- An Electron Spin Resonance Study of the Radical Cations of Pyrroles, Furans, and Thiophenes in Liquid Solution
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Photolysis of alkylpyrroles in trifluoroacetic acid containing mercury(II) trifluoroacetate, alkylfurans in trifluoroacetic acid, or alkylthiophenes in sulphuric acid, induces oxidation to the corresponding radical cations.The e.s.r. spectra show that the electronic configuration is similar in all three species, the unpaired electron occupying the φA MO in which the heteroatom lies in a nodal plane.Photolysis of 2,6-dimethyl- and 2,6-diethyl-thiophene in trifluoroacetic acid containing mercury(II) trifluoroacetate, on the other hand, gave rise to spectra with a high g value (2.0062), showing hyperfine coupling to two non-equivalent pairs of alkyl groups in an unsymmetrical dimer.
- Davies, Alwyn G.,Julia, Luis,Yazdi, Safieh N.
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p. 239 - 244
(2007/10/02)
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- ELECTRONIC EXCITATION OF ORGANOSULFUR RADICALS
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Transition energies of neutral and ionic sulfur containing heterocyclic radicals have been calculated by the method of Longuet-Higgins and Pople and compared with experimental excitation energies obtained by UV/VIS absorption and photoelectron spectroscopy.In most cases the calculated transition energies satisfactorily match the ones found experimentally.A few compounds behave exceptionally.Discrepancies between the two sets of expermental values are attributed to different molecular geometries of the radical species.According to the calculations, the UV/VIS absorption spectra of recently synthesized sulfur and nitrogen containing radicals are compatible with the 1,2,3-dithiazolyl structure.
- Fabian, J.,Mayer, R.,Bleisch, S.,Zahradnik, R.
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p. 107 - 118
(2007/10/02)
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- ESR Investigation of Radical Cations Formed from Aromatics and Heteroaromatics Adsorbed on Mo-Al2O3 Surfaces
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Molybdena-alumina is an important model catalyst system that has attracted considerable attention over the years.The behavior of adsorbed species on catalytic surfaces is also of interest because this may lead to a better understanding of the reaction mechanisms involved in the catalytic process.Using electron spin resonance, we have continued our systematic study of the molybdena-alumina system to which various aromatics and heteroaromatics have been added.We have investigated electron-transfer reactions with the molybdena-alumina surface and have also investigated the structural and dynamical aspects of the resulting adsorbed cations.Computer fitting of the cation ESR spectra has been carried out for a more precise determination of spectral parameters, and a comparison with solution spectral parameters has also been made.
- Petrakis, L.,Meyer, P. L.,Jones, Gerald L.
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p. 1029 - 1038
(2007/10/02)
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