PNPN‐H in Comparison to other PNP, PNPN and NPNPN Ligands for the Chromium Catalyzed Selective Ethylene Oligomerization

Rosenthal, Uwe

doi:10.1002/cctc.201902111

Cited by 29 publications

(15 citation statements)

References 54 publications

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“…Other results revealed mononuclear chromacycles for tetramerization to 1‐octene [19a–d] . At least the possible and realistic mechanism always depends on the particular nature of the ligands used [17b] …”

Section: Catalytic Ethylene Oligomerizationmentioning

confidence: 99%

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Contributions of Erhard Kurras to Organochromium Chemistry – From a Historical Perspective

Rosenthal

Schulz

2021

Eur J Inorg Chem

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Starting from the fundamental organometallic research work of Franz Hein, Erhard Kurras investigated the possibility of isolating stable organochromium compounds. He studied the existence of σ‐alkyl and σ‐alkylene complexes, π‐allyl compounds, as well as dichromium complexes containing a chromium‐chromium quadruple bond. Since that time a variety of organochromium compounds have been developed by the scientific community. In this article, we highlight the scientific work of Erhard Kurras by using selected examples. Most of these examples represent very important contributions to the field of chromium complex chemistry, as they were completely new at that time in terms of bonding, activation of small molecules, and finally catalytic behavior. We believe that Kurras's fundamental work has opened a new chapter in organometallic chemistry.

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Section: Catalytic Ethylene Oligomerizationmentioning

confidence: 99%

“… [17c] It is reasonable to assume that a mechanism similar to that previously described for the cyclotetramerization of acetylene to cyclooctatetraene via a binuclear center may be responsible for the selective ethylene tetramerization to 1‐octene (Scheme 14). [17a,b,d] …”

Section: Catalytic Ethylene Oligomerizationmentioning

confidence: 99%

Contributions of Erhard Kurras to Organochromium Chemistry – From a Historical Perspective

Rosenthal

Schulz

2021

Eur J Inorg Chem

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“…23 , 24 Importantly, this catalytic cycle is consistent with several experimental studies, 25,26,27,28,29 including deuterium labeling experiments. 4,5,30,31,32,33 Scheme 2. The black arrows outline the lowest energy catalytic cycle for (P,N)Cr-catalyzed ethylene trimerization to 1-hexene.…”

Section: -Hexene Catalytic Mechanism and Mechanisms To Give Alternative C6 Productsmentioning

confidence: 99%

Computational Assessment and Understanding of C6 Product Selectivity for Chromium Phosphinoamidine Catalyzed Ethylene Trimerization

Ess

Morgan

Maley

et al. 2021

Preprint

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One approach to selectively generate 1-hexene is through ethylene trimerization using highly active Cr N-phosphinoamidine catalysts ((P,N)Cr). Depending on the ligand, (P,N)Cr catalysts can either generate nearly pure 1-hexene or form 1-hexene with significant mixtures of other C6 mass products, for example methylenecyclopentane. Here we report DFT transition state modeling examining 1-hexene catalysis pathways as well as pathways that lead to alternative C6 mass products. This provided qualitative and semi-quantitative modeling of the experimental 1-hexene purity values for several (P,N)Cr catalysts. Consistent with previous computational studies, the key 1-hexene purity-determining transition states were determined to be β-hydrogen transfer structures from the metallacycloheptane intermediate. The origin of selectivity for these (P,N)Cr catalysts can be attributed to steric effects in the transition-state structure with coordinated ethylene that leads to C6 impurities.

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“…Along with the development of the general pincer concept, amidophosphine hybrid ligands, combining hard nitrogen donors and soft phosphines within a tailor‐made ligand framework, have emerged in coordination chemistry. Out of the numerous known P x N y amidophosphines, monoanionic PNP ligands stand out as being well‐suited not only for the complexation of transitions metals, but also for coordinating f‐block and main group elements …”

Section: Introductionmentioning

confidence: 99%

Phosphines and N‐Heterocycles Joining Forces: an Emerging Structural Motif in PNP‐Pincer Chemistry

2020

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Aminodiphosphines and their monoanionic amido derivatives are among the most widely used tridentate ligands. A good share of these ligands, in particular the ones that are based on a rigid N‐heterocyclic core, is predisposed to coordinate in a meridional fashion. Negatively charged derivatives of these meridionally coordinating N‐heterocyclic ligands satisfy all the criteria for PNP pincer scaffolds. Herein, these ligands and their coordination chemistry is reviewed from the perspective of coordination chemistry. For our discussion, ligands containing a protonated N‐heterocycle (e.g. pyrrole‐ or carbazole‐based PNP scaffolds) are to be distinguished from their counterparts that do not contain such an NH‐functionality (e.g. pyridine‐ or triazine‐based PNP scaffolds). Different synthetic methodologies for the preparation of PNP pincer complexes are presented and shown to often depend on the presence or absence of the aforementioned NH‐proton. The different reactivity patterns of the resulting complexes are sub‐divided into two categories, namely into metal‐centered reactions and reactions that result in a chemical transformation at the metal and the ligand. The latter represent ligand‐cooperative transformations, which often play a key role in catalysis, and are showcased by discussing selected applications in catalysis. It will become evident in this review that this relatively young research field is still emerging and far from reaching maturity. Finally, a brief overview on ligand/metal combinations that have not been explored to date is provided, to stimulate future research on PNP pincers featuring a central N‐heterocycle.

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PNPN‐H in Comparison to other PNP, PNPN and NPNPN Ligands for the Chromium Catalyzed Selective Ethylene Oligomerization

Cited by 29 publications

References 54 publications

Contributions of Erhard Kurras to Organochromium Chemistry – From a Historical Perspective

Contributions of Erhard Kurras to Organochromium Chemistry – From a Historical Perspective

Computational Assessment and Understanding of C6 Product Selectivity for Chromium Phosphinoamidine Catalyzed Ethylene Trimerization

Phosphines and N‐Heterocycles Joining Forces: an Emerging Structural Motif in PNP‐Pincer Chemistry

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