Synthesis of a Hexachloro Sulfate(IV) Dianion Enabled by Polychloride Chemistry.

The preparation and structural characterization of [NEt 3 Me] 2 [SCl 6 ] is described, which is the first example of a [SCl 6 ] 2- dianion and of a halosulfate anion of the type [S x X y ] z- in general. This dianion belongs to the group of 14-valence electron AB 6 E systems and forms an octahedral structure in the solid-state. Interestingly, co-crystallization with CH 2 Cl 2 affords [NEt 3 Me] 2 [SCl 6 ]⋅4 CH 2 Cl 2 containing [SCl 6 ] 2- dianions with C 4v symmetry. As suggested by quantum-chemical calculations, the distortion of the structure is not caused by a stereochemically active lone pair but by enhanced hydrogen bonding interactions with CH 2 Cl 2 . At elevated temperatures, [NEt 3 Me] 2 [SCl 6 ] decomposes to various sulfur chlorine compounds as shown by Raman spectroscopy. Cooling back to room temperature results in the selective formation of [NEt 3 Me] 2 [SCl 6 ] which is comparable to the well-studied SCl 4 .