Reactions of oxiranylidene and dimethyloxiranylidene, and their generation by retro Diels–Alder-type reactions: a computational study

Delamere, C; Jakins, C; Lewars, Errol G.

doi:10.1016/s0166-1280(02)00144-6

Cited by 6 publications

(1 citation statement)

References 41 publications

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“…Second, previous studies have shown that TD-DFT can sometimes provide reasonable estimates of UV–vis spectra for related reactive intermediates. − Thus, we computed the absorption spectrum of the singlet phenyloxenium ion using TD-B3LYP/6-311+G(2d,p), shown in Figure . The computed absorption band for 1 4 gives a single band in the visible region of the UV–vis spectrum centered at 524 nm, in good agreement with the experimental band (see Figure ).…”

Section: Resultsmentioning

confidence: 99%

Direct Detection and Reactivity of the Short-Lived Phenyloxenium Ion

et al. 2013

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Photolysis of protonated phenylhydroxylamine was studied using product analysis, trapping experiments, and laser flash photolysis experiments (UV-vis and TR 3 detection) ranging from the femtosecond to the microsecond time scale. We find that the excited state of the photoprecursor is followed by two species: a longer-lived transient (150 ns) that we assign to the phenoxy radical and a shorter-lived (3-20 ns) transient that we assign to the singlet phenyloxenium ion. Product studies from photolysis of this precursor show rearranged protonated o-/p-aminophenols and solvent water adducts (catechol, hydroquinone) and ammonium ion. The former products can be largely ascribed to radical recombination or ion recombination, while the latter are ascribed to solvent water addition to the phenyloxenium ion. The phenyloxenium ion is apparently too short-lived under these conditions to be trapped by external nucleophiles other than solvent, giving only trace amounts of o-/p-chloro adducts upon addition of chloride trap. Product studies upon thermolysis of this precursor give the same products as those generated from photolysis, with the difference being that the ortho adducts (o-aminophenol, hydroquinone) are formed in a higher ratio in comparison to the photolysis products. Disciplines Materials Chemistry | Other Chemistry | Physical Chemistry CommentsReprinted (adapted) with permission from J. Am. Chem. Soc., 2013, 135 (24) ABSTRACT: Photolysis of protonated phenylhydroxylamine was studied using product analysis, trapping experiments, and laser flash photolysis experiments (UV−vis and TR 3 detection) ranging from the femtosecond to the microsecond time scale. We find that the excited state of the photoprecursor is followed by two species: a longer-lived transient (150 ns) that we assign to the phenoxy radical and a shorter-lived (3−20 ns) transient that we assign to the singlet phenyloxenium ion. Product studies from photolysis of this precursor show rearranged protonated o-/ p-aminophenols and solvent water adducts (catechol, hydroquinone) and ammonium ion. The former products can be largely ascribed to radical recombination or ion recombination, while the latter are ascribed to solvent water addition to the phenyloxenium ion. The phenyloxenium ion is apparently too short-lived under these conditions to be trapped by external nucleophiles other than solvent, giving only trace amounts of o-/p-chloro adducts upon addition of chloride trap. Product studies upon thermolysis of this precursor give the same products as those generated from photolysis, with the difference being that the ortho adducts (o-aminophenol, hydroquinone) are formed in a higher ratio in comparison to the photolysis products.

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Section: Resultsmentioning

confidence: 99%

Direct Detection and Reactivity of the Short-Lived Phenyloxenium Ion

et al. 2013

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Reactivity of silagermenylidene toward nitrous oxide: a preliminary DFT study

Yildiz

2017

J Mol Model

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The possible reaction mechanism of silagermenylidene and its NHC (N-heterocyclic carbene) coordinated form with NO were investigated by DFT methods. Mainly, the potential energy surfaces of the five pathways I-IV were explored. Pathways I, II, III, and III' deal with the oxidation of silagermenylidene, whereas that of NHC coordinated form is associated with pathways I, III, III', and IV. Pathway I is initiated by the interaction between terminal N atom of NO and Si atom of silagermenylidene in a stepwise manner. Pathway II details concerted direct oxidation of silagermenylidene. Pathways III and III' are related to the concerted 1,3-dipolar cycloaddition steps. Pathway IV is about the interaction of terminal atoms of NO with carbenic Ge atom of silagermenylidene. All the proposed pathways I-IV portray the isomerization of silagermenylidenes to silagermoxiranylidenes. The subsequent NO addition to the silagermoxiranylidenes was also investigated in the present study. Somehow with a trend similar to silagermenylidenes, the proposed pathways I-IV exist for the second molecule NO activation by silagermoxiranylidenes. A comparison of the free energy profiles of the proposed pathways gave the important result that pathways III and III' remain the most facile mechanisms to activate NO in all cases. We strongly believe that the proposed mechanisms will be effective to better understand the chemistry of heavier vinylidenes and provide further impetus to this field. Graphical Abstract The possible oxidation reaction mechanism of silagermenylidene with nitrous oxide was investigatedthrough density functional calculations. The concerted 1,3-dipolar cycloadditions are determined to beenergetically most facile pathways.

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Vibrational frequencies and structural determination of dimethylketene

Jensen

2005

Journal of Molecular Structure: THEOCHEM

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Reactions of oxiranylidene and dimethyloxiranylidene, and their generation by retro Diels–Alder-type reactions: a computational study

Cited by 6 publications

References 41 publications

Direct Detection and Reactivity of the Short-Lived Phenyloxenium Ion

Direct Detection and Reactivity of the Short-Lived Phenyloxenium Ion

Reactivity of silagermenylidene toward nitrous oxide: a preliminary DFT study

Vibrational frequencies and structural determination of dimethylketene

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