【作者】 张旭；

【导师】 陈晓丹；

【作者基本信息】 暨南大学 ， 化学工程（专业学位）， 2020， 硕士

【摘要】 小分子活化目前是化学领域的一大热点,很久以来,人们认为只有双亲性的过渡金属（TM）配合物可以活化小分子,由于其同时具有被电子占据和空的d轨道,能分别与小分子的反键轨道和成键轨道作用,迫使小分子的键断裂来激活小分子;然而,最近一些研究已经证明了具有开壳结构的主族元素也能像TM配合物类一样的活化小分子。其中典型的有主族元素双自由基化合物,这些化合物具有未成键电子或存在某些活泼π电子,同时一些主族元素具有和TM一样的d轨道,用来接受小分子化学键中σ轨道的电子,倾向与小分子发生氧化加成反应。许多双自由基不仅与小分子如H₂、NH₃、CO₂等反应,而且还可以作为高效的有机催化剂,为小分子的活化开辟了新的去金属化的反应路径。本文用P₂C₂四元杂环双自由基和水、丙二腈、对乙腈苯胺、碘甲烷、碘乙烷等12种小分子化合物进行氧化加成反应,并对其E-H（E=C,N,O）键和R-X（R=烷烃,X=卤素）键活化的机理进行研究。以下为论文各章的简介:第一章综述了双自由基的化学性质、不同类型的四元杂环双自由基及其在活化小分子中应用。1:四元杂环双自由基的研究与进展;2:四元杂环双自由基在活化小分子中的应用和讨论;第二章的工作中,我们通过之前工作中分离出一种NHC（氮杂环卡宾）稳定6π电子L→（C₂P₂）?L(L=NHC=1,3-二（2,6-二异丙基苯基氮杂环卡宾）四元杂环双自由基化合物1与小分子进行氧化加成反应,通过底物诱导,当底物靠近化合物1时,由于分子间电子相互作用,导致双自由基化合物1中的π电子发生波动,使两个在基态等价的P原子不再等价,从而表现出以P原子为中心的亲核性和亲电性。在N-杂环卡宾稳定的双自由基化合物1中,与具有极性E-H键（E=C,N,O）的小分子底物相互作用,生成一系列不对称的1,3-二磷酸骨架(含P-C（2-2）、P-N（2-6和2-7）和P-O键（2-8b、2-8c和2-9）。此外通过与（[（CN）₂CH]^–（2-3）和[（Ph OH）₂Ph O]^–（2-10））弱配位也得到了1,3-二膦酸盐。我们通过核磁共振波谱、X射线衍射、紫外可见光谱,红外光谱等进行表征,核磁和单晶数据表明小分子与双自由基化合物1反应会有顺反异构体产生,并且我们根据密度泛函理论（DFT）计算,对其反应机理进行了研究。第三章的工作中,我们用四元杂环双自由基化合物1与含R-X键（R为烷基,X为卤素I原子）的小分子进行氧化加成反应。化合物1与Me I、Et I、1-碘-2-甲基丙烷和2-碘-2甲基丙烷反应,分别得到对应化合物3-3a、3-3b、3-3c和3-4。反应结果是R-X键断裂,R加成在化合物1四元环中的一个P原子上,形成R（LPC）₂⁺阳离子和X^-阴离子。我们通过核磁、红外、紫外及单晶等表征数据对产物的化学性质进行分析,并且通过DFT计算对其反应中过渡态的电子转移进行理论研究。更多还原

【Abstract】 Currently,activation of small molecules is a hot topic in chemistry.For a long time,it was believed that only amphiphilic transition metal（TM）coordination compounds can activate small molecules,because they have both electron-occupied and empty d-orbits that can make strong bonds fracture to activate small molecules.However,some recent studies have demonstrated that biradicaloids with main-group elements also have similar activation functions as TM coordination compounds.These free radicals have unbonded electrons or some activeπelectrons.Meanwhile,some main-group elements,having the same d orbits as TM,are used to receive electrons ofσorbits in the chemical bonds of small molecules,and inclined to trigger fracture and addition reaction of small molecules.Many biradicaloids not only react with such small molecules as H₂,NH₃,CO₂,etc.,but also can be used as high-performance organic catalysts,opening up new fields for activation of small molecules.In this thesis,P₂C₂four-membered heterocyclic biradicaloid was used for the oxidative addition reaction with 12 small molecules such as water,malonic nitrile、P-acetonitrile aniline,methyl iodide and ethyl iodide,and the mechanism of activating E-H（E=C,N and O）bond and R-X（R=alkane,X=halogen）bond was studied.A brief introduction of each chapter of the thesis is as follows.The first chapter is an overview of the chemical properties of biradicaloids,different types of four-membered heterocyclic biradicaloid and their application in activation of small molecules.1.Study and development of four-membered heterocyclic biradicaloid;2.Application of four-membered heterocyclic biradicaloids in activation of small molecules and relevant discussions;In Chapter 2,we separated a type of NHC（N-heterocyclic carbene）in previous efforts to stabilize 6πelectron L→（C₂P₂）?L(L=NHC=1,3-di（2,6-diisopropylphenylimino N-heterocyclic carbene）,four-membered heterocyclic biradicaloid compound 1 to realize oxidative addition with small molecules.When the substrate approached compound 1 through substrate induction,inter-molecular electronic interaction led to fluctuation ofπelectron in compound 1,making the two P atoms equivalent in ground state no longer equivalent and thereby showing nucleophilicity and electrophilicity centering on P atoms.In the biradicaloid compound 1 containing stable N-heterocyclic carbene,it interacted with a small molecule substrate with a E-H bond（E=C,N,O）of polarity to generate a series of asymmetric 1,3-diphosphates skeleton(including P-C（2-2）,P-N（2-6 and 2-7）and P-O bond（2-8b,2-8c and 2-9）.Besides,1,3-diphosphates salt was also obtained through weak coordination with（[（CN）₂CH]^–（2-3）and[（Ph OH）₂Ph O]^–（2-10））.Nuclear magnetic resonance（NMR）spectrum,diffraction of x-rays,UV-visible spectroscopy,and infrared spectroscopy（IR）were used for characterization,while NMR and single crystal data indicated that small molecules will react with compound 1 to produce cis-trans isomers,and the reaction mechanism were studied based on density functional theory（DFT）calculation.In Chapter 3,we used compound 1 to realize oxidative addition reaction with small molecules containing R-X bond（R refers to alkyl while X refers to halogen I atom）.Compound1 reacted with Me,Et I,1-iodo-2-methylpropane and 2-iodo-2-methylpropane and obtained corresponding compounds 3-3a、3-3b、3-3c and 3-4 respectively,which lead to fracture of R-X bond,R being added to one of the P atoms on the four-membered rings in Compound 1,forming R（LPC）₂⁺cation and X^-negion.Characterization data,including NMR,infrared,ultraviolet and monocrystal,were used to analyze the chemical properties of the products and theoretically study the electron transfer of the transient state in the reaction through mechanical calculation.更多还原