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1.
用INDO系列方法研究C78(CH2)2的18种可能异构体,表明最稳定异构体是42,43,62,63-C78(CH2)2,其中CH2加在C78(C2V)椭球长轴所穿过的同一六员环的两个6/6键上,形成类环丙烷结构。并对最稳定的四种异构体用B3LYP/3-21G方法进行了结构优化,在此基础上, 用INDO/CIS方法计算的C78(CH2)2稳定异构体的电子光谱的第一吸收峰和用AM1方法计算的碳笼上的C-C键的主要红外振动频率与C78(C2V)相比发生兰移,原因是C78(CH2)2具有较大的LUMO-HOMO能隙和由于加成带来的共轭体系变小。在B3LYP/3-21G水平上计算的13C NMR谱表明,被加成的C-C键上的C原子化学位移向高场移动, 这是因为sp2杂化的C 原子被转化为 sp3杂化的C 原子.  相似文献   

2.
钌可以促使炔烃通过亚乙烯基钌卡宾金属配合物或钌金属杂环配合物的形式发生碳-碳偶联反应, 它的化学性质很大程度上取决于配体的电子和立体特征. 普通环戊二烯基钌配合物可以促使炔烃三聚生成苯环衍生物或使两分子炔烃和一分子含C=X键(X = C, O, S, N等)的不饱和底物发生环加成反应得到杂环化合物. 含桥联碳硼烷–环戊二烯基配体的钌乙腈配合物[η5:σ-Me2C(C5H4)(C2B10H10)]Ru(NCCH3)2 (1)表现出与环戊二烯基钌不同的反应性质. 例如, 配合物1与三甲基硅基取代的端炔或中间炔反应可生成含有单或双亚乙烯基有机钌卡宾配合物; 与末端芳炔则通过三分子炔和桥联配体中的环戊二烯基发生加成反应得到含有独特三环结构的有机钌配合物. 以上结果表明, 配体的位阻效应和炔烃的种类都可以影响产物的类型. 本文进一步研究了此钌乙腈配合物1与烷基或芳基取代的中间炔及中间二炔的反应. 配合物1与3-己炔或二苯乙炔在甲苯中于 80 ℃反应可以生成对空气和水稳定的η4-钌-环丁二烯配合物[η5: σ-Me2C(C5H4)(C2B10H10)]Ru(η4-C4Et4) (2) 或 [η5:σ-Me2C(C5H4)(C2B10H10)]Ru(η4-C4Ph4) (3), 此反应相信是通过一个钌杂环戊三烯中间体进行的. 由于这个中间体既不能在反应中被分离到也不能在核磁反应中被监测到, 我们接下来尝试了1和1,6-二炔的反应. 在 1与2,7-壬二炔或3,8-十一碳二炔的反应中成功分离到钌杂环戊三烯配合物[η5: σ-Me2C(C5H4)(C2B10H10)]Ru[=C2- (Me)2C2(CH2)3] (4) 或 [η5: σ-Me2C(C5H4)(C2B10H10)]Ru[=C2(Et)2C2(CH2)3] (5). 化合物4与5 在甲苯回流温度仍然稳定. 由于位阻效应, 它们也不与苯乙炔、3-己炔、苯基异氰酸酯、二硫化碳以及叔丁基异腈反应. 以上新化合物通过了核磁和元素分析表征, 其中化合物2和4的结构得到了单晶X射线衍射确定. 在化合物2的晶体结构中, 钌原子通过η5-键与环戊二烯基配位, σ-键与硼笼相连, 以及η4-键与环丁二烯配位, 形成一个平面三角形结构. 在化合物4的晶体结构中, 钌原子通过η5-键与环戊二烯基配位, σ-键与硼笼相连, 以及与两个碳卡宾原子配位, 形成一个扭曲四面体构型. 钌与碳卡宾原子之间的键长显示其为Ru=C双键. 在以上实验结果基础上我们提出了1与炔烃反应生成2和3的反应机理: 钌-乙腈配合物通过与炔烃的配体交换反应得到钌-二炔配合物, 进一步氧化偶联得到钌杂环戊三烯中间体, 还原消除反应得到最终产物?钌-环丁二烯配合物. 在1与二炔的反应中, 4和5中的并环结构可以阻止还原消除反应, 从而起到稳定钌杂环戊三烯中间体的作用. 上述实验结果表明, 桥联碳硼烷配体和底物(炔烃)的空间位阻效应都对反应有很大的影响.  相似文献   

