Synthesis and reactivity of bis(diphenylphosphino)amine ligands and their application in Suzuki cross-coupling reactions

Two new bis(diphenylphosphino)amines, N,N-bis(diphenylphosphino)benzidine 1 and N,N-bis(diphenylphosphino)-3,3-dimethoxybenzidine 2 were prepared by aminolysis. Their corresponding oxides, sulfides and selenides were readily prepared by reaction with hydrogen peroxide, elemental sulfur or grey selenium, respectively. Symmetric dinuclear palladium and platinum complexes were also isolated from the reaction with [M(cod)Cl2] (M = Pd or Pt, cod = cycloocta-1,5-diene). All compounds were characterized by IR and NMR spectroscopy and elemental analysis and the structure of [(Ph2P)2N–C6H4–C6H4–N(PPh2)2] was determined by single crystal X-ray diffraction. The catalytic activity of palladium complexes in Suzuki coupling reactions was also investigated.