Structural Expansion of Chalcogenido Tetrelates in Ionic Liquids by Incorporation of Sulfido Antimonate Units

Multinary chalcogenido (semi)metalate salts exhibit finely tunable optical properties based on the combination of metal and chalcogenide ions in their polyanionic substructure. Here, we present the structural expansion of chalcogenido germanate(IV) or stannate(IV) architectures with Sb III , which clearly affects the vibrational and optical absorption properties of the solid compounds. For the synthesis of the title compounds, [K 4 (H 2 O) 4 ][Ge 4 S 10 ] or [K 4 (H 2 O) 4 ][SnS 4 ] were reacted with SbCl 3 under ionothermal conditions in imidazolium‐based ionic liquids. Salt metathesis at relatively low temperatures (120 °C or 150 °C) enabled the incorporation of (formally) Sb 3+ ions into the anionic substructure of the precursors, and their modification to form (Cat) 16 [Ge 2 Sb 2 S 7 ] 6 [GeS 4 ] ( 1 ) and (Cat) 6 [Sn 10 O 4 S 20 ][Sb 3 S 4 ] 2 ( 2 a and 2 b ), wherein Cat=(C 4 C 1 C 1 Im) + ( 1 and 2 a ) or (C 4 C 1 C 2 Im) + ( 2 b ). In 1 , germanium and antimony atoms are combined to form a rare noradamantane‐type ternary molecular anion, six of which surround an {GeS 4 } unit in a highly symmetric secondary structure, and finally crystallize in a diamond‐like superstructure. In 2 , supertetrahedral oxo‐sulfido stannate clusters are generated, as known from the ionothermal treatment of the stannate precursor alone, yet, linked here into unprecedented one‐dimensional strands with {Sb 3 S 4 } units as linkers. We discuss the single‐crystal structures of these uncommon salts of ternary and quaternary chalcogenido (semi)metalate anions, as well as their Raman and UV‐visible spectra.