Structure and spectroscopic properties of the dimeric copper(I) N‐heterocyclic carbene complex [Cu2(CNCt‐Bu)2](PF6)2

In recent years, the use of copper N‐heterocyclic carbene (NHC) complexes has expanded to fields besides catalysis, namely medicinal chemistry and luminescence applications. In the latter case, multinuclear copper NHC compounds have attracted interest, however, the number of these complexes in the literature is still quite limited. Bis[μ‐1,3‐bis(3‐tert‐butylimidazolin‐2‐yliden‐1‐yl)pyridine]‐1κ⁴C²,N:N,C^2′;2κ⁴C²,N:N,C^2′‐dicopper(I) bis(hexafluoridophosphate), [Cu₂(C₁₉H₂₅N₅)₂](PF₆)₂, is a dimeric copper(I) complex bridged by two CNC, i.e. bis(N‐heterocyclic carbene)pyridine, ligands. Each Cu^I atom is almost linearly coordinated by two NHC ligands and interactions are observed between the pyridine N atoms and the metal centres, while no cuprophilic interactions were observed. Very strong absorption bands are evident in the UV–Vis spectrum at 236 and 274 nm, and an emission band is observed at 450 nm. The reported complex is a new example of a multinuclear copper NHC complex and a member of a compound class which has only rarely been reported.     

(2‐Aminopyrimidine‐κN1)aqua(pyridine‐2,6‐dicarboxylato‐κ3O2,N,O6)copper(II): X‐ray and DFT calculated structure

In the title compound, [Cu(C₇H₃N₂O₄)(C₄H₅N₂)(H₂O)], (I), pyridine‐2,6‐dicarboxylate (pydc²⁻), 2‐aminopyrimidine and aqua ligands coordinate the Cu^II centre through two N atoms, two carboxylate O atoms and one water O atom, respectively, to give a nominally distorted square‐pyramidal coordination geometry, a common arrangement for copper complexes containing the pydc²⁻ ligand. Because of the presence of Cu...X_bridged contacts (X = N or O) between adjacent molecules in the crystal structures of (I) and three analogous previously reported compounds, and the corresponding uncertainty about the effective coordination number of the Cu^II centre, density functional theory (DFT) calculations were used to elucidate the degree of covalency in these contacts. The calculated Wiberg and Mayer bond‐order indices reveal that the Cu...O contact can be considered as a coordination bond, whereas the amine group forming a Cu...N contact is not an effective participant in the coordination environment.     

Chemoselective Oxidation of Benzyl,Amino, and Propargyl Alcohols to Aldehydes and Ketones under Mild Reaction Conditions

Catalytic oxidation reactions often suffer from drawbacks such as low yields and poor selectivity. Particularly, selective oxidation of alcohols becomes more difficult when a compound contains more than one oxidizable functional group. In order to deliver a methodology that addresses these issues, herein we report an efficient, aerobic, chemoselective and simplified approach to oxidize a broad range of benzyl and propargyl alcohols containing diverse functional groups to their corresponding aldehydes and ketones in excellent yields under mild reaction conditions. Optimal yields were obtained at room temperature using 1 mmol substrate, 10 mol % copper(I) iodide, 10 mol % 4-dimethylaminopyridine (DMAP), and 1 mol % 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) in acetonitrile, under an oxygen balloon. The catalytic system can be applied even when sensitive and oxidizable groups such as alkynes, amines, and phenols are present; starting materials and products containing such groups were found to be stable under the developed conditions.     

火试金法测定铜硫矿中的金和银量的研究

本文针对铜硫矿中铜含量较高的特性,建立了适合该试样的配料比、高温熔融,金、银与铅形成合金,利用其比重悬殊与熔渣分离,将铅扣灰吹得金、银合粒,用硝酸分金,用重量法测定金量,用容量法测定银量。方法的相对标准偏差0.66%到4.78%,加标回收率96.5%到100.6%。     

Zinc Complexes of Cyclodextrin‐bearing 8‐Hydroxyquinoline Ligands: A Comparative Study

The mounting evidence supporting the role of metal ions in several diseases has turned metal‐ion chelation therapy into a promising treatment strategy. The design of efficient metal‐binding ligands requires in‐depth knowledge of molecular structure and stability constants of the complexes formed. This paper presents an extensive overview on the stability of zinc(II) and copper(II) complexes of a series of cyclodextrin‐8‐hydroxyquinoline conjugates. In order to explain the differences observed in the stability constants between the metal complexes of the 6‐functionalized and 3‐functionalized cyclodextrin isomers, conformational analysis and DFT simulations were also performed. Molecular simulations allowed us to clarify the binding mode and to explain the differences in the stability constants of the metal complexes of these derivatives.     

Unusual 4‐arsonoanilinium cationic species in the hydrochloride salt of (4‐aminophenyl)arsonic acid and formed in the reaction of the acid with copper(II) sulfate,copper(II) chloride and cadmium chloride

