Selenirenium and Tellurirenium Ions

Poleschner, Helmut; Seppelt, Konrad

doi:10.1002/anie.200801691

Cited by 57 publications

(82 citation statements)

References 37 publications

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“…Single crystal X-ray analysis showed the formation of a salt complex (5) consisting of a cationic diboraphenyltellurirenium fragment and a spatially separated anionic phenyltelluride. An equivalent reaction utilizing the more electron-poor di-[4-fluorophenyl]-ditellurium showed identical reactivity, allowing the isolation and characterization of 6.Similar organic three-membered tellurirenium ions (7, Eq.3) have been previously demonstrated by Poleschner and Seppelt; [21] however, the reaction pathway to these products is notably different. In the organic reaction, an [ArTe] + fragment is generated by oxidation of a ditelluride and subsequently reacted with an alkyne (Eq.…”

supporting

confidence: 64%

Highly Strained Heterocycles Constructed from Boron–Boron Multiple Bonds and Heavy Chalcogens

et al. 2016

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Abstract:The reactions of a diborene with elemental selenium or tellurium are shown to afford a diboraselenirane or diboratellurirane, respectively. These reactions are reminiscent of the sequestration of sub-valent oxygen and nitrogen in the formation of oxiranes and aziridines; however, such reactivity is not known between alkenes and the heavy chalcogens. While carbon is too electronegative to affect the reduction of elements of lower relative electronegativity, the highly reducing nature of the B=B double bond enables reactions with Se 0 and Te 0 . The capacity of multiple bonds between boron to donate electron density is highlighted in reactions where diborynes behave as nucleophiles, attacking one of the two Te atoms of diaryltellurides, forming salts consisting of diboratellurenium cations and aryltelluride anions.The energy stored in small, highly strained cyclic molecules has made them an integral part of modern synthetic chemistry. Since this "strain energy" increases with decreasing ring size, it is greatest for three-membered rings, and when these rings are heterocyclic the charge-asymmetry induced in the molecule provides sites ready for reaction. Accordingly, an enormous amount of research has gone into both the synthetic paths to, and reactions of, members of this class of compounds, most prominently oxiranes (C2O rings) and aziridines (C2N rings). The most common route to these materials is the oxidation of olefins using, in the case of oxirane formation, subvalent oxygen species such as O2, peroxides, peroxyacids, and ozone, or with reagents that impart a degree of electron deficiency to an oxygen atom, such as chlorite or iodosylbenzene. [1] Aziridination of olefins is most frequently accomplished through the in situ generation of nitrenes from azides or other electron deficient nitrogen sources such as iodinanes, hydroxylamines, and hydrazines. [1a,2] These alkene-oxidations are made possible by the relatively high electronegativity of oxygen and nitrogen, (χPauling = 3.44 and 3.04, respectively), relative to carbon (χPauling = 2.55).Thiiranes (C2S rings) are comparatively less common, and though examples of the direct addition of elemental sulfur to alkenyl double bonds are not unknown, [3] their syntheses are more likely than their first row neighbors to involve non-redox routes. [4] The similar electronegativities of carbon and sulfur (χPauling = 2.58) decreases the thermodynamic driving force for alkene oxidation, further exemplified by the noted willingness of thiiranes to thermally extrude atomic sulfur [5] and by their utility as sulfur atom transfer reagents. [6] Three-membered heterocycles featuring heavier chalcogens (Se and Te) are even less prevalent. Though seleniranes have been proposed as reactive intermediates in a handful of transformations, [7] the isolated examples of these compounds are few and none have been crystallographically verified. [8] To date, there are no known examples of telluriranes. The heavy chalcogens have roughly equal (χSe = 2.55) or smaller (χTe = 2.10...

