Oxygen reduction in acid media: influence of the heat treatment on the FeNPc(1–20 isomer mixture impregnated on carbon blacks and active charcoals
Oxygen reduction with the aid of a number of FeNPc(1–2) impregnated carbon supports in sulphuric acid solutions has been investigated. 
 
Loading of the carbon samples amounted to about 10 wt.%. After a 10 day stay in the aerated solutions the samples were investigated with rotating disk electrode and X-ray photoelectron spectroscopy techniques. The most active and stable samples correspond to mono- or submonolayers of FeNPc deposited on high dibutylphthalate adsorption carbon blacks. Comparison with data obtained previously on Norit BrX impregnations emphasizes the role of the electron density on the inner nitrogen atoms rather than that on the iron centres.
Electron donor-acceptor properties of porphyrins, phthalocyanines, and related ring chelates: a molecular orbital approach
Tetraazaoporphyrin is used as a primitive fragment to examine theoretically the electron donor-acceptor properties of a variety of highly conjugated planar ligands of the porphyrins and phthalocyanine type. Calculations employing the atom superposition electron delocalization MO theory indicate that for iron macrocylces the energy gap between the occupied d/sub xz/, d/sub yz/ orbitals and the empty e/sub g/(..pi..*) ring orbitals plays a key role in controlling the extent of metal to ring back-bonding. This provides a framework for a rational search of structural modifications of chelating ligands that may afford an optimized activation of axially coordinated ..pi.. electron acceptor molecules such as dioxygen, nitric oxide, and carbon monoxide. The higher reactivity of iron(II) porphyrins toward such ..pi.. acceptor species, compared to iron(II) phthalocyanine, is attributed to the longer Me-N bond length in the porphyrins, which leads to less metal to ligand back-bonding and thus to more electron charge at the metal center.
Photoelectron spectra of adsorbed carbonates
Abstract In order to provide photoelectron spectra for analytical purposes, X-ray and ultraviolet photoelectron spectra for known surface species have been measured. The surface carbonate on Ag(110), formed by reacting gaseous CO 2 with pre-adsorbed atomic oxygen, yields C 1 s and O 1 s peaks at 287.7 and 529.9 eV, respectively. The UPS results show features due to surface CO 3 which scale well with those for bulk carbonates. These observations, coupled with the increase in work function that accompanies carbonate formation, suggest strongly that this surface species is negatively charged.