Electron Transfer in the Cs⊂{Mn 4 Fe 4 } Cubic Switch: a Soluble Molecular Model of the MnFe Prussian-Blue Analogues
Résumé
A mixed-valence {MnII3 MnIII FeII2 FeIII2} cyanidebridged molecular cube hosting a caesium cation, Cs⊂ - {Mn4Fe4}, was synthesized and structurally characterized by X-ray diffraction. Cyclic-voltammetry measurements show that its electronic state can be switched between five different redox states, which results in a remarkable lectrochromic effect. Magnetic measurements on fresh samples point to the occurrence of a spin-state change near room temperature, which could be ascribed to a metal-to-metal electron transfer converting the {FeII-CN-MnIII} pair into a {FeIII-CN-MnII} pair. This feature was only previously observed in the polymeric MnFe Prussian-blue analogues (PBAs). Moreover, this novel switchable molecule proved to be soluble and stable in organic solvents, paving the way for its integration into advanced materials.