Rationalizing the catalytic performance of Cr(III) complexes stabilized with alkylphosphanyl PNP ligands for selective ethylene tri-/tetramerization: a DFT study

Fan, Haonan; Alam, Fakhre; Hao, Biao‐Biao; Ma, Jing; Zhang, Jingyi; Zhi, Ma; Jiang, Tao

doi:10.1007/s00214-022-02887-5

Cited by 4 publications

(4 citation statements)

References 23 publications

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“…These results were consistent with the observation of Blann et al, who reported the temperature impact on the selectivity of 1-C 6 and 1-C 8 for PCNP/Cr tetramerization systems . Coupling with the probable reaction mechanism, it is believed that the stability of the formed metallacycloheptane intermediate was poor at high temperature, and β-hydride transfer and reductive elimination of metallacycloheptane were more favored than further ethylene insertion …”

Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

“…46 Coupling with the probable reaction mechanism, it is believed that the stability of the formed metallacycloheptane intermediate was poor at high temperature, and β-hydride transfer and reductive elimination of metallacycloheptane were more favored than further ethylene insertion. 47 Then, the Al/Cr molar ratios (500, 600, 700, and 800) were optimized for the complex 7/MAO system at 45 °C and 45 bar, as shown in Figure 3. A trend of catalytic activity first increasing and then decreasing was observed.…”

Section: Effects Of Reaction Parameters On Ethylenementioning

confidence: 99%

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Chromium-Based Complexes Bearing Aminophosphine and Phosphine–Imine–Pyrryl Ligands for Selective Ethylene Tri/Tetramerization

Liu

Liu²,

Yang³

et al. 2023

ACS Omega

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A series of Cr-based complexes 6−10 bearing aminophosphine (P,N) ligands Ph 2 P−L−NH 2 [L = CH 2 CH 2 (1), L = CH 2 CH 2 CH 2 (2), and L = C 6 H 4 CH 2 (3)] and phosphine−imine− pyrryl (P,N,N) ligands 2-(Ph 2 P−L−N�CH)C 4 H 3 NH [L = CH 2 CH 2 CH 2 ( 4) and L = C 6 H 4 CH 2 (5)] were prepared, and their catalytic properties were examined for ethylene tri/tetramerization. Xray crystallographic analysis of complex 8 indicated the κ 2 -P,N bidentate coordination mode at the Cr(III) center and the distorted octahedral geometry of monomeric P,N−CrCl 3 . Upon activation by methylaluminoxane (MAO), complexes 7−8 bearing P,N (PC 3 N backbone) ligands 2−3 showed good catalytic reactivity for ethylene tri/tetramerization. On the other hand, complex 6 bearing the P,N (PC 2 N backbone) ligand 1 was found active for non-selective ethylene oligomerization, while complexes 9−10 bearing P,N,N ligands 4−5 only produced polymerization products. In particular, the high catalytic activity of 458.2 kg/(g•Cr•h), excellent selectivity of 90.9% (1-hexene and 1-octene combined), and extremely low PE content of 0.1% were obtained with complex 7 in toluene at 45 °C and 45 bar. These results suggest that rational control of P,N and P,N,N ligand backbones, including a carbon spacer and rigidity of a carbon bridge, can lead to the high-performance catalyst for the ethylene tri/tetramerization process.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Effects Of Reaction Parameters On Ethylenementioning

confidence: 99%

See 1 more Smart Citation

Chromium-Based Complexes Bearing Aminophosphine and Phosphine–Imine–Pyrryl Ligands for Selective Ethylene Tri/Tetramerization

Liu

Liu²,

Yang³

et al. 2023

ACS Omega

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show abstract

“…A special phosphine ligand was invented to stabilise WRCs 5,[7][8][9][10] during catalysis and to increase the rigidity of the ligand backbone for chromophores. [11][12][13] The electronic and steric effects of the substituents on the phosphine ligand have an influence on the auxiliary ligands and their transition metal complexes: electronegative substituents lower the energy gap of the anti-binding s*-orbitals, benefitting p-acceptor properties.…”

Section: A Introductionmentioning

confidence: 99%