Reactive high-spin iron(IV)-oxo sites through dioxygen activation in a metal-organic framework.

In nature, nonheme iron enzymes use dioxygen to generate high-spin iron(IV)=O species for a variety of oxygenation reactions. Although synthetic chemists have long sought to mimic this reactivity, the enzyme-like activation of O to form high-spin iron(IV) = O species remains an unrealized goal. Here, we report a metal-organic framework featuring iron(II) sites with a local structure similar to that in α-ketoglutarate-dependent dioxygenases.

Reversible dehydrogenation and rehydrogenation of cyclohexane and methylcyclohexane by single-site platinum catalyst.

Developing highly efficient and reversible hydrogenation-dehydrogenation catalysts shows great promise for hydrogen storage technologies with highly desirable economic and ecological benefits. Herein, we show that reaction sites consisting of single Pt atoms and neighboring oxygen vacancies (V) can be prepared on CeO (Pt/CeO) with unique catalytic properties for the reversible dehydrogenation and rehydrogenation of large molecules such as cyclohexane and methylcyclohexane. Specifically, we find that the dehydrogenation rate of cyclohexane and methylcyclohexane on such sites can reach values above 32,000 mol mol h, which is 309 times higher than that of conventional supported Pt nanoparticles.

Interlayer Structure Manipulation of Iron Oxychloride by Potassium Cation Intercalation to Steer HO Activation Pathway.

Structural regulation of the active centers is often pivotal in controlling the catalytic functions, especially in iron-based oxidation systems. Here, we discovered a significantly altered catalytic oxidation pathway via a simple cation intercalation into a layered iron oxychloride (FeOCl) scaffold. Upon intercalation of FeOCl with potassium iodide (KI), a new stable phase of K-intercalated FeOCl (K-FeOCl) was formed with slided layers, distorted coordination, and formed high-spin Fe(II) species compared to the pristine FeOCl precursor.

Designing hierarchical nanoporous membranes for highly efficient gas adsorption and storage.

Nanoporous membranes with two-dimensional materials such as graphene oxide have attracted attention in volatile organic compounds (VOCs) and H adsorption because of their unique molecular sieving properties and operational simplicity. However, agglomeration of graphene sheets and low efficiency remain challenging. Therefore, we designed hierarchical nanoporous membranes (HNMs), a class of nanocomposites combined with a carbon sphere and graphene oxide.

Efficient Hydrogen Production from Methanol Using a Single-Site Pt/CeO Catalyst.

Hydrogen is regarded as an attractive alternative energy carrier due to its high gravimetric energy density and only water production upon combustion. However, due to its low volumetric energy density, there are still some challenges in practical hydrogen storage and transportation. In the past decade, using chemical bonds of liquid organic molecules as hydrogen carriers to generate hydrogen in situ provided a feasible method to potentially solve this problem.

A Robust Pentacoordinated Iron(II) Proton Reduction Catalyst Stabilized by a Tripodal Phosphine.

A pentacoordinated triphosphine benzenedithiolatoiron(II) complex containing a vacant site for binding has been prepared and characterized. The complex is found to be a robust proton reduction catalyst with an overpotential of 0.56 V and a turnover frequency of 2900 s with respect to 0.

Computational exploration of the mechanism of copper-catalyzed aromatic C-H bond amination of benzene via a nitrene insertion approach.

The mechanism of aromatic C-H amination of benzene via a nitrene insertion approach catalyzed by the Tp(Br3)Cu(NCMe) complex was computationally investigated. The results of computational studies show that addition of the nitrene moiety of the Tp(Br3)Cu-nitrene intermediate to benzene, and therefore, to form an aziridine intermediate, is more favorable than the nitrene moiety induced hydrogen atom abstraction from a sp(2) C-H bond of benzene. Subsequently, the cleavage of a C-N bond of the aziridine intermediate followed by an H-atom transfer step might occur, due to the driving force of the rearomatization, to afford the desired aromatic C-H amination product.

