A crystalline C5-protonated 1,3-imidazol-4-ylidene

Rottschäfer, Dennis; Glodde, Timo; Neumann, Beate; Stammler, Hans‐Georg; Ghadwal, Rajendra S.

doi:10.1039/c9cc09428h

Cited by 35 publications

(37 citation statements)

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“… [4c] The C2–Se1 bond length and N1‐C2‐C3 bond angle of 6 a (1.856(2) Å, 104.8(1)°) (Figure 2) are comparable with that of( 2 a )Se (1.859(2) Å, 104.3(1)°) [4c] . The C2–Au1 bond lengths and the N1‐C2‐C3 bond angles of 7 (1.983(2) Å/104.3(1)°) and ( 2 g )AuCl (2.008(4) Å)/(102.5(1)°) [12a] are fully consistent. The C2–Pd1 bond length of 8‐H (2.042(2) Å) is slightly larger compared to those of other iMIC‐Pd complexes (1.955(2)–2.030(2) Å), [13c] which may be due to steric reason [18] …”

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confidence: 55%

Nickel‐Catalyzed Intramolecular 1,2‐Aryl Migration of Mesoionic Carbenes (iMICs)

et al. 2020

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Intramolecular 1,2‐Dipp migration of seven mesoionic carbenes (iMICAr) 2 a–g (iMICAr=ArC{N(Dipp)}2CHC; Ar=aryl; Dipp=2,6‐iPr2C6H3) under nickel catalysis to give 1,3‐imidazoles (IMDAr) 3 a–g (IMDAr=ArC{N(Dipp)CHC(Dipp)N}) has been reported. The formation of 3 indicates the cleavage of an N−CDipp bond and the subsequent formation of a C−CDipp bond in 2, which is unprecedented in NHC chemistry. The use of 3 in accessing super‐iMICs (5) (S‐iMIC=ArC{N(Dipp)N(Me)C(Dipp)}C) has been shown with selenium (6), gold (7), and palladium (8) compounds. The quantification of the stereoelectronic properties reveals the superior σ‐donor strength of 5 compared to that of classical NHCs. Remarkably, the percentage buried volume of 5 (%Vbur=45) is the largest known amongst thus far reported iMICs. Catalytic studies show a remarkable activity of 5, which is consistent with their auspicious stereoelectronic features.

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Section: Figuresupporting

confidence: 55%

Nickel‐Catalyzed Intramolecular 1,2‐Aryl Migration of Mesoionic Carbenes (iMICs)

et al. 2020

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“…Attempts to prepare the free carbene ligand Dpt‐MIC (Dpt=diphenyltriazinyl) by reaction of 1 with potassium bis(trimethylsilyl) amide (KHMDS) were not successful. [ 66 , 67 ] The NMR spectrum of the reaction mixture recorded at room temperature was very complex, indicating decomposition of Dpt‐MIC. However, we were able to capture in situ generated Dpt‐MIC by coordination to RhCl(CO) 2 .…”

Section: Resultsmentioning

confidence: 99%

Tuning the π‐Accepting Properties of Mesoionic Carbenes: A Combined Computational and Experimental Study

Dong

Blaskovits

Fadaei‐Tirani

et al. 2021

Chemistry A European J

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Mesoionic imidazolylidenes are recognized as excellent electron‐donating ligands in organometallic and main group chemistry. However, these carbene ligands typically show poor π‐accepting properties. A computational analysis of 71 mesoionic imidazolylidenes that bear different aryl or heteroaryl substituents in C2 position was performed. The study has revealed that a diphenyltriazinyl (Dpt) substituent renders the corresponding carbene particularly π‐acidic. The computational results could be corroborated experimentally. A mesoionic imidazolylidene with a Dpt substituent was found to be a better σ‐donor and a better π‐acceptor compared to an Arduengo‐type N‐heterocyclic carbene. To demonstrate the utility of the new carbene, the ligand was used to stabilize a low‐valent paramagnetic tin compound.

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“… [4c] Die C2‐Se1‐Bindungslänge und der N1‐C2‐C3‐Winkel von 6 a (1.856(2) Å, 104.8(1)°) (Abbildung 2) sind gut mit ( 2 a )Se (1.859(2) Å, 104.3(1)°) vergleichbar [4c] . Die C2‐Au1‐Bindungslänge und der N1‐C2‐C3‐Winkel von 7 (1.983(2) Å, 104.3(1)°) und ( 2 g )AuCl (2.008(4) Å), (102.5(1)°) [12a] sind gut vergleichbar. Die C2‐Pd1‐Bindungslänge von 8‐H (2.042(2) Å) ist im Gegensatz zu anderen iMIC‐Pd‐Komplexen (1.955(2)–2.030(2) Å) [13c] leicht vergrößert, was durch den sterischen Anspruch von 5 begründet werden kann [18] …”

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Nickel‐katalysierte intramolekulare 1,2‐Aryl‐Wanderung von mesoionischen Carbenen (iMICs)

et al. 2020

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Die Ni‐katalysierte intramolekulare 1,2‐Verschiebung eines 2,6‐Diisopropylphenyl‐Substituenten (Dipp) von sieben mesoionischen Carbenen (iMICAr) 2 a–g (iMICAr=ArC{N(Dipp)}2CHC; Ar=Aryl) unter Bildung von 1,3‐Imidazolen (IMDAr) 3 a–g (IMDAr=ArC{N(Dipp)CHC(Dipp)N}) wird berichtet. Dieser Prozess impliziert die Spaltung einer N‐CDipp‐Bindung in 2 und die anschließende Knüpfung einer C‐CDipp‐Bindung, was in der NHC‐Chemie bislang unbekannt war. Die Überführung von 3 in Super‐iMICs (5) (S‐iMIC=ArC{N(Dipp)N(Me)C(Dipp)}C) wurde mit der Herstellung von Selen‐ (6), Gold‐(7) und Palladium‐Derivaten (8) gezeigt. Die Quantifizierung der stereoelektronischen Eigenschaften lässt hierbei eine deutliche Erhöhung der σ‐Donorstärke von 5 relativ zu klassischen NHCs erkennen. Bemerkenswert hierbei ist das “Buried Volume” von 5 (%Vbur=45), welches in iMICs dem bisher größten bekannten Wert entspricht. Katalytische Studien weisen auf eine hervorragende Aktivität von 5 hin, was mit den stereoelektronischen Eigenschaften der Liganden im Einklang ist.

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A crystalline C5-protonated 1,3-imidazol-4-ylidene

Abstract: The first C5-protonated 1,3-imidazole-based mesoionic carbene (iMICBp) has been isolated and characterized by single-crystal X-ray diffraction.

Cited by 35 publications

References 77 publications

Nickel‐Catalyzed Intramolecular 1,2‐Aryl Migration of Mesoionic Carbenes (iMICs)

Nickel‐Catalyzed Intramolecular 1,2‐Aryl Migration of Mesoionic Carbenes (iMICs)

Tuning the π‐Accepting Properties of Mesoionic Carbenes: A Combined Computational and Experimental Study

Nickel‐katalysierte intramolekulare 1,2‐Aryl‐Wanderung von mesoionischen Carbenen (iMICs)

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