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  • Inorganic Chemistry  (11)
  • Analytical Chemistry and Spectroscopy  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1477-1479 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Yellow Isomer of (1,5-Diphenylformazanyl)glyoxylic AcidThe yellow isomer is shown to be 4,4-dihydroxy-l-phenyl-3-phenylazo-2-pyrazolin-5-one (3), the hydrate of the pyrazolin-4,5-dione 4. Treatment of 4 with a solution of potassium -tert- butoxide in dimethylsulfoxide leads to the formation of a radical anion identified as 5 by ESR.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2423-2430 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,4-Dihydro-1,2,4-benzotriazine Radical Cations1,4-Dihydro-1,2,4-benzotriazinyl radicals (4) are protonated in the presence of strong acids. The structure of the radical cations was confirmed by ESR studies of deuterated derivatives.
    Notes: 1,4-Dihydro-1,2,4-benzotriazinyl-Radikale (4) werden in Gegenwart starker Säuren protoniert. Die Konstitution der Radikalkationen wurde durch ESR-spektroskopische Untersuchung deuterierter Derivate gesichert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1076-1079 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,3-Diphenyl-2,3-diazabicyclo[2.2.2]octaneThe title compound 5 was synthesized by twofold arylation of 2,3-diazabicyclo[2.2.2]oct-2-ene (1). The conformational features of 5 are discussed using 1H NMR and PE data.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 2049-2051 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Verdazyle, 27. 1,1′,5,5′-Tetraphenyl-3,3′-biverdazyl, das primäre BisverdazylDie Titelverbindung 3 wurde dargestellt. Die gefundenen Nullfeldaufspaltungsparameter |D′| = 305 G und |E′| ≍ 0 G entsprechen der Struktur.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1,1,2,2-bis(1,3-diketo-2,2-bindanylidene)ethane radical anion (13) and 1,1,4,4-bis (1,3-diketo-2,2-binanylidene)butene-2 radical anion (14)We employ herein nomenclature wherein the term ‘radical anion’ means the gain of one electron of the named substrate. representing 1,6- and 1,8-conjugated semidiones have been prepared by reduction. Electron spin resonance hyperfine splitting constants have been assigned on the basis of Hückel and McLachlan calculations.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Not only strongly basic aromatic amines such as ‘proton sponges’ show characteristic [M - Me2NH - H]+ peaks corresponding to cyclization to stable heterocyclic ions under electron impact. The fragmentation of the title compounds, which are weak bases, leads to [M - RNH2 - C6H5]+ heteroaromatic ions. These are the 7-phenyl-7H-benz[kl]acridine radical cation and the delocalized stable 7H-benz[kl]acridin-7-ylium ion as shown by unimolecular metastable ion spectra, collision-induced decomposition (CID) tandem mass spectrometry (MS/MS) and accurate mass measurements. The high-collision-energy CID tandem mass spectra of these ions are perfectly superimposable on those of the ions produced by the reference substance, 7-phenyl-7H-benz[kl]acridine obtained as a by-product in the Ullmann phenylation of 1,8-diaminonaphthalene. This combination of MS/MS experiments also provides strong support for the gas-phase reaction mechanism leading to the benz[kl]acridine ions and for the structures of these ions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical anions and cations have been prepared by the reduction of the title compounds or their diprotonated derivatives. The same radical ions have been observed by oxidation of the dihydro derivatives. Electron spin resonance hyperfine splitting constants have been assigned on the basis of Hückel and McLachlan calculations and selective substitutions. The hyperfine splitting by the bridging hydrogen atoms in the radical anions was much weaker (0·5 to 0·7 gauss) than for the corresponding radical cations (2 to 3 gauss) for the naphthacene, anthracene, and naphthalene dihydrotetrones. This is interpreted to be a result of orbital symmetry since, in the highest occupied MO for the anion but not for the cation, a nodal plane passes through the bridging hydrogen atom.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1885-1889 
    ISSN: 0009-2940
    Keywords: Pyrimidine derivatives ; Sulfur extrusion, photolytic ; Pyrimidinophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds 1 and 2 are synthesized by photolytic sulfur extrusion from the 2,11-dithia[3.3](2,5)pyrimidinophane 17. The molecular structures of 1 and 2 are determined by X-ray structure analysis and are discussed with regard to the steric strain in these molecules. Thermolysis of [(5-methyl-2-pyrimidinyl]methyl]- or [(2-methyl-5-pyrimidinyl)methyl]-trimethylammonium hydroxide (10 or 11) does not generate 1 and 2. α-Chlorination of 2,5-dimethylpyrimidine (3) with N-chlorosuccinimide provides the required precursors 4-6.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 815-822 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 6-Oxo- and 6-ThioxoverdazylsA series of persistent 6-oxo- (4a-P) and 6-thioxoverdazyls (5a-g) could be obtained by dehydrogenation of corresponding 1,4,5,6-tetrahydro-1,2,4,5-tetrazin-3(2H)-ones (2a-p) and thiones (3a-g). This reaction can also be used for the preparation of diradicals, e.g. 7 and 10. Reduction, oxidation, and spectra of the radicals were investigated. The ESR results are discussed in detail.
    Notes: Eine Reihe beständiger 6-Oxo- (4a-p) und 6-Thioxoverdazyle (5a-g) konnten durch Dehydrierung der 1,4,5,6-Tetrahydro-1,2,4,5-tetrazin-3(2H)-one (2a-p) bzw. der Thione (3a-g) erhalten werden. Diese Reaktion läßt sich auch auf die Darstellung von Diradikalen, z.B. 7 und 10, übertragen. Reduktion, Oxidation und Spektren der Radikale wurden und Spektren der Radikale wurden Untersucht. ESR-Ergebnisse werden eingehend diskutiert.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 523-533 
    ISSN: 0009-2940
    Keywords: Hofman 1,6-elimination / Pyrazine derivatives / [2.2]Pyrazinophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds 1-3 and their methyl derivatives 4-7 were synthesized 2,11-dithia[3.3]pyrazinophanes 24-26 or by Hofmann 1,6-elimination of the appropriate [(5-methyl-2-pyrazinyl)methyl]trimethylammonium hydroxides followed by dimerization of the generated 2,5-dihydro-2,5-dimethylenepyrazines. α-Chlorination of the methylpyrazines 8-10 with N-chlorosuccinimide gave the required precursors 11, 12, 14, 17 and 18. The results of the X-ray structure determinations for 1-4 and 7 which indicate an unequivocal isomer assignment are discussed with regard to steric strain in these molecules. The electronic spectra of the pyrazinophanes 7-7 are reported and compared with those of the parent methylpyrazines.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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