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Low-Spin Ferriheme Models of the Cytochrome: Correlation of Molecular Structure with EPR spectral type.

Low-Spin Ferriheme Models of the Cytochrome: Correlation of Molecular Structure with EPR spectral type.

Authors :
Yatsunyk, Libya A.
Carducci, Michael D.
Walker, F. Ann
Source :
Journal of the American Chemical Society. 12/24/2003, Vol. 125 Issue 51, p15986-16005. 20p.
Publication Year :
2003

Abstract

The preparation and characterization of the following bis-imidazole and bis-pyridine complexes of octamethyltetraphenylporphyrinatoiron(III), Fe(III) OMTPP, octamethyltetraphenylporphyrinatoiron (III), Fe-(III)OETPP, and tetra-β,β-tetramethylenetetraphenylporphyrinatoiron(III), Fe(III)TC[SUB6]TPP, are reported: paral-[FeOMTPP(1-Melm)[SUB2]]Cl, perp-[FeOMTPP(1-Melm)[SUB2]]Cl, [FeOETPP(1-Melm)[SUB2]Cl, [FeTC[SUB6]TPP(l-Melm)[SUB2]]Cl,[FeOMTPP(4Me[SUB2]Npy[SUB2]]Cl, and [FeOMTPP(2-MeHim)[SUB2]]Cl. Crystal structure analysis shows that paral-[FeOMTPP(1-Melm)[SUB2]]Cl has its axial ligands in close to parallel orientation (the actual dihedral angle between the planes of the imidazole ligands is 19.5°), while perp-[FeOMTPP(l-Melm)[SUB2]]Cl has the axial imidazole ligand planes oriented at 90° to each other and 29° away from the closest N[SUBP]-Fe-N[SUBP] axis. [FeOETPP-(1-Melm)[SUB2]]Cl has its axial ligands close to perpendicular orientation (the actual dihedral angle between the planes of the imidazole ligands is 73.1°). In all three cases the porphyrin core adopts relatively purely saddled geometry. The [FeTC[SUB6]TPP1-Melm)[SUB2]]Cl complex is the most planar and has the highest contribution of a ruffled component in the overall saddled structure compared to all other complexes in this study. The estimated numerical contribution of saddled and ruffled components is 0.68:0.32, respectively. Axial ligand planes are perpendicular to each other and 15.3° away from the closest N[SUBP]-Fe-N[SUBP] axis. The Fe-N[SUBP] bond is the longest in the series of octaalkyltetraphenylporphyrinatoiron complexes due to [FeTC[SUB6]TPP-(1-Melm)[SUB2]]Cl having the least distorted porphyrin core. In addition to these three complexes, two crystalline forms each of [FeOMTPP(4-Me[SUB2]NPy)[SUB2]Cl and [FeOMTPP(2-MeHlm)[SUB2]]Cl were obtained. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00027863
Volume :
125
Issue :
51
Database :
Academic Search Index
Journal :
Journal of the American Chemical Society
Publication Type :
Academic Journal
Accession number :
12120967
Full Text :
https://doi.org/10.1021/ja036398r