Slow magnetic relaxation in Cu(ii)–Eu(iii) and Cu(ii)–La(iii) complexes

Abstract

A dinuclear {Cu^II–Eu^III} complex has been prepared and characterized by single crystal X-ray diffraction, where each metal atom is doubly phenoxido-bridged by the two phenolato oxygen atoms of a hexadentate Schiff-base ligand. The DC magnetic data is consistent with the population of the lowest electronic multiplets of the Eu(III) atom i.e., ground ⁷F₀ and thermally accessible ⁷F₁ (ΔE/hc ∼ 300 cm⁻¹) tuned by a weak exchange with the Cu(II) centre that is of an antiferromagnetic nature. The AC susceptibility measurements confirm the presence of field supported slow magnetic relaxation: the relaxation time is τ_LF (1.9 K) = 25 ms for the low-frequency relaxation channel. Also the isostructural analogue {Cu^II–La^III} shows slow magnetic relaxation, however with different dynamic characteristics.