Transition metal acetylides and alkynyls

Those complexes which have a —C CR system o-bonded to a metal atom are called acetylide or alkynyl complexes. They may be classified according to the other ligands wUch may be attached to the metal. 

Differences between cyanide and acetylide complexes arise from the instability of the acetylide ligand to hydrolysis. The alkynyl anions are strong bases, and anhydrous solvents such as liquid ammonia must be used in the preparation of many of their complexes. Metal thiocyanates, 

Many complex acetylides are explosive and, as would be expected, the more labile ones are readily hydrolysed. The complexes with silver and gold in particular are sensitive to li t. Some other reactions of the complexes are reduction, 

The acetylide ligand differs from cyanide in forming the cobalt complex M4[Co(C=CR)6] and the tetraco-ordinated manganese(II) complex anion [Mn(C CR)4]. Further, whereas complex cyanides of copper [Cu(CN)J-( - ), where x = 2, 3 or 4, are known, the corresponding complex acet de where n = 4 is unknown. 

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