1
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Collins S, Linnolahti M. Cages versus Sheets: A Critical Comparison in the Size Range Expected for Methylaluminoxane (MAO). Chemphyschem 2023; 24:e202300342. [PMID: 37314040 DOI: 10.1002/cphc.202300342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 06/14/2023] [Accepted: 06/14/2023] [Indexed: 06/15/2023]
Abstract
New cage models (MeAlO)n (Me3 Al)m (n=16, m=6 or 7) isomeric with previously reported sheet models for the principle activator found in hydrolytic MAO (h-MAO) are compared at M06-2X and MN15 levels of theory using density functional theory with respect to their thermodynamic stability. Reactivity of the neutrals or corresponding anions with formula [(MeAlO)16 (Me3 Al)6 Me]- towards chlorination, and loss of Me3 Al is explored while reactivity of the neutrals towards formation of contact- and outer-sphere ion pairs from Cp2 ZrMe2 and Cp2 ZrMeCl is examined. The results suggest on balance that a cage model for this activator is less consistent with experiment than an isomeric sheet model, although the latter are more stable based on free energy.
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Affiliation(s)
- Scott Collins
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, Yliopistokatu 7, 80100, Joensuu, Finland
| | - Mikko Linnolahti
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, Yliopistokatu 7, 80100, Joensuu, Finland
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2
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Li K, Liu H, Li S, Li Q, Li S, Wang Q. The determinants of effective defluorination by the LiAl-LDHs. J Environ Sci (China) 2023; 126:153-162. [PMID: 36503744 DOI: 10.1016/j.jes.2022.04.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 06/17/2023]
Abstract
Millions of people in poor areas are still under the threat of fluoride contamination. How to effectively separate fluorine in water is an important step to reduce the ecological risk. In this paper, we performed a systematic DFT calculation focused on the defluorination behavior between the LiAl- and MgAl-LDHs. The results indicated that the LiAl-LDHs exhibited high chemical activity before the defluorination, because of the better electronic structure. After the defluorination, the LiAl-LDHs with adsorbed-F- were also more stable than the MgAl-LDHs. In addition, the existence of coordination covalent bond for the adsorbed-F- attached to the LiAl-LDHs was confirmed. This is an important reason for the high defluorination efficiency by the LiAl-LDHs. In addition, a series of weak interaction, including hydrogen bond and van der Waals interaction were also observed. Finally, a LiAl-LDHs with excellent fluoride removal properties were synthesized well by simple hydrothermal method. The results showed that our synthesized LiAl-LDHs with the capacity of 156.09 mg/g, could be effectively defluorinated in water. Notably, it surpasses most materials and has potential applications.
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Affiliation(s)
- Kaizhong Li
- School of Metallurgy and Environment, Central South University, Changsha 410083, China
| | - Hui Liu
- School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China; Water Pollution Control Technology Key Lab of Hunan Province, Changsha 410004, China
| | - Shuimei Li
- School of Metallurgy and Environment, Central South University, Changsha 410083, China
| | - Qingzhu Li
- School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China; Water Pollution Control Technology Key Lab of Hunan Province, Changsha 410004, China.
| | - Shengtu Li
- School of Metallurgy and Environment, Central South University, Changsha 410083, China
| | - Qingwei Wang
- School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China; Water Pollution Control Technology Key Lab of Hunan Province, Changsha 410004, China
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3
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Li K, Liu H, Li Q, Yao W, Wu L, Li S, Wang Q. The role of doped-Mn on enhancing arsenic removal by MgAl-LDHs. J Environ Sci (China) 2022; 120:125-134. [PMID: 35623766 DOI: 10.1016/j.jes.2021.07.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/19/2021] [Accepted: 07/19/2021] [Indexed: 06/15/2023]
Abstract
To meet the challenges posed by global arsenic water contamination, the MgAlMn-LDHs with extraordinary efficiency of arsenate removal was developed. In order to clarify the enhancement effect of the doped-Mn on the arsenate removal performance of the LDHs, the cluster models of the MgAlMn-LDHs and MgAl-LDHs were established and calculated by using density functional theory (DFT). The results shown that the doped-Mn can significantly change the electronic structure of the LDHs and improve its chemical activity. Compared with the MgAl-LDHs that without the doped-Mn, the HOMO-LUMO gap was smaller after doping. In addition, the -OH and Al on the laminates were also activated to improve the adsorption property of the LDHs. Besides, the doped-Mn existed as a novel active site. On the other hand, the MgAlMn-LDHs with the doped-Mn, the increased of the binding energy, as well as the decreased of the ion exchange energy of interlayer Cl-, making the ability to arsenate removal had been considerably elevated than the MgAl-LDHs. Furthermore, there is an obvious coordination covalent bond between arsenate and the laminates of the MgAlMn-LDHs that with the doped-Mn.
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Affiliation(s)
- Kaizhong Li
- School of Metallurgy and Environment, Central South University, Changsha 410083, China
| | - Hui Liu
- School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China; Water Pollution Control Technology Key Lab of Hunan Province, Changsha 410004, China
| | - Qingzhu Li
- School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China; Water Pollution Control Technology Key Lab of Hunan Province, Changsha 410004, China.
| | - Wenming Yao
- School of Metallurgy and Environment, Central South University, Changsha 410083, China
| | - Lanyan Wu
- School of Metallurgy and Environment, Central South University, Changsha 410083, China
| | - Shuimei Li
- School of Metallurgy and Environment, Central South University, Changsha 410083, China
| | - Qingwei Wang
- School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China; Water Pollution Control Technology Key Lab of Hunan Province, Changsha 410004, China
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4
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Linnolahti M, Collins S. Thermodynamics of metallocene catalyst activation: alignment of theory and experiment. Dalton Trans 2022; 51:11152-11162. [PMID: 35801522 DOI: 10.1039/d2dt01711c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three equilibria involved in metallocene catalyst activation, including dissociation of R6Al2 (R = Me, Et or i-Bu) and related species such as [L2ZrMe2AlMe2][B(C6F5)4] (L2 = Cp2, 1,2-ethylenebis(η5-indenyl), Me2C(η5-C5H4)2) or [(L2ZrMe)2μ-Me][MePBB] (L2 = (h5-1,2-Me2C5H3)2, [MePBB]- = [MeB(ArF)3]- with ArF = o-C6F5-C6F4) are studied by DFT using various approaches to account for the enthalpy and entropy changes in gas and condensed phases. These studies reveal that both low energy vibrations and translational entropy conspire to cause significant deviations between theory and experiment when it comes to the free energy change in condensed or even gas phase. Alignment of theory with experiment requires in addition, consideration of specific solvation of reactants and products.
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Affiliation(s)
- Mikko Linnolahti
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, Yliopistokatu 7, FI-80100, Joensuu, Finland.
| | - Scott Collins
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, Yliopistokatu 7, FI-80100, Joensuu, Finland.
