Stable palladium(O), palladium(II), and platinum(II) complexes containing a new, multifunctional and hemilabile phosphino-imino-pyridyl ligand: Synthesis, characterization, and reactivity

The new, multifunctional, hemilabile phosphorus-bis(nitrogen) ligand N-(2-(diphenylphosphino)benzylidene)(2-(2-pyridyl)ethyl)amine PNN, containing phosphine, imine, and pyridyl donor groups and alkyl-, allyl-, and acylpalladium complexes, methylplatinum complexes, and a zerovalent palladium complex containing PNN have been synthesized and characterized with H-1- C-13-, P-31-, and N-15-NMR. PNN commonly coordinates in a terdentate fashion, resulting in ionic complexes of the type [(PNN)M(II)(R)]Y (M = Pd, Pt, R = CH3, Y = Cl, CF3SO3; M = Pd, R = C(O)CH3, Y = CF3SO3; M = Pd, R = eta(1)-CH2C(H)=CH2, Y = Cl, CF3SO3). Bidentate coordination of PNN is observed for [(PNN)Pd-II(eta(3)-(CH3)(2)CC(CH3)C(CH3)(2))]Cl and surprisingly also for neutral (PNN)Pd-II(C(O)CH3)(Cl). An unprecedented zerovalent palladium complex (PNN)Pd-0 has been isolated, which is stabilized by PNN only. Preliminary results show that palladium complexes of PNN are very active in allylic alkylation reactions.