1,6-环十二二烯-2,4,8,10四炔的结构和光谱的从头算研究

用量子化学从头计算方法对１,６－环十二二烯－２,４,８,１０四炔的几何结构和光谱性质进行了研究,在优先分子构型的基础上通过等键反应分析分析和自然键轨道方法研究了它的稳定性、成键情况和共轭性。结果表明,１,６－环十二二烯－２,４,８,１０四炔是一个平面刚性分子,具有一定程度的稳定性,可能稳定存在。分子中的Ｃ≡Ｃ键与Ｃ＝Ｃ键,Ｃ≡Ｃ键与Ｃ≡Ｃ健存在一定程度的共轭,分子可能具有芳香性。     

基于二芳炔硫醚的2,6-二芳基-1,4-二噻烯的合成

描述了一种基于二芳炔硫醚(Ar—C≡C—S—C≡C—Ar)底物合成2,6-二芳基-1,4-二噻烯的方法.将二芳炔硫醚和Na2S·9H2O在C2H5OH/C2H5ONa体系中回流反应,以80%~96%的产率合成了一系列2,6-二芳基-1,4-二噻烯化合物.该方法反应条件温和、产率高并且表现出很好的选择性.反应机理涉及硫负离子对底物分子的两个C≡C键的选择性亲核加成,即硫负离子(包括S2-和中间体B硫负离子)总是选择性地加到芳基一侧的炔碳上形成1,4-二噻烯.对化合物1a进行了X线晶体结构解析.分子中的六元杂环呈"船式"构型.C(1)—C(2)和C(1A)—C(2A)具有典型的双键性质,S(1)—C(2)和S(2)—C(1)的键长数则比一般C—S单键稍短,显示硫原子上的孤对电子与C(1)=C(2)双键上的π电子存在一定程度的共轭作用.1a的晶体学参数:属正交晶系,Pnma空间群,a=10.1330(11),b=27.318(3),c=5.5402(6),α=90.00°,β=90.00°,γ=90.00°,V=1533.6(3)3,Z=4,ρcalcd=1.422 g/cm3.最终偏离因子R=0.038,Rw=0.102。     

含烯烃配体的过渡金属卡宾配合物的研究 XVIII: 异构化的螺环[4.4]-1,3-壬二烯(二羰基)[乙氧基(芳基)卡宾]铁配合物和螯合烯丙基铁配合物的合成和结构

螺环[4.4]-1,3-壬二烯三羰基铁(1)与芳基锂试剂, ArLi(Ar=C~6H~5, o-,p-CH~3C~6H~4, p-CH~3OC~6H~4, p-ClC~6H~4, p-C~6H~5C~6H~4)在乙醚中于低温下反应, 生成的酰羰基金属盐用Et~3OBF~4在水溶液中于0℃烷基化生成不稳定的异构化的螺环[4.4]-1,3-壬二烯(二羰基)[乙氧基(芳基)卡宾]铁配合物(2-7)。这些配合物与膦在石油醚中于低温下加成反应, 转变为稳定的膦加成物(8-12)。12的结构经单晶X射线结构分析进一步证实。     

含烯烃配体的过渡金属卡宾配合物的研究 XVIII: 异构化的螺环[4.4]-1,3-壬二烯(二羰基)[乙氧基(芳基)卡宾]铁配合物和螯合烯丙基铁配合物的合成和结构

螺环[4.4]-1,3-壬二烯三羰基铁(1)与芳基锂试剂, ArLi(Ar=C~6H~5, o-,p-CH~3C~6H~4, p-CH~3OC~6H~4, p-ClC~6H~4, p-C~6H~5C~6H~4)在乙醚中于低温下反应, 生成的酰羰基金属盐用Et~3OBF~4在水溶液中于0℃烷基化生成不稳定的异构化的螺环[4.4]-1,3-壬二烯(二羰基)[乙氧基(芳基)卡宾]铁配合物(2-7)。这些配合物与膦在石油醚中于低温下加成反应, 转变为稳定的膦加成物(8-12)。12的结构经单晶X射线结构分析进一步证实。     

顺, 顺-1,5-环辛二烯的单重态氧反应及其产物的重排

本文报道用竹红菌甲素作光敏剂匹配高压钠灯光源, 对1,5-环辛二烯(1)进行单重态氧氧化反应, 高产率和立体选择性地得到顺-5,8-二(氢过氧基)-1,3-环辛二烯(7). 证明了7还原产物顺-5,8-二烃基-1,3-环辛二烯(8)热重排的产物是6-羟基-4-环辛烯酮(3). 而不是6-羟基-3-环辛烯酮(6). 并讨论了热重排过程的机理.     

