Palladium complexes bearing κ2-N,N and κ3-N,N,O pendant amine bis(phenolate) ligands

The synthesis and characterization of ten new palladium(II) amine bis(phenolate) complexes is reported. Solution and single-crystal X-ray diffraction studies reveal the presence of both κ2-N,N and κ3-N,N,O binding modes in these square planar complexes. For complexes with sterically less demanding phenolate donors, addition of external acidic or basic reagents allows for the selective masking of a coordination site at Pd. Complexes bearing bulky cumyl substituents on phenolate donors exhibited unusual 1H NMR spectroscopic features that are consistent with an anagostic interaction with the palladium center. Computational analysis at the ωB97X-D/LAN2LDZ level of theory supported the assertion that such an anagostic interaction may play a role in stabilizing κ2 complexes bearing a cumyl-substituted amine bis(phenolate) ligand. X-ray crystallographic data for H21a-PdCl2, H22a-PdCl2, H1b-PdCl, H2b-PdCl, H1d-PdCl, and H1e-PdCl are reported.