The syntheses, structures and properties of three new lanthanoid thioarsenates: The only example of thioarsenate acting as a ligand to a lanthanide complex

摘要

Three new lanthanoid thioarsenates [Eu(en)_3(η~2- AsS_4)] (1, en = ethylenediamine), [Er(teta)(en)(η~2- AsS_4)] (2, teta = triethylenetetramine) and [La_2(tepa) _2(μ-η~1,η~3-AsS_3) _2] (3, tepa = tetraethylenepentamine) have been solvothermally synthesized and structurally characterized. In compounds 1and 2, the tetrathioarsenate [AsS_4]~(3-) anions act as η~2-AsS_4 chelating ligands to the lanthanide complexes [Eu(en)_3]~(3+)/[Er(teta)(en)]~(3+), leading to neutral molecules [Eu(en)_3(η~2-AsS_4)]/ [Er(teta)(en)(η~2-AsS_4)], whereas the [AsS _3]~(3-) anion in compound 3 acts as a μ-η~1, η~3-AsS_3 tetradentate bridging ligand to link [La(tepa)]~(3+) ions into neutral centrosymmetric [La _2(tepa)_2(μ-η~1,η~3-AsS _3)_2] moieties, where a new coordination mode of μ-η~1,η~3-AsS_3 is observed for the [AsS_3]~(3-) ligand. Compounds 1-3 are the only examples of solvothermally synthesized thioarsenates where the [AsS_4] ~(3-)/[AsS_3]~(3-) anions act as ligands in the lanthanide complex. Compound 1 exhibits a fluorescence emission at room temperature. Density functional theory calculations for compounds 2 and 3 also have been performed, and the absorption edges of compounds 1-3 have been investigated by UV-vis spectroscopy.