Slow magnetic relaxation of light lanthanide-based linear LnZn2 trinuclear complexes

Four isostructural LnZn2 trinuclear complexes, [Ln(NO3){Zn(L)(SCN)}2] (H2L is a Schiff base ligand derived from o-vanillin and ethylenediamine), were synthesized, which include light lanthanide ions as spin carriers (Ln = Ce 1, Pr 2, Nd 3, and Sm 4). These complexes involve a linear Zn(ii)-Ln(iii)-Zn(ii) array, which leads to an axially stressed ligand field and can also cause single-moleluce magnet (SMM) behavior in oblate-type electronic distributions of ground sublevels found in Ce(iii), Pr(iii), and Nd(iii). Slow magnetic relaxation behavior was observed in 1 and 3 under an applied bias dc field of 1000 Oe, whereas such a slow relaxation was not observed in 2 and 4. The appearance of field-induced SMM behavior in 1 and 3 was correlated with the even-numbered Jz sublevels of Ce(iii) and Nd(iii) ions known as the Kramers system.