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.