CX2+CH2O (X=F, Cl, Br)环加成反应的密度泛函理论计算

用密度泛函理论,在B3LYP/6-311 G(d)水平上研究了CX2 CH2O(X=F,Cl,Br)环加成反应一条三过渡态三中间体路径的反应机理,全参数优化了反应势能面各驻点的几何构型,用内禀反应坐标(IRC)和频率分析方法,对过渡态进行了验证.用高级电子相关校正的耦合簇[CCSD(T)/6-311 G(d)]方法对优化构型进行了单点能计算.采用经Wigner校正的Eyring过渡态理论和热力学方法,研究了该反应通道的热力学及动力学性质.从热力学和动力角度综合分析,该途径CF2与GH2O的环加成反应难以发生,而CCl2及CBr2与CH2O反应的适宜温度范围均为400～1000K,如此,反应既具有较大的自发趋势和平衡常数,又具有较快的反应速率.     

钐(Ⅱ)类卡宾CH3SmCH2X(X=Cl、Br和I)促进乙烯环丙烷化反应途径的理论研究

用密度泛函B3LYP方法研究了过渡金属钐类卡宾与乙烯的环丙烷化反应的机理.对三种不同的钐的SS试剂CH3SmCH2X(其中X=Cl、Br和I)分别和CH2CH2反应的各反应物、中间体、过渡态和产物构型的全部结构几何参数进行了优化,用内禀反应坐标(IRC)计算和频率分析方法,对过渡态进行了验证.结果表明:CH3SmCH2X(其中X=Cl、Br和I)与CH2CH2环丙烷化反应按亚甲基转移通道(通道A)和卡宾金属化通道(通道B)都可以进行,与锂类卡宾的反应机理相同,只是按亚甲基转移通道(通道A)进行反应较容易一些,而且此反应在较低的温度下就可以发生.     

二溴卡宾与CH3OH多通道反应的理论计算

对单、三重态CBr2与CH3OH的多通道反应进行了理论计算. 在b3lyp/6-311g*水平上优化了势能面上构型并进行了构型确认. 计算了各物种经零点能校正的CCSD(T)能量. 结果表明, 单重态CBr2既可以与O－H键插入生成1,1-二溴代甲醚P1 (CH3OCHBr2), 也可以与C－H键插入生成2, 2-二溴代乙醇P3(Br2HCCH2OH). 同时, 存在单重态CBr2与CH3OH抽提双氢生成Pabs(CH2O+CH2Br2)的反应. 采用统计热力学及Wigner校正的Erying理论研究了主反应通道的热力学及动力学性质, 并对反应通道上的关键点进行了NBO和AIM分析.     

二溴卡宾与CH3OH多通道反应的理论计算

对单、三重态CBr2与CH3OH的多通道反应进行了理论计算. 在b3lyp/6-311g*水平上优化了势能面上构型并进行了构型确认. 计算了各物种经零点能校正的CCSD(T)能量. 结果表明, 单重态CBr2既可以与O－H键插入生成1,1-二溴代甲醚P1 (CH3OCHBr2), 也可以与C－H键插入生成2, 2-二溴代乙醇P3(Br2HCCH2OH). 同时, 存在单重态CBr2与CH3OH抽提双氢生成Pabs(CH2O+CH2Br2)的反应. 采用统计热力学及Wigner校正的Erying理论研究了主反应通道的热力学及动力学性质, 并对反应通道上的关键点进行了NBO和AIM分析.     

N(4S)+CH3X(X=Cl、Br)反应机理的理论研究

利用abinitio方法对N(4S)+CH3X(X=Cl、Br)反应进行了理论研究,在MP2/6311+G(d,p)水平上优化得到了反应途径上的反应物、过渡态和产物的几何构型和谐振频率,在MP2/6311++G(3df,2p)和QCISD(T)/6311+G(d,p)水平上进行单点能计算,并用G2MP2方法计算了所有物种的能量.计算结果表明,反应存在三条反应通道:H抽提反应通道a、Cl或Br抽提反应通道b和替代反应通道c.对于N(4S)+CH3Cl反应,a反应通道是主反应通道,b和c反应通道在反应中有少量贡献.对于N(4S)+CH3Br反应,a反应通道是主反应通道,b和c反应通道在反应中有一定的贡献.     

CH3CH2+O(3P)反应机理的理论研究

利用abinitio方法对CH3CH2+O(3P)反应进行了理论研究,在MP2/6311+G(d,p)水平上优化得到了反应途径上的反应物、中间体、过渡态和产物的几何构型和谐振频率,并在QCISD(T)/6311+G(d,p)水平上进行单点能计算.计算结果表明:CH2O+CH3、CH3CHO+H和CH2CH2+OH是主要反应产物,其中CH2O+CH3主要来自反应通道A1:(R)→IM1→TS3→(A),CH3CHO+H主要来自反应通道B1:(R)→IM1→TS4→(B),CH2CH2+OH主要来自直接抽提反应通道C1和C2:(R)→TS1(TS2)→(C).计算结果同时表明该反应生成CO的通道能垒是非常高的,CO应该不是主要产物.     

