Evidence of solubility of the acetylide ion C2(2-): syntheses and crystal structures of K2C2⋅2 NH3, Rb2C2⋅2 NH3, and Cs2C2⋅7 NH3.

Carbon anions in solution: C(2)(2-) dumbbells are well-known in solid-state compounds. The crystallization of the title compounds now shows that acetylide ions are existent in solution and therefore chemistry with small dissolved carbon anions may be within reach.