BOND-BREAKING ENERGIES FOR 2,2'-DICHLORODIETHYL SULFIDE (SULFUR MUSTARD) IN MEDIA OF DIFFERENT DIELECTRIC-CONSTANTS

The energies required to homolytically break the S-C, C-C, and C-Cl bo nds in sulfur mustard, as well as the C-Cl bond heterolytically, are c omputed through a combined HF/6-31G and MP2/6-31G* treatment. The eff ects of media of different dielectric constants epsilon are taken into account by means of the Onsager reaction field model. The homolytic b ond-breaking energies decrease slightly as epsilon increases from 1.00 to 5.91 but then remain nearly constant to epsilon = 78.46. The energ y required for heterolytic C-Cl cleavage is more affected by epsilon a nd also decreases rapidly as epsilon becomes larger.