Novel Brønsted Acid Catalyzed C-C Bond Activation and α-Alkylation of Ketones.

A novel approach for the -alkylation of ketones was developed using Brønsted acid-catalyzed C-C bond cleavage. Both aromatic and aliphatic ketones reacted smoothly with 2-substituted 1,3-diphenylpropane-1,3-diones to afford -alkylation products with high yields and with excellent regioselectivity, in which the 1,3-dicarbonyl group acted as a leaving group in the presence of the catalyst TfOH. Mechanism experiments showed that the -C-C bond cleavage of diketone and the shift of the equilibrium towards the enol formation from ketone are driving forces that induce the desired products.

Strategies for Promoting Catalytic Performance of Ru-Based Electrocatalysts towards Oxygen/Hydrogen Evolution Reaction.

Ru-based materials hold great promise for substituting Pt as potential electrocatalysts toward water electrolysis. Significant progress is made in the fabrication of advanced Ru-based electrocatalysts, but an in-depth understanding of the engineering methods and induced effects is still in their early stage. Herein, we organize a review that focusing on the engineering strategies toward the substantial improvement in electrocatalytic OER and HER performance of Ru-based catalysts, including geometric structure, interface, phase, electronic structure, size, and multicomponent engineering.

Interfacial built-in electric-field for boosting energy conversion electrocatalysis.

The formation of a built-in electric field (BIEF) can induce electron-rich and electron-poor counterparts to synergistically modify electronic configurations and optimize the binding strengths with intermediates, thereby leading to outstanding electrocatalytic performance. Herein, a critical review regarding the concept, modulation strategies, and applications of BIEFs is comprehensively summarized, which begins with the fundamental concepts, together with the advantages of BIEF for boosting electrocatalytic reactions. Then, a systematic summary of the advanced strategies for the modulation of BIEF along with the in-detail mechanisms in its formation are also added.

Introducing Te for boosting electrocatalytic reactions.

The deployment of robust catalysts for electrochemical reactions is a critical topic for energy conversion techniques. Te-based nanomaterials have attracted increasing attention for their application in electrochemical reactions due to their positive influence on the electrocatalytic performance induced by their distinctive electronic and physicochemical properties. Herein, we have summarized the recent progress on Te-based nanocatalysts for electrocatalytic reactions by primarily focusing on the positive influence of Te on electrocatalysts.

Intensifying Hydrogen Spillover for Boosting Electrocatalytic Hydrogen Evolution Reaction.

Hydrogen spillover has attracted increasing interests in the field of electrocatalytic hydrogen evolution reaction (HER) in recent years because of their distinct reaction mechanism and beneficial terms for simultaneously weakening the strong hydrogen adsorption on metal and strengthening the weak hydrogen adsorption on support. By taking advantageous merits of efficient hydrogen transfer, hydrogen spillover-based binary catalysts have been widely investigated, which paves a new way for boosting the development of hydrogen production by water electrolysis. In this paper, we summarize the recent progress of this interesting field by focusing on the advanced strategies for intensifying the hydrogen spillover towards HER.

Pd-Based Metallenes for Fuel Cell Reactions.

Pd-based metallenes, atomically thin layers composed primarily of under-coordinated Pd atoms, have emerged as the newest members in the family of two-dimensional (2D) nanomaterials. Moreover, the unique physiochemical properties, high intrinsic activity associated with metallenes coupled with the ease of applying chemical modifications result in great potential in catalyst engineering for fuel cell reactions. Especially in recent years, interest in Pd-based metallenes is growing, as evidenced by surge in available literatures.

The Triplet Hydroxyl Radical Complex of Phosphorus Monoxide.

Phosphorus monoxide ( PO) is a key intermediate in phosphorus chemistry, and its association with the hydroxyl radical ( OH) to yield metaphosphorous acid (cis-HOPO) contributes to the chemiluminescence in the combustion of phosphines. When photolyzing cis-HOPO in an Ar-matrix at 2.8 K, the simplest dioxophosphorane HPO and an elusive hydroxyl radical complex (HRC) of PO form.

Spectroscopic Properties, Conformation and Structure of Difluorothiophosphoryl Isocyanate in the Gaseous and Solid Phase.

Difluorothiophosphoryl isocyanate, FP(S)NCO was characterized with UV/vis, NMR, IR (gas and Ar-matrix), and Raman (liquid) spectroscopy. Its molecular structure was also established by means of gas electron diffraction (GED) and single crystal X-ray diffraction (XRD) in the gas phase and solid state, respectively. The analysis of the spectroscopic data and molecular structures is complemented by extensive quantum-chemical calculations.

Hydrogen-Atom Tunneling in Metaphosphorous Acid.

