Complex sentence: Mn 2 + often competes with Mg 2 + in bi75385 to the unstable oxide Mn 2 O 7 and compounds of the intensely purple permanganate anion MnO 4 −, are powerful oxidizing agents.
Split into simpler sentences: Mn 2 + often competes with Mg 2 + in biological systems. Manganese compounds where manganese is in oxidation state +7, which are restricted to the unstable oxide Mn 2 O 7 and compounds of the intensely purple permanganate anion MnO 4 −, are powerful oxidizing agents.