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5
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Li K, Li S, Li Q, Liu H, Yao W, Wang Q, Chai L. Design of a high-performance ternary LDHs containing Ni, Co and Mn for arsenate removal. JOURNAL OF HAZARDOUS MATERIALS 2022; 427:127865. [PMID: 34848069 DOI: 10.1016/j.jhazmat.2021.127865] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/15/2021] [Accepted: 11/18/2021] [Indexed: 06/13/2023]
Abstract
To cope with the current serious arsenate pollution problem, a new ternary layered double hydroxides (LDHs) containing Ni, Co and Mn with good performance was developed, guiding by DFT calculations. First, Ni, Co and Mn were screened as the metal sources to constitute the LDHs, due to their high ionic charge density. Then, Ni(II), Co(II) and Mn(III)-O octahedra were selected as the primary units for structuring the LDHs, because of their good chemical activity. Meanwhile, the ratio of metals in the ternary LDHs, favoring for arsenate removal, was optimized at 1:2:1. In addition, the synergistic effect among various metals in the LDHs was considered. The results suggested that in the case of single doping, all three metals can act as the center to promote chemical activity independently. On the contrary, when combined together, there is only one unilateral active center. Moreover, the existence of ligand covalent bonds between arsenate and LDHs was confirmed. Finally, a promising new NiCo2Mn-LDHs with the maximum adsorption capacity of 407.23 mg/g for arsenate removal had been prepared.
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Affiliation(s)
- Kaizhong Li
- School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083, China
| | - Shuimei Li
- School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083, China
| | - Qingzhu Li
- School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China; Water Pollution Control Technology Key Lab of Hunan Province, Changsha 410004, China.
| | - Hui Liu
- School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China; Water Pollution Control Technology Key Lab of Hunan Province, Changsha 410004, China
| | - Wenming Yao
- School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083, China
| | - Qingwei Wang
- School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China; Water Pollution Control Technology Key Lab of Hunan Province, Changsha 410004, China
| | - Liyuan Chai
- School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China; Water Pollution Control Technology Key Lab of Hunan Province, Changsha 410004, China
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6
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Transition Metal-Catalyzed and MAO-Assisted Olefin Polymerization; Cyclic Isomers of Sinn’s Dimer Are Excellent Ligands in Iron Complexes and Great Methylating Reagents. Catalysts 2022. [DOI: 10.3390/catal12030312] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Methylaluminoxane (MAO) is the most commonly used co-catalyst for transition metal-catalyzed olefin polymerization, but the structures of MAO species and their catalytic functions remain topics of intensive study. We are interested in MAO-assisted polymerization with catalysts L(R2)FeCl2 (L = tridentate pyridine-2,6-diyldimethanimine; imine-R = Me, Ph). It is our hypothesis that the MAO species is not merely enabling Fe–Me bond formation but functions as an integral part of the active catalyst, a MAO adduct of the Fe-precatalyst [L(R2)FeCl]+. In this paper, we explored the possible structures of acyclic and cyclic MAO species and their complexation with pre-catalysts [L(R2)FeCl]+ using quantum chemical approaches (MP2 and DFT). We report absolute and relative oxophilicities associated with the Fe ← O(MAO) adduct formation and provide compelling evidence that oxygen of an acyclic MAO species (i.e., O(AlMe2)2, 4) cannot compete with the O-donor in cyclic MAO species (i.e., (MeAlO)2, 7; MeAl(OAlMe2)2, cyclic 5). Significantly, our work demonstrates that intramolecular O → Al dative bonding results in cyclic isomers of MAO species (i.e., cyclic 5) with high oxophilicities. The stabilities of the [L(R2)FeClax(MAO)eq]+ species demonstrate that 5 provides for the ligating benefits of the cyclic MAO species 4 without the thermodynamically costly elimination of TMA. Mechanistic implications are discussed for the involvement of such Fe–O–Al bridged catalyst in olefin polymerization.
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7
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Collins S, Joshi A, Linnolahti M. Formation and Structure of Hydrolytic Methylaluminoxane Activators. Chemistry 2021; 27:15460-15471. [PMID: 34436806 PMCID: PMC8596698 DOI: 10.1002/chem.202102463] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Indexed: 01/14/2023]
Abstract
Methylaluminoxane (MAO) activators have sheet structures which form ion-pairs on reaction of neutral donors such as octamethyltrisiloxane (OMTS). The ion-pairs can be detected by electrospray ionization mass spectrometry (ESI-MS) in polar media. The growth of these reactive precursors during hydrolysis of Me3 Al can be monitored using ESI-MS. Density functional theory, combined with numerical simulation of growth, indicates that this process involves rapid formation of low MW oligomers, followed by assembly of these species into low MW sheets. These can grow through further addition of low MW oligomers or by fusion into larger sheets. The mechanism of these growth processes leads to the prediction that even-numbered sheets should be favored, and this surprising result is confirmed by ESI-MS monitoring experiments of both activator growth and MAO aging.
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Affiliation(s)
- Scott Collins
- Former affiliation: Department of Chemistry, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada)
| | - Anuj Joshi
- UVic Genome BC Proteomics Research Centre sup, 4464 Markham St #3101, Victoria, BC V8Z 5N3, Canada
| | - Mikko Linnolahti
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, Yliopistokatu 7, 80100, Joensuu, Finland
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8
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Tyumkina TV, Islamov DN, Kovyazin PV, Parfenova LV. Chain and cluster models of methylaluminoxane as activators of zirconocene hydride, alkyl and metallacyclopropane intermediates in alkene transformations. MOLECULAR CATALYSIS 2021. [DOI: 10.1016/j.mcat.2021.111768] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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9
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Collins S, Hasan G, Joshi A, McIndoe JS, Linnolahti M. Are Methylaluminoxane Activators Sheets? Chemphyschem 2021; 22:1326-1335. [PMID: 33971081 PMCID: PMC8362195 DOI: 10.1002/cphc.202100268] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/07/2021] [Indexed: 11/14/2022]
Abstract
Density functional theory calculations on neutral sheet models for methylaluminoxane (MAO) indicate that these structures, containing 5‐coordinate and 4‐coordinate Al, are likely precursors to ion‐pairs seen during the hydrolysis of trimethylaluminum (Me3Al) in the presence of donors such as octamethyltrisiloxane (OMTS). Ionization by both methide ([Me]−) and [Me2Al]+ abstraction, involving this donor, were studied by polarizable continuum model calculations in fluorobenzene (PhF) and o‐difluorobenzene (DFB) media. These studies suggest that low MW, 5‐coordinate sheets ionize by [Me2Al]+ abstraction, while [Me]− abstraction from Me3Al‐OMTS is the likely process for higher MW 4‐coordinate sheets. Further, comparison of anion stabilities per mole of aluminoxane repeat unit (MeAlO)n, suggest that anions such as [(MeAlO)7(Me3Al)4Me]−=[7,4]− are especially stable compared to higher homologues, even though their neutral precursors are unstable.
