Structural switching from paramagnetic to single-molecule magnet behaviour of LnZn2 trinuclear complexes

Five LnZn(2) trinuclear complexes, [Ln(NO3){Zn(L)(SCN)}(2)] (H2L is a Schiff base ligand derived from o-vanillin and ethylenediamine; Ln = Tb 1, Dy 2, La 3, Tb0.14La0.86 4, and Dy0.21La0.79 5), were synthesised in which the Zn-II-Ln(III)-Zn-II array exhibits two slightly different arrangements: 1 and 2 exhibited slightly bent arrangements, whereas 3-5 exhibited more linear arrangements. These differences in the arrangements lead to a slightly different coordination geometry around Ln(III). From the detailed studies of dynamic susceptibility, 1 and 2 were found to be paramagnetic, whereas 4 and 5 were SMMs with barriers for the flipping of magnetisation with a height of 41.2(4) K and 156(4) K, respectively.