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[(dmpe)_2MnAlH_4]_2和(dmpe)_2MnAlH_4的电子结构和化学键
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作者 吴念慈 蔡国强 董南 《化学研究与应用》 CAS CSCD 1991年第4期78-81,共4页
70年代中期,已有不少作者对过渡元素硼氢化合物进行研究。但对过渡元素铝氢化合物的研究是近几年才开始的。这两类化合物的化学行为有着显著差异,通常,硼以四配位单个形式存在,而铝则以五配位双聚形式存在,我们曾用CNDO/2研究了Cp<su... 70年代中期,已有不少作者对过渡元素硼氢化合物进行研究。但对过渡元素铝氢化合物的研究是近几年才开始的。这两类化合物的化学行为有着显著差异,通常,硼以四配位单个形式存在,而铝则以五配位双聚形式存在,我们曾用CNDO/2研究了Cp<sub>2</sub>BH<sub>4</sub>、Cp<sub>2</sub>TiBH<sub>4</sub>、Cp<sub>2</sub>TiAlH<sub>4</sub>、(dmpe)<sub>2</sub>HCrBH<sub>4</sub>、(dmpe)<sub>2</sub>HCrAlH<sub>4</sub>以及其它一些Ti的五配位铝化合物的电子结构,较合理地解释了这一现象。 展开更多
关键词 CNDO/2 铝氢化合物 电子结构 桥骨架
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(Cp_2Ti)_2AlH_4CH_3,(Cp_2Ti)_2AlH_4Cl和(Cp_2Ti)_2AlH_4BH_4配合物的电子结构和催化活性
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作者 蔡国强 董南 吴念慈 《Chinese Journal of Catalysis》 SCIE CAS CSCD 北大核心 1990年第5期403-409,共7页
本文用CNDO方法研究了配合物(Cp_2Ti)_2AlH_4CH_3(Ⅰ),(Cp_2Ti)_2AlH_4Cl(Ⅱ)和(Cp_2Ti)_2AlH_4BH_4(Ⅲ)的电子结构和其催化活性的关系。结果表明,从Ⅰ到Ⅲ,随着Ⅹ吸电子能力增加,HOMO能量、在HOMO中氢桥骨架(Ti(μ-H)_2AlX(μ-H)_2Ti)... 本文用CNDO方法研究了配合物(Cp_2Ti)_2AlH_4CH_3(Ⅰ),(Cp_2Ti)_2AlH_4Cl(Ⅱ)和(Cp_2Ti)_2AlH_4BH_4(Ⅲ)的电子结构和其催化活性的关系。结果表明,从Ⅰ到Ⅲ,随着Ⅹ吸电子能力增加,HOMO能量、在HOMO中氢桥骨架(Ti(μ-H)_2AlX(μ-H)_2Ti)成分、Al原子的电荷密度以及在LUMO中Ti原子成分均依次下降,但Ti—H键级依次上升,这些与在烯烃加氢和烯烃异构化反应中,Ⅰ的催化活性最强,Ⅱ其次,Ⅲ最弱这一实验结果相符。 展开更多
关键词 配合物催化剂 铝氢化合物
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(dmpe)_2HCrBH_4、(dmpe)_2HCrAIH_4和[(dmpe)_2HCrAIH_4]_2的电子结构
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作者 蔡国强 吴念慈 董南 《化学研究与应用》 CAS CSCD 1990年第4期47-52,共6页
本文用CNDO/2方法研究了(dmpe)_2H_tCrBH_4(Ⅰ)、(dmpe)_2H_tCrAlH_4(Ⅱ)和[(dmpe)_2H_tCrAlH_4]_2(Ⅲ)(dmpe=(CH_3)_2PCH_2CH_2P(CH_3)_2,在计算时,我们用二个PH_3代替一个(dmpe)的电子结构。结果表明:(1)在(Ⅱ)的6b_1(HOMO),7a_1占据... 本文用CNDO/2方法研究了(dmpe)_2H_tCrBH_4(Ⅰ)、(dmpe)_2H_tCrAlH_4(Ⅱ)和[(dmpe)_2H_tCrAlH_4]_2(Ⅲ)(dmpe=(CH_3)_2PCH_2CH_2P(CH_3)_2,在计算时,我们用二个PH_3代替一个(dmpe)的电子结构。结果表明:(1)在(Ⅱ)的6b_1(HOMO),7a_1占据轨道中,Cr3d轨道与2H_b1S轨道(H_b为桥氢原子)对称性不匹配,相互排斥,而在(Ⅰ)中这种排斥有所减弱;Cr(u-H_b)_2Al骨架较Cr(u-H_b)_2B能量高而不稳定。(2)在(Ⅲ)的电子结构中Cr3d与2H_b1S之间排斥大为减弱,Cr(u-H_b)_2Al稳定性提高;新形成的AL(u-H)_2AL能量较低;在较高占据轨道中H_t和H_b成份多,活泼性强,这可能是H_t和H_b易交换的主要原因。三个化合物在电子结构上的差异较合理解释了实验现象。 展开更多
关键词 铬的硼化合物 铬的铝氢化合物 CNDO/2 电子结构
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Corrosion of in-situ grown Mg Al-LDH coating on aluminum alloy 被引量:4
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作者 张芬 张昌磊 +3 位作者 宋亮 曾荣昌 刘振国 崔洪芝 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第10期3498-3504,共7页
Mg Al-layered double hydroxides(LDH) coatings were fabricated by the in-situ hydrothermal treatment method on the AA5005 aluminum alloy.The characteristics of the coatings were investigated by XRD,FT-IR,SEM and EDS.... Mg Al-layered double hydroxides(LDH) coatings were fabricated by the in-situ hydrothermal treatment method on the AA5005 aluminum alloy.The characteristics of the coatings were investigated by XRD,FT-IR,SEM and EDS.The effect of the p H value of the solution on the formation of the LDH coatings was studied.The optimum p H value of the solution was 10.0.The corrosion