Ion-Molecular Reactions of Diethylsilylium Ions with Alcohols in the Gas Phase

Radiochemistry was used to study reaction of tritium-labeled diethylsilylium ions with alcohols in the gas phase. The reaction involves both rearrangement of the diethylsilylium ions and isomerization of the substituent in the substrate. The hydroxyl hydrogen of the alcohol and the tritium atom of the diethyl-silylium ion undergo exchange which, however, is less vigorous that in the case of the monoethylsilylium ion. A possible reaction mechanism is proposed.     

应用MALDI-FTICRMS技术研究气相中含钨系列离子簇

以Keggin型磷钨酸为原料, 2,5-二羟基苯乙酮(DHAP)和2,4,6-三羟基苯乙酮(THAP)为基质, 使用基质辅助激光解吸/电离-傅里叶变换离子回旋共振质谱(MALDI-FTICRMS)技术研究气相中金属相关簇的稳定性及气相离子-分子反应. 在气相中获得不同系列的-1价含钨离子簇, 准确确定各系列离子簇的组成及Magic Numbers物种, 并发现基质与钨相互作用生成有机-无机杂化离子簇系列. 结果表明, MALDI-FTICRMS技术适用于研究气相中团簇离子的稳定性及气相离子-分子反应.     

一些双电荷离子的气相碎裂反应

借助质量分析离子动能谱和串联质谱研究了由电子轰击产生的双电荷离子的单分子亚稳碎裂及碰撞诱导分解过程,讨论了两种实验方法导致的差别因素.此外,根据质量分析离子动能谱提供的双电荷离子电荷分离反应的动能释放值计算了两电荷中心间距的最小值,以判别按不同电荷分离方式碎裂的双电荷离子的过渡态结构.     

气相中铜催化的脱羧碘化反应

提供了一种通过电喷雾电离质谱在气相中对一类有机铜配体复合物的合成方法.通过碰撞诱导解离和分子-离子反应,在离子阱质量分析器中完成了气相中铜催化的脱羧碘化反应.羧酸（RCOOH）作为反应物最终通过碰撞诱导解离技术和分子-离子反应转化为碘代烃（RI）.在整个反应过程中,观察到了铜的价态变化,由此也对羧酸的脱羧碘化反应的反应机理进行了解释.同时,不同的羧酸和双氮配体也适用于该反应体系.该方法检测了一类有机铜复合物的气相反应活性,并对液相中铜催化的脱羧碘化反应的反应机理研究提供了重要信息.     

Radiochemical Study of the Reactions of Diethylsilylium Ions with Hexamethyldisilazane and Isobutylamine in the Gas Phase

Ion-molecule reactions of diethylsilylium ions with hexamethyldisilazane and isobutylamine were studied radiochemically. These reactions, like the previously studied reactions of diethylsilylium ions with tert-butylaminotrimethylsilane, occur exclusively along the condensation pathway; in both cases, the diethylsilylium ion undergoes a rearrangement. The extremely low degree of rearrangement of the diethylsilylium ion and high yield of the labeled substrate in the reaction with isobutylamine are due to the presence of two labile N-H hydrogen atoms, resulting in active isotope exchange between the Si-T tritium atoms and N-H hydrogen atoms and in shorter lifetime of the condensation complex, caused by more intense bimolecular deprotonation of the complex.     

甲基羟基铀酰离子与水的复分解反应

以醋酸铀酰为主要试剂, 在负离子检测模式下, 采用电喷雾串联质谱法制备了甲基羟基铀酰负离子. 实验发现, 气相中的甲基羟基铀酰离子与水分子发生分子离子复分解反应, 并用串联质谱法对反应产生的离子性产物进行了结构确认, 提出了反应的可能机理. 热力学计算结果表明, 该反应的ΔGReaction为-473.0 kJ/mol, ΔHReaction为-236.5 kJ/mol, ΔSSystem为0.792 kJ·mol-1·K-1. 该反应的速率常数为2.26 s-1.     

