Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction

Regulation of Ferroptotic Cancer Cell Death by GPX4

TiO(2) is one of the most studied compounds in materials science. Owing to some outstanding properties it is used for instance in photocatalysis, dye-sensitized solar cells, and biomedical devices. In 1999, first reports showed the feasibility to grow highly ordered arrays of TiO(2) nanotubes by a simple but optimized electrochemical anodization of a titanium metal sheet. This finding stimulated intense research activities that focused on growth, modification, properties, and applications of these one-dimensional nanostructures. This review attempts to cover all these aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field.

TiO2 nanotubes: synthesis and applications.

N-Heterocyclic Carbenes in Late Transition Metal Catalysis

The chemistry of heterocyclic carbenes has experienced a rapid development over the last years. In addition to the imidazolin-2-ylidenes, a large number of cyclic diaminocarbenes with different ring sizes have been described. Aside from diaminocarbenes, P-heterocyclic carbenes, and derivatives with only one, or even no heteroatom within the carbene ring are known. New methods for the synthesis of complexes with N-heterocyclic carbene ligands such as the oxidative addition or the metal atom template controlled cyclization of β-functionalized isocyanides have been developed recently. This review summarizes the new developments regarding the synthesis of N-heterocyclic carbenes and their metal complexes.

Heterocyclic Carbenes: Synthesis and Coordination Chemistry

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.

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

Group 11 Metal Complexes of N-Heterocyclic Carbene Ligands: Nature of the Metal-Carbene Bond

The forefront of research into the complexes of uranium reveals chemical transformations that challenge and expand our view of this unique element. Certain ligands form multiple bonds to uranium, and small, inert molecules such as nitrogen and carbon dioxide become reactive when in complex with the metal. Such complexes provide clues to the catalytic future of uranium, in which the applications of the element extend far beyond the nuclear industry. Most excitingly, the ability of uranium to use its outermost f electrons for binding ligands might enable the element to catalyse reactions that are impossible with conventional, transition-metal catalysts.

/pdf/towards-uranium-catalysts-g0ip07bt9l.pdf

Towards uranium catalysts.

The electron-rich, six-coordinate tris-aryloxide uranium(III) complex [((AdArO)3tacn)UIII] [where (AdArOH)3tacn = 1,4,7-tris(3-adamantyl-5-tert-butyl-2-hydroxybenzyl)1,4,7-triazacyclononane] reacts rapidly with CO2 to yield [((AdArO)3tacn)UIV(CO2)], a complex in which the CO2 ligand is linearly coordinated to the metal through its oxygen atom (η1-OCO). The latter complex has been crystallographically and spectroscopically characterized. The inequivalent O–C–O bond lengths [1.122 angstroms (A) for the O–C bond adjacent to uranium and 1.277 A for the other], considered together with magnetization data and electronic and vibrational spectra, support the following bonding model: UIV=O=C⚫–O– ↔ UIV–OC–O–. In these charge-separated resonance structures, the uranium center is oxidized to uranium(IV) and the CO2 ligand reduced by one electron.

https://science.sciencemag.org/content/sci/305/5691/1757.full.pdf

A Linear, O-Coordinated η1-CO2 Bound to Uranium

Despite being implicated as important intermediates, iron(V) compounds have proven very challenging to isolate and characterize. Here, we report the preparation of the iron(V) nitrido complex, [PhB((t)BuIm)(3)Fe(V)≡N]BAr(F24) (PhB((t)BuIm)(3)(-) = phenyltris(3-tert-butylimidazol-2-ylidene)borato, BAr(F24) = B(3,5-(CF(3))(2)C(6)H(3))(4)(-)), by one electron oxidation of the iron(IV) nitrido precursor. Single-crystal x-ray diffraction of the iron(V) complex reveals a four-coordinate metal ion with a terminal nitrido ligand. Mosbauer and electron paramagnetic resonance spectroscopic characterization, supported by electronic structure calculations, provide evidence for a d(3) iron(V) metal center in a low spin (S = 1/2) electron configuration. Low-temperature reaction of the iron(V) nitrido complex with water under reducing conditions leads to high yields of ammonia with concomitant formation of an iron(II) species.

http://science.sciencemag.org/content/sci/331/6020/1049.full.pdf

Karsten Meyer

Papers

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

Group 11 Metal Complexes of N-Heterocyclic Carbene Ligands: Nature of the Metal-Carbene Bond

Towards uranium catalysts.

A Linear, O-Coordinated η1-CO2 Bound to Uranium

Synthesis, structure, and reactivity of an iron(V) nitride.