P(CH2CH2Py)nPh3-n (Py = 2-Pyridyl; n = 1, 2, 3) as Chelating and as Binucleating Ligands for Palladium

Several neutral palladium(II) complexes of the type [PdRCl(PN n )] with the ligands P(CH 2 CH 2 Py)Ph 2 (PN), P(CH 2 CH 2 Py) 2 Ph (PN 2 ), and P(CH 2 CH 2 Py) 3 (PN 3 ) have been prepared by reacting the corresponding phosphines with [Pd 2 (μ-Cl) 2 R 2 (tht) 2 ] (R = C 6 Cl 2 F 3, C 6 F 5; tht = tetrahydrothiophene). In all these complexes, the ligands act as bidentate P,N-chelating ligands. Abstraction of the chloride with AgBF 4 leads to the formation of the dimeric compounds [Pd 2 R 2 (PN 2 ) 2 ](BF 4 ) 2 and [Pd 2 R 2 (PN 3 ) 2 ](BF 4 ) 2, in which the PN n ligands act as P,N-chelating and P,N-bridging ligands. The bridges are labile, and exchange experiments on mixtures of the complexes with different R groups show the equilibrium in solution between the dimeric “pure” complexes and the mixed complexes [Pd 2 (C 6 F 5 )(C 6 Cl 2 F 3 )(PN n ) 2 ] 2+ . The structure of the complex [Pd 2 (C 6 Cl 2 F 3 ) 2 {P(CH 2 CH 2 Py) 2 Ph} 2 ](BF 4 ) 2 has been studied by X-ray diffraction.