Magnetic circular dichroism and theoretical studies of the excited states of magnesium phthalocyanine negative ions

Abstract
In this work, the magnetic circular dichroism spectra and the absorption spectra of the first four negative ions of magnesium phthalocyanine are reported and discussed. Calculations of the π-LCAO-SCF-CI type are compared in two different approximations. The first approximation assumes that SCF orbitals generated from the neutral molecule are sufficient to describe the ions and is shown to be inaccurate. The second approximation includes the extra electrons in the SCF calculation, and the results, together with the magnetic circular dichroism spectra, are used to assign the mono- and tetranegative ion spectra and to assign tentatively the trinegative ion spectra. The magnetic circular dichroism measurements are apparently the first to be made on radicals and radical ions.