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  • 1990-1994  (3)
  • 1970-1974  (1)
  • Analytical Chemistry and Spectroscopy  (3)
  • Dimethylpyridine  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 123 (1992), S. 325-331 
    ISSN: 1434-4475
    Keywords: Azide ; Crystal structure ; Dimethylpyridine ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Three adducts of zinc azide with 2,4-/3,4- and 3,5-dimethylpyridine (DMP), respectively, were prepared and the crystal structures determined by single crystal X-ray diffraction methods. The three compounds crystallize in the monoclinic space group P21/c withZ=4: Zn(N3)2·2,4-DMP at 300 (2) K:a=1 098.6(4),b=1 600.2(6),c=608.8(3) pm, β=102.47(3)°;R=0.071 (R w =0.056). Zn(N3)2·3,4-DMP at 103 (3) K:a=1 102.1(3),b=1 649.0(4),c=611.8(1) pm, β=104.54(2)°;R=0.055 (R w =0.051). Zn(N3)2·3,5-DMP at 97 (3) K:a=602.1(2),b=2 037.9(7),c=853.8(3) pm, β=90.77(3)°;R=0.069 (R w =0.055). The molecular geometry is similar for the three adducts, but the packing of theDMP-molecules is different. The zinc atoms are surrounded by five nitrogen atoms, four belonging to the azide groups and one to theDMP-adduct. The trigonal bipyramidal shaped ZnN5-polyhedra share common edges to form chains.
    Type of Medium: Electronic Resource
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  • 2
    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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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 30 (1992), S. 84-86 
    ISSN: 0749-1581
    Keywords: ESR ; Nitrogen-centred radicals ; 2,3-Dihydro-1-oxo-1λ4,2,3,5-thiatriazol-3-yl radicals ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dehydrogenation of 2,5-dihydro-1,2,3,5-thiatriazole 1-oxides with thermally formed bis(4-methylphenyl)aminyl generated 2,3-dihydro-1-oxo-1λ4,2,3,5-thiatriazol-3-yl radicals. ESR, ENDOR and triple resonance studies in combination with 15N labelling yielded the magnitude and assignment of all 1H and 14N hyperfine coupling (HFC) constants. The radicals have a basic five-π-electron amidrazon-2-yl structure with the highest spin density at N-2.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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