4-Oxo-2,3,5,6-tetrafluorocyclohexa-2,5-dienylidene—A Highly Electrophilic Triplet Carbene

Sander, Wolfram; Hübert, Rolf; Kraka, Elfi; Gräfenstein, Jürgen; Cremer, Dieter

doi:10.1002/1521-3765(20001215)6:24<4567::aid-chem4567>3.3.co;2-1

Cited by 15 publications

(29 citation statements)

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“…[11] Transient triplet carbenes, such as methylene, react with CO to give the corresponding ketenes. [12] In contrast, although the carbonylation of singlet carbenes is spin-allowed, there are very few examples of ketene formation using this route. [13] In 1994 it was claimed that the imidazol-2-ylidene 1 a reacts with carbon monoxide to give the stable diamino ketene 2 a (Scheme 1).…”

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confidence: 99%

CO Fixation to Stable Acyclic and Cyclic Alkyl Amino Carbenes: Stable Amino Ketenes with a Small HOMO–LUMO Gap

et al. 2006

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A quick fix: In contrast to cyclic diamino carbenes, stable alkyl amino carbenes react with CO to give stable ketenes (see scheme, top). Contrary to the acyclic versions, cyclic amino ketenes cannot escape from the destabilizing n–π donation of the nitrogen lone pair, which induces a diradical character and unusual optical (see scheme, bottom and photographs of crystals) and NMR spectroscopic properties.

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confidence: 99%

CO Fixation to Stable Acyclic and Cyclic Alkyl Amino Carbenes: Stable Amino Ketenes with a Small HOMO–LUMO Gap

et al. 2006

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“…Similarly, 4‐oxo‐2,3,5,6‐tetrafluorocyclohexadienylidene was isolated in matrix conditions (Fig. , 31 is a model of the known compound) . Many other CCCs are reported as ligands in transition metal‐coordinated species [3a] .…”

Section: Resultsmentioning

confidence: 99%

“…Most of the CCCs known in the literature are 3/4/5 and 7 membered, only a very few six‐membered CCCs are reported till now in the form of ligands to metal centers ( 30–32 , Fig. ) . 32 is the model of a known six‐membered CCC, which was also labeled as r NHC, and the Δ E S–T value for this species is ~0.9 kcal/mol marginally favoring singlet state.…”

Section: Resultsmentioning

confidence: 99%

Electronic and ligating properties of carbocyclic carbenes: A theoretical investigation

et al. 2018

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Carbocyclic carbenes (CCCs) are a class of nucleophilic carbenes which are very similar to N-heterocyclic carbenes (NHCs) in terms of their reactivity, but they do not contain a stabilizing heteroatom in their cyclic ring system. In this study, 17 representative known CCCs and 34 newly designed CCCs are evaluated using quantum chemical methods, and the results are compared in terms of their stability, nucleophilicity, and proton affinity (PA) parameters. The results are divided on the basis of ring size of the known and reported CCCs. The stability, nucleophilicity, PA, complexation energy, and bond strength-related parameters were estimated using M06/6-311 ++G(d,p) method. The results indicated that the CCCs known in the literature are strong σ-electron donating species and have considerable π-accepting properties. This study led to the design and identification of a few new CCCs with dimethylamine and diaminomethynyl substituents which can be singlet stable and are substantially nucleophilic.

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“…This reaction, mainly studied by Sander, is important and has been much described both for singlet and triplet carbenes [23][24][25][26]. The mechanism, through a radical pair, has also been discussed [27,28].…”

Section: Xementioning

confidence: 99%

Interaction of N‐Heterocyclic Carbenes and Simple Carbenes with Small Molecules (One to Three Atoms) Excluding Metals: Formation of Covalent C–X Bonds

Alkorta

Elguero

2018

Journal of Heterocyclic Chem

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4-Oxo-2,3,5,6-tetrafluorocyclohexa-2,5-dienylidene—A Highly Electrophilic Triplet Carbene

Cited by 15 publications

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CO Fixation to Stable Acyclic and Cyclic Alkyl Amino Carbenes: Stable Amino Ketenes with a Small HOMO–LUMO Gap

CO Fixation to Stable Acyclic and Cyclic Alkyl Amino Carbenes: Stable Amino Ketenes with a Small HOMO–LUMO Gap

Electronic and ligating properties of carbocyclic carbenes: A theoretical investigation

Interaction of N‐Heterocyclic Carbenes and Simple Carbenes with Small Molecules (One to Three Atoms) Excluding Metals: Formation of Covalent C–X Bonds

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