A facile, highly stereo- and regioselective hydrometalation of alkynes generating alkenylmetal complex is disclosed for the first time from a reaction of alkyne, carboxylic acid, and a zerovalent group 10 transition metal complex M(PEt(3))(4) (M = Ni, Pd, Pt). A mechanistic study showed that the hydrometalation does not proceed via the reaction of alkyne with a hydridometal generated by the protonation of a carboxylic acid with Pt(PEt(3))(4), but proceeds via a reaction of an alkyne coordinate metal complex with the acid. This finding clarifies the long proposed reaction mechanism that operates via the generation of an alkenylpalladium intermediate and subsequent transformation of this complex in a variety of reactions catalyzed by a combination of Brϕnsted acid and Pd(0) complex. This finding also leads to the disclosure of an unprecedented reduction of alkynes with formic acid that can selectively produce cis-, trans-alkenes and alkanes by slightly tuning the conditions.

Removing NO x by supported catalysts is important for industrial flue gases and exhaust fumes of diesel engines at low temperature (100-300 °C). However, it is still a challenge to develop the low-temperature catalyst (LTC) for selective catalytic reduction of NO x , especially at temperatures below 200 °C. This paper reviews the effect of the different carriers with different active centres. Most supported metal oxide catalysts are prepared by impregnation method. But under the same condition, catalysts perform better if they were prepared by sol-gel method. Also, this paper described and compared the research progress of reaction mechanism and kinetics of the supported catalysts which were used for the selective catalytic reduction of NO x at low temperature. There are different mechanisms because of the different reducing agents and active centres. The L-H and E-R mechanisms, or both of them coexisting, can explain the overall mechanism. In order to research the mechanism thoroughly, the exploration of the reactions of the surface chemical process may be a direction to develop low temperature supported catalysts for removing NO x .

A Cu-catalyzed selective aerobic heterocoupling of terminal alkynes is disclosed, which enables the synthesis of a broad range of unsymmetrical 1,3-diynes in good to excellent yields. The results disprove the long-held belief that homocouplings are exclusively favored in the Glaser-Hay reaction.

Copper catalyzed the aerobic oxidative coupling of terminal alkynes with H-phosphonates to afford alkynylphosphonates in high yields.

Ni 2 (3,5-bis(N-methylimidazolylidenylmethyl)pyrazolate) 2 ](PF 6 ) 2 (1), [Ni 2 (µ-OH)(3,5-bis(N-pycolylimidazolylidenylmethyl)pyrazolate)](PF 6 ) 2 (2), and [Ni 2 (µ-OH)(3,5-bis(N-pyridylimidazolylidenylmethyl)pyrazolate)](PF 6 ) 2 (3) have been prepared from the corresponding imidazolium salts via in situ generated silver-carbene complexes. The complexes and imidazolium salts were characterized by elemental analyses and NMR spectroscopy. The structures of 1-3 were identified by X-ray diffraction analysis. In complex 1, two nickel(II) ions are sandwiched by two 3,5-bis(N-methylimidazolylidenylmethyl)pyrazolates behaving as anionic tetradentate ligands. Complexes 2 and 3 contain Ni 2 (µ-OH) cores with two nickel centers bridged by anionic hexadentate imidazolylidene ligands. Complexes 2 and 3 show excellent catalytic activities in Suzuki-Miyaura and Kumada-Corriu coupling reactions of various aryl chlorides. The cross-coupling reactions of deactivated aryl chlorides with arylboronic acids and Grignard reagents have been accomplished in excellent yields at low catalyst loadings.

The mononuclear complexes [Ag(H2L1)(Py)2](NO3) x H2O (1, H2L1 = 2,6-bis(5-methyl-1H-pyrazol-3-yl)pyridine) and [Ag(NO3)(L()] (2, L2 = 2,6-bis(5-methyl-1-isopropyl-1H-pyrazol-3-yl)pyridine), dinuclear complex [Ag2(H2L3)2(HL4)2] (3, H2L3 = 2,6-bis(5-phenyl-1H-pyrazol-3-yl)pyridine, HL4 = 6-(5-phenyl-1H-pyrazolyl-3-yl)picolinate), one-dimensional polymer {[Ag2(H2L1)2](NO3)2 x H2O}(n) (4), and hexanuclear clusters [Ag6(HL1)4](X)2 (X = NO3-, 5 ; BF4-, 6 ; ClO4-, 7) stabilized by pincer-like bispyrazolyl ligands have been prepared and characterized using (1)H NMR spectroscopy, elemental analysis, IR spectroscopy, luminescence spectroscopy and X-ray diffraction. In complex , there is a ligand unsupported Ag-Ag bond between the two silver atoms. Complex displays a one-dimensional polymer consisting of an infinite Ag-Ag chain and every two adjacent silver ions are bridged by an H2L1 ligand. Complexes and have the same Ag6 cores in which six silver atoms are held together by four HL1 and five Ag-Ag bonds, while complex was held together by six Ag-Ag bonds. The silver-silver distances in these complexes are found in the range of 2.874(1)-3.333(2) A for ligand supported, and 3.040(1) A for ligand unsupported Ag-Ag bonds, respectively. Complexes 3-7 are strongly luminescent due to either intraligand or metal-ligand charge transfer processes.

Reactions of the imidazolium salts or their corresponding silver carbene complexes with copper powder afforded unusual copper(II) hydroxide complexes of N-heterocyclic carbenes: [Cu 2 (μ-OH)-( L1)](PF 6 ) 2 (2; L1 = 3,5-bis(N-picolylimidazolylidenylmethyl)pyrazolate), [Cu 4 (μ 3 -OH) 2 (L2) 2 ](PF 6 ) 4 (3; L2 = 3,5-bis(N-pyridylimidazolylidenylmethyl)pyrazolate), and [Cu 4 (μ 3 -OH) 2 (L3) 2 ](PF 6 ) 4 (4; L3 = 3,5-bis(N-pyrimidylimidazolylidenylmethyl)pyrazolate). The same reaction of 3,5-bis(N-thiophenylimidazoliumylmethyl)pyrazole yielded a dinuclear Cu(II)-NHC complex, [Cu 2 (L4) 2 ](PF 6 ) 2 (5; L4 = 3,5-bis(N-thiophenylimidazolylidenylmethyl)pyrazolate). The complexes have been fully characterized by X-ray diffraction analysis, elemental analysis, and IR and ESI-MS spectra. A catalytic study shows that complex 4 is highly active in the N-arylation reactions of imidazoles and aromatic amines with arylboronic acids in methanol at room temperature under base-free conditions.

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