Synthesis, structures, and magnetic properties of butterfly-shaped hexanuclear [FeIII4LnIII2] single-molecule magnets†
Abstract
Two new FeIII4LnIII2 complexes, [FeIII4LnIII2(μ3-OH)2(mdea)6(NO3)4(H2O)2]·4MeOH (Ln = Y (1); Dy (2)), and their diluted analogs with a YIII1.83DyIII0.17 ratio (3) were synthesized and characterized. In the absence of carboxylate ancillary ligands, the hexanuclear cores of all three compounds possess a unique centrosymmetric chair-like topology. DC magnetic susceptibility measurements revealed the dominant antiferromagnetic interactions between FeIII centers. Compounds 2 and 3 containing DyIII ions display single-molecule magnet behavior with the effective energy barrier Ueff increasing from 39.7 K (for 2) to 101.5 K (for 3). The off-diagonal ligand field terms and the very weak magnetic interaction between DyIII centers in compound 2 enhance the QTM effect at 0 dc field, which can be suppressed by performing a magnetic dilution.