缩酮作为探针反应表征催化剂活性的探索

将乙二醇与环己酮的缩合反应作为探针反应,对不同酸催化剂的催化活性进行了表征.在此基础上,提出了以反应速率来定量表征催化剂的反应活性,并以空白实验的活性为基础,提出了相对活性的概念.该表征方法简单快捷,能比较直观地反映出不同催化剂的活性大小.     

Preparation and Reaction of Cyclic Oxalate of Diols

Cyclic oxalates were efficiently prepared by the reaction of diols with ethyl oxalyl chloride in the presence of triethylamine. They were stable under acidic conditions but cleaved to diols under basic conditions.     

Gas Phase Reaction of Tetrachlorogermane with Conjugated Dienes in the Presence of Hexachlorodisilane Initiator

Studies of the reaction of GeCl₄ with acyclic conjugated dienes (1,3-butadiene, 2-methyl-1,3- butadiene, 2,3-dimethyl-1,3-butadiene) and cyclopentadiene in the presence of Si₂Cl₆ initiator were carried out. With acyclic dienes, corresponding 1,1-dichloro-1-germacyclo-3-pentenes and 1,1-dichloro-1-silacyclo-3- pentenes are preferrably formed. With cyclopentadiene the main reaction products are cyclopentenyltrichlorogermanes and cyclopentenyltrichlorosilanes formed respectively by hydrogermylation and hydrosilylation of the starting diene. The explanation of the established rule is offered.     

Structure and Reactivity of Gas‐Phase Molybdenum Oxide Cluster Ions

Combining the ion cyclotron resonance method and a Knudsen effusion source, we obtained a series of Mo_xO_y ⁺ (x = 1 – 5, y = 1 – 15) molybdenum oxide cluster ions. We studied the dependence of the concentrations of these ions on the trapping time and their reactions with carbon monoxide. It is shown that Mo_xO_y ⁺ ions with x > 3 contain a cyclic Mo₃O₉ fragment in their structure. The oxygen bond energies in Mo_xO_y ⁺ ionic clusters are estimated.     

Intra- and Inter-Molecular Cross-Linking of Peptide Ions in the Gas Phase: Reagents and Conditions

Intra-molecular and inter-molecular cross-linking of protonated polypeptide ions in the gas phase via ion/ion reactions have been demonstrated using N-hydroxysulfosuccinimide (sulfo-NHS)- based reagent anions. The initial step in the ion/ion reaction involves the formation of a long-lived complex between the peptide and reagent, which is a prerequisite for the covalent bioconjugation chemistry. The sulfonate groups on the NHS rings of the homo-bifunctional cross-linking reagents have high affinity for the protonated sites in the peptide and, therefore, facilitate the long-lived complex formation. In addition to the formation of a long-lived chemical complex, intra-molecular cross-linking also requires two unprotonated primary amine sites within a molecule where the covalent modification takes place. Alternatively, inter-molecular cross-linking demands the availability of one neutral primary amine site in each of the two peptides that are being cross-linked. Nucleophilic displacement of two sulfo-NHS groups by the amine functionalities in the peptide is a signature of the covalent cross-linking chemistry in the gas phase. Upon removal of the two sulfo-NHS groups, two amide bonds are formed between an unprotonated, primary amine group of a lysine side chain in the peptide and the carboxyl group in the reagent.     

激光溅射Cu等离子体与气相C2H5OH团簇的反应

用激光溅射-分子束技术研究了气相中Cu的等离子体与乙醇分子团簇的反应.观察到三种团簇正离子Cu＋(C2H5OH)n、CuO＋(C2H5OH)n、H＋(C2H5OH)n和三种团簇负离子(C2H5OH)nC2H5O－、(C2H5OH)n(H2O)OH－、(C2H5OH)n(H2O)2OH－(n≤12).详细考察了在不同的载气压力下激光烧蚀等离子体作用于脉冲分子束， 以及在一定的压力下等离子体作用于分子束不同位置时，对团簇产物种类和团簇尺寸大小的影响.分析了Cu＋(C2H5OH)n、CuO＋(C2H5OH)n、H＋(C2H5OH)n、(C2H5OH)nC2H5O－、(C2H5OH)n(H2O)OH－、(C2H5OH)n(H2O)2OH－等团簇的产生机理.     

