Rh的芳基化合物与含氮芳基卤代物交叉偶联反应机理研究

利用密度泛函理论(DFT)研究了Rh的芳基化合物与含氮芳基卤代物交叉偶联过程催化循环的微观反应机理。在B3LYP/6-31+G(d) 基组水平上(Rh、I采用了赝势基组LanL2DZ)优化了反应过程中所有化合物的几何构型并计算了频率，通过能量、频率和振动方式确定了中间体和过渡态的真实性。此外，在同等基组水平上还运用了分子中的原子理论讨论了成键临界点的电荷密度的变化，运用了自然键轨道理论讨论了键的性质与轨道间的相互作用。为了提高计算精度, 在6-311++G(d,p) 基组水平上计算了反应机理中所有物质在气相及溶剂化下的单点能, 得到与 6-31+G(d) 基组计算相同的结论。结论表明Rh(Ⅰ)起到了有效的催化作用，且计算所得结论与实验结果相符合。     

Rh的芳基化合物与含氮芳基卤代物交叉偶联反应机理研究

利用密度泛函理论(DFT)研究了Rh的芳基化合物与含氮芳基卤代物交叉偶联过程催化循环的微观反应机理.在B3LYP/6-31+G(d)基组水平上(Rh、I采用了赝势基组Lan L2DZ)优化了反应过程中所有化合物的几何构型并计算了频率,通过能量、频率和振动方式确定了中间体和过渡态的真实性.此外,在同等基组水平上还运用了分子中的原子理论讨论了成键临界点的电荷密度的变化,运用了自然键轨道理论讨论了键的性质与轨道间的相互作用.为了提高计算精度,在6-311++G(d,p)基组水平上计算了反应机理中所有物质在气相及溶剂化下的单点能,得到与6-31+G(d)基组计算相同的结论 .结论表明Rh(Ⅰ)起到了有效的催化作用,且计算所得结论与实验结果相符合.     

二聚物X2 和 XK (X= Mn, Fe, Co, Ni, Cu)吸附NO的密度泛函理论研究

为有效降低NO对环境以及人体造成的危害,着重从催化剂入手,研究过渡金属Mn₂, Fe₂, Co₂, Ni₂, Cu₂及K掺杂的MnK, FeK, CoK, NiK, CuK的二聚物对NO的吸附性能.采用密度泛函理论的B3LYP, B3PW91, B3P86, B1B95以及PBE1PBE方法结合LANL2DZ, SDD, CEP-121G基组,采用B3LYP, B3PW91, B3P86以及PBE1PBE方法结合6-31++G(3df, 3pd), 6-311++G(3df, 3pd), 6-31G(d, p), LANL2DZ, SDD基组分别系统研究了X₂和XK (X=Mn, Fe, Co, Ni, Cu)团簇和NO的几何结构,计算出其键长,频率,离解能,再与对应的实验值进行对比.进一步采用PBE1PBE方法结合LANL2DZ和6-31G(d, p)基组研究了X₂NO和KXNO团簇的几何结构,计算出各原子间键长和吸附能.结果表明,...     

CuCl催化下苯炔与环己烯乙炔偶联反应机理的理论研究

利用密度泛函理论(DFT)研究了Cu Cl催化下苯炔与环己烯乙炔偶联反应的微观反应机理.在B3LYP/6-31+G*基组水平上(Cu采用了赝势基组Lan L2DZ)优化了反应过程中所有化合物的几何构型并计算了频率,通过能量、频率和振动方式确定了中间体和过渡态的真实性.此外,在同等基组水平上还运用了分子中的原子理论讨论了成键临界点的电荷密度的变化,运用了自然键轨道理论讨论了键的性质与轨道间的相互作用.为了提高计算精度,在6-311+G*基组水平上计算了反应机理中所有物质在气相及溶剂化下的单点能,得到与6-31+G*基组计算相同的结论.结论表明Cu Cl对苯炔与1-乙炔基环己烯偶联反应起到了有效的催化作用,且计算所得结论与实验结果相符合.     

金属Pt表面氢同位素解离吸附的热力学研究

基于电子与振动近似方法和密度泛函B3LYP理论,对氢原子采用6-311G"基函数,Pt选择赝势基组LanL2DZ,优化得到Pt-H和Pt-H2结构和微观性质,Pt-H分子平衡键长和谐振频率分别为0.1528nm和2336cm-1,与实验值一致.氢气分子吸附于Pt表面反应的Gibbs自由能⊿G0为正值,远大于解离反应⊿G0值,氢气在Pt表面不能以完整分子形式与Pt结合,易于解离成氢原子.计算了氢同位素在Pt表面解离反应的⊿S0,⊿H0,⊿G0和平衡压力,并导出它们与温度的关系.由⊿G=0kJ.mol-1计算得0.1MPa时H2,D2和T2的脱附温度分别为962K,919K和892K,大多数反应Pt-H(D或T)都能稳定存在.     

