Syntheses, crystal structures and magnetic properties of two new Ln(III)-nitronyl nitroxide (LnGd(III), Dy(III)) complexes

Two new complexes based on rare-earth-radical of formula {Ln(hfac)3[NITPhp-OCH2CHCH2]2} (LnGd (1), Dy(2)); hfachexafluoroacetylacetonate; NITPhp-OCH2CHCH22-(4′-Alloxylphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been synthesized and their structures and magnetic properties have been characterized. The X-ray crystal structure analyses show that two complexes have similar structures, in which the metal ions are eight-coordinated in slightly distorted dodecahedron geometry. Two oxygen atoms of the N–O group from nitronyl nitroxide radicals and six oxygen atoms from three different hfac anions are coordinated to the metal ions. Due to the steric hindrance effect, two complexes are mononuclear structures. In complex 1, the molecular units are bridged by the hydrogen bonds to form a 1D chain structure, while in complex 2, 3D network structure is built by three kinds of hydrogen bonds. The variable temperature magnetic susceptibility studies reveal that there are ferromagnetic interactions between the Gd(III) ions and the radicals in complex 1, while there exists antiferromagnetic interactions between the Dy(III) ions and the radicals in complex 2.

Graphical abstractTwo complexes based on rare-earth-radical have been synthesized and characterized. These complexes have similar mononuclear structures, in which the metal ions are eight-coordinated dodecahedron geometry. Complex 1 forms a 1D chain structure, while complex 2 shows a 3D network structure by hydrogen bonds. The magnetic studies show that there are ferromagnetic interactions between the Gd(III) ions and the radicals, while complex 2 exhibits antiferromagnetic interactions between the Dy(III) ions and the radicals.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesize two rare-earth metal complexes based on nitronyl nitroxide radicals. ► Two complexes have eight-coordinated dodecahedron geometry. ► Complex 1 and 2 form a 1D chain and 3D network structure by different hydrogen bonds, separately. ► Weak ferromagnetic coupling exists between Gd(III) ion and radical. ► Weak antiferromagnetic interaction exists between the Dy(III) ion and radical.