Molecular weight control in organochromium olefin polymerization catalysis by hemilabile ligand–metal interactions
نویسندگان
چکیده
A series of Cr(III) complexes based on quinoline-cyclopentadienyl ligands with additional hemilabile side arms were prepared and used as single-site catalyst precursors for ethylene polymerization. The additional donor functions interact with the metal centers only after activation with the co-catalyst. Evidence for this comes from DFT-calculations and from the differing behavior of the complexes in ethylene polymerization. All complexes investigated show very high catalytic activity and the additional side arm minimizes chain-transfer reactions, leading to increase of molecular weights of the resulting polymers.
منابع مشابه
Synthesis and Application of Bis[1,2-(4-aryl-2-alkyl-1H- inden-1-yl)]Ethane as an Efficient`Ligand for Preparation of Olefin Polymerization Catalysts
In this study, a class of bis-1,2-(4-aryl-2-alkyl-1H- inden-1-yl) ethane was synthesized and characterized by spectroscopic methods such as 1HNMR, 13CNMR, melting point and FTIR. bis-1,2-(4-aryl-2-alkyl-1H- inden-1-yl) ethane was synthesized by the reaction of butyllithium, arylindenes and dibromoethane in a facile, one-pot strategy. It’s shown that these methods have a wide scope to afford li...
متن کاملCopolymerization of ethylene with α-olefins over highly active supported Ziegler-Natta catalyst with vanadium active component
The new highly active supported vanadium-magnesium catalyst (VMC) has been studied in α-olefin (1-butene, 1-hexene)/ ethylene copolymerization in the presence of hydrogen. Data on the effect of α-olefin/ethylene ratio in copolymerization on the content of branchings in copolymers, kinetic profile, copolymer yield, molecular weight and molecular weight distribution of copolymers have been obtain...
متن کاملDinickel Bisphenoxyiminato Complexes for the Polymerization of Ethylene and α-Olefins.
Dinuclear nickelphenoxyiminato olefin polymerization catalysts based on rigid p-terphenyl frameworks are reported. Permethylation of the central arene of the terphenyl unit and oxygen substitution of the peripheral rings ortho to the aryl-aryl linkages blocks rotation around these linkages allowing atropisomers of the ligand to be isolated. The corresponding syn and anti dinickel complexes (25-...
متن کامل"Inverse-electron-demand" ligand substitution in palladium(0)-olefin complexes.
Ligand substitution reactions are ubiquitous in transition-metal chemistry and catalysis. Investigation of ligand substitution reactions for a series of electron-rich palladium(0)-olefin complexes, (bathocuproine)Pd(nitrostyrene) reveals an unprecedented mechanism in which the metal serves as the nucleophilic partner in an "associative" substitution pathway.
متن کاملHeteroatom-assisted olefin polymerization by rare-earth metal catalysts
Heteroatom-functionalized polyolefins are of fundamental interest and practical importance. This has spurred investigations of the copolymerization of polar and nonpolar olefins. We report the first syndiospecific polymerization of a series of heteroatom-containing α-olefins and their copolymerization with ethylene catalyzed by half-sandwich rare-earth complexes. We have found that the interact...
متن کامل