Steric hindrances create a discrete linear Dy4 complex exhibiting SMM behaviour

Abstract

Two linear tetranuclear lanthanide complexes of general formula [Ln₄(L)₂(C₆H₅COO)₁₂(MeOH)₄], where HL = 2,6-bis((furan-2-ylmethylimino)methyl)-4-methylphenol, (Scheme 1) and Ln^III = Dy^III (1) and Gd^III (2), have been synthesized and characterized. The crystal structural analysis demonstrates that two Schiff-base ligands inhibit the growth of benzoate bridged 1D chains, leading to the isolation of discrete tetranuclear complexes due to their steric hindrances. Every Ln^III ion is coordinated by eight donor atoms in a distorted bicapped trigonal-prismatic arrangement. Alternating current (ac) susceptibility measurements of complex 1 reveal a frequency- and temperature-dependent out-of-phase signal under zero dc field, typical of single-molecule magnet (SMM) behaviour with an anisotropic barrier Δ_eff = 17.2 K.