理论研究氧原子与富勒烯C60(Ih)的相互作用

运用密度泛函理论(DFT)方法,研究了异构体C60O[6,6]与C60O[5,6]之间的重排反应机理。结果显示: 它们之间的反应路径是经过一个过渡态没有中间体的一步反应。C60O[6,6] 转化成C60O[5,6]的反应能垒是42.7 kcal*mol-1,在反方向,C60O[5,6]转化成C60O[6,6]的反应能垒是47.3 kcal*mol-1,同时,扫描出氧原子在富勒烯C60(Ih)表面的势能面（PEC）,以详细显示异构体C60O[6,6]与C60O[5,6]之间的重排反应机理。     

理论研究氧原子与富勒烯C_(60)(Ih)的相互作用（英文）

运用密度泛函理论(DFT)方法,研究了异构体C_(60)O[6,6]与C_(60)O[5,6]之间的重排反应机理。结果显示:它们之间的反应路径是经过一个过渡态没有中间体的一步反应。C_(60)O[6,6]转化成C_(60)O[5,6]的反应能垒是42.7 kcal*mol~(-1),在反方向,C_(60)O[5,6]转化成C_(60)O[6,6]的反应能垒是47.3 kcal*mol-1,同时,扫描出氧原子在富勒烯C_(60)(Ih)表面的势能面(PEC),以详细显示异构体C_(60)O[6,6]与C_(60)O[5,6]之间的重排反应机理。     

氧化石墨烯负载的Pt单原子催化硼胺烷水解机理的理论研究（英文）

本文研究了氧化石墨烯负载Pt单原子(Pt_1/Gr-O)催化硼胺烷(NH_3BH_3)全水解反应机理,即一分子的NH_3BH_3生成三分子的氢气(H_2)的过程,在水解路径中,首先吸附的硼胺烷连续断裂两个B-H键生成第一分子的H_2.接着,一个H_2O分子与*BHNH_3基团(*表示吸附态)反应生成*BH(H_2O)NH_3,其中伸长的O-H键断裂后形成*BH(OH)NH_3.然后,第二个H_2O与*BH(OH)NH_3反应生成*BH(OH)(H_2O)NH_3,在指向Pt_1/Gr-O表面的O-H断裂后,生成BH(OH)_2NH_3并脱附到水溶液中,两个水分子脱氢产生的两个H原子脱附生成第二个H_2分子,且Pt_1/Gr-O催化剂恢复.脱附后的BH(OH)_2NH_3在水溶液中水解生成第三个H_2分子.纵观整个水解反应,H_2O分子和*BHNH_3基团的结合是反应速控步,其反应能垒是16.1 kcal/mol.因此,Pt_1/Gr-O有希望成为室温催化NH_3BH_3全水解催化剂.     

二水合丙氨酸复合体内的质子迁移和氢键迁移

采用B3LYP/6-31++G**方法研究了二水合丙氨酸复合体的结构和性质.找到3个质子迁移反应,相应的反应物都比产物稳定.质子迁移方式有"直接式"和"水桥式"两种.由于"直接式"质子迁移的逆反应是无垒过程,所以产物不能稳定存在,即"直接式"质子迁移反应难以发生;"水桥式"质子迁移反应能够存在,正逆反应能垒分别为6.47和1.43kcal·mol-1.体系中存在着水链参与的氢键迁移,正逆反应能垒分别为2.60和1.63kcal·mol-1.     

CH2和CH3分子在金属团簇Cun(n=1～6)上吸附性质

以σ-羟基环氧化合物作为模型化合物, 利用密度泛函中B3LYP/6-31G(d,p)的方法研究了三乙基铝促进的环氧化合物的重排还原有机串联反应机理. 根据乙烯消去和六元环重排顺序的不同可有两条可能的反应路径,路径I首先进行的是六元环的收缩重排,而且该步即决速步,能垒为116.62 kJ/mol;路径II中首先发生乙烯的消去然后进行六元环开环重排,开环反应步是该反应路径的决速步,相应的能垒为251.38 kJ/mol,如此高的能垒导致后续反应难于进行. 因此,路径I是更有利的反应路径,与实验结果一致.     

