# Magnetic properties of potassium manganate(VII)

According to me, $$\ce{MnO4^2-}$$ is paramagnetic and $$\ce{MnO4^-}$$ is diamagnetic. On the basis of this, the corresponding potassium salts inherit these magnetic properties, i.e. $$\ce{K2MnO4}$$ is paramagnetic and $$\ce{KMnO4}$$ is diamagnetic.

However, according to my class teacher $$\ce{KMnO4}$$ is paramagnetic.

Is potassium manganate(VII) dia- or paramagnetic?

Actually it is diamagnetic but due to a phenomenon called charge transfer spectrum (CTS), oxygen transfers one electron to manganese and $$\ce{KMnO4}$$ as a whole becomes paramagnetic. This is also the reason why it shows a characteristic colour while diamagnetic complexes are colourless due to absence of d-d transitions.

• What would be the percentage of the excited state from charge transfer, in let's say a solution of KMnO4 ? Because a significant number of the molecules have to be in excited state before the bulk material gains paramagnetic properties. – S R Maiti Apr 26 at 20:37