What is the correct IUPAC name of K2[Ni(CN)4] is Potassium tetracyanonickelate(II) OR Potassium tetracyanidonickelate(II) ?
Potassium tetracyanonickelate(II) is correct.
For anionic ligands, with names ending in -ide (cyanide), '-ide' is changed to '-o' (cyano).
For anionic ligands, with names ending in -ide (cyanide), '-ide' is changed to '-o' (cyano).