A series of pyrrolyl-imines HL 1–6 was prepared by the condensation of pyrrole-2-carboxyaldehyde with different amines. The reaction of 2 equiv of pyrrolyl-imine with tetrabenzyl complexes of hafnium and zirconium M(CH 2Ph) 4 (M=Hf or Zr) gave dibenzyl complexes (L 3–6) 2M(CH 2Ph) 2, which were characterized by NMR spectroscopy and crystal structure analysis. NMR spectra of the complexes with secondary alkyl substituents at the imine nitrogen (isopropyl: 3a, 4- tert-butylcyclohexyl: 4a and 4b) suggest that rapid racemization between Δ and Λ configurations occurs in solution on the NMR time scale. The complexes with pyrrolide-imine ligands with a tertiary alkyl group such as tert-butyl ( 5a and 5b) or 1-adamantyl ( 6a and 6b) at the imine nitrogen possess cis-configured benzyl groups. Hafnium complexes 5a and 6a react with B(C 6F 5) 3 in bromobenzene-d 5 to give the corresponding cationic benzyl complexes, which exhibit high activity for ethylene polymerization ( 5a: 2242 kg-polymer/ mol-Hf h bar, 6a: 2096 kg-polymer/ mol-Hf h bar). Zirconium complexes 5b and 6b display a remarkably high ethylene polymerization activity when activated with methylaluminoxane ( 5b: 17,952 kg-polymer/mol-Zr h bar, 6b: 22,944 kg-polymer/mol-Zr h bar).