Understanding structure does not always explain reactivity: a phosphinoamide anion reacts as an iminophosphide anion.

The aminophosphine C(6)H(4)(o-CN)NHPPh(2), 1, containing an electron-withdrawing nitrile group, was prepared from the lithiation of 2-aminobenzonitrile followed by addition of Ph(2)PCl. Lithiation of 1 using (n)BuLi affords the anion [Ph(2)PN(Li)C(6)H(4)(o-CN)(thf)](2), 2. Compound 2 reacts with Ph(2)PCl or MeI to afford C(6)H(4)(o-CN)N=PPh(2)-PPh(2), 3, and [C(6)H(4)(o-CN)N=PPh(2)(CH(3))(LiI)(C(2)H(5)O)](2), 4, respectively. In these products new P-P and P-C bonds have been formed rather than N-P and N-C bonds. The structures of 1-4 have been determined by single-crystal X-ray diffraction analysis, and the synthetic results are discussed in terms of the structural data and NMR spectroscopic studies.