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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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Sian L, Dall’Anese A, Macchioni A, Tensi L, Busico V, Cipullo R, Goryunov GP, Uborsky D, Voskoboynikov AZ, Ehm C, Rocchigiani L, Zuccaccia C. Role of Solvent Coordination on the Structure and Dynamics of ansa-Zirconocenium Ion Pairs in Aromatic Hydrocarbons. Organometallics 2022. [DOI: 10.1021/acs.organomet.1c00653] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Leonardo Sian
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli studi di Perugia and CIRCC, Via Elce di sotto, 8, 06123 Perugia, Italy
- Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
| | - Anna Dall’Anese
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli studi di Perugia and CIRCC, Via Elce di sotto, 8, 06123 Perugia, Italy
- Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
| | - Alceo Macchioni
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli studi di Perugia and CIRCC, Via Elce di sotto, 8, 06123 Perugia, Italy
- Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
| | - Leonardo Tensi
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli studi di Perugia and CIRCC, Via Elce di sotto, 8, 06123 Perugia, Italy
| | - Vincenzo Busico
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Via Cintia, 80126 Napoli, Italy
- Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
| | - Roberta Cipullo
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Via Cintia, 80126 Napoli, Italy
- Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
| | - Georgy P. Goryunov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
- Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
| | - Dmitry Uborsky
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
- Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
| | - Alexander Z. Voskoboynikov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
- Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
| | - Christian Ehm
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Via Cintia, 80126 Napoli, Italy
- Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
| | - Luca Rocchigiani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli studi di Perugia and CIRCC, Via Elce di sotto, 8, 06123 Perugia, Italy
| | - Cristiano Zuccaccia
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli studi di Perugia and CIRCC, Via Elce di sotto, 8, 06123 Perugia, Italy
- Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
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Theoretical Study on Ethylene Polymerization Catalyzed by Half-Titanocenes Bearing Different Ancillary Groups. Catalysts 2021. [DOI: 10.3390/catal11111392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Half-titanocenes are well known to show high activity for ethylene polymerization and good capability for copolymerization of ethylene with other olefins, and the ancillary ligands can crucially affect the catalytic performance. In this paper, the mechanisms of ethylene polymerization catalyzed by three half-metallocenes, (η5-C5Me5)TiCl2(O-2,6-iPr2C6H3) (1), (η5-C5Me5)TiCl2(N=CtBu2) (2) and [Me2Si(η5-C5Me4)(NtBu)]TiCl2 (3), have been investigated by density functional theory (DFT) method. At the initiation stage, a higher free energy barrier was determined for complex 1, probably due to the presence of electronegative O atom in phenoxy ligand. At the propagation stage, front-side insertion of the second ethylene is kinetically more favorable than back-side insertion for complexes 1 and 2, while both side insertion orientations are comparable for complex 3. The energy decomposition showed that the bridged cyclopentadienyl amide ligand could enhance the rigidity of the active species as suggested by the lowest deformation energy derived from 3. At the chain termination stage, β-H transfer was calculated to be a dominant chain termination route over β-H elimination, presumably owing to the thermodynamic perspective.
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Zaccaria F, Zuccaccia C, Macchioni A. Hemi-metallocene Ti(IV) η3-allyl-type complexes: Structure, dynamics in solution and exploration of reactivity. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2021.120565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Edeleva M, Van Steenberge PH, Sabbe MK, D’hooge DR. Connecting Gas-Phase Computational Chemistry to Condensed Phase Kinetic Modeling: The State-of-the-Art. Polymers (Basel) 2021; 13:3027. [PMID: 34577928 PMCID: PMC8467432 DOI: 10.3390/polym13183027] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 09/02/2021] [Accepted: 09/03/2021] [Indexed: 02/06/2023] Open
Abstract
In recent decades, quantum chemical calculations (QCC) have increased in accuracy, not only providing the ranking of chemical reactivities and energy barriers (e.g., for optimal selectivities) but also delivering more reliable equilibrium and (intrinsic/chemical) rate coefficients. This increased reliability of kinetic parameters is relevant to support the predictive character of kinetic modeling studies that are addressing actual concentration changes during chemical processes, taking into account competitive reactions and mixing heterogeneities. In the present contribution, guidelines are formulated on how to bridge the fields of computational chemistry and chemical kinetics. It is explained how condensed phase systems can be described based on conventional gas phase computational chemistry calculations. Case studies are included on polymerization kinetics, considering free and controlled radical polymerization, ionic polymerization, and polymer degradation. It is also illustrated how QCC can be directly linked to material properties.
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Affiliation(s)
- Mariya Edeleva
- Laboratory for Chemical Technology (LCT), Ghent University, Technologiepark 125, 9052 Zwijnaarde, Belgium; (P.H.M.V.S.); (M.K.S.)
| | - Paul H.M. Van Steenberge
- Laboratory for Chemical Technology (LCT), Ghent University, Technologiepark 125, 9052 Zwijnaarde, Belgium; (P.H.M.V.S.); (M.K.S.)
| | - Maarten K. Sabbe
- Laboratory for Chemical Technology (LCT), Ghent University, Technologiepark 125, 9052 Zwijnaarde, Belgium; (P.H.M.V.S.); (M.K.S.)
- Industrial Catalysis and Adsorption Technology (INCAT), Ghent University, Valentin Vaerwyckweg 1, 9000 Ghent, Belgium
| | - Dagmar R. D’hooge
- Laboratory for Chemical Technology (LCT), Ghent University, Technologiepark 125, 9052 Zwijnaarde, Belgium; (P.H.M.V.S.); (M.K.S.)
- Centre for Textile Science and Engineering (CTSE), Ghent University, Technologiepark 70a, 9052 Zwijnaarde, Belgium
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