3.
采用HF, MP2, CCSD以及CISD方法,研究了二价阴离子C7H22-和C7H32-及其一价阴离子的几何结构振动频率。在理论上,我们得到了C7H22-和C7H32-能量最低结构分别为:C2C(H2)C42-和C2CHCHCHC22-,而且均没有虚频。计算这两种结构所有可能的碎片化通道,碎片化能表明这两结构都不易解离为两个一价阴离子碎片。但是这两结构的垂直电离能和绝热电离能表明C2C(H2)C42-是稳定的,但C2CHCHCHC22-是不稳定的。  相似文献   

4.
利用高压容积法辅以卸压升温脱附排水法, 测定金属K修饰多壁碳纳米管对H2的吸附储存容量. 结果表明, 在室温(25 ℃), 7.25 MPa实验条件下, x%K0-MWCNTs (x%=30%~35%, 质量百分数)对H2的吸附储存容量可达3.80 wt%(质量百分数), 是相同条件下单纯MWCNTs氢吸附储量的2.5倍; 室温下卸至常压的脱附氢量为3.36 wt%(占总吸附氢量的~88%), 后续升温至673 K的脱附氢量为0.41 wt%(占总吸附氢量的~11%). 利用LRS和H2-TPD-GC/MS等谱学方法对H2/K0-MWCNTs吸附体系的表征研究表明, H2在K0-MWCNTs上吸附存在非解离 (即分子态)和解离(即原子态)两种吸附态; 在≤723 K温度下, H2/K0-MWCNTs体系的脱附产物几乎全为H2气; 723 K以上高温脱附产物不仅含H2, 也含有CH4, C2H4和C2H2等C1/C2-烃.  相似文献   

5.
合成了高氯酸镨和咪唑(C3H4N2), DL-α-丙氨酸(C3H7NO2)混配配合物晶体. 经傅立叶变换红外光谱、化学分析和元素分析确定其组成为[Pr(C3H7NO2)2(C3H4N2)(H2O)](ClO4)3. 使用具有恒温环境的溶解-反应量热计, 以2.0 mol•L-1 HCl为量热溶剂, 在T=(298.150±0.001) K时测定出化学反应PrCl3•6H2O(s)+2C3H7NO2(s)+C3H4N2(s)+3NaClO4(s)=[Pr(C3H7NO2)2(C3H4N2)(H2O)](ClO4)3(s)+3NaCl(s)+5H2O(1)的标准摩尔反应焓为ΔrHmө=(39.26±0.11) kJ•mol-1. 根据盖斯定律, 计算出配合物的标准摩尔生成焓为ΔfHmө{[Pr(C3H7NO2)2(C3H4N2)(H2O)](ClO4)3(s), 298.150 K}=(-2424.2±3.3) kJ•mol-1. 采用TG-DTG技术研究了配合物在流动高纯氮气(99.99%)气氛中的非等温热分解动力学, 运用微分法(Achar-Brindley-sharp和Kissinger法)和积分法(Satava-Sestak和Coats-Redfern法)对非等温动力学数据进行分析, 求得分解反应的表观活化能E=108.9 kJ•mol-1, 动力学方程式为dα/dt=2(5.90×108/3)(1-α)[-ln(1-α)]-1exp(-108.9×103/RT).  相似文献   

6.
碳纳米管负载纳米Fe2O3的研究   总被引:4,自引:0,他引:4  
本文研究了用液相化学沉积法制备的碳纳米管负载Fe2O3。首先用浓HCl、浓HNO3和浓HNO3 / H2SO4(混酸)三种酸对碳纳米管进行改性处理,对样品进行了TEM形貌观察和FTIR光谱分析,FTIR分析表明浓HCl处理后不能在碳纳米管表面引入官能团,而浓HNO3能在碳纳米管表面引入-OH和-C=O,浓HNOO3 / H2SO4能在碳纳米管表面引入大量的-OH、-C=O、COOH。制备了以上三种碳纳米管分别负载Fe2O3。TEM分析表明,负载效果:混酸>浓HNO3>浓HCl。经混酸处理后的碳纳米管所负载的Fe2O3的XRD分析,表明所负载的是α-Fe2O3。机理分析表明碳纳米管上的含氧基团能增强其在水溶液中的分散性,同时能增强其对Fe3+吸附和离子交换能力,使吸附在碳纳米管表面的Fe3+成为结晶成核中心,调节溶液pH值后,使Fe2O3沉积在碳纳米管表面。  相似文献   

