The synthesis of new iron(Pi) diiminopyridine complexes and their heterogenization to give highly active ethene polymerization catalysts is described. The ligands are characterized by (HNMR)-H-1, (CNMR)-C-13 spectroscopy and GC/MS. The complexes are paramagnetic and were characterized by elemental analyses and mass spectrometry. The complexes were activated and heterogenized with a cocatalyst consisting of partially hydrolyzed trimethylaluminum (PHT) on silica gel and were used for ethene polymerization. The polymerization results and the polymer properties are presented. The influence of the catalyst structure, hydrogen and 1-hexene on the polymerization behavior is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.