Enhancement of magnetic relaxation properties with 3d diamagnetic cations in [ZnIILnIII] and [NiIILnIII], LnIII = Kramers lanthanides

Abstract

Employing the chiral bi-compartmental Schiff-base ligand H₂L obtained from the condensation of (RR) or (SS)-1,2-diphenyl-ethylenediamine and o-vanillin, we report the structural characterization of the discrete dinuclear pairs of enantiomers [Ni^IIEu^III] 1RR, 1SS and [Zn^IIEu^III] 2RR, 2SS and the magnetic properties for the series of complexes [Ni^IILn^III], Ln = Ce, 3RR; Nd, 4RR; Dy, 5RR; Er, 6RR, Yb, 7SS and [Zn^IILn^III], Ln = Ce, 8RR; Nd, 9RR; Dy, 10SS; Er, 11SS and Yb, 12RR in which M^II is diamagnetic and Ln^III is a Kramers lanthanide. Single crystal X-ray diffraction shows that relevant changes in the [Zn^IILn^III] structures are produced after a period in open air (2RRb, 2RRc), evidencing that the lability of the ligands bonded to Zn^II can modify the structures that will be correlated to the experimental measurements. The dynamic magnetic measurements showed that the [Ni^IILn^III] and [Zn^IILn^III] derivatives exhibit different behaviors in the relaxation of magnetization especially for oblate and prolate Ln^III cations.