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Affiliation(s)
- Scott Collins
- Department of Chemistry, University of Victoria, 3800, Finnerty Road, Victoria, BC, V8P 5 C2, Canada
| | - Galib Hasan
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, Yliopistokatu 7, 80100, Joensuu, Finland.,Institute for Atmospheric and Earth System Research (INAR) c/o Department of Chemistry, University of Helsinki, A.I Virtasen Aukio 1, 00014, Helsinki, Finland
| | - Anuj Joshi
- Department of Chemistry, University of Victoria, 3800, Finnerty Road, Victoria, BC, V8P 5 C2, Canada.,UVic Genome BC Proteomics Research Centre, 4464, Markham St #3101, Victoria, BC V8Z 5N3, Canada
| | - J Scott McIndoe
- Department of Chemistry, University of Victoria, 3800, Finnerty Road, Victoria, BC, V8P 5 C2, Canada
| | - Mikko Linnolahti
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, Yliopistokatu 7, 80100, Joensuu, Finland
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10
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Joshi A, Collins S, Linnolahti M, Zijlstra HS, Liles E, McIndoe JS. Spectroscopic Studies of Synthetic Methylaluminoxane: Structure of Methylaluminoxane Activators. Chemistry 2021; 27:8753-8763. [PMID: 33780574 DOI: 10.1002/chem.202100271] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Indexed: 11/06/2022]
Abstract
Hydrolysis of trimethylaluminum (Me3 Al) in polar solvents can be monitored by electrospray ionization mass spectrometry (ESI-MS) using the donor additive octamethyltrisiloxane [(Me3 SiO)2 SiMe2 , OMTS]. Using hydrated salts, hydrolytic methylaluminoxane (h-MAO) features different anion distributions, depending on the conditions of synthesis, and different activator contents as measured by NMR spectroscopy. Non-hydrolytic MAO was prepared using trimethylboroxine. The properties of this material, which contains incorporated boron, differ significantly from h-MAO. In the case of MAO prepared by direct hydrolysis, oligomeric anions are observed to rapidly form, and then more slowly evolve into a mixture dominated by an anion with m/z 1375 with formula [(MeAlO)16 (Me3 Al)6 Me]- . Theoretical calculations predict that sheet structures with composition (MeAlO)n (Me3 Al)m are favoured over other motifs for MAO in the size range suggested by the ESI-MS experiments. A possible precursor to the m/z 1375 anion is a local minimum based on the free energy released upon hydrolysis of Me3 Al.
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Affiliation(s)
- Anuj Joshi
- Department of Chemistry, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
| | - Scott Collins
- C/o Department of Chemistry, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
| | - Mikko Linnolahti
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, Yliopistokatu 7, 80100, Joensuu, Finland
| | - Harmen S Zijlstra
- Department of Chemistry, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
| | - Elena Liles
- Department of Chemistry, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
| | - J Scott McIndoe
- Department of Chemistry, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
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11
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Kilpatrick AFR, Geddes HS, Turner ZR, Buffet JC, Goodwin AL, O'Hare D. Polymethylaluminoxane organic frameworks (sMAOF) – highly active supports for slurry phase ethylene polymerisation. Catal Sci Technol 2021. [DOI: 10.1039/d1cy00767j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A series of modified solid polymethylaluminoxane (sMAO) catalyst supports have been developed for slurry phase ethylene polymerisation, using aryl di-ol modifier groups.
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Affiliation(s)
| | | | - Zoë R. Turner
- Chemistry Research Laboratory
- Department of Chemistry
- University of Oxford
- Oxford
- UK
| | - Jean-Charles Buffet
- Chemistry Research Laboratory
- Department of Chemistry
- University of Oxford
- Oxford
- UK
| | | | - Dermot O'Hare
- Chemistry Research Laboratory
- Department of Chemistry
- University of Oxford
- Oxford
- UK
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12
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Teixeira VE, Livotto PR. The mechanism of the reaction between MAO and TMA: DFT study of the electronic structure and characterization of transition states for [AlOMe] 6, [AlOMe] 9 and [AlOMe] 16 cages. J Mol Graph Model 2020; 99:107626. [PMID: 32447271 DOI: 10.1016/j.jmgm.2020.107626] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/02/2020] [Accepted: 04/20/2020] [Indexed: 10/24/2022]
Abstract
Methylaluminoxane (MAO) and trimethylaluminium (TMA) are relevant compounds in organometallic catalysis. Despite many published studies, aspects of their interaction persist an unsolved puzzle. Hence, in this work, we used quantum mechanic approaches based on density functional theory to study this topic. Our calculations revealed that interaction between MAO and TMA occurs initially by the formation of an intermediary Lewis adduct. In agreement with the latent acidity concept, the activation energy for the tensioned Al-O bond break is small, and changes with the local environment of the MAO cages. Breakage of bond belonging to two square faces requires between 4.20 and 5.80 kcal/mol, whereas square-hexagonal faces demand 0.61-9.43 kcal/mol. The products of this reaction present a terminal, acidic 3-coordinate aluminum atom, that can be capped by another TMA molecules. However, our computations suggest that entropic effects may prevent this reaction from occurring at all these sites in the MAO models studied. Additionally, we also characterize the inter/intramolecular methane elimination mechanism. These reactions are not feasible at room temperature but may occur at high temperatures.
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Affiliation(s)
- Vinícius Esteves Teixeira
- Institute of Chemistry - Federal University of Rio Grande do Sul UFRGS, Av. Bento Gonçalves, 9500 CEP 91501-970, Porto Alegre, Brazil.
| | - Paolo Roberto Livotto
- Institute of Chemistry - Federal University of Rio Grande do Sul UFRGS, Av. Bento Gonçalves, 9500 CEP 91501-970, Porto Alegre, Brazil
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13
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Zaccaria F, Budzelaar PHM, Cipullo R, Zuccaccia C, Macchioni A, Busico V, Ehm C. Reactivity Trends of Lewis Acidic Sites in Methylaluminoxane and Some of Its Modifications. Inorg Chem 2020; 59:5751-5759. [PMID: 32271565 PMCID: PMC7997381 DOI: 10.1021/acs.inorgchem.0c00533] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Indexed: 11/28/2022]
Abstract
The established model cluster (AlOMe)16(AlMe3)6 for methylaluminoxane (MAO) cocatalyst has been studied by density functional theory, aiming to rationalize the different behaviors of unmodified MAO and TMA-depleted MAO/BHT (TMA = trimethylaluminum; BHT = 2,6-di-tert-butyl-4-methylphenol), highlighted in previous experimental studies. The tendency of the three model Lewis acidic sites A-C to release neutral Al fragments (i.e., AlMe2R; R = Me or bht) or transient aluminum cations (i.e., [AlMeR]+) has been investigated both in the absence and in the presence of neutral N-donors. Sites C are most likely responsible for the activation capabilities of TMA-rich MAO, but TMA depletion destabilizes them, possibly inducing structural rearrangements. The remaining sites A and B, albeit of lower Lewis acidity, should be still able to release cationic Al fragments when TMA-depleted modified MAOs are treated with N-donors (e.g. [AlMe(bht)]+ from MAO/BHT). These findings provide tentative interpretations for earlier observations of donor-dependent ionization tendencies of MAO and MAO/BHT and how TMA depleted MAOs can still be potent activators.
