硅烯

The computa-tion indicated that the stable silicyl alkene is produced by the addition reaction of silicon alkyne and hydro-gen.

计算表明，硅炔与氢分子加成反应可生成稳定的甲硅烷基硅烯。

Two special structural features of the sulfonium salt were proved to stabilize its corresponding ylide and depress the 2,3-sigma rearrangement. One is that there is a trimethylsilyl in the end of the allylic double band. This silicon atom can stabilize a α-carbon anion and the corresponding ylide. Another is that there is hydroxy group in the beta-position of sulfonium atom. The oxygen of this hydroxy group may stabilize the sulfonium cation.

为了稳定生成的烯丙基硫叶立德，并抑制它的2， 3-sigma 重排反应，在硫叶立德结构上做了两方面的考虑：一是在烯丙基双键的未端引入硅基，利用硅原子对 a -碳负离子的稳定作用来稳定烯丙基硫叶立德；二是在硫原子的 b -位引入羟基，利用羟基氧对硫正离子的作用来稳定硫叶立德。

So, by the Diels-Alder reaction of tetraphenylcyclopentadienone, acenaphthenecyclone and benzophenanthrenecyclone with the vinyl groups in C gum, three kinds of polymethylvinylsilicone oil with condensed aromatics are synthesized respectively: polymethylvinylsilicone oil with tetraphenylphenyl groups (called C_1 gum for short), polymethylvinylsilicone oil with acenaphthenyl groups (C_2 gum) and polymethylvinylsilicone oil with benzophenanthrene groups (C3 gum).

根据此原则，利用四苯基环戊二烯酮、苊式环戊二烯酮和菲式环戊二烯酮与C胶上的乙烯基进行Diels—Alder反应，分别合成了三种含稠环基团的乙烯基硅油：四苯基苯基乙烯基硅油(C_1胶)，苊式多苯基苯基乙烯基硅油(C_2胶)和菲式多苯基苯基乙烯基硅油(C_3胶)，并根据~1HNMR谱图上不同氢原子的积分面积计算了三种胶中稠环基团和乙烯基的含量。

The results show that this reaction proceeds in two step: 1 silylene and formaldehyde form an intermediate complex, which is a kind of exothermal reaction with no barrier; 2 the intermediate complex isomerizes to sive the product. The barrier for the second step is 51.4kJ·mol^-^1 at MP2/6-31G^*//6-31G^* level (with zero-point energies correction). In view of dynamics and thermodynamics, it is between 300～400K that the reaction will have not only larger spontaneous tendency and equilibrium constant but also quicker reaction rate.

结果表明，此反应历程由两步组成：1硅烯与甲醛生成一中间配合物，是一无势垒的放热反应，2中间配合物异构化为产物，此步势垒经零点能校正后只有51.4kJ·mol^-^1(MP2/6-31G^*//6-31G^*)；从热力学和动力学的综合角度考虑，该反应在300～400K温度下进行为宜，如此，反应既有较大的自发趋势和平衡常数，又具有较快的反应速率。

Furthermore, single-point energy calculations were refined at the QCISD level of theory with the same basis set (6-311++G**). As a result, the singlet reaction of silylene with isothiocyanic acid contain S-atom abstraction channel, N—H inserted channel, and NH abstraction channel, respectively.

又用QCISD/6-311＋＋G**//B3LYP/6-311＋＋G**方法计算了各个驻点的单点能，计算结果表明单重态的硅烯与异硫氰酸的反应有抽提硫、插入、抽提亚氨基的路径。

The synthesis of hyperbranched poly based upon 1,2-bis diallyl (methyl silyl ethane (B4) as a core molecule and diallyl silane (AB2) monomer via hydrosilylation addition have been investigated: And the hyperbranched poly were prepared using onestep without core, one-step with core and pseudo-one-step methods.

以四烯丙基硅烷(B4)为核、甲基氢二烯丙基硅烷(AB2)为单体，通过硅氢加成反应，采用无核一步法、核一步法、核多步法合成了超支化聚有机硅破烷。

It is found that the stereochemistry of the reactions of telluronium allylide,crotonylide and trimethylsilyallylide with α,β-unsaturated esters and amides can be tuned by thechoice of reaction conditions.

利用反应条件的变化首次实现了烯丙基、巴豆基、含硅烯丙基碲叶立德与α，β-不饱和酯、酰胺进行环丙烷反应的立体化学调控，能高立体选择性地、高效率地合成两种不同几何异构体中的一个。

Thestercoselectivity of the reaction of propargylide was different completely from that of the reactionof telluronium 3-trimethylsilylalltide with α,β-unsaturaled ketones and trans-trimethysilylacetylenyl-l-benzoyleyelopropane derivatives were obtained.

发现这一反应的立体化学与同样条件下含硅烯丙基碲叶立德和α，β-不饱和酮反应的立体化学完全不同，得到的是又式-2-三甲基硅基乙炔基-1-酮基环丙烷衍生物。

These results show that the ring expansion of cyclopropylsilylene C3H5SiH to silacyclobutene is easy to occur with a barrier of 113.4kJ/mol, while the 1,2-H shift is not competitive to the ring expansion for its much higher barrier.

结果表明，环丙基硅烯经过113.4kJ/mol的势垒扩环重排为硅杂环丁烯为自发反应；而其1，2-氢迁移重排反应热垒为190.0kJ/mol，是非自发反应，难于进行，不能与扩环重排相竞争。

From the potential energy profile, it can be predicted that, the dominant channel of this reaction consists of three steps: the two reactants first form a three-membered ring intermediate (INT1) through a barrier-free exothermic reaction of 19.2 kJ/mol; three-membered ring intermediate (INT1) isomerizes to a four-membered ring silylene(P2) via the transition state (TS2) with an energy barrier of 22.8 kJ/mol; four-membered ring silylene(P2) further reacts with ethene(R2) to form a silicic bis-heterocyclic compound (P3), which is also a barrier-free exothermic reaction of 132.2 kJ/mol.

用CCSD//MP2/6-31G*方法研究了单重态二甲基亚烷基硅烯与乙烯生成硅杂双环化合物环加成反应的机理，根据该反应的势能面可以预言，该反应的主反应通道有三步组成：第一步是两反应物（R1， R2）首先生成了一三元环中间体（INT1），它是一无势垒的放热反应，放出的能量为19.2 kJ/mol；第二步是三元环中间体(INT1)经过渡态TS2异构化为了四元环硅烯（P2），其势垒为22.8 kJ/mol；第三步是四元环硅烯（P2）进一步与乙烯(R2)反应生成了硅杂双环化合物（P3），该反应也是一无势垒的放热反应，放出的能量为132.2 kJ/mol。

I am accused of being overreligious," she said in her quiet, frank manner,"but that does not prevent me thinking the children very cruel who obstinately commit such suicide.""

客人们在卡罗利娜·埃凯家里，举止就文雅一些，因为卡罗利娜的母亲治家很严厉。

Designed by French fashion house Herm è s, this elegant uniform was manufactured in our home, Hong Kong, and was the first without a hat.

由著名品牌 Herm è s 设计，这件高贵的制服是香港本土制造，是我们第一套不配帽子的制服。