title: Lanthanide(III) complexes with a reinforced cyclam ligand show unprecedented kinetic inertness.
abstract: Lanthanide(III) complexes of a cross-bridged cyclam derivative containing two picolinate pendant arms are kinetically inert in very harsh conditions such as 2 M HCl, with no dissociation being observed for at least 5 months. Importantly, the [Ln(dota)](-) complexes, which are recognized to be extremely inert, dissociate under these conditions with lifetimes in the range ca. 1 min to 12 h depending upon the Ln(3+) ion. X-ray diffraction studies reveal octadentate binding of the ligand to the metal ion in the [Eu(cb-tedpa)](+) complex, while (1)H and (13)C NMR experiments in D2O point to the presence of a single diastereoisomer in solution with a very rigid structure. The structure of the complexes in the solid state is retained in solution, as demonstrated by the analysis of the Yb(3+)-induced paramagnetic shifts.
authors.affiliation: Departamento de Química Fundamental, Universidade da Coruña , Campus da Zapateira-Rúa da Fraga 10, 15008 A Coruña, Spain.
authors.forename: Aurora
authors.initials: A
authors.lastname: Rodríguez-Rodríguez
authors.forename: David
authors.initials: D
authors.lastname: Esteban-Gómez
authors.forename: Raphaël
authors.initials: R
authors.lastname: Tripier
authors.forename: Gyula
authors.initials: G
authors.lastname: Tircsó
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Garda
authors.forename: Imre
authors.initials: I
authors.lastname: Tóth
authors.forename: Andrés
authors.initials: A
authors.lastname: de Blas
authors.forename: Teresa
authors.initials: T
authors.lastname: Rodríguez-Blas
authors.forename: Carlos
authors.initials: C
authors.lastname: Platas-Iglesias
mesh_terms: D006571:Heterocyclic Compounds / Q000737:chemistry*; D007700:Kinetics; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*
chemical_list: D006571:Heterocyclic Compounds; D028581:Lanthanoid Series Elements; D008024:Ligands; D009942:Organometallic Compounds; C024560:cyclam