MN3

Mn3 is the shorthand notation for manganese in the +3 oxidation state, written Mn3+ in chemical contexts. In most chemical reactions Mn3+ is discussed as a cation formed when manganese loses three electrons, leaving a d4 electronic configuration. In octahedral coordination, Mn3+ often adopts high-spin arrangements and can exhibit Jahn-Teller distortions due to uneven occupancy of the eg orbitals, which influences geometry and properties of its complexes and solids.

In aqueous solution Mn3+ is relatively unstable compared with Mn2+. It tends to hydrolyze and, especially at neutral or basic pH, disproportionate to Mn2+ and MnO2 (solid): 2 Mn3+ → Mn2+ + MnO2. In strongly acidic conditions Mn3+ can persist longer as a powerful oxidizing agent and is subject to reduction by various reductants.

Common manganese(III) compounds include manganese(III) oxide, Mn2O3, where manganese exists predominantly as Mn3+. Mn3+ centers also appear in a range of coordination complexes with organic and inorganic ligands, contributing distinctive colors and magnetic or catalytic properties. Mn3+ is a key oxidation state in materials science, notably in manganese oxide materials used for catalysis and energy storage, where Mn3+/Mn4+ redox couples participate in charge transfer processes.

In biology and geochemistry, Mn3+ is a transient oxidation state in manganese cycling and can be involved in catalytic centers such as those found in photosynthesis, where manganese cycles through multiple oxidation states during water splitting. See also manganese, manganese(II) oxide, manganese(IV) oxide, and Jahn-Teller effect.

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