Reversible Dihydrogen Activation and Hydride Transfer by a Uranium Nitride Complex

Abstract: Cleavage of dihydrogen is an important step in the industrial and enzymatic transformation of N2 into ammonia. The reversible cleavage of dihydrogen was achieved under mild conditions (room temperature and 1 atmosphere of H2) by the molecular uranium nitride complex, [Cs{U(OSi-(OtBu)3)3}2(m-N)] 1, leading to a rare hydride–imide bridged diuranium(IV) complex, [Cs{U(OSi(OtBu)3)3}2(m-H)(m- NH)], 2 that slowly releases H2 under vacuum. This complex is highly reactive and quickly transfers hydride to acetonitrile and carbon dioxide at room temperature, affording the ketimide- and formate-bridged UIV species [Cs{U(OSi-(OtBu)3)3}2(m-NH)(m-CH3CHN)], 3 and [Cs{U(OSi-(OtBu)3)3}2(m-HCOO)(m-NHCOO)], 4

Electrochemical Reduction of CO2 Using Cu (II) and Ni (II) Complexes with 8-Hydroxyquinoline Ligand

Two dinuclear Cu (II) and Ni (II) complexes of the general formula [Cu2L2], (1), and [Ni2L6].4 (C2H5OH), (2), which L=8-Hydroxyquinoline have been synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopic methods. The crystal structure analysis showed the binuclear structure for 1 and the Cu (II) centers adopt a distorted square pyramidal geometries. Two Cu centers in complex 1 are linked via µ-O coordination bridge modes of 8-hydroxyquinoline ligands with the Cu-Cu distances of 3.534 Å. The electrochemical behavior of the free ligand and corresponding 1 and 2 complexes was studied in DMF. The cyclic voltammetry of the complexes 1 and 2 show an irreversible metal and ligand based reductions at negative potentials. The electrocatalytic activity of the complexes 1 and 2 was monitored for CO2 reduction in DMF solution. The results show that the complexes can be used as new electrocatalysts for CO2 reduction, leading to formation of carbon monoxide product

Correction: Facile N-functionalization and strong magnetic communication in a diuranium(v) bis-nitride complex (vol 10, pg 3543, 2019)

Correction for Facile N-functionalization and strong magnetic communication in a diuranium(v) bis-nitride complex' by Luciano Barluzzi et al., Chem. Sci., 2019, DOI: ; 10.1039/c8sc05721d

Synthesis of tetraarylethene luminogens by C−H vinylation of aromatic compounds with triazenes

Tetraarylethenes are obtained by acid‐induced coupling of vinyl triazenes with aromatic compounds. This new C−H activation route for the synthesis of aggregation‐ induced emission luminogens is simple, fast, and versatile. It allows the direct grafting of triarylethenyl groups onto a variety of aromatic compounds, including heterocycles, supramolecular hosts, biologically relevant molecules, and commercial polymers

The Intricate Structural Chemistry of MII2nLn-Type Assemblies

The reaction of cis-blocked, square-planar M-II complexes with tetratopic N-donor ligands is known to give metallasupramolecular assemblies of the formula M2nLn. These assemblies typically adopt barrel-like structures, with the ligands paneling the sides of the barrels. However, alternative structures are possible, as demonstrated by the recent discovery of a Pt8L4 cage with unusual gyrobifastigium-like geometry. To date, the factors that govern the assembly of (M2nLn)-L-II complexes are not well understood. Herein, we provide a geometric analysis of M2nLn complexes, and we discuss how size and geometry of the ligand is expected to influence the self-assembly process. The theoretical analysis is complemented by experimental studies using different cis-blocked Pt-II complexes and metalloligands with four divergent pyridyl groups. Mononuclear metalloligands gave mainly assemblies of type Pt8L4, which adopt barrel- or gyrobifastigium-like structures. Larger assemblies can also form, as evidenced by the crystallographic characterization of a Pt10L5 complex and a Pt16L8 complex. The former adopts a pentagonal barrel structure, whereas the latter displays a barrel structure with a distorted square orthobicupola geometry. The Pt16L8 complex has a molecular weight of more than 23 kDa and a diameter of 4.5 nm, making it the largest, structurally characterized M2nLn complex described to date. A dinuclear metalloligand was employed for the targeted synthesis of pentagonal Pt10L5 barrels, which are formed in nearly quantitative yields

