Solid‐State and Solution Structure of Lanthanide(III) Complexes with a Flexible Py‐N₆ Macrocyclic Ligand

Abstract

Lanthanide complexes of a hexaaza macrocyclic ligand containing a pyridine head unit (L) were synthesized (Ln = LaLu, except Pm). The solid-state structures of the corresponding La, Ce, Pr, Nd, and Lu complexes were determined by single-crystal X-ray crystallography, and they reveal the presence of three different mononuclear complexes with three different conformations of the macrocycle and coordination environments around the metal ions. In all complexes the lanthanide ion is coordinated in an endomacrocyclic manner to the six nitrogen donor atoms of the ligand. In the La, Ce, and Pr complexes the metal ions show a 12-coordinate mononuclear environment in which 3 nitrate anions coordinate in a bidentate fashion. However, in the Nd analogue the metal ion displays a 10-coordinated environment with the coordination of 2 bidentate nitrate groups, whereas Lu shows a 9-coordinate environment interacting with 2 nitrate ligands, one of them acting as bidentate and the second one coordinating in a monodentate fashion. The

Applications of Density Functional Theory (DFT) to Investigate the Structural, Spectroscopic and Magnetic Properties of Lanthanide(III) Complexes

“…However, the electronic description becomes less accurate in molecular calculations, which often predict too short Ln-ligand bonds and too high binding energies [89,91]. Different GGA functionals such as BLYP [92,93], or BP86 [92,94] have been successfully used for describing lanthanide coordination compounds, yet hybrid functionals such as B3LYP [92,95] are often the functionals of choice within computational lanthanide chemistry [96][97][98][99][100]. An evaluation of different GGA and hybrid functionals on the LnF (Ln = Nd, Eu, Gd, Yb) and YbH systems showed that B3LYP and BP86 functionals give very similar geometries, with BLYP calculations deviating slightly more from the experimental results [101].…”

Selective Chelation of Cd(II) and Pb(II) versus Ca(II) and Zn(II) by Using Octadentate Ligands Containing Pyridinecarboxylate and Pyridyl Pendants

“…With the use of frequency calculations, the zero-point energies and the thermal corrections together with the entropies were calculated in order to convert the internal energies to the Gibbs energies at 298.15 K. The solvation energies were computed in order to convert the gas-phase energies to the energies in the solution phase. 53 Hydration free energies were evaluated by using the polarizable continuum model (PCM). In particular, we used the C-PCM variant 54 that employs conductor rather than dielectric boundary conditions.…”

Density functional dependence of molecular geometries in lanthanide(III) complexes relevant to bioanalytical and biomedical applications

“…However, the electronic description becomes less accurate in molecular calculations, which often predict too short Lnligand bonds and too high binding energies [35] . Different functionals that use generalized gradient approximation (GGA) such as BLYP, or BP86 have been successfully used for describing lanthanide complexes, yet hybrid functionals such as B3LYP are often the functionals of choice within computational lanthanide chemistry [36][37][38][39][40] . An evaluation of different GGA and hybrid functionals on the LnF (Ln = Nd, Eu, Gd, Yb) and YbH systems showed that B3LYP and BP86 functionals give very similar geometries, while BLYP calculations deviate slightly more from the experimental results [41] .…”