X-ray photoelectron spectroscopic studies on the electronic structures of porphyrin and phthalocyanine compounds

Abstract

We have measured the nitrogen Is binding energies and some metal binding energies of porphyrin and phthalocyanine compounds by X-ray photoelectron spectroscopy. We find that this technique yields interesting new data. In particular, we find two kinds of nitrogen in tetraphenylporphine free base, differing in charge by about 0.2 e. We find the nitrogens of most metalloporphyrins to be similar to those of porphine base which lack protons. We find the two kinds of nitrogen in metal phthalocyanines to be identical with photoelectron spectroscopy. Finally, we find that the iron in the oxidized and reduced forms of iron porphyrin differ in charge by some 0.44 electron charges. On the whole, our results compare well with the theoretical predictions of Gouterman and coworkers.

XANES Spectroscopic Studies of Evaporated Porphyrin Films: Molecular Orientation and Electronic Structure

“…Transitions to the corresponding z* orbitals in metal-free porphyrin are calculated to be negligibly weak. We note that the character of the highest energy peak in the simulated spectrum of free-base porphyrin in Figure 3 does not correspond to the highest energy peak (IV) of Be porphine, but to the second peak (11).…”

Further Studies on the Oxidation State of Iron in μ-Oxo Dimeric Phthalocyanine Complexes

“…709.1 eV for PcFe, 708.0 eV for [23,24,25]. It is well known that for Fe(III) and Fe(II) porphyrins the difference in energies for this level is 3-4 eV [100]; therefore the XPS data for form '690' suggest that this complex has only Fe(II) ions in the molecule.…”

2D Coordination Polymer Built from Lithium Dimethylmalonate and CoII Ions: The Influence of Dehydration on Spectral and Magnetic Properties

“…The coordination environment of Co II in 2 can be estimated on the basis of comparison of data, obtained for 2 and 1 by using our XPS results, and previously reported complexes 5 (hexacoordinate, pseudo‐octahedral environment), 6 (hexacoordinate, pseudo‐octahedral environment), and [Co(acac) 2 ] (tetracoordinate, pseudo‐tetrahedral environment), in which Co II ions are located in donor sets of oxygen atoms in weak fields. The value of E b for the Co2p 3/2 line in 2 (781.1 eV) is close to the values observed for 1 , 5 , and 6 (Table ), and significantly differ from the value observed for Co II ions in the pseudo‐tetrahedral donor set in 7 (780.0 eV).…”

“…For comparison, we measured XPS for Co II dimethylmalonate, [K 2 Co(Me 2 Mal) 2 (H 2 O) 3 ] n ( 5 ) (see the Experimental Section for details). In addition, Table contains XPS parameters for compounds [Co 9 (OH) 6 (Piv) 12 (OCMe 2 ) 4 ] ( 6 ) and [Co(acac) 2 ] ( 7 ), which also were used as references.…”