Structural and Magnetic Properties of 2p-3d-4f Hetero-Tri-Spin Chains Comprising [{Cu(hfac)2 -Radical}2 ] Dimers and Ln(hfac)3 (hfac=hexafluoroacetylacetonate).

A new family of 2p-3d-4f hetero-tri-spin complexes [Ln(hfac)3 {Cu(hfac)2 (NIT-3 PyPh)}2 ] (Ln=Gd (1), Tb (2), Dy (3), Ho (4); NIT-3 PyPh=2-[4-(3-pyridinylmethoxy)phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; hfac=hexafluoroacetylacetonate) have been synthesized. Four complexes possess a 1D chain structure in which two radical ligands join two Cu(hfac)2 molecules to form a [{Cu(hfac)2 -rad)}2 ] dimer cycle and the dimer rings are linked by Ln(hfac)3 units. Magnetic studies show that ferromagnetic exchange couplings exist between the coordinated NO groups of radical ligands and metal ions. Field-induced slow relaxation of the magnetization was observed in the Tb and Dy compounds.