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  • Electronic Resource  (3)
  • Organic Chemistry  (3)
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  • Electronic Resource  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 2065-2072 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical cations and the radical anions of 1,6-dithiapyrene (1) and 3,10-dithiaperylene (2) as well as those of three further Weitz-type S-donors 3, 4, and 5 have been studied by ESR spectroscopy. The experimental findings for \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} (widths and behaviour on saturation of hyperfine lines) suggest that the ground state of this radical anion is effectively degenerate. With the exception of \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document}, the ESR studies of all radical ions could be complemented by the use of the ENDOR and general TRIPLE resonance techniques. In addition to proton hyperfine data, 33S coupling constants have been determined for \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{+ \atop \dot{}} $\end{document} (0.53mT), \documentclass{article}\pagestyle{empty}\begin{document}$ 2^{+ \atop \dot{}} $\end{document} (0.46mT), and \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{+ \atop \dot{}} $\end{document} (0.34mT); they are in agreement with the predicted substantial π-spin populations at the S-atoms.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photoelectron (PE.) spectra of azuleno[l, 2, 3-cd]phenalene (1) and azuleno- [5,6,7-cd]phenalene(2) have been recorded. The first five bands of both compounds could be assigned to transitions corresponding to removal of electrons from 4a2, 6b1, 5b1, 3a2 and 4bl orbitals. This assignment is based mainly on a comparison between the observed ionization potentials and orbital energies calculated in a HMO and a PPP model.The UV./VIS. polarized absorption spectrum of 1 in the region 10000-45000 cm-1 has been measured by means of the stretched film technique. The measurements were performed in polyethylene sheets at 77°K. Several bands could be assigned to π* ← π transitions calculated by a PPP-CI method.A comparison between the electronic structures of 1 and2 is made by means of a simple HMO diagram.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 58 (1975), S. 2473-2483 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical anion and the radical cation of azuleno[1,2,3-cd]phenalene (III) have been investigated by ESR. spectroscopy, along with the radical anion of 2-phenylazulene (IV). Also studied has been the neutral radical obtained by one-electron reduction of cyclohepta[cd]phenalenium-cation (VI⊕). Assignment of the proton coupling constants for the radical ions III. ·⊖, III ·⊕ and IV·⊕, and the radical VI · is supported by comparison with the ESR. spectra of specifically deuteriated derivatives III-d5 ·⊖, III-d5 ·⊕, IV-d2 ·⊖ and VI-d1′. The experimental results are in full accord with qualitative topological arguments and predictions of HMO models. Whereas the radical anion III ·⊖ exhibits α-spin distribution similar to that of IV ·⊖the corresponding radical cation III ·⊕ and the neutral radical VI · are related in this respect to phenalenyl (V·). It is noteworthy that oxidation of III by conc. H2SO4 yields a paramagnetic species (IIIa ·⊕) which has a similar - but not an identical - structure as the radical cation III ·⊕ produced from III with AlCl3 in CH3NO2.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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