A Cyclic Sulfate with a Seven-Membered Ring: 1,3,2-Dioxathiepane 2,2-Dioxide

We report the first structure of a seven-membered cyclic organosulfate, C₄H₈O₄S. The molecule has almost a local C₂ symmetry (r.m.s. deviation within molecule 1 is 0.018 Å). The two molecules in the asymmetric unit show the same conformation [r.m.s. deviation of all non-H atoms is 0.017 (7) Å]. Although the seven-membered ring is flexible in solution, the conformations of the two independent molecules are apparently not influenced by crystal-packing effects.

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