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1.
The addition of BCl3 to the carbene‐transfer reagent NHC→SiCl4 (NHC=1,3‐dimethylimidazolidin‐2‐ylidene) gave the tetra‐ and pentacoordinate trichlorosilicon(IV) cations [(NHC)SiCl3]+ and [(NHC)2SiCl3]+ with tetrachloroborate as counterion. This is in contrast to previous reactions, in which NHC→SiCl4 served as a transfer reagent for the NHC ligand. The addition of BF3 ? OEt2, on the other hand, gave NHC→BF3 as the product of NHC transfer. In addition, the highly Lewis acidic bis(pentafluoroethyl)silane (C2F5)2SiCl2 was treated with NHC→SiCl4. In acetonitrile, the cationic silicon(IV) complexes [(NHC)SiCl3]+ and [(NHC)2SiCl3]+ were detected with [(C2F5)SiCl3]? as counterion. A similar result was already reported for the reaction of NHC→SiCl4 with (C2F5)2SiH2, which gave [(NHC)2SiCl2H][(C2F5)SiCl3]. If the reaction medium was changed to dichloromethane, the products of carbene transfer, NHC→Si(C2F5)2Cl2 and NHC→Si(C2F5)2ClH, respectively, were obtained instead. The formation of the latter species is a result of chloride/hydride metathesis. These compounds may serve as valuable precursors for electron‐poor silylenes. Furthermore, the reactivity of NHC→SiCl4 towards phosphines is discussed. The carbene complex NHC→PCl3 shows similar reactivity to NHC→SiCl4, and may even serve as a carbene‐transfer reagent as well.  相似文献   

2.
Beside several other applications, metal azides can be used for the synthesis of nitridophosphates and binary nitrides. Herein we present a novel synthetic access to azides: Several metals, such as main‐group, transition metals, and rare‐earth metals, react with silver azide in liquid ammonia as a solvent giving the corresponding metal azides. In this work Mn(N3)2, Sn(N3)2, and Eu(N3)2, as well as their ammonia complexes were synthesized for the first time through low‐temperature methods. Also a simpler access to Zn(N3)2 was possible. At room temperature and the respective vapor pressure of NH3, it became possible to grow single crystals of the dinuclear holmium azide [Ho2(μ‐NH2)3(NH3)10](N3)3?1.25 NH3. We are confident that this new route could lead to novel metal azides as well as nitrides of the main‐group, the transition, and the rare‐earth metals upon careful decomposition.  相似文献   

3.
The Chloride Nitrate PrCl2(NO3) · 5 H2O with Cationic and Anionic Complexes according to [PrCl2(H2O)6][PrCl2(NO3)2(H2O)4] Green single crystals of PrCl2(NO3) · 5 H2O have been obtained from an aqueous solution of PrCl3 and Pr(NO3)3. The crystal structure [monoclinic, P2/c, Z = 4, a = 1228.8(3), b = 648.4(1), c = 1266.0(4) pm, β = 91.91(3)°] contains cationic and anionic Pr3+ complexes according to [PrCl2(H2O)6][PrCl2(NO3)2(H2O)4]. Both nitrate groups of the anionic complex act as bidentate chelating ligands. Hydrogen bonds are observed with water molecules as donors and chlorine as well as oxygen atoms as acceptors.  相似文献   

4.
Metal promoted zirconia-based oxide sorbents, such as Pt–ZrO2/Al2O3 for NO x have been investigated. To clarify the role of the catalyst component, sorption of NO and NO2 was compared using the samples with and without Pt. The catalytic oxidation of NO to NO2 and successively to nitrate ions is an important role for the Pt catalyst. The experimental results indicate that a high-temperature calcination is essential to remove residual Cl from Pt–ZrO2–Al2O3 prepared from H2PtCl6 in order to provide more active NO x sorption sites. Of M–ZrO2–Al2O3 samples investigated, ruthenium as well as Pt demonstrated relatively good performance as a catalyst component in the sorbent. The FT-IR spectra after sorption of NO and NO2 demonstrated a strong band attributed to stored nitrate ions. The Pt catalyst was more resistant to sulfur poisoning than a base metal catalyst. However, the NO x sorptive capacities of the Pt–ZrO2/Al2O3 sorbents were expected to be deteriorated in dilute SO2 as far as observed from FT-IR spectra.  相似文献   

