The cyanide ion, ${\mathrm{CN}}^{-} \mathrm{and} {\mathrm{N}}_2$ are isoelectronic, but in contrast to ${\mathrm{CN}}^{-}, {\mathrm{N}}_2$ is chemically inert, because of

N₂ is more stable and chemically inert. This is because N₂​ has a very high bond energy because of the presence of a triple bond between the two N atoms. ${\mathrm{CN}}^{-}$also has a triple bond but the bond is polar, unlike N₂ in which there is no bond polarity. Therefore, ${\mathrm{CN}}^{-}$ is less stable and not chemically inert.