Ternary complexes of the Cu(II) and Ni(II) chelates of edta and dcta with cyanide and ethylenediamine

Korsse, J.

doi:10.1016/0039-9140(83)80003-4

Cited by 10 publications

(1 citation statement)

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“… h From ref . i From ref . j 37 °C, 0.15 M NaCl form ref . k Competitive titration with the use of cyclen (the stability constants used for the determination are included in the Supporting Information). l 20 °C, 0.1 M NaClO 4 from ref . …”

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confidence: 99%

H₄octapa: Highly Stable Complexation of Lanthanide(III) Ions and Copper(II)

et al. 2015

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The acyclic ligand octapa 4− (H 4 octapa = 6,6′-((ethane-1,2-diylbis((carboxymethyl)azanediyl))bis-(methylene))dipicolinic acid) forms stable complexes with the Ln 3+ ions in aqueous solution. The stability constants determined for the complexes with La 3+ , Gd 3+ , and Lu 3+ using relaxometric methods are log K LaL = 20.13(7), log K GdL = 20.23(4), and log K LuL = 20.49(5) (I = 0.15 M NaCl). High stability constants were also determined for the complexes formed with divalent metal ions such as Zn 2+ and Cu 2+ (log K ZnL = 18.91(3) and log K CuL = 22.08 (2)). UV− visible and NMR spectroscopic studies and density functional theory (DFT) calculations point to hexadentate binding of the ligand to Zn 2+ and Cu 2+, the donor atoms of the acetate groups of the ligand remaining uncoordinated. The complexes formed with the Ln 3+ ions are nine-coordinated thanks to the octadentate binding of the ligand and the presence of a coordinated water molecule. The stability constants of the complexes formed with the Ln 3+ ions do not change significantly across the lanthanide series. A DFT investigation shows that this is the result of a subtle balance between the increased binding energies across the 4f period, which contribute to an increasing complex stability, and the parallel increase of the absolute values of the hydration free energies of the Ln 3+ ions. In the case of the [Ln(octapa)(H 2 O)] − complexes the interaction between the amine nitrogen atoms of the ligand and the Ln 3+ ions is weakened along the lanthanide series, and therefore the increased electrostatic interaction does not overcome the increasing hydration energies. A detailed kinetic study of the dissociation of the [Gd(octapa)(H 2 O)]− complex in the presence of Cu 2+ shows that the metal-assisted pathway is the main responsible for complex dissociation at pH 7.4 and physiological [Cu 2+ ] concentration (1 μM).

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Section: Resultsmentioning

confidence: 99%

H₄octapa: Highly Stable Complexation of Lanthanide(III) Ions and Copper(II)

et al. 2015

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Ternäre Komplexe von Eisen(III) mit Ethylendiamintetraessigsäure und einigen Anionen

Koch

Ackermann

1985

Zeitschrift fuer Chemie

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Über ternäre Komplexe des Eisen(III)‐Ions mit Aminopolycarbonsäuren und einigen Liganden

Koch

1987

Zeitschrift fuer Chemie

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In this paper is discussed the ternary complexation of iron(III) with aminopolycarboxylic acids (nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid) and some inorganic as well as organic ligands. The complicated equilibria in aqueous solution were investigated by spectrophotometric and in some cases by electrophoretic methods. It was found that the composition of the species is Fe: APC:L = 1:1:1. The reaction mechanism of these equilibria is suggested and the stability of ternary complexes is described. The measured optical properties (λmax, ϵmax) of the mixed ligand complexes are discussed and compared with the corresponding binary species.

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Ternary complexes of the Cu(II) and Ni(II) chelates of edta and dcta with cyanide and ethylenediamine

Cited by 10 publications

References 10 publications

H₄octapa: Highly Stable Complexation of Lanthanide(III) Ions and Copper(II)

H₄octapa: Highly Stable Complexation of Lanthanide(III) Ions and Copper(II)

Ternäre Komplexe von Eisen(III) mit Ethylendiamintetraessigsäure und einigen Anionen

Über ternäre Komplexe des Eisen(III)‐Ions mit Aminopolycarbonsäuren und einigen Liganden

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Ternary complexes of the Cu(II) and Ni(II) chelates of edta and dcta with cyanide and ethylenediamine

Cited by 10 publications

References 10 publications

H4octapa: Highly Stable Complexation of Lanthanide(III) Ions and Copper(II)

H4octapa: Highly Stable Complexation of Lanthanide(III) Ions and Copper(II)

Ternäre Komplexe von Eisen(III) mit Ethylendiamintetraessigsäure und einigen Anionen

Über ternäre Komplexe des Eisen(III)‐Ions mit Aminopolycarbonsäuren und einigen Liganden

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H₄octapa: Highly Stable Complexation of Lanthanide(III) Ions and Copper(II)

H₄octapa: Highly Stable Complexation of Lanthanide(III) Ions and Copper(II)