Synthesis and electrochemistry of para-diethylamino tetraphenylporphyrin derivatives

The electrochemistry and spectroelectrochemistry of several diethylamino tetraphenylporphyrin derivatives were investigated in various solvents. A cathodic shift was induced by the electron donating substituents on (p-Et2N)TPPFeCl which underwent two one- electron transfer ring centered oxidations. In DMF, the oxidation mechanism is changed and two electrons are abstracted in a single oxidation process. The reduction site of (p-Et2N)TPPFe is also solvent directed. In benzonitrile, both ESR and UV-visible data are consistent with an anion radical character, but in DMF the reaction indicates formation of iron(I) moiety. The synthesis of (p-Et2N)TPPFe(C6H5) is described and this compound was studied using spectroelectrochemistry. Spectral data for the reduction product suggests a resonance equilibrium between a formal metal-centered and a formal ring-centered reduction. [...]