A series of monoanionic, bidentate 2-anilidomethylpyridine ligands were synthesized and used to prepare bis(chelate) Zr(IV) and Hf(IV) bis(dimethylamido) complexes. All complexes were characterized by NMR spectroscopy and elemental analysis. The solution structures of the complexes were more or less fluxional, depending on the substituent on the ligands. The complexes were tested as catalysts for the polymerization of ethylene and propene, in combination with different activators. Use of (AlBu2H)-Bu-1 - methylaluminoxane as the co-catalyst resulted in the generation of catalysts producing high molecular weight polyethylenes with good activities, but yielding only stereoirregular and poorly regioregular polypropylenes. (C) 2011 Elsevier B.V. All rights reserved.