5.
The selective formation of dialkyl formamides through photochemical CO2 reduction was developed as a means of utilizing CO2 as a C1 building block. Photochemical CO2 reduction catalyzed by a [Ru(bpy)2(CO)2]2+ (bpy: 2,2′‐bipyridyl)/[Ru(bpy)3]2+/Me2NH/Me2NH2+ system in CH3CN selectively produced dimethylformamide. In this process a ruthenium carbamoyl complex ([Ru(bpy)2(CO)(CONMe2)]+) formed by the nucleophilic attack of Me2NH on [Ru(bpy)2(CO)2]2+ worked as the precursor to DMF. Thus Me2NH acted as both the sacrificial electron donor and the substrate, while Me2NH2+ functioned as the proton source. Similar photochemical CO2 reductions using R2NH and R2NH2+ (R=Et, nPr, or nBu) also afforded the corresponding dialkyl formamides (R2NCHO) together with HCOOH as a by‐product. The main product from the CO2 reduction transitioned from R2NCHO to HCOOH with increases in the alkyl chain length of the R2NH. The selectivity between R2NCHO and HCOOH was found to depend on the rate of [Ru(bpy)2(CO)(CONR2)]+ formation.  相似文献   

6.
Salicylaldehyde thiosemicarbazone (H2saltsc) reacts with [M(PPh3)3X2] (M = Ru, Os; X = Cl, Br) to afford complexes of type [M(PPh3)2(Hsaltsc)2], in which the salicylaldehyde thiosemicarbazone ligand is coordinated to the metal as a bidentate N,S-donor forming a four-membered chelate ring. Reaction of benzaldehyde thiosemicarbazones (Hbztsc-R) with [M(PPh3)3X2] also affords complexes of similar type, viz. [M(PPh3)2(bztsc-R)2], in which the benzaldehyde thiosemicarbazones have also been found to coordinate the metal as a bidentate N,S-donor forming a four-membered chelate ring as before. Reaction of the Hbztsc-R ligands has also been carried out with [M(bpy)2X2] (M = Ru, Os; X = Cl, Br), which has afforded complexes of type [M(bpy)2(bztsc-R)]+, which have been isolated as perchlorate salts. Coordination mode of bztsc-R has been found to be the same as before. Structure of the Hbztsc-OMe ligand has been determined and some molecular modelling studies have been carried out determine the reason for the observed mode of coordination. Reaction of acetone thiosemicarbazone (Hactsc) has then been carried out with [M(bpy)2X2] to afford the [M(bpy)2(actsc)]ClO4 complexes, in which the actsc ligand coordinates the metal as a bidentate N,S-donorformingafive-membered chelate ring. Reaction of H2saltsc has been carried out with [Ru(bpy)2Cl2] to prepare the [Ru(bpy)2(Hsaltsc)]ClO4 complex, which has then been reacted with one equivalent of nickel perchlorate to afford an octanuclear complex of type [Ru(bpy)2(saltsc-H)4Ni4](ClO4)4.  相似文献   

7.
Li-rich layered Li1.2Ni0.2Mn0.6O2 has been surface modified by nickel–manganese composite oxide (Ni0.5Mn1.5O x ) to serve as a novel cathode material with novel layered spinel structure for lithium-ion battery. The as-prepared Li1.2Ni0.2Mn0.6O2 before and after surface modification by Ni0.5Mn1.5O x as well as simply blended Li1.2Ni0.2Mn0.6O2 with spinel LiNi0.5Mn1.5O4, have been characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electronic microscopy, and differential scanning calorimetry. Electrochemical studies indicate that the Ni0.5Mn1.5O x surface modified Li1.2Ni0.2Mn0.6O2 with peculiar layered spinel character dramatically represented increased discharge capacity, improved cycling stability as well as excellent rate capability at high-voltage even up to 5.0 V.  相似文献   

