Controlled Synthesis of Pnicogen–Chalcogen Polycations in Ionic Liquids

Three new pnicogen–chalcogen polycations were synthesized under specific conditions in the Lewis‐acidic ionic liquids (ILs) [EMIm] X · n Al X 3 and [BMIm] X · n Al X 3 ( X = Cl, Br; [EMIm]: 1‐ethyl‐3‐methylimidazolium, [BMIm]: 1‐butyl‐3‐methylimidazolium) and crystallized as their tetrahalogenidoaluminate salts. Single‐crystal X‐ray diffraction revealed the new polycation [Bi 6 Te 4 Br 2 ] 4+ in triclinic [Bi 6 Te 4 Br 2 ](AlBr 4 ) 4 as the reaction product of bismuth, tellurium, and bismuth tribromide. Substitution of the elements with Bi 2 Te 3 yielded the heterocubane [Bi 4 Te 4 ] 4+ in tetragonal [Bi 4 Te 4 ](AlBr 4 ) 4 , which crystallizes isotypically to its known chlorine counterpart. The latter is also accessible from ILs. The interactions between cations and anions were evaluated by quantum‐chemical calculations. Bi 2 S 3 , which is insoluble in most media, readily dissolves in the employed IL and forms the new augmented heterocubane [Bi 3 S 4 AlCl] 3+ , which crystallizes with the complex anion [S(AlCl 3 ) 3 ] 2– as triclinic [Bi 3 S 4 AlCl][S(AlCl 3 ) 3 ]AlCl 4 . Quantum‐chemical calculations support the assignment of elements in this compound. The monoclinic crystal structure of [Sb 13 Se 16 ](AlCl 4 ) 6 (Al 2 Cl 7 ) contains a new member of the small family of pnicogen–chalcogen spiro ‐heterocubanes.