Synthesis, characterization and reactivity of binuclear palladium(I)bis(diphenylphosphino)amine complexes

The binuclear Pd(I) complex [Pd2(μ-dppa)2(CH3CN)2][BF4]2 (1), where dppa is the bridging diphosphine ligand bis(diphenylphosphino)amine, was prepared by the reaction of [Pd(dppa)2][BF4]2 and 12equiv. of [Pd2(dba)3]. The acetonitrile ligands in complex 1 are readily displaced by other ligands. Substitution of one or both of the acetonitrile ligands of the dimer 1 with Cl−, Br−, I−, (CN)− and PPh3 is described. 31P NMR and mass spectral data for the complexes are reported. The single crystal X-ray structures of the binuclear complexes, [Pd2(μ-dppa)2(PPh3)(THF)][BF4]2·4THF, [Pd2(μ-dppa)2(PPh3)2][BF4]2·THF·H2O and [Pd2(μ-dppa)2Cl2]·3CH3CN have been determined. Attempts to react the binuclear complex [Pd2(μ-dppa)2I2] with ligands capable of bridging the PdPd bond (CO, SO2 and HgCl2) were unsuccessful.