钐(Ⅱ)类卡宾CH_3SmCH_2X(X=Cl、Br和Ⅰ)促进乙烯环丙烷化反应途径的理论研究(英文)

用密度泛函B3LYP方法研究了过渡金属钐类卡宾与乙烯的环丙烷化反应的机理。对三种不同的钐的SS试剂CH_3SmCH_2X(其中X=Cl、Br和Ⅰ)分别和CH_2CH_2反应的各反应物、中间体、过渡态和产物构型的全部结构几何参数进行了优化,用内禀反应坐标(IRC)计算和频率分析方法,对过渡态进行了验证。结果表明：CH_3SmCH_2X(其中X=Cl、Br和Ⅰ)与CH_2CH_2环丙烷化反应按亚甲基转移通道(通道A)和卡宾金属化通道(通道B)都可以进行,与锂类卡宾的反应机理相同,只是按亚甲基转移通道(通道A)进行反应较容易一些,而且此反应在较低的温度下就可以发生。     

SiF_2自由基与异硫氰酸反应机理的理论研究北大核心CSCD

采用密度泛函理论B3LYP方法研究了SiF2自由基与异硫氰酸(HNCS)的反应机理,并在B3LYP/6-311++G**水平上对反应物、中间体、过渡态进行了全几何参数优化,通过频率分析和内禀反应坐标(IRC)确定中间体和过渡态的真实性.为了得到更精确的能量值,又用CCSD(T)/6-311++G**方法计算了在B3LYP/6-311++G**水平优化后的各个驻点的相对能量.根据统计热力学及用Winger校正的Eyring过渡态理论,利用自编程序,计算不同温度下低势垒反应的平衡常数和速率常数,并且通过电子密度拓扑分析讨论了化学反应过程中主要化学键的生成和断裂.计算结果表明,单重态的SiF2自由基与HNCS反应有6条可能的反应通道,其中反应通道SiF2+HNCS→IM1→TS1→IM2HSiF2NCS(P1)为主反应通道.     

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。     

分子内氮原子上亲核取代反应的理论研究

在MP2(full)/631+G(d,p)理论水平上,以-CHR-(CH2)3-NFCH3(R=H,CH3,CH2CF3,CHO,COCH3)为计算模型,对分子内可能发生的两条反应路径—氮原子上的亲核取代反应及消去反应进行了理论研究.结果表明,当进攻基团-CHR为碱性较强的基团,即R=H、CH3、CH2CF3时,有利于发生消去反应而生成直链化合物R-CH2-(CH2)3N=CH2;而当R为吸电子基团-CHO、-COCH3时,主要发生分子内氮原子上的亲核取代反应,产物为含氮的五员杂环化合物.这些理论预测与已有的实验结果吻合.     

Theoretical study of the mechanism of cycloaddition reaction between dichloromethylene silylene and formaldehyde

The mechanism of cycloaddition reaction between singlet dichloromethylene silylene and formaldehyde has been investigated using a MP2/6-31G* method, including geometry optimization and vibrational analysis for the stationary points on the potential energy surface. The energies of different conformations are calculated by CCSD(T)//MP2/6-31G* method. From the potential energy profile, it can be predicted that the cycloaddition reaction between singlet dichloromethylene silylene and formaldehyde has three competitive dominant reaction channels: (1) the two reactants first form a highly strained three-membered ring intermediate INT1c, which then isomerizes to an active four-membered ring product P1 via a transition state TS1c by ring-increasing reaction; Subsequently, P1 further reacts with formaldehyde to form the more stable silapolycyclic product P2; (2) the two reactants first form a four-membered ring intermediate INT1b by the [2?+?2] cycloaddition reaction, which then isomerizes to the four-membered ring product P3.1 via a transition state TS3.1, resulting from the chlorine transfer reaction; (3) INT1b further reacts with formaldehyde to form a silapolycyclic intermediate INT4, which then isomerizes to a silapolycyclic product P₄ via a transition state TS4.     

