Highly stable complexes of divalent metal ions (Mg2+, Ca2+, Cu2+, Zn2+, Cd2+, and Pb2+) with a dota‐like ligand containing a picolinate pendant
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Highly stable complexes of divalent metal ions (Mg2+, Ca2+, Cu2+, Zn2+, Cd2+, and Pb2+) with a dota‐like ligand containing a picolinate pendantAutor(es)
Data
2014-12Cita bibliográfica
Regueiro‐Figueroa, M., Ruscsák, E., Fra, L., Tircsó, G., Tóth, I., de Blas, A., Rodríguez‐Blas, T., Platas‐Iglesias, C. and Esteban‐Gómez, D. (2014), Highly Stable Complexes of Divalent Metal Ions (Mg2+, Ca2+, Cu2+, Zn2+, Cd2+, and Pb2+) with a Dota‐Like Ligand Containing a Picolinate Pendant. Eur. J. Inorg. Chem., 2014: 6165–6173.
Resumo
[Abstract] The stability constants of complexes of the macrocyclic ligand do3a‐pic4– (H4do3a‐pic = 2,2′,2″‐{10‐[(6‐carboxypyridin‐2‐yl)methyl]‐1,4,7,10‐tetraazacyclododecane 1,4,7‐triyl}triacetic acid) with several divalent metal ions (Pb2+, Cd2+, Zn2+, Cu2+, Ca2+, and Mg2+) have been determined by using pH‐potentiometric titrations (I = 0.1 M KCl, 25 °C). The stability of these complexes follows the trend Cu2+ > Cd2+ ≈ Pb2+ ≈ Zn2+ >> Ca2+ >> Mg2+. A particularly high stability constant has been determined for the Cu2+ complex [log KCuL = 23.20(4)]. Analysis of the titration curves indicate the presence of protonated forms of the complexes in solution, with protonation constants of log KM(HxL) = 6.9–2.0 (x = 1, 2, or 3). The structure of the complexes in solution has been investigated by using 1H and 13C NMR spectroscopy and DFT calculations performed in aqueous solution at the TPSSh/6‐31G(d) level. In the case of the Pb2+ and Cd2+ complexes, relativistic effects were considered with the use of relativistic effective core potentials. Calculations show that the complexes with the largest metal ions (Pb2+ and Ca2+) are nine‐coordinate, with their coordination polyhedra being best described as capped twisted square antiprisms. The Cd2+ and Mg2+ complexes are seven‐coordinate, with the metal ions being bound to the four nitrogen atoms of the cyclen unit and the three acetate pendant arms. Finally, in the Cu2+ and Zn2+ complexes, the metal ions are six‐coordinated, with the metal ions being asymmetrically placed inside the macrocyclic cavity of the ligand, and the coordination polyhedra can be described as an octahedron and a trigonal prism, respectively.
Palabras chave
Macrocycles
Macrocyclic ligands
Lead
Copper
Cadmium
Macrocyclic ligands
Lead
Copper
Cadmium
Versión do editor
Dereitos
This is the peer reviewed version of the following article: Regueiro‐Figueroa, M., Ruscsák, E., Fra, L., Tircsó, G., Tóth, I., de Blas, A., Rodríguez‐Blas, T., Platas‐Iglesias, C. and Esteban‐Gómez, D. (2014), Highly Stable Complexes of Divalent Metal Ions (Mg2+, Ca2+, Cu2+, Zn2+, Cd2+, and Pb2+) with a Dota‐Like Ligand Containing a Picolinate Pendant. Eur. J. Inorg. Chem., 2014: 6165–6173, which has been published in final form at https://doi.org/10.1002/ejic.201402693. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
ISSN
1434-1948
1099-0682
1099-0682