Hexaphenyl carbodiphosphorane adducts of heavier group 15 element trichlorides: syntheses, properties and reactivities

Herein, we present the series of hexaphenyl carbodiphosphorane (CDPPh) adducts of heavier group 15 trichlorides ECl3 (E = P-Bi). The reaction with PCl3 yields the known salt [CDPPh−PCl2][Cl] ([1][Cl]), the heavier element trichlorides ECl3 (E = Sb (4), Bi (5)) give the neutral adducts CDPPh−ECl3 which were characterised crystallographically and spectroscopically. The reaction of CDPPh with AsCl3 does not yield CDPPh−AsCl3 (2), but in the presence of GaCl3 the corresponding salt [CDPPh−AsCl2][GaCl4] ([3][GaCl4]) is formed. DFT (density functional theory) calculations were carried out to examine the molecular frontier orbitals in 1+-5. Additional reactivity studies revealed an intramolecular electrophilic aromatic substitution (SEAr) in 1+, which represents an excellent starting point for further selective C−P bond formation reactions.