Reaction Pathway for the Formation of Binuclear Samarocene Hydride from Monomeric Alkyl Samarocene Derivative and the Effective Catalysis of Samarocene Hydride for the Block Copolymerization of Ethylene with Polar Monomers

Abstract

The X-ray analysis of Me 2 Si(C 5 H 3 -3-Me 3 -Si) 2 SmCH(Me 3 Si) 2 (THF) (1) revealed a monomeric structure, while the hydrogenated complex, [Me 2 Si(C 5 H 3 -3-Me 3 Si) 2 SmH(THF)] 2 (2), exhibits binuclear µ-H structure to indicate that Me 2 SiCp′ 2 M f M(µ-Me 2 SiCp′ 2 ) 2 M rearrangement of the η 5 -η 5 ligation occurs during the hydrogenation. The resulting samarocene hydride 2 exhibits high activity as an initiator for the block copolymerization of ethylene with polar monomers such as methyl methacrylate and -caprolactone.

Katalysatoren für die lebende Insertionspolymerisation von Alkenen: mit Ziegler-Natta-Chemie zu neuartigen Polyolefin-Architekturen

“…[48] Die strukturell verwandten Komplexe 5 und 6 (Abbildung 2) wurden zu den ersten kontrollierten Blockcopolymerisationen von 1-Hexen und 1-Penten mit MMA und CL eingesetzt. [48] Die strukturell verwandten Komplexe 5 und 6 (Abbildung 2) wurden zu den ersten kontrollierten Blockcopolymerisationen von 1-Hexen und 1-Penten mit MMA und CL eingesetzt.…”

Synthesis of New Silicon‐linked Lanthanocene Complexes and Their High Catalytic Activity for Methyl Methacrylate Polymerization with Nanometric Sodium Hydride as Co‐catalyst

“…It may be up to the fact that the introduction of the bridge between two cyclopentadienyl rings can provide a more open coordination sphere for the metal center, which can increase the rate of monomer insertion into Ln-H bonds. 7,22 When the nanometric sodium hydride was used as the co-catalyst of the complex [Me 2 Si(C 5 H 3 CMe 2 -C 6 H 5 ) 2 ErCl] 2 , the effects of such factors as variation in the molar ratio of MMA/Ln and co-catalyst/Ln and temperature of polymerization were studied. The result is presented in Table 3.…”

Developments of rare earth metal catalysts for olefin polymerization

“…A chiral, C 2 -symmetric ansa-metallocene complex of yttrium, [rac-Me 2 Si(C 5 H 2-SiMe 3 -2-Bu t -4) 2 YH] 2 (15), polymerizes propylene, 1-butene, 1-pentene, and 1-hexene slowly over a period of several days at 25°C to afford isotactic polymers with modest molecular weight [11]. Hydrogenation of a similar samarium complex, rac- 16), in which the linked Cp ligands are bridging between two samarium atoms [26]. The complex 16 shows moderate activity for ethylene polymerization and for copolymerization of ethylene with polar monomers.…”