单茂钪催化非共轭双烯环化聚合及与乙烯共聚合的研究

以(C5Me4SiMe3)Sc(CH2C6H4NMe2-o)2和[Ph3C][B(C6F5)4]组成的单茂钪催化体系催化非共轭双烯均聚合及与乙烯共聚合,考察了聚合条件及非共轭双烯结构对聚合活性、产物分子量和微结构的影响.单茂钪催化体系中,单体浓度、聚合温度、聚合溶剂以及烷基铝试剂对1,5-己二烯的聚合活性和选择性以及聚合产物的分子量和分子量分布均有较大影响.室温甲苯溶剂中,单茂钪可以催化1,5-己二烯,1,6-庚二烯,1,7-辛二烯,1,9-癸二烯四种非共轭双烯聚合获得相应的聚合物;除1,9-癸二烯聚合获得不溶的交联聚合物外,其它非共轭双烯聚合均获得可溶的环烯烃聚合物.1,5-己二烯聚合形成亚甲基-1,3-环戊基(MCPN)五元环和四元环开环形成的3-乙烯基四亚甲基(VTM)结构单元.1,6-庚二烯聚合完全环化形成亚甲基-1,3-环己基(MCHX)六元环和乙烯基-1,2-环戊基(ECPN)五元环结构单元,1,7-辛二烯聚合形成亚甲基-1,3-环庚基(MCHP)七元环结构单元和未环化的悬挂己烯(HEB)结构单元.室温1.01×105Pa乙烯压力下,单茂钪催化体系还可以快速催化非共轭双烯1,5-己二烯,1,6-庚二烯,1,7-辛二烯,1,9-癸二烯与乙烯共聚合,获得含有环状结构单元、悬挂双键结构单元和聚乙烯嵌段的无规共聚物.在单茂钪催化非共轭双烯均聚合及与乙烯共聚合中,非共轭双烯的链长直接影响了其聚合活性和选择性.     

含烯烃配体的过渡金属卡宾配合物的研究X: 从1,5-环辛二烯三羰基铁配合物合成新奇的η^6-芳烃二羰基铁配合物

研究了以含环状非共轭双烯配体的1,5-环辛二烯三羰基铁为原料,与芳基锂反应,用Et3OBF4烷基化,以进一步研究不同环烯烃配体在卡宾配合物中的异构化行为和对反应产物的影响,用元素分析,红外光谱,核磁共振氢谱,质谱确定了八个新化合物的结构.用X-射线结构测定进一步证实了9-(η^6-芳烃二羰基铁)-9-三甲基硅氧基双环[4.2.1]壬-2-烯的分子结构.     

(η^5-C~5H~5)~3Ln.OC~4H~8(Ln=Ce,Er)的合成及晶体结构

用无水硝酸铈铵[(NH~4)~2Ce(NO~3)~6]与环戊二烯钠(C~5H~5Na)在四氢呋喃中1:6摩尔比反应, 得到(η^5-C~5H~5)~3Ce.OC~4H~8; 用ErCl~3.nTHF与环辛二烯钾(C~8H~11K)按等摩尔比于-78℃反应, 升至室温, 再按1:2摩尔比加入C~5H~5Na, 得到了(η^5-C~5H~5)~3Er.OC~4H~8。两配合物晶体结构测定结果表明都属单斜晶系P2~1/n空间群。Ce配合物与已测定过的(η^5-C~5H~5)~3Ln.OC~4H~8(Ln=La, Pr,Nd, Gd, Dy, Y, Lu)的晶体结构不是同构物; 而Er配合则是同构物。Ce配合物中的Ce-O、Ce-Cent(环戊二烯环中心)和平均Ce-C(η^5)键长不符合镧系收缩规律, 而Er配合物的键长符合。这说明在(η^5-C~5H~5)~3Ln.OC~4H~8同构系列中的Ce和Dy有两个断点, 但不存在所谓的“钆断现象”, 因为Y, Er, Lu配合物的Ln-O和Ln-C(η^5)和Ln-Centroid距离不大于Gd的相应值。     

