LCAO-MO-SCF-CI semi-empirical ?-electron calculations on heteroaromatic systems

Forshey, D. R.; Pukanic, G. W.; Wegener, Br. Jerome D.; Greenshields, J. B.

doi:10.1007/bf00526107

Cited by 15 publications

(4 citation statements)

References 46 publications

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“…The molecules were assumed to be planar with C-C, C-0, C=O, C-C (methyl group) and C r H , distances equal to 1.396 A" [12], 1.46 A" [12] The Slater orbital exponent of the H, group required for the calculation of the overlap matrix elements involving this group was derived by adjusting the orbital exponent until the known value, 0.541 [21], of the overlap integral was obtained using the standard formula for 2p, and 2p, orbitals. An orbital exponent of 0.629 was thus determined.…”

Section: Methodsmentioning

confidence: 99%

“…All elements of the H'-matrix involving non-neighbours were neglected. Elements of the core matrix over STO'S were written in the manner of Pukanic and coworkers [12], due account being taken of heteroatoms which donated two Telectrons.…”

Section: Methodsmentioning

confidence: 99%

“…The molecules were assumed to be planar with C-C, C-0, C=O, C-C (methyl group) and C r H , distances equal to 1.396 A" [12], 1.46 A" [12], 1.22 A" [ 181, 1.51 A" [ 191 and 0.45 A" [ 191, respectively. All bond angles were set equal to 120" with the exception of -a H 3 , for which a value of 180" was taken while using the H-model.…”

Section: Methodsmentioning

confidence: 99%

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Effect of methyl and hydroxyl substituents on the π‐electronic spectra and ionization potential of p‐benzoquinone

Mitra

Kapoor

1972

Int J of Quantum Chemistry

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Abstracts SCF-LCAO-MO-CIsemi-empirical n-electron calculations have been made of the first two singlet transitions and ionization potentials of hydroxy-, methyl-and hydroxy-methyl substituted p-benzoquinone, using a modified Pariser-Parr-Pople method. The various molecules could be divided into two classes on the basis of their first n-electron transition, namely, those in which the 3-position was occupied and others where this position was vacant.Avec une mtthode Pariser-Parr-Pople modifite on a fait des calculs SCF-LCAO-MO-CI semi-empiriques des tlectrons n pour les deux premieres transitions singulet et les potentiels d'ionization du p-benzoquinone substitut hydroxy, mCthyle-et hydroxy-mtthyle. Selon leur premiere transition n-tlectronique ces moltcules peuvent Ctre divistes en deux classes, a savoir celles oh la position C'trois" est occupte et celles oh cette position est vacante.Halbempirische SCF-LCAO-MO-CI n-Elektronenberechnungen der zwei ersten Singulettubergange und der Ionisierungspotentiale sind fur Hydroxy, Methyl-, und HydroxyMethylsubstituiertes p-Benzokinon mit einer modifizierten Pariser-Parr-Pople-Methode ausgefuhrt worden. Die verschiedenen Molekule konnen nach ihrem ersten n-Elektronenubergang klassifiziert werden; in den Molekulen der ersten Klasse ist die "drei"-Stellung besetzt und in denen der zweiten Klasse nicht.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Effect of methyl and hydroxyl substituents on the π‐electronic spectra and ionization potential of p‐benzoquinone

Mitra

Kapoor

1972

Int J of Quantum Chemistry

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“…Лучшую корреляцию между химическими сдвигами и электронными плотностями можно было ожидать на основе расчетов по методу ППП [ 7 ]. Однако оба расчетных варианта с учетом а-электронных плотностей не устраняют отдельного группирования замещенных атомовуглерода.…”

unclassified

Химические Сдвиги Углерода-13 Оксибензолов И Оксидифенилов

Lippmaa¹,

Pehk²

1970

Eesti NSV Teaduste Akadeemia Toimetised. Keemia. Geoloogia

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Т. ПЕХК Э. ЛИППМАА ХИМИЧЕСКИЕ СДВИГИ УГЛЕРОДА-13 ОКСИБЕНЗОЛОВ И ОКСИДИФЕНИЛОВ Т. РЕНК, Е. LIPPMAA. HÜDROKSÜBENSEENIDE JA HÜDROKSÜD I FENOOLI DE SOSINIK-13-' KEEMILISED NIHKED T. РЕНК, Е. LIPPMAA. THE CARBON-13 CHEMICAL SHIFTS OF HYDROXYBENZENES AND* HYDROXYDIPHENYLS Исследование спектров ЯМР С-13 метоксибензолов показало, что стерические взаимодействия играют существенную роль при экранировании углеродных атомов [ ! ]. Одновременно наблюдается удовлетворительная корреляция между химическими сдвигами углерода и л-электронными плотностями. Можно предположить, что из-за меньшей роли стерических взаимодействий в оксибензолах соблюдается лучшая корре-; ляция между химическими сдвигами и электронными плотностями, чем в метоксибензолах.

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Circular dichroism of nucleoside derivatives. VII. The electronic structure and spectra of some simple nucleoside derivatives

Miles

Inskeep

Robins

et al. 2009

Int. J. Quantum Chem.

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The electronic structures and spectra of some simple nucleoside derivatives with the formal structure of cytosine nucleoside are presented. The experimental spectroscopic information is obtained from the circular dichroism and absorption spectra. The first four circular dichroism bands of pi-pi* origin possess the same sign pattern previously reported for most cytosine nucleoside derivatives. The four electronic states that produce the characteristic circular dichroism spectra are correlated with the B,, , B,, , and El, states of benzene. Pariser-Parr-Pople calculations are also presented which qualitatively explain the trends in both the circular dichroism and absorption spectra. Configuration interaction involving single electron excitations between the five highest occupied and the three lowest unoccupied molecular orbitals has been included in the calculations. 1511 (1965).

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LCAO-MO-SCF-CI semi-empirical ?-electron calculations on heteroaromatic systems

Cited by 15 publications

References 46 publications

Effect of methyl and hydroxyl substituents on the π‐electronic spectra and ionization potential of p‐benzoquinone

Effect of methyl and hydroxyl substituents on the π‐electronic spectra and ionization potential of p‐benzoquinone

Химические Сдвиги Углерода-13 Оксибензолов И Оксидифенилов

Circular dichroism of nucleoside derivatives. VII. The electronic structure and spectra of some simple nucleoside derivatives

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