EMn3+/Mn2+∘>ECr3+/Cr2+∘ or EFe3+/Fe2+∘ Electronic configuration of Mn3+=[Ar]3d4 Electronic configuration of Mn2+=[Ar]3d5 Electronic configuration of Cr3+=[Ar]3d3 Electronic configuration of Cr2+=[Ar]3d4 As Mn3+ from d4 configuration goes to more stable d5 configuration (Half filled), due to more exchange energy in d5 configuration.