排序方式: 共有191条查询结果,搜索用时 15 毫秒
101.
用量子化学自洽场分子轨道从头计算方法,采用STO-3G基组计算了MgH~+,Mg_2H~+离子的位能曲线与位能面;给出电子波函数与电子集居数;得到MgH~+的平衡构型键长γ_(Mg-H)1.60A.Mg_2H~+的平衡构型有C_(∞v)与D_(∞h)两类,前者为[Mg—Mg—H]~+,键长γ_(Mg-Mg)2.41,γ_(Mg-H)1.63A;后者为[Mg—H—Mg]~+,γ_(Mg-H)1.73A.前者的总能量比后者低50kcal/mol.还讨论了它们的稳定性.MgH~+的键长计算结果和实测值较吻合,Mg_2H~+的平衡构型计算结果支持了Porter从热力学研究提出的假设. 相似文献
102.
The adsorption of NH3 on (AO)3SiO*HAl(OA)2OSi(OA)3 cluster from the structure of site (VI) of mordenite Zeolite has been calculated by an adsorption model of hydrogen-bond form, quantum chemical method, CNDO/2 scheme. Variations of adsorption distance between NH3 and O* in the cluster were directly related to initial adsorption heats of NH3 on O*H group, jump frequency of the proton between NH3 and O* and frequency shift of IR band with O*H group. Adsorption distance of NH3 on O*H group has been calculated, the range was about 2.5 to 2.75A, and the most favourable adsorption distance with strong acid strength was 2.5A. It was related to the maximum initial adsorption heat which was 33.80 kcal/mol, the lowest activation energy of proton mobility between NH3 ane O*, and the largest frequency shift of IR bands with O*H group. This result qualitatively corresponded to experimental observations. It showed that the various representations of acidic strength are equivalent to each other which could be explained on basis of adsorptin model of hydrogen bond form. 相似文献
103.
The complexation of Rh(III) with nitrite ions was studied at ionic strength 3.0 and at 16`,26` and 35`C by solubility method. The results showed the formation of 1:1, 1:2, 1:3, 1:4, 1:5 and 1:6 complexes of Rh(III) with nitrite ions. The consecutive stability constants a1.d thermodynamic parameters ΔG0, ΔH and ΔS0 of complexation were calculated from the experimental data. 相似文献
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106.
基于金属有机和元素有机化合物参与的新合成方法学 的研究 总被引:1,自引:0,他引:1
包括下列研究工作:碱催化形成碳-碳双键的合成方法学;双烯化反应的合成方法学;立体选择性地控制合成烯炔和丙烯类化合物的合成方法等;连串反应的合成方法学。 相似文献
107.
总结了麻生明自1997年回国后在国家自然科学基金委、科技部、中国科学院、上海市科委的共同资助下开展的一些研究工作:(1)联烯化学;(2)偶联反应的区域选择性研究-1-芳基-1-炔烃的单锂化反应;(3)多中心反应-1,1-二溴-1-烯烃的氧化加成反应,α-脱卤钯化反应和分子内双环钯碳化反应。 相似文献
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109.
通过α-(1-萘基)-N-硫代甲酰乙胺与卤代酮反应制得六个光学活性的4-烷基-3-α-(1-萘基)乙基噻唑溴化物烷基碳链长=1,2,7.11,15,21). 将其用于催化水溶液中的安息香缩合反应, 所得产物收率约20-30%具有较高的光学纯度(47-57%). 在各种缓冲溶液中测定了S(+)-4-甲基-3-α-(1-萘基)乙基噻唑氯化物(Ta)的胶团性质和由它催化的不对称安息香缩合反应. 临界胶团浓度(cmc)证明(Ta)在反应中确以胶团形式催化. 在硼砂溶液中, 安息香的收率高达61%, 光学纯度23.6%. 相似文献
110.
本文报道了CW-CO2激光引发的CF2HCH3与Cl2的反应.除主要产物CF2=CH2外,还有CF2ClCH3. CF2ClCH2Cl. CF2=CHCl. CF2=CCl2和CF2Cl2.为了探索应用激光方法合成CF2=CH2的可能性,研究了激光输出功率. 照射时间. 反应体系中CF2HCH3与Cl2的比例及样品压力对CF2=CH2得率的影响.同时为了探讨反应机理,还进行了TEA-CO2激光引发CF2HCH3加Cl2实验和CW-CO2激光作用下CF2=CH2. CF2=CH2加Cl2的反应研究,令人感兴趣的是在激光照射CF2=CH2时,发现了双键的断裂. 相似文献