Question

MnO4 - is a stronger oxidizing agent than ReO4 - . Both ions have charge-transfer (LMCT) bands; however, the charge-transfer band for ReO4 - is in the ultraviolet, whereas the corresponding band for MnO4 - is responsible for its intensely purple color. Are the relative positions of the charge-transfer absorptions consistent with the oxidizing abilities of these ions? Explain

Answer 1

Answer:

$MnO^-_4$  is a strong oxidizing agent.

Explanation:

The 5d orbitals of Re are higher in energy than 3 d orbitals of Mn. So an LMCT ligand to metal charge transfer excitation requires more energy of $ReO^-_4$.

Also, since the molecular orbitals are derived primarily from  3d orbitals of $MnO^-_4$ are lower in energy than the corresponding MO's of   $ReO^-_4$, $MnO^-_4$  is better able to accept the electrons.

So it is a better oxidizing agent.