Amido, chloro, and benzyl hafnium complexes bearing 2-(N-aryliminomethyl)pyrrole [(R-pyr)H, 1a: R=DIP=2-{N-(2,6-diisopropylphenyl)-iminomethyl}, 1b: R=XYL=2-{N-(2,6-dimethylphenyl)iminomethyl}, 1c: R=ANI=2-{N-(4-methoxyphenyl)iminomethyl}, 1d: R=TOL=2-{N-(4-methylphenyl)iminomethyl}] were prepared and characterized. The coordination modes of (R-pyr)(2)Hf(NMe2)(2) (2a-d) depend on the bulkiness of the aromatic substituent at the imine nitrogen of the ligands. In contrast, all (R-pyr)(2)HfCl2 (3a-d) have a C-2-symmetric octahedral structure. These diamido- and dichloro-bis(iminopyrrolyl)hafnium complexes, when combined with MMAO, become active catalysts for ethylene polymerization. Two types of hafnium benzyl complexes, (DIP-pyr)Hf(CH2Ph)(3) (4a) and (DIP-PYr)(2)Hf(CH2Ph)(2) (5a), were prepared by the alkane elimination reaction from reactions of Hf(CH2Ph)(4) with controlled amounts of iminopyrrole (1a). The mono(iminopyrrolyl)hafnium tribenzyl complex (4a) exhibited a high catalytic activity for I-hexene polymerization. (c) 2006 Elsevier B.V. All rights reserved.