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Computational and experimental insights into the oxidative stability of iron porphyrins: A mono‐ortho‐substituted iron porphyrin with unusually high oxidative stability
Author(s) -
Khazaei Saeede,
Eskandari Mortaza,
Zakavi Saeed
Publication year - 2018
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.3869
Subject(s) - chemistry , porphyrin , steric effects , dihedral angle , oxidative phosphorylation , density functional theory , photochemistry , medicinal chemistry , crystallography , computational chemistry , stereochemistry , organic chemistry , molecule , hydrogen bond , biochemistry
The oxidative stability of iron(III) meso‐tetraarylporphyrins in oxidation of styrene with periodate decreased in the order FeT(2‐Me)PPOAc > > FeT(2‐Cl)PPOAc > FeTPPOAc > FeT(4‐OMe)PPOAc. While the observed order correlates approximately with the electron deficiency of the porphyrin ligands, FeT(2‐Me)PPOAc showed an unusually high stability (99.1% in 120 minutes) under reaction conditions. It is noteworthy that due to the presence of bulky and electronegative chlorine atoms at the ortho positions of FeT(2‐Cl)PPOAc, a higher or at least comparable oxidative stability was expected for FeT(2‐Cl)PPOAc. The energy, electronic, and structural features obtained from spin‐unrestricted hybrid density functional theory‐based calculations showed the involvement of steric and electronic effects as the main factors determining the oxidative stability of iron porphyrins. In the case of FeT(2‐Me)PPOAc, the steric bulk of methyl substituents as well as the large dihedral angle between the aryl substituents and porphyrin mean plane seem to play crucial roles in the observed oxidative stability.