Easy Synthesis of New Chiral Tridentate Schiff Bases and Their Use as [N,N,O] Ligands for Ni and Pd Complexes − Catalytic Behaviour versus Hydrogenation Reactions

Abstract

AbstractThe chiral [N,N,O] tridentate unsymmetrical Schiff bases 3−5 (aryl = phenyl, 1‐naphthyl, 2‐naphthyl) were synthesised easily in high purity and good yields. All the organic compounds were characterised by elemental analysis, mass spectrometry, IR, 1H and 13C NMR spectroscopy. Palladium(II) and nickel(II) Schiff‐base complexes were prepared as air‐stable solids. Because the [N,N,O] ligand is tridentate after deprotonation of the −OH group, the coordination of the metal ion is completely stereospecific and gives rise to only one diastereoisomer. The X‐ray crystal structures of the complexes [Ni(3)(OAc)] and [Pd(4)(OAc)] were determined. These complexes were shown to be very active catalysts (TOF up to 106 h−1) for the hydrogenation of olefins and imines under mild conditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)