Solvothermal syntheses of lanthanide thiogermanates displaying three new structural moieties

A series of lanthanide thiogermanates Ln(dien)32Ge2S6Cl2 Ln = Pr (Ia), Sm (Ib), Gd (Ic), Dy (Id); dien = diethylenetriamine, Er2(dien)4(μ-OH)2Ge2S6 (II) and Ho(trien)(en)GeS3(SH) (III, trien = triethylenetetramine, en = ethylenediamine) have been hydrothermally synthesized and structurally characterized. The structures of Ia–d consist of isolated Ln(dien)33+ cations, Ge2S64− anions built up from the connection of two GeS4 tetrahedra sharing a common edge and Cl− ions. II contains binuclear Er2(dien)4(μ-OH)24+ cations constructed by the linkage of Er(dien)23+ ions and –OH bridging groups, and Ge2S64− anions. III contains neutral holmium-centred complexes, where the unusual protonated tetrahedral anion GeS3(SH)3− acts as a chelating ligand to complex the Ho(en)(trien)3+ cation. A systematic investigation of six lanthanide thiogermanates and four reported compounds revealed that both the well-known lanthanide contraction and different chelating organic amines have a significant influence on the formation of lanthanide thiogermanates under solvothermal conditions. Density functional theory calculation for III has also been performed and the absorption edges of all compounds have been investigated by UV-vis spectroscopy.