Gold(I)‐Catalyzed Regiodivergent Rearrangements: 1,2‐ and 1,2′‐Alkyl Migration in Skipped Alkynyl Ketones

A series of 2‐alkynyl carbonyl compounds that contain a cyclopentene ring or a heterocycle can be transformed into various fused dihydrobenzofurans and tetrahydrofuro[2,3‐c]pyridines by means of a 1,2‐alkyl migration process. Both of these reactions proceed with excellent regioselectivity and stereospecificity when using a cationic gold(I) catalyst. Treatment of 4‐styrylcyclopent‐1‐enecarboxylates under different conditions affords a range of highly functionalized dihydrobenzofurans and dihydroisobenzofurans. A divergence in product selectivity, which depends on the anion of the silver salts used, was observed. Interestingly, ring‐fused tetrahydroquinolines undergo only 1,2′‐alkyl migration reaction by means of a C? C cleavage/cyclization sequence to provide tetrahydroazepine derivatives. Mechanistic studies suggest that the gold complexes catalyze 1,2‐alkyl migration reactions through a concerted reaction pathway and 1,2′‐alkyl migration reactions through a stepwise reaction pathway.     

Electronic Coupling between Two Amine Redox Sites through the 5,5′‐Positions of Metal‐Chelating 2,2′‐Bipyridines

Electron delocalization of new mixed‐valent (MV) systems with the aid of lateral metal chelation is reported. 2,2′‐Bipyridine (bpy) derivatives with one or two appended di‐p‐anisylamino groups on the 5,5′‐positions and a coordinated [Ru(bpy)₂] (bpy=2,2′‐bipyridine), [Re(CO)₃Cl], or [Ir(ppy)₂] (ppy=2‐phenylpyridine) component were prepared. The single‐crystal molecular structure of the bis‐amine ligand without metal chelation is presented. The electronic properties of these complexes were studied and compared by electrochemical and spectroscopic techniques and DFT/TDDFT calculations. Compounds with two di‐p‐anisylamino groups were oxidized by a chemical or electrochemical method and monitored by near‐infrared (NIR) absorption spectral changes. Marcus–Hush analysis of the resulting intervalence charge‐transfer transitions indicated that electron coupling of these mixed‐valent systems is enhanced by metal chelation and that the iridium complex has the largest coupling. TDDFT calculations were employed to interpret the NIR transitions of these MV systems.     

Synthesis, structure and catalytic activity of complexes [Ln(EDBP)2(DME)Na(DME)3](Ln=Er, Yb, Sm) for ring-opening polymerization of ?-caprolactone

Discrete ion-pair complexes [Ln(EDBP)₂(DME)Na(DME)₃] [Ln=Er (1), Yb (2), Sm (3)] have been synthesized by the reaction between sodium salt of 2,2′-ethylidene-bis(4,6-di-tert-butylphenol)(EDBPH₂) and Ln(BH₄)₃·3THF (Ln=Er, Yb, Sm) followed by centrifugation and recrystalization. The complexes were characterized by elemental analysis and FT-IR, and the bonding model of these compounds was confirmed by X-ray single crystal diffraction for complex 1. It was found that four O atoms in two biphenol ligands as well as two O atoms in one ethylene glycol dimethyl ether (DME) molecule connect to the center rare earth metal atom, while sodium exists as counterpart cation to balance the charge. Complexes 1–3 can all be used as single component initiators for the ring-opening polymerization of ɛ-caprolactone.     

Highly luminescent ZnO and CdS nanostructures prepared by ionic liquid precursors

The ionic liquids containing Cd and Zn, which served as the metal-chalcogenides precursors, were synthesized and reacted with Na₂S to synthesize the ionic-liquid-capped semiconductors. The products were detected by XRD and TEM. The results demonstrated that the CdS was composed of 5–6 nm monodispersed nanocrystals. At the same time, the ZnO composed of 1 μm hexagonal-disk nanostructure was prepared under the same experimental condition. The difference of the morphology and structures between Zn and Cd systems was discussed by thermodynamics and crystallography. The fluorescence of as-prepared ZnO and CdS showed the excellent photoluminescence.     

