Inductive effects on molecular ionization potentials—VI

Levitt, L. S.; Levitt, Barbara W.; Párkányi, Cyril

doi:10.1016/0040-4020(72)88097-9

Cited by 20 publications

(7 citation statements)

References 15 publications

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“…This has been explained as being caused by a delocalization effect, methylation increasing the delocalization of positive charge created by ionization thus stabilizing the ion, 43 and also an inductive effect, the methyl groups donating electron density and destabilizing the neutral. 44 The decrease in the term values for the three lowest valence transitions demonstrate that the 1r* orbital is also destabilized by increasing methylation by nearly the same degree as the1rorbital (0.9 eV /methyl). Indeed, all the lower molecular orbitals studied are destablized with methylation, including the Rydberg orbitals by about 0.2 e V /methyl for the s type and about 0.02 e V /methyl for the d type.…”

Section: C_ Discussionmentioning

confidence: 99%

Electron-impact spectroscopy of acetaldehyde

Walzl

Koerting

Kuppermann

1987

The Journal of Chemical Physics

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Acetaldehyde has been studied by the technique of low-energy variable-angle electron energyloss spectroscopy. With this method the low-lying spin-forbidden transitions have been located via the behavior of the relative differential cross sections, providing the first identification by this technique of such states in acetaldehyde. High-lying states were also investigated and some assignments of dipole symmetry-forbidden/quadrupole symmetry-allowed excitations were made on the basis of characteristic angular behavior, evident for the asymmetric molecule acetaldehyde just as for the symmetric molecules formaldehyde and acetone. Through a comparison of the acetaldehyde results with those for formaldehyde and acetone the trends in the allowed and forbidden transition energies were examined as a function of methyl substitution and found to be relatively linear.

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Section: C_ Discussionmentioning

confidence: 99%

Electron-impact spectroscopy of acetaldehyde

Walzl

Koerting

Kuppermann

1987

The Journal of Chemical Physics

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“…We have also found good results for aldehydes [5], Cu and Cr acetylacetonates [10,13], and benzene Cr tricarbonyls [13], as well as for benzene [14], pyridine and thiophene derivatives [15]. It is interesting to note that quantum mechanical calculations using simple Hiickel molecular orbital theory for obtaining values of highest occupied molecular orbitals (HOMO) have resulted, for alkenes [1G], disulfides [17], alkylbenzenes [14] and for pyridine and thiophene derivatives [15] constants [5].…”

Section: Molecular Ionization Potentialsmentioning

confidence: 99%

The Alkyl Inductive Effect, II Theoretical Calculation of Inductive Parameters

Widingand

Levitt

1979

Zeitschrift Für Naturforschung B

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AbstractThree models of alkyl groups, “derealization”, “through-the-bond”, and “electric field” models, are presented, all of which enable the calculation of σI (R) from first principles, and excellent agreement is demonstrated for the calculated and experimental values of σI (R) . For the “delocalization” model it is found that - σI (R) = 0.0455 + 0.0232(1-1/n), where n is the number of C atoms in an n-alkyl group, and for an infinite C-chain R group, σI( R∞) is - 0.0687, identical to the value found b y a different method in Part I of this series. The “through-the-bond” model gives - σI(R) = - 0.0559 +, where Ci is the number of C-atoms in the i th position from X in RX; and for the “electric field” model, we obtain - σI(R) = 0.0463 + 0.0102 , where di is the calculated distance from C1 to Cn in the most probable conformation of the R-group. It is concluded that Taft's σI(R) values have a real significance whether or not the physical and chemical effects of alkyl substitution reside ultimately in an internal induction mechanism, or in alkyl group polarization by charged centers in the molecule, or a combination of the two.

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“…Л. С. Левит с сотр. [ 9 ] установил, что ПИ алкенов С 2 -С 6 зависят линейно от индукционных констант заместителей (2од) и показали возможность теоретического расчета энергии ионизации простым методом ХМО. В настоящей работе с целью выявления закономерностей изменения адиабатических ПИ более высококипящих изомеров изучены я-алкены С B С )0 (таблица).…”

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“…Линейные зависимости экпериментальных значений ПИ от полярных и индукционных констант заместителей (Sa* и Sar [ 9 > 10 ]) описываются: для я-октенов ПИ =10,057+10,567 Sa 7 , (1) ПИ= 9,063+ 0,987 So*, (5) ПИ= 9,041+ 1,041 Sa*. (6) Эти уравнения для Sa r близки к уравнению ПИ = 10,260+ 11,586 Sar, приведенному для алкенов Сз -С 6 [ 9 ] и могут быть применены для расчета ПИ.…”

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