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

Three new thiogermanates, (trenH(2))(2)[Ge2S6] (1, tren tris(2-aminoethyl)amine), [Eu(dien)(3)](2)[Ge2S6]Cl-2 (2, dien = diethylenetriamine) and [Y-2(tepa)(2)(mu-OH)(2)(mu-Ge2S6)](tepa)(0.5)center dot 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 mu(2)-ligand with trans terminal S atoms linking [Y-2(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).