Change search
ReferencesLink to record
Permanent link

Direct link
O-O bond cleavage in dinuclear peroxo complexes of iron porphyrins: a quantum chemical study
Stockholm University.
2007 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 46, no 19, 7992-7997 p.Article in journal (Refereed) Published
Abstract [en]

To gain insight into the mechanisms of O-2 activation and cleavage in metalloenzymes, biomimetic metal complexes have been constructed and experimentally characterized. One such model complex is the dinuclear peroxo complex of iron porphyrins observed at low temperature in a noncoordinating solvent. The present theoretical study examines the O-O bond cleavage in these complexes, experimentally observed to occur either at increased temperature or when a strongly coordinating base is added. Using hybrid density functional theory, it is shown that the O-O bond cleavage always occurs in a state where two low-spin irons (S = +/- 1/2) are antiferromagnetically coupled to a diamagnetic state. This state is the ground state when the strong base is present and forms an axial ligand to the free iron positions. In contrast, without the axial ligands, the ground state of the clinuclear peroxo complex has two high-spin irons (S = +/- 5/2) coupled antiferromagnetically. Thus, the activation barrier for O-O bond cleavage is higher without the base because it includes also the promotion energy from the ground state to the reacting state. It is further found that this excitation energy, going from 10 unpaired electrons in the high-spin case to 2 in the low-spin case, is unusually difficult to determine accurately from density functional theory because it is extremely sensitive to the amount of exact exchange included in the functional.

Place, publisher, year, edition, pages
2007. Vol. 46, no 19, 7992-7997 p.
Keyword [en]
iron, metalloporphyrin, oxygen, peroxide
National Category
Theoretical Chemistry
URN: urn:nbn:se:kth:diva-77646DOI: 10.1021/ic7007182ISI: 000249371500042OAI: diva2:491919
QC 20120313Available from: 2012-02-07 Created: 2012-02-07 Last updated: 2012-03-13Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Johansson, Adam Johannes
In the same journal
Inorganic Chemistry
Theoretical Chemistry

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 29 hits
ReferencesLink to record
Permanent link

Direct link