Ein neuer Zugang zur Carben‐Chemie

Wanzlick, Hans‐Werner; Schikora, Eberhard

doi:10.1002/ange.19600721409

Cited by 236 publications

(114 citation statements)

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“…The halogen precursors of the latter dissociate spontaneously into the cyclic cation Since the pioneering studies of Wanzlick on nucleophilic and a halide anion [17] . In contrast, Arduengo-type carbenes carbenes [1] , their successful isolation as stable species bewith Group IIIa elements are as yet unknown. If these came prominent in the reports of Arduengo et al [2] [3] on compounds are considered as being isoelectronic with the the imidazo-2-ylidene, 1 (E ϭ C).…”

mentioning

confidence: 94%

Isoelectronic Arduengo-Type Carbene Analogues with the Group IIIa Elements Boron, Aluminum, Gallium, and Indium

Sundermann

Reiher

Schoeller³

1998

Eur. J. Inorg. Chem.

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confidence: 94%

Isoelectronic Arduengo-Type Carbene Analogues with the Group IIIa Elements Boron, Aluminum, Gallium, and Indium

Sundermann

Reiher

Schoeller³

1998

Eur. J. Inorg. Chem.

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“…The synthesis, characterization, and structural parameters of M(cod) complexes (M = Rh, Ir) of general structures I and II are discussed. Additionally, we report an unusual dinuclear, diamagnetic bis-ruthenium(III) species, having both a neutral C NHC -NH 2 Crystals of both 1 and 2, suitable for X-ray diffraction, were grown from slow vapor diffusion of pentane into a THF solution. The solid-state structure of 1, which is isostructural with 2, is shown in Figure 2.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Synthesis 2 ], [RuCp*(cod)Cl]), bases (KOtBu, NaH, NaHMDS), approaches (ligand deprotonated, deprotonated in situ or via silver complex), solvents, additives, and reaction conditions were attempted. In almost all cases, an inseparable or decomposed product mixture was found, and in many cases the cod signals were missing.…”

Section: ■ Introductionmentioning

confidence: 99%

Charge-Delocalized κ²C,N-NHC-Amine Complexes of Rhodium, Iridium, and Ruthenium

et al. 2014

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The development of a novel set of complexes bearing an NHC-amine ligand (C NHC -NH 2 ) is described. M(cod) complexes (M = Ir, Rh) and a Ru complex have been synthesized in which three different coordination modes of the ligand were established: monodentate, neutral bidentate, and anionic bidentate. The anionic bidentate coordination mode of the anionic C NHC -NH − ligand arises from deprotonation of the amine moiety of the neutral C NHC -NH 2 ligand. Ligand deprotonation proved to be reversible for the Rh and Ir complexes, as was shown by subsequent treatment of the complexes with base and acid. The structural parameters of these differently coordinated ligands were examined, and it was shown that the conjugation of the aniline ring plays a major role in determining the ligand properties. ■ INTRODUCTIONThe use of carbenes as ligands is well developed in the field of transition-metal complex chemistry.1 In particular, the Nheterocyclic carbene (NHC) class of imidazol-2-ylidines, first reported in the 1960s, 2 have received their fair share of attention. Many successful examples of the application of NHCs in transition-metal-catalyzed transformations such as hydrogenations and metathesis reactions 3−5 have been reported. We recently reported on the synthesis of a conjugated NHC-amine ligand species where an NHC is conjugated with an aniline (C NHC -NH 2 ). 6 In this species, the primary amine is tethered to the NHC via an aromatic ring. The amine moiety of our C NHC -NH 2 ligand A (see Figure 1) can coordinate in a neutral or in an anionic fashion (when deprotonated). Monoanionic (bidentate) ligands have found widespread application in homogeneous catalysis. The most recognized are (pentamethyl)cyclopentadienyl (Cp, Cp*), acetylacetonate (acac), and diketimine (nacnac, where the two oxygen atoms of acac have been replaced by nitrogen-based moieties of the form NR). 7,8 Well-known examples of bifunctional ligands are ligands containing hydroxyl or oxime 9 groups and pincer-type ligands containing an anionic donor arm. 10,11 Previous work by Morris, involving a benzylic amine tethered to an NHC, has shown the ability of this ligand scaffold to display cooperativity, but this depended greatly on other factors such as the ancillary ligand (p-cym vs Cp*) and solvent assistance.12 Morris also explored the potential of iridium(I)-cod complexes containing neutral bidentate NHC-benzylic amine ligands, coordinated as seven-membered chelate rings to the metal center. Anilinebased C NHC -NH 2 ligands, forming neutral complexes containing conjugated anionic C NHC -NH − ligands bound to Rh, Ir, or

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“…Beginning in 1960 Wanzlick reported the chemistry of imidazolines and (to a lesser extent) imidazoles in the quest for stable carbenes. [5] Unfortunately, Wanzlick's efforts were contemporaneous with other rather spectacular experimental mishaps that laid false claims to the isolation of simple singlet carbenes. [6] Wanzlick's experiments were perhaps nearly capable of producing a 'bottle-able' carbene, [7] but the scientific environment and culture in his time was still not welcoming to his views.…”

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confidence: 99%

N-Heterocyclic Carbenes

Arduengo¹

2011

Aust. J. Chem.

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Ein neuer Zugang zur Carben‐Chemie

Cited by 236 publications

References 1 publication

Isoelectronic Arduengo-Type Carbene Analogues with the Group IIIa Elements Boron, Aluminum, Gallium, and Indium

Isoelectronic Arduengo-Type Carbene Analogues with the Group IIIa Elements Boron, Aluminum, Gallium, and Indium

Charge-Delocalized κ²C,N-NHC-Amine Complexes of Rhodium, Iridium, and Ruthenium

N-Heterocyclic Carbenes

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Ein neuer Zugang zur Carben‐Chemie

Cited by 236 publications

References 1 publication

Isoelectronic Arduengo-Type Carbene Analogues with the Group IIIa Elements Boron, Aluminum, Gallium, and Indium

Isoelectronic Arduengo-Type Carbene Analogues with the Group IIIa Elements Boron, Aluminum, Gallium, and Indium

Charge-Delocalized κ2C,N-NHC-Amine Complexes of Rhodium, Iridium, and Ruthenium

N-Heterocyclic Carbenes

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Charge-Delocalized κ²C,N-NHC-Amine Complexes of Rhodium, Iridium, and Ruthenium