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

Four isostructural LnZn(2) 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 J(z) sublevels of Ce(III) and Nd(III) ions known as the Kramers system.