Diiodine hexaoxide
Diiodine hexaoxide, is a chemical compound of oxygen and iodine with the chemical formula I2O6. It belongs to the class of iodine oxides, and is a mixed oxide, consisting of iodine and iodine oxidation states.
Synthesis
Reaction of periodic acid with iodic acid in sulfuric acid:The thermal decomposition of meta-periodic acid in vacuum also leads to the formation of diiodine hexoxide.
Chemical properties
Below 100 °C, diiodine hexaoxide can be stored stably in the absence of moisture. When dissolved in water, an exothermic reaction to form iodine and periodic acid takes place. When heated above 179 °C, decomposition into diiodine pentoxide can be observed, with the reaction going to completion at 197 °C:Structurally, the compound is a polymeric iodine oxide consisting of repeating I4O12, units contradicting previous sources describing it as "iodyl periodate". As a solid, the compound crystallizes in the space group P1 with the lattice constants a = 500.6 pm, b = 674.1 pm, c = 679.5 pm, α = 97.1°, β = 96.43°, γ = 105.36° with one formula unit per unit cell.