Group 4 metallocene complexes with annulated twelve-membered ring cyclopentadienyl ligands: Their synthesis, characterization and catalytic behavior in olefin polymerization

Abstract

The synthesis, characterization and olefin polymerization properties of Group 4 compounds {1,2-(CH2)(10)(C5H3)}(2) MCl(2) (M = Ti 5, Zr 6, Hf 7) containing annulated twelve-membered ring cyclopentadienyl ligands are reported. The reactions of lithiated annulated cyclopentadiene (Li[1,2-(CH2)(10)C5H3]) with MCl(4)(THF)(2) (M = Ti, Zr) or HfCl4 in tetrahydrofuran gave new metallocene products in reasonable yields. 6 and 7 have been characterized by single crystal X-ray diffraction studies. The compound 6 [7] crystallizes in the orthorhombic space group P2(1)2(1)2(1)[P2(1)2(1)2(1)], with a = 8.188(1) [8.190(5)] Angstrom, b = 11.371(1) [11.352(5)] Angstrom, c = 30.253(1) [30.177(8)] Angstrom, Z = 4 [4] and V = 2816.6(4) [2805.7] Angstrom(3). Both compounds are isostructural and adopt a distorted tetrahedron around the metal center. The steric crowding of the annulated twelve-membered ring in 6 and 7 is greater than that of the seven-membered ring in {2-Me-4,5-(CH2)(5)Cp}2ZrCl2. The catalytic behavior of the new metallocenes in propylene and ethylene polymerization has been studied in the presence of excess amount of methylaluminoxane.