Synthesis, structure and magnetic properties of lanthanide(III) complexes with new imidazole-substituted imino nitroxide radical

Synthesis, characterization and magnetic properties of new lanthanide–radical complexes, [LnIII(hfac)3(IM2imH)] (Ln = Gd, Tb; IM2imH = 2-(2-pyridyl)-4,5-dihydro-4,4,5,5-tetramethyl-1H-imidazolyl-1-oxy), are described. The molecular structure of the [Tb(hfac)3(IM2imH)] has been determined by the X-ray diffraction. The magnetic susceptibility data for [Gd(hfac)3(IM2imH)] show that the Gd–IM2imH magnetic interaction is antiferromagnetic with an exchange coupling constant J = −2.59 cm−1 in contrast to the ferromagnetic interaction in most of Gd(III) complexes containing paramagnetic center, which will be examined in connection with planarity of the IM2imH chelate.