8.
The effects of three corundum structure oxides, α-Al2O3, α-Cr2O3, and α-Fe2O3, on the thermal decomposition of sodium and potassium peroxodisulfates (persulfates) under non-isothermal static air conditions and using various oxide/persulfate molar ratios, have been thermoanalytically investigated. Compounds such as Na3Al(SO4)3, K3Al(SO4)3, Cr2(SO4)3, K3Cr(SO43, and Na3Fe(SO4)3 are identified by X-ray diffractometry and conventional chemical analysis. The molar ratios as well as temperatures of the stoichiometric formation for these compounds have been established. At higher temperatures, α-Al2O3 acts as a promoter catalyst for the decomposition of pyrosulfate to sulfate, whereas α-Cr2O3 behaves as a retarder for the decomposition of persulfate. A eutectic mixture is formed between K3Al(SO4) and K2SO4 at 675°C. Also, K3Fe(SO4)3 is identified as two crystalline phases.  相似文献   

9.
The enhanced reactivity of [WF5]+ over WF6 has been exploited to access a neutral derivative of elusive WF5. The reaction of WF6(NC5H5)2 with [(CH3)3Si(NC5H5)][O3SCF3] in CH2Cl2 results in quantitative formation of trigonal-dodecahedral [WF5(NC5H5)3]+, which has been characterised as its [O3SCF3] salt by Raman spectroscopy in the solid state and variable-temperature NMR spectroscopy in solution. The salt is susceptible to slow decomposition in solution at ambient temperature via dissociation of a pyridyl ligand, and the resultant [WF5(NC5H5)2]+ is reduced to WF5(NC5H5)2 in the presence of excess C5H5N, as determined by 19F NMR spectroscopy. Pentagonal-bipyramidal WF5(NC5H5)2 was isolated and characterised by X-ray crystallography and Raman spectroscopy in the solid state, representing the first unambiguously characterised WF5 adduct, as well as the first heptacoordinate adduct of a transition-metal pentafluoride. DFT-B3LYP methods have been used to investigate the reduction of [WF5(NC5H5)2]+ to WF5(NC5H5)2, supporting a two-electron reduction of WVI to WIV by nucleophilic attack and diprotonation of a pyridyl ligand in the presence of free C5H5N, followed by comproportionation to WV.  相似文献   

10.
In this work, samples consisting of BiVO4 with exposed (040) facets coupled with Bi2S3 (Bi2S3/BiVO4) were prepared through a one-pot hydrothermal method, using ethylenediaminetetraacetic acid as directing agent and L-cysteine as sulfur source and soft template. X-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy measurements indicated that the Bi2S3 content had a significant influence on the growth of (040) and (121) facets as well as on the morphology of the Bi2S3/BiVO4 samples. When the Bi2S3 content reached 1 mmol, the Bi2S3/BiVO4 samples exhibited a peony-like morphology. The results of transient photocurrent tests and electrochemical impedance spectroscopy measurements confirmed that a more effective charge separation and a faster interfacial charge transfer occurred in Bi2S3/BiVO4 than BiVO4. The enhanced photocatalytic activity of the Bi2S3/BiVO4 samples could be attributed to the improved absorption capability in the visible light region and the enhanced electron-hole pair separation efficiency due to the formation of the Bi2S3/BiVO4 heterostructure. In addition, the Bi2S3/BiVO4 samples showed relative stability and reusability. The simple method presented in this work could be used to fabricate composite photocatalysts with high activity for different applications, such as photocatalytic degradation of organic pollutants, photocatalytic splitting of water, and photocatalytic reduction of carbon dioxide.  相似文献   