The mechanism of Fe induced bond stability of uranyl( v )

The stabilization of uranyl(V) (UO21+) by Fe(II) in natural systems remains an open question in uranium chemistry. Stabilization of UVO21+ by Fe(II) against disproportionation was also demonstrated in molecular complexes. However, the relation between the Fe(II) induced stability and the change of the bonding properties have not been elucidated up to date. We demonstrate that U(V) – oaxial bond covalency decreases upon binding to Fe(II) inducing redirection of electron density from the U(V) – oaxial bond towards the U(V) – equatorial bonds thereby increasing bond covalency. Our results indicate that such increased covalent interaction of U(V) with the equatorial ligands resulting from iron binding lead to higher stability of uranyl(V). For the first time a combination of U M4,5 high energy resolution X-ray absorption near edge structure (HR-XANES) and valence band resonant inelastic X-ray scattering (VB-RIXS) and ab initio multireference CASSCF and DFT based computations were applied to establish the electronic structure of iron-bound uranyl(V)

Multitarget-Directed Gallium(III) Tris(acyl-pyrazolonate) Complexes Induce Ferroptosis in Cancer Cells via Dysregulation of Cell Redox Homeostasis and Inhibition of the Mevalonate Pathway

A series of Ga(Q(n))(3) coordination compounds have been synthesized, where HQ(n) is 1-phenyl-3-methyl-4-RC(=O)-pyrazolo-5-one. The complexes have been characterized through analytical data, NMR and IR spectroscopy, ESI mass spectrometry, elemental analysis, X-ray crystallography, and density functional theory (DFT) studies. Cytotoxic activity against a panel of human cancer cell lines was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, with interesting results in terms of both cell line selectivity and toxicity values compared with cisplatin. The mechanism of action was explored by spectrophotometric, fluorometric, chromatographic, immunometric, and cytofluorimetric assays, SPR biosensor binding studies, and cell-based experiments. Cell treatment with gallium(III) complexes promoted several cell death triggering signals (accumulation of p27, PCNA, PARP fragments, activation of the caspase cascade, and inhibition of the mevalonate pathway) and induced changes in cell redox homeostasis (decreased levels of GSH/GPX4 and NADP(H), increased reactive oxygen species (ROS) and 4-hydroxynonenal (HNE), mitochondrial damage, and increased activity of CPR and CcO), identifying ferroptosis as the mechanism responsible for cancer cell death

Synthesis of Organic Super-Electron-Donors by Reaction of Nitrous Oxide with N‐Heterocyclic Olefins

The reaction of nitrous oxide (N2O) with N-heterocyclic olefins (NHOs) results in cleavage of the N–O bond and formation of azo-bridged NHO dimers. The latter represent very electron-rich compounds with a low ionization energy. Cyclic voltammetry studies show that the dimers can be classified as new organic super-electron-donors, with a reducing power similar to what is found for tetraazafulvalene derivatives. Mild oxidants are able to convert the neutral dimers into radical cations, which can be isolated. Further oxidation gives stable dications

Synthesis and Reactivity of 1-Allenyltriazenes

1-Aryl-3,3-dialkyltriazenes have received considerable attention in the context of synthetic and medicinal chemistry. In contrast, the chemistry of other unsaturated triazenes is largely unexplored. The synthesis of 1-allenyltriazenes is described. This new class of compounds can be obtained by base-induced isomerization of 1-alkynyltriazenes. The latter are accessible by reaction of alkynyl Grignard reagents with lithium amides and nitrous oxide. 1-Allenyltriazenes were found to be thermally labile, but they can be stored without degradation at lower temperatures. In the presence of ZnCl2, 1-allenyltriazenes rearrange into N-aminopyrazoles