7.
采用广义梯度近似的密度泛函理论并结合平板模型的方法, 优化了糠醛分子在Pt(111)面的吸附模型,并探究了糠醛脱碳反应形成呋喃的机理. 结果表明: 吸附后糠醛分子环上的C―H(O)键及支链―CHO相对于金属表面倾斜上翘, 分子平面被扭曲, 易于呋喃的形成; 同时, 糠醛分子向Pt表面转移电子0.765e, 环中的大π键与Pt(111)表面的d轨道发生较强的相互作用, 使得糠醛的芳香性被破坏, 环上的碳原子呈现准sp3杂化. 此外, 对糠醛脱碳反应中的各反应步骤进行过渡态搜索, 通过比较各步骤的活化能, 得出糠醛更易先失去支链上的H形成酰基中间体(C4H3O)CO, 中间体继续脱碳加氢形成产物呋喃. 该过程的控速步骤为(C4H3O)CO*+*→C4H3O*+CO* (*为吸附位),活化能为127.65 kJ·mol-1.  相似文献   

8.
以磷铁废渣(Fe1.5P)和温室效应气体CO2为原料,以磷酸为补充磷源合成磷酸铁锂(LiFePO4)的前驱体Fe2P2O7,并研究了其合成过程对LiFePO4正极材料储能性能的影响。采用SEM观察了LiFePO4的表面形貌,采用XRD分析了LiFePO4和Fe2P2O7的晶体结构。进一步对该方法进行优化,发现Fe1.5P与磷酸混合物(nFe1.5PnH3PO4=1:1)在800℃热处理6 h合成的Fe2P2O7对应的LiFePO4/C电化学性能最好,在0.1C,0.2C,0.5C和1C倍率下的容量分别可达130,126,117和108 mAh·g-1。  相似文献   

9.
合成了高氯酸镨和咪唑(C3H4N2), DL-α-丙氨酸(C3H7NO2)混配配合物晶体. 经傅立叶变换红外光谱、化学分析和元素分析确定其组成为[Pr(C3H7NO2)2(C3H4N2)(H2O)](ClO4)3. 使用具有恒温环境的溶解-反应量热计, 以2.0 mol•L-1 HCl为量热溶剂, 在T=(298.150±0.001) K时测定出化学反应PrCl3•6H2O(s)+2C3H7NO2(s)+C3H4N2(s)+3NaClO4(s)=[Pr(C3H7NO2)2(C3H4N2)(H2O)](ClO4)3(s)+3NaCl(s)+5H2O(1)的标准摩尔反应焓为ΔrHmө=(39.26±0.11) kJ•mol-1. 根据盖斯定律, 计算出配合物的标准摩尔生成焓为ΔfHmө{[Pr(C3H7NO2)2(C3H4N2)(H2O)](ClO4)3(s), 298.150 K}=(-2424.2±3.3) kJ•mol-1. 采用TG-DTG技术研究了配合物在流动高纯氮气(99.99%)气氛中的非等温热分解动力学, 运用微分法(Achar-Brindley-sharp和Kissinger法)和积分法(Satava-Sestak和Coats-Redfern法)对非等温动力学数据进行分析, 求得分解反应的表观活化能E=108.9 kJ•mol-1, 动力学方程式为dα/dt=2(5.90×108/3)(1-α)[-ln(1-α)]-1exp(-108.9×103/RT).  相似文献   

10.
通过原位反应法,利用富镍层状金属氧化物LiNi0.8Co0.1Mn0.1O2(LNCM811)正极材料表面残余的氢氧化锂和碳酸锂,与C8H20O4Ti和(NH4)H2PO4反应,在LNCM811表面原位生成快离子导体LiTi2(PO43(LTP)包覆层。这种原位反应的包覆方法有利于移除LNCM811表面有害的残留物氢氧化锂和碳酸锂。而且,获得的LTP均匀包覆层不仅可以有效地抑制LNCM811表面和电解液的直接接触及其副反应,还可以确保充放电循环过程中LNCM811正极材料的快速Li+传导。因此,在LTP包覆层的多重作用下,LTP包覆的LNCM811正极材料具有优异的循环稳定性和倍率性能:在0.2C时,首次放电比容量高达200.6 mAh·g-1,200圈后的可逆容量依然有155.7 mAh·g-1;在2C和5C的高电流密度下,200圈后的可逆容量仍然有126.4和111.9 mAh·g-1。  相似文献   

