Crystallographic and (spectro)electrochemical characterizations of cobalt(II) 10-phenyl-5,15-di-p-tolylporphyrin

The synthesis, cyclic and rotating disk electrode voltammograms, UV-visible absorption and X-ray diffraction analyses of cobalt(II) 10-phenyl 5,15-di-p-tolylporphyrin (1-Co) are described. 1-Co was crystallized by slow diffusion of n-hexane into a concentrated CH2Cl2 solution. X-ray diffraction analyses reveals porphyrin aromatic cycle stacking in the crystal, Co(II)center dot center dot center dot pi interactions of the CH2Cl2 solvent with the pi-system of one tolyl group and Co(II)center dot center dot center dot pi (porphyrin ring) interactions. The abstraction of 1.0 F/mol during the electrolysis at the first oxidation potential was followed by spectroelectrochemistry. It leads to the Co(II) -> Co(III) transformation rather than the formation of the cation radical of the porphyrin ligand. These results were supported by comparison of the cyclic and rotating disc electrode voltammograms, of the UV-Visible absorption spectra, before and after electrolysis of 1-Co. Published by Elsevier B.V.