Zirconocene dichlorides as catalysts in alkene carbo- and cyclometalation by AlEt<sub>3</sub>: intermediate structures and dynamics

Parfenova, Lyudmila V.; Kovyazin, Pavel V.; Mukhamadeeva, O. V.; Ivchenko, Pavel V.; Nifant’ev, Ilya E.; Халилов, Л. М.; Джемилев, У. М.

doi:10.1039/d1dt03160k

Cited by 2 publications

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“…In the presence of α-olefin, the highly reactive species Zr12 is further transformed into a cycloalumination product [ 148 ]. The mechanism of this reaction was studied by DFT modeling, which confirmed the importance of Zr–(μ-Cl)–Al bonding for all key reaction stages [ 149 , 150 , 151 , 152 ].…”

Section: Complexes Of Zrmentioning

confidence: 89%

Transition Metal–(μ-Cl)–Aluminum Bonding in α-Olefin and Diene Chemistry

2022

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Olefin and diene transformations, catalyzed by organoaluminum-activated metal complexes, are widely used in synthetic organic chemistry and form the basis of major petrochemical processes. However, the role of M–(μ-Cl)–Al bonding, being proven for certain >C=C< functionalization reactions, remains unclear and debated for essentially more important industrial processes such as oligomerization and polymerization of α-olefins and conjugated dienes. Numerous publications indirectly point at the significance of M–(μ-Cl)–Al bonding in Ziegler–Natta and related transformations, but only a few studies contain experimental or at least theoretical evidence of the involvement of M–(μ-Cl)–Al species into catalytic cycles. In the present review, we have compiled data on the formation of M–(μ-Cl)–Al complexes (M = Ti, Zr, V, Cr, Ni), their molecular structure, and reactivity towards olefins and dienes. The possible role of similar complexes in the functionalization, oligomerization and polymerization of α-olefins and dienes is discussed in the present review through the prism of the further development of Ziegler–Natta processes and beyond.

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Section: Complexes Of Zrmentioning

confidence: 89%

Transition Metal–(μ-Cl)–Aluminum Bonding in α-Olefin and Diene Chemistry

2022

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“…Heterobimetallic adducts featuring bridging alkyl/hydride/chloride moieties are usually proposed as catalyst resting states or intermediates in these transformations. − Although several heterobimetallic adducts having hydride, methyl, or chloride bridges have been intercepted and characterized, ,,− very few studies examine systems with alkyl bridges longer than methyl or systems with inequivalent alkyl bridges − critical to olefin polymerization, CCTP, and CSP processes.…”

Section: Introductionmentioning

confidence: 99%

Solution Structure and Dynamics of Hf–Al and Hf–Zn Heterobimetallic Adducts Mimicking Relevant Intermediates in Chain Transfer Reactions

Tensi,

Moretti,

Amendola

et al. 2024

Inorg. Chem.

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H f ] [ B ( C 6 F 5 ) 4 ] ( 4 P r ) a n d [Cp iBu Cp CH2CH(Me)CH2 Hf][B(C 6 F 5 ) 4 ] (4a iBu and 4b iBu ) were synthesized from the corresponding [(Cp Pr ) 2 HfMe][B(C 6 F 5 ) 4 ] (1 Pr ) and [(Cp iBu ) 2 HfMe][B(C 6 F 5 ) 4 ] (1 iBu ) complexes via C−H activation.4a iBu , 4b iBu , and 4 Pr , mimicking a propagating M-polymeryl species (M = transition metal) with or without a β-methyl branch on the metalated chains, serve to investigate whether and how the nature of the last inserted olefin molecules changes the structure, stability, and reactivity of the corresponding heterobimetallic complexes, formed in the presence of aluminum-or zinc-alkyl chain transfer agents (CTAs), which are considered relevant intermediates in coordinative chain transfer polymerization (CCTP) and chain shuttling polymerization (CSP) technologies. NMR and DFT data indicate no major structural difference between the resulting heterobridged complexes, all characterized by the presence of multiple α-agostic interactions. On the contrary, thermodynamic and kinetic investigations, concerning the reversible formation and breaking of heterobimetallic adducts, demonstrate that isomer 4a iBu , in which the β-Me is oriented away from the reactive coordination site on Hf, but not 4b iBu , having the β-Me pointing in the opposite direction, is capable of reacting with CTAs. Quantification of kinetic rate constants highlights that the formation process is rate limiting and that the nature of the last inserted α-olefin unit modulates transalkylation kinetics. The reaction of 4a iBu , 4b iBu , and 4 Pr with diisobutylaluminum hydride (DiBAlH) allows the interception and characterization of new heterobinuclear and heterotrinuclear species, featuring both hydride and alkyl bridging moieties, which represent structural models of elusive intermediates in CCTP and CSP processes, capturing the instant when an alkyl chain has just transferred from a transition metal to a main group metal, while the two metals remain engaged in a single heterobimetallic intermediate.

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Zirconocene dichlorides as catalysts in alkene carbo- and cyclometalation by AlEt₃: intermediate structures and dynamics

Abstract: Catalytic activity and chemoselectivity of zirconocenes in the reaction of alkenes with AlEt3 were evaluated. NMR study of the reaction between L2ZrCl2 and AlEt3 showed the formation of various bimetallic intermediates.

Cited by 2 publications

References 65 publications

Transition Metal–(μ-Cl)–Aluminum Bonding in α-Olefin and Diene Chemistry

Transition Metal–(μ-Cl)–Aluminum Bonding in α-Olefin and Diene Chemistry

Solution Structure and Dynamics of Hf–Al and Hf–Zn Heterobimetallic Adducts Mimicking Relevant Intermediates in Chain Transfer Reactions

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Zirconocene dichlorides as catalysts in alkene carbo- and cyclometalation by AlEt3: intermediate structures and dynamics

Abstract: Catalytic activity and chemoselectivity of zirconocenes in the reaction of alkenes with AlEt3 were evaluated. NMR study of the reaction between L2ZrCl2 and AlEt3 showed the formation of various bimetallic intermediates.

Cited by 2 publications

References 65 publications

Transition Metal–(μ-Cl)–Aluminum Bonding in α-Olefin and Diene Chemistry

Transition Metal–(μ-Cl)–Aluminum Bonding in α-Olefin and Diene Chemistry

Solution Structure and Dynamics of Hf–Al and Hf–Zn Heterobimetallic Adducts Mimicking Relevant Intermediates in Chain Transfer Reactions

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Zirconocene dichlorides as catalysts in alkene carbo- and cyclometalation by AlEt₃: intermediate structures and dynamics