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  • 1
    Electronic Resource
    Electronic Resource
    Complexation of divalent and trivalent nickel and copper ions by rigid and flexible dioxo tetraaza macrocycles (1986)
    s.l. : American Chemical Society
    Inorganic chemistry 25 (1986), S. 321-327 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic00223a018
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  • 2
    Electronic Resource
    Electronic Resource
    Ditopic receptors for transition-metal ions: a heterobimetallic nickel(II)-copper(II) bis(macrocyclic) complex and its stepwise oxidation to the tervalent state (1986)
    s.l. : American Chemical Society
    Inorganic chemistry 25 (1986), S. 2671-2672 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic00236a001
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  • 3
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. Part XXXIPart XXX: see [1].. Protonation studies and complexation properties of tetraazamacrocyclic methylenephosphonates with earth-alkali ions (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 140-148 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The three ligands 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylenephosphonic acid) (1), 1,4,7,11-tetraazacyclotridecane-1,4,7,11-tetrakis(methylenephosphonic acid) (2), and 1,4,8,11-tetraazacyclotetradecane-1,4,8,1 1-tetrakis(methylenephosphonic acid) (3) have been synthesized by condensation of the corresponding macrocycles with formaldehyde and phosphorous acid. The protonation and stability constants with the earth-alkali ions have been determined at 25° and I = 0.1 M (Me4)N(NO3) by potentiometric titrations. Because of the high values of the first two protonation constants, 1H-NMR measurements were necessary to determine them. Titrations in different supporting electrolytes (NaNO3, KNO3, RbNO3, CsNO3, and Me4N(NO3)) show that their choice is of paramount importance, as the above ligands can form complexes with alkali-metal ions. The potentiometric results for the earth-alkali ions show that beside mononuclear complexes of different degrees of protonation ([MLHn], n = 0-4), also binuclear species are formed ([M2LHm], m = 0-2). It is interesting that 1 with the smallest macrocyclic ring has the greatest tendency to form binuclear complexes, which are so stable that they partially prevent the formation of the corresponding mononuclear species. For [ML], [MLH], [M2L], and [M2LH], the stability sequence is Mg2+ 〈 Ca2+ 〉 Sr2+ 〉 Ba2+, whereas for [MLH2], [MLH3], and [MLH4], the stability steadily decreases from Mg2+ to Ba2+.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730115
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  • 4
    Electronic Resource
    Electronic Resource
    Metal complexes with macrocyclic ligands. Part XIXPart XVIII: [1].. Synthesis and Cu2+-complexes of a series of 12-, 14- and 16-membered cis- and trans-N2S2-macrocycles (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 29-38 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of 12-, 14-, and 16-membered N2S2-macrocycles (9-11 and 19-21) with cis and trans-arrangement of the heteroatoms have been synthesized by high-dilution cyclization and subsequent reduction of the amides with B2H6. With these ligands the corresponding Cu2+-complexes were prepared and their UV/VIS spectra, their electrochemistry and their EPR properties have been studied. Generally three absorption bands at 270-320 nm, 330-370 nm and 530-620 nm can be observed in aqueous solution and these have been assigned to the N→Cu2+ and S→Cu2+ charge-transfer bands and to the d-d* transition, respectively. The cyclic voltammetry in CH3CN shows in all cases a reversible or quasi-reversible Cu2+/Cu+-transition at potentials of 10-480 mV against SHE. The values of g‖ and A‖ obtained from EPR spectra indicate that the geometry of the Cu2+-complex of the 14-membered cis-N2S2-macrocycle is less distorted than that of the other complexes.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670105
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  • 5
    Electronic Resource
    Electronic Resource
