Question

The purple color of $KMn{O}_4$ is due to:

• A. ionic nature of $KMn{O}_4$.
• B. incomplete $d$-subshell.
• C. charge transfer.
• D. resonance in $Mn{O}_4^{-}$ ion.

Answer 1

Answer: (C)

The purple color in $KMn{O}_4$ arises from an electronic transition, but it is actually not a d-d transition, since the Mn in this compound has no d electrons. It arises from a charge transfer reaction within the molecule, in which photons promote an electron from the highest energy molecular orbital in one of the Mn-O bonds to an empty d orbital on the manganese.

Charge transfer from the ligand$(O_2–)$ to the metal center. This is called a ligand-to-metal charge transfer.

Hence,option C is correct.