Synthesis and structural characterization of [RuCl2(CO)2(TePh2)2]·1/2C6H6

The reaction of Ph₂Te with [RuCl₂(CO)₃]₂ affords a monomeric ruthenium complex [RuCl₂(CO)₂(TePh₂)₂]. The X-ray structure shows the formation of the trans(Ph₂Te), cis(Cl), cis(CO) isomer. The ¹³C NMR and ¹²⁵Te NMR spectra of the complex are reported.     

Reactive consolidation and high-temperature strength of HfB2–SiB6

During the spark plasma sintering at 1900 °C, SiB₆ decomposes into cubic silicon carbide and boron carbide, owing to the reducing environment of the furnace. For the HfB₂-SiB₆ ceramic improvement in hardness (24.5 ± 0.7 GPa) was attributed to the formation of the B₁₂(C,Si,B)₃. Fracture toughness by indentation (6.8 ± 2.4 MPa·m^1/2), single-edge notched bend specimens (4.6 ± 0.4 MPa·m^1/2) and room-temperature strength (513 ± 21 MPa) of the HfB₂–SiB₆ composite produced by spark plasma sintering was higher or on the same level as the HfB₂–SiC ceramics. The high-temperature flexural strength tests suggested that the strength would decrease monotonically with an increase in temperature. At or below 1600 °C, only a linear stress-strain response was observed, and resulted into a mean strength of ~320 MPa. During the tests at 1800 °C, we observed a nonlinear deformation indicating ongoing plastic deformation which led to a strength decrease down to 230 ± 30 MPa.     

Synthesis and Thermotropic Studies of Two Novel Series of Kinked Liquid Crystals: 2-(4′-Alkoxybiphen-4-yl)-6-methylquinolines and 2-(6-Alkoxynaphthalen-2-yl)-6-methylquinolines

Two novel homologous series of kinked (Z-shaped) liquid crystalline compounds were synthesized using a short two-step reaction. Yields of 30%–40% and 51%–57% were obtained for 2-(4′-alkoxybiphen-4-yl)-6-methylquinolines (nO-PPQMe, n = 3–8) and 2-(6-alkoxynaphthalen-2-yl)-6-methylquinolines (iO-NpQMe, i = 3–7), respectively. Spectral analyses agreed with the expected structures. The thermotropic behaviors of these compounds were investigated using polarized optical microscopy and differential scanning calorimetry. An enantiotropic nematic phase appeared to be the main mesophase in these two series of kinked liquid crystalline compounds, and an additional enantiotropic smectic C phase appeared when n = 8.     

2，2，6，6－四氯环己酮的研制

阐述了以环己酮为原料液相法制备２，２，６．－四氯环己酮的方法，就催化剂的种类、用量、加料速度、水的存在等诸多因素对反应的影响进行了讨论。     

Cyclohexadiene-linked clusters: synthesis and molecular structure of [{Os4(CO)8(MeCCMe)(η6-C6H6)}2(μ2-η2:η2-C6H8-1,3)]

The reaction of [Os₄(CO)₉(RCCR)(η⁶-C₆H₆)] (R=Me, Ph) with Me₃NO in the presence of 1,3-cyclohexadiene or 1,4-cyclohexadiene yields the clusters [{Os₄(CO)₈(RCCR)(η⁶-C₆H₆)}₂(μ₂-η²:η²-C₆H₈-1,3)] and [{Os₄(CO)₈(RCCR)(η⁶-C₆H₆)}₂(μ₂-η²:η²-C₆H₈-1,4)], respectively. The molecular structure of [{Os₄(CO)₈(MeCCMe)(η⁶-C₆H₆)}₂(μ₂-η²:η²-C₆H₈-1,3)] has been determined by single crystal X-ray diffraction, and represents the first example of two osmium cluster fragments linked by 1,3-cyclohexadiene through a μ₂-η²:η²-bridge.     

Spark plasma sintering and high-temperature strength of B6O–TaB2 ceramics

Tantalum diboride – boron suboxide ceramic composites were densified by spark plasma sintering at 1900 °C. Strength and fracture toughness of these bulk composites at room temperature were 490 MPa and 4 MPa m^1/2, respectively. Flexural strength of B₆O–TaB₂ ceramics increased up to 800 °C and remained unchanged up to 1600 °C. At 1800 °C a rapid decrease in strength down to 300 MPa was observed and was accompanied by change in fracture mechanisms suggestive of decomposition of boron suboxide grains. Fracture toughness of B₆O–TaB₂ composites showed a minimum at 800 °C, suggestive a relaxation of thermal stresses generated from the mismatch in coefficients of thermal expansion.Flexural strength at elevated temperatures for bulk TaB₂ reference sample was also investigated.Results suggest that formation of composite provides additional strengthening/toughening as in all cases flexural strength and fracture toughness of the B₆O–TaB₂ ceramic composite was higher than that reported for B₆O monoliths.     