Mechanistic Investigations of the AuCl3-Catalyzed Nitrene Insertion into an Aromatic C-H Bond of Mesitylene.

The AuCl3-catalyzed nitrene insertion into an aromatic C-H bond of mesitylene demonstrates a unique activity and chemoselectivity in direct C-H aminations. Mechanisms for catalytic nitrene insertion are examined here using theory. The AuCl3 catalyst favors formation of a complex with the PhI═NNs (Ns = p-nitrobenzenesulfonyl) substrate, followed by the appearance of the key (N-chloro-4-nitrophenylsulfonamido)gold(III) chloride intermediate (INT5).

Electrocatalytic proton reduction catalyzed by a dimanganese disulfide carbonyl complex containing a redox-active internal disulfide bond.

A dimanganese hexacarbonyl complex [(Mn(CO)3)2(μ-SC6H4-o-S-S-C6H4-o-μ-S-)] containing an elongated disulfide bond electrocatalyses proton reduction at moderate overpotentials of 0.55 to 0.65 V.

Electrocatalytic hydrogen generation by a trithiolato-bridged dimanganese hexacarbonyl anion with a turnover frequency exceeding 40,000 s(-1).

An unusual ionic manganese model complex [Mn(bpy)3](+)[(CO)3Mn(μ-SPh)3Mn(CO)3](-)(bpy: 2,2'-bipyridine) has been synthesized, which bears some structural resemblance to the active site of [FeFe] hydrogenase. An overpotential of 0.61 V has been determined for the electrocatalytic proton reduction using this complex in CH3CN with CF3COOH as the proton source.

Reactions of the cationic zinc thiolate model complex [Zn(Tab)4](PF6)2 with N-donor ligands and cobalt dichloride.

Reactions of [Zn(Tab)(4)](PF(6))(2) (Tab = 4-(trimethylammonio)benzenethiolate) (1) with 2,2'-bipyridine (2,2'-bipy), 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (2,9-dmphen), N-methylimidazole (N-Meim), and 2,6-bis(pyrazol-3-yl)pyridine (bppy) or with CoCl(2)·6H(2)O at the presence of N-donor ligands (2,2'-bipy, phen, 4,4'-dimethyl-2,2'-bipyridine (4,4'-dmbpy), 2,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)pyridine (bdmppy))gave rise to a family of zinc or cobalt thiolate complexes, [Zn(Tab)(2)(L)](PF(6))(2) (2: L = 2,2'-bipy, 3: L = phen, 4: L = 2,9-dmphen), [Zn(Tab)(2)(N-Meim)(2)](PF(6))(2) (5), [Zn(Tab)(2)(bppy)](PF(6))(2) (6), [Co(Tab)(2)(L)(2)](PF(6))(3) (7: L = 2,2'-bipy, 8: L = phen, 9: L = 4,4'-dmbpy), and [Co(Tab)(bdmppy)Cl](PF(6)) (10). These compounds were characterized by elemental analysis, IR spectra, UV-vis spectra,(1)H NMR, electrospray ionization (ESI) mass spectra, and single-crystal X-ray diffraction. The Zn(II) in [Zn(Tab)(2)L(n)](2+)dications of 2-5 is tetrahedrally coordinated by two Tab ligands and one L or two N-Meim ligands.

Reactions of a methylmercury zwitterionic thiolate complex [MeHg(Tab)]PF6 with various donor ligands: relevance to methylmercury detoxification.

Reaction of MeHgI with Ag(2)O in H(2)O followed by addition of equimolar TabHPF(6) in MeCN gave rise to a methylmercury zwitterionic thiolate complex [MeHg(Tab)]PF(6) (1) (TabH = 4-(trimethylammonio)benzenethiol) in a high yield. Treatment of 1 with KI and KSCN afforded an anion exchange product [MeHg(Tab)]I·0.25H(2)O (2·0.