PCNCP Ligands in the Chromium‐Catalyzed Oligomerization of Ethylene: Tri‐ versus Tetramerization

Klemps, Christian; Payet, Elina; Magna, Lionel; Saussine, Lucien; Goff, Xavier F. Le; Floch, Pascal Le

doi:10.1002/chem.200900986

Cited by 69 publications

(55 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…9,19 Encouraged by this finding, introduction of a carbon linkage between the pyridine and the aminophosphine fragments was endeavored for 1−3, affording the analogous ligands 4−6 (Scheme 4). These ligands were then reacted with CrCl 3 (THF) 3 to afford corresponding chromium complexes.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Selective Ethylene Oligomerization with Chromium Complexes Bearing Pyridine–Phosphine Ligands: Influence of Ligand Structure on Catalytic Behavior

et al. 2014

View full text Add to dashboard Cite

show abstract

Section: ■ Results and Discussionmentioning

confidence: 99%

Selective Ethylene Oligomerization with Chromium Complexes Bearing Pyridine–Phosphine Ligands: Influence of Ligand Structure on Catalytic Behavior

et al. 2014

View full text Add to dashboard Cite

show abstract

“…11–16 The elimination step may involve either a β -hydride elimination/reduction elimination sequence or a concerted 3,7-hydride shift; it is difficult to distinguish between these alternatives, 13 but the latter is favored by recent theoretical studies. 15–17 Whichever mechanism operates, the elimination is expected on geometric grounds to be much more favorable, relative to further insertion, for the seven-membered rather than for the five-membered metallacycle, accounting for the observed selectivity. With some catalysts, and especially at higher ethylene pressures, a second insertion becomes favored over elimination, yielding 1-octene.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Studies of Ethylene and α-Olefin Co-Oligomerization Catalyzed by Chromium–PNP Complexes

Labinger

Bercaw

2012

Organometallics

View full text Add to dashboard Cite

To explore the possibility of producing a narrow distribution of mid- to long-chain hydrocarbons from ethylene as a chemical feedstock, co-oligomerization of ethylene and linear α-olefins (LAOs) was investigated, using a previously reported chromium complex, [CrCl3(PNPOMe)] (1, where PNPOMe = N,N-bis(bis(o-methoxyphenyl)phosphino)methylamine). Activation of 1 by treatment with modified methylaluminoxane (MMAO) in the presence of ethylene and 1-hexene afforded mostly C6 and C10 alkene products. The identities of the C10 isomers, assigned by detailed gas chromatographic and mass spectrometric analyses, strongly support a mechanism that involves five- and seven-membered metallacyclic intermediates comprising of ethylene and LAO units. Using 1-heptene as a mechanistic probe, it was established that 1-hexene formation from ethylene is competitive with formation of ethylene/LAO co-trimers, and that co-trimers derived from one ethylene and two LAO molecules are also generated. Complex 1/MMAO is also capable of converting 1-hexene to C12 dimers and C18 trimers, albeit with poor efficiency. The mechanistic implications of these studies are discussed and compared to previous reports of olefin co-trimerization.

show abstract

“…Cr complex with a bidentate PCNCP ligand (Chart 5.5 5f) promotes ethylene trimerization upon activation with MAO (activity up to 9,783 g (g Cr) Table 5.2, run 9, 10) [92]. The ligand is coordinated by the Cr center in a P,P-bidentate form.…”

Section: Chromium Catalystmentioning

confidence: 99%

Oligomerization of Olefins

Takeuchi

Osakada

2014

Organometallic Reactions and Polymerization

View full text Add to dashboard Cite

This article reviews recent studies on oligomerization of olefins catalyzed by transition metal complexes. Ni, Pd, and Fe complexes, having a ligand with a similar structure to the ethylene polymerization catalyst but with less bulky substituents, convert ethylene to the oligomers as a mixture with various chain lengths with Schulz-Flory molecular weight distribution. Cossee-type insertion of ethylene into the M-C bond and frequent elimination of a-olefins are proposed as the major reaction mechanism. The reaction using the Fe catalyst for polymerization and large excess of chain transfer reagents such as ZnEt 2 can yield the oligomers with Poisson distribution. Cr complexes with various ligands promote selective trimerization and/or tetramerization of ethylene to produce 1-hexene and/ or 1-octene. The mechanism involving metallacycle is proposed to account for the selectivity. Several Ti and Ta complexes are also effective for the trimerization of ethylene. Oligomerization of a-olefins has been also studied, although the product is frequently composed of branched oligomers and/or inner olefins.

show abstract

PCNCP Ligands in the Chromium‐Catalyzed Oligomerization of Ethylene: Tri‐ versus Tetramerization

Cited by 69 publications

References 59 publications

Selective Ethylene Oligomerization with Chromium Complexes Bearing Pyridine–Phosphine Ligands: Influence of Ligand Structure on Catalytic Behavior

Selective Ethylene Oligomerization with Chromium Complexes Bearing Pyridine–Phosphine Ligands: Influence of Ligand Structure on Catalytic Behavior

Mechanistic Studies of Ethylene and α-Olefin Co-Oligomerization Catalyzed by Chromium–PNP Complexes

Oligomerization of Olefins

Contact Info

Product

Resources

About