Binuclear Homoleptic Manganese(III,III) and Manganese(IV,III) Complexes with DeprotonatedD-Mannose from Aqueous Solution

Just a “reducing” sugar—namely, D-mannose—is a starting material in the synthesis of a mixed-valence complex of manganese in the oxidation states +III and +IV. Ba2[MnIIIMnIV(β-D-ManfH−5)2]Cl⋅14 H2O (Manf=mannofuranose; the structure of the anion is shown on the right) is prepared in aqueous solution by oxidation of an analogous Mn2III complex with oxygen. In neutral solutions the MnIIIMnIV binuclear complex is formed by disproportionation of the Mn2III precursor.