Some ω technique calculations on the vertical ionization potentials of mono- and 1,4-disubstituted benzenes

Caldow, G.L.; Harrison, Gfs

doi:10.1016/s0040-4020(01)82876-3

Cited by 6 publications

(3 citation statements)

References 12 publications

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“…From the PE. spectra of trifluoromethyl-benzene, 9-ditrifluoromethyl-benzene and of related trifluoromethyl substituted benzene derivatives [8] [15] it is known that both el&) orbitals are equally stabilized by roughly -0.5 eV per trifluoromethyl substituent so that no split occurs between the symmetric and antisymmetric orbital, presumably because of an accidental cancellation of inductive and conjugative effects [16]. Consequently we expect that A for the four n-orbitals @ (i, X) is lowered to A' = A -1 eV = -10 eV approximately.…”

Section: E(b2u(4) = a -Zmentioning

confidence: 99%

Consequences of Substitution in the Photoelectron Spectra of [2, 2]Paracyclophanes: Separation of ‘through‐space’ and ‘through‐bond’ interactions as a consequence of fluorosubstitution

Heilbronner

Maier

1974

Helvetica Chimica Acta

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Summary. The PE. spectra of [2, Zlparacyclophane (1). 4-amino[2, 2lparacyclophane (2) and 1,1,2.2,9,9,1O,l0-octafluoro[2, Zjparacyclophane (3) are presented. The bands corresponding to ejection of the photoelectron from the five highest occupied n-orbitals have been assigned. The 'observed' orbital energies (i.e. the negative ionization potentials) axe discussed in terms of 'through spacc' and 'through-bond' interactions between the semi-localized n-orbitals (elr) of the benzene moieties and the C, C-a-orbitals of the ethylene bridges.The PE. spectrum of 3 shows that the fluorine-induced lowering of the C, C-a-orbital energy effectively 'turns-off' the 'through-bond' interaction. The resulting pattern of the first four bands confirms the assignment given for 1. with the theoretical predictions of Gleiter [3] this feature should be assigned to the three transitions of 1 to its radical cation l f i n the states1) 2Bzg, 2B3,, 2B3g. The second band at 9.5 eV was assigned to a transition to the 2BzU state of 1' .In the present contribution we wish to confirm and extend this assignment of the z-bands of 1, by making use of the information contained in the PE. spectra of the derivatives 4-amino[2,2]paracyclophane (2) and 1,1,2,2,9,9,10,10-0ctafluoro[2,2]-paracyclophane (3).

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Section: E(b2u(4) = a -Zmentioning

confidence: 99%

Consequences of Substitution in the Photoelectron Spectra of [2, 2]Paracyclophanes: Separation of ‘through‐space’ and ‘through‐bond’ interactions as a consequence of fluorosubstitution

Heilbronner

Maier

1974

Helvetica Chimica Acta

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“…CALCULATIONS We now report some calculations on ionization potentials and carbon-carbon bond distances of some conjugated hydrocarbons using the self-consistent procedure developed in the preceding paragraphs. The calculation of these properties is of interest because of the success of the oJ technique in calculations of the former [5,6] while equilibrium bond distances have been successfully calculated using the approximate self-consistent Hfickel procedure developed by Coulson and Gotebiewski [10]. Since the self-consistent features of both these techniques are inherent in the present approach, one might hopefully expect our method to be successful for both types of calculation.…”

Section: It Itmentioning

confidence: 99%

“…In this technique [5,6] the Coulomb integrals, or diagonal elements as defined in H/ickel theory, are assumed to depend in a linear fashion on atomic charge:…”

Section: Introductionmentioning

confidence: 99%

Self-consistent Hückel theory

Caldow

1970

Molecular Physics

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Theoretical study of ionization potentials in monosubstituted benzenes

Melo

Gomes

1993

Int J of Quantum Chemistry

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Monosubstituted benzenes, in which the substituents participate in the w-electron system, are studied following a classification in two classes according to the w-electronic structure of the substituent. For this type of molecule, a relation is established between the nature of the substituent and, on the one hand, the energies of the two highest occupied molecular orbitals and, on the other hand, their respective differences. The two orbitals referred to above have Ir-character and belong to the a2 and bl species if a C2" point group is assumed. Simple symmetry arguments lead to the conclusion that the a2 orbitals have, essentially, an intraring character, whereas the Ir-orbitals of the substituents do give an important contribution to the bl orbitals. Therefore, an a2 electron must have a larger interaction with the benzene ring and a smaller kinetic energy, whereas a bl electron must have a larger interaction with the substituent and a larger kinetic energy. It is also expected that the changes in the w-electronic structure of the substituent must much more influence the variations on the bl energies and on the components of orbital energies associated with the substituent than the variations on the a2 energies and on the intraring components of the orbital energies. A modified version of the MOPAC program was prepared to perform the decomposition of the orbital energies in their kinetic and potential energy components and these in their monocentric and bicentric terms.MNDO calculations on nine monosubstituted benzenes, using the modified MOPAC program, give good confirmation of the symmetry predictions and prove the consistency of the classification of the substituents that is introduced.

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Some ω technique calculations on the vertical ionization potentials of mono- and 1,4-disubstituted benzenes

Cited by 6 publications

References 12 publications

Consequences of Substitution in the Photoelectron Spectra of [2, 2]Paracyclophanes: Separation of ‘through‐space’ and ‘through‐bond’ interactions as a consequence of fluorosubstitution

Consequences of Substitution in the Photoelectron Spectra of [2, 2]Paracyclophanes: Separation of ‘through‐space’ and ‘through‐bond’ interactions as a consequence of fluorosubstitution

Self-consistent Hückel theory

Theoretical study of ionization potentials in monosubstituted benzenes

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