Asymmetric binuclear metallocene complexes and their application for olefin polymerization

Abstract

Asymmetric double silylene-bridged binuclear complexes [(g 5 -RC 5 H 4 )MCl 2 ] 2 [l, l-(SiMe 2 ) 2 (g 5 -t-BuC 5 H 2 )(g 5 -C 5 H 3 )] [R 5 H, M 5 Ti (1); R 5 Me, M 5 Ti (2); R 5 allyl, M 5 Ti(3); R 5 H, M 5 Zr (4); R 5 allyl, M5 Zr (6)]; and [(g 5 -C 5 H 5 )TiCl 2 ] 2 [l, l-(SiMe 2 ) 2 (g 5 -Me 3 SiC 5 H 2 )(g 5 -C 5 H 3 )] (5) were synthesized by the reaction of (g 5 -RC 5 H 4 ) TiCl 3 or (g 5 -RC 5 H 4 )ZrCl 3 ÁDME (R 5 H, allyl) with [l, l-(SiMe 2 ) 2 (g 5 -t-BuC 5 H 2 )(g 5 -C 5 H 3 )] Li 2 or [l, l-(SiMe 2 ) 2 (g 5 -Me 3 Si C 5 H 2 )(g 5 -C 5 H 3 )]Li 2 in THF, and they were all well characterized by 1 H NMR, MS, IR, and EA. When activated with methylaluminoxane (MAO), they are efficient catalysts for the polymerization of ethylene (Complex 4, 5.99 3 10 5 g-PE/molÁZrÁh) and the polymer with multipeak broaden molecular weight distribution (PD 5 Mw/Mn) was obtained (polymer sample gained by complex 3, PD 5 25.03). The copolymerization results indicate that 1-hexene could incorporate into the growing PE chain with these complexes in the presence of MAO (Complex 4, 1.07 3 10 6 g-PE/molÁZrÁh; 1-hexene content, 1.57% mol).

An Asymmetric Dinuclear Bis(ansa-Zirconocene) Complex: Synthesis and Performance in Olefin (co-)Polymerization

“…[2][3][4][5]. The most commonly reported bi-or multinuclear group 4 metal pre-catalysts for olefin polymerization are metallocenetype complexes with hydrocarbyl- [4][5][6][7][8][9][10][11][12][13][14] or silyl/silyloxy- [6,[15][16][17] bridges between their cyclopentadienyl-type (Cp) moieties (Chart 1). Such catalysts usually produce atactic poly(α-olefins) (e.g., polypropylene) because of the lack of a stereoselective coordination site.…”

Polymerization of ethylene using a series of binuclear and a mononuclear Ni (II)‐based catalysts

“…There are several structures in multinuclear catalysts containing metallocene and postmetallocene based and even combination of them . The diversity of bridge between the metal centers has given more variety to these types of catalysts which can be rigid or flexible or even counter‐ion of cocatalyst .…”

“…[16][17][18][19][20][21][22][23] There are several structures in multinuclear catalysts containing metallocene and postmetallocene based and even combination of them. [24][25][26][27][28] The diversity of bridge between the metal centers has given more variety to these types of catalysts which can be rigid or flexible or even counter-ion of cocatalyst. [29][30][31][32][33] Homogenous late transition metal catalysts considered as being one of the interesting research fields in mono and multinuclear catalyst of the olefin polymerization due to their unique reactivity patterns and unusual catalytic properties such as producing branched polyethylene (PE) without any a-olefin comonomers and chemical stability due to less oxophilic properties.…”