Which of the following complex ions is not expected to absorb visible light ?
<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}-->
AIPMT - 2010 Pre
Open in App
Solution
[Ni(CN)4]2−
For the absorption of visible light, the presence of unpaired d-electrons is the necessity.
a) In [Ni(CN)4]2−,Niis present as Ni2+ Ni2+=[Ar]3d84s0
Therefore,
(pairing occurs because CN− is a strong field ligand).
Since in [Ni(CN)4]2−, no unpaired electron is present in d− orbitals, it does not absorb visible light.
[Cr(NH3)6]3+→Cr3+ = Have three unpaired electrons [Fe(H2O)6]2+→Fe2+ = Have four unpaired electrons [Ni(H2O)6]2+→Ni2+ = Have two unpaired electrons