(4-Aminophenyl)(4'-nitrophenyl) phenylphosphine oxide (6) was prepared by nucleophilic aromatic substitution of bis (4-fluoropheny1) phenylphosphine oxide to give the corresponding dinitro compound, followed by selective mono-reduction. The X-ray crystal structure of (4-aminophenylldiphenylphosphine oxide (la), along with those of mono-, di-, and trihydroxy triphenylphosphine oxides lb, 2b, and 3b, exhibit extensive intermolecular ...