Ti Group Metallocene-Catalyzed Synthesis of 1-Hexene Dimers and Tetramers

Kovyazin, Pavel V.; Bikmeeva, Almira Kh.; Islamov, Denis N.; Yanybin, V. M.; Tyumkina, T. V.; Parfenova, Lyudmila V.

doi:10.3390/molecules26092775

Cited by 10 publications

(18 citation statements)

References 44 publications

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“…During these experimental studies, increases in the selectivity of dimerization when adding R 2 AlCl were detected. A similar ‘chlorine effect’ was previously demonstrated by the chemists Idemitsu Kosan [ 182 , 183 ], and later by Parfenova et al [ 184 ]. As was shown by Parfenova’s group, Zr 2 bimetallic species are also active in selective dimerization [ 185 ]; however, the use of these in situ forming species is not of interest in practice.…”

Section: Complexes Of Zrsupporting

confidence: 76%

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 Zrsupporting

confidence: 76%

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

2022

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“…We studied the catalytic effect of complexes 1a – j in the oligomerization reaction in the presence of HAlBu i 2 and the activators MMAO-12 (modified methylaluminoxane) and [Ph 3 C][B(C 6 F 5 ) 4 ]. We used di(isobutyl)alane HAlBu i 2 as a co-catalyst similar to AlBu i 3 [ 6 , 7 , 26 , 27 , 28 , 30 ] to initiate the formation of zirconocene hydrides, which act as catalytically active sites in these reactions [ 29 , 30 , 33 , 34 , 35 ]. The reactant ratios were chosen on the basis of our earlier studies [ 33 , 34 , 35 ].…”

Section: Resultsmentioning

confidence: 99%

“…We used di(isobutyl)alane HAlBu i 2 as a co-catalyst similar to AlBu i 3 [ 6 , 7 , 26 , 27 , 28 , 30 ] to initiate the formation of zirconocene hydrides, which act as catalytically active sites in these reactions [ 29 , 30 , 33 , 34 , 35 ]. The reactant ratios were chosen on the basis of our earlier studies [ 33 , 34 , 35 ]. During the reaction under the selected conditions, the conversion of 1-hexene was approximately 99% in 1–3 h in most of the experiments.…”

Section: Resultsmentioning

confidence: 99%

“…The difference between the behaviors of the complexes is primarily determined by the composition and reactivity of the intermediates. It was assumed that hydride bimetallic intermediates may act as the active sites of dimerization and oligomerization reactions [ 29 , 30 , 33 , 34 , 35 ]. Our previous NMR study of the reaction of Cp 2 ZrCl 2 or [Cp 2 ZrH 2 ] 2 with OACs showed the existence of Zr,Zr-hydride complexes, which are activated by MMAO-12 or organoboron compound ([Ph 3 C][B(C 6 F 5 ) 4 ] or B(C 6 F 5 ) 3 ), being thus converted to active species responsible for dimer formation [ 32 , 33 , 34 , 35 ].…”

Section: Resultsmentioning

confidence: 99%

“…Our interest in the structural features and reactivity of group 4B metal hydrides is due to the recent data on the alkene transformation reactions catalyzed by zirconocene dichloride Cp 2 ZrCl 2 or zirconocene dihydride [Cp 2 ZrH 2 ] 2 and OACs in the presence of aluminum- or boron-containing activators [ 32 , 33 , 34 , 35 ]. The formation of the bimetallic Zr,Zr-hydride intermediate in these systems was established, and its ability to serve as the precursor of the specific and selective catalytically active sites for alkene dimerization was demonstrated.…”

Section: Introductionmentioning

confidence: 99%

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Catalytic Properties of Zirconocene-Based Systems in 1-Hexene Oligomerization and Structure of Metal Hydride Reaction Centers

et al. 2023

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Despite large-scale investigations of homogeneous single-site metallocene catalysts and systems based on them, there are still unsolved problems related to the control of their activity and chemo- and stereoselectivity. A solution to these problems is required to develop efficient methods for the synthesis of practically useful products of alkene transformations, such as dimers, oligomers, and polymers. Here we studied the catalytic activity of structurally diverse zirconocenes (L2ZrCl2, L = Cp, C5Me5, Ind, L2 = Me2CCp2, Me2SiCp2, Me2C2Cp2, rac-Me2CInd2, rac-H4C2Ind2, BIPh(Ind)2, H4C2[THInd]2), and co-catalysts activating the system, namely HAlBui2, MMAO-12, and (Ph3C)[B(C6F5)4], at low activator/Zr ratios in a 1-hexene oligomerization reaction. The influence of catalyst structure and system composition on the alkene conversion, the type of products, and the reaction stereoselectivity were investigated. The composition of hydride intermediates formed in the L2ZrCl2–HAlBui2–activator system (L2 = ansa-Me2CCp2, Ind) was studied by NMR spectroscopy. Participation of the bis-zirconium hydride complex as the precursor of catalytically active sites of the alkene dimerization reaction was shown.

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Activation of metallocene hydride intermediates by methylaluminoxane in alkene dimerization and oligomerization

Parfenova,

Kovyazin,

Bikmeeva

et al. 2023

Reac Kinet Mech Cat

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Homogeneous catalytic systems based on metallocenes, organoaluminum compounds, and activators proved to be e cient in alkene dimerization, oligomerization, and polymerization reactions. Metal hydrides can act as highly reactive species of these catalytic systems. Despite the large number of experimental and theoretical studies in this eld, the effect of the activator on the structure and dynamics of hydride intermediates is an open question. In order to elucidate the dependence of the structure and reactivity of the bimetallic hydride intermediates formed in the systems metal complex -OAC -activator on the nature of the transition metal atom and ligand environment, we used NMR spectroscopy to study reactions of a series of L 2 MCl 2 complexes (M = Hf, Zr; L 2 = Cp 2 , CpMe 2 , ansa-(Me 2 C) 2 Cp 2 , ansa-Me 2 CInd 2 ) with HAlBu i 2 and ММАО-12 activator. As a result, M,Al-bimetallic intermediates containing [L 2 ZrH 3 ] and [(L 2 Zr) 2 H 3 ] type moieties were detected for both hafnium and zirconium complexes with cyclopentadienyl ligands. The [L 2 ZrH 3 ] type structure predominates in the system based on the ansa-linked bis-indenyl zirconium complex. The detected complexes provide associates with ММАО-12 and, hence, they can act as precursors of active sites determining the alkene dimerization and oligomerization routes.

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Ti Group Metallocene-Catalyzed Synthesis of 1-Hexene Dimers and Tetramers

Cited by 10 publications

References 44 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

Catalytic Properties of Zirconocene-Based Systems in 1-Hexene Oligomerization and Structure of Metal Hydride Reaction Centers

Activation of metallocene hydride intermediates by methylaluminoxane in alkene dimerization and oligomerization

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