Theoretical Study on the Reaction Mechanism of SiCl_4 with H in the Gas Phase

1 INTRODUCTION Semiconductor silicon materials are vital for mi- croelectronic and information industry. Silicon has many advantages, for example, rich resource, out- standing quality and sophisticated processing tech- nology. So it has been widely used in semiconduc- tor industry. One of the key techniques of mo- dern microelectronic industry is epitaxial growth of single crystal thin film on single crystal silicon and its ba- cking materials. In the chemical vapour deposition of Si, g…     

Macrolide Analogues of the Novel Immunosuppressant Sanglifehrin: New Application of the Ring-Closing Metathesis Reaction

Macrocycles containing a conjugated 1,3-diene moiety have been synthesized for the first time in good yields by the ring-closing metathesis reaction [Eq. (1)]. The new compounds represent cyclophilin-binding, simplified analogues of the macrocyclic core of sanglifehrin A, an immunosuppressant which binds with high affinity to cyclophilin.     

气相中Cu＋和Zn＋与SCO反应的理论研究

为更清晰地揭示M^＋与SCO基元反应的机理, 采用密度泛函B3LYP方法, 在6-311＋＋G**基组水平上研究了Cu^＋＋SCO和Zn^＋＋SCO反应体系. 对反应势能面上各驻点的几何构型进行了全优化, 用频率分析方法和内禀反应坐标(IRC)方法对过渡态进行了验证. 在Cu^＋与SCO的反应中, 对影响反应机理和反应速率的势能面交叉现象进行了讨论, 运用Hammond假设和Yoshizawa等的内禀反应坐标垂直激发的计算方法找到了势能面交叉点. 计算结果表明, C—S和C—O键的活化都是通过插入消去机理, 但C—S键的活化在能量上更占优势. 计算确认了标题反应的主通道, 所有的计算结果与实验吻合.     

CH3S与NO基态反应的机理及动力学

在G3(MP2)水平上,通过对CH3S与NO反应势能面(PES)上关键驻点的能量计算,共找到3种中间体、7个过渡态、9种产物通道,并对其反应机理进行了讨论.结果表明此反应主要以两种方式进行一是加成反应,先生成CH3SNO,然后发生单分子解离和异构化反应;二是直接抽提反应,生成CH2S+HNO.用多通道RRKM-TST模型计算了反应随温度和压力变化的速率常数.以295 K的N2作浴气,在200.0～39996.6 Pa压力范围的速率常数为1.6×10-12～1.28×10-11 cm3·molecule-1·s-1.我们计算的速率常数与Balla等的实验值符合较好.反应的速率常数有明显的负温度效应和较强的压力依赖关系.预测常压低温下反应以生成CH3SNO为主,在常压高温1000 K以上以生成CH2S+HNO为主.     

Theoretical Study on the Gas Phase Reaction of Au + with CS2

The reaction of Au+(1S,3D) with CS2 has been investigated at the B3LYP and CCSD(T) levels of theory.The identified reaction pathways revealed that the experimentally observed products,AuS+ and AuCS+,can be produced by the insertion of Au+ into C-S bond.The calculated energetics shows that the reactions on singlet surface lead to excited-state products,AuS+(1Σ) + 1CS and AuCS+(1Σ) + 1S,and have notable energy barriers,whereas the reactions on triplet surface producing the ground state products of AuS+(3Σ) + 1CS and AuCS+(1Σ) + 3S are energetically much more favorable.This result suggests that the minor formations of AuS+ and AuCS+ observed in the previous experiment under room-temperature condition should result from the reactions of excited-state Au+(3D) with CS2.Further,the possibility for singlet-triplet surface crossing was also discussed by approximately determining the crossing region.