金属-糖胺配合物的合成,光谱表征及催化酯类水解的动力学研究

合成了4种新的糖胺 金属配合物,分别为[Ni(HL) (H2 O) 2 ]2 Cl2 ·CH3OH·2H2 O ,[Cu(HL) ]2 Cl2 ·CH3CH2 OH·3H2 O ,[Zn(HL) ]2 Cl2 ·H2 O ,[Co(HL) (H2 O) (OH) ]2 Cl2 ·CH3OH·2H2 O (HLN ,N′ 二βD 葡萄糖基乙二胺) ,并用元素分析、红外、紫外、核磁共振氢谱对其结构进行了表征。结果表明,Ni(Ⅱ) ,Co(Ⅲ)配合物为八面体构型,而Cu(Ⅱ) ,Zn(Ⅱ)配合物为四面体构型。最后研究了其对对硝基苯吡啶甲酸酯(PNPP)催化水解的催化速率常数。     

Mechanistic study on Mo(CO)6‐catalyzed intramolecular [2 + 2] or [2 + 2 + 1] cycloaddition reaction of 5‐allenyl‐1‐ynes

By means of density functional theory, the Mo(CO)₆‐catalyzed intramolecular [2 + 2] or [2 + 2 + 1] cycloaddition reaction of 5‐allenyl‐1‐ynes was investigated. All the intermediates and transition states were optimized completely at B3LYP/6‐311++G(d,p) level (LANL2DZ(f) for Mo). Calculations indicate that the complexation of 5‐allenyl‐1‐ynes with Mo(CO)₆ occurred preferentially at the triple bond to give the complex M1 and then the complexation with the distal double bond of the allenes generates the complex M5 . In this reaction, Mo(CO)₆‐catalyzed intramolecular [2 + 2] cycloaddition is more favorable than [2 + 2 + 1] cycloaddition. The reaction pathway Mo(CO)₆ + R → M5 → T7 → M12 → M13 → T11 → M18 → P4 is the most favorable one, and the most dominant product predicted theoretically is P4 . The solvation effect is remarkable, and it decreases the reaction energy barriers. Copyright © 2011 John Wiley & Sons, Ltd.     

Solid state and sonochemical syntheses of nano lead(II) chloride and bromide coordination polymers from its nitrate analog via mechanochemical crystal to crystal transformations

Reversible crystal-to-crystal transformations of 3D lead(II) coordination polymers with the ligand 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene (4-bpdh), from nitrate analoge [Pb(4-bpdh)(NO₃)₂(H₂O)]_n (1) to [Pb(4-bpdh)(NO₃)(Br)]_n (2), [Pb(4-bpdh)(Br)₂]_n (3), [Pb(4-bpdh)(NO₃)(Cl)]_n (4) and [Pb(4-bpdh)(Cl)₂]_n (5) by solid state anion-replacement processes under mechanochemical reactions, have been studied. The reversible solid state structural transformations of compounds 1–5, by anion-replacement processes under mechanochemical reaction, have been verified by PXRD measurements. Nanoparticles of compounds were synthesized by sonochemical process and characterized by scanning electron microscopy (SEM), powder X-ray diffraction, IR spectroscopy and elemental analyses. The SEM images showed that morphology change occurs during solid state anion-replacements of nanocrystals.     

A theoretical study of hemiacetal formation from the reaction of methanol with derivatives of CX3CHO (X = H,F, Cl,Br and I)

A theoretical study of the hemiacetal formation reaction between methanol and CX₃CHO (X = H, F, Cl, Br, and I) has been carried out using density functional theory and Becke, three‐parameter, Lee–Yang–Parr/6‐311++G(d,p) computational methods. The stationary points of the reaction between the isolated molecules and the reaction catalyzed by an additional methanol molecule have been characterized. Because the final products present a stereogenic center, the potential autocatalysis of the reaction has been examined and also the possibility of spontaneous generation of chirality when the hemiacetal molecules are involved in the transition state structure. High barriers are found in the reaction between the isolated molecules that are reduced by the assistance of an additional molecule (methanol or hemiacetal product). The reactions catalyzed by the hemiacetal products show higher barriers than the one catalyzed by methanol. Copyright © 2012 John Wiley & Sons, Ltd.     

RRKM理论研究N(4S)+CH2X(X=F,Cl)的反应通道

采用RRKM理论和疏松过渡态模型计算了N(4S) +CH2 X(X =F ,Cl)反应的微正则速率常数和通道分支比 .计算结果表明 ,在较低的内能下 (E =2 80 .2 9kJ/mol) ,N(4S) +CH2 F的主要产物为NCHF +H ,占总产物的5 9.2 % ,次要产物为H2 CN +F ,占 37.4 % .而N(4S) +CH2 Cl反应在E =2 6 7.78kJ/mol时 ,主要产物是H2 CN +Cl,占 90 .3% ,NCHCl+H只占 9.0 % .在内能较高的时候 (取E =5 0 0 .0 0kJ/mol) ,N(4S) +CH2 F的主要通道并未变化 ,而N(4S) +CH2 Cl的主要通道变为NCHCl+H ,比例为 5 1.5 % ,H2 CN +Cl的比例降到 4 0 .4 % .