The extended σ*-Lewis acidity of catena-tetraphosphorus dication, [(C6H5)2P(C6H4)P]22.

The salt [(C6H5)2P(C6H4)P]2[O3SCF3]2 which was synthesized via reductive P-P coupling of C6H4(PPh2)(PCl2), exhibits Lewis acidity derived from the σ*-orbitals of the central PP bond. This was evidenced by the Guttmann-Beckett test, the isolation of [(C6H5)2P(C6H4)P]2Br[O3SCF3] where bromide is associated with the P-P bond, and supported by computational studies.