Synthesis and structural characterization of Pd(II) complexes containing 2,6-bis[(dimethylamino)methyl]-4-methylphenolate ligand

Treatment of 2,6-bis[(dimethylamino)methyl]-4-methylphenol (1) with [Pd(PhCN)2Cl2] in a 1:1 molar ratio gives the mononuclear Pd(II) complex [PdCl2(OC6H2(CH2NMe2)-2-Me-4-(CH2NHMe2)-6)] (2) containing one ligand with an ammonium hydrogen atom, which forms a bifurcated hydrogen bonding to the phenoxy oxygen and the chlorine atoms, as shown by the single crystal X-ray diffraction study. The reaction between the lithium salt of 1 and [Pd(COD)Cl2] gives the mononuclear Pd(II) complex [Pd(OC6H2(CH2NMe2)2-2,6-Me-4)2] (3). The X-ray structure of 3 showed the presence of two ligands coordinated to one palladium metal center in a trans fashion with two dangling dimethylamine groups. The yield of the complex 3 was improved by carrying out the reaction between [Pd(OAc)2] and 1 in acetone. The solid state structures of the complexes 2 and 3 were confirmed by 1H, 13C, HETCOR NMR, IR and elemental analysis methods. The 1H NMR spectra of 2 and 3 showed two different chemical shifts corresponding to the coordinated and uncoordinated amine groups of the ligand. No decoalescence of signals for the chelate ring puckering process was observed in variable-temperature NMR spectra.