MnO4

MnO4 most commonly denotes the permanganate species, MnO4−, a tetrahedral oxoanion in which manganese is in the +7 oxidation state. The neutral oxide MnO4 is not a stable compound under ordinary conditions, since manganese cannot adopt an equivalent neutral +8 oxidation state in a simple oxide.

The permanganate anion has a tetrahedral geometry with Td symmetry in both solid salts and aqueous solution. Mn–O bond lengths in typical salts are around 1.58 Å. In solution, the tetrahedral arrangement is retained, though hydration influences bond characteristics.

As a strong oxidizing agent, permanganate is widely used in redox chemistry. In acidic solution, MnO4− is reduced to Mn2+ (MnO4− + 8 H+ + 5 e− → Mn2+ + 4 H2O). In basic solution, it is reduced to solid MnO2 (MnO4− + 2 H2O + 3 e− → MnO2(s) + 4 OH−). In neutral water, permanganate can gradually form MnO2 as a brown precipitate. Because of its vivid color changes—purple MnO4− turning colorless or pale pink on reduction—permanganate is a common titrant in permanganimetric analyses and an oxidant in organic synthesis and water treatment.

Commercially, permanganate salts, most notably potassium permanganate (KMnO4) and sodium permanganate, are used as oxidizers and disinfectants. They are produced industrially and sold for laboratory and environmental applications, as well as in some quantitative analyses where durable, visible indicators of redox endpoints are advantageous.

Safety notes: permanganate is a powerful oxidizer and can ignite or accelerate combustion of organic materials. Avoid contact with reducing agents and organic substances; handle solutions with appropriate precautions.