Molten flux synthesis, single crystal X-ray structure and ion-exchange properties of the first polythiogallate, CsGaS<inf>3</inf>

A new polythiogallate, CsGaS3, has been synthesized using molten flux of caesium polysulfide, and structurally characterized, by single crystal X-ray diffraction techniques, as possessing one-dimensional GAS3- chains, built from GaS4 tetrahedra. Cs+ ions undergo facile ion-exchange, at room temperature, with Rb+, NH4+, Me4N+ and alkaline earth and a few divalent first row transition metal ions in aqueous solution. AGaS3 (A = Cs, Rb, NH4, Me4N) compounds are, as determined from their diffuse reflectance spectra, insulators.