K2SiF6沉淀容量法测定H2SiF6和Na2SiO3

Ｋ_２ＳｉＦ_６沉淀容量法测定Ｈ_２ＳｉＦ_６和Ｎａ_２ＳｉＯ_３朱光华（江西第二机床厂，３４３４００）１前言装饰性滚镀铬、尺寸复合镀铬都要用Ｈ２ＳＯ４和Ｈ２ＳｉＦ６作催化剂。由于含有Ｈ２ＳｉＦ６的镀铬溶液可采用较高的电流密度，电流效率较高１８～２５％，光...     

A new imine ligand avoiding imine–enamine rearrangement and cyclometallation: Synthesis and coordination of Me3C6H2CH2NCHtBu

The new imine ligand (E)-2,4,6-Me₃C₆H₂CH₂NCH^tBu (1) has been prepared from 2,4,6-trimethylbenzylamine and trimethylacetaldehyde. In this imine, the ortho-positions of the benzyl group are blocked by methyl groups, and there are no β-hydrogen atoms susceptible for imine–enamine rearrangement. Thus, reaction with [PdCl₂(C₆H₅CN)₂] leads to the complex trans-[PdCl₂(2,4,6-Me₃C₆H₂CH₂NCH^tBu)₂] (2) that cannot undergo cyclopalladation. The single-crystal X-ray structure analysis of trans-[PdCl₂(2,4,6-Me₃C₆H₂CH₂NCH^tBu)₂] (2) confirms the trans-coordination of the imine ligands in this square-planar complex.     

H_2PtCl_6·6H_2O热分解动力学及其产物性能

本文深入探究了氯铂酸六水合物的热分解过程及其产物,以更好地掌握、控制该化合物,并深入认识其反应动力学。除此之外,还探究了其部分分解产物的电催化水分解产氢性能,并取得重要的进展。     

Reactions of [(η6-Me6C6)Ru(Ph2PCHCH2)Cl2] with 1-ethynylcycloalkanols leading to methoxy-alkenyl carbenes via vinylvinylidene and/or allenylidene intermediates

Methoxy-alkenyl carbenes 1 and 2 have been synthesized by treating a dichloro-methane/methanol solution of the [(η⁶-Me₆C₆)Ru(Ph₂PCHCH₂)Cl₂] complex with an excess of 1-ethynyl-1-cyclohexanol and 1-ethynyl-1-cyclopentanol in the presence of NaPF₆. The compounds were characterized by IR and ¹H, ¹³C{¹H}, ³¹P{¹H} NMR spectroscopies and by elemental analyses. The crystal structure of 2 has also been determined by X-ray crystallography.     

2，6──二氯苯甲醛

２，６──二氯苯甲醛该产品是染料、农药、医药工业的重要中间体。其合成路线是以硝基苯为原料经氧化等六步反应而得，其总收率达到４５％以上，纯度达到９５％以上，熔点６７一６９度。该工艺在精馏及高压过程，反应条件缓和具有设备简单、收率高，原料易得，造价低等特...     

Phase formation,dielectric and ferroelectric properties of CaxBa1−xNb2O6 ceramics

Lead-free Ca_xBa_1?xNb₂O₆ (CBN, 0.20≤x≤0.35) ceramics were prepared by the conventional solid state method. Effects of Ca content on the phase formation, microstructure, dielectric and ferroelectric properties for the prepared CBN ceramics were systematically studied. XRD results showed that pure CBN phase with tungsten bronze structure could be obtained from the solid solutions of BaNb₂O₆ and CaNb₂O₆ in all ceramics. Higher Ca contents favored the occurrence of grains with anisometric morphology, but no abnormal grain growth could be found in all compositions. With the increase of x, Curie temperature T_c shifted downward, whereas the maximum dielectric constant ε_m increased initially and then decreased. All the ceramics showed an intermediate relaxor-like behavior between normal and ideal relaxor ferroelectrics according to the modified Curie–Weiss law. Normal ferroelectric hysteresis loops were observed in all compositions. Both remnant polarization P_r and coercive field E_c increased initially and then decreased with the increase of x. The ceramics with homogeneous microstructure, high density and better properties were obtained at x=0.28 with ε_m=2998, T_c=234 °C, P_r=3.98 μC cm^?2 and E_c=14.03 kV cm^?1.     

