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

The trans-configured square-planar palladium complexes [Pd(OAc)2(LNtBu)2] (1), [Pd(OAc)2(?2-LN?NtBu)] (2), [Pd(OAc)2(LNPh)2] (3), and [Pd(OAc)2(?2-LN?NPh)] (4), were synthesized by treating palladium acetate with the amines NHtBuCH2-2,4,6-Me3C6H2 (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-CH2-2,4,6-Me3C6H-CH2-2,4,6-Me3C6H-CH2-NHPh (LN?NPh). The single-crystal x-ray structure anal. 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 Me substituents. All complexes are found to catalyze Suzuki cross-coupling reactions of deactivated and even sterically hindered arene substrates. [on SciFinder(R)]