Significant intramolecular sulfur-sulfur interactions in cis- and trans-2,3-dimethyl-5,6-dithiabicyclo-[2.1.1]hexane

Reduction of (±)-(1α, 2α, 3β, 4α, 5β)-2,3-dimethyl-5,6-dithiabicyclo[2.1.1]hexane 5-oxide (3a) and (1α, 2α, 3α, 4α, 5β)-2,3-dimethyl-5,6-dithiabicyclo[2.1.1]hexane 5-oxide (3b) gives the bis-sulfides (±)-trans-2,3-dimethyl-5,6-dithiabicyclo[2.1.1]hexane (2a) and cis-2,3-dimethyl-5,6-dithiabicyclo[2.1.1]hexane (2b), respectively. Bis-sulfides 2a and 2b, on oxidation with one equivalent of m-CPBA, give 3a and 3b, respectively, as the only products. Significant sulfur-sulfur interactions in 2a and 2b are indicated by the long-wavelength UV maxima, the lowered ionization potentials, as measured by photoelectron spectroscopy, and the lowered oxidation potentials, as found by cyclic voltammetry.