Solvothermal synthesis, crystal structures and properties of three new thiogermanates: the only example of the thiogermanate anion [Ge2S6]4− as a bridging ligand to a lanthanide complex ion

Abstract

Three new thiogermanates, (trenH₂)₂[Ge₂S₆] (1, tren = tris(2-aminoethyl)amine), [Eu(dien)₃]₂[Ge₂S₆]Cl₂ (2, dien = diethylenetriamine) and [Y₂(tepa)₂(μ-OH)₂(μ-Ge₂S₆)](tepa)_0.5·H₂O (3, tepa = tetraethylenepent-amine), were solvothermally synthesized and characterized. Both 1 and 2 are composed of discrete [Ge₂S₆]⁴⁻ anions, while 3 contains a bridging [Ge₂S₆]⁴⁻ anion as a μ₂-ligand with trans terminal S atoms linking [Y₂(OH)₂(tepa)₂]⁴⁺ groups, which is the only example of germanium chalcogenide anions acting as bridging ligands to a lanthanide complex ion. The optical absorption spectra indicate that they are wide band-gap semiconductors and their thermal stabilities have been investigated by thermogravimetric analyses (TGA).