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  • 1980-1984  (4)
  • Organic Chemistry  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1790-1795 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex formation of some divalent 3d- and trivalent 4f-metal ions with four macrocyclic ligands has been investigated in methanol/water 95:5 by use of alkalimetric titrations. In contrast to alkali and alkaline-earth cations the obtained stability constants are quite low. The reasons of this effect are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 162-169 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of the linear tetraamines H2N—(CH2)2—NH—(CH2)2—NH—(CH2)2—NH2 (n = 4 and 5) are described. The protonation of the homologous tetraamines for n = 2, 3, 4, 5, 6 and 8, as well as of N-methylethylenediamine, was investigated using potentiometric and calorimetric measurements. The results obtained are discussed taking into consideration the substituent effect on the basicity of the aminic N-atoms.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 913-923 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex formation of Co2+, Ni2+, Cu2+, Zn2+, Pb2+ and Hg2+ with three tetraamines of type H2N—(CH2)2—NH—(CH2)n—NH—(CH2)2—NH2 (= 2, n, 2-tet) for n = 2. 3 and 4, and with N-methylethylenediamine (= nmen) have been investigated at 25° and I = 1(KNQ3). The stability constants and the heat evolved by formation of the (1:1)-complexes ML have been determined. It is shown that the more stable complexes are normally formed by 2,3,2-tet-ligands. These results are discussed relating the thermodynamic data obtained to the stereochemistry of the complexes and using the visible spectra of the complexes in solution. The change in enthalpy is found to be the dominant factor and the measure of the steric strain whereas the entropy of complex formation decreases slowly.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound and its potassium analog have been prepared from corresponding aqueous solutions of 99TcO4-; at pH ≍ 2 with SO2 as a reducing agent. An X-ray structure determination of the Na-salt showed Tc coordinated to the tetradentate N(CH2COO)33- ligand (NTA). Two Tc-NTA moieties are joined via two bridging O-atoms into a four-membered Tc2O2 ring. The observed diamagnetism, a strong absorption band at 19 950 cm-1, and a short Tc-Tc distance of 2.363 Å are typical for the Tc2O2-fragment with its strong metal-metal interaction. The structural trans-influence at Tc and the network of H-bonds are consistent with Tc in oxidation state IV.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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