Knowledge Bank

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 $\pi -LCAO-SCF-CI$ 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 has been shown to be in error. 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 tentatively assign the trinegative ion spectra.