过渡金属催化烯烃异构化的研究 Ⅵ.Cp_2TiCl_2/i-C_3H_7MgBr催化4-乙烯基环己烯异构化的研究

近年来我们用 Cp_2 TiCl_2/i-C_3 H_7 MgBr(Cp=η~5-C_5 H_5)催化体系对非共轭双烯烃的异构化进行了一系列的研究.以1,5-环辛二烯和1,5-已二烯为模型化合物的催化异构化反应结果表明,这一催化体系无论是对非共轭的环双烯还是链双烯都具有催化剂活性高,反应条件温和,产物选择性好的特点.本文用同一体系,以4-乙烯基环已烯(1)为代表,研究了     

6-取代-l,4-环辛二烯的单重态氧反应——合成顺式-5,8-和反式-5,6-二取代-1,3-环辛二烯含氧衍生物的方便途径

以竹红菌甲素作敏化剂匹配高压钠灯产生单重态氧,在甲醇溶液中,氧化6-取代-1,4-环辛二烯(1),(2),并经亚硫酸钠还原,得到顺-5,8-二取代-1,3-环辛二烯和反-5,6-二取代-1,3-环辛二烯发。化合物(3)是在三氯乙烷溶液中,未经还原得到过氧化氢基取代-1,3-环辛二烯。基态分子的稳定构象决定了反应产物的立体选择性。这类反应为用光氧化方法合成顺-5,8-二取代和反-5,6-二取代-1,3-环辛二烯含氧衍生物提供了方便的途径。     

2-丁基-四氢噻吩亚砜13C-NMR的理论研究

在RHF/6-31G和B3LYP/6-31G水平上对顺式(Cis-)与反式(Trans-)2-丁基-四氢噻吩亚砜(BTHTO)进行几何优化,应用规范不变原子轨道法(GIAO)在6-31G、6-31+G、6-31++G和6-31+G(2d,p)水平上计算了Cis-和Trans-BTHTO的13C-NMR,对13C-NMR谱进行了归属。结果表明,BTHTO噻吩五元环的稳定构象呈半椅式,Cis-和Trans-BTHTO中与硫原子直接碳原子13C-NMR的显著差异主要是由于空间构型不同引起分子的静电势场对相应碳原子的屏蔽作用不同所致。     

2,3,7,8-四氯苯并二英分子结构与热力学性质的理论研究

用密度泛函理论(DFT)和从头算(ab initio)方法,在B3LYP/6-31G、 B3LYP/6-31G*、 B3LYP/6-311G*和MP2/6-31G*水平上全优化计算了2,3,7,8-四氯苯并二英(2,3,7,8-TCDD)的几何构型、电子结构和振动频率,并用校正后的频率计算了298～1500 K的标准热力学函数,同时用半经验的PM3 SCF-MO进行了同样的计算,计算结果与实验值及文献值较好地吻合.     

Theoretical study on the hydrogen bonding of five-membered heteroaromatics with water

The hydrogen-bonding ability of five-membered heteroaromatic molecules containing one chalcogen and two heteroatoms with nitrogen in addition to chalcogen, respectively, have been analyzed using density functional and molecular orbital methods through adduct formation with water. The stabilization energies for all the adducts are established at B3LYP/6-31+G* and MP2/6-31+G* levels after correcting for the basis set superposition error by using the counterpoise method and also corrected for zero-point vibrational energies. A natural bond orbital analysis at B3LYP/6-31+G* level and natural energy decomposition analysis at HF/6-31+G* using MP2/6-31+G* geometries have been carried out to understand the nature of hydrogen-bonding interaction in monohydrated heterocyclic adducts. Nucleus-independent chemical shift have been evaluated to understand the correlation between hydrogen bond formation and aromaticity.     

