Zirconium Complexes Containing Bidentate Pyrrole Ligands: Synthesis, Structural Characterization, and Ethylene Polymerization

Reactions of ZrCl 4 with 2 or 3 equiv of Li[C 4 H 3 N(CH 2 NMe 2 )-2] in toluene afford ZrCl 2 [C 4 H 3 N(CH 2 NMe 2 )-2] 2 ( 1 ) and ZrCl[C 4 H 3 N(CH 2 NMe 2 )-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 NMe 2 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.