Three cyclic lanthanide-radical complexes syntheses, crystal structures and magnetic properties

Abstract

Three lanthanide–nitronyl nitroxide radical complexes [Ln(hfac)3(NIT-2Br-4Py)]2 (Ln(III) = Gd (1), Tb (2), Dy (3); hfac = hexafluoroacetylacetonate; NIT-2Br-4Py = 2-(2′-bromo-4′-pyridyl)-(4,4,5,5-tetramethyl-3-oxylimidazoline-1-oxide)) have been synthesized. Single crystal X-ray diffraction analysis reveals that complexes 1–3 are isomorphous in which NIT-2Br-4Py acts as a bridging ligand linking two Ln(III) ions through the nitrogen atom of pyridine ring and the oxygen atom of NO group to form a four-spin system. The magnetic studies show that ferromagnetic coupling interaction between Ln(III) ions and nitronyl nitroxide radical. Moreover, ac measurements show that Tb(III) complex exhibits frequency-dependent signals at low temperature.