The X-ray Structures of 2-and 3-Sulfolene and Two Halogenated Derivatives

The structures of the isomeric 2,5-dihydrothiophene 1,1-dioxide [orthorhombic, a=11.340(2), b=7.0887(15), c= 6.2811(13) A, space group Pnma] and 2,3-dihydrothiophene 1,1-dioxide [orthorhombic, a = 6.3903(13), b = 7.2783(16), c = 11.075(2) A, 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) A, b = 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) A, 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. [GRAPHICS] .

Automated summary

This paper reports the crystal structures of 2,5-dihydrothiophene 1,1-dioxide and 2,3-dihydrothiophene 1,1-dioxide, which show perfectly planar rings with expected bond lengths and angles. In contrast, the halogenated derivatives 3,3,4,4-tetrachlorotetrahydrothiophene 1,1-dioxide and 2,3-dibromotetrahydrothiophene 1,1-dioxide exhibit twisted conformations. The degree of planarity is compared with similar 5-membered ring cyclic sulfones, and the C-H...O hydrogen bonding patterns are discussed.