Th(H2O)(IVO3)2[IVII0.6V1.76O7(OH)]: A Mixed-Valent Iodine Compound Containing Periodate Stabilized by Crystallographically Compatible Lattice Sites

Periodate is a strong oxidant and is often reduced to IO3– or I2 under hydrothermal conditions. Here, we present a rare case of a mixed-valent iodate­(V)/periodate­(VII) compound, Th­(H2O)­(IVO3)2[IVII0.6V1.76O7(OH)], prepared with a hydrothermal method starting from periodic acid. Crystallographic results demonstrate that heptavalent iodine adopts IVIIO6 distorted octahedral geometries, which are stabilized on the crystallographically compatible crystal lattice sites of VO6 octahedra through an aliovalent substitutional disorder mechanism. X-ray photoelectron and synchrotron radiation X-ray absorption spectroscopes both quantitatively confirm the presence of mixed valent iodine oxoanions with a molar ratio (IV/IVII) of 4:1, consistent with the single crystal X-ray analysis. The crystallization of mixed-valent products with compatible lattice site can be fancily utilized for stabilizing the uncommon oxidation states of other elements in general.