Tetra-cationic imidazoliumyl-substituted phosphorus–sulfur heterocycles from a cationic organophosphorus sulfide

Abstract

The reaction of imidazoliumyl-substituted P^(III) cations of type [L^(R,Me)PCl₂]⁺ (3a,b⁺; L^R,Me = imidazolium-2-yl a: R = Me; b: R = iPr) with (Me₃Si)₂S leads to the formation of tetra-cationic, eight-membered phosphorus sulfur heterocycles [L^(R,Me)PS]₄⁴⁺ (9a,b⁴⁺), which can be explained by the tetramerization of the intermediately formed cationic phosphorus monosulfide [L^(R,Me)PS]⁺ (8a,b⁺). The P₄S₄ ring adopts a crown conformation as observed for cyclo-S₈. The Lewis base DMAP (4-dimethylaminopyridine) initiates a deoligomerization- and dismutation reaction of 9a,b⁴⁺ to give P^(I) centered cation [L^(R,Me)₂P]⁺ (12a,b⁺) and phosphorus disulfide [(DMAP)₂PS₂]⁺ (14⁺).