【作者】 方冉；

【导师】 耿志远；

【作者基本信息】 西北师范大学 ， 无机化学， 2006， 硕士

【摘要】 本研究论文是采用量子化学理论和计算方法，对亚烷基卡宾与环氧乙烷、环硫乙烷的氧、硫转移反应机理和锗烯与环硫乙烷的硫转移反应机理，亚烷基卡宾与甲醇的插入反应机理进行了系统的理论计算研究。为了解上述有机活性中间体反应过程和机理提供了理论基础，进一步为实验研究提供了理论依据。全文共分六章。第一章介绍了亚烷基卡宾，锗烯等有机活性中间体反应的研究进展。第二章概述了本文工作的量子化学理论背景和计算方法。第三章用量子化学的密度泛函理论（DFT）在6-311G（d，p）水平上对亚烷基卡宾及取代亚烷基卡宾与环氧乙烷的氧转移反应机理进行了系统的研究。用IRC对过渡态进行了确认。并用组态混合模型讨论了反应势垒（ΔE^≠）与XYC=C的单-三态能量差ΔE_ST之间的关系。结果表明：取代基的电负性是控制反应的主要因素，取代基的电负性越大，取代基越多，π电子给予体越多，单-三态能量差ΔE_ST就越小，该反应的活化能就越小，反应越容易发生。同时还研究了该反应中环氧乙烷中C-O键的解离过程。发现两个C-O键解离是一个不同步的协同过程。第四章用量子化学的密度泛函理论（DFT）在6-311G（d，p）水平上对亚烷基卡宾及取代亚烷基卡宾与环硫乙烷的硫转移反应机理进行了系统的研究。用IRC对过渡态进行了确认。并用组态混合模型讨论了反应势垒（ΔE^≠）与XYC=C的单-三态能量差ΔE_ST之间的关系，结果表明，取代基的电负性是控制反应的主要因素，取代基的电负性越大，取代基越多，π电子给予体越多，单-三态能量差ΔE_ST就越小，该反应的活化能就越小，反应越容易发生。同时还讨论了该反应中环硫乙烷的C-S键的解离过程。发现亚烷基卡宾与环硫乙烷硫转移反应与环氧乙烷的氧转移反应不同，是一个同步的协同反应。第五章用量子化学的密度泛函理论（DFT）在6-311G（d，p）水平上对亚烷基卡宾及取代亚烷基卡宾与甲醇的插入反应机理进行了系统的研究。结果表明，该类插入反应很容易生成乙烯醚，而且单取代的亚烷基卡宾将生成顺式和反式的混合物。反应活性顺序依次为：HFC=C＞HClC=C＞HBrC=C＞H（CH₂）C=C＞H₂C=C。第六章利用量子化学密度泛函理论的B3LYP方法，在6-311++G（d，p）的水平上对锗烯X₂Ge（X=H、CH₃、F、Cl、Br、OH、OCH₃）与SC₂H₄的硫转移反应进行了计算研究。结果表明，锗烯的基态是单重态，取代基的电负性越强，单-三态的能量差越大：反应的活化能越高，放热越少；控制反应的因素是电子效应，而不是立体效应；该硫转移反应由两步组成，第一步生成中间配合物，是一个无势垒的放热过程，第二步经过渡态生成产物。并用组态混合模型对反应机理和势垒进行了解释。同时讨论了该反应中环硫乙烷的C-S键解离过程。更多还原

【Abstract】 In this paper, high-level quantum chemistry calculation methods are used to theoretically investigate on the potential energy surfaces of some alkylidenecarbenes with oxirane, thiirane, methanol and the abstraction reactions of germylene with thiirane and oxirane. Much kinetic information of these reactions was obtained. The results presented in this paper may be very helpful for understanding the reactions of active intermediate and may provide some elemental theoretical basis for futher experiments on active intermediate reactions. The whole paper consists of six chapters.Chapter 1 mainly reviews the evolution of alkylidenecarbenes and germylenes reactions. The second chapter summarizes the theory of quantum chemistry and calculation methods of this paper.In the third chapter, the mechanisms for the abstraction reactions of alkylidenecarbenes with oxirane have been characterized in detail by density functional theory. The results show that the electro negativity of the substituents played an important role to predict its activity for the abstraction reactions. The major conclusion was that the stronger the p-donation or the more electronegative the substituents were, the smaller the△E_ST of XYC=C: and the lower the activation energy for the abstraction reactions. In other words, it is the electronic factors, rather than the steric ones, that play a decisive role in the chemistry of the alkylidenecarbene species.In the fourth chapter, the mechanisms for the abstraction reactions of alkylidenecarbenes with thiirane have been characterized in detail using density functional theory. The results show that the electro negativity of the substituents played an important role to predict its activity for the abstraction reactions. The major conclusion showed: the more strong the p-donation or the more electro negativity the substituents were the smaller the△E_ST of XYC=C and the lower the activation energy for the abstraction reactions. In the other words, it is the electronic factors, rather than the steric factors, that play a decisive role in the chemistry of the alkylidenecarbene species. Furthermore, a comparison with oxirane led also to the same result.In the fifth chapter, the mechanisms for the insertion reactions of alkylidenecarbenes with CH₃O-H have been investigated at the B3LYP/6-311G （d, p） level of the theory. According to our model calculations these insertion reactions will easily yield vinyl ether products and for a given single substituted alkylidenecarbene will yield cis-/trans- isomer mixture. Moreover the reactivity of alkylidenecarbene decreases in the order: HFC=C > HC1C=C > HBrC=C> H（CH₃）C=C> H₂C=C.In the sixth chapter, the potential energy surfaces for the abstraction reactions ofgermylene with thiirane have been characterized in detail using deasity functional theory （DFT）. The major conclusion is as follow: the reactions are in two steps: （1） germylenes and thiirane form an intermediate complex through exothermal reactions without any barrier; （2） the intermediate complexes isomerize to give the products. Furthermore, the stronger the p-donation is or the more electronegative the substituents are the bigger the△E_ST of X₂Ge, The higher the action energy for the abstraction reactions will be.更多还原