A COMPARISON OF EXCITON AND MOLECULAR ORBITAL CALCULATIONS ON n$Yields$$pi$ TRANSITIONS

Technical Report · Mon Jan 01 04:00:00 EST 1962

OSTI ID:4651999

Kearns, D R; El-Bayoumi, M A

The application of the Exciton and the Molecular Orbital (MO) methods is compared to the calculation of n - approximates pi /sup */ transitions in N- heteroaromatic molecules. A number of the features of the n yields approximates pi /sup */ transitions were treated by these two methods including energies of the (n, pi /sup */) stntes, the intensities of the allowed n yields approximates pi /sup */ transitions, the ordering of the allowed and forbidden transitions and singlettriplet splittings. From a comparison of experiment and theory, it is concluded that the assumption, which is made in the Exciton calculations, that n - approximates pi /sup */ transitions are essentially localized atomic-like'' transitions, is poor initial approximation and leads to a number of incorrect predictions. The assumption that the promoted lone-pair electron is delocalized over the pi-aromntic system appears to be a much better initial approximation, and when the effect of electron repulsion between lone- pair electrons is included in the MO calculations, there is very good ngreement between the theoretical predictions and experimental observations on n yields approximates pi /sup */ transition in the mono- and polycyclic azines. The relation between MO theory in the one-electron approximation and MO theory in which electron repulsion between the lone-pair electrons is included and is also discussed. (auth)

• Research Organization: California. Univ., Riverside; Alexandria Univ., Egypt
• NSA Number: NSA-17-033952
• OSTI ID: 4651999
• Report Number(s): TID-19258
• Country of Publication: United States
• Language: English

Related Subjects

AROMATICS
ATOMIC MODELS
AZINES
CHEMISTRY
ELECTRONS
ENERGY LEVELS
HETEROCYCLICS
MOLECULES
ORGANIC NITROGEN COMPOUNDS
PAIR PRODUCTION
QUANTUM MECHANICS
TRANSIENTS