resistance of the LDH coatings was studied using potentiodynamic polarization tests and electrochemical impedance spectrum(EIS).The results demonstrate that the LDH coatings,characterized by platelets vertically to the substrate surface possess excellent corrosion resistance.The influence of the hydrothermal crystallization time on the corrosion resistance was evaluated.Prolonging the crystallization time can increase the corrosion resistance of the obtained LDH coatings.The anticorrosion mechanism of the LDH coatings was discussed. 展开更多
关键词 aluminum alloy layered double hydroxide COATING CORROSION
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(Cp_2TiAlH_3Y)_2(Y=H、NH_2、OH)配合物的电子结构和性能的量子化学研究
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作者 蔡国强 俞庆森 +1 位作者 吴念慈 董南 《浙江大学学报(自然科学版)》 CSCD 1993年第4期547-554,共8页
本文用CNDO量子化学方法研究了配合物(Cp_2TiAlH_3Y)_2[Y=—H(Ⅰ)、—NH_2(Ⅱ)、—OH(Ⅲ))的电子结构和化学键。研究表明:氢键结构Ti(u—H)_2AlH(u—Y)_2AlH(u—H)_2Ti是配合物中最活泼的部分。这些分子的HOMO特征主要是TiH_2;Ti—H键... 本文用CNDO量子化学方法研究了配合物(Cp_2TiAlH_3Y)_2[Y=—H(Ⅰ)、—NH_2(Ⅱ)、—OH(Ⅲ))的电子结构和化学键。研究表明:氢键结构Ti(u—H)_2AlH(u—Y)_2AlH(u—H)_2Ti是配合物中最活泼的部分。这些分子的HOMO特征主要是TiH_2;Ti—H键是带有离子成份的共价键;分子从Ⅰ、Ⅱ到Ⅲ,HOMO能量下降,Ti—H键级增加,LUMO中Ti轨道成份下降。根据文中所提出的催化机理,上述性质的变化和它们在烯烃加氢和异构化中呈现的催化活性是一致的。此外,本文还解释了分子Ⅰ双聚的原因。 展开更多
关键词 化合物 电子结构 量子化学
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Stable High-Energy Density Super-Atom Clusters of Aluminum Hydride 被引量:1
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作者 Ke-yan Lian Yuan-fei Jiang +4 位作者 De-hou Fei Wei Feng Ming-xing Jin Da-jun Ding Yi Luo 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2012年第2期147-152,I0003,共7页
With the concept of super-atom, first principles calculations propose a new type of super stable cage clusters AlnH3n that are much more energetic stable than the well established clusters, AlnHn+2. In the new cluste... With the concept of super-atom, first principles calculations propose a new type of super stable cage clusters AlnH3n that are much more energetic stable than the well established clusters, AlnHn+2. In the new clusters, the aluminum core-frame acts as a super-atom with n vertexes and 2n A1-A1 edges, which allow to adsorb n hydrogen atoms at the top-site and 2n at the bridge-site. Using Al12H36 as the basic unit, stable chain structures, (Al12H36)m, have been constructed following the same connection mechanism as for (A1H3)n linear polymeric structures. Apart from high hydrogen percentage per molecule, calculations have shown that these new clusters possess large heat of formation values and their combustion heat is about 4.8 times of the methane, making them a promising high energy density material. 展开更多
关键词 High-energy density Super-atom First principles Cluster of aluminum hydride
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EPR and DFT Study of the Polycyclic Aromatic Radical Cations from Friedel-Crafts Alkylation Reactions
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作者 Tao Wang An-an Wu +1 位作者 Li-guo Gao Han-qing Wang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2009年第1期51-56,共6页
