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Gutkina, E. A.; Rubtsova, T. B.; Shteinman, A. A.

doi:10.1023/a:1022580903767

Cited by 12 publications

(4 citation statements)

References 8 publications

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“…77 In comparison to the H2O2-driven reaction, oxidation of alkanes with these systems proceeds much slower and substrates containing exclusively aliphatic primary and secondary C−H bonds cannot be activated. Shteinman et al [78][79][80][81] introduced the tetradentate ligand TPCAH bearing an amide functionality (23, Figure 7), which was also successfully applied in iron-based catalytic oxygenation of alkane substrates with H2O2. The mononuclear complex Scheme 4 Selective oxidation of secondary C−H bonds in complex substrates using [Fe II (21a)](SbF6)2 and H2O2.…”

Section: Iron Nonheme Complexes Bearing Pure N-donor Ligandsmentioning

confidence: 99%

Molecular iron complexes as catalysts for selective C–H bond oxygenation reactions

2015

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The selective oxygenation of C-H bonds is a promising and interesting task for both academia and chemical industry. Inspired by the efficiency and selectivity of naturally occurring enzymes, iron heme and nonheme complexes have proven to be valuable candidates for the development of environmentally friendly catalysts as alternative to traditional systems. This feature article summarises developments of the last decade regarding oxygenation reactions of aliphatic and aromatic substrates with various oxidants catalysed by molecular iron complexes. With a special focus on the catalytic performance of the systems, both the potential and the limitations as well as mechanistic aspects are discussed in some detail.

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Section: Iron Nonheme Complexes Bearing Pure N-donor Ligandsmentioning

confidence: 99%

Molecular iron complexes as catalysts for selective C–H bond oxygenation reactions

2015

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“…It could be the nitrogen atoms from the three amide groups of the peptide bonds starting to coordinate with the Fe(II) ion together with the three cysteine residues, resulting in a hexacoordinated Fe(II) complex, with nitrogen and sulfur atoms being the only ligands in the {3 S – , 3 N – } mode. The possibility of Fe(II) binding by amides has already been documented in the literature, not only for peptides but also for macrocycles and other ligands. − Moreover, taking into consideration the borderline acid character of Fe(II), the displacement of oxygen ligands by nitrogen donors would most probably result in more stable complexes. With scarce literature regarding the peptide complexes of Fe(II), there are almost no data on the p K a values of amide nitrogen in such systems; however, values obtained by us are consistent with those proposed in recent work on Fe(II)/peptide systems, suggesting that indeed amides likely enter the Fe(II) coordination sphere under alkaline pH conditions.…”

Section: Resultsmentioning

confidence: 95%

Fe(II), Mn(II), and Zn(II) Binding to the C-Terminal Region of FeoB Protein: An Insight into the Coordination Chemistry and Specificity of the Escherichia coli Fe(II) Transporter

Orzel,

Pelucelli,

Ostrowska

et al. 2023

Inorg. Chem.

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The interactions between two peptide ligands [Ac763CCAASTTGDCH773 (P1) and Ac743RRARSRVDIELLATRKSVSSCCAASTTGDCH773 (P2)] derived from the cytoplasmic C-terminal region of Eschericha coli FeoB protein and Fe(II), Mn(II), and Zn(II) ions were investigated. The Feo system is regarded as the most important bacterial Fe(II) acquisition system, being one of the key virulence factors, especially in anaerobic conditions. Located in the inner membrane of Gram-negative bacteria, FeoB protein transports Fe(II) from the periplasm to the cytoplasm. Despite its crucial role in bacterial pathogenicity, the mechanism in which the metal ion is trafficked through the membrane is not yet elucidated. In the gammaproteobacteria class, the cytoplasmic C-terminal part of FeoB contains conserved cysteine, histidine, and glutamic and aspartic acid residues, which could play a vital role in Fe(II) binding in the cytoplasm, receiving the metal ion from the transmembrane helices. In this work, we characterized the complexes formed between the whole cytosolic C-terminal sequence of E. coli FeoB (P2) and its key polycysteine region (P1) with Fe(II), Mn(II), and Zn(II) ions, exploring the specificity of the C-terminal region of FeoB. With the help of a variety of potentiometric, spectroscopic (electron paramagnetic resonance and NMR), and spectrometric (electrospray ionization mass spectrometry) techniques and molecular dynamics, we propose the metal-binding modes of the ligands, compare their affinities toward the metal ions, and discuss the possible physiological role of the C-terminal region of E. coli FeoB.