Double Bond Migration Mechanism in Allyl Systems Involving the Hydroxide Ion. 2. Polarizable Continuum Model (PCM)

Isomerization processes of a double bond site in propene and methylthiopropene molecules with the hydroxide ion were studied in the framework of the RHF/6-31+G*, MP2/6-31+G*, and B3LYP/6-31+G* (density functional) ab initio methods. The solvent effect was taken into account using PCM in its IEFPCM and SCIPCM versions. It is shown that to construct a reaction profile for propene rearrangement, it suffices to perform geometry optimization of stationary points within the Born–Onsager model with further refinement of the energy using IEFPCM. The reaction profiles obtained display that the multiple bond migration mechanism involving the hydroxide ion proton is energetically preferable to the two-stage mechanism forming a solvated carbanion for the propene molecule and for the methylthiopropene molecule that forms a much more stable carbanion.     

吡啶-BH~3相互作用复合物的理论研究

对吡啶-BH~3复合物分别用MP2/6-31+G^*和B3LYP/6-31+G^*进行理论计算以预测该复合物的构型及解离能，得到四种构型，在MP2优化构型基础上作CCSD/6-31+G^*单点能量计算以验证MP2与B3LYP结果的可靠性，然后用B3LYP作振动频率分析，计算了各构型的垂直电离势，最后用更大基组作单点能量计算和自然键轨道(NBO)分析。结果表明，N-B直接相连的构型最稳定，其解离能为141.50kJ/mol,MP2和B3LYP对N-H接近的构型结果相关较大，另外两种构型稳定性介于二者之间，解离能分别为15.18kJ/mol,14.06kJ/mol(MP2/6-31+G^*)。     

Conformational space of 4,4′-methoxypropylstilbene molecule

Quantum-chemical simulation of the ground state [the density function B3LYP/6-31G, B3LYP/6-31G(d), and B3LYP/6-31+G(d,p) and the perturbation theory MP2/6-31G(d) methods] and the transition states [the B3LYP/6-31G(d) method] of 4,4′-methoxypropylstilbene molecule has been performed. Using the Ellinger MM2 force field method, the potentials of internal rotation have been obtained for each rotational degree of freedom of the molecule. The B3LYP simulation has revealed the planarity of the conjugated system and the orthogonal position of the alkyl substituent, whereas the benzene rings have deviated by about 20° with respect to the double bond plane according to the MP2 data. Three transition states of the molecule corresponding to the saddle points of the first and the second orders have been revealed. The stationary points have been identified by means of vibrational analysis.     

Structure and conformational stability of CH2CHCH2X (X=F, Cl and Br) molecules—post Hartree–Fock and density functional theory methods

The molecular structure and conformational stability of CH₂CHCH₂X (X=F, Cl and Br) molecules were studied using ab initio and density functional theory (DFT) methods. The molecular geometries of 3-fluoropropene were optimized employing BLYP and B3LYP levels of theory of DFT method implementing 6-311+G(d,p) basis set. The MP2/6-31G^*, BLYP and B3LYP levels of theory of ab initio and DFT methods were used to optimize the 3-chloropropene and 3-bromopropene molecules. The structural and physical parameters of the molecules are discussed with the available experimental values. The rotational potential energy surface of the above molecules were obtained at MP2/6-31G^* and B3LYP/6-311+G(d,p) levels of theory. The Fourier decomposition of the rotational potentials were analyzed. The HF/6-31G^* and MP2/6-31G^* levels of theory have predicted the cis conformer as the minimum energy structure for 3-fluoropropene, which is in agreement with the experimental values, whereas the BLYP/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels of theory reverses the order of conformation. The ΔE values calculated for 3-chloropropene at MP2/6-31G^*, BLYP/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels of theory show that the gauche form is more stable than the cis form, which is in agreement with the experimental value. The same levels of theory have also predicted that the gauche form is stable than cis for 3-bromopropene molecule. The maximum hardness principle has been able to predict the stable conformer of 3-fluoropropene at HF/6-31G^* level of theory, but the same level of theory reverses the conformational stability of 3-chloropropene and 3-bromopropene molecules and MP2/6-31G^* level of theory predicted the stable conformer correctly.     

