Formal Valence, Charge Distribution, and Chemical Bond in a Compound with a High Oxidation State: KMnO4

V. I. Anisimov1,2, A. R. Oganov3, M. A. Mazannikova1,2, D. Y. Novoselov2,1, Dm. M. Korotin2
1Department of Theoretical Physics and Applied Mathematics, Ural Federal University, Yekaterinburg, Russia
2Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, Yekaterinburg, Russia
3Skolkovo Institute of Science and Technology, Moscow, Russia

Tóm tắt

KMnO4 has unusual formal manganese oxidation state Mn+7 that seems puzzling: the energy of creating such ion (119 eV) is much greater than the energy of chemical bonds (up to ~10 eV). We have used the Wannier functions formalism to analyze the distribution of Mn- $$3d$$ electrons and O- $$2p$$ electrons for empty electronic states in the $${\text{MnO}}_{4}^{ - }$$ complex and have found that, while formally one has $${{d}^{0}}$$ configuration for manganese ion in this compound, in reality only about one-half of the hole density described by these Wannier functions corresponding to this configuration belongs to d-electrons, while the other half is spread over surrounding oxygen atoms. This corresponds much more to Mn+7 state than to Mn+2, because the calculated total number of d‑electrons is equal to 5.25. Our analysis has also sown nearly perfect covalent type of chemical bond within the $${\text{MnO}}_{4}^{ - }$$ complex with negligible contribution of the ionic part.

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