Methylene Bridged P(III) and P (V) Phosphiniminato-Phosphanes: Versatile Ligands And Substituents for Metals and Metalloids

Abstract

Recent studies¹ have shown that the mono oxidized phosphanolminatophosphane Me₃SiN=PPh₂CH₂PPh₂ 1 is a versatile ligand for a variety of transition metals in high and low oxidation states. This heterodifunctional ligand may bind to metals via the “hard” (N) or the “soft”(P(III)) centres; the former favours high oxidation states and “early” transition metals, the latter, low oxidation states and “late” transition metals. Monodentate or bidentate complexation is observed and in the latter case chelation or bridging is possible. Elimination of Me₃SiCl from a metal halide or migration of Me₃Si group to a terminal oxygen atom leads to metal nitrogen sigma bond formation. To modify the basicity at nitrogen a variety of approaches have been employed. Metathetical elimination of Me₃SiX from activated halogenated aromatics leads to functionalisation at N. The R₃Sn and R₃Ge analogs of 1 have also been made by extensions of the Staudinger reaction. Reactions of 1 and its N-aromatic, N-Ge, and N-Sn analogs with a variety of metals wiil be described. In water, 1 produces the unstable parent imine which has been trapped as a coordination complex of Pd(II) and Pt(II) metals. The reactions of halides produces a variety of N substituted compounds of non metals (eg; =N-SePh) and metals (eg; =N-TiR₃) which demonstrate the important heterodifunctional character of the ligand system.