JEE Main2015Chemistryd and f Block ElementsActual
The colour of K M n O 4 is due to: [where M → metal, L → ligand]
Options
- Aσ − σ * transition
- BM → L charge transfer transition
- Cd - d transition
- DL → M charge transfer transition
Correct answer
D. L → M charge transfer transition
Step-by-step solution
Charge transfer from O 2 - to empty d -orbitals of metal ion (Mn 7 + ) . The colour in KMnO 4 arises from an electronic transition. In the permanganate ion (MnO 4 − ), manganese is in the + 7 oxidation state, so it has no d electrons. Photons promote an electron from the highest energy molecular orbital to an empty d -orbital on the manganese. When a photon of light is absorbed, this charge transfer takes place from L to M .