Metal ion insertion into N-alkylated and N,N′-dialkylated porphyrins

Abstract

Addition of FeCl 3/Fe to N-(2,2′-bis-p-chlorophenylethenyl)tetraphenyl porphyrin yields the iron(II) insertion product which has been characterized by extensive 1H and 2H NMR studies. The pyrrole protons of this and other N-alkyl porphyrin Fe(II) complexes shown up as four equally intense resonances with chemical shifts at 25 °C of 28, 20, 8 and −6 ppm. The NMR spectra clearly distinguish between N-alkyl porphyrin complexes of Fe(II) and Fe(III) complexes of similar symmetry in which a carbene is inserted into the FeN bond. Treatment of N,N′-bis(2,2′- p-chlorophenylethenyl)tetraphenyl porphyrin with metal carbonyls can result in the rupture of one or both NC bonds. Thus with Fe 3(CO) 12 the iron(II) carbene complex TPPFe (C = C{C 6H 4Cl} 2) is formed while Ni(CO) 4 nickel is inserted into one NC bond to form I. ( See next column). ▪