Zirconium complexes containing bidentate pyrrole ligands: Synthesis, structural characterization, and ethylene polymerization

Reactions of ZrCl4 with 2 or 3 equiv of Li[C4H3N(CH2NMe2)-2] in toluene afford ZrCl2[C4H3N(CH2 NMe2)-2]2 (1) and ZrCl[C4H3N(CH2NMe2)-2]3 (2), respectively. Compounds 1 and 2 are characterized by NMR spectroscopy and single-crystal X-ray diffraction. Compound 1 exists as a six-coordinate octahedral structure with the two NMe2 units taking trans positions, and the seven-coordinate compound 2 shows a chloride-capped octahedral structure in which three bidentate pyrrole ligands form a pseudo-propeller structure with a δλλ form. A polymerization study shows that compounds 1 and 2 exhibit moderate activity toward ethylene, with compound 2 having higher activity.