Abstract The structures of the isomeric 2,5-dihydrothiophene 1,1-dioxide [orthorhombic, a = 11.340(2), b = 7.0887(15), c = 6.2811(13) Å, space group Pnma] and 2,3-dihydrothiophene 1,1-dioxide [orthorhombic, a = 6.3903(13), b = 7.2783(16), c = 11.075(2) Å, space group Pnma] have been determined and show perfectly planar rings with the expected bond lengths and angles. In contrast, the halogenated derivatives 3,3,4,4-tetrachlorotetrahydrothiophene 1,1-dioxide [monoclinic, a = 11.8716(8), b = 6.5579(4), c = 11.4802(8) Å, β = 97.705(17), space group P21/c] and 2,3-dibromotetrahydrothiophene 1,1-dioxide [orthorhombic, a = 5.2502(3), b = 11.3561(6), c = 24.9802(17) Å, space group Pbca] both show twisted conformations. The degree of planarity is compared with that in the structures of comparable 5-membered ring cyclic sulfones and C–H…O hydrogen bonding patterns are discussed for all four structures.Graphical Abstract The two isomeric sulfolenes are perfectly planar while tetrachloro- and dibromo-derivatives adopt twisted structures.
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