Calix[4]arenes as Selective Extracting Agents. An NMR Dynamic and Conformational Investigation of the Lanthanide(III) and Thorium(IV) Complexes - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Inorganic Chemistry Année : 2000

Calix[4]arenes as Selective Extracting Agents. An NMR Dynamic and Conformational Investigation of the Lanthanide(III) and Thorium(IV) Complexes

Alexander Shivanyuk
  • Fonction : Auteur
Susan Matthews
  • Fonction : Auteur
Abdi Tunayar
  • Fonction : Auteur
Marc Baaden
Volker Böhmer
  • Fonction : Auteur
Jean Desreux
  • Fonction : Auteur

Résumé

The lanthanide and Th4+ complexes with calix[4]arene ligands substituted either on the narrow or at the wide rim by four coordinating groups behave totally differently as shown by an NMR investigation of the dia- and paramagnetic complexes. Solutions of complexes were prepared by reacting anhydrous metal perchlorate salts with the ligands in dry acetonitrile (CAUTION). Relaxation time T1 titrations of acetonitrile solutions of Gd3+ by calixarenes indicate that ligands substituted on the narrow rim form stable 1:1 complexes whether they feature four amide groups (1) or four phosphine oxide functions. In contrast, a ligand substituted by four (carbamoylmethyl)diphenylphosphine oxide moieties on the wide rim (3) and its derivatives form polymeric species even at a 1:1 ligand/metal concentration ratio. Nuclear magnetic relaxation dispersion (NMRD) curves (relaxation rates 1/T1 vs magnetic field strength) of Gd3+, Gd3+·1 and Gd3+·3 perchlorates in acetonitrile are analyzed by an extended version of the Solomon−Bloembergen−Morgan equations. A comparison of the calculated rotational correlation times τr shows that ligand 3 forms oligomeric Gd3+ species. The chelates of ligand 1 are axially symmetric (C4 symmetry), and the paramagnetic shifts induced by the Yb3+ ion are accounted for quantitatively. The addition of water or of nitrate ions does not modify the geometry of the complex. The metal chelates of 3 and its derivatives adopt a C2 symmetry, and the paramagnetic shifts are interpreted on a semiquantitative basis only. Water and NO3- ions completely labilize the complexes of the heavy lanthanides. The very high selectivity of ligand 3 through the lanthanide series stems from a complex interplay of factors.

Dates et versions

hal-03920094 , version 1 (03-01-2023)

Identifiants

Citer

Bernard Lambert, Vincent Jacques, Alexander Shivanyuk, Susan Matthews, Abdi Tunayar, et al.. Calix[4]arenes as Selective Extracting Agents. An NMR Dynamic and Conformational Investigation of the Lanthanide(III) and Thorium(IV) Complexes. Inorganic Chemistry, 2000, 39 (10), pp.2033-2041. ⟨10.1021/ic990683n⟩. ⟨hal-03920094⟩
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