11.
The adsorption of C2H4 on W(100) has been studied by ultraviolet photoelectron spectroscopy with hν = 21.22 eV. The spectrum measured after in initial saturation exposure at 80 K exhibits structure which correlates well with energy levels recently calculated by Demuth and Eastman (DE) for sp3 rehybridized C2H4. Dehydrogenation of the adsorbate, either by subsequent heating to 295 K or direct adsorption at 295 K, yields a spectrum which correlates with DE's calculation for sp2 rehybridized C2H2. These results suggest that C2H4 and C2H2 may be distorted from their planar and linear structures respectively and that the CC bonds on these molecules are stretched by adsorption on W(100). Qualitative arguments suggest that the bonding site for both melecules is directly over a W atom and that the Dewar—Chatt model for πd bonding in organometallic compounds is applicable.  相似文献   

12.
An X-ray structure analysis for the title complex obtained by the reaction of PtIICL2(C5H4NC(O)C?H+NC5H3(CH3)2-3.5) with ethylenediamine in water has revealed the presence of an ylide carbon atom which is coordinated to the platinum(II) ion with an sp2 configuration.  相似文献   

13.
1-Allyl-4-aminopyridinium chloride reacts with Cu(NO3)2 · 3H2O in an ethanolic solution under the conditions of ac electrochemical synthesis at copper electrodes to form crystals of compound [(NH2C5H4N(C3H5))2Cu3Cl3(NO3)2] (I). The crystals of compound I are monoclinic: space group P21/c, Z = 4, a = 25.770(7), b = 7.230(4), c = 12.505(5) ?, β = 92.58(3)°, V = 2328(2) ?3. The direct interaction of 1-allylquinolinium nitrate with Cu(NO3)2 · 3H2O in a methanolic solution in the presence of metallic copper yields crystals of compound [C9H7N(C3H5)Cu(NO3)2] (II). The crystals of compound II are triclinic: space group P , a = 6.756(3), b = 8.391(4), c = 12.489(5) ?, α = 77.18(3)°, β = 89.48(4)°, γ = 73.32(3)°, V = 662.0(5) ?3. The structure of compound I is built of infinite linear anions: polymeric fragments {(NH2C5H4N(C3H5))2Cu3Cl3(NO3)2} n . Each of two copper atoms (Cu(1) and Cu(2)) π-coordinates the C=C bonds of the allyl groups of the 1-allyl-4-aminopyridinium cations, the oxygen atom of the nitrate ions, and two chlorine atoms. The third copper atom Cu(3) is linearly linked with two chlorine atoms. Particular polymeric fragments are additionally joined by the N-H…O, C-H…O, C-H…Cl hydrogen bonds. The crystal structure of compound II is built-up of the isolated L2Cu2(NO3)4 fragments (L is the 1-allylquinolinium cation). The metal atom is localized in the trigonal pyramidal coordination environment of three oxygen atoms of the nitrate ions and of the C=C bond of the allyl group of the cation. The particular L2Cu2(NO3)4 fragments are additionally joined by the C-H…O hydrogen bonds. Original Russian Text ? A.V. Pavlyuk, T. Lis, M.G. Mys’kiv, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 6, pp. 458–462.  相似文献   

14.
Bis(cycloocta-1,5-diene)platinum reacts with 2,3,4,5-tetraphenylfulvene to afford the complex [Pt(η2-CH2C5Ph4)(cod)] (cod  C8H12) in which the metal atom is coordinated to the exo-cyclic double bond of the fulvene. Related compounds [Pt(η2-CH2C5Ph4L2] (L  PPh3, PMePh2, PMe2Ph, AsPh3 or CNBut have also been prepared and characterised. Reaction of the complexes [Pt(C2H4)2(L)] (L  P(cyclo-C6H11)3, PPh3 or AsPh3) with 2,3,4,5-tetraphenylfulvene yields the compounds [Pt(C2H4)(η2-CH2C5PH4)(L)]. NMR data for the new species are reported and discussed. 6,6-Diphenylfulvene reacts with [Pt(cod)2] and PPh3 (12 mol ratio) to give the complex [Pt(η2-C5H4CPh2)-(PPh3)2] in which the metal atom is bonded to carbon atoms C(2) and C(3) of the fulvene ring. This was established by an X-ray diffraction study. Crystals are monoclinic, space group P21/n, with Z  4 in a unit cell of dimensions a  13.761(4), b  21.653(13), c  17.395(6) Å, β,  104.46(2)°. The structure has been solved and refined to R  0.064 (R′  0.064) for 3139 independent diffracted intensifies measured at room temperature. The platinum atom is in a trigonal environment formed by the two ligated phosphorus atoms and the CC bond of the fulvene which is elongated to 1.52(3) Å. The c5 fulvene ring is planar, and makes an angle of 108° with the coordination plane around the platinum. In this plane the metal atom is slightly asymmetrically bonded with PtC 2.15(2) and 2.24(2) Å, and PtP 2.280(6) and 2.301(6) Å.  相似文献   

