高能量密度化合物六硝基六氮杂三环十四烷并双氧化呋咱的理论研究

在DFT-B3LYP/6-31G**水平上，对最近新合成的高能量密度化合物六硝基六氮杂三环十四烷并双氧化呋咱（HHTTD）的分子几何，电子结构，红外振动光谱以及热力学性质进行了理论研究。根据计算结果可知，其全优化几何构型可取α, β, γ和δ四种构象，校正后的计算频率与已有实验值符合。根据分子总能量和前线轨道能隙对几种构象的稳定性进行了分析。此外，基于理论计算密度和生成热，运用Kamlet-Jacobs方程估算了标题物的爆速和爆压，结果表明标题物四种构象的爆速和爆压分别达到10 km/s和45 GPa。表明标题物可作为潜在的高能量密度材料(HEDM)，具有较高的研究开发价值和广阔的应用前景。本文为寻求新型呋咱及氧化呋咱类HEDM提供了丰富信息和指导。     

含能材料六硝基六氮杂异伍兹烷分子的B3LYP研究

在B3LYP/6-31G^**水平上对六硝基六氮杂异伍兹烷(CL-20)分子进行结构优化、集居数分析、自然键轨道和振动频率计算,得到与实验值相符的稳定构型.根据计算结果,讨论了键特性对分子性质的影响.     

双环-HMX结构和性质的理论研究

在DFT-B3LYP/6-311G*水平上, 计算研究了高能化合物四硝基四氮杂双环辛烷(双环-HMX) α和β两种异构体的结构和性质. 比较分子对称性、分子内氢键和环张力等几何参数以及分子总能量和前线轨道能级等电子结构参数, 发现α比β稳定. 分子中N—N键较长, N—N键集居数较小, 预示该键为热解和起爆的引发键. 基于简谐振动分析求得IR谱频率和强度. 运用统计热力学方法求得200～1000 K温度的热力学性质. 以非限制性半经验PM3方法探讨其热解机理, 求得各反应通道的过渡态和活化能, 发现热解始于侧链N—NO₂键的均裂. 还从理论上预测了该化合物的密度、爆速和爆压, 有助于寻求高能量密度材料(HEDM).     

几种新型六氮杂异伍兹烷衍生物结构与性能的理论预测—— 高能量密度化合物的寻求

以CN, NC, ONO2, N3, NH2, N2H, NHNH2, N4H和N4H3 9种含氮高能基团为取代基, 分别取代2,4,6,8,10,12-六氮杂异伍兹烷(IW)中亚氨基的6个H原子所形成的9种六氮杂异伍兹烷衍生物作为研究目标分子. 运用密度泛函理论, 在B3LYP/6-31G**水平上求得了它们的分子几何构型、电子结构、解离能(BDE)及IR谱等信息, 并设计等键反应计算了生成热( ). 基于统计热力学原理计算拟合了100～1200 K温度范围内体系的热力学函数, 利用Kamlet-Jacobs方程估算了它们的爆轰性能. 研究结果表明, 9种六氮杂异伍兹烷衍生物存在两种可能的热解引发类型. 在衍生物HNiIW, HBDAIW和HBAIW中, 可能的热解引发键是取代基内部的化学键, 而其余衍生物的热解引发键则可能是骨架N与取代基R之间N—R键. 另外, 硝酸酯基(ONO2)取代所得化合物HNiIW的密度ρ、爆速D及爆压p分别为1.998 g•cm－3, 9.71 km•s－1和44.47 GPa, 完全达到高能量密度化合物(HEDC)的基本要求, 且优于已应用的HNIW, 有望成为新型的HEDC.     

