Slow Relaxation of Magnetization in an Isostructural Series of Zinc–Lanthanide Complexes: An Integrated EPR and AC Susceptibility Study

We report the synthesis, structure, and spectroscopic and dynamic magnetic properties of a series of heterodinuclear complexes, [ZnLn(LH 4 ) 2 ](NO 3 ) 3 ⋅ 6 H 2 O (Ln=Nd, Tb, Dy, Ho, Er, and Yb), with the singly deprotonated form of a new compartmentalized Schiff‐base ligand, LH 5 . The Ln III ions in these systems show a distorted square‐antiprism geometry with an LnO 8 coordination sphere. EPR spectroscopy and DC magnetic studies have shown that the anisotropic nature of the complexes is far more complicated than predicted on the basis of a simple electrostatic model. Among the investigated systems, only the Dy III derivative showed single‐ion magnet behavior, in zero and an applied magnetic field, both in pure polycrystalline samples and in a series of polycrystalline samples with different degrees of dilution at the single‐crystal level in the isostructural Y III derivative. The rich dynamics observed as functions of frequency, field, and temperature reveals that multiple relaxation mechanisms are at play, resulting in a barrier of 189 cm −1 , which is among the highest reported for a dinuclear Zn–Dy system. Analysis of the dynamic behavior as a function of dilution degree further evidenced the persistence of non‐negligible intermolecular interactions, even at the lowest concentration of 1 %.