聚对苯二甲酸丁二醇酯二聚体键离能的理论研究

采用密度泛函理论方法对聚对苯二甲酸丁二醇酯(PBT)二聚体的键离能进行了计算.为了选取较为精确的方法来计算PBT各个键的键离能,以与PBT具有相同的酯基官能团的乙酸乙酯为模型参照物.采用M062X, B3P86, M06, PBE0, wB97xD方法分别在基组6-31G(d), 6-311G(d), 6-311+G(d, p), 6-311++G(d, p), cc-pVDZ, cc-pVTZ水平下对乙酸乙酯的键离能进行计算.通过对比计算结果与iBonD数据库的乙酸乙酯实验测定值可知,M062X在基组6-311G(d)水平下计算结果与实验值最为接近.因此,本研究采用M062X方法在基组6-311G(d)水平下对聚对苯二甲酸丁二醇酯(PBT)二聚体的键离能进行计算.计算结果表明：在PBT的各键中C-C_arcmatic键的键离能最大,主链上的C-C键离能最小,为370.9 kJ/mol.其次就是C-O键,为404.6 kJ/mol.基于PBT键离能的计算结果,设计了3条PBT二聚体热降解过程可能形成的反应路径,分析了热解产物的形成机理.结果表明PBT二聚体热解过程可...     

脂肪胺水溶液吸收CO2的热力学参数的密度泛函理论研究

采用密度泛函理论研究CO₂在脂肪胺水溶液热力学参数．研究的脂肪胺包括烷基胺、链烷醇胺、二胺以及氨基酰胺．在B3LYP/6-311+ G(d,p)水平计算脂肪胺在CO₂气相中的振动频率．通过连续介质模型在HF/6-31G(d)水平计算了溶剂几何优化的标准自由能,评价了CO₂吸收到脂肪胺水溶液过程有关的两个重要参数：酸解离常数和标准焓变二者之间大致呈线性关系．随着胺碱度的提高,CO₂吸收过程释放的热量增加,则胺再生所需的能量增加．     

Theoretical Study of the C-Cl Bond Dissociation Enthalpy and Electronic Structure of Substituted Chlorobenzene Compounds

利用密度泛函(DFT)三种交换/相关函数(B3LYP, B3PW91,B3P86)结合6-31G**和6-311G**基组,计算了13个取代氯苯化合物的键离解能. 结果表明B3P86/6-311G**方法是计算取代氯苯化合物键离解能的可信方法,研究发现C-Cl键的键离解能与所使用的基组和计算方法密切相关,取代基对C-Cl键的键离解能的影响不明显. 研究了目标化合物的前线轨道能级差,并对取代氯苯化合物的热稳定性做了评估.     

吩噻嗪表面增强拉曼光谱的密度泛函理论研究

吩噻嗪是含有N、S的杂环化合物,具有大的离域π键。用Gaussian 09程序,在B3LYP方法下,Ag原子使用LANL2DZ赝式基组,C、H、N、S等原子使用6-31++G(d,p)基组,优化并计算了吩噻嗪和吩噻嗪银配合物(PTH-Ag)的拉曼光谱,并利用GaussianView对PTH分子进行归属,为食品和产品中吩噻嗪残留的定性、定量测定提供理论依据。计算结果说明连接Ag原子越多,增强效果越明显。     

CuCl催化苯腙和丙炔酸甲酯Michael加成反应的机理研究

本文采用密度泛函理论(DFT)中的M05方法针对性的研究了以CuCl为催化剂催化苯腙和丙炔酸甲酯发生Michael加成的微观反应机理.采用Gaussian09程序,使用6-31+G*(Cu采用赝势基组LanL2DZ)对化学反应过程中的反应物、中间体、过渡态分子的几何构型进行了优化,同时进行了频率计算,所有过渡态都有唯一虚频,中间体和过渡态分子结构的合理性得到了确认.通过自然键轨道(NBO)理论分析了分子轨道间的相互作用.通过理论计算发现CuCl催化苯腙和丙炔酸甲酯发生Michael加成反应的位点在苯腙的N原子上,反应的速控步骤活化能为34.86 kcal/mol,相关的理论研究结果与实验反应现象相吻合.     

