DFT study of formation and properties of dinuclear zirconocene cations: Effects of ligand structure, solvent, and metal on the dimerization process

Meelua, Wijitra; Keawkla, Natchayatorn; Oláh, Julianna; Jitonnom, Jitrayut

doi:10.1016/j.jorganchem.2019.121024

Cited by 8 publications

(11 citation statements)

References 44 publications

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“…In earlier work, several limiting conformers were located for dinuclear cations of this type with the stability of the syn isomers ( φ < 90°) vs. the anti conformers ( φ > 90°) being dependent on ligand structure in gas phase. 15,50 Thus, the X-ray structure more closely resembles the situation in gas or condensed phase of an isolated cation, while our DFT results suggest that close contact of anion and cation induces a conformational change in the latter.…”

Section: Resultsmentioning

confidence: 52%

Thermodynamics of metallocene catalyst activation: alignment of theory and experiment

Linnolahti

Collins

2022

Dalton Trans.

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Section: Resultsmentioning

confidence: 52%

Thermodynamics of metallocene catalyst activation: alignment of theory and experiment

Linnolahti

Collins

2022

Dalton Trans.

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“…It is known from solution NMR work that the μ‐CH 3 group is approximately sp 2 hybridized based on the magnitude of 1 J CH [3,13b–c] . Recently, DFT calculations on a wide variety of complexes 2 confirm these experimental details [37] …”

Section: Resultsmentioning

confidence: 83%

“…[3,13b-c] Recently, DFT calculations on a wide variety of complexes 2 confirm these experimental details. [37] On the other hand, as reported elsewhere for adducts of [(η 5 -Cp) 3 Zr][MeB(C 6 F 5 ) 3 ] with either Cp 2 ZrCl 2 or (η 5 -Cp) 3 ZrCl the ZrÀ ClÀ Zr linkage is bent to varying degrees at Cl. [38] In this work we examined the structure of these complexes at the M06-2X/TZVP level of theory and determined two stable geometries for complexes 2, gauche and syn-periplanar, as shown in Scheme 3.…”

Section: Structure Of Dinuclear Ions 2 5 Andmentioning

confidence: 74%

Activation of Substituted Metallocene Catalysts Using Methylaluminoxane

Collins

Linnolahti

2022

ChemCatChem

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Activation of the metallocene complexes (n-C 4 H 9 -(η 5 -C 5 H 4 )) 2 ZrCl 2 (BuCp 2 ZrCl 2 ) and rac-1,2-ethylenebis(1-η 5 -C 9 H 6 )ZrCl 2 (EBIZrCl 2 ) using methylaluminoxane (MAO) was investigated by electrospray ionization mass spectrometry (ESI-MS). Formation of dinuclear complexes at low Al : Zr ratios, which is accompanied by catalyst deactivation, occurs in the former case. In contrast, this behavior was not observed at similar Al : Zr ratios in the case of the EBIZrCl 2 complex. Both active [BuCp 2 ZrMe 2 AlMe 2 ][MAO(Me)] 3 and deactivated [(BuCp 2 Zr) 2 (μ-CH 2 )μ-Cl][MAO(Me)] 9 complexes were detected in leaching experiments using a SiO 2 -MAO-supported BuCp 2 ZrCl 2 catalyst and excess MAO. DFT studies of the structure and UV-Vis spectra calculated for the dinuclear cations 9 detected by ESI-MS suggest that these species may account for long-wavelength absorption seen in experimental spectra of complexes like BuCp 2 ZrCl 2 upon activation with MAO.

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“…The effective core potential double-ζ basis set (LANL2DZ) [32] was used for La atom and a double-ζ basis set, 6-31G(d), for all non-metal atoms (C, H, O). The DFT/mixed basis set method has been widely adopted for transition metal complexes [33][34][35][36]. Vibrational frequencies analyzed on the optimized geometries are used to confirm the transition state(s) and other intermediates and to estimate the zeropoint vibrational energies and thermal corrections to the Gibbs free energies (G) at the experimental temperature and pressure (363.15 K and S C H E M E 1 Previously proposed mechanism for the ROP of l-lactide (LLA) initiated by La(OTMP) 3 (-OTMP = 2,4,6-trimethylphenolate) as suggested by Yu et al [6].…”

Section: Methodsmentioning

confidence: 99%

Mechanism of ring‐opening polymerization of l‐lactide by lanthanide aryloxide: A theoretical study on the effect of the aryloxide ligands on the process

Meelua

Wanjai

Chokbunpiam

et al. 2023

Int J of Quantum Chemistry

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A detailed mechanistic study of ring‐opening polymerization (ROP) of l‐lactide by a lanthanum aryloxide complex, La(OTMP)3 (−OTMP = 2,4,6‐trimethylphenolate), is carried out using DFT theoretical calculations. Both initiation and propagation steps were considered. The calculations reveal the two‐step coordination‐insertion mechanism, proceeding via an unprecedented lanthanum π‐arene intermediate, with the selective acyl‐oxygen bond scission of the monomer. The first step of phenolate insertion into the La − O bond of the initiator is rate‐limiting, and the bulkiness of the aryloxide ligand initiates the ROP slowly with the activation energy of 19.3 kcal mol−1, in consistent with the activation energy (15 kcal mol−1) obtained with previous kinetic experiment. Furthermore, a rationale for the broadening of molecular weight distribution reported in this initiating system is also provided.

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DFT study of formation and properties of dinuclear zirconocene cations: Effects of ligand structure, solvent, and metal on the dimerization process

Cited by 8 publications

References 44 publications

Thermodynamics of metallocene catalyst activation: alignment of theory and experiment

Thermodynamics of metallocene catalyst activation: alignment of theory and experiment

Activation of Substituted Metallocene Catalysts Using Methylaluminoxane

Mechanism of ring‐opening polymerization of l‐lactide by lanthanide aryloxide: A theoretical study on the effect of the aryloxide ligands on the process

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