Preparation

Sneeden, R. P. A.

doi:10.1016/b978-0-12-653850-2.50005-8

Cited by 1 publication

(2 citation statements)

References 235 publications

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“…Complex 4 has relatively long Cr–C and Cr–O bonds compared to the other precursors (vide supra), a possible explanation for faster initiation. Importantly, we found that a known Cr tris(aryl) precursor ( 6 , Cr( o -(Et 2 NCH 2 )-C 6 H 4 ) 3 ) stabilized by pendant amines was not a viable precatalyst. No oligomers were observed following stoichiometric activation of 6 .…”

Section: Resultsmentioning

confidence: 92%

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Robust Chromium Precursors for Catalysis: Isolation and Structure of a Single-Component Ethylene Tetramerization Precatalyst

2019

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We have introduced a new class of stable organometallic Cr reagents (compounds 1-4) that are readily prepared, yet reactive enough to serve as precursors. They were used for ethylene tetramerization catalysis following stoichiometric activation by in situ protonation. This study highlights the importance of balancing stability with reactivity in generating an organometallic precursor that is useful in catalysis. Moreover, precursor 4 allowed for the isolation and crystallographic characterization of a room-temperature stable cationic species, (PNP)CrR2 + (R = o-C6H4(CH2)2OMe, PNP = i PrN(PPh2)2). This complex (5) may be used as a single component precatalyst, without any alkyl aluminum reagents. This result provides an unprecedented level of insight into the kind of structures that must be produced from more complicated activation processes.

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Section: Resultsmentioning

confidence: 92%

“…This has been described previously, and is related to the dimethylamino-substituted version. , Our synthesis is as follows: N -(2-bromobenzyl)- N -ethylethanamine (0.288 g, 1.20 mmol) in 4 mL of THF was stirred over excess activated Mg turnings at room temperature. After several hours, Grignard formation was complete.…”

Section: Experimental Sectionmentioning

confidence: 99%