Photoelectron Spectroscopy on Thin Films of Extended Copper Porphyrazines

Nickel-macrocycle interaction in nickel(II) porphyrins and porphyrazines bearing alkylthio β-substituents: A combined DFT and XPS study

An electronic structure analysis of two nickel(II) tetrapyrrole complexes bearing β-alkylthio substituents, NiOMTP and NiOETPz, has been carried out through a combination of high-resolution XPS experiments and DFT calculations. The Ni 2p XPS spectra show a 0.5 eV shift to higher energy of the Ni 2p[Formula: see text] and Ni 2p[Formula: see text] binding energies on going from the porphyrin to the porphyrazine complex. This shift, which is well-reproduced by relativistic spin-orbit ZORA calculations, is indicative of a depletion of electron density on the central metal. Such a depletion of electron density is related to the macrocycle-induced changes in the metal-ligand interactions. In the porphyrazine complex both the ligand to metal [Formula: see text] donation and the metal to ligand [Formula: see text]-back donation increase. The latter increases slightly more than the former, however, leading to a decrease of electron density on the central metal.

Photoelectron Spectroscopy on Thin Films of Extended Zinc Porphyrazines

Photoemission measurements were performed on a series of stepwise benzoannelated zinc porphyrazine molecules in thin films. The electronic structure of tert-butyl-substituted zinc tetraazaporphyrin, phthalocyanine, and naphthalocyanine is investigated using mainly EUV synchrotron radiation. A detailed analysis of the zinc satellites in the spectra of the valence region is performed in an attempt to infer the effect of ligand size extension on the metal-ligand interactions. No differences in the character of the bond between zinc and ligand were detected as a function of ligand size. The results are compared with those for the respective metal-free and copper-containing molecules.