(+)-1R,3R,5S-1,8,8-三甲基-3-硫代-3-(4-甲基苯氧基)-2,4,3-二氮磷杂二环[3,2,1]辛烷的合成和分子绝对构型

合成的标题化合物用X射线衍射方法确定其分子的绝对构型,晶体空间群为P_(2_1 2_1 2_1),晶胞参数:a=0.8365(3)、b=0.8625(3)、c=2.3513(2)nm,Z=4.结构分析表明,分子骨架中存在3个环结构,即含磷、氮原子的船式七元环、椅式六元环以及由碳原子组成的信封式五元环。P—S键为e键,P—O键为a键。     

ε-六硝基六氮杂异伍兹烷（CL-20）热解机理的理论研究

运用量子化学中非限制性Hartree-Fock自洽场(UHF-SCF)PM3分子轨道(MO)方法,计算研究六硝基六氮杂异伍兹烷(HNIW或CL-20)的最稳定ε晶型化合物的气相热解引发反应.求得可能的四种不同热解反应通道的过渡态、活化能和位能曲线,发现其热解引发步骤为五元环上侧链N—NO2键的均裂.在过渡态附近相关原子电荷发生突变.     

一个取代的1, 5-苯并二氮杂卓的晶体结构及构象研究

用X射线衍射方法测定了4-苯甲酰基-3-(邻氯苯基)-1-乙酸乙酯基-1a-苯基-1,1a,2,3-四氢化-4H-环丙胺-[1,2-a][1,5]-苯并二氯杂卓化合物的晶体结构,晶体结构测定结果表明分子核心骨架二氮杂卓为类船式构象。用动力学模拟退火(SimulatedAnnealing)方法对分子进行了构象分析,结果表明分子中的二氮杂卓七元环具有三种较稳定的构象,其中以船式构象为最稳定,并存在着明显的芳环堆积作用。分子中七元环同时并接苯环和三元环,且环中的N(2)-C(12)-C(11)-N(1)有π键成分,大大限制了七元环构象的相互转换。     

反式和顺式含磷稠环6,13-二硫丙基-5,12-二氧-6,13-二硫羰基-6a,7,13a,14-四氮-6,13-二磷杂二苯并(a,h)蒽烷的晶体结构

采用X射线分析测定了标题化合物的晶体结构和分子结构。化合物C_(20)H_(22)-O_2N_4P_2S4(1)为反式构型,M_r=540.63,正交晶系,空间群Pcab,a=7.255(2),b=18.297(3),c=18.576(2),V=2465.9 ~3,Z=4,D_c=1.456g/cm~(-3),最终偏离因子R=0.058,R_ω=0.049;化合物(2)为顺式构型,单斜晶系,空间群Ic,a=14.649(5),b=7.009(2),c=22.694(8),β=100.60(3)°,V=2290.1 ~3,Z=4,D_c=1.643g/cm~(-3),最终偏离因子R=0.061,R_ω=0.065。晶体结构测定结果表明,这对顺反异构体的构象明显不同:反式异构体的分子本身有对称中心且与晶体学对称中心重合,氧,氮,磷杂六员环为椅式构象,磷硫单键为轴向键,磷硫双键为平伏键;顺式异构体的分子本身无对称中心,两个氧氮磷杂六员环分别为椅式和船式构象,环上的磷硫单键为平伏键,磷硫双键为轴向键,与反式异构体恰恰相反。     

一个取代的1, 5-苯并二氮杂卓的晶体结构及构象研究

用X射线衍射方法测定了4-苯甲酰基-3-(邻氯苯基)-1-乙酸乙酯基-1a-苯基-1,1a,2,3-四氢化-4H-环丙胺-[1,2-a][1,5]-苯并二氯杂卓化合物的晶体结构,晶体结构测定结果表明分子核心骨架二氮杂卓为类船式构象。用动力学模拟退火(SimulatedAnnealing)方法对分子进行了构象分析,结果表明分子中的二氮杂卓七元环具有三种较稳定的构象,其中以船式构象为最稳定,并存在着明显的芳环堆积作用。分子中七元环同时并接苯环和三元环,且环中的N(2)-C(12)-C(11)-N(1)有π键成分,大大限制了七元环构象的相互转换。     

