Effect of a proton-donating solvent on the complexation of classical and nonclassical porphyrins in a pyridine medium

The inhibitory effect of proton-donating additives (HAc) on the rate of coordination reaction (1) of tetrabenzoporphine (H 2 TBP, I), tetraphenyltetrabenzoporphine (H 2 TPTBP, II), and N-substituted porphyrins III and IV inpyridine was established. The N-H bonding state in compounds I and II and the reactivity of these compounds in reaction (1) were shown to be similar to those of nonclassical porphyrins (H 2 P), whereas N-substituted porphyrins apparently do not belong to this group. The inhibition of reaction (1) in the case of compounds III and IV is due to the high basicity of the tertiary nitrogen atoms in these molecules.