Acetylene acetylide anion formation from

Finally, the peculiar formation of iodoalkynes from iodine and acetylenes with relatively low (< 25) pK values in liquid ammonia should be mentioned [121]. The most likely intermediates occurring are acetylide "anions" formed in very low concentrations from the acetylene and the base ammonia. The conversions proceed very slowly and iodinadon of the lithiated alkynes in the same solvent is undoubtedly a far superior method. 

This review deals with metal-hydrocarbon complexes under the following headings (1) the nature of the metal-olefin and -acetylene bond (2) olefin complexes (3) acetylene complexes (4) rr-allylic complexes and (5) complexes in which the ligand is not the original olefin or acetylene, but a molecule produced from it during complex formation. ir-Cyclopentadienyl complexes, formed by reaction of cyclopentadiene or its derivatives with metal salts or carbonyls (78, 217), are not discussed in this review, neither are complexes derived from aromatic systems, e.g., benzene, the cyclo-pentadienyl anion, and the cycloheptatrienyl cation (74, 78, 217), and from acetylides (169, 170), which have been reviewed elsewhere. 

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