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Affiliation(s)
- Francesco Zaccaria
- Dipartimento
di Scienze Chimiche, Università di
Napoli Federico II, Via Cintia, 80126 Napoli, Italy
- Dipartimento
di Chimica, Biologia e Biotecnologie and CIRCC, Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
| | - Peter H. M. Budzelaar
- Dipartimento
di Scienze Chimiche, Università di
Napoli Federico II, Via Cintia, 80126 Napoli, Italy
| | - Roberta Cipullo
- Dipartimento
di Scienze Chimiche, Università di
Napoli Federico II, Via Cintia, 80126 Napoli, Italy
| | - Cristiano Zuccaccia
- Dipartimento
di Chimica, Biologia e Biotecnologie and CIRCC, Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
| | - Alceo Macchioni
- Dipartimento
di Chimica, Biologia e Biotecnologie and CIRCC, Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
| | - Vincenzo Busico
- Dipartimento
di Scienze Chimiche, Università di
Napoli Federico II, Via Cintia, 80126 Napoli, Italy
| | - Christian Ehm
- Dipartimento
di Scienze Chimiche, Università di
Napoli Federico II, Via Cintia, 80126 Napoli, Italy
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14
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Zaccaria F, Zuccaccia C, Cipullo R, Budzelaar PHM, Macchioni A, Busico V, Ehm C. On the Nature of the Lewis Acidic Sites in “TMA‐Free” Phenol‐Modified Methylaluminoxane. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201901035] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Francesco Zaccaria
- Dipartimento di Scienze Chimiche Università di Napoli Federico II Via Cintia 80126 Napoli Italy
- Dipartimento di Chimica Biologia e Biotecnologie and CIRCC Università di Perugia Via Elce di Sotto 8 06123 Perugia Italy
| | - Cristiano Zuccaccia
- Dipartimento di Chimica Biologia e Biotecnologie and CIRCC Università di Perugia Via Elce di Sotto 8 06123 Perugia Italy
| | - Roberta Cipullo
- Dipartimento di Scienze Chimiche Università di Napoli Federico II Via Cintia 80126 Napoli Italy
| | - Peter H. M. Budzelaar
- Dipartimento di Scienze Chimiche Università di Napoli Federico II Via Cintia 80126 Napoli Italy
| | - Alceo Macchioni
- Dipartimento di Chimica Biologia e Biotecnologie and CIRCC Università di Perugia Via Elce di Sotto 8 06123 Perugia Italy
| | - Vincenzo Busico
- Dipartimento di Scienze Chimiche Università di Napoli Federico II Via Cintia 80126 Napoli Italy
| | - Christian Ehm
- Dipartimento di Scienze Chimiche Università di Napoli Federico II Via Cintia 80126 Napoli Italy
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15
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Velthoen ME, Boereboom JM, Bulo RE, Weckhuysen BM. Insights into the activation of silica-supported metallocene olefin polymerization catalysts by methylaluminoxane. Catal Today 2019. [DOI: 10.1016/j.cattod.2018.11.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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16
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Velthoen MEZ, Muñoz-Murillo A, Bouhmadi A, Cecius M, Diefenbach S, Weckhuysen BM. The Multifaceted Role of Methylaluminoxane in Metallocene-Based Olefin Polymerization Catalysis. Macromolecules 2018; 51:343-355. [PMID: 29910511 PMCID: PMC5997399 DOI: 10.1021/acs.macromol.7b02169] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 12/02/2017] [Indexed: 01/26/2023]
Abstract
![]()
In
single-site olefin polymerization catalysis, a large excess
of cocatalyst is often required for the generation of highly active
catalysts, but the reason for this is unclear. In this work, fundamental
insight into the multifaceted role of cocatalyst methylaluminoxane
(MAO) in the activation, deactivation, and stabilization of group
4 metallocenes in the immobilized single-site olefin polymerization
catalyst was gained. Employing probe molecule FT-IR spectroscopy,
it was found that weak Lewis acid sites, inherent to the silica-supported
MAO cocatalyst, are the main responsible species for the genesis of
active metallocenes for olefin polymerization. These weak Lewis acid
sites are the origin of AlMe2+ groups. Deactivation
of metallocenes is caused by the presence of silanol groups on the
silica support. Interaction of the catalyst precursor with these silanol
groups leads to the irreversible formation of inactive metallocenes.
Importantly, a high concentration of MAO (14 wt% Al) on the silica
support is necessary to keep the metallocenes immobilized, hence preventing
metallocene leaching and consequent reactor fouling. Increasing the
loading of the MAO cocatalyst leads to larger amounts of AlMe2+, fewer silanol groups, and less metallocene leaching,
which all result in higher olefin polymerization activity.
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Affiliation(s)
- Marjolein E Z Velthoen
- Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Ara Muñoz-Murillo
- Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Abdelkbir Bouhmadi
- Albemarle Europe SPRL, Parc Scientifique de LLN, Rue du Bosquet 9, B-1348 Louvain-la-Neuve, Belgium
| | - Michaël Cecius
- Albemarle Europe SPRL, Parc Scientifique de LLN, Rue du Bosquet 9, B-1348 Louvain-la-Neuve, Belgium
| | - Steve Diefenbach
- Albemarle Corporation, Gulf States Road, Baton Rouge, Louisiana 70801, United States
| | - Bert M Weckhuysen
- Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
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17
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Kilpatrick AFR, Rees NH, Sripothongnak S, Buffet JC, O’Hare D. Slurry-Phase Ethylene Polymerization Using Pentafluorophenyl- and Pentafluorophenoxy-Modified Solid Polymethylaluminoxanes. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00846] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alexander F. R. Kilpatrick
- Chemistry
Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
| | - Nicholas H. Rees
- Chemistry
Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
| | | | - Jean-Charles Buffet
- Chemistry
Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
| | - Dermot O’Hare
- Chemistry
Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
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18
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Collins S, Linnolahti M, Zamora MG, Zijlstra HS, Rodríguez Hernández MT, Perez-Camacho O. Activation of Cp2ZrX2 (X = Me, Cl) by Methylaluminoxane As Studied by Electrospray Ionization Mass Spectrometry: Relationship to Polymerization Catalysis. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b00933] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Scott Collins
- Department
of Chemistry, University of Victoria, 3800 Finnerty Rd. Victoria, BC, Canada
- Centro de Investigacion en Quimica Aplicada, CP 25294 Saltillo, COAH, Mexico
| | - Mikko Linnolahti
- Department
of Chemistry, Joensuu Campus, University of Eastern Finland, P.O. Box 111 FI-80101 Joensuu, Finland
| | | | - Harmen S. Zijlstra
- Department
of Chemistry, University of Victoria, 3800 Finnerty Rd. Victoria, BC, Canada
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19
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Parfenova LV, Kovyazin PV, Tyumkina TV, Islamov DN, Lyapina AR, Karchevsky SG, Ivchenko PV. Reactions of bimetallic Zr,Al- hydride complexes with methylaluminoxane: NMR and DFT study. J Organomet Chem 2017. [DOI: 10.1016/j.jorganchem.2017.09.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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20
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Linnolahti M, Collins S. Formation, Structure, and Composition of Methylaluminoxane. Chemphyschem 2017; 18:3369-3374. [PMID: 28857416 DOI: 10.1002/cphc.201700827] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 08/31/2017] [Indexed: 11/12/2022]
Abstract
The structurally ill-characterized methylaluminoxane (MAO) is the activator of choice in olefin polymerization catalysis. We have carried out large scale and systematic quantum chemical calculations to simulate the thermodynamics of its formation by controlled hydrolysis of trimethylaluminum (TMA), extending the studies up to 25 Al atoms, and thus, to the real size domain of MAO. In agreement with previous postulates on its structure, MAO is shown to favor cage-like structures, which commonly contain associated TMA, regardless of size or shape. The sites containing associated TMA are reactive, and explain the function of MAO as a catalyst activator. The compositions of MAOs show overall agreement with experiments, and exhibit structural transitions from chains to rings to sheets to eventually cages as a function of size. The most stable cage structure is obtained for a composition of (MeAlO)16 (Me3 Al)6 , which is in precise agreement with mass spectrometric studies of corresponding anions, and adapts a tubular molecular structure with a molecular weight of 1360 g mol-1 . Our mass spectrometric measurements enable detection of both major and minor anion species.
