115570-71-3Relevant articles and documents
Evidence of solubility of the acetylide ion C22-: Syntheses and crystal structures of K2C2·2NH 3, Rb2C2·2NH3, and Cs 2C2·7NH3
Hamberger, Markus,Liebig, Stefan,Friedrich, Ute,Korber, Nikolaus,Ruschewitz, Uwe
, p. 13006 - 13010 (2012)
Most alkali- and alkaline-earth-metal acetylides of composition A 2IC2 (AI=Li-Cs) and (AE)IIC 2 ((AE)II=Mg-Ba) have been known since the 19th century.[1,2] Very early crystal structure investigations had already revealed that they contA In C2 2- dumbbells,[3, 4] but the complex phase behavior of these compounds was elucidated only very recently.[5] In the first half of the last century, CaC2 in particular, which is accessible from CaO and coal, attracted a lot of interest as an industrial feedstock of acetylene by hydrolysis.[6] Owing to the limited petroleum resources, this reaction has found a revival within the last years.[7] Apart from hydrolysis however, reports on further reactions of alkali- and alkaline-earthmetal acetylides are quite rare, which is surely due in part to the fact that these compounds are insoluble in common solvents.[8] However, during the synthesis of ternary copper acetylides AICuC2 with AI=K-Cs, we observed that a suspension of AI 2C2 in liquid ammonia reacts with CuI at temperatures as low as -78°C within minutes.[9] To clarify whether this reaction can be interpreted as a (low) solubility of A I 2C2 in liquid ammonia, we decided to investigate the system AI 2C2/ NH3(l) in more detAIl. The versatility of liquid ammonia to stabilize unusual mAIn-group-element clusters has been shown by several impressive examples.[10] Herein we report the crystal structures of the ammoniates K2C2·2NH3 (1), Rb2C2·2NH3 (2), and Cs2C2·7NH3 (3),[11a-c] which are the first examples of binary acetylide solvates. Additionally, the crystal structure of [Li(NH3)4]C2H (4),[11d] which contA Ins the hydrogen acetylide anion C2H-, is briefly presented.
