Synthesis and characterization of a heptadentate (N4O3) schiff base ligand and associated La(ІІІ), Sm(III) AND Gd(III) complexes, and a theoretical study

Abstract

A new symmetrical potentially heptadentate (N₄O₃) Schiff base ligand    {N[CH₂CH₂CH₂N=CH(2-OH-5-BrC₆H₃)]₃} (H₃L⁶) and associated neutral Gd(III), La(III) and Sm(III) complexes, were synthesized. The new compounds were characterized by IR spectroscopy, elemental analysis and mass spectrometry in all cases and in the case of ligand also with NMR spectroscopy. The relative capability of H₃L⁶ to encapsulate a lanthanide ion, herein La(III), has been theoretically studied by ab initio restricted Hartree-Fock (RHF) and DFT (B3LYP) methods. The calculation confirmed that the H₃L⁶ ligand can effectively encapsulate a lanthanide ion and enforce a seven-coordinate geometry.

KEY WORDS:Ab initio, Heptadentate ligands, Lanthanide ions, Schiff base complexes


Bull. Chem. Soc. Ethiop. 2010, 24(1), 59-66.