The present invention relates to metal complexes which are composed of a transition metal and at least one polydentate ligand of the formula Ia or Ib to a process for preparing the metal complexes, to the polydentate ligands themselves and their preparation, to catalytically active compositions comprising the metal complex of the present invention, to the use of the catalytic composition of the present invention for the polymerization or copolymerization of olefins and to a process for the polymerization or copolymerization of olefins in which the catalytic composition of the present invention is used and to a polymer or a copolymer which can be prepared by the process of the present invention.