Square-planar dichloro palladium complexes with trans-configurated phosphine ligands avoiding ortho-metallation: Ligand design, complex synthesis, molecular structure and catalytic potential for Suzuki cross-coupling reactions

摘要

The square-planar palladium complexes trans-[PdCl (PPh-CH-2,4,6-CHMe)] () and trans-[PdCl (η-PPh-CH-2,4,6-CHMe-CH-2,4,6-CHMe-CH-PPh)] () have been synthesized from [PdCl (cod)] (cod = 1,5-cyclooctadiene) and the corresponding new phosphine or diphosphine ligands. The single-crystal X-ray structure analysis reveals for both complexes a arrangement of the two chlorine and of the two phosphorus atoms. In both cases, -metallation leading to palladacycles is not possible, since all positions in the benzylic rings of and are blocked by methyl substituents. Both complexes are found to catalyze Suzuki cross-coupling reactions of deactivated and even bulky arene substrates.