Structures and magnetic properties of two series of phenoxo-O bridged Ln2 compounds: Two Gd2 compounds displaying magnetic refrigeration properties

Abstract

Two series of lanthanide dinuclear compounds, namely[Ln(hfac)2L]2 (LnIII=Gd (1), Ho (2) and Er (3), hfac=hexafluoroacetylacetonate, HL=2-[[(4-iodophenyl)imino]methyl]-8-hydroxyquinoline) and [Ln(tfac)2L]2 (LnIII=Gd (4) and Tm (5), tfac=trifluoroacetylacetonate), have been synthesized and characterized by elemental analysis, IR, PXRD, UV–Vis and single crystal X-ray diffraction. Single-crystal X-ray diffraction analysis shows that the two series of Ln2 compounds have very similar structures and each eight-coordinated center Ln(III) ion is in a slightly distorted dodecahedral geometry with two bidentate β-diketonate coligands and two μ2-O bridging 8-hydroxyquinoline Schiff base ligands. The magnetic study reveals that 1 and 4 display cryogenic magnetic refrigeration properties with maximum −ΔSm values of 16.41 and 18.32JK−1kg−1 at 2.0K and 7.0T, respectively.