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“…In general, stereospecific alkane oxidation reactions catalyzed by non-heme iron complexes are rare, 12 and every new example is interesting. The ligand composition of iron in complexes 2, 3 and 5 is similar to that in the iron tripicolylamine (TPA) complexes 29 that also catalyze stereospecific alkane oxidation. The ligand environments in 2, 3, and 5 differ from the TPA complexes in the respect that one pyridine nitrogen (from the TPA ligand) has been replaced by an oxygen of a carboxylate.…”

Section: Catalytic Activity Of Complexes 2 3 and 5 In Alkane Oxidatio...mentioning

confidence: 85%

“…However, the data in these papers does not point uniquely to either a mono-or dinuclear complex as the active catalyst in oxo transfer and usually a mechanism involving a mononuclear center is suggested. 29 According to mass spectrometry data, the dinuclear structure of complex 2 is stable up to micromolar concentrations in MeCN due to the encapsulation of the iron ions by the framework polydentate ligand. Therefore it is possible to conclude in our case that the Fe 2 O centers with labile coordination sites are active in oxo-transfer catalysis.…”

Section: Catalytic Activity Of Complexes 2 3 and 5 In Alkane Oxidatio...mentioning

confidence: 99%

Tetranuclear iron(iii) complexes of an octadentate pyridine-carboxylate ligand and their catalytic activity in alkane oxidation by hydrogen peroxide

et al. 2006

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Reaction of the octadentate ligand 2,6-bis{3-[N,N-di(2-pyridylmethyl)amino]propoxy}benzoic acid (LH) with Fe(ClO4)3 leads to the formation of the tetranuclear complexes [Fe4(mu-O)2(LH)2(ClCH2-CO2)4](ClO4)4 (1), [{Fe2(mu-O)L(R-CO2)}2](ClO4)4 (2 R = C6H5-, 3 R = CH3-, 4, R = ClCH2-). The crystal structures of complexes 1 and 2 reveal that they consist of two Fe(III)2(mu-O)(mu-RCO2)2 cores that are linked via the two LH/L ligands to give a "dimer of dimers" structure. Complex assumes a helical shape, with protonated carboxylic acid moieties of the two ligands forming a hydrogen-bonded pair at the center of the cation. In complexes 2, 3 and 4, central carboxylates of the two ligands bridge the iron ions in each of the two Fe2O units, with an interdimer iron-iron separation of approximately 10 A and an intradimer separation of approximately 3.1 A. The second carboxylate bridge within the Fe2O units is defined by exogenous benzoate (2), acetate (3) or chloroacetate (4) ligands. The aqua complex [{Fe2(mu-O)L(H2O)2}2](ClO4)6 (5) is proposed to have a similar structure, but with the exogenous bridging carboxylates replaced by two terminal water ligands. These complexes exhibit electronic and Mössbauer spectral features that are similar to those of (mu-oxo)diiron(III) proteins as well as other related (mu-oxo)bis(mu-carboxylato)diiron(III) complexes. This similarity shows that these properties are not significantly affected by the nature of the bridging exogenous carboxylate, and that the octadentate framework ligand is essential in stabilizing the "dimer of dimers" structure. This structural feature remains in highly diluted solution (10(-5) M) as evidenced by electrospray ionization mass-spectroscopy (ES MS). Cyclic voltammetric studies of complexes 2 and 5 showed two irreversible two-electron reductions, indicating that the two Fe2O units of the tetranuclear complexes behave as distinct redox entities. Complexes 2, 3 and, especially, the aqua complex 5 are active alkane oxidation catalysts. Catalytic reactions carried out with alkane substrate molecules and hydrogen peroxide predominantly gave alcohols. High stereospecificity in the oxidation of cis-1,2-dimethylcyclohexane supports the metal-based molecular mechanism of O-insertion into C-H bonds postulated for non-heme iron enzymes such as methane monooxygenase.

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Untitled

Cited by 12 publications

References 8 publications

Molecular iron complexes as catalysts for selective C–H bond oxygenation reactions

Molecular iron complexes as catalysts for selective C–H bond oxygenation reactions

Fe(II), Mn(II), and Zn(II) Binding to the C-Terminal Region of FeoB Protein: An Insight into the Coordination Chemistry and Specificity of the Escherichia coli Fe(II) Transporter

Tetranuclear iron(iii) complexes of an octadentate pyridine-carboxylate ligand and their catalytic activity in alkane oxidation by hydrogen peroxide

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