Ethylene polymerization and ethylene/styrene copolymerization with secondary phosphine-pendant and phosphide-pendant complexes of Zr and Hf

Abstract

Ethylene and styrene polymerizations and ethylene/styrene copolymerization have been examined with a catalytic system obtained by a combination of zirconium or hafnium complexes bearing a secondary phosphine-pendant cyclopentadienyl ligand { η 5 -C 5 H 4 (CH 2 ) 2 P(H)R} (R = 2,4,6-trimethylphenyl (Mes), 2,4,6-tri(i-propyl)phenyl (Tip)) or a phosphide-pendant cyclopentadienyl ligand { η 5 -C 5 H 4 (CH 2 ) 2 PR- κP } with modified methylaluminoxane (MMAO) or a mixture of methylaluminoxane (MAO) and tri-i-butylaluminium (TIBA) as a cocatalyst. These systems show moderate activity in ethylene polymerization (8–316 g mmol −1 h −1 ) but show inactivity in styrene polymerization. In ethylene/styrene copolymerization, these systems afford ethylene/styrene copolymers with a relatively high styrene content (35–87%). The catalytic systems obtained by a combination of zirconium or hafnium complexes bearing a secondary phosphine-pendant cyclopentadienyl ligand or a phosphide-pendant cyclopentadienyl ligand with a cocatalyst show moderate activity in ethylene polymerization but show inactivity in styrene polymerization. In ethylene/styrene copolymerization, these systems afford ethylene/styrene copolymers with a high styrene content.