Spectral Evidence and Kinetics for Formation of the Sitting-Atop Complex of Copper(II) Ion with 5,10,15,20-Tetraphenylporphyrin in Acetonitrile

Abstract The kinetic parameters for the formation of the sitting-atop (SAT) complex of the copper(II) ion with 5,10,15,20-tetraphenylporphyrin (H2tpp) were directly determined in acetonitrile. The large ΔH≠ and ΔS≠ values imply that deformation of the porphyrin ring is required during the activation process. In the SAT complex, the protons bound to the pyrrole nitrogens remain on the nitrogens and by the addition of a base such as pyridine, they are abstracted to form the Cu(tpp) complex, in which the copper(II) ion is incorporated into the porphyrin core.