Abstract
The quaternary thioaluminogermanates Na(AlS2)(GeS2) (1) and K(AlS2)(GeS2) (2) crystallize in the tetragonal space group I4/mcm (no. 140) with unit cell parameters a = 7.4274(11) angstrom, c = 5.8560(12) angstrom for Na(AlS2)(GeS2) and a = 7.8826(2) angstrom, c = 5.8642(4) angstrom for K(AlS2)(GeS2). The crystal structure comprises of one-dimensional [(AlS2)(GeS2)](-) anionic chains with Al and Ge sharing the tetrahedral site. The alkali metal cations fill the square antiprismatic voids between chains. Both 1 and 2 are semiconductors with bandgap of around 3.6 eV and 3.5 eV, respectively.