[(Cu-Radical)2‑Ln]: Structure and Magnetic Properties of a Hetero-tri-spin Chain of Rings (Ln = YIII, GdIII, TbIII, DyIII)

Novel hetero-tri-spin coordination polymers formed of ring-shaped Cu-nitronyl nitroxide spin clusters and LnIII linkers are reported. These mixed 2p-3d-4f compounds of formula {[Ln­(hfac)3]­[Cu­(hfac)2(NIT-3Py)]2·C6H14}n [LnIII = Y (1), Gd (2), Tb (3), and Dy (4); NIT-3Py = 2-(3-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; hfac = hexa-fluoroacetylacetonate], exhibit a 1D chain structure consisting of [Cu­(NIT-3Py)]2 rings linked by Ln­(hfac)3 units. Their magnetic behavior is characteristic for ferromagnetic interactions between the metal centers and the coordinated radical units. The Tb derivative was found to exhibit slow relaxation of its magnetization.