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

The preparation and structural characterization of [NEt3 Me]2 [SCl6 ] is described, which is the first example of a [SCl6 ]2- dianion and of a halosulfate anion of the type [Sx Xy ]z- in general. This dianion belongs to the group of 14-valence electron AB6 E systems and forms an octahedral structure in the solid-state. Interestingly, co-crystallization with CH2 Cl2 affords [NEt3 Me]2 [SCl6 ]⋅4 CH2 Cl2 containing [SCl6 ]2- dianions with C4v 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 CH2 Cl2 . At elevated temperatures, [NEt3 Me]2 [SCl6 ] decomposes to various sulfur chlorine compounds as shown by Raman spectroscopy. Cooling back to room temperature results in the selective formation of [NEt3 Me]2 [SCl6 ] which is comparable to the well-studied SCl4 .