Enhancement of magnetic relaxation properties with 3d diamagnetic cations in [Zn II Ln III ] and [Ni II Ln III ], Ln III = Kramers lanthanides.

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 [NiIIEuIII] 1RR, 1SS and [ZnIIEuIII] 2RR, 2SS and the magnetic properties for the series of complexes [NiIILnIII], Ln = Ce, 3RR; Nd, 4RR; Dy, 5RR; Er, 6RR, Yb, 7SS and [ZnIILnIII], Ln = Ce, 8RR; Nd, 9RR; Dy, 10SS; Er, 11SS and Yb, 12RR in which MII is diamagnetic and LnIII is a Kramers lanthanide. Single crystal X-ray diffraction shows that relevant changes in the [ZnIILnIII] structures are produced after a period in open air (2RRb, 2RRc), evidencing that the lability of the ligands bonded to ZnII can modify the structures that will be correlated to the experimental measurements. The dynamic magnetic measurements showed that the [NiIILnIII] and [ZnIILnIII] derivatives exhibit different behaviors in the relaxation of magnetization especially for oblate and prolate LnIII cations.