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A computational analysis of electromerism in hemoprotein Fe(I) models.
MedLine Citation:
PMID:  20437065     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
The electronic structures of formally Fe(I) centers in thiolate- and imidazole-ligated hemoproteins are examined with density functional theory. The S = 1/2 spin state of the imidazole-ligated model apparently features a net total of one unpaired electron on the porphyrin, suggestive of a macrocycle-centered reductive process; however, this spin density originates from two different orbitals, each carrying 0.5 spin units on the porphyrin. Under these conditions, the system may be described as S = 3/2 Fe(I) (d(xy)(2)d(xz)(1)d(yz)(1)dz2(1)) antiferromagnetically coupled to a porphyrin triplet state; nevertheless, there is still the caveat that the iron d (xz) and d (yz) orbitals are strongly mixed with porphyrin orbitals, to such an extent that they each harbor 0.5 spin units and hence an alternative description as Fe(II) or Fe(III) cannot be ruled out. Electromerism phenomena are described in the formally Fe(I) systems examined here, with electronic structures varying between Fe(II) and Fe(III) in various spin states, coupled either ferro- or antiferromagnetically to porphyrin radicals. The main factors controlling this electromerism appear to be the identity of the axial ligand, the iron-axial ligand bond length, and the overall spin state; heme deformations, ligand charge, or medium polarity do not appear to qualitatively affect the electronic structures of these systems.
Authors:
Radu Silaghi-Dumitrescu; Sergei V Makarov
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-05-01
Journal Detail:
Title:  Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry     Volume:  15     ISSN:  1432-1327     ISO Abbreviation:  J. Biol. Inorg. Chem.     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-07-23     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9616326     Medline TA:  J Biol Inorg Chem     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  977-86     Citation Subset:  IM    
Affiliation:
Department of Chemistry and Chemical Engineering, Babes-Bolyai University, Cluj-Napoca, 400028, Romania. rsilaghi@chem.ubbcluj.ro
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