FeCl3催化2-(1-丙炔基)-2’-乙酰基联苯环化反应的机理研究

采用密度泛函理论的B3LYP方法研究了2-(1-丙炔基)-2’-乙酰基联苯分子内环化生成菲衍生物的反应机理。结果表明,该反应在无催化剂和FeCl3催化下均能通过四元环和八元环路径生成产物,其相应的决速步骤分别为四元环和八元环的生成过程。在无催化剂时,四元环路径和八元环路径的决速步骤的能垒相差仅6.8kJ·mol-1,两条路径为竞争反应。在FeCl3催化下,四元环路径决速步骤的能垒为137.52 kJ·mol-1,比八元环路径的低57.4 kJ·mol-1,为优势反应路径。该能垒比没有催化剂时低114.23 kJ·mol-1,表明FeCl3对于该反应具有强的催化作用,能够有效地提高反应速率,使反应在温和的条件下进行。     

FeCl3催化2-(1-丙炔基)-2’-乙酰基联苯环化反应的机理研究

采用密度泛函理论的B3LYP方法研究了2-(1-丙炔基)-2’-乙酰基联苯分子内环化生成菲衍生物的反应机理。结果表明,该反应在无催化剂和FeCl3催化下均能通过四元环和八元环路径生成产物,其相应的决速步骤分别为四元环和八元环的生成过程。在无催化剂时,四元环路径和八元环路径的决速步骤的能垒相差仅6.8kJ·mol-1,两条路径为竞争反应。在FeCl3催化下,四元环路径决速步骤的能垒为137.52 kJ·mol-1,比八元环路径的低57.4 kJ·mol-1,为优势反应路径。该能垒比没有催化剂时低114.23 kJ·mol-1,表明FeCl3对于该反应具有强的催化作用,能够有效地提高反应速率,使反应在温和的条件下进行。     

AuCl3催化炔酮分子内环化反应的机理

采用密度泛函理论的B3LYP方法研究炔酮发生分子内环化生成菲衍生物的反应机理.结果表明：在无催化剂和AuCl₃催化剂作用下,反应均可通过[2+2]和[6+2]途径生成产物.无催化剂时,两条途径控制步骤的能垒都较高,但是[2+2]途径的能垒比[6+2]途径的低32.01 kJ·mol^-1,故反应主要通过[2+2]途径进行.在AuCl₃催化作用下,反应的优势途径为[2+2]途径,其能垒为137.05 kJ·mol^-1.比较活化能发现,AuCl₃催化剂明显地降低了反应能垒,使反应能够顺利进行.     

铁(Ⅱ)异腈配合物与三甲基胺氮氧化物氧原子转移反应动力学及其机理研究

在CH2 Cl2 介质中研究了铁 (Ⅱ )异腈配合物 [FeL5(CN) ]Br(1 ,L = CNCH2 Ph)和trans [FeL4(CN) 2 ] (2 ,L = CNCH2 Ph)等与氧原子转移试剂 (CH3) 3NO的反应动力学行为 ,研究结果表明 :配合物 1与 (CH3) 3NO反应遵从二级速率定律 ,反应速率 =k2 [铁异腈配合物 ]× [(CH3) 3NO]。反应的活化熵ΔS≠ 和活化焓ΔH≠ 分别为- 2 5 34± 1 67cal·(mol·K) - 1 和 1 2 71± 0 49kcal·mol- 1 ,而配合物 2不与氧原子转移试剂反应。认为反应以缔合机理进行。     

三硝基甲烷键离解能和生成焓的理论计算

采用密度泛函(DFT)四种交换/相关函数(B3LYP、B3P86、B3PW91和PBE0)结合不同的基函数,求得了三硝基甲烷C-NO2键的离解能(BDE),并且通过合理选择参考物硝基甲烷,设计等键等电子对反应,计算了气相三硝基甲烷分子的生成焓(HOF).与实验数据进行比较,PBE0/6-31g*计算出的BDE值最好,误差为-2.1 kcal mol-1;PBE0密度泛函结合带极化函数的6-31g基组得到的HOF值与实验值吻合的最好(误差在0.1 kcal mol-1以内).     

