Catalytic reactivity of the complexes [Pd{(Ph2P)2N(tBu)-P,P´}X2], X = Cl, Br, I, in the Suzuki-Miyaura C−C coupling reaction: Probing effects of the halogeno ligand X− and the ligand's tBu group

The synthesis, as well as the spectroscopic and structural characterization of three analogous palladium(II) complexes, [Pd{(Ph2P)2N(tBu)-κ2P,P´}X2], X = Cl, Br, I, is presented. X-ray crystallography studies revealed a similar square planar PdP2X2 first coordination sphere among the three complexes. The catalytic reactivity of these complexes was tested in the Suzuki-Miyaura coupling reaction, showing that the X = Cl, Br, complexes are more active than the X = I analogue. The differences in the catalytic reactivity within this series of complexes, as well as comparisons with similar palladium(II) catalysts reported in the literature, are discussed with respect to the different electronegativity of the three halogens and the strong +I inductive effect of the ligand's tBu group.