吸附分子间通过底物的作用能的密度泛函理论计算

尝试用密度泛函理论B3LYP方法,计算研究了Ag(111)面上烷烃硫醇自组织单分子层中分子间通过底物的作用能(间接作用能)的大小,揭示了它与单体吸附能绝对值的正比关系,阐明了其物理本质．DFT的计算结果与以前提出的间接作用能的半经验表达式定性一致．     

Cadmium–carbon wavenumber analysis using B3LYP level theory calculations in investigations of dimethylcadmium decomposition

Computational chemistry has been widely used to understand homogeneous reactions and to support spectroscopy analysis. Thus, it is a useful tool to understand gas‐phase dynamics of metal organic chemical vapor deposition (MOCVD). In this study, we report that the basis set selection possibly results in unequivocal peak assignment in Raman spectroscopy, especially when an effective core potential (ECP) is employed. The basis set selection for the decompositionof dimethylcadmium (DMCd), for example, was examined using five different ECPs (i.e. CRENBS, CRENBL, SDD, LanL2DZ and SBKJC for Cd atom combined with STO‐3G, 3‐21G, 6‐31G(d), 6‐311G(d) and 6‐311++G(2d,2p) for C and H atoms). The analyses demonstrated that the SDD/STO‐3G/3‐21G combination for Cd/C/H atoms best reproduce the experimentally reported Cd C vibrational stretching modes of Cd(CH₃)₂ (DMCd) and •CdCH₃ (MMCd). Although the SDD/STO‐3G/3‐21G combination consists of simple and basic basis sets, we found that a good potential balance between metal (Cd) and auxiliary (C) atoms is essential to estimate frequencies suitable for spectroscopy analysis computationally. The same combination of basis set was then used to examine other possible reaction steps, and Raman experiments successfully detected one of the suggested intermediates of (CdCH₃)₂. Copyright © 2009 John Wiley & Sons, Ltd.     

ONIOM方法计算胺和二芳基碳正离子的亲核反应的速率常数

利用第一性原理计算了胺和二芳基碳正离子的亲核反应的速率常数. 研究不同的溶剂化模型(PCM、CPCM和COSMORS)、不同类型的原子半径(UA0、UAKS、UAHF、Bondi和UFF)、以及一些单点能计算方法(B3LYP、B3P86、B3PW91、BHANDH、BMKPBEPBE、M06、MP2和ONIOM)在计算这类速率常数时的表现.通过比较速率常数的实验值和计算值,发现ONIOM(CCSD(T)/6-311++G(2df,2p):B3LYP/6-311++G(2df,2p))//B3LYP/6-31G(d)/PCM/UFF方法表现最好. 该方法随后被用于计算更多的胺和二芳基碳正离子的亲核反应的速率常数. 65个反应的速率常数的实验值和计算值之间表现出了相当好的相关性,这表明该方法适用于计算胺二芳基碳正离子的亲核反应的速率常数.     

Theoretical investigations of the gas phase reaction of limonene (C10H16) with OH radical

The rate coefficients of hydroxyl radical (OH) reaction with limonene were computed using canonical variational transition state theory with small-curvature tunnelling between 275 and 400 K. The geometries and frequencies of all the stationary points are calculated using hybrid density functional theory methods M06-2X and MPWB1K with 6-31+G(d,p), 6-311++G(d,p), and 6-311+G(2df,2p) basis sets. Both addition and abstraction channels of the title reaction were explored. The rate coefficients obtained over the temperature range of 275–400 K were used to derive the Arrhenius expressions: k(T) = 4.06×10^?34 T^7.07 exp[4515/T] and k(T) = 7.37×10^?25 T^3.9 exp[3169/T] cm³ molecule^?1 s^?1 at M06-2X/6-311+G(2df,2p) and MPWB1K/6-311+G(2df,2p) levels of theory, respectively. Kinetic study indicated that addition reactions are major contributors to the total reaction in the studied temperature range. The atmospheric lifetime (τ) of limonene due to its reactions with various tropospheric oxidants was calculated and concluded that limonene is lost in the atmosphere within a few hours after it is released. The ozone production potential of limonene was computed to be (14–18) ppm, which indicated that degradation of limonene would lead to a significant amount of ozone production in the troposphere.     

