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)[(C(11)Im)(2)(+)], CT and AC Fe(III)[((C(4))(2)phi)(2)](+), CT Fe(III)[((C(3))(2)phi)(C(12))](+), CT and AC Fe(III)[((C(3))(2)phi)(2)](+)). The meso-alphaalpha betabeta and meso-alphabeta alphabeta atropisomers of Fe(III)-tetrakis(o-pivalamidophenyl)-porphyrins represents the Fe(III)PFP(+) derivatives (Fe(III)alphaalpha betabeta-T(piv)PP(+) and Fe(III)alphabeta alphabeta-T(piv)PP(+), respectively).

Nonplanar distortions of bis-base low-spin iron(II)-porphyrinates: absorption and resonance Raman investigations of cross-trans-linked iron(II)-basket-handle porphyrin complexes.

Electronic absorption and Soret-excited resonance Raman (RR) spectra are reported for bis-N-alkylimidazole and bis-pyridine complexes of various cross-trans-linked iron(II)-"basket-handle" porphyrins (Fe(II)-BHP) in methylene chloride. These compounds enable us to characterize the spectroscopic properties of ruffled six-coordinated low-spin Fe(II)-porphyrin complexes. The visible absorption spectra show that the Q and B bands are progressively red-shifted when the handles are shortened and/or when the steric hindrance of the axial ligands is increased.

Absorption and resonance Raman investigations of ligand rotation and nonplanar heme distortion in bis-base low-spin iron(II)-tetrakis(o-pivalamidophenyl)porphyrin complexes.

The absorption and resonance Raman (RR) spectra of the bis-N-methylimidazole, bis-1,5-dicyclohexylimidazole, and bis-pyridine complexes of the meso-alphaalphabetabeta and meso-alphabetaalphabeta atropisomers of Fe(II)-tetrakis(o-pivalamidophenyl)porphyrins (Fe(II)TpivPP) were obtained in methylene chloride. The different spatial arrangements of the o-pivalamide pickets in these two Fe(II)TpivPP compounds are expected to control the absolute and relative positions of the axial ligand rings with respect to the Fe-N(pyrrole) bonds. In particular, the spectroscopic data obtained for the bis-N-methylimidazole and bis-dicyclohexylimidazole complexes of the Fe(II)[alphabetaalphabeta-TpivPP] derivative showed the most important differences.