A 3+ metal complex for coordination polymerization of olefins is disclosed. The precursor metal complex is stabilized by a anionic multidentate ligand and at least two monoanionic ligands. The multidentate ligand and the transition metal form a metallocycle having at least five primary atoms, counting any .pi.-bound cyclopentadienyl group in the metallocycle as two primary atoms. Olefin polymerization is exemplified.