Palladium alkyl complexes with a formazanate ligand: synthesis, structure and reactivity

Palladium(ii) complexes with a bidentate, anionic formazanate ligand are described. Attempts to prepare mono(formazanate) palladium alkyl complexes often leads to the homoleptic bis(formazanate) complex, which shows rich electrochemistry due to the redox-active nature of the ligands. Performing salt metathesis between the precursor [Pd(COD)(CH3)Cl] and the potassium salt of the ligand in the presence of tetrabutylammonium chloride yields a square planar mono(formazanate) palladate complex through coordination of chloride anion. Ligand exchange allows binding of unsaturated molecules and evaluation of the reactivity of the Pd-CH3 fragment. Using this approach, insertion reactions of CO, isocyanide and methyl acrylate into the Pd-CH3 bond are demonstrated.