Reactions of (meso-.alpha.,.alpha.,.alpha.,.alpha.-tetrakis[o-(N-methylisonicotinamido)phenyl]porphyrin)iron(5+) and (meso-tetrakis[N-methylpyridinium-4-yl]porphyrin)iron(5+) with CN-, CO2- and O2-

The picket fence porphyrin, Fe III (meso-α,α,α,α-tetrakis[o-(N-methylisonicotinamido)phenyl]porphyrin), α 4 -Fe III (TMINP) 5+ , shows two proton ionization steps in the pH regions commonly observed for water soluble Fe III porphyrins; is found to have a considerably lower tendency to dimerize than the previously reported isomeric Fe III (OH)(meso-α,α,α,α-tetrakis[o-(N-methylnicotinamido)phenyl]porphyrin) 4+ , α4-Fe III (TMNIP)(OH) 4+ .