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(Me 2 AsO 2 ) 3 ][H 2 O] 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, μ 2 - ƞ 1 : ƞ 1 ) 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 Eu III and Tb III 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 Ln III compounds.