Rare single-molecule magnets with six-coordinate LnIII ions exhibiting a trigonal antiprism configuration†
Abstract
Four Ni–Ln–Ni heterometallic complexes, [Ni2LnL2]NO3·3H2O (H3L = tri(((3-methoxysalicylidene)amino)ethyl)amine, Ln = Gd for 1, Tb for 2 and Dy for 3, respectively) and [Ni2DyL2]ClO4·MTBE·0.65H2O (4, MTBE = methyl tert-butyl ether) have been synthesized by diffusion of methyl tert-butyl ether vapor into the reaction solution. The X-ray analyses demonstrated that the GdIII ion in 1 exhibits rare seven-coordination, the TbIII and DyIII ions in 2–4 display unusual six-coordination, and two NiII ions and one LnIII ion are bridged by six phenolato atoms to form linear Ni–Ln–Ni heterotrinuclear complexes for 1–4. All complexes exhibit weak ferromagnetic interactions between NiII and LnIII ions. Alternating current susceptibility measurements demonstrated that compounds 3 and 4 behave as single-molecule magnets with the effective energy barriers of 14.17 and 11.13 K under zero direct current field. They are rare single-molecule magnets containing six-coordinate DyIII ions.