Carbenes in matrixes: spectroscopy, structure, and reactivity

Sander, Wolfram; Bucher, Götz; Wierlacher, Stefan

doi:10.1021/cr00020a009

Cited by 277 publications

(284 citation statements)

References 150 publications

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“…The ketene product is easily detected by IR spectroscopy and provides chemical evidence for the presence of carbenes in a matrix. [10][11][12] As expected, photolysis of mesityldiazomethane in a CO-doped argon matrix does generate a ketene.…”

Section: Mesitylcarbenesupporting

confidence: 54%

LASER FLASH PHOTOLYSIS STUDY OF PHENYLCARBENE,o-TOLYLCARBENE AND MESITYLCARBENE

Admasu

Platz

Marjcinek

et al. 1997

J. Phys. Org. Chem.

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Section: Mesitylcarbenesupporting

confidence: 54%

LASER FLASH PHOTOLYSIS STUDY OF PHENYLCARBENE,o-TOLYLCARBENE AND MESITYLCARBENE

Admasu

Platz

Marjcinek

et al. 1997

J. Phys. Org. Chem.

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“…1 Certain carbenes are an exception to this rule. 2,3 A carbene has a hypovalent, formally neutral carbon atom. Thus, in a Lewis sense, the carbene carbon has two electrons not involved in bonding and two non-bonding orbitals into which to place those electrons (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“…However, by various analyses of predicted molecular geometries and electronic structures within a related series of carbenes at an appropriate level of theory, it is possible to rationalize qualitatively the relative importance of these interactions for a given set of substituent groups. An improved understanding of substituent effects may be useful both for understanding carbene reactivities in organic reactions 3,21 and for the design of stable carbenes having either high-or low-spin ground states. 1 Goddard and coworkers [22][23][24] have been particularly active in the area of developing predictive models and have suggested certain simple, empirically-corrected computational approaches to estimate S-T gaps, particularly for halo-substituted carbenes.…”

Section: Introductionmentioning

confidence: 99%

Density functional calculations of the influence of substitution on singlet–triplet gaps in carbenes and vinylidenes

Worthington¹,

Cramer²

1997

J. Phys. Org. Chem.

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Density functional theory calculations of multiplet splittings are presented that agree closely with experimental measurements for six carbenes and six vinylidenes. The calculations are further analyzed to gauge the relative importance of different factors influencing the stabilities of the different spin and electronic states. In the carbene series, with halogen substituents, orbital rehybridization effects and charge redistribution effects are large. The magnitude of -conjugation (back-bonding) is calculated to be only moderately larger (6-8 kcal mol ؊ 1 ) for singlets than for triplets based on natural bond orbital-derived conjugation energies. In the vinylidene series, substituion effects are primarily associated with through-space and through-bond inductive stabilization effects, especially hyperconjugation; -conjugation effects are found to be small

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“…The simplest example of such a migration involving heterocyclic carbenes is the 1,2H-shift reaction to imidazol-2-ylidenes that has been known since the beginning of the 1990s. 19,32,33,[280][281][282][283][284] The unimolecular concerted mechanism for this reaction was found to take place only with carbenes of low stabilities. 281,285,286 This prompted a search for an alternative intermolecular mechanism.…”

Section: Rearrangements and Autotransformationsmentioning

confidence: 99%