View : 10 Download: 0

Synthetic Mononuclear Nonheme Iron-Oxygen Intermediates

Title
Synthetic Mononuclear Nonheme Iron-Oxygen Intermediates
Authors
Nam, Wonwoo
Ewha Authors
남원우
SCOPUS Author ID
남원우scopus
Issue Date
2015
Journal Title
ACCOUNTS OF CHEMICAL RESEARCH
ISSN
0001-4842JCR Link1520-4898JCR Link
Citation
vol. 48, no. 8, pp. 2415 - 2423
Publisher
AMER CHEMICAL SOC
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
CONSPECTUS: Mononuclear nonheme iron-oxygen species, such as iron-superoxo, -peroxo, -hydroperoxo, and -oxo, are key intermediates involved in dioxygen activation and oxidation reactions catalyzed by nonheme iron enzymes. Because these iron-oxygen intermediates are short-lived due to their thermal instability and high reactivity, it is challenging to investigate their structural and spectroscopic properties and reactivity in the catalytic cycles of the enzymatic reactions themselves. One way to approach such problems is to synthesize biomimetic iron-oxygen complexes and to tune their geometric and electronic structures for structural characterization and reactivity studies. Indeed, a number of biologically important iron-oxygen species, such as mononuclear nonheme iron (III) -superoxo, iron (III) -peroxo, iron (III) -hydroperoxo, iron (IV)-oxo, and iron(V)-oxo complexes, were synthesized recently, and the first X-ray crystal structures of iron(III)-superoxo, iron(III)-peroxo, and iron(IV)-oxo complexes in nonheme iron models were successfully obtained. Thus, our understanding of iron-oxygen intermediates in biological reactions has been aided greatly from the studies of the structural and spectroscopic properties and the reactivities of the synthetic biomimetic analogues. In this Account, we describe our recent results on the synthesis and characterization of mononuclear nonheme iron-oxygen complexes bearing simple macrocyclic ligands, such as N-tetramethylated cyclam ligand (TMC) and tetraamido macrocyclic ligand (TAML). In the case of iron-superoxo complexes, an iron(III)-superoxo complex, [(TAML)Fe-III(O-2)](2-), is described, including its crystal structure and reactivities in electrophilic and nudeophilic oxidative reactions, and its properties are compared with those of a chromium(III)-superoxo complex, [(TMC)Cr-III(O-2)(Cl)](+), with respect to its reactivities in hydrogen atom transfer (HAT) and oxygen atom transfer (OAT) reactions. In the case of iron-peroxo intermediates, an X-ray crystal structure of an iron(III)-peroxo complex binding the peroxo ligand in a side-on (eta(2)) fashion, [(TMC)Fe-III(O-2)](+), is described. In addition, iron(III) -peroxo complexes binding redox-inactive metal ions are described and discussed in light of the role of redox-inactive metal ions in O-O bond activation in cytochrome c oxidase and O-2-evolution in photosystem II. In the case of iron-hydroperoxo intermediates, mononuclear nonheme iron(III)-hydroperoxo complexes can be generated upon protonation of iron(III)-peroxo complexes or by hydrogen atom abstraction (HAA) of hydrocarbon C-H bonds by iron(III)-superoxo complexes. Reactivities of the iron(III)-hydroperoxo complexes in both electrophilic and nucleophilic oxidative reactions are described along with a discussion of O-O bond cleavage mechanisms. In the last section of this Account, a brief summary is presented of developments in mononuclear nonheme iron(IV)-oxo complexes since the first structurally characterized iron(IV)-oxo complex, [(TMC)Fe-IV(O)](2+), was reported. Although the field of nonheme iron-oxygen intermediates (e.g., Fe-O-2, Fe-O2H, and Fe-O) has been developed greatly through intense synthetic, structural, spectroscopic, reactivity, and theoretical studies in the communities of bioinorganic and biomimetic chemistry over the past 10 years, there is still much to be explored in trapping, characterizing, and understanding the chemical properties of the key iron-oxygen intermediates involved in dioxygen activation and oxidation reactions by nonheme iron enzymes and their biomimetic compounds.
DOI
10.1021/acs.accounts.5b00218
Appears in Collections:
자연과학대학 > 화학·나노과학전공 > Journal papers
Files in This Item:
There are no files associated with this item.
Export
RIS (EndNote)
XLS (Excel)
XML


qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE