Substituent effects in diphenylmercury radical cations: a very clear distinction between σ- and π-states

Rhodes, Christopher J.; Ağirbaş, Hıkmet; Shine, Henry J.; Hoque, Anwarul; Venkatachalam, T. K.

doi:10.1039/p29930002129

Cited by 6 publications

(3 citation statements)

References 14 publications

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“…Radical cations of saturated hydrocarbons (and of many other compounds as well) may be generated by exposure of these compounds to ionizing radiation in a trichlorofluoromethane matrix at cryogenic temperatures . As trichlorofluoromethane is the dominant component in the binary CCl 3 F/decane systems at moderate decane concentrations, absorption of ionizing radiation that is nonselective mainly occurs by that compound, resulting in its excitation and ionization…”

Section: Discussionmentioning

confidence: 99%

Carbon−Hydrogen vs Carbon−Carbon Protonation in the Proton Transfer from Alkane Radical Cations to Alkane Molecules. A Study in γ-Irradiated CCl₃F/Decane at 77 K

Demeyer

Ceulemans

2000

J. Phys. Chem. A

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A study is made of the formation of the isomeric chlorodecanes, and a search is made for shorter-chain 1-chloroalkanes (5 ≤ n C ≤ 9) formed in CCl3F/decane by γ-irradiation at 77 K and subsequent melting at various concentrations of decane. In such systems, proton transfer from decane radical cations to decane molecules resulting in the formation of pentacoordinated decane carbonium ions (protonated decanes) is quite extensive at high decane concentration, as is evidenced by the fact that under such conditions (i) the ESR spectrum of the irradiated system at 77 K largely consists of decyl radicals and (ii) the contribution of 1-chlorodecane to chlorodecane formation after melting the sample is quite small. The contribution of decyl radicals to the paramagnetic absorption sharply increases and the contribution of 1-chlorodecane to chlorodecane formation strongly decreases with increasing concentration of decane. It is observed that at high decane concentration formation of secondary chlorodecanes is extensive, with 2-chlorodecane being by far the most prominent, but that shorter-chain 1-chloroalkanes are essentially absent. From the results obtained it is concluded that proton transfer from decane radical cations to decane molecules in γ-irradiated CCl3F/decane results in the selective formation of secondary C−H protonated decanes with a clear preference for the penultimate position and that formation of C−C and primary C−H protonated decanes by this process is negligible.

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Section: Discussionmentioning

confidence: 99%

Carbon−Hydrogen vs Carbon−Carbon Protonation in the Proton Transfer from Alkane Radical Cations to Alkane Molecules. A Study in γ-Irradiated CCl₃F/Decane at 77 K

Demeyer

Ceulemans

2000

J. Phys. Chem. A

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“…Accordingly, photo‐induced Z ↔ E photoisomerization causes activation of functionalities in systems containing bridged azo moieties as photoresponsive units. Moreover, it has been shown that azo compounds with a strained geometry and those with aliphatic substituents form rather persistent radical ions upon one‐electron reduction (or oxidation) [14,21–32] . Whereas it has been shown that electron transfer causes efficient and rapid Z ↔ E conversion in non‐bridged azo compounds with advantageous reduction potentials, [26,33–40] the changes in molecular configuration upon one‐electron reduction in bridged azobenzene derivatives have not been addressed.…”

Section: Introductionmentioning

confidence: 99%

To Isomerize or not to Isomerize? E/Z Isomers of Cyclic Azobenzene Derivatives and Their Reactivity Upon One‐Electron Reduction

Glotz

Knaipp

Maier

et al. 2023

Chemistry A European J

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Azo compounds are efficient electron acceptors. Upon one‐electron reduction they generally isomerize forming the thermodynamically most stable radical anion. Herein we show that the size of the central ring in 1,2‐diazocines and diazonines has a ruling influence on the configuration of the one‐electron reduced species. Markedly, diazonines, which bear a central nine membered heterocycle, show light‐induced E/Z isomerization, but retain the configuration of the diazene N=N moiety upon one‐electron reduction. Accordingly, E/Z isomerization is not induced by reduction.

