Lanthanide Complexes with Multidentate Oxime Ligands as Single-Molecule Magnets and Atmospheric Carbon Dioxide Fixation Systems
Résumé
The synthesis, structure, and magnetic properties of five lanthanide complexes with multidentate oxime ligands are described. Complexes 1 and 2 (1:[La2(pop)2(acac)4(CH3OH)], 2: [Dy2(pop)(acac)5]) are synthesized from the 2-hydroxyimino-N-[1-(2-pyridyl)ethylidene]-propanohydrazone (Hpop) ligand, while 3, 4, and 5(3:[Dy2(naphthsaoH)2(acac)4H(OH)]·0.85CH3CN·1.58H2O; 4: [Tb2(naphthsaoH)2(acac)4H(OH)]·0.52CH3CN·1.71H2O; 5:
[La6(CO3)2(naphthsao)5 (naphthsaoH)0.5(acac)8(CO3)0.5(CH3- OH)2.76H5.5(H2O)1.24]·2.39CH3CN·0.12H2O) contain 1-(1-hydroxynaphthalen- 2-yl)-ethanone oxime (naphthsaoH2). In 1–4, dinuclear [Ln2] complexes crystallize, whereas hexanuclear LaIII complex 5 is formed after fixation of atmospheric carbon dioxide. DyIII-based complexes 2 and 3 display single-molecule-magnet properties with energy barriers of 27 and 98 K, respectively. The presence of a broad and unsymmetrical relaxation mode observed in the ac susceptibility data for 3 suggest two different dynamics of the magnetization which might be a consequence of independent relaxation processes of the two different Dy3+ ions.