Mixed-valence trimanganese complex made

The first known example of a trinuclear manganese complex in which the three manganese ions are in different oxidation states has been synthesized by a team of German chemists (Dalton Trans. 2006, 2169). Multinuclear manganese complexes are of interest as mimics for the tetramanganese photosystem II oxygen-evolving complex involved in plant photosynthesis. A variety of mixed-valence tri- and tetramanganese complexes containing Mn(II), Mn(III), or Mn(IV) centers are known. But generally the combination of manganese atoms is limited to two of the three oxidation states. One exception is the photosystem II complex, which has an intermediate with a Mn(II)−Mn(IV)−Mn(IV)−Mn(III) combination. Phalguni Chaudhuri and colleagues at Max Planck Institute for Bioinorganic Chemistry, M??lheim, have now synthesized the Mn(III)-Mn(II)-Mn(IV) complex, Mn₃L₄Cl, by reacting MnCl₂ with the novel ligand (L) shown.