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“…Trichlorofluoromethane containing various solutes has been used extensively for the formation and trapping of solute radical cations by γ-irradiation at cryogenic temperatures, allowing the study of these cationic intermediates by EPR spectroscopy . In combination with theoretical calculations, such studies have yielded detailed information on the electronic structure of the radical cations concerned.…”

Section: Introductionmentioning

confidence: 99%

Nature of the Undecyl Radicals Formed by γ-Irradiation of CCl₃F/Undecane at 77 K. Evidence on the Physical State of Alkane Aggregates in CCl₃F

2002

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A study is made by EPR spectroscopy of the nature of the undecyl radicals formed by γ-irradiation of CCl 3 F/ undecane at 77 K. It is observed that at low undecane concentration (e.g., 1 mol %) primary undecyl radicals are very prominent. With increasing undecane concentration, the (relative) contribution of primary undecyl radicals to undecyl formation decreases as a result of intermolecular radical site transfer and at 4-6 mol % undecane in CCl 3 F primary undecyl radicals are essentially absent. With further increases in undecane concentration primary undecyl radicals regain some of their prominence in the EPR spectra but only to a limited extent, contributing an estimated 5-10% to the total undecyl radical concentration at for instance 20 mol % undecane. In view of the documented dependence of intermolecular radical site transfer on the molecular alignment in n-alkane crystals (Iwasaki, M.; Toriyama, K.; Fukaya, M.; Muto, H.; Nunome, K. J. Phys. Chem. 1985, 89, 5278), the results allow us to conclude that (quite unlike neat undecane) undecane aggregates in CCl 3 F do not assume the orthorhombic crystalline structure at cryogenic temperatures, with exception of some aggregates at the highest concentrations investigated. Taking into account general crystallization characteristics of n-alkanes, it can be deduced that as a rule undecane aggregates in CCl 3 F are in all likelihood amorphous and this conclusion can reasonably be extended to all n-alkanes with n C e 11 for concentrations below 20 mol %. Thermodynamic as well as kinetic factors are cited as causes for this general absence of crystallization.

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Substituent effects in diphenylmercury radical cations: a very clear distinction between σ- and π-states

Cited by 6 publications

References 14 publications

Carbon−Hydrogen vs Carbon−Carbon Protonation in the Proton Transfer from Alkane Radical Cations to Alkane Molecules. A Study in γ-Irradiated CCl₃F/Decane at 77 K

Carbon−Hydrogen vs Carbon−Carbon Protonation in the Proton Transfer from Alkane Radical Cations to Alkane Molecules. A Study in γ-Irradiated CCl₃F/Decane at 77 K

To Isomerize or not to Isomerize? E/Z Isomers of Cyclic Azobenzene Derivatives and Their Reactivity Upon One‐Electron Reduction

Nature of the Undecyl Radicals Formed by γ-Irradiation of CCl₃F/Undecane at 77 K. Evidence on the Physical State of Alkane Aggregates in CCl₃F

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Substituent effects in diphenylmercury radical cations: a very clear distinction between σ- and π-states

Cited by 6 publications

References 14 publications

Carbon−Hydrogen vs Carbon−Carbon Protonation in the Proton Transfer from Alkane Radical Cations to Alkane Molecules. A Study in γ-Irradiated CCl3F/Decane at 77 K

Carbon−Hydrogen vs Carbon−Carbon Protonation in the Proton Transfer from Alkane Radical Cations to Alkane Molecules. A Study in γ-Irradiated CCl3F/Decane at 77 K

To Isomerize or not to Isomerize? E/Z Isomers of Cyclic Azobenzene Derivatives and Their Reactivity Upon One‐Electron Reduction

Nature of the Undecyl Radicals Formed by γ-Irradiation of CCl3F/Undecane at 77 K. Evidence on the Physical State of Alkane Aggregates in CCl3F

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Carbon−Hydrogen vs Carbon−Carbon Protonation in the Proton Transfer from Alkane Radical Cations to Alkane Molecules. A Study in γ-Irradiated CCl₃F/Decane at 77 K

Carbon−Hydrogen vs Carbon−Carbon Protonation in the Proton Transfer from Alkane Radical Cations to Alkane Molecules. A Study in γ-Irradiated CCl₃F/Decane at 77 K

Nature of the Undecyl Radicals Formed by γ-Irradiation of CCl₃F/Undecane at 77 K. Evidence on the Physical State of Alkane Aggregates in CCl₃F