Electron transfer reaction of porphyrin and porphycene complexes of Cu(II) and Zn(II) in acetonitrile.

The outer-sphere one-electron oxidation reaction of the Cu(II) and Zn(II) complexes of nonplanar 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin and planar porphycenes as well as those of 2,3,7,8,12,13,17,18-octaethylporphyrin and 5,10,15,20-tetraphenylporphyrin by Cu(2+) giving corresponding pi-cation radicals was investigated spectrophotometrically in acetonitrile. The electron self-exchange rate constants between the parent porphyrin and porphycene complexes and their pi-cation radicals were determined using the Marcus cross relation for the electron transfer reaction. The obtained rate constants are in the order of 10(9) to 10(11) M(-1) s(-1) for the planar porphyrin and porphycene complexes and 10(4) to 10(6) M(-1) s(-1) for the nonplanar OETPP complexes at T = 25.