Reconfirmation of Solubility of C 2 2− in Liquid Ammonia: Syntheses and Crystal Structures of the Tetrahedral Acetylide Ammoniates [Zn(C 2 H) 4 ] 2− , [Cd(C 2 H) 4 ] 2− and [In(C 6 H 5 ) 3 (C 2 H)] −

The new compounds with the sum formulae [Cs([18]crown‐6)] 2 [Zn(C 2 H) 4 ] ⋅ 8NH 3 , Rb 3 [Rb([18]crown‐6)(NH 3 )][Cd(C 2 H) 4 ] 2  ⋅ {[18]crown‐6 ⋅ 2NH 3 } ⋅ NH 3 and [Cs([2.2.2]crypt)][In(C 6 H 5 ) 3 (C 2 H)] were synthesized in liquid ammonia. The anionic units show tetrahedrally coordinated central atoms with four hydrogenacetylide ligands or one C 2 H − and three C 6 H 5 − ligands. Solid state starting materials for these ligands were either A C 2 H ( A =Rb, Cs) or Cs 2 C 2 . The fact that the indium compound contains a hydrogenacetylide ligand, which was formed from Cs 2 C 2 , confirms again the equilibrium of the species C 2 H 2 , C 2 H − and C 2 2− in liquid ammonia and again proves that acetylides slowly dissolve in this medium.