Beitrge zur Chemie der Pyrrolpigmente, 2. Mitt.: Die Rntgenphotoelektronenspektren einiger Pyrrolpigmente@@@On the chemistry of pyrrole pigments, II.: The X-ray photoelectron spectra of some pyrrole pigments

The charge densities on the nitrogen atoms of symmetrically substituted dipyrromethenes, porphins, chlorins and bacteriochlorins were determined by X-ray photoelectron spectroscopy of the N1s-levels. Calculation by means of a π-electron- and an all-valence-electron-method (SCF-LCAO-MO-PPP and CNDO/2) reveals good correlation of both methods with experiment. Both are comparable in predicting the energy of the highest occupied orbitals which were studied by measuring the valenceband regions.