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Affiliation(s)
- Mikko Linnolahti
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, FI-80101, Joensuu, Finland
| | - Scott Collins
- Department of Chemistry, University of Victoria, 3800 Finnerty Rd., Victoria, BC, Canada
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21
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22
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Influence of trimethylaluminum on kinetics of rac -Et(Ind) 2 ZrCl 2 /aluminoxane catalyzed ethylene polymerization. J Organomet Chem 2016. [DOI: 10.1016/j.jorganchem.2016.02.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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23
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Quantitative structure–property relationships in propene polymerization by zirconocenes with a rac-SiMe2[Ind]2 based ligand framework. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.molcata.2015.11.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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24
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Atiqullah M, Adamu S, Malaibari ZO, Al-Harthi MA, Emwas AHM. (nBuCp)2ZrCl2-catalyzed ethylene-4M1P copolymerization: Copolymer backbone structure, melt behavior, and crystallization. AIChE J 2016. [DOI: 10.1002/aic.15159] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Muhammad Atiqullah
- Center for Refining and Petrochemicals, Research Institute, King Fahd University of Petroleum & Minerals; Dhahran 31261 Saudi Arabia
| | - Sagir Adamu
- Dept. of Chemical Engineering; King Fahd University of Petroleum & Minerals; Dhahran 31261 Saudi Arabia
| | - Zuhair O. Malaibari
- Dept. of Chemical Engineering; King Fahd University of Petroleum & Minerals; Dhahran 31261 Saudi Arabia
| | - Mamdouh A. Al-Harthi
- Dept. of Chemical Engineering; King Fahd University of Petroleum & Minerals; Dhahran 31261 Saudi Arabia
| | - Abdul-Hamid M. Emwas
- NMR Core Laboratory, King Abdullah University of Science & Technology; Thuwal 23955-6900 Saudi Arabia
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25
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Falls Z, Zurek E, Autschbach J. Computational prediction and analysis of the 27Al solid-state NMR spectrum of methylaluminoxane (MAO) at variable temperatures and field strengths. Phys Chem Chem Phys 2016; 18:24106-18. [PMID: 27526292 DOI: 10.1039/c6cp04260k] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
27Al MAS NMR of the co-catalyst methylaluminoxane may be able to reveal the fraction of species that are catalytically active.
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Affiliation(s)
- Zackary Falls
- Department of Chemistry
- University at Buffalo
- State University of New York
- Buffalo
- USA
| | - Eva Zurek
- Department of Chemistry
- University at Buffalo
- State University of New York
- Buffalo
- USA
| | - Jochen Autschbach
- Department of Chemistry
- University at Buffalo
- State University of New York
- Buffalo
- USA
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26
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Chen Y, Fang X, Dan W. 1,2-Azaborolyl-Ligated Titanium(IV) Half-Metallocenes: Synthesis, Characterization, and Catalytic Activity in Ethylene Polymerization. Organometallics 2015. [DOI: 10.1021/acs.organomet.5b00779] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yang Chen
- Department of Chemistry,
Shanghai Key Laboratory of Chemical Assessment and Sustainability
(CAS), Tongji University, 1239 Siping Road, Yangpu District, Shanghai 210092, People’s Republic of China
| | - Xiangdong Fang
- Department of Chemistry,
Shanghai Key Laboratory of Chemical Assessment and Sustainability
(CAS), Tongji University, 1239 Siping Road, Yangpu District, Shanghai 210092, People’s Republic of China
| | - Wenyan Dan
- Department of Chemistry,
Shanghai Key Laboratory of Chemical Assessment and Sustainability
(CAS), Tongji University, 1239 Siping Road, Yangpu District, Shanghai 210092, People’s Republic of China
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27
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Tymińska N, Zurek E. DFT-D Investigation of Active and Dormant Methylaluminoxane (MAO) Species Grafted onto a Magnesium Dichloride Cluster: A Model Study of Supported MAO. ACS Catal 2015. [DOI: 10.1021/acscatal.5b01697] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nina Tymińska
- Department
of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260-3000, United States
| | - Eva Zurek
- Department
of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260-3000, United States
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28
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Kuklin MS, Virkkunen V, Castro PM, Resconi L, Linnolahti M. Controlling the Microstructure of Isotactic Polypropene byC2-Symmetric Zirconocene Polymerization Catalysts: Influence of Alkyl Substituents on Regio- and Stereocontrol. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201500862] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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29
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Kuklin MS, Hirvi JT, Bochmann M, Linnolahti M. Toward Controlling the Metallocene/Methylaluminoxane-Catalyzed Olefin Polymerization Process by a Computational Approach. Organometallics 2015. [DOI: 10.1021/acs.organomet.5b00394] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mikhail S. Kuklin
- Department of Chemistry, University of Eastern Finland, Joensuu
Campus, FI-80101 Joensuu, Finland
| | - Janne T. Hirvi
- Department of Chemistry, University of Eastern Finland, Joensuu
Campus, FI-80101 Joensuu, Finland
| | - Manfred Bochmann
- Wolfson Materials and Catalysis Centre, School of Chemistry, University of East Anglia, Earlham Road, Norwich, NR4 7TJ, United Kingdom
| | - Mikko Linnolahti
- Department of Chemistry, University of Eastern Finland, Joensuu
Campus, FI-80101 Joensuu, Finland
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30
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Ethylene homo- and copolymerization chain-transfers: A perspective from supported ( n BuCp) 2 ZrCl 2 catalyst active centre distribution. J CHEM SCI 2015. [DOI: 10.1007/s12039-015-0828-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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31
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Kerber RN, Kerber T, Rozanska X, Delbecq F, Sautet P. Grafting trimethylaluminum and its halogen derivatives on silica: general trends for 27Al SS-NMR response from first principles calculations. Phys Chem Chem Phys 2015; 17:26937-45. [DOI: 10.1039/c5cp04109k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
27Al solid-state NMR spectrum and parameters for various types of Al monomeric and dimeric alkyl and halogen compounds grafted on silica are interpreted based on the trends obtained from first-principles calculations.
