Stabilizing the Homopolycation (I 4 ) 2+ with a Hexasulfate in (I 4 )[S 6 O 19 ] and a Borosulfate in (I 4 )[B(S 2 O 7 ) 2 ] 2 .

The reaction of elemental iodine and SO 3 in a sealed glass ampoule yielded a turquoise-colored solution. At temperatures below 7 °C, deep red crystals of (I 4 )[S 6 O 19 ] grow. With the addition of B 2 O 3 and pyridine-SO 3 complex red crystals of (I 4 )[B(S 2 O 7 ) 2 ] 2 can be obtained after heating the mixture to 120 °C. The combination of an (I 4 ) 2+ cation with oxoanions has previously not been observed. Both anions have a significant but different influence on the structural properties of the (I 4 ) 2+ cation.