The initiation of the addition of thiyl radicals at the C≡C bond by AlBr3 complexes with disulfides

The geometric and electronic structures of R-S-S-R disulfides (R =-C2H5,-C6H4-CH3, and-CH2-C6H5), their complexes with one and two AlBr3 (A) molecules, and the products of the dissociation of the S-S bond with the formation of radical complexes R-SA. and thiyl radicals R-S. were studied by the density functional theory method with the B3LYP hybrid functional. The enthalpies and Gibbs energies of S-S bond dissociation in disulfides and complexes were calculated. Complexes of A with ditolyl-and dibenzyldisulfides easily dissociated at the S-S bond, whereas diethyldisulfide formed stable complexes with A and did not dissociate. Experimentally, stilbene derivatives were obtained and studied by physicochemical methods. These compounds were prepared in the reaction of initial ditolyl-and dibenzyldisulfides with diphenylacetylene in the presence of AlBr3. Diethyldisulfides did not experience such transformations. The theoretical and experimental results are compared.