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Affiliation(s)
- Rachel Nathaniel Kerber
- Université de Lyon
- CNRS
- Institut de Chimie de Lyon
- Ecole Normale Supérieure de Lyon
- F-69364 Lyon Cedex 07
| | - Torsten Kerber
- Université de Lyon
- CNRS
- Institut de Chimie de Lyon
- Ecole Normale Supérieure de Lyon
- F-69364 Lyon Cedex 07
| | - Xavier Rozanska
- Université de Lyon
- CNRS
- Institut de Chimie de Lyon
- Ecole Normale Supérieure de Lyon
- F-69364 Lyon Cedex 07
| | - Françoise Delbecq
- Université de Lyon
- CNRS
- Institut de Chimie de Lyon
- Ecole Normale Supérieure de Lyon
- F-69364 Lyon Cedex 07
| | - Philippe Sautet
- Université de Lyon
- CNRS
- Institut de Chimie de Lyon
- Ecole Normale Supérieure de Lyon
- F-69364 Lyon Cedex 07
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32
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Trefz TK, Henderson MA, Linnolahti M, Collins S, McIndoe JS. Mass spectrometric characterization of methylaluminoxane-activated metallocene complexes. Chemistry 2014; 21:2980-91. [PMID: 25556910 DOI: 10.1002/chem.201405319] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Indexed: 11/11/2022]
Abstract
Electrospray-ionization mass spectrometric studies of poly(methylaluminoxane) (MAO) in the presence of [Cp2 ZrMe2 ], [Cp2 ZrMe(Cl)], and [Cp2 ZrCl2 ] in fluorobenzene (PhF) solution are reported. The results demonstrate that alkylation and ionization are separate events that occur at competitive rates in a polar solvent. Furthermore, there are significant differences in ion-pair speciation that result from the use of metallocene dichloride complexes in comparison to alkylated precursors at otherwise identical Al/Zr ratios. Finally, the counter anions that form are dependent on the choice of precursor and Al/Zr ratio; halogenated aluminoxane anions [(MeAlO)x (Me3 Al)y-z (Me2 AlCl)z Me](-) (z=1, 2, 3…︁) are observed using metal chloride complexes and under some conditions may predominate over their non-halogenated precursors [(MeAlO)x (Me3 Al)y Me](-) . Specifically, this halogenation process appears selective for the anions that form in comparison to the neutral components of MAO. Only at very high Al/Zr ratios is the same "native" anion distribution observed when using [Cp2 ZrCl2 ] when compared with [Cp2 ZrMe2 ]. Together, the results suggest that the need for a large excess of MAO when using metallocene dichloride complexes is a reflection of competitive alkylation vs. ionization, the persistence of unreactive, homodinuclear ion pairs in the case of [Cp2 ZrCl2 ], as well as a change in ion pairing resulting from modification of the anions formed at lower Al/Zr ratios. Models for neutral precursors and anions are examined computationally.
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Affiliation(s)
- Tyler K Trefz
- Department of Chemistry, University of Victoria, P.O. Box 3065 Victoria, BC V8W3V6 (Canada)
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33
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Zijlstra HS, Harder S. Methylalumoxane – History, Production, Properties, and Applications. Eur J Inorg Chem 2014. [DOI: 10.1002/ejic.201402978] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Harmen S. Zijlstra
- Stratingh Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands
- Dutch Polymer Institute (DPI), P. O. Box 902, 5600 AX Eindhoven, Netherlands
| | - Sjoerd Harder
- Dutch Polymer Institute (DPI), P. O. Box 902, 5600 AX Eindhoven, Netherlands
- Inorganic and Organometallic Chemistry, University of Erlangen‐Nürnberg, Egerlandstr. 1, 91058 Erlangen, Germany, http://www.harder‐research.com
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34
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Falls Z, Tymińska N, Zurek E. The Dynamic Equilibrium Between (AlOMe)n Cages and (AlOMe)n·(AlMe3)m Nanotubes in Methylaluminoxane (MAO): A First-Principles Investigation. Macromolecules 2014. [DOI: 10.1021/ma501892v] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Zackary Falls
- Department of Chemistry University
at Buffalo, State University of New York Buffalo, New York 14260−3000, United States
| | - Nina Tymińska
- Department of Chemistry University
at Buffalo, State University of New York Buffalo, New York 14260−3000, United States
| | - Eva Zurek
- Department of Chemistry University
at Buffalo, State University of New York Buffalo, New York 14260−3000, United States
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35
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Ehm C, Antinucci G, Budzelaar PH, Busico V. Catalyst activation and the dimerization energy of alkylaluminium compounds. J Organomet Chem 2014. [DOI: 10.1016/j.jorganchem.2014.09.013] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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36
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Atiqullah M, Adamu S, Hossain MM, Al-Harthi MA, Anantawaraskul S, Hossaen A. Effects of supported (nBuCp)2ZrCl2 catalyst active center multiplicity on crystallization kinetics of ethylene homo- and copolymers. J Taiwan Inst Chem Eng 2014. [DOI: 10.1016/j.jtice.2013.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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37
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Hirvi JT, Bochmann M, Severn JR, Linnolahti M. Formation of octameric methylaluminoxanes by hydrolysis of trimethylaluminum and the mechanisms of catalyst activation in single-site α-olefin polymerization catalysis. Chemphyschem 2014; 15:2732-42. [PMID: 24930450 DOI: 10.1002/cphc.201402298] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Indexed: 11/10/2022]
Abstract
Hydrolysis of trimethylaluminum (TMA) leads to the formation of methylaluminoxanes (MAO) of general formula (MeAlO)n (AlMe3)m. The thermodynamically favored pathway of MAO formation is followed up to n=8, showing the major impact of associated TMA on the structural characteristics of the MAOs. The MAOs bind up to five TMA molecules, thereby inducing transition from cages into rings and sheets. Zirconocene catalyst activation studies using model MAO co-catalysts show the decisive role of the associated TMA in forming the catalytically active sites. Catalyst activation can take place either by Lewis-acidic abstraction of an alkyl or halide ligand from the precatalyst or by reaction of the precatalyst with an MAO-derived AlMe2(+) cation. Thermodynamics suggest that activation through AlMe2(+) transfer is the dominant mechanism because sites that are able to release AlMe2(+) are more abundant than Lewis-acidic sites. The model catalyst system is demonstrated to polymerize ethene.
