Synthesis, structures, and magnetic properties of butterfly-shaped hexanuclear [FeIII4LnIII2] single-molecule magnets

Two new Fe(4)(III)Ln(2)(III) complexes, [Fe(4)(III)Ln(2)(III)(mu(3)-OH)(2)(mdea)(6)(NO3)(4)(H2O)(2)]center dot 4MeOH (Ln = Y (1); Dy (2)), and their diluted analogs with a Y(1.83)(III)Dy(0.17 )(III)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 Fe-III centers. Compounds 2 and 3 containing Dy(III )ions display single-molecule magnet behavior with the effective energy barrier U-eff 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 Dy-III centers in compound 2 enhance the QTM effect at 0 dc field, which can be suppressed by performing a magnetic dilution.

Automated summary

Two new hexanuclear [Fe(4)(III)Ln(2)(III)] complexes with unique centrosymmetric topology were synthesized and characterized. The compounds containing Dy(III) ions displayed single-molecule magnet behavior.