Electron paramagnetic resonance and electron-nuclear double resonance methods were used to study the polycyclic aromatic radical cations produced in a Friedel-Crafts alkylating sys- tem, with m-xylene, or p-xylene and... Electron paramagnetic resonance and electron-nuclear double resonance methods were used to study the polycyclic aromatic radical cations produced in a Friedel-Crafts alkylating sys- tem, with m-xylene, or p-xylene and alkyl chloride. The results indicate that the observed electron paramagnetic resonance spectra are due to polycyclic aromatic radicals formed from the parent hydrocarbons. It is suggested that benzyl halides produced in the Friedel-Crafts alkylation reactions undergo Scholl self-condensation to give polycyclic aromatic hydrocar- bons, which are converted into corresponding polycyclic aromatic radical cations in the presence of AlCl3. The identification of observed two radicals 2,6-dimethylanthracene and 1,4,5,8-tetramethylanthraeene were supported by density functional theory calculations using the B3LYP/6-31G(d,p)//B3LYP/6-31G(d) approach. The theoretical coupling constants support the experimental assignment of the observed radicals. 展开更多
关键词 Electron paramagnetic resonance Eelectron-nuclear double resonance Density functional theory Polycyclic aromatic radical cation
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Adsorption of Cd(II) on Zn-AI LDHs (Layered Double Hydroxides) Intercalated with Chelating Agents EDTA
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作者 Shuang Zhang Naoki Kano Hiroshi Imaizumi 《Journal of Chemistry and Chemical Engineering》 2016年第2期60-67,共8页
The hydrotalcite-like compound [Zn2AI(OH)6]NO3-mH20 (shorted as ZnAI-NO3) was intercalated with the chelating agent EDTA (ethylene diamine tetraacetic acid) by anion exchange to uptake cadmium ion from aqueous s... The hydrotalcite-like compound [Zn2AI(OH)6]NO3-mH20 (shorted as ZnAI-NO3) was intercalated with the chelating agent EDTA (ethylene diamine tetraacetic acid) by anion exchange to uptake cadmium ion from aqueous solutions. The materials synthesized in this work were characterized by chemical analysis, FT-IR (fourier transform infrared spectroscopy), XRD (X-ray powder diffraction) to confirm their properties. In order to investigate the optimum conditions for Cd(II) adsorption, the amount of Cd(ll) adsorbed by Zn-AI LDHs intercalated with EDTA (ZnAI-EDTA) under different conditions (i.e., adsorbent dosage, temperature and contact time) were determined by ICP-AES (inductively coupled plasma-atomic emission spectrometry). Adsorption isotherms of Cd(II) onto ZnA1-EDTA were measured at varying initial Cd concentrations (0.05 mg/L to 1 mg/L) under optimized conditions. The data were applied to Langmuir and Freundlich isotherms model, and well fitted by the Freundlich isotherms model. The pseudo-second-order kinetic model was more adequate to describe the kinetic in this case. 展开更多
关键词 Layered Double Hydroxide EDTA cadmium ADSORPTION kinetic.
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