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Affiliation(s)
- Janne T Hirvi
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, 80101 Joensuu (Finland)
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38
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Fang G, Ma J. Rapid atomic layer deposition of silica nanolaminates: synergistic catalysis of Lewis/Brønsted acid sites and interfacial interactions. NANOSCALE 2013; 5:11856-11869. [PMID: 24126605 DOI: 10.1039/c3nr02086j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Rapid atomic layer deposition (RALD) has been applied to prepare various nanolaminates with repeated multilayer structures. The possible reaction pathways for RALD of the Al2O3/SiO2 nanolaminate using trimethylaluminum (TMA) and tris(tert-butoxy)silanol (TBS) are investigated by using density functional theory (DFT) calculations. The introduction of a Lewis-acid catalyst, TMA, can result in the formation of the catalytic site, which accelerates the propagation of the siloxane polymer. The rate-determining step of whole RALD is the elimination of isobutene of the tert-butoxy groups. The Brønsted acid site of [AlO4] can catalyze the elimination of isobutene. At the same time, the interfacial interactions, such as hydrogen bonding interactions between tert-butoxy groups and the surface, further catalyze the elimination of isobutene and accelerate SiO2 RALD reactions. The synergistic catalysis of Lewis/Brønsted acid sites and interfacial interactions may be applied in the RALD fabrication of other silica nanolaminates, such as HfO2/SiO2, ZrO2/SiO2, and TiO2/SiO2, in microelectronics, catalysis, energy storage, and conversion.
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Affiliation(s)
- Guoyong Fang
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China.
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39
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Atiqullah M, Anantawaraskul S, Emwas AHM, Al-Harthi MA, Hussain I, Ul-Hamid A, Hossaen A. Silica-supported (n
BuCp)2
ZrCl2
: effect of catalyst active center distribution on ethylene-1-hexene copolymerization. POLYM INT 2013. [DOI: 10.1002/pi.4587] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Muhammad Atiqullah
- Center for Refining and Petrochemicals, Research Institute; King Fahd University of Petroleum & Minerals; Dhahran 31261 Saudi Arabia
- Center of Research Excellence in Petroleum Refining and Petrochemicals; King Fahd University of Petroleum & Minerals; Dhahran 31261 Saudi Arabia
| | - Siripon Anantawaraskul
- Department of Chemical Engineering; Kasetsart University; Jatujak Bangkok 10900 Thailand
| | - Abdul-Hamid M Emwas
- NMR Core Laboratory; King Abdullah University of Science & Technology; Thuwal 23955 Saudi Arabia
| | - Mamdouh A Al-Harthi
- Department of Chemical Engineering; King Fahd University of Petroleum & Minerals; Dhahran 31261 Saudi Arabia
| | - Ikram Hussain
- Center of Research Excellence in Petroleum Refining and Petrochemicals; King Fahd University of Petroleum & Minerals; Dhahran 31261 Saudi Arabia
| | - Anwar Ul-Hamid
- Center for Engineering Research, Research Institute; King Fahd University of Petroleum & Minerals; Dhahran 31261 Saudi Arabia
| | - Anwar Hossaen
- Center of Research Excellence in Petroleum Refining and Petrochemicals; King Fahd University of Petroleum & Minerals; Dhahran 31261 Saudi Arabia
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40
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Atiqullah M, Anantawaraskul S, Emwas AHM, Al-Harthi MA, Hussain I, Ul-Hamid A, Hossaen A. Effects of Supported (nBuCp)2ZrCl2 Catalyst Active-Center Distribution on Ethylene–1-Hexene Copolymer Backbone Heterogeneity and Thermal Behaviors. Ind Eng Chem Res 2013. [DOI: 10.1021/ie4005139] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
| | - Siripon Anantawaraskul
- Department of
Chemical Engineering, Kasetsart University, Jatujak, Bangkok 10900, Thailand
| | - Abdul-Hamid M. Emwas
- NMR Core Laboratory, King Abdullah University of Science & Technology, Thuwal 23955-6900, Saudi Arabia
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41
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Ghiotto F, Pateraki C, Tanskanen J, Severn JR, Luehmann N, Kusmin A, Stellbrink J, Linnolahti M, Bochmann M. Probing the Structure of Methylalumoxane (MAO) by a Combined Chemical, Spectroscopic, Neutron Scattering, and Computational Approach. Organometallics 2013. [DOI: 10.1021/om4002878] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fabio Ghiotto
- Wolfson Materials and Catalysis
Centre, School of Chemistry, University of East Anglia, Norwich,
United Kingdom
| | - Chrysoula Pateraki
- Wolfson Materials and Catalysis
Centre, School of Chemistry, University of East Anglia, Norwich,
United Kingdom
| | - Jukka Tanskanen
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, FI-80101 Joensuu, Finland
| | - John R. Severn
- UHMwPE Chemistry & Catalysis, DSM, NL-6160MD Geleen, The Netherlands
| | - Nicole Luehmann
- Jülich Centre for Neutron Science and Institute for Complex
Systems, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - André Kusmin
- Jülich Centre for Neutron Science and Institute for Complex
Systems, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Jörg Stellbrink
- Jülich Centre for Neutron Science and Institute for Complex
Systems, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Mikko Linnolahti
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, FI-80101 Joensuu, Finland
| | - Manfred Bochmann
- Wolfson Materials and Catalysis
Centre, School of Chemistry, University of East Anglia, Norwich,
United Kingdom
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42
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Trefz TK, Henderson MA, Wang MY, Collins S, McIndoe JS. Mass Spectrometric Characterization of Methylaluminoxane. Organometallics 2013. [DOI: 10.1021/om400256f] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tyler K. Trefz
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC V8W3 V6, Canada
| | - Matthew A. Henderson
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC V8W3 V6, Canada
| | - Miles Y. Wang
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC V8W3 V6, Canada
| | - Scott Collins
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC V8W3 V6, Canada
| | - J. Scott McIndoe
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC V8W3 V6, Canada
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43
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Linnolahti M, Laine A, Pakkanen TA. Screening the thermodynamics of trimethylaluminum-hydrolysis products and their co-catalytic performance in olefin-polymerization catalysis. Chemistry 2013; 19:7133-42. [PMID: 23576459 DOI: 10.1002/chem.201204450] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Indexed: 11/10/2022]
Abstract
Herein, we introduce an approach for the computational screening of stoichiometric reactions between trimethylaluminum (TMA) and water. The thermodynamic products of these reactions are methylaluminoxanes (MAOs) with different compositions, which have the general formula (AlOMe)n(AlMe3 )m, in which n describes the degree of oligomerization and m is the number of associated TMA molecules. These reaction products were thoroughly explored up to n=4, thus demonstrating the thermodynamically preferable association of up to four AlMe3 molecules, that is, TMA molecules in their monomeric form. The relative Lewis acidities of the Al sites in these MAOs were systematically explored and we found that the associated TMA molecules were a key ingredient for co-catalytic activity in olefin-polymerization catalysis. This conclusion was supported by computational studies on catalyst activation, which revealed an exergonic insertion of ethene into the metallocene/MAO complex.
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Affiliation(s)
- Mikko Linnolahti
- Department of Chemistry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland.
