a cationic group 3 or lanthanide metal complex for coordination polymerization of olefins is disclosed . the precursor metal complex is stabilized by an anionic multidentate ancillary ligand and two monoanionic ligands . the ancillary ligand and the transition metal form a metallocycle having at least five primary atoms , counting any π - bound cyclopentadienyl group in the metallocycle as two primary atoms . olefin polymerization is exemplified .