Selective activation of metallic center in heterobinuclear cobalt and nickel complex in ethylene polymerization

Sun, Tianxu; Wang, Qi; Fan, Zhiqiang

doi:10.1016/j.polymer.2010.04.050

Cited by 17 publications

(7 citation statements)

References 36 publications

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“…They investigated the influence of catalyst compositions and polymerization parameters on polyethylene compositions and properties, and they thus prepared a wide range of polyethylene reactor blends with variable branching patterns and tailored properties. ,− The last two decades have seen the emergence of several other families of multisite catalysts that combine early and late transition-metals and include binuclear nickel complexes. ,,− Moreover, bimodal polyethylenes with tunable MWDs were obtained when ZnEt 2 was added as a chain-transfer agent to diimine nickel/zirconocene dual-site catalysts …”

Section: Homogeneous Multisite Polyolefin Catalysismentioning

confidence: 99%

From Multisite Polymerization Catalysis to Sustainable Materials and All-Polyolefin Composites

Mihan²,

2015

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Section: Homogeneous Multisite Polyolefin Catalysismentioning

confidence: 99%

From Multisite Polymerization Catalysis to Sustainable Materials and All-Polyolefin Composites

Mihan²,

2015

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“…Bridges of various structures (polymethylene, phenylene, silane, siloxane, rigid/flexible) in multinuclear metallocene and constrained geometry complex-based catalysts have been used and reported, although in the field of late transition metal catalysts, there are more scarce reports. [13][14][15][16] Based on this, there is a demand for the study of the effect of length and nature of bridge and substituents in multinuclear late transition metal catalysts. The importance of late transition metal catalysts especially Ni and Pd complexes is in regard to chain walking mechanism and their activity in the copolymerization of polar monomers and production of highly branched polyolefins and thermoplastic elastomers.…”

mentioning

confidence: 99%

Cooperative effect through different bridges in nickel catalysts for polymerization of ethylene

Khoshsefat

Dechal

Ahmadjo

et al. 2019

Applied Organom Chemis

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A series of mononuclear (M 1 and M 2 ) and dinuclear (C 1 -C 6 ) Ni α-diimine catalysts activated by modified methylaluminoxane were used in polymerization of ethylene. Catalyst C 2 bearing the optimum bulkiness showed the highest activity (1.6 × 10 6 g PE (mol Ni) −1 h −1 ) and the lowest short-chain branching (32.5/1000 C) in comparison to the dinuclear and mononuclear analogues.Although the mononuclear catalysts M 1 and M 2 polymerized ethylene to a branched amorphous polymer, the dinuclear catalysts led to different branched semicrystalline polyethylenes. Homogeneity and heterogeneity in the microstructure of the polyethylene samples was observed. Different trends for each catalyst were assigned to syn and anti stereoisomers. In addition, thermal behavior of the samples in the successive self-nucleation and annealing technique exhibited different orders and intensities from methylene sequences and lamellae thickness in respect of each stereoisomer behavior. Higher selectivity of hexyl branches obtained by catalyst C 2 showed a cooperative effect between the centers. The results also revealed that for catalysts C 5 and C 6 , selectivity of methyl branches led to very high endotherms and crystalline sequences with melting temperatures higher than that of 100% crystalline polyethylene indicating ethylene/propylene copolymer analogues. For catalysts C 3 and C 4 , more vinyl end groups were a result of the long distance between the Ni centers. Kinetic profiles of polymerization along with a computational study of the precatalysts and catalysts demonstrated that there is a direct relation between rate constant, energy interval of catalyst and precatalyst, and interaction energy of Et···methyl cationic active center (Et···MCC or π-Comp.). Based on this, narrow energy interval (activation energy) of precatalyst and catalyst leads to fast and higher activation rate (catalyst M 2 ), and strong interaction of ethylene and catalyst leads to high monomer uptake and productivity (catalyst C 2 ). Moreover, theoretical parameters including electron affinity, Mulliken charge on Ni, chemical potential and hardness, and global electrophilicity showed optimum values for C 2 .

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“…The NiCo complex 46 was synthesized by Fan's group and was compared with its monometallic cobalt and nickel counterparts in ethylene polymerization (Fig. 16) [100]. On activation with MMAO, 46 displayed only low polymerization activity of [1.64 × 10 6 g(PE) mol -1 (M) h -1 ] when compared to its mononuclear counterparts [i.e., 3.40 × 10 6 g(PE) mol -1 (Co) h -1 and 1.95 × 10 6 g(PE) mol -1 (Ni) h -1 ].…”

Section: Heterobimetallic Catalystsmentioning

confidence: 99%

Developments in compartmentalized bimetallic transition metal ethylene polymerization catalysts

Suo

Solan

et al. 2018

Coordination Chemistry Reviews

101

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Recent progress concerning the application of compartmentalized bimetallic complexes as homogeneous catalysts in ethylene polymerization is reviewed with particular regard to metal-metal combinations based on either early-(Ti, Zr, Hf and V) or late-transition metals (Fe, Co and Ni). The effect of positioning two polymerization-active metal centers in close proximity on catalytic activity, molecular weight, molecular weight distribution and levels of branching are thoroughly documented. Compartmental ligands comprising binding domains consisting of phenoxyimines, ansa-bridged cyclopentadienyl-amides, α-diimines and iminopyridines are described as is their capacity to serve as compatible binucleating supports for homobimetallic and also for the less investigated heterobimetallic counterparts. By comparison with their mononuclear analogs, any synergic properties exhibited by these binuclear catalysts represents an underlying theme to be developed where possible throughout this review.

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Selective activation of metallic center in heterobinuclear cobalt and nickel complex in ethylene polymerization

Cited by 17 publications

References 36 publications

From Multisite Polymerization Catalysis to Sustainable Materials and All-Polyolefin Composites

From Multisite Polymerization Catalysis to Sustainable Materials and All-Polyolefin Composites

Cooperative effect through different bridges in nickel catalysts for polymerization of ethylene

Developments in compartmentalized bimetallic transition metal ethylene polymerization catalysts

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