Electron Transfer in Organic Reactions

Patz, Matthias; Fukuzumi, Shunichi

doi:10.1002/(sici)1099-1395(199703)10:3<129::aid-poc884>3.0.co;2-4

Cited by 30 publications

(11 citation statements)

References 98 publications

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“…Quinones are well known to be electron acceptors with the formation of chargetransfer complexes. 43,44 Control experiments revealed that no reaction was observed on treatment of Mes 3 P with pO 2 C 6 Cl 4 in C 6 H 5 Cl. Moreover, the UV-visible ).…”

Section: Resultsmentioning

confidence: 99%

A Radical Mechanism for Frustrated Lewis Pair Reactivity

Liu

Cao

Shao

et al. 2017

Chem

155

128

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The frustrated Lewis pairs (FLPs) derived from tBu 3 P and E(C 6 F 5 ) 3 (E = B, Al) react with pO 2 C 6 Cl 4 and Ph 3 SnH to give [tBu 3 POC 6 Cl 4 OE(C 6 F 5 ) 3 ] (E = B 1, Al 2), [tBu 3 PSnPh 3 ][HB(C 6 F 5 ) 3 ] 3, and [tBu 3 PSnPh 3 ][(m-H)(Al(C 6 F 5 ) 3 ) 2 ] 4. These products form via the accepted two-electron process involving a transient ''encounter complex.'' In contrast, the corresponding reactions of Mes 3 P and E(C 6 F 5 ) 3 (E = B, Al) with pO 2 C 6 Cl 4 give [(Mes 3 POC 6 Cl 4 OE(C 6 F 5 ) 3 ] (E = B 8, Al 9); however, the identification of the intermediates [Mes 3 P$] 2 [(C 6 F 5 ) 3 EOC 6 Cl 4 OE(C 6 F 5 ) 3 ] (E = B 5, Al 6) supports a mechanism that proceeds via a single-electron transfer process. This is further supported by the reactions of Mes 3 P and E(C 6 F 5 ) 3 (E = B, Al) with Ph 3 SnH, which yielded [Mes 3 PH] [HB(C 6 F 5 ) 3 ] 10 and [Mes 3 PH][(m-H)(Al(C 6 F 5 ) 3 ) 2 ] 11, respectively, with the concurrent formation of Ph 3 SnSnPh 3 .

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Section: Resultsmentioning

confidence: 99%

A Radical Mechanism for Frustrated Lewis Pair Reactivity

Liu

Cao

Shao

et al. 2017

Chem

155

128

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“…One is an electron-transfer mechanism where C 60 2- acts as an electron donor and the other is an S N 2 mechanism where C 60 2- acts as a nucleophile. The electron transfer vs nucleophilic process alternative has been one of the most central propositions in reaction mechanism, − but it has never been examined in the case of C 60 . The heterogeneous electron-transfer reactions of fullerenes with electrodes 1 as well as their photoinduced electron-transfer reactions have been studied extensively, , but few studies have been carried out with respect to the homogeneous electron-transfer reactions of C 60 .…”

Section: Introductionmentioning

confidence: 99%

Formation of C₆₀Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and S_N2 Reactions

et al. 1998

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The formation of organofullerenes of the type R2C60 and R(R‘)C60 from C60 2- and alkyl halides (RX or R‘X) in benzonitrile was mechanistically investigated for 15 different alkyl halides which vary in electrophilicity and electron acceptor ability. The first step in the reaction leads to RC60 - via an electron-transfer mechanism, followed by formation of R2C60 or R(R‘)C60 via an SN2 mechanism. Evidence of the mechanism comes from comparison of rate constants for the stepwise addition of two R groups to C60 2- with rate constants for the genuine electron transfer and SN2 reactions. The formation of t-BuC60 - and PhCH2C60 - after the first R group addition was confirmed by electrospray ionization mass spectroscopy. The t-BuC60 - derivative will not react further with excess t-BuI, but this is not the case for the less sterically hindered PhCH2Br, which adds to t-BuC60 - in benzonitrile to give t-Bu(PhCH2)C60. A protonation of t-BuC60 - with trifluoroacetic acid can also occur to give 1,4-t-Bu(H)C60, which rearranges rapidly to yield 1,2-t-Bu(H)C60. Rate constants for the second alkylation of t-BuC60 - with a variety of different alkyl halides are compared with values of genuine SN2 reactions and indicate that the second step in the fullerene alkylation reaction proceeds via an SN2 mechanism. The rate constants of electron transfer from C60 2- to RX span a range of 105, but are insensitive to the steric effect of the alkyl group, i.e., they depend only on the electron-acceptor ability of RX. In contrast, the SN2 rate constants of t-BuC60 - with RX are highly susceptible to the steric effect of the alkyl group and no reaction at all takes place between t-BuC60 - and t-BuI. Thus, the first addition of one sterically hindered alkyl group to C60 2- occurs via electron transfer and cannot be followed by further addition of a second sterically hindered group (via an SN2 reaction). This is not the case for less sterically hindered alkyl groups such as benzyl bromide which can add via an SN2 reaction to yield C60 adducts with two different alkyl groups.

