P(CH2CH2Py)(n)Ph3-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(PNn)] with the ligands P(CH2CH2Py)Ph-2 (PN), P(CH2CH2Py)(2)Ph (PN2), and P(CH2CH2Py)(3) (PN3) have been prepared by reacting the corresponding phosphines with [Pd-2(mu-Cl)(2)R-2(tht)(2)] (R = C6Cl2F3, C6F5; tht = tetrahydrothiophene). In all these complexes, the ligands act as bidentate P,N-chelating ligands. Abstraction of the chloride with AgBF4 leads to the formation of the dimeric compounds [Pd2R2(PN2)(2)](BF4)(2) and [Pd2R2(PN3)(2)](BF4)(2), in which the PNn 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(C6F5)(C6Cl2F3)(PNn)(2)](2+). The structure of the complex [Pd-2(C6Cl2F3)(2)(P(CH2CH2Py)(2)Ph)(2)](BF4)(2) has been studied by X-ray diffraction.