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  • Chemistry  (16)
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  • 1
    Electronic Resource
    Electronic Resource
    1:1 Metal Complexes of Bivalent Cobalt, Nickel, Copper, Zink, and Cadmium with the Tripodal Ligand tris[2-(dimethylamino)ethyl]amine: Their stabilities and the X-ray crystal structure of its copper(II) complex sulfate (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 685-690 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex formation by Co2+, Ni2+, Cu2+, Zn2+, and Cd2+ with tris[2-(dimethylamino)ethyl]amine (N(CH2CH2NMe2)3, Me6tren) was investigated at 25° and at an ionic strength of 1, using VIS spectroscopy and potentiometric measurements. The stability constants of these complexes are compared with those of tris(2-aminoethyl)amine (N(CH2CH2NH2)3, tren), obtained under the same conditions. The values of the constants for Me6tren are much lower than those for tren, due to the bulky Me substituents. The values of the constants can be correlated with the ability of the individual metal ions to adopt coordination number 5. This appears to be easier for Cu2+ and Co2+ than for Cd2+ and Zn2+ and is very difficult for Ni2+. The 1:1 complexes [ML(H2O)]2+ are monoprotonic acids whose pKs values are similar or lower than those of the corresponding aquametal ions. The X-ray crystal structure of the copper(II) complex [Cu(SO4)(Me6tren)] · 8H2O reveals pentacoordination at the central ion. The UV/VIS spectra of the aqueous solutions of the Co2+, Ni2+, and Cu2+ 1:1 complexes confirm that the same coordination number is present also in these complexes.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770312
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  • 2
    Electronic Resource
    Electronic Resource
    Nitrogen-NMR Studies on the Protonation of 2-(Aminomethyl)pyridine and Tris[(2-pyridyl)methyl]amine (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 329-332 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 14N- and 15N-NMR spectra have been recorded for 2-(aminomethyl)pyridine (1), tris[(2-pyridyl)methyl]amine (2), and some of their protonated forms. For 1, the most basic site is the aliphatic N-atom, whereas for 2 the pyridine N-atoms are more basic, in contrast to what might be expected for a tertiary aliphatic amine.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690210
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  • 3
    Electronic Resource
    Electronic Resource
    The Stability of Divalent 3d- and Trivalent 4f-Metal Complexes with Diazapolyoxa Macrocyclic Ligands (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1790-1795 
    Details
    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
    URL: http://dx.doi.org/10.1002/hlca.19810640608
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  • 4
    Electronic Resource
    Electronic Resource
    Polyamines XIV. Protonation Equilibria of Linear Tetraamines Containing two Ethylenediamine Residues (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 162-169 
    Details
    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
    URL: http://dx.doi.org/10.1002/hlca.19820650115
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  • 5
    Electronic Resource
    Electronic Resource
    Polyamines XV. Thermodynamics of Metal Complex Formation of Linear Tetraamines Containing Two Ethylenediamine Residues (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 913-923 
    Details
    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
    URL: http://dx.doi.org/10.1002/hlca.19820650324
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  • 6
    Electronic Resource
    Electronic Resource
    Preparation, characterization, crystal and molecular structure of Na2[N(CH2COO)3 99Tc(IV) (μ-O)2 99Tc(IV)N(CH2COO)3] · 6H2O (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 1593-1598 
    Details
    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
    URL: http://dx.doi.org/10.1002/hlca.19830660528
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  • 7
    Electronic Resource
    Electronic Resource
    Complex Formation of PdII Ion with the Tripodal Ligand Tris[2-(dimethylamino)ethyl]amine (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 1964-1969 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex formation of PdII with tris[2-(dimethylamino)ethyl]amine (N(CH2CH2N(CH3)2)3, Me6tren) was investigated at 25° and ionic strength I = 1, using UV/VIS, potentiometric, and NMR measurements. Chloride, bromide, and thiocyanate were used as auxiliary ligands. The stability constant of [Pd(Me6tren)]2+ in various ionic media was obtained: log β([Pd(Me6tren)] = 30.5 (I = 1(NaCl)) and 30.8 (I = 1(NaBr)), as well as the formation constants of the mixed complexes [Pd(HMe6tren)X]2+ from [Pd(HMe6tren)(H2O)]3+:log K = 3.50 = Cl-) and 3.64 (X- = Br-) and [Pd(Me6tren)X]+ from [Pd(Me6tren)(H2O)]2+: log K = 2.6 (X- = Cl-), 2.8(Br-) and 5.57 (SCN-) at I = 1 (NaClO3). The above data, as well as the NMR measurements do not provide any evidence for the penta-coordination of PdII, proposed in some papers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760515
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  • 8
    Electronic Resource
    Electronic Resource
    Chelate Complexes with Methylmercury and Phenylmercury Cations (1974)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 57 (1974), S. 1340-1346 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex formation of Hg2+, CH3Hg+ and C6H5Hg+ with eight substituted quinolines, α,α′-bipyridyl and 1, 10-phenanthroline has been investigated in water and 75(v)% dioxane by pH and pHg methods. Hg2+ forms mercurated products with 8-hydroxyquinolines, if the 5- or 7-positions are unsubstituted. The formation of chelates by CH3Hg+ and C6H5Hg+ is postulated.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19740570511
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  • 9
    Electronic Resource
    Electronic Resource
    Thermodynamik der Metallkomplexbildung mit Polyoxadiazamacrocyclen (1975)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 58 (1975), S. 1218-1225 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ligands of the type H3-nN(CH2CH2OCH2CH2OCH2CH2)nNH3-n with n values from 1 to 3 have been investigated. The stability constants and the heat evolved by formation of the 1:1 complexes of Na+, K+, Rb+, Tl+, Ca2+, Sr2+, Ba2+, Cd2+, Ag+, Hg2+ and Pb2+ have been determined. The complex formation is discussed in terms of ΔH and ΔS taking into consideration the radii of the cations. In contrast with the normal trend, for the A cations, complex formation is exothermic and almost exclusively favoured by the reaction enthalpy.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19750580427
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  • 10
    Electronic Resource
    Electronic Resource
    Komplexone XLVII. The Stability of Palladium(II) Complexes with Aminopolycarboxylate Anions (1976)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 59 (1976), S. 1498-1511 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The formation of Pd(II) complexes with aminopolycarboxylate anions has been investigated using pH and UV.-spectrophotometric measurements at ionic strength 1 M and 20°. In some cases bromide or thiocyanate ions have been used as auxiliary ligands. Pd2+ forms the strongest complexes of the hitherto investigated divalent metal ions. The stability constants are discussed in relation to the particular stereochemistry of Pd(II) complexes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19760590511
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