Square-planar diacetatopalladium complexes with trans-configured secondary amine ligands that avoid orthometalation: Ligand synthesis, coordination, molecular structure and catalytic potential for Suzuki cross-coupling reactions

Article abstract of DOI:10.1002/ejic.200700518

The trans-configured square-planar palladium complexes [Pd(OAc) ₂(LNtBu)₂] (1), [Pd(OAc)₂(η²- LN∩NtBu)] (2), [Pd(OAc)₂(LNPh)₂] (3), and [Pd(OAc)₂(η²-LN∩NPh)] (4), have been synthesized by treating palladium acetate with the amines NHtBuCH₂-2,4,6-Me ₃C₆H₂ (LNtBu) or NHPhCH₂-2,4,6- Me₃C₆H₂ (LNPh) or with the diamines NHtBuCH₂-2,4,6-Me₃C₆H-CH₂-2,4,6- Me₃C₆H-CH₂-NHtBu (LN∩NtBu) or NHPh-CH ₂-2,4,6-Me₃C₆H-CH₂-2,4,6-Me ₃C₆H-CH₂-NHPh (LN∩NPh). The single-crystal X-ray structure analysis of complexes 1-3 confirms a trans arrangement of the two acetato groups and of the two nitrogen atoms. Orthometalation leading to palladacycles is impossible in all cases as the ortho positions in the benzylic rings are blocked by methyl substituents. All complexes are found to catalyze Suzuki cross-coupling reactions of deactivated and even sterically hindered arene substrates. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.