Tuning the Coordination Geometry and SMM Behavior of Binuclear {LnIII2} Complexes (Ln = Dy, Er) by Varying the Ligand Substitutions

Abstract

Two series of lanthanide metal complexes [Ln2(H2TEA)2(p-NH2C6H4COO)2(NO3)2] (Ln = Dy (1), Er (2)) and [Ln2(H2TEA)2(p-NO2C6H4COO)4] (Ln = Dy (3), Er (4)) have been synthesized and characterized. Different substituents on benzoate ligands lead to a change in coordination number from nine (for 1 and 2) to eight (for 3 and 4) and a modification of coordination environment, which are further accompanied by a change in SMM behavior. Magnetic susceptibility measurements reveal that for 1 and 2 using p-aminobenzoate as coligand, compound 1 containing DyIII ions displayed single-molecule magnetic (SMM) behavior with the energy barrier Ueff = 98.25 K, while compound 2 containing ErIII ions did not show any sign of slow magnetic relaxation. However, for compounds 3 and 4 using p-nitrobenzoate as coligand, only compound 4 containing ErIII ions exhibits slow relaxation of magnetization expected for a SMM.