Redox effects on the coordination geometry and heme conformation of bis(N-methylimidazole) complexes of superstructured Fe-porphyrins. A spectroscopic study.

Electronic absorption, electron paramagnetic resonance (EPR), and Soret-excited resonance Raman (RR) spectra are reported for bis(N-alkylimidazole) complexes of various iron(III)-“basket-handle” (Fe(III)BHP+) and “picket-fence” (Fe(III)PFP+) porphyrins in methylene chloride. The Fe(III)BHP+ derivatives consist of four cross-trans (CT) and two adjacent-cis (AC) -linked in which the composition and the length of the handles are variable (CT Fe(III)[(C11Im)2+], CT and AC Fe(III)[((C4)2ϕ)2]+, CT Fe(III)[((C3)2ϕ)(C12)]+, CT and AC Fe(III)[((C3)2ϕ)2]+). The meso-ααββ and meso-αβαβ atropisomers of Fe(III)-tetrakis(o-pivalamidophenyl)-porphyrins represents the Fe(III)PFP+ derivatives (Fe(III)ααββ-TpivPP+ and Fe(III)αβαβ-TpivPP+, respectively). The absorption and RR data obtained for these ferric compounds were compared to those previously published for the homologous ferrous complexes (Picaud, T., Le Moigne, C., Loock, B., Momenteau, M. and Desbois, A. J. Am. Chem. Soc. 2003, 125, 11616 and Le Moigne, C., Picaud,...