trans-Spanning ferrocene amidodiphosphine ligand: Synthesis, palladium complexes and catalytic use in Suzuki-Miyaura cross-coupling

Amide coupling between [2-(diphenylphosphino)phenyl]methylamine and 1'-(diphenylphosphino)ferrocene- 1-carboxylic acid (Hdpf) afforded a novel diphosphine-amide, 1-{N-[(2-(diphenylphosphino) phenyl)methyl]carbamoyl}-10-(diphenylphosphino) ferrocene (1), which was subsequently studied as a ligand for palladium(II) complexes. Depending on the metal precursor, the following complexes were isolated: [PdCl2(1-kappa P-2, P')] (2), [PdCl(Me)(1-kappa P-2,P')] (3), [(mu-1){PdCl2(PBu3)}(2)] (4) and [(mu-1){PdCl(LNC)}(2)] (L-NC = 2-[(dimethylamino-kappa N)methyl]phenyl-kappa C-1), featuring this ligand either as a trans-chelating or as a P,P'-bridging donor. The crystal structure of 2.1.25CH(2)Cl(2) was established by X-ray crystallography, corroborating that 1 coordinates as a trans-spanning diphosphine without any significant distortion to the coordination sphere. Complex 2 together with a catalyst prepared in situ from 1 and palladium(II) acetate were tested in Suzuki-Miyaura reaction of aryl bromides with phenylboronic acid in dioxane. (C) 2009 Elsevier B.V. All rights reserved.