[Sulfonyl-bis-(bromo-methyl-ene)]di-benzene.

The title compound, CHBrOS, crystallizes as the isomer of a diastereoisomeric pair. This structure determination was key to determining that the 1,3 elimination of bromine by tri-phenyl-phosphine occurs with inversion of the configuration at each of the two chiral carbon atoms. In the crystal, the molecules are linked by weak C-H⋯O and C-H⋯Br hydrogen bonds.