Radical Ions, 46. One‐Electron Oxidation of 1,8‐Chalcogen‐Bridged Naphthalenes

Bock, Hans; Brähler, Georg; Dauplaise, David; Meinwald, Jerrold

doi:10.1002/cber.19811140724

Cited by 46 publications

(19 citation statements)

References 23 publications

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“…The first ionization is a band with a vertical ionization energy of 8.16 eV. For comparison, the first ionization of dimethyl disulfide is 8.96 eV, while the first ionization of the peri-chalcogen-bridged naphthalene naphtho[1,8- c,d ]-1,2-dithiole is located at 7.14 eV . For 1,2-dithiin, more structure is observed in these spectra than in those previously studied …”

Section: Photoelectron Resultsmentioning

confidence: 69%

Gas-Phase Photoelectron Spectroscopic and Theoretical Studies of 1,2-Dichalcogenins: Ionization Energies, Orbital Assignments, and an Explanation of Their Color

et al. 2000

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Gas-phase photoelectron spectroscopy and theoretical calculations are used to study the electronic structure of 1,2-dichalcogenins. Photoelectron spectra are reported for 1,2-dithiin, 3,6-dimethyl-1,2-dithiin, 3,6-diisopropyl-1,2-dithiin, 3,6-di-tert-butyl-1,2-dithiin, 2-selenathiin, 1,2-diselenin, 3,6-dimethyl-1,2-diselenin, and 3,6-di-tert-butyl-1,2-diselenin and are assigned on the basis of (a) trends in ionization cross sections as the ionization photon energy is varied and (b) shifts of the ionizations as chemical substitutions are made. The calculated properties of 1,2-dithiin and 3,6-dimethyl-1,2-dithiin are compared to experimental results. The first four filled frontier valence orbitals are associated with orbitals that can be described as being primarily carbon π and chalcogen lone pair in character. Comparison of spectra collected with He I, He II, and Ne I ionization sources for each compound indicate that there is a large degree of mixing of chalcogen and carbon character through most of the valence orbitals. The highest occupied molecular orbital of the selenium-containing compounds has more chalcogen character than the highest occupied molecular orbital of the 1,2-dithiins. The photoelectron spectra of 1,2-dithiin and 1,2-diselenin contain a sharp ionization that corresponds to removal of an electron from an orbital that is predominantly chalcogen−chalcogen σ bonding in character. The narrow ionization profile indicates fairly weak chalcogen−chalcogen σ bonding in this orbital, which would result in a corresponding weakly antibonding chalcogen−chalcogen σ* orbital. Computational results show that an orbital that is primarily S−S σ* in character is the lowest unoccupied molecular orbital of 1,2-dithiin, and electronic transition calculations show a low-energy HOMO-to-LUMO transition that can be described as a π/lone pair-to-σ* transition that explains the unusual color of 1,2-dichalcogenins.

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Section: Photoelectron Resultsmentioning

confidence: 69%

Gas-Phase Photoelectron Spectroscopic and Theoretical Studies of 1,2-Dichalcogenins: Ionization Energies, Orbital Assignments, and an Explanation of Their Color

et al. 2000

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“…Furthermore, an EPR spectrum of 4b was recorded in the presence of TFA, as shown in Figure . In related work, previous groups have reported EPR spectra derived from disulfide 1a in the course of their investigations of its charge-transfer complexes, while Bock, Meinwald et al recorded EPR spectra of the radical cations produced when disulfide 1a and diselenide 1b underwent oxidation by the Lewis acid aluminum trichloride. The present process is also related to the broader category of proton-coupled electron transfer (PCET) reactions.…”

Section: Resultsmentioning

confidence: 99%

Acid-Catalyzed Electron Transfer Processes in Naphthalene peri-Dichalcogenides

et al. 2018

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1,8-Naphthalene peri-dichalcogenides undergo protonation by Bronsted acids to produce electrophilic cations. Single electron transfer (SET) from the remaining unprotonated electron-rich peri-dichalcogenide to the cation then generates a radical cation and a radical. Thus, the formation of radical species results in severe peak broadening and coalescence of NMR signals when trifluoroacetic acid or other strong acids are added to the peri-dichalcogenide, and the process can be reversed by treatment with base. Further evidence for the formation of radicals stems from EPR, radical quencing with sodium dithionite, and computational experiments. The electron transfer is enhanced by the presence of 2,7-dialkoxy substituents that further increase the electron-donating ability of the dichalcogenides. This is an unusual example of a proton-coupled electron transfer process where an electron-rich molecule reacts with its own conjugate acid via a single electron transfer process.

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“…This change can be attributed to the formation of complexes and the deviation of electron cloud around selenium atom. The electron donors, the quinones, decrease the n-π* and π-π* conjugate effect in chromophoric group and increase the energy needed for the n-π* and π-π* transitions [17][18][19][20], resulting shifting in the absorption band toward shorter wave length.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Study of Charge-transfer Complexes for 5,6-dimethyl-2,1,3-benzoselenadiazole

2009

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The synthesis of new solid charge-transfer (CT) complexes using 5,6-dimethyl-2,1,3-benzoselnadiazoles as donors with 1,4-naphthaquinone; 1,8-dihydroxyanthraquinone, 2-hydroxy-1,4-naphthaquinone and 2,3-dichloro-4,5-dicyano-p-benzoquinone (DDQ) as acceptor are reported. These complexes are characterized by elemental analysis, IR, UV-V, and 1 HNMR spectroscopic data. Solid conductivity for 1, 2 and 3 compounds revel that they are not conductors. The calculated HOMO is largely localized on the selnadiazoles fragment, while the calculated LUMO of the studied molecule is seen to be substantially localized along the C-C axis of the conjugated system.

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Radical Ions, 46. One‐Electron Oxidation of 1,8‐Chalcogen‐Bridged Naphthalenes

Cited by 46 publications

References 23 publications

Gas-Phase Photoelectron Spectroscopic and Theoretical Studies of 1,2-Dichalcogenins: Ionization Energies, Orbital Assignments, and an Explanation of Their Color

Gas-Phase Photoelectron Spectroscopic and Theoretical Studies of 1,2-Dichalcogenins: Ionization Energies, Orbital Assignments, and an Explanation of Their Color

Acid-Catalyzed Electron Transfer Processes in Naphthalene peri-Dichalcogenides

Synthesis and Study of Charge-transfer Complexes for 5,6-dimethyl-2,1,3-benzoselenadiazole

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