Correlation of calculated halonium ion structures with product distributions from fluorine substituted terminal alkenes

Shellhamer, Dale F.; Gleason, David C.; Rodriguez, Sean J; Heasley, Victor L.; Boatz, Jerry A.; Lehman, Jeffrey

doi:10.1016/j.tet.2006.09.071

Cited by 7 publications

(17 citation statements)

References 31 publications

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“…There have been both experimental and computational studies of fluoronium and chloronium ions, which all describe CX bonds as weak and the stability of halonium ions as low. This is confirmed by the CX stretching force constants k a and RBSO values n obtained in this work.…”

Section: Resultsmentioning

confidence: 99%

Are carbon—halogen double and triple bonds possible?

Kalescky

Kraka

Cremer

2014

Int J of Quantum Chemistry

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The carbonAhalogen and carbonAchalcogen bonding of 84 molecules was investigated utilizing local vibrational modes calculated at the M06-2X/cc-pVTZ level of theory including anharmonicity corrections in all cases. The relative bond strength order of each CX or CE bond (X 5 F, Cl; E 5 O, S) was derived from the local CX or CE stretching force constant and compared with trends of calculated bond lengths r and bond dissociation energies (BDE) obtained at the G3 level of theory. It is shown that both bond length r and BDE are not reliable bond strength descriptors. The CX double bond is realized for some Cl-substituted carbenium ions, however, not for the cor-responding F-derivatives. Diatomic CF 1 and CCl 1 possess fully developed double bonds but not, as suggested in the literature, triple bonds. Halonium ions have fractional (electron-deficient) CX bonds, which can be stabilized by r-donor substituents or by an increased polarizability of the halogen atom as with Cl. Bridged halonium ions are more stable than their acyclic counterparts, which results from more effective two-electron-three-center bonding.

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Section: Resultsmentioning

confidence: 99%

Are carbon—halogen double and triple bonds possible?

Kalescky

Kraka

Cremer

2014

Int J of Quantum Chemistry

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“…All studies on halonium ions ,,, describe their CX bonds as relatively weak and the stability of the ions as low. This is confirmed by the CX stretching force constants k a and RBSO values n CE obtained in this work.…”

Section: Relationship Between Force Constants and Bond Lengthsmentioning

confidence: 99%

Quantitative Assessment of the Multiplicity of Carbon–Halogen Bonds: Carbenium and Halonium Ions with F, Cl, Br, and I

2014

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CX (X = F, Cl, Br, I) and CE bonding (E = O, S, Se, Te) was investigated for a test set of 168 molecules using the local CX and CE stretching force constants k(a) calculated at the M06-2X/cc-pVTZ level of theory. The stretching force constants were used to derive a relative bond strength order (RBSO) parameter n. As alternative bond strength descriptors, bond dissociation energies (BDE) were calculated at the G3 level or at the two-component NESC (normalized elimination of the small component)/CCSD(T) level of theory for molecules with X = Br, I or E = Se, Te. RBSO values reveal that both bond lengths and BDE values are less useful when a quantification of the bond strength is needed. CX double bonds can be realized for Br- or I-substituted carbenium ions where as suitable reference the double bond of the corresponding formaldehyde homologue is used. A triple bond cannot be realized in this way as the diatomic CX(+) ions with a limited π-donor capacity for X are just double-bonded. The stability of halonium ions increases with the atomic number of X, which is reflected by a strengthening of the fractional (electron-deficient) CX bonds. An additional stability increase of up to 25 kcal/mol (X = I) is obtained when the X(+) ion can form a bridged halonium ion with ethene such that a more efficient 2-electron-3-center bonding situation is created.

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“…The reaction then proceeds via D 2h symmetry as shown in Figure 3. The differences in geometry between the corner-protonated cyclopropane and the 1,2-dyotropic methyl exchange TS are much more pronounced than the corresponding geometric differences between the halonium ions [19] and the 1,2-dyotropic halogen TS. For the CXC angle, the decrease is 9.84˚ (Cl) and 6.34˚ (Br).…”

Section: A Comparison Between the Mo Results Of The 12-cyclic Halonimentioning

confidence: 90%

An Adjusted Model for Simple 1,2-Dyotropic Reactions. <i>Ab Initio</i> MO and VB Considerations

Buck¹

2013

OJPC

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With an adjusted model, we reconsider simple 1,2-dyotropic reactions with the introduction of a concept based on the intramolecular dynamics of a tetrahedron (van 't Hoff modeling). In fact the dyotropic reactions are strongly related to conversions originated from neighbouring group participation or anchimeric assistance, defined as the interaction of a center with a lone pair of electrons in an atom and the electrons present in a ϭ or π bond. The researchful 1,2-dyotropic reactions, based on the 1,2-interchange of halogens, methyl and hydrogen taking place in a concerted fashion, are in competition with the two-step reaction in which the neighbouring group participation or anchimeric assistance comes to full expression by ionic dissociation of the other exchangeable (halogen) atom. As to be expected there is an essential difference between halogen or methyl exchange regarding the number of electrons participating in the transition state. This aspect becomes evident in the geometries of the corresponding transition state geometries. In this paper we refer to ab initio MO calculations and VB considerations. We consider the 1,2-halogen exchange as a combination of two S N 2 reactions each containing four electrons. The van 't Hoff dynamics appears a useful model in order to illustrate the computations in a straightforward manner.

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Correlation of calculated halonium ion structures with product distributions from fluorine substituted terminal alkenes

Cited by 7 publications

References 31 publications

Are carbon—halogen double and triple bonds possible?

Are carbon—halogen double and triple bonds possible?

Quantitative Assessment of the Multiplicity of Carbon–Halogen Bonds: Carbenium and Halonium Ions with F, Cl, Br, and I

An Adjusted Model for Simple 1,2-Dyotropic Reactions. <i>Ab Initio</i> MO and VB Considerations

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Correlation of calculated halonium ion structures with product distributions from fluorine substituted terminal alkenes

Cited by 7 publications

References 31 publications

Are carbon—halogen double and triple bonds possible?

Are carbon—halogen double and triple bonds possible?

Quantitative Assessment of the Multiplicity of Carbon–Halogen Bonds: Carbenium and Halonium Ions with F, Cl, Br, and I

An Adjusted Model for Simple 1,2-Dyotropic Reactions. &lt;i&gt;Ab Initio&lt;/i&gt; MO and VB Considerations

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An Adjusted Model for Simple 1,2-Dyotropic Reactions. <i>Ab Initio</i> MO and VB Considerations