New Families of Hetero-tri-spin 2p-3d-4f Complexes: Synthesis, Crystal Structures, and Magnetic Properties

In this work we report the synthesis, crystal structures, and magnetic behavior of 2p-3d-4f heterospin systems containing the nitroxide radical 4-azido-2,2,6,6-tetramethylpiperidine-1-oxyl radical (N(3)tempo). These compounds were synthesized through a one-pot reaction by using [Cu(hfac)(2)], [Ln(hfac)(3)] (hfac = hexafluoroacetylacetonate, Ln = Dy-III, Tb-III or Gd-III), and the N(3)tempo radical. Depending on the stoichiometric ratio used, the synthesis leads to penta- or trimetallic compounds, with molecular formulas [Cu(3)Ln(2)(hfac)(8)(OH)(4)(N(3)tempo)] (Ln = Gd, Tb, Dy) and [CuLn(2)(hfac)(8)(N(3)tempo)(2)(H2O)(2)] (Ln = Gd, Dy). The magnetic properties of all compounds were investigated by direct current (dc) and alternating current (ac) measurements. The ac magnetic susceptibility measurements of Tb-III- and Dy-III-containing compounds of both families revealed slow relaxation of the magnetization, with magnetic quantum tunneling in zero field.