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supporting

confidence: 64%

Highly Strained Heterocycles Constructed from Boron–Boron Multiple Bonds and Heavy Chalcogens

et al. 2016

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“…[19] Scheme 6. a) H 2 O 2 (30 %), CH 3 CN, room temp. All newly synthesized compounds were fully characterized by 1 H, 13 C, 77 Se NMR spectroscopy, mass spectrometry techniques and elemental analysis. Some of the compounds were characterized by single-crystal X-ray diffraction studies.…”

Section: Resultsmentioning

confidence: 99%

“…[13] Both are stable enough for isolation under argon, however, decompose within a week to a significant extent. Very recently, transfer of in situ generated seleniranium group 7 from one olefin to another, has been observed by Denmark et al using NMR spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Stable Selenenium Cations: Unusual Reactivity and Excellent Glutathione Peroxidase‐Like Activity

Singh

Butcher

2010

Eur J Inorg Chem

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The syntheses of the three selenenium cations 17–19 derived from N‐[n‐butyl‐(3‐nitrobenzylimino)]phenyl selenide (14) are described. Precursor 14 was synthesized by treating N‐(2‐bromo‐3‐nitrobenzylimino)benzene (12) with in situ generated nBuSeNa. The selenenium cation 17 with chloride as counteranion was isolated when 14 was treated with sulfuryl chloride (SO2Cl2) in the presence of triethylamine (Et3N). The selenenium cations with bromide (18) and tribromide (19) as counteranions, were synthesized by treating 14 with Br2 in the presence of Et3N. Reaction of 19 with thiophenol afforded two unexpected products: the cyclic diselenide 20 and the bicyclic selenide 21. Oxidation of 18 with hydrogen peroxide afforded the ebselen derivative, 2‐(4‐bromophenyl)‐7‐nitro‐1,2‐benzisoselenazol(2H)‐3‐one Se‐oxide (22). The presence of nonbonding Se···O/Se–N intramolecular interactions in 18 and 19 have been confirmed by single‐crystal X‐ray studies. Glutathione peroxidase‐like antioxidant activities of 17–19 and related compounds have been determined by the coupled reductase assay. It is proved that the high GPx‐like activities of cations involve the formation of corresponding intermediate selenoxide in the catalytic cycle. The isolated selenoxide 22 shows the highest GPx‐like activity among the series of compounds. The compounds have been further investigated by density functional theory calculations at the B3LYP level of theory using the 6‐31+G(d) basis set to identify nonbonding Se···O/N interactions. The second perturbation energy was obtained through natural bond orbital (NBO) analysis and NBO charges were calculated to ascertain the positive charge at the selenium atom. Nucleus‐independent chemical shifts (NICS) calculations have also been carried out.

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“…The vibration frequencies of the C−C triple bond of 4-octyne, the C-C double bond of 1b, and the C-C double bond of cis-4-octene show linear correlation with the C−C bond lengths obtained by DFT calculaFons (Figure 3b), which is similar to the tendency of seleniranium ions reported in the literature. 34 The higher frequency and the shorter bond length of 1b than those of cis-4-octene is not because of the bond order of the C−C The thermal stability of thiirenium ion 1a was investigated. 35 After a solution of 1a was kept at the second temperature for 30 min, the resulting solution was recooled to −78 °C.…”

Section: 7mentioning

confidence: 99%

Generation and reactions of thiirenium ions by the Cation Pool method

Shimizu¹,

Horiuchi²,

Hayashi³

et al. 2017

Arkivoc

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Thiirenium ions generated and accumulated by low-temperature electrochemical oxidation of disulfides in the presence of alkynes were successfully observed by low-temperature NMR, Raman, and mass spectroscopies and were found to be stable at temperatures below −40 °C. The thiirenium ions showed ambident reactivity toward subsequently added nucleophiles to give either disubstituted alkenes or alkynes depending on the nature of the nucleophiles.

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Selenirenium and Tellurirenium Ions

Cited by 57 publications

References 37 publications

Highly Strained Heterocycles Constructed from Boron–Boron Multiple Bonds and Heavy Chalcogens

Highly Strained Heterocycles Constructed from Boron–Boron Multiple Bonds and Heavy Chalcogens

Stable Selenenium Cations: Unusual Reactivity and Excellent Glutathione Peroxidase‐Like Activity

Generation and reactions of thiirenium ions by the Cation Pool method

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