Structures having the unusual protonated 4‐arsonoanilinium species, namely in the hydrochloride salt, C₆H₉AsNO₃⁺·Cl⁻, (I), and the complex salts formed from the reaction of (4‐aminophenyl)arsonic acid (p‐arsanilic acid) with copper(II) sulfate, i.e. hexaaquacopper(II) bis(4‐arsonoanilinium) disulfate dihydrate, (C₆H₉AsNO₃)₂[Cu(H₂O)₆](SO₄)₂·2H₂O, (II), with copper(II) chloride, i.e. poly[bis(4‐arsonoanilinium) [tetra‐μ‐chlorido‐cuprate(II)]], {(C₆H₉AsNO₃)₂[CuCl₄]}_n , (III), and with cadmium chloride, i.e. poly[bis(4‐arsonoanilinium) [tetra‐μ‐chlorido‐cadmate(II)]], {(C₆H₉AsNO₃)₂[CdCl₄]}_n , (IV), have been determined. In (II), the two 4‐arsonoanilinium cations are accompanied by [Cu(H₂O)₆]²⁺ cations with sulfate anions. In the isotypic complex salts (III) and (IV), they act as counter‐cations to the {[CuCl₄]²⁻}_n or {[CdCl₄]²⁻}_n anionic polymer sheets, respectively. In (II), the [Cu(H₂O)₆]²⁺ ion sits on a crystallographic centre of symmetry and displays a slightly distorted octahedral coordination geometry. The asymmetric unit for (II) contains, in addition to half the [Cu(H₂O)₆]²⁺ ion, one 4‐arsonoanilinium cation, a sulfate dianion and a solvent water molecule. Extensive O—H…O and N—H…O hydrogen bonds link all the species, giving an overall three‐dimensional structure. In (III), four of the chloride ligands are related by inversion [Cu—Cl = 2.2826 (8) and 2.2990 (9) Å], with the other two sites of the tetragonally distorted octahedral CuCl₆ unit occupied by symmetry‐generated Cl‐atom donors [Cu—Cl = 2.9833 (9) Å], forming a two‐dimensional coordination polymer network substructure lying parallel to (001). In the crystal, the polymer layers are linked across [001] by a number of bridging hydrogen bonds involving N—H…Cl interactions from head‐to‐head‐linked As—O—H…O 4‐arsonoanilinium cations. A three‐dimensional network structure is formed. Cd^II compound (IV) is isotypic with Cu^II complex (III), but with the central CdCl₆ complex repeat unit having a more regular M —Cl bond‐length range [2.5232 (12)–2.6931 (10) Å] compared to that in (III). This series of compounds represents the first reported crystal structures having the protonated 4‐arsonoanilinium species.     

火试金-重量法测定阳极铜中的金和银

阳极铜是铜电解过程的重要产品,其中含有一定量的金、银等贵金属,快速准确地测定阳极铜中的贵金属含量,具有重要的现实意义。采用火试金重量法可以同时且快速地测定出样品中的金量和银量,试样与适量的熔剂经高温熔融,铅将金、银富集起来形成铅扣,灰吹得到金、银合粒,用硝酸分金,重量法测得金量;用电感耦合等离子体发射光谱(ICP-OES)法测定分金液中的杂质量和金量,合粒质量减去金量及杂质量即为银量。此方法精密度好,准确度高。金、银的加标回收率在97.6%~102%,可以很好地满足阳极铜中金、银含量的测定。     

Copper‐Catalyzed Three‐Component Annulations of Alkenes,Nitrosoarenes, and N‐Hydroxyallylamines To Form Fused Oxazinane/Isoxazolidine Heterocycles

One‐pot cascade annulations among nitrosoarenes, alkenes, and N‐hydroxyallylamines have been achieved with CuCl/O₂ catalysts, forming fused oxazinane/isoxazolidine heterocycles with excellent diastereoselectivity (d.r. >20:1). To enhance the synthetic utility, we developed a successive cleavage of the two N−O bonds of the resulting heterocycles. A mechanism involving dipolar [3+2] cycloadditions of nitrone intermediates with their tethered alkenes is postulated for formation of these heterocycles.     

捕捉环加成反应中的有机亚铜中间体构筑氮杂环化合物研究进展

铜(I)盐催化的环加成反应,如叠氮-炔[3+2]环加成(Cu AAC)、不饱和化合物与异氰基化合物的[3+2]环加成、硝酮-炔的环加成(Kinugasa反应)是构建多类氮杂环的高效合成方法,被广泛应用于有机合成的各个领域.近年来,针对几类环加成反应中产生的有机亚铜中间体的多样性转化吸引了国内外很多课题组的注意,基于对这些环加成反应中有机亚铜中间体的捕捉,多类串联及多组分反应得以发展,从而成功实现了一系列多取代杂环或稠环结构的高效构建.本综述总结了这一领域的研究进展,按照所经历的有机亚铜中间体的类型进行分类,包括:(1)Cu AAC反应中产生的三氮唑亚铜中间体;(2)炔烃与异氰化合物[3+2]环加成反应中产生的2H-吡咯基亚铜中间体;(3) Kinugasa反应中产生的烯醇亚铜中间体.期望此综述能够有助于研究者了解有机亚铜中间体捕捉策略的发展、应用现状及不足之处,进一步推动铜催化转化的发展.     

高活性铜催化剂无受体乙醇催化脱氢制乙醛研究

相较于Wacker工艺进行乙醛工业化生产,发展多相催化体系实现乙醇直接无氧催化脱氢制乙醛和副产氢气,从生产工艺和经济价值方面无疑是一条更加安全高效的路线.在此,我们发展了一种高效、稳固的Cu/SiO₂催化剂,用于乙醇的无受体催化脱氢.通过氨蒸发法制备得到高度分散的Cu颗粒,在没有任何平衡气体的纯乙醇进料条件下,显示出超强的热稳定性.活性组分Cu和载体SiO₂之间的强相互作用,使其具有优异的催化性能.通过反应条件优化,在250℃下实现了较高的乙醇转化率(>40%)和乙醛选择性(>95%),且催化剂在固定床连续反应过程中可稳定运行超过400 h.