Crystal Structures, UV Spectra of Solid Iodide Anionic Water Clusters I–(H2O)1–4, and Electrochemical Reaction of I–(H2O)1–4 → I· + e–(H2O)1–4

Four iodide anionic water clusters of I–(H2O)1–4 in two supramolecular complexes of [Fe­(phen)3]­[I2(H2O)3] (1) and [Zn­(phen)3]­[I2(H2O)4.5] (2) have been determined by single-crystal X-ray diffraction analysis. The diffuse reflectance spectra for the solid iodide anionic water clusters of I–(H2O)1–4 were investigated, and their absorption bands were demonstrated by denisty functional theory calculation. The electrochemical reaction of I–(H2O)1–4 → I· + e–(H2O)1–4 with the oxidation potential of Ep = 0.61 eV was first found and reported in two aqueous solutions (1 mmol·dm–3) of 1 and 2.