Coordination of Olefins and N-Donor Ligands at the Fragment [2,6-Bis((diphenylphosphino)methyl)pyridine]- palladium(II). Synthesis, Structure, and Amination of the New Dicationic Complexes [Pd(PNP)(CH₂CHR)](BF₄)₂ (R = H, Ph)

Abstract

Dicationic complexes of palladium(II) containing the tridentate ligand 2,6-bis((diphenylphosphino)methyl)pyridine (PNP) of the general formula [Pd(PNP)L](BF4)2 (L = MeCN, pyridine, C2H4, CH2CHPh) have been prepared from Pd(PNP)Cl2 by addition of 2 equiv of AgBF4 in the presence of an excess of the respective ligand L in CH2Cl2. The corresponding amine complex (L = NHMe2) was obtained by substitution of the acetonitrile from [Pd(PNP)(MeCN)](BF4)2 by NHMe2 at 0 °C. The complexes were characterized by 1H, 13C, and 31P NMR spectroscopy, and the molecular structure of the styrene complex was determined by X-ray diffraction analysis. The spectral and structural parameters of the complexes are discussed in comparison to those of the recently prepared Rh(I) analogues. Nucleophilic attack of secondary amines on the coordinated olefins gave the corresponding β-aminoethyl complexes from which, upon reductive degradation, the respective ethylamines were obtained, showing selective anti-Markovnikov addition in the case of the styrene complex.