Some zirconium compounds containing chelating diamido dipyrrole or tetra-amido tetra-pyrrole ligands were synthesized and used as polymerization catalyst with high polymerization activity of ethylene at 40 C and 1 bar, in presence of MAO or BðC6F5Þ3 as co-catalyst. The maximum catalytic activity reached 1100 Kg/mol bar h for ethylene polymerization by Zr2(octa-phenyl calix[4]pyrrolidine)Cl4. These results reveal that half-zirconocene like complexes including four terminal chlorine and one calix[4]pyrrolidine in middle with both p and r-interaction have the highest ethylene polymerization turnover
