Synthesis and structural characterization of isomeric palladium(II) complexes with chiral N,O-bidentate ligands

The chiral N,O-bidentate ligands (S)-2-[(1-phenylethyl)imino]methyl-1-naphthalenol (3) and (S)-1-[(1-phenylethyl)imino]methyl-2-naphthalenol (4) give with PdCl2 in methanol in the presence of KOtBu the isomeric palladium(II) complexes 5 and 6. They were characterized by IR, NMR, and MS spectroscopy and also by single crystal X-ray diffraction. With respect to the palladium atom the isomeric complexes 5 and 6 adopt a distorted square planar trans-coordination geometry. Concerning the ligand arrangement, complex 5 has a step configuration with angles of 3.2° and 2.0° between the mean planes of the naphthalene rings in the two independent molecules, whereas complex 6 has a bowl configuration with an angle of θ = 48.1°.