Photoelectron and electronic spectra of acenaphthenequinone, naphthalic anhydride, and naphthalimide

Abstract

The u.v. photoelectron spectra of acenaphthenequinone, naphthalic anhydride, naphthalimide, and N-methyl-naphthalimide are reported and interpreted employing correlative arguments assisted by results of semiempirical calculations. The core ionisation energies (I.E.s) of the atoms of the carbonyl groups are also reported. For a series of cyclic anhydrides and imides it is shown that there is a fair correlation between the average I.E.s of the carbonyl lone pair orbitals and the average CO stretching frequencies, while there is no direct correlation between the average n I.E.s and the ¹³C carbonyl chemical shifts.

The main features of the u.v.–visible spectra of these compounds have been analysed theoretically by means of SCF–INDO/S–Cl calculations and an elucidation of the electronic bands is given in terms of n→π* carbonyl transitions and π→π* transitions of specifically naphthalene origin.