed for CT complexes in the solid state. [25,26] There are recent precedents in the literature showing the existence of CT complexes in pillared MOFs between a dipyridylnaphthalenediimide pillar and 2,6-naphthalenedicarboxylate linker in the layers with a distance between the centers of the two molecules of 3.42 . [27] Although theoretical calculations will be useful to determine the electron density of the two ligands in 2, as has been performed on related examples, [28] the spatial proximity between the amino-and nitroisophthalates in the MOF would be responsible for the fast electron-transfer quenching between them, which causes the lack of photochemical response on the nanosecond timescale.…”

Section: Resultsmentioning

confidence: 99%

Photophysical Evidence of Charge‐Transfer‐Complex Pairs in Mixed‐Linker 5‐Amino/5‐Nitroisophthalate CAU‐10

et al. 2014

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The photochemistry of two isostructural metal-organic frameworks based on 5-amino/5-formamidoisophthalate (CAU-10-NH2 /NHCHO) or mixed-linker 5-amino/5-formamido- and 5-nitroisophthalate (CAU-10-NO2 /NH2 /NHCHO) has been studied using laser flash photolysis. 355 nm excitation of CAU-10-NH2 /NHCHO leads to a transient absorption spectrum characterized by a broad continuous absorption from 380 to 800 nm that was attributed to the presence of holes (440 nm) and electrons (600 nm) based on iPrOH and N2 O quenching, respectively. In contrast, no transients were observed for the isostructural mixed-linker CAU-10-NO2 /NH2 /NHCHO, data that is compatible with the uniform distribution of linkers 5-amino/5-formamido/5-nitroisophthalate as charge-transfer complex pairs. The same effect of quenching of 5-aminoisophthalate transients by 5-nitroisophthalate was also observed in aqueous solution (pH 9) but with much lower strength. Using a simple Stern-Volmer formalism allowed the estimation of the interaction of 5-aminoisophthalate with 5-nitroisophthalate in MOF to be 5.2×10(4) times stronger than in the aqueous phase.

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“…Generally, its reactions with bi-and polycyclic arenes possessing, as a rule, low ionisation potentials 110 give rise to the corresponding radical cations or their reaction products. 55,78,109 Thus, the reactions of naphthalene with nitrosonium salts in trifluoroacetic acid at *20 8C afforded initially a monomeric radical cation, followed by the formation of a dimeric radical cation and, finally, of a mixture of hydrocarbons C 10 H 7 ± (C 10 H 6 ) m ± C 10 H 7 . 109,111,112 Most likely, the transfer of one electron from the aromatic substrate to the NO + cation is preceded by the formation of the ArH7NO + p-complex.…”

Section: Ref 88)mentioning

confidence: 99%

Nitrosonium complexes of organic compounds. Structure and reactivity

Borodkin¹,

Shubin²

2001

Russ. Chem. Rev.

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Data on the structures and reactivities of nitrosonium Data on the structures and reactivities of nitrosonium complexes of organic compounds are systematised and general-complexes of organic compounds are systematised and generalised. The characteristic features of the electronic structure of the ised. The characteristic features of the electronic structure of the NO NO + + cation are responsible for a wide structural variety of cation are responsible for a wide structural variety of nitrosonium complexes. Reactions of nitrosonium complexes are nitrosonium complexes. Reactions of nitrosonium complexes are described. The bibliography includes 172 references described. The bibliography includes 172 references. .

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Chemical Activation by Electron Transfer in Charge-Transfer Complexes. Formation and Reactions of Transient Ion Radical Pairs.

Cited by 83 publications

References 0 publications

Reductive activation of arenecarbonitriles for the reactions with some carbon-centered electrophiles: the reaction mechanisms and synthetic applications

Reductive activation of arenecarbonitriles for the reactions with some carbon-centered electrophiles: the reaction mechanisms and synthetic applications

Photophysical Evidence of Charge‐Transfer‐Complex Pairs in Mixed‐Linker 5‐Amino/5‐Nitroisophthalate CAU‐10

Nitrosonium complexes of organic compounds. Structure and reactivity

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