We report the synthesis and characterization of seven new tetranuclear 3d–4f complexes derived from the 3:3:1 reaction of 1,4-diformylnaphthalene-2,3-diol (H2 L) with copper­(II) nitrate and a lanthanide salt, Ln = Tb [L 3Cu3TbCl2(NO3)2(H2O)2] (C1), Ho [L 3Cu3HoCl3(H2O)3(MeOH)]­(H2O) (C2), Er [L 3Cu3ErCl3(H2O)3.5(MeOH)0.5]­(H2O) (C3), Gd [L 3Cu3Gd­(NO3)2(H2O)2(MeOH)]­(NO3) (C4), Dy [L 3Cu3Dy­(NO3)2(H2O)2(MeOH)]­(NO3) (C5), Yb [L 3Cu3Yb­(NO3)2(H2O)2(MeOH)]­(NO3) (C6), and La [L 3Cu3La­(NO3)2(H2O)2(MeOH)]­(NO3) (C7). Structural elucidation showed that the self-assembly using the acyclic ligand system was successful for all seven complexes, which exhibit the same near-planar Cu3LnO12 core. Five complexes (C1, C2, and C4–C6) were magnetically characterized at 300 K and 1.8 K. Complexes C1, C4, and C5 were observed to have ferromagnetic ground states and showed appreciable frequency dependence in their AC magnetic measurements, which yielded effective barriers between 7.82(4) and 13.2(3) K, confirming the presence of single-molecule magnet properties.

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A cubane-like complex dianion [Tb4(OH)4(tfa)6(hfac)4]2− was synthesized, accompanied by two counter cations of [Ni(hfac)(2pyIN)2]+, where Htfa, Hhfac, and 2pyIN stand for trifluoroacetic acid, 1,1,1,5,5,5-hexafluoropentane-2,4-dione, and 4,4,5,5-tetramethyl-2-pyridylimidazolin-1-oxyl, respectively. In the complex anion, each Tb ion was capped with hfac, and each Tb···Tb diagonal was bridged with tfa, thus forming an approximate Td symmetry, though the whole molecular formula was crystallographically independent in an orthorhombic Pbca space group. The ionic charge was −2 in total. The magnetic study revealed that the complex ions were magnetically isolated from each other. Practically no 4f–4f superexchange interaction was operative, while the 2p–3d ferromagnetic coupling seemed to be appreciable, as anticipated from the proposed magnetostructural relationship.