异硫氰酸与甲亚胺环加成反应机理的理论研究

对异硫氰酸与甲亚胺形成四元或六元环产物的环加成反应进行了理论研究,结果表明,一分子异硫氰酸与一分子甲亚胺形成四元环(1:1)产物P1的反应(1)为经过一个两性离子中间体的分步反应,其中第二步为速控步骤,其活化热垒为107.86kJ/mol.此外,反应(1)的中间体还可与另一甲亚胺或异硫氰酸分子继续反应形成两个不同的六元环(1:2或2:1)产物P2或P3;这两个反应均为协同反应,其活化势垒分别为15.88和21.82kJ/mol.这些结果与当异硫氰酸酯与亚胺发生环加成反应时,只有类似于P2和P3的两种六元环产物生成的实验事实一致。     

5,6,9,10-四脱氢苯并环辛烯结构和性质的理论研究

在RHF/6-31G^**,MP2/6-31G^**,B3LYP/6-31G^**水平下优化了5,6,9,10-四脱氢苯并环辛烯的平衡几何构型。用B3LYP/6-31G^**方法计算了该化合物的红外光谱、拉曼光谱、核磁共振谱。计算结果与实验结果吻合很好,从而在理论上证实了它的存在。用等键反应分析,自然键轨道方法对它的稳定性和共轭性分别进行了讨论。结果表明5,6,9,10-四脱氢苯并环辛烯分子平面刚性结构,可能稳定存在,但由于苯环共轭性的削弱和较高的张力,使得它易于分解。     

Synthesis, spectroscopic characterization, and conformational properties of trichloromethanesulfenyl acetate, CCl3SOC(O)CH3

Trichloromethanesulfenyl acetate, CCl 3SOC(O)CH 3, belongs to the family of sulfenic esters. This molecule has been characterized by vibrational spectroscopy. The conformational and geometrical properties of this species have been determined by IR and Raman spectroscopy, X-ray diffraction, and quantum chemical calculations. Geometry optimizations of the most stable forms were performed with ab initio (HF, MP2) and density functional theory (B3LYP) methods. According to our data, this compound results in a gauche-syn conformer with C 1 symmetry (gauche orientation around the S-O bond and syn orientation of the CO double bond with respect to the S-O single bond) for the most stable geometry, and trans-syn conformer with C s symmetry (trans orientation around the S-O bond and syn orientation of the CO double bond with respect to the S-O single bond) for the second stable conformer (1.1 and 0.53 kcal/mol higher in energy than the most stable C 1 form according to the matrix FTIR spectroscopy and MP2/6-31G* level of the theory, respectively). The crystalline solid (monoclinic, P2 1/ n, a = 8.0152(17) A, b = 5.7922(13) A, c = 17.429(4) A, alpha = gamma = 90 degrees , beta = 100.341(3) degrees ) consists exclusively of the main form. The geometrical parameters (X-ray diffraction) are d C-Cl = 1.767(19) A, d C-S = 1.797(2) A, d S-O = 1.663(14) A, d CO = 1.189(2) A, d O-C = 1.389(3) A, d C-C = 1.483(3) A, angles Cl-C-Cl = 110.3(11) degrees , Cl-C-S = 111.8(12) degrees , C-S-O = 97.4(8) degrees , S-O-C = 116.7(11) degrees , O-CO = 122.8(19) degrees , OC-C = 127.1(2) degrees , and the main torsion angles are delta(CSOC) = 105.9(15) degrees and delta(SOC(O)) = 7.6(3) degrees . The geometrical data calculated with B3LYP/6-31G++(3df,3pd), B3LYP/6-311G++(3df,3pd), B3LYP/aug-cc-pVTZ, and MP2/6-31G* are in good agreement with diffraction data.