Role of Microstructure and Spectrum Features on the Catalysis Effect of Ce1-x(Nd0.5Eu0.5)xO2-δSolid Solutions

Nanosized Ce^1-x）（Nd^0.5）Eu^0.5））xO^2-δ） solid solutions（x = 0.00-0.20） were synthesized by means of hydrothermal method.Then the solid solutions were ball milled with Mg2Ni and Ni powders for 20 h to get the Mg2Ni–Ni–5 mol% Ce^1-x）（Nd^0.5）Eu^0.5））xO^2-δ） composites.The structures and spectrum characteristics of the Ce^1-x）（Nd^0.5）Eu^0.5））xO^2-δ） solid solutions catalysts were analyzed systemically.XRD results showed that the doped samples exhibited single phase of CeO2 fluorite structure.The cell parameters and cell volumes were increased with increasing the doped content.Raman spectrum revealed that the peak position of F^2g mode shift to higher wavenumbers and the peak corresponding to oxygen vacancies were observed distinctly for the doped samples.UV-Vis technique indicated that the absorption peaks of Eu^3＋ and Nd^3＋ ions appeared; the bandgap energy was decreased linearly.The electrochemical and kinetic properties of the Mg2Ni–Ni–5 mol% Ce1-x（Nd0.5Eu0.5xO2-δ composites were measured.The maximum discharge capacity was increased from 722.3 mA h/g for x = 0.00 to 819.7 mA h/g for x = 0.16,and the cycle stability S20 increased from 25.0%（x = 0.00） to 42.2%（x = 0.20）.The kinetic measurement proved that the catalytic activity of composite surfaces and the hydrogen diffusion rate were improved for the composites with doped catalysts,especially for the composites with x = 0.16 and x = 0.20.The catalysis mechanism was analyzed from the point of microstructure and spectrum features of the Ce1-x（Nd0.5Eu0.5）xO2-δ solid solutions.

Nickel-catalyzed carbonylative four-component 1,4-dicarbofunctionalization of 1,3-enynes

An efficient Ni-catalyzed four-component 1,4-carbocarbonylation of 1,3-enynes with activated alkyl halides and arylboronic acids under atmospheric pressure of CO is presented.By tuning the electronic and steric effects of alkyl radicals,both electronrich and electron-deficient 1,3-enynes were compatible with this cascade.This protocol features mild conditions,broad substrate scope,excellent functional group compatibility and facile gram-scale synthesis,providing a practical approach to the quaternary carbon center-containing allenyl ketones.Mechanistic study revealed that the acyl-NiIIspecies plays an important role in both the coupling and the alkyl radical generation processes.

Nickel-catalyzed kinetic resolution to achieve P-chiral phosphine oxides and sec-phosphine oxides

P-Chiral phosphines and sec-phosphine oxides(SPO) are found in a diverse range of compounds that play crucial roles in various fields, including asymmetric catalysis, materials, agrochemistry, and pharmaceutical chemistry. Herein, we describe an enantioselective Ni-catalyzed kinetic resolution of racemic sec-phosphine oxides to obtain the corresponding optically pure Pchiral phosphine oxides and sec-phosphine oxides, respectively. These products are versatile chiral phosphine building blocks that can be used to construct an extensive range of P-chiral phosphines.

基于成对电解和光催化协同作用的镍催化环烷醇的芳基化反应

The merging of transition metal catalysis with electrochemistry has become a powerful tool for organic synthesis because catalysts can govern the reactivity and selectivity.However,coupling catalysts with alkyl radical species generated by anodic oxidation remains challenging because of electrode passivation,dimerization,and overoxidation.In this study,we developed convergent paired electrolysis for the coupling of nickel catalysts with alkyl radicals derived from photoinduced ligand-to-metal charge-transfer of cyclic alcohols and iron catalysts,providing a practical method for site-specific and remote arylation of ketones.The synergistic use of photocatalysis with convergent paired electrolysis can provide alternative avenues for metal-catalyzed radical coupling reactions.

Nickel-Catalyzed Electroreductive Syntheses of Triphenylenes Using ortho-Dihalobenzene-Derived Benzynes

Electrochemical nickel-catalyzed syntheses of triphenylenes by a)reductive trimerization of ortho-dibromobenzenes or ortho-bromoarylsulfurofluoridates,or b)reductive cross-coupling of ortho-dibromobenzenes to 2,2’-diiodobiphenyls,are described.The former provides a practical means for the construction of triphenylene derivatives in up to 87%isolated yield at room temperature.For 1,2-dihalo-3-methylbenzenes and related ortho-trisubstituted substrates,trimerizations proceed with high substrate-controlled regioselectivity for the non-C3h symmetric triphenylene isomer.

Recent advances in theoretical studies on ligand-controlled selectivity of nickel-and palladium-catalyzed cross-coupling reactions

Nickel-and palladium-catalyzed cross-coupling reactions have attracted wide attentions,while ligandcontrolled selectivity in these reactions are still elusive,and calculations can help obtain possible catalytic cycles to generate different products and provide insights into key factors of selectivity,which facilitates the development of new catalyst systems to control reaction selectivity.This review covers our efforts and some significant achievements from other groups on ligand-controlled reaction selectivity of coupling reactions,including introduction,computational methods,selectivity control by ligands in Niand Pd-catalyzed coupling reactions,as well as summary and future perspectives.