Stable Tetraaryldiphosphine Radical Cation and Dication

Salts containing tetraaryldiphosphine radical cation 1•+ and dication 12+ have been isolated and structurally characterized. Radical 1•+ has a relaxed pyramidal geometry, while dication 12+ prefers a planar, olefin-like geometry with a two-electron π bond. The alteration of the geometries of the tetraaryldiphosphine upon oxidation is rationalized by the nature of the bonding. The EPR spectrum showed that the spin density of radical 1•+ is mainly localized on phosphorus atoms, which is supported by theoretical calculation.