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.
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