六硝基六氮杂异伍兹烷结构和性质的理论研究

用abinitio和DFT方法,分别在HF/6-31G^*和B3LYP/6-31G^*水平下全优化计算了高能量密度材料六硝基六氮杂异伍兹烷(HNIW)的α(γ),β和ε型构象的分子几何构型、电子结构、IR谱和298～1000K温度下的热力学性质,细致分析比较了两种方法和相关的实验结果。理论计算几何参数与实验值相一致。分子中N—N键较长,N—N键Mulliken集居数较小,预示该键为热解和起爆的引发键。所得的IR谱形符合实验、指纹区频率与实验的平均绝对差值小于45cm^-1。由前线MO能级及其差值预示的热力学稳定性次序[ε＞α(γ)＞β]与实验排序相吻合。     

Preparation and properties of sterically demanding and chiral distibine ligands

A series of new rigid distibines, 1,8-bis(R(2)Sb)naphthalene (R = Me: (); R = Ph: ()), and chiral distibines, 2,2'-bis(R(2)Sb)-1,1'-binaphthyl (R = Me: (); R = Ph: () obtained as racemic mixtures) and the discrete enantiomers of 4,5-bis((R(2)Sb)methyl)-2,2-dimethyl-1,3-D/L-dioxolane (R = Me: () (l), () (d); R = Ph: () (l), () (d)) have been obtained in high yields, using either electrophilic halostibine reagents with di-lithium reagents (()-()) or nucleophilic stibide reagents with dibromo-derivatives (()-()). The distorted octahedral complexes [Mo(CO)(4)(L)], L = ()-(), planar [PtCl(2)(L)], L = (), (), (), (), and neutral, five-coordinate [RhCl(cod)(L)], L = (), (), (), are reported and trends in the spectroscopic data are discussed in terms of the ligand donor properties. Crystal structures of () and [Mo(CO)(4)()] reveal significant structural changes occur upon coordination, and these are also reflected in the solution NMR spectroscopic parameters. Changes in the C-Sb-C angles and C-Sb bond distances upon coordination of () are discussed in term of increased s/p orbital mixing. Air oxidation of () forms a very unusual stibine oxide, the structure of which shows a distorted Sb(4)O(4) cubane core (bridging O atoms) with two orthogonal naphthalene units.     

环三甲撑三硝胺(RDX)结构和性质的DFT研究

环三甲撑三硝胺(RDX)是综合性能好、使用极广的高能炸药。本文用密度泛函理论(DFT)B3LYP方法,取6-31G*基组,求得其分子几何构型、电子结构、IR谱和热力学性质。全优化几何构型和电子结构均具有C3V对称性。在相邻原子之间以NNO2键的Mulliken集居数最小,表明其间电子分布较少,预示其为热解和起爆的引发键。IR谱与实验结果良好相符。计算所得298-1200K的热力学性质,对进一步深入研究RDX的反应和性质有助。     

二氨基二硝基乙烯结构和性质的理论研究

对三种二氨基二硝基乙烯同分异构体进行了HF/6-31G^*^*水平、DFT-B3LYP/6-31G^*^*水平的几何全优化以及MP2/6-31G^*^*//HF-6-31G^*^*水平的总能量计算。结果表明,1,1-二氨基-2,2-二硝基乙烯(Ⅰ)总能量比顺式(Ⅱ)和反式(Ⅲ)1,2-二氨基-1,2-二硝基乙烯的总能量低,即热力学稳定性次序为Ⅰ>Ⅲ>Ⅱ。分子的共轭性和分子内氢键的强度次序为Ⅰ≈Ⅲ>Ⅱ,前沿轨道能级差次序为Ⅰ>Ⅱ>Ⅲ,也均表明(Ⅰ)最稳定。此外还计算研究了标题物的红外光谱;化合物Ⅰ的理论计算与实验值良好相符。在此基础上计算研究了标题物的热力学性质。     

Valency and molecular structure

Valency is defined for each molecular orbital. The molecular orbital valency values are shown to be a good measure of the bonding nature of the molecular orbital. Comparisons are made with photoelectron spectral studies and Mulliken overlap population analysis.The variation of molecular valency and molecular orbital valency with bond angle is studied. It is found that for all the molecules presently considered, energy is linearly related to valency and that the molecular valency reaches a maximum at the equilibrium bond angle. It is also shown that the molecular orbital valency can serve as a quantitatively reliable ordinate for Mulliken-Walsh diagrams.     

