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This paper reports a computational study on the specific 1,4‐cis polymerization of butadiene catalyzed by the cationic gadolinium metallocene [(C5Me5)2Gd][B(C6F5)4] combined with excess amount of Al(iBu)3. Because this reaction system has no initial Gd–alkyl bond, a mechanism with conventional coordinative chain transfer polymerization (CCTP) is not feasible. Density functional theory (DFT) analyses indicate a novel mechanism in which the cationic Gd plays a crucial role by assisting butadiene insertion into one of the Al−C bond of Al(iBu)3. The proposed butadiene polymerization mechanism can account for the specific 1,4‐cis selectivity of this catalyst system. [ABSTRACT FROM AUTHOR]

The cationic gadolinium metallocene [(C5Me5)2Gd][B(C6F5)4], when combined with an excess amount of Al(iBu)3, efficiently produces polyethylene at 80 °C under 0.8 MPa pressure of ethylene. After quenching, the resulting polyethylene has ethyl group at one end and isobutyl group at the other terminal. Because no Gd‐alkyl species appears to be involved, a mechanism with conventional coordinative chain transfer polymerization (CCTP) is not feasible. Density functional theory (DFT) analyses indicate a novel mechanism in which the cationic Gd plays a crucial role by coordinating ethylene and assists the insertion of the coordinated ethylene into Al−C bond. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) analysis indicates a mechanism in which cationic Gd assists butadiene insertion into one of the Al-C bonds of Al( SP I i i sp Bu) SB 3 sb , explaining the 1,4- I cis i selectivity unique to this catalytic system. Keywords: Lanthanides; Alkylaluminum; Butadiene polymerization; Reaction mechanisms; DFT study EN Lanthanides Alkylaluminum Butadiene polymerization Reaction mechanisms DFT study 1 1 1 12/06/22 20221201 NES 221201 B A novel mechanism for the polymerization of butadiene b by cationic gadolinium metallocene in the presence of excess Al( SP I i i sp Bu) SB 3 sb is presented. Front Cover: Non- -Allyl Mechanism for the 1,4-cis-Butadiene Polymerization: Theoretical Study of Polymerization via Insertion of Butadiene into Al-C Bond with Cationic Gadolinium Metallocene. [Extracted from the article]

Abstract: The Ni-methyl complex (η5-C5H5)Ni(CH3)(PPh3) (1) reacted with B(C6F5)3 to give an unstable contact ion-pair complex with a μ-methyl bridge between the Ni and B atoms. Formation of the B-CH3 bond was confirmed by the reaction of this complex with PPh3 to give [(η5-C5H5)Ni(PPh3)2][B(CH3)(C6F5)3] which was structurally characterized. Spontaneous decomposition of the contact ion-pair complex yielded (η5-C5H5)Ni(C6F5)(PPh3) which is very stable and does not show any reactions with norbornene with or without added B(C6F5)3. 19F NMR study showed that the polynorbornene obtained by the catalysis of 1/B(C6F5)3 system has the C6F5 end-group. A series of reactions, which includes CH3/C6F5 exchange between the Ni and B centers with concomitant dissociation of PPh3 to accept coordination of a norbornene monomer, is proposed as the route to active species that can initiate vinyl polymerization of norbornene. [Copyright &y& Elsevier]

This paper reports a computational study on the specific 1,4-cis polymerization of butadiene catalyzed by the cationic gadolinium metallocene [(C 5 Me 5 ) 2 Gd][B(C 6 F 5 ) 4 ] combined with excess amount of Al( i Bu) 3 . Because this reaction system has no initial Gd-alkyl bond, a mechanism with conventional coordinative chain transfer polymerization (CCTP) is not feasible. Density functional theory (DFT) analyses indicate a novel mechanism in which the cationic Gd plays a crucial role by assisting butadiene insertion into one of the Al-C bond of Al( i Bu) 3 . The proposed butadiene polymerization mechanism can account for the specific 1,4-cis selectivity of this catalyst system., (© 2022 Wiley-VCH GmbH.)

The cationic gadolinium metallocene [(C 5 Me 5 ) 2 Gd][B(C 6 F 5 ) 4 ], when combined with an excess amount of Al( i Bu) 3 , efficiently produces polyethylene at 80 °C under 0.8 MPa pressure of ethylene. After quenching, the resulting polyethylene has ethyl group at one end and isobutyl group at the other terminal. Because no Gd-alkyl species appears to be involved, a mechanism with conventional coordinative chain transfer polymerization (CCTP) is not feasible. Density functional theory (DFT) analyses indicate a novel mechanism in which the cationic Gd plays a crucial role by coordinating ethylene and assists the insertion of the coordinated ethylene into Al-C bond., (© 2021 Wiley-VCH GmbH.)