    Stabilities and Redox Properties of Cu(I) and Cu(II) Complexes with Macrocyclic Ligands Containing the N2S2 donor Set (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1060-1069 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complexation of Cu(I) and Cu(II) by a series of 12-, 14- and 16-membered macrocyclic ligands 1-6 containing the N2S2 donor set has been studied potentiometrically, spectrophotometrically and voltammetrically.In the case of Cu(II), mononuclear complexes CuL2+ with stability constants of 1010-1015 are formed. In addition, partially hydrolyzed species Cu(L)OH+ are observed at pH 〉 10 for the 12-membered ligands. For Cu(I), beside the specis CuL+ with stabilities of 1012-1014, the unexpected formation of protonated species CuLH2+ was detected. In contrast to the well-known general trends in coordination chemistry, the stability of these protonated species increases relative to that of the complexes with the neutral ligand when the ring size and concomitantly the distance between neighbouring donor atoms is decreased. From the stability constants of the Cu(I)- and Cu(II)-complexes the redox potentials have been calculated and are compared to the values of E1/2 obtained by cyclic voltammetry. Despite the identical donor set the Cu(II)/Cu(I) redox potentials of the complexes are spanning a range of 340 mV or six orders of magnitude in relative stability, reflecting the importance of subtle differences in steric requirements.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670419
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  • 6
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. Part XLVIPart XLV:[1].. Synthesis and structures of dinuclear metal complexes of bis-macrocycles having a pyrazole bridging unit (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2315-2328 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three bis-macrocyclic ligands consisting of two N3-, N2S-, or NS2-cyclononane rings, i.e., of two octahydro-1H-1,4,7-triazonine, octahydro-1,4,7-thiadiazonine, or hexahydro-5H-1,4-7-dithiazonine rings, connected by a 1H-pyrazolediyl unit were prepared. They form dinuclear CuII and NiII complexes which are able to bind one additional exogenous bridging molecule such as Cl-, Br-, N-3-, SO42-, and 1H-pyrazol-1-ide. The structures determined by X-ray diffraction show that each Cu2+ is coordinated by the three donor atoms of the macrocyclic ring, by a pyrazolidodiyl N-atom, by an atom of the exogenous bridging ligand, and sometimes by a solvent molecule. In the majority of the Cu2+ cases, the metal ion exhibits square-pyramidal or trigonal-bipyramidal coordination geometry, except in the sulfato-bridged complex, in which one Cu2+ is hexacoordinated with the participation of a water molecule. The X-ray structure of the azide-bridged dinuclear Ni2+ complex was also solved and shows that both Ni2+ centres have octahedral coordination geometries. In all complexes, the 1H-pyrazolediyl group connecting the macrocycles is deprotonated and bridges the two metal centres, which, depending on the exogenous ligand, have distances between 3.6 and 4.5 Å. In the dinuclear Cu2+ complexes, antiferromagnetic coupling is present. The azido-bridged complex shows a very strong interaction with -2J ≥ 1040 cm-1; in contrast, the H-pyrazol-1-ide and chloride bridged species have -2J values of 300 and 272cm-1, respectively. Cyclic voltammetry of the Cu2+ complexes in MeCN reveals a strong dependence of the potentials CuII/Cu-II → CuII/CuI → CuI/CuI on the nature of the donor atoms of the macrocycle as well as on the type of bridging molecule. The more S-donors are present in the macrocycle, the higher is the potential, indicating a stabilization of the Cu1 oxidation state.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800804
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  • 7
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the dissociation of the Cu2+ and Ni2+ complexes with monooxo- and dioxomacrocyclic tetraamines (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 549-555 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the acid-induced dissociation of the Ni2+ and Cu2+ complexes of a monooxo and two dioxo tetraaza macrocycles were studied by stopped-flow spectrophotometry at single wavelengths and using a photodiode array, For the monooxo derivative the dissociation rate follows the law vd = k1Ccom [H+]/(K2 + [H+]), whereas for the dioxo derivatives the law is vd = k2Ccom [H+]2/(K1 + K2 [H+] + [H+]2). The dissociation kinetics are interpreted by a mechanism in which protonated intermediates are formed in a rapid pre-equibrium, the rate-determining step being the dissociation of this species. Comparison of the spectral results from multi-wavelength stopped-flow measurements with those acquired in the equilibium study using spectrophotometric titrations allows the nature and structure of these intermediates to be discussed. The order of the dissociation rates in strongly acidic solution, where a plateau in the pH dependence is reached, was determined and it demonstrates the importance of the ring size on one hand and of the number of amide groups on the other.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050818
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