Invited for the cover of this issue is X. Zeng and co-workers at Soochow University, University of Stuttgart, and Max-Planck Institute for Solid State Research. The image depicts the fast tunneling transformation of the highly elusive metaphosphorous acid (HOPO).

Hydrogen-Atom Tunneling in Metaphosphorous Acid.

Metaphosphorous acid (HOPO), a key intermediate in phosphorus chemistry, has been generated in syn- and anti-conformations in the gas phase by high-vacuum flash pyrolysis (HVFP) of a molecular precursor ethoxyphosphinidene oxide (EtOPO→C H +HOPO) at ca. 1000 K and subsequently trapped in an N -matrix at 2.8 K.

The Simplest, Isolable, Alkynyl Isocyanate HC≡CNCO: Synthesis and Characterization.

Alkynyl isocyanates have been postulated as highly reactive intermediates in synthetic chemistry. Herein, the parent molecule HC≡CNCO is isolated for the first time. In sharp contrast to the previously reported short lifetime (ca.

Spectroscopic identification of monomeric methyl metaphosphate.

Monomeric methyl metaphosphate (CHOPO), a highly electrophilic phosphorylating intermediate in chemical oligonucleotide synthesis, has been generated in the gas phase by high-vacuum flash pyrolysis (1000 K) of methyl 2-butenylphosphonate. In addition to the unambiguous characterization using IR spectroscopy in solid N-, Ar-, and Ne-matrices, the formation CHOPO in the photooxidation of the prototypical phosphinidene oxide CHPO by O with O-isotope scrambling has been observed in the solid N-matrix (15 K).

Phosphorus Analogues of Methyl Nitrite and Nitromethane: CH OPO and CH PO.

Methoxyphosphinidene oxide (CH OPO) and isomeric methyldioxophosphorane (CH PO ) are key intermediates in the degradation of organophosphorus compounds (OPCs). Unlike the nitrogen analogues CH ONO and CH NO , the experimental data for these two prototypical OPCs are scarce. By high-vacuum flash pyrolysis (HVFP) of the diazide CH OP(O)(N ) at 1000 K, the cis and trans conformers of CH OPO have been generated in the gas phase and subsequently isolated in cryogenic Ar and N matrices for IR spectroscopic characterization.

Chloro- and Dichloro-methylsulfonyl Nitrenes: Spectroscopic Characterization, Photoisomerization, and Thermal Decomposition.

Chloro- and dichloro-methylsulfonyl nitrenes, CH₂ClS(O)₂N and CHCl₂S(O)₂N, have been generated from UV laser photolysis (193 and 266 nm) of the corresponding sulfonyl azides CH₂ClS(O)₂N₃ and CHCl₂S(O)₂N₃, respectively. Both nitrenes have been characterized with matrix-isolation IR and EPR spectroscopy in solid N₂ (10 K) and glassy toluene (5 K) matrices. Triplet ground-state multiplicity of CH₂ClS(O)₂N (|/| = 1.

Oxidation of a phosphinidene oxide: formation of a dioxaphosphirane oxide with oxygen scrambling.

The oxidation of a prototypical phosphinidene oxide FP[double bond, length as m-dash]O has been studied in O2-doped Ar and N2 matrices at 10 K. Upon 266 nm laser irradiation, FP[double bond, length as m-dash]O combines with O2 and yields the cyclic peroxide, dioxaphosphirane oxide FP([double bond, length as m-dash]O)(O2). Unexpected oxygen scrambling occurs during the oxygenation as evidenced by the observation of a 1 : 2 mixture of FP([double bond, length as m-dash]16O)(18O18O) and FP([double bond, length as m-dash]18O)(16O18O) when 18O2 was used.

Methoxyphosphinidene and Isomeric Methylphosphinidene Oxide.

A rare oxyphosphinidene (Me-OP) has been generated in the triplet ground state through either photolysis (266 nm) or flash-vacuum pyrolysis (FVP, 700 °C) of methoxydiazidophosphine MeOP(N). Upon ArF laser irradiation (193 nm), an unprecedented isomerization from Me-OP to the long-sought methylphosphinidene oxide (Me-PO) occurs in cryogenic Ne- and N-matrices. Alternatively, the latter can be efficiently generated through photolysis (193 nm) or FVP (ca.

The Trifluoromethyl Sulfinyl and Oxathiyl Radicals.

Two hitherto unreported sulfur-centered radicals CF SO and CF OS were generated in the gas phase through high-vacuum flash pyrolyses of sulfoxide CF S(O)X (X=CF , Cl, PhO) precursors. The CF OS molecule is the first experimental example that constitutes an oxathiyl radical. It was isolated and characterized by combining matrix-isolation IR and UV/Vis spectroscopy with quantum chemical computations up to the UCCSD(T)-F12/cc-pVTZ-F12 level of theory.