Square-planar mesitylenido(triphenylphosphane)nickel(II) complexes containing bidendate N,O-ligands: Changes in catalytic efficiency upon small alterations in the ligand backbone

► Eight nickel(II) complexes were synthesised and used as catalysts for polymerisation. ► Three new N,O-chelate ligands were coordinated to different Ni precursor complexes. ► All ligand and three corresponding complex structures were determined. ► The catalytic activity for the copolymerisation of ethene and CO was investigated. ► Possible mechanistic explanations for the catalytic behaviour are discussed.