Pt_(10)团簇催化肉桂醛选择性加氢反应机理的研究

本文以Pt_(10)团簇作为催化剂模型,采用密度泛函理论(DFT)中的B3LYP方法,在6-31+G(d)(Pt采用贗势基组Lanl2dz)基组水平上,探讨了Pt_(10)团簇催化肉桂醛选择性加氢反应的微观反应历程.研究结果表明,Pt_(10)团簇催化肉桂醛选择性加氢反应可生成3种不同的产物,分别是3-苯基丙醛(P1)、3-苯基丙烯醇(P2)和肉桂醇(P3),每种产物分别通过两条不同的反应通道而得到.Pt_(10)团簇催化有利于肉桂醛分子中C=O键活化加氢.这点与实验结果一致.     

Is the (hfac)Cu(I)–(tmvs) bond intrinsically weak?

Density functional theory studies were performed to study the structure and bonding of (hexafluoroacetylacetonate)-copper(I)-(trimethylvinylsilane) [Cu(hfac)(tmvs)], an ideal and important Cu(I)-CVD compound. A popular three-parameter hybrid density functional (B3LYP) with 6-311+G(d,p) and an effective core potential included LanL2DZ basis set was utilized for this purpose. The (hfac)Cu–(tmvs) bond energy of approximately 30?kcal?mol^?1 obtained at the B3LYP/6-311+G(d,p) level of theory reveals that the Cu–olefin bond in Cu(hfac)(tmvs) is not as weak as previously estimated/assumed and, hence, that the substrate plays a vital role in copper film formation from Cu(hfac)(tmvs). Bonding analysis reveals that fairly strong (hfac)Cu–(tmvs) bonding is the result of DCD-model σ-donation and π-back-bonding between the copper and tmvs in Cu(hfac)(tmvs).     

Mechanistic and kinetics study of the gas phase reactions of methyltrifluoroacetate with OH radical and Cl atom

Theoretical investigations are carried out on the title reactions by means of ab initio and DFT methods. The optimized geometries, frequencies and minimum energy path are obtained at MPWB1K/6-31+G(d,p) level. Single point energy calculations are performed at MP2 and QCISD(T) levels of theory. Energetics were further refined by calculating the energy of the species with a high level G2(MP2) method. The rate constant of the two reactions are calculated at 298?K and 1?atm using Canonical Transition State Theory (CTST) utilizing the ab initio data obtained during the present study. The rate constant values are found to be 5.5?×?10^?14 and 5.9?×?10^?14?cm³ molecule^?1 s^?1, respectively which are in good agreement with the experimental data.     

Design and Synthesis of a Pyridine Based Chemosensor: Highly Selective Fluorescent Probe For Pb2+

A pyridine based imine-linked chemosensor has been synthesized and evaluated its binding affinity with library of transition metal ions. It has prominent selectivity towards Pb²⁺ among other metal ions in DMF/H₂O (9:1, v/v) solvent system. The 1:1 stoichiometric was confirmed by job’s plot and has a binding constant (K_a)?=?5.142?×?10³ M^?1 on fluorescence. A B3LYP/6-31G and B3LYP/LanL2DZ basis sets were employed for optimization of 3 and 3.Pb²⁺.     

(1,2-μ2-L1)(1,2-μ2-L2)十羰基合三锇振动光谱的理论计算[L1, L2=H, Cl, Br, I]

用密度泛函理论和从头计算(abinitio)方法,在B3LYP CEP 4G ,B3LYP LanL2DZ和RHF CEP 4G ,RHF LanL2DZ水平上,全优化计算了(1,2 μ2 H) (1,2 μ2 L)Os3(CO) 1 0 (L :Cl,Br,I)的分子几何构型和电子结构;在RHF CEP 4G水平上,全优化计算了(1,2 μ2 L) 2 Os3(CO) 1 0 (L :H ,Cl,Br,I)的分子几何构型和电子结构。计算结果表明,在这些体系中,电子由Os(CO) 3向Os(CO) 4转移。用RHF CEP 4G对这七个簇合物进行了简正振动频率分析,在计算得到振动频率及吸收强度的基础上,模拟了稳定平衡结构的红外光谱图,并对计算结果进行了比较和讨论。     

AunLa(n=1~8)团簇的密度泛函研究简

采用密度泛函理论(DFT)中的杂化密度泛函B3LYP方法,在LANL2DZ基组水平上研究了Aun La(n=1~8)团簇的几何结构.计算并讨论了基态结构稳定性及电子性质.结果表明,当n=3-8时,基态结构均为三维结构且La原子趋向与更多的Au原子结合.团簇二阶能量差分,能隙和化学硬度计算结果显示除了AuLa外,具有偶数数目的团簇比奇数数目的团簇具有更好的稳定性,其中,Au3La团簇的稳定性相对较好.