Redox-Assisted Self-Assembly of a Water-Soluble Cyanido-Bridged Mixed Valence {Co III /Fe II } 2 Square.

The facile redox-assisted assembly of a water-soluble, extremely robust, cyanide-bridged mixed-valence [{CoIII {(Me)2 (μ-ET)cyclen}}2 {(μ-NC)2 FeII (CN)4 }2 ]2- square is reported. The preparation process involved the use of the enhanced lability of inert CoIII synthons triggered by outer-sphere redox processes. Characterization of the final compounds has been carried out by NMR, UV/Vis, electrochemistry, and ICP analyses. DFT calculations have been conducted to optimize a structure that has the same hydrodynamic radius as that obtained from DOSY experiments. The new compound is extremely robust, surviving in aqueous solution within the 0-12 pH range for months. The species shows a high affinity for both protons and hydroxo ions in aqueous medium.