Modeling of hydrogen bonds in monohydrated 2,4-dithiothymine: an ab initio and AIM study

Twelve tautomers of 2,4-dithiothymine are calculated at the MP2/6-31+G(d) level, and the most stable one is referred to the di-keto form (P12). Then four H-bonded complexes between P12 and water are optimized at the MP2/6-31+G(d) level of theory. The calculation of vibrational frequencies and natural bond orbital analysis are also carried out at the same level to investigate the hydrogen bonds involved in all the systems. Within all the four complexes, three types of hydrogen bonds are formed, in which the O-H...S and N-H...O bonds are the normal bonds with the X-H bond elongation and red shift of the corresponding stretch frequencies, while the C-H...O interaction is an improper, blue-shifting hydrogen bond accompanied with the contraction of the C-H bond and a blue shift of the C-H stretch frequency. The topological properties are investigated with the atoms-in-molecules (AIM) theory. The NMR chemical shielding for the isolated and the four monohydrated 2,4-dithiothymine are calculated using the "gauge-including atomic orbital" (GIAO) method. The 1H chemical shifts are influenced by the formation of hydrogen bonds.     

Crystal Structure and Conformation of 2'-C-Ethoxy- 3',5'-O-(tetraisopropyldisiloxane-1,3-diyl)uridine

INTRODUCTION In the past few years many modified nucleosides have been synthesized primarily because of their potential antiviral and anticancer activities. For synthetic purpose, ketonucleosides are very useful intermediates[1], using the reaction of carbonyl group with Wittig reagents[2], cyanide ion[3],organometallic reagents[4] and other nucleophilic reagents[5], some nucleoside derivatives were obtained. Recently, we found some ketonucleosides could react with primary alcohol to form…     

Molecular dynamics simulation and density functional theory insight into the cocrystal explosive of hexaazaisowurtzitane/nitroguanidine

Theoretical methods involving molecular dynamics (MD) simulation and density functional theory were performed to investigate the different molecular ratios, mechanical Properties, structure, trigger bond, and intermolecular interaction of hexaazaisowurtzitane (CL‐20)/nitroguanidine (NQ) cocrystal explosive. Results of MD simulation show that CL‐20 and NQ packed in ratios of 1:1 present the larger binding energy and better mechanical properties than any other molecular ratios, which indicates 1:1 cocrystal can form the stable crystal structure. Shorter length and larger dissociation energy of trigger bond in composite structure than in isolated CL‐20 component suggests that the cocrystal may exhibit less sensitive than CL‐20. Analyses of atoms in molecules, reduced density gradient, and natural bond orbital confirm that intermolecular interactions are mainly derived from a series of weak hydrogen bond and strong vdW forces, involving of NH···O, CH···O, CH···N, O···N, and O···O. Additionally, composite structures of 2 and 3 bringing us more attractive performance will act as a key role in constructing of CL‐20/NQ cocrystal explosive. © 2015 Wiley Periodicals, Inc.     

卤化铈的化学键性质

结合Ziegler的过渡态方法和Xα-SW方法,从能量上分析了CeF₄、CeF₃、CeCl₃、CeBr₃的离子键和共价键性质。结果表明,Ce-X(X为卤素)共价键主要由Ce的5d和4f轨道与卤素构成;未成对电子基本分布在Ce的4f轨道上;在成对占据的轨道中有一定程度的Ce_4f成分,对Ce-X共价键有相当程度的贡献;CeF₃中离子键起主要作用,其它化合中离子键的程度与共价键接近。     

Chemical bond between Cu(II) and Rn: ab initio study of CuRn n 2+ (n = 1–6) by coupled cluster method

Quantum chemical calculations of the structures, stabilities, and interactions of the title series at the CCSD(T) theoretical level are performed. The analysis of binding energies, average binding energies, and fragmentation energies indicate that the n = 2 system is more stable than its neighbors. Topological analysis of the natural bond orbital, electron density deformation, integrated charge transfer, bond critical point properties, reduced density gradient analysis are performed to explore the nature of the interaction. The results show that the present Rn–Cu²⁺ interactions fall into intermediate interaction type with a pronounced covalent character.