Bi‐Compartmental Schiff‐Base with Peripheral Ester Functionalization: Synthesis and Magnetic Behavior of Bimetallic Zn‐Ln Complexes (Ln = Dy, Tb, Gd)

A novel ester-functionalized bi-compartmental Schiff-base ligand and its dinuclear Zn-Ln complexes [Ln = Dy (1), Tb (2), Gd (3)] are reported herein. Athough electron-withdrawing substituents at the para position of the phenol moieties do not change the coordination environment of the Ln centers in comparison with the nonfunctionalized ligand, they have a clear steric effect on the crystal packing and alter the coordination strength of the central ligand core. This is illustrated by the atypical reactivity of the bi-compartmental Schiff-base ligand towards Ln coordination and corroborated by its longer bond lengths to the rare-earth ions in comparison with the nonfunctionalized ligand. Crystal structures, magnetic behavior, and ab initio calculations for the two series of complexes are reported. A slow relaxation of the magnetization with an energy barrier of 96 K was found for Dy derivative 1 in zero field.