NEETChemistryCoordination CompoundsMCQ+4 / −1
Which of the following complex ions is not expected to absorb visible light?
- A[Ni(CN)4]2
- B[Cr(NH3)6]3+
- C[Fe(H2O)6]2+
- D[Ni(H2O)6]2+
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Correct answer: A
A transition metal complex absorbs visible light only if it has unpaired electrons.

Pairing occur because CN– is a strong field ligand. Thus, [Ni(CN)4]2– does not contain any unpaired electron so it does not absorb visible light.
All other in the option contains pair of electrons thus absorb visible light.
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