11.
The recently proposed systems of various anions (A) confined inside C60 , A @ C60 , which in turn behave as large and stable anions, (A @ C60) , can find potential applications in various fields. On the other hand, it has earlier been shown that from the dihalogens (X2 ) encapsulated C60 , X2 @ C60 , only F2 @ C60 can be introduced as a system in which the cage acts as a cation C60+ and interacts with an endohedral anion, F2 , forming the F2 @ C60+ as a single-molecule crystal compound. In this work, two density functional theory energy decomposition analysis (EDA) schemes, where in one of them the noninteracting kinetic, electrostatic, and exchange-correlation energies come into play while another scheme, called as EDA-SBL, includes the steric, electrostatic, and quantum effects as essential ingredients (S. Liu, J. Chem. Phys. 2007 , 126, 244103), are utilized to find out what energetic components govern the unique characteristics of the (A @ C60) and X2 @ C60 confinements. It is shown that the noninteracting kinetic energy and steric energies have important contributions to the total interaction energies for the considered systems. However, there are other confinements for which the electrostatic and exchange-correlation contributions play also imperative roles. Furthermore, we find reasonable correlations between interaction energies and their components as well as the energetic components themselves, leading to an alternative EDA scheme including the noninteracting kinetic, steric, and electrostatic energies for investigations on other endohedral fullerenes. Extending our analyses to large size confinements, Cl @ Cn with n up to 90 as illustrative examples, the quantitative cooperativity concept is also explored, where the positive and negative cooperativity profiles unveil a specific size of the anionic confinements to form the most stable large anion.  相似文献   

12.
Metal promoted zirconia-based oxide sorbents, such as Pt–ZrO2/Al2O3 for NO x have been investigated. To clarify the role of the catalyst component, sorption of NO and NO2 was compared using the samples with and without Pt. The catalytic oxidation of NO to NO2 and successively to nitrate ions is an important role for the Pt catalyst. The experimental results indicate that a high-temperature calcination is essential to remove residual Cl from Pt–ZrO2–Al2O3 prepared from H2PtCl6 in order to provide more active NO x sorption sites. Of M–ZrO2–Al2O3 samples investigated, ruthenium as well as Pt demonstrated relatively good performance as a catalyst component in the sorbent. The FT-IR spectra after sorption of NO and NO2 demonstrated a strong band attributed to stored nitrate ions. The Pt catalyst was more resistant to sulfur poisoning than a base metal catalyst. However, the NO x sorptive capacities of the Pt–ZrO2/Al2O3 sorbents were expected to be deteriorated in dilute SO2 as far as observed from FT-IR spectra.  相似文献   

13.
Two synthetic routes to 14C-labelled trimethyllead chloride ((CH3)3PbCl) from 14C-methyl iodide (CH3I) were investigated. Alkylation of (CH3)3PbCl with labelled methylmagnesium halide, on a microscale, was less efficient for the synthesis of tetramethyllead ((CH3)4Pb) than was an electrochemical reduction of labelled CH3I at a sacrificial lead cathode. In the Grignard approach, unlabelled decyl bromide served as an initiator for the reaction of 14C-CH3l with excess Mg and as a carrier during the subsequent alkylation of (CH3)3PbCl. In the electrochemical approach a two-compartment cell, using dimethylformamide as solvent and sodium perchlorate as supporting electrolyte, offered several advantages over a single compartment reactor. The labelled (CH3)4Pb from both reactions was isolated by extraction, converted to (CH3)3PbCl by controlled oxidation with HCl and purified by thin layer chromatography.  相似文献   

