Two new mononuclear tri-spin lanthanide-nitronyl nitroxide radical complexes: Syntheses, structure and magnetic properties

Based on a new nitronyl nitroxide radical, 2-(benzo[b]thiophen-2-yl)-4,4,5,5-tetramethylimidazolin-1-oxyl-3-oxide (NITThioPh), two new mononuclear tri-spin complexes [Ln(hfac)(3)(NITThioPh)(2)] (Ln = Gd (1), Tb (2); hfac = hexafluoroacetylacetonate) are successfully synthesized and fully characterized. Complexes 1 and 2 are isostructural and crystalize in P2(1)/c space group, in which the central metal ions are eight-coordinated in distorted triangular dodecahedron LnO(8) coordination geometries (D-2d symmetry) finished by three bischelate hfac(-) ligands and two monodentate radicals. Magnetic studies on 1 suggest the coexistence of ferromagnetic nearest-neighbor (NN) coupling between Gd(III) ions and radical spins and antiferromagnetic next-nearestneighbor (NNN) interaction between intramolecular radical spins. In addition, antiferromagnetic ordering below 1.8 K was detected in the Tb(III) complex. (C) 2015 Elsevier B.V. All rights reserved.