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Effect of the axial cysteine ligand on the electronic structure and reactivity of high‐valent iron(IV) oxo‐porphyrins (Compound I): A theoretical study
Author(s) -
Choe YoongKee,
Nagase Shigeru
Publication year - 2005
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20302
Subject(s) - chemistry , reactivity (psychology) , ligand (biochemistry) , imidazole , heme , hydroxylation , density functional theory , porphyrin , catalysis , catalytic cycle , histidine , computational chemistry , stereochemistry , medicinal chemistry , photochemistry , organic chemistry , medicine , biochemistry , receptor , alternative medicine , pathology , enzyme
The effect of axial ligands on the reactivity of high‐valent iron(IV) oxo‐porphyrins (Compound I) was investigated using the B3LYP hybrid density functional method. We studied alkane hydroxylation using four models: Compound I with thiolate, imidazole, phenolate, and chloride anions as axial ligands. The first three ligands were employed as models for cysteinate, histidine, and tyrosinate, respectively. Our calculations show that anionic ligands and neutral ligands favor different electronic states for stationary points in the reaction coordinate, and the calculated energy barrier and energy of several reaction intermediates show similar values. A remarkable effect of axial ligands was found in the final product release step. Our calculations show that the thiolate ligand weakens a bond between heme and an alcohol. In contrast, the imidazole ligand significantly increases the interaction between heme and an alcohol, which causes the catalytic cycle to be less efficient. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1600–1611, 2005