Thermodynamics of cis-trans isomerizations. II. 1-Chloro-2-fluoroethylenes, 1,2-difluorocyclopropanes, and related molecules

Craig, Norman C.; Piper, Lawrence G.; Wheeler, Vicki L.

doi:10.1021/j100680a015

Cited by 98 publications

(65 citation statements)

References 7 publications

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“…Therefore, the C-X n overlap population variation cannot be invoked to explain the experimental relative stabilities, contrary to previous suggestion [8].…”

Section: Unauthenticatedcontrasting

confidence: 86%

“…Falling into the first group are the elements C-C, C-H and X-X. However, the element X-X cited by previous work [5,8,9,11] to be responsible for the observed trend is actually calculated to be repulsive for all cis isomers. Element C-X runs in exactly the opposite direction, favoring the trans isomer in C2H2F2 and the cis isomer in 02^12-One notes that these results cannot be interpreted within the non-bonded attraction theory because not only is the X-X interaction repulsive in all of the cis isomers, but it is actually slightly more repulsive in difluoroethylene than in diiodoethylene.…”

Section: Discussionmentioning

confidence: 90%

“…It is reasonable to assume that these orbital energies reflect the differences in total energies. To attribute [8] the relative stabilities of the dihaloethylenes to their respective 71 systems is to neglect the large differences and concentrate on the smaller ones. Granted that this is a very attempting approach (the 71 system is much simpler -having fewer atomic orbitals), however we believe that it is totally without justification.…”

Section: Unauthenticatedmentioning

confidence: 99%

“…Various explanations have been given for these phenomena, including 1) increased C-F n bonding [5,8] in the cis-isomer relative to the trans-isomer due to the high electronegativity of the fluorine. This is considered to be of less importance as one progesses down the halogen family.…”

Section: Introductionmentioning

confidence: 99%

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Relative Stabilities of Dihaloethylenes and Dihaloethanes. A Theoretical Study [1]

Nascimento

Brinn

1978

Zeitschrift Für Naturforschung A

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CNDO/2-type calculations have been carried out on 1,1-dihaloethylenes, 1,2-dihaloethylenes and 1,2-dihaloethanes treating all four halogens. The energy was minimized with respect to the coordinates by use of the FORCE method. The results are consistent with experimental isomer and conformer stabilities and it is shown, by means of a cis-trans correlation diagram and calculated intramolecular atomic interaction energies, that previous explanations of the apparent halogen-halogen attraction are inconsistent with our results.

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“…Therefore, the C-X n overlap population variation cannot be invoked to explain the experimental relative stabilities, contrary to previous suggestion [8].…”

Section: Unauthenticatedcontrasting

confidence: 86%

Section: Discussionmentioning

confidence: 90%

Section: Unauthenticatedmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Relative Stabilities of Dihaloethylenes and Dihaloethanes. A Theoretical Study [1]

Nascimento

Brinn

1978

Zeitschrift Für Naturforschung A

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“…This is the interpretation of the 'cis' effect, i.e. the greater stability of (Z)-l,2-dihalogenoethenes compared with their (E)-diastereomers (Craig, Piper & Wheeler, 1971;Epiotis, 1973;Epiotis & Yates, 1976). However, this view is not unchallenged (Bingham, 1976).…”

Section: Introductionmentioning

confidence: 99%

Substituted cyclopropanes. 2. cis-1,2,3-Trichlorocyclopropane

Schrumpf¹,

Jones²

1987

Acta Crystallogr C

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1182trans-1,2,3-TRICYANOC YCLOPROPANE ring skeleton, i.e. the lengthening of the bond C(2)-C(2~, can be viewed as contributing to the relaxation of a repulsive interaction between the substituents. In view of the results of cyclopropanecarbonitrile (Kiers et aL, 1985), the effects of cyano substituents on the cyclopropane structure are approximately additive, but do not solely depend on topology, but also on the stereochemistry of the individual molecule.This latter aspect is expected to be even more important for cyclopropanes multiply substituted by carbonyl groups, which additionally introduce several conformational degrees of freedom. We are currently investigating the cumulative effect of halogen substituents on the geometry of the cyclopropane moiety in order to test whether the findings of the present investigation can be transferred to substituents that are not n acceptors.We thank the Fonds der Chemischen Industrie for financial support. 0108-2701/8 7/061182-04501.50 crystallographic mirror symmetry is imposed. The mean ring bond length (corrected for libration) is 1.504/~; the chlorine substituents thus appear to have little effect on this parameter.

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Density functional calculations of difluorodiazete structures with Gaussian-orbital-type approach

Jursic

1996

Int. J. Quantum Chem.

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rnThe comparison of local nonlocal and hybrid DF1 methods with RHF, MP2, CCSD, and CPF ab initio methods in generating geometries and relative energies of cis-and transdifluorodiazete. SVWN, BLYP, B r 8 6 , BECKE3LYI', and B E C K t 3 P 8 6 DFT methods with 6-311 + g ( 2 d ) and 6-311 + + g(3df) basis sets. The geometries generated with RHF ab initio models are quite different from experimental values and energy evaluation prefers the wrong isomer. The hybrid methods give superior geometries while energies evaluated with nonlocal DFT methods are better than the one obtained with MP2 or CCDS ab initio methods. The results suggest DFT as the method of choice for studying similar systems.

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Thermodynamics of cis-trans isomerizations. II. 1-Chloro-2-fluoroethylenes, 1,2-difluorocyclopropanes, and related molecules

Cited by 98 publications

References 7 publications

Relative Stabilities of Dihaloethylenes and Dihaloethanes. A Theoretical Study [1]

Relative Stabilities of Dihaloethylenes and Dihaloethanes. A Theoretical Study [1]

Substituted cyclopropanes. 2. cis-1,2,3-Trichlorocyclopropane

Density functional calculations of difluorodiazete structures with Gaussian-orbital-type approach

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