A Series of Lanthanide Selenidogermanates: The First Coexistence of Three Types of Selenidogermanate Units in the Same Architecture.

A series of lanthanide selenidogermanates, (H2peha)[Ln2(μ-OH)2(tepa)2Cl2]{[Ln2(μ-OH)2(tepa)2Cl]2(μ-Ge2Se6)}[Ge2Se6]Cl2 [Ln = Y (1a) and Er (1b); peha = pentaethylenexamine, tepa = tetraethylenepentamine], [Sm2(μ-OH)2(tepa)2(μ-Ge2Se6)]n (2), [Ho2(μ-OH)2(tepa)2(μ-Ge2Se6)]n (3), and [Ce4(tepa)4(μ-GeSe4)(μ-GeSe5)(μ-Ge2Se6)]n (4), were made under solvothermal conditions. Compounds 1a and 1b contain a protonated H2peha2+ ion, the complex cation [Ln2(μ-OH)2(tepa)2Cl2]2+, a [Ge2Se6]4- anion, free Cl- ions, and a {[Ln2(μ-OH)2(tepa)2Cl]2(μ-Ge2Se6)}2+ cation constructed by two unsaturated [Ln2(μ-OH)2(tepa)2Cl]3+ groups connecting via the trans terminal Se atoms of the [Ge2Se6]4- anion, which provides the first example of an organic decorated lanthanide selenidogermanate cation. Both compounds 2 and 3 contain one-dimensional chains [Ln2(μ-OH)2(tepa)2(μ-Ge2Se6)]n constructed by a combination of unsaturated complex cations [Ln2(μ-OH)2(tepa)2]4+ and [Ge2Se6]4- anions, but their stacking patterns of neutral chains are different. Compound 4 contains one-dimensional chain [Ce4(tepa)4(μ-GeSe4)(μ-GeSe5)(μ-Ge2Se6)]n, where three different selenidogermanate units acting as bridging ligands connect unsaturated [Ce(tepa)]3+ ions. Compound 4 represents the first example of the coexistence of three different selenidogermanate anions in the same architecture. Their optical properties are studied, and the magnetic properties of compounds 1b and 2-4 are also investigated.