Electronic Spectra and Structure of the Carbonyl Group

A theoretical treatment of the electronic structures of compounds containing the carbonyl group has been developed. The method employs the self-consistent field (SCF) procedure to determine the best molecular orbitals, for the lowest configuration, which can be formed as linear combinations of the atomic orbitals (LCAO—MO). Semiempirical methods are used throughout to determine the numerical values of all core parameters and electronic repulsion integrals. By a judicious choice of parameters and integrals it is possible to describe semiquantitatively the π-electron ionization potentials, n→π and π→π electronic transition energies, and π-electronic contribution to the dipole moment of formaldehyde, glyoxal, and p-benzoquinone. The effect of configurational interaction (CI) upon the calculated transition energies is considered for the n→π and for the π→π transitions.