Competition between Diradical Stepwise and Concerted Mechanisms in Chalcogeno-Diels−Alder Reactions:  A Density Functional Study

Orlova, Galina; Goddard, John D.

doi:10.1021/jo010280g

Cited by 24 publications

(9 citation statements)

References 36 publications

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“…To our knowledge, the electron affinity of selenoformaldehyde has not been reported yet. Moreover, it is reported that there is a significant lowering of the orbital energy for the p * LUMO of these carbonyls, on changing O in formaldehyde to S and a moderate lowering on changing S to Se or Te [56]. Moreover, it is reported that there is a significant lowering of the orbital energy for the p * LUMO of these carbonyls, on changing O in formaldehyde to S and a moderate lowering on changing S to Se or Te [56].…”

Section: Electron Affinitiesmentioning

confidence: 99%

Telluroformaldehyde and its derivatives: structures, ionization potentials, electron affinities and singlet–triplet gaps of the X2CTe and XYCTe (X,Y = H, F, Cl, Br, I and CN) species

et al. 2012

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A systematic investigation of the X 2 CTe and XYCTe (X,Y = H, F, Cl, Br, I and CN) species is carried out using the second-order Møller-Plesset perturbation theory and density functional theory. The basis sets used for all atoms (except iodine and tellurium) in this work are of double-f plus polarization quality with additional s-and p-type diffuse functions and denoted DZP??. The LANL2DZdp ECP and 6-311G(d,p) basis sets are used for tellurium and iodine. Vibrational frequency analyses are performed to evaluate zero-point energy corrections and to determine the nature of the stationary points located. The ionization potentials (IP ad and IP ad(ZPVE) ), the four different forms of neutral-anion separations (EA ad , EA ad(ZPVE) , VEA and VDE), the singlet-triplet splittings as well as the HOMO-LUMO gaps are predicted. The electronegativity (v) reactivity descriptor for the halogens (F, Cl, Br and I) and the calculated Mulliken's electronegativity are used as tools to assess the interrelated properties of these telluroformaldehyde derivatives. The predicted IP ad(ZPVE) values with the B3LYP functional range from 7.89 [I 2 CTe] to 9.16 eV [F(NC)CTe], the EA ad(ZPVE) ranges from 1.29 [I 2 CTe] to 3.34 eV [(NC) 2 CTe], the singlet-triplet splitting ranges from 0.64 [H(NC)CTe)] to 1.85 eV [F 2 CTe], and the HOMO-LUMO gap ranges from 2.21 [H(NC)CTe] to 3.42 eV [F 2 CTe]. The HOMO-LUMO gap is found to be proportional to the singlet-triplet splitting. The results obtained are critically analyzed and discussed. This research is also compared with analogous studies of formaldehyde, thioformaldehyde and selenoformadehyde.

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Section: Electron Affinitiesmentioning

confidence: 99%

Telluroformaldehyde and its derivatives: structures, ionization potentials, electron affinities and singlet–triplet gaps of the X2CTe and XYCTe (X,Y = H, F, Cl, Br, I and CN) species

et al. 2012

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“…The second paper on the Diels-Alder reaction examines the familiar question of stepwise versus concerted mechanisms as applied to chalcogen substituted reactants 66-68 (with X = S, Se, Te). 63 At the B3LYP level of theory the concerted mechanism is favoured in every case. Steric and electronic factors reinforce this preference.…”

Section: Reactionsmentioning

confidence: 99%

13 Computational organic chemistry

Yates

2002

Annu. Rep. Prog. Chem., Sect. B: Org. Chem.

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Conformational analysis remains one of the bread-and-butter activities of the computational organic chemist. The papers reviewed in this section represent a cross-section of this activity.Aziridine-2-carbonitrile. The energies of the cis and trans forms of aziridine-2carbonitrile (2) have been determined at very high levels of theory by Tschumper. 5 This state-of-the-art study included very large basis sets and the use of the coupled cluster CCSD(T) and Brueckner doubles BD(TQ) methods. The latter method included a perturbative treatment of the triple as well as quadruple excitations, as shown. The focal point analysis technique was then used to extrapolate to the basis set limit and obtain results of thermochemical accuracy. The best estimate of ∆G 0 from this study shows that the trans form lies 3.5 kJ mol Ϫ1 higher in energy than the cis. This value is in good agreement with previous theoretical studies, but not with the experimental estimate of the lower bound of 11 kJ mol Ϫ1 . The transition structure connecting the two isomers was also calculated and gives rise to an estimated barrier of 77.15 kJ mol Ϫ1 above the cis isomer. These results have significance in two areas of experimental research: the study of nucleic acid structure, and the determination of rotational spectra in interstellar dust clouds.Fumaric and maleic acids. The (E ) and (Z ) forms of butenedioic acid (fumaric and maleic acid, respectively) have been the subject of a combined molecular orbital and matrix isolation study. 6 The authors used the popular MP2 and B3LYP methods to determine the lowest energy rotational conformers of each structure (see 3). In each case these were shown to be planar, with the maleic acid incorporating an intramolecular hydrogen bond to form a seven-membered ring. The OH ؒ ؒ ؒ O = C hydrogen-bonded conformer was considerably lower in energy than the OH ؒ ؒ ؒ OH hydrogen-bonded conformer. Infrared spectra of the matrix isolated species indicated that the most stable conformers of maleic and fumaric acids were indeed present in the argon matrix.

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“…19 The reactions of butadienes with CH 2 ᎐ ᎐ X (X = S, Se, Te), and of ethylene with thio-, seleno-, and telluroacrolein, were investigated. In all cases, the concerted cycloaddition is more favorable, even in the sterically-demanding reaction between selenoformaldehyde and cis,trans-hexa-2,4-diene.…”

Section: Diels-alder Reactionsmentioning

confidence: 99%

“…Shtarov et al describe the gas-phase kinetics of [2ϩ2] and [4ϩ2] cycloaddition reactions of 1,1-difluoroallene with buta-1,3-diene, obtained using gas-phase 19 F NMR. 3 The [2ϩ2] adduct is formed preferentially above 160 ЊC, while the [2ϩ4] adduct predominates at lower temperatures.…”

Section: Cycloaddition Reactionsmentioning

confidence: 99%

6 Reaction mechanisms : Part (ii) Pericyclic reactions

Morgan

2002

Annu. Rep. Prog. Chem., Sect. B: Org. Chem.

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Competition between Diradical Stepwise and Concerted Mechanisms in Chalcogeno-Diels−Alder Reactions: A Density Functional Study

Cited by 24 publications

References 36 publications

Telluroformaldehyde and its derivatives: structures, ionization potentials, electron affinities and singlet–triplet gaps of the X2CTe and XYCTe (X,Y = H, F, Cl, Br, I and CN) species

Telluroformaldehyde and its derivatives: structures, ionization potentials, electron affinities and singlet–triplet gaps of the X2CTe and XYCTe (X,Y = H, F, Cl, Br, I and CN) species

13 Computational organic chemistry

6 Reaction mechanisms : Part (ii) Pericyclic reactions

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