Thermo-mechanical behaviour of Polyamide 6 chain extended with 1,1′-Carbonyl-Bis-Caprolactam and 1,3-Phenylene-Bis-2-Oxazoline

A commercial Polyamide 6 (PA6) was melt compounded by using a twin screw extruder with a combination of 1,1′-Carbonyl-Bis-Caprolactam (CBC) and 1,3-Phenylene-Bis-2-Oxazoline (PBO), in order to evaluate their effect on the chain extension behaviour of the resulting materials. An increase of the viscosity values with the chain-extender amount was evidenced by rheological tests on the compounded pellets and relative viscosity measurements on solubilized samples, while the opposite trend was determined increasing the residence time at elevated temperatures. The increase of the molecular weight due to the presence of CBC and PBO was confirmed by the reduction of carboxylic and aminic functionalities evidenced in end group analysis. DSC tests showed a reduction of the melting temperature and of the crystallinity degree proportionally to the chain extender amount. Elastic modulus of the chain-extended materials was similar to that of the corresponding PA6 grades at different molecular weight, while crystallinity drop due to chain extension determined an increase of the strain at break values.     

Structure and upconversion analyses of Er3+-doped Ba6Ti2Nb8O30–Sr6Ti2Nb8O30 solid solutions

Er³⁺-doped filled tungsten bronze Ba₆Ti₂Nb₈O₃₀–Sr₆Ti₂Nb₈O₃₀ solid solutions with different Ba₆Ti₂Nb₈O₃₀/Sr₆Ti₂Nb₈O₃₀ ratios (SBTNx) have been prepared by a high temperature solid-state reaction. The crystal structure has been investigated simultaneously by the Rietveld structural refinement and upconversion photoluminescence (UC-PL) spectra. It is found that the crystal structure of SBTNx changes from TE-FTB symmetry (0≤x≤3, space group P4bm) to OR-FTB symmetry (3.5≤x≤5.91, space group Pba2) with x increasing. More interestingly, the structure transition of SBTNx system is also revealed by the UC-PL spectra which indicate the intimate correlation between the UC-PL spectra and the structure transition. Furthermore, the underlying origin concerning the variation of UC-PL spectra has been studied from crystal structure aspect which suggests UC-PL spectra can be explored as a structure probe for present filled tungsten bronze solid solutions.     

Preparation and properties of (Ba0·6Sr0·4)Bi2Ta2O9 ceramic

(Ba_0·6Sr_0·4)Bi₂Ta₂O₉ (BSBT) ceramic materials with plate-like grains were prepared by the conventional mixed oxide method. The microstructures of BSBT ceramic sintered at different temperatures were studied. The variations of the saturation polarization (P_s), remanent polarization (P_r) and coercive field (E_c) with applied electric field and temperature were studied by hysteresis (D–E loop) measurements. The permittivities, piezoelectric and pyroelectric coefficients of BSBT ceramic poled at various electric fields and temperatures were measured.     

Unraveling the cooperative effects of acid sites and kinetics for pyrolysis of CHF3 to C2F4 and C3F6 on SO42−/ZrO2-SiO2

The treatment or upgrading of waste trifluoromethane (CHF₃, R23), which has a significant greenhouse effect, is of great importance in industry. Herein, series of SO₄²⁻/ZrO₂-SiO₂ catalysts with different Brønsted and Lewis acid site densities and ratios were prepared for pyrolysis of R23 to tetrafluoroethylene (C₂F₄, TFE) and hexafluoropropylene (C₃F₆, HFP). The effects of impregnation concentration of (NH₄)₂SO₄ on specific surface area, crystal phase, and Brønsted and Lewis acid site densities and ratios were respectively demonstrated. The Brønsted and Lewis acid sites were observed to have cooperative effects on R23 transformation and up to 94.6% selectivity of (TFE + HFP) could be achieved at 750°C. The kinetic studies revealed the decomposition of R23 into CF₂ carbene and HF was the rate-determining step, and a deactivation behavior was found due to the site coverage and pore blockage by the oligomers of TFE and HFP.     

Bi_2MoO_6和Bi_2WO_6材料的合成和光催化性能研究

本课题利用水热法一步合成了钼酸铋(Bi_2Mo O_6)和钨酸铋(Bi_2WO_6)两种半导体光催化剂。借助红外光谱(IR)、X射线衍射光谱(XRD)和扫描电子显微镜(SEM)对样品的物相结构、表面结构进行了表征。以罗丹明B为目标降解物,借助太阳光为光源,研究了两种催化剂材料在不同光催化时间下对有机染料的光催化性能影响。结果表明,纳米片结构的Bi_2WO_6对有机染料的降解综合性能要优越于纳米线团簇结构的Bi_2Mo O_6材料,尤其是Bi_2WO_6催化剂对罗丹明B染料的降解度在光催化5小时后可以达到80%。