2p-3d-4f Heterotrispin Chains and Ring–Chains Bridged by a Nitronyl Nitroxide Ligand: Structure and Magnetic Properties

Two types of the radical-3d-4f chains {[Cu­(hfac)2]­[(NIT-4PyPh)]2[Ln­(hfac)3]}n (Ln = Gd, 1; Tb, 2; Dy, 3) and {[Cu­(hfac)2(NIT-4PyPh)]2Ln­(hfac)3}n (Ln = Gd, 4; Tb, 5; Dy, 6; NIT-4PyPh = 2-[4-(4-pyridinylmethoxy)­phenyl]-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide; hfac = hexafluoroacetylacetonate) have been successfully achieved upon adjusting the experimental conditions. Compounds 1–3 display one-dimensional (1D) chain structure with NIT-4PyPh radical ligand bridging LnIII and CuII ions in “head-to-head” mode through pyridine-N atom and nitroxide unit of the radical. Complexes 4–6 possess an interesting 1D topological structure consisting of cyclic [Cu-Radical]2 dimers connected by Ln ions. Magnetic investigations indicate that ferromagnetic the copper­(II)/lanthanide­(III)-NO exchange occurs in two series of compounds. Furthermore, complexes 3 and 5 were found to exhibit frequency dependence of ac susceptibilities, evidencing slow magnetic relaxation