Syntheses and properties of palladium complexes containing phosphorus-nitrogen-phosphorus ligands with a tunable hemilabile site

A series of phosphorus-nitrogen-phosphorus (PNP) ligands of the type R-N(CH 2CH2PPh2)(2) (R = C(=O)(C6H4OMe-p), Bu-t, Ph, C6H4OMe-p) have been prepared . Their coordination chemistry to palladium(II) and palladium(0) complexes was examined using a combination of X-ray crystallography, NMR, and electro chemical techniques. The palladium(0) complexes undergo reactions with aryl iodides to give the palladium(II) complexes [Pd(Ar){R-N(CH2CH2PPh2)(2)}]I- +(-), where the rate of oxidative addition was found to be dependent on the nature of the aryl group, as well as the substitution on nitrogen.