Stabilizing the Homopolycation (I4)2+ with a Hexasulfate in (I4)[S6O19] and a Borosulfate in (I4)[B(S2O7)2]2

The reaction of elemental iodine and SO3 in a sealed glass ampoule yielded a turquoise‐colored solution. At temperatures below 7 °C, deep red crystals of (I4)[S6O19] grow. With the addition of B2O3 and pyridine‐SO3 complex red crystals of (I4)[B(S2O7)2]2 can be obtained after heating the mixture to 120 °C. The combination of an (I4)2+ cation with oxoanions has previously not been observed. Both anions have a significant but different influence on the structural properties of the (I4)2+ cation. The (I4)2+ cation has been stabilized by a hexasulfate and a borosulfate anion in the compounds (I4)[S6O19] and (I4)[B(S2O7)2]2. Both occur as red crystals and can only be achieved from reactions with SO3. While the cation‐anion interactions have strong influence on the structure of hexasulfate anion, the severe coordination of multiple borosulfate anions causes significant changes in the cation geometry.