High-valent iron in chemical and biological oxidations

Groves, John T.

doi:10.1016/j.jinorgbio.2006.01.012

Cited by 577 publications

(508 citation statements)

References 110 publications

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“…Haem and non-haem proteins use these reactive intermediates to couple the activation of dioxygen to the oxidation of their substrates. In most cases, an oxygen atom is inserted into an unactivated C-H bond of the substrate; for example, in hydroxylation reactions [1][2][3][4][5][6][7][8][9][10] . However, many other reactions, including halogenation, desaturation, cyclization, epoxidation and decarboxylation, are also known to involve oxoiron species 1,3 .…”

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confidence: 99%

“…For haem enzymes the A tensor shows a qualitative trend of 'two large negative values, one small negative value' 20,21 , thereby reflecting an intermediate spin, S = 1 spin state for the iron(IV) centre. In CPd-I intermediates, this S = 1 spin state is coupled ferromagnetically or antiferromagnetically to the porphyrin radical cation, giving an overall quartet or doublet state, respectively 3,6,7,9 . In contrast, for the non-haem case, a high-spin S = 2 state is demonstrated by 'three large negative' A tensors 1,19 .…”

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confidence: 99%

“…The Fe = O bond distances (1.64-1.68 Å), obtained from extended X-ray absorption fine structure (EXAFS) or X-ray diffraction studies, and the Fe-O stretching frequencies (776-843 cm − Iron-oxo model complexes. The first high-valent oxoiron complex was synthesized in 1981 by Groves et al 7,8 via oxidation of [(TMP)Fe III (Cl)] (TMP = meso-tetramesityl porphinate anion) with meta-chloroperbenzoic acid in a dichloromethane-methanol mixture at − 78 °C. On the basis of its absorption spectra, the electronic structure of the resultant green compound was best described as an oxoiron(IV) porphyrin π-radical cation (d 4 ) species [(TMP + • )Fe IV (O)(CH 3 OH)] + , which showed the characteristic features of Cpd-I intermediates; namely, a weak and broad Soret band at 405 nm and a Q-band at 605 nm 6,9 .…”

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“…The [(TMP + • )Fe IV (O)(CH 3 OH)] + complex was found to be a competent oxidant in olefin epoxidation and alkane hydroxylations 6,7 . Since then, a number of oxoiron(IV) porphyrin π-radicals bearing electron-rich and -deficient porphyrins (Fig.…”

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confidence: 99%

“…4) have been prepared in an effort to understand the electronic effects of the porphyrins on the chemical properties of the oxoiron(IV) intermediates 3 . The results of these studies, which are summarized in some recent review articles 3,6,7 , indicate that the electronic nature of porphyrin ligands controls the oxidizing power of oxoiron porphyrins, and that oxoiron species with electron-deficient porphyrins are more powerful oxidants in the oxygenation of organic substrates. The axial ligands bound trans to the iron-oxo moiety also markedly influence the reactivities of oxoiron(IV) porphyrin π-cation radicals.…”

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The biology and chemistry of high-valent iron–oxo and iron–nitrido complexes

2012

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selective functionalization of unactivated c-H bonds and ammonia production are extremely important industrial processes. a range of metalloenyzmes achieve these challenging tasks in biology by activating dioxygen and dinitrogen using cheap and abundant transition metals, such as iron, copper and manganese. High-valent iron-oxo and -nitrido complexes act as active intermediates in many of these processes. the generation of well-described model compounds can provide vital insights into the mechanism of such enzymatic reactions. advances in the chemistry of model high-valent iron-oxo and -nitrido systems can be related to our understanding of the biological systems.H igh-valent oxoiron(IV) and formally oxoiron(V) species have been spectroscopically identified as active intermediates in the catalytic cycles of a number of enzymatic systems 1-10 . Haem and non-haem proteins use these reactive intermediates to couple the activation of dioxygen to the oxidation of their substrates. In most cases, an oxygen atom is inserted into an unactivated C-H bond of the substrate; for example, in hydroxylation reactions [1][2][3][4][5][6][7][8][9][10] . However, many other reactions, including halogenation, desaturation, cyclization, epoxidation and decarboxylation, are also known to involve oxoiron species 1,3 . Superoxidized iron complexes with (valence) isoelectronic imido and nitrido ligands, as well as 'surface nitrides' , have also been implicated as key intermediates in the nitrogen atom transfer reactions 11 , the biological synthesis of ammonia by the nitrogenase enzyme 12-16 and the industrial Haber-Bosch process 17 .The generation of well-described model compounds can provide vital insights into the mechanism of such enzymatic reactions. Consequently, considerable effort has been made by synthetic chemists to prepare viable models for the putative reaction intermediates in the catalytic cycles of O 2 and N 2 activating enzymes. In this review, we provide an overview of all high-valent oxoiron and nitridoiron species that have been either identified or proposed as reactive intermediates in biology. Subsequently, we summarize some of the recent advances in bioinorganic chemistry that have led to the identification and isolation of iron complexes in unusually high formal oxidation states, containing iron-oxygen or iron-nitrogen multiple bonds. The spectroscopic characterization and the reactivity studies of these model complexes provide vital insights into the mechanism that nature uses to induce the reductive cleavage of dioxygen or dinitrogen in carrying out a number of important biochemical oxidative transformations. Moreover, the comparative review of the electronic structures of the isoelectronic oxoiron and nitridoiron functionalities reveals that the Fe-N bonds are intrinsically more covalent than the Fe-O bonds.

