Synthesis and Reactivity of Sulfur(II) Dications Stabilized Using Monodentate Ligands

The stoichiometric 1:2:2 reaction of SCl₂, trimethylsilyl trifluoromethanesulfonate, and pyridine produced sulfur(II) dications featuring two pyridine donors. The complexes were reacted with unsaturated organic substrates, which displayed addition with carbon−carbon and carbon−nitrogen double bonds. The substitution on the para position of the ligand was varied by using electron donating, electron withdrawing, and neutral groups. The electronics at this position were determined to have a substantial effect on the outcome of the reaction. The presence of an electron donating group increased the Lewis basicity sufficiently to completely stop the reaction, whereas an electron withdrawing group decreased the reaction time. These observations are unique to the chemistry of sulfur(II) dications and main group polycations as a whole.