Thioaluminogermanate M(AlS2)(GeS2)4 (M = Na, Ag, Cu): Synthesis, Crystal Structures, Characterization, Ion-Exchange and Solid-State 27Al and 23Na NMR Spectroscopy

The new thioaluminogermanate Na(AlS2)(GeS2)(4) (1) was successfully synthesized by a direct combination reaction. The compound crystallizes in the monoclinic space group P2(1)/ n (no. 14) with unit cell parameters a = 6.803(3) angstrom, b = 38.207(2) angstrom, c = 6.947(4) angstrom, and beta = 119.17(3)degrees. The crystal structure is composed of a [(AlS2)(GeS2)(4)](-) 3D polyanionic network, in which Al and Ge atoms share the atomic positions and Na cations occupy the channels and voids formed by the connection of (Ge/Al)S-4 tetrahedra. The title compound shows a cation-exchange property with monovalent Ag+ and Cu+ ions at room temperature in solvent media, resulting in the formation of the isostructural compounds Ag(AlS2)(GeS2)(4) (2) and Cu(AlS2)(GeS2)(4) (3), respectively. The ion-exchange products Ag(AlS2)(GeS2)(4) (2) and Cu(AlS2)(GeS2)(4) (3) show higher air stability and narrower bandgap energies compared to those of the parent compound Na(AlS2)(GeS2)(4) (1).