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44
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Rocchigiani L, Busico V, Pastore A, Macchioni A. Probing the interactions between all components of the catalytic pool for homogeneous olefin polymerisation by diffusion NMR spectroscopy. Dalton Trans 2013; 42:9104-11. [DOI: 10.1039/c3dt00041a] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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45
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Boudene Z, De Bruin T, Toulhoat H, Raybaud P. A QSPR Investigation of Thermal Stability of [Al(CH3)O]n Oligomers in Methylaluminoxane Solution: The Identification of a Geometry-Based Descriptor. Organometallics 2012. [DOI: 10.1021/om300916q] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zoubeyr Boudene
- IFP Energies nouvelles, 1 & 4 Avenue de Bois Préau, 92852 Rueil-Malmaison, France
| | - Theodorus De Bruin
- IFP Energies nouvelles, 1 & 4 Avenue de Bois Préau, 92852 Rueil-Malmaison, France
| | - Hervé Toulhoat
- IFP Energies nouvelles, 1 & 4 Avenue de Bois Préau, 92852 Rueil-Malmaison, France
| | - Pascal Raybaud
- IFP Energies nouvelles, Rond-point de l’Echangeur de Solaize, BP 3, 69360, Solaize,
France
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46
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Alkylation and activation of metallocene polymerization catalysts by reactions with trimethylaluminum: A computational study. J Organomet Chem 2012. [DOI: 10.1016/j.jorganchem.2012.06.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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47
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Kerber RN, Kermagoret A, Callens E, Florian P, Massiot D, Lesage A, Copéret C, Delbecq F, Rozanska X, Sautet P. Nature and structure of aluminum surface sites grafted on silica from a combination of high-field aluminum-27 solid-state NMR spectroscopy and first-principles calculations. J Am Chem Soc 2012; 134:6767-75. [PMID: 22440230 DOI: 10.1021/ja3008566] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The determination of the nature and structure of surface sites after chemical modification of large surface area oxides such as silica is a key point for many applications and challenging from a spectroscopic point of view. This has been, for instance, a long-standing problem for silica reacted with alkylaluminum compounds, a system typically studied as a model for a supported methylaluminoxane and aluminum cocatalyst. While (27)Al solid-state NMR spectroscopy would be a method of choice, it has been difficult to apply this technique because of large quadrupolar broadenings. Here, from a combined use of the highest stable field NMR instruments (17.6, 20.0, and 23.5 T) and ultrafast magic angle spinning (>60 kHz), high-quality spectra were obtained, allowing isotropic chemical shifts, quadrupolar couplings, and asymmetric parameters to be extracted. Combined with first-principles calculations, these NMR signatures were then assigned to actual structures of surface aluminum sites. For silica (here SBA-15) reacted with triethylaluminum, the surface sites are in fact mainly dinuclear Al species, grafted on the silica surface via either two terminal or two bridging siloxy ligands. Tetrahedral sites, resulting from the incorporation of Al inside the silica matrix, are also seen as minor species. No evidence for putative tri-coordinated Al atoms has been found.
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Affiliation(s)
- Rachel Nathaniel Kerber
- Université de Lyon, CNRS, Institut de Chimie de Lyon, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, F-69364 Lyon Cedex 07, France
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48
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Glaser R, Sun X. Thermochemistry of the initial steps of methylaluminoxane formation. Aluminoxanes and cycloaluminoxanes by methane elimination from dimethylaluminum hydroxide and its dimeric aggregates. J Am Chem Soc 2011; 133:13323-36. [PMID: 21819106 DOI: 10.1021/ja109457j] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Results are presented of ab initio studies at levels MP2(full)/6-31G* and MP2(full)/6-311G** of the hydrolysis of trimethylaluminum (TMA, 1) to dimethylaluminumhydroxide (DMAH, 2) and of the intramolecular 1,2-elimination of CH(4) from 2 itself to form methylaluminumoxide 3, from its dimeric aggregate 4 to form hydroxytrimethyldialuminoxane 5 and dimethylcyclodialuminoxane 6, and from its TMA aggregate 7 to form 8 and/or 9, the cyclic and open isomers of tetramethyldialuminoxane, respectively. Each methane elimination creates one new Lewis acid site, and dimethylether is used as a model oxygen-donor molecule to assess the most important effects of product stabilization by Lewis donor coordination. It is found that the irreversible formation of aggregate 4 (ΔG(298) = -29.2 kcal/mol) is about three times more exergonic than the reversible formation of aggregate 7 (ΔG(298) = -9.9 kcal/mol), that the reaction free enthalpies for the formations of 5 (ΔG(298) = -9.0 kcal/mol) and 6 (ΔG(298) = -18.8 kcal/mol) both are predicted to be quite clearly exergonic, and that there is a significant thermodynamic preference (ΔG(298) = -7.2 kcal/mol) for the formation of 6 over ring-opening of 5 to hydroxytrimethyldialuminoxane 10. The mechanism for oligomerization is discussed based on the bonding properties of dimeric aggregates and involves the homologation of HO-free aluminoxane with DMAH (i.e., 9 to 13), and any initially formed hydroxydialuminoxane 10 is easily capped to trialuminoxane 13. Our studies are consistent with and provide support for Sinn's proposal for the formation of oligoaluminoxanes, and in addition, the results point to the crucial role played by the kinetic stability of 5 and the possibility to form cyclodialuminoxane 6. Dialuminoxanes 9 and 10 are reversed-polarity heterocumulenes, and intramolecular O→Al dative bonding competes successfully with Al complexation by Lewis donors. Intramolecular O→Al dative bonding is impeded in cyclodialuminoxane 6, and the dicoordinate oxygen in 6 is a strong Lewis donor. Ethylene polymerization catalysts contain highly oxophilic transition metals, and our studies suggest that these transition metal catalysts should discriminate strongly in favor of cycloaluminoxane-O donors even if these are present only in small concentrations in the methylaluminoxane (MAO) cocatalyst.
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Affiliation(s)
- Rainer Glaser
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States.
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49
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Busico V. Metal-catalysed olefin polymerisation into the new millennium: a perspective outlook. Dalton Trans 2009:8794-802. [PMID: 19826709 DOI: 10.1039/b911862b] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The second half of the last Century is often referred to as 'the Age of Plastics'. Whether this calls to one's mind the 1963 Nobel Laureates Karl Ziegler and Giulio Natta, or "The Graduate" Ben Braddock of Charles Webb's novel (played by Dustin Hoffman in a 1967 cult movie) being explained that "the future is in plastics", the conclusion can only be that there is indeed some truth in the definition. But that is over now, and the new Millennium has much more and better to offer than 'plastics'--or not? This perspective article will not address such an epochal question; more modestly, it will make the point that--at odds with a growing misconception--there is still room for good and useful research in metal-catalysed olefin polymerisation for quite some years to come.
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Affiliation(s)
- Vincenzo Busico
- Laboratory of Stereoselective Polymerizations, Paolo Corradini Department of Chemistry, Federico II University of Naples, Via Cintia, 80126, Naples, Italy.
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