Durene Capped Porphyrin Complexes of Iron(II). Part II; Binding of Imidazoles, and Spectroscopic Trends Within Fe(porp)B(L) Species (B = imidazole base; L = RNC, CO, O2)
David, S., James, B.R., and David Dolphin
J. Inorg. Biochem.
Solution equilibria are presented for in situ reactions of the type FeII(porp) + B →← FeII(porp)B, where porp represents the dianion of some durene-capped porphyrins with variable length linking methylene straps, and B is 1-Me, 1,2-di-Me, or 1,5-dicyclohexylimidazole. Increasing distortion of the porphyrin skeleton has no effect on coordination of B at the unhindered side of the capped porphyrin. Increasing skeleton distortion gives rise to regular trends within the visible spectra of the free base porphyrins, the hemin (FeIII) chlorides, and 6-coordinate FeII(porp)B(L) species (L = RNC, CO, O2), whereas the visible spectra of FeII(porp) and of FeII(porp)B species are independent of the nature of porp and B, which may be related to greater flexibility of the lower coordination number systems. The ν(CO) data for the FeII(porp)(CO)B species are discussed briefly.