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The biology and chemistry of high-valent iron–oxo and iron–nitrido complexes

2012

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Production of alkenes and novel secondary products by P450 OleT_JE using novel H₂O₂‐generating fusion protein systems

et al. 2017

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Jeotgalicoccus sp. 8456 OleT JE (CYP152L1) is a fatty acid decarboxylase cytochrome P450 that uses hydrogen peroxide (H 2 O 2 ) to catalyse production of terminal alkenes, which are industrially important chemicals with biofuel applications. We report enzyme fusion systems in which Streptomyces coelicolor alditol oxidase (AldO) is linked to OleT JE . AldO oxidizes polyols (including glycerol), generating H 2 O 2 as a co-product and facilitating its use for efficient OleT JE -dependent fatty acid decarboxylation. AldO activity is regulatable by polyol substrate titration, enabling control over H 2 O 2 supply to minimise oxidative inactivation of OleT JE and prolong activity for increased alkene production. We also use these fusion systems to generate novel products from secondary turnover of 2-OH and 3-OH myristic acid primary products, expanding the catalytic repertoire of OleT JE .

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Oxygen‐Activating Enzymes, Chemistry of

Hess

Welford

Klinman

2008

Wiley Encyclopedia of Chemical Biology

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Aerobic organisms derive the energy required for cellular processes from the conversion of dioxygen to water, which highlights the importance of dioxygen chemistry in biologic systems. The biochemistry of dioxygen is far from simple and has been the subject of intense study in a range of chemical and biologic disciplines. The reduction of dioxygen is energetically favorable; however, dioxygen is a ground state triplet, kinetically unreactive with singlet organic molecules. Nature has developed a diverse array of catalysts to overcome this kinetic barrier. These dioxygen‐activating enzymes are divided into two classes: oxygenases and oxidases. Oxygenases incorporate directly at least one atom from dioxygen into the organic products of their reaction. Oxidases couple the reduction of dioxygen with the oxidation of substrate. Typically, enzymes that react with dioxygen contain transition metal ions and/or conjugated organic molecules as cofactors. The reaction with dioxygen is initiated by electron transfer from the cofactor to O 2 . The subsequent chemistry varies depending on both the nature of the cofactor and the protein scaffold. Here we review the fascinating chemistry of the dioxygen‐activating enzymes and identify some of the common strategies and themes that have emerged from over half a century of research.

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High-valent iron in chemical and biological oxidations

Cited by 577 publications

References 110 publications

The biology and chemistry of high-valent iron–oxo and iron–nitrido complexes

The biology and chemistry of high-valent iron–oxo and iron–nitrido complexes

Production of alkenes and novel secondary products by P450 OleT_JE using novel H₂O₂‐generating fusion protein systems

Oxygen‐Activating Enzymes, Chemistry of

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High-valent iron in chemical and biological oxidations

Cited by 577 publications

References 110 publications

The biology and chemistry of high-valent iron–oxo and iron–nitrido complexes

The biology and chemistry of high-valent iron–oxo and iron–nitrido complexes

Production of alkenes and novel secondary products by P450 OleTJE using novel H2O2‐generating fusion protein systems

Oxygen‐Activating Enzymes, Chemistry of

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Production of alkenes and novel secondary products by P450 OleT_JE using novel H₂O₂‐generating fusion protein systems