Diaryldichalcogenide radical cations

Mallow, Ole; Khanfar, Monther A.; Malischewski, Moritz; Finke, Pamela; Hesse, Malte; Lork, Enno; Augenstein, Timo; Breher, Frank; Harmer, Jeffrey; Vasilieva, Nadezhda V.; Zibarev, Andrey V.; Bogomyakov, A. S.; Seppelt, Konrad; Beckmann, Jens

doi:10.1039/c4sc02964j

Cited by 40 publications

(33 citation statements)

References 55 publications

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“…Here also two EtSe + Tf 2 N − equivalents have been carried over [reaction (4) in Scheme ]. This method is limited to alkyl selenium compounds, since diaryl diselenides Ar 2 Se 2 form radical cations rather than cyclic [Ar 4 Se 4 ] 2+ salts. The method according to reaction (1) allows complete use of all selenium atoms, whereas here one equivalent of Et 2 Se 2 remains unused as byproduct.…”

Section: Resultsmentioning

confidence: 99%

“…[4] Addition to an olefin shoulda lso be possible. Indeed [Et 4 Se 4 ] 2 + (Tf 2 N À ) 2 reacts with 1 to give seleniranium salt [Ad 2 SeEt] + Tf 2 N À (8)q uantitatively.H ere also two EtSe + Tf 2 N À equivalents have been carriedo ver [reaction (4) in Scheme 1].T his method is limitedt oa lkyl selenium compounds,s ince diaryl diselenides Ar 2 Se 2 form radical cations [32] rather than cyclic [Ar 4 Se 4 ] 2 + salts. The methoda ccording to reaction (1) allows complete use of all seleniuma toms, whereas here one equivalent of Et 2 Se 2 remains unused as byproduct.…”

Section: Resultsmentioning

confidence: 99%

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Seleniranium and Telluriranium Salts

Poleschner

Seppelt

2018

Chemistry A European J

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Seleniranium salts [Ad SeR] X (2-8), which are moderately stable at room temperature, were synthesized by addition of RSe X equivalents to the bulky olefin bis(adamantylidene) Ad=Ad (1), where R is aryl or alkyl and X is Tf N , B(C F ) , or SbCl . Unstable telluriranium salts [Ad TeR] X (9-12) were obtained by addition of RTe X equivalents to 1 (R=Ph, Et; X =Tf N , BF ). The compounds were characterized by NMR spectroscopy and quantum chemical calculations, and the Se compounds also by ESI mass spectrometry. Crystal structures were determined for seleniranium salts 2 and 7 and telluriranium salt 9.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Seleniranium and Telluriranium Salts

Poleschner

Seppelt

2018

Chemistry A European J

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“…[171] Concentrated solutions of SbF 5 can thus be considered as LSA. The high Lewis acidity and the oxidative strength coupled with the WCA properties of the formed anionsw ere used to access uniquec ationic Group 14, [143a, 172] Group 15, [173] Group 16, [174] Group 17, [175] Group 18, [176] or dblock metal compounds. [177] Various applications in organic synthesis have been developed as can be found in excellent reviews.…”

Section: Group 15mentioning

confidence: 99%

Lewis Superacids: Classifications, Candidates, and Applications

Greb

2018

Chemistry A European J

228

239

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Lewis acids play a major role in all areas of chemistry. For a long time, toxic, corrosive and oxidizing SbF was considered as the strongest Lewis acid known. Lately, species significantly exceeding the Lewis acidity of SbF have been realized and were termed Lewis superacids (LSA). Prospective new candidates emerge steadily, which not only outperform SbF by their strength, but also in terms of their accessibility and ease of handling. In principle, Lewis superacids allow us to combine the outstanding activity of Brønsted superacids with the excellent selectivity of a common Lewis acid. However, the broad application of Lewis superacids in synthesis is all but popular. The present review deals with strong Lewis acids. First, it critically discusses Lewis acidity scaling methods and suggests an extended definition for Lewis superacidity. It then summarizes the properties and applications of the strongest currently known Lewis acids, indexed by the fluoride ion affinity (FIA). The supporting information contains a comprehensive list of experimentally and theoretically derived FIA data as a guide for the choice of Lewis acidic reagents/catalyst. This contribution shall encourage the search for new Lewis superacids and promote their application in non-specialized laboratories.

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“…Most recently,Beckmann et al succeeded in the oxidation of dichalcogenides and the subsequent isolation of radical cations. [14] We are especially interested in radicals centered on Group 15 elements,o fw hich several examples are known to date (Scheme 1). By thermally induced processes of bond breaking or formation, the generation or recombination of Pcentered radicals was observed for several cases of diphosphanes and their heavier homologues (A).…”

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Cyclic Group 15 Radical Cations

et al. 2015

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Singlet cyclo-1,3-dipnicta-2,4-diazane-1,3-diyls of the type [E(μ-NTer)2 E] (2, E=P, As, Ter=2,6-dimesitylphenyl) can undergo a one-electron-oxidation utilizing silver salts of weakly coordinating anions such as [AgLn][B(C6F5)4 ] (L=donor solvents) to afford the novel cyclic radical cations, [E(μ-NTer)2E](+·) (3(+·)). When smaller and more basic anions were employed in the reaction, the anions were found to form covalent bonds to the radical centers yielding dipnictadiazanes, [FP(μ-NTer)2PF] (5) and [(CF3CO2)P(μ-NTer)2P(CF3CO2)] (6). A two-electron oxidation process, resulting in the formation of dications of the type [E(μ-NTer)2E](2+), could not be observed. Computational and EPR data revealed that the spin density is almost completely localized at the two heavier pnictogen centers E of the former 1,3-dipnictadiazane-1,3-diyls. The bonding situation in the radical cations features a rare example of a transannular one-electron π bond without having a σ bond.

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Diaryldichalcogenide radical cations

Abstract: One-electron oxidation of diaryldichalcogenides is the key to the preparation of the corresponding radical cations.

Cited by 40 publications

References 55 publications

Seleniranium and Telluriranium Salts

Seleniranium and Telluriranium Salts

Lewis Superacids: Classifications, Candidates, and Applications

Cyclic Group 15 Radical Cations

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