Monoanionic iminophosphonamide ligands have a N-P-N linkage and undergo four-membered ring N,N-ligand formation when treated with aluminum compounds. The reaction of LLi (L = [Ph(2)P(NSiMe(3))(2)]) with equivalent amounts of AlCl(3) and AlMeCl(2) in toluene afforded LAlCl(2) (3) and LAlClMe (4), respectively. L(2)AlH (5), LAlEt(2) (6), and LAl(NMe(2))(2) (7) respectively were prepared by the reaction of LH with AlH(3) x NMe(3), AlEt(3), and Al(NMe(2))(3) in n-hexane. Subsequently compounds 3-7 were characterized by elemental analysis, (1)H, (13)C, and (31)P NMR spectroscopy and X-ray crystallographic studies (for 3, 4, 5, and 7).