Three-electron-bonded sulfur-centered radical cations and possible ylide formation during the oxidation of various 1,3-dithiacylopentanes

Bonifacic, M.; Asmus, K.‐D.

doi:10.1021/jo00358a011

Cited by 27 publications

(11 citation statements)

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“…Almost all significant deviations lie on one side of the 1:1l ine. The ab initio bond energies are highert han those predicted by Equation (6). These deviations are, however,a ll explained by additional bonding interactions, such as the hydrogen bonds in HF···OH 2 + C,t he three-electron bonded complex that deviates most from Equation (6) and strong hyperconjugation in CH 3 ···BeH + C,t he one-electron bonded speciest hat deviates most from Equation (6).…”

Section: Resultsmentioning

confidence: 86%

“…Even thougho dd-electron bonds are important in radicalr eactivity,e lectrochemistry and catalysis, it is remarkable how unfamiliar these principles have remained. Above all, much of the late Dieter Asmus' seminalw ork [4][5][6][7][8][9][10][11][12][13] has apparently been forgotten, [72] but also the pioneering experimental studies of Meot-Ner, [19] Pauling [3] and Hiberty's [29] rationalization of oddelectron bond energiesi nt erms of valence-bond theory and Bock [34] and Nelsen's [35] fundamental studies on three-electron p-bonds are apparently no longerp resenti no ur general picture of bondingt heory.T his short review attempts to remind us of these classical examples of physicalo rganic chemistry, which taken on an even more importantr ole as the importance of radicals and radical ions is increasingly recognized in both biology and photovoltaics and whose importance in transition-metal chemistry has recently been reviewed. [73] Computational Section All calculations used the Gaussian 09 series of programs.…”

Section: Discussionmentioning

confidence: 99%

“…Theoretical interest in odd-electron bonding was strengthened by Asmus' observation of intramolecular SÀS three-electron bonds in solution. [4] This was followed by similar studies on S-halogen three-electron bonds [5][6][7][8][9] and acyclic SÀS three-electron bonded radical cations. [10,11] Furthert hree-electron bonds of sulfur with nitrogen, oxygen [12] and phosphorus [13] and between two nitrogen [14,15] and two iodine [16] cen-ters [17] werea lso reported.…”

Section: Introductionmentioning

confidence: 96%

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Odd‐Electron Bonds

Clark

2017

ChemPhysChem

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Section: Resultsmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Odd‐Electron Bonds

Clark

2017

ChemPhysChem

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“…(>S);' + Br-->S.'.Br + : S (9) (>s);+ + I -->S.'.I + >s (10) (9) and (10) are 2.1 x lo9 and 7.8 x lo9 dm3 mol-' s-I, respectively.…”

Section: Methodsmentioning

confidence: 99%

Pulse radiolysis investigations on electron-transfer reactions in aqueous solutions of substituted alkyl sulfides

Mohan¹,

Mittal

1992

J. Chem. Soc., Perkin Trans. 2

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The transient optical absorption band (A,,, = 345 nm, t+ = 4.0 ps, E = 2.6 x lo3 dm3 mo1-I ern-') formed on pulse radiolysis of N,O-saturated dilute neutral aqueous solutions of dimethyl 3,3'thiodipropionate (DTDP) is assigned to an 'OH-adduct. The rate constant for the reaction of 'OH radicals has been determined to be 1.4 x IO'O dm3 mol-' s-'. At higher solute concentrations the 'OH-adduct is converted to sulfur-centred dimer radical cations (A,,, = 510 nm, E = 4.9 x lo3 dm3 mol-I cm-', t+ = 14.0 ps). In acidic solutions, only dimer radical cations are formed. In neutral aqueous solutions of 3,3'-thiodipropanol (TDP) *OH radicals are able to bring about one-electron oxidation, forming intramolecular radical cations with p-orbital overlap between the oxidized sulfur and oxygen (Amax = 420 nm, t+ = 17 ps, E = 2.6 x lo3 dm3 mol-' cm-I). in acidic solutions, sulfur-centred dimer radical cations are formed (Amax = 51 0 nm, t+ = 12 ps, E = 6.3 x 1 O3 dm3 mol-' cm-'). In the presence of halide ions, the oxidized sulfur in DTDP and TDP stabilizes by formation of an >S.'.X type species. * 10%. Results and Discussion HydroxylRadical Reactions with DTDP.-Fig. l(a) shows the transient optical absorption spectrum obtained on pulse radiolysis of an N,O-saturated aqueous solution of DTDP (2.3 x lop4 mol dmP3, pH = 6.0, dose = 1.4 x 1017 eV cmP3 per pulse). It exhibits an absorption band with A, , , Paper 1/02825A

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“…Some examples of these species are RSSR •− , RSSR •+ , and R2SX with X=halide. [56][57][58][59][60]] RSSR •− constitutes and interesting case since it is in equilibrium with the corresponding thiyl radical. However, while RSSR •− is a reductant that may react with O 2 yielding O 2…”

Section: Free Radicals Chemical Features and Reactivitymentioning

confidence: 99%

Free Radicals Induced Oxidative Stress at a Molecular Level: The Current Status, Challenges and Perspectives of Computational Chemistry Based Protocols

Galano

2017

J. Mex. Chem. Soc.

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Oxidative stress is frequently caused by an excess of free radicals and has been associated with a wide variety of health disor-ders. Therefore, finding strategies for scavenging free radicals has be-come an active area of research. This review summarizes, from a physicochemical perspective, relevant strategies to fight oxidative stress via antioxidants, including prevention, deactivation of oxidants, and repair of damaged targets. Different reaction mechanisms in-volved in the chemical protection exerted by antioxidants are dis-cussed, as well as their relative importance depending on several aspects. Some of them are the polarity of the environment, the pH of aqueous phase, and the chemical nature of the reacting radicals. Data that can currently be obtained from computational, quantum, chemis-try, protocols are detailed and their reliability is analyzed. Viable crite-ria to identify optimal antioxidants using such protocols are provided. Current challenges and future directions in this area of research are discussed. A large set of antioxidants are compared and their trends in activity, based on kinetic data, is provided.

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Three-electron-bonded sulfur-centered radical cations and possible ylide formation during the oxidation of various 1,3-dithiacylopentanes

Cited by 27 publications

References 1 publication

Odd‐Electron Bonds

Odd‐Electron Bonds

Pulse radiolysis investigations on electron-transfer reactions in aqueous solutions of substituted alkyl sulfides

Free Radicals Induced Oxidative Stress at a Molecular Level: The Current Status, Challenges and Perspectives of Computational Chemistry Based Protocols

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