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“…However, an intramolecular electron-transfer reaction of a donor-acceptor-linked system can also be started thermally by addition of a metal ion [22]. Addition of scandium triflate [Sc(OTf) 3 ] to an MeCN solution of ferrocene-naphthoquinone dyad (Fc-NQ) resulted in formation of the Fc + -NQ ؒ-/Sc 3+ complex as indicated by appearance of the absorption band due to the Fc + moiety at 860 nm together with the absorption band at λ max = 420 nm owing to the NQ ؒ-/Sc 3+ moiety (Scheme 5).…”

Section: Catalytic Control Of Intramolecular Electron Transfermentioning

confidence: 99%

“…1 and 5 [28]. Hydride transfer from AcrH 2 to 3,6-diphenyl-1,2,4,5-tetrazine (Ph 2 Tz), which contains N=N double bond, occurs efficiently in the presence of Sc(OTf) 3 via Sc 3+ -promoted electron transfer in MeCN at 298 K, whereas no reaction occurs in the absence of Sc 3+ [29].…”

Section: Catalytic Control Of Electron Transfer and The Subsequent Stepmentioning

confidence: 99%

“…If the electron transfer is endergonic, no net electron transfer would occur because of facile back electron transfer (BET) to regenerate the reactant pair. However, numerous chemical reactions, previously formulated by "movements of electron pairs", are now understood as processes in which an initial electron transfer from a nucleophile (reductant) to an electrophile (oxidant) produces a radical ion pair, which leads to the final products via the follow-up steps involving cleavage and formation of chemical bonds [1][2][3][4][5][6]. The follow-up steps are usually sufficiently rapid to render the initial electron transfer the rate-determining step in an overall irreversible transformation.…”

Section: Introductionmentioning

confidence: 99%

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Catalytic control of electron-transfer processes

Fukuzumi

2003

Pure and Applied Chemistry

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Catalytic control of electron-transfer processes is described for a number of photoinduced and thermal electron-transfer reactions, including back electron transfer in the charge-separated state of artificial photosynthetic compounds. The intermolecular and intramolecular electron-transfer processes are accelerated by complexation of radical anions, produced in the electron transfer, with metal ions that act as Lewis acids. Quantitative measures to determine the Lewis acidity of a variety of metal ions are given in relation with the promoting effects of metal ions in the electron-transfer reactions. The mechanistic viability of metal ion catalysis in electron-transfer reactions is demonstrated by a variety of examples of both thermal and photochemical reactions that involve metal ion-promoted electron-transfer processes as the rate-determining steps, which are made possible to proceed by complexation of radical anions with metal ions.

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Electron Transfer in Organic Reactions

Cited by 30 publications

References 98 publications

A Radical Mechanism for Frustrated Lewis Pair Reactivity

A Radical Mechanism for Frustrated Lewis Pair Reactivity

Formation of C₆₀Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and S_N2 Reactions

Catalytic control of electron-transfer processes

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Electron Transfer in Organic Reactions

Cited by 30 publications

References 98 publications

A Radical Mechanism for Frustrated Lewis Pair Reactivity

A Radical Mechanism for Frustrated Lewis Pair Reactivity

Formation of C60Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and SN2 Reactions

Catalytic control of electron-transfer processes

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Formation of C₆₀Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and S_N2 Reactions