Question

Which of the following is not an ambidentate ligand?

• A. C2O42−
• B. SCN−
• C. NO2−
• D. CN−

Answer 1

Answer: (A)

C2O42−

Answer 2

An ambidentate ligand is a ligand that can bind to a central metal ion through two different donor atoms.

$C2O_4^{2-}$ (Oxalate): Oxalate is a bidentate ligand , meaning it binds through two oxygen atoms. However, both oxygen atoms are equivalent, so it is not ambidentate. It always binds through its two oxygen atoms.

$SCN^-$(Thiocyanate): Thiocyanate can bind through either the sulphur atom (thiocyanate-S) or the nitrogen atom (thiocyanate-N), making it ambidentate.

$NO_2^-$ (Nitrite): Nitrite can bind through either the nitrogen atom (nitro) or the oxygen atom (nitrate), making it ambidentate.

$CN^-$(Cyanide): Cyanide can bind through either the carbon atom (cyano) or the nitrogen atom (isocyanate), making it ambidentate. Although cyanide preferentially binds through carbon, the possibility of N-bonding makes it technically ambidentate.