Six-coordinated rare earth organoarsinate complexes: Crystal structure, luminescent and magnetic properties investigation

An isostructural series of rare earth complexes has been synthesized by using the dimethylarsinate ligand. All complexes have the formula [Ln(Me2AsO2)3][H2O]8 (Ln ​= ​Sm(1), Eu(2), Gd(3), Tb(4), Dy(5), Ho(6), Er(7), Tm(8), Yb(9), Y(10)). They are the first rare earth complexes ligated by organoarsinate. Crystallographic characterizations reveal that all the compounds feature 1D chain-like arrangements, in which two rare earth ions are bounded by three dimethylarsinate ligands (syn,syn, μ2-ƞ1:ƞ1) and the rare six-coordinated rare earth ions display ideal octahedron coordination geometry. The solid state photoluminescent studies reveal that compounds 2 and 4 exhibit the characteristic emission band of the EuIII and TbIII ions respectively. Magnetic measurements indicate Gd(3) shows magnetocaloric effect (MCE) with entropy change of 24.92 ​J ​kg–1 K–1 for ΔH ​= ​0 – 7 ​T at 3 ​K. The Dy(5) and Yb(9) show field induced slow relaxation, which is rare for octahedron coordinate LnIII compounds.