Hydrogen binding property of Co- and Ni-based organometallic compounds

The binding property of hydrogen on organometallic compounds consisting of Co, and Ni transition metal atoms bound to C _m H _m rings (m = 4, 5) is studied through density functional theory calculation. CoC _m H _m and NiC _m H _m complexes can store up to 3.49 wt% hydrogen with an average binding energy of about 1.3 eV. The adsorption characteristics of hydrogen to organometallic compounds are investigated by analyzing vibrational spectra of CoC₄H₄(H₂) _n and NiC₄H₄(H₂) _n (n = 0, 1, 2). The kinetic stability of these hydrogen-covered organometallic complexes is assured by analyzing the energy gap between the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals. It is also discussed the application of 18-electron rule in predicting maximum number of hydrogen molecules that could be adsorbed by these organometallic compounds.     

Adsorption behavior of VII group elements on tertiary pyridine resin in hydrochloric acid solution

We investigated the adsorption behaviors of technetium and rhenium on tertiary pyridine resin in hydrochloric acid solution. Technetium has a little larger distribution coefficient in higher concentration of hydrochloric acid region than rhenium. However, the tendency of adsorption behavior of technetium and rhenium is similar. We concluded that the rhenium can be used as the substitute for technetium. Adsorption behaviors of platinum group elements were also investigated. The separation of technetium from platinum group elements is discussed.     

8-羟基喹啉对碘离子修饰的B-Z化学振荡体系的扰动

研究了用碘化钾溶液对B-Z化学振荡反应的修饰,以8-羟基喹啉为被检测化合物考察了修饰前后B-Z化学振荡体系对环境的敏感性变化.结果表明,修饰后的B-Z化学振荡体系对8-羟基喹啉的灵敏度大为提高,在2.50×10~(-9)～3.16×10~(-11)mol/L范围内,振荡体系的周期变化值与8-羟基喹啉浓度的负对数呈现良好的线性关系,相关系数为0.9980.     

钴配合物[Co_2(H_2O)_8(C_(10)H_8N_2)_2]·(HO_3PCH_2CH_2SO_3)(SO_4)(H_2O)_4的合成与晶体结构研究

用硫酸钴、4,4'-联吡啶和2-磺酸基乙基膦酸合成了一个新颖的钴化合物:[Co_2(H_2O)_8(C_(10)H_8N_2)_2]·(HO_3PCH_2CH_2SO_3)(SO_4)(H_2O)_4,并对其进行了红外.元素分析、热重测试,通过单晶衍射仪测定了其晶体结构.结果表明,配合物属单斜晶系C2/c空间群,分子式为C_(22)H_(45)Co_2N_4O_(22)PS_2,分子量为930.57,晶胞参数为a=19.8456(18),b=11.2957(10),c=34.719(3)(A),β=106.095(3)°,晶胞体积为7477.9(12)(A)~3,Z=8,Dc=1.653 g/cm~3,F(000)=3856,μ=1.131 mm~(-1),最终残差因子R_1=0.0726,wR_2= 0.1719(相对于5612个I>2σ(I)的可观测衍射点).在这个化合物中,二齿配体4,4'-联吡啶把Co(II)桥连成[Co(4,4'-bipy)]~(2+)链.化合物中的[Co(4,4'-bipy)]~(2+)链有三个不同的朝向.2-磺酸基乙基膦酸没有参与配位而是做为一个有机模板剂填充在[Co(4,4'-bipy)]~(2+)链形成的空隙中.     

Efficient synthesis of 5,6-dihydrothieno[3′,2′:4,5]-thieno[2,3-d]pyrimidin-4(3H)-ones via an iminophosphorane

5,6-Dihydrothieno[3′,2′:4,5]thieno[2,3-d]pyrimidin-4(3H)-ones 6 were synthesized in yields of 71-87%by a consecutive method,which includes aza-Wittig reaction of iminophosphorane 3 with aromatic isocynate to give carbodiimide 4 and subsequent reaction of 4 with various amines,phenols or alcohols in the presence of catalytic amount of sodium ethoxide or solid potassium carbonate.