Electrochemistry of [(TMpyP)MII]4+(X-)4 (X- = Cl- or BPh4-) and [(TMpyP)MIIICl]4+(Cl-)4 in N,N-Dimethylformamide Where M Is One of 15 Different Metal Ions

The electrochemistry of 16 different water-soluble porphyrins of the type [(TMpyP)MII]4+(X-)4 or [(TMpyP)MIIICl]4+(Cl-)4 is reported in nonaqueous media where TMpyP is the dianion of meso-tetrakis(N-methylpyridiniumyl)porphyrin and X- = Cl- or BPh4-. These studies were carried out to examine the effect of the metal ion and porphyrin counterion (X-) on the electrochemical properties of the TMpyP complexes with a special emphasis being given to the overall number of electrons added and the number of electrode processes upon reduction. All of the investigated compounds with electroinactive central metal ions undergo an overall addition of six electrons. This occurs for most compounds via three two-electron-transfer steps, but more than three processes are observed for porphyrins having metal ions with a low electronegativity (e.g., Cd(II)). The first reduction of each porphyrin having an M(II) ion or an electroinactive M(III) ion yields a porphyrin dianion which is characterized by an intense band located cl...