14.
Reaction of donor-acceptor cyclopropanes with 1,3-diphenylisobenzofuran in the presence of lanthanide triflates, as well as CuOTf, Sn(OTf)2, SnCl2, ZnCl2, GaCl3, and MgI2, proceeds as a formal [3+4]-cycloaddition leading to a newly formed seven-membered ring. This reaction was found to be typical of cyclopropane-1,1-diesters and dinitriles, as well as 1-nitrocyclo-propanecarboxylates containing aromatic, heteroaromatic, and vinylic substituents at the C(2) atom of the small ring. When Me3SiOTf, TiCl4, SnCl4, or BF3·OEt2 were used as initiators, unusual cyclic hemiacetals were formed via the conjugate 1,4-addition of a cyclopropane and a nucleophile to the diene moiety.  相似文献   

15.
The indirect electro-epoxidation of ethylene (C2H4), produced from CO2 electroreduction (CO2R), holds immense promise for CO2 upcycling to valuable ethylene oxide (EO). However, this process currently has a mediocre Faradaic efficiency (FE) due to sluggish formation and rapid dissociation of active species, as well as reductive deactivation of Cu-based electrocatalysts during the conversion of C2H4 to EO and CO2 to C2H4, respectively. Herein, we report a bromine-induced dual-enhancement strategy designed to concurrently promote both C2H4-to-EO and CO2-to-C2H4 conversions, thereby improving EO generation, using single-atom Pt on N-doped CNTs (Pt1/NCNT) and Br-bearing porous Cu2O as anode and cathode electrocatalysts, respectively. Physicochemical characterizations including synchrotron X-ray absorption, operando infrared spectroscopy, and quasi in situ Raman spectroscopy/electron paramagnetic resonance with theoretical calculations reveal that the favorable Br2/HBrO generation over Pt1/NCNT with optimal intermediate binding facilitates C2H4-to-EO conversion with a high FE of 92.2 %, and concomitantly, the Br with strong nucleophilicity protects active Cu+ species in Cu2O effectively for improved CO2-to-C2H4 conversion with a FE of 66.9 % at 800 mA cm−2, superior to those in the traditional chloride-mediated case. Consequently, a single-pass FE as high as 41.1 % for CO2-to-EO conversion can be achieved in a tandem system.  相似文献   

16.
Polyaniline coated silica/maghemite nanoparticles (PANI/SiO2/γ-Fe2O3 composites) were synthesized by the combination of a sol-gel process and an in-situ polymerization method, in which ferrous and ferric salts as well as tetraethyl orthosilica (TEOS) acted as the precursor for γ-Fe2O3 and silica, respectively. As a result, the SiO2/γ-Fe2O3 particle showed a core-shell structure, with γ-Fe2O3 as the magnetic core and silica as the shell of the particle. The shell thickness can be controlled by changing the TEOS concentration. The PANI/SiO2/γ-Fe2O3 composites revealed a multilayer core-shell structure, where PANI is the outer shell of the composite. The doping level and the conductivity of PANI/SiO2/γ-Fe2O3 composites decreased with increasing the TEOS content due to the presence of the less coated PANI on the SiO2/γ-Fe2O3 core at higher TEOS content. For a SQUID analysis at room temperature, all γ-Fe2O3 containing composites showed a typical superparamagnetic behavior. The saturation magnetization of SiO2/γ-Fe2O3 nanoparticles decreased with increasing the TEOS content due to the increase in silica shell thickness, while the saturation magnetization of PANI/SiO2/γ-Fe2O3 composites also decreased with increasing the TEOS content, which is attributed to the lower conductivity of PANI in the composites at higher TEOS content.  相似文献   

17.
NiO, Li0.68Ni1.32O2 and Li0.68Ni1.32O2/Ag composite as anodes for Li-ion batteries are reported. Li0.68Ni1.32O2 decomposed to Ni and Li2O when discharged to 0.02 V, according to XRD analysis, which was similar to NiO. Increased initial coulombic efficiency was obtained for the Li0.68Ni1.32O2 electrode (73%), higher than that of NiO (64.9%), but its cycling performance became worse because poorer conductive Li2O formed when the first discharge process was finished. However, the Li0.68Ni1.32O2/Ag electrode exhibited better cycling performance than NiO and Li0.68Ni1.32O2, because the Ag nanoparticles in the composite improved the conductivity of the electrode. The initial coulombic efficiency for Li0.68Ni1.32O2/Ag is still as high as 72%, nearly the same as that of Li0.68Ni1.32O2.  相似文献   

