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
(N3tempo). These compounds were synthesized through a one-pot
reaction by using [Cu­(hfac)2], [Ln­(hfac)3] (hfac
= hexafluoroacetylacetonate, Ln = DyIII, TbIII or GdIII), and the N3tempo radical. Depending
on the stoichiometric ratio used, the synthesis leads to penta- or
trimetallic compounds, with molecular formulas [Cu3Ln2(hfac)8­(OH)4(N3tempo)]
(Ln = Gd, Tb, Dy) and [CuLn2(hfac)8­(N3tempo)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 TbIII- and DyIII-containing compounds of both families revealed slow relaxation
of the magnetization, with magnetic quantum tunneling in zero field.