15.
This paper deals with the synthesis of six σ-cyclohexylethynyl complexes of CoII and FeII and their characterization by chemical analysis, infrared and 1H NMR spectra, and magnetic measurements. Four of them are six-coordinate complexes, unsubstituted or substituted, namely K4[M(C≡C—C6H11)6] nNH3(M = Co, n = 2; M = Fe, n = 0), K2[Co(C≡C6H11)4(NH3)2] and K4[Fe(CN)4-(C≡C—C6H11)2]. Two are four-coordinate complexes of formula [(Ph3P)2M-(C≡C6H11)2] (M = Co, Fe). All are low-spin complexes, the magnetic moment for the six-coordinate Co(II) complexes, measured at various temperatures, being intermediate between low- and high-spin values.  相似文献   

16.
Thermally induced dehydrogenation of the H‐bridged cation L2B2H5+ (L=Lewis base) is proposed to be the key step in the intramolecular C? H borylation of tertiary amine boranes activated with catalytic amounts of strong “hydridophiles”. Loss of H2 from L2B2H5+ generates the highly reactive cation L2B2H3+, which in its sp2‐sp3 diborane(4) form then undergoes either an intramolecular C? H insertion with B? B bond cleavage, or captures BH3 to produce L2B3H6+. The effect of the counterion stability on the outcome of the reaction is illustrated by formation of LBH2C6F5 complexes through disproportionation of L2B2H5+ HB(C6F5)3?.  相似文献   

17.
(2S,3S)‐2,6‐Dimethylheptane‐1,3‐diol, C9H20O2, (I), was synthesized from the ketone (R)‐4‐benzyl‐3‐[(2R,3S)‐3‐hydroxy‐2,6‐dimethylheptanoyl]‐1,3‐oxazolidin‐2‐one, C19H27NO4, (II), containing C atoms of known chirality. In both structures, strong hydrogen bonds between the hydroxy groups form tape motifs. The contribution from weaker C—H...O hydrogen bonds is much more evident in the structure of (II), which furthermore contains an example of a direct short Osp3...Csp2 contact that represents a usually unrecognized type of intermolecular interaction.  相似文献   

18.
Thermally induced dehydrogenation of the H‐bridged cation L2B2H5+ (L=Lewis base) is proposed to be the key step in the intramolecular C H borylation of tertiary amine boranes activated with catalytic amounts of strong “hydridophiles”. Loss of H2 from L2B2H5+ generates the highly reactive cation L2B2H3+, which in its sp2‐sp3 diborane(4) form then undergoes either an intramolecular C H insertion with B B bond cleavage, or captures BH3 to produce L2B3H6+. The effect of the counterion stability on the outcome of the reaction is illustrated by formation of LBH2C6F5 complexes through disproportionation of L2B2H5+ HB(C6F5)3.  相似文献   

19.
The iridium complexes IrH2{C6H3-2,6-(CH2PBut2)2 (1), IrH2{C6H3-2,6-(CH2PPri2)2 (2), and IrHCl{C6H3-2,6-(OPBut2)2 (3) have been found to be highly active catalysts for the dehydrogenation of N-ethyl perhydrocarbazole at 200 °C. However, dehydrogenation to the fully unsaturated ethyl carbazole does not occur in most instances. Complex 3 is the most active catalyst and shows reasonable activity even at 150 °C. No signs of dehydrogenation were found in experiments conducted at 100 °C. This apparently reflects the thermodynamic constraints imposed by the high enthalpy of dehydrogenation of the substrate.  相似文献   

20.
代小平  余长春  李然家 《催化学报》2007,28(12):1047-1052
在固定床反应器上考察了原粒度(1~3mm)CeO2助Co/SiO2催化剂的费托反应性能,提出了催化剂失活的机理,并采用程序升温还原、X射线衍射和X射线光电子能谱对催化剂进行了表征.结果表明,在1.5MPa,488K和400h-1条件下进行的300h稳定性实验中,原粒度CeO2助Co/SiO2催化剂上的CO平均转化率达到41%,液态烃选择性达到85%,液态烃中C10 烃的质量含量占88%以上.反应器出口的催化剂中有少量的CoO和Co2SiO4生成.催化剂的失活过程受动力学控制而非热力学控制,催化剂的失活机理为:高分散的纳米Co离子在反应器出口高水蒸气压力的作用下,以CoO为中间物种,与水合SiO2作用生成Co2SiO4,即Co H2O→CoO H2,SiO2 H2O→OSi(OH)2,2CoO OSi(OH)2→Co2SiO4 H2O.  相似文献   

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