18.
石杰  成伟唯  郑磊  许岩 《无机化学学报》2017,33(11):2083-2094
水热条件下合成了具有超大孔道和层状结构的有机模板稀土硫酸盐。超大孔道的稀土硫酸盐(1)的分子式为[(CH32NH2]9[Pr5(SO412]·2H2O,它展现出有趣的交叉二十元环孔道结构。层状的稀土硫酸盐的分子式为[H3O]3[(CH32NH2]3[Ln2(SO46](Ln=Pr,2;Nd,3),它可以被看作是由双链和八元环结合而成。这3种化合物的合成揭示了大的有机胺(三聚氰胺)可能用作为第二结构导向剂,阻止形成高维数的无机骨架,从而诱导了二维层状结构稀土硫酸盐晶体的生长。对化合物13的磁性进行了研究,测试的温度范围在2~300 K。  相似文献   

19.
Studies on photo-catalytic reduction of CO2 using TiO2 photo-catalyst (0.1%, w/v) as a suspension in water was carried out at 350 nm light. CO2 from both commercially available source, as well as generated in situ through 2-propanol oxidation, was used for this study. The photolytic products such as hydrogen (H2), carbon monoxide (CO) andmethane (CH4) generated were monitored in TiO2 suspended aqueous solution with and without a hole scavenger, viz., 2-propanol. Similar photolytic experiments were also carried out with varying ambient such as air, O2, N2 and N2O. The yields of CO and CH4 in all these systems under the present experimental conditions were found to be increasing with light exposure time. H2 yield in N2-purged systems containing 2-propanol was found to be more as compared to the without 2-propanol system. The rate of H2 production in N2-purged aqueous solutions containing 0.1% TiO2 suspension were evaluated to be 0.226 and 5.8 μl/h, without and with 0.5 M 2-propanol, respectively. This confirmed that 2-propanol was an efficient hole scavenger and it scavenged photo-generated holes (h+), allowing its counter ion, viz., e, to react with water molecule/H+ to yield more H2. The formation of both CO and CH4 in the photolysis of CO2-purged aqueous solutions containing suspended TiO2 in absence of 2-propanol reveal that the generation of CH4 is taking place mainly through CO intermediate. In presence of air/O2, the yield of H2 in the system without 2-propanol was observed to be negligible as compared to the system containing 2-propanol in which low yield of H2 was obtained with a formation rate of approx. 0.5 μl/h.  相似文献   

20.
Microencapsulation technology for thiourea corrosion inhibitor   总被引:1,自引:0,他引:1  
The microencapsulation technology was brought in to solidify corrosion inhibitor in order to prolong the releasing time of it. In this work, thiourea (H2NCSNH2) was used as a corrosion inhibitor and microcapsuled using glutin and polyvinyl alcohol (PVA), respectively, as protective agent. The re-sealing process was used as a way to prolong the releasing time of the H2NCSNH2 encapsulated in microcapsules. It was found that the H2NCSNH2 microcapsule corrosion inhibitor using PVA as a protective agent had a better releasing time. The releasing times of the H2NCSNH2 microcapsule corrosion inhibitors were prolonged from 18 to 48 h by re-sealing process and using PVA as a protective agent. Both the use of PVA as a protective agent and the application of the re-sealing process decreased the encapsulation efficiency of the H2NCSNH2. The performance parameters on protecting Q235 carbon steel from corrosion in 0.1-M H2SO4 solution were evaluated by polarization curve and electrochemical impedance spectra methods. The results showed that the H2NCSNH2 released into the solution from microcapsules could well protect Q235 carbon steel from corrosion and the corrosion-inhibiting mechanisms of it were the same as that of H2NCSNH2.  相似文献   

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