Isolable Arylphosphinidene Chalcogenides and their Radical Anions

We report the synthesis, characterization, and reactivity of isolable arylphosphinidene chalcogenides (Ar─P═E; 2 (E = S), 3 (E = Se), 4 (E = Te)), prepared via chalcogen atom transfer from tris(dimethylamino)phosphine chalcogenides (Me2N)3P═E (E = S, Se, Te) to a phosphanorcaradiene. The compounds crystallize at ambient temperature and feature P═E double bonds, as confirmed by structural and computational studies. Compounds 2-4 undergo [4+2] cycloaddition with 2,3-dimethyl-1,3-butadiene to furnish six-membered heterocyclic products, demonstrating their π-bond reactivity. Compound 3 reacts with mesityl azide to afford a P(V) compound. Additionally, 2 and 3 are capable of oxidative cleavage of O─H and N─H bonds in H2O and NH3, respectively. Furthermore, 2-4 can be one-electron reduced to their corresponding radical anion salts, which are unprecedented radical anions of pnictinidene chalcogenides isolable in the condensed phase.