Theoretical study of the [Si,C, P,O] potential energy surface

The structures, energetics, spectroscopies and stability of the doublet [Si, C, P, O] radical are explored at the density functional theory and ab initio levels. Eighteen isomers connected by 22 interconversion transition states are located at the DFT/B3LYP/6-311G(d) level. The structures of the kinetically stable isomers and the relevant transition states are further optimized at the QCISD/6-311G(d) level followed by CCSD(T)/6-311 + G(2df) single-point energy calculations. At the QCISD/6-311G(d) level, the lowest-lying isomer is the cyclic O-cCSiP 8 (0.0 kcal/mol) with considerable kinetic stability of 22.0 kcal/mol. In addition, two bent isomers OSiCP 1 (7.3 kcal/mol) and SiCPO 3 (34.7 kcal/mol) also possess considerable kinetic stability (more than 10.0 kcal/mol). As a result, three isomers 1, 3 and 8 are predicted to be possible candidates for future experimental and astrophysical detection. The bonding nature of the three isomers is analysed. The calculated results are compared with those of the analogous radical [Si, C, N, O]. Implications in the laboratory and interstellar space are also discussed. The predicted structures and spectroscopic properties are expected to be informative for the identification of [Si, C, P, O] in the laboratory and space.     

Theoretical studies on [2 + 2 + 2] reaction mechanisms of three ethynes. More accurate estimation of activation energy

The mechanisms of the [2 + 2 + 2] cycloaddition reaction of three ethyne molecules were studied by ab initio molecular orbital and density functional methods. The transition states range from that of the concerted mechanism with D_3h symmetry to that of the stepwise mechanism with C₂ symmetry. The transition state structure and the activation energy depend on the basis set and computational method employed in the analysis. The activation energy barrier was determined to be in the range of 36–44 kcal/mol. The activation energy determined by various methods corresponds to the interaction energy, which is related to the electron correlation energy. The best estimation of the activation energy barrier is 41.6 kcal/mol, achieved from the relation between the interaction energy and the activation energy. Copyright © 2013 John Wiley & Sons, Ltd.     

Theoretical studies of ethylene addition to transition metal compounds with carbene and oxo groups LnM(CH2)(O)

Quantum chemical calculations using density functional theory at the B3LYP level in combination with relativistic effective core potentials for the metals and TZ2P valence basis sets have been carried out for elucidating the reaction pathways of ethylene addition to MeReO₂(CH₂) ( C1 ). The results are compared with our previous studies of ethylene addition to OsO₂(CH₂)₂ ( A1 ) and OsO₃(CH₂) ( B1 ). Significant differences have been found between the ethylene additions to the osmium compounds A1 and B1 and the rhenium compound C1 . Seven pathways for the reaction C1 +C₂H₄ were studied, but only the [2+2]_Re,C addition yielding rhenacyclobutane C5 is an exothermic process with a high activation barrier of 48.9 kcal mol^?1. The lowest activation energy (27.7 kcal mol^?1) is calculated for the [2+2]_Re,C addition, which leads to the isomeric form C5 ′. Two further concerted reactions [3+2]_O,C, [3+2]_O,O, and [2+2]_Re,O and the addition/hydrogen migration of ethylene to one oxo ligand are endothermic processes which have rather high activation barriers (>35 kcal mol^?1). Four isomerization processes of C1 have very large activation energies of >65 kcal mol^?1. The ethylene addition to the osmium compounds A1 and B1 are much more exothermic and have lower activation barriers than the C₂H₄ addition to C1 . Copyright © 2007 John Wiley & Sons, Ltd.     

过氧硝酸分解势能面的理论研究

使用密度泛函理论B3LYP/6-311+ G(2d,2p)研究了过氧硝酸的最低能量结构．采用耦合簇方法CCSD(T)/aug-cc-pVDZ首次分别扫描了过氧硝酸沿氧-氮和氧-氧键的分解势能面．计算结果表明在氧-氮势能面上,当O3—N4键长是2.82 ?时,对应的疏松过渡态的能垒是25.6 kcal/mol;在氧$-$氧键的势能面上,当O2—O3键长是2.35 ?时,对应的疏松过渡态的能垒是37.4 kcal/mol．这表明过氧硝酸更容易分解为HO₂和NO₂．     

