Dimers and trimers of diphosphenes: a wealth of cyclo-phosphanes

Various new P-based ring systems were synthesised by transferring established reaction routes from NP chemistry to the analogous PP compounds. Due to the different electronic situations of phosphorus and nitrogen with respect to s and p character of the lone pair, different reactivity of the phosphorus compounds was observed, especially with regard to the specificity of the reactions and the stability of the products. Whereas Mes*NPCl (Mes*=2,4,6-tri-tert-butylphenyl) is stable in the solid state and in solution, the formal phosphorus congener Mes*PPCl is highly reactive and could not be observed. Instead, several formal dimers and trimers of Mes*PPCl could be isolated, which constitute an intriguing variety of three- and four-membered ring systems.