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The electron absorption spectra of protonation products of ClFe(III) anions-octaethylporphyrin (Fe(III)OEP) have been investigated. The spectra of monoanions (Fe(II)OEP) and dianions (Fe(I)OEP) in tetrahydrofuran remain practically unchanged on protonation of these reduced forms by methanol, whereas in the spectra of protonation products of tri- and tetraanions absorption bands characteristic of π-monoanions and Zn-phlorins are observed. These data are interpreted as proof of the π-anionic character of the ligand, i.e., the excess electron density in three- and four-electron reduced forms of FeOEP is concentrated not only on the d-orbitals of the Fe ion, but also in the cyclic system of the tetrapyrrole ligand. |
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