Absorption and diffusion of oxygen in the Ti<Subscript>3</Subscript>Al alloy

The absorption and diffusion of oxygen in the Ti₃Al alloy are studied by the projector augmented wave within the density functional theory. The highest absorption energies are shown to correspond to the sites in the octahedra formed by six titanium atoms, and the presence of aluminum in the nearest neighbors leads to a substantial decrease in the binding energy of oxygen in the alloy by approximately 1.5 eV. The energy barriers of oxygen diffusion between various interstices in the crystal lattice of the alloy are estimated, and the preferred migration paths in the (0001) plane and the [0001] direction are determined. It is found that the migration barrier from the most preferred octahedral O1 site to distorted tetrahedral Ti-site (2.42 eV) is a key barrier and limits the oxygen diffusion in the alloy. The calculated temperature diffusion coefficient of oxygen in the Ti₃Al alloy and the activation energies determined in two directions agree with the experimental data.     

Theoretical investigation on structures,stability and properties of [P,X, Y] (X=C,Si; Y = O,S) isomers

The structures, energetics and stability of the [P, X, Y] (X?=?C, Si; Y?=?O, S) radicals are explored by means of the density functional theory and ab initio levels. Seventeen [P, X, Y] isomers and 14 interconversion transition states are obtained at the B3LYP/6-311G(d) level. At the CCSD(T)/6-311?+?G(2df)//QCISD/6-311G(d)?+?ZPVE level, the lowest-lying isomers are the linear PCO 1a (0.0?kcal/mol), PCS 1b (0.0) and the three-membered ring cPSiO 1c (0.0), cPSiS 1d (0.0) on their respective potential energy surfaces. These four isomers exhibit considerably not only thermodynamic but also kinetic stabilities. Additionally, the cyclic cPCS 2b (32.8) and linear PSiS 2d (18.6) possess also high kinetic stability. All of six isomers 1a, 1b, 2b, 1c, 1d and 2d are considerably stabilized by a barrier of at least 20?kcal/mol, and may be detected in the laboratory or interstellar space. Their valence bond structures and possible formation strategies in the laboratory and space are discussed in detail. Finally, the similarities and discrepancies on structures and stabilities between [P, X, Y] (X?=?C, Si; Y?=?O, S) isomers are compared. These predicted results are highly expected to be informative for the future identification of [P, X, Y] (X?=?C, Si; Y?=?O, S) in the laboratory and space.     

Theoretical study on the mono and multiply oxygenated Si60H60 fullerene

We have applied density functional theory (DFT) calculations to study the structures, stabilities, electronic and magnetic properties of mono and multiply oxygenated Si₆₀H₆₀ fullerenes (Si₆₀H_60–2nO_n, n = 1, 3, 6, 9, 10, 12, 18, 20, 21, 27 and 30). DFT results show that rearrangement between the closed [6,6] and [5,6] isomers of Si₆₀H₅₈O follows a two-step pathway involving an intermediate and two transition states. Preserving the C₃ symmetry in the cage structure, extra epoxidation of Si₆₀H₆₀ has been accomplished. Based on our results, formation energies per oxygen atom for the multiple additions of oxygen atoms on Si₆₀H₆₀ cage are positive (endothermic character), and increase with the increasing of the number of oxygen atoms. In general, the oxygenation of Si₆₀H₆₀ cage leads to an increase in the electrophilicity of the Si₆₀H_60–2nO_n oxides. The oxygenation of Si–Si bonds not only introduces a substantial broadening of the NMR pattern but also yield individual peaks, indicating different electrostatic environments of silicon nuclei in the Si₆₀H_60–2nO_n oxides.     

C78O异构体的电子结构和光谱

为了模拟C78单加成物的加成位置和稳定性,并预测其光谱性质,用INDO系列方法对基于C2v-C78之上的C78O所有可能的34个异构体结构和电子光谱进行理论研究．结果表明,C78O的最稳定异构体是O加在位于C2v-C78短轴上的73,78-键上且形成环氧结构的6／6异构体,O的原子轨道对73,78-C78O中的HOMO能量降低起重要作用．讨论